ARTICLE | doi:10.20944/preprints202005.0406.v1
Subject: Medicine And Pharmacology, Dietetics And Nutrition Keywords: Drospirenone 4mg; breastfeeding; plasma concentration; milk concentration
Online: 24 May 2020 (20:26:11 CEST)
Objective: The primary objective of this trial was to assess the transfer of drospirenone to breast milk after daily administration of an oral test preparation containing 4 mg of drospirenone at the steady state. The secondary objective of the trial was to assess the safety of the preparation based on safety clinical and laboratory measurements (at the beginning and at the end of the trial) and reporting of adverse events and/or adverse drug reactions. Patients and Methods: This was an open label, non-comparative single center study. Drospirenone 4mg per day was the first postpartum contraceptive for the study participants who were no longer breastfeeding yet were still lactating. It was administered for 7 (seven) days to achieve steady-state concentration. All participants were volunteers who planned to use oral contraceptives as their family planning method in the future. Results: A total number of 12 volunteers completed the trial according to the protocol and the samples of all the 12 study completers were analyzed. The average concentration-time curve of drospirenone in plasma 24 h after the administration of the last dose (AUC(0-24h)) was 635.33 ng*h/mL and 120 h after the single repeat dose administration (AUC(0-120h) was 1180.57 ng*h/mL, respectively. The average Cmax was 48.64 ng/mL. The average concentration-time curve of drospirenone in milk 24 h after the administration of the last dose (AUC(0-24h)) was 134.35 ng*h/mL and 120 h after the single repeat dose administration (AUC(0-120h) was 227.17 ng*h/mL respectively. The average Cmax was 10.34 ng/mL. Conclusion: On average 18.13% of plasma drospirenone made it to breast milk and the highest concentration of drospirenone in breast milk was 17.55% of that in plasma. The total quantity of drospirenone passing to breast milk is on average 4478 ng during a 24 h period representing 0.11% of the maternal daily dose. Thus, at the recommended doses, no effects on breastfed newborns/infants are anticipated with drospirenone 4 mg.
ARTICLE | doi:10.20944/preprints202111.0445.v1
Subject: Business, Economics And Management, Economics Keywords: Skilled birth attendance; Inequality; Concentration curve; Concentration index; Oaxaca decomposition; Mauritania
Online: 24 November 2021 (08:20:28 CET)
Background: The presence of a skilled health professional at delivery is critical to reduce infant and maternal mortality. Health development plans and strategies, especially in developing countries, consider equity in access to maternal health care services as a priority. This study aimed to measure and analyze the inequality in the use of skilled births attendance services in Mauritania. The study identifies the inequality determinants and to explore its changes over the period 2007–2015. Methods: The concentration curve, concentration index, decomposition of the concentration index and Oaxaca-type decomposition technique were performed to measure socio-economics related inequalities in skilled birth attendance services utilization and identify contribution of different determinants to such inequality as well as the changes in inequality overtime using data from Mauritania Multiple Indicator Cluster Surveys (MICS) 2007, 2011 and 2015. Results: The concentration index for skilled birth attendance services utilization dropped from 0.6324 [P < 0.001] in 2007 to 0.5852 [P < 0.001] in 2015. Prenatal care, household wealth Status and urban-rural location made the biggest contributions to socio-economic related inequalities. Decomposition of the concentration index and Oaxaca-type decomposition revealed changes prenatal care, rural-urban location made positive contributions to decline in inequality. However, alternation in household wealth score, woman’s age, her education level and the number of living children pushed the equality toward deterioration. Conclusion: Clearly, the pro-rich inequality in skilled birth attendance is high in Mauritania despite a slight decrease during the study period. Policy actions on eliminating urban-rural and wealth index disparity should target increase access to skilled birth attendance. Multisectoral Policy actions is needed to improve social determinants of health and to remove health system bottlenecks including socio-economic empowerment of women and girls, enhancing availability and affordability of Reproductive and Maternal Health commodities, improving availability of obstetrical providers in rural area, promoting a better distribution and quality of health infrastructure particularly health posts and health centers, and replacing user fees by an equitable, efficient and sustainable financing scheme under an universal health coverage vision.
ARTICLE | doi:10.20944/preprints202208.0171.v2
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: combination; antimicrobial resistance; selection index; collateral sensitivity; mutant prevention concentration; minimal inhibitory concentration; fractional inhibitory concentration index; stress factor
Online: 13 September 2022 (07:53:32 CEST)
Antimicrobial resistance (AMR) has been a serious threat to human health, and combination therapy is proved to be an economic and effective strategy to fight the resistance. However, the abuse of drug combinations would conversely accelerate the spread of AMR. In our previous work, it had been concluded that the mutant selection indexes (SIs) of one agent against a specific bacterial strain are closely related to the proportions of two agents in a drug combination. To discover probable correlations, predictors and laws for further proposing feasible principles and schemes guiding the AMR-preventing practice, here three aspects were further explored. First, the power function (y=axb, a > 0) correlation between the SI (y) of one agent and the ratio value (x) of two agents in a drug combination was further established based on the mathematical and statistical analyses for those experimental data, and two rules a1 × MIC1 = a2 × MIC2 and b1 + b2 = -1 were discovered from both equations of y=a1xb1 and y=a2xb2 respectively for two agents in drug combinations. Simultaneously, it was found that one agent with larger MPC alone for drug combinations show greater potency for narrowing itself MSW and preventing the resistance. Second, a new concept as mutation-preventing selection index (MPSI) was proposed and used for evaluating the mutation-preventing potency difference of two agents in drug combinations, and the positive correlation between the MPSI and the mutant prevention concentration (MPC) or minimal inhibitory concentration (MIC) was subsequently established. Inspired by this, the significantly positive correlation, contrary to previous reports, between the MIC and the corresponding MPC of antimicrobial agents against pathogenic bacteria was established using one hundred and eighty-one of data pairs reported. These results together of above three aspects indicate that the MPCs in alone and combination are very important indexes for drug combinations to predict the mutation-preventing effects and the trajectories of collateral sensitivity, and while the MPC of an agent can be roughly calculated from its corresponding MIC. Subsequently, the former conclusion was further verified and improved by the antibiotic exposure to forty-three groups designed as different drug concentrations and various proportions. The results further proposed that the C/MPC for the agent with larger proportion in drug combinations can be considered as a predictor and is the key to judge whether the resistance and the collateral sensitivity occur to two agents. Based on these above correlations, laws, and their verification experiments, some principles were proposed, and a diagram of the mutation-preventing effects and the resistant trajectories for drug combinations with different concentrations and ratios of two agents was presented. Simultaneously, the reciprocal of MPC alone (1/MPC), proposed as the stress factors of two agents in drug combinations, together with their SI in combination, is the key to predict the mutation-preventing potency and control the trajectories of collateral sensitivity. Finally, a preliminary scheme for antimicrobial combinations preventing the AMR was further proposed for subsequent improvement research and clinic popularization, based on the above analyses and discussion. Moreover, some similar conclusions were speculated for triple or multiple drug combinations.
ARTICLE | doi:10.20944/preprints202308.0494.v1
Subject: Chemistry And Materials Science, Ceramics And Composites Keywords: hydrophilic; PLA; plasticize; ﬁber concentration
Online: 7 August 2023 (10:07:03 CEST)
One of the drawbacks of natural fibers and their composites is their inherent hydrophilic nature. The effect of moisture on mechanical properties of a composite is irrefutable. This study deals with hygroscopic characteristics of Enset-PLA composites and its effect on the mechanical properties of the composite. To do this, injection molded composite specimens of different fiber volume fraction; plasticizer ratio, fiber length, and fiber age have been considered. The specimens are exposed to distilled water and the moisture absorption was monitored on a daily base. Subsequently, the specimens are subjected to mechanical loading to determine the effect of moisture on their Strength, Stiffness and strain at break strength. Lastly, individual and joint effects of considered factors have been scrutinized using optimal design of experiment. The result from the study shows that maximum and minimum moisture uptake is noticed for 25% and 10% fiber ratio respectively. Due to moisture effect, tensile and bending strength is decreased by 11% and 5% respectively for 15% fiber volume fraction; while 16% and 13% for 25% fiber volume fraction respectively. Increasing amount of plasticizer increases moisture resistance. The result indicate that Enset-PLA composite have competitive properties and stability when exposed to moisture.
Subject: Computer Science And Mathematics, Probability And Statistics Keywords: concentration bounds; sampling without replacement
Online: 17 May 2020 (08:52:49 CEST)
We show how some concentration inequalities for sampling without replacement can be used for bounding future samples. This process can be extended to bound the sum of future samples from multiple populations, and we analyse an illustrative sample allocation problem.
ARTICLE | doi:10.20944/preprints202306.1502.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Opilia amentacea; phytochemical screening; antioxidant activity; antimicrobial activity; Minimal inhibitory concentration; Minimal bactericidal concentration
Online: 21 June 2023 (08:24:19 CEST)
Dermatoses are essentially due to infectious or free radical aggression, immunoallergic disor-ders, or can be secondary to general diseases. To investigate new antimicrobial sources against dermatoses, Opilia amentacea crude ethanol extracts and fractions were subjected to phytochemical screening and tested for antioxidant and antimicrobial activities on Gram-positive cocci, Gram negative bacilli and fungi. Phytochemical screening revealed secondary metabolites such as sterols, triterpenes, flavonoids and tannins. Leaves and stem bark of Opilia amentacea exhibited the highest total phenolic contain (65,92 ± 0,93 and 65,71 ± 0,57 mg GAE/g DW respectivily) and flavonoids (38,8 ± 1,05 and 26,81 ± 0,19mg QE/g DW respectively). Dichloromethane fractions of leaves (FDFe) and stem bark (FDET) exhibited the best antioxidant activity with FRAP values of 741,15 and 662,84 mMol AAE/g and IC50 values of ABTS of 88,40 and 36,85 µg/mL respectively. These fractions were also the most active on Gram positive bacilli while Hexane leaves (FHFe) and hexane root bark (FHER) fractions exhibited the best antifungal activity against Candida tropicalis at MIC values of 0.23 mg/mL and 0.43 mg/mL respectively. Gram-negative bacteria were particularly resistant. This study constitutes a solid scientific basis that could justify the traditional uses of Opilia amen-tacea as an antidermatosis plant.
ARTICLE | doi:10.20944/preprints202302.0211.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: FPGA; DAQ; Data concentration; Beneš network
Online: 13 February 2023 (09:10:55 CET)
The concentration of data from multiple links to a single output is an essential task performed by High-Energy Physics (HEP) Data Acquisition Systems (DAQs). At high and varying data rates combined with the large width of the concentrator’s output interface, this task is non-trivial. This paper presents a concentrator based on the Beneš network, which provides efficient concentration without using a high-frequency clock internally. It warrants that empty data are eliminated and does not disturb the data time-ordering if the data rates significantly differ between inputs. Additionally, it is well suited to FPGA implementation. It is based on simple data-routing primitives and may be fully pipelined.
ARTICLE | doi:10.20944/preprints202009.0612.v1
Subject: Business, Economics And Management, Accounting And Taxation Keywords: Water; Gini coefficient; concentration; privatization; Chile
Online: 25 September 2020 (11:58:40 CEST)
This document makes a comprehensive analysis of the inequality of the water market in Chile, measured by the Gini coefficient method. The situation of water rights in Chile is of particular interest because it is a completely privatized system, where rights are traded in the market and therefore water is presented as a commodity. This privatization of water in Chile occurred as part of the process of neoliberalization since the 1981 Water Code. The results of this study indicate that both the concentration and the inequality in the distribution of water rights is very high. It proposes a profound revision of applying a mercantile logic to a scarce basic resource for life such as water and exploring the importance of its role as a national good for public use.
ARTICLE | doi:10.20944/preprints201810.0496.v1
Subject: Medicine And Pharmacology, Gastroenterology And Hepatology Keywords: zinc, HCC, liver function, Zn concentration
Online: 22 October 2018 (12:38:25 CEST)
Background and Aim: Zinc plays a pivotal role in various zinc enzymes, resulting in the maintenance of liver function. Patients with chronic liver diseases (CLDs) usually have lower concentrations of zinc, which decrease further as liver fibrosis progresses. It remains unknown whether long-term zinc supplementation improves liver function and reduces the risk of hepatocellular carcinoma (HCC) development. Patients and Methods: Two hundred sixty-seven patients with CLDs who received a zinc preparation (Zn-group; 196 patients), or who did not receive zinc (no Zn-treatment group; 71 patients) were retrospectively analyzed in this study. The Zn-group was divided into 4 groups according to their serum Zn concentrations at 6 months after the start of Zn treatment. Results: Liver function significantly deteriorated in the no Zn-treatment group, while no notable change was observed in the Zn-group. The cumulative incidence rates of events and HCC at 3 years were lower in the Zn-group (9.5%, 7.6%) than in the no Zn-treatment group (24.9%, 19.2%) (p<0.001). According to the serum Zn concentrations, the cumulative incidence rates of events and HCC were significantly decreased in patients with Zn concentrations ≥ 70 µg/dl (p<0.001). Conclusion: Zinc supplementation appears to be effective at maintaining liver function and suppressing events and HCC development, especially among patients whose Zn concentration is greater than 70 µg/dl.
ARTICLE | doi:10.20944/preprints202309.1871.v1
Subject: Biology And Life Sciences, Other Keywords: cognitive flexibility; mood; energy; concentration; motivation; nootropics
Online: 27 September 2023 (11:52:54 CEST)
This study assessed the acute effects of oral methylliberine (DynamineTM) supplementation on cognitive function and indices of well-being. This was a double-blind, randomized, within-subject crossover trial. 25 healthy men and women (33.5±10.7yr, 172.7±8.6cm, 73.3±11.0kg) underwent pretesting before ingesting methylliberine (100mg) or placebo (PLA) for 3 days. On the fourth day participants were tested before their 4th dose (baseline) and every hour post-ingestion for 3 hours. After a one-week washout period, participants repeated testing with the alternate investigational product. The testing battery consisted of vitals, Stroop test and Trail Making Test-B, and visual analog scales that assessed various indices of well-being. Mixed factorial ANOVA with repeated measures were used to assess all variables. There were significant (p≤0.050) interactions in concentration, motivation, and mood. Methylliberine improved concentration 1- and 3-hours, motivation 3 hours, and mood 1-, 2-, and 3 hours (p≤0.050). Methylliberine improved energy, sustained energy, and mood in all participants to a greater extent than PLA at 1-hour and 3-hours relative to baseline (p≤0.050). PLA improved motivation at 1- and 2-hours and mood at 2-hours (p≤0.050). Methylliberine improved concentration, well-being, and the ability to tolerate stress to a greater extent than PLA at 3-hours relative to baseline (p≤0.050). Women observed elevations in sustained energy 1- and 3-hours (p≤0.050) in methylliberine vs. PLA. Methylliberine had negligible influence on cognitive function, vitals (p>0.050), and no adverse events were reported. Methylliberine significantly improved subjective feelings of energy, concentration, motivation, and mood, but not cognitive function. PLA improved motivation and mood at hours 1 and 2, while methylliberine sustained benefits for longer. Methylliberine also improved concentration, well-being, and the ability to tolerate stress to a greater degree than PLA while having no detrimental effects on vital signs. Methylliberine also seems to have a positive impact on sustained energy in women.
ARTICLE | doi:10.20944/preprints202309.0851.v1
Subject: Environmental And Earth Sciences, Ecology Keywords: plastic garbage; microplastics; pollution; aquatic environment; concentration
Online: 13 September 2023 (07:49:39 CEST)
Abstract. The paper presents primary material on determining the presence of micro- and macroplastics in Markakol Lake, one of the high-mountainous and unique water bodies of Kazakhstan, conditionally undisturbed, but vulnerable to anthropogenic pollution. In the course of work, micro- and macroplastics were detected in all selected samples in the water area of the lake and its main tributaries, the Urunkhaika, Topolevka, Tikhushka, Matabai, Elovka rivers. When determining micro- and macroplastics, we were guided by the method of analysis in aquatic environment, NOAA research program, developed by American scientists Masura J. et al, which is used in many countries. Concentrations and sizes of MP found in the water of the main tributaries of the rivers Urunhaika in concentrations up to 211.4 µg/m3, Tikhushka – 97.9 µg/m3, Zhirelka – 67.8 µg/m3, Topolevka – 157.2 µg/m3, Matabai – 78.3 µg/m3. Concentrations of MP in the surface water layer of the lake detected during 15 minute trawling at distances from 438 m to 841 m occur in sieve mesh sizes of 1.0 mm – 316.7 µg/m3 and 0.315 mm – 520.8 µg/m3. The total concentration of detected micro- and macroplastics coming with tributaries was – 150 µg/m3, in the lake water area – 837.4 µg/m3. The sizes of plastic debris found both in river waters and along the lake water area ranged from mesoplastic debris (fishing line net fragments, foam balls, plastic bags, plastic bottles, wrappers, food labels and packaging, etc.) to microplastic particles detected using a microscope with 40X magnification in size ranges of 25 mm, 1.0 mm and 0.315 mm. Sources of MP depend on local human activities (fishing, transportation, waste disposal etc.).
ARTICLE | doi:10.20944/preprints202305.1253.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: supercapacitor; MWCNTs; activated carbon; Na2SO4; electrolyte concentration
Online: 17 May 2023 (14:11:29 CEST)
Along with the rapid development of technology and industry, the need for energy storage has become fundamental. One promising energy storage devices is the supercapacitor. Several type supercapacitors are available, one of which is the electrical double-layer capacitor made from carbon graphite and multiwalled carbon nanotubes (MWCNTs). In this study, we combined these two materials into a working electrode in a three-electrode system. In the morphological analysis using scanning electron microscope, transmission electron microscope, and X-ray diffraction, the two materials were found to have formed a composite on the surface. In the electrochemical analysis, two types of testing were conducted using cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical analysis was carried out on five electrolyte concentrations of Na2SO4 from 1 to 6 M. The capacitance produced at concentrations of 1, 2, 3, 4, and 5 M were 34.395, 35.808, 46.284, 49.502, and 76.815 F/g, respectively. At an electrolyte concentration of 5 M Na2SO4, an energy density of 27.312 Wh/Kg and a power density of 343.786 W/Kg were produced. Meanwhile on concentration of 6 M, the surface of the electrode was damaged.
ARTICLE | doi:10.20944/preprints202112.0093.v1
Subject: Medicine And Pharmacology, Pediatrics, Perinatology And Child Health Keywords: children; face masks; school; cognitive impairment; concentration
Online: 6 December 2021 (17:31:38 CET)
In the current Sars-CoV-2 pandemic, wearing a face mask was mandatory and is still desired during school lessons. There are no controlled studies in children to date indicating an effect on cognitive performance wearing face masks. In a randomized controlled trial, we analysed the influence of face masks on cognitive performance of pupils during regular school lessons. Pupils (n=133, 5th to 7th grade) were randomized by alternating allocation into control (with masks, n=65) and intervention groups (without mask, n=68). After two school lessons with (control) and without (intervention) face masks in class all pupils performed digital tests for cognitive performance regarding attention and executive functions (Switch, CORSI block tapping, 2-back and flanker task). Overall, there were no significant differences in cognitive performance between both groups, masks vs. no masks. Wearing face masks has no significant influence on attention and executive functions of pupils and can still be recommended during school lessons.
ARTICLE | doi:10.20944/preprints202108.0299.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: contamination; trace elements; metal concentration; environmental pollution
Online: 13 August 2021 (15:07:34 CEST)
The Katangese Copperbelt area (KCA) located south-eastern of D.R. Congo presents high concentration of metal trace elements (MTE) in several soils due to a rich natural geochemical background, and intense mining activities, causing serious health issues to humans and animals. However, the lack of data on specific baseline concentrations makes it difficult to properly assess and monitor the environmental quality of soils in the region. In this study, the baseline concentration of 11 potentially toxic MTE (i.e., Mn, Zn, Cu, Co, Cr, Pb, Cd, Ti, Ni, Al, and Fe) was assessed in topsoils of the KCA, and the possible influence of land uses (croplands, forest and mining areas) was examined. Results showed the following baseline concentrations, i.e. lower and upper limits (mg.kg-1) in cropland soils : Al (18.4–162.0), Cd (0.0–0.1), Co (0.1–3.5), Cu (0.8–17.7), Cr (0.0–0.2), Fe (4.7–233.8), Mn (3.5–575.6), Ni (0.1–1.9), Pb (0.2–2.4), Zn (0.1–20.3), Ti (0.0–392.6); in forests: Al (18.8–1167.1), Cd (0.02–0.48), Co (0.20–18.1), Cu (3.6–42.7), Cr (0.1–33.7), Fe (86.4–283.3), Mn (4.9–1538.9), Ni (0.05–24.2), Pb (0.3–13.7), Zn (2.0–7.0), Ti (0.2–0.8); and in mining areas: Al (7.4–241.2), Cd (0.01–164.8), Co (0.2–211.3), Cu (2.4–5485.4), Cr (0.03–0.4), Fe (5.9–481.6), Mn (7.1–95.9), Ni (0.1–1.9), Pb (0.2–390.8), Zn (1.5–5629.3), Ti (0.1–1.3). Cu and Zn were highest in mining areas demonstrating a prevalent influence of mining activities in altering the natural background of metals concentrations in the region. By contrast, croplands and forest shared a similar trend of Al and Mn contents, suggesting a mild influence of agricultural activity. Intriguingly, higher Cu and Co contents were found in forest compared to croplands. For all the three studied land uses, no straightforward relation was found between metal concentrations and soil total acidity. This study is the first attempt to establish reference values of MTE contents in the KCA soils and thus provides valuable information for legislative purposes and for soil quality assessment.
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: polymer solution; critical micellization concentration; Zeta Potential
Online: 17 July 2020 (15:29:49 CEST)
The interaction of solution of poly (diallyldimethylammonium) chloride, PDADMAc and sodium dodecylsulfate, SDS has been studied using conductometric, densimeter and zeta potential methods. the critical micellization concentration (cmc) was determinated with conductance results and increased with the addition of PDADMAc comparing with solutions containing pure SDS. Further the degree of dissociation, and thermodynamic parameters viz. free energy of micellization, and entropy of micellization, has been evaluated. there results demonstrated that surfactant/polymer complex is governed by both electrostatic and hydrophobic interactions. The apparent molar volume, Vϕ and adiabatic compressibility, Kϕ;s have been determined for the SDS solution from density and speed sound data. the negative charge of the SDS solutions with polymer shows that these complexes probably do not contain surfactant in the form of micelles.
ARTICLE | doi:10.20944/preprints202002.0459.v1
Subject: Engineering, Energy And Fuel Technology Keywords: low concentration; gas; reactor; high-temperature oxidation
Online: 29 February 2020 (09:20:28 CET)
To achieve efficient utilization of low-concentration mine gas, reduce resource waste, and alleviate environmental pollution, high-temperature oxidation of low-concentration gas at a concentration range of 1.00% to 1.50% that is directly discharged into the atmosphere during coal mine production was oxidized to recover heat for reuse. The gas oxidation equipment was improved for the heating process, and the safety of low-concentration gas oxidation under high-temperature environment was evaluated. Experimental results showed that the reactor could provide a 1000 ℃ high-temperature oxidation environment for gas oxidation after installing high-temperature resistant ceramics. The pressure variation curves of the reactor with air and different concentrations of gas were similar. Due to the thermal expansion, the air pressure slightly increased and then returned to normal pressure. In contrast, the low-concentration gas exhibited a stable pressure response in the high-temperature environment of 1000 ℃. The outlet pressure was significantly greater than the inlet pressure, and the pressure difference between the inlet and outlet exhibited a trend to increase with the gas concentration. The explosion limit varied with the temperature and the blend with oxidation products. The ratio of measured gas pressure to air pressure after oxidation was below the explosion criterion, indicating that the measured concentration gas is still safe after the shift of explosion limit, which provides a safe concentration range for efficient use of low-concentration gas in the future.
ARTICLE | doi:10.20944/preprints201901.0211.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: particulates; wetland; concentration; meteorological factors; removal efficiency
Online: 22 January 2019 (11:06:49 CET)
Particulate matter is a severe source of atmospheric pollution in urban cities, and it has adverse effects on human health. This study was conducted during the whole year of 2016 to monitor the concentrations of PM10 and PM2.5 on the Beijing Hanshiqiao wetland and bare land in Beijing to analyze their correlations with meteorological factors and compare the removal efficiency between two land surface types. The results indicated that (1) the PM10 and PM2.5 concentrations on the bare land were higher than those on wetland as a whole, reaching the highest value both at night and dusk and the lowest value near noon. The average concentration of PM10 was higher in winter (wetland: 137.48 μg·m-3; bare land: 164.75 μg·m-3) and spring (wetland: 205.18 μg·m-3; bare land: 244.85 μg·m-3) and the concentration of PM2.5 on the wetland also reached the higher value in winter and spring with the average of 84.52 μg·m-3 and 98.98 μg·m-3, whereas, it was higher in spring and summer on the bare land; (2) concentrations of PM10 and PM2.5 were significantly positively affected by the relative humidity (P < 0.01) and negatively influenced by wind speed (P < 0.05). The relationship between PM10 and PM2.5 concentrations and temperature was found complicated: it showed a significantly negative correlation (P < 0.01) in winter and spring and was insignificant in autumn, but in summer, only the correlation between the PM10 concentration and temperature on wetland was significant (P < 0.01); (3) the removal efficiencies of PM10 and PM2.5 followed the order of spring > winter > autumn > summer on the wetland, and the removal efficiency of PM10 was greater than that of PM2.5. This study is aim to provide practical measures to improve the air quality and facilitate sustainable development in Beijing.
ARTICLE | doi:10.20944/preprints202001.0093.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: aquatic macrophytes; freshwater systems; salinity tolerance; intraspecific variation; lethal concentration; genotypic variability; ecotype; salt stress; effective concentration; growth rate
Online: 10 January 2020 (06:49:09 CET)
Increased salinity caused by saltwater intrusion or runoff from de-icing salts can severely affect freshwater vegetation and deteriorate aquatic ecosystems. These habitats can be restored with freshwater ecotypes (locally adapted populations) that tolerate above-normal salinity. Vallisneria americana is a prominent species in many freshwater ecosystems that responds differently to abiotic conditions such as substrate composition and fertility, so in this study we evaluated the effects of salt stress on 24 ecotypes of V. americana. Instant Ocean aquarium salt was used to create saline solutions [0.2 to 20.0 parts per thousand (ppt)], then plants were abruptly exposed to these solutions and maintained in these concentrations for 5 weeks before being visually assessed for quality and destructively harvested. Analysis of variance and non-linear regression were used to calculate LC50 values – the lethal concentration of salt that reduced plant biomass and quality by 50% compared to control treatment. Growth rate and visual quality varied significantly among ecotypes, and ecotypes that were most and least sensitive to salt had 50% biomass reductions at 0.47 and 9.10 ppt, respectively. All ecotypes survived 10.0 ppt salinity concentration but none survived at 20.0 ppt, which suggests the maximum salinity concentration tolerated by these ecotypes is between 15.0 and 20.0 ppt.
ARTICLE | doi:10.20944/preprints202312.0493.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: pathogens; IspE inhibitor; carboline, synthesis; minimum inhibitory concentration
Online: 7 December 2023 (16:54:59 CET)
In a recent effort to mitigate harm from human pathogens, many biosynthetic pathways are extensively evaluated for their ability to inhibit pathogen growth and determine drug targets. Among those, one of the important products/targets of such pathways is isopentenyl diphosphate, the universal precursor of isoprenoids, which are essential for the normal functioning of microorganisms. In general, two biosynthetic pathways lead to the formation of isopentenyl diphosphate: 1) the mevalonate pathway in animals and 2) the non-mevalonate or methylerythritol phosphate (MEP) in many bacteria, some protozoa, and plants. Because the MEP pathway is not found in mammalian cells, it is considered an attractive target for the development of antimicrobials against a variety of human pathogens, including Mycobacterium tuberculosis (M.tb). In the MEP pathway, 4-diphosphocytidyl-2-c-methyl-d-erythritol kinase (IspE) phosphorylates 4-diphosphocytidyl-2-C-methyl-D-erythritol (CDPME) to form 4-diphosphocytidyl-2-C-methyl-D-erythritol 2-phosphate (CDPME2P), followed by cyclization to 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MECPP) by 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase (IspF). A virtual high throughput screening was done by docking IspE protein with commercially available compounds and identified an active heterotricyclic compound. Hence, we designed, synthesized, and tested similar new heterotricyclic compounds. This study will provide the critical insight necessary for the ability to develop novel antimicrobials that target the MEP pathways in pathogens.
ARTICLE | doi:10.20944/preprints202310.0155.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Zirconia, Glass-Ceramic; Crown; Failure Load; Yttria Concentration.
Online: 3 October 2023 (14:36:51 CEST)
The objective was to compare the failure loads of glass ceramic, and polymer crowns against yttria-partially stabilized zirconia (Y-PSZ) crowns with varying yttria concentrations. Monolithic crowns of zirconia (Cercon XT, Katana UTML, BruxZir Anterior), glass ceramic (Celtra press, IPS e.max press, Lisi press), and polymeric materials (Trilor, Juvora, Pekkton) were fabricated and cemented to epoxy abutments. The total number of specimens was 135 for crowns and 135 for discs (15 specimens per material type and design). A universal testing machine was used to perform compressive loading of all crowns to failure with a steel hemisphere along the longitudinal axis of the abutments. Energy dispersive spectroscopy (EDS) was used to identify the concentration (mol% yttria-partially stabilized zirconia) for each zirconia brand. The data were analyzed using a generalized linear model and regression analysis. The results revealed significant differences (P < .05) in mean failure loads for different crown materials: Trilor (6811 ± 960 N) > Juvora (5215 ± 151 N) > Cercon (4260 ± 520 N) = BruxZir (4186 ± 269 N) = e.max (3981 ± 384 N) > Katana (3195 ± 350 N) = Lisi (3173 ± 234 N) = Pekkton (3105 ± 398 N) > Celtra (2696 ± 393 N). EDS showed that the zirconia materials contained yttria at different concentrations (BruxZir = 5Y-PSZ, Cercon = 4Y-PSZ, Katana = 3Y-PSZ). The yttria concentration had a significant effect on the failure load of the Katana (3Y-PSZ) crowns, which revealed lower failure loads than the Cercon (4Y-PSZ) and BruxZir (5Y-PSZ) crowns. New zirconia materials are provided with different yttria concentrations (3Y-, 4Y-, and 5Y-PSZ). Since a higher yttria concentration increases the translucency, clinicians should be aware that 4-5 wt% yttria-partially stabilized zirconia materials provide comparable or higher mechanical properties than e. max glass ceramic for dental application of crowns.
ARTICLE | doi:10.20944/preprints202204.0125.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Cherry; trade intensity analysis method; concentration coefficient; Turkey
Online: 13 April 2022 (10:23:16 CEST)
Trade of agricultural products has gained importance with the development of global trade. Cherries has a crucial place in Turkish agricultural exports. Fresh cherries are in the scope of this study. The aim of this study is to examine Turkey’s position and competitiveness in cherry trade. Trade Intensity Analysis Method which represents the course of trade flow among countries is used in the study. The study indicates that European countries which are Turkey’s tradition trade partner has a biggest trade share with Turkey and that share did not much change in years. By the way, Asia market especially China, became a game changer in cherry trade and Turkey should prepare itself for this situation.
ARTICLE | doi:10.20944/preprints201812.0084.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: mixture toxicity; concentration addition; pesticide; pharmaceuticals; Aliivibrio fischeri
Online: 6 December 2018 (11:08:43 CET)
This work introduced the potential synergistic toxicity of binary mixtures of pesticides and pharmaceuticals, which have been substantially detected in major river basins in South Korea. Different dose-response curve functions were employed in each experimental toxicity dataset for Aliivibrio fischeri. We tested the toxicity of 30 binary mixtures at two effect concentrations: high effect concentration [EC50] and low effect concentration [EC10] ranges. Thus, the toxicological interactions were evaluated at 60 effected concentration data points in total and based on model deviation ratios (MDRs) between predicted and observed toxicity values (e.g., three types of combined effects: synergistic (MDR > 2), additive (0.5 ≤ MDR ≤ 2), and antagonistic (MDR < 0.5)). From the 60 data points, MDRs could not be applied to 17 points, since their toxicities could not be measured. The result showed 48 %-additive (n = 20), 40 %-antagonistic (n = 17), and 12 %-synergistic (n = 6) toxicity effects from 43 binaries (excluding the 17 combinations without MDRs). In this study, EC10 ratio mixtures at a low overall effect range showed a general tendency to have more synergistic effects than the EC50 ratio mixtures at a high effect range. We also found an inversion phenomenon, which detected three binaries of the combination of synergism at low concentrations and additive antagonism at high concentrations.
ARTICLE | doi:10.20944/preprints201811.0608.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: spheroids; concentration gradient generator; drug screening; high-throughput
Online: 28 November 2018 (10:08:05 CET)
Three-dimensional (3D) cell culture is considered more clinically relevant in mimicking the structural and physiological conditions of tumors in vivo compared to two-dimensional cell cultures. In recent years, high-throughput screening (HTS) in 3D cell arrays has been extensively used for drug discovery because of its usability and applicability. Herein, we developed a microfluidic spheroid culture device (μFSCD) with a concentration gradient generator (CGG) that enabled cells to form spheroids and grow in the presence of cancer drug gradients. The device is composed of concave microwells with several serpentine micro-channels which generate a concentration gradient. Once the colon cancer cells (HCT116) formed a single spheroid (approximately 120 μm in diameter) in each microwell, spheroids were perfused in the presence of the cancer drug gradient irinotecan for 3 days. The number of spheroids, roundness, and cell viability, were inversely proportional to the drug concentration. These results suggest that the μFSCD with a CGG has the potential to become an HTS platform for screening the efficacy of cancer drugs.
COMMUNICATION | doi:10.20944/preprints201806.0057.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: gold nanoparticles; citrate reduction method; pH-effect; concentration
Online: 5 June 2018 (09:49:45 CEST)
Gold nanoparticles (AuNPs) are currently under intense investigation for biomedical and biotechnology applications, thanks to their ease in preparation, stability, biocompatibility, multiple surface functionalities and size-dependent optical properties. The most commonly used method for AuNPs synthesis in aqueous solution is the reduction of tetrachloroauric acid (HAuCl4) with trisodium citrate. We observed variations in the pH and concentration of the gold colloidal suspension synthesized under standard conditions, verifying a reduction in the reaction yield by around 46% from pH 5.3 (2.4 nM) to pH 4.7 (1.29 nM). Citrate-capped AuNPs were characterized by UV-visible spectroscopy, TEM, EDS and zeta-potential measurements, revealing a linear correlation between pH and the concentration of the generated AuNPs. This result can be attributed to the adverse effect of protons both on citrate oxidation and on citrate adsorption onto the gold surface, which is required to form the stabilization layer. Overall, this study provides insight into the effect of the pH over the synthesis performance of the method, which would be of particular interest from the point of view of large-scale manufacturing processes.
ARTICLE | doi:10.20944/preprints201711.0188.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: water concentration; fluorine doped; SPEED; tin oxide; properties
Online: 29 November 2017 (10:06:07 CET)
Influence of water concentration on the properties of fluorine-doped tin oxide (FTO) thin films was systematically studied in this work. Home made SISOM’s SPEED techniques and its chemical formulation was employed to grow the FTO on quartz substrate. Water concentration in the precursor solution was varied from 0, 0.5, 1.0 and 1.5 mol %. The structural, optical, and electrical properties of the films were studied under these deposition conditions. The results show that the properties of the films varied significantly with water concentration. Scanning electron microscopy (SEM) revealed FTO films whose grain size and uniformity increases significantly with increase in water concentration. The structure of the films was measured by X-ray diffraction (XRD) measurement. It shows polycrystalline films with (110), (101), (200), (211) and (220) orientation; the strength increases as water concentration increases. The optical transmission was determined by UV-Vis spectroscopy at 380–780 nm UV-VIS regions. The optical transmittance varies with water concentration with an average of 84%. The electrical property, measured by Hall Effect revealed n-type semiconductor. The films have the following properties: resistivity, 15 × 10-4Ω cm; carrier concentration, 18.7 × 1019 cm-3 and mobility of 21.86 cm2 V-1 s-1. The average figure of merit, φ of the FTO film is 1.25. Optimum deposition condition was established after series of experiments and was found to be 1.5% water concentration at 460oC substrate temperature. The FTO films deposited in this work could be a promising replacement to indium tin oxide (ITO) especially in dye-sensitized solar cells.
ARTICLE | doi:10.20944/preprints201708.0033.v1
Subject: Engineering, Chemical Engineering Keywords: petroleum sludge; characterization; total organic carbon; metal concentration
Online: 8 August 2017 (13:24:39 CEST)
Thermal plasma technique is becoming prominent in the treatment of variety of waste ranging from municipal solid waste, incinerator residue, hospital waste, electronics waste and industrial sludge. Application of the new treatment technology to petroleum sludge requires information on the nature and characteristics of the sludge that will be use to optimize the treatment system. In this investigation, petroleum sludge obtained from Petronas Melaka was characterized for its physical and chemical features. Proximate and ultimate analysis as well as determination of elemental composition were carried out. The sludge was found to contain high moisture (78.91%), low ash (5.06%), low volatiles (5.52%) and high fixed carbon (10.51%). The sludge has a TOC of 54.48% and HHV of 23.599MJ/kg. Despite the high moisture content, the higher heating value (HHV) is high when compared to literature values. The high value of HHV may be associated with the high fixed carbon, low ash content and high value of TOC. The apparent density of the sludge is slightly lower. Fourteen heavy metals are detected in significant quantities. Proper waste management that will safely dispose the sludge is required. The waste disposal technique should take into cognizant the possibility of leaching of heavy metals into ground water on one hand and the gasification of lighter ones on the other.
ARTICLE | doi:10.20944/preprints201703.0019.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: anodic oxidation; titanium dioxide; electrolyte concentration; sulfuric acid
Online: 2 March 2017 (18:25:55 CET)
To obtain smooth coatings of TiO2 for building a new design of Ti-6Al-4V heart valve, the anodic oxidation technique in pre-spark conditions was evaluated. TiO2 coating is necessary for its recognize biocompatibility and corrosion resistance. A required feature on surfaces in contact with blood is a low level of roughness (Ra ≤ 50 nm) that not favor the formation of blood clots. The present paper compares the coatings obtained by anodic oxidation of the Ti-6Al-4V alloy using H2SO4 at different concentrations (0.1 M to 4 M) as electrolyte and applying different voltages (from 20 V to 70 V). Color and morphological analysis of coatings are performed using optical and scanning microscopy. The crystalline phases were analyzed by glancing X-ray diffraction. By varying the applied voltage different interference colors coatings were obtained. The differences in morphologies of the coatings, due to the change in concentration, are more evident at high voltages limiting the oxidation conditions for the desired application. Anatase phase was detected from 70 V for 1 M H2SO4. An increase in the concentration of H2SO4 decreases the voltage at which the transformation of amorphous to crystalline coatings occurs, i.e. with 4 M H2SO4 the anatase phase appears at 60 V.
ARTICLE | doi:10.20944/preprints202311.1619.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Olive trees; Nitrogen fertilization; yield; leaf concentration; fruit set
Online: 28 November 2023 (01:45:24 CET)
Nitrogen is the most commonly managed mineral nutrient in olive groves because it is essential for plant growth. The precise management of N fertilization in olive cultivation is still not fully clarified, but it is now essential for providing sustainable production. A nitrogen fertilizer ex-periment with olive trees (cv. Kalinioti) was carried out over a six-year period. Seven levels of nitrogen fertilizer given as ammonium nitrate (control, 1, 2, 3, 4, 5, and 6 kg/tree) were annually applied in order to determine the effect of nitrogen on vegetative growth, fruit set, fruit weight, yield, maturation index and leaf N,P, and K concentrations. The results indicate that, under these conditions, application of up to 4 kg NH4NO3/tree significantly increased yield to 62.5 kg/tree compared to the control. The positive effect was attributed to the initial and final fruit set increases (7.63 and 3.73%, respectively). However, the weight of 100 olives (337 g) at the same fertilizer rate was considerably lower compared to the control. Higher nitrogen rates decreased yield while increasing overall shoot growth. Nitrogen fertilization did not significantly influence the oil content of olive fruit. Fruit weight, maturation index and concentration of oil reached maximum levels in the beginning of December, indicating a suitable start to olive harvesting with reduced yield losses due to unfavorable weather conditions. With increasing fertilizer levels from 0 to 6 kg NH4NO3,/tree concentration of N in olive leaves also increased from 1.23% to 2.38%. Maximum yield was achieved at a level of 6 kg NH4NO3/tree, which corresponded to 2.01% N in leaves. The results suggest that application of 3 kg NH4NO3/tree can be recommended for table olive pro-duction due to the fact that fruit weight was not decreased, while fertilization with 4 kg NH4NO3/tree was suitable for oil olives.
ARTICLE | doi:10.20944/preprints202310.2014.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: biomass; Ca concentration; seedling; emergence; roots; youngest mature leaf
Online: 31 October 2023 (07:47:40 CET)
Soil sodicity is a major constraint to seedling emergence and crop production, potentially reducing plant growth due to physical and chemical constraints. Examining responses to ion imbalances may assist in the identification of genotypes tolerant to chemical constraints in sodic soils and improve productivity. We evaluated the performance of four wheat (Triticum aestivum. L) genotypes in solutions with five sodium adsorption ratios (SARs) ranging from 0 to 60. For all four genotypes, seedling emergence and shoot dry matter (DM) decreased significantly with increasing SAR. A significant positive correlation was observed between Ca concentration in roots, as well as both root and shoot DM for all genotypes. At SAR values >20, a more tolerant genotype (EGA Gregory), had higher Ca concentrations in root tissues, while a more sensitive genotype (Baxter) exhibited Na-induced Ca deficiency. Thus, selection for genotypes that are able to accumulate Ca in roots in sodic conditions may be a useful trait for selecting genotypes tolerant of soils with high ESP values. However, for soils that restrict plant growth at ESP (SAR) values of 6-10%, it is likely that growth is restricted by physical constraints rather than by a Na-induced Ca deficiency.
ARTICLE | doi:10.20944/preprints202310.1958.v1
Subject: Engineering, Mining And Mineral Processing Keywords: bioleaching; forced aeration; airflow; low-grade ores; oxygen concentration
Online: 31 October 2023 (04:29:01 CET)
The airflow carried by artificial aeration provides oxidant O2 for microbial growth and mineral dissolution in heap bioleaching. To investigate the effect of forced aeration rate on bioleaching of low-grade copper sulfide ores, column bioleaching experiments with six columns were conducted in the aeration range of 0~150 L/h at 30~45 ℃. The results showed that when the aeration rate was higher than 95 L/h, the proportions of heap settlement and fine particles mass were much greater than that without aeration. The final total Fe concentration and bacterial cell numbers in pregnant leach solution increased with the increase of aeration rate.The final concentrations of Cu2 + in the mother liquor under aeration conditions of 60-150 L / h were 1.411, 1.432, 1.498, 1.491 and 1.583 g / L, respectively, which were higher than 1.345 g / L under non-aeration conditions. When the aeration rate was 150 L / h, the final Cu leaching rate was 80.1 %, which was 11.4 % higher than that without aeration ( 68.7 % ). Furthermore, in the early stage of leaching, copper leaching rate with 95 L/h aeration rate remained the highest. 结论Artificial aeration accelerates the bioleaching of low-grade copper sulfide ores by improving porosity structure, temperature range of bacterial activity and microbial catalyzed dissolution of targeted minerals.
ARTICLE | doi:10.20944/preprints202308.1334.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: PM2.5 concentration; feature selection; clustering algorithm; Adaboost integration model
Online: 18 August 2023 (09:49:34 CEST)
Determining accurate PM2.5 pollution concentrations and understanding their dynamic patterns is crucial for scientifically informed air pollution control strategies. Traditional reliance on linear correlation coefficients for ascertaining PM2.5 related factors only uncovers superficial relationships. Moreover, the invariance of conventional prediction models restricts their accuracy. To enhance the precision of PM2.5 concentration prediction, this study introduces a novel integrated model that leverages feature selection and a clustering algorithm. Comprising three components - feature selection, clustering, and integrated prediction, the model first employs the non-dominated sorting Genetic Algorithm (NSGA-III) to identify the most impactful features affecting PM2.5 concentration within air pollutants and meteorological factors. This step offers more valuable feature data for subsequent modules. The model then adopts a two-layer clustering method (SOM+K-means) to analyze the multifaceted irregularity within the dataset. Finally, the model establishes the Extreme Learning Machine (ELM) weak learner for each classification, integrating multiple weak learners using the Adaboost algorithm to obtain a comprehensive prediction model. Through feature correlation enhancement, data irregularity exploration, and model adaptability improvement, the proposed model significantly enhances the overall prediction performance. Data sourced from 12 Beijing-based monitoring sites in 2016 were utilized for an empirical study, and the model's results compared with five other predictive models. The outcomes demonstrate that the proposed model significantly heightens prediction accuracy, offering useful insights and potential for broadened application to multifactor correlation concentration prediction methodologies for other pollutants.
ARTICLE | doi:10.20944/preprints202306.1659.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: MicroRNA detection; biosensors; pre-concentration of exosomes; breast cancer
Online: 23 June 2023 (10:54:30 CEST)
MicroRNAs (miRNAs) within the exosomes are short non-coding RNAs that are associated with many diseases including cancers and are crucial players in regulating gene expression and regula-tion. Owing to their potential role as emerging biomarkers, efficient isolation, and quantification methods of miRNA from the exosomes in the cell’s supernatant are complicated and challenging. The quantitative PCR method is the gold standard for miRNA identification and estimation. Nucleic acid-based assays are expensive, labour-intensive, and require expertise. In this work, we demon-strated an aptamer-based magnetic separation of the exosomes, and quantification of the miRNA using a fluorescence switching assay. The fluorescence assay relies on the fluorescence of the fluorophore labelled cDNA quenched by carbon nanomaterials coated on magnetic beads (OFF state). When the target miRNA210 is introduced to the system, the cDNA detaches from the quenching surface. As a result, the fluorescence intensity increases (ON state) with increasing miRNA concentration within the dynamic range of 0-100 nM. This method can detect miR210 as low as 5 pM. This method does not exhibit any cross-reactivity with other closely related miRNAs. The method was validated by spiking miRNA with the standard RT-PCR method using SYBR green as a fluorescent probe. This method can be used for the minimally invasive detection of cancer biomarkers in breast cancer patients.
ARTICLE | doi:10.20944/preprints202305.0498.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: Black-box models; Neural networks; LSTM; oxygen concentration modeling
Online: 8 May 2023 (09:49:20 CEST)
Activated sludge process is a well known method to treat municipal and industrial waste water. In this complex process, the oxygen concentration in the reactors plays a critical role in the plant efficiency. This paper proposes the use of a Long Short-Term Memory (LSTM) network to identify an input-output model suitable for the design of an oxygen concentration controller. The model is identified from easy-accessible measures collected from a real plant. This dataset covers almost a month. The performances achieved with the proposed LSTM model are compared with the ones obtained with a standard AutoRegressive model with eXogenous input (ARX). Both models catch the oscillation and the overall behaviour (ARX ρ=0.833 , LSTM ρ=0.921), but, while the ARX model fails in reaching the correct amplitude (FIT=41.20%), the LSTM presents satisfactory performance (FIT=60.56%).
ARTICLE | doi:10.20944/preprints202305.0200.v1
Subject: Physical Sciences, Optics And Photonics Keywords: THz spectra; Contact lens; poled PVDF; water concentration; hydrogel
Online: 4 May 2023 (05:42:32 CEST)
As the most commonly used hydrogel material in contact lenses, the amount of water in a lens affects its optical properties and comfort for the wearer. Therefore, an important challenge is to determine the safety and efficacy of contact lenses by accurately and non-destructively measuring the water content in real time. In this study, we demonstrate the accurate detection of water content in hydrogel contact lenses using a high-precision ATR format in a portable terahertz time-domain spectroscopy system. The technique can resolve small variations in the dielectric constant in solution, which is difficult to achieve with traditional transmission and reflection measurement modes. Information is obtained from the interaction between the sample and the swift waves propagating along the prism surface. The swift waves can excite longitudinal modes that are not directly accessible by conventional techniques. It is worth noting that the reference wave can be measured by removing the sample without disturbing the optical path. We also enhance the plasma effect at the interface with the hydrogel by using PVDF dielectric films of different polarities. We observed that the water content and refractive index changes in the ATR mode show different response patterns for nonpoled PVDF and poled PVDF membranes. This suggests that reflection and relative phase can be accurately evaluated in the THz-ATR technique, resulting in an accurate method for determining complex dielectric constants in the reflection geometry. This will allow accurate measurement of both surface and in vivo water content in hydrogels in the future and is a potential technical route for application in bioaqueous tissue measurements.
ARTICLE | doi:10.20944/preprints202011.0144.v1
Subject: Business, Economics And Management, Finance Keywords: Poverty; Financial development; Education; Trade openness; Export product concentration
Online: 3 November 2020 (09:57:05 CET)
Numerous studies in the literature have investigated the effect of financial development on poverty, and tend to report a poverty reduction effect of financial development. The present paper considers the issue in the other way around, by examining the effect of poverty on financial development. In particular, it has investigated the financial development effect of poverty that passes through three main channels, including the education level, the level of trade openness, and the degree of export product concentration. The analysis is carried out using a sample of 97 developing countries over the period 1980-2017, and the two-step Generalized Methods of Moments (GMM). Results have shown that poverty genuinely affects financial development through these three channels. Specially, lower poverty rates induce greater financial development in countries that experience higher education levels. Similarly, a rise in poverty rates in the context of restrictive trade policies (that eventually result in lower levels of trade openness) undermines the development of the financial sector. Finally, higher poverty levels adversely affect financial development in countries that experience an increase in the level of export product concentration.
ARTICLE | doi:10.20944/preprints202007.0473.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Pregnancy; Iodine; Dietary habits; Iodine supplement, Urinary iodine concentration
Online: 21 July 2020 (03:42:20 CEST)
Background: The nutritional status of women during pregnancy can have a considerable effect on maternal and fetal health, and on perinatal outcome. The aim was to assess the changes occurring in dietary iodine intake, KI supplementation, and smoking habit, and the impact of these changes on the urinary iodine concentration (UIC) during pregnancy in a population of women in Catalonia (Spain). Methods: Between 2009-2011 an observational study including a cohort of women whose pregnancy was monitored in the publically-funded health system in a central region of Catalonia. Women received individual educational counseling imparted, a dietary questionnaire was completed, and a urine sample collected for iodine determination at each trimester visit. Results: 633 (67.9%) women answered the questionnaire at all 3 visits. The percentage of women with a desirable UIC (≥150μg/L) increased from the first to the second trimester and remained stable in the third (p<0.001). Analysis of the relationship between UIC≥150 μg/L and the women’s dietary habits showed that the percentage with UIC≥150 μg/L increased with greater consumption of milk, fresh vegetables, and fruit in the first trimester, and the same was true for iodized salt use in all three trimesters and iodine supplementation in all three. Conclusion: During pregnancy increased intake of milk, iodized salt, and iodine supplements was associated with an increase in the UIC.
ARTICLE | doi:10.20944/preprints202007.0043.v1
Subject: Engineering, Control And Systems Engineering Keywords: aerosol; amine emission; CO2 capture; absorber; particle number concentration
Online: 5 July 2020 (04:41:13 CEST)
In this study, a monoethanolamine aerosol growth model was developed to investigate the aerosol growth factor. Interactions among the internal conditions in an absorber were considered in this aerosol model. Additionally, an experiment was conducted to measure aerosol particle size, for collecting in-house validation data. Sucrose was used as the aerosol nuclei instead of sulfuric acid to prevent the corrosion of equipment used in the experiment. Experimental results showed that the outlet aerosol sizes increased to the same size regardless of the sucrose concentrations. The aerosol growth model was validated using the in-house experimental data. The aerosol growth model efficiently predicted the aerosol size. For investigating aerosol growth effects, particle number concentration was determined to be the primary factor affecting aerosol growth and amine emissions. When the particle number concentration increased, the aerosol size decreased, whereas the MEA emission increased.
ARTICLE | doi:10.20944/preprints201902.0228.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: hydrogen sensors; PdNi thin films; Wheatstone bridge; low concentration
Online: 25 February 2019 (14:34:58 CET)
MEMThe PdNi film hydrogen sensors with Wheatstone bridge structure were designed and fabricated by the micro-electro-mechanical system (MEMS) technology. The integrated sensors consisted of four PdNi alloy film resistors. The interval two of them were shielded with silicon nitride film and used as reference resistance, while the others were used for hydrogen sensing. The PdNi alloy films and SiN films were deposited by magnetron sputtering. The morphology and microstructure of the PdNi films were characterized with X-ray diffraction (XRD). The output resistance signal was converted to millivolt output voltage signal for easy data acquisition. Hydrogen (H2) sensing properties of PdNi film hydrogen sensor with Wheatstone bridge structure was investigated under different temperatures (30℃, 50℃ and 70℃) and H2 concentrations (from 10 ppm to 0.4%). The hydrogen sensor demonstrated good response at different hydrogen concentrations and high repeatability in cycle testing under 0.4% H2 concentration. Under 10ppm hydrogen, the PdNi film hydrogen sensor had evident and collectable output voltage of 600 μV.
ARTICLE | doi:10.20944/preprints202310.1324.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: feature selection; milk mid-infrared spectra; fatty acids concentration; regression
Online: 20 October 2023 (10:15:41 CEST)
Milk MIR spectra have been shown to provide valuable information on a wide range of traits to be used in dairy cattle breeding programs. Selecting the most informative variables from complex data can improve prediction accuracy and model robustness and, consequently, the interpretability of MIR spectra. Thus, we aimed to investigate the prediction performance of feature selection methods based on MIR spectra data, using the milk fatty acid (FA) profile as an example to illustrate the evaluated procedure. Data of MIR spectra, milk test-day records, and reference FA concentrations of 155 first-parity Holstein cows were used in the analyses. Four models comprising different explanatory variables and five feature selection methods were evaluated. The results indicated that the Competitive Adaptive Reweighted Sampling (CARS) method can effectively select the most informative variables from the MIR spectra, resulting in higher prediction accuracies than other variable selection approaches. The model including selected MIR spectra and cow information variables [days in milk at the test day, age at the test day, pregnancy stage (in days), number of days open, number of inseminations, and somatic cell count] yielded the best FA profile predictions based on Partial Least Square regression. In particular, ten FAs (C8:0, C10:0, C14:1, C17:0 isomers, C18:1, C18:1 isomer, medium-chain FA, unsaturation FA, monounsaturated FA, and polyunsaturated FA) presented accuracies based on the determination coefficient (R2cv) ranging from 0.66 to 0.85 in internal validation and from 0.65 to 0.84 in external validation. By running CARS 1,000 times in internal validations, we obtained the frequency of selected milk MIR wavenumber for 35 FAs. The most related wavenumbers to FAs were found within 1,003 to 1,145 cm-1, while other discrete areas were between 1,651 to 1,797 and 2,834 to 2,954 cm-1. These biomarkers may give insights into the relationship between MIR spectra and FA phenotypes. In conclusion, using CARS and cow information improved predictions of FAs based on MIR spectra in Chinese Holstein dairy cows. Additional validation studies should be conducted as larger datasets become available.
ARTICLE | doi:10.20944/preprints202309.1123.v1
Subject: Computer Science And Mathematics, Computational Mathematics Keywords: finite difference method; convergence; advection-diffusion-reaction equation; pollutant concentration
Online: 18 September 2023 (08:52:19 CEST)
In this paper, we analyze the convergence of a finite difference method with the implicit forward time central space (FTCS) scheme for solving the three-dimensional advection-diffusion-reaction equation (ADRE). It is proved that the method is unconditionally convergent. We apply the scheme to obtain numerical solutions for the transport of pollutants in street tunnel problems with various reaction coefficients and various rates of change of concentrations of sources or sinks of pollution.
ARTICLE | doi:10.20944/preprints202305.0782.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: Hyperspectral IR Sounding, Methane, CH4 Concentration, AIRS, CrIS, CH4 Trends
Online: 11 May 2023 (04:26:45 CEST)
Methane (CH4) is the second most significant contributor to climate change after carbon dioxide (CO2), accounting for approximately 20% of the contributions from all the well-mixed greenhouse gases. Understanding the spatiotemporal distributions, and the relevant long-term trends are crucial to identifying the sources, sinks, and impacts on climate. Hyperspectral thermal infrared (TIR) sounders, including the Atmospheric Infrared Sounder (AIRS), the Cross-track Infrared Sounder (CrIS), and the Infrared Atmospheric Sounding Interferometer (IASI), have been used to measure global CH4 concentrations since 2002. This study analyzed nearly twenty years of data from AIRS and CrIS and confirmed a significant increase in CH4 concentrations in the mid-upper troposphere (around 400 hPa) from 2003 to 2020, with a total increase of approximately 85 ppb, representing a +4.8% increase in 18 years. The rate of increase was derived using global satellite TIR measurements is consistent with in-situ measurements, indicating a steady increase starting in 2007 and became stronger in 2014. The study also compared CH4 concentrations derived from the AIRS and CrIS against ground-based measurements from NOAA Global Monitoring Laboratory (GML) and found phase shifts in the seasonal cycles in the middle to high latitudes in the northern hemisphere, which is attributed to the influence of stratospheric CH4 that varies at different latitudes. These findings provide insights into the global budget of atmospheric composition and the understanding of satellite measurement sensitivity of CH4.
ARTICLE | doi:10.20944/preprints202304.1224.v1
Subject: Biology And Life Sciences, Forestry Keywords: Optimum calcium concentration; growth; photosynthesis; water use efficiency; stress resistance
Online: 29 April 2023 (07:44:57 CEST)
Ca2+ is a crucial second messenger in plant cells, playing a vital role in various physiological and biochemical processes, including plant growth and development, photosynthesis, and enzyme regulation. Exogenous calcium concentration can have different effects on plant growth. This study aimed to investigate the optimal calcium concentration for the growth of four tree species, namely Pinus tabuliformis, Pinus sylvestris var. mongolica, Populus, and Morus alba seedlings, and whether the optimal calcium concentration varies among different tree species. The study utilized five calcium concentration gradients (0, 100, 200, 400, 800 mg·kg-1) for each species with three repeated treatments. Various growth indexes, photosynthetic parameters, chlorophyll fluorescence parameters, water use efficiency, and antioxidant enzyme activities were assessed to determine each species' calcium concentration requirements. The results showed that exogenous calcium significantly affected the growth and development of each seedling. The growth, biomass, photosynthetic parameters, photosynthetic products, photosynthetic pigments, water use efficiency, and antioxidant enzyme activity all increased initially and then decreased with increasing calcium concentration. Leaf calcium concentration also increased with the exogenous calcium content. Thus, there is an optimal calcium concentration for plant growth, and high or low calcium concentration is not conducive to plant growth. Furthermore, the study found that different tree species have varying optimal calcium concentrations. The optimal calcium concentration for Pinus tabuliformis, Pinus sylvestris var. mongolica, Populus, and Morus alba seedlings was 100, 100, 200, and 400 mg·kg-1, respectively. Finally, the study revealed that broadleaf species require higher calcium concentrations than coniferous species.
ARTICLE | doi:10.20944/preprints202206.0265.v1
Subject: Social Sciences, Political Science Keywords: COVID-19 prevention; vulnerability index; inequality; concentration index; South Africa
Online: 20 June 2022 (09:56:12 CEST)
To contain and mitigate the coronavirus (COVID-19) pandemic, African governments have implemented non-pharmacological interventions (NPIs), such as imposing travel bans, confining people to their homes and closing schools, shops and workplaces. These NPIs are likely to be less effective in circumstances where people need to leave their homes to work, collect food, water and cooking fuel or where people cannot maintain distancing due to overcrowded living environments. Using data from the nationally representative South African General Household Survey 2019, we examined individuals’ vulnerability to the risk of COVID-19 infection due to their health, socioeconomic and living circumstances. We explored socioeconomic-related inequalities in COVID-19 using concentration curve and concentration index methods. Our results showed that vulnerability to COVID-19 was disproportionately concentrated among those with low socioeconomic status. Using the Recentered Influence Function decomposition approach, we found that higher income and education had a significant and positive impact on reducing socioeconomic-related COVID-19 vulnerability. Conversely, people with lower socioeconomic status were more likely to live in circumstances that made compliance with NPI requirements almost impossible, and they were also more likely to have pre-existing health conditions that made them more vulnerable to COVID-19.
ARTICLE | doi:10.20944/preprints202201.0388.v1
Subject: Medicine And Pharmacology, Emergency Medicine Keywords: ambient air pollution; case-crossover; cluster; concentration; counts; strata; urban
Online: 25 January 2022 (17:16:48 CET)
This study examines the relation between ambient air pollution and emergency department (ED) visits due to certain infectious diseases in Toronto, Canada. The National Ambulatory Care Reporting System database was used to draw the corresponding health cases. Daily data on ED visits, ambient air pollution concentration levels, and weather conditions during the period from April 2004 to December 2015 (4,292 days in total) were linked together and used in statistical models. Six air pollutants (fine particulate matter PM2.5, CO, NO2, SO2, ozone O3 as a daily average, and ozone O3-8 hour ozone, as a maximum eight hour average) were investigated. In addition, the Air Quality Health Index (combining NO2, O3, and PM2.5) was also considered. The time-stratified case-crossover technique was applied in the study design. Conditional Poisson models were created using the daily counts of ED visit data. The considered factors, air pollutants and weather, were lagged by the same number of days, from 0 to 14. In the period of the study 339,644 ED visits were identified; 177,619 for females and 162,025 for males. For each air pollutant 270 models were realized (15 lags x 18 strata). Ambient air pollution concentrations lagged by 2, 3, and 5 days have the highest impact on ED visits, with 34, 32, and 35 positive associations, respectively. For all patients and an increase in a one interquartile range (IQR=1.2 ppb) of sulphur dioxide, the following values of the relative risks (RR) were estimated: RR=1.005 (95% confidence interval: 0.998, 1.013), 1.008 (1.001, 1.016), 1.009 (1.001, 1.016), 1.011 (1.004, 1.019), 1.007 (0.987, 1.028), and 1.009 (1.002, 1.016) for lags from 0 to 5, respectively. The results suggest that exposures for certain air pollutants (mainly CO, O3, and SO2) in urban environment affect the number of ED visits related to infectious diseases.
ARTICLE | doi:10.20944/preprints202107.0035.v1
Subject: Engineering, Automotive Engineering Keywords: centrifugal pump; impeller; erosion; particle track; particle concentration; flow rate
Online: 1 July 2021 (15:09:10 CEST)
Double suction centrifugal pump installed along the Yellow River faces the serious sediment erosion due to the high sediment content which cause the poor operation efficiency of pump unit. The particle motion characteristics and erosion characteristics in the pump under different flow rates and different particle concentrations were numerically simulated based on the particle track model of solid-liquid two-phase flow. The results show that the flow rate has a significant effect on the particle tracks and the erosion caused by the particles in the impeller. The total erosion rate is positively correlated with the flow rate, and increases with the increase of flow rate. The vortex and secondary flow in the impeller have obvious influence on the particle trajectory, which increases the particle concentration at the trailing edge of the pressure surface and intensifies the impact erosion in this area. The particles carried by the vortex intensifies the local erosion. The particle concentration mainly affects the erosion rate, but has little effect on the erosion position. The in-fluence of flow rate on the pump erosion is greater than that of the particle properties. These results provide a reference for optimization of the design of anti-erosion blades of the double-suction pump and regulation-operation of pumping station.
ARTICLE | doi:10.20944/preprints202012.0042.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Fresh cassava root; Pellet product; Rumen fermentation; Cyanide concentration; Sulfur
Online: 1 December 2020 (18:22:42 CET)
The current work aimed to screen the ruminal cyanide-utilizing bacteria and evaluate the influence of fresh cassava root (FCR) and pellets containing high sulfur (PELFUR) on cyanide content, kinetics of gas, in vitro degradability, and ruminal fermentation. The experiment was conducted in a Completely randomized design (CRD) for a screening of cyanide-utilizing bacteria and the dietary treatments were the level of cyanide at 0, 150, 300, and 450 ppm. A 5 × 3 factorial arrangement in a Completely randomized design was used for in vitro study. Factor A was the level of FCR at 0, 260, 350, 440, and 530 g/kg of 0.5 g dry matter (DM) substrate, and factor B was the level of PELFUR at 0, 15, and 30 g/kg DM substrate. Adding different doses of cyanide significantly affected cyanide-utilizing rumen bacterial growth (p < 0.05). Increasing the concentration of cyanide from 0 to 150 and 150 to 300 ppm, resulted in an increase in cyanide-utilizing rumen bacteria of 38.2% and 15.0%, respectively. Increasing the FCR level to more than 260 g/kg of 0.5 g substrate could increase cumulative gas production (p < 0.05), whereas increasing doses of PELFUR from 15 to 30 g/kg increased the cumulative gas production when compared with that of 0 g/kg PELFUR (p < 0.05). Cyanide concentration in rumen fluid decreased with PELFUR (p < 0.05) supplementation. Degradability of in vitro dry matter and organic matter following incubation increased at 12 and 24 h due to PELFUR supplementation with FCR and increased additionally with 15 g/kg PELFUR (p < 0.05) in 440 g/kg FCR. Proportions of the total volatile fatty acids, acetic acid (C2), propionic acid (C3), and butyric acid, as well as the ratio of C2 to C3 among supplementations with FCR (p < 0.05) were significantly different. As the proportion of FCR increased to 530 g/kg of the substrate, the volume of C3 increased by 14.6%. This is the first finding of bacteria in the rumen capable of utilizing cyanide, and cyanide might function as a nitrogen source for bacterial cell synthesis. Inclusion of FCR of 530 g/kg with 30 g/kg PELFUR could increase the cumulative gas production, the bacterial population, the in vitro degradability, the proportion of C3, and the rate of the disappearance of cyanide.
ARTICLE | doi:10.20944/preprints202309.2013.v1
Subject: Biology And Life Sciences, Neuroscience And Neurology Keywords: Drosophila melanogaster; cocaine; methamphetamine; neurotransmitter concentration; locomotor sensitization; LC-MS/MS
Online: 29 September 2023 (04:30:31 CEST)
Due to similarities in genetics, cellular response, and behavior, Drosophila is used as a model organism in addiction research. A well described behavioral response examined in flies is the induced increase in locomotor activity after a single dose of volatilized cocaine (vCOC) and volatilized methamphetamine (vMETH) known as sensitivity, and the escalation of the locomotor response after the repeated dose, known as the locomotor sensitization. However, knowledge about how vCOC and vMETH affect different neurotransmitter systems over time is scarce. We used LC-MS/MS to systematically examine changes in the concentration of neurotransmitters, metabolites and non-metabolized COC and METH in the whole head homogenates of male flies one to seven hours after single and double vCOC or vMETH administrations. vMETH leads to complex changes in the levels of examined substances over time, while vCOC strongly and briefly increases concentrations of dopamine, tyramine and octopamine followed by a delayed degradation into N-acetyl dopamine and N-acetyl tyramine. The first exposure to psychostimulants leads to significant and dynamic changes in the concentrations relative to the second administration when they are more stable over several hours. Further investigations are needed to understand neurochemical and molecular changes post-psychostimulant administration.
ARTICLE | doi:10.20944/preprints202307.1568.v1
Subject: Environmental And Earth Sciences, Geography Keywords: runoff; sediment; sediment concentration; sediment inflow coefficient; variation; reservoir; Jinsha River
Online: 25 July 2023 (04:17:45 CEST)
For the purpose of clean energy hydropower development, the construction of reservoirs has been continuously promoted in the Jinsha River basin for many years, and how the reservoirs affect the water and sediment process is a very necessary topic to study. This study is based on the gauged water and sediment data (span from the 1960’s to 2020) at Shigu, Panzhihua, and Xiangjiaba stations downstream located in the trunk channel of the river, and uses Mann-Kendall trend test method and double cumulative curve method to comprehensively judge the variation trends of runoff and suspended sediment load and reveal their credible mutation years. The linear regression method is used to reveal the variation characteristics of the relationship between water and sediment before and after the abrupt change years. The results show that the variations in runoff at Shigu and Panzhihua stations have significant and relatively obvious increasing trends, respectively, and that at Panzhihua station has a mutation year of 1985. The runoff at Xiangjiaba Station slightly increased but not significantly. The variation of suspended sediment load showed a temporal and spatial differentiation. The variation of sediment discharge at Shigu Station showed an increasing trend with a mutation year of 1997. For Panzhihua Station, it showed an increasing trend before 1998, but has significantly decreased since 1998. The fluctuation of sediment transport at Xiangjiaba Station was significant before 1998, but the trend is unclear. In the period of 1998−2020, it showed a significant decreasing trend, especially since 2013, when the mean annual suspended sediment load only accounted for 0.61% of its multi-year average. The variations of mean annual sediment concentration and sediment inflow coefficient at the hydrological stations is consistent with the variation trend of sediment transport. Before 2013, the correlation between water and sediment was strong, but thereafter it was extremely weak. The two sudden years of 1998 and 2013 are consistent with the year when large reservoirs were built in the river basin. The construction of large reservoirs and their large amount of sediment retention are the key reasons for the sudden changes in the water-sediment relationship and the sharp decrease in sediment transport in the downstream reach of the reservoir dam. The climate and underlying surface changes in the study area are not significant, and their impact on the water and sediment processes in the watershed is limited.
ARTICLE | doi:10.20944/preprints202306.1316.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: Concentration Characteristics; Health Risk Assessment; Heavy Metals; Nandong; Underground River Watershed
Online: 19 June 2023 (07:46:53 CEST)
Wastes from social economic activities had great impact on water quality thereby limiting water usability for domestic purposes. Sewages discharge from people activities, usually consist of undesirable concentrations of soluble chemicals that infiltrate into the surrounding surface and underground water, and then constitute health risk to the populace. In order to investigate the concentration characteristics and health risk for the local residents in Nandong Underground River Watershed (NURW), eleven common heavy metals in the water body analysis were conducted. Health risk assessment (HRA) was taken to analyze eleven heavy metals of 84 water samples from surface and underground waters in NURW: 36 samples underground water and 48 samples surface water. Our results showed that the heavy metals concentration order is that of Fe > Al > Mn > Zn > As > Cd > Pb > Cr > Ni > Cu > Hg. Correlation analysis indicates that these eleven metal elements have certain similarity on material source and migration transformation. The health risks for local residents exposed to metal elements in the water of NURW mainly from carcinogenic risk (10−6～10−4 a−1) through drinking way, and the health risk of heavy metals exposed to children through drinking way was much higher than adults. The maximum exposing health risks of Cr in both underground and surface water were higher than the recommendation standard (5.0×10-5 a-1) from ICRP, and all the values over the standard (5.0×10-6 a-1) recommended by the Swedish Environmental Protection Agency and the Dutch Ministry of Construction and Environment and the British Royal Society. The results of health risk assessment shows that Cr in the water of NURW was the mainly source of carcinogenic risk for the local residents, following by Cd and As. Consequently, it is necessary to control the three carcinogenic metals when the water was used as drinking water source.
ARTICLE | doi:10.20944/preprints202106.0054.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: monitoring of methane concentration; ventilation of mines; measurements of ventilation parameters
Online: 2 June 2021 (08:45:36 CEST)
The data from the extended system was recorded on-going basis in the archives of the monitoring system, and the multipoint system was directly stored in the methane-anemometers, which allows one to perform a comparative analysis of the obtained records from many methane detectors. An important element of the analyses was the simultaneous registration of the methane concentration in the longwall, together with information on operating time, direction of shearer operation and type of work: mining/cleaning. Mining practice shows that in methane coal mines, methane is often the basic limitation for modern and high-efficiency longwall complexes. The paper reports on selected observations and tests carried out in the Cw-4 longwall in seam 364/2 of the Budryk mine belonging to JSW SA. In observation of the methane level in the Cw-4 longwall, additional sensors installed in the end part of the longwall from the side of the gobs and registration of air velocity and methane concentration in the multipoint system built in the selected longwall cross-section were used, regardless of the air parameters recorded in the monitoring system.
ARTICLE | doi:10.20944/preprints202101.0555.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: composite polymers; magnetoactive elastomers; dynamic and mechanical properties; concentration; anisotropy; fineness
Online: 27 January 2021 (11:50:59 CET)
The paper describes the research findings on dynamic and mechanical properties of composite elastomers with high permeability magnetic filling agent capable of rapidly and reversibly changing its properties when exposed to an external magnetic field, which makes it a perspective material for application in a wide range of engineering areas. The research has analyzed the trends in the strength properties of the materials obtained through the use of filling agents of different fineness, content, and structural organization in the final polymer, under different conditions. This allowed to obtain the correlations between the influence of the filler's relative fineness on the dynamic and mechanical properties of composite polymers, and to estimate the trends in the parameters describing the material strength under the complex magnetic and thermal influence. The results obtained by the authors allowed to ground the composition and structural organization of the final material with the best set of dynamic and mechanical properties.
ARTICLE | doi:10.3390/sci2040077
Subject: Environmental And Earth Sciences, Environmental Science Keywords: temperature; global warming; greenhouse gases; atmospheric CO2 concentration
Online: 20 October 2020 (00:00:00 CEST)
It is common knowledge that increasing CO2 concentration plays a major role in enhancement of the greenhouse effect and contributes to global warming. The purpose of this study is to complement the conventional and established theory that increased CO2 concentration due to human emissions causes an increase of temperature, by considering the reverse causality. Since increased temperature causes an increase in CO2 concentration, the relationship of atmospheric CO2 and temperature may qualify as belonging to the category of “hen-or-egg” problems, where it is not always clear which of two interrelated events is the cause and which the effect. We examine the relationship of global temperature and atmospheric carbon dioxide concentration at the monthly time step, covering the time interval 1980–2019, in which reliable instrumental measurements are available. While both causality directions exist, the results of our study support the hypothesis that the dominant direction is
T → CO2. Changes in CO2 follow changes in T by about six months on a monthly scale, or about one year on an annual scale. We attempt to interpret this mechanism by involving biochemical reactions, as at higher temperatures soil respiration, and hence CO2 emission, are increasing.
Subject: Business, Economics And Management, Accounting And Taxation Keywords: Financial Constraints; Agency Cost; Equity Concentration; Holding Heterogeneity; Real Estate Industry
Online: 19 October 2020 (14:32:53 CEST)
Real estate industry is related to the national economy and people's livelihood，characterized by a high degree of financial intensity. The enterprises in this industry need certain financial ability and large shareholder controlling ability to support their survival. However，due to the multiple adverse impacts of current state policies，banks and private capital，the credit crunch，the sudden decrease in withdrawn funds and the limitation of internal financing，the problem of capital restraint of real estate enterprises has become more and more serious. From the perspective of corporate governance，this paper studies the interaction among financial constraints，ownership concentration and corporate performance under different shareholding states by analyzing the quantitative characteristics of equity structure，and looks for the appropriate range of the largest shareholder holding ratio，which has considered the financial performance and risk. It is found that raising the ownership concentration can effectively ease the financing constraints and improve the performance of enterprises，both of which are significant under the state of high ownership concentration， while the financial constraints play a significant intermediary effect under the State of absolute holding， while in the decentralized state of ownership，there is a significant regulatory effect，and the interaction of the three will be different due to the size of the enterprise.
ARTICLE | doi:10.20944/preprints201901.0202.v2
Subject: Computer Science And Mathematics, Probability And Statistics Keywords: Concentration Inequality, Empirical Bernstein Bound, Stratified Random Sampling, Shapley Value Approximation
Online: 31 May 2019 (10:37:48 CEST)
We derive a concentration inequality for the uncertainty in the mean computed by stratified random sampling, and provide an online sampling method based on this inequality. Our concentration inequality is versatile and considers a range of factors including: the data ranges, weights, sizes of the strata, the number of samples taken, the estimated sample variances, and whether strata are sampled with or without replacement. Sequentially choosing samples to minimize this inequality leads to a online method for choosing samples from a stratified population. We evaluate and compare the effectiveness of our method against others for synthetic data sets, and also in approximating the Shapley value of cooperative games. Results show that our method is competitive with the performance of Neyman sampling with perfect variance information, even without having prior information on strata variances. We also provide a multidimensional extension of our inequality and discuss future applications.
ARTICLE | doi:10.20944/preprints201901.0269.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: volume ratio; adsorbed water layer; stationary phase; salt concentration; column temperature
Online: 28 January 2019 (08:31:15 CET)
The water-rich liquid layer immobilized on the surface of the polar stationary phases is critical to the retention of polar compounds in hydrophilic interaction chromatography (HILIC). Although the presence of the adsorbed water layer has been investigated and confirmed by multiple techniques, there is a lack of quantitative measure that can be easily determined and linked to chromatographic parameters. This study proposes a simple measure termed volume ratio (the ratio of the adsorbed water layer volume and the mobile phase volume) that provides a relative, but quantitative information on the adsorbed water layer and may be linked to the phase ratio. The volume ratio can be easily determined using toluene elution volume. The volume ratio values are measured in 25 polar stationary phases in various mobile phase conditions. In addition to the acetonitrile content in the mobile phase, ammonium acetate concentration in the mobile phase and column temperature also have significant influences on the volume ratio and the adsorbed water layer.
REVIEW | doi:10.20944/preprints201805.0086.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: water quality; soil structure; threshold electrolyte concentration; zero point of dispersion
Online: 4 May 2018 (07:53:35 CEST)
The sustainability of irrigated agriculture depends on the quality of irrigation water used. The electrolyte concentration (EC) of irrigation water may lead to the accumulation of salts in the root zone layers and affect the physiological functions of the crop by osmotic and ion toxicity effects. Further, the cationic and anionic composition of the water may alter the exchangeable cation composition of the soil and as well as its pH. Because of the dominance of sodium salts in many sources of irrigation water, parameters related to sodium such as exchangeable sodium percentage (ESP) of soils and sodium adsorption ratio (SAR) of soil solutions have been commonly used to study the effects of sodium in irrigation water on soil structural stability. Quirk and Schofield concept of ‘threshold electrolyte concentration’ (TEC) has shown the importance of electrolytes in preventing the effects of sodium on soil structure. Based on this concept, several models have been proposed to relate ESP or SAR with EC to predict the possible impacts of irrigation water on soil structural stability. However, many research reports indicate that this relationship varies with soils and a given model is not suitable for all types of soils. Further, the effects of potassium and magnesium in the processes leading to clay dispersion are disregarded in these models. This essay analyses all the factors involved in the structural failure of soils with different cationic composition, identify the defects in these TEC models and re-defines TEC on the basis of new insights on dispersive and flocculating charges of soils. This review does not deal with EC effects on crops and also the role of contaminant ions not involved with soil structural stability.
ARTICLE | doi:10.20944/preprints201609.0072.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: Pb-acid batteries, electrolyte additives, battery energy capacity, electrolyte additive concentration
Online: 20 September 2016 (15:39:49 CEST)
The paper presents a method to assess the effect of electrolyte additives on the energy capacity of Pb-acid batteries. The method applies to any chemically unreactive additive, including suspensions and gels. The approach is thermodynamically based and it leads to the definition of a region of admissible concentrations –the battery’s admissible range– where the battery can undergo an indefinite number of charge/discharge cycles without suffering permanent damage. An experimental procedure to determine this range is presented. The obtained results provide a way to assess the potential of electrolyte additives to improve the energy capacity of Pb-acid batteries. The same results also provide a means to determine the additive concentration that produces the maximum energy capacity increase of the battery. The paper closes with an example of application of the proposed approach to a practical case.
ARTICLE | doi:10.20944/preprints202311.1452.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: quantitative analysis; X-ray fluorescence spectroscopy; bimetallic nanoparticle; nanoparticle concentration
Online: 23 November 2023 (03:37:14 CET)
High-throughput research on bimetallic nanoparticles brought a vast overview of their characteristics and catalytic activities.1 However, traditional bimetallic nano-allloy quantification methods serving catalyst preparations are not suitable for the fast and robust data output of high-throughput experiments. Hence, this work designed and validated a more fast, more neat, and reliable quantitative analysis using X-ray fluorescence spectroscopy for bimetallic nanoparticles synthesized by high-throughput setups. The results demonstrated this method to be accurate with high precision. Furthermore, the agreement to qualitative results from an energy-dispersive X-ray spectrometer equiped on a scanning electron microscope provided an option to quantify a bimetallic nano-alloy by just analyzing one of the two composing elements. Thus, this method is proved to be highly compatible with high-throughput experiments.
REVIEW | doi:10.20944/preprints202311.0183.v1
Subject: Physical Sciences, Chemical Physics Keywords: Reichardts dye, solvatochromism; solvent mixtures; refractive index; solvent composition; average molar concentration
Online: 3 November 2023 (01:33:27 CET)
The UV/Vis absorption energies (νmax) of different solvatochromic probes measured in co-solvent/water mixtures are analysed as a function of the average molar concentration (Nav) of the solvent composition. Nav is discussed in terms of the underlying average molar mass (mol average or mass average) of the mixture. ET(30) of Reichardt`s dye B30 is the focus of the analysis. Methanol, ethanol, 1,2-ethanediol, 2-propanol, 2-methyl-2-propanol, 2-butoxyethanol, formamide, N-methylformamide (NMF), dimethylformamide (DMF), N-formylmorpholine (NFM), 1,4-dioxane and DMSO were used as co-solvents. Significant linear dependencies of ET(30) as a function of Nav can be demonstrated for formamide/water, 1,2-ethanediol/water, NMF/water and DMSO/water mixtures over the whole composition range. These mixtures belong to the group of solvents that do not enhance the water structure according to the Marcus classification. The specifics of the 1,4-dioxane/water mixtures are discussed. For alcohol/water mixtures with enhanced water structure, the influence of the solvent microstructure on ET(30) is particularly evident.
COMMUNICATION | doi:10.20944/preprints202308.1299.v1
Subject: Physical Sciences, Astronomy And Astrophysics Keywords: apparent surface density; concentration parameter; GAIA DR2; globular clusters; HST; space observations
Online: 18 August 2023 (10:18:22 CEST)
This article is a logical continuation of the work of Nuritdinov et al. (2021). We analyzed space observations of the apparent surface density of 81 globular clusters (GCs) observed by GAIA DR2 and published in de Boer et al (2019). First, we studied the features of the quality of the GC surface density data, including comparing them with the HST data. Using our 3-parameter model, previously tested on the example of HST space observations, we found the values of the stellar concentration parameter towards the center of the cluster. As a result, we found good correlations of this parameter with the physical characteristics of the GCs. We have also found the corresponding empirical formulas for this parameter.
ARTICLE | doi:10.20944/preprints202308.0088.v1
Subject: Social Sciences, Tourism, Leisure, Sport And Hospitality Keywords: menstrual cycle; running; kinetic variables; lactate concentration; heart rate; level of fatigue
Online: 2 August 2023 (02:28:34 CEST)
Background: Depending on the phase of the menstrual cycle the athlete is in, some kinetic, physiological and fatigue variables will show differences. The aim of this study is to analyze whether there are changes in these variables over the course of the menstrual cycle. Methods: Eight regular female runners and triathletes performed a maximal treadmill test, as well as a submaximal test (6’ stages at 50%, 60% and 80% of maximal aerobic speed) in each of the phases of the menstrual cycle: bleeding phase (day 2.4 ± 0.7), follicular phase (day 10.4 ± 2.2) and luteal phase (day 21.8 ± 2.1). Running dynamics were measured (using RunScribe) at the end of each test, as were lactate concentration, heart rate and fatigue (evaluated on a scale of 0 to 5). Results: Higher shock (G) values were recorded in the bleeding phase and higher vertical spring stiffness (kN/m) in the follicular phase. The phase of the menstrual cycle had a significant effect on average and peak heart rate, which was significantly higher in the follicular phase. Conclusions: Higher vertical spring stiffness was observed in the follicular phase, as well as higher peak and average heart rate.
ARTICLE | doi:10.20944/preprints202306.1489.v1
Subject: Engineering, Architecture, Building And Construction Keywords: CO2 concentration; living walls; fresh air energy consumption; Energyplus; indoor air quality
Online: 21 June 2023 (07:13:19 CEST)
Elevated indoor CO2 levels might have adverse effects on human health. However, the introduction of outdoor air to lower indoor CO2 concentrations results in significant HVAC energy consumption. Aligning with office hours and the natural light cycle, the utilization of photosynthesis in living walls offers an energy-efficient and sustainable solution for the mitigation of high CO2 levels in office spaces. This study experimentally investigates the impacts of the carbon fixation pathways, light intensity, and substrate moisture content on the CO2 removal rate of living walls at the room scale. Furthermore, the fresh air energy-saving effects of living walls under different scenarios are accurately simulated in EnergyPlus. The results demonstrate that choosing C3 plants over CAM plants in living walls yields higher CO2 removal efficiency. In a 30-m2 office room accommodating 2-3 occupants, living walls can reduce the demand for fresh air by 12.3%-27.8% and decrease fresh air energy consumption by 11.2%-28.2%. The city with the highest energy savings has energy savings that are 4.5 times greater than those of the city with the lowest energy savings. The findings of this research promote the application and development of living walls, thus providing a viable solution for improving indoor air quality.
ARTICLE | doi:10.20944/preprints202306.0097.v1
Subject: Biology And Life Sciences, Aquatic Science Keywords: repeated stress; hematology; fish; rainbow trout; hypoxia; dissolved oxygen concentration; RDW; cortisol
Online: 1 June 2023 (13:40:17 CEST)
Oxygen is a limiting factor both in the environment and production systems, so reduction may become a stressor. Diel cyclic hypoxia occurs with varying frequency and duration in freshwater habitats. Under a stressful situation fish activate the hypothalamic-pituitary-interrenal axis (HPI) which triggers the release of cortisol that induces secondary and tertiary responses. The recovery of individuals depends on their ability to modulate physiological, and biochemical responses to maintain homeostasis. The aim of this study is to determine the hematological and physiological responses of rainbow trout under repeated hypoxic stress in different time points. The methodology of the experiment consisted of dividing the fish in 5 different treatment groups, 2 control groups and 3 hypoxia groups. Every exposure consisted in decrease the dissolved oxygen concentration from 8mg O2/L to 2mg O2/L for 1 hour. After the exposure the fish went to a recovery tank until the sampling procedure. Hematological and physiological results show a habituation of the fish to different parameters such as hematocrit, hemoglobin and mean corpuscular volume among others. Overall, our results indicate an ability of rainbow trout to resist this type of hypoxic exposures and a habituation of fish to repeated hypoxia as observed in the different measured parameters.
ARTICLE | doi:10.20944/preprints202302.0393.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Carbon sinks; equilibrium concentration; emission pulse; peak emissions; Bern model; Net zero
Online: 23 February 2023 (02:10:57 CET)
The relation between CO2 emissions and atmospheric CO2 concentration has traditionally been treated with more or less complex models with several boxes. Our approach is motivated by the question of how much CO2 must necessarily be absorbed by sinks. Observations lead to the model assumption, that carbon sinks like oceans or biosphere are linearly dependent on CO2 concentration on a decadal scale. In particular this implies the falsifiable hypothesis that oceanic and biological CO2 buffers have not significantly changed in the past 50 years and are not saturated in the forseeable future. The simple model with 2 parameters explains very well the CO2 emission and historical CO2 concentration data. The model gives estimates of the natural emissions, the pre-industrial CO2 equilibrium concentration levels, the half-life time of an emission pulse, and the future CO2 concentration level from a given emission scenario. This is validated by an ex-post forecast of the last 20 years. The important result is that with the stated polices scenario of the IEA future CO2 concentrations will not rise above 475 ppm. The model is compared with the Carbon modul of the Bern model, mapping their complex IRFs to a single time variant parameter.
ARTICLE | doi:10.20944/preprints202208.0400.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: remote sensing; air-quality; S5P/TROPOMI; LOTOS-EUROS; EEA; NO2 surface concentration
Online: 23 August 2022 (11:40:33 CEST)
The aim of this paper is to evaluate the surface concentration of nitrogen dioxide (NO2) inferred from the Sentinel-5 Precursor TROPOspheric Monitoring Instrument (S5P/TROPOMI) NO2 tropospheric column densities over Central Europe for two time periods, the summer of 2019 and the winter of 2019-2020. Simulations of the NO2 tropospheric vertical column densities and surface concentrations from the LOng-Term Ozone Simulation – EURopean Operational Smog (LOTOS-EUROS) chemical transport model are also applied in the methodology. More than two hundred in-situ air quality monitoring stations, reporting to the European Environment Agency (EEA) air quality database, are used to carry out comparisons with the model simulations and the space-borne inferred surface concentrations. Stations are separated into seven types (urban traffic, suburban traffic, urban background, suburban background, rural background, suburban industrial and rural industrial) in order to examine the strengths and shortcomings of the different air quality markers, namely the NO2 vertical column densities and NO2 surface concentrations. S5P/TROPOMI NO2 surface concentrations are inferred by multiplying the fraction of the satellite and model NO2 vertical column densities with the model surface concentrations. The estimated inferred TROPOMI NO2 surface concentrations are examined further with the altering of three influencing factors: the model vertical levelling scheme, the versions of the TROPOMI NO2 data and the air mass factors applied to the satellite and model NO2 vertical column densities. Overall, the inferred TROPOMI NO2 surface concentrations show a better correlation with the in-situ measurements for both time periods and all station types, especially for the industrial stations (R>0.6) in winter. The calculated correlation for background stations is moderate for both periods (R~0.5 in summer and R>0.5 in winter), whereas for traffic stations it improves in the winter (from 0.20 to 0.50). After the implementation of the air mass factors from the local model, the bias is significantly reduced for most of the station types, especially in winter for the background stations, ranging from +0.49% for the urban background to +10.37% for the rural background stations. The mean relative bias in winter between the inferred S5P/TROPOMI NO2 surface concentrations and the ground-based measurements for industrial stations is about -15%, whereas for traffic urban stations it is approximately -25%. In summertime, biases are generally higher for all station types, especially for the traffic stations (~ -75%), ranging from -54% to -30% for the background and industrial stations.
ARTICLE | doi:10.20944/preprints202201.0331.v1
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: Concentration field; Spatial auto-correlation; Association rules; Apriori algorithm; Element co-occurrence
Online: 21 January 2022 (13:42:44 CET)
The spatial distribution of elements can be regarded as a numerical field of concentration values with a continuous spatial coverage. An active area of research is to discover geologically meaningful relationships among elements from their spatial distribution. To solve this problem, we propose an association rule mining method based on clustered events of spatial auto-correlation and applied it to the polymetallic deposits of the Chahanwusu River area, Qinghai Province, China. The elemental data for stream sediments were first clustered into HH (high-high), LL (low-low), HL (high-low), and LH (low-high) groups by using local Moran’s I clustering map (LMIC). Then the Apriori algorithm was used to mine the association rules among different elements in these clusters. More than 86% of the mined rule points are located within 1000 m of faults and near known ore occurrences, and occur in the upper reaches of the stream and catchment areas. In addition, we found that the Indosinian granodiorite is enriched in sulfophile elements, e.g., Zn, Ag and Cd, and the Variscan granite quartz diorite (P1γδο) coexists with Cu and associated elements. Therefore, the proposed algorithm is an effective method for mining co-existence patterns of elements and provides an insight into their enrichment mechanisms.
REVIEW | doi:10.20944/preprints202109.0153.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Biosurfactants; Critical micelle concentration (C.M.C.); Antioxidant; Microorganism; Soil quality; Plant disease management
Online: 8 September 2021 (13:34:43 CEST)
In the current scenario of changing climatic conditions and rising global population, there is always a need to explore novel, efficient, and economical natural products for the benefit of human kind. Biosurfactant is one of the latest explored microbial biomolecules that have been used in numerous fields, including agriculture, pharmaceuticals, cosmetics, food processing, and environment-cleaning industries as raw material, lubrication, wetting, foaming softening, making emulsions, and stabilizing dispersions. The amphiphilic nature of biosurfactant biomolecules showed great advantage, distributing themselves into two immiscible surfaces by reducing interfacial surface tension and increasing the solubility of hydrophobic compounds. Furthermore, their eco-friendly nature, low or even no toxic nature, durability at higher temperatures, and wide range of pH fluctuations making the microbial surfactants preferable compared to their chemical counterparts. Additionally, the biosurfactants can obviate the oxidation flow by eliciting the antioxidant property, antimicrobial, anticancer activity, and drug delivery system, further broadening their applicability in the food, pharmaceutical, and pharma industries. Nowadays, biosurfactant has been broadly utilized to improve the soil quality by improving the concentration of trace elements and mixed with pesticides or applied singly on the plant surfaces for plant disease management. In the present review, we summarise the latest aspect of microbial synthesized biosurfactant compounds, limiting factors of biosurfactant production, and their application in improving soil quality, plant disease management.
ARTICLE | doi:10.20944/preprints202107.0222.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: Graphene oxide; Quantum Dots; TD-DFT; Absorption; Quenching effect; Concentration; Optical Response
Online: 9 July 2021 (13:22:41 CEST)
In this work, we investigate by ab initio calculations and optical experiments the sensitiv- ity of graphene quantum dots in their use as devices to measure the presence, and concentration, of heavy metals in water. We demonstrate that the quenching or enhancement in the optical response (absorption, emission) depends on the metallic ion considered. In particular, two test cases of opposite behaviour are considered: Cd 2+ , where we observe an increase in the optical response for increasing concentration, and Pb 2 whose emission spectra are quenched along the concentration rise. We envisage that quantum dots of graphene may be routinely used as cheap detectors to measure the degree of poisoning ions in water
ARTICLE | doi:10.20944/preprints201910.0237.v1
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: Sehezar; geochemical anomaly separation; threshold; factor analysis; cluster analysis; concentration - area fractal
Online: 20 October 2019 (16:53:36 CEST)
Sehezar area is located in southern Tonokabon in Mazandaran province, north of Iran, near the Tarom – Hashdtjin belt. The existence of granitoid masses in the region can be important in terms of the potential of mineralization. Geochemical anomaly separation from the background is one of the important steps in mineral exploration. In the past decades, geochemical anomalies have been identified by means of various methods. Some of these separation methods include: statistical analysis methods (like univariate, bivariate, multivariate statistics), spatial statistical methods and fractal and multi-fractal methods. To identify the anomalous area, 71 stream sediment samples were collected from the area and analyzed by the ICP-MS method, and then interpreted. Initially, data were normalized and afterwards, univariate analysis (threshold limit and screening (P.N) methods) was used, in which results of the probable and definite anomaly of the threshold method were confirmed by the P.N screening method. Finally, the maps of the anomal zones were drawn. Then, bivariate analysis (Pearson correlation coefficients) and multivariate analysis on normal data were performed on SPSS software, in which factor analysis and cluster analysis were used for multivariate analysis. As a result of using the factor analysis method, six factors were identified and factor maps were drawn by the Surfer software. Also, by using cluster analysis, the variables were divided into two groups. In order for a better separation of the geochemical anomaly from the background, in addition to the threshold method, the Concentration - Area fractal method was used. Here, the fractal geometry using full-logarithmic graphs of the Concentration - Area obtained is capable of separating the stairs of different sections (background, threshold, and anomaly) with respect to the angle coefficient of the Concentration - Area plot. Then, in conclusion, results of these methods were compared and investigated, and finally, the anomalies area maps of the Au, Ag, Cu, Fe, W elements were drawn by Concentration - Area fractal and threshold methods and anomalous zones were introduced.
ARTICLE | doi:10.20944/preprints201807.0036.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: foraging activity; food exploitation; sugar nectar concentration; tropical species; meliponiculture; bee farming
Online: 3 July 2018 (11:08:42 CEST)
Stingless bee beekeeping provides new opportunities to improve the incomes of many households in Malaysia through the sale of honey and other bee products. While Heterotrigona itama is one of the most commonly cultured species of stingless bees, its behavior is not very well understood. Hence, we conducted this study to investigate the behavior of H. itama in exploiting food sources by ascertaining the nectar sugar concentration preferred by the bee. We also aimed to determine the preferred distance of food source from the bee hive. Our results suggest that H. itama prefers high sugar concentrations of 35% and above, and they would fly up to 7 m from the hive to collect food. We discuss how nectar concentration and food distance influence the number of bees exploiting food sources and the overall foraging pattern of H. itama.
ARTICLE | doi:10.20944/preprints202311.0560.v1
Subject: Environmental And Earth Sciences, Oceanography Keywords: sea ice concentration; recurrent neural network; Arctic sea ice prediction; short-term prediction
Online: 8 November 2023 (14:45:25 CET)
Arctic sea ice prediction holds significant importance for facilitating Arctic route planning, optimizing fisheries management, and advancing the field of sea ice dynamics research. While various deep learning models have been developed for sea ice prediction, they predominantly operate at the seasonal or sub-seasonal scale, often focusing on localized areas, and few cater to full-region daily scale prediction. This study introduces the use of spatiotemporal sequence data prediction models, namely, the convolutional LSTM (ConvLSTM) and predictive recurrent neural network (PredRNN), for the prediction of sea ice concentration (SIC). Our analysis reveals that, when solely utilizing SIC historical data as the input, the ConvLSTM model outperforms the PredRNN model in SIC prediction. To enhance the model's capacity to capture spatiotemporal relationships between multiple variables, we expanded the range of input data types to form the ConvLSTM-multi and PredRNN-multi models. Experimental findings demonstrate that the ConvLSTM-multi model excels in assimilating the influence of reanalysis data on sea ice within the sea ice edge region, thus exhibiting superior performance in predicting daily Arctic SIC over the subsequent 10 days. Furthermore, sensitivity tests on various model parameters highlight the substantial impact of sea surface temperature and prediction date on the accuracy of daily sea ice prediction. Additionally, meteorological and oceanographic parameters primarily affect the prediction accuracy of the thin ice region at the edge of the sea ice.
ARTICLE | doi:10.20944/preprints202310.0934.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: Attabad landslide-dammed lake; KKH; Lake Area; Suspension Sediment concentration; Remote Sensing Monitoring
Online: 16 October 2023 (10:17:33 CEST)
Understanding the evolving hydrological characteristics of landslide-induced barrier lakes is crucial for flood control, forecasting, early warning, and safety measures in the reservoir area. This study examines the changes in hydrological characteristics of the Attabad landslide-dammed lake over the past decade after the occurrence of the landslide, focusing on lake area dynamics and sediment concentration. High-resolution satellite images from QuickBird, Pleiades, and WorldView2 over seven periods were analyzed. The findings indicate that the lake area has gradually decreased, with the center of mass shifting towards the lake dam, indicating a trend towards stability. The suspended sediment in the barrier lake is distributed in a strip running from north to south, then northeast to southwest, with sediment concentration decreasing from the lake entrance to the dam and from the lake bank to the center. Over time, the average sediment concentration has decreased from 2010 to 2020, with higher concentrations in summer than in winter. Notably, during the 2017-2020 period, the lower-middle parts of the lake experienced higher sediment concentration, while the dam area witnessed lower concentrations, thereby reducing the sediment impact on the dam.
ARTICLE | doi:10.20944/preprints202309.1230.v1
Subject: Engineering, Mining And Mineral Processing Keywords: element concentration–area (C-A); multifractal; singularity exponent; uranium ore; uranium distribution characteristic
Online: 19 September 2023 (13:30:31 CEST)
Based on the analysis of the spatial distribution of uranium grade in 348 boreholes of a uranium deposit in Xinjiang, the enrichment and spatial variation of uranium ore in two stopes of the deposit are discussed by using multifractal theory. The distribution characteristics of uranium ore of the two stopes are studied by multifractal parameters: the scaling exponent of mass , the scaling exponent of each sub-set and its corresponding fractal dimension , the fractal dimension D0 and information dimension D1. The differences of uranium distribution in two stopes can be well quantified by multifractal spectrum and multifractal parameters( , , ).10m×10m is defined as a fence unit, and the window sizes are respectively set, the singularity exponent of the two stopes are calculated by this element concentration-area(C-A) method. The results show that the multifractal theory and model can organically combine spatial structure information, scale change information and anisotropy information to obtain low-grade and weak mineral resources information, and can effectively distinguish complex and superimposed anomalies. This will provide a basis for local concentration and spatial variation rules of uranium distribution and the design of the parameters of leaching uranium mining well site.
ARTICLE | doi:10.20944/preprints202305.0849.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Escherichia coli; bacterial transformation; plasmid-to-cell ratio; competent cell concentration; incubation time
Online: 11 May 2023 (11:49:13 CEST)
Bacterial transformation is the essential tool for introducing foreign DNA into bacterial cells in a host of recombinant technology applications useful for biomanufacturing and drug production. Thus far, chemically competent cells remain an important enabling technology for bacterial transformation given its facile transformation approach. However, many parameters affect transformation efficiency, and there is relatively little documentation of their cross-interacting effect in the literature. This work explores the roles played by incubation time on ice, competent cell concentration, and plasmid-to-cell ratio on transformation efficiency in Escherichia coli DH5α. Results revealed that increases in incubation time improve transformation efficiency, but 2 minutes incubation still yield appreciable efficiency. On the other hand, low concentration competent cells (106 CFU/mL) yielded significant improvement in transformation efficiency compared to high concentration competent cells (108 CFU/mL). In terms of plasmid-to-cell ratio, higher ratio increases transformation efficiency. Overall, bacterial transformation is incompletely understood particularly in the area of cross-interacting parameters. Experiments reported here revealed the possibility of short duration transformation where lower competent cell concentration and higher plasmid-to-cell ratio could improve transformation.
ARTICLE | doi:10.20944/preprints202303.0234.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: aluminum chlorohydrate; antibiotic resistance; minimum inhibitory concentration; quantitative reverse transcriptase-PCR; Staphylococcus epidermidis
Online: 13 March 2023 (14:04:54 CET)
This study investigates the effects of the antiperspirant aluminum chlorohydrate on the development of antibiotic resistance in commensal Staphylococcus epidermidis isolates. The isolates were exposed to aluminum chlorohydrate for 30 days, respectively. The bacteria that developed resistance to oxacillin, and ciprofloxacin were isolated, and the expression levels of some antibiotic resistance genes were determined by quantitative reverse transcriptase-PCR. Before and after the exposure, the minimum inhibitory concentration (MIC) values of the bacteria were determined by the microdilution method. A time-dependent increase was observed in the number of bacteria that developed resistance and increased the MIC value. Consistent with the ciprofloxacin resistance observed after exposure, an increase in the norA, norB/C, gyrA, gyrB, parC, and parE gene expressions was observed. In addition to aluminum chlorohydrate exposure, oxacillin resistance was observed in all test bacteria in the group subcultured only in the medium, suggesting that phenotypic resistance cannot be correlated with chemical exposure in the light of these data. The increase in mecA gene expressions of selected test bacteria that acquired resistance to oxacillin after exposure compared with control groups suggests that the observed resistance may be related to aluminum chlorohydrate exposure. To our knowledge, this is the first time in the literature that the effects of aluminum chlorohydrate as an antiperspirant on the development of antibiotic resistance in Staphylococcus epidermidis have been reported.
ARTICLE | doi:10.20944/preprints202301.0488.v1
Subject: Medicine And Pharmacology, Anesthesiology And Pain Medicine Keywords: minimum alveolar concentration MAC; isoflurane; dexmedetomidine; morphine; synthetic cannabinoid WIN 55,212-2; rats
Online: 27 January 2023 (06:16:10 CET)
The effects of morphine (MOR) and dexmedetomidine (DEX) on the MAC of isoflurane were measured in rats chronically treated with the synthetic cannabinoid WIN 55,212-2 (WIN55). Methods: The MAC of isoflurane was determined in 32 male rats from expiratory samples at the time of tail clamping. The effects of morphine (MAC(ISO+MOR)) and dexmedetomidine (MAC(ISO+DEX)) on the MAC of isoflurane in untreated rats and rats treated for 21 days with WIN 55,212-2 (MAC(ISO+WIN55+MOR)) and (MAC(ISO+WIN55+DEX)) were measured. Prior to the administration of morphine and dexmedetomidine, the MAC of the isoflurane was measured in both untreated rats (MAC(ISO)) and those treated with WIN 55,212-2 (MAC(ISO+WIN55)). Results: The minimum alveolar concentration was measured as 1.32 ± 0.06 in the MAC(ISO) group and 1.69 ± 0.09 in the MAC(ISO+WIN55) group. The MAC of the MAC(ISO+MOR) group was 0.97 ± 0.02 (26% less than the control group, MAC(ISO)). MAC was measured as 1.55 ± 0.08 in the MAC(ISO+WIN55+MOR) group (8% less than the MAC(ISO+WIN55) group), 0.68 ± 0.10 in the MAC(ISO+DEX) group (48% less than the control group, MAC(ISO)), and 0.67 ± 0.08 in the MAC(ISO+WIN55+DEX) group (60% less than the MAC(ISO+WIN55) group). Conclusions: The administration of WIN 55,212-2 for 21 days increases the MAC of isoflurane in rats. The sparing effect on isoflurane of morphine decreases in rats chronically treated with the synthetic cannabinoid, WIN 55,212-2. Dexmedetomidine increases its sparing effect on the minimum alveolar concentration of isoflurane in rats chronically treated with WIN 55,212-2.
ARTICLE | doi:10.20944/preprints202204.0302.v1
Subject: Engineering, Control And Systems Engineering Keywords: Organic mulching; rainfall simulator; Hydraulic Tilting flume system; Sediment concentration; Sediment outflow rate
Online: 29 April 2022 (12:52:48 CEST)
Trash mulches are very effective in preventing soil erosion; reduce sediment transport rate, runoff rate and increasing infiltration. The study was carried out with the objectives to observe the sediment outflow from sugar cane leaf (trash) mulch treatments at selected land slopes under simulated rainfall conditions by using rainfall simulator of size 10 m × 1.2 m × 0.5 m with the locally available soil material collected from Pantnagar. In the present study, trash mulches with different quantities were selected to observe the effect of mulching in soil loss reduction. The quantity of mulch was taken as, 6 t/ha, 8 t/ha and 10 t/ha, three rainfall intensities viz. 11cm/h, 13cm/h and 14.65cm/h at 0%, 2% and 4% land slopes were selected. The duration of rainfall was fixed (10 minutes) for every mulch treatment. The total runoff volume was found to be varying with different mulch rates for particular rainfall input and land slope. The runoff distribution pattern was observed to be increasing with the increase in land slope. The average sediment concentration (SC) and outflow was found to be increasing with the increasing land slope, but SC and outflow decreased with increasing mulch rate for particular land slope and rainfall intensity. The SOR (SOR) for no mulch treated land was higher as compared to trash mulch treated lands. Mathematical relationships were developed for relating SOR, SC, land slope and rainfall intensity for a particular mulch treatment. It was observed that values of SOR and average SC had a good correlation with rainfall intensity and land slope for each mulch treatment. The correlation coefficients of developed models were found to be more than 90%.
ARTICLE | doi:10.20944/preprints202309.0181.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Carbon; concentration; CO2; emission; rivers; lakes; biogeochemical cycle; Central Asia, Al-tai-Sayan mountain
Online: 5 September 2023 (02:52:19 CEST)
Carbon (C) cycle n inland waters, including its concentrations and carbon dioxide (CO2) emis-sions from water surfaces are at the forefront of biogeochemical studies, especially in the re-gions, strongly impacted by on-going climate change. Towards better understanding of C stor-age, transport and emission in Central Asian mountain regions, extremely poorly studied until now, here we carried out systematic measurements of dissolved C and CO2 emissions in 15 riv-ers and 5 lakes located along a macro-transect of various natural landscapes in the Sayan-Altai mountain region, from high mountains of the Western Sayan in the northwest of Tyva to arid (dry) steppe and semi-deserts in intermountain basins of the southeast of Tyva, the border with Mongolia. New data on major hydrochemical parameters, CO2 fluxes by floating chambers, dis-solved organic and inorganic carbon concentrations collected over four main hydrological sea-sons allowed to assess the current C biogeochemical status of these water bodies in order to judge possible future changes under climate warming. We further tested the impact of perma-frost, river watershed size, lake area and climate parameters as well as ‘internal’ biogeochemical drivers (pH, mineralization, organic matter quality and bacterial population) on CO2 concentra-tion and emissions in lakes and rivers of this region, and compared them with available data on other subarctic and mountain settings.
ARTICLE | doi:10.20944/preprints202304.0701.v1
Subject: Environmental And Earth Sciences, Pollution Keywords: low-cost sensors; particle number concentration; laboratory study; fine particles; particulate matter; air pollution
Online: 21 April 2023 (09:10:07 CEST)
Low-cost particulate matter (PM) sensors offer an excellent opportunity to improve our knowledge about this type of pollution. Their size and their cost, which support multi-node network deployment, along with their temporal resolution, enable them to report fine spatio-temporal resolution for a given area. These sensors have known issues across performance metrics. Generally, the literature focuses on the PM mass concentration reported by these sensors but some models of sensors also report particle number concentrations (PNC) segregated into different PM size bins. In this study, 8 units of each Alphasense OPC-R1, Plantower PMS5003 and Sensirion SPS30 have been exposed, under controlled conditions, to short-lived peaks of PM generated using two different combustion sources of PM, exposing the sensors to different particle size distributions to quantify and better understand the low cost sensors performance across a range of relevant environmental ranges. The PNC reported by the sensors were analysed. This study showed that there is added value in directly using the PNC reported by the sensors instead of the mass concentrations, which could aid the efforts to calibrate these sensors to a known accuracy. It demonstrated that all sensors tested here could track the fine temporal variation of PNC, that the Alphasense OPC-R1 could closely follow the variations of size distribution between the two sources of PM, and it showed that particle size distribution and composition are more impactful on the sensors measurement than relative humidity.
ARTICLE | doi:10.20944/preprints202211.0108.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: diffusion dialysis; concentration; electrodialysis; ion-exchange membrane; separation of acids and salts; acid recovery
Online: 7 November 2022 (06:10:02 CET)
In the present study, the problem of the sulfuric acid recycling from spent copper plating solution was solved using a hybrid membrane technology, including diffusion dialysis and electrodialysis. A real solution from the production of copper-coated steel wire, containing 1.45 mol/L of sulfuric acid, 0.67 mol/L of ferrous sulfate and 0.176 mol/L of copper sulfate was processed. Diffusion dialysis with anion-exchange membranes was used to separate sulfuric acid and salts of heavy metals. Then purified dilute sulfuric acid was concentrated by electrodialysis. Energy consumption for sulfuric acid electrodialysis concentration at a current density of 400 A/m2 was 162 W·h/mol with current efficiency 16 %. After processing according to the hybrid membrane scheme, the solution contained 1.13 mol/L sulfuric acid, 0.077 mol/L ferrous sulfate and 0.022 mol/L copper sulfate. The resulting acid solution with a small amount of ferrous sulfate and copper sulfate met the established requirements for a copper plating bath solution and can be reused in production.
CASE REPORT | doi:10.20944/preprints202111.0331.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: wearable sensor; pulse oximetry; sleep disturbance; blood oxygenation; haptic feedback; home care; oxygen concentration
Online: 18 November 2021 (14:32:09 CET)
The study reports about a case of a lung cancer patient with increasing difficulties in falling asleep and frequent periods of wakefulness. Severe dyspnea related to pneumonitis caused as a side effect of immunotherapy worsened the situation. Eventually, fear of falling asleep developed, including panic attacks and anxiety of choking, which was shown to lead to nights of complete wakefulness. The patient did not only sleep poorly; he did not sleep at all at night for several days, as evidenced by the notes he made during the night. Polygraphy showed no evidence of sleep-disordered breathing, but frequent periods of wakefulness and reduced basal saturation around 90% during sleep due to lung changes such as extensive functional failure of the left upper lobe with position-dependent shunts. The authors hypothesized that the symptoms described were causally related to a drop in oxygen saturation in the patient's blood. Therefore, they pursued the goal of finding a measurement technique that is as inexpensive as possible and that the patient can operate without outside assistance and great effort. So the patient started using a low-cost wearable device that allows simultaneous measurements of blood oxygen content, pulse rate and movement intensity. It consists of a finger ring with pulse oximetry sensor and a wristband with the control unit containing a vibration motor. The described device reliably warned of disturbances in oxygen concentration in the blood during the night with its vibration alarm. By use of that device during the whole night at home, the events of reduced oxygen saturation and the anxiety symptoms were reduced. Sleep disturbances with sudden awakenings did not occur when using the device. The patient benefited from the security gained in this way and slept much more peacefully, and he could spend nights without waking up again. In conclusion, wearable oximeters with vibration alarm can be recommended for patients’ home care in lung cancer patients.
ARTICLE | doi:10.20944/preprints202110.0075.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: High-entropy alloys; compositional complexity; valence electron concentration; Miedema model; paired sigma forming element
Online: 5 October 2021 (09:21:32 CEST)
High-entropy alloys (HEAs) are of great interest in the field of materials science and engineering. Unlike conventional alloys, which contain a maximum of two base metals, this new category of materials consists of multi-principle elements and the possible number of alloy compositions, in case of HEAs, is outstandingly higher than that for conventional alloys. Here, a review on the high-entropy alloys, has been provided, on the issue whether the earliest definition of High- Entropy alloys, proposed in 2004[2, 4], is consistent with one of the four-component equiatomic Compositionally complex alloys exhibiting a “High-entropy” effect.
TECHNICAL NOTE | doi:10.20944/preprints202001.0386.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: remote sensing; water quality; chlorophyll concentration; suspended sediment; sentinel-2; sentinel-3; open science
Online: 31 January 2020 (11:59:22 CET)
Easy to use satellite-based water quality visualizations are needed for monitoring and understanding coastal and inland waters, but to date, no publicly accessible real-time global visualization system was in place. Here we introduce the Ulyssys Water Quality Viewer (UWQV), a Sentinel Hub EO Browser Custom script designed for qualitative views of aquatic chlorophyll and suspended sediment concentrations. The viewer avoids unmixing of the chlorophyll and suspended sediment spectral signal by visualizing these parameters together, with high concentrations of suspended sediment obscuring chlorophyll if present. Cloud masking uses the Hollstein and Braaten algorithms (existing EO Browser custom script code), additionally water surfaces are masked using the Normalized Differential Water Index. Chlorophyll is estimated using reflectance line height-based indicators such as fluorescence line height and maximum chlorophyll index. Suspended sediment is visualized based on single-band reflectances at 620 or 700 nm. Data sources are Sentinel-2 and Sentinel-3 images, allowing either 20 m spatial resolution or up to daily imaging. This visualization system is easy to operate and interpret, and combined with the data service capacity of the Sentinel Hub, it is expected that UWQV will contribute to monitoring of remote water bodies and to our overall understanding of physical limnology and aquatic ecology.
ARTICLE | doi:10.20944/preprints201809.0062.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: Nernst voltage; activation overvoltage; concentration loss; equilibrium potential; exchange current density; net current density
Online: 4 September 2018 (11:56:23 CEST)
Normally, the Nernst voltage calculated from the concentration of the reaction gas in the flow channel is considered to be the ideal voltage (reversible voltage) of the oxyhydrogen fuel cell, but actually it will cause a concentration gradient when the reaction gas flows from the flow channel through the gas diffusion layer to the catalyst layer. The Nernst voltage loss in fuel cells in most of the current literature is thought to be due to the difference in concentration of reaction gas in the flow channel and concentration of reaction gas on the catalyst layer at the time when the high net current density is generated. Based on the Butler-Volmer equation in oxyhydrogen fuel cell, this paper demonstrates that the Nernst voltage loss is caused by the concentration difference of reaction gas in flow channel and on the catalytic layer at the time when equilibrium potential (Galvanic potential) of each electrode is generated.
ARTICLE | doi:10.20944/preprints202311.1229.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: atmosphere– ocean dynamics; sea surface temperature; polar vortex; air temperature; ozone concentration; zonal wind
Online: 20 November 2023 (07:50:24 CET)
Tropical sea surface temperature (SST) variability, mainly driven by the El Niño–Southern Oscillation (ENSO), influences the atmospheric circulation and hence the transport of heat and chemical species in both the troposphere and stratosphere. This paper uses Met Office, ERA5 and MERRA2 reanalysis data to examine the impact of SST variability on the dynamics of the polar stratosphere and ozone layer over the period 1980 to 2020. Particular attention is paid to studying the differences in the influence of different types of ENSO (East Pacific (EP) and Central Pacific (CP)) for the El Niño and La Niña phases. It is shown that during the EP El Niño, the zonal wind weakens more strongly and changes direction more often than during the EP El Niño, and the CP El Niño leads to a more rapid decay of the polar vortex (PV), an increase in stratospheric air temperature and an increase in the concentration and total column ozone than during EP El Niño. For the CP La Niña, the PV is more stable, which often leads to a significant decrease in Arctic ozone. During EP La Niña, powerful sudden stratospheric warmings are often observed, which lead to the destruction of PV and an increase in column ozone.
ARTICLE | doi:10.20944/preprints202308.0788.v1
Subject: Engineering, Mechanical Engineering Keywords: stress concentration factors; fatigue life; finite element analyse (FEA); stress analysis; fatigue notch factor; solidworks
Online: 9 August 2023 (14:34:55 CEST)
Fatigue failure remains a critical concern in structural engineering and material science, prompting extensive research to understand and predict the behaviour of materials under cyclic loading conditions. The present study aims to investigate the fatigue life of carbon steel specimens containing opposite semicircular edge notches through a comprehensive experimental and numerical analysis. In this study, stress concentration factors (SCF, Kt) of rectangular plate with opposite semicircular notches are considered under uniform tensile stress to analyse the notch deformation because of stretching of plate. Furthermore, the research focuses on quantifying stress concentration factors (SCFs) for these notches based on S-N curves of carbon steel. The study employs a combination of experimental and numerical techniques to understand the influence of these notches on the fatigue performance of carbon steel structures. A plate with opposite semicircular edge single notches under the axial load creates stress concentration near the notch and it is much larger than the average stress on the plate. Both analytical and finite element methods are used to calculate the maximum stress around the notch. SOLIDWORKS Premium Student Edition 2023 has been employed for modelling and SOLIDWORKS Simulation Premium Student Edition 2023 has been used for stress analysis and fatigue notch factor of rectangular plate of size 31 mm x 25.4 mm x 6.35 mm. The uniform tensile load with a magnitude of 20195 N is applied on one sides of rectangular plate normal to the sides of notches with ratio h/r = 1, for the semicircular notch. The result obtained on both analytical and finite element methods are compared and the percentage of error has been evaluated. Subsequently, these specimens undergo fatigue testing under varying loading conditions to capture their fatigue behaviour. The acquired fatigue data is then plotted against stress amplitude to construct S-N curves, forming the foundation for assessing the fatigue life of the notched specimens. To complement the experimental findings and to gain a deeper understanding of the stress concentration phenomenon, numerical simulations are conducted using advanced finite element analysis (FEA) techniques. The finite element models are carefully calibrated against the experimental results to ensure their accuracy and reliability. The FEA simulations enable the determination of stress concentration factors at critical locations within the notched specimens, further validating the experimental observations. The investigation reveals crucial insights into the effect of opposite semicircular edge notches on the fatigue life of carbon steel structures. The obtained S-N curves allow engineers and designers to predict the fatigue life of components with similar notches, aiding in the development of reliable and durable structures in practical applications. Moreover, the stress concentration factors determined from the numerical simulations provide valuable data to assess the potential failure modes and to optimise designs, effectively mitigating fatigue-related failures. The combination of experimental and numerical approaches ensures a comprehensive and rigorous analysis of the fatigue behaviour in notched specimens, offering a reliable basis for making informed engineering decisions. The comparison between the analytical method and the Finite Element Method (FEM) demonstrated good agreement, with an error percentage of 4.272%. The analysis revealed that the specimen would experience failure after approximately 2882 cycles, with a maximum stress of 395.914 MPa. This research study enhances the understanding of fatigue life in carbon steel structures containing opposite semicircular edge notches and contributes valuable data to the field of fatigue mechanics. The outcomes serve as a valuable resource for professionals engaged in structural engineering, material science, and design optimisation, ultimately leading to safer and more durable industrial components in critical applications. The findings of this research contribute to the understanding of fatigue behaviour in carbon steel components with stress concentration effects caused by semicircular notches. Moreover, the validated numerical simulations and data curves facilitate the prediction of fatigue life and aid in determining the critical conditions leading to fatigue failure. In conclusion, this research highlights the significance of combining experimental testing with numerical simulations to comprehensively analyse the fatigue life of carbon steel specimens with opposite semicircular edge notches. The obtained stress concentration factors provide crucial information for structural integrity assessment and offer potential for further optimising design criteria to mitigate fatigue-related failures. The findings of this study could play a vital role in enhancing the reliability and safety of carbon steel structures subjected to cyclic loading conditions. The comprehensive experimental and numerical analyses establish a foundation for future studies exploring other materials and geometries with notches, fostering advancements in fatigue life prediction and structural integrity assessment.
ARTICLE | doi:10.20944/preprints202305.1691.v1
Subject: Engineering, Civil Engineering Keywords: bending load; sulfate erosion; dry and wet cycle; cement-based materials; ion concentration; numerical simulation
Online: 24 May 2023 (04:38:30 CEST)
The goal of this lab is to look at how the characteristics of cementitious materials are affected by bending loads combined with dry and wet cycles of sulfate. In this paper, three sets of specimens with different water–cement ratios were designed. This study applied 20% and 40% of the ultimate bending load as a continuous bending load to the cementitious material specimens for a sulfate erosion test. It was discovered that the specimens' porosity, flexural strength, and compressive strength all tended to improve initially before declining as the cementitious material was degraded in the sulfate solution aged. The flexural strength of the cementitious materials declined as the bending load increased, and their internal sulfate ion concentration rose. A transport model of sulfate ions in cementitious materials under the coupling effect of bending load and sulfate erosion was created by combining the improved version of Fick’s second law and chemical reaction kinetics. The simulation results show that the ion transport properties of sulfate ions in cementitious materials are in accordance with the experimental laws. These research results formed the basis of the unified standards for the coupling of load dry and wet cycle systems, as well as evaluating the durability of cementitious materials under corrosive environments.
ARTICLE | doi:10.20944/preprints202103.0362.v1
Subject: Engineering, Civil Engineering Keywords: apartment building; aerodynamic coefficient; wind speed; air change rate; concentration of carbon dioxide; experimental measurement
Online: 15 March 2021 (08:11:30 CET)
Air change rate is an important parameter for quantification of ventilation heat losses and also affects the indoor climate of buildings. Indoor air quality is significantly associated with ventilation. If air change isn't sufficient, trapped allergens, pollutants and irritants can degrade the indoor air quality and affect the well-being of a building's occupants. Many studies on ventilation and health have concluded that lower air change rates can have a negative effect on people’s health and low ventilation may result in an increase in allergic diseases. Quantification of air change rate is complicated, since it is affected by a number of parameters, of which the one of the most variable is the air-wind flow. This study aims to determination and comparison of values of the air change rate in two methods - by quantifying of aerodynamic coefficient Cp = Cpe - Cpi – so called aerodynamic quantification of the building and the methodology based on experimental measurements of carbon dioxide in the selected reference room in apartment building.
ARTICLE | doi:10.20944/preprints202311.1786.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: chainsaw chain type; inhalable wood dust concentration; motor-manual harvesting; operator health and safety; tree species
Online: 28 November 2023 (08:24:19 CET)
This study examines the impact of chainsaw chain type and tree species on the concen-tration of inhalable wood dust generated during motor-manual harvesting in forested areas. The chainsaw chain is a critical component, contributing not only to productivity but also to the oper-ator's health and safety. Wood dust creation during harvesting operations poses significant risks and necessitates careful attention due to its potential health effects. We investigated the effects by conducting real-world measurements of inhalable dust within the operator's breathing zone during forestry work. Two different chain types were evaluated: the commonly used 3/8" pitch chain (conventional chain) and the 0.325" pitch chain. Additionally, measurements were taken for three tree species: beech, oak, and pine (including both live and standing dead trees after a fire). Results showed that, overall, using the conventional 3/8" chain type yielded the highest concentration of wood dust for all three tree species. Notably, the highest wood dust concentration was observed in the burned Pinus brutia cluster, also with the 3/8" chain pitch. These findings emphasize the im-portance of understanding how chain type and tree species contribute to wood dust levels and provide valuable insights for enhancing operator health and safety during motor-manual har-vesting operations
ARTICLE | doi:10.20944/preprints202211.0049.v2
Subject: Environmental And Earth Sciences, Oceanography Keywords: optical characteristics; chlorophyll-a concentration; ocean color; seawater; absorbing aerosol; dust; MODIS Aqua; AERONET; Black Sea
Online: 2 December 2022 (08:52:08 CET)
In the presence of absorbing aerosol in the atmosphere a number of systematic errors of standard Ocean Color algorithms were noted, for example, negative values of remote sensing reflectance in the short-wavelength region at 412 nm and 443 nm. The main goal of this work is to develop an algorithm for additional correction of remote sensing reflectance level 2 satellite data, taking into account the presence of absorbing aerosol over the Black Sea, where a large number of dust transfers from the Sahara are observed annually. To implement the algorithm, an analytical and experimental evaluation of the interpolation function is carried out, taking into account the optical effects caused by the stratification of the absorbing aerosol. This algorithm is based on the constancy of the color index value, characteristic of the selected region. For the Black Sea the average value of CI(412/443) = 0.80±0.08, a small standard deviation indicates that the sample is slightly variable. Therefore, CI(412/443) = 0.80 will be further considered as the reference value of the color index for calculating new restored Rrs(λ).
ARTICLE | doi:10.20944/preprints202111.0160.v1
Subject: Engineering, Energy And Fuel Technology Keywords: Absorber Layer; Buffer Layer; CZTS; CdSe; ZnSe; Conversion Efficiency; Carrier Concentration; Temperature; SCAPS-1D; Solar Cell
Online: 9 November 2021 (08:19:08 CET)
This article describes in detail the numerical modeling of a CZTS (copper zinc tin sulfide) based kesterite solar cell. The Solar Cell Capacitance Simulator -one-dimension (SCAPS-1D) software was used to simulate MO/CZTS/CdS/ZnO/FTO structured solar cells. The parameters of different photovoltaic thin-film solar cells are estimated and analyzed using numerical modeling. The effects of various parameters on the performance of the photovoltaic cell and the conversion efficiency are discussed. Since the response of the solar cell is also contingent on its internal physical mechanism, J-V characteristic measures are insufficient to characterize the behavior of a device. Different features, as well as different potential conditions, must be considered for simulation, disregarding the belief in the modeling of a solar cell. With a conversion efficiency of 25.72%, a fill factor of 83.75%, a short-circuit current of 32.96436 mA/cm2 and an open-circuit voltage of 0.64V, promising optimized results have been achieved. The findings will be useful in determining the feasibility of fabricating high-efficiency CZTS-based photovoltaic cells. The efficiency of a CZTS-based experimental solar cell is also discussed. First, the effects of experimentally developed CZTS solar cells are simulated in the SCAPS-1D environment. The experimental results are then compared to the SCAPS-1D simulated results. The conversion efficiency of an optimized system increases after cell parameters are optimized. Using one-dimensional SCAPS-1D software, the effect of system parameters such as the thickness, acceptor and donor carrier concentration densities of absorber and electron transport layers, and the effect of temperature on the efficiency of CZTS-based photovoltaic cells is investigated. The proposed results will greatly assist engineers and researchers in determining the best method for optimizing solar cell efficiency, as well as in the development of efficient CZTS-based solar cells.
ARTICLE | doi:10.20944/preprints201904.0324.v1
Subject: Engineering, Civil Engineering Keywords: salt-lake environment; concrete; concrete chloride-ion diffusion coefficient; multi-factor coupling model; chloride-ion concentration
Online: 30 April 2019 (11:10:26 CEST)
Immersion in salt-lake solution was adopted to periodically test the concrete chloride-ion diffusion coefficient. The regression analysis was also completed. Also investigated was the time-dependent law of concrete chloride-ion diffusion coefficient with time. The influence of chloride-ion concentration in solution, water-to-cement ratio, and corrosion time on the largeness and accumulation rate of the concrete chloride-ion diffusion coefficient was also analyzed. Test results show that the concrete chloride-ion diffusion coefficient gradually decreased with increasing time and increased with increasing chloride-ion concentration in a salt lake . Taking into account the influence of factors such as water–binder ratio, chloride-ion concentration, and time-varying characteristics, a multi-factor calculation model for the concrete chloride-ion diffusion coefficient was established. Combining the prediction results and the measured data reported in this paper, the effectiveness and applicability of the established concrete chloride-ion diffusion coefficient calculation model were compared and verified, and the durability design and service life of a concrete structure under cool chlorine were compared. The results of analysis provide important boundary conditions.
ARTICLE | doi:10.20944/preprints201704.0092.v1
Subject: Medicine And Pharmacology, Dietetics And Nutrition Keywords: Parboiled rice, medium-grain white rice, cold stored, reheating, blood glucose concentration chewing time, satiety, palatability.
Online: 17 April 2017 (05:35:10 CEST)
Background: Globally, hot cooked refined rice is consumed in large quantities and is a major contributor to dietary glycaemic load. This study aimed to compare the glycaemic potency of hot and cold stored parboiled rice to widely available medium grain white rice. Method: Twenty-eight healthy volunteers participated in a three treatment experiment where postprandial blood glucose was measured over 120 minutes after consumption of 140g of rice. Three rice samples were freshly cooked medium-grain white rice, freshly cooked parboiled rice, and parboiled rice stored overnight at 4 ºC. All rice was served warm at 65 ºC. Chewing time was recorded. Results: The 24-hours cold-stored and reheated parboiled rice resulted in a 42% and 12% lower blood glucose concentration trajectory than freshly cooked medium-grain white rice and freshly cooked parboiled rice. Chewing time for 10g cold stored parboiled rice was 6 seconds (25%) longer and was considered more palatable, visually appealing and better tasting than freshly cooked medium grain (all P<0.05). Conclusions:. For regular consumers of rice reheating cooked rice after cold storage would lower the dietary glycaemic load and long term may reduce risk for type 2 and gestational diabetes. More trials are needed to identify the significance.
ARTICLE | doi:10.20944/preprints201608.0234.v1
Subject: Physical Sciences, Particle And Field Physics Keywords: 3-D fluid-electrostatic coupling field; electrical sensor performance; concentration measurement; gas/solid two-phase flow
Online: 31 August 2016 (09:03:30 CEST)
This paper proposed three-dimensional numerical simulation method by coupling of electrostatic and fluid fields to evaluating the performance of electrical sensor in the concentration measurement of gas/solid two-phase flow. Compared with the static numerical simulation, this real-time dynamic 3-D simulation method can research on a designed capacitance sensor combining the dynamic characteristics of the two-phase flows for concentration measurement. Several fluid-electrostatic models of transmission pipes with different sensor structures are built. Under different test positions and different particle concentrations, the flow characteristics and the corresponding electric signals can be obtained, and the correlation coefficient between the concentration values and the capacitance values are used for performance evaluation of the sensors. The effects of flow regimes on concentration measurement are also been investigated in this paper. To validate the results of simulation, an experimental platform with horizontal straight pipe for phase volume concentration measurement of solid/air two-phase flow is built, and the experimental results agree well with simulation conclusions. The simulation and test results show that the coupling models can give constructive reference opinions for the sensor design and collection of installation position in different transmission pipelines, which are very important for the practical process of pneumatic conveying system.
ARTICLE | doi:10.20944/preprints202308.1711.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: skeletal muscle; actomyosin ATPase; ADP; temperature; cytoplasmic magnesium ion concentration, cytoplasmic pH; inorganic phosphate, Pi; isometric force generation
Online: 24 August 2023 (09:50:53 CEST)
In this report, we establish a straightforward method for estimating the equilibrium constant for the CK reaction over wide but physiologically and experimentally relevant ranges of pH, Mg2+ and temperature. Our empirical formula for CK Keq” is based on experimental measurements. It can be used to estimate [ADP] when [ADP] is below the resolution of experimental measurements, a typical situation because [ADP] is on the order of micromolar concentrations in living cells, and may be much lower in many in vitro experiments. Accurate prediction of [ADP] is essential for in vivo studies of cellular energetics and metabolism, and for in vitro studies of ATP-dependent enzyme function under near-physiological conditions. With [ADP], we could estimate ΔGATP. Application to actomyosin force generation in muscle provides support for the hypothesis that, when [Pi] varies but not when pH is altered, maximum Ca2+-activated isometric force depends on ΔGATP in both living and permeabilized muscle preparations. Further analysis of the pH studies introduces a novel hypothesis for the role of submicromolar ADP in force generation.
ARTICLE | doi:10.20944/preprints202105.0716.v1
Subject: Engineering, Civil Engineering Keywords: hard rock mine; cemented rock fill (CRF); backfilling step scenario; major principal stress; stress concentration factor (SCF); displacement
Online: 31 May 2021 (08:43:52 CEST)
Cemented rock fill (CRF) is commonly used in cut-and-fill stoping operation in underground mining. This allows for the maximum recovery of ore. Backfilling can improve stope stability in underground workings, and then improve ground stability of the whole mine site. Backfilling step scenarios vary from site to site. This paper presents the investigation of five different backfilling step scenarios and their impacts on the stability of stopes at four different mining levels. A comprehensive comparison of displacements, major principal stress and stress concentration factor (SCF) was conducted. The results show that different backfilling step scenarios have little influence on the final displacement for displacement in the stopes. Among the five backfilling scenarios, the major principal stress and stress concentration factor (SCF) have almost the same final results. The backfilling scenario SCN-1 is the optimum option among these five backfilling scenarios. It can immediately prevent the increase of the displacement and reduce the sidewall stress concentration, thereby preventing possible failures. Using the same strength of CRF can achieve same effects among the four mining levels. Applying backfilling CRF of the same strength at different mining depths is acceptable and feasible to improve the stability of the stopes.
ARTICLE | doi:10.20944/preprints201902.0230.v1
Subject: Physical Sciences, Fluids And Plasmas Physics Keywords: Two-phase flow, Sand concentration, PVC and PP 90-degree elbow, Pressure drop, Minor head losses, Mathematical model
Online: 25 February 2019 (14:35:40 CET)
The article presents the results of tests of minor head losses through PVC and PP elbows for a flow of water and mixtures of water and sand with grain sizes of up to 0.5 mm and concentrations of 5.6 g∙L-1, 10.84 g∙L-1, and 15.73 g∙L-1. The tests were carried out at variable flow velocities for three elbow diameters of 63, 75, and 90 mm. The flow rate, pressure difference in the tested cross-sections, and temperature of the fluids were measured and automatically recorded. The results of the measurements were used to develop mathematical models for determining the minor head loss coefficient as a function of elbow diameter, sand concentration in the liquid, and Reynolds number. The mathematical model was developed by cross validation. It was shown that when the concentration of sand in the liquid was increased by 1.0 g∙L-1, the coefficient of minor head loss through the elbows increased, in the Reynolds number range of 4.6∙104 − 2.1∙105, by 0.3−0.01% for PP63, 0.6−0.03 % for PP75, 1.1−0.06 % for PP90, 0.8−0.01 % for PVC63, 0.8−0.02 % for PVC75, and 0.9−0.04 % for PVC90. An increase in Re from 5∙104 to 2∙106 for elbows with diameters of 63, 75 and 90 mm caused a 7.3 %, 6.8 %, and 6.0 % decrease in the minor head loss coefficient, respectively.
REVIEW | doi:10.20944/preprints202307.1238.v1
Subject: Engineering, Chemical Engineering Keywords: thorium removing; thorium recovery, thorium recycling; thorium separation, thorium transport; thorium separation; thorium membrane separation; thorium membrane concentration; thorium determination
Online: 18 July 2023 (13:36:38 CEST)
Although a slightly radioactive element, thorium is considered very toxic because its various species, which reach the environment, can constitute an important problem for the health of the population. The present paper aims to expand the possibilities of using membrane processes in the removal, recovery and recycling of thorium from industrial residues reaching the municipal waste processing platforms. The paper includes a short introduction on the interest shown for this element, a weak radioactive metal, followed by highlighting of some common (domestic) uses. In a distinct but concise part, the bio-medical impact of thorium is presented. The classic technologies for obtaining thorium are concentrated in a single schema, and then the speciation of thorium is presented with an emphasis on the formation of hydroxo-complexes and complexes with common organic reagents. The determination of thorium has been highlighted both on the basis of its radioactivity, but especially through methods that call for extraction followed by an established electrochemical, spectral or chromatographic method. Membrane processes are presented based on the electrochemical potential difference, rapidly presenting barro-membrane processes, electrodialysis, liquid membranes and hybrid processes. A separate sub-chapter is devoted to proposals and recommendations for the use of membranes in order to achieve some progress in urban mining for the valorization of thorium.
ARTICLE | doi:10.20944/preprints202110.0225.v1
Subject: Computer Science And Mathematics, Geometry And Topology Keywords: Function Representation; implicit functions; geometry and topology; 3D bioprinting; tissue spheroids; modeling and simulation; diffusion-concentration calculations; cellular necrosis; additive technologies
Online: 15 October 2021 (12:26:09 CEST)
We propose a non-invasive approach to control the quality of spheroids and their fusion into a complex bioconstruct. The proposed method is based on the union of the nutrient concentration change calculated using Fick's law and the "reaction-diffusion" equations, taking into account absorption coefficient with specifying the exact fusion geometry using implicit Function Repre-sentation (FRep) functions. The proposed approach allows us to analyze the viability of cells within the spheroid, predict the fusion of spheroids, and accurately model complex heteroge-neous biostructures as a future task for our research. These results will significantly accelerate the development of such a promising field of additive biotechnologies as 3D bioprinting.
ARTICLE | doi:10.20944/preprints202202.0194.v1
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: antifungal resistance; isavuconazole; cystic fibrosis; pulmonary disease; Aspergillus fumigatus; pulmonary aspergillosis; respiratory disease; antifungal stewardship; therapeutic drug monitoring; minimum inhibitory concentration (MIC)
Online: 16 February 2022 (05:12:39 CET)
Background: The burden of resistant fungal infection is rising in patients with pulmonary disease. Options for antifungal therapy are limited, and the only orally-available antifungals, the triazoles, demonstrate inter and intra-patient variability, non-linear kinetics, toxicity, drug interactions and increasing antifungal resistance. Therapeutic drug monitoring (TDM) of itraconazole, voriconazole and posaconazole has been necessary to ensure their safety and efficacy, but is considered unnecessary for the newest triazole isavuconazole, use of which is increasing. Aims: To characterise isavuconazole susceptibility of Aspergillus fumigatus isolates in a tertiary respiratory referral centre to understand prevalence of isavuconazole antimicrobial resistance. To retrospectively review experience of isavuconazole use in this setting, assessing tolerability and therapeutic drug monitoring. Methods: A retrospective observational analysis of adult patients with respiratory disease in a tertiary hospital setting between Sept 2016 and Aug 2021. Clinical cultures were collected and triazole Minimum inhibitory concentration (MIC) were recorded (based on Clinical & Laboratory Standards Institute (CLSI method)). Isavuconazole trough drug levels were carried out as part of the standard of care. Clinical outcomes of treatment were evaluated, along with drug tolerance and TDM. Results: During the study period, isavuconazole susceptibility testing was performed on 26 Aspergillus spp isolates. 80.8% of Aspergillus fumigatus isolates were non-wild type and had isavuconazole MIC > 1mg/L, and 73.0% had MIC above the EUCAST (European Committee on Antimicrobial Susceptibility Testing) epidemiological cut-off (ECOFF) of 2mg/L. There was good correlation between isavuconazole MIC and voriconazole MIC (r =0.7, p=0.0002). 54 patients had isavuconazole therapy over the study period with a median duration of 7.7 months (IQR 0.79 - 16.42). 67% of patients were able to tolerate isavuconazole, despite toxicity with prior azole treatment being the primary indication for use (in 61.8%). Increased age (r=0.29; p=0.03 (95%CI 0.02,0.52)) and gender (r for female sex=-0.31; p=0.027 (95%CI -0.52,0.036) were associated risk factors for development of adverse events (AEs). 127 Isavuconazole TDM levels were performed over the study period with 90% >1mg/L and 72% >2mg/L. Dose change from manufacturer’s dose recommendation, however, was required in 15% of patients to achieve a serum drug concentration above the EUCAST ECOFF or Area of technical uncertainty (ATU) value of 2mg/L. Conclusion: In our study, we show use of Isavuconazole as salvage therapy in chronic pulmonary fungal disease setting with high prevalence of azole resistance. Isavuconazole MICs demonstrated good correlation with voriconazole MICs suggesting the latter could be a useful surrogate marker for isavuconazole susceptibility. Although Isavuconazole achieved excellent serum drug concentrations at standard dose compared to other azole drugs, we highlight the importance of antifungal stewardship and TDM monitoring to optimise therapy in this setting.