Influence of Carbon Sorbent Quantity on Breakthrough Time in Absorbent Filters for Antismog Half Mask Application

In this article, we present polymer non-woven fabrics with the addition of carbon sorbents being tested to estimate the breakthrough time and efficient protection against vapors present in smog. For this purpose, three substances were selected, which constitute an inhalation hazard and are smog components: cyclohexane, toluene, and sulfur dioxide. It was demonstrated that an increased quantity of carbon sorbent in polymeric filters significantly prolongs the breakthrough time. However, high sorbent quantities may increase the filter surface mass and air flow resistance. To optimize the protective parameters with functionality, a compromise between the two has to be found. By comparing the breakthrough times for different carbon sorbent quantities, the optimal filter composition was elaborated. The analyzed non-woven fabrics were manufactured by the melt-blown process and filled with ball-milled carbon sorbents supplied directly into the fabric blowing nozzle. Both protective performance and textural properties were analyzed for two commercially available carbon sorbents. Furthermore, it was proven that high values of sorbent-specific surface area translates directly into greater filter performance.

Investigation of helical strut attached vena cava filter hemodynamic performanc

Hemodynamic performance of the Celect Platinum vena cava filter and the revised forms of it with helical flow inducer strut were studied with computational fluid dynamic software Ansys Fluent 18. The central velocity and shear stress increased but overall flow disturbance has been observed minimal level. Central velocity increases to 9.72% with Celect filter, by the single helical flow inducer strut the rate reaches to 14.69%, and with doubled form it reaches to 19.73%. The filter surface shear rate increases to 8.29% with the single helical flow inducer strut and increases 13.31% with doubled attachment. Increased velocity and shear stress on the filter may eliminate short term thrombus build-up problems by breaking the big size particulates with the high shearing forces. The new struts may also contribute to the ability of the filter to capture smaller clots, as well as to dissolve them from being bigger. Shear stress in the vein wall increases approximately 6.63% with the filter placement. It raises to 8.06% and 9.45% with single and double helical flow inducer strut attachment. Increased vein wall shear may reduce the recirculation and clotting in the vein wall and it may prevent the accumulation of clots. The increased shear stress on the filter may cause the migration problem, design improvements can minimize this risk. Helical flow inducer strut attachment can cause efficacy increase, and the flow are normalized.

Eco-Friendly Poly(Vinyl Alcohol) Nanofiber-Based Air Filter for Effectively Capturing Particulate Matter

Due to the increasing use of polypropylene-based nonwoven dust masks and air filters, environmental problems that occur due to the plastic pollution resulting from the disposal of these materials have also increased. Hence, an eco-friendly air filter based on PVA nanofibers (NFs) was fabricated by electrospinning on a nonwoven fabric, and its performance was evaluated as a filter capable of blocking or capturing particulate matter. The quality factor of the optimized PVA NF-based air filter was found to be 0.010606 Pa−1, which is lower than that of a HEPA filter (0.015394 Pa−1), but higher than that of a cabin air filter (0.010517 Pa−1) and a dust mask (0.009102 Pa−1). The contamination level of the PVA NF-based filter was analyzed by optical and structural analyses of the filter surface. Finally, the filter was soaked in water to selectively remove the contaminated PVA NF layer, and the remaining nonwoven fabric was able to be reused to make the filter.

Optimising Dead-End Cake Filtration Using Poroelasticity Theory

Understanding the operation of filters used to remove particulates from fluids is important in many practical industries. Typically the particles are larger than the pores in the filter so a cake layer of particles forms on the filter surface. Here we extend existing models for filter blocking to account for deformation of the filter material and the cake layer due to the applied pressure that drives the fluid. These deformations change the permeability of the filter and the cake and hence the flow. We develop a new theory of compressible-cake filtration based on a simple poroelastic model in which we assume that the permeability depends linearly on local deformation. This assumption allows us to derive an explicit filtration law. The model predicts the possible shutdown of the filter when the imposed pressure difference is sufficiently large to reduce the permeability at some point to zero. The theory is applied to industrially relevant operating conditions, namely constant flux, maximising flux and constant pressure drop. Under these conditions, further analytical results are obtained, which yield predictions for optimal filter design with respect to given properties of the filter materials and the particles.

Field application of an improved protocol for environmental DNA extraction, purification, and measurement using Sterivex filter

Environmental DNA (eDNA) is increasingly popular as a useful non-invasive method to monitor and study biodiversity and community structure in freshwater and marine environments. To effectively extract eDNA from the filter surface is a fundamental factor determining the representativeness of the samples. We improved the eDNA extraction efficiency of an established Sterivex method by 12- to 16-fold using a larger volume of lysis buffer mix coupled with backflushing the cartridges. The DNeasy extraction column could be overloaded when the environmental sample input is high, possibly due to a higher nonspecific binding present in environmental samples, thus resulting in a relatively lower quantity measured. Therefore, we included an internal control DNA in the extraction to monitor the extraction and purification efficiencies in field samples, which is crucial for quantification of original eDNA concentration. The use of Takara Probe qPCR Mix supplemented with protein-based additives improved the robustness of the real time PCR assay on inhibitor-rich environmental samples, but prior purification by Qiagen PowerClean Pro Cleanup kit could be essential for inhibitor-rich water samples, even though the recovery rate was unexpectedly low (average 33.0%). The improved extraction and quantification complement the qualitative analyses including metabarcoding and metagenomics in field application.

The Challenge of Cleaning Woven Filter Cloth in the Beverage Industry—Wash Jets as an Appropriate Solution

Beverage production requires many different and complex unit operations. One crucial procedural step is filtration. Typical filters are filter presses, candle filters, membrane filters, belt filters, and drum filters, which require considerable hygienic precaution and the application of appropriate cleaning concepts. In the last decades, the hygienic design has become a central design feature of equipment in the beverage and food industries. Today, also correspondent concepts regarding filter cloth increasingly come to the fore. However, filter cloth cleaning is rapidly facing limitations. Complex filter geometries originating from different gauzes and sensitive polymeric materials hinder efficient cleaning. Additionally, extensive biological residues adhering to the filter surface increase the challenge of cleaning. The goal of this paper is to outline the cleaning of woven filter cloths systematically with a particular focus on beverages and correspondent biophysical interactions between filter and residue. Based on these elemental cleaning limits of filter cloths, this paper focuses mainly on jet cleaning as one of the most appropriate cleaning methods. The flow-mechanical properties are discussed in detail since these are precisely the parameters that, on the one hand, describe the understanding of the cleaning process and, on the other hand, show how a wash jet can be adjusted precisely. In contrast to conventional cleaning techniques, such wash jets are expeditious to adapt and offer the best prerequisites to enable demand-oriented and optimized cleaning concepts. The latest research and approaches are enhancing jet efficiency and highlight their potentials for future process strategies.

Quadrupling the N95 Supply during the COVID-19 Crisis with an Innovative 3D-Printed Mask Adaptor

The need for personal protective equipment during the COVID-19 pandemic is far outstripping our ability to manufacture and distribute these supplies to hospitals. In particular, the medical N95 mask shortage is resulting in healthcare providers reusing masks or utilizing masks with filtration properties that do not meet medical N95 standards. We developed a solution for immediate use: a mask adaptor, outfitted with a quarter section of an N95 respirator that maintains the N95 seal standard, thereby quadrupling the N95 supply. A variety of designs were 3D-printed and optimized based on the following criteria: seal efficacy, filter surface area and N95 respirator multiplicity. The final design is reusable and features a 3D-printed soft silicone base as well as a rigid 3D-printed cartridge to seal one-quarter of a 3M 1860 N95 mask. Our mask passed the computerized N95 fit test for six individuals. All files are publicly available with this publication. Our design can provide immediate support for healthcare professionals in dire need of medical N95 masks by extending the current supply by a factor of four.

Highly Portable and Sensitive Filter-Based Antibody-or DNA Aptamer-Enzyme-Linked Fluorescence Detection of Potential Bacterial Pathogens Proximal to Agricultural Fields

A novel, sensitive, rapid and highly portable system consisting of a membrane filtration unit connected to a large syringe with tubing was used to detect Escherchia coli and Salmonella enterica bacteria in a mobile laboratory setting. These simple fluorescent enzyme-linked molecular assays consisted of biotinylated DNA aptamers or antibodies which were allowed to bind the target bacteria and be deposited on 0.45 μm pore size membrane filters by suction, followed by binding of streptavidin-peroxidase conjugate, wash steps and development in Amplex® UltraRed (AUR; resazurin derivative) with hydrogen peroxide activation. Fluorescence values of developed AUR from the filter surface were assessed with a commercially-available handheld fluorometer. Preliminary data indicate detection limits in the range of 50–110 E. coli and Salmonella bacterial cells per sample with good specificity and total processing times under one hour.

Delayed Release of Intracellular Microcystin Following Partial Oxidation of Cultured and Naturally Occurring Cyanobacteria

Oxidation processes can provide an effective barrier to eliminate cyanotoxins by damaging cyanobacteria cell membranes, releasing intracellular cyanotoxins, and subsequently oxidizing these toxins (now in extracellular form) based on published reaction kinetics. In this work, cyanobacteria cells from two natural blooms (from the United States and Canada) and a laboratory-cultured Microcystis aeruginosa strain were treated with chlorine, monochloramine, chlorine dioxide, ozone, and potassium permanganate. The release of microcystin was measured immediately after oxidation (t ≤ 20 min), and following oxidant residual quenching (stagnation times = 96 or 168 h). Oxidant exposures (CT) were determined resulting in complete release of intracellular microcystin following chlorine (21 mg-min/L), chloramine (72 mg-min/L), chlorine dioxide (58 mg-min/L), ozone (4.1 mg-min/L), and permanganate (391 mg-min/L). Required oxidant exposures using indigenous cells were greater than lab-cultured Microcystis. Following partial oxidation of cells (oxidant exposures ≤ CT values cited above), additional intracellular microcystin and dissolved organic carbon (DOC) were released while the samples remained stagnant in the absence of an oxidant (>96 h after quenching). The delayed release of microcystin from partially oxidized cells has implications for drinking water treatment as these cells may be retained on a filter surface or in solids and continue to slowly release cyanotoxins and other metabolites into the finished water.

EXPERIMENTAL RESEARCH OF DUST POWER OF FILTERING MATERIALS FOR ANTI-DUST RESPIRATORS

The purpose is to carry out experimental investigations of the physicochemical properties of filtering materials for the manufacture of two-layer filters of high dust capacity of dust respirators for operating conditions of coal mines. The dust capacity of filter materials for the manufacture of two-layer filters was determined at a dust concentration of about 400 mg/m3, with a final pressure drop of 500 Pa (according to the requirements of DSTU EN 143 for filters of the 2nd class of protection). "AFA VP-10" filters with a diameter of 36 mm were used; "VLO 200" laboratory scales; "HS43" electronic stopwatch; the pressure drop on the filter boxes was monitored using an "MKV 250" compensation micro manometer. It is established that in order to increase the dust capacity of dust filter respirators, their filter should be combined with filter materials with different physicochemical properties to ensure a uniform distribution of dust sediment over the thickness of the filter layer. It is proved that the increase in the duration of the protective action of dust suppressors is possible due to the effect of aftofiltration, when the settled dust layer on the filter surface independently delays aerosol particles. The dependence of the differential pressure on the filter of the dust respirator on the change in the density of packing of fibres with dust is obtained, which allows determining the rational physicochemical properties of the materials of the filter layers of the filter for maximum dust intensity. It was found that the smallest increase in the air flow resistance of the multilayer filter was recorded by combining the filter layers with the fibre packing density of 30 and 60 g/cm3, respectively. The experimental dependences are established that will allow finding a rational combination of filter layers to ensure maximum dust capacity of the filter.