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1.
J Am Med Dir Assoc ; 2023 Jun 08.
Article in English | MEDLINE | ID: covidwho-20237531

ABSTRACT

OBJECTIVES: Improving indoor air quality is one potential strategy to reduce the transmission of SARS-CoV-2 in any setting, including nursing homes, where staff and residents have been disproportionately and negatively affected by the COVID-19 pandemic. DESIGN: Single group interrupted time series. SETTING AND PARTICIPANTS: A total of 81 nursing homes in a multifacility corporation in Florida, Georgia, North Carolina, and South Carolina that installed ultraviolet air purification in their existing heating, ventilation, and air conditioning systems between July 27, 2020,k and September 10, 2020. METHODS: We linked data on the date ultraviolet air purification systems were installed with the Nursing Home COVID-19 Public Health File (weekly data reported by nursing homes on the number of residents with COVID-19 and COVID-19 deaths), public data on data on nursing home characteristics, county-level COVID-19 cases/deaths, and outside air temperature. We used an interrupted time series design and ordinary least squares regression to compare trends in weekly COVID-19 cases and deaths before and after installation of ultraviolet air purification systems. We controlled for county-level COVID-19 cases, death, and heat index. RESULTS: Compared with pre-installation, weekly COVID-19 cases per 1000 residents (-1.69; 95% CI, -4.32 to 0.95) and the weekly probability of reporting any COVID-19 case (-0.02; 95% CI, -0.04 to 0.00) declined in the post-installation period. We did not find any difference pre- and post-installation in COVID-19-related mortality (0.00; 95% CI, -0.01 to 0.02). CONCLUSIONS AND IMPLICATIONS: Our findings from this small number of nursing homes in the southern United States demonstrate the potential benefits of air purification in nursing homes on COVID-19 outcomes. Intervening on air quality may have a wide impact without placing significant burden on individuals to modify their behavior. We recommend a stronger, experimental design to estimate the causal effect of installing air purification devices on improving COVID-19 outcomes in nursing homes.

2.
National Journal of Clinical Anatomy ; 10(1):1-4, 2021.
Article in English | EMBASE | ID: covidwho-20241556
3.
Avances en Odontoestomatologia ; 39(1):42-48, 2023.
Article in Spanish | EMBASE | ID: covidwho-20234681

ABSTRACT

The oral cavity houses a large number of microorganisms that are potential pathogens, such as cytome-galovirus, hepatitis B virus (HBV), hepatitis C virus, herpes simplex virus types 1 and 2, human immuno-deficiency virus, mycobacterium tuberculosis and currently with the appearance of the SARS COV-2 that causes covid-19, the dental community must take stricter measures in its protection protocols against diseases. To evaluate its germicidal efficacy, ultraviolet light was applied with different exposure times on the alginate dental impressions, immediately after having taken the impression, which when it came into contact with the oral cavity of the patient is contaminated. As a result, a decrease in size and quantity of the bacterial colonies was observed in most of the samples in which the UV LED light was applied at 10 and 15 minutes of exposure. Some samples showed less bacterial growth even after 5 minutes of exposure. All this confirms its germicidal capacity thanks to its 245 nm ultraviolet spectrum that affects the DNA and RNA chain of microorganisms since it is the wavelength of maximum absorption of its molecule, eliminating its reproductive and survival capacity. The advantages it offers such as its small size, easy to handle and install, that it does not require constant maintenance, low acquisition cost;its constant high intensity light that does not generate any increase in temperature, makes it an excellent disinfectant auxiliary that can be incorporated into dental clinics.Copyright © 2023, Ediciones Avances S.L.. All rights reserved.

4.
Bioengineering (Basel) ; 10(5)2023 Apr 26.
Article in English | MEDLINE | ID: covidwho-20231195

ABSTRACT

The use of ultraviolet fluorescence markers in medical simulations has become popular in recent years, especially during the COVID-19 pandemic. Healthcare workers use ultraviolet fluorescence markers to replace pathogens or secretions, and then calculate the regions of contamination. Health providers can use bioimage processing software to calculate the area and quantity of fluorescent dyes. However, traditional image processing software has its limitations and lacks real-time capabilities, making it more suitable for laboratory use than for clinical settings. In this study, mobile phones were used to measure areas contaminated during medical treatment. During the research process, a mobile phone camera was used to photograph the contaminated regions at an orthogonal angle. The fluorescence marker-contaminated area and photographed image area were proportionally related. The areas of contaminated regions can be calculated using this relationship. We used Android Studio software to write a mobile application to convert photos and recreate the true contaminated area. In this application, color photographs are converted into grayscale, and then into black and white binary photographs using binarization. After this process, the fluorescence-contaminated area is calculated easily. The results of our study showed that within a limited distance (50-100 cm) and with controlled ambient light, the error in the calculated contamination area was 6%. This study provides a low-cost, easy, and ready-to-use tool for healthcare workers to estimate the area of fluorescent dye regions during medical simulations. This tool can promote medical education and training on infectious disease preparation.

5.
Aims Microbiology ; 9(3):431-443, 2023.
Article in English | Web of Science | ID: covidwho-20231397

ABSTRACT

To minimize health risks, surrogates are often employed to reduce experiments with pathogenic microorganisms and the associated health risk. Due to structural similarities between the enveloped RNA -viruses SARS-CoV-2 and Phi6, the latter has been established as a nonpathogenic coronavirus surrogate for many applications. However, large discrepancies in the UV log-reduction doses between SARS-CoV-2 and Phi6 necessitate the search for a better surrogate for UV inactivation applications. A literature study provided the bacteriophage PhiX174 as a potentially more suitable nonpathogenic coronavirus surrogate candidate. In irradiation experiments, the sensitivity of PhiX174 was investigated upon exposure to UV radiation of wavelengths 222 nm (Far-UVC), 254 nm (UVC), 302 nm (broad-band UVB), 311 nm (narrow-band UVB) and 366 nm (UVA) using a plaque assay. The determined log-reduction doses for PhiX174 were 1.3 mJ/cm2 @ 222 nm, 5 mJ/cm2 @ 254 nm, 17.9 mJ/cm2 @ 302 nm, 625 mJ/cm2 @ 311 nm and 42.5 J/cm2 @ 366 nm. The comparison of these results with published log-reduction doses of SARS-CoV-2 in the same spectral region, led to the conclusion that the bacteriophage PhiX174 exhibits larger log-reduction doses than SARS-CoV-2, nevertheless, it is a better UV-surrogate at 222 nm (Far-UVC), 254 nm (UVC) and 302 nm (UVB) than the often applied Phi6.

6.
2022 Ieee 19th India Council International Conference, Indicon ; 2022.
Article in English | Web of Science | ID: covidwho-20231368

ABSTRACT

Sterilization of hospitals is one of the major concerns when it comes to hygiene and cleanliness especially during a pandemic situation. The existing methodologies include ultraviolet disinfection or hydrochloride spraying for sterilizing hospital rooms and chemical treatment for surgical and medical equipment. However since COVID strains are developing at a rapid rate, it is necessary for more efficacy and accuracy in sterilization. According to the August 2021 census collected by NCBI, 87 percent of virus transmission is only because of improper sterilization. The following paper proposes efficient and proven ultrasonic sterilization methods that can be preferred to ultraviolet and chemical sterilization in sterilizing not only hospital rooms but also any crowded regions like malls and schools. The Cremant's formula helps in determining the appropriate and effective sterilization ultrasonic frequency level. Using machine learning algorithms, the approximate location, and the number of droplets per second present in the room will be calculated and treated with ultrasonic waves. This demonstration is proved using micro silicon balls which are similar in properties of COVID - 19 viruses. Simulation results are displayed to show the working of the same.

7.
Nanotechnology ; 34(33)2023 Jun 01.
Article in English | MEDLINE | ID: covidwho-2323424

ABSTRACT

The temperature-dependent external quantum efficiency (EQE) droops of 265 nm, 275 nm, 280 nm, and 285 nm AlGaN-based ultraviolet-c light-emitting diodes (UVC-LEDs) differed in Al contents have been comprehensively investigated. The modifiedABCmodel (R = An+Bn2+Cn3) with the current-leakage related term,f(n)= Dn4, has been employed to analyze the recombination mechanisms in these UVC-LED samples. Experimental results reveal that, at relatively low electrical-current levels, the contribution of Shockley-Read-Hall (SRH) recombination exceeds those of the Auger recombination and carrier leakage. At relatively high electrical-current levels, the Auger recombination and carrier leakage jointly dominate the EQE droop phenomenon. Moreover, the inactivation efficiencies of 222 nm excimer lamp, 254 nm portable Mercury lamp, 265 nm, 280 nm, and 285 nm UVC-LED arrays in the inactivation ofEscherichia colihave been experimentally investigated, which could provide a technical reference for fighting against the new COVID-19.

8.
International Journal of Infectious Diseases ; 130:S104-S104, 2023.
Article in English | Academic Search Complete | ID: covidwho-2324510

ABSTRACT

COVID-19 pandemic affected the entire globe and resulted in millions of deaths. Besides human-to-human respiratory droplets transmission, contact with aerosol-infected surfaces is an important way of transmitting this virus. The virus can be detected on many surfaces for a long time, in aerosols for at least 3 hours, and on plastic surfaces for up to 72 hours. Hence, it is crucial to determine how to disinfect the environment. Several biocidal agents have been used to clean the environment. Apart from biocidal agents, ultraviolet (UV) irradiation had also been used for environmental disinfection. However, there are several UV sources and systems with different wavelengths were used for disinfection and there was a wide range of effectiveness in disinfection with different modules. Thus, it was necessary to comprehensively review the current understanding of UV light used in disinfection to advise regarding UV light for environmental disinfection. Using the keywords COVID-19, UV light, and disinfection from 2020 to 2022, we searched various databases for articles online. We found various devices that had been studied for disinfection of SARS-CoV-2 with UV, such as monochromatic UV-C lamps, UV-LED light, broad- spectrum UV light devices, and excimer lamps. As a monochromatic UV source, different types of lamps were reported to have an excellent effect on disinfection, with the most common wavelength used for disinfection being 254 nm. As a broad-spectrum wavelength light, which is from 200 to 280 nm, one- minute exposure is enough to cause a 3 log10 reduction of viral load, which means 99.97% in disinfection. UV light are effective in coronavirus disinfection. Compared with the chemical agent, it is more environmentally friendly. To apply the UV light to environmental disinfection, five minutes is enough to reach 99.99% disinfection of the SARS-CoV-2 virus, for broad-spectrum wavelength light placed within one meter from the target surface. [ FROM AUTHOR] Copyright of International Journal of Infectious Diseases is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

9.
17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022 ; 2022.
Article in English | Scopus | ID: covidwho-2323618

ABSTRACT

Microbial contamination of indoor air in public spaces plays an important role in the SARSCoV-2 pandemic. So far, most studies on the reduction of airborne microbial load by UVC irradiation have been conducted as simulations or in laboratory environments. The aim of our study is to demonstrate the efficiency of Upper-Room Ultraviolet Germicidal Irradiation (UVGI) in a real environment like a supermarket. Restrictions on the use of harmful SARSCoV-2 particles for testing in public areas could be circumvented by using airborne germs as indicators. The results of this study show significant germ (bacterial and fungal) reductions by use of UVGI during business hours in a supermarket. Referring to known susceptibility values of airborne germs from previous work, we were able to estimate the effectiveness of the UVGI-system used against corona viruses. It met the requirements for complete disinfection. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

10.
Recent Advancement of IoT Devices in Pollution Control and Health Applications ; : 127-152, 2023.
Article in English | Scopus | ID: covidwho-2323183

ABSTRACT

With the rise of the COVID-19 pandemic across the globe, people have come to understand the requirement of sanitation. However, other than the personal hygiene, sanitization of all the appliances (like mobile phone, wristwatch, wallet, eye wear, etc.) has become very important. Therefore, the requirement of germicides is being increased to sanitize all the appliances. A few germicides comprise chemical sanitization mechanisms and others devices are based on high radiant UV (ultraviolet) light. From the available literature, UV-based germicides are more efficient and effective in killing the harmful microorganisms. However, in the existing system the rate of disinfection is less, which makes this system lag. In general, the UV-based germicides use UV rays for the sanitization process. The UV rays are one of the forms of electromagnetic radiation with the wave lengths from 10 to 400nm. Typically, there are three types of UV rays, viz., ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC) Moreover, UVA are longer waves, used as a black light through which microorganisms may be noticeable, while UVC are the shorter waves that kill the harmful microorganisms directly by destructing their DNA. Further, we have developed a germicidal system with greater rate of disinfection that is comparatively faster than the existing system, and it also includes the sanitization of our working environment too to disinfect the airborne organisms with greater accuracy. In the present invention, an IoT device that provides surface sanitization through microcontroller-based UV germicide is developed to reduce the disinfection time and air sterilization as well. © 2023 Elsevier Ltd. All rights reserved.

11.
17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022 ; 2022.
Article in English | Scopus | ID: covidwho-2327441

ABSTRACT

This study investigated upper-room germicidal ultraviolet (UR-GUV) light application in a music rehearsal room with a high ceiling (7.5 m). The focus was on the influences of the elevation and height of UV zone on disinfection of airborne viruses. This study assumed a uniform UV fluence rate of 0.2 W/m2 in the UV irradiation zone. According to the Computational Fluid Dynamics (CFD) results, average viral concentrations (Ca), fraction remaining (FR), and equivalent air exchange rate (λe) attributed to GUV, have power relationships with UV zone height. Ca and FR decreased with UV zone height, while λe did the opposite. UV zone elevation showed little influence on UR-GUV performance, indicating well-mixed air in the rehearsal room. High ceiling makes it possible to achieve adequate UV dose by increasing both UV zone height and UV light intensity. Using open fixtures improved energy efficiency and reduced operational costs of the UR-GUV system. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

12.
J Chromatogr A ; 1702: 464098, 2023 Aug 02.
Article in English | MEDLINE | ID: covidwho-2323006

ABSTRACT

The antiviral oral liquid (AOL) was an antiviral drug currently in clinical trials against coronavirus disease 2019. This study aimed to improve its quality consistency evaluation method using fingerprint techniques from several aspects. First, the five-wavelength matched average fusion fingerprint (FMAFFP) for HPLC, electrochemical fingerprint (ECFP), and ultraviolet spectral quantum fingerprint (UVFP) was established for 22 samples, respectively. Their quality was then assessed using the average linear quantitative fingerprint method, and 22 samples were classified into eight quality grades. OPLS and PCA were then used further to explore the characteristic parameters of these three fingerprints. Five compounds were quantified simultaneously for the first time, and then the relationship between the average linear quantitative similarity (PL) and the sum of the five quantitative components (P5c) was investigated. A linear correlation (r ≥ 0.9735) between PL and P5c suggested that PL may be used to predict chemical content. Finally, to investigate the antioxidant potential of the AOL, correlation analyses were performed for FMAFFP peaks-PEC and UVFP peaks-PEC, respectively, where the PEC value was defined as the quantitative similarity of ECFP. The Pearson correlation coefficient and gray correlation analysis were consistent, allowing us to initially explore the antioxidant capacity of the unidentified components of the samples. This study researched AOL using multidimensional fingerprints to provide a comprehensive and reliable method for quality consistency control of herbal compound preparations.


Subject(s)
COVID-19 , Drugs, Chinese Herbal , Humans , Drugs, Chinese Herbal/chemistry , Chromatography, High Pressure Liquid/methods , Antiviral Agents , Antioxidants/analysis
13.
Environ Res ; 231(Pt 1): 116088, 2023 Aug 15.
Article in English | MEDLINE | ID: covidwho-2320339

ABSTRACT

BACKGROUND: Evidence is limited regarding the association between meteorological factors and COVID-19 transmission in low- and middle-income countries (LMICs). OBJECTIVE: To investigate the independent and interactive effects of temperature, relative humidity (RH), and ultraviolet (UV) radiation on the spread of COVID-19 in LMICs. METHODS: We collected daily data on COVID-19 confirmed cases, meteorological factors and non-pharmaceutical interventions (NPIs) in 2143 city- and district-level sites from 6 LMICs during 2020. We applied a time-stratified case-crossover design with distributed lag nonlinear model to evaluate the independent and interactive effects of meteorological factors on COVID-19 transmission after controlling NPIs. We generated an overall estimate through pooling site-specific relative risks (RR) using a multivariate meta-regression model. RESULTS: There was a positive, non-linear, association between temperature and COVID-19 confirmed cases in all study sites, while RH and UV showed negative non-linear associations. RR of the 90th percentile temperature (28.1 °C) was 1.14 [95% confidence interval (CI): 1.02, 1.28] compared with the 50th percentile temperature (24.4 °C). RR of the10th percentile UV was 1.41 (95% CI: 1.29, 1.54). High temperature and high RH were associated with increased risks in temperate climate but decreased risks in tropical climate, while UV exhibited a consistent, negative association across climate zones. Temperature, RH, and UV interacted to affect COVID-19 transmission. Temperature and RH also showed higher risks in low NPIs sites. CONCLUSION: Temperature, RH, and UV appeared to independently and interactively affect the transmission of COVID-19 in LMICs but such associations varied with climate zones. Our results suggest that more attention should be paid to meteorological variation when the transmission of COVID-19 is still rampant in LMICs.


Subject(s)
COVID-19 , Humans , COVID-19/epidemiology , Cross-Over Studies , Developing Countries , Temperature , Meteorological Concepts , Humidity , Tropical Climate , China
14.
British Medical Bulletin ; 144(1):1-2, 2022.
Article in English | EMBASE | ID: covidwho-2320171
15.
South African Gastroenterology Review ; 20(1):6-8, 2022.
Article in English | EMBASE | ID: covidwho-2317500
16.
Transplantation and Cellular Therapy ; 29(2 Supplement):S143, 2023.
Article in English | EMBASE | ID: covidwho-2316751

ABSTRACT

Background: Crystalloid fluid administration has traditionally played an important role in prevention of hemorrhagic cystitis with high dose cyclophosphamide. Cryopreservation of stem cells in the era of the COVID pandemic has further led to an increase in crystalloid use. Excess fluid administration over a short duration could lead to volume overload, respiratory failure and impact overall survival. Method(s): A retrospective chart review was conducted on patients receiving PtCy following Haplo SCT at UVA Medical Center from September 2016 through August 2022. Internal BMT quality audit in June 2021 identified increased rate of ICU transfers and respiratory failure amongst patient receiving PtCy due to fluid overload. Hence our PtCy hydration was reduced, with IV fluid administration decreasing from 200 mL/ hr over 62 hours to 100 mL/hr over 12 hours. Urine output parameters placed to administer Cytoxan were also removed. We present our quality improvement project demonstrating outcomes pre and post intervention. Result(s): All demographic patient and transplant-related data was collected during the period of hospitalization for Haplo SCT [Table 1]. Pre-intervention spanned 9/2016-8/2021. Our analysis identified higher than expected rates of respiratory (Table Presented) failure prompting intervention on 8/2021. Post-intervention spanned 8/2021-8/2022. Pre-intervention, 45% of patients receiving Haplo SCT developed respiratory failure (defined as a new hypoxia) in the 30 day post-transplant period. Of these, 93% had volume overload. Mechanical ventilation was required in 21%. Complication rates included ICU transfer - 30%, AKI - 39%, and renal replacement therapy - 18%. Three percent (1 pt) developed hemorrhagic cystitis requiring bladder irrigation. Median LOS was 31.0 days. Post-intervention, average IV crystalloid received was reduced by about 15L. Median diuretic use reduced by 40%. No instances of respiratory failure, mechanical ventilation, ICU transfer, AKI or renal replacement therapy occurred in this group. Median LOS was 26.5 days. There were no cases of hemorrhagic cystitis. Please refer Figure 1. (Figure Presented) (Figure Presented) Conclusion(s): This single center quality improvement initiative shows that reducing IV crystalloid administration with PtCy is associated with a reduction in respiratory failure and other adverse clinical outcomes, without observed increase in hemorrhagic cystitis. Larger multi-center studies are needed to validate this finding.Copyright © 2023 American Society for Transplantation and Cellular Therapy

17.
Acta Physica Sinica ; 72(4), 2023.
Article in English | Web of Science | ID: covidwho-2309530

ABSTRACT

AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) are widely used in sterilization, sensing,water purification, medical treatment, non-line of sight (NLOS) communication and many other fields.Especially it has been reported that the global novel coronavirus (COVID-19) can be effectively inactivated bythe DUV light with a wavelength below 280 nm (UVC) within a few seconds, which has also attracted greatattention. However, the external quantum efficiency (EQE) of UVC LED is still at a low level, generally notmore than 10%. As an important component of EQE, internal quantum efficiency (IQE) plays a crucial role inrealizing high-performance DUV-LED. In order to improve the IQE of AlGaN-based DUV-LED, this workadopts an electron blocking layer (EBL) structure based on InAlGaN/AlGaN superlattice. The results showthat the superlattice EBL structure can effectively improve the IQE compared with the traditional single-layerand double-layer EBL structure for the DUV-LED. On this basis, the optimization method based on JAYAintelligent algorithm for LED structure design is proposed in this work. Using the proposed design method, theInAlGaN/AlGaN superlattice EBL structure is further optimized to maximize the LED' s IQE. It isdemonstrated that the optimized superlattice EBL structure is beneficial to not only the suppression of electronleakage but also the improvement of hole injection, leading to the increase of carrier recombination in the activeregion. As a result, the IQE of the DUV-LED at 200 mA injection current is 41.2% higher than that of thesingle-layer EBL structure. In addition, the optimized structure reduces IQE at high current from 25% to 4%.The optimization method based on intelligent algorithm can break through the limitation of the current LEDstructure design and provide a new method to improve the efficiency of AlGaN-based DUV-LED.

18.
J Environ Chem Eng ; 11(3): 110040, 2023 Jun.
Article in English | MEDLINE | ID: covidwho-2309988

ABSTRACT

Microplasma UV lamps have recently emerged as viable excimer-based sources of UV radiation, garnering significant attention during the recent COVID-19 pandemic for their use in disinfection applications because of their ability to emit human-safe far-UVC (200-240 nm) spectrums. An accurate model to simulate the radiation profile of microplasma UV lamps is of paramount importance to develop efficient microplasma lamp-implemented systems. We developed a 3D numerical model of microplasma UV lamps using the ray optics method. The simulation results for lamp irradiance and fluence rate were experimentally validated with standard optical radiometry and actinometry measurements, respectively. To improve the optical efficiency of microplasma lamps, an in-depth analysis of radiation behavior inside the standard commercially available lamp was performed using the geometrical optics method, and several potential scenarios were explored. A 2D modeling of an individual microcavity indicated that the current common lamp design can be significantly improved by preventing radiation loss, and small modifications in optical design can greatly increase the energy performance of the system. Based on the findings of this study, several virtual design concepts were proposed, and their performances were numerically compared with that of the original design of commercial microplasma lamps. The developed model can potentially be integrated with hydrodynamic and kinetic models for the virtual prototyping of complex photoreactors operating with UV microplasma lamps.

19.
Polymers (Basel) ; 15(8)2023 Apr 21.
Article in English | MEDLINE | ID: covidwho-2291212

ABSTRACT

During the initial stages of the COVID-19 pandemic, healthcare facilities experienced severe shortages of personal protective equipment (PPE) and other medical supplies. Employing 3D printing to rapidly fabricate functional parts and equipment was one of the emergency solutions used to tackle these shortages. Using ultraviolet light in the UV-C band (wavelengths of 200 nm to 280 nm) might prove useful in sterilizing 3D printed parts, enabling their reusability. Most polymers, however, degrade under UV-C radiation, so it becomes necessary to determine what 3D printing materials can withstand the conditions found during medical equipment sterilization with UV-C. This paper analyzes the effect of accelerated aging through prolonged exposure to UV-C on the mechanical properties of parts 3D printed from a polycarbonate and acrylonitrile butadiene styrene polymer (ABS-PC). Samples 3D printed using a material extrusion process (MEX) went through a 24-h UV-C exposure aging cycle and then were tested versus a control group for changes in tensile strength, compressive strength and some selected material creep characteristics. Testing showed minimal mechanical property degradation following the irradiation procedure, with tensile strength being statistically the same for irradiated parts as those in the control group. Irradiated parts showed small losses in stiffness (5.2%) and compressive strength (6.5%). Scanning electron microscopy (SEM) was employed in order to assess if any changes occurred in the material structure.

20.
19th China International Forum on Solid State Lighting and 8th International Forum on Wide Bandgap Semiconductors, SSLCHINA: IFWS 2022 ; : 228-230, 2023.
Article in English | Scopus | ID: covidwho-2306504

ABSTRACT

Recent studies in the epidermis have shown that Far-UVC (200-230nm) is a promising candidate against Novel Coronavirus (SARS-Cov-2) with little DNA damage. Due to the consideration that conventional Far-UVC KrCl excilamps may emit 200-230 nm radiation (typically 222-nm peak wavelength) but with some harmful UV radiation beyond 230 to 280 nm, a novel design of Far-UVC KrCl excilamps with the filter and reflector is introduced to reduce the harmful UV radiation from 10.9% to 2.5% at the cost of 30%~40% reduction in the total irradiance. In our study, the radiant characteristics and service life of the novel Far-UVC KrCl excilamps of 40~75 Watt (electrical power) with 222-nm peak wavelength were investigated. The service life was assessed under aging at the ambient temperatures (Ta) of 25 and 85 for 500 hours, respectively. The results showed that both the ambient temperature and the root mean square of current (Irms) into the excilamps have a substantial effect on the lifetime of the KrCl excilamps. Furthermore, although no significant change of the off-nominal emission ratio existed during the lifetime test, it was observed that the high ambient temperature has a negative effect on the filtering of the harmful radiation. © 2023 IEEE.

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