Ultraviolet Dose Research Articles

Hypericum brasiliense: assessment of the antioxidant potential in UVA-induced in vitro phototoxicity

Photoaging induced by ultraviolet A (UVA) radiation is mainly caused by the reactive oxygen species (ROS) increase, which trigger undesirable changes in the skin, such as inflammatory reactions, wrinkles, hyperpigmentation, and loss of elasticity. In this context, plant ingredients have been highlighted in recent decades due to their antioxidant mechanisms. This study investigated the potential of Hypericum brasiliense ethanolic extract against UVA-induced damage in 3T3 fibroblasts. Cells exposed to a single UVA dose (4 J/cm2, 30 min) were treated with different extract concentrations. The results showed that H. brasiliense extract has antioxidant potential, mitigating UVA-induced stress by reducing ROS and lipid peroxidation. Furthermore, the extract stimulated fibroblast proliferation, suggesting its potential to restore cell viability after radiation-induced damage. The search for replacing synthetic actives with natural ones reinforces the importance of these findings on the antioxidant and regenerative properties of H. brasiliense extract, making it a promising anti-aging ingredient or a sunscreen adjuvant.

Global transcriptional response of Pseudomonas aeruginosa to UVA radiation.

Ultraviolet A (UVA) radiation is the major fraction of UV radiation reaching the Earth's surface. Its harmful effects on microorganisms, due mainly to oxidative damage, have been exploited for development of natural solar and commercial UVA-based disinfection methods. In this work, the global transcriptional response of Pseudomonas aeruginosa exposed to ultraviolet A (UVA) radiation was analyzed. To conduct this study, we analyzed the whole transcriptome of the PAO1 strain grown to logarithmic phase under sublethal doses of UVA or in the dark. We found that a total of 298 genes responded to UVA with a change of at least two-fold (5.36% of the total P. aeruginosa genome), and showed equal amount of induced and repressed genes. An important fraction of the induced genes were involved in the response to DNA damage and included induction of SOS, prophage and pyocins genes. The results presented in this study suggest that one of the main UVA targets are proteins carrying [Fe-S] clusters since several genes involved in the processes of synthesis, trafficking and assembly of these structures were upregulated. The management of intracellular iron levels also seems to be a robust response to this stress factor. The strong induction of genes involved in denitrification suggest that this pathway and/or reactive nitrogen species such as nitric oxide could have a role in the response to this radiation. Regarding the down-regulated genes, we found many involved in the biosynthesis of PQS, a quorum-sensing signal molecule with a possible role as endogenous photosensitizer.

Ultraviolet, Did the Cell See It from the Side or the Bottom? Assessment and Modeling of UV Effects on Cultured Cells Using the CL-1000 UV-Crosslinker.

Numerous natural extracts and compounds have been evaluated for their ability to mitigate the adverse effects of ultraviolet (UV) overexposure. However, variability in the UV doses that trigger biological responses across studies likely arises from inconsistencies in UV exposure standardization. We hypothesize that these discrepancies are due to variations in culture plates and dishes. The UV dose (D) required to reduce cell viability by 50% differed by a factor of ten between 3.5 cm dishes and 96-well plates. Similarly, the EC50 dose for IL-6 release (D1/2) varied, potentially correlating with the surface area (S). UV exposure to wells with increasing height in 3.5 cm dishes resulted in a decrease in IL-6 release, suggesting that the greater the well height, the more it may influence UV exposure through reflection or shielding effects, thereby contributing to the physiological effects on the cells. To compare these differences among plates, we defined the height-to-diameter ratio (r). Analysis revealed a linear correlation between D1/2 and S in a log-log plot, and between D1/2 and r in a semi-log plot. From this, we defined two empirical indices σ and ρ for UV dose adjustment. A deductive model was also developed to derive a D' value that adjusts UV doses without requiring training. As with σ and ρ, the UV dose D was effectively adjusted using D' as well. These attempts suggest that D' offers a foundational framework for evaluating UVB effects on cultured cells.

Potential for synergism of sequential UV-NaClO disinfection on ARGs removal in municipal sewage: Effectiveness, kinetics, and mechanisms

Conventional disinfection technologies have limitations in effectively addressing the challenges posed by the emerging pollutant of antibiotic resistance genes (ARGs). To reduce the risk of antibiotic resistance in wastewater treatment plant (WWTP) effluent, this study investigated the effectiveness of ultraviolet (UV) irradiation followed by Sodium hypochlorite (NaClO) (sequential UV-NaClO) disinfection in removing six classes and 18 subtypes of ARGs in the secondary effluent of a municipal WWTP. The study showed that UV disinfection could reduce tetracycline ARGs (TCs-ARGs) subtype tetQ by 0.98 log, while it was ineffective in removing sulfonamide ARGs (SAs-ARGs). NaClO disinfection was very effective in removing ARGs. Increasing the disinfectant dosage is more effective than extending the disinfection time. The highest removal was observed for the SAs-ARGs subtype sul1 with 4.15 log and the β-lactams-ARGs(β-LACs-ARGs) subtype blaCTX-M1 with 3.87 log. Sequential UV-NaClO disinfection has the potential for synergistic effects in disinfection. Sequential UV-NaClO disinfection with a UV dosage of 15 mJ/cm2 and a NaClO dosage of 10 mg/L can effectively remove 1.46 log of the total 18 subtypes of ARGs, which is 0.73 log higher than the removal achieved by standalone UV irradiation at a fluence of 100 mJ/cm2, and equivalent to the results obtained with NaClO disinfection alone at a dose of 30 mg/L. Additionally, sequential UV-NaClO disinfection can reduce the repair efficiency of ARGs. The proposed modified Hom model can be used to analyze the kinetics of sequential UV-NaClO disinfection synergy. Analysis of microbial community structure and co-occurrence of ARGs showed synchronized and consistent removal of ARGs and their potential bacterial hosts. Sequential UV-NaClO disinfection could achieve 99 % removal of more than half of the genera. Overall, our results indicate that sequential disinfection is a promising disinfection technology for disinfecting municipal wastewater and reducing the spread and transfer of ARGs.

Variability of solar UV radiation in the northern mountains of the Czech Republic, 2020–2021

Solar ultraviolet (UV) radiation has a crucial role in many atmospheric processes and a huge impact on living organisms. Its main positive effect is the synthesis of vitamin D, but it also causes problems such as sunburn, skin cancer or eye cataracts. In the mountains, high doses of UV frequently occur due to a specific combination of atmospheric and geographical factors such as a high ground reflection as a consequence of a large number of days with snow cover, or a lower concentration of atmospheric pollutants in comparison to lowland urban regions. This study used measurements of erythemal UV radiation from two high altitude areas: the Hrubý Jeseník Mountains (Vysoká hole meteorological station, 1 464 m a.s.l.) and the Giant Mountains (Luční bouda meteorological station, 1 413 m a.s.l.) in the Czech Republic, during 2020 and 2021. We evaluated the daily and monthly changes in erythemal dose and UV index. The maximum daily dose of 5.0 kJ.m-2 (8.9 of UV index) was measured on 28 June 2020 at Vysoká hole. The maximal UV index of 10.1 was observed at Luční bouda on 5 July 2020, while the maximum daily dose of 4.9 kJ.m-2 occurred on 14 June 2021. The main factors that caused changes in solar UV radiation were the amount of cloud cover as well as the total ozone column.

α-Arbutin ameliorates UVA-induced photoaging through regulation of the SIRT3/PGC-1α pathway.

Owing to its tyrosinase inhibitory activity, α-arbutin has been added to several skin care products as a skin-lightening agent. However, the protective effect of α-arbutin against ultraviolet A (UVA)-induced photoaging has not been well investigated. The present study was designed to investigate the photoprotective effect and mechanism of α-arbutin against UVA-induced photoaging. In vitro experiments, HaCaT cells were treated with UVA at a dose of 3J/cm2 to evaluate the anti-photoaging effect of α-arbutin. α-Arbutin was found to exhibit a strong antioxidant effect by increasing glutathione (GSH) level and inhibiting reactive oxygen species (ROS) production. Meanwhile, α-arbutin markedly improved the expression of sirtuin 3 (SIRT3) and peroxisome proliferator-activated receptor γ coactivator 1 α (PGC-1α) proteins, initiating downstream signaling to increase mitochondrial membrane potential and mediate mitochondrial biogenesis, and improve mitochondrial structure significantly. In vivo analysis, the mice with shaved back hair were irradiated with a cumulative UVA dose of 10J/cm2 and a cumulative ultraviolet B (UVB) dose of 0.63J/cm2. The animal experiments demonstrated that α-arbutin increased the expression of SIRT3 and PGC-1α proteins in the back skin of mice, thereby reducing UV-induced skin damage. In conclusion, α-arbutin protects HaCaT cells and mice from UVA damage by regulating SIRT3/PGC-1α signaling pathway.

Preliminary Study of the Characterization of the Viable but Noncultivable State of Yersinia enterocolitica Induced by Chloride and UV Irradiation.

The viable but non-culturable (VBNC) state is a survival strategy for many foodborne pathogens under adverse conditions. Yersinia enterocolitica (Y. enterocolitica) as a kind of primary foodborne pathogen, and it is crucial to investigate its survival strategies and potential risks in the food chain. In this study, the effectiveness of ultraviolet (UV) irradiation and chlorine treatment in disinfecting the foodborne pathogen Y. enterocolitica was investigated. The results indicated that both UV irradiation and chlorine treatment can induce the VBNC state in Y. enterocolitica. The bacteria completely lost culturability after being treated with 25 mg/L of NaClO for 30 min and a UV dose of 100 mJ/cm². The number of culturable and viable cells were detected using plate counting and a combination of fluorescein and propidium iodide (live/dead cells). Further research found that these VBNC cells exhibited reduced intracellular Adenosine Triphosphate (ATP) levels, and increased levels of reactive oxygen species (ROS) compared to non-induced cells. Morphologically, the cells changed from a rod shape to a shorter, coccobacillary shape with small vacuoles forming at the edges, indicating structural changes. Both condition-induced VBNC-state cells were able to resuscitate in tryptic soy broth (TSB) medium supplemented with Tween 80, sodium pyruvate, and glucose. These findings contribute to a better understanding of the survival mechanisms of Y. enterocolitica in the environment and are of significant importance for the development of effective disinfection strategies.

Estimation of the UV susceptibility of aerosolized SARS-CoV-2 to 254 nm irradiation using CFD-based room disinfection simulations

The recent COVID-19 pandemic has raised interest in efficient air disinfection solutions. The application of germicidal ultraviolet (GUV) irradiation is an excellent contender to prevent airborne transmission of COVID-19, as well as other existing and future infectious airborne diseases. While GUV has already been proven effective in inactivating SARS-CoV-2, quantitative data on UV susceptibility and dose requirements, needed to predict and optimize the performance of GUV solutions, is still limited. In this study, the UV susceptibility of aerosolized SARS-CoV-2 to 254 nm ultraviolet (UV) irradiation is investigated. This is done by employing 3D computational fluid dynamics based simulations of SARS-CoV-2 inactivation in a test chamber equipped with an upper-room UV-C luminaire and comparing the results to previously published measurements performed in the same test chamber. The UV susceptibility found in this study is (0.6 ± 0.2) m2/J, which is equivalent to a D90 dose between 3 and 6 J/m2. These values are in the same range as previous estimations based on other corona viruses and inactivation data reported in literature.

Photodynamic inactivation of antibiotic-resistant bacteria in whole blood using riboflavin photodynamic method.

Treating bacteremia caused by antibiotic-resistant bacteria is a global concern. Antibacterial photodynamic inactivation is a promising strategy to combat it. However, it's challenging to achieve the inactivation of antibiotic-resistant bacteria in whole blood because of its opacity and complexity. We investigated a riboflavin photodynamic method to effectively inactivate antibiotic-resistant bacteria in whole blood. Four strains of antibiotic-resistant bacteria were isolated, identified, and cultured in this research: methicillin-resistant Staphylococcus aureus (MRSA), pan-drug-resistant Acinetobacter baumannii (PDRAB), ESBLs-producing Escherichia coli (EPEC) and pan-drug-resistant Klebsiella pneumoniae (PDRKP). To simulate bacteremia, antibiotic-resistant bacteria was added into whole blood. Whole blood was treated using riboflavin photodynamic method with ultraviolet irradiation (308 nm and 365 nm). The ultraviolet irradiation dose was divided into 18 J/cm2, 36 J/cm2, and 54 J/cm2. Microbial count of antibiotic-resistant bacteria in whole blood was used for evaluating inactivation effectiveness. The roles of red blood cells, lymphocytes, coagulation factors, and platelets in whole blood were assessed. In results, inactivation effectiveness increased as the ultraviolet dose increased from 18 J/cm2 to 54 J/cm2. At the dose of 18 J/cm2, inactivation effectiveness of four antibiotic-resistant bacteria were more than 80%, while only 67% of MRSA. The antibacterial effect was enhanced by the combination of riboflavin photodynamic treatment and antibiotic. The red blood cell function was susceptible to ultraviolet dose. At the dose of 18 J/cm2, hemolysis rate was less than 0.8% and there was no change in levels of ATP and 2,3-DPG. At the same dose, the proliferation, cell killing, and cytokine secretion activities of lymphocytes decreased 20-70%; Factor V and Factor VIII activities decreased 50%; Fibrinogen and platelet function loss significantly but reparable. Consequently, we speculated that riboflavin photodynamic method with a ultraviolet dose of 18 J/cm2 was effective in inactivating four antibiotic-resistant bacteria in whole blood while whole blood function was preserved. We also provided a novel extracorporeal circulation phototherapy mode for treating bacteremia caused by antibiotic-resistant bacteria.

Determining the ultraviolet radiation dose experienced by aerosols using ultraviolet-sensitive dyes

Abstract. ​​​​​​​The application of ultraviolet (UV)-light-based air disinfection methods holds promise but also presents several challenges. Among these, the quantitative determination of the required UV radiation dose for aerosols is particularly significant. This study explores the possibility of determining the UV dose experienced by aerosols without the use of virus-containing aerosols, circumventing associated laboratory safety issues. To achieve this, we developed a model system comprised of UV-sensitive dyes dissolved in di-ethyl-hexyl-sebacate (DEHS), which facilitates the generation of non-evaporating and UV-degradable aerosols. For the selection of UV-sensitive dyes, 20 dyes were tested, and 2 of them were selected as being the most suitable, according to several selection criteria. Dye-laden aerosol droplets were generated using a commercial aerosol generator and subsequently exposed to UV-C radiation in a laboratory-built UV irradiation chamber. We designed a low-pressure impactor to collect the aerosols pre- and post-UV exposure. Dye degradation, as a result of UV light exposure, was then analyzed by assessing the concentration changes in the collected dye solutions using a UV-visible spectrophotometer. Our findings revealed that a UV dose of 245 mW s cm−2 resulted in a 10 % degradation, while a lower dose of 21.6 mW s cm−2 produced a 5 % degradation. In conclusion, our study demonstrates the feasibility of using aerosol droplets containing UV-sensitive dyes to determine the UV radiation dose experienced by an aerosol.

Photochromic Perovskite Nanocrystals for Ultraviolet Dosimetry.

Excessive ultraviolet (UV) radiation has serious damage to human's health, therefore the development of visible, portable, and wearable sensor for monitoring UV radiation, especially the cumulative UV dosage, is highly desired but full of challenges. Herein, a wearable and flexible UV dosimeter based on photochromic perovskite nanocrystals (PNCs) is designed. The obtained CsPbCl3 PNCs dispersed in dibromomethane (PNCs-DBM) undergo continuous, vivid, and multiple (from very weak purple to blue, cyan, and finally strong green) color change in response to UV radiation. It is demonstrated that the UV-induced degradation of DBM and subsequent anion-exchange reaction between CsPbCl3 and Br-, play a crucial role in the color change of PNCs-DBM. The properties of continuous fluorescence color change and enhanced fluorescence intensity enable the construction of sensitive and visible UV dosimeter. Furthermore, by integrated photochromic PNCs with flexible bracelet or PDMS substrate, a wearable UV sensor or a multi-indicator array for the detection of solar UV dosage is developed. This work may advance the fundamental understanding about photochromic perovskite, and show promising application of perovskite nanomaterials in easily fabricated, low-cost, visualized, and wearable solar UV dosimeter.

From waste to tape: Inverse vulcanization of sulfur and solvent-based depolymerization for preparation of pressure-sensitive adhesives

Upcycling is an eco-friendly method that turns waste into valuable items. Elemental sulfur, a waste substance produced in large amounts (70 million tons per year), can be converted into valuable polymers using inverse vulcanization. However, the traditional method had significant limitations, such as limited consumption and weak strength. To address this problem, we newly fabricated sulfur-based pressure-sensitive adhesives (PSAs). PSAs are soft and tacky materials that should have low modulus, and they are used extensively (3.1 million tons per year). We prepared sulfur-based PSAs in four steps: polymerization, dissolution, coating/drying, and curing. In the polymerization step, castor oil and oleic acid were employed to facilitate inverse vulcanization. The resulting polymer then underwent solvent-based depolymerization to be coated in a film form. After drying and ultra-violet (UV)-induced curing, the tapes were successfully produced. Significantly, we adjusted the PSA's crosslinking density by changing the oleic acid content and UV dose. As the amount of mono-functional oleic acid decreased or the UV dose increased, the resulting PSA's crosslinking density increased. The best conditions led to PSAs with excellent adhesion performances and creep resistance, similar to commercial tapes. Moreover, the prepared PSAs exhibited self-healing properties, suggesting the feasibility of high-performance PSAs like remoldable PSAs and conductive sensors.

Comparison of photodamage in non-pigmented and pigmented human skin equivalents exposed to repeated ultraviolet radiation to investigate the role of melanocytes in skin photoprotection.

Daily solar ultraviolet (UV) radiation has an important impact on skin health. Understanding the initial events of the UV-induced response is critical to prevent deleterious conditions. However, studies in human volunteers have ethical, technical, and economic implications that make skin equivalents a valuable platform to investigate mechanisms related to UV exposure to the skin. In vitro human skin equivalents can recreate the structure and function of in vivo human skin and represent a valuable tool for academic and industrial applications. Previous studies have utilised non-pigmented full-thickness or pigmented epidermal skin equivalents to investigate skin responses to UV exposure. However, these do not recapitulate the dermal-epidermal crosstalk and the melanocyte role in photoprotection that occurs in vivo. In addition, the UV radiation used in these studies is generally not physiologically representative of real-world UV exposure. Well-characterised pigmented and non-pigmented skin equivalents that contain human dermal fibroblasts, endogenous secreted extracellular matrix proteins (ECM) and a well-differentiated and stratified epidermis have been developed. These constructs were exposed to UV radiation for ×5 consecutive days with a physiologically relevant UV dose and subsequently analysed using appropriate end-points to ascertain photodamage to the skin. We have described that repeated irradiation of full-thickness human skin equivalents in a controlled laboratory environment can recreate UV-associated responses in vitro, mirroring those found in photoexposed native human skin: morphological damage, tanning, alterations in epidermal apoptosis, DNA lesions, proliferation, inflammatory response, and ECM-remodelling. We have found a differential response when using the same UV doses in non-pigmented and pigmented full-thickness skin equivalents, emphasising the role of melanocytes in photoprotection.

Recovery of insect-pathogenic fungi from solar UV damage: Molecular mechanisms and prospects.

Molecular mechanisms underlying insect-pathogenic fungal tolerance to solar ultraviolet (UV) damage have been increasingly understood. This chapter reviews the methodology established to quantify fungal response to solar UV radiation, which consists of UVB and UVA, and characterize a pattern of the solar UV dose (damage) accumulated from sunrise to sunset on sunny summer days. An emphasis is placed on anti-UV mechanisms of fungal insect pathogens in comparison to those well documented in model yeast. Principles are discussed for properly timing the application of a fungal pesticide to improve pest control during summer months. Fungal UV tolerance depends on either nucleotide excision repair (NER) or photorepair of UV-induced DNA lesions to recover UV-impaired cells in the darkness or the light. NER is a slow process independent of light and depends on a large family of anti-UV radiation (RAD) proteins studied intensively in model yeast but rarely in non-yeast fungi. Photorepair is a rapid process that had long been considered to depend on only one or two photolyases in filamentous fungi. However, recent studies have greatly expanded a genetic/molecular basis for photorepair-dependent photoreactivation that serves as a primary anti-UV mechanism in insect-pathogenic fungi, in which photolyase regulators required for photorepair and multiple RAD homologs have higher or much higher photoreactivation activities than do photolyases. The NER activities of those homologs in dark reactivation cannot recover the severe UV damage recovered by their activities in photoreactivation. Future studies are expected to further expand the genetic/molecular basis of photoreactivation and enrich principles for the recovery of insect-pathogenic fungi from solar UV damage.

A Correlation Analysis between Color Change and Environmental Factors of Traditional Dancheong Specimens with Outdoor Exposure

The purpose of this study was to analyze the influence of various environmental factors on the color change of outdoor exposed dancheong specimens. From 2017 to 2019, nine traditional Dancheong specimens(Sokganju, Jinsa, Hwangto, Jahwang, Wunghwang, Seokrok, Noerok, Seokcheong, and Baekto) were exposed to Sungnyemun Gate(SNG) and the National Institute of Cultural Heritage(NRICH) as conditions for blocking rainfall, respectively. Subsequently, chromaticity measurements were conducted periodically, and monitoring, collection, and IC analysis of meteorological elements, gaseous pollutants, TSP and Dustfall were performed. As a result of the analysis, after processing the measured values, the linear correlation between the color difference of the traditional dancheong specimen and environmental factors was analyzed by Pearson’s correlation analysis. Among the meteorological elements, the linear correlation of strong positive between solar radiation, UV radiation, and evaporation was confirmed in 6-8 of the NRICH specimens and 6 of the SNG specimens. Among the gaseous pollutants, a strong positive linear correlation with SO<sub>2</sub> and O<sub>3</sub> was confirmed only by the SNG specimens, Among the ion concentrations of TSP, four types of strong positive linear correlations between NO<sub>3</sub><sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, and Ca<sup>2+</sup> were confirmed only in the specimen of the NRICH. Among the ion concentrations of Dustfall, a strong positive linear correlation with SO<sub>4</sub><sup>2-</sup>, NO<sub>3</sub><sup>-</sup> and Ca<sup>2+</sup> was found in 5-7 of SNG and 1-5 of the NRICH, and in particular, a strong positive linear correlation with Na<sup>+</sup> and Cl<sup>-</sup> was found in 2 of the SNG specimens. Therefore, it was confirmed that ultraviolet dose among meteorological elements and the concentration of NO<sub>3</sub><sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, and Cl<sup>-</sup> in the dustfall act as accelerating factors in the chromaticity change of the dancheong specimen.

Inactivation of pathogenic microorganisms in water by electron beam excitation multi-wavelength ultraviolet irradiation: Efficiency, influence factors and mechanism

Due to the limitations of traditional ultraviolet (UV) in microbial inactivation in water, it is necessary to explore a more suitable and efficient UV disinfection method. In this study, an electron beam excitation multi-wavelength ultraviolet (EBE-MW-UV) system was established and aims to analyze its differential microbial inactivation capabilities in comparison to single-wavelength UV-LEDs in waterborne applications. Furthermore, the inactivation mechanisms of this system on microorganisms were explored. The results showed that EBE-MW-UV had significantly higher inactivation effects on the Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans in water compared to UV-LEDs (p＜0.05), and the inactivation effect of EBE-MW-UV on Escherichia coli and Pseudomonas aeruginosa at the same UV dose was 3.8 and 1.9 log higher than that of UV-LEDs, respectively, EBE-MW-UV exhibited better inactivation effects on Gram-negative bacteria. Further research found that, under the majority of irradiation doses, neither EBE-MW-UV nor UV-LEDs were significantly affected by the concentration of suspended solids (5 and 20 mg/L) or humic acids (2 and 5 mg/L) in the water. Mechanism analysis revealed that during the disinfection process of EBE-MW-UV, microbial DNA and proteins were initially damaged, which prevented the occurrence of dark repair and led to bacterial inactivation. In addition, UV irradiation led to the production of additional reactive oxygen species (ROS) inside the cells, increasing cell membrane permeability and exacerbating membrane damage. This was accompanied by a decrease in energy metabolism and depletion of ATP, ultimately resulting in microbial inactivation. Therefore, EBE-MW-UV demonstrated more effective disinfection than single-wavelength UV-LEDs, showing great potential. Our research gives new insights into the characteristics of multiple wavelength ultraviolet, and provides scientific basis for the selection of new light sources in the field of ultraviolet disinfection.

A pilot study on the antimicrobial efficacy of a novel UV-LED system against drainage stack bioaerosol emissions during flushing episodes

Inactivation of airborne microorganisms by ultraviolet (UV) light has been considered one of the most effective procedures among disinfection methods. Ultraviolet light-emitting diodes (UV-LEDs) have a unique place as an emerging technology in air disinfection processes because of their rapid effectiveness and lack of material deterioration. In this study, the efficacy of high-power 285 nm UV-LEDs was explored for Escherichia coli (E. coli) (ATCC15597) inactivation in drainage stack airflow under continuous- and pulsed-UV irradiation conditions. Most relevant photoelectric properties influencing the device operation and performance, including duty cycles and input voltage, were thoroughly investigated. Antimicrobial efficiency varied from 29.0% to 88.0%. The antimicrobial efficiency of pulsed UV irradiation at different duty cycles but the same UV dose was similar. Antimicrobial efficiency was positively correlated with input voltage but negatively correlated with airflow velocity. Moreover, antimicrobial efficiency increased almost linearly with input power per airflow volume (P/Qa). The estimated Z-values of E. coli ranged from 0.0027 to 0.0341 cm2/µJ, and about 29–370 μJ/cm2 of UV dose can be used to obtain one-log inactivation of E. coli, depending on the experimental conditions. The results of this investigation indicate that UVB units can inactivate gastrointestinal drainage stack bioaerosols effectively. This study provides critical information and guidelines for disinfecting drainage stacks with UV, which may aid pathogen infection control in public environments during outbreaks.

Эффект синергизма для управления посевными качествами семян люцерны изменчивой с элементами нейросети для контроля дозы УФО

The article presents studies to identify the greatest synergy effect for managing the sowing qualities of alfalfa seeds of variable Victoria with the use of neural network elements to control the dose of ultraviolet irradiation. The synergistic effect occurs when the seeds are simultaneously exposed first to ultraviolet radiation and then to a silicon-containing preparation of nanosilicon, or first to treatment with a preparation of NanoSilicon, and then to ultraviolet radiation. In both cases, changes in the sowing qualities of seeds were observed. The seeds were irradiated on a mobile LED UV irradiation unit using end-to-end digital energy-saving technologies with neural network elements to control the dose of UFOs with a VEML6070 digital sensor from the manufacturer Vishay Semiconductors. The TKS– ABC device measured the energy illumination of UV LEDs at a height of 70 mm, which showed that UV-A radiation is 95.67% at an average energy illumination of 3.137 W/m2, UV-B radiation is 3.41% at 0.112 W/m2 and UV-C radiation is 0.91% at 0.030 W/m2. The conducted studies have revealed that the greatest synergistic effect for managing the sowing qualities of alfalfa seeds occurs when alfalfa seeds are treated first with a nanosilicon preparation, and then with UFOs. As a result of the management of the sowing qualities of alfalfa seeds, which is involved in the implementation of the proposed sequence of pre-sowing seed treatment, an increase in laboratory germination was obtained by 6% at HCR05 – 4%; the length of the sprout up to 2.4 cm and the root up to 1.5 cm; the degree of development of seedlings up to 3.0 points and growth strength up to 29.8%. Keywords: ALFALFA VARIABLE, LABORATORY GERMINATION, DEGREE OF SEEDLING DEVELOPMENT, GROWTH VIGOR, SYNERGISM, ULTRAVIOLET IRRADIATION DOSE, DIGITAL CONTROL SYSTEMS

The Kinetics of Carrier Trap Parameters in Na8Al6Si6O24(Cl,S)2 Hackmanite.

Tenebrescence has been reported to have a high potential for personal ultraviolet (UV) detection. Color changes can detect UV doses and can also be used as visual sensors for X-rays. Hackmanite is known to exhibit tenebrescence. This study investigated the kinetics of electron-trapping levels contributing to the luminescence of Na8Al6Si6O24(Cl,S)2 hackmanite using thermoluminescence. The glow curves were measured at a heating rate of 5 K/s on hackmanite irradiated with X-rays. The physical parameters of the electron-trapping levels were evaluated by analyzing them using the deconvolution, peak shape, and initial rise methods. The Na8Al6Si6O24(Cl,S)2 hackmanite had at least five trapping levels, with activation energies of 0.78, 1.12, 1.86, 1.26, and 1.18 eV and corresponding peak trap lifetimes of 3.59, 2.71, 1.47, 3.34, and 3.91 s, respectively. The estimated migration time was 15.0 s.

Dose Distribution Scaling and Validation of Ultraviolet Photoreactors Using Dimensional Analysis.

Ultraviolet (UV) disinfection is commonly applied in the treatment of drinking water and wastewater. The performance of UV disinfection systems is governed by the UV dose distribution delivered to the fluid, which is an intrinsic characteristic of the reactor under a given operating condition. Current design and validation approaches are based on empirical methods that are expensive to apply and provide limited information about the UV photoreactor behavior. To address this issue, a dose distribution scaling method was developed based on dimensional analysis (i.e., application of the Buckingham-π theorem). Three dimensionless groups representing UV dose, reactor geometry, and UV absorption behavior were defined. Using these groups, the approach was applied for the analysis of 15 operating conditions, defined by process variables of volumetric flow rate, UV transmittance, and lamp power. The approach was demonstrated to allow scaling of the dose distribution with these critical, dimensionless variables and yielded close agreement between predictions of disinfection efficacy against MS2 and E. coli based on the scaling approach with conventional CFD-E' modeling results. The approach thus provides a low-cost, rapid method for predicting the performance of UV disinfection systems across a wide range of operating conditions and against essentially any microbial challenge agent.