Moderate UV Exposure Enhances Learning and Memory by Promoting a Novel Glutamate Biosynthetic Pathway in the Brain.

Sunlight exposure is known to affect mood, learning, and cognition. However, the molecular and cellular mechanisms remain elusive. Here, we show that moderate UV exposure elevated blood urocanic acid (UCA), which then crossed the blood-brain barrier. Single-cell mass spectrometry and isotopic labeling revealed a novel intra-neuronal metabolic pathway converting UCA to glutamate (GLU) after UV exposure. This UV-triggered GLU synthesis promoted its packaging into synaptic vesicles and its release at glutamatergic terminals in the motor cortex and hippocampus. Related behaviors, like rotarod learning and object recognition memory, were enhanced after UV exposure. All UV-induced metabolic, electrophysiological, and behavioral effects could be reproduced by the intravenous injection of UCA and diminished by the application of inhibitor or short hairpin RNA (shRNA) against urocanase, an enzyme critical for the conversion of UCA to GLU. These findings reveal a new GLU biosynthetic pathway, which could contribute to some of the sunlight-induced neurobehavioral changes.

CsMYBL2 homologs modulate the light and temperature stress-regulated anthocyanin and catechins biosynthesis in tea plants (Camellia sinensis).

Anthocyanin and catechin production in tea (Camellia sinensis) leaves can positively affect tea quality; however, their regulatory mechanisms are not fully understood. Here we report that, while the CsMYB75- or CsMYB86-directed MYB-bHLH-WD40 (MBW) complexes differentially activate anthocyanin or catechin biosynthesis in tea leaves, respectively, CsMYBL2a and CsMYBL2b homologs negatively modified the light- and temperature-induced anthocyanin and catechin production in both Arabidopsis and tea plants. The MBW complexes activated both anthocyanin synthesis genes and the downstream repressor genes CsMYBL2a and CsMYBL2b. Overexpression of CsMYBL2b, but not CsMYBL2a, repressed Arabidopsis leaf anthocyanin accumulation and seed coat proanthocyanin production. CsMYBL2b strongly and CsMYBL2a weakly repressed the activating effects of CsMYB75/CsMYB86 on CsDFR and CsANS, due to their different EAR and TLLLFR domains and interactions with CsTT8/CsGL3, interfering with the functions of activating MBW complexes. CsMYBL2b and CsMYBL2a in tea leaves play different roles in fine-tuning CsMYB75/CsMYB86-MBW activation of biosynthesis of anthocyanins and catechins, respectively. The CsbZIP1-CsmiR858a-CsMYBL2 module mediated the UV-B- or cold-activated CsMYB75/CsMYB86 regulation of anthocyanin/catechin biosynthesis by repressing CsMYBL2a and CsMYBL2b. Similarly, the CsCOP1-CsbZIP1-CsPIF3 module, and BR signaling as well, mediated the high temperature repression of anthocyanin and catechin biosynthesis through differentially upregulating CsMYBL2b and CsMYBL2a, respectively. The present study provides new insights into the complex regulatory networks in environmental stress-modified flavonoid production in tea plant leaves.

Comparison of different trapping methods to collect malaria vectors indoors and outdoors in western Kenya.

BACKGROUND: Vector surveillance is among the World Health Organization global vector control response (2017-2030) pillars. Human landing catches are a gold standard but difficult to implement and potentially expose collectors to malaria infection. Other methods like light traps, pyrethrum spray catches and aspiration are less expensive and less risky to collectors. METHODS: Three mosquito sampling methods (UV light traps, CDC light traps and Prokopack aspiration) were evaluated against human landing catches (HLC) in two villages of Rarieda sub-county, Siaya County, Kenya. UV-LTs, CDC-LTs and HLCs were conducted hourly between 17:00 and 07:00. Aspiration was done indoors and outdoors between 07:00 and 11:00 a.m. Analyses of mosquito densities, species abundance and sporozoite infectivity were performed across all sampling methods. Species identification PCR and ELISAs were done for Anopheles gambiae and Anopheles funestus complexes and data analysis was done in R. RESULTS: Anopheles mosquitoes sampled from 608 trapping efforts were 5,370 constituting 70.3% Anopheles funestus sensu lato (s.l.), 19.7% Anopheles coustani and 7.2% An. gambiae s.l. 93.8% of An. funestus s.l. were An. funestus sensu stricto (s.s.) and 97.8% of An. gambiae s.l. were Anopheles arabiensis. Only An. funestus were sporozoite positive with 3.1% infection prevalence. Indoors, aspiration captured higher An. funestus (mean = 6.74; RR = 8.83, P < 0.001) then UV-LT (mean = 3.70; RR = 3.97, P < 0.001) and CDC-LT (mean = 1.74; RR = 1.89, P = 0.03) compared to HLC. UV-LT and CDC-LT indoors captured averagely 0.18 An. arabiensis RR = 5.75, P = 0.028 and RR = 5.87, P = 0.028 respectively. Outdoors, UV-LT collected significantly higher Anopheles mosquitoes compared to HLC (An. funestus: RR = 5.18, P < 0.001; An. arabiensis: RR = 15.64, P = 0.009; An. coustani: RR = 11.65, P < 0.001). Anopheles funestus hourly biting indoors in UV-LT and CDC-LT indicated different peaks compared to HLC. CONCLUSIONS: Anopheles funestus remains the predominant mosquito species. More mosquitoes were collected using aspiration, CDC-LTs and UV-LTs indoors and UV-LTs and CD-LTs outdoors compared to HLCs. UV-LTs collected more mosquitoes than CDC-LTs. The varied trends observed at different times of the night suggest that these methods collect mosquitoes with diverse activities and care must be taken when interpreting the results.

Acute skin exposure to ultraviolet light triggers neutrophil-mediated kidney inflammation.

Photosensitivity to ultraviolet (UV) light affects up to ∼80% of lupus patients. Sunlight exposure can exacerbate local as well as systemic manifestations of lupus, including nephritis, by mechanisms that are poorly understood. Here, we report that acute skin exposure to UV light triggers a neutrophil-dependent injury response in the kidney characterized by upregulated expression of endothelial adhesion molecules as well as inflammatory and injury markers associated with transient proteinuria. We showed that UV light stimulates neutrophil migration not only to the skin but also to the kidney in an IL-17A-dependent manner. Using a photoactivatable lineage tracing approach, we observed that a subset of neutrophils found in the kidney had transited through UV light-exposed skin, suggesting reverse transmigration. Besides being required for the renal induction of genes encoding mediators of inflammation (vcam-1, s100A9, and Il-1b) and injury (lipocalin-2 and kim-1), neutrophils significantly contributed to the kidney type I interferon signature triggered by UV light. Together, these findings demonstrate that neutrophils mediate subclinical renal inflammation and injury following skin exposure to UV light. Of interest, patients with lupus have subpopulations of blood neutrophils and low-density granulocytes with similar phenotypes to reverse transmigrating neutrophils observed in the mice post-UV exposure, suggesting that these cells could have transmigrated from inflamed tissue, such as the skin.

Natural variation in Beauty Mark is associated with UV-based geographical adaptation in Gossypium species.

BACKGROUND: Anthocyanins, a class of specialized metabolites that are ubiquitous among plant species, have attracted a great deal of attention from plant biologists due to their chemical diversity. They confer purple, pink, and blue colors that attract pollinators, protect plants from ultraviolet (UV) radiation, and scavenge reactive oxygen species (ROS) to facilitate plant survival during abiotic stress. In a previous study, we identified Beauty Mark (BM) in Gossypium barbadense as an activator of the anthocyanin biosynthesis pathway; this gene also directly led to the formation of a pollinator-attracting purple spot. RESULTS: Here, we found that a single nucleotide polymorphism (SNP) (C/T) within the BM coding sequence was responsible for variations in this trait. Transient expression assays of BM from G. barbadense and G. hirsutum in Nicotiana benthamiana using luciferase reporter gene also suggested that SNPs in the coding sequence could be responsible for the absent beauty mark phenotype observed in G. hirsutum. We next demonstrated that the beauty mark and UV floral patterns are associated phenotypes and that UV exposure resulted in increased ROS generation in floral tissues; BM thus contributed to ROS scavenging in G. barbadense and wild cotton plants with flowers containing the beauty mark. Furthermore, a nucleotide diversity analysis and Tajima's D Test suggested that there have been strong selective sweeps in the GhBM locus during G. hirsutum domestication. CONCLUSIONS: Taken together, these results suggest that cotton species differ in their approaches to absorbing or reflecting UV light and thus exhibit variations in floral anthocyanin biosynthesis to scavenge reactive ROS; furthermore, these traits are related to the geographic distribution of cotton species.

Streptomycetes as Microbial Cell Factories for the Biotechnological Production of Melanin.

Melanins are complex, polymeric pigments with interesting properties like UV-light absorbance ability, metal ion chelation capacity, antimicrobial action, redox behaviors, and scavenging properties. Based on these characteristics, melanins might be applied in different industrial fields like food packaging, environmental bioremediation, and bioelectronic fields. The actual melanin manufacturing process is not environmentally friendly as it is based on extraction and purification from cuttlefish. Synthetic melanin is available on the market, but it is more expensive than animal-sourced pigment and it requires long chemical procedures. The biotechnological production of microbial melanin, instead, might be a valid alternative. Streptomycetes synthesize melanins as pigments and as extracellular products. In this review, the melanin biotechnological production processes by different Streptomyces strains have been revised according to papers in the literature. The different fermentation strategies to increase melanin production such as the optimization of growth conditions and medium composition or the use of raw sources as growth substrates are here described. Diverse downstream purification processes are also reported as well as all the different analytical methods used to characterize the melanin produced by Streptomyces strains before its application in different fields.

Minimizing Escherichia coli O157:H7 contamination in indoor farming: effects of cultivar type and ultra-violet light quality.

BACKGROUND: Bacterial contamination of produce is a concern in indoor farming due to close plant spacing, recycling irrigation, warm temperatures, and high relative humidity during production. Cultivars that inherently resist contamination and photo-sanitization using ultraviolet (UV) radiation during the production phase can reduce bacterial contamination. However, there is limited information to support their use in indoor farming. RESULTS: Lettuce (Lactuca sativa) cultivars with varying plant architectures grown in a custom-built indoor farm exhibited differences in E. coli O157:H7 survival after inoculation. The survival of E. coli O157:H7 was lowest in the leaf cultivar (open architecture) and highest in the romaine and oakleaf cultivars (compact architecture). Of the different UV wavelengths that were tested (UV-A, UV-A + B, UV-A + C), UV A + C at an intensity of 54.5 µmol m-2 s-1 (with 3.5 µmol m-2 s-1 of UV-C), provided for 15 min every day, was found to be most efficacious in reducing the E. coli O157:H7 survival on romaine lettuce with no negative effects on plant growth and quality. CONCLUSION: Contamination of E. coli O157:H7 on lettuce plants can be reduced and the food safety levels in indoor farms can be increased by selecting cultivars with an open leaf architecture coupled with photo-sanitization using low and frequent exposure to UV A + C radiation. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Photo-thermal synergistic excitation: Feasible strategy to detect ethanol for wide bandgap ZIF-8 at low work temperature.

Zeolitic Imidazolate Framework-8 (ZIF-8) material was prepared by chemical precipitation method. The microstructure and physical properties of the as-prepared samples were characterized by XRD, BET, FESEM and UV spectrophotometer. The self-made four-channel measurement device was used to test the gas sensitivity of ZIF-8 material toward ethanol gas under photo-thermal synergistic excitation. The results showed that the sample was typical ZIF-8 (Eg = 4.96 eV) with a regular dodecahedron shape and the specific surface is up to 1793 m2/g. The as-prepared ZIF-8 has a gas response value of 55.04 to 100 ppm ethanol at 75°C and it shows good gas sensing selectivity and repeated stability. The excellent gas sensitivity can be attributed to the increase of free electron concentration in the ZIF-8 conduction band by photo-thermal synergistic excitation, and the large specific surface area of ZIF-8 material provides more active sites for gas-solid surface reaction. The reaction mechanism of ZIF-8 material under multi-field excitation was also discussed.

Changes in the Location of Cutaneous Melanoma Over the Past 30 Years. A Retrospective Observational Study. / Cambios en la localización del melanoma cutáneo en los últimos 30 años. Estudio observacional retrospectivo.

BACKGROUND: The location of cutaneous melanoma is associated with photoexposure. OBJECTIVES: To retrospectively analyze changes in the location of cutaneous melanoma over the past 30 years. PATIENTS AND METHODS: All patients treated at our hospital for cutaneous melanoma from 1988 through 2017 were prospectively collected. Data obtained in cases diagnosed from 1988 through June 2006 were compared to those diagnosed from July 2006 through 2017. RESULTS: A total of 1,937 patients (876 men and 1061 women; median age, 57 years; interquartile range 27) were diagnosed with primary cutaneous melanoma. The location of melanoma was head and neck (470 cases), trunk (745 cases), upper limbs (239 cases), and lower limbs (483 cases). From July 2006 through 2017 we detected an increase in the incidence of head and neck melanomas (19.9% vs 28.6%, p <0.001). A drop in the incidence of melanomas located in the lower extremities was also seen in women (39.8% vs 30.4%, p <0.001), and in the trunk men (57.5% vs 47.3%, p=0.003). In the multivariate analyses, only the decrease in melanomas located in lower extremities in women remained significant. CONCLUSION: The increased incidence of head and neck melanomas in both sexes and the decrease in trunk melanomas in men can be attributed to the aging of our population. The reduction in the incidence of melanomas in the lower extremities in women could be associated with changes in photoexposure patterns. Analyzing the factors possibly associated with these changes would contribute to better understanding the pathogenesis of cutaneous melanoma for prevention purposes.

Use of light activated intramedullary device for revision of a proximal humerus fracture: a case study.

BACKGROUND: Post-operative non-compliance is a risk factor for fracture fixation failure and presents a challenge for revision surgery planning. We present a patient who underwent revision surgery for a proximal humerus fracture with lateral locked plating augmented with a UV light activated intramedullary implant. CASE: A 45-year-old woman with a history of alcoholism presented with a proximal humerus fracture. After undergoing open reduction internal fixation with a lateral locking plate, the patient suffered a fall secondary to delirium tremens. New radiographs demonstrated displacement of the fracture with failure of screws. Revision surgery consisting of removal of the initial construct as well as open reduction internal fixation via lateral locking plate, augmented with a UV-activated intramedullary cement implant, was performed. CONCLUSION: This is the first case report describing the use of a UV-activated intramedullary cement implant to augment the use of lateral locked plating for proximal humerus fractures. This case illustrates the successful management using UV-activated intramedullary cement to augment fixation, specifically in a patient with risk factors and post-operative non-compliance that predispose to fixation failure.

Customized Production of Holey Graphene Oxides via a Continuous Flow Process.

Continuous flow manufacturing is an innovative technology mainly applied in the chemical and pharmaceutical industries that is progressively being adapted to the manufacturing of nanomaterials to overcome the challenge of reproducing a product with consistent characteristics at a large scale. Here, a flow photochemical system is designed and prototyped for the synthesis of holey graphene oxides (hGOs). Compared to existing methods for the synthesis of hGO, the process is fast, highly scalable, and controllable. Through a combination of rigorous data analysis using machine learning algorithms on transmission electron microscope images and systematic studies of process parameters, it is demonstrated that characteristics of the produced hGO (i.e., porosity and pore size) are remarkably reproducible to the extent that it can be predicted by empirical models of processing-property correlations. Depending on the tailored nanopore structures, the synthesized hGOs out-performed GO in a range of applications that can benefit from the nanoporous two-dimensional (2D) sheets such as in supercapacitors, gas adsorption, and nanofiltration membranes. These results are significant in offering new perspectives on the low-cost industrialization of 2D nanomaterials.

Inactivated Cowpea Mosaic Virus for In Situ Vaccination: Differential Efficacy of Formalin vs UV-Inactivated Formulations.

Cowpea mosaic virus (CPMV) has been developed as a promising nanoplatform technology for cancer immunotherapy; when applied as in situ vaccine, CPMV exhibits potent, systemic, and durable efficacy. While CPMV is not infectious to mammals, it is infectious to legumes; therefore, agronomic safety needs to be addressed to broaden the translational application of CPMV. RNA-containing formulations are preferred over RNA-free virus-like particles because the RNA and protein, each, contribute to CPMV's potent antitumor efficacy. We have previously optimized inactivation methods to develop CPMV that contains RNA but is not infectious to plants. We established that inactivated CPMV has reduced efficacy compared to untreated, native CPMV. However, a systematic comparison between native CPMV and different inactivated forms of CPMV was not done. Therefore, in this study, we directly compared the therapeutic efficacies and mechanisms of immune activation of CPMV, ultraviolet- (UV-), and formalin (Form)-inactivated CPMV to explain the differential efficacies. In a B16F10 melanoma mouse tumor model, Form-CPMV suppressed the tumor growth with prolonged survival (there were no statistical differences comparing CPMV and Form-CPMV). In comparison, UV-CPMV inhibited tumor growth significantly but not as well as Form-CPMV or CPMV. The reduced therapeutic efficacy of UV-CPMV is explained by the degree of cross-linking and aggregated state of the RNA, which renders it inaccessible for sensing by Toll-like receptor (TLR) 7/8 to activate immune responses. The mechanistic studies showed that the highly aggregated state of UV-CPMV inhibited TLR7 signaling more so than for the Form-CPMV formulation, reducing the secretion of interleukin-6 (IL-6) and interferon-α (IFN-α), cytokines associated with TLR7 signaling. These findings support the translational development of Form-CPMV as a noninfectious immunotherapeutic agent.

An innovative strategy to investigate microbial protein modifications in a reliable fast and sensitive way: A therapy oriented proof of concept based on UV-C irradiation of SARS-CoV-2 spike protein.

The characterization of modifications of microbial proteins is of primary importance to dissect pathogen lifecycle mechanisms and could be useful in identifying therapeutic targets. Attempts to solve this issue yielded only partial and non-exhaustive results. We developed a multidisciplinary approach by coupling in vitro infection assay, mass spectrometry (MS), protein 3D modelling, and surface plasma resonance (SPR). As a proof of concept, the effect of low UV-C (273 nm) irradiation on SARS-CoV-2 spike (S) protein was investigated. Following UV-C exposure, MS analysis identified, among other modifications, the disruption of a disulphide bond within the conserved S2 subunit of S protein. Computational analyses revealed that this bond breakage associates with an allosteric effect resulting in the generation of a closed conformation with a reduced ability to bind the ACE2 receptor. The UV-C-induced reduced affinity of S protein for ACE2 was further confirmed by SPR analyses and in vitro infection assays. This comprehensive approach pinpoints the S2 domain of S protein as a potential therapeutic target to prevent SARS-CoV-2 infection. Notably, this workflow could be used to screen a wide variety of microbial protein domains, resulting in a precise molecular fingerprint and providing new insights to adequately address future epidemics.

Accelerated Ultraviolet Treatment of Carbamazepine and NDMA in Water under 222 nm Irradiation.

Krypton chloride (KrCl*) excimer ultraviolet (UV) light may provide advantages for contaminant degradation compared to conventional low-pressure (LP) UV. Direct and indirect photolysis as well as UV/hydrogen peroxide-driven advanced oxidation (AOP) of two chemical contaminants were investigated in laboratory grade water (LGW) and treated secondary effluent (SE) for LPUV and filtered KrCl* excimer lamps emitting at 254 and 222 nm, respectively. Carbamazepine (CBZ) and N-nitrosodimethylamine (NDMA) were chosen because of their unique molar absorption coefficient profiles, quantum yields (QYs) at 254 nm, and reaction rate constants with hydroxyl radical. Quantum yields and molar absorption coefficients at 222 nm for both CBZ and NDMA were determined, with measured molar absorption coefficients of 26 422 and 8170 M-1 cm-1, respectively, and QYs of 1.95 × 10-2 and 6.68 × 10-1 mol Einstein-1, respectively. The 222 nm irradiation of CBZ in SE improved degradation compared to that in LGW, likely through promotion of in situ radical formation. AOP conditions improved degradation of CBZ in LGW for both UV LP and KrCl* sources but did not improve NDMA decay. In SE, photolysis of CBZ resulted in decay similar to that of AOP, likely due to the in situ generation of radicals. Overall, the KrCl* 222 nm source significantly improves contaminant degradation compared to that of 254 nm LPUV.

222-nm UVC light as a skin-safe solution to antimicrobial resistance in acute hospital settings with a particular focus on methicillin-resistant Staphylococcus aureus and surgical site infections: a review.

The increasing burden of antimicrobial resistance necessitates a novel approach to disinfect multidrug resistant pathogens. Conventional 254-nm ultraviolet-C (UVC) light shows high germicidal efficacy against bacteria. However, it induces pyrimidine dimerization in exposed human skin with carcinogenic potential. Recent developments suggest 222-nm UVC light can be used to disinfect bacteria and cause less harm to human DNA. This new technology can be used to disinfect healthcare-associated infections and more specifically surgical site infections (SSIs). This includes but is not limited to methicillin-resistant Staphylococcus aureus (MRSA), P. aeruginosa, C. difficile, E. coli, and other aerobic bacteria. This thorough review of scarce literature assesses the germicidal efficacy and skin safety of 222-nm UVC light with a particular focus on its clinical applications to MRSA and SSIs. The study reviews a variety of experimental models, including in vivo and in vitro cell cultures, live human skin, human skin models, mice skin, and rabbit skin. The potential for long-term eradication of bacteria and efficacy against specific pathogens is appraised. This paper focuses on the methods and models used in past and present research to determine the efficacy and safety of 222-nm UVC in the acute hospital setting with a focus on MRSA and its applicability to SSIs.

Luteolin photo-protects zebrafish from environmental stressor ultraviolet radiation (UVB).

Ultraviolet B wavelength ray radiation (UVB) is an environmental stressor with detrimental effects to the aquatic and human systems but also enhances adverse effects when combined with several other environmental factors such as temperature and pollution. UV rays induce cellular oxidative damage and impair motility. This study aimed to examine the photo-protective activity of flavonoid luteolin against UV-B irradiation-induced oxidative stress and cellular damage using zebrafish. An in-vivo photoaging model was established using UV-B irradiation in zebrafish larvae exposed to 100 mJ/cm2. Data demonstrated that UV-B irradiation of swimming water enhanced production of ROS and superoxide anions as well as depleted total glutathione levels in zebrafish larvae. UV-B irradiation also triggered cellular damage and membrane rupture in zebra fish. Further, 100 mJ/cm2 of UV-B radiation exposure to adult-wild type zebrafish co-exposed with intraperitoneally (ip) injected luteolin upregulated the local neuroendocrine axes by activating vascular endothelial growth factor (VEGF) and elevating levels of pro-inflammatory cytokines IL-1ß and TNF-α. Histologically, UV-B irradiation induced skin lesions and locomotory defects with clumping and degeneration of brain glial cells. However, luteolin effectively inhibited the excess production of reactive oxygen species (ROS) and decreased superoxide anion levels induced by UV-B irradiation. Luteolin restored the depleted glutathione levels. In addition, luteolin blocked apoptosis and lipidperoxidation. Luteolin protected adult zebrafish by downregulating the pro-inflammatory cytokine protein expression levels and diminishing VEGF activation. Luteolin also alleviated locomotory defects by inhibiting activation of microglia and inflammatory responses by preventing accumulation of glial cells and vacuolation. Data demonstrate that luteolin may protect zebrafish from UV-B-induced photodamage through DNA-protective, antioxidant and anti-inflammatory responses.

Seasonality and uncertainty in global COVID-19 growth rates.

The virus causing COVID-19 has spread rapidly worldwide and threatens millions of lives. It remains unknown, as of April 2020, whether summer weather will reduce its spread, thereby alleviating strains on hospitals and providing time for vaccine development. Early insights from laboratory studies and research on related viruses predicted that COVID-19 would decline with higher temperatures, humidity, and ultraviolet (UV) light. Using current, fine-scaled weather data and global reports of infections, we develop a model that explains 36% of the variation in maximum COVID-19 growth rates based on weather and demography (17%) and country-specific effects (19%). UV light is most strongly associated with lower COVID-19 growth. Projections suggest that, without intervention, COVID-19 will decrease temporarily during summer, rebound by autumn, and peak next winter. Validation based on data from May and June 2020 confirms the generality of the climate signal detected. However, uncertainty remains high, and the probability of weekly doubling rates remains >20% throughout summer in the absence of social interventions. Consequently, aggressive interventions will likely be needed despite seasonal trends.

UV Sensor Based on Surface Acoustic Waves in ZnO/Fused Silica.

Zinc oxide (ZnO) thin films have been grown by radio frequency sputtering technique on fused silica substrates. Optical and morphological characteristics of as-grown ZnO samples were measured by various techniques; an X-ray diffraction spectrum showed that the films exhibited hexagonal wurtzite structure and were c-axis-oriented normal to the substrate surface. Scanning electron microscopy images showed the dense columnar structure of the ZnO layers, and light absorption measurements allowed us to estimate the penetration depth of the optical radiation in the 200 to 480 nm wavelength range and the ZnO band-gap. ZnO layers were used as a basic material for surface acoustic wave (SAW) delay lines consisting of two Al interdigitated transducers (IDTs) photolithographically implemented on the surface of the piezoelectric layer. The Rayleigh wave propagation characteristics were tested in darkness and under incident UV light illumination from the top surface of the ZnO layer and from the fused silica/ZnO interface. The sensor response, i.e., the wave velocity shift due to the acoustoelectric interaction between the photogenerated charge carriers and the electric potential associated with the acoustic wave, was measured for different UV power densities. The reversibility and repeatability of the sensor responses were assessed. The time response of the UV sensor showed a rise time and a recovery time of about 10 and 13 s, respectively, and a sensitivity of about 318 and 341 ppm/(mW/cm2) for top and bottom illumination, respectively. The ZnO/fused silica-based SAW UV sensors can be interrogated across the fused silica substrate thanks to its optical transparency in the UV range. The backlighting interrogation can find applications in harsh environments, as it prevents the sensing photoconductive layer from aggressive environmental effects or from any damage caused by cleaning the surface from dust which could deteriorate the sensor's performance. Moreover, since the SAW sensors, by their operating principle, are suitable for wireless reading via radio signals, the ZnO/fused-silica-based sensors have the potential to be the first choice for UV sensing in harsh environments.

Synthesis of Bimetallic BiPO4/ZnO Nanocomposite: Enhanced Photocatalytic Dye Degradation and Antibacterial Applications.

Multidrug-resistant strains (MDRs) are becoming a major concern in a variety of settings, including water treatment and the medical industry. Well-dispersed catalysts such as BiPO4, ZnO nanoparticles (NPs), and different ratios of BiPO4/ZnO nanocomposites (NCs) were synthesized through hydrothermal treatments. The morphological behavior of the prepared catalysts was characterized using XRD, Raman spectra, PL, UV-Vis diffuse reflectance spectroscopy (UV-DRS), SEM, EDX, and Fe-SEM. MDRs were isolated and identified by the 16s rDNA technique as belonging to B. flexus, B. filamentosus, P. stutzeri, and A. baumannii. The antibacterial activity against MDRs and the photocatalytic methylene blue (MB) dye degradation activity of the synthesized NPs and NCs were studied. The results demonstrate that the prepared BiPO4/ZnO-NCs (B1Z4-75:300; NCs-4) caused a maximum growth inhibition of 20 mm against A. baumannii and a minimum growth inhibition of 12 mm against B. filamentosus at 80 µg mL-1 concentrations of the NPs and NCs. Thus, NCs-4 might be a suitable alternative to further explore and develop as an antibacterial agent. The obtained results statistically justified the data (p ≤ 0.05) via one-way analysis of variance (ANOVA). According to the results of the antibacterial and photocatalytic study, we selected the best bimetallic NCs-4 for the photoexcited antibacterial effect of MDRs, including Gram ve+ and Gram ve- strains, via UV light irradiation. The flower-like NCs-4 composites showed more effectiveness than those of BiPO4, ZnO, and other ratios of NCs. The results encourage the development of flower-like NCs-4 to enhance the photocatalytic antibacterial technique for water purification.

Metal-Free Aerobic C-N Bond Formation of Styrene and Arylamines via Photoactivated Electron Donor-Acceptor Complexation.

This study processes a facile and green approach for the Markovnikov-selective hydroamination of styrene with naphthylamine through irradiation with UV LED light (365 nm) via an electron donor-acceptor complexation between naphthylamines and oxygen in situ. This protocol showcases the synthetic potential for aerobic C-N bond formation without using a metal catalyst and photosensitizer. Three naphthylamines were examined and afforded desired C-N bond formation product in moderate yield.