ARTICLE | doi:10.20944/preprints201608.0140.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: silicon pressure sensor; shield layer; stability
Online: 13 August 2016 (10:47:16 CEST)
This paper presents a piezoresistive pressure sensor with a shield layer for improved stability. Compared with the conventional piezoresistive pressure sensors, p-type piezoresistors are covered by an n-type shield layer, which is formed by ion implantation. The proposed pressure sensors have been successfully fabricated by bulk micromachining techniques. The impact of electrical field on piezoresistors is studied by simulation. The temperature drift of the pressure sensor has been investigated by both simulation and experimental measurement. Characteristics of developed pressure sensors are tested from -40 C to 125 C. A sensitivity of 0.022 mV/V/KPa and a maximum non-linearity of 0.085% FS are measured for the fabricated sensor in a pressure range of 1 MPa. The temperature coefficients of resistance of shielded piezoresistors are found to be smaller than those of un-shielded ones. It is demonstrated that the shield layer is able to reduce the drift caused by electrical field and ambient temperature variation.
ARTICLE | doi:10.20944/preprints202305.1158.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: leak identification; pressure sensor deployment; water distribution networks
Online: 16 May 2023 (10:53:02 CEST)
Pipe leakage is an inevitable phenomenon in water distribution networks (WDNs), leading to energy waste and economic damage. Leakage events can be reflected quickly by pressure values, and the deployment of pressure sensors is significant for minimizing the leakage ratio of WDNs. Concerning the restriction of realistic factors, including project budgets, available sensor installation locations, and sensor fault uncertainties, a practical methodology is proposed in this paper to optimize pressure sensor deployment for leak identification in terms of these realistic issues. Two indexes are identified to evaluate the leak identification ability, that is, detection coverage rate (DCR) and total detection sensitivity (TDS), and the principle is to determine priority to ensure an optimal DCR and retain the largest TDS with an identical DCR. Leakage events are generated by a model simulation and the essential sensors for maintaining the DCR are obtained by subtraction. In the event of a surplus budget, and if we suppose the partial sensors have failed, then we can determine the supplementary sensors that can best complement the lost leak identification ability. Moreover, a typical WDN Net3 is employed to show the specific progress, and the result shows that the methodology is largely appropriate for real projects.
ARTICLE | doi:10.20944/preprints202007.0629.v1
Subject: Engineering, Automotive Engineering Keywords: smart textiles; pressure sensor; concussion detection; Velostat; football helmet; head impacts
Online: 26 July 2020 (02:34:43 CEST)
A Mild traumatic brain injury (mTBI) or concussion has become a public health problem in the United State. Sports and recreational activities are major sources of concussions; with the most incidents connected to American football. Recently, many companies and research institutions have started studying concussions and introduced some means of protection and some alarming systems of strong jolts. The major detection and protection system currently available on the market is the electronic helmet (e-helmet) composed of measurement devices to record head impact acceleration. The most commonly used devices in e-helmets are accelerometers to measure linear acceleration and gyroscopes for rotational/angular acceleration. Using smart textiles for concussion detection is currently uncommon and limited due to the lack of literature studying their voltage related errors. Actually, there are few works that characterize some voltage-force related errors for such type of sensors but for small impact forces and under bench testing while the behavior of those sensors was not described for higher ranges of applied forces and in field situations. This paper previews some common techniques used in e-helmets for concussion detection and highlights electronic textiles and smart fabric sensors that could be very useful for these applications. It discusses and validates the general behavior of such type of sensors under high impact forces and on field testing instead of bench testing, and also it characterizes the effect of increasing the thickness of the sensing element layer on the sensor. A custom-made pressure sensor was created of some available fabrics to be embedded within the padding of a football helmet to quantify the impacting force to the head. The sensor is mainly composed a Semi Conductive Polymer Composite SCPC layer with modifiable thickness that was modified three times with 0.2, 0.4, and 1.6mm to characterize the general behavior of the sensor due to a high amount of impacts and correlated with the thickness. A pendulum system was built to test the pressure sensors, while a special camera and an open-source video analysis software, Tracker was used to track the pendulum bob. The speed and the acceleration of the pendulum bob were measured, then the impact force was calculated and a voltage-force response was obtained. The results showed that no meaningful improvement occurs by small increase in the thickness but better sensor behavior could be obtained by significant increment to observe any difference. Despite that at a very high impacts, the suggested sensor with Velostat layers is not giving the real voltage readings that reflect the actual applied forces but it gives a helpful information that illustrate the distribution of the force through identification the place of the highest and lowest voltage readings regardless of the exact values of those readings. However, the proposed smart textile pressure sensor could be applicable in future e-helmet designs with additional research-based improvements especially on the structure of the sensing element layer to be able to withstand such high impacts which in turns improves the overall sensor performance and accurately measures pressure in concussion-inducing ranges.
ARTICLE | doi:10.20944/preprints202309.0703.v1
Subject: Public Health And Healthcare, Physical Therapy, Sports Therapy And Rehabilitation Keywords: ankle pump movement; ankle joint flexion and extension movement monitoring; pressure sensor; STM32
Online: 12 September 2023 (04:46:28 CEST)
Ankle joint flexion and extension exercises play an important role in the rehabilitation training of patients who have been injured or bedridden for a long time before and after surgery. Accurately guiding patients to perform ankle flexion and extension exercises can significantly reduce deep vein thromboembolism. Currently, most ankle rehabilitation devices focus on assisting patients with ankle flexion and extension movements, and there is a lack of devices for effectively monitoring these movements. In this study, we designed an ankle joint flexion and extension movement monitoring device based on a pressure sensor. It is composed of an STM32 microcontroller, a pressure sensor, an HX711A/D conversion chip, and an ESP8266 WiFi communication module. The value of force and effective number of ankle joint flexion and extension movements were obtained. An experimental device was designed to verify the accuracy of the system. The results showed that the device can effectively monitor and control ankle flexion and extension movements remotely, ultimately ensuring that the patient can effectively monitor and grasp the active ankle pump movement.
ARTICLE | doi:10.20944/preprints202305.2025.v1
Subject: Physical Sciences, Optics And Photonics Keywords: Annular photonic crystal; polymer material; transfer matrix method; pressure sensor; sensitivity
Online: 30 May 2023 (03:19:51 CEST)
This study aims to theoretically address the design and analysis of an efficient pressure sensor designed by using a polymer-based defective 1D annular photonic crystal (APC). The 1D APC comprises an alternate arrangement of Si and SiO2 in a cylindrical fashion, incorporating a central defect layer. The investigation of the reflectance characteristics of the proposed structure is conducted by separately considering the polystyrene (PS) and the polymethyl methacrylate (PMMA) polymer materials as the defect layer. The pressure-sensitive refractive index of the polymers and the constituent materials of the APC plays a vital role in envisaging the pressure-sensing application. The cornerstone of this study is represented by the shift analysis in the wavelength of the defect mode inside the band gap using different applied pressures by employing the modified transfer matrix method (MTMM). Various geometrical parameters like the defect polymer layer’s thickness and the APC period were carefully optimized to achieve higher sensing performance. The proposed design demonstrated a remarkable pressure sensitivity and FoM of 51.29 nm/GPa and 301.7 GPa-1, respectively, which is considerably high in the current research scenario. It is believed that the proposed structure can be an apt candidate as an innovative high-performance pressure sensor, and it can play a key role in photonic integrated circuits.
ARTICLE | doi:10.20944/preprints202109.0385.v1
Subject: Engineering, Automotive Engineering Keywords: Wireless Sensors Networks; Fiber Bragg Grating; Pressure; Speed; Wheelbase distance; Weight; Vehicle; Identification.
Online: 22 September 2021 (13:27:42 CEST)
Due to the renewed variation in government and political systems inside and outside countries, and with the high tariffs at borders, the latter have become an outlet for terrorism and smugglers. Therefore, each country seeks to develop its own protection system, and the technologies used in these systems vary according to the severity and the importance of the installations to be protected, it is found that some of them are expensive and unnecessary, but other have good and variable levels of efficiency. Consequently, the idea of designing a surveillance system that can monitor and control access becomes indispensable. In the same context, this work is of crucial strategic and geopolitical importance. It combines pre-existing alarm and monitoring methods and revolutionary Internet of Things (IoT) application products, of which Wireless Sensor Networks (WSN) and Optical Fiber Sensors (OFS) are part of this application. This article presents the distribution of wireless radar nodes accompanying with a Bragg fiber sensor to identify each rolling intruder incoming the zone to be monitored, from the determination of its speed, weight and wheelbase distance.
ARTICLE | doi:10.20944/preprints201807.0107.v1
Subject: Chemistry And Materials Science, Other Keywords: RF MEMS; pressure sensor; MEMS resonators; implantable BioMEMS; flexible electronics; touch mode capacitive sensor
Online: 6 July 2018 (07:42:03 CEST)
This paper reports the novel design of a touch mode capacitive pressure sensor (TMCPS) system with a wireless approach for a full-range continuous monitoring of ventricular pressure. The system consists of two modules: an implantable set and an external reading device. The implantable set, restricted to a 2x2 cm2 area, consists of a TMCPS array connected with a dual-layer coil, for making a reliable resonant circuit for communication with the external device. The capacitive array is modelled considering the small deflection regime for achieving a dynamic and full 5-300 mmHg pressure range. In this design, the two inductive-coupled modules are calculated considering proper electromagnetic alignment, based on two planar coils and considering the following: 13.56 MHz frequency to avoid tissue damage and three types of biological tissue as core (skin, fat and muscle). The system was validated with the Comsol Multiphysics and CoventorWare softwares; showing a 90% power transmission efficiency at a 3.5 cm distance between coils. The implantable module includes aluminum- and polyimide-based devices, which allows ergonomic, robust, reproducible, and technologically feasible integrated sensors. In addition, the module shows a simplified and low cost design approach based on PolyMEMS INAOE® technology, featured by low-temperature processing.
ARTICLE | doi:10.20944/preprints202111.0041.v1
Subject: Medicine And Pharmacology, Other Keywords: Obstructive sleep apnea; Continuous positive airways pressure therapy; Near-infrared spectroscopy; Oxygen desaturation; Arm; Pulse oximeter
Online: 2 November 2021 (10:52:45 CET)
Obstructive sleep apnea (OSA) is a common sleep disorder, and continuous positive airways pressure (CPAP) is the most effective treatment. Poor adherence is one of the major challenges in CPAP therapy. The recent boom of wearable optical sensors measuring oxygen saturation makes the at-home multiple-night CPAP titrations possible, which may essentially improve the adherence of CPAP therapy by optimizing its pressure in a real-life setting economically. We tested whether the oxygen desaturations (OD) measured in the arm muscle (arm_OD) by gold-standard frequency-domain multi-distance near-infrared spectroscopy (FDMD-NIRS) changes with titrated CPAP pressures in OSA patients together with polysomnography. We found that the arm_OD (2.08 ± 1.23%, mean ± standard deviation) was significantly smaller (P-value <0.0001) than the fingertip OD (finger_OD) (4.46 ± 2.37%) measured by polysomnography pulse oximeter. Linear mixed-effects models suggested that CPAP pressure was a significant predictor for finger_OD but not for arm_OD. Since FDMD-NIRS measures a mixture of arterial and venous OD, whereas fingertip pulse oximeter measures arterial OD, our results of no association between arm_OD and finger_OD indicate that the arm_OD mainly represented venous desaturation. Arm_OD measured by near-infrared optical sensors may be not a suitable indicator of the effectiveness of CPAP titration.
ARTICLE | doi:10.20944/preprints202301.0007.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: systolic blood pressure; diastolic blood pressure; GWAS; high blood pressure; multivariate; univariate
Online: 3 January 2023 (07:28:58 CET)
Background: High blood pressure (BP) has been implicated as a major risk factor for cardiovascular diseases in several global populations, including in individuals of African ancestry. Despite the elevated burden of high BP-induced cardiovascular diseases in Africa and other global populations with African ancestry, limited genetic studies have been carried out to explore the genetic machinery driving this phenomenon. Methods: We performed univariate and multivariate analyses using Genome-wide association studies (GWAS) and summary statistics data of 77,850 individuals of African ancestry for systolic (SBP) and diastolic blood pressure (DBP) traits. The six independent cohorts used included individuals derived from the African Partnership for Chronic Disease Research (APCDR), the UK Biobank, and the Million Veteran Program (MVP). Subsequently, we annotated, prioritized, visualized, and interpreted our meta-analyses results using FUMA, to gain further insight into the molecular mechanism(s) that contribute to the genetics of BP traits. Finally, loci attaining genome-wide significance, GWS (p<5x10-8) were also followed up with Bayesian fine-mapping to identify potential causal variants. Results: Our meta-analyses altogether identified 350 GWAS SNPs for SBP (166 SNPs) and DBP (184 SNPs, including two novel loci) whilst our multivariate GWAS method identified 166 SNPs (including three novel loci). Interestingly, in FUMA there was significant tissue enrichment of up-regulated differentially expressed genes (DEGs) in the sigmoid and transverse colon for SBP, as well as 10 significant gene sets from MAGMA gene set analyses, However, for DBP, no significant DEGs nor gene sets in MAGMA were found; instead, in DBP for gene property analysis for tissue specificity nine candidates were found to be significant and all nine were in different brain regions. Finally, Bayesian fine-mapping revealed that only 11 variants from the lead SNPs had >50% posterior probability (PP) of being causal and they included novel variant rs562545 (MOBP, PP = 77%) and 10 other previously published variants. Conclusion: Our results demonstrate the importance of performing GWAS in large sample sizes of global populations of African ancestry, including continental Africans; which yield novel insights, from novel loci to novel pathways/tissue expression candidates. Large-scale genomic datasets are required to enhance further discovery and fine-mapping of high-risk loci/variants in highly susceptible groups for cardiovascular disease and other related traits. Our study highlights the need for diversity in genetic research and the importance of expanding large GWASs to include ancestrally diverse populations.
ARTICLE | doi:10.20944/preprints201801.0100.v1
Subject: Medicine And Pharmacology, Clinical Medicine Keywords: intra-abdominal pressure; abdominal compartment syndrome; pressure sensor; negative pressure wound therapy; open abdomen;
Online: 11 January 2018 (09:17:10 CET)
1) Introduction: Negative pressure wound therapy (NPWT) is a frequently applied open abdomen (OA) treatment. There are only a few experimental data supporting this method and describing the optimal settings and pressure distribution in the abdominal cavity during this procedure. The aim of our study was to evaluate pressure values at different points of the abdominal cavity during NPWT in experimental abdominal compartment syndrome (ACS) animal model. 2) Methods: In this study (permission Nr. 13/2014/UDCAR) 27 Hungahib pigs (15.4- 20.2 kg) were operated. ACS was generated by implanting a plastic bag in the abdomen through mini-laparotomy and filled with 2100- 3300 ml saline solution (37 C°) to an intraabdominal pressure (IAP) of 30 mmHg. After 3 hours, NPWT (Vivano Med ® Abdominal Kit, Paul Hartmann AG, Germany) or Bogota bag was applied. NPWT group was divided into -50, -100 and 150 mmHg suction group. Pressure distribution to the abdominal cavity was monitored at 6 different points of the abdomen via a multichannel pressure monitoring system. 3) Results: The absolute pressure levels were significantly higher above than below the layer. The values of the pressure were similar in the midline than laterally. Amongst the bowels, the pressure values changed periodically between 0 and -12 mmHg which might be caused by the peristaltic movements. 4) Conclusions: The porcine model of the present study seems to be well applicable for investigating ACS and NPWT. It was possible to provide valuable for clinicians. The pressure was well distributed by the protective layer to the lateral parts of the abdomen and this phenomenon did not change considerably during the therapy.
ARTICLE | doi:10.20944/preprints202106.0571.v2
Subject: Medicine And Pharmacology, Ophthalmology Keywords: glaucoma progression; nycthemeral intraocular pressure; mean ocular perfusion pressure
Online: 1 July 2021 (11:08:41 CEST)
Purpose: Nycthemeral (24-hour) glaucoma inpatient intraocular pressure (IOP) monitoring has been used in Europe for more than 100 years to detect peaks missed during regular office hours. Data supporting this practice is lacking, partially because it is difficult to correlate manually drawn IOP curves to objective glaucoma progression. To address this, we deployed automated IOP data extraction tools and tested for a correlation to a progressive retinal nerve fiber layer loss on spectral-domain optical coherence tomography (SDOCT). Methods: We created and deployed a machine-learning image analysis software to extract IOP data from hand-drawn, nycthemeral IOP curves of 225 retrospectively identified glaucoma patients. The relationship between demographic parameters, IOP and mean ocular perfusion pressure (MOPP) data to SDOCT data was analyzed. Sensitivities and specificities for the historical cut-off values of 15 mmHg and 22 mmHg in detecting glaucoma progression were calculated. Results: IOP data could be extracted efficiently. The IOP average was 15.2±4.0 mmHg, nycthemeral IOP variation was 6.9±4.2 mmHg, and MOPP was 59.1±8.9 mmHg. Peak IOP occurred at 10 AM and trough at 9 PM. Disease progression occurred mainly in the temporal-superior and -inferior SDOCT sectors. No correlation could be established between demographic, IOP, or MOPP parameters and SDOCT disease progression. The sensitivity and specificity of both cut-off points (15 and 22 mmHg) were insufficient to be clinically useful. Outpatient IOPs were non-inferior to nycthemeral IOPs. Conclusion: IOP data obtained during a single visit make for a poor diagnostic tool, no matter whether obtained using nycthemeral measurements or during outpatient hours.
REVIEW | doi:10.20944/preprints201908.0052.v2
Subject: Public Health And Healthcare, Nursing Keywords: pressure ulcer; pressure injury; decubitus ulcer; position change; Ethiopia
Online: 3 November 2019 (15:10:34 CET)
Background: Pressure ulcers (PU) aﬀect millions of people worldwide and always occur over bony areas of the body where pressure and tissue distortion is greatest. The national pooled prevalence of pressure ulcer remains unknown. Hence, the aim of this meta-analysis was to determine the effect of position change on pressure ulcer among hospitalized clients in Ethiopia. Methods: Studies were retrieved through search engines in PubMed, Scopus, WHO afro library, Google Scholar, Africa journal online, PsycINFO and web-science following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P). Analysis was done using STATA version 14 software. We checked the between-study heterogeneity using the I2 and examined a potential publication bias by visual inspection of the funnel plot and Egger’s regression test statistic. The random-effect model was fitted to estimate the summary effects, odds ratios (ORs), and 95% confidence interval (CIs) across studies. Results: Out of the reviewing 401 studies, 7 studies fulfilled the inclusion criteria and were included in the meta-analysis. The estimated pooled prevalence of pressure ulcer in Ethiopia was 11.7% (95% CI (7.28, 16.13%)). Based on the subgroup analysis, the estimated magnitude of pressure ulcer was 15.89% (95% CI: 35.34, 54.04) among studies their sample size were greater than or equals to 250. Those clients who have position change during hospitalization were 85% less likely to develop pressure ulcer [(OR 0.15, 95%CI (0.06, 0.4)] than their counter part. Conclusion: The overall prevalence of pressure ulcer in Ethiopia was relatively high. Position change of the client during hospitalization had paramount benefit to reduce the burden of pressure ulcer. Therefore, policymakers could give special attention to minimize the magnitude of pressure ulcer in order to improve the overall quality of healthcare service. Further meta-analysis study is need to identify individual and health care service related factors to the occurrence of pressure ulcer.
ARTICLE | doi:10.20944/preprints202308.1445.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Counter diffusion method; Confining pressure; Gas pressure; Temperature; Diffusion coefficient
Online: 22 August 2023 (02:32:47 CEST)
The diffusion coefficient (D) is a key parameter characterizing gas transport in coal seams. Usually, the D is calculated from the desorption curve of particle coal, which cannot accurately reflect the diffusion characteristics under the stress constraint conditions of in-situ coal seams. In this paper, based on Fick's law of counter diffusion, different metamorphic deformed coals of medium and high coal rank are taken as the research object. The change laws of D under different confining pressure, gas pressure, and temperature conditions are tested and analyzed, and the influencing mechanisms on the D are discussed. The results show that the D of different metamorphic deformed coals decreases exponentially with the increase of confining pressure, and increases exponentially with the increase of gas pressure and temperature. There is a limit diffusion coefficient. The influence of confining pressure on the D is essentially determined by the change of effective stress, and the D has a negative effect of effective stress similar to permeability. The effect of gas pressure on the D involves two mechanisms, namely, mechanical and adsorption effects, which are jointly restricted by effective stress and coal particle shrinkage and expansion deformation. The effect of temperature on the D is mainly achieved by changing the root mean square speed and average free path of gas molecules. Under the same temperature and pressure conditions, the D increases first and then decreases with the increase of deformation degree, and the D of fragmented coal is the largest. Under similar deformation conditions, the D of high-rank anthracite is greater than that of medium-rank fat coal. It is considered that porosity is the key factor affecting the change of D in different metamorphic deformed coals.
REVIEW | doi:10.20944/preprints202007.0489.v1
Subject: Chemistry And Materials Science, Inorganic And Nuclear Chemistry Keywords: High pressure X-ray crystallography; high pressure magnetometry; high pressure absorption spectroscopy; high pressure EPR; molecule-based magnets; single-molecule magnets; single-ion magnets
Online: 21 July 2020 (12:48:58 CEST)
The cornerstone of molecular magnetism is a detailed understanding of the relationship between structure and magnetic behaviour, i.e. the development of magneto-structural correlations. Traditionally, the synthetic chemist approaches this challenge by making multiple compounds that share a similar magnetic core but differ in peripheral ligation. Changes in the ligand framework induce changes in the bond angles and distances around the metal ions which are manifested in changes to magnetic susceptibility and magnetisation data. This approach requires the synthesis of series of different ligands and assumes that the chemical/electronic nature of the ligands and their coordination to the metal, the nature and number of counter ions and how they are positioned in the crystal lattice, and the molecular and crystallographic symmetry have no effect on the measured magnetic properties. In short, the assumption is that everything outwith the magnetic core is innocent, which is a huge oversimplification. The ideal scenario would be to have the same complex available in multiple structural conformations, and this is something that can be achieved through the application of external hydrostatic pressure, correlating structural changes observed through high pressure single crystal X-ray crystallography with changes observed in high pressure magnetometry, in tandem with high pressure inelastic neutron scattering (INS), high pressure electron paramagnetic resonance (EPR) spectroscopy and high pressure absorption/emission/Raman spectroscopy. In this review, which summarises our work in this area over the last 15 years, we show that the application of pressure to molecule-based magnets can (reversibly): (1) lead to changes in bond angles, distances and Jahn-Teller orientations; (2) break and form bonds; (3) induce polymerisation/depolymerisation; (4) enforce multiple phase transitions; (5) instigate piezochromism; (6) change the magnitude and sign of pairwise exchange interactions and magnetic anisotropy and (7) lead to significant increases in magnetic ordering temperatures.
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: Limited current O2 sensor; YDC solid electrolyte; ZDC dense diffusion barrier; Water vapor pressure
Online: 5 June 2019 (10:33:25 CEST)
Using co-precipitation to synthesize (CeO2)0.95(Y2O3)0.05 (YDC) and solid reaction method to synthesize (CeO2)0.75(ZrO2)0.25 (ZDC), and the characterization for both crystal structure and micro-structure of the two materials was conducted with X-ray diffraction (XRD) and scanning electron microscope (SEM) methods. Prepare the YDC and ZDC based limited current O2 sensor by employing platinum pasting bonding method. Sensing characteristics of the sensor were obtained at different conditions and study on the impact of temperature, O2 concentration as well as water vapor pressure on the sensing characteristics had been conducted. XRD results show that the phase structure of both YDC and ZDC is cubic phase. SEM results show that both YDC and ZDC layers are dense layers, which are then qualified to be the composition materials of the sensor. This limited current O2 sensor shows good sensing performance and conforms to the Knudsen model. Log(IL•T) depends linearly on 1000/T with R2 of 0.9904, IL depends linearly on x(O2) with R2 of 0.9726 and sensing characteristics are not affected by p(H2O).
ARTICLE | doi:10.20944/preprints202309.0831.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: Low-pressure powder injection molding; metallic powder; numerical simulation; injection pressure
Online: 13 September 2023 (07:58:07 CEST)
Controlling injection parameters is paramount when it comes to producing high-quality green parts using powder injection molding. This work combines experimental and numerical approaches to study the impact of injection parameters on mold in-cavity pressure and on the overall quality of green parts produced by low-pressure powder injection molding. The properties of two low-viscosity feedstocks (formulated from a water-atomized stainless-steel powder and wax-based binder system) were measured and implemented in an Autodesk Moldflow numerical model to quantify the molding pressures, which were finally validated using experimental real-scale injections. The results confirmed that an increase in mold temperature, an increase in feedstock temperature, and a decrease in solid loading decrease the mold in-cavity pressure, which was correlated with the feedstock viscosity. As a key result, real-scale injections confirmed that a minimum flow rate was required to avoid atypical high in-cavity pressure leading in several visual defects such as weld lines, flow marks, cracks, sinks, and incomplete filling. Due to differences in its thermal transfer properties, this flow rate threshold value decreases as the feedstock solid loading increases. For injection speeds higher than this value, the injection pressure measured experimentally was linearly correlated with the injection flow rate.
ARTICLE | doi:10.20944/preprints202305.1333.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: Continuous blood pressure measurement; MEMS pressure sensor; Flexible packaging; Machine learning
Online: 18 May 2023 (10:42:15 CEST)
In order to realize the accurate measurement of wearable sphygmomanometer, this paper selects the micro electro mechanical system (MEMS) pressure sensor with small size, low cost and high accuracy, and proposes a flexible packaging method combining Parylene and Polydimethylsiloxane (PDMS). The flexible packaging sensor protects the sensor chip while ensuring the comfort of the measured person. It can be worn for a long time, and the encapsulated sensor has good accuracy and sensitivity. At the same time, the encapsulated MEMS pressure sensor was used to collect good pulse signals and extract multiple pulse wave characteristic parameters. A blood pressure measurement method based on the combination of arterial tonometry method and pulse wave parameters method was proposed, and multiple machine learning algorithms were compared and analyzed to select the algorithm model with the smallest error as the optimal regressor. The experimental results show that the blood pressure measurement method combining the arterial tonometry method and the pulse wave parameters method can effectively improve the accuracy of blood pressure measurement. The experimental results demonstrate that the combination of arterial tonometry and pulse wave parameter methods can effectively enhance the accuracy of blood pressure measurement, with the random forest model serving as the optimal regressor. The average deviation between the systolic blood pressure measured by our self-made sphygmomanometer and the commercial sphygmomanometer was 0.86mmHg, with a standard deviation of 4.04mmHg. The average deviation of diastolic blood pressure was 0.63mmHg, with a standard deviation of 5.15mmHg, meeting the AAMI standard for clinical practice.
ARTICLE | doi:10.20944/preprints202212.0174.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: high-pressure water jet; high-pressure abrasive water- jet; rock processing
Online: 9 December 2022 (09:22:30 CET)
Rocks are materials with a wide variety of structures and properties. These can be unprocessed conglomerates of conglomerated minerals as well as crystallized outcrop or metamorphic rocks. Their processing, especially shaping, poses many technological difficulties. Therefore, it is very important to answer the question of how these natural materials yield to high-pressure water jet and abrasive water. It is equally important to determine the effect of key process parameters such as pressure, water nozzle diameter and feed rate on cutting efficiency. The first two parameters determine the water output and power of the jet, while the third determines the jet erosion time per unit volume of material. Their interdependence, using appropriate evaluation indicators, allows to determine the energy intensity of processing and directions for its minimization.
ARTICLE | doi:10.20944/preprints202109.0528.v1
Subject: Public Health And Healthcare, Public, Environmental And Occupational Health Keywords: black carbon; systolic blood pressure; diastolic blood pressure; sex; obesity; traffic enforcers
Online: 30 September 2021 (16:08:10 CEST)
Exposure to traffic-related air pollution is linked with acute alterations in blood pressure (BP). We examined the cumulative short-term effect of black carbon (BC) exposure on systolic (SBP) and diastolic (DBP) BP and assessed effect modification by participant characteristics. SBP and DBP were repeatedly measured on 152 traffic enforcers. Using a linear mixed-effects model with random intercepts, quadratic (QCDL) and cubic (CCDL) constrained distributed lag models were fitted to estimate the cumulative effect of BC concentration on SBP and DBP during the 10-hours (daily exposure) and 7-days (weekly exposure) before the BP measurement. Ambient BC was related to increased BP with QCDL models. An interquartile range change in BC cumulative during the 7-days before the BP measurement was associated with increased BP [1.2% change in mean SBP, 95% confidence interval (CI), 0.1 to 2.3; and 0.5% change in mean DBP, 95% CI, –0.8 to 1.7]. Moreover, the association between the 10-hours cumulative BC exposure and SBP was stronger for females (4.0% change, 95% CI: 2.1–5.9) versus males, and for obese (2.9% change, 95% CI: 1.0–4.8) vs. non-obese traffic enforcers. Short-term cumulative exposure to ambient traffic-related BC could bring about cardiovascular diseases through mechanisms involving increased BP.
ARTICLE | doi:10.20944/preprints202112.0410.v2
Online: 5 January 2022 (10:36:30 CET)
Over the last two decades, microfluidics has received significant attention from both academia and industry, and researchers report thousands of new prototype devices each year for use in a broad range of environmental, pharmaceutical, and biomedical engineering applications. While lab-on-a-chip fabrication costs have continued to decrease, the hardware required for monitoring fluid flows within microfluidic devices themselves remains expensive and often cost prohibitive for researchers interested in starting a microfluidics project. As microfluidic devices become capable of handling complex fluidic systems, low-cost, precise and real time pressure and flow rate measurement capabilities has become increasingly important. While many labs use commercial platforms and sensor, these solutions can often cost thousands of dollars and can be too bulky for on-chip use. Here we present a new inexpensive and easy -to-use piezoresistive pressure and flow sensor that can be easily integrated into existing on-chip microfluidic channels. The sensor consists of PDMS-Carbon black conductive membranes and uses an impedance analyzer to measure impedance change due fluid pressure. The sensor costs several orders of magnitude less than existing commercial platforms and can monitor local fluid pressures and calculate flow rates based on pressure gradient.
ARTICLE | doi:10.20944/preprints202310.0746.v1
Subject: Engineering, Mechanical Engineering Keywords: terramechanics; sensors; tracked vehicle; ground pressure; soil bin; cone penetrometer; bearing capacity; pressure-sinkage
Online: 12 October 2023 (05:07:43 CEST)
Tracked vehicles play a significant role in engineering. Supportive trafficability is the salvation of any tracked vehicle. Terrain characteristics have a substantial impact on tracked vehicle mobility. We consider a tracked vehicle traversing known terrain in this paper. Vehicle-terrain interaction covers track-soil friction, soil compaction, traction, bearing capacity, and sinkage resistance. Identifying the soil parameters upon which a tracked vehicle moves will likely lead to more accurate traversability predictions, better traction control, and more accurate trajectory tracking. Conventional terramechanical models cannot adequately describe the connection between tracks and soil. Obtaining real-time measurements of the ground pressure of the soil as the unmanned tracked vehicle moves in the soil bin of dimensions 610 cm long, 245 cm wide, and 180 cm deep is challenging. The utilization of real-time data enables monitoring dynamic variations in ground pressure exerted by the operational components within a soil bin. A ground pressure monitoring device suitable for wet and dry soil was designed to reduce the accumulation of choked damp soil, clay, or mud in the sensor, sensor bracket, track, and other equipment. The device uses a pressure sensor, a data logger, and wireless measurement technology. It can simultaneously measure up to 8 pressure sensors and transmit measurement data remotely to a computer. This reduces the labor intensity of measuring personnel in muddy soil. Data analysis showed that the crewless tracked vehicle’s ground pressure and forward resistance increased with forward speed and vertical load. A law was also discovered explaining how ground pressure (sinkage) spreads between the trackpad and the soil. A general technique is presented in this paper that can be applied to any tracked vehicle. The conclusions show that the ground pressure measurement system works steadily in different humidity scenarios. In addition, the data that has been gathered can be transmitted to a computer using wireless communication methods.
ARTICLE | doi:10.20944/preprints202307.1659.v1
Subject: Engineering, Civil Engineering Keywords: acid gas injection (AGI); saline aquifers; capillary pressure; reservoir characterization; caprock integrity; capillary pressure
Online: 25 July 2023 (07:39:38 CEST)
Approximately 2 TCF (Trillion Cubic Feet) of acid gas are projected to be injected into the Surmeh formation. The recommended injection rate is 180 MMSCFD (Million standard cubic feet per day), based on acid gas content and gas in place of the source of injection. The tight nature of the Surmeh formation limits injectivity, with a maximum achievable rate of 7 MMSCFD for permeability of 1 mD (millidarcy). However, higher porosity (12%) and permeability of 100 mD enable more efficient injection without fracturing the formation. This study provides valuable insights into the feasibility of AGI in saline aquifers, emphasizing reservoir characterization, geomechanics, caprock integrity, and rock properties. The findings contribute to the implementation of environmentally sustainable acid gas disposal at offshore reservoirs.
ARTICLE | doi:10.20944/preprints202304.0412.v1
Subject: Engineering, Mechanical Engineering Keywords: CTCS; Debris filter; Differential pressure; Fluid resistance; Pressure drop; Turbulence kinetic energy; Flow vortex
Online: 17 April 2023 (06:16:34 CEST)
In a power plant that uses seawater as a coolant, a debris filter is required to remove foreign substances from the seawater, and differential pressure leads to a decrease in the coolant flow rate, leading to a decrease in power generation efficiency. In this study, analysis was performed under different initial flow velocity conditions of 1.5m/s, 2.0m/s, and 2.5m/s for a debris filter used in a power plant to understand flow characteristics in CTCS. The flow and differential pressure characteristics of a CTCS with an installed debris filter were considered in a comparative analysis of velocity, pressure, and turbulent kinetic energy distribution. The results confirmed that a vortex was generated in the pipe with the debris filter, apparently due to the collision of the flow with the bracket of the debris filter. As the flow rate increased, the range of the vortex increased, causing a loss in flow.
ARTICLE | doi:10.20944/preprints202001.0310.v1
Subject: Computer Science And Mathematics, Applied Mathematics Keywords: mathematical modeling; characteristic points; extreme pressure; hydraulic jump; pressure fluctuations; standard deviation; stilling basin
Online: 26 January 2020 (07:32:50 CET)
Pressure fluctuations beneath hydraulic jumps downstream of Ogee spillways potentially damage stilling basin beds. This paper deals with the extreme pressures underneath free hydraulic jumps along a smooth stilling basin. The experiments were conducted in a laboratory flume. From the probability distribution of measured instantaneous pressures, the pressures with different non-exceedance probabilities (P*a%) could be determined. It was verified that the maximum pressure fluctuations, as well as the negative pressures, are located at the positions closest to the spillway toe. The minimum pressure fluctuations are located at the downstream of hydraulic jumps. It was possible to assess the cumulative curves of P*a% related to the characteristic points along the basin, and different Froude numbers. To benchmark, the results, the dimensionless forms of mean pressures, standard deviations, and pressures with different non-exceedance probabilities were assessed. It was found that an existing methodology can be used to interpret the present data, and pressure distribution in similar conditions, by using a new third-order polynomial relationship for the standard deviation (σ*X) with the determination coefficient (R2) equal to 0.717. It was verified that the new optimized adjustment gives more accurate results for the estimation of the maximum extreme pressures than the minimum extreme pressures.
ARTICLE | doi:10.20944/preprints202206.0017.v3
Subject: Medicine And Pharmacology, Internal Medicine Keywords: High-intensity interval training; Continuous aerobic training; Systolic blood pressure; Diastolic blood pressure; Pre-hypertension
Online: 13 July 2022 (09:21:03 CEST)
The likelihood of pre-hypertensive young adults developing hypertension has been steadily increasing over the past few years. Despite the fact that aerobic exercise training (AET) has demonstrated positive results in lowering high blood pressure, the efficacy of different types of AET among pre-hypertensive young adults has not been well-established. The objective of this study was to evaluate the effectiveness of high-intensity interval training (HIIT) and continuous moderate-intensity training (CMT) on blood pressure (BP) of physically inactive pre-hypertensive young adults. 32 adults (age 20.0±1.1 years and BMI 21.5±1.8) were randomly assigned into 3 groups: HIIT, CMT and control (CON). HIIT and CMT groups participated in 5 weeks of AET; while the CON group followed a DASH diet plan only. The HIIT protocol consisted of 1:4 minute work to rest ratio of participants 80%-85% heart rate reserve (HR-reserve) and 40%-60% HR-reserve respectively for 20-minutes, CMT group exercised at 40%-60% of HR-reserve continuously for 20-minutes. In both HIIT and CMT groups, systolic blood pressure (SBP) (3.8±2.8 mmHg, P=0.002 VS 1.6±1.5 mmHg, P=0.011) was significantly reduced. While, significant reductions in the diastolic blood pressure (DBP) (2.9±2.2 mmHg, P=0.002) and mean arterial pressure (MAP) (3.1±1.6mmHg, P<0.0005) were noted only in the HIIT group. No significant differences in SBP (-0.4±3.7 mmHg, P=0.718), DBP (0.4±3.4 mmHg, P=0.714), or MAP (0.1±2.5mmHg, P= 0.892) were observed in the CON group. Both HIIT and CMT decreased the BP in physically inactive pre-hypertensive young adults; however, HIIT yielded more beneficial results in terms of reducing the SPB, DBP and MAP.
ARTICLE | doi:10.20944/preprints202311.0398.v1
Subject: Physical Sciences, Thermodynamics Keywords: piezomagnetism; magnetostriction; electrostriction; piezoelectricity; pressure; thermodynamics
Online: 7 November 2023 (06:43:34 CET)
For paramagnetic and elastic materials in the presence of quasi-static magnetic field, there is correspondingly quasi-static magnetic pressure, in contrast to the radiational electromagnetic pressure associated with electromagnetic momentum density. A thermodynamic pressure demagnetization is demonstrated. For the elastic dielectrics in the presence of quasi-static electrical field, its dual effect can be easily obtained by variable transformation.
ARTICLE | doi:10.20944/preprints202309.1739.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: pressure temperature; ZnO; MD; Chemical Bonds
Online: 27 September 2023 (02:29:58 CEST)
Zinc oxide (ZnO) as a semiconductor in its crystalline or amorphous form is still a promised material, especially under isobaric and isothermal ensembles. In this work, Parallel and Equilibrium Molecular Dynamics and DL_POLY_4 software are employed to predict the relationship between the behavior of ZnO chemical bonds and the phase transition literatures, using correlation function g(r) of Zn-Zn, Zn-O, and O-O pairs. Our system is composed of 5832 atoms of ZnO rocksalt structure (2916 atoms of Zn2+ and 2916 atoms of O2-), under the temperature of 300 (K) and the range of pressure 0-400 (GPa). The lengths of ZnO bonds, the standard error, standard deviation, the maximum of g(r), and the percentage of the variation of the bonds are analyzed. The interatomic interactions are modeled by the potential of Buckingham for short-range and Coulomb for long-range interactions. The calculations were run on the RAVEN Supercomputer of Cardiff University (UK). Our data are mostly in the vicinity of available information of bonds lengths; the rest can be deduced from the pressure of phase transition to use it as a new approach of phase transition confirmation. However, the rest of our results are still a prediction because of no results under extended pressure used in this work.
ARTICLE | doi:10.20944/preprints202309.0528.v1
Subject: Engineering, Mechanical Engineering Keywords: Pressure-dependent Viscosity; Generalized Brinkman Equation
Online: 7 September 2023 (13:37:34 CEST)
Unidirectional flow of a fluid with pressure-dependent viscosity through a porous structure is considered when the viscosity-pressure relationship is an exponential function of a pressure power function in order to investigate effects of the viscosity-pressure relation on the flow characteristics. The flow is governed by the generalized Brinkman’s equation with constant permeability, and a model flow domain of flow down an inclined porous channel is chosen for the sake of studying flow behaviour. Although the current work considers flow in a constant permeability porous structure, it does represent a first step in studying the more general, flow through a variable permeability porous channel. The arising governing equations are solved numerically using MATLAB and the flow is simulated to illustrate the effects of fluid properties as well as flow and medium parameters on the velocity profiles and shear stress.
REVIEW | doi:10.20944/preprints202305.1981.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: Serotonin; CGRP; blood pressure; migraine; hypertension
Online: 29 May 2023 (05:42:58 CEST)
5-Hydroxytryptamine (5-HT) or serotonin plays a crucial role as a neuromodulator and/or neurotransmitter of several nervous system functions. Its actions are complex and depend on multiple factors, including the type of effector or receptor activated. Briefly, 5-HT can activate: (i) metabotropic (G-protein-coupled) receptors to promote inhibition (5-HT1, 5-HT5) or activation (5-HT4, 5-HT6, 5 HT7) of adenylate cyclase, as well as activation (5-HT2) of phospholipase C; and (ii) ionotropic receptors (5-HT3), which form a ligand-gated Na+/K+ channel. Regarding blood pressure regulation (and beyond the intricacy of central 5-HT effects), this monoamine also exerts direct postjunctional (on vascular smooth muscle and endothelium) or indirect prejunctional (on autonomic and sensory perivascular nerves) effects. At the prejunctional level, 5-HT can facilitate or preclude the release of autonomic (e.g., noradrenaline and acetylcholine) or sensory (e.g., calcitonin gene-related peptide) neurotransmitters facilitating hypertensive or hypotensive effects. Hence, we cannot formulate a specific impact of 5-HT on blood pressure level, since an increase or decrease in neurotransmitter release would be favoured depending on the type of prejunctional receptor involved. This review summarizes and discusses the current knowledge on the prejunctional mechanisms involved in blood pressure regulation by 5-HT and its impact on some vascular-related diseases.
ARTICLE | doi:10.20944/preprints202211.0353.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: high blood pressure; Cancer; malignancies; hypertension
Online: 18 November 2022 (10:05:11 CET)
Background of the Study: We investigated the link between hypertension and cancer since it has been suggested that hypertension may raise the long-term risk of cancer. Previous large observational cohort studies found that greater blood pressure (BP) was related to a higher risk of cancer. Mendelian randomization (MR) was utilized to produce less confounded blood pressure estimates (BP) on overall and site-specific malignancies. The study aims to draw conclusions on the relationship between high blood pressure and cancer. Methods: Studies on high blood pressure and various malignancies are inconclusive, except for renal cell carcinoma. However, given that most meta-analyses only contained a limited number of trials, some relative risks had small to moderate magnitudes, and several may have been impacted by residual confounding, careful interpretation is necessary. The study was conducted using the meta-analysis technique. Cochran's Q test and I2 test were used to assess statistical heterogeneity between studies in the current investigation for research involving two or more cause and outcome combinations. Results: Positive correlations were also reported between high blood pressure and esophageal adenocarcinoma, squamous cell carcinoma, liver, and squamous cell carcinoma. However, most studies lacked multivariable adjustments. Physical and numerical risk of cardiovascular disease is linked to bowel cancer but no other cancers. According to a meta-analysis, hypertensive persons could also be at increased danger of gastrointestinal and breast cancer. Most meta-analyses comprised several trials with moderate or mild hazard ratios.ConclusionDifferent types of cancers have been noted to be directly caused by hypertension. In addition, some treatments have also been associated with the side effects of cancer treatments to cause hypertension. Women facing hypertension have an increased risk of getting breast cancer. Although some cancers showed a real relationship with hypertension, others had no connection at all.
Subject: Engineering, Electrical And Electronic Engineering Keywords: Bismuth; Chitosan; pressure; thermoelectric; composite film
Online: 3 February 2020 (04:52:51 CET)
The main aim of this work is to report an alternative energy efficient technique of fabricating flexible thermoelectric generators (TEGs) using printable ink. In this process, we have fabricated thermoelectric (TE) composite thick film and we are experimenting several ways to overcome the challenges of conventional and additive manufacturing methods. Two different mesh sizes of n-type bismuth particle, various binder to thermoelectric (TE) material weight ratio, and two different pressure (200 MPa and 300 MPa) were employed for optimizing the thermoelectric properties of TE composite films. We are also exploring naturally occurring chitosan as a binder. Dimethyl sulfoxide (DMSO) dissolved chitosan was used for the binder and less than 0.2 wt% of chitosan was sufficient for the fabrication of TE inks and composite films. Low energy intensive curing process was employed to evaporate the solvent from the drop casted inks. External uniaxial pressure not only eliminated high energy intensive curing processes but also increased the packing density of the film by removing pores and voids in the chitosan-bismuth composite film. The microstructure analysis reveals that bulk-like structure, which rarely has voids, pores and grain boundaries, was observed in the composite films pressed at sufficiently high pressures. The highest performing composite film was obtained with the conditions of 1:2000 binder to bismuth weight ratio, 100 mesh of particle size, and 300 MPa of pressure. The best performing bismuth chitosan composite film pressed at 300 MPa had the power factor as 4009 ± 391 μW/m·K2 with high electrical conductivity value of 7337 ± 522 S/cm. The measured thermal conductivity of the best performing chitosan-bismuth composite film was 4.4 ± 0.7 W/m·K and the figure of merit calculated from the thermal conductivity was 0.27 at room temperature.
ARTICLE | doi:10.20944/preprints201912.0259.v1
Subject: Physical Sciences, Chemical Physics Keywords: hydrate; propane; normal butane; equilibrium pressure
Online: 19 December 2019 (13:10:12 CET)
The purpose of this study is to determine the equilibrium conditions for the formation of a mixture of propane and normal butane hydrates including temperature, pressure and mole fraction. In order to prevent the formation of hydrates in the cooling path, it is necessary to examine the conditions of hydrate formation and provide solutions. Modeling of hydrate formation conditions was performed using Hydoff software and compared with experimental results in this field, which obtained an acceptable error percentage. The range of temperature is between 267-276 °C and the molar percentage of propane is 0.7,0.8 and 0.9 and the mathematical equation was presented to predict hydrate formation. By analyzing the results, it was found that by increasing the concentration of ethane in the presence of other compounds, hydrate growth increased and hydrates formed more stable, also by increasing the concentration of propane and normal butane the amount of equilibrium pressure will decrease.
ARTICLE | doi:10.20944/preprints201910.0315.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: piezoresistivity; PVDF; nanocarbonaceous; electromechanical; pressure sensibility
Online: 27 October 2019 (16:17:54 CET)
Polymer-based composites reinforced with nanocarbonaceous materials can be tailored for functional applications. Poly(vinylidene fluoride) (PVDF) reinforced with carbon nanotubes (CNT) or graphene with different filler contents have been developed as potential piezoresistive materials. The mechanical properties of the nanocomposites depend of the PVDF matrix, filler type and filler content. PVDF 6010 is a relatively more ductile material, whereas PVDF-HFP shows larger maximum strain near 300% strain for composites with CNT, 10 times higher than the pristine polymer. This behaviour is similar for all composites reinforced with CNT. On the other hand, rGO/PVDF composites decrease the maximum strain compared to neat PVDF. It is shown that the use of different PVDF copolymers does not influence the electrical properties of the composites. On the other hand, CNT as filler leads to composites with percolation threshold around 0.5 wt.%, whereas reduced graphene oxide (rGO) nanocomposites shows percolation threshold at ≈2 wt.%. Both nanocomposites present excellent linearity between applied pressure and resistance variation, with pressure sensibility (PS) decreasing with applied pressure, from PS≈ 1.1 to 0.2 MPa-1. A proof of concept demonstration is presented, showing the suitability of the materials for industrial pressure sensing applications.
ARTICLE | doi:10.20944/preprints201812.0358.v1
Online: 31 December 2018 (05:55:50 CET)
This manuscript discusses a novel method to map pressure results from one 3D surface shell mesh onto another. This technique is especially important when transferring results from one numerical analysis to another. This method works independent of the actual pressures, and only focuses on ensuring the surface areas consistently match. By utilizing this approach, the cumulative forces consistently match for all input pressures. This method is demonstrated to work for pressure profiles with precipitous changes in pressures, and with small quadrangular source elements being applied to a mix of large quadrangular and triangular target elements, and the forces at all pressure profiles match remarkably.
ARTICLE | doi:10.20944/preprints201804.0288.v1
Subject: Physical Sciences, Mathematical Physics Keywords: Maxwell slip flow; microchannels; pressure profile
Online: 23 April 2018 (11:50:03 CEST)
Expressions for the axial pressure profiles in a cylindrical channel and between parallel plates or a rectangular channel with large aspect ratio, with Maxwell slip gas flow are derived from first principles. The resulting expressions, which only involve the inlet and outlet pressures and the channel dimensions, will be useful in modelling or simulations of channel flows at Knudsen numbers in the range 0.001–0.1, such as in MEMS and NEMS. The expression for a cylindrical channel is validated by deriving from it an expression for the channel mass flow, which is shown to agree with a known expression for the mass flow through cylindrical channels with Maxwell slip flow. The expression for flow between parallel plates is found to agree with the zeroth order relation derived by Arkilic et al. using perturbation analysis. The effect of the accommodation coefficient on the pressure profile in a cylindrical channel is shown.
ARTICLE | doi:10.20944/preprints201709.0076.v1
Subject: Business, Economics And Management, Business And Management Keywords: fiscality; pressure; assets; debts; liquidity; solvency
Online: 18 September 2017 (10:56:11 CEST)
The financial equilibrium of the enterprise is an important company function ensuring by itself the maintenance of the enterprise of the competitive market. The financial equilibrium is analysed in numerous empirical studies. In this empirical study we highlight for the first time in a research the impact that taxation has on the financial equilibrium of some companies over ten years, period that includes the pre-crisis, the financial crisis and post-crisis periods.
ARTICLE | doi:10.20944/preprints202305.1449.v2
Subject: Engineering, Mechanical Engineering Keywords: pressure vessel:; ASME code; optimum design; working pressure; structural analysis; finite element method; autodesk inventor professional
Online: 30 May 2023 (03:04:41 CEST)
As the demand for liquefied petroleum gas (LPG) continues to increase worldwide, more LPG facilities are being constructed. However, the design and manufacture of pressure vessels used to store dangerous liquids or pressurised fluids, such as LPG, has been a major cause of hazards, including explosions and leakage. In this study, we aim to address this issue by designing and analysing a vertical pressure vessel with a capacity of 10 m3 of pressurised LPG in accordance with the American Society of Mechanical Engineers (ASME) code. Safety is the primary concern in designing pressure vessels due to the potential risks posed by accidents. Therefore, the main objective of this project is to design a pressure vessel that is safe from failure. The vessel is cylindrical with two elliptical heads, two nozzles, a manway and four leg supports, and we used Autodesk Inventor Professional 2023 for geometric modelling and Inventor Nastran for FEA analysis. To investigate the displacements, deflections and Von-Mises stresses in the pressure vessel, we used the finite element method, and Autodesk Inventor Nastran was employed for the analysis. Our results showed that changes to the structure of the pressure vessel were needed to reduce stress in the structure. Specifically, the displacement showed an inverse relationship with the tank section shell thickness. Moreover, we observed that the factor of safety increased linearly with shell thickness. We carefully considered permissible pressures and determined the required wall thickness to ensure acceptable maximum stresses. Our results indicate that the design is safe from failure, and the highest stresses are experienced by the manway followed by the shell, while the heads, nozzles and legs support experienced the lowest stresses. We also performed a theoretical calculation for the entire model and checked the results to ensure they were within the acceptable limits. In summary, our study highlights the importance of designing pressure vessels in accordance with ASME codes to ensure safety and prevent hazards caused by improper design and manufacturing. By using the finite element method, we identified potential stress points in the pressure vessel and were able to make modifications to improve its safety.
ARTICLE | doi:10.20944/preprints202304.0292.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: systolic blood pressure; diastolic blood pressure; serum leptin; body mass index; normal and overweight male students
Online: 13 April 2023 (03:41:43 CEST)
Precise association of serum leptin with body mass index (BMI) and blood pressure (BP; both systolic blood pressure (SBP) and diastolic blood pressure (DBP) is not well known for understanding their involvement in health and disease. Hence, the present study was planned to be conducted for investigating the association of BP, BMI and serum leptin levels in young normal weight (NW) and overweight (OW) male Saudi students. The NW (n: 198) and OW male subjects (n: 192) in the age range of 18-20 years were consulted. Blood pressure (BP) was measured with a mercury sphygmomanometer. Leptin Human ELISA Kits were employed for the determination of the serum leptin levels. The mean ± SD values of BMI (kg/m2), serum leptin (ng/ml), SBP (mmHg), and DBP (mmHg) all showed significant difference for young OW vs. NW male university students as: 27.52± 1.42 vs. 21.49± 2.03; 10.70± 4.67 vs. 4.68± 1.91; 121.37±2.59 vs.118.51±1.54 and 81.44±1.97 vs. 78.79±1.44 respectively. All associations (among BMI, leptin, SBP and DBP) showed positive linear and significant correlation except nonsignificant correlation of BMI and SBP for NW group. The present study in the young Saudi male students, presents significant variations for BP and serum leptin levels and significant positive linear association among serum leptin, BMI and BP.
ARTICLE | doi:10.20944/preprints201703.0050.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: mefenamic acid; diamond anvil cell; high-pressure; polymorphism; high-pressure crystallization; non-steroidal anti-inflammatory drugs
Online: 8 March 2017 (08:58:38 CET)
High pressure crystallization technique has been successfully used to prepare an elusive form II of a non-steroidal anti-inflammatory drug, Mefenamic acid. Single crystal of form II was grown at 0.3 GPa from an 4:1 methanol/ ethanol mixture as a solvent using Diamond Anvil Cell. Comparison of crystal structures show that the efficient packing of MA molecules in Form II results from the structural flexibility of MA acid molecules. Compression studies performed on the single crystal of form I resulted in 14 % decrease of unit cell volume up to 2.5 GPa. No phase transition was observed up to this pressure. A reconstructive phase transition is required to induce conformational changes in the structure, which is confirmed by crystallization at high pressure results.
ARTICLE | doi:10.20944/preprints201608.0224.v2
Subject: Engineering, Marine Engineering Keywords: propeller; cavitation pattern; unsteady cavitation; induced pressure fluctuations; high-speed visualization; volume acceleration; cavitation-pressure correlations
Online: 5 September 2016 (09:37:05 CEST)
An experimental study is carried out in a cavitation tunnel on a propeller operating downstream of a non-uniform wake. The goal of this work is to establish quantitative correlations between the near pressure field and the cavitation pattern that takes place on the propeller blades. The pressure field is measured at the walls of the test section and in the near wake of the propeller, and is combined with quantitative high-speed image recording of the cavitation pattern. Through simple harmonic analysis of the pressure data and image processing techniques that allow to retrieve the cavitation extension and volume, we discuss the potential sources that generate the pressure fluctuations. Time correlations are unambiguously established between pressure peak fluctuations and cavitation collapse events, based upon the Rayleigh collapse time. Finally, we design a model to predict the cavitation-induced pressure fluctuations from the derivation of the cavitation volume acceleration. This simple model demonstrates a remarkable agreement with the actual pressure field.
REVIEW | doi:10.20944/preprints202311.1049.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: powders; pressure; density; die-compaction equation; approximation.
Online: 16 November 2023 (11:20:19 CET)
The well-known equations for the process of powder compaction (PCP) in a rigid die published over the period from the beginning of the last century to the present are considered. Most of the considered equations are converted into the dependence of the densification pressure on the relative density. The equations were analyzed and their ability to describe PCP was assessed by determining the coefficient of determination when approximating experimental data on the compaction of various powders. It is shown that most of the equations contain two constants, the values of which are determined by fitting the mathematical dependence to the experimental curve. Such equations are able to describe PCP with high accuracy in the case of compaction of powders up to a relative density of 0.9-0.95. It is also shown that different equations can describe PCP in the range of density change from the initial to 0.9 with the same and sufficiently high accuracy, but when the process of compaction is extrapolated to higher values of density, the curves diverge. This indicates the importance of equations that can unambiguously describe PCP to a relative density equal to or close to 1.0. For an adequate description of PCP to a relative density greater than 0.95, equations containing three or four constants have proven themselves well.
REVIEW | doi:10.20944/preprints202311.0909.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: Blood Pressure; Ischemia Monitoring; Wearable Ultrasonic Sensor
Online: 15 November 2023 (03:51:00 CET)
Ischemia, the inadequate blood flow, can arise from pre-existing or traumatic events, remain an undetectable issue, and impact the body's ability to provide oxygen to necessary limbs, organs, muscles, or tissue. New technology involving wearable ultrasonic devices allows medical professionals to gain real-time insight into the cardiovascular system of their patients. A non-invasive, postage-stamp-sized ultrasonic sensor can be attached to a patient, allowing for continuous monitoring of the patient’s blood pressure outside of the hospital. After reviewing 16 papers on ultrasonic sensors, this paper intends to review the current use of wearable ultrasonic sensors and the advantages and limitations of the technology used to obtain accurate blood pressure readings. This review will bring attention to the evolving and expanding world of wearable ultrasonic sensors for medical applications.
ARTICLE | doi:10.20944/preprints202310.1891.v1
Subject: Social Sciences, Education Keywords: parental pressure; academic; achievement; school; students; survey
Online: 30 October 2023 (09:43:00 CET)
This research aims to investigate the effects of parental pressure on students' academic achievement at the school level. The research objectives include examining the relationship between parental pressure and academic achievement and identifying potential moderating variables. A sample of middle and high school students will be utilized in this study.
REVIEW | doi:10.20944/preprints202309.0552.v1
Subject: Public Health And Healthcare, Public Health And Health Services Keywords: Forests; cortisol, natural killer; blood pressure; intervention.
Online: 7 September 2023 (11:37:46 CEST)
Background: The mental state is important in the health/illness process. Including stress, depression and anxiety. Nature immersion therapies have been implemented as a valid method for reducing these disorders. The aim will evaluate the effect of forest intervention therapies on levels of stress, depression, and anxiety. Methods: We searched for randomized clinical trials related to stress, anxiety and depression levels. Risk of bias was assessed according to the guidelines of the Cochrane Handbook for International Systematic Reviews. Results: We identified and synthesized eight publications. Two studies for cortisol showed significant differences between the pre-test and post-test levels in the intervention groups. One study including Natural killer cells, that reported a significant decrease in the intervention group compared to the control group. Two studies used the Stress Response Inventory, indicated a significant reduction in stress levels in the intervention group compared to the control group. Regarding Restorative Out-come Scale, no significant differences were found. Three studies were selected for the evaluation of anxiety and depression levels according to the Positive and Negative Affect Schedule. Four studies used The Profile of Mood States scale; no significant difference was observed. Conclusions: There is limited evidence to recommend forest bathing for reducing these disorders.
ARTICLE | doi:10.20944/preprints202308.0654.v1
Subject: Medicine And Pharmacology, Veterinary Medicine Keywords: dog; intra-abdominal pressure; dexmedetomidine; hypercapnia; PulseCO
Online: 9 August 2023 (03:13:15 CEST)
Intra-abdominal pressure (IAP) elevation during capnoperitoneum can cause adverse cardiovascular and respiratory effects. This study aimed to determine if a sequentially increased IAP affects cardiovascular and respiratory variables in anesthetized dogs and evaluate the effects of constant rate infusion of dexmedetomidine (Dex) on cardiovascular and respiratory variables with increased IAP. Five dogs were anesthetized, instrumented, and the Veress needle was equipped to adjust the IAP using a carbonic anhydrase insufflator. Stabilization was conducted for 1 h, and physiological variables were measured in IAPs of 0, 5, 10, 15, and 20 mmHg and after desufflation. After the washout period, the dogs underwent similar procedures along with constant rate infusion of dexmedetomidine. Cardiovascular effects of increased IAP up to 20 mmHg were not significant in healthy beagle dogs and those administered with dexmedetomidine. In the control group, the arterial pressure slightly increased, but not statistically significant, at an IAP of 20 mmHg compared with that at baseline (mean arterial blood pressure, p = 0.399; systolic arterial blood pressure, p = 0.293; diastolic arterial blood pressure, p = 0.141). When comparing the control and dexmedetomidine groups, overall significant effects of dexmedetomidine were noted on heart rate, cardiac output, and systemic vascular resistance during the experiment. Respiratory effects were not affected by abdominal insufflation when compared between different IAPs and between the two groups. Overall, an increased IAP of until 20 mmHg did not significantly affect cardiovascular and respiratory variables in both control and dexmedetomidine groups. This study suggests that dexmedetomidine infusion administration is applicable in laparoscopic procedures in healthy dogs.
ARTICLE | doi:10.20944/preprints202302.0044.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Brain death diagnosis; Intracranial Pressure; Intracranial compliance
Online: 2 February 2023 (11:30:01 CET)
Background: Due to the importance of brain death (BD) diagnostic do not mistake, reliable confirmatory exams should be performed to enhance its security. This study aims to evaluate the intracranial pressure (ICP) pulse morphology behavior in brain-dead patients through a noninvasive monitoring system. Methods: A pilot case-control study was conducted in adults that met the BD national protocol criteria. Quantitative data from the ICP waveforms were extracted and analyzed comparing BD patients and health subjects. Results: Fifteen patients were included. ICP waveforms presented substantial differences amidst BD patients when compared to the control group. Moreover, pulse amplitude and time to peak variables values in the case group were also statistically significant. Conclusions: In this exploratory study, noninvasive ICP waveforms have shown potential as a screening method in patients with suspected brain death. Future studies should be carried out in a larger population.
ARTICLE | doi:10.20944/preprints202210.0392.v1
Subject: Medicine And Pharmacology, Internal Medicine Keywords: Keywords: Hypertension; Avocado leaves; Blood pressure; seniors
Online: 26 October 2022 (02:13:28 CEST)
Background: Hypertension is a condition of a person's blood pressure being at a level above normal, hypertension treatment can be done herbally using avocado leaves. Avocado leaves can lower blood pressure because they contain active substances, namely flavonoids and quercetin. This research was conducted in the working area of the Tilango Health Center. Objective: This study aims to determine the effect of giving boiled water of avocado leaves on reducing blood pressure in the elderly with hypertension. Methods: Design This study used a two-group quasi-experimental pre-test - post-test design. The sample is the elderly who have hypertension, amounting to 125 people with purposive sampling technique. The research instrument used a questionnaire. Results: Statistical test using T-Test on blood pressure before and after the intervention was given a significance value of 0.000 (p-value < 0.05 ). Conclusion : This study concludes that there is a significant effect between giving avocado leaf boiled water on reducing blood pressure in the elderly with hypertension in the working area of the Tilango Health Center.
ARTICLE | doi:10.20944/preprints202208.0499.v1
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: HAPE; risk factors; echocardiography; pulmonary pressure; workload
Online: 30 August 2022 (03:18:35 CEST)
Background: At altitudes beyond 2500 m the risk of developing high altitude pulmonary edema (HAPE) grows with the increases in pulmonary arterial pressure. HAPE is characterized by severe pulmonary hypertension, though the incidence and relevance of individual risk factors are not yet predictable. However, the systolic pulmonary pressure (SPAP) and peak in tricuspid regurgitation velocity (TVR) are crucial factors when diagnosing pulmonary hypertension by echocardiography. Methods: The SPAP and TVR of 27 trekkers aged 20-65 years en route in the Solu Khumbu region of Nepal was assessed. Echocardiograph measurements were performed at Lukla (2,860 m), Gorak Shep (5170 m), and the summit of Kala Patthar (5,675 m). The altitude profile and the participant’s characteristics were also compiled for correlation with the measured data. Results: The results showed a highly significant increase of SPAP and TVR after ascending Kala Patthar. The study revealed a lower increase of SPAP and TVR in the group of older participants, although the initial respective measurements in Gorak Shep were significantly higher for this group. A similar finding occurred in those using Diamox® as prophylaxis. There was an inverse relationship between TVR and SPAP, the peripheral capillary oxygen saturation and heart rate. Conclusions: The echocardiograph results indicate that older people are a risk group for developing a HAPE. The prophylactic use of acetazolamid led to higher initial SPAP values in Gorak Shep, and a lower increase of SPAP as well as TRV after ascending Kala Patthar. Arterial oxygen saturation measurements can provide an indicator for the self-assessment for the risk of developing HAPE and provide a rule of thumb for the altitude profile but does not replace a HAPE diagnosis. The collected data variables concerning backpack weight, sex, workload (actual ascent speed), and pre-existing diseases were not statistically significant factors related to SPAP and TVR (p=<0.05).
ARTICLE | doi:10.20944/preprints202009.0606.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: fracture; theoretical model; seepage pressure; rock deformation
Online: 25 September 2020 (11:36:54 CEST)
The formation of rock fractures in nature has a certain relationship with water seepage. In order to analyze the shape of rock fracture, we propose a rock deformation theoretical model in three-dimensional space considering with the condition of seepage water pressure, and establish the mass conservation equation, seepage equation, surrounding rock displacement equation, so as to deduce the rock deformation control equation under seepage pressure action. The numerical analysis of the nonlinear quadratic partial differential equation obtains the fracture deformation distribution in the example, and verifies with the calculated fracture morphology. And we further use this principle to analyze the fracture morphology in nature and prove the rationality of the theory.
ARTICLE | doi:10.20944/preprints202009.0389.v1
Subject: Medicine And Pharmacology, Ophthalmology Keywords: Graves’ ophthalmopathy; exophatlmos; intraocular pressure; topical medications
Online: 17 September 2020 (08:35:17 CEST)
Purpose: The evaluation of the efficacy of topical hypotensive treatment and/or systemic corticosteroids therapy in patients with elevated intraocular pressure and Graves’ orbitopathy (GO). Methods: 172 eyes in 86 individuals with duration of GO ≥ 3 months, intraocular pressure in either eye ≥ 25.0 mmHg and GO ranked ≥ 3 at least in one eye in modified CAS form, were included. The study subjects were divided into three treatment subgroups: subgroup I was administered latanoprost QD; subgroup II was administered a combined preparation of brimonidine and timolol BID; subgroup III was the control group, not receiving any topical hypotensive treatment. All the study participants received systemic treatment – intravenous corticosteroid therapy at the same dose, according to the EUGOGO guideline Results: On the final visit, the mean IOP value was significantly lower in all treatment subgroups comparing to the initial values. In both subgroups receiving topical treatment the IOP reduction was higher than in the control group receiving systemic corticosteroids only. However, the latanoprost eye drops decreased intraocular pressure more effectively than drops containing brimonidine and timolol. Conclusion: Topical ocular hypotensive treatment is effective in reducing intraocular pressure in GO and decreases intraocular pressure more effectively than systemic corticosteroid therapy alone.
ARTICLE | doi:10.20944/preprints202003.0204.v1
Subject: Computer Science And Mathematics, Artificial Intelligence And Machine Learning Keywords: Burns; Pressure Ulcer; Bruises; Deep Learning; Classification
Online: 12 March 2020 (09:04:23 CET)
While visual assessment is the standard technique for burn evaluation, computer-aided diagnosis is increasingly sought due to high number of incidences globally. Patients are increasingly facing challenges which are not limited to shortage of experienced clinicians, lack of accessibility to healthcare facilities, and high diagnostic cost. Certain number of studies were proposed in discriminating burn and healthy skin using machine learning leaving a huge and important gap unaddressed; whether burns and related skin injuries can be effectively discriminated using machine learning techniques. Therefore, we specifically use pre-trained deep learning models due to deficient dataset to train a new model from scratch. Experiments were extensively conducted using three state-of-the-art pre-trained deep learning models that includes ResNet50, ResNet101 and ResNet152 for image patterns extraction via two transfer learning strategies: fine-tuning approach where dense and classification layers were modified and trained with features extracted by base layers, and in the second approach support vector machine (SVM) was used to replace top-layers of the pre-trained models, trained using off-the-shelf features from the base layers. Our proposed approach records near perfect classification accuracy of approximately 99.9%.
ARTICLE | doi:10.20944/preprints201810.0028.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: Hypertension; Blood pressure; Genetics; Pharmacogenetics; Pharmacotherapy; Treatment
Online: 2 October 2018 (15:02:46 CEST)
Several common and functional genes are known to contribute to responsiveness to blood pressure (BP) therapy. BP therapy is typically guided by algorithms that do not include a patient’s genetic information. This study aimed to determine the impact of a multi-organ genetic panel on BP response to pharmacotherapy. Eighty-six patients completed one study visit consisting of a buccal swab collection, measurement of office BP, and a medical chart review for BP history. Genes analyzed included those that encode for one drug metabolizing enzyme, renal Na+ handling, vascular, and cardiac function. Relationships between genotype and control of BP (<140/<90), ∆ systolic BP, ∆ diastolic BP, and ∆ mean arterial BP were assessed. SLC12A3 resulted in a significant association between the target drug and the functional genotype for BP control (<140/<90 cut off) (p<0.05). Conversely, three of five renal genotypes were associated with BP control using 120/80 as a cut-off (p<0.05). Three of four cardiac genotypes were associated with the BP control at <140/<90, with one being statistically significant (position 49 of ADRB1). Only one vascular genotype was predictive of blood pressure control at <140/<90. We found a significant drop in mean BP from baseline in six genes, three important in the diuretic response and three in β-blockade (p<0.05 on target drug vs. not). These results demonstrate that a multi-gene panel for renal Na+ handling, vascular function, and cardiac output may influence the BP response to therapy, but larger studies with more statistical power are needed.
ARTICLE | doi:10.20944/preprints201807.0137.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: CHIP; metabolism; fenofibrate; fibrosis; metabolomics; pressure overload
Online: 9 July 2018 (12:11:53 CEST)
We previously reported how the loss of CHIP expression (Carboxyl terminus of Hsc70-Interacting Protein) during pressure overload resulted in robust cardiac dysfunction, accompanied by a failure to maintain ATP levels in the face of increased energy demand. In this study, we analyzed the cardiac metabolome after seven days of pressure overload and found an increase in long- and medium-chain fatty acid metabolites in wild-type hearts, a response that was attenuated in mice that lack expression of CHIP (CHIP-/-). These findings suggest that CHIP may play an essential role in regulating oxidative metabolism, pathways that are regulated in part by the nuclear receptor PPARα (Peroxisome Proliferator-Activated Receptor alpha). Next, we challenged CHIP-/- mice with the PPARα agonist, fenofibrate. Surprisingly, treating CHIP-/- mice with fenofibrate for five weeks under non-pressure overload conditions resulted in a loss of skeletal muscle mass and a marked increase in cardiac fibrosis, accompanied by a decrease in cardiac function. Isolated CHIP-/- cardiac fibroblasts treated with fenofibrate did not increase synthesis of collagen or TGFβ, suggesting that the fibrosis observed in CHIP-/- hearts likely depends on signaling from other cell types or circulating factors. In conclusion, in the absence of functional CHIP expression, fenofibrate results in unexpected cardiac pathologies. These findings are particularly relevant to patients harboring loss-of-function mutations in CHIP and are consistent with a prominent role for CHIP in regulating cardiac metabolism.
ARTICLE | doi:10.20944/preprints201803.0133.v1
Subject: Medicine And Pharmacology, Dietetics And Nutrition Keywords: hypertension; lead; cadmium; blood pressure; combined exposure
Online: 16 March 2018 (07:22:57 CET)
We evaluated the association of blood pressure with blood levels of cadmium, lead, and cadmium and lead together (cadmium+lead) in a representative sample of adolescents from Korea by use of 2010-2016 data from the Korean National Health and Nutrition Examination Survey (KNHANES). This cross-sectional study enrolled adolescents aged at 10-18 years-old who completed a health examination survey and had blood measurements of lead and cadmium. The association of adjusted mean differences in diastolic and systolic blood pressure with doubling of blood lead and cadmium were estimated by regression of blood pressure against log2-transformed blood metals and their quartiles after covariate adjustment. Adjusted odds ratios for prehypertension were calculated for log2-transformed blood levels of lead and cadmium and their quartiles. Our analysis of adolescents in Korea indicated that blood levels of lead and cadmium were not significantly associated with increased blood pressure or risk of pre-hypertension. However, the cadmium+lead level was associated with pre-hypertension. Previous studies showed that blood levels of lead and cadmium were associated with increased blood pressure and risk of hypertension in adult populations. We found no such effect in Korean adolescents, although the cadmium+lead level was associated with prehypertension. These differences may be because adolescents generally have lower levels of these blood metals or because adolescents only rarely have hypertension.
ARTICLE | doi:10.20944/preprints201711.0103.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: superconductivity; bismuth at ambient pressure; Bi–I; bismuth at high pressure; Bi–V; constraining forces; nonadiabatic Heisenberg model
Online: 16 November 2017 (04:58:52 CET)
As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation generated by the strongly correlated atomic-like motion of the electrons in narrow, roughly half-filled "superconducting bands". These are energy bands represented by optimally localized spin-dependent Wannier functions adapted to the symmetry of the material under consideration. The formation of Cooper pairs is not the result of an attractive electron-electron interaction but can be described in terms of quantum mechanical constraining forces constraining the electrons to form Cooper pairs. There is theoretical and experimental evidence that only this nonadiabatic mechanism operating in superconducting bands may produce eigenstates in which the electrons form Cooper pairs. These constraining forces stabilize the Cooper pairs in any superconductor, whether conventional or unconventional. Here we report evidence that also the experimentally found superconducting state in bismuth at ambient as well as at high pressure is connected with a narrow, roughly half-filled superconducting band in the respective band structure. This observation corroborates once more the significance of constraining forces in the theory of superconductivity.
HYPOTHESIS | doi:10.20944/preprints202108.0531.v1
Subject: Business, Economics And Management, Accounting And Taxation Keywords: nature of stock rights; state-controlled firm; income smoothing; institutional investor; pressure-resistant institutional investor; pressure-sensitive institutional investor
Online: 28 August 2021 (15:07:13 CEST)
The purpose of this study is to examine the relationship between the institutional investors which can affect financial performance for corporate sustainability on the income smoothing. Therefore, this study focus on the connection between the nature of stock rights and income smoothing in China. For this study, hypotheses were established on the relationship each state-controlled companies, income smoothing, and information equilibrium of individual investors, and empirical analysis was conducted through related variables. The analysis results are summarized in three categories as follows. First, this research finds that state-controlled firms (CONTs) prefer income smoothing activities compared to non-state-controlled firms for the long-term sustainable development of firms using data from 2011 to 2019. Second, this study found out that Institutional investors support the behavior of CONTs to smooth their earnings because this behavior is seen as an attempt by CONTs to convey valuable private information to other investors. Third, we was able to discover that institutional investors' monitoring effect is predominantly driven by pressure-resistant institutional investors. This research complements the lack of empirical research on income smoothing and enable to give a guideline that the type of stock rights is a critical key determinant of participation in income smoothing activities for stable growth and sustainability in the future.
ARTICLE | doi:10.20944/preprints202311.0407.v1
Subject: Engineering, Mechanical Engineering Keywords: Air mass flow; pressure; optimization; PEM fuel cell
Online: 7 November 2023 (10:32:16 CET)
A study was conducted on the power system of a forklift equipped with PEM fuel cells. A fuel cell assembly relies on several components for proper functioning, and among these, the air compressor holds paramount importance due to its significant energy consumption when compared to other Balance of Plant components. The air supply system, in turn, plays a critical role in ensuring the stable and efficient operation of the entire fuel cell system. To enhance system efficiency, we delved into the impact of varying the stoichiometric ratio of air and air pressure on the validated and optimized power module model. This investigation was carried out under real loading conditions, replicating the conditions experienced by the power module when fuel cells are in use within a forklift. The air compressor, being a pivotal component of a PEM fuel cell system, can be oper-ated at different excess air and pressure ratios, which in turn influence both the fuel cell's performance and the overall efficiency of the power module system. Our research focused on assessing the performance of polymer electrolyte membrane (PEM) fuel cells under different load cycles, adhering to the VDI60 requirements for forklift applications. This comprehensive examination encompassed the system's minimum and maximum load scenarios, with the primary goal of optimizing excess air and pressure ratio parameters, especially under dynamic load conditions. The results revealed that higher air pressures and lower excess air ratios were con-ducive to increasing system efficiency, shedding light on potential avenues for enhancing the performance of PEM fuel cell systems in forklift applications.
COMMUNICATION | doi:10.20944/preprints202311.0177.v1
Subject: Engineering, Civil Engineering Keywords: concrete cracking; hydrostatic pressure; diffusion coefficient; chloride transportation
Online: 3 November 2023 (06:38:52 CET)
The service life of the reinforced concrete structure in the marine environment can be impaired significantly due to chloride-induced corrosion. However, how the chloride diffusion in pre-cracked concrete structures is affected by the hydrostatic pressure magnitude is poorly understood. This study experimentally examined the effect of hydrostatic pressure on the chloride diffusion in pre-cracked concrete. Cracks with five different widths, i.e., 20 μm, 40 μm, 60 μm, 80 μm, and 100 μm, were manually created using a splitting tensile apparatus respectively. The chloride diffusion in the concrete with a certain crack was then studied under four different hydrostatic pressures of 0 MPa, 0.1 MPa, 0.3 MPa, and 0.5 MPa. Experimental results show that the chloride diffusion in concrete with a crack greatly relies on both the hydrostatic pressure and the crack width. The chloride concentration increases as the hydrostatic pressure grows, particularly for the wider cracks with width ranging from 60 μm to 100 μm. Surprisingly, the hydrostatic pressure has a negligible effect on the chloride distribution in the concrete with a crack width no larger than 40 μm. Both the chloride diffusion coefficient and the surface chloride concentration of concrete increased gradually as the hydrostatic pressure increased. The experimental findings enrich our understanding of the behavior of pre-cracked concrete when exposed to chloride-induced corrosion at different depths of marine environments.
ARTICLE | doi:10.20944/preprints202310.0352.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: ball milling; high-pressure homogenization; ultrasonication; cell counting
Online: 9 October 2023 (08:56:51 CEST)
The high protein content of several microalgal species makes them attractive and unconventional for applications in the food and pharmaceutical industries. Due to microalgae's robust cell wall, cell rupture is necessary to improve the extraction of their intracellular proteins. Thus, choosing a suitable cell-breaking treatment before protein extraction is a vital downstream processing step. Additionally, it is necessary to use an effective technique for monitoring and measuring the impact of rupture treatments on microalgal cell walls. In our study, Tetradesmus obliquus cells were disrupted by three different mechanical rupture methods: high-pressure homogenization (HPH), ultrasound (US), and ball milling (BM). The ruptured biomass cells were counted, and soluble proteins were extracted and quantified. The cell counting technique did not detect differences between intact and damaged cells after BM treatment because the dye (erythrosine B) did not permeate the microalgae biomass accurately. The US treatment promoted the highest yield of total protein extraction (19.95%). The yields of protein extraction of T. obliquus with HPH (15.68%) and BM (14.11%) were significantly (p value ≤ 0.05) lower than that achieved in the US treatment. The increase in the number of extraction steps increased the protein recovery. Thus, the content of extracted soluble protein was a reliable indirect index for a quantitative comparison of the cell disruption level.
REVIEW | doi:10.20944/preprints202309.0518.v1
Subject: Biology And Life Sciences, Other Keywords: Oxidative stress; NADPH oxidase; Ethanol; Blood pressure; Endothelium
Online: 7 September 2023 (11:00:10 CEST)
Consumption of high amounts of ethanol is a risk factor for development of cardiovascular diseases such as arterial hypertension. The hypertensive state induced by ethanol is a complex multi-factorial event, and oxidative stress is a pathophysiological hallmark of vascular dysfunction associated with ethanol consumption. Increasing levels of reactive oxygen species (ROS) in the vasculature triggers important processes underlying vascular injury, including accumulation of intracellular Ca2+ ions, reduced bioavailability of nitric oxide (NO), activation of mitogen-activated protein kinases (MAPKs), endothelial dysfunction, and loss of the anticontractile effect of perivascular adipose tissue (PVAT). The enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase plays a central role in vascular ROS generation in response to ethanol. Activation of the renin-angiotensin-aldosterone system (RAAS) is an upstream mechanism which contributes to NADPH oxidase stimulation, overproduction of ROS and vascular dysfunction. This review discusses the mechanisms of vascular dysfunction induced by ethanol, detailing the contribution of ROS to these processes. Data examining the association between neuroendocrine changes and vascular oxidative stress induced by ethanol are also reviewed and discussed. These issues are of paramount interest to public health as ethanol contributes to blood pressure elevation in the general population, and it is linked to cardiovascular conditions and diseases.
ARTICLE | doi:10.20944/preprints202308.1848.v1
Subject: Engineering, Mechanical Engineering Keywords: evaporative condenser; R744; subcritical; pressure drop; air conditioning
Online: 29 August 2023 (04:23:57 CEST)
Numerical simulations and experiments on evaporative condensers in air conditioning systems using R744 were performed. Two configurations were given to study the feasibility of operating the subcritical R744 cycle. It indicated the capable of evaporative cooling condensing R744 to liquify by analyzing the outlet temperature at the end of the condenser reached from 28.7oC to 30.3oC with the operating pressure from 72.6 bar to 68.5 bar. The mass flow rate in the study increases from 14.34 kg/h to 46.08 kg/h, the pressure drop also increases from 0.23 bar to 0.47 bar for the simulation and 0.4 bar to 0.5 bar for the experiment, respectively. This study indicates that a 5-layers of copper tubes configuration causes a higher pressure drop and lower COP when compared to an 8-layers of copper tubes that split into 2 sets for smaller pressure drop. In this study, the evaporative condensers using mini tubes that are flooded in the cooling water tank are suitable for the subcritical R744 air conditioning system. The results obtained from the experimental data are in good agreement with those obtained from the numerical results, with the deviation less than 5%.
BRIEF REPORT | doi:10.20944/preprints202308.0079.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Single nucleotide polymorphism, Population Branch Statistic, selective pressure.
Online: 1 August 2023 (10:37:24 CEST)
GDF5 gene is involved in the development of skeletal elements, synovial joint formation, tendons, ligaments, and cartilage. Several polymorphisms are present within the gene and two of them, rs143384 and 143383, have been reported as correlated with osteoarticular disease or muscle flexibility. The aim of this research is to verify if the worldwide distribution among human populations of rs143384 polymorphism has been shaped by selective pressure, or if it’s the result of random genetic drift events. Ninety-four individuals of both sexes, 18-28 years old, from Sardinia were analyzed. We observed the following genotype frequencies: 28.72% of homozygotes AA, 13.83% of homozygotes GG, and 57.45% of heterozygotes AG. Allele frequencies were 0.574 for allele A and 0.426 for alle G. Relationships between populations were verified by Multidimensional Scaling (MDS). Our data show: i) a clear heterogeneity within the African populations; ii) a strong differentiation between Africans and the other populations: iii) the Sardinian population is placed withing the European cluster. To reveal possible traces of selective pressure, Population Branch Statistic (PBS) was calculated; both SNPs rs143384 and 143383 have low PBS values, suggesting that there are no signals of selective pressure in those areas of the gene.
ARTICLE | doi:10.20944/preprints202306.2113.v1
Subject: Engineering, Civil Engineering Keywords: Natural ventilation; Wind tunnel; Air pressure; Aerodynamic coefficients.
Online: 29 June 2023 (11:14:30 CEST)
The close proximity of different buildings heights can cause disturbances in the working of the smoke and ventilation ducts of lower buildings, threatening the health and even the lives of residents. To define the influence of high-rise building on the work of the ducts of the neighbouring double-storied building, experimental investigations in the wind tunnel were conducted. On this basis, empirical equations and graphs were developed leading to determining the aerodynamic coefficients considering different wind directions and the height of ducts. The direction of the wind reveals a greater influence than the height of the ducts. Properly using deflectors or increasing the height of the duct ensures maintaining static rarefaction in the area of smoke and ventilation ducts. The creation of rarefaction ensures the reliability of the natural ventilation system and the safety of the health of residents.
ARTICLE | doi:10.20944/preprints202306.1375.v1
Subject: Engineering, Mechanical Engineering Keywords: Centrifugal pumps; Cavitation; Entropy; Hydrodynamics Characteristics; Pressure fluctuation.
Online: 19 June 2023 (15:33:43 CEST)
A numerical method using combined detached-eddy simulation (DES) and cavitation model considering the rotation effect is used for unsteady cavitation flow field of the centrifugal pump. Closed type pump test system was established to obtain the pump performance and pressure pulsation characteristics under different flow rates and cavitation condition, which provide boundary conditions and verification of calculations. Based on the calculation results of the unsteady flow field of the centrifugal pump cavitation, the entropy generation analysis of the flow field and the pressure fluctuation characteristics were carried out. Then the relationship between cavitation and the deterioration of the centrifugal pump performance and the generation of the unstable operation excitation force was tried to reveal. The internal energy loss is mainly concentrated in the impeller, volute, and pump cavity area, which accounts for more than 85% of the total entropy generation. The characteristic frequency of about 0.333 Strouhal Number appears at the volute tongue due to the cavitation flow spread downstream.
ARTICLE | doi:10.20944/preprints202104.0453.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: high-pressure microbiology; deep biosphere; cultivation devices; decompression
Online: 17 April 2021 (08:46:55 CEST)
High temperatures (HT) and high hydrostatic pressures (HHP) are characteristic of deep-sea hydrothermal vents and other deep crustal settings. These environments host vast and diverse microbial populations, yet only a small fraction of those populations have been successfully cultured. This is due, in part, to the difficulty of sampling while maintaining these in situ conditions and also replicating those high-temperature and high-pressure conditions in the laboratory. In an effort to facilitate more HT-HHP cultivation, we present two HT-HHP batch culture incubation systems for cultivating deep-sea vent and subsurface (hyper)thermophilic microorganisms. One HT-HHP system can be used for batch cultivation up to 110 MPa and 121°C, and requires sample decompression during subsampling. The second HT-HHP system can be used to culture microorganisms up to 100 MPa and 160°C with variable-volume, pressure-retaining vessels that negate whole-sample decompression during subsampling. Here, we describe how to build cost effective heating systems for these two types of high-pressure vessels, as well as the protocols for HT-HHP microbial batch cultivation in both systems. Additionally, we demonstrate HHP transfer between the variable-volume vessels, which has utility in sampling and enrichment without decompression, laboratory isolation experiments, as well as HHP filtration.
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: urodynamics; urethral profile; urethral pressure; assessment method; profilometry
Online: 26 February 2021 (12:19:53 CET)
BACKGROUND: To present a new method of urethral pressures examination, and to evaluate diagnostic capabilities of three dimensional profilometry , as an alternative to classical urethral profile (UPP) .Using four channel catheters and dedicated software global urethral pressures image is obtained. The method eliminates the main limitation of classical urethral profilometry where the catheter orientation determines the pressures picture limited to only one point in the uretral circumference while we observed even 50% differences in pressure measures depending on the point of measurement. METHODS: This is a preliminary study containing method presentation and analisys of the use in varied clinical cases of either healthy patients and patients with LUTS. The article includes technique and equipment decription, full evaluation of selected cases, including three dimensional urethral pressures distribution graphics. RESULTS AND CONCLUSIONS:Three dimensional profilometry compared to classical technique is comparable regarding the time, cost, technical difficulty and patient discomfort. At the same time we obtain much more data on the urethral pressures and its distribution.The results are easy for interpretation due to 3D movable graphics created automatically through the dedicated software.
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: astigmatism; glaucoma; intraocular pressure; phacotrabeculectomy; Ex-PRESS device
Online: 7 December 2020 (09:43:29 CET)
To compare surgical and refractive outcomes between phacotrabeculectomy (P-Trab) and phaco with Ex-PRESS (P-Ex-PRESS) for glaucoma at 6-month follow-up. This prospective randomized controlled trial included 81 eyes; 43 (53%) and 38 (47%) were assigned to the P-Ex-PRESS and P-Trab groups, respectively. Refraction, intraocular pressure (IOP), and best-corrected visual acuity were measured. Refractive change was described by analyzing the magnitude of the cylinder, and polar analysis assessed the change in trend of astigmatism [with-the-rule, against-the-rule (ATR), oblique] evaluating mean astigmatism in centroid form. All patients showed statistically significant postsurgical decrease in IOP (P<0.05). There were no differences neither between the groups for postoperative IOP or visual outcomes, nor in astigmatism before or after surgery (P=0.61, P=0.74). In both groups, the mean pre- and postoperative astigmatism was ATR and OBL, respectively. Pre- and postoperative centroids in the P-Ex-PRESS group were 0.44±1.32 D at 177˚ and 0.35±1 D at 8˚, respectively, (P=0.5) and in the P-Trab group, 0.16±1.5 D at 141˚ and 0.39±1.38 D at 29˚, respectively (P=0.38). Both P-Ex-PRESS and P-Trab showed comparable antihypertensive efficacy in treating open-angle glaucoma in a 6-month period. Pre- and postoperative astigmatism did not differ between groups. The groups showed comparable results for final visual acuity.
ARTICLE | doi:10.20944/preprints202010.0147.v1
Subject: Engineering, Automotive Engineering Keywords: Pedestrian navigation; ZUPT; Zero Velocity Detection; Plantar Pressure
Online: 7 October 2020 (08:31:29 CEST)
The zero velocity update(ZUPT) algorithm is the core of a foot-mounted pedestrian navigation system. The zero velocity detection method is the premise and guarantee of the effective application of the ZUPT algorithm. To make ZUPT work properly, it is necessary to detect zero velocity intervals correctly. The detection accuracy of the existing zero velocity detection methods is easy to be affected by users and environment. A novel zero velocity detection method based on the plantar pressure is proposed in this paper, which has higher detection accuracy and better environmental adaptability. First, the paper analyzes the motion characteristics of foot during walking. Second, the inherent relationship between the plantar pressure and the gait change during walking is studied based on the pressure sensor. Then, the model of the zero velocity detection method using the plantar pressure is established. Finally, the indoor and outdoor multi-scene experiments show that this method not only has a high detection accuracy, but also has good adaptability to users and walking environment.
BRIEF REPORT | doi:10.20944/preprints202004.0275.v1
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: COVID-19; ARDS; PEEP; mechanical ventilation; transpulmonary pressure
Online: 16 April 2020 (13:24:29 CEST)
With the emergence of COVID-19 we are confronted with a new clinical picture of acute respiratory distress syndrome in the intensive care unit. In the majority of patients, the respiratory mechanics are very different from the “normal” ARDS patient. We measured transpulmonary pressure and dead space ventilation to assess the effects of high and low PEEP levels on lung compliance and ventilation-perfusion mismatching. Advanced respiratory mechanics were assessed in 14 patients. Compared to ARDS patients, lung compliance was relatively high (61 ± 5 mL/cmH2O). COVID-19 patients had high dead space ventilation and gas exchange impairment (Bohr 52 ± 3%; Enghoff modification 67 ± 2%; ventilatory ratio 2.24 ± 0.23). we show that higher PEEP levels decrease lung compliance and in most cases increase dead space ventilation, indicating that high PEEP levels probably cause hyperinflation in patients with COVID-19. We suggest using prone position for an extended period of time, and apply lower PEEP levels as much as possible.
Subject: Engineering, Electrical And Electronic Engineering Keywords: surface discharge; flashover; gas; modelling; pressure; thermal properties
Online: 27 October 2019 (04:12:23 CET)
The aim of this paper is the presentation of an analytical model of insulator flashover and its application for air at atmospheric pressure and pressurized SF6. After a review of the main existing models in air and compressed gases, we develop a relationship of flashover voltage on the basis of an electrical equivalent circuit and the thermal properties of the discharge. The model includes the discharge resistance, the insulator impedance, and the gas interface impedance. The application of this model to a cylindrical resin-epoxy insulators in air medium and SF6 gas with different pressures gives results close to the experimental measurements.
Subject: Engineering, Energy And Fuel Technology Keywords: Keywords: retrievable packer; sealing; height; thickness; pressure-bearing
Online: 4 September 2019 (14:37:33 CEST)
Abstract In order to reduce the failure accidents of conventional packers, a kind of sealing structure of retrievable packers is designed, which can provide reference for optimizing the sealing performance and pressure capacity of packers. And theoretical calculation and experimental research on its sealing performance and pressure capacity are carries out through the finite element analysis on the contact with large deformation based on Abaqus and experimental. The results show that when the rubber cylinder of retrievable packers in the sealing process, the upper packer is subjected to greater stress and mainly plays a sealing role. In order to improve the sealing performance of packer, the height of upper and lower packer should be preferentially selected about 60 mm, the height of middle rubber cylinders should be about 50 mm, and the thickness of packer should be about 21 mm. The newly designed rubber cylinders can meet 150 ℃. Sealing and pressure-bearing function under the condition of 10000 Psi. The rubber cylinder of newly designed can satisfy the function of sealing and pressure-bearing under 140 ℃ and 10000 Psi. The whole experiment shows that the capacity of bearing pressure and sealing is stable, which can better meet the requirements of field use.
ARTICLE | doi:10.20944/preprints201811.0283.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: Arthrospira maxima; antioxidant; cardiovascular; nutraceutical; systolic blood pressure
Online: 12 November 2018 (10:42:25 CET)
1) Background: Spirulina (Arthrospira) maxima has shown beneficial effects such anti-dyslipidemic, antiviral, antioxidant and antihypertensive. However, there are few and limited clinical studies. 2) Methods: a prospective, randomized, parallel pilot study of 4.5 g administration of Spirulina maxima or placebo for 12 weeks in 16 patients with systemic arterial hypertension undergoing treatment with ACE inhibitors was performed to assess the effects on endothelial damage and oxidative stress indicators. The blood levels of sICAM-1, sVCAM-1, endothelin-1, and sE-selectin were quantified; the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and concentrations of reduced glutathione, oxidized glutathione, and thiobarbituric acid reactive susbtances, were also quantified before and after the treatment period. 3) Results: There were statistically significant (p < 0.05) decreases in systolic blood pressure, sVCAM-1, sE-selectin and endothelin-1 levels, and increases in glutathione peroxidase activity and oxidized glutathione levels. 4) Conclusion: The effects found in the present study agree with antihypertensive and antioxidant effects previously reported for Spirulina maxima. However, this is the first report about the effects on indicators of endothelial damage. More research in this field is necessary to gain an insight into the effects of Spirulina on these indicators.
REVIEW | doi:10.20944/preprints201808.0411.v1
Subject: Medicine And Pharmacology, Ophthalmology Keywords: Glucosamine, intraocular pressure, glaucoma, osteoarthritis, medication side effects.
Online: 23 August 2018 (10:20:47 CEST)
Glucosamine is the most common nutrition supplement used in the United States. It is promoted not only as a pain reliever but also a therapy to slow osteoarthritis. Although studies with 3,800 patients with osteoarthritis of the knee or hip found that glucosamine was no better than placebo, it continues to be used for these two indications due to its perceived safety. However, reports of an increased intraocular pressure are alarming, especially in glaucoma. Glycosaminoglycans play a key role in the physiology of the cornea, conventional outflow of aqueous humor and the retina. In theory, long-term treatment with glucosamine could reach a concentration that impacts the morphology and function of ocular tissues. We recommend ophthalmologists counsel glaucoma patients about the potential risks of glucosamine and encourage cessation in uncontrolled intraocular pressure.
ARTICLE | doi:10.20944/preprints201808.0287.v1
Subject: Engineering, Chemical Engineering Keywords: CO2 reduction; Photoreduction; Titania; Photocatalysis; High pressure photocatalysis
Online: 16 August 2018 (14:04:33 CEST)
The photoreduction of CO2 is an intriguing process, which allows the synthesis of fuels and chemicals. One of the limitations for CO2 photoreduction in the liquid phase is its low solubility in water. This point has been here addressed by designing a fully innovative concept of pressurized photoreactor, allowing operation up to 20 bar and applied to improve the productivity of this very challenging process. The photoreduction of CO2 in the liquid phase was performed using commercial TiO2 (Evonink P25), TiO2 obtained by flame spray pyrolysis (FSP) and gold doped P25 (0.2 wt% Au-P25) in the presence of Na2SO3 as hole scavenger (HS). The different reaction parameters (catalyst concentration, pH and amount of HS) have been addressed. The products in liquid phase were formic acid and formaldehyde. Moreover, for longer reaction time and with total consumption of HS, gas phase products formed (H2 and CO) after accumulation of significant amount of organic compounds in the liquid phase, due to their consecutive photoreforming. Enhanced CO2 solubility in water was achieved by adding a base (pH= 12-14). In basic environment, CO2 formed carbonates which further reduced to formaldehyde and formic acid and consequently formed CO/CO2+H2 in the gas phase through photoreforming. The deposition of small Au nanoparticles (3-5 nm) (NPs) onto TiO2 was found to quantitatively influence the products distribution and increase the selectivity towards gas phase products.
ARTICLE | doi:10.20944/preprints201807.0308.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: porosity; multijetfusion; fluids; watertightness; 3Dprint; orientation; pressure; leakage;
Online: 17 July 2018 (11:10:14 CEST)
The aim of this paper is to explore the watertightness behaviour for high pressure applications using Multijetfusion technology and polyamide 12 as a material. It reports an efficient solution for manufacturing functional prototypes and final parts for water pressure applications. It provides manufacturing rules to engineers in the pressurized product development process up to 10 MPa of nominal pressure. The research findings show manufacturers the possibility of using additive manufacturing as an alternative to traditional manufacturing. Water leakage was studied using different printing orientations and wall thickness for a range of pressure values. An industrial ball valve was printed and validated with the ISO 9393 standard also meeting tolerance requirements. This paper is a pioneering approach to the additive manufacturing of high performance fluid handling components. This approach solves the problem of leakage caused by porosity in additive manufacturing technologies
ARTICLE | doi:10.20944/preprints201806.0183.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: FeSe2; high pressure; low temperature; single crystal diffraction
Online: 12 June 2018 (10:25:24 CEST)
We conducted an in-situ crystal structure analysis of ferroselite at non-ambient conditions. The aim is to provide a solid ground to further the understanding of the properties of this material in a broad range of conditions. Ferroselite, marcasite-type FeSe2, was studied under high pressures up to 46 GPa and low temperatures, down to 50 K using single-crystal microdiffraction techniques. High pressure and low temperatures were generated using a diamond anvil cell and a cryostat. We found no evidences of structural instability in the explored P-T space. The deformation of the orthorhombic lattice is slightly anisotropic. As expected, the compressibility of the Se-Se dumbbell, the longer bond in the structure, is larger than that of the Fe-Se bonds. Less obvious is the behavior of the octahedral bonds, the shorter bond is the most compressible determining a small increase in the octahedron distortion with pressure. We also achieved a robust structural analysis of ferroselite at low temperature in the diamond anvil cell. Structural changes upon temperature decrease are small but qualitatively similar to those produced by pressure.
ARTICLE | doi:10.20944/preprints201805.0446.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: plasma-TIG; coupled arc; arc profile; pressure distribution
Online: 30 May 2018 (09:39:07 CEST)
In this article, a novel hybrid welding process called plasma-TIG coupled arc welding was proposed to improve the efficiency and quality of welding by utilizing the full advantage of plasma and TIG welding processes. The two arcs of plasma and TIG were pulled into each other into one coupled arc under the effect of Lorentz force and plasma flow force during welding experiments. The arc behavior of coupled arc was studied by means of it’s arc profile, arc pressure and arc force conditions. The coupled arc pressure distribution measurements were performed. The effects of welding conditions on coupled arc pressure were evaluated and the maximum coupled arc pressure was improved compared with single-plasma arc and single-TIG arc. It was found that the maximum arc pressure was mainly determined by plasma arc current and plasma gas flow. According to the results, the proposed coupled arc welding process have both advantages of plasma arc and TIG method, and it has a broad application prospect.
ARTICLE | doi:10.20944/preprints201711.0179.v2
Subject: Engineering, Energy And Fuel Technology Keywords: methane; desorption; hydraulic; thermal; high pressure water injection
Online: 10 May 2018 (08:22:23 CEST)
Moisture and thermal are the key factors for influencing methane desorption during CBM exploitation. Using high pressure water injection technology into coalbed, new fractures and pathways are formed to methane transport. It is existed a phenomenon of water inhibiting gas flow. This study is focused on various water pressures impacted on gas adsorbed coal samples, then the desorption capacity could be revealed under different conditions. And the results are shown that methane desorption capacity was decreased with water pressure increased at room temperature and the downtrend would be steady until water pressure was large enough. Heating could promote gas desorption capacity effectively, with the increasing of water injection pressures, the promotion of thermal on desorption became more obvious. These results are expected to provide a clearer understanding of theoretical efficiency of heat water or steam injection into coalbed, they can provide some theoretical and experimental guidance on CBM production and methane control.
CASE REPORT | doi:10.20944/preprints201712.0044.v1
Subject: Engineering, Energy And Fuel Technology Keywords: reciprocating pump; oil station; pipeline; vibration; pressure pulsation
Online: 7 December 2017 (14:46:23 CET)
Due to the periodic movement of the piston in the reciprocating pump, the fluid will cause pressure pulsation, and the vibration of the pipeline will lead to instrument distortion, pipe failure and equipment damage. Therefore, it is necessary to study the vibration phenomena of the reciprocating pump pipeline based on the pressure pulsation theory. This paper starts from the reciprocating pump pipe pressure pulsation caused by fluid, pressure pulsation in the pipeline and the excited force is calculated under the action of the reciprocating pump. Then, the numerical simulation model is established based on the pipe beam model, and the rationality of the numerical simulation method is verified by the indoor experiment. Finally, a case study is taken as an example to analyze the vibration law of the pipeline system, and proposed the stress reduction and vibration reduction measures. The main conclusions are drawn from the analysis: (1) Excited force is produced in the bend or tee joint, and it can also influence the straight pipe in different levels; (2) In this pipeline system, the pump discharge pipe has a larger vibration amplitude and lower natural frequency; (3) The vibration amplitude increases with the pipe thermal stress, and when the oil temperature is higher than 85°C, it had a greater influence on the vertical vibration amplitude of the pipe.
ARTICLE | doi:10.20944/preprints201806.0025.v1
Subject: Engineering, Energy And Fuel Technology Keywords: high pressure hydrogen; metal hydride-based high pressure compression; techno-economic analysis; Ti-based AB2 metal hydrides; mini-channel heat exchanger
Online: 4 June 2018 (09:36:54 CEST)
Traditional high pressure mechanical compressors account for over half of the car station’s cost, have insufficient reliability and are not feasible for a large-scale fuel cell market. An alternative technology, employing a two-stage, hybrid system based on electrochemical and metal hydride compression technologies, represents an excellent alternative to conventional compressors. The high-pressure stage, operating at 100-875 bar, is based on a metal hydride thermal system. A techno-economic analysis of the metal hydride system is presented and discussed. A model of the metal hydride system was developed, integrating a lumped parameter mass and energy balance model with an economic model. A novel metal hydride heat exchanger configuration is also presented, based on mini-channel heat transfer systems, allowing for effective high-pressure compression. Several metal hydrides were analyzed and screened, demonstrating that one selected material, namely (Ti0.97Zr0.03)1.1Cr1.6Mn0.4, is likely the best candidate material to be employed for high-pressure compressors under the specific conditions. System efficiency and costs were assessed based on the properties of currently available materials at industrial levels. Results show that the system can reach pressures on the order of 875 bar with thermal power provided at approximately 150 °C. The system cost is comparable with the current mechanical compressors and can be reduced in several ways as discussed in the paper.
ARTICLE | doi:10.20944/preprints202311.1328.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: deoxycholic acid; blood pressure; cardiac output; vasodilatation; bacterial metabolites
Online: 21 November 2023 (13:19:07 CET)
Background: Deoxycholic acid (DCA) is a secondary bile acid produced by gut bacteria. Its serum concentration increases in cardiovascular disease (CVD). We hypothesized that DCA may affect hemodynamic parameters in rats. Methods: The concentration of DCA in systemic blood was measured with liquid chromatography coupled with mass spectrometry. Arterial blood pressure (BP), heart rate (HR) and echocardiographic parameters were evaluated in anesthetized, male, 3-4-month-old Sprague-Dawley rats administered intravenously (IV) or intracerebroventricularly (ICV) with investigated compounds. Mesenteric artery (MA) reactivity was tested ex vivo. Results: The baseline plasma concentration of DCA was 0.24 ± 0.03 mg/l. The oral antibiotic treatment produced a large decrease in the concentration. Administered IV, the compound increased BP and HR in a dose-dependent manner. DCA also increased heart contractility and cardiac output. None of the tested compounds: prazosin (an alpha-blocker), propranolol (beta-adrenolytic), atropine (muscarinic receptor antagonist), glibenclamide (K-ATP inhibitor) or DY 268 (FXR antagonist), glycyrrhetinic acid (11HSD2 inhibitor) significantly diminished the DCA-induced pressor effect. ICV infusion did not exert significant HR or BP changes. DCA relaxed MAs. Systemic vascular resistance did not change significantly. Conclusions: DCA increases BP by increasing cardiac output. As a bioactive gut bacteria-derived metabolite, DCA may co the interaction between gut microbiota and the host’s circulatory system.
ARTICLE | doi:10.20944/preprints202310.1017.v1
Subject: Medicine And Pharmacology, Hematology Keywords: roxadustat; rhEPO; blood pressure; micro-inflammatory state; lipid metabolism
Online: 17 October 2023 (08:29:21 CEST)
Objective To observe the effect of roxadustat on blood pressure and micro-inflammatory response in patients with hemodialysis anemia, and to provide a viable technique for the treatment of hemodialysis anemia patients. Methods A total of 100 hemodialysis anemia patients admitted to the Nephrology Department of our hospital from July 2020 to July 2021 were enrolled and randomly divided into an observation group (roxadustat) and a control group (human recombinant erythropoietin (rhEPO). The clinical efficacy, blood lipid metabolism, inflammatory factor levels, iron metabolism-related indicators, blood biochemical indicators, anemia indicators, adverse reactions and blood pressure were recorded and compared. Results There was no significant difference in baseline data and serum indicators (P>0.05). The study group demonstrated superior performance to the control group in terms of clinical efficacy, blood lipid metabolism, inflammatory factor levels, iron metabolism-related indicators, blood biochemical indicators, anemia indicators, adverse reactions and blood pressure (all P<0.05). Conclusion Compared with rhEPO treatment, roxadustat exhibits a promising outcome in treating anemia and has slight impact on blood pressure of patients.
ARTICLE | doi:10.20944/preprints202309.1262.v1
Subject: Medicine And Pharmacology, Orthopedics And Sports Medicine Keywords: unilateral neck pain; myofascial stiffness; indentometry; pain pressure threshold
Online: 19 September 2023 (08:29:35 CEST)
(1) Background: Globally, neck pain is prevalent, affecting around thirty percent of the population annually. To better understand the influence of pain on the myofascial layers, the present study investigated these on the upper trapezius muscle in unilateral, more severe neck pain. (2) Methods: This study was a cross-sectional study. Forty patients (42.2 ± 14.7) with a confirmed diagnosis of unilateral neck pain were examined using durometry and indentometry. The study evaluated stiffness, elasticity, and pressure pain threshold of both sides of the neck (symptomatic side: SS; healthy side: HS). Furthermore, the range of motion of the cervical spine (lateral flexion, rotation) was quantified using a digital goniometer. (3) Results: A significant lateral discrepancy was observed in stiffness between groups (durometry: SS – 33.76 ± 7.78, HS – 29.75 ± 7.45, p<0.001; indentometry: SS – 59.73 ± 33.93, HS – 4.18 ± 12.69, p=0.024). In contrast, no differences were found between the comparison sides of the upper trapezius for the parameter’s elasticity (SS – 0.101 ± 1.09, HS – -0.006 ± 0.29, p=0.416), cervical spine mobility (lateral flexion: SS – 37.08 ± 8.15, HS – 37.73 ± 7.61, p=0.559; rotation: SS – 73.55 ± 12.37, HS – 72.85 ± 11.10, p=0.660) and algometry (SS – 36.41 ± 17.53, HS – 37.22 ± 17.00, p=0.657). (4) Conclusion: Overall, it can be concluded that more severe neck pain unilaterally shows differences in stiffness on the same side. Future research is needed to investigate the links.
ARTICLE | doi:10.20944/preprints202308.1799.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: ocean; pollution; anthropogenic pressure; bivalves; food resources; sea water
Online: 25 August 2023 (10:44:09 CEST)
The accumulation of microplastics in the world oceans is one of the main global problems of the modern world. The Black Sea is the main source of seafood for people from several countries, including Bulgaria. The pollution of the Black sea is a result of various factors, especially anthropogenic. The present study demonstrated detailed MPs contamination of five fish species important for the commercial fishing (Garfish, Мullet, Knout goby, Pontic shad and Mediterranean horse mackerel) collected from the Sozopol area on the Bulgarian Black Sea coast. Within each microplastic morphological group, three size classes were recognized: 100-200 µm, 25-100 µm, and ≤ 25 µm. Microplastics were found in the soft tissues of all studied specimens but in a different ratio of pellets, fibers and fragments. Generally, the pellets were the most often registered particles, followed by irregularly-shaped fragments, whereas fibers were less numerous. The dominant part of the isolated plastics are made of polyethylene (PE), and polyethylene terephthalate (PET). Our results pointed out serious pollution with plastic particles in the Bulgarian Black Sea aquatory, which in the future may seriously affect the health of the fish population and also human health.
ARTICLE | doi:10.20944/preprints202308.1270.v1
Subject: Public Health And Healthcare, Public, Environmental And Occupational Health Keywords: albuminuria; blood pressure; cadmium; chronic kidney disease; estimated GFR
Online: 17 August 2023 (08:07:45 CEST)
Cadmium (Cd) is a pervasive, toxic environmental pollutant that preferentially accumulates in tubular epithelium of the kidney. Current evidence suggests that the cumulative burden of Cd here leads to progress loss of the glomerular filtration rate (GFR). In this study, we have quantified changes in estimated GFR (eGFR) and albumin excretion (Ealb) in according to levels of blood Cd ([Cd]b) and excretion of Cd (ECd) after adjustment for confounders. ECd and Ealb were normalized to creatinine clearance (Ccr) as ECd/Ccr and Ealb/Ccr. Among 482 residents of Cd-polluted and non-polluted regions of Thailand, 8.1% had low eGFR and 16.9% had albuminuria, (Ealb/Ccr)×100 ≥ 20 mg/L filtrate. In the low Cd burden group, (ECd/Ccr) ×100 < 1.44 µg/L filtrate, eGFR did not correlate with ECd/Ccr (β = 0.007), while an inverse association with ECd/Ccr was found in the medium (β =−0.230) and high-burden groups (β =−0.349). Prevalence odds ratios (POR) for low eGFR were increased in the medium (POR 8.26) and high Cd burden groups (POR 3.64). Also, eGFR explained a significant proportion of Ealb/Ccr variation among those with middle (η2 0.093) and high [Cd]b tertiles (η2 0.132), but did not with low tertile (η2 0.001). With adjustment of eGFR, age and BMI, POR values for albuminuria were increased in the middle (POR 2.36) and high [Cd]b tertiles (POR 2.74) and those with diabetes (POR 6.02) and hypertension (2.05). These data argue that ECd/Ccr of 1.44 µg/L filtrate (0.01−0.02 µg/g creatinine) could determine a Cd threshold level from which protective exposure guidelines should be formulated.
ARTICLE | doi:10.20944/preprints202307.1194.v1
Subject: Chemistry And Materials Science, Paper, Wood And Textiles Keywords: Vacuum-pressure impregnation; larch, Larix kaempferi; flame retardant; grooving
Online: 18 July 2023 (13:32:07 CEST)
Due to wood’s susceptibility to fire, it is crucial to treat wood-based materials with flame retardants, especially in construction applications. This study investigated the effectiveness of various grooving types, including transverse, longitudinal, both transverse and longitudinal, and surface grooving, in enhancing larch's vacuum pressure impregnation process. The results revealed that transverse grooving provided a slightly greater impregnation advantage than longitudinal grooving. Moreover, exceptional impregnation performance was observed in larch samples subjected to both longitudinal and transverse grooving and surface grooving, exhibiting a remarkable improvement of 214,7 % compared to untreated larch.
ARTICLE | doi:10.20944/preprints202307.0439.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: physical property; sodium alginate; extraction condition; high pressure homogenization
Online: 7 July 2023 (05:40:55 CEST)
In this study, we had investigated the use of high-pressure homogenization (HPH) as a novel pretreatment method for the extraction of sodium alginate (SA) from Laminaria japonica. Our results demonstrated that under optimal condition of 100 MPa HPH pressure, 4 cycles, pH 6.0, and 0.5% ethylene diaminetetra acetic acid tetrasodium salt (EDTA) concentration (w/v) for 3.0 hours, the extraction yield of HPH reached 34%, which was higher than that achieved by previous methods such as complex enzyme hydrolysis (CE), ultrasonic-assisted extraction (UAE), and complex enzyme-ultrasonic combined method (CE-UC). To further characterize the extracted SA, we conducted a comprehensive analysis using SEM, FTIR, MRS, NMR, XRD, TGA, and T-AOC assay. Our findings revealed the following: 1) HPH treatment significantly disrupted the structure of L. japonica cells and reduced their crystallinity to 76.27%, the lowest among all pretreatment samples; 2) the extracted SA had a greater tendency to form elastic gels; and 3) the antioxidant activity of HPH-extracted SA reached 0.02942 mgVceq∙mg-1, which was the highest among all tested methods. Based on these results, we concluded that HPH extraction not only increased the yield of SA but also enhanced its antioxidant activity.
ARTICLE | doi:10.20944/preprints202306.1126.v1
Subject: Environmental And Earth Sciences, Other Keywords: MICP; Sandy slope; Pore water pressure; Fluid-slip pattern
Online: 15 June 2023 (12:45:48 CEST)
With the development of free trade port in Hainan Island, the construction of tourist roads around the island is also in full swing. Under the weather conditions of strong typhoon and rainstorm in Hainan, the highway cutting slope built on the coastal weak sandy terraces has strong sand loss and is easy to be scour by rainfall. MICP green spray irrigation solidification technology is used to strengthen the sandy cutting, and pore water pressure monitoring is carried out on the slope model during MICP solidification and rainfall scour. Combined with the model pore water pressure and flow slip failure pattern, dynamic analysis was carried out. The results show that MICP sprinkler irrigation technology can solidified the surface of the slope model in a short time, and the cementation depth of the model reaches 4cm after three sets of rotation reinforcement. The surface reinforcement effect is good, and the sand samples are closely connected. Under the erosion effect of simulated rainfall intensity, the sand loss of the slope is weakened, and no sand binding damage occurs, and the integrity is enhanced. Due to the cementation between sand grains, most of the rainfall was converted into runoff, and the slope slid after 150s. When the slope began to slip, the leading edge of the slope model lost sand and unloaded, and the failure mode was graded creep slip failure. Finally, the slope was divided into several blocks due to the continuous expansion of cracks after the slope failure. The erosion stability of the sandy slope under heavy rains is optimized and the sand loss is prevented effectively. In this study, a new method of MICP remediation techniques is proposed, which provides a new test basis for the application of MICP technology in practical engineering.
ARTICLE | doi:10.20944/preprints202305.1025.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: High Pressure; Phase Transition; Synchrotron Radiation, X-ray Diffraction
Online: 15 May 2023 (10:37:43 CEST)
Co-doped SnO2 nanocrystals with tetragonal rutile-type (space group P42/mnm) structure have been investigated using in-situ high-pressure synchrotron angle dis-persive X-ray diffraction till 20.9 GPa at ambient temperature. The analysis of ex-perimental results based on Rietveld refinements suggest that rutile-type SnO2 un-dergoes a structural phase transition at 14.2 GPa to an orthorhombic CaCl2-type phase (space group Pnnm) with no coexistence during the phase transition. No further phase transition is observed till 20.9 GPa. The low-pressure and high-pressure phases are related via a group/subgroup relationship. However, as a discontinuous change in the unit-cell volume is detected at the phase transition, thus, the phase transition can be classified as first-order type. On decompression the transition is found to be re-versible. The results are compared with previous high-pressure studies on SnO2.
ARTICLE | doi:10.20944/preprints202304.0168.v1
Subject: Public Health And Healthcare, Nursing Keywords: Central venous pressure; intensive care units; questionnaire; reliability; validity
Online: 10 April 2023 (10:27:04 CEST)
Although, central venous pressure (CVP) is among the most frequent estimated hemodynamic parameters in the critically ill setting, extremely little is known on how intensive care unit (ICU) nurses use this index in their decision-making process. The purpose of the study was to develop a new questionnaire for accessing how ICU nurses use CVP measurements to address patients’ he-modynamics investigating its validity and reliability. A cross-sectional study was conducted among 120 ICU nurses from four ICUs of Greece. Based on a comprehensive literature review and the evaluation of a five-experts panel a new questionnaire, named “CVP-Score”, was created having 8 items. The construct validity and the reliability of the questionnaire were examined. The half of the study participants’ (51.7%) was working at a specialized ICU, and they had a mean [±Standard Deviation (SD)] ICU experience of 13(±7.1) years. The estimated construct validity of the new-developed tool was acceptable, while the internal consistency reliability as measured by Cronbach alpha was excellent (0.901). CVP Score had acceptable test-retest reliability (r=0.996, p<0.001) and split-half reliability (0.855). CVP Score is a valid and reliable instrument for measuring how critical care nurses use CVP measurements in their decision-making process.
ARTICLE | doi:10.20944/preprints202302.0385.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: minimum miscibility pressure (MMP); swelling factor; carbondioxide (CO2); slimtube
Online: 22 February 2023 (10:52:06 CET)
Minimum miscibility pressure (MMP) and oil swelling are two important factors of carbondioxide (CO2) gas displacement mechanism occurred in the reservoir relate to application of CO2 injection in the field to enhance oil recovery. In this paper determination of minimum miscibility pressure (MMP) between crude oil samples with carbondioxide gas conducted using two methods, i.e. correlation methods and laboratory experiment using slimtube. While, determination of swelling factor was conducted using PVT cell, where recombined fluid injected and conditionally at the reservoir temperature. The results of MMP using empirical equation (2807 Psig) and Holm & Josendal correlation (2750 Psig) is more approximate to the result of laboratory analysis (2805 Psig). The result of swelling test during injection CO2 gas processes until 46.82% mole, shows that bubble point pressure is increasing gradually from 410 psig through 2200 psig, and swelling factor was also increase from 1.0 through 1.442. Based on the value of fracture pressure of Layer F in the KHL Field is 2200 Psig and MMP is 2805 Psig, hence the application of CO2 gas injection in the field only could be conducted as immiscible flooding.
ARTICLE | doi:10.20944/preprints202302.0202.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: Dyslipidemia; Atrial Fibrillation; Geriatrics; High Blood Pressure; Polymedication; Polypill
Online: 13 February 2023 (07:21:50 CET)
INTRODUCTION: Cardiovascular prevention is less effective than expected due to the concern about polymedication of professionals and the lack of adherence of patients. Polypills are presented as a possible solution, increasing therapeutic adherence in the medium or long term and improving therapeutic results compared to the administration of drugs separately: they increase effectiveness and Adherence of patients to primary and secondary cardiovascular prevention programs, without increasing the cost of the intervention. OBJECTIVES: Study #Trigeria: to specify the combined prevalence of Atrial Fibrillation, Dyslipidemia and Hypertension and analyze the pharmacological prescription for these pathologies and the possible indications and advantages that would have the prescription of a polypill for these risk factors.METHODS: Observational analytical study on the pathological history in elderly institutionalized in nursing homes and analysis of prescribed oral medication.RESULTS: 169 people analyzed (79.3% women) from 4 nursing homes; 8.9% had a history of Atrial Fibrillation, Dyslipidemia and Arterial Hypertension; these had a higher prevalence of heart disease (42.9%) and Cerebral Vascular Accident (35.7%). Polymedication was present in 88.5%, with an average of 6.94 oral drugs prescribed; among those with the three pathological antecedents, the average number of oral medications was 8.60. Only 26.7% of those with all three factors were prescribed drugs to control them.DISCUSSION: There are high rates of polymedication in the sample and low rates of prescription of antiplatelet agents in people with Atrial Fibrillation (26.5%); the low prescription of statins and antihypertensives of the ACE inhibitor or ARB-II groups may be due to good control with non-pharmacological measures or by the use of other groups of drugs . A polypill holding the drugs that control the three factors studied could increase the prescription rate while simplifying the administration schedule and reducing polymedication by 23.25% improving prescription, increasing adherence and control of risk factors without increasing pharmaceutical expenditure.CONCLUSIONS: There is a low rate of prescription of antiplatelet agents among people with atrial fibrillation. Combination methods (polypills) can increase the suitability of prescriptions in people with polypathology, improving prescribing, simplifying administration and increasing adherence to pharmacological treatments.
ARTICLE | doi:10.20944/preprints202205.0346.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: β-adrenoceptor; diabetes; empagliflozin; heart; pressure-volume loop analysis
Online: 25 May 2022 (09:59:26 CEST)
Diabetes mellitus leads to cardiovascular complications including impaired cardiac β-adrenoceptor (β-AR) function. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, such as empagliflozin (EMPA) improve outcomes in heart failure patients and animal models thereof. Therefore, we have investigated the effects of EMPA on in vivo cardiac function (pressure-volume loop analysis) and β-AR-mediated contractile responses (papillary strips) in streptozotocin (STZ; 40 mg/kg, i.p.)-induced diabes in male Sprague Dawley rats (control, EMPA-treated control, diabetic, EMPA-treated diabetic) in a design reflecting late-onset treatment. 13-16 weeks after STZ injection treatment with a low dose of EMPA (10 mg/kg/day, daily oral gavage) or vehicle was administered for another 8 weeks. EMPA did not change cardiac function in control rats. Diabetic rats had a reduced heart rate, cardiac output, stroke work, rate of contration and rate of relaxation and increased isovolumic relaxation, whereas in vitro responses were not markedly attenuated. Treatment with EMPA showed a trend for improvement of some but not all parameters. Our results indicate that low dose EMPA treatment had limited effects on cardiac impairment despite reducing blood glucose when initiated after diabetes is manifest. Future studies with a higher dose and greater sample sizes could help to clarify the possible benefits of EMPA on the diabetic heart.
ARTICLE | doi:10.20944/preprints202110.0115.v1
Subject: Medicine And Pharmacology, Clinical Medicine Keywords: intracranial compliance; intracranial pressure; intracranial hypertension; acute brain injury
Online: 7 October 2021 (10:54:26 CEST)
We validated a new noninvasive tool (B4C) to assess intracranial pressure waveform (ICPW) morphology in a set of neurocritical patients, correlating the data with ICPW obtained from invasive catheter monitoring. Materials and Methods: Patients undergoing invasive intracranial pressure (ICP) monitoring were consecutively evaluated using the B4C sensor. Ultrasound-guided manual internal jugular vein (IJV) compression was performed to elevate ICP from the baseline. ICP values, amplitudes, and time intervals (P2/P1 ratio and time-to-peak [TTP]) between the ICP and B4C waveform peaks were analyzed. Results: Among 41 patients, the main causes for ICP monitoring included traumatic brain injury, subarachnoid hemorrhage, and stroke. Bland-Altman’s plot indicated agreement between the ICPW parameters obtained using both techniques. The strongest Pearson’s correlation for P2/P1 and TTP was observed among patients with no cranial damage (r = 0.72 and 0.85, respectively) in detriment of those who have undergone craniotomies or craniectomies. P2/P1 values of 1 were equivalent between the two techniques (area under the receiver operator curve [AUROC], 0.9) whereas B4C cut-off 1.2 was predictive of intracranial hypertension (AUROC 0.9, p < 000.1 for ICP > 20 mmHg). Conclusion: B4C provided biometric amplitude ratios correlated with ICPW variation morphology and is useful for noninvasive critical care monitoring.
ARTICLE | doi:10.20944/preprints202109.0235.v1
Subject: Medicine And Pharmacology, Ophthalmology Keywords: Glaucoma; TrabEx; Trabectome; ab-interno trabeculectomy; prognosis; intraocular pressure
Online: 14 September 2021 (11:01:38 CEST)
Purpose: To compare ab interno trabeculectomy by trabecular meshwork excision to plasma-mediated ablation in primary open-angle glaucoma. Methods: Retrospectively collected data of TrabEx+ (TEx, n=56) and Trabectome (T, n=99) were compared by coarsened exact matching to reduce confounding and matched based on baseline IOP and age. Primary outcomes were IOP and number of glaucoma medications. Complications and need for additional glaucoma surgery were assessed. Patients were followed for up to one year. Results: 53 TEx could be matched to T. Baseline IOP was 16.5±4.6 mmHg in both; age was 73.7±8.8 and 71.5±9.9 years in TEx and T, respectively. TEx were taking more medications than T (p<0.001). IOP was reduced to 14.8±4.3 in TEx and to 13.4±3.4 in T at 6 months, and to 14.9±6.0 (p=0.13) in TEx and to 14.1±3.8 mmHg (all p<0.05) in T at 12 months. Medications were reduced at both 6 and 12 months (p< 0.05). No differences were seen between TEx and T at 6 and 12 months. In TEx, only one serious complication occurred, and two patients required further glaucoma surgery. Conclusion: Although both groups had a baseline IOP considered low for ab-interno trabeculectomy, IOP and medications were reduced further at 6 and 12 months. IOP reduction did not reach significance in TEx at 12 months. The inter-group comparison did not reveal any significant differences. Both had a low complication rate.
ARTICLE | doi:10.20944/preprints202108.0533.v1
Subject: Medicine And Pharmacology, Ophthalmology Keywords: glaucoma progression; nycthemeral intraocular pressure; right-left comparison; laterality
Online: 30 August 2021 (09:52:58 CEST)
Purpose: To determine whether 24-hour IOP monitoring can be a predictor for glaucoma progression and to analyze the inter-eye relationship of IOP, perfusion and progression parameters. Methods: We extracted data from manually drawn IOP curves with HIOP-Reader, a software suite we developed. The relationship between measured IOPs and mean ocular perfusion pressures (MOPP) to retinal nerve fiber layer (RNFL) thickness was analyzed. We determined the ROC curves for peak IOP (Tmax), average IOP (Tavg), IOP variation (IOPvar) and historical IOP cut-off levels to detect glaucoma progression (rate of RNFL loss). Bivariate analysis was conducted to check for various inter-eye relationships. Results: 217 eyes were included. The average IOP was 14.8±3.5 mmHg, with a 24-hour variation of 5.2±2.9 mmHg. 52% of eyes with RNFL data showed disease progression. There was no significant difference in Tmax, Tavg and IOPvar between progressors and non-progressors (all p>0.05). Except for Tavg and the temporal RNFL, there was no correlation between disease progression in any quadrant, Tmax, Tavg and IOPvar. 24-hour and outpatient IOP variables had poor sensitivities and specificities in detecting disease progression. The correlation of inter-eye parameters was moderate; correlation with disease progression was weak. Conclusion: In line with our previous study, IOP data obtained during a single visit (outpatient or inpatient monitoring) make for a poor diagnostic tool, no matter the method deployed. Glaucoma progression and perfusion pressure in left and right eyes correlated weakly to moderately with each other.
ARTICLE | doi:10.20944/preprints202106.0716.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: intracranial compliance; intracranial pressure; decompressive craniectomy; acute brain damage
Online: 29 June 2021 (23:58:09 CEST)
Background: Morphological alterations in intracranial pressure pulse waveform (ICPPW) secondary to intracranial hypertension (ICP >20 mmHg) and reduction in intracranial compliance (ICC) are well known indicators of neurological severity. To date, no studies have documented the ICPPW modifications after intracranial hypertension resolution with decompressive craniectomy (DC). The present study aimed to assess the morphological alterations in ICPPW among neurocritical care patients with and without DC, by comparing the variations of ICPPW features according to elevations in mean ICP values. Methods: Patients requiring ICP monitoring because of severe traumatic or spontaneous conditions were included. Mean ICP values were compared with ICPPW features (P2/P1 ratio, TTP and pulse amplitude). Elevation in ICP was produced by means of ultrasound-guided manual internal jugular veins compression. Results were distributed for three groups: intact skull (exclusive burr hole for ICP monitoring), craniotomy/large fractures (group 2) or DC (group 3). Results: 57 patients were analyzed. 21 (36%) presented no skull defects, whereas 15 (26%) had DC. ICP was not significantly different between groups: ±13.59 for intact and ±17.66 mmHg for DC, with ICP induced elevation also similar between groups (p= 0.56). Significant elevation was observed for P2/P1 ratio for groups 1 and 2, whereas reduction was observed in group 3 (elevation of ±0.09 for groups 1 and 2, whereas reduction of 0.03 for group 3, p=0.01). Conclusion: In the present study, intracranial pressure pulse waveform analysis indicated that intracranial compliance was significantly more impaired among decompressive craniectomy patients, although ICPPW indicated DC to be protective for further influences of ICP elevations over the brain. Analysis of ICPPW seems to be an alternative to real time ICC assessment.
ARTICLE | doi:10.20944/preprints202106.0428.v1
Subject: Physical Sciences, Acoustics Keywords: whispering gallery modes; microsphere; membrane; pressure sensor; optical interference
Online: 16 June 2021 (09:28:30 CEST)
We propose the physical proof-of-concept of a new simple miniature pressure sensor based on the whispering gallery modes (WGMs) optically excited in a dielectric microsphere placed near a flexible reflective membrane, which acts as an ambient pressure sensing element. WGMs excitation is carried out by free-space coupling of optical radiation to a microsphere. The distinctive feature of proposed sensor design is double excitation of optical eigenmodes by forward and backward propagating radiation reflected from a membrane that causes WGMs interference in particle volume. The optical intensity of resulting resonant field established in the microsphere carries information about the exact position of the pressure-loaded reflecting membrane. The sensitivity of the proposed sensor strongly depends on the quality factor of the excited resonant mode, as well as geometrical and mechanical parameters of the flexible membrane. We propose to register not the displacement of the position of the WGM resonance, but the change in its amplitude under the influence of the change in the distance between the sphere and the mirror under the influence of pressure. Important advantages of the proposed sensor are miniature design (linear sensor dimensions depends only on the membrane diameter) and the absence of a mechanical contact of pressure-sensitive element with WGM resonator.
TECHNICAL NOTE | doi:10.20944/preprints202101.0444.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: GRACE; Ocean Bottom Pressure; Earthquakes; Mediterranean Ridge accretionary complex.
Online: 22 January 2021 (12:15:52 CET)
Mediterranean Ridge accretionary complex (MAC) is one of the most critical subduction zones in the world. It is known that the region exhibits a continuous mass change (horizontal/vertical movements). This process is associated with the devastating and tragic earthquakes shaking the MAC for centuries. Here, we investigate the ocean bottom pressure (OBP) anomalies in the MAC derived from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow On (GRACE-FO) satellite missions. The OBP time series for the MAC comprises a decreasing trend in addition to 1-, 1.53-, 2.36-, 3.67-, and 9.17-year periodic components partially explained by the atmosphere, oceans, and hydrosphere (AOH) processes, and Earth's pole movement. We noticed that the OBP anomalies appear to link to a rising trend and periods in earthquakes' power time series. This finding sheds new light on the mechanisms controlling the most destructive natural hazard.
ARTICLE | doi:10.20944/preprints202002.0204.v2
Subject: Biology And Life Sciences, Plant Sciences Keywords: pistachio; cashew; allergens; DIC processing; pressure processing; thermal processing
Online: 26 March 2020 (13:41:00 CET)
Pistachio and cashew contain allergenic proteins, which causes them to be removed from the diet of allergic people. Former evidences have demonstrated that food processing (thermal and non-thermal) can produce structural and/or conformational changes in proteins by altering their allergenic capacity. In this study, the influence of Instant Controlled Pressure Drop (DIC) on the pistachio and cashew allergenic capacity has been studied. Western blot was carried out using IgG anti-11S and anti-2S and IgE antibodies from sera of patients sensitized to pistachio and cashew. DIC processing causes changes in the electrophoretic pattern, reducing the number and intensity of protein bands, as the pressure and temperature treatment increment what results in a remarkable decrease of detection of potentially allergenic proteins. The harshest conditions of DIC (7bar, 120s) markedly reduce the immunodetection of allergenic proteins, not only by using IgG (anti 11S and anti 2S) but also when IgE sera from sensitized patients were used for Western blots. Such immunodetection is more affected in pistachio than in cashew nuts, but it not completely removed. Therefore, cashew proteins are possibly more resistant than pistachio proteins. According these findings, Instant Controlled Pressure Drop (DIC) can be considered a suitable technique in order to obtain hypoallergenic tree nuts flour to be used in food industry.