scholarly journals Comparative Performance Testing of Respirator versus Surgical Mask Using a Water Droplet Spray Model

2021 ◽  
Vol 18 (4) ◽  
pp. 1599
Author(s):  
Paul T. J. Scheepers ◽  
Heiman F. L. Wertheim ◽  
Maurice van Dael ◽  
Rob Anzion ◽  
Henk Jan Holterman ◽  
...  
Keyword(s):  
Water Droplet ◽  
Membrane Filter ◽  
Performance Testing ◽  
Test Method ◽  
Protective Equipment ◽  
Sensitive Test ◽  
Water Droplets ◽  
Comparative Performance ◽  
Fluorescent Marker ◽  
Droplet Spray

Background. During the SARS-CoV-2 pandemic, there was shortage of the standard respiratory protective equipment (RPE). The aim of this study was to develop a procedure to test the performance of alternative RPEs used in the care of COVID-19 patients. Methods. A laboratory-based test was developed to compare RPEs by total inward leakage (TIL). We used a crossflow nebulizer to produce a jet spray of 1–100 µm water droplets with a fluorescent marker. The RPEs were placed on a dummy head and sprayed at distances of 30 and 60 cm. The outcome was determined as the recovery of the fluorescent marker on a membrane filter placed on the mouth of the dummy head. Results. At 30 cm, a type IIR surgical mask gave a 17.7% lower TIL compared with an FFP2 respirator. At 60 cm, this difference was similar, with a 21.7% lower TIL for the surgical mask compared to the respirator. When adding a face shield, the TIL at 30 cm was further reduced by 9.5% for the respirator and 16.6% in the case of the surgical mask. Conclusions. A safe, fast and very sensitive test method was developed to assess the effectiveness of RPE by comparison under controlled conditions.

Initial-Position-Driven Opposite Directional Transport of Water Droplet on Wedge-Shaped Groove

Nanoscale ◽  
2021 ◽  
Author(s):  
Shaoqian Hao ◽  
Xie Zhang ◽  
Zheng Li ◽  
Jianlong Kou ◽  
Fengmin Wu
Keyword(s):  
Water Droplet ◽  
Initial Position ◽  
Water Droplets ◽  
Transport Direction ◽  
Directional Transport ◽  
Prevailing View ◽  
Functionalized Surface

Transport direction of water droplets on a functionalized surface is of great significance due to its wide applications in microfluidics technology. The prevailing view is that a water droplet on...

scholarly journals Water vapor transmission properties of acrylic organic coatings

2020 ◽  
Author(s):  
Réka Lilla Kovács ◽  
Lajos Daróczi ◽  
Péter Barkóczy ◽  
Eszter Baradács ◽  
Eszter Bakonyi ◽  
...  
Keyword(s):  
Water Vapor ◽  
Transmission Rate ◽  
Performance Testing ◽  
Preexponential Factor ◽  
Diffusion Activation Energy ◽  
Vapor Permeability ◽  
Coating Materials ◽  
Comparative Performance ◽  
Water Vapor Transmission ◽  
Arrhenius Function

AbstractIn this work, we evaluate the water vapor transmission rate (WVTR), the permeability (P), solubility (S), and diffusion (D) coefficients of Paraloid B44, Paraloid B72, and Incralac coatings in the temperature range of 5–35°C. The Arrhenius function—diffusion activation energy and preexponential factor—has also been determined from the data: $$D_{B44} = 35.2\;{\text{cm}}^{2} \;{\text{s}}^{ - 1} \exp \left( { - 25\;{\text{kJ mol}}^{ - 1} /{\text{RT}}} \right)$$ D B 44 = 35.2 cm 2 s - 1 exp - 25 kJ mol - 1 / RT ; $$D_{B72} = 9.5\;{\text{cm}}^{2} \;{\text{s}}^{ - 1} \exp \left( { - 23\;{\text{kJ mol}}^{ - 1} /{\text{RT}}} \right)$$ D B 72 = 9.5 cm 2 s - 1 exp - 23 kJ mol - 1 / RT ; $$D_{\text{Incralac}} = 622.8\;{\text{cm}}^{2} \;{\text{s}}^{ - 1} { \exp }\left( { - 28\;{\text{kJ mol}}^{ - 1} /{\text{RT}}} \right)$$ D Incralac = 622.8 cm 2 s - 1 exp - 28 kJ mol - 1 / RT . These resins are important coating materials, for example, for conservators to protect metallic artifacts, such as statues, against corrosion. Despite Paraloid B44 and B72 resins being considered as reference materials in conservation practice, that is, new coating materials (either water vapor retarders or transmitters) are often compared to them, there are no comprehensive data for the quantities describing the vapor permeability (P, S, D) of these materials. The measurements are based on the ISO cup-method using substrate/coating composite samples. The strength of this technique is that it can also be used when the coating is non-self-supporting; nevertheless, P, S, and D can be deduced for the coating layer itself, and it seems to be a standardizable procedure for comparative performance testing of coating materials. Paraloid B72 layers exhibited higher WVTRs—from 39 to 315 g m−2 day−1 as the temperature increased from 5 to 35°C—compared to Paraloid B44 and Incralac coatings—from 17 to 190 g m−2 day−1, respectively. The transmission rate parameters were also compared to the results of corrosion tests. Incralac was the most effective corrosion inhibitor, and the performance of the B44 was better than the B72, which is in good agreement with the transmission rate tests.

scholarly journals Performance Test of a Household Rocket Stoves Fired with Coconut Frond, Coconut Shell and Bamboo

2021 ◽  
Vol 8 (1) ◽  
pp. 59-64
Author(s):  
Almuzakkir . ◽  
Muhammad . ◽  
Adi Setiawan
Keyword(s):  
Thermal Efficiency ◽  
Fossil Fuels ◽  
Performance Test ◽  
Performance Testing ◽  
Biomass Energy ◽  
Test Method ◽  
Fuel Oil ◽  
Coconut Shell ◽  
Water Boiling Test ◽  
A Value

Fuel is something that is very important in everyday life. Almost every human being needs fuel to meet their needs and support their activities, for example cooking in household needs. Currently, fossil fuels or fuel oil (BBM) are still widely used to meet demand, however, it should be noted that fossil fuels or fuel oil (BBM) are non-renewable natural resources. The biomass rocket stove is one of the modern stove innovations that uses biomass energy as the main energy source. Rocket stoves are designed to increase fuel efficiency with thermal efficiency, a combination of the increased combustion efficiency and heat transfer associated with burning briquette fuel. The purpose of this research is to design and manufacture rocket stove fired with coconut and bamboo biomass for household needs as well as developing methods and equipment for performance testing of rocket stoves. In this study, several steps were carried out, including designing a rocket furnace, selecting biomass fuel and testing the performance of a rocket furnace. From the design of the biomass stove, it is noteworthy that the design with two holes makes the combustion air easily enters and makes combustion in the furnace more perfect and efficient. Water boiling test using three types of solid fuels with the cold start condition suggested that the highest thermal efficiency was coconut fronds with a value of 38% and the lowest thermal efficiency was found from coconut shell combustion, i.e. 22%. During hot start test, the highest thermal efficiency was obtained from coconut fronds firing with a value of 41%. Moreover, with simmer water boiling test method, firing the rocket stove with coconut fronds showed the highest thermal efficiency with a value of 37%. Keywords: Rocket Stoves, Coconut Fronds and Shells, Bamboo, Thermal Efficiency, .Water Boiling Tests.

scholarly journals Direct 24-Hour Presumptive Enumeration of Escherichia coli 0157:H7 in Foods Using Hydrophobic Grid Membrane Filter Followed by Serological Confirmation: Collaborative Study

1998 ◽  
Vol 81 (2) ◽  
pp. 403-418 ◽  
Author(s):  
Phyllis Entis ◽  
◽  
D Bryant ◽  
J Bryant ◽  
R G Bryant ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Membrane Filter ◽  
Collaborative Study ◽  
Reference Method ◽  
Test Method ◽  
Cottage Cheese ◽  
Apple Cider ◽  
Dairy Foods ◽  
E Coli ◽  
Repeatability And Reproducibility

abstract Fifteen laboratories took part in a collaborative study to validate a method for enumerating Escherichia coli 0157:H7. The method is based on use of a hydrophobic grid membrane filter and consists of 24 h presumptive enumeration on SD-39 Agar and serological confirmation to yield a confirmed E. coli 0157:H7 count. Six food products were analyzed: pasteurized apple cider, pasteurized 2% milk, cottage cheese, cooked ground pork, raw ground beef, and frozen whole egg. The test method produced significantly higher confirmed count results than did the reference method for milk, pork, and beef. Test method results were numerically higher than but statistically equivalent to reference method results for cheese, cider, and egg. The test method produced lower repeatability and reproducibility values than did the reference method for most food/inoculation level combinations and values very similar to those of the reference method for the remaining combinations. Overall, 94% of presumptive positive isolates from the test method were confirmed serologically as E. coli 0157:H7, and 98% of these were also biochemically typical of E. coli 0157:H7 (completed test). Corresponding rates for the reference method were 69 and 98%, respectively. On the basis of the results of this collaborative study and the precollaborative study that preceded it, it is recommended that this method be adopted official first action for enumeration of E. coli 0157:H7 in meats, poultry, dairy foods, infant formula, liquid eggs, mayonnaise, and apple cider

Development and performance testing of solar cookers

2007 ◽  
Vol 18 (3) ◽  
pp. 41-51 ◽  
Author(s):  
C.Z.M. Kimambo
Keyword(s):  
Fossil Fuels ◽  
Energy Use ◽  
Energy Requirement ◽  
Performance Testing ◽  
Comparative Performance ◽  
Study Results ◽  
Critical Issues ◽  
Sub Saharan ◽  
And Performance ◽  
Mental Testing

The most common type of energy used is firewood. In some Sub Saharan countries, up to 90% of total energy use is from firewood. The consumption of wood fuel is in some countries as high as twice the sustainable yield, something that has led to environ-mental degradation due to deforestation and scarci-ty of firewood. The use of fossil fuels such as kerosene and LPG for cooking is expensive. Solar energy is a non-consumptive and non-polluting fuel. It can help alleviate the problem of insecurity of cooking energy, which is the major domestic energy requirement. Several attempts have been made to introduce solar cookers in different coun-tries and have achieved variable successes. There are still critical issues yet to be resolved in order to make that technology acceptable for wider dissemi-nation. They include getting the most appropriate types of solar cookers for specific locations, opti-mum size/capacity, types of materials to be used, optimal design and affordable cost. In an attempt to resolve these issues, a comprehensive study involv-ing theoretical review, development work, experi-mental testing and evaluation of solar cookers was conducted for several years on six different types of solar cookers. The cookers are the ‘SunStove’ box cooker, wooden box cooker, panel cooker, reflector cooker with unpolished aluminium reflectors, reflec-tor cooker with polished aluminium reflectors and reflector cooker with glass mirror reflectors. This paper presents the results of the study. Results obtained indicate that many of the cookers could be used to cook food for households in areas with medium and high insolation, with appropriate selec-tion of the type and specification of the cookers. The specification should be based on the measured inso-lation data of the location indication of the direct and diffuse components. As a guiding tool, reflector cookers offer best comparative performance in areas with longest durations of clear sky (greatest direct beam), panel and collector cookers under moderate cloudy conditions and box cookers under very cloudy conditions.

Enumeration of β-Glucuronidase-Positive Escherichia coli in Foods by Using the ISO-GRID Method with SD-39 Agar

1998 ◽  
Vol 61 (7) ◽  
pp. 913-916 ◽  
Author(s):  
PHYLLIS ENTIS ◽  
IRINA LERNER
Keyword(s):  
Escherichia Coli ◽  
Membrane Filter ◽  
Reference Method ◽  
Grid Method ◽  
Test Method ◽  
Cottage Cheese ◽  
Filter Method ◽  
Official Method ◽  
Membrane Filter Method ◽  
Aoac Official

A study was undertaken to compare β-glucuronidase-positive Escherichia coli counts produced by the ISO-GRID hydrophobic grid membrane filter method using SD-39 agar (test method) with those produced by AOAC Official Method 990.11, an existing ISO-GRID method using lactose monensin glucuronate agar and buffered MUG agar (reference method). The methods were evaluated using 21 food products, with three independent lots of five replicate samples analyzed per product by both methods. The test and reference methods were statistically equivalent for 19 of the 21 products; frozen, raw ground lamb produced significantly higher counts using the reference method, whereas counts obtained from cottage cheese were significantly higher using the SD-39 agar-based method.

The Evaporation of Water Droplets in Superheated Steam

1968 ◽  
Vol 90 (4) ◽  
pp. 445-451 ◽  
Author(s):  
Kwan Lee ◽  
D. J. Ryley
Keyword(s):  
Reynolds Number ◽  
Glass Fiber ◽  
Water Droplet ◽  
Superheated Steam ◽  
Droplet Diameter ◽  
Steam Pressure ◽  
Water Droplets ◽  
Heating Up ◽  
Correlating Equation

The evaporation of a water droplet, diameter 230-1130μ, suspended on a 50μ diameter glass fiber was measured optically for the following range of variables: droplet Reynolds number 64-250, superheated steam pressure 14.7–29 psia, degrees of superheat 5–61 deg F; velocity 9–39 fps. The correlating equation was found to be Nu¯=2+0.74Re0.5Pr0.33 The apparatus and technique were proven using air as the evaporating medium. Calculations were made of the heating-up period at the beginning, and the drop asphericity at the end of a given test.

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