ARTICLE | doi:10.20944/preprints201802.0184.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Water Treatment, Filtration, Modified Perlite, Optical density, wastewater
Online: 27 February 2018 (16:02:02 CET)
Water treatment efficiency of several filter media such as perlite, modified (silicated) perlite, zeolite and sand were studied on wastewater. This study contains 2 distinct experiments which the first one emphasize on the modified perlite’s performance in removing turbidity which has been gone through 3 phases including low turbidity model water, mid turbidity and high turbidity model water; the second experiment underlines the differentiation between 3 evolutionary material based on perlite which undergoes the filtration process with certain turbid model water. It was dedicated that modified perlite removed more than 90% of turbidity and it functions better than other materials with high turbidity (more than100 NTU). The experiments have been conducted with sodium silicate perlite, normal perlite and synthetic zeolite perlite in order to determine the optimized material which is able to be substituted with perlite in the filtration process.
ARTICLE | doi:10.20944/preprints201904.0087.v1
Subject: Materials Science, Polymers & Plastics Keywords: thermoplastic polyurethane; foaming; perforated structure; membrane; filtration
Online: 8 April 2019 (11:24:16 CEST)
The way in which a perforated structure is formed has attracted much interest in the porous membrane research community. This novel structure gives materials an excellent antifouling property as well as a low operating pressure and other benefits. Unfortunately, the current membrane fabrication methods usually involve multi-step processes and the use of organic solvents or additives. Our study is the first to offer a way to prepare perforated membrane by using a physical foaming technique with CO2 as the blowing agent. We selected thermoplastic polyurethane (TPU) as the base material because it is a biocompatible elastomer with excellent tensility, high abrasion resistance, and good elastic resilience. Various processing parameters, which included the saturation pressure, the foaming temperature, and the membrane thickness, were applied to adjust the TPU membrane’s perforated morphology. We proposed a possible formation mechanism of the perforated membrane. The as-prepared TPU membrane had good mechanical properties with a tensile strength of about 5 MPa and an elongation at break above 100%. Such mechanical properties make this novel membrane usable as a self-standing filter device. In addition, its straight-through channel structure can separate particles and meet different separation requirements.
ARTICLE | doi:10.20944/preprints201905.0204.v2
Subject: Engineering, Civil Engineering Keywords: groundwater; pre-treatment; contact filtration; infiltration ponds; nutrients removal; TP; Cyanobacteria; Cyanotoxin; microcystin-LR; eutrophic lakes; TOC
Online: 19 August 2019 (04:08:58 CEST)
Artificial groundwater recharge is commonly used for drinking water supply. The resulting water quality is highly dependent on the raw water quality. In many cases, pre-treatment is required. Pre-treatment improves the drinking water quality, although how and to what extent it affects the subsequent pond water quality and infiltration process, is still unknown. We evaluated two treatment systems by applying different pre-treatment methods for raw water from a eutrophic and temperate lake. An artificial recharge pond was divided into two parts, where one received raw water, only filtered through a micro-screen with 500 µm pores (control treatment), while the other part received pre-treated lake water using chemical flocculation with polyaluminium chloride (PACl) combined with sand filtration, i.e. continuous contact filtration (contact filter treatment). Water quality such as cyanobacterial biomass, microcystin-LR as well as organic matter and nutrients were measured in both treatment processes. We found cyanobacterial biomass and microcystin-LR level after the contact filter treatment was significantly different from the control treatment and also significantly different in the pond water. In addition, with contact filter treatment, total phosphorus (TP) and organic matter removal were significantly improved in the end water, TP was reduced by 96 % (< 20 µg/L) and the total organic carbon (TOC) was reduced by 66 % instead of 55 % (TOC content around 2.1 mg/L instead of 3.0 mg/L). This full-scale onsite experiment demonstrated effective pre-treatment would benefit a more stable water quality system, with less variance and lower cyanotoxin risk. In a broader drinking water management perspective, the presented method is promising to reduce cyanotoxin risk, as well as TP and TOC, which are all predicted to increase with global warming and extreme weather.
REVIEW | doi:10.20944/preprints202206.0156.v1
Subject: Materials Science, Nanotechnology Keywords: Nanofibres; membranes; water filtration; vapour; chemical
Online: 10 June 2022 (08:19:03 CEST)
Nanofibres have gained increasing attention due to their advantages of having a high porous structure, narrow pore size and distribution, and a high specific surface area. One of the most efficient techniques for producing nanofibres is via electrospinning. Nanofibres are currently being used in various fields, including water filtration. Although nanofibres possess the ability to filter various components, the fibres generally have a low mechanical strength that can mitigate the performance over time. Therefore, in overcoming this issue, several studies have focused on improving the strength of the nanofibre membranes for a water filtration application. This review discusses the advantages and challenges of nanofibres for water filtration membranes and summarises the methods to increase the strength of the membranes, including solvent vapour, thermal treatment, and chemical crosslinking.
ARTICLE | doi:10.20944/preprints202105.0483.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Filtration; Flux density function; Protein crystals
Online: 20 May 2021 (11:07:11 CEST)
Development and engineering of protein crystals regarding mechanical stability and crystallizability occurs on a small scale. Later in the process chain of industrial production however, filtration properties are important to separate the crystals from mother liquor. Many protein crystals are sensitive to mechanical stress which is why it is important to know the filtration behavior early on. In this study we analyze settling and filtration behavior of isometric, rod-like and needle shaped lysozyme and rod-like alcohol dehydrogenase (ADH) crystals on a small scale using an optical analytical centrifuge. Needle shaped lysozyme and rod-like ADH crystals show compressible material behavior. With the results from settling and filtration experiments the flux density function is calculated and modeled which can be used to describe the whole settling and permeation process in dependency of the solids volume fraction. This is also an issue for simulations of industrial processes.
ARTICLE | doi:10.20944/preprints201912.0055.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: dielectrophoresis; porous media; filtration; ac electrokinetics
Online: 4 December 2019 (12:54:38 CET)
State-of-the-art dielectrophoretic (DEP) separation techniques provide unique properties to separate particles from a liquid or particles with different properties such as material, morphology or size from each other. However, such separators do not operate at throughput that is sufficient for a vast fraction of separation tasks. The reason for this limitation is that, in order to move particles by dielectrophoresis, high electric field gradients to drive the separation are required. Conventionally, those gradients are generated by electrode microstructures that limit the maximum channel size. Here, we investigate DEP filtration, a technique that uses open porous microstructures instead of microfluidic devices to easily increase the filter cross section and therefore also the processable throughput by several orders of magnitude. Previously, we already separated baker’s yeast by DEP filtration in open porous ceramic structures. Now, we give a more elaborate experimental study about DEP filtration in these open porous structures and separate model particles, that are an order of magnitude smaller (500 nm, polystyrene), from aqueous suspensions. Almost 100% separation at flow rates of up to 9 mL min-1 was achieved while the majority of the trapped particles could be recovered. We show how particle separation depends on key parameters (voltage, throughput, filter structure size). Further, we work towards selective particle separation and show that particle separation is very dependent on the particle polarizability: This creates the possibility to adjust selectivity by changing the electrical conductivity of the suspension around that of the particle. This study highlights the unique qualities of dielectrophoretic filtration enabling switchable, selective, and scalable particle separation to solve existing problems such as cell separation or precious metal recovery.
ARTICLE | doi:10.20944/preprints201611.0027.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: vitamin C; hyperuricemia; gout; glomerular filtration rate
Online: 3 November 2016 (10:49:06 CET)
Abstract: Hyperuricemia is commonly diagnosed in subjects with abnormal purine metabolism. Prolonged hyperuricemia often associated with gout, which is a vital risk factor for joint dysfunction. The current study was designed to determine the efficacy of vitamin C supplements for treatment of high serum uric acid (UA) among hyperuricemic and gouty patients, and finding-out the effect of supplementation on serum creatinine (Cr) level and glomerular filtration rate (GFR). This intervention study was started in April, 2013, till two months. A convenient sample of 30 adults aged between 24-75 years of both genders was assigned into two study groups: hyperuricemic (n=15) and gouty (n=15) groups. Each participant supplemented with 500 mg/day vitamin C chewable tablets for 2 months. Serum UA, Cr, and GFR were measured before and after treatment. At the end of this study, Cr and GFR enhanced insignificantly in both groups. UA increased insignificantly in gouty group after 2 months by about 0.31 mg/dl. On the other hand, hyperuricemic group showed significant (P ≤0.05) decrease in UA (-0.78 mg/dl) after 2 months duration. In conclusion, supplementation with 500 mg/day vitamin C for 2 months significantly attenuated serum UA for hyperuricemic patients and insignificantly affected serum UA in gouty patients. The uselessness of vitamin C supplements on gouty patients could be associated to a number of possible reasons.
ARTICLE | doi:10.20944/preprints201803.0181.v1
Subject: Engineering, Other Keywords: stormwater; biofilter; de-icing chemicals; nutrients; filtration performance
Online: 20 March 2018 (16:28:04 CET)
Biofilter application for treatment of stormwater containing de-icing chemicals commonly applied in airports, propylene glycol and potassium formate, was investigated. Lab-scale adsorption tests using filter media made of crushed clay (Filtralite) and granular activated carbon showed that adsorption was unsuitable for removal of propylene glycol and potassium formate. Column filtration experiment testing two different crushed clay size ranges was conducted. The results showed that DOC removal was dependent on a number of factors. This study investigated the impact of filter depth, nutrients addition, and filtration rate. DOC removal suggested that DOC degradation occurred on the top filter layer. It was shown that the most active separation occurred in the first ~20 cm of filter depth. This was confirmed by results from water quality analysis (i.e. DOC removal and ATP measurement) and calculations based on a filtration performance analysis (Iwasaki model) and filter hydraulic evaluation (Lindquist diagram). It was shown that for the highest C:N:P ratio tested (molar ratio of 24:7:1), 50-60% DOC removal was achieved. Addition of nutrients was found important and determining the biofilter performance.
ARTICLE | doi:10.20944/preprints202003.0130.v1
Subject: Materials Science, Biomaterials Keywords: liposomes; polymersomes; filtration; freeze-thaw; membrane mechanics; encapsulation stability
Online: 8 March 2020 (04:23:34 CET)
Sterilisation and preservation of vesicle formulations are an important consideration for their viable manufacture for industry applications, particular those intended for medicinal use. Here we undertake an initial investigation of the stability of hybrid lipid – block copolymer vesicles to common sterilisation and preservation processes, with particular interest in how the block copolymer component might tune vesicle stability. We investigate two sizes of polybutadiene-block-poly(ethylene oxide) polymers (PBd12-PEO11 and PBd22-PEO14) mixed with the phospholipid POPC considering the encapsulation stability of a fluorescent cargo and the colloidal stability of vesicle size distributions. We find that autoclaving and lyophilisation cause complete loss of encapsulation stability under the conditions studied here. Filtering through 200 nm pores appears to be viable for sterilisation for all vesicle compositions with comparatively low release of encapsulated cargo, even for vesicle size distributions which extend beyond the 200 nm filter pore size. Freeze-thaw of vesicles also shows promise for preservation of hybrid vesicles with high block copolymer content. We discuss the process stability of hybrid vesicles in terms of the complex mechanical interplay between bending resistance, stretching elasticity and lysis strain of these membranes and propose strategies for future work to further enhance the process stability of these vesicle formulations.
ARTICLE | doi:10.20944/preprints201810.0475.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Pb; turbidity; pH; rain water; filtration; absorbtion; public health
Online: 22 October 2018 (06:06:19 CEST)
Pb found in rain water is not only caused by tin roof on houses but also caused by the pollution of industrial activities, vehicles and land clearing activity by fire. Pb pollutant dissolves and enters into rain water storages and it’s consumed as drinking. Pb can cause bad impact to human, for example disruption of enzyme, anemia and low intelligence. The purposes of this research are (1) to evaluate Pb, pH and turbidity level in rain water, (2) to analyze the effectiveness of mollusk sand filtration and the absorption of activity carbon to decrease Pb, turbidity and pH, and (3) to analyze the correlation of Pb, length of stay and smoking habit on public health. This research is an experimental by using pre and post test designs with control and observational by using cross sectional design. The research was conducted in urban and rural areas of Pontianak and Kubu Raya regency. The sampling was done in determining the number of samples of Pb, pH and turbidity in rain water. The analyzing the data by using computer program. The results show that: (1) the average of Pb, pH and turbidity level before treatment is considered high at 131.7 µg/L on Pb, turbidity at 20 NTU and low pH at 5.2. After the treatment was the Pb has decreased to 0.71 µg/L and turbidity has to 5.66 NTU, pH to 6.9 and (2) Rain water treatment is very effective to decrease Pb for 99.4% and turbidity for 72%, and (3) there is a correlation among Pb found in rain water, length of stay and smoking activity to public health. Recommends that: the residents of Pontianak and Kubu Raya to process rain water before consuming. The rain water treatment can be done by applying mollusk sand filtration and absorption of active carbon.
ARTICLE | doi:10.20944/preprints201803.0223.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: animal protein; plant protein; elderly; obesity; glomerular filtration rate
Online: 27 March 2018 (11:23:20 CEST)
Controversy exists on whether animal and plant proteins influence obesity differently. The purpose of this study was to evaluate the association between total, animal, and plant protein intake with the obesity index and renal function in Korean adults. Study participants included Korean adults aged 60 years or older from the Korean National Health and Nutrition Examination Survey in 2013-2014. Height, weight, and waist circumference (WC) were measured and the body mass index (BMI) was calculated. One-day 24-hour recall data were used to estimate the daily total, animal, and plant protein intake. Glomerular filtration rate (GFR) was calculated by using the Modification of Diet in Renal Disease (MDRD) equation. General linear modellings were used to assess the relationships between protein intake, BMI and WC. The mean age was 69.2 ± 0.2 years, 44.2% were male. The total daily protein intake was 1.1 ± 0.02 g/kg/d and 0.9 ± 0.02 g/kg/d for males and females, respectively. Only one third of protein intake was from animal sources. In males, BMI (p < 0.001, p = 0.016, p < 0.001 respectively) and WC (p < 0.001, p = 0.010, p < 0.001, respectively) decreased as daily intake of plant protein (g/kg/d), animal protein (g/kg/d) and total protein (g/kg/d) increased. Similar associations were shown in Korean female. GFR was not associated with protein intake regardless of protein source in both sexes. In Korean adults aged 60 years or older, the protein intake was associated with a favorable obesity index without decrease in renal function. The effect was similar in both male and females, with both animal and plant proteins.
ARTICLE | doi:10.20944/preprints201611.0124.v1
Subject: Biology, Ecology Keywords: electivity; feeding behavior; filtration rate; Great Barrier Reef; phytoplankton
Online: 24 November 2016 (11:27:13 CET)
Outbreaks of the crown-of-thorns seastar (CoTS) represent a major cause of coral loss on the Great Barrier Reef. Outbreaks might be explained by enhanced larval survival supported by higher phytoplankton availability after flood events, yet little is known about CoTS larvae feeding behaviour, in particular their potential for selective feeding. Here, single- and mixed-species feeding experiments were conducted on CoTS bipinnaria larvae using five algae (Phaeodactylum tricornutum, Pavlova lutheri, Tisochrysis lutea , Dunaliella sp. and Chaetoceros sp.) and two algal concentrations (1000 and 2500 algae mL-1). Cell counts using flow-cytometry at the beginning and end of each incubation experiment allowed us to calculate the filtration and ingestion rates of each species by CoTS larvae. In line with previous studies, CoTS larvae ingested more algae when initial algal concentration was higher. We found evidence for the selective ingestion of some species (Chaetoceros sp., Dunaliella sp.) over others (P. lutheri, P. tricornutum). The preferred algal species had the highest energy content, suggesting that CoTS selectively ingested the most energetic algae. Ultimately, combining these results with spatio-temporal patterns in phytoplankton communities will help elucidate the role of larval feeding behaviour in determining the frequency and magnitude of CoTS outbreaks.
ARTICLE | doi:10.20944/preprints202010.0574.v1
Subject: Medicine & Pharmacology, Allergology Keywords: SARS-CoV-2; COVID-19; face masks; filtration efficiency; Tanzania
Online: 28 October 2020 (09:43:55 CET)
Increased demand for wearing face masks, lack of surgical masks and N95 respirators during the coronavirus pandemic created alternative needs for cloth masks. Therefore, to determine filtration efficacy, reusability and duration of wearing new and hand washed cloth masks, the bacteria filtration efficacy was tested using Staphylococcus aureus and Escherichia coli. Cotton cloth masks; single layer without pleats and with pleats, double layer with canvas filter in the middle, double layer with stiff filter in the middle, double layer with pleats on both sides and locally made and imported surgical masks and N95 respirators were used. Bacterial suspension was sprayed over outer surface and swabbed from inner surface at 0hrs, 4thhr, 8thhr and 12thhr. Similar procedure was performed to hand washed and ironed cotton cloth masks. After 24 hours of incubation, single layer without pleats and with pleats had no filtration efficacy(0-100%). Double layer with stiff filter in the middle and double layer with pleats on both sides had higher filtration efficacy(99.96-100%), this filtration efficacy remained up to three occasions of hand washing with soap and water, conferring protection up to 12hours. Filtration efficacy of surgical masks made locally, imported and N95 respirators were 90-100%, 99.99-100%, and 99.99-100% respectively.
Subject: Engineering, Mechanical Engineering Keywords: COVID-19; additive manufacturing; N95; respirator; particle transmission; filtration efficiency
Online: 7 June 2020 (10:33:30 CEST)
The COVID-19 pandemic has disrupted the supply chain for personal protective equipment (PPE) for medical professionals, including N95-type respiratory protective masks. To address this shortage, many have looked to the agility and accessibility of additive manufacturing (AM) systems to provide a democratized, decentralized solution to producing respirators with equivalent protection for last-resort measures. However, there are concerns about the viability and safety in deploying this localized download, print, and wear strategy. Several polymer-based AM processes produce porous parts, and inherent process variation between printers and materials also threaten the integrity of tolerances and seals within the printed respirator assembly. The goal of this paper is to quantitatively measure particle transmission through printed respirators of different designs, materials, and AM processes, and assess the viability of printed respirators as N95 equivalents. Results from this study show that respirators printed using desktop/industrial-scale fused filament fabrication processes and industrial-scale powder bed fusion processes have insufficient filtration efficiency at the size of the SARS-CoV-2 virus, even while assuming a perfect seal between the respirator and the user’s face. Almost all printed respirators provided <60% filtration efficiency at the 100-300 nm particle range. Only one respirator, printed on an industrial-scale fused filament fabrication system provided >90% efficiency as-printed. Post-processing procedures including cleaning, sealing surfaces, and reinforcing the filter cap seal generally improved performance, but no respirator sustained the filtration efficiency of an N95 respirator, which filters 95% of SARS-CoV-2 virus particles. Instead, the printed respirators showed similar performance to various cloth masks. While continued optimization of printing process parameters and design tolerances could be implemented to directly print respirators that provide the requisite 95% filtration efficiency, AM processes are not sufficiently reliable for widespread distribution and local production of N95-type respiratory protection without commensurate quality assurance processes in place. Certain design/printer/material combinations may provide sufficient protection for specific users, but the respirators should not be trusted without quantitative filtration efficiency testing. It is currently not advised to expect printed respirators originating from distributed designs to replicate performance across different printers and materials.
TECHNICAL NOTE | doi:10.20944/preprints202104.0023.v1
Subject: Engineering, Automotive Engineering Keywords: air filtration; air purifier; COVID-19; haze; HEPA filter; particulate matter
Online: 1 April 2021 (13:43:51 CEST)
Purpose: This study aimed to focus on the design and development of low-cost DIY air purifiers, using a ventilating fan, air pump, water pump, and an ultrasonic generator, with regard to filtration efficacy and also cost-effectiveness that can be used during the COVID-19 pandemic and haze pollution. Methods: Six types of household air purifiers, incorporating a HEPA filter, a HEPA filter & electrostatic fiber, an air pump, an air pump & ultrasonic wave, a water pump, and a water pump & ultrasonic wave, were fabricated. The amount of particulate matter (PM) and CO2 levels were recorded at 0, 10, 20, 30, and 60 min, then, repeated 3 times. After 10 min of the 3rd experiment of each study, the last measurement of air pollution would be recorded. Results: At 60 min, the HEPA filter & electrostatic fiber showed the best performance regarding reduction of PM and CO2 levels. The highest PM reduction rate had occurred at 30 min using an air pump procedure (99.330 to 100%). The CO2 levels of all experiments had fluctuated at different times. After 10 min of a closed machine, HEPA filter & electrostatic fiber revealed the highest rate of PM elevation, while PM levels of all water-based purifier systems were decreased. A water pump and air pump were the cheapest air cleaners, when taking into account maintenance expenses and electricity charges. Conclusion: An air pump is the optimum method for reducing particulate matter at minimum cost but without the benefit of reduced humidity, while the HEPA filter & electrostatic fiber is the best system to decrease PM levels, but this requires an enclosed structure at the inlet to prevent dust coming back into the room. As filtration efficiency is increased by the use of filters & electrostatic fiber mechanisms, the more expensive the system becomes.
ARTICLE | doi:10.20944/preprints201810.0609.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: positioning; ultra-wide band; filtration; Kalman filter; smart city; industry 4.0
Online: 25 October 2018 (14:04:47 CEST)
As a part of the proposed article, the authors presented comprehensive data analysis for movement data that comes from a positioning system based on ultra-wide band (UWB) technology. For purpose of this article, a test was carried out during which the car equipped with cruise control overcame the given path at a speed from 10 km/h to 60 km/h. The obtained motion models (information about position) have been filtered through a series of filters - from fundamentals filters with a variable window (median, moving average, Savitzky-Golay filter), through more complex ones like the Wiener or Kalman filter. As a result, the authors proposed a form of data analysis and filtration depending on the speed of the moving object. In addition, the maximum accuracy that can be obtained for a given traffic model was also determined. The whole research proves that it is possible to use a system based on UWB technology in positioning objects for urban applications - smart city, in industry 4.0 applications as well as for positioning autonomous vehicles in urban applications, such as well as on highways to maintain cohesion of convoys vehicles.
ARTICLE | doi:10.20944/preprints202211.0464.v1
Subject: Life Sciences, Molecular Biology Keywords: NHE3; glomerular filtration rate; bicuculline; PVN of the hypothalamus; sympathetic nerve activity.
Online: 25 November 2022 (02:49:16 CET)
This study aimed to verify the effects of an acute increase in blood pressure (BP) and/or renal sympathetic nerve activity (rSNA) on the renal excretion of sodium and water and its potential effect on the regulation of NHE3 activity. Uninephectomized anesthetized male Wistar rats were divided into three experimental groups: 1) Sham, the rats had their BP and rSNA recorded, and urine was collected for 2 h; 2) bicuculline (Bic) paraventricular nucleus of the hypothalamus (PVN), rat BP, and rSNA were recorded, and urine was collected for 1 h at baseline conditions and 1 h after bicuculline injection into the PVN; 3) RNS + Bicuculine injection into the PVN, BP, and rSNA were recorded, and urine was collected 1h after RNS and 1 h after bicuculline injection into the PVN. Renal nerve stimulation (RNS) decreased sodium and water excretion independent of changes in BP. However, after Bic in the PVN during RNS stimulation, BP and rSNA increased up to 30% and 60%, respectively, increasing diuresis (5-fold) and natriuresis (2.3-fold), accompanied by a significant reduction in the NHE3 activity independent of GFR changes. In conclusion, an acute increase in BP overcomes such effects, generating diuresis, natriuresis, and NHE3 activity inhibition.
ARTICLE | doi:10.20944/preprints202207.0359.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Drinking water; rapid sand filtration; Recreational areas; Exposure; Microcystis and Dolichospermum; Microcystins
Online: 25 July 2022 (08:16:59 CEST)
Africa’s water needs are often supported by eutrophic waterbodies dominated by cyanobacteria posing health threats to riparian populations from cyanotoxins, and Lake Victoria is no exception. In two embayments of the lake (Murchison Bay and Napoleon Gulf), cyanobacterial surveys were conducted to characterize the dynamics of cyanotoxins in lake water and water treatment plants. Forty-six cyanobacterial taxa were recorded and out of these 14 were considered potentially toxigenic (i.e., from the genera Dolichospermum, Microcystis, Oscillatoria, Pseudanabaena and Raphidiopsis). A higher concentration (ranging from 5-10 µg MC-LR equiv. L-1) of microcystins (MCs) was detected in Murchison Bay compared to Napoleon Gulf, with a declining gradient from the inshore (max. 15 µg MC-LR equiv. L-1) to the open lake. In Murchison Bay, an increase either in Microcystis sp. biovolume and MC was observed over the last two decades. Despite high cell densities of toxigenic Microcystis and high MC concentrations, the water treatment plant in Murchison Bay efficiently removed the cyanobacterial biomass, intracellular and dissolved MC to below the lifetime guideline value for exposure via drinking water (< 1.0 µg MC-LR equiv. L-1). Thus, the potential health threats stem from the consumption of untreated water and recreational activities, along the shores of the lake embayments. MC concentrations were predicted from Microcystis cell numbers regulated by environmental factors such as solar radiation, wind speed in the N-S direction and turbidity. Thus, an early warning through microscopical counting of Microcystis cell numbers is proposed to better manage health risks from toxigenic cyanobacteria in Lake Victoria.
ARTICLE | doi:10.20944/preprints202001.0213.v1
Subject: Medicine & Pharmacology, Pediatrics Keywords: glomerular filtration rate; Brenner hypothesis; extreme low birth weight infants; renal outcome
Online: 19 January 2020 (05:12:19 CET)
Different cohort studies documented a lower glomerular filtration rate (GFR) in former extremely low birth weight (ELBW, <1000 g) neonates throughout childhood when compared to term controls. The current aim is to pool these studies to describe the GFR pattern over the pediatric age range. To do so, we conducted a systematic review on studies reporting on GFR measurements in former ELBW cases while GFR data of healthy age-matched controls included in these studies were co-collected. Based on 248 hits, 6 case-control and 3 cohort studies were identified, with 444 GFR measurements in 380 former ELBW cases (median age 5.3-20.7 years). The majority were small (17-78 cases) single center studies, with heterogeneity in GFR measurement (inulin, Cystatin C or creatinine estimated GFR formulae) tools. Despite this, the median GFR (ml/kg/1.73m2) within case-control studies was consistently lower (-13, range -8 to -25%) in cases, so that a relevant minority (15-30%) has a eGFR<90 mgl/kg/1.73m2). Consequently, this pooled analysis describes a consistent pattern of reduced eGFR in former ELBW cases throughout childhood. Research should focus on perinatal risk factors for impaired GFR and long-term outcome, but is hampered by single center cohorts, study size, and heterogeneity of GFR assessment tools.
ARTICLE | doi:10.20944/preprints201909.0175.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: water purification; developing countries; SDG-6; microbiological contamination; public health; membrane filtration
Online: 16 September 2019 (17:23:23 CEST)
Introduction: In rural communities in regions with limited resources the provision of clean water remains challenging. Fecal contamination of water is very common and results in a high incidence of diarrhea, subsequent acute kidney injury and mortality particularly in the very young and old. Membrane filtration is a practical solution to this problem and recent innovation allows membrane filtration using recycled hemodialyzers. We, Easy Water for Everyone, have quantified the systematic effect on health outcomes. Material and Methods: Between 02/2018 and 12/2018, 4 communities in rural Ghana (in the Greater-Accra region) were each provided with a high-volume membrane filtration devices (NUF 500; NuFiltration using recycled hemodialyzers). Health data from montly household surveys and chart review in local healthcare facilities were collected with approval from Ghana Health Services. Specifically, data was collected on gastrointestinal disease, acute kidney injury and therapeutic interventions. Incidence rates for a five-months period before and after implementation of the device were calculated and compared to rates during the same months from 4 neighboring communities that were not yet provided with the device. Results: Acceptance of the devices and the purified water in the studied villages was good and self-reported data of 1130 villagers over 10 months from 9 studied communities in rural Ghana (11% younger than 5 years and 14 % older than 65 years) were included in this analysis. The overall monthly incidence rate of diarrhea showed a decline following the implementation of the device in the 4 study villages from a mean of 0.18 to 0.05 cases per person-month for a reduction in rates by 72% (rate ratio = 0.27). By contrast, the control group of 4 villages in the same region showed no decline in mean rates during the same months as the study period with mean rates changing not significantly from 0.11 to 0.08 cases per person-month. Discussion: Provision of a hemodialyzer membrane filtration device markedly improves health outcomes as measured by diarrhea incidence within rural communities. While our data awaits confirmation in a larger population and further statistical analyses accounting for village characteristics, seasonality and subject demographics, the obvious decline in incidence rates supports widespread use of hemodialyzer membrane filtration devices, particularly in rural regions. Rollout of the device in further sites will likely increase our understanding in terms of risk and other preventive factors modifying the incidence of diarrhea and subsequent acute kidney injury.
ARTICLE | doi:10.20944/preprints201801.0180.v1
Subject: Biology, Ecology Keywords: current; filtration rate; freshwater bivalve; mussel size; response surface methodology; Sinanodonta woodiana
Online: 19 January 2018 (06:41:05 CET)
In this study, we applied a central composite design to estimate independent variables and establish optimal conditions of filtration rate and feces production that enhance filtration of suspended organic matter by the freshwater mussels Sinanodonta woodiana. The results indicated that statistical design methodology offers an efficient and feasible approach for high filtration and low feces production condition optimization. The proposed model equation takes into account the quantitative effect of variables and also the influence of interactions among variables on mussel filtration rate. Under the optimal experimental conditions (mussel size, 13.0 ± 0.2 cm; water current, 17.5 L/h), the experimental filtration rate of 4.47 ± 1.82 L/mussel/h showed a degree of correspondence with the predicted value of 8.4 L/mussel/h, which verified the practicability of this optimum strategy.
ARTICLE | doi:10.20944/preprints202110.0162.v1
Subject: Engineering, Civil Engineering Keywords: air pollution control; biosecurity; animal diseases; ultraviolet light; advanced oxidation; filtration; environmental technology
Online: 11 October 2021 (14:05:44 CEST)
This study evaluated the use of filtration and UV-A photocatalysis for the reduction of particulate matter (PM) and airborne bacterial pathogens in swine barns. Two MERV filters (8 and 15) were used to mitigate PM concentrations measured at the PM 1, PM 2.5, respirable PM, and PM 10 ranges. Filtration was also used to generate different levels of airborne pathogens to be treated by UV-A. Results show that MERV 8 and 15 filters effectively reduced PM concentrations (96-98%) in air exhausted from a swine barn (p ranged from < 0.01 to 0.04). UV-A photocatalysis did not mitigate PM concentrations. UV-A photocatalysis treatment reduced measured colony-forming units (CFUs) by 15-95%. The CFU percent reduction was higher when airborne PM concentration was low. The numeric results suggested a real mitigation effect despite p-values that did not meet the usual statistical cut-off of <0.05 for significance due to the large variability of the CFU control samples. Normalization of measured airborne pathogen concentrations by smaller PM size range concentrations led to emerging significant treatment differences for CFUs. A significant decrease (~60% reduction; p < 0.03) in the concentration of viable airborne bacteria was shown for all PM below the 10-micron range.
REVIEW | doi:10.20944/preprints202104.0574.v1
Subject: Chemistry, Analytical Chemistry Keywords: smart materials; drug delivery systems; flame retardant; industrial coatings; filtration membranes; antifouling coatings.
Online: 21 April 2021 (11:47:42 CEST)
Abstract: This review presents current literature on different nanocomposites coatings and surface finishing for different substrates (such as textiles, concrete, plastics, stones, metals and so on). In particular, this study is focused on smart materials, drug delivery systems, and industrial, antifouling and nano/ultrafiltration membrane coatings. Each of these nanostructured coatings shows interesting properties for different fields of application. In this review, particular attention is paid to the synthesis and the consequent physico-chemical characteristics of each coating and, therefore, to the different parameters that influence the substrate deposition process. Several techniques used in the characterization of these surface finishing coatings are also described. In this review, the sol-gel and polymerization method for preparing stimuli-responsive coatings as smart sensor materials is described; functional polymers and nanoparticles sensitive to pH, temperature, phase, light and biomolecules are also treated. Finally, nanomaterials based on phosphorus, borates, hydroxy carbonates and silicones are used and described as flame retardant coatings; organic/inorganic hybrid sol-gel coatings for industrial applications are illustrated, together with functional nanofiller (carbon nanotubes, metallic oxides, etc.) and polymers employed for nano/ultrafiltration membrane and antifouling coatings. In the last decades, several research institutes and industries have collaborated for the advancement of nanotechnology by optimizing conversion processes of conventional materials into coatings with new functionalities for intelligent, innovative, eco-sustainable and advanced applications.
ARTICLE | doi:10.20944/preprints201808.0057.v1
Subject: Earth Sciences, Environmental Sciences Keywords: groundwater; Haiti; filtration; water treatment; developing country; point of use treatment; household treatment
Online: 3 August 2018 (04:03:22 CEST)
Water resources, especially safe, potable water, are limited for many Haitians. In areas where shallow groundwater is available, many household water needs such as laundry, bathing, and cooking are supplied by hand-dug wells. In order to better understand the water quality and prevalence of these household wells, 35 hand-dug wells were surveyed and sampled near the Hôpital Albert Schweitzer (HAS) in Deschapelles, Haiti. Water samples were collected and tested for fecal coliform and E. coli using the IDEXX Colilert-18 method. Of the samples collected, 89 percent were determined unsafe to use as a drinking water source based on the World Health Organization standard of 1.0 colony-forming unit (cfu) Escherichia Coli (E. coli) per 100 mL. 66 percent of the wells exceeded recreational/body contact standards for the state of Michigan (130 cfu/100 mL). Some of these wells were deemed suitable for conversion to a new well type called In-Situ Filtration (ISF) wells. ISF wells are installed with an internal sand filter pack, PVC casing, pump, and cap which seals the well from surface contamination and provides additional water treatment as water is pumped. Previous ISF installations have reduced E. coli to safe drinking water levels within 90 days.
CONCEPT PAPER | doi:10.20944/preprints201612.0105.v5
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: csf; shunt; filtration; neurodegenerative; neuroimmunology; alzheimer; parkinson; guillain-barre; device; ventriculo-peritoneal shunt
Online: 30 January 2017 (14:22:03 CET)
Liquorpheresis (CSF filtration) comprises a therapeutical approach that has been proposed to treat several neurological conditions where antibodies, inflammatory mediators or abnormal peptides are the cause or play an important role in the pathogenesis of the disease. CSF replacement may be an alternative approach not explored so far. Here, we review previous experiences in the use of liquorpheresis in autoimmune and degenerative neurological diseases. Then we describe previous developments and provide some new technical innovations in order to design bidirectional CSF shunting systems. These systems can be complemented either with a deposit of artificial CSF or with a CSF filter, allowing CSF replacement or liquorpheresis respectively. Both options would lead to mechanical dilution of the patient’s CSF.
REVIEW | doi:10.20944/preprints202102.0344.v1
Subject: Social Sciences, Accounting Keywords: water supply; crisis situation; safety of water supply; flood; water decontamination; water filtration; flexible tanks
Online: 17 February 2021 (07:56:01 CET)
Various methods of water purification, the aim of which is to obtain such a purity class that makes it suitable for consumption are presented in the article. It is a review of solutions, ranging from methods known and used for over 100 years, through research and experiments underway, to those that are only a concept. Some of the solutions are so effective that they should also be combined with the possibility of safe storage of purified water. Flexible tanks are used for this, which significantly improve logistics and provide a supply of water in all places where it is needed.
ARTICLE | doi:10.20944/preprints201810.0729.v1
Subject: Materials Science, Nanotechnology Keywords: silver nanoparticles; laser ablation in liquids; laser synthesis of colloidal nanoparticle solution, nanoparticle impregnated paper; antimicrobial activity; fiber fines; sheet forming; vacuum filtration
Online: 30 October 2018 (16:14:31 CET)
A paper impregnated with silver nanoparticles (AgNPs) has been prepared. For the preparation of the substrates, aqueous suspensions of pulp fines, a side product from the paper production, have been mixed with Ag nanoparticles (AgNP) suspensions. The nanoparticle synthesis thereof was carried out via laser ablation of pure Ag in water. After the sheet formation process, the leaching of the AgNPs was determined to be low while the sheets exhibited antimicrobial activity towards E. Coli.
CASE REPORT | doi:10.20944/preprints201801.0227.v1
Subject: Life Sciences, Other Keywords: Lactate dehydrogenase (LDH), Computed Tomography (CT), Glomerular filtration rate (GFR), C reactive protein (CRP), Angiotensin converting enzyme inhibitor (ACEI) Angiotensin receptor blocker (ARB), Kidney Urinary bladder ( KUB), Dimercapto Succinic Acid (DMSA)
Online: 24 January 2018 (11:41:15 CET)
Renal artery thrombosis is a sporadic serious clinical condition which potentially cause renal infarction. Diagnosis of renal infarction can be delayed or missed due to non specific clinical presentation and overlapping appearance of medical and surgical phenomena. Early diagnosis supported by biochemical and radiological findings while appropriate management potentially improve morbidity and mortality. Persistent abdominal or flank pain with raised LDH and proteinuria on background of thromboembolism risk factors supports the diagnosis. Despite the rarity of the disease rapid identification with prompt medical or endovascular intervention could prevent irreversible renal parenchymal damage.