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Article: Flow visualization of an N95 respirator with and without an exhalation valve using schlieren imaging and light scattering.

Staymates, Matthew

Physics of fluids (Woodbury, N.Y. : 1994)

2020 Volume 32, Issue 11, Page(s) 111703

Abstract: This work demonstrates the qualitative fluid flow characteristics of a standard N95 respirator with and without an exhalation valve. Schlieren imaging was used to compare an adult male breathing through an N95 respirator with and without a valve. The ... ...

Abstract	This work demonstrates the qualitative fluid flow characteristics of a standard N95 respirator with and without an exhalation valve. Schlieren imaging was used to compare an adult male breathing through an N95 respirator with and without a valve. The schlieren imaging technique showed the flow of warm air passing through these respirators but did not provide information about droplet penetration. For this, strategic lighting of fog droplets was used with a mannequin head to visualize the penetration of droplets through both masks. The mannequin exhaled with a realistic flow rate and velocity that matched an adult male. The penetration of fog droplets was also visualized with a custom system that seals each respirator onto the end of a flow tube. Results of these qualitative experiments show that an N95 respirator without an exhalation valve is effective at blocking most droplets from penetrating through the mask material. Results also suggest that N95 respirators with exhalation valves are not appropriate as a source control strategy for reducing the proliferation of infectious diseases that spread via respiratory droplets.
Language	English
Publishing date	2020-11-02
Publishing country	United States
Document type	Journal Article
ZDB-ID	1472743-2
ISSN	1089-7666 ; 1070-6631
ISSN (online)	1089-7666
ISSN	1070-6631
DOI	10.1063/5.0031996
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: High-speed imaging system to visualize particle removal/collection via wipe sampling and aerodynamic sampling.

Staymates, Matthew / Gillen, Greg / Staymates, Jessica

The Review of scientific instruments

2019 Volume 90, Issue 6, Page(s) 63703

Abstract: This work describes a high-speed imaging system that enables the microscopic visualization of the removal and collection of micrometer-sized particles from surfaces during wipe sampling and aerodynamic sampling events. The system features a high-speed ... ...

Abstract	This work describes a high-speed imaging system that enables the microscopic visualization of the removal and collection of micrometer-sized particles from surfaces during wipe sampling and aerodynamic sampling events. The system features a high-speed digital camera, microlens, custom sample mount and sampling sled, and an illumination source. This imaging system enables direct visualization of wipe-particle and particle-particle interactions during sampling and provides insights relevant to the dynamics of particle removal and collection. Examples of common and adhesive-modified wipe materials sampling polymer microspheres and an explosive-laden fingerprint are given, along with visualization of particle removal via air jet impingement.
Language	English
Publishing date	2019-06-26
Publishing country	United States
Document type	Journal Article
ZDB-ID	209865-9
ISSN	1089-7623 ; 0034-6748
ISSN (online)	1089-7623
ISSN	0034-6748
DOI	10.1063/1.5096488
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Microscopy of Woven and Nonwoven Face Covering Materials: Implications for Particle Filtration.

Vicenzi, Edward P / Whittaker, Scott / Weaver, Jamie L / Staymates, Matthew E / Radney, James G / Zangmeister, Christopher D

Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada

2024 Volume 30, Issue 1, Page(s) 27–40

Abstract: A suite of natural, synthetic, and mixed synthetic-natural woven fabrics, along with nonwoven filtration layers from a surgical mask and an N95 respirator, was examined using visible light microscopy, scanning electron microscopy, and micro-X-ray ... ...

Abstract	A suite of natural, synthetic, and mixed synthetic-natural woven fabrics, along with nonwoven filtration layers from a surgical mask and an N95 respirator, was examined using visible light microscopy, scanning electron microscopy, and micro-X-ray computed tomography (µXCT) to determine the fiber diameter distribution, fabric thickness, and the volume of solid space of the fabrics. Nonwoven materials exhibit a positively skewed distribution of fiber diameters with a mean value of ≈3 μm, whereas woven fabrics exhibit a normal distribution of diameters with mean values roughly five times larger (>15 μm). The mean thickness of the N95 filtration material is 1093 μm and is greater than that of the woven fabrics that span from 420 to 650 μm. A new procedure for measuring the thickness of flannel fabrics is proposed that accounts for raised fibers. µXCT allowed for a quantitative nondestructive approach to measure fabric porosity as well as the surface area/volume. Cotton flannel showed the largest mean isotropy of any fabric, though fiber order within the weave is poorly represented in the surface electron images. Surface fabric isotropy and surface area/volume ratios are proposed as useful microstructural quantities to consider for future particle filtration modeling efforts of woven materials.
Language	English
Publishing date	2024-01-22
Publishing country	England
Document type	Journal Article
ZDB-ID	1385710-1
ISSN	1435-8115 ; 1431-9276
ISSN (online)	1435-8115
ISSN	1431-9276
DOI	10.1093/micmic/ozad138
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Article ; Online: Net Weights: Visualizing and Quantifying their Contribution to Drug Background Levels in Forensic Laboratories.

Sisco, Edward / Staymates, Matthew E / Watt, Laura M

Forensic chemistry (Amsterdam, Netherlands)

2021 Volume 20

Abstract: While the drug background in forensic laboratories has been quantified, the processes that most contribute to the background have not been extensively researched. This work presents both qualitative visualization and quantitative analysis of the spread ... ...

Abstract	While the drug background in forensic laboratories has been quantified, the processes that most contribute to the background have not been extensively researched. This work presents both qualitative visualization and quantitative analysis of the spread of simulant drug particulate during the process of taking net weights. The process was modeled using three masses of powder (0.2 g, 2 g, and 100 g). The net weight process, in which the mixture was poured onto weighing paper, was mimicked and the resulting aerosolized particulate was allowed to settle. Wetted cotton swabs were then used to sample 6.45 cm
Language	English
Publishing date	2021-06-18
Publishing country	Netherlands
Document type	Journal Article
ISSN	2468-1709
ISSN (online)	2468-1709
DOI	10.1016/j.forc.2020.100259
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Article ; Online: An Easy to Implement Approach for Laboratories to Visualize Particle Spread During the Handling and Analysis of Drug Evidence.

Sisco, Edward / Staymates, Matthew E / Burns, Amber

Forensic chemistry (Amsterdam, Netherlands)

2020 Volume 18

Abstract: Recent work has shown that detectable levels of drugs exists on nearly all surfaces within a forensic laboratory - especially within the drug chemistry unit. This is an expected occurrence due to the handling and opening of drug evidence that contains ... ...

Abstract	Recent work has shown that detectable levels of drugs exists on nearly all surfaces within a forensic laboratory - especially within the drug chemistry unit. This is an expected occurrence due to the handling and opening of drug evidence that contains powder material. The process of opening evidence, which produces aerosolized particulate that can settle on surfaces throughout the lab, has never been visualized. This work presents the first attempt to visualize the spread of particulate throughout the laboratory during the analysis of drug evidence and introduces an easy to implement approach laboratories can use to evaluate their specific protocols. By creating two simulated bricks of drugs that contained fluorescent particles, the spread of particulate was able to be monitored throughout the evidence handling process up to and including cleaning of surfaces after analysis. The protocols in this work, showed the spread of particulate, prior to cleaning, to be quite extensive, with transfer onto surfaces and items that were handled. In this study, cleaning with methanol after processing the evidence was shown to be effective at removing nearly all particulate that was released in the process. The use of visualization techniques such as this demonstrate promise for helping laboratories identify processes in their own protocols that may contribute to drug background levels and educate forensic chemists how trace residues spread.
Language	English
Publishing date	2020-09-30
Publishing country	Netherlands
Document type	Journal Article
ISSN	2468-1709
ISSN (online)	2468-1709
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Article ; Online: Optimization of confined direct analysis in real time mass spectrometry (DART-MS).

Sisco, Edward / Staymates, Matthew E / Forbes, Thomas P

The Analyst

2020 Volume 145, Issue 7, Page(s) 2743–2750

Abstract: Direct analysis in real time mass spectrometry (DART-MS) is seeing increased use in many fields, including forensic science, environmental monitoring, food safety, and healthcare. With increased use, novel configurations of the system have been created ... ...

Abstract	Direct analysis in real time mass spectrometry (DART-MS) is seeing increased use in many fields, including forensic science, environmental monitoring, food safety, and healthcare. With increased use, novel configurations of the system have been created to either aid in detection of traditionally difficult compounds or surfaces, provide a more reproducible analysis, and/or chemically image surfaces. This work focuses on increasing the fundamental understanding of one configuration, where the DART ionization gas is confined in a junction, such as with thermal desorption (TD) DART-MS. Using five representative compounds and a suite of visualization tools, the role of the DART ionization gas, Vapur flow rate, gas back pressure, and exit grid voltage were examined to better understand both the chemical and physical processes occurring inside the confined configuration. The use of nitrogen as a DART ionization gas was found to be more beneficial than helium because of enhanced mixing with the analyte vapors, providing a more reproducible response. Lower Vapur flow rates were also found to be advantageous as they increased the analyte residence time in the junction, thus increasing the probability of its ionization. Operation at even lower Vapur flow rates was achieved by modifying the junction to restrict the DART gas flow. The DART exit grid voltage and gas back pressure had little observed impact on analyte response. These results provide the foundation to better understand and identify best practices for using a confined DART-MS configuration.
Language	English
Publishing date	2020-02-24
Publishing country	England
Document type	Journal Article
ZDB-ID	210747-8
ISSN	1364-5528 ; 0003-2654
ISSN (online)	1364-5528
ISSN	0003-2654
DOI	10.1039/d0an00031k
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Article ; Online: Enhanced aerodynamic reach of vapor and aerosol sampling for real-time mass spectrometric detection using Venturi-assisted entrainment and ionization.

Forbes, Thomas P / Staymates, Matthew

Analytica chimica acta

2017 Volume 957, Page(s) 20–28

Abstract: Venturi-assisted ENTrainment and Ionization (VENTI) was developed, demonstrating efficient entrainment, collection, and transport of remotely sampled vapors, aerosols, and dust particulate for real-time mass spectrometry (MS) detection. Integrating the ... ...

Abstract	Venturi-assisted ENTrainment and Ionization (VENTI) was developed, demonstrating efficient entrainment, collection, and transport of remotely sampled vapors, aerosols, and dust particulate for real-time mass spectrometry (MS) detection. Integrating the Venturi and Coandă effects at multiple locations generated flow and analyte transport from non-proximate locations and more importantly enhanced the aerodynamic reach at the point of collection. Transport through remote sampling probes up to 2.5 m in length was achieved with residence times on the order of 10
Language	English
Publishing date	2017-03-08
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1483436-4
ISSN	1873-4324 ; 0003-2670
ISSN (online)	1873-4324
ISSN	0003-2670
DOI	10.1016/j.aca.2016.12.037
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Article ; Online: Hydration of Hydrophilic Cloth Face Masks Enhances the Filtration of Nanoparticles.

Zangmeister, Christopher D / Radney, James G / Staymates, Matthew E / Vicenzi, Edward P / Weaver, Jamie L

ACS applied nano materials

2021 Volume 4, Issue 3, Page(s) 2694–2701

Abstract: Under high humidity conditions that mimic respiration, the filtration efficiency (FE) of hydrophilic fabrics increases when challenged with hygroscopic nanoparticles, for example, respiratory droplets containing SARS-CoV-2. The FE and differential ... ...

Abstract	Under high humidity conditions that mimic respiration, the filtration efficiency (FE) of hydrophilic fabrics increases when challenged with hygroscopic nanoparticles, for example, respiratory droplets containing SARS-CoV-2. The FE and differential pressure (Δ
Language	English
Publishing date	2021-03-08
Publishing country	United States
Document type	Journal Article
ISSN	2574-0970
ISSN (online)	2574-0970
DOI	10.1021/acsanm.0c03319
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Article: The effect of reusing wipes for particle collection.

Staymates, Jessica L / Staymates, Matthew E / Lawrence, Jeffrey

International journal for ion mobility spectrometry : official publication of the International Society for Ion Mobility Spectrometry

2015 Volume 19, Page(s) 41–49

Abstract: Sample collection for Ion Mobility Spectrometry (IMS) analysis is typically completed by swiping a collection wipe over a suspect surface to collect trace residues. The work presented here addresses the need for a method to measure the collection ... ...

Abstract	Sample collection for Ion Mobility Spectrometry (IMS) analysis is typically completed by swiping a collection wipe over a suspect surface to collect trace residues. The work presented here addresses the need for a method to measure the collection efficiency performance of surface wipe materials as a function of the number of times a wipe is used to interrogate a surface. The primary purpose of this study is to investigate the effect of wipe reuse, i.e., the number of times a wipe is swiped across a surface, on the overall particle collection and IMS response. Two types of collection wipes (Teflon coated fiberglass and Nomex) were examined by swiping multiple times, ranging from 0 to 1000, over representative surfaces that are common to security screening environments. Particle collection efficiencies were determined by fluorescence microscopy and particle counting techniques, and were shown to improve dramatically with increased number of swiping cycles. Ion mobility spectrometry was used to evaluate the chemical response of known masses of explosives (deposited after reusing wipes) as a function of the wipe reuse number. Results show that chemical response can be negatively affected, and greatly depends upon the conditions of the surface in which the wipe is interrogating. For most parameters tested, the PCE increased after the wipe was reused several times. Swiping a dusty cardboard surface multiple times also caused an increase in particle collection efficiency but a decrease in IMS response. Scanning electron microscopy images revealed significant surface degradation of the wipes on dusty cardboard at the micrometer spatial scale level for Teflon coated wipes. Additionally, several samples were evaluated by including a seven second thermal desorption cycle at 235°C into each swipe sampling interval in order to represent the IMS heating cycle. Results were similar to studies conducted without this heating cycle, suggesting that the primary mechanism for wipe deterioration is mechanical rather than thermal.
Language	English
Publishing date	2015-11-04
Publishing country	Germany
Document type	Journal Article
ZDB-ID	2423554-4
ISSN	1865-4584 ; 1435-6163
ISSN (online)	1865-4584
ISSN	1435-6163
DOI	10.1007/s12127-015-0185-9
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Article ; Online: Filter Inserts Impact Cloth Mask Performance against Nano- to Micro-Sized Particles.

Radney, James G / Weaver, Jamie L / Vicenzi, Edward P / Staymates, Matthew E / Zangmeister, Christopher D

ACS nano

2021 Volume 15, Issue 8, Page(s) 12860–12868

Abstract: The United States Centers for Disease Control and Prevention and World Health Organization recognize that wearing cloth face coverings can slow the transmission of respiratory diseases via source control. Adding a partial layer of material with a high ... ...

Abstract	The United States Centers for Disease Control and Prevention and World Health Organization recognize that wearing cloth face coverings can slow the transmission of respiratory diseases via source control. Adding a partial layer of material with a high filtration efficiency (FE, e.g., polypropylene sheets that meet the HEPA standard) as an insert can potentially provide additional personal protection; however, data on the necessary areal coverage are sparse. The relationship between insert area ratio (IAR) relative to fabric area, FE, differential pressure (ΔP, a surrogate for breathability), and quality factor (QF, a ratio including FE and ΔP) utilizing two fabrics (rayon and 100% cotton lightweight flannel) and three insert materials (HEPA vacuum bag, sterilization wrap and paper coffee filter) was investigated. The effect of inserts on particle flows mimicking human exhalation is semiquantitatively and qualitatively examined using flow visualization techniques. The following was found: (1) The relationship between FE, ΔP, and QF is complex, and a trade-off exists between personal protection from filtration during inhalation and source control from leakage during exhalation; (2) FE and ΔP of the composite covering increase with IAR, and the rate is dependent upon insert type; (3) improvements (decrements) in the QF of the composite assemblage require inserts with a higher (lower) QF than the fabric and larger differences yield greater gains (losses); (4) the increased ΔP from an insert results in increased leakage during exhalation; (5) to minimize leaks, ΔP must be as low as possible; and (6) small relative areas not covered by an insert (i.e., IAR slightly smaller than 1) strongly deteriorate the benefits of an insert similar to small leaks in a covering.
MeSH term(s)	Humans ; Masks ; Respiratory Protective Devices ; Aerosols ; Textiles ; Filtration
Chemical Substances	Aerosols
Language	English
Publishing date	2021-07-12
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ISSN	1936-086X
ISSN (online)	1936-086X
DOI	10.1021/acsnano.1c05182
Database	MEDical Literature Analysis and Retrieval System OnLINE

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