Doses Of Ultraviolet Radiation Research Articles

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.

Evaluation of the abilities of atomic oxygen/ultraviolet resistance for the filled silicone rubber coating: Structures, properties, and aging mechanism

A series of experimental techniques were used to study the erosion-damage effect of a silica-filled silicone rubber coating exposed to simulated space environment (atomic oxygen and ultraviolet irradiation). The elastomer is known to be chemically and thermally stable, but there are insufficient data on its durability in the space environment. In the present work, atomic oxygen doses up to 3.8 × 1021 atoms·cm−2 and ultraviolet irradiation doses up to 360 equivalent sun-hours (ESH) were applied from Space Environment Simulation Measurement System, respectively. Since the aging and failure processes of the filled silicone rubber relate to different aspects of chemical structure and physics form, therefore, this study explored the use of chemical-mechanics methods to comprehensively evaluate the erosion-damage effect of materials. Morphology and chemical changes due to radiation were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and nanoindentation test probed surface mechanical properties changed with exposure dose. Results demonstrated that, with increased exposure time and irradiation-induced free radicals，the aggregation state and molecular chain structure of the silica-filled silicone rubber have changed, which caused an increase in surface hardness and modulus. Taken together, the results indicated that oxidative cross-linking was the dominant degradation mechanism under the irradiation dose in this paper.

Eradication of skin microbiota restores cytokine production and release in polymorphic light eruption.

Polymorphic light eruption (PLE) has been mechanistically linked to cytokine abnormalities. Emerging preclinical evidence posits the skin microbiome as a critical modulator of ultraviolet (UV)-induced cytokine expression, thereby influencing subsequent immune responses. This intricate relationship remains underexplored in the context of PLE. Hence, we investigated the differential responses between disinfected and non-disinfected skin following both single and repetitive exposures to solar-simulated UV radiation in patients with PLE. An experimental, half-body pilot study was conducted involving six PLE patients and 15 healthy controls. Participants' skin was exposed to single and multiple doses of solar-simulated UV radiation, both in disinfected and in non-disinfected skin areas. The co-primary outcomes were PLE score and cytokine expression in blister fluid analysed through OLINK proteomic profiling. Secondary outcomes were erythema, pigmentation, induction of apoptotic cells in vacuum-generated suction blisters, and density of infiltrate in skin biopsies of PLE patients. Among the 71 cytokines analysed, baseline expression levels of 20 specific cytokines-integral to processes such as apoptosis, inflammation, immune cell recruitment, cellular growth, and differentiation-were significantly impaired in PLE patients compared with healthy controls. Notably, skin disinfection reversed the observed cytokine imbalances following a single UV exposure at the minimal erythema dose (MED) level and exhibited even more pronounced effects after multiple UV exposures. However, no significant differences were evident in PLE score, erythema, pigmentation, or rates of apoptotic cell induction upon UV radiation. These findings provide evidence for UV-driven cytokine regulation by the skin microbiota and imply microbiome involvement in the PLE immune response.

Transcriptome analysis in mouse skin after exposure to ultraviolet radiation from a canopy sunbed.

Exposure to ultraviolet radiation (UV-R), from both natural and artificial tanning, heightens the risk of skin cancer by inducing molecular changes in cells and tissues. Despite established transcriptional alterations at a molecular level due to UV-R exposure, uncertainties persist regarding UV radiation characterization and subsequent genomic changes. Our study aimed to mechanistically explore dose- and time-dependent gene expression changes, that may drive short-term (e.g., sunburn) and long-term actinic (e.g., skin cancer) consequences. Using C57BL/6N mouse skin, we analyzed transcriptomic expression following exposure to five erythemally weighted UV-R doses (0, 5, 10, 20, and 40 mJ/cm2 ) emitted by a UV-R tanning device. At 96 h post-exposure, 5 mJ/cm2 induced 116 statistically significant differentially expressed genes (DEGs) associated with structural changes from UV-R damage. The highest number of significant gene expression changes occurred at 6 and 48 h post-exposure in the 20 and 40 mJ/cm2 dose groups. Notably, at 40 mJ/cm2 , 13 DEGs related to skin barrier homeostasis were consistently perturbed across all timepoints. UV-R exposure activated pathways involving oxidative stress, P53 signaling, inflammation, biotransformation, skin barrier maintenance, and innate immunity. This invivo study's transcriptional data offers mechanistic insights into both short-term and potential non-threshold-dependent long-term health effects of UV-R tanning.

Chemical characterization of sunflower oil oxidized by UV and ozone with different degrees of oxidation and study of their antimicrobial action

Oxidation by the action of ozone takes place at high rates and involves the reaction of ozone molecules with fatty acid double bonds followed by the formation of stable oxidation products with biological activity. In the present work, a comparative study on sunflower oil oxidized by ultraviolet (UV) light and ozone was carried out. This study involved the chemical characterization of sunflower oil oxidized by UV irradiation and ozonation, in addition to assessing the germicidal activity of oxidized oils obtained under various conditions. The results indicated that under the conditions studied, the increase in the dose of UV irradiation did not produce significant changes in the level of oxidation of the oil. Ozonation promoted the formation of oxygenated compounds at higher rates, increasing in concentration as the applied dosage of ozone increased. The germicidal activity of the oils behaved similarly, with considerably higher activity found in the ozonized oils.

Inhibitory effect of UV and gamma radiation for fungal biodeterioration of concrete: A short-term study for sustainable conservation

The conservation of concrete-based deteriorated heritage buildings is a big challenging issue worldwide including in India. This study focused on to prevent fungal biodeterioration in concrete using UVC and gamma radiation. M20 graded concrete cubes (5 cm × 5 cm × 5 cm) were infected with Aspergillus tamarii, which was isolated from a 200 years old historic heritage building. M20 signifies a mixture of cement, sand and aggregate (1:1.5:3), made in such a way that the concrete cube has a compressive strength of 20 N/mm2 when examined after 28 days of curing. The fungal growth appeared clearly as calcium oxalate crystals in the Scanning Electron Microscope (SEM) photographs. Several doses of UVC and gamma radiation were applied on concrete cube. The changes in concrete properties were examined after 30 days in terms of weight, compressive strength, Fourier Transform Infrared Spectroscopy (FTIR) and micro Energy Dispersive X-ray Fluorescence (EDXRF). The results exhibited that compressive strength of control (non-infected and non-irradiated), biodeteriorated (infected), UVC (625 µw/cm² × 300 s) and gamma (0.5 KGy) irradiated infected (inhibition) concrete cubes were 19.74 ± 0.46, 18.88 ± 0.43, 20.20 ± 0.34 and 19.93 ± 0.20 N/mm2 respectively whereas negligible weight losses were observed for inhibition cubes compared to biodeteriorated ones. Calcite (1400, 874 and 705 cm−1), one of the major functional band present in concrete became weak after getting infected by Aspergillus tamarii and strong for inhibition samples irradiated with the above doses. The EDXRF analysis exhibited that mass percentage of calcium ions of the biodeteriorated concrete cubes (49.88 ± 0.65%) was lower than that of UV (75.75 ± 0.16%) and gamma (70.95 ± 0.30%) irradiated infected or inhibition concrete cubes. Altogether, the efficacy of the recommended inhibitory dose of ultraviolet and gamma radiation against concrete deterioration in the field of conservation of heritage building was observed to be positive.

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.

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

Smart City and the digital measurement of solar ultraviolet radiation in Outdoor workers in the City of Lisbon

Abstract The growing incidence of skin cancer over the years has made it a significant public health problem. However, technology can be used to tackle the skin cancer which is highly preventable, mainly through reduced exposure to solar ultraviolet radiation (UVR). Digital services can be used to promote individual and collective protective measures and interventions. Specifically, there is an opportunity when the exposure is intermittent or continuous, and occurs in an occupational or leisure setting. We are using a digital platform to contribute to raising public and policy awareness on solar UVR-inflicted occupational skin cancers in the municipality of Lisbon. The digital platform is performing direct measurements of the solar UVR dose received by outdoor workers. Results will likely contribute to further understanding the risk estimates for keratinocyte cancer estimations in this population. The digital platform integrates a personal electronic dosimeter (GENESIS-UV system) to assess occupational solar UVR doses of gardeners, masons, and gravediggers of the municipality of Lisbon. Two hundred and ten outdoor workers were selected to wear the dosimeter for 1 month each, between April and October during their daily working hours. The digital platform that offers private access to information through dashboard visualization provided information for the outdoor workers and facilitate communication with the participants. Study data provides the outdoor workers with information on their personal solar UVR exposure during their working hours and an estimate of their risk of developing skin cancer. The results prospectively should flow into the design of adequate prevention campaigns for skin cancer in outdoor workers.

Ultraviolet sun exposure and sun protection behaviors in outdoor rock climbers

BackgroundOverexposure to sunlight and sunburn are the main preventable causes of skin cancer. Outdoor sports are associated with significant levels of sunlight exposure.AimsWe sought to quantify the sun radiation exposure received by outdoor rock climbers and assess their sun exposure habits, sun protection behaviors, attitudes, and knowledge regarding skin cancer.MethodsFrom April to June 2021, outdoor rock climbers contacted via email completed an online validated self-reported questionnaire on sun related habits, behaviors, attitudes and knowledge. As a pilot trial, ten participants wore a personal dosimeter during two outdoor climbing weekends in May and November 2021. Ambient ultraviolet radiation (UVR) was also recorded.ResultsA total of 217 outdoor rock climbers (103 women), mean age 36.8 ± 8.8 years (range 20–70 years) and median climbing practice per week of 8 h (IQR 7.5) were studied. Two in three (65.9%) participants reported at least one sunburn event during the previous rock climbing season. Of the survey respondents, 49.3% reported using sunscreen with SPF ≥ 15, 47% wore sunglasses, and 14.3% indicated they reapplied sunscreen every two hours. The median personal UVR dose measured during the two outdoor climbing weekends analyzed was 5.2 (IQR 1.8) and 8.8 (IQR 1.1) standard erythemal doses, respectively.ConclusionsThe high rates of sunburn, the elevated personal UVR measured and the clearly insufficient sun protection practices followed during rock climbing together with unsatisfactory attitudes towards tanning reveal the need to develop explicit sun protection campaigns and educational strategies to reduce the risk of skin cancer among the athletes studied.Graphical abstract

Photoirradiation‐Gated Excitation‐Dependent Room‐Temperature Phosphorescence in Through‐Space Charge Transfer Molecules

AbstractOrganic materials showing reversible changes in persistent room‐temperature phosphorescence (RTP) upon exposure to external stimuli have attracted considerable attention in recent years. One potentially groundbreaking development in this area is the introduction of the gating concept for organic persistent RTP materials. This refers to a material where a desired responsive ability only occurs when it is triggered by a specific stimulus, but it remains a formidable challenge. In this study, photoirradiation‐gated excitation‐dependent (Ex‐De) persistent RTP is achieved. A series of molecules, triphenylphosphine and carbazole derivatives connected through flexible carbon chains, are designed and prepared. Upon removal of ultraviolet (UV) irradiation, all these compounds doped polyvinyl alcohol (PVA) films exhibit obvious blue or green afterglow RTP. Among them, (2‐(9H‐[3,9′‐bicarbazol]−9‐yl)ethyl)triphenylphosphonium bromide (TPP‐2C‐Cz) doped PVA film initially exhibits blue persistent RTP after removal of 300 nm excitation but no RTP upon ceasing 365 nm irradiation. Interestingly, upon UV irradiation with a power density of 0.05 W cm−2 (UVA) for 50 min, the Ex‐De RTP behavior of TPP‐2C‐Cz doped PVA film is activated. Eventually, photoirradiation‐gated Ex‐De afterglow emission will be used for a wide range of applications, including the quantitative determination of UV irradiation dose and the permanent record of UV irradiation history, and read on‐demand.

Photochromic Uranyl-Based Coordination Polymer for Quantitative and On-Site Detection of UV Radiation Dose.

A highly sensitive detection of ultraviolet (UV) radiation is required in a broad range of scientific research, chemical industries, and health-related applications. Traditional UV photodetectors fabricated by direct wide-band-gap inorganic semiconductors often suffer from several disadvantages such as complicated manufacturing procedures, requiring multiple operations and high-cost instruments to obtain a readout. Searching for new materials or simple strategies to develop UV dosimeters for quantitative, accurate, and on-site detection of UV radiation dose is still highly desirable. Herein, a photochromic uranyl-based coordination polymer [(UO2)(PBPCA)·DMF]·DMF (PBPCA = pyridine-3,5-bis(phenyl-4-carboxylate), DMF = N,N'-dimethylformamide, denoted as SXU-1) with highly radiolytic and chemical stabilities was successfully synthesized via the solvothermal method at 100 °C. Surprisingly, the fresh samples of SXU-1 underwent an ultra-fast UV-induced (365 nm, 2 mW) color variation from yellow to orange in less than 1 s, and then the color changed further from orange to brick red after the subsequent irradiation, inspiring us to develop a colorimetric dosimeter based on red-green-blue (RGB) parameters. The mechanism of radical-induced photochromism was intensively investigated by UV-vis absorption spectra, EPR analysis, and SC-XRD data. Furthermore, SXU-1 was incorporated into an optoelectronic device to fabricate a novel dosimeter for convenient, quantitative, and on-site detection of UV radiation dose.

Thermal compensation reduces DNA damage from UV radiation

Increases in ultraviolet radiation (UVR) correlate spatially and temporally with global amphibian population declines and interact with other stressors such as disease and temperature. Declines have largely occurred in high-altitude areas associated with greater UVR and cooler temperatures. UVR is a powerful mutagenic harming organisms largely by damaging DNA. When acutely exposed to UVR at cool temperatures, amphibian larvae have increased levels of DNA damage. Amphibians may compensate for the depressive effects of temperature on DNA damage through acclimatisation, but it is unknown whether they have this capacity. We reared striped marsh frog larvae (Limnodynastes peronii) in warm (25 °C) and cool (15 °C) temperatures under a low or moderate daily dose of UVR (10 and 40 μW cm−2 UV-B for 1 h at midday, respectively) for 18–20 days and then measured DNA damage resulting from an acute high UVR dose (80 μW cm−2 UV-B for 1.5 h) at a range of temperatures (10, 15, 20, 25, and 30 °C). Larvae acclimated to 15 °C and exposed to UVR at 15 °C completely compensated UVR-induced DNA damage compared with 25 °C acclimated larvae exposed to UVR at 25 °C. Additionally, warm-acclimated larvae had higher DNA damage than cold-acclimated larvae across test temperatures, which indicated a cost of living in warmer temperatures. Larvae reared under elevated UVR levels showed no evidence of UVR acclimation resulting in lower DNA damage following high UVR exposure. Our finding that thermal acclimation in L. peronii larvae compensated UVR-induced DNA damage at low temperatures suggested that aquatic ectotherms living in cool temperatures may be more resilient to high UVR than previously realised. We suggested individuals or species with less capacity for thermal acclimation of DNA repair mechanisms may be more at risk if exposed to changing thermal and UVR exposure regimes.

Disinfection of Surfaces Contaminated with SARS-CoV-2 Coronavirus by UV Radiation of Low-Pressure Mercury-Vapour Lamp

The aim of the work was to determine the effective ultraviolet (UV) doses required for the disinfection of surfaces contaminated with the SARS-CoV-2 coronavirus using a low-pressure mercury lamp. Materials and methods. To carry out prompt disinfection of surfaces, a specially designed source of UV radiation with a power of 7.5 W at a wavelength of 254 nm in the form of a portable flashlight was employed, which has a high efficiency of UV radiation output and the possibility of long-term autonomous operation from a compact battery. In the studies, a suspension culture of the SARS-CoV-2 coronavirus with biological activity of 5.3∙106 PFU/ml was used. The objects of testing were plastic Petri dishes (disposable) and office paper (grade C, density 80 g/m2 ). Results and discussion. Doses of UV radiation that provide disinfection of surfaces contaminated with the COVID-19 pathogen with an efficiency of 99.0 % (paper) to 99.95 % (plastic) have been determined. The results obtained make it possible to recommend a portable UV irradiator for use in the practice of preventive measures to combat the spread of the disease caused by the SARS-CoV-2 coronavirus.

Performance Comparison of SONOS-Type UV TD Sensor Using Indium Tin Oxide-Aluminum Oxide-Zirconia Aluminum Oxide-Silicon Oxide-Silicon and Indium Tin Oxide-Aluminum Oxide-Hafnium Aluminum Oxide-Silicon Oxide-Silicon

This study compares the performance of two types of capacitive devices, indium tin oxide-aluminum oxide-zirconia aluminum oxide-silicon oxide-silicon (IAZAOS) and indium tin oxide-aluminum oxide-hafnium aluminum oxide-silicon oxide-silicon (IAHAOS), as silicon-oxide-nitride-oxide-silicon (SONOS) non-volatile memory (NVM) total dose of ultraviolet radiation (UV TD) sensors. Results show that IAZAOS with zirconia aluminum oxide as the charge-trapping layer outperforms IAHAOS with hafnium aluminum oxide for a UV TD sensor. After exposure to UV TD irradiation of 100 mW·s/cm2, the threshold voltage (VT) change of IAZAOS is almost 1.25 times that of IAHAOS. The study also found that annealing can significantly improve the response performance of IAZAOS UV TD sensors. Furthermore, IAZAOS devices with partially smaller nanocrystals in the charge-trapping layer greatly enhance the response of SONOS-type UV TD sensors. The study also compared the constant voltage stress-induced leakage current (CVSILC) and found that the CVSILC for annealed IAZAOS devices is 1000 times smaller than that of IAHAOS devices. Moreover, the IAZAOS-I2Z2 exhibits a superior performance regarding irradiation/refresh cycle endurance as compared to the IAHAOS-I2H1 device. These findings suggest that IAZAOS capacitive devices have superior performance and potential for use in SONOS-type UV TD sensors.

Obtaining emulsions of furanocoumarins from Sosnowsky’s hogweed and <i>in vitro</i> assessment of their phototoxic effect

Background. Furanocoumarin-based drugs are used for photochemotherapy of various diseases. Sosnovsky’s hogweed can be an available source of furanocoumarins for the development of drugs.The aim of the study. To obtain stable emulsions containing furanocoumarins from Sosnowski’s hogweed and to evaluate their photocytotoxicity.Materials and methods. To obtain the emulsions, furanocoumarins were extracted with chloroform from the sap of the aerial part of the Sosnowski’s hogweed. The chloroform extract was clarified by silica gel gradient column chromatography. The extractive fraction containing furanocoumarins was analyzed by high performance liquid chromatography with ultraviolet (UV) detection. An extract with a high content of 8-methoxypsoralen was used to prepare two types of emulsions. The extract was dissolved in peach oil and emulsified in water with tween-80 (emulsion No. 1) and in an aqueous glycerin solution with lecithin (emulsion No. 2).The emulsions were tested for dark and photo-induced toxicity for human lung fibroblasts. The dose of UV radiation for the photoactivation of furanocoumarins was 9 J/cm2. A solution of chlorine e6 was used as a comparison photosensitizer.Results. The obtained emulsions contained 1 mg/ml 8-methoxypsoralen. Both emulsions were homogeneous at macro- and microscopic visualization, remained stable when stored under various temperature conditions for 14 days. Emulsion No. 2 did not show dark toxicity and caused a statistically significant inhibition of cell viability under UV irradiation at a concentration of 12.5–31.3 µg/mL. Emulsion No. 1 had a toxic effect on cells regardless of UV irradiation due to the content of tween-80. According to fluorescent microscopy, the phototoxic effect of emulsion No. 2 was manifested mainly due to apoptosis, in contrast to the effect of chlorine e6, in which there were more pronounced signs of cell necrosis.Conclusion. The developed experimental emulsions of furanocoumarins from Sosnovski’s hogweed are an example of promising medicinal photosensitizers of plant origin for phototherapy of various dermatological and oncological diseases.

Study of the Sensor Properties of Ordered ZnO Nanorod Arrays for the Detection of UV Radiation

Zinc oxide is one of the most promising materials used to create devices in the ultraviolet (UV) range. In this article, we study the sensor properties of ordered ZnO nanorod arrays grown by chemical vapor deposition. The possibility of their use as an indicator of UV radiation to control the dose of UV radiation, both from natural and artificial light sources, is assessed. The X-ray diffraction, Raman spectroscopy (RS), and cathodoluminescence (CL) data demonstrate the high quality of nanorods. Based on the ZnO nanorod array, a sensor prototype was fabricated based on the change in ZnO conductivity under the UV irradiation. A compari-son of the response of such a sensor with the readings of a UV radiometer showed a high correlation.

PD03 Afamelanotide reduces the ultraviolet radiation erythemal response soon after application in healthy volunteers with skin phototypes II–III

Abstract Afamelanotide is a potent α-melanocyte stimulating hormone analogue that binds to the melanocortin 1 receptor and, over time, promotes tanning, conferring systemic photoprotection. Afamelanotide also has antioxidant properties and may promote repair of ultraviolet (UV) radiation (UVR)-induced DNA damage. The objectives of this study were to examine the short-term impact of afamelanotide on DNA damage repair mechanisms, UVR erythema and melanogenic responses in healthy human skin following exposure to UVR. Healthy men and women (n = 10) volunteers aged 27–43 years (median 34) of skin phototypes II–III were recruited. Reflectance spectrophotometry was performed on six body sites (photoexposed and photoprotected) to assess skin pigmentation, and then a geometric series of erythemally weighted doses (7–80 mJ cm−2) of broadband UVB (∼60% UVB, 40% UVA; Philips TL12) was applied to unexposed upper buttock skin. After 24 h, the minimal erythema dose (MED) was assessed and erythema intensity (CIE a*) was measured at each dose site. A subcutaneous implant of afamelanotide 16 mg was administered; 5 days later, the same UVR dose series was applied to unexposed contralateral upper buttock skin. After 24 h, the MED was assessed and repeat skin reflectance measurements were performed. The overall UVR–erythema dose response (area under curve) showed a significant decrease post-afamelanotide (mean 3.5 vs. 2.7; P = 0.018). There was an apparent increase in the median MED post-afamelanotide (24.5 vs. 29.9 mJ cm−2; not statistically significant). Reflectance measurements showed skin lightness (CIE L*) significantly decreased at only one site (central forehead, from 63.0 to 61.0; P = 0.015), while determination of melanin density by reflectance at 420 and 400 nm showed a statistically significant increase in density at all sites except the right abdomen, with a mean overall increase from 2.5% to 2.9% (P = 0.001). Our results indicate that afamelanotide reduces the overall UVR–erythema dose response in healthy human skin shortly after administration, with a small increase in melanogenesis, suggesting other nonmelanogenic properties of this agent contribute to the erythema protection. Further investigation will examine whether enhanced repair of UVR-induced DNA damage plays a role. Funding sources: research sponsored by CLINUVEL (UK) Ltd.

Micromechanical modeling of the visco-hyperelastic–viscoplastic​ behavior and fracture of aged semicrystalline polymers

This work presents a micromechanical-based visco-hyperelastic–viscoplastic constitutive model for low-density polyethylene (LDPE) films subjected to accelerated ultraviolet (UV) aging. The model captures the evolution of the mechanical and fracture properties of the material. Our proposed framework assumes that the semicrystalline polymer’s macromechanical behavior is the sum of the intermolecular and macromolecular network contributions. The intermolecular part of the model follows a nonlinear composite mixture rule, combining the contribution of the crystalline and amorphous phases, each represented rheologically by a linear elastic spring in series with a nonlinear viscous dashpot. The rheological representation of the macromolecular network consists of a series of two Langevin springs capturing deformation-induced conformation change and interatomic bond deformation between Kuhn segments, as well as a viscous dashpot for chain relaxation. We have developed a novel framework that reformulates the eight chain model to include the energy densities associated with both conformation change and interatomic bond deformation, providing a more accurate description of macromolecular network mechanical and fracture behavior. The aging of semicrystalline polymers results from two competing mechanisms: oxidation-induced strengthening resulting from chemicrystallization and crosslinking, and oxidation-induced softening resulting from chain scissions and chemicavitation. Our proposed model accurately captures the effect of UV aging on the mechanical behavior of the semicrystalline material. Additionally, we introduce the novel concept of a ”healthy network” to predict the evolution of the strain to fracture. The model accurately predicts the evolution of the mechanical behavior and elongation at break over a wide range of UV irradiation doses.

Ultraviolet radiation exposure in cannabis-growing facilities

Cannabis cultivation and processing is becoming an important industry in the United States and Canada. The industry employs over 400,000 workers in the United States and is growing rapidly. Both natural sunlight and artificial lamp-generated radiation are commonly used to grow cannabis plants. These optical sources can contain both visible and ultraviolet radiation (UVR) wavelengths, and overexposure to UVR is associated with negative health effects. The severity of these adverse health effects is governed by the specific wavelengths and exposed dose of UVR, yet worker exposure to UVR within cannabis-growing facilities has not been studied. In this study, worker exposure to UVR was assessed at five cannabis production facilities in Washington State, including indoor, outdoor, and shade house facilities. Lamp emission testing was performed at each facility and worker UVR exposures were measured for 87 work shifts. Observations of worker activities and use of personal protective equipment in association with UVR exposure measurements were recorded. For lamp emission measurements, at 3 feet from the center of the lamp, the average irradiances were 4.09 × 10−4, 6.95 × 10−8, 6.76 × 10−9, 3.96 × 10−9, and 1.98 × 10−9 effective W/cm2 for germicidal lamps, metal halide lamps, high-pressure sodium lamps, fluorescent lamps, and light emitting diodes, respectively. The average measured UVR exposure was 2.91 × 10−3 effective J/cm2 (range: 1.54 × 10−6, 1.57 × 10−2 effective J/cm2). Thirty percent of the work shifts monitored exceeded the American Conference for Governmental Industrial Hygienists (ACGIH®) threshold limit value (TLV®) of 0.003 effective J/cm2. Exposures were highest for workers who spent all or part of the work shift outdoors, and solar radiation was the primary source of worker UVR exposure for most of the work shifts that exceeded the TLVs. Outdoor workers can reduce UVR exposure by applying sunscreen and wearing appropriate personal protective equipment. Although the artificial lighting used in the cannabis production facilities included in this study did not contribute substantially to the measured UV exposures, in many cases the lamp emissions would generate theoretical exposures at 3 feet from the center of the lamp that would exceed the TLV. Therefore, employers should choose low UVR emitting lamps for indoor grow operations and should use engineering controls (e.g., door-interlocks to de-energize lamps) to prevent worker exposure to UVR from germicidal lamps.