scholarly journals UV-C decontamination for N95 emergency reuse: Quantitative dose validation with photochromic indicators

2020 ◽  
Author(s):  
Alison Su ◽  
Samantha M. Grist ◽  
Alisha Geldert ◽  
Anjali Gopal ◽  
Amy E. Herr
Keyword(s):  
Dynamic Range ◽  
Medical Personnel ◽  
Consumer Electronics ◽  
Critical Design ◽  
Design Considerations ◽  
Optical Attenuators ◽  
N95 Respirators ◽  
Dose Variation ◽  
Uv C

With COVID-19 N95 respirator shortages, frontline medical personnel are forced to reuse this disposable − but sophisticated − multilayer textile respirator. Widely used for decontamination of nonporous surfaces, UV-C light has germicidal efficacy on porous, non-planar N95 respirators when ≥1.0 J/cm^2 dose is applied across all surfaces. Here, we address outstanding limitations of photochromic indicators (qualitative readout and insufficient dynamic range) and introduce a photochromic UV-C dose quantification technique for: (1) design of UV-C treatments and (2) in-process UV-C dose validation. Our methodology establishes that color-changing dosimetry can achieve the necessary accuracy (>90%), uncertainty (<10%), and UV-C specificity (>95%). Furthermore, we adapt consumer electronics for accessible quantitative readout and extend the dynamic range >10× using optical attenuators. In a measurement infeasible with radiometers, we observe striking 20× dose variation over 3D N95 facepieces. By transforming photochromic indicators into quantitative dosimeters, we illuminate critical design considerations for both photochromic indicators and UV-C decontamination.

scholarly journals Quantitative UV-C dose validation with photochromic indicators for informed N95 emergency decontamination

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0243554
Author(s):  
Alison Su ◽  
Samantha M. Grist ◽  
Alisha Geldert ◽  
Anjali Gopal ◽  
Amy E. Herr
Keyword(s):  
Empirical Evidence ◽  
Dynamic Range ◽  
Medical Personnel ◽  
Consumer Electronics ◽  
Optical Attenuators ◽  
Dose Measurements ◽  
N95 Respirators ◽  
Dose Variation ◽  
Uv C ◽  
Treatment Design

With COVID-19 N95 shortages, frontline medical personnel are forced to reuse this disposable–but sophisticated–multilayer respirator. Widely used to decontaminate nonporous surfaces, UV-C light has demonstrated germicidal efficacy on porous, non-planar N95 respirators when all surfaces receive ≥1.0 J/cm2 dose. Of utmost importance across disciplines, translation of empirical evidence to implementation relies upon UV-C measurements frequently confounded by radiometer complexities. To enable rigorous on-respirator measurements, we introduce a photochromic indicator dose quantification technique for: (1) UV-C treatment design and (2) in-process UV-C dose validation. While addressing outstanding indicator limitations of qualitative readout and insufficient dynamic range, our methodology establishes that color-changing dosimetry can achieve the necessary accuracy (>90%), uncertainty (<10%), and UV-C specificity (>95%) required for UV-C dose measurements. In a measurement infeasible with radiometers, we observe a striking ~20× dose variation over N95s within one decontamination system. Furthermore, we adapt consumer electronics for accessible quantitative readout and use optical attenuators to extend indicator dynamic range >10× to quantify doses relevant for N95 decontamination. By transforming photochromic indicators into quantitative dosimeters, we illuminate critical considerations for both photochromic indicators themselves and UV-C decontamination processes.

scholarly journals Integrated photothermal decontamination device for N95 respirators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marcelo Muñoz ◽  
Maxime Comtois-Bona ◽  
David Cortes ◽  
Cagla Eren Cimenci ◽  
Qiujiang Du ◽  
...  
Keyword(s):  
Low Income ◽  
Temperature Treatment ◽  
Low Income Countries ◽  
Effective Vaccine ◽  
Global Pandemic ◽  
Photothermal Treatment ◽  
Mild Temperature ◽  
N95 Respirators ◽  
Uv C

AbstractThe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for the COVID-19 global pandemic has infected over 25 million people worldwide and resulted in the death of millions. The COVID-19 pandemic has also resulted in a shortage of personal protective equipment (PPE) in many regions around the world, particularly in middle- and low-income countries. The shortages of PPE, such as N95 respirators, is something that will persist until an effective vaccine is made available. Thus, devices that while being easy to operate can also be rapidly deployed in health centers, and long-term residences without the need for major structural overhaul are instrumental to sustainably use N95 respirators. In this report, we present the design and validation of a decontamination device that combines UV-C & B irradiation with mild-temperature treatment. The device can decontaminate up to 20 masks in a cycle of < 30 min. The decontamination process did not damage or reduce the filtering capacity of the masks. Further, the efficacy of the device to eliminate microbes and viruses from the masks was also evaluated. The photothermal treatment of our device was capable of eradicating > 99.9999% of the bacteria and > 99.99% of the virus tested.

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 Applying heat and humidity using stove boiled water for decontamination of N95 respirators in low resource settings

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0255338
Author(s):  
Siddharth Doshi ◽  
Samhita P. Banavar ◽  
Eliott Flaum ◽  
Surendra Kulkarni ◽  
Ulhas Vaidya ◽  
...  
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Low Resource Settings ◽  
Low Resource ◽  
Surgical Masks ◽  
Temperature And Humidity ◽  
Similar Temperature ◽  
N95 Respirators ◽  
Electricity Access ◽  
Uv C

Global shortages of N95 respirators have led to an urgent need of N95 decontamination and reuse methods that are scientifically validated and available world-wide. Although several large scale decontamination methods have been proposed (hydrogen peroxide vapor, UV-C); many of them are not applicable in remote and low-resource settings. Heat with humidity has been demonstrated as a promising decontamination approach, but care must be taken when implementing this method at a grassroots level. Here we present a simple, scalable method to provide controlled humidity and temperature for individual N95 respirators which is easily applicable in low-resource settings. N95 respirators were subjected to moist heat (>50% relative humidity, 65–80°C temperature) for over 30 minutes by placing them in a sealed container immersed in water that had been brought to a rolling boil and removed from heat, and then allowing the containers to sit for over 45 minutes. Filtration efficiency of 0.3–4.99 μm incense particles remained above 97% after 5 treatment cycles across all particle size sub-ranges. This method was then repeated at a higher ambient temperature and humidity in Mumbai, using standard utensils commonly found in South Asia. Similar temperature and humidity profiles were achieved with no degradation in filtration efficiencies after 6 cycles. Higher temperatures (>70°C) and longer treatment times (>40 minutes) were obtained by insulating the outer vessel. We also showed that the same method can be applied for the decontamination of surgical masks. This simple yet reliable method can be performed even without electricity access using any heat source to boil water, from open-flame stoves to solar heating, and provides a low-cost route for N95 decontamination globally applicable in resource-constrained settings.

scholarly journals Specificity of UV-C LED Disinfection Efficacy for Three N95 Respirators

2021 ◽  
Author(s):  
C. Carolina Ontiveros ◽  
David C. Shoults ◽  
Sean MacIsaac ◽  
Kyle D. Rauch ◽  
Crystal L. Sweeney ◽  
...  
Keyword(s):  
Uv Light ◽  
Woven Fabric ◽  
Uv Disinfection ◽  
Protective Equipment ◽  
Specific Design ◽  
Elastic Band ◽  
Independent Variables ◽  
Uv Technology ◽  
N95 Respirators ◽  
Uv C

Abstract The recent surge in the use of UV technology for personal protective equipment (PPE) has created a unique learning opportunity for the UV industry to deepen surface disinfection knowledge, especially on surfaces with complex geometries, such as the N95 filter facepiece respirators (FFR). The work outlined in this study addresses the interconnectedness of independent variables (e.g., UV Fluence, respirator material) that require consideration when assessing UV light efficacy for disinfecting respirators. Through electron microscopy and Fourier-transform infrared (FTIR) spectroscopy, we characterized respirator filter layers and revealed that polymer type affects disinfection efficacy. Specifically, FFR layers made from polypropylene (PP) (hydrophobic in nature) resulted in higher disinfection efficiency than layers composed of polyethylene terephthalate (PET-P) (hygroscopic in nature). An analysis of elastic band materials on the respirators indicated that silicone rubber-based bands achieved higher disinfection efficiency than PET-P bands and have a woven, fabric-like texture. While there is a strong desire to repurpose respirators, through this work we demonstrated that the design of an appropriate UV system is essential and that only respirators meeting specific design criteria may be reasonable for repurposing via UV disinfection.

scholarly journals UV Sterilization of Personal Protective Equipment with Idle Laboratory Biosafety Cabinets During the COVID-19 Pandemic

2020 ◽  
Author(s):  
◽  
Kyle J. Card ◽  
Dena Crozier ◽  
Andrew Dhawan ◽  
Mina N. Dinh ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Personal Protective Equipment ◽  
Cleveland Clinic ◽  
The United States ◽  
Alternative Methods ◽  
Common Element ◽  
Protective Equipment ◽  
Surgical Masks ◽  
N95 Respirators ◽  
Uv C

ABSTRACTDISCLAIMERThis article does not represent the official recommendation of the Cleveland Clinic or Case Western Reserve University School of Medicine, nor has it yet been peer reviewed. We are releasing it early, pre-peer review, to allow for quick dissemination/vetting by the scientific/clinical community given the necessity for rapid conservation of personal protective equipment (PPE) during this dire global situation. We welcome feedback from the community.Personal protective equipment (PPE), including face shields, surgical masks, and N95 respirators, is crucially important to the safety of both patients and medical personnel, particularly in the event of an infectious pandemic. As the incidence of Coronavirus Disease (COVID-19) increases exponentially in the United States and worldwide, healthcare provider demand for these necessities is currently outpacing supply. As such, strategies to extend the lifespan of the supply of medical equipment as safely as possible are critically important. In the midst of the current pandemic, there has been a concerted effort to identify viable ways to conserve PPE, including decontamination after use. Some hospitals have already begun using UV-C light to decontaminate N95 respirators and other PPE, but many lack the space or equipment to implement existing protocols. In this study, we outline a procedure by which PPE may be decontaminated using ultraviolet (UV) radiation in biosafety cabinets (BSCs), a common element of many academic, public health, and hospital laboratories, and discuss the dose ranges needed for effective decontamination of critical PPE. We further discuss obstacles to this approach including the possibility that the UV radiation levels vary within BSCs. Effective decontamination of N95 respirator masks or surgical masks requires UV-C doses of greater than 1 Jcm−2, which would take a minimum of 4.3 hours per side when placing the N95 at the bottom of the BSCs tested in this study. Elevating the N95 mask by 48 cm (so that it lies 19 cm from the top of the BSC) would enable the delivery of germicidal doses of UV-C in 62 minutes per side. Effective decontamination of face shields likely requires a much lower UV-C dose, and may be achieved by placing the face shields at the bottom of the BSC for 20 minutes per side. Our results are intended to provide support to healthcare organizations looking for alternative methods to extend their reserves of PPE. We recognize that institutions will require robust quality control processes to guarantee the efficacy of any implemented decontamination protocol. We also recognize that in certain situations such institutional resources may not be available; while we subscribe to the general principle that some degree of decontamination is preferable to re-use without decontamination, we would strongly advise that in such cases at least some degree of on-site verification of UV dose delivery be performed.

Memetic Algorithm Image Enhancement for Preserving Mean Brightness Without Losing Image Features

2019 ◽  
Vol 19 (04) ◽  
pp. 1950020
Author(s):  
Mitra Montazeri
Keyword(s):  
Contrast Enhancement ◽  
Dynamic Range ◽  
Memetic Algorithm ◽  
Image Features ◽  
Image Contrast ◽  
Consumer Electronics ◽  
Major Step ◽  
Processing Application ◽  
Low Contrast ◽  
Image Contrast Enhancement

In the image processing application, contrast enhancement is a major step. Conventional contrast enhancement methods such as Histogram Equalization (HE) do not have satisfactory results on many different low contrast images and they also cannot automatically handle different images. These problems result in specifying parameters manually to produce high contrast images. In this paper, an automatic image contrast enhancement on Memetic algorithm (MA) is proposed. In this study, simple exploiter is proposed to improve the current image contrast. The proposed method accomplishes multi goals of preserving brightness, retaining the shape features of the original histogram and controlling excessive enhancement rate, suiting for applications of consumer electronics. Simulation results shows that in terms of visual assessment, peak signal-to-noise (PSNR) and Absolute Mean Brightness Error (AMBE) the proposed method is better than the literature methods. It improves natural looking images specifically in images with high dynamic range and the output images were applicable for products of consumer electronic.

scholarly journals A Fast and Reliable Luma Control Scheme for High-Quality HDR/WCG Video

2018 ◽  
Vol 8 (10) ◽  
pp. 1975 ◽  
Author(s):  
Tae-Young Kim ◽  
Yong-Goo Kim
Keyword(s):  
Dynamic Range ◽  
Sampling Rate ◽  
Optimal Solution ◽  
High Dynamic Range ◽  
Consumer Electronics ◽  
Processing Unit ◽  
Fixed Amount ◽  
Control Scheme ◽  
Wide Color Gamut ◽  
Rate Conversion

The evolution of display technologies makes high dynamic range/wide color gamut (HDR/WCG) media of great interest in various applications including cinema, TV, blue-ray titles, and others. However, the HDR/WCG media format for consumer electronics requires the sampling rate conversion of chroma signals, resulting in a quality problem on the luminance perception of media, even without compression. In order to reduce such luminance perception problems, this paper proposes a fast and reliable luma control scheme which takes advantage of the bounds on the best luma value derived from the solution based on truncated Taylor series. Simulations performed for an extensive comparison study demonstrate that the proposed algorithm significantly outperforms the previous representative fast luma control schemes, resulting in almost the same quality of the iterative optimal solution with a fixed amount of computations per processing unit.

Fundamental Design Issues for Supplemental Damping Applications

1993 ◽  
Vol 9 (3) ◽  
pp. 627-636 ◽  
Author(s):  
Roger Scholl
Keyword(s):  
Cost Benefit ◽  
Earthquake Response ◽  
Critical Design ◽  
Design Considerations ◽  
Significant Damage ◽  
Frame Buildings ◽  
Structural Engineer ◽  
Supplemental Damping ◽  
Frame Member ◽  
Mode Response

In considering supplemental damping for a project, immediate questions that the structural engineer must address are: 1) Is the building suitable for supplemental damping; 2) How much damping should be provided; and 3) How should the dampers be distributed in the building? These are issues that need to be resolved irrespective of the type of damper used. The evaluation in this paper shows that supplemental damping is ideally suited for flexible frame buildings, or buildings detailed to accommodate interstory drift ratios of about 0.01 without significant damage. Providing 10% to 20% supplemental damping reduces response significantly for most structures. Providing more damping is difficult to justify from a cost-benefit perspective. Providing less supplemental damping can reduce earthquake response for structures having only small amounts of inherent damping; e.g., 1% to 2%. For most buildings having predominant fundamental mode response, the distribution of dampers in a structure is determined mostly from designing to carry the damper lateral forces. Frame member stresses, plan stiffness regularity, and elevation stiffness regularity are critical design considerations for establishing damper distributions in buildings.

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