scholarly journals Size-Dependent Filtration Efficiency of Alternative Facemask Filter Materials

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1868
Author(s):  
David I. A. Dhanraj ◽  
Shruti Choudhary ◽  
Udayabhanu Jammalamadaka ◽  
David H. Ballard ◽  
Benjamin M. Kumfer ◽  
...  
Keyword(s):  
Filtration Efficiency ◽  
Filter Media ◽  
Size Dependent ◽  
Breathing Resistance ◽  
Filter Materials ◽  
Triple Layer ◽  
The Media ◽  
3D Printed ◽  
American Society ◽  
20 Nm

The use of facemasks is proven to mitigate the spread of the coronavirus and other biological agents that cause disease. Various forms of facemasks, made using different materials, are being used extensively, and it is important to determine their performance characteristics. The size-dependent filtration efficiency and breathing resistance of household sterilization wrap fabrics, and isolation media (American Society for Testing and Materials (ASTM)- and non-ASTM-rated), were measured in filter-holder- and mannequin-in-chamber-based systems, focusing on particles sizes between 20 nm and 2 μm. Double-layer MERV-14 (Minimum Efficiency Reporting Values with rating 14) showed the highest filtration efficiency (94.9–73.3%) amongst household filter media, whereas ASTM-rated isolation masks showed the highest filtration efficiencies (95.6–88.7) amongst all the masks considered. Filtration efficiency of 3D-printed masks with replaceable filter media was found to depend on the degree of sealing around the media holder, which depended on the material’s compressibility. Filtration efficiencies of triple-layer combinations (95.8–85.3%) follow a profile similar to single layers but with improved filtration efficiencies.

Material Properties Analysis with Addition of Nanofibres for Air Intake Filtration in Internal Combustion Engines

2021 ◽  
Vol 18 (1) ◽  
pp. 8621-8636
Author(s):  
T. Dziubak
Keyword(s):  
Flow Resistance ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Filtration Efficiency ◽  
Combustion Engines ◽  
Test Results ◽  
Air Filtration ◽  
Filter Media ◽  
Air Filter ◽  
Filter Materials

The aim of this study is to provide an experimental properties evaluation of a standard filter material (cellulose) and materials with fiber layer addition with small diameters (nanofibers). Filter media, including cellulose, used in the internal combustion engine inlet air filtration are made of high diameter fibres, approx. 15 µm. Significantly higher separation and filtration efficiency performance are obtained for materials with lower fibre diameters (nanofibres), however, at the expense of a significantly higher pressure drop, affecting the engine performance. Filter media manufacturers mainly specify the structure parameters (pore size, air permeability and thickness), without giving any information on the dust filtration performance and rate. The literature includes test results for models of different filter media structures. Filtration process modelling using polydisperse dust with particles of different shape and density and irregular filter media structure is possible using advanced computer techniques, however, the process is complex and requires many simplifications. Test results can be applied directly in the automotive industry. The data can be obtained by experimental tests on filter medium specimens, complete filter elements or air filters which are costly and time-consuming tests, however, those test methods are the most reliable. Conditions and testing methodology for intake air filter materials used in internal combustion engines were developed. Filtration and flow resistance efficiency and accuracy were done depending on test dust mass stopped per unit area. Tested materials filtration efficiency was assessed by a filtration quality factor, which includes experimentally determined efficiency and accuracy as well as flow resistance values. Much higher efficiency and filtration accuracy of dust grains below 5 µm in filtration materials with nanofibers addition compared to standard filtration material (filter paper) were demonstrated. For the same flow resistance values, filter materials with nanofibers addition accumulate smaller dust mass than standard filter paper. Usage of materials with nanofibers addition used in motor vehicles intake air filtration ensures their high efficiency and accuracy. It minimises its components wear, but at the expense of faster flow resistance increase, which shortens filter life and increases filter replacement frequency. Results obtained during the experimental research partly fill the gap when it comes to the basic material properties used in internal combustion engines intake air filter partitions production.

scholarly journals Size Dependent Particle Removal Efficiency and Pressure Drop of a Dust Cleaning Material For Use as Facemask Filters for Protection during COVID-19

2020 ◽  
Author(s):  
David Dhanraj ◽  
Shruti Choudhary ◽  
Pat Raven ◽  
Pratim Biswas
Keyword(s):  
Pressure Drop ◽  
Removal Efficiency ◽  
Fine Particles ◽  
Electrostatic Charge ◽  
Filtration Efficiency ◽  
Particle Removal ◽  
Test Results ◽  
Filter Holder ◽  
Size Dependent ◽  
3D Printed

The COVID-19 pandemic has caused a severe demand for facemasks, and this has resulted in the use of those made from alternate media. As SARS-CoV-2 spreads primarily due to airborne droplets, it is critical to verify the filtration efficiency of these alternate media based facemasks. While several media are being tested and used, commercially available dust cleaners have shown reasonable filtration efficiency. This may also be due to the potential electrostatic charge on the surface which enhances capture of the fine particles. In this manuscript, we report the size dependent filtration efficiency studied systematically in a filter holder-based system as 47 mm punches; and test results on a mannequin that was 3D printed wearing a bandana mask that was placed in a chamber.

Coating techniques for glass beads as filter media for removal of manganese from water

2016 ◽  
Vol 17 (1) ◽  
pp. 95-106 ◽  
Author(s):  
Peter Rose ◽  
Simon Hager ◽  
Karl Glas ◽  
Dirk Rehmann ◽  
Thomas Hofmann
Keyword(s):  
Manganese Oxides ◽  
Glass Beads ◽  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Filter Media ◽  
Dry Coating ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Coated Glass ◽  
The Media

Dry as well as wet coating techniques were developed to coat glass beads as filter media to remove manganese from water. For dry coating, powdered manganese oxide ore was fixed on the media surface. Wet coating was achieved by depositing synthetic manganese oxides onto the bead surface. The media were characterized by electron microscopy as well as by testing the removal of Mn2+ in a continuous stirred tank reactor. Image analysis of microscopic pictures illustrated that the surface area could partly be coated by powdered material using dry coating methods, whereas complete coverage was achieved using wet coating approaches. With regard to dry coating techniques, Mn sorption uptake was higher for the adhesively dry coated glass beads than for beads where a binding agent was used. The wet coating column approach proved to be more successful than the coating of beads in a stirred tank reactor. Mn removal capability of the beads increased with higher reactant concentrations during coating. Oxide-coated glass beads applied in filter systems have the potential to improve conventional demanganization processes.

scholarly journals An Overview of the Removal Phosphorus in Wastewater

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Norwardatun Abd Roni ◽  
◽  
Suraya Hani Adnan ◽  
Nuramidah Hamidon ◽  
Tuan Noor Hasanah Tuan Ismail ◽  
...  
Keyword(s):  
Critical Factor ◽  
Recycled Concrete ◽  
Filter Media ◽  
Column Studies ◽  
Recycled Concrete Aggregates ◽  
Al Content ◽  
Removal Capacity ◽  
Filter Materials ◽  
Pre Treatment ◽  
P Removal

The high levels of phosphorus (P) removal occurring through human activities contributes to Eutrophication. Therefore, it is important to understand the quantity of P flows of the different filter materials. This paper provides an overview on the different filter media used for P removal from wastewater also the conventional wastewater treatment system for phosphorus removal. The filter materials consist of natural materials, industrial by-products and man-made products. Most filters have been investigated in batch and column studies in laboratory. The results from these overview vary for every filters and recycled concrete aggregates (RCA) have demonstrated promising properties with regard to P removal capacity. The chemical composition of the adsorption media is a critical factor. Because phosphorus is removed via sorption and precipitation processes, Calcium (Ca), Iron (Fe) and Aluminium (Al) content is important in efficient P removal. Thus filter media should be selected very carefully. In such systems, appropriate pre-treatment will also allow for a longer lifetime of the filter media, by decreasing the risk of clogging and allowing one to use finer reactive filter media with higher sorption capacity. The usage of these alternatives filters materials will ease the environmental problems that are currently perceived globally.

Size-Dependent Effect of Cu2O Nanocubes in Electrochemical and Photocatalytic Properties

2018 ◽  
Vol 18 (12) ◽  
pp. 8282-8288 ◽  
Author(s):  
Yuanyuan Tang ◽  
Yinlong Xu ◽  
Caiyu Qi ◽  
Xianyang Li ◽  
Enming Xing ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Visible Light ◽  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Absorption Capacity ◽  
Electrochemical Impedance Spectra ◽  
Size Dependent ◽  
Eis Measurements ◽  
20 Nm ◽  
Degradation Of Methyl Orange

Cu2O nanocubes with different size (ranging from 20 nm to 400 nm) were prepared by a seed-mediated method to systematically explore the strong size-dependent properties in photocatalytic degradation of methyl orange (MO). Cu2O nanotubes were characterized by TEM, XRD, UV-Vis measurements. The size-dependent photocatalytic efficiency of the Cu2O nanocubes was evaluated by degradation of methyl orange (MO) in water under visible light (λ > 420 nm) irradiation. Furthermore, the photocurrent, linear sweep voltammetry (LSV) and electrochemical impedance spectra (EIS) measurements were applied to elucidate the size-dependent properties of Cu2O nanocubes, which demonstrated that smaller Cu2O nanocubes with certain length (30 nm) showed higher current density, faster electron transfer and lower rate of charge recombination in their exposed (100) facet. Therefore, 30 nm Cu2O nanocubes showed stronger visible light absorption capacity and higher photocatalytic activity in MO degradation among a series of nanocubes (20, 30, 100, 130, 200 and 400 nm) and their corresponding photocatalytic activities decreased with increasing the particles sizes.

The Intersection of the Asian American Model Minority Myth and Sports

2015 ◽  
pp. 63-89
Author(s):  
Teresa A. Mok ◽  
David W. Chih
Keyword(s):  
Asian American ◽  
Media Coverage ◽  
Model Minority ◽  
The Internet ◽  
Model Minority Myth ◽  
Model Minority Stereotype ◽  
American Model ◽  
The Everyday ◽  
The Media ◽  
American Society

While the model minority stereotype depicts Asian Americans as having somehow “made it” in American society, rarely does the discourse involve Asian American athletes. The purpose of this chapter is to delineate how race and the model minority myth were an integral part of the media coverage and affected perceptions of the phenomenon known colloquially as “Linsanity,” which charted the unprecedented rise of Jeremy Lin. In 2012, Jeremy Lin became one of the most famous players in the NBA. By exploring the popular press coverage of this event, fueled by the Internet and social media, the intersection of the model minority myth and athletics are investigated. Through a combination of media critique and analysis, narrative, psychological literature, and coverage of other Asian and Asian American athletes, the authors illustrate how racism was a prominent factor and a significant part of the everyday discourse that permeated the coverage of Jeremy Lin.

scholarly journals Comparison of Electrostatic Charging at Different Locations in the Melt Blowing Process

2000 ◽  
Vol os-9 (3) ◽  
pp. 1558925000OS-90
Author(s):  
Peter Ping-yi Tsai ◽  
Guo-wei Qin ◽  
Charles Hassenboehler
Keyword(s):  
Flow Resistance ◽  
High Efficiency ◽  
Air Flow ◽  
Filtration Efficiency ◽  
Fiber Glass ◽  
Melt Blowing ◽  
Electrostatic Charging ◽  
The Media

Melt blown (MB) fabrics are composed of fine fibers which contribute to high filtration efficiency (FE) and low air flow resistance compared to high efficiency filtration media such as fiber glass paper. Furthermore, MB fabrics are mostly made of polypropylene (PP) polymer, which can be electrostatically charged to enhance the media filtration efficiency without the increase of air flow resistance. However, different charging techniques or charging at different locations on the MB line will contribute to different filtration efficiency. This paper compares the efficiencies of different charging techniques in the MB line.

Sticking to the Script

2017 ◽  
Author(s):  
Sujatha Fernandes
Keyword(s):  
Young People ◽  
Undocumented Students ◽  
Political Engagement ◽  
Dream Act ◽  
Immigration Reform ◽  
Immigrant Rights ◽  
Undocumented Youth ◽  
Legislative Agenda ◽  
The Media ◽  
American Society

This chapter looks at how storytelling was used by mainstream immigrant rights groups to produce an aspiring class of upwardly mobile and self-reliant undocumented youth while defusing broader migrant rights activism. In the campaign for legalization through a DREAM Act, the undocumented students known as Dreamers told their stories to the legislature and the media. The students were given scripts to follow that emphasized their achievements, assimilation into American society, and rejection of their home countries. In the lead-up to the 2008 national election and the subsequent push for Comprehensive Immigration Reform (CIR), groups of young people were mobilized in mass storytelling trainings across the country to support the electoral and legislative agenda of mainstream organizations. Eventually, many young people rebelled against this orchestration and sought to take control over their own representations. Some even began to move away from storytelling as a mode of political engagement altogether.

The Media and American Society

1992 ◽  
Vol 6 (4) ◽  
pp. 14-19
Author(s):  
J. Nerone
Keyword(s):  
The Media ◽  
American Society

“Nothing but Words”? Chronicling and Storytelling in Robert Coover's The Public Burning

2009 ◽  
Vol 44 (1) ◽  
pp. 171-186
Author(s):  
THEOPHILUS SAVVAS
Keyword(s):  
Political Culture ◽  
Atomic Bomb ◽  
Vice President ◽  
Narrative Methods ◽  
The Public ◽  
Richard Nixon ◽  
The Past ◽  
Third Person ◽  
The Media ◽  
American Society

Robert Coover's 1977 novel The Public Burning is a dramatic re-presentation of the last three days of the lives of Julius and Ethel Rosenberg. Dubbed the “atomic spies” by the media, the Rosenbergs were accused of passing on the “secret” of the atomic bomb to the Russians. The sensational trial provoked widespread attention for its seeming encapsulation of the fault lines in American society opened up by anticommunism and the emergent Cold War. Found guilty, they were the first American nationals to be executed for espionage. This paper analyses the different narrative methods that Coover employs to re-present the past. In particular I focus on Coover's juxtaposition of a third-person, seemingly omniscient, narrator with the first-person narratological voice of then Vice President Richard Nixon. I suggest that we can best understand this not simply as providing objective and subjective versions of the event, as some critics have claimed, but rather as a distinction between history as chronicle (or what I call a synchronic method of history), and history as storytelling (or diachrony). Through this The Public Burning becomes not just a satirical critique of the specific political culture of the time, I contend, but, more fundamentally, a general exploration of the difficulties of reconstituting past events into knowledge. It is here, perhaps, where the novel's continuing relevance for today lies.

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