Filtration Apparatus Research Articles

加圧ろ過による水系炭化ケイ素サスペンションの成形

The applied pressure and suspension height during consolidation of an aqueous suspension with 800 or 30 nm SiC particles were continuously recorded using a developed pressure filtration apparatus. The suspension of 5-30 vol% solid was filtered through three sheets of a 0.1 μm pore diameter membrane filter attached to the bottom of the piston displaced at 0.05-0.5 mm/min. The dehydrated solution flowed into the pore channels in the piston in the Teflon cylinder. The final packing density of 800 nm particles reached 55-62%, depending on the surface charge of particles. On the other hand, the final packing density (41% density) of 30 nm SiC particles was not influenced by the surface charge, and was lower than that of 800 nm SiC particles. The consolidation energy for 1 cm3 SiC was 1.1-5.5 J/cm3 for 800 nm SiC particles and 17.2 J/cm3 for 30 nm SiC particles. Decrease of the pore size of the consolidated SiC compact increased the consolidation energy. The ratio of energy applied between two particles during consolidation to the interaction energy between two particles in a suspension was correlated to the packing density of the consolidated SiC cake.

Evaluation of a new device against bacterial penetration

Objective: This study analyzed how effectively bacteria penetrate through a new filtering device (Muski™) aimed at providing temporary protection against hazardous air contaminants. Materials and methods: A 1.5–7×108 cfu/ml bacterial or spore suspension was aerosolized. Fragments of the Muski filter, previously sterilized by gamma rays, were placed in a sterile stainless steel Seitz filter holder, plugged into an Erlenmeyer vacuum flask connected to a vacuum pump to force the bacteria aerosol through the Muski filter. As a control the same apparatus was used without the Muski filter. To evaluate the bacteria passing through the apparatus, diluent solution was introduced in the Erlenmeyer flask, which was then subjected to mechanical shaking. Both the contents of Erlenmeyer flask and the diluent solution, used to rinse out the Erlenmeyer flask, were filtered through a membrane filtration apparatus. The filtration membrane was transferred to the surface of a Petri dish containing a suitable culture medium f...

Filtration methods for recovery of Bacillus anthracis spores spiked into source and finished water

Spores of Bacillus anthracis Sterne strain were recovered from 100 ml and 1 L volumes of tap and source waters using filtration through a 0.45 um filter, followed by overnight culture on agar plates. In a set of experiments comparing sheep red blood cell (SRBC) plates with a chromogenic agar formulation designed by R & F Laboratories, with a spiking dose of 47 plate-enumerated spores in 100 ml tap water, the mean spore recoveries were 34.0 and 30.8 spores, respectively. When a spiking dose of 100 fluorescence activated cell sorter(FACS)-enumerated spores was used in 100 ml potable water, the average recovery with SRBC plates was 48 spores. Detection efforts with spiking doses of 35 and 10 spores in 1 L tap water were successful, but recovery efforts from spiked 1 L volumes of source water were problematic due to the concomitant growth of normal spore-forming flora. Recoveries were also attempted on 10 L volumes of tap water. For a spiking dose of 100 spores, mean recovery from six replicates was 11 spores (±6.8, range 2–20), and for a spiking dose of 10 spores, mean recovery from six replicates was 2.3 spores (±3.5, range 0–9). Efforts were also made to “direct detect” spores via polymerase chain reaction (PCR) on washes from filters. When spiking 534 spores in 100 ml, 9/9 replicates of spiked tap water, 6/6 source water replicates, and 0/3 unspiked controls were positive by lef PCR. When 534 spores were spiked into 1 L tap water, the lef PCR was unsuccessful; however, using the nested vrrA PCR resulted in 4/9 spiked samples, and 0/3 unspiked controls, testing positive. Our results indicate that an inexpensive and user-friendly method, utilizing filtration apparatus commonly present in many water quality testing labs, can readily be adapted for use in detecting this potential threat agent.

PPARα activation upregulates nephrin expression in human embryonic kidney epithelial cells and podocytes by a dual mechanism

Nephrin is an important member of the glomerular ultrafiltration complex and changes in its expression are associated with severe proteinuria. In this study, we show that synthetic PPARα agonists, but not PPARγ agonists, stimulate an increased nephrin mRNA and protein expression in cultures of human podocytes and A293 human embryonic kidney epithelial cells which are blocked by the PPARα antagonist RU486. Furthermore, the PPARα agonists have an additive effect on the interleukin-1β (IL-1β)-induced nephrin upregulation. Luciferase-reporter assays reveal that human nephrin promoter activity is stimulated by the PPARα agonists. Neither IL-1β nor TNFα alone has an effect on nephrin promoter activity suggesting that additional posttranscriptional regulatory events might be operative. The role of nephrin mRNA stability regulation was evaluated in cells treated with actinomycin D to stop further RNA transcription. In the presence of PPARα agonists, IL-1β or TNFα, the decay of nephrin mRNA was drastically reduced thus arguing for an additional posttranscriptional mode of action. In summary, these data show that PPARα activation causes an increased nephrin expression by a dual action, on the one hand by stimulating nephrin promoter activity and on the other hand by reducing nephrin mRNA degradation. These findings may have importance for treatment strategies of renal diseases affecting the expression of nephrin and subsequently the proper action of the glomerular filtration apparatus.

Solution-Phase Parallel Synthesis of a 1,2,7-Trialkyl-1H-imidazo[4,5-g]quinoxalin-6-ol Library Scaffold

This paper describes solution-phase parallel synthesis of a library with a novel 1,2,7-trialky-1H-imidazo[4,5-g]quinoxalin-6-ol scaffold and three points of diversity. The library is prepared using 1,5-difluoro-2,4-dinitrobenzene as the starting material and commercially available chemicals as the building blocks. A new, inexpensive, and practical apparatus for parallel filtration is also described.

Organization of the pronephric filtration apparatus in zebrafish requires Nephrin, Podocin and the FERM domain protein Mosaic eyes

Podocytes are specialized cells of the kidney that form the blood filtration barrier in the kidney glomerulus. The barrier function of podocytes depends upon the development of specialized cell–cell adhesion complexes called slit-diaphragms that form between podocyte foot processes surrounding glomerular blood vessels. Failure of the slit-diaphragm to form results in leakage of high molecular weight proteins into the blood filtrate and urine, a condition called proteinuria. In this work, we test whether the zebrafish pronephros can be used as an assay system for the development of glomerular function with the goal of identifying novel components of the slit-diaphragm. We first characterized the function of the zebrafish homolog of Nephrin, the disease gene associated with the congenital nephritic syndrome of the Finnish type, and Podocin, the gene mutated in autosomal recessive steroid-resistant nephrotic syndrome. Zebrafish nephrin and podocin were specifically expressed in pronephric podocytes and required for the development of pronephric podocyte cell structure. Ultrastructurally, disruption of nephrin or podocin expression resulted in a loss of slit-diaphragms at 72 and 96 h post-fertilization and failure to form normal podocyte foot processes. We also find that expression of the band 4.1/FERM domain gene mosaic eyes in podocytes is required for proper formation of slit-diaphragm cell–cell junctions. A functional assay of glomerular filtration barrier revealed that absence of normal nephrin, podocin or mosaic eyes expression results in loss of glomerular filtration discrimination and aberrant passage of high molecular weight substances into the glomerular filtrate.

Differential Expression of Cannabinoid Receptors in the Human Colon: Cannabinoids Promote Epithelial Wound Healing

Differential Expression of Cannabinoid Receptors in the Human Colon: Cannabinoids Promote Epithelial Wound Healing

Filtration characterisation for assessing MBR performance: three cases compared

Understanding of membrane fouling processes in membrane bioreactors (MBR) treating municipal wastewater is essential for proper design and operation of full-scale MBR wastewater treatment plants. One of the tools in investigating this subject must be a well-defined measuring protocol to quantify the filterability of activated sludge. Such a method was developed and a filtration apparatus was built by Delft University of Technology [1]. This article describes the results of applying the mentioned filtration characterisation method at three MBR pilot locations in the Netherlands. The measurements were sustained by EPS analyses in the water phase of the respective activated sludge broths. Each MBR installation produces an activated sludge with a specific filterability, which can be quantified by the proposed measuring protocol quite well. Activated sludge from each installation could be filtered under subcritical conditions, i.e. without filtration resistance increase for at least thirty minutes of filtration. Photometric EPS analyses of the water phase and obtained permeate seem to be too weak to explain the differences in filtration behaviour.

Fr�hdiagnostik von chronischen Nierenerkrankungen

Chronic kidney diseases frequently progress to end-stage renal failure over a period of several years. Ultimately, the glomerular filtration apparatus and tubulus are destroyed to such an extent that renal replacement therapy is required. This process may last longer than 10 years. To avoid loss of renal function, chronic kidney diseases should be diagnosed as early as possible so that therapeutic measures are initiated in time. Medications which prevent or delay progression to end-stage renal failure, e.g. ACE inhibitors and AT(1) blockers, are more effective if started early in the course of renal disease. A significant number of patients with chronic kidney disease are still diagnosed too late and are without adequate therapy so that chances for prevention and/or delay of chronic kidney disease are missed.

The Nociceptin Pharmacophore Site for Opioid Receptor Binding Derived from the NMR Structure and Bioactivity Relationships

Nociceptin, a 17 amino acid opioid-like peptide that has an inhibitory effect on synaptic transmission in the nervous system, is involved in learning, memory, attention, and emotion and is also implicated in the perception of pain and visual, auditory, and olfactory functions. In this study, we investigated the NMR solution structure of nociceptin in membrane-like environments (trifluoroethanol and SDS micelles) and found it to have a relatively stable helix conformation from residues 4-17 with functionally important N-terminal residues being folded aperidoically on top of the helix. In functional assays for receptor binding and calcium flux, alanine-scanning variants of nociceptin indicated that functionally important residues generally followed helix periodicity, consistent with the NMR structural model. Structure-activity relationships allowed identification of pharmacophore sites that were used in small molecule data base searches, affording hits with demonstrated nociceptin receptor binding affinities.

Anti-Vascular Endothelial Growth Factor Receptor-2 Antibody Accelerates Renal Disease in the NZB/W F1 Murine Systemic Lupus Erythematosus Model

Anti-Vascular Endothelial Growth Factor Receptor-2 Antibody Accelerates Renal Disease in the NZB/W F1 Murine Systemic Lupus Erythematosus Model

Effects of six in-office agents of desensitization on the permeability of dentin - An in-vitro hydraulic conductance study

The objective of this in-vitro study was to evaluate the effects of six in-office agents of desensitization on the hydraulic conductance of human dentin by measuring the mean percentage reduction in permeability over a period of one month. The tested agents were Fluoride varnish (Fluorprotector),resin desensitizer ( Gluma desensitizer ), adhesive resin ( Gluma comfort bond ), laser (Nd: YAG Laser), fluoride iontophoresis (Electric pulp tester, for fluoride iontophoresis) and 3% Potassium oxalate(freshly prepared). Sixty non carious, intact human mandibular third molars were sectioned at mid coronal region and polished to obtain a 1mm thick disc which were divided into six groups. A split chamber device with fluid filtration apparatus was constructed for hydraulic conductance measurements. Permeability of dentin discs was measured at baseline that serves as a control and following the application of the various in-office agents, measurements was recorded post operatively, after 24 hrs, after I week and after 1 month. Mean percentage reduction in permeability was tabulated and statistically analyzed. The results of this study indicate that all the tested agents led to a decrease in dentin permeability Nd: YAG laser gave the highest reduction in permeability throughout the entire period of study followed by Gluma desensitizer Gluma comfort bond, Fluoride iontophoresis, and Fluor protector and 3% Potassium oxalate was the least effective.

Packing density and consolidation energy of flocculated aqueous SiC suspension

The applied pressure and suspension height during consolidation were continuously recorded with an aqueous 30 vol.% suspension of 0.8 μm SiC particles at pH 3.0 (near the isoelectric point) using a developed pressure filtration apparatus. The consolidation to the solid content above 46 vol.% was accompanied by a rapid increase of the pressure. The maximum packing density, where an average distance between two SiC particles was close to 0, reached 62–63% at 19 MPa of applied pressure. The consolidation energy was 1.6–1.8 J/g-SiC. The influence of the addition of polyacrylic acid (dispersant) on the consolidation energy of the SiC suspension and the strain relaxation of the consolidated SiC compact after the pressure release, are also reported.

Utilização de reagentes auxiliares na filtragem

Esse trabalho teve como objetivo estudar o efeito de auxiliares químicos de filtragem na formação e desaguamento de tortas de produtos de finos de minérios de ferro. Foram utilizados um floculante fracamente aniônico e dois surfatantes aniônicos. Empregou-se uma montagem de laboratório que inclui uma balança interligada a um microcomputador. A tensão superficial foi medida por meio de tensiômetro, usando o método da lâmina. A adição do floculante reduziu significativamente o tempo de formação da torta, aspecto da maior relevância para a operação industrial, porém causou ligeiro aumento na umidade final da torta. A adição de surfatantes propiciou um abaixamento na tensão superficial do filtrado, entretanto não levou ao esperado abaixamento significativo da umidade final da torta.

Crystallisation of a multiparaffinic wax in normal tetradecane under high pressure

The Wax appearance temperature as well as the amount and composition of wax precipitation were determined as a function of pressure in a synthetic complex system tetracosane + (multiparaffinic commercial wax). Measurements were performed by using two different experimental techniques: - A high pressure microscopy apparatus for the solid–liquid phase boundary measurement. - A filtration apparatus coupled to a chromatographic analysis of the partially frozen mixtures for the determination of the solid phase behaviour. Experimental results were compared with the values calculated by a predictive model. The influence of pressure on wax formation is shown to be as important as the influence of temperature and the model used can provide an excellent description of the melting behaviour over a wide pressure range.

Determination of System Losses of Geosmin and MIB in Bench-Scale Filtration Apparatus

Abstract Geosmin and 2-methylisoborneol (MIB) are two of the causative compounds responsible for the earthy/musty odour problem in drinking water. They are a major concern for the water treatment industry because they are difficult to remove by conventional water treatment practices and are fairly resistant to chemical oxidation. Various studies have been conducted at both bench and full scale to examine the removal of these compounds by adsorption and/or biological filtration. Lack of study at realistic odour compound concentrations and disregard for losses of these compounds by other means (i.e., volatilization or adsorption) represent some of the limitations of such studies. The bench-scale investigation reported herein focussed on system design and minimization of system losses. The results indicated that the preferred system design included the use of Teflon feed bottles, Teflon tubing, and a glass filter column in which the influent feed line descended close to the media surface. Such a design minimized system losses of both geosmin and MIB to 42 and 30%, respectively, based on target influent concentrations of 200 ng/L.

A rapid filtration apparatus for harvesting cells under controlled conditions for use in genome-wide temporal profiling studies

Gene expression can respond rapidly to changes in environmental conditions. To effectively monitor these responses, we built a filtration apparatus that allows for the rapid harvesting and processing of moderate volumes of yeast cells under controlled atmospheric conditions (e.g., anaerobic conditions). Harvesting by filtration offers several advantages over that by centrifugation, especially when rapid, repeated sampling of dilute cultures is required. A number of different filter membranes, including cellulose acetate, mixed esters of cellulose, regenerated cellulose, polycarbonate, and polyvinylidene fluoride, were assayed for harvest efficiency and the quality of RNA obtained by hot-phenol extraction from cells directly adhering to the membranes. To determine the suitability of the RNA for microarray analyses, we quantified both cDNA yield from reverse transcription and the indirect coupling of Cyan dyes. In general, filtration times, cell yields, and RNA quality were similar among the filters examined, although some media components (e.g., antifoam) can cause fouling of smaller-pore-sized filters. Thus, choice of a membrane will depend on the particular medium, ease of filter handling, or on other experimental considerations. We routinely use this filtration apparatus with Osmonics 1.2 μm cellulose acetate filters for isolating RNA for genome-wide temporal profiling analyses.

Establishment of a new quantitative filtration apparatus to evaluate erythrocyte deformability

Establishment of a new quantitative filtration apparatus to evaluate erythrocyte deformability

Neutralization of Circulating Vascular Endothelial Growth Factor (VEGF) by Anti-VEGF Antibodies and Soluble VEGF Receptor 1 (sFlt-1) Induces Proteinuria

There are about 2.5 million glomeruli in the kidneys each consisting of a barrel of glomerular basement membrane surrounded by glomerular endothelial cells on the inside and glomerular epithelial cells with established foot processes (podocytes) on the outside. Defects in this filtration apparatus lead to glomerular vascular leak or proteinuria. The role of vascular endothelial growth factor (VEGF) in the regulation of glomerular vascular permeability is still unclear. Recent studies indicate that patients receiving anti-VEGF antibody therapy may have an increased incidence of proteinuria. In a different setting, pregnancies complicated by preeclampsia are associated with elevated soluble VEGF receptor 1 protein (sFlt-1), endothelial cell dysfunction and proteinuria. These studies suggest that neutralization of physiologic levels of VEGF, a key endothelial survival factor, may lead to proteinuria. In the present study, we evaluated the potential of anti-VEGF neutralizing antibodies and sFlt-1 in the induction of proteinuria. Our studies demonstrate that anti-VEGF antibodies and sFlt-1 cause rapid glomerular endothelial cell detachment and hypertrophy, in association with down-regulation of nephrin, a key epithelial protein in the glomerular filtration apparatus. These studies suggest that down-regulation or neutralization of circulating VEGF may play an important role in the induction of proteinuria in various kidney diseases, some forms of cancer therapy and also in women with preeclampsia.

Preparation of PVP immobilized microporous chlorinated polyvinyl chloride membranes on fabric and their hydraulic permeation behavior

Chlorinated polyvinyl chloride (CPVC)/polyvinyl pyrrolidone (PVP) membranes were prepared using the water vapor induced phase separation technique. The surface pore size of the membrane was dependent on the relative humidity (RH) and the PVP content. PVP was used as the pore-forming and wetting agent. However, as PVP could leach during the filtration process, the PVP was immobilized within the CPVC membrane by chemical cross-linking. This reduced the depletion of PVP from the membrane and maintained the hydrophilicity. The physical properties of the membranes were investigated before and after cross-linking using FT-IR, TGA, and contact angle measurements. The pure water flux of the membranes was measured using a filtration apparatus, and the quantity of PVP extracted from the prepared membranes was measured using a total organic carbon (TOC) analyzer. PVP immobilized on the microporous CPVC membranes showed an increased hydrophilicity and thermal resistance at a slight expense in water flux rate. This was confirmed by capillary flow porometry where the decrease in mean pore size of the membrane caused a decrease in water flux after cross-linking.