Ultraviolet Devices Research Articles

Novel two-dimensional CS semiconductor with tunable fantastic electronic and optical properties

First-principles calculations are addressed to study the stability, electronic and optical properties of the CS monolayer. It's found that the CS monolayer has excellent stability and semiconductor characteristics (Indirect band gap of 2.09 eV). Through applying external biaxial strain (−4%∼+4 %), the value of the indirect band gap of the CS monolayer is tuned in a wide interval (0.18–2.86 eV). The electronic and optical properties of the CS monolayer are also regulated by chemical modifications, exhibiting rich changing behaviors. Interestingly, the fully hydrogenated CS monolayer exhibits a wide direct band gap (3.61 eV), while the semi-hydrogenated CS monolayer exhibits an indirect band gap (3.11 eV), both have good stabilities. The absorption spectrum of the CS monolayer is found to have strong absorption in green light (528 nm) and ultraviolet light. While those of the chemically modified CS monolayers show strong absorption strength in violet and medium ultraviolet light, showing potential application in ultraviolet devices.

Degradation of reactive red (B-3BF) dye wastewater using UV irradiation (254/185 nm) with sodium persulfate in a pilot UV device

Two low-pressure ultraviolet (UV) lamps at 185/254 nm with sodium persulfate in a pilot UV device were utilized for the degradation of reactive red (B-3BF) dye wastewater compared with two UV lamps at 185/185 nm and two UV lamps at 254/254 nm. The degradation performances of UV irradiation (254/185 nm) with sodium persulfate under different degradation times, flow rates, initial pH, initial Na2S2O8 concentrations and initial dye concentrations were investigated. The experimental results illustrated that the degradation percentage of B-3BF dye could reduce to 90.42% with the energy consumption of 85.1 kWh/kg and the residual dye concentration of 1.92 mg/L by UV irradiation (254/185 nm) with initial Na2S2O8 concentration of 1.5 mmol/L and initial dye concentration of 20 mg/L. In addition, degradation performance of B-3BF dye wastewater by UV irradiation (254/185 nm) with sodium persulfate was more effective than those of UV irradiation (254/254 nm) and UV irradiation (185/185 nm). Therefore UV irradiation (254/185 nm) with sodium persulfate was promising for the degradation of B-3BF dye wastewater.

Self-Powered UV Photodetector Construction of the P(EDOS-TTh) Copolymer-Modified ZnO Nanoarray.

To solve the problem that zinc oxide nanorods (ZnO NRs)-based self-powered ultraviolet (UV) photodetectors cannot obtain both higher responsiveness and shorter response time, P(EDOS-TTh) was prepared using 3,4-ethylenedioxyselenphene (EDOS) and terthiophene (TTh) as copolymers, which modify the ZnO NRs surface, and the ZnO/P(EDOS-TTh) P-N junction self-powered UV device is assembled. The effect of the number of electrochemical polymerization cycles on the UV photodetection performance of ZnO/P(EDOS-TTh) P-N heterojunction was studied by adjusting the number of electrochemical polymerization cycles at the monomer molar ratio of 1:1. Benefiting from the enhanced built-in electric field of the ZnO/P(EDOS-TTh) interface, balancing photogenerated carriers, and charge separation and transport. The results show that the contact between N-type ZnO NRs and P-type P(EDOS-TTh) is best when the number of polymerization cycles is 3, due to the fact that EDOS-TTh and ZnO NRs form excellent P-N heterojunctions with strong internal electric fields, and the devices show good pyroelectric effect and UV photodetection performance. Under 0 V bias and 0.32 mW/cm2 UV irradiation, the responsivity (R) of ZnO/P(EDOS-TTh) reaches 3.31 mA/W, the detectivity (D*) is 7.25 × 1010 Jones, and the response time is significantly shortened. The rise time is 0.086 s, which exhibited excellent photoelectric properties and stability. UV photodetection performance with high sensitivity and fast response time is achieved.

Preparation of ZnGa2O4-based deep ultraviolet photodetector with high photodetectivity by magnetron sputtering

Ultra-wide bandgap semiconductors are frequently utilized materials in the fabrication of deep ultraviolet photodetectors (DUVPDs). However, it is imperative to enhance both the photoresponsivity and response speed of these detectors. Herein, we deposited high-quality (111)-oriented ZnGa2O4 films with a bandgap of approximately 4.75 eV onto c-plane sapphire (0001) substrates using magnetron sputtering. Our findings illuminate the pivotal role of pressure in shaping their structural properties, chemical compositions, and photoelectric characteristics. Importantly, DUVPDs based on ZnGa2O4 films exhibited a photo/dark current ratio of 1.46 × 104. Furthermore, we observed the highest responsivity to be 72.2 A/W, complemented by a photodetectivity of 4.21 × 1014 Jones, an external quantum efficiency of 4.04 × 104 %, and rise and decay times of 2.32 s and 0.055 s, respectively. This study underscores the commendable photoresponsivity and rapid response time of the ZnGa2O4 photodetector, positioning it as a compelling candidate for the advancement of deep ultraviolet devices.

Electronic transport and optical properties of five different phases (α, β, ε, δ and γ) of Ga2O3: A first-principles study

In the field of power and ultraviolet devices, Ga2O3 becomes an emerging semiconductor due to its large energy bandgap and suitable optical absorption wavelength at solar blind ultraviolet band. In this work, the electronic and optical properties of five Ga2O3 polymorphs are investigated by the first-principles calculations to study their potential in ultraviolet devices. The geometry structures, electronic structure, optical and electronic transport properties of five polymorphs have been investigated through GGA + U approach and deformation potential theory. Based on the deformation potential theory, the anisotropic electron mobility of five Ga2O3 polycrystals is obtained by analyzing the parameters obtained from the first-principles calculation. TCAD simulations using calculation results before show the spectral response of MSM solar-blind detectors based on five polymorphs, and indicating that ε-Ga2O3 is the best candidate material for solar blind UV detector. This work provides theoretical insights for the preparation of different phase gallium oxide materials and devices.

High‐Quality Nonpolar a‐Plane AlGaN Film Grown on Si‐Doped AlN Template by Metal Organic Chemical Vapor Deposition

High crystalline quality and flat a‐plane aluminum gallium nitride (AlGaN) films are obtained on Si‐doped AlN templates with a moderate silane (SiH4) flow rate by metal‐organic chemical vapor deposition (MOCVD). The effects of the SiH4 flow rate on the surface morphology, crystalline quality, stress state, and optical property of a‐plane AlN templates and AlGaN films are comprehensively investigated. As the SiH4 flow rate increases from 0 to 7.0 nmol min−1, the full width at half maximum of X‐ray rocking curve values along [0001]/[1–100] directions for the AlGaN films are monotonically reduced to 1124/1143 arcsec. Meanwhile, the surface root mean square roughness value is decreased to 0.88 nm. These achievements are attributed to the suppression of the anisotropy degrees and in‐plane stress of AlN templates. In addition, an excess SiH4 flow rate leads to deteriorated surface morphologies and increased basal plane stacking fault (BPSF) densities for both AlN and AlGaN films. This work suggests that doping AlN layers with an appropriate SiH4 flow rate is a promising route to obtain high‐quality a‐plane AlGaN films for efficient nonpolar deep ultraviolet (DUV) devices.

First principles study of the electronic structure, mechanical and optical properties of cubic perovskite NaCaCl3 under pressure

Based on the first-principles methods, the electronic, mechanical and optical properties of NaCaCl3 crystal were investigated under various pressures for the first time. At 0 GPa, the lattice constant and bulk modulus were calculated to be 5.278 Å and 27.011 GPa, respectively. Analysis of Poisson's ratio and Pugh's ratio indicated that NaCaCl3 exhibits ductile characteristics, which increases with the increasing pressure. Based on the crystal mechanical stability condition, the phase transition pressure of NaCaCl3 was calculated to be 5.12 GPa. The electronic property demonstrated that NaCaCl3 exhibits an indirect and wide band gap insulator (3.84 eV) at 0 GPa, and the band gap increases with the increasing pressure. The results of optical properties show that all spectrums of NaCaCl3 exhibit a blue shift when the pressure increases. The excellent ultraviolet absorption suggests that NaCaCl3 has a potential application in vacuum ultraviolet devices. And it is also suitable as transparent coating and window materials in the infrared and visible regions due to small reflectivity and absorption.

DGAT1 Gene Polymorphism in Morkaraman and Tushin

This study aims to investigate the polymorphism of the Diacylglycerol acyltransferase1 (DGAT1) gene locus in 105 Morkaraman and 65 Tushin lambs to determine the distribution of genotype and allele frequencies of lambs in terms of related genes. DGAT1/Alu1 gene polymorphism was defined by using the PCR-RFLP method in the DNAs isolated from hair samples taken from Morkaraman and Tushin lambs used in this study. PCR- RFLP products were run in an electrophoresis medium and the results were visualized on an ultraviolet (UV) transluminator. When the population was examined in terms of allele frequencies, it was defined that the C allele and the T allele were 0.72% and 0.28% for the Morkaraman, and 0.71% and 0.29% for Tushin, respectively. The CC, CT, and TT genotype frequencies of the DGAT1 gene in the population were found to be 53.3%, 38.1%, and 8.6% for the Morkaraman and 50.8%, 40.0%, and 9.2% for the Tushin, respectively. In the Hardy-Weinberg genetic equilibrium test, it was observed that the distribution of genotype frequencies was in balance (P>0.05) in the population. It has been defined that the genotype and allele frequencies determined in terms of DGAT1 gene polymorphism may be found to be sufficient to reveal the genotype diversity of the breeds. The genotype and allele frequencies determined in terms of DGAT1 gene polymorphism were sufficient to reveal the genotype diversity of the breed, the sheep with CC genotype are economically advantageous in the herd, and therefore DGAT1 gene can be used for marker-assisted selection (MAS).

High‐Efficiency Ultraviolet Electroluminescence from Multi‐Resonance Phosphine Oxide Polycyclic Aromatics

AbstractEfficient ultraviolet (UV) electroluminescent materials remain a great challenge, since short peak wavelength <400 nm and narrow full width at half maximum (FWHM) <50 nm are simultaneously required. In this sense, multi‐resonance (MR) thermally activated delayed fluorescence (TADF) emitters featuring narrow‐band emissions hold the promise for UV applications. Herein, a novel MR‐TADF skeleton featuring carbazole‐phosphine oxide (P=O) fused aromatics is developed to construct the first two UV MR emitters named CzP2PO and tBCzP2PO. In addition to synergistic resonance effects of P=O and N atom, sp3‐hybrid P atom renders the curved polycyclic planes of CzP2PO and tBCzP2PO, giving rise to their narrowband UV emissions with peak wavelengths <390 nm and FWHM<35 nm. Besides configuration quasi‐planarization for radiation enhancement and quenching suppression, P=O moiety further enhances singlet‐triplet coupling to facilitate reverse intersystem crossing, resulting in the state‐of‐the‐art photoluminescence quantum yield of 62 % in tBCzP2PO doped films. As consequence, tBCzP2PO endowed its UV organic light‐emitting diodes with the peak at 382 nm and FWHM of 32 nm, and especially the record‐high external quantum efficiency (EQE) of 15.1 % among all kinds of UV devices. Our results demonstrate great potential of P=O based MR emitters in practical applications including optoelectronics, biology and medicine science.

High-Efficiency Ultraviolet Electroluminescence from Multi-Resonance Phosphine Oxide Polycyclic Aromatics.

Efficient ultraviolet (UV) electroluminescent materials remain a great challenge, since short peak wavelength <400 nm and narrow full width at half maximum (FWHM) <50 nm are simultaneously required. In this sense, multi-resonance (MR) thermally activated delayed fluorescence (TADF) emitters featuring narrow-band emissions hold the promise for UV applications. Herein, a novel MR-TADF skeleton featuring carbazole-phosphine oxide (P=O) fused aromatics is developed to construct the first two UV MR emitters named CzP2PO and tBCzP2PO. In addition to synergistic resonance effects of P=O and N atom, sp3 -hybrid P atom renders the curved polycyclic planes of CzP2PO and tBCzP2PO, giving rise to their narrowband UV emissions with peak wavelengths <390 nm and FWHM<35 nm. Besides configuration quasi-planarization for radiation enhancement and quenching suppression, P=O moiety further enhances singlet-triplet coupling to facilitate reverse intersystem crossing, resulting in the state-of-the-art photoluminescence quantum yield of 62 % in tBCzP2PO doped films. As consequence, tBCzP2PO endowed its UV organic light-emitting diodes with the peak at 382 nm and FWHM of 32 nm, and especially the record-high external quantum efficiency (EQE) of 15.1 % among all kinds of UV devices. Our results demonstrate great potential of P=O based MR emitters in practical applications including optoelectronics, biology and medicine science.

Germicidal Efficiency of 272 nm LED in Relation to the Hospital Strain of Klebsiella Pneumoniae

Relevance. Currently, the use of ultraviolet (UV) radiation for the disinfection of objects and the treatment for infectious diseases is considered as a promising alternative to chemical biocides and antibiotics. Shortwave — UV-C and UV-B -light emitting diodes (LED) are a relatively new type of UV radiation sources and potentially able to meet the requirements of current medical technologies. However, their possibilities for the treatment of wounds and infectious diseases have not been practically researched to date, which determines the relevance of experiments aimed at studying the biocidal and therapeutic properties of shortwavelength UV LEDs.Purpose. OF STUDY To evaluate the bactericidal efficacy of 272 nm LED radiation against hospital strains of Klebsiella pneumoniae bacteria characterized by multidrug resistance.Materials and Methods. The studies were carried out with an experimental sample of the LED apparatus for UV irradiation. In the irradiator of the device, 5 LEDs are installed with a maximum radiation at a wavelength of 272 nm and a total electrical power of 10 watts. The UV radiation dose achieved in one irradiation session (12 seconds) at a distance of 10 cm from the irradiator was 8 mJ/cm2 . In the experiments, a hospital strain of the bacterium Klebsiella pneumoniae, isolated from the patient’s blood, was used. The strain was characterized by multidrug resistance. A daily culture suspension of K. pneumoniae with a concentration of 108 CFU/ml in a volume of 100 µl was transferred into a Petri dish with a diameter of 9 cm with meat-peptone agar and evenly distributed over a surface with a diameter of 8 cm. Petri dishes were irradiated from a distance of 10 cm from the irradiator. The change in the dose of UV irradiation from 4 to 80 mJ/cm2 was carried out by varying the exposure time. Studies were carried out in 4 repetitions at each dose. After irradiation, the experimental and control (without irradiation) Petri dishes were placed in a thermostat at 37ºC for 24 hours, then the grown colonies were counted. A total of 60 experiments were carried out.Results. As a result of the research, it was shown that the LED device based on five 272 nm diodes provides deep and prompt disinfection of the surface from hospital strains of K. pneumoniae bacteria characterized by multidrug resistance. A dose of UV radiation of 8 mJ/cm2 reduces surface contamination with K. pneumoniae bacteria by more than a million times (decontamination efficiency over 99.9999%). At doses less than 10 mJ/cm2 , the efficiency of the 272 nm LED device in terms of inactivation of K. pneumoniae bacteria is 3–4 times higher than the bactericidal efficiency of mercury lamps.Conclusion.The prospects of using UV devices based on LEDs with a maximum radiation at a wavelength of 272 nm in systems for the operational disinfection of massively contaminated surfaces, potentially including wound surfaces, have been shown.

Reduction of airborne and surface-borne bacteria in a medical center burn intensive care unit using active, upper-room, germicidal ultraviolet (GUV) disinfection.

To determine the effectiveness of active, upper-room, germicidal ultraviolet (GUV) devices in reducing bacterial contamination in patient rooms in air and on surfaces as a supplement to the central heating, ventilation, and air conditioning (HVAC) air handling unit (AHU) with MERV 14 filters and UV-C disinfection. This study was conducted in an academic medical center, burn intensive care unit (BICU), for 4 months in 2022. Room occupancy was monitored and recorded. In total, 402 preinstallation and postinstallation bacterial air and non-high-touch surface samples were obtained from 10 BICU patient rooms. Airborne particle counts were measured in the rooms, and bacterial air samples were obtained from the patient-room supply air vents and outdoor air, before and after the intervention. After preintervention samples were obtained, an active, upper-room, GUV air disinfection system was deployed in each of the patient rooms in the BICU. The average levels of airborne bacteria of 395 CFU/m3 before GUV device installation and 37 CFU/m3 after installation indicated an 89% overall decrease (P < .0001). Levels of surface-borne bacteria were associated with a 69% decrease (P < .0001) after GUV device installation. Outdoor levels of airborne bacteria averaged 341 CFU/m3 in March before installation and 676 CFU/m3 in June after installation, but this increase was not significant (P = .517). Significant reductions in air and surface contamination occurred in all rooms and areas and were not associated with variations in outdoor air concentrations of bacteria. The significant decrease of surface bacteria is an unexpected benefit associated with in-room GUV air disinfection, which can potentially reduce overall bioburden.

Toward Sustainable Ultrawide Bandgap van der Waals Materials: An ab initio Screening Effort

AbstractThe sustainable development of next‐generation device technology is paramount in the face of climate change and the looming energy crisis. Tremendous effort is made in the discovery and design of nanomaterials that achieve device‐level sustainability, where high performance and low operational energy cost are prioritized. However, many of such materials are composed of elements that are under threat of depletion and pose elevated risks to the environment and human health. The role of materials‐level sustainability in computational screening efforts is overlooked thus far. This work presents a general van der Waals materials screening framework imbued with sustainability‐motivated search criteria. Using ultrawide bandgap (UWBG) materials as a backdrop, 25 sustainable UWBG layered materials comprising only of low‐risks elements result from this screening effort, with several meeting the requirements for dielectric, power electronics, and ultraviolet device applications. These findings constitute a critical first‐step toward reinventing a more sustainable electronics landscape beyond silicon, with the framework established in this work serving as a harbinger of sustainable 2D materials discovery.

Influence of the postpolymerization type and time on the flexural strength and dimensional stability of 3D printed interim resins

Statement of problemThe mechanical strength of 3-dimensionally (3D) printed interim resins is unclear but influenced by printing parameters. Evidence regarding standardization of the postpolymerization type and time for 3D printed interim resins is sparse. PurposeThe purpose of this in vitro study was to evaluate the influence of postpolymerization type and time on flexural strength and dimensional stability of 3D printed resins for interim restorations. Material and methodsA total of 288 bars were 3D printed (Form 2; Formlabs, stereolithography—SLA, 50 µm, 30 degrees), (25×2×2 mm; International Organization for Standardization—ISO 4049:2019) abraded and randomly divided into 9 groups (n=30) according to postpolymerization (Ultraviolet device—UV; Microwave with water—MWA; Microwave without water—MW) and time (15, 20, and 30 minutes for UV; and 5, 8, and 10 minutes for MW and MWA). Each bar was then measured with digital calipers at 11 points for length, thickness, and width before and after postpolymerization to analyze dimensional stability. The flexural strength was then measured (σ; 980.6 N, 1 mm/minute) and the fractured surfaces were analyzed with scanning electron microscopy. The σ (MPa) data were evaluated by using a 2-way analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) pairwise comparisons test (α=.05). Dimensional stability data (mm) were analyzed by using the Kruskal-Wallis test and Dwass-Steel-Critchlow-Fligner multiple comparisons. The Weibull analysis was performed with σ data. ResultsThe 2-way ANOVA revealed that all factors and their interaction were significant for σ (P<.001). The UV groups presented the highest σ values, being statistically higher than all MW and MWA groups. The Weibull analysis revealed that postpolymerization UV groups found the highest values regarding the characteristic strength, although the MW 8-minute group (13.71) found the highest value for the Weibull modulus. Furthermore, the Kruskal-Wallis test revealed that only the postpolymerization factor was significant for dimensional stability (P<.001). The postpolymerization microwave groups found greater expansion variations at all times, with the MW 8-minute group (0.78 ±0.54) presenting the greatest variation in dimensional stability. ConclusionsUV was determined to be the most suitable type of postpolymerization for interim printed resin among the postpolymerization methods, regardless of the application time. The postpolymerization MW groups found greater variations in dimensional stability.

Single-dislocation ultraviolet light emission

Micro-nano ultraviolet light sources have recently attracted great attention due to their promising applications in future quantum display, photoelectric detection sensors, biomedical devices, and so on. Design of ultraviolet light sources with smaller size, stronger emission intensity, and higher integration, are the key aspects for the development of high-performance micro-nano ultraviolet devices. Here, we demonstrate that unidirectional threading dislocation arrays in an AlN thin film can emit ultraviolet light with wavelength of ∼ 317 nm. The density of AlN dislocations is ∼ 4 × 1010 cm−2, and the light emission intensity of AlN dislocations is comparable to the intrinsic emission of the AlN thin film. By combining aberration-corrected transmission electron microscopy, atomic-resolution valence electron energy-loss spectroscopy, and first-principles calculations, the atomic and electronic structures and the band gaps of the AlN threading dislocations are determined. It is found that the AlN threading dislocations are comprised of edge, screw, and mixed dislocations. All the AlN dislocations exhibit smaller band gaps compared to the AlN bulk due to the increase of the Al-N bond length at the dislocation cores. The dangling bonds of Al and N at the edge dislocations, Al-Al and NN bonds at the screw dislocations cause the defect states in the band gaps. This study not only has clarified the atomic origin of dislocation nano-optics, but also will encourage the development of microelectronics and optoelectronic devices based on dislocation ultraviolet light emission.

Evaluation of microbiological efficiency of use of pulsed ultraviolet devices in medical organization

Objective. To study bactericidal effect of continuous spectrum ultraviolet radiation on hospital flora and evaluate microbiological efficiency of using portable pulsed ultraviolet unit for disinfection of air and open surfaces in a medical organization. During the study, it was found that the selected research methods probably did not allow to achieve higher values of disinfection efficiency in shorter processing times.Materials and methods. The strains of microorganisms that were used for the study were taken from various loci from patients of the department of anesthesiology and intensive care for children with cardiac pathology on the first day of their transfer from various medical organizations, as well as museum strains from the collection of microorganisms of the laboratory. Single-use plastic Petri dishes with nutrient media in the laboratory were artificially contaminated with test strains. Air samples were taken during the work shift by aspiration using a Krotov’s apparatus. Wipes were taken with a sterile cotton swab dipped in nutrient medium.Results. No colonies of multiresistant K. pneumoniae, S. aureus, E. coli were detected in the samples as a result of exposure to a pulsed ultraviolet radiation source in a mode № 1; the efficiency of the action was 99.9–100%. With the regimen № 2 the efficacy was 83.33–99.9%. Assessment of microbiological efficiency of the disinfected open surfaces and air in a small operating room and a dressing room showed that the level of air contamination did not exceed the permissible level.Conclusions. It has been experimentally proved that pulsed UV radiation of broadband spectrum has high bactericidal activity against microorganisms of hospital environments.

Electronic structure, mechanical, optical and thermodynamic properties of cubic perovskite InBeF3 with pressure effects: First-principles calculations

The electronic structure, mechanical, optical and thermodynamic properties of cubic fluoroperovskite InBeF3 under high pressure were studied for the first time. The lattice parameter of the optimized InBeF3 crystal is 3.853 Å, which agrees well with the literature value (3.846 Å). The calculated phase transition point of InBeF3 is about 28.1 GPa. The band structure analysis show that the InBeF3 is an indirect band gap semiconductor (Eg = 2.226 eV) at zero pressure, and the band gap decreases as the pressure increases. Yet the form of its band gap does not change, and the value of band gap is always in the visible region under the pressure. In addition, the electronic structure of InBeF3 crystal is calculated by hybrid functional HSE06. It is found that the application of hybrid functional does not have much effect on the electronic structure of InBeF3. The valence bands of InBeF3 are mainly composed of the 4d orbital electrons of In and the 2 s orbital and 2p orbital electrons of F. The optical properties of InBeF3 crystal were further investigated. The absorption edge and static refractive index for InBeF3 at 0 GPa are 0.59 eV and 2.19, respectively. The peaks of all optical spectral increase as the pressure increase. Additionally, the relative volume, heat capacity, thermal expansion coefficient and Debye temperature of InBeF3 crystal were studied. The results of this paper show that the InBeF3 crystal has good absorption in the ultraviolet region and is potential candidate material in optical and ultraviolet devices.

A Computational First Principle Examination of the Elastic, Optical, Structural and Electronic Properties of AlRF3 (R = N, P) Fluoroperovskites Compounds.

This work describes an ab initio principle computational examination of the optical, structural, elastic, electronic and mechanical characteristics of aluminum-based compounds AlRF3 (R = N, P) halide-perovskites. For optimization purposes, we used the Birch-Murnaghan equation of state and discovered that the compounds AlNF3 and AlPF3 are both structurally stable. The IRelast software was used to compute elastic constants (ECs) of the elastic properties. The aforementioned compounds are stable mechanically. They exhibit strong resistance to plastic strain, possess ductile nature and anisotropic behavior and are scratch-resistant. The modified Becke-Johnson (Tb-mBJ) approximation was adopted to compute various physical properties, revealing that AlNF3 and AlPF3 are both metals in nature. From the density of states, the support of various electronic states in the band structures are explained. Other various optical characteristics have been calculated from the investigations of the band gap energy of the aforementioned compounds. These compounds absorb a significant amount of energy at high levels. At low energy levels, the compound AlNF3 is transparent to incoming photons, whereas the compound AlPF3 is somewhat opaque. The examination of the visual details led us to the deduction that the compounds AlNF3 and AlPF3 may be used in making ultraviolet devices based on high frequency. This computational effort is being made for the first time in order to investigate the aforementioned properties of these chemicals, which have yet to be confirmed experimentally.

Assessment of SARS-CoV-2 surrogate inactivation on surfaces and in air using UV and blue light-based intervention technologies

ABSTRACT The COVID-19 pandemic has created an urgent need to utilize existing and develop new intervention technologies for SARS-CoV-2 inactivation on surfaces and in the air. Ultraviolet (UV) technology has been shown to be an effective antimicrobial intervention. Here a study was conducted to determine the efficacy of commercially available UV and blue light-based devices for inactivating HCoV-229E, a surrogate of SARS-CoV-2. The results indicate that two UV devices designed for surface disinfection, with doses of 8.07 µJ/cm2 for the 254 nm device and 20.61 µJ/cm2 for the 275 nm device, were efficient in inactivating 4.94 logs of surface inoculated HCoV-229E. Additionally, a 222 nm UV device with intended ceiling-based operation was effective in inactivating 1.7 logs of the virus inoculated on surface, with a dose of 6 mJ/cm2. A ceiling-based device designed to emit blue light at 405 nm was found to produce 89% reduction in HCoV-229E inoculated on a surface for a dose of 78 J/cm2. Finally, the UV based 222 nm device was found to produce a 90% reduction in the concentration of airborne HCoV-229E, at a 55 µJ/cm2 dose. These results are indicative of the great potential of using UV based technology for the control of SARS-CoV-2. Implications: An important avenue of arresting COVID-19 and future pandemics caused by infectious pathogens is through environmental disinfection. To this effect, the study presented here evaluates commercially available UV and blue light based antimicrobial devices for their ability to kill the human coronavirus HCoV-229E, a surrogate of SARS-CoV-2, on surfaces and in air. The results indicate that two handheld UV devices produced complete inactivation of surface viral inoculum and a UVC ceiling based device produced 1 log reduction in HCoV-229E in air. These results imply the efficacy of UV technology as an antimicrobial tool, especially for rapid disinfection of indoor air.

Design and Construction of Ultraviolet and Incoming Solar Irradiance Sensing Device

In-situ measurements of ultraviolet (UV) and solar irradiance is very sparse in Nigeria because of cost; it is estimated using meteorological parameters. In this work, a low-cost UV and pyranometer device, using locally sourced materials, was developed. The instrument consists of a UV sensor (ML8511), a photodiode (BPW34) housed in a carefully sealed vacuumed glass bulb, the UV and solar irradiance sensor amplifiers, a 16-bit analog-to-digital converter (ADS1115), Arduino mega 2560, liquid crystal display (LCD) and microSD card for data logging. The designed amplifier has an offset voltage of 0.8676 mV. The sensitivity of the irradiance device is 86.819 Wm-2/mV with a correcting factor of 27.77 Wm-2 and a maximum range of 1200 Wm-2. The instrument validation error is 9.67% and a correlation coefficient of 0.89 when compared with a standard SRS100 pyranometer. The UV sensor showed a close response with a correlation of 0.99 in comparison with a standard Skye instrument. From 08:00 to 16:00 local time (LT), there is a very close agreement between the standard device and the developed counterpart, with marginal differences of about 9.6% observed at the two extremes.