scholarly journals Practical considerations for Ultraviolet-C radiation mediated decontamination of N95 respirator against SARS-CoV-2 virus

2020 ◽  
Author(s):  
Guillaume R. Golovkine ◽  
Allison W. Roberts ◽  
Chase Cooper ◽  
Sebastian Riano ◽  
Angela M. DiCiccio ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Model Material ◽  
Efficacy Data ◽  
Light Emitting ◽  
Ultraviolet C ◽  
N95 Respirators ◽  
Uv C ◽  
Disinfection Chamber

AbstractDecontaminating N95 respirators for reuse could mitigate shortages during the COVID-19 pandemic. We tested a portable UV-C light-emitting diode disinfection chamber and found that decontamination efficacy depends on mask model, material and location on the mask. This emphasizes the need for caution when interpreting efficacy data of UV-C decontamination methods.

scholarly journals Practical considerations for Ultraviolet-C radiation mediated decontamination of N95 respirator against SARS-CoV-2 virus

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258336
Author(s):  
Guillaume R. Golovkine ◽  
Allison W. Roberts ◽  
Chase Cooper ◽  
Sebastian Riano ◽  
Angela M. DiCiccio ◽  
...  
Keyword(s):  
United States ◽  
Light Emitting Diode ◽  
The United States ◽  
Model Material ◽  
Efficacy Data ◽  
Light Emitting ◽  
Ultraviolet C ◽  
N95 Respirators ◽  
Uv C ◽  
Disinfection Chamber

Decontaminating N95 respirators for reuse could mitigate shortages during the COVID-19 pandemic. Although the United States Center for Disease Control has identified Ultraviolet-C irradiation as one of the most promising methods for N95 decontamination, very few studies have evaluated the efficacy of Ultraviolet-C for SARS-CoV-2 inactivation. In addition, most decontamination studies are performed using mask coupons that do not recapitulate the complexity of whole masks. We sought to directly evaluate the efficacy of Ultraviolet-C mediated inactivation of SARS-CoV-2 on N95 respirators. To that end we created a portable UV-C light-emitting diode disinfection chamber and tested decontamination of SARS-CoV-2 at different sites on two models of N95 respirator. We found that decontamination efficacy depends on mask model, material and location of the contamination on the mask. Our results emphasize the need for caution when interpreting efficacy data of UV-C decontamination methods.

scholarly journals UV-C LED Irradiation Reduces Salmonella on Chicken and Food Contact Surfaces

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1459
Author(s):  
Alexandra Calle ◽  
Mariana Fernandez ◽  
Brayan Montoya ◽  
Marcelo Schmidt ◽  
Jonathan Thompson
Keyword(s):  
Light Emitting Diode ◽  
Chicken Breast ◽  
Light Emitting ◽  
Work Surface ◽  
Food Contact ◽  
Bacterial Aggregation ◽  
Food Contact Surfaces ◽  
Contact Surfaces ◽  
Uv C ◽  
Surface Pores

Ultraviolet (UV-C) light-emitting diode (LED) light at a wavelength of 250–280 nm was used to disinfect skinless chicken breast (CB), stainless steel (SS) and high-density polyethylene (HD) inoculated with Salmonella enterica. Irradiances of 2 mW/cm2 (50%) or 4 mW/cm2 (100%) were used to treat samples at different exposure times. Chicken samples had the lowest Salmonella reduction with 1.02 and 1.78 Log CFU/cm2 (p ≤ 0.05) after 60 and 900 s, respectively at 50% irradiance. Higher reductions on CB were obtained with 100% illumination after 900 s (>3.0 Log CFU/cm2). Salmonella on SS was reduced by 1.97 and 3.48 Log CFU/cm2 after 60 s of treatment with 50% and 100% irradiance, respectively. HD showed a lower decrease of Salmonella, but still statistically significant (p ≤ 0.05), with 1.25 and 1.77 Log CFU/cm2 destruction for 50 and 100% irradiance after 60 s, respectively. Longer exposure times of HD to UV-C yielded up to 99.999% (5.0 Log CFU/cm2) reduction of Salmonella with both irradiance levels. While UV-C LED treatment was found effective to control Salmonella on chicken and food contact surfaces, we propose three mechanisms contributing to reduced efficacy of disinfection: bacterial aggregation, harboring in food and work surface pores and light absorption by fluids associated with CB.

scholarly journals Mapping of UV-C dose and SARS-CoV-2 viral inactivation across N95 respirators during decontamination

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alisha Geldert ◽  
Alison Su ◽  
Allison W. Roberts ◽  
Guillaume Golovkine ◽  
Samantha M. Grist ◽  
...  
Keyword(s):  
Optical Simulation ◽  
Pathogen Inactivation ◽  
Viral Inactivation ◽  
Flexible Form ◽  
Measurement Tools ◽  
Ultraviolet C ◽  
N95 Respirators ◽  
Uv C ◽  
Dose Difference

AbstractDuring public health crises like the COVID-19 pandemic, ultraviolet-C (UV-C) decontamination of N95 respirators for emergency reuse has been implemented to mitigate shortages. Pathogen photoinactivation efficacy depends critically on UV-C dose, which is distance- and angle-dependent and thus varies substantially across N95 surfaces within a decontamination system. Due to nonuniform and system-dependent UV-C dose distributions, characterizing UV-C dose and resulting pathogen inactivation with sufficient spatial resolution on-N95 is key to designing and validating UV-C decontamination protocols. However, robust quantification of UV-C dose across N95 facepieces presents challenges, as few UV-C measurement tools have sufficient (1) small, flexible form factor, and (2) angular response. To address this gap, we combine optical modeling and quantitative photochromic indicator (PCI) dosimetry with viral inactivation assays to generate high-resolution maps of “on-N95” UV-C dose and concomitant SARS-CoV-2 viral inactivation across N95 facepieces within a commercial decontamination chamber. Using modeling to rapidly identify on-N95 locations of interest, in-situ measurements report a 17.4 ± 5.0-fold dose difference across N95 facepieces in the chamber, yielding 2.9 ± 0.2-log variation in SARS-CoV-2 inactivation. UV-C dose at several on-N95 locations was lower than the lowest-dose locations on the chamber floor, highlighting the importance of on-N95 dose validation. Overall, we integrate optical simulation with in-situ PCI dosimetry to relate UV-C dose and viral inactivation at specific on-N95 locations, establishing a versatile approach to characterize UV-C photoinactivation of pathogens contaminating complex substrates such as N95s.

scholarly journals 4 Gbps wireless optical communications up to 5 m using a UV-C micro-light-emitting diode array

2021 ◽  
Author(s):  
Jonathan J.D. McKendry ◽  
Enyuan Xie ◽  
Mohamed Sufyan Islim ◽  
Xiaobin Sun ◽  
Daniel MacLure ◽  
...  
Keyword(s):  
Optical Communications ◽  
Light Emitting Diode ◽  
Diode Array ◽  
Light Emitting ◽  
Wireless Optical Communications ◽  
Uv C

Effects of ultraviolet-C light-emitting diodes at 275 nm on inactivation of Alicyclobacillusacidoterrestris vegetative cells and its spores as well as the quality attributes of orange juice

2020 ◽  
pp. 108201322095752 ◽  
Author(s):  
Yafei Zhai ◽  
Jiali Tian ◽  
Ruonan Ping ◽  
Hongxia Xiu ◽  
Qisen Xiang ◽  
...  
Keyword(s):  
Orange Juice ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Titratable Acidity ◽  
Quality Attributes ◽  
Soluble Solids ◽  
Total Phenolic ◽  
Vegetative Cells ◽  
Light Emitting ◽  
Ultraviolet C

Alicyclobacillus acidoterrestris is a thermoacidophilic, spore-forming bacillus. A. acidoterrestris and its spores can survive in pasteurized juices and cause microbial spoilage. In this work, the effects of ultraviolet-C light-emitting diodes at 275 nm on the inactivation of A. acidoterrestris vegetative cells and its spores in commercial pasteurized orange juice were studied. Meanwhile, the effects of ultraviolet-C light-emitting diodes on the quality attributes of the orange juice were also investigated. The quantities of A. acidoterrestris vegetative cells and its spores inoculated in orange juice were reduced by 6.04 and 2.49 log10 CFU/mL after ultraviolet-C light-emitting diode treatment at 220 mJ/cm2, respectively. The Weibull and Weibull plus tail models were satisfactorily fitted to estimate the reductions of A. acidoterrestris vegetative cells and its spores in orange juice, respectively. Physicochemical properties (pH, titratable acidity, total soluble solids, and clarity) of orange juice did not change significantly after exposure to ultraviolet-C light-emitting diodes. However, the total phenolic content of orange juice decreased with increasing fluence. In addition, ultraviolet-C light-emitting diode treatment at a higher fluence led to a noticeable color difference. These results indicate that ultraviolet-C light-emitting diode treatment has a potential application in the juice processing industry.

An AlGaN Core–Shell Tunnel Junction Nanowire Light-Emitting Diode Operating in the Ultraviolet-C Band

Nano Letters ◽  
2017 ◽  
Vol 17 (2) ◽  
pp. 1212-1218 ◽  
Author(s):  
S. M. Sadaf ◽  
S. Zhao ◽  
Y. Wu ◽  
Y.-H. Ra ◽  
X. Liu ◽  
...  
Keyword(s):  
Tunnel Junction ◽  
Light Emitting Diode ◽  
Core Shell ◽  
Light Emitting ◽  
Ultraviolet C

scholarly journals Light Guide Layer Thickness Optimization for Enhancement of the Light Extraction Efficiency of Ultraviolet Light–Emitting Diodes

2021 ◽  
Author(s):  
Zhi Ting Ye ◽  
Yuan Heng Cheng ◽  
Li Wei Hung ◽  
Kung Hsieh Hsu ◽  
Yu Chang Hu
Keyword(s):  
Layer Thickness ◽  
Extraction Efficiency ◽  
Light Guide ◽  
Light Emitting Diode ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Thickness Optimization ◽  
Optimal Thickness ◽  
Light Emitting ◽  
Uv C

Abstract Challenges related to deep-ultraviolet light-emitting diode substrates include material costs and lattice mismatch. Sapphire substrates are commonly used, although their high refractive index can result in the total internal reflection of light whereby some light is absorbed, reducing light extraction efficiency (LEE). In this study, we proposed an optimal thickness value of a sapphire substrate light guide layer through first-order optical design and used the optical simulation software Ansys SPEOS to assess and refine its effect on LEE. AlGaN ultraviolet-C light-emitting diode (UV-C LED) wafers with a substrate thickness of 150–700 μm were used. The simulation proceeded under a UV-C LED center wavelength of 275 nm to determine the optimal thickness of the light guide layer. Finally, the experimental results demonstrated that a light guide layer thickness of 150 μm resulted in a reference output power of 13.53 mW, and an increased thickness of 600 um resulted in output power of 20.58 mW. The LEE can therefore be increased by 1.52 times through light guide layer thickness optimization.

scholarly journals Effectiveness of Ultraviolet-C Light and a High-Level Disinfection Cabinet for Decontamination of N95 Respirators

2020 ◽  
Vol 5 (1) ◽  
pp. 52 ◽  
Author(s):  
Jennifer L. Cadnum ◽  
Daniel Li ◽  
Sarah N. Redmond ◽  
Amrita R. John ◽  
Basya Pearlmutter ◽  
...  
Keyword(s):  
Methicillin Resistant Staphylococcus Aureus ◽  
Test Method ◽  
Dry Heat ◽  
Ultraviolet C ◽  
Multiple Cycles ◽  
American Society ◽  
High Level ◽  
N95 Respirators ◽  
Uv C ◽  
Disk Test

Background-Shortages of personal protective equipment (PPE) including N95 filtering facepiece respirators is an urgent concern in the setting of the global COVID-19 pandemic.  Decontamination of PPE could be useful to maintain adequate supplies, but there is uncertainty regarding the efficacy of decontamination technologies.Methods-A modification of the American Society for Testing and Materials standard quantitative carrier disk test method (ASTM E-2197-11) was used to examine the effectiveness of ultraviolet-C (UV-C) light, a high-level disinfection cabinet that generates aerosolized peracetic acid and hydrogen peroxide, and dry heat at 70°C for 30 minutes for decontamination of bacteriophages Phi6 and MS2 and methicillin-resistant Staphylococcus aureus (MRSA) inoculated onto 3 commercial N95 respirators.  Three and 6 log10 reductions on N95 respirators were considered effective for decontamination and disinfection, respectively. Results-UV-C administered as a 1-minute cycle in a UV-C box or a 30-minute cycle by a room decontamination device reduced contamination but did not meet criteria for decontamination of the viruses from all sites for any of the N95s.  The high-level disinfection cabinet was effective for decontamination of all the organisms from the N95s and achieved disinfection with 3 disinfection cycles over ~60 minutes.  Dry heat at 70°C for 30 minutes was not effective for decontamination of the bacteriophages.  Conclusions-UV-C could be useful to reduce contamination on N95 respirators.  However, the UV-C technologies studied did not meet our criteria for decontamination under the test conditions used.  The high-level disinfection cabinet was effective for decontamination of N95s and met criteria for disinfection with multiple cycles.

scholarly journals Effects of Combined Aerosolization with Ultraviolet C Light-Emitting Diode on Enterohemorrhagic Escherichia coli and Staphylococcus aureus Attached to Soft Fresh Produce

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1834
Author(s):  
Chae-Lim Lee ◽  
Geun-Hyang Kim ◽  
Ki-Sun Yoon
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Light Emitting Diode ◽  
Fresh Produce ◽  
Combined Treatment ◽  
Enterohemorrhagic Escherichia Coli ◽  
Light Emitting ◽  
Ultraviolet C ◽  
And Staphylococcus Aureus ◽  
Led Irradiation

Washing soft fresh produce such as strawberries, baby leaves, and sliced onions with sanitizing agents is challenging due to their fragile texture. Thus, treatments like aerosolization using slightly acidic electrolyzed water (SAEW) and ultraviolet C light-emitting diode (UVC LED) irradiation may be good alternatives. In the present study, the reduction effects of a combined treatment of aerosolization using SAEW and UVC LED irradiation on enterohemorrhagic Escherichia coli (EHEC) and Staphylococcus aureus attached to strawberries, baby leaves, and sliced onions were investigated. The behaviours of EHEC and S. aureus, moisture loss, colour measurement, and visual appearance were also analyzed at 10 and 15 °C for 7 days. The reduction effect of the combined treatment with 100 SAEW and UVC LED was higher (0.53–0.92 log CFU g−1) than a single aerosolization treatment (0.11–0.41 log CFU g−1), regardless of samples or pathogens. A greater effect on EHEC and S. aureus reduction was observed in strawberries (0.74 and 0.92 log CFU g−1) than in baby leaves (0.62 and 0.53 log CFU g−1) and sliced onions (0.55 and 0.62 log CFU g−1). The combined treatment further reduced the EHEC and S. aureus populations in strawberries during 7 days of storage at 10 and 15 °C. However, the EHEC and S. aureus populations were maintained in baby leaves and sliced onions at 10 °C for 7 days. Additionally, the greatest effect on the maintenance of colour and appearance was obtained in the combined treatment. Since the combined treatment reduces EHEC and S. aureus populations and preserves visual quality, it could be expected to extend the shelf life of soft fresh produce at the retailer stage of the supply chain.

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