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In this research, the influence of face milling, sanding and UV irradiation of the hornbeam and ash wood sample on the wetting and adhesion strength of solvent-based and water-borne coating was studied. The adhesion of coatings to substrates is one of the most important parameters for finishing quality and service life of wood coatings, while wetting properties are usually used to assess the quality of surfacing process and could also provide important information on the adhesion ability of coatings. Surface roughness, contact angle of coatings and water as well as adhesion strength of coatings were tested on differently prepared (face milled, sanded and UV irradiated) samples of unmodified and thermally modified ash and hornbeam wood. Surface roughness was measured with stylus-type profilometer over the traverse of 12.5 mm and with a cut-off value of 2.5. Contact angle was measured using the sessile drop method 2 s, 10 s and 30 s after the application of the liquid drop on the sample surface, and adhesion strength was measured according to ASTM D4541. Results showed that sanding of hornbeam and ash wood resulted in the least rough surface compared to the face milled and UV irradiated surface. Contact angles of the water-borne coating were on average three times higher than the contact angles of the solvent-based coating. Sanding the surface of hornbeam and ash samples increased the adhesive strength in relation to the face milled surface, while UV irradiation of the sanded surface decreased the adhesive strength of most samples coated with solvent-based coating., U radu je istraživan utjecaj čeonog blanjanja, brušenja i UV zračenja grabovine i jasenovine na kvašenje i adhezivnu čvrstoću premaza na bazi organskih otapala i vodenog premaza. Adhezija premaza jedan je od najvažnijih parametara za kvalitetu površinske obrade i trajnost premaza za drvo, dok svojstva kvašenja obično služe za ocjenu kvalitete nanošenja i adhezije premaza. Na različito pripremljenim uzorcima (obrađenim čeonim blanjanjem, brušenjem ili UV zračenjem) nemodificirane i toplinski modificirane grabovine i jasenovine ispitivana je hrapavost, kontaktni kut premaza i vode te adhezivna čvrstoća premaza. Hrapavost površine mjerena je profilometrom na duljini vrednovanja 12,5 mm, uz referentnu duljinu od 2,5 mm. Kontaktni kut mjeren je metodom s kapljicom, i to 2 s, 10 s i 30 s nakon nanošenja kapljice na površinu uzorka, a adhezivna čvrstoća određivana je prema normi ASTM D4541. Rezultati su pokazali da je brušenje grabovine i jasenovine rezultiralo najmanje hrapavom površinom u usporedbi s čeono blanjanom i UV zračenom površinom. Kontaktni kutovi vodenog premaza bili su u prosjeku tri puta veći od kontaktnih kutova premaza na bazi organskih otapala. Brušenjem površine uzoraka grabovine i jasenovine adhezivna je čvrstoća postala veća od čvrstoće čeono blanjanih površina, dok je UV zračenjem na brušenim površinama većine uzoraka smanjena adhezivna čvrstoća premaza na bazi organskih otapala.

The current research is devoted to fabricating a superhydrophobic coating on alumina surfaces via a facile one-step electrospinning technique. The wettability properties of the as-prepared coating were investigated. The polymeric coatings exhibited a water contact angle (WCA) of about 152° ± 3 and a sliding angle (SA) is 4 ± 2°. However, a WCA of 154 ± 2° and a SA of 3 ± 2° were recorded after the addition of Al2O3 nanoparticles. The wettability of the prepared coatings has also been inspected after exposure to intense UV irradiation of 0.89 W/(m2 nm) and high-temperature degree of 60 °C, for 500 h. It was found that the measured WCA and water contact hysteresis (WCAH) for the poly(vinylidene fluoride-co-hexafluoropropylene) PVDF-HFP/Al2O3 nanocomposite 150 ± 1° and 10 ± 1° compared with 122 ± 4° and 22 ± 4° of pure PVDF-HFP, respectively. The morphology of the superhydrophobic coating was explored, illustrating the construction of a beaded fiber structure. The surface roughness of the fabricated super water-repellent coatings was recorded using an atomic force microscope (AFM). The electrochemical behavior of superhydrophobic coating was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5 wt % NaCl solution before and after exposure to UV radiation. The research outcomes promote a one-step fabrication technique to prepare polymeric superhydrophobic coatings with good resistance for corrosion and degradation under UV irradiation.

The charging and levitation of particles using UV irradiation in an upward electric field were investigated. Glass beads with a mass median diameter of 61 μm were used for the experiments. The particle layers formed on a glass plate were irradiated by UV light with wavelengths ranging from 240 to 400 nm. The particles in the top layer were positively charged by photoemission and levitated by the electrostatic forces. The fluxes and motions of the levitated particles were analyzed by digital processing of the images obtained with a high-speed camera. The charge of each levitated particle was determined by fitting the results calculated using the equation of motion to the experimentally obtained particle motion. The charge of the particles beginning to be levitated was determined by the force balance and thus was not affected by the UV irradiance. The positive charge of the levitated particles could be increased by continuous photoemission from the particles and decreased by the capture of photoelectrons emitted by other particles. Approximately 40% of the levitated particles descended because of the negative charge clouds formed by the photoemission from the particle layers and the levitated particles. Furthermore, in a second set of experiments, an upward electric field was applied after UV irradiation. In these experiments, the particles in the top layer were levitated after applying the electric field. These particles could be gain more excess charges than the particles for which the levitation was governed by the force balance.

Access to safe drinking water is essential yet threatened for many, with the United Nations highlighting the importance of providing clean water for all as one of their Sustainable Development Goals to be met by 2030. Provision of drinking water in India is of particular importance, as the majority of the population live in rural areas without sufficient access to water, leading to illnesses which could be easily prevented. The large population and land coverage of the country makes installing widespread centralised water treatment facilities to service all inhabitants extremely difficult, and many households rely on their own means of treating water. Traditional methods of point-of-use water treatment, such as filtration, chlorination and boiling all have limitations, meaning there is a need for finding an improved method. One of the best candidates for such an aim is to use solar driven heterogeneous photocatalysis, whereby a semiconductor material is used to facilitate the generation of reactive oxidising species (ROS), which destroy organic pollutants and pathogens contaminating the water, leading it to be disinfected and safe for human consumption. However, photocatalysis is often limited in its applications due to the reliance on titania (TiO₂) as the catalyst, which requires UV irradiation for efficient generation of the ROS species. Thus, if the material properties of titania can be enhanced through chemical and structural modifications, such that the system is activated by visible light, it will be a highly useful tool for use in rural settings. This is of particular importance as TiO₂ is inexpensive relative to many novel high functioning photocatalysts, such as those based on silver nanoparticles and other materials which are less abundant than Ti or O. It is also biologically and chemically inert, and is frequently produced on an industrial scale for many varied uses. Thus, building on the high efficiency of TiO₂ under UV irradiation with chemical modifications can help to create high functioning visible light-activated photocatalysts that are affordable and non-toxic, making them ideal for such an application. In this Thesis, work has been conducted to address the practical limitations of photo- catalytic water treatment, with the goal of making it suitable for implementing in rural areas on a local, decentralised scale. Field studies were conducted in India, hosted by the Indian Institute of Technology in Kharagpur, during which time catalyst materials were tested with real water samples under solar irradiation, to more closely replicate the conditions in which the treatment method would be used. This helped to build upon lab-scale testing, and highlight areas required for further optimisation. It was found that the catalysts studied (commercial P25 TiO₂ and a bismuth titanate material prepared by previous member of the Robertson research group, Dr Gylen Odling, referred to as BTO-TiO₂) were more successful at removing bacteria from the water samples than solar disinfection alone. However, it was also noticed that there was a significant loss of catalyst over the course of the investigations, and not all could be recaptured. In this study, the catalyst was immobilised on small glass beads, but the adhesion was not as robust as required for the level of use, and the coating would become damaged. Following these field investigations, the main limitations to practical photocatalytic water treatment were highlighted and motived the remaining work for this Thesis. One of the main concerns preventing implementation of such a technique is the difficulty in recapturing the nanopowder catalyst from the water once treatment has been completed. Typically, the catalyst is added as a slurry, which is beneficial for utilising the high surface area of the catalyst, but makes it very difficult to recapture and therefore reuse, as expensive microfilters or centrifuges would be required, adding costs and complexity to the process. The use of glass beads in the field studies improved this and simplified the set-up required, but improvements were still needed. In this work, focus has been given to improving immobilisation of the catalyst powder, primarily focusing on the use of glass as a substrate, whilst adjusting the structure to find a practical balance between costs, surface area, ease of use and robustness of the applied film. Studies were conducted which showed that mixing a suspension of the catalyst with a solution of tetraethyl orthosilicate helped to improve adhesion by forming SiO₂ during sintering, which acted as a glue to hold the catalyst to the surface more effectively. Further, glass chips were used which were formed from ground down used glass bottles, which were successful in replacing glass beads as a high surface area support with lower costs and without the need for intensive chemical pre-treatment to prepare the surface for coating. As well as improving practical aspects, studies were also conducted to explore methods for enhancing the photochemical properties of TiO₂, in order to increase the photocatalytic activity under the whole solar spectrum, not just the UV portion. Firstly, studies focused on attempts to make composites of zinc-iron oxide (ZnFe₂O₄) semiconductors with commercial P25 TiO₂. The synthesis involved adding zinc and iron precursor salts in a solution of ethylene glycol and water in the presence of P25 TiO₂ and either oxalic acid or ammonia to initiate the reaction. It was found that both acid and base methods led to a significant increase in visible light performance, with the base synthesis being the most simple to perform. However, the same high activity was not observed for tests performed under UV or simulated solar irradiation, where the performance was worsened relative to P25 TiO₂. Following this, a different approach was taken, whereby TiO₂ was synthesised in-situ in the presence of bismuth in a reverse-micelle sol-gel approach, in an attempt to build on the success of the BTO-TiO₂ material studied during field testing. This led to much better performance than the ZnFeO/TiO₂ composites, with excellent visible light activity, and UV activity similar to that of P25 TiO₂. The materials were also shown to be stable with repeated use. The materials did not however outperform BTO-TiO₂, which was prepared via a sequential ionic layer adsorption reaction (SILAR) route. SILAR methods have practical limitations that this work attempted to address, and therefore finding the right balance between simplicity of preparation, long-term stability, costs and performance is very important for finding materials suitable for the specific application of solar driven water treatment in rural areas.

The chemoresistive sensor response of nanoporous NiO films prepared by advanced gas deposition was investigated with and without simultaneous light irradiation, to detect nitrogen dioxide and acetone gases. The presented data show electrical responses presented as sensor resistance or relative changes in sensor resistance under selected environment conditions including UV-vis irradiation, humidity and selected target gases. The sensitivity towards nitrogen dioxide highly increased with the use of UV irradiation (275 nm) and simultaneous heating up to 150 °C. For acetone, neither reproducible nor improved responses were observed for 150 °C.

Networks consisting of randomly oriented carbon nanotubes (CNN) were investigated toward nitrogen dioxide detection by means of electrical and low-frequency noise measurements. UV-activation of CNN layers improved gas sensitivity and reduced the limit of detection, especially by employing 275 nm-LED. This data set includes DC resistance measurements and low-frequency noise spectra collected for CNN sensor reacting to target gas (nitrogen dioxide) under selected lighting conditions at room temperature.

Back-gated field-effect transistors with graphene channels (GFETs) were investigated toward organic vapors sensing. Two methods were used for sensing experiments including DC characteristics measurements and fluctuation-enhanced sensing by low-frequency noise studies. The data set consists of raw and modified data on GFET responses to acetonitrile, tetrahydrofuran, chloroform, and acetone - DC and noise responses. The combination of electrical measurements with fluctuation-enhanced sensing enable enhanced vapors detection and underlie mechanisms responsible for surface processes under UV irradiation of graphene channel.

The possible presence of plastic particles with diameters smaller than a µm in the aquatic environment raises widespread concern over their environmental impact. Therefore, it is important to understand whether and to what extent nanoplastics dispersed in water degrade under UV irradiation. To address this issue, we studied the effect of UV irradiation on monodisperse polystyrene (PS) latex particles (R=0.1-2.5 µm) and polydisperse polyethylene (PE) particles ( R=0.35 µm). All particles were found to fully degrade with a degradation rate of PS particles much faster than that of PE particles. Light scattering measurements showed that the molar mass of the particles decreased by more than 70% without changing the radius indicating that degradation mainly occurred within the particles through the release of organic molecules, see figure 1(top). The formation of hollow particles and a decrease of their size are confirmed with CLSM microscopy, see figure 1 (bottom) before their complete disappearance. TOC measurements showed that the degradation of PS particles lead to the complete conversion of all the initial organic carbon possibly into volatile products suggesting that the ultimate fate of PS nanoplastics and small microplastics after exposition to UV may no longer be in the aquatic environment. Please see the supplementary file for figure 1. Also see: https://micro2022.sciencesconf.org/426936/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Polymethylmethacrylate (PMMA) is commonly applied to microfluidic devices due to its excellent biocompatibility, high optical transparency, and suitability for mass production. Recently, various surface treatment methods have been reported to improve the wettability of polymers, which is directly related to adhesion. In this research, the effect of a UV irradiation technique and an IPA rinsing technique as surface treatments for PMMA is investigated regarding the water contact angle of the PMMA surface. PMMA sheets that were 1.62 mm thick and commercially available were exposed to UV light with four different exposure times. Significant decreases in the water contact angle were observed after exposure to UV light, and the lowered contact angles due to the UV irradiation increased over time. According to the measurement, the water contact angle is a function of UV exposure dose as well as storage time after UV exposure. We examined the effect of a IPA rinsing process after UV irradiation and observed an increase in the water contact angle.

The gas sensing properties of graphene back-gated field-effect transistor (GFET) sensors toward acetonitrile, tetrahydrofuran, and chloroform vapors were investigated with the focus on unfolding possible gas detection mechanisms. The FET configuration of the sensor device enabled gate voltage tuning for enhanced measurements of changes in DC electrical characteristics. Electrical measurements were combined with a fluctuation-enhanced sensing methodology and intermittent UV irradiation. Distinctly different features in 1/f noise spectra for the organic gases measured under UV irradiation and in the dark were observed. The most intense response observed for tetrahydrofuran prompted the decomposition of the DC characteristic, revealing the photoconductive and photogating effect occurring in the graphene channel with the dominance of the latter. Our observations shed light on understanding surface processes at the interface between graphene and volatile organic compounds for graphene-based sensors in ambient conditions that yield enhanced sensitivity and selectivity.

Polycarbonate (PC)-ZnO films with different percentages of ZnO were prepared by a solution stirring technique and subjected to ultraviolet (UV; λ = 254 nm) irradiation. Structural parameters of the samples and the effects of UV irradiation on the surface properties of the PC and PC-ZnO nanocomposites were evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), water contact angle (WCA) measurements, and a Vickers microhardness (HV) tester. The XRD patterns of the nanocomposite films were found to show an increase in crystallinity with the increasing ZnO nanoparticles percentage. The WCA was found to be reduced from 90° to 17° after 15 h of UV irradiation, which could be ascribed to the oxidation of the surface of the samples during the irradiation and exposure of the ZnO nanoparticles, a result that is also supported by the obtained XPS data. The microhardness value of the PC-ZnO films including 30 wt.% ZnO enhanced considerably after UV radiation, which can also be attributed to the exposition of the ZnO nanoparticles after photodegradation of the PC superficial layer of the nanocomposite films.

The paper studies issues related to physicochemical and chemical techniques for the modification of wood-polymer composites with a thermoplastic polymer matrix (WPCs) to improve their physical and mechanical properties. The physicochemical modification was performed by photochemical crosslinking with the exposure of WPC specimens to UV irradiation. Chemical modification was performed by introducing benzoyl peroxide into the material composition, leading to chemical crosslinking of polyethylene macromolecules of the WPC polymer matrix. As a result of the study, quantitative characteristics of the effect of the benzoyl peroxide content in the composite, as well as the WPC specimen UV irradiation intensity and duration on the basic physical and mechanical properties of the material have been obtained. The efficiency of physicochemical techniques for modifying WPCs has been estimated by changing the specimen properties such as Brinell hardness, water absorption, and impact strength. It has been found that the Brinell hardness increases by 80 % as compared to unmodified WPC specimens. Effective modification of wood-polymer composites with polymer matrices based on high-density polyethylene may lead to a significant improvement in the quality of products made of these materials. © 2021 Trans Tech Publications Ltd, Switzerland.

UV radiation is one of the main contributors to skin photoaging by promoting the accumulation of cellular senescence, which in turn induces a proinflammatory and tissue-degrading state that favors skin aging. The members of the sirtuin family of NAD + -dependent enzymes play an anti-senescence role and their activation suggests a promising approach for preventing UV-induced senescence in the treatment of skin aging. A two-step screening designed to identify compounds able to protect cells from UV-induced senescence through sirtuin activation identified shikimic acid (SA), a metabolic intermediate in many organisms, as a bona-fide candidate. The protective effects of SA against senescence were dependent on specific activation of SIRT1 as the effect was abrogated by the SIRT1 inhibitor EX-527. Upon UV irradiation SA induced S-phase accumulation and a decrease in p16 INK4A expression but did not protect against DNA damage or increased polyploidies. In contrast, SA reverted misfolded protein accumulation upon senescence, an effect that was abrogated by EX-527. Consistently, SA induced an increase in the levels of the chaperone BiP, resulting in a downregulation of unfolded protein response (UPR) signaling and UPR-dependent autophagy, avoiding their abnormal hyperactivation during senescence. SA did not directly activate SIRT1 in vitro, suggesting that SIRT1 is a downstream effector of SA signaling specifically in the response to cellular senescence. Our study not only uncovers a shikimic acid/SIRT1 signaling pathway that prevents cellular senescence, but also reinforces the role of sirtuins as key regulators of cell proteostasis.

UV irradiation is known to cause harmful effects on microorganisms. As the result, microorganisms have developed protection against exposure to harmful UV irradiation. We suggested that resistance to UV might be specific characteristic of certain genera of microorganisms. So, the aim of the work is to assess whether there is a correlation between UV resistance and the taxonomic position of microorganisms or is it the adaptation of cells to extreme conditions. There were studied 67 strains from extreme ecosystems (phytocenoses and оrnithogenic soil of the Antarctic, hypersaline ecosystems of the Crimea and the Dead Sea, the lake Baikal). Sequence of 16S rRNA genes, phylogenetic analysis and UV resistance were performed according to standard procedures. Phylogenetic analysis revealed live representatives of the following genera: Pseudomonas, Serratia, Rheinheimera, Aeromonas, Buttiauxella, Brevundimonas, Sphingomonas, Sphingopyxis, Dermacoccus, Frondihabitans, Microbacterium, Rhodococcus, Janthinobacterium, Arthrobacter, Micrococcus, Kocuria, Sphingobacterium, Flavobacterium, Chryseobacterium, Bacillus, Staphylococcus, Paenibacillus, Sporosarcina. Gram-positive bacteria were significantly more resistant to UV irradiation (LD99.99 750–1400 J/m2). Gram-negative had lower resistance (LD99.99 35–150 J/m2). Most pigmented strains were more resistant to UV than non-pigmented ones. According to the values of lethal doses of UV irradiation we suggest that investigated microorganisms have effective mechanisms to repair DNA damages. Resistance of microorganisms to UV, as a rule, was not related to the ecological features of their habitat. Thus, there is a correlation between the resistance of microorganisms to UV irradiation and their taxonomic position, which allows to consider UV resistance as a diagnostic feature at the genus level.

A simple, equipment-free, direct fluorometric method, employing paper-based analytical devices (PADs) as sensors, for the selective determination of quinine (QN) is described herein. The suggested analytical method exploits the fluorescence emission of QN without any chemical reaction after the appropriate pH adjustment with nitric acid, at room temperature, on the surface of a paper device with the application of a UV lamp at 365 nm. The devices crafted had a low cost and were manufactured with chromatographic paper and wax barriers, and the analytical protocol followed was extremely easy for the analyst and required no laboratory instrumentation. According to the methodology, the user must place the sample on the detection area of the paper and read with a smartphone the fluorescence emitted by the QN molecules. Many chemical parameters were optimized, and a study of interfering ions present in soft drink samples was carried out. Additionally, the chemical stability of these paper devices was considered in various maintenance conditions with good results. The detection limit calculated as 3.3 S/N was 3.6 mg L−1, and the precision of the method was satisfactory, being from 3.1% (intra-day) to 8.8% (inter-day). Soft drink samples were successfully analyzed and compared with a fluorescence method.

Sunlight is essential for humans. However, sunlight can be the source of several disadvantageous effects and illnesses, e.g., skin aging, sunburn, and skin cancer. Textiles with functional protective effects can counteract these problems. In the current research, knitted fabrics were produced from Lyocell yarns spin-doped with the inorganic UV absorber titanium dioxide TiO2. Lyocell yarns without TiO2 were used as reference materials. The produced knitted fabrics were dyed with different dyestuffs to improve the protective properties against UV light and infrared light. The protective properties are determined by optical spectroscopy in an arrangement of diffusive transmission. With the two dyestuffs Drimaren Yellow HF-CD and Solophenyl Bordeaux 3BLE, dyes were determined which complete UV protection and additionally reduce transmission in the near-IR range (700 nm to 1000 nm). TiO2 in the fibers enhanced this effect. In the UV range (280 nm to 400 nm), the transmission was almost zero with both dyes. Overall, the Lyocell samples containing TiO2 exhibit less sensitivity to abrasion and a UV protective effect after washing can be still determined. The weight loss after the abrasion test for these samples is quite low with only around 8.5 wt-% (10,000 rubbing cycles in the Martindale device). It is concluded that the right choice of dye can improve the protective effect of textiles against various types of radiation. Lyocell fiber-based textiles are suitable for the production of summer clothing due to their good moisture management. Compared to other radiation protective materials based on coating application, the presented solution is advantageous, because the textile properties of the realized products are still present. For this, a direct transfer to clothing application and use in apparel is easily possible. This study can be seen as the first proof-of-concept for the future development of light-protective clothing products.

Mulching technology has created a major problem of agricultural plastic pollution. This is because the mulch is severely degraded by UV (ultraviolet) irradiation and the mechanical properties deteriorate, which makes mechanical recycling or manual recycling difficult. This study was conducted on m-LLDPE (metallocene linear low-density polyethylene) mulch films. The difference in mechanical properties of specimens in the TD (transverse direction) and PD (parallel direction) was investigated, and the changes in the mechanical properties after UV irradiation were compared. Finally, an initial mulch mechanical property evaluation model was developed to adapt to different recovery machines and crop agronomic requirements. The results suggest that the mechanical properties of m-LLDPE mulch films were strongly influenced by the film thickness, and also showed directional differences in tensile and tear properties. After UV irradiation, the mechanical properties of the specimens were enhanced after a short period of time, but the overall trend was a non-linear decay which gradually slowed down with time.

A strain of Staphylococcus simulans D14 (S. simulans D14) showed the highest nitrate reductase activity (NRA) of 4.52 mM NO2−/mg dry weight by the spectrophotometric method, which was screened from traditional Chinese sausage. When the UV mutagenesis time was 25 s, the positive mutation rate was the highest at 26.60%. The NRA of the obtained positive mutant UV-11 was 9.21 mM NO2−/mg dry weight, and the activity was found to be 1.04-fold higher than that of the original strain S. simulans D14. A Plackett–Burman design (PBD) was employed to screen the significant variables pH, KNO3 (%) and incubation time (h), and response surface methodology (RSM) was used to optimize the significant variables using a Box–Behnken design (BBD). The results showed that the NRA of S. simulans UV-11 was 15.22 mM NO2−/mg dry weight under optimum conditions of 37 °C, pH 6.5, incubation time 15 h, KNO3 0.045%, NaCl 5%, NaNO2 0.015%, peptone 1%, and D–mannitol 1%, which increased by 65.2% compared with the unoptimized medium. Natural curing agents (containing 107 CFU/g S. simulans UV-11 under optimal conditions and 1.40% celery powder, T2) were added to the cured meat model. T2 produced significantly lighter and redder signals than the control group (C) and the addition of 150 ppm NaNO2 group (T1). The thiobarbituric acid reactive substance (TBARS) of T2 was 2.30 mg malonaldehyde/kg product and residual nitrite of T2 was 7.1 ppm after 14 days of storage,which were lower than those groups of C and T1. Taking into account the results of cured meat models, S. simulans UV-11 could be selected as a potential starter culture for the processing of natural meat products.

The COVID-19 pandemic draws much attention to virus inactivation since the SARS-CoV-2 was detected in miscellaneous environments and the wastewater can be a potential transmitting pathway. UV irradiation, ozonation and chlorination are widely used disinfection processes in water treatment. In this review, the mechanisms and applications of three disinfection processes are introduced, and their inactivation effects on virus as well as other microorganisms are compared and discussed. The resistance of viruses to UV irradiation is generally stronger than that of bacteria. 4-log inactivation of bacteria can be easily obtained within a UV dose of 10 ​mJ/cm2. However, the doses to reach the same virus removal rate vary greatly from 10 to 140 ​mJ/cm2. The coronaviruses have even stronger UV resistance. Comparatively, ozonation and chlorination are effective methods to inactivate viruses, and the CT values of 4-log removal for most viruses concerned are lower than 1 ​mg·min/L and 10 ​mg·min/L, respectively. Protozoa, fungal spores and bacterial spores are more resistant to disinfection. Temperature, pH, organic matters, turbidity and other parameters all have influences on the disinfection. With a 10 ​°C decrease in temperature, the CT value required for certain removal rates doubles. Generally low pH promotes disinfection and high pH is against it. In drinking water and wastewater treatment process, the resistance properties of microorganisms and other influence parameters should be taken into consideration when choosing disinfection technologies.

UV emiciler UV ışınlarının zararlı etkilerini azaltmak ve malzemelerin özelliklerinin yeterince korunmasını sağlamak için kullanılır. UV ışınlarına karşı koruma sağlamak için, UV emici moleküllerden biri, foto fiziksel bir işlemde daha az enerji sağlayan radyasyon enerjisini termal enerjiye birleştirebilir. TiO2, CeO2 ve ZnO, UV koruyucu özelliklere sahip inorganik bileşiklerdir. Bu bileşiklerin bazıları renklendirildiği için kullanımları sınırlıdır. Bor nitrür nano tabakaları (BNNS’ler), bu inorganik bileşiklere alternatif UV inhibitörleridir. Bu çalışmada BNNS / PVB çok katmanlı ince filmler, daldırarak kaplama yöntemi kullanılarak cam şişelerin korunması için üretilmiştir. Hem kaplanmış hem de kaplanmamış şişedeki Riviera zeytinyağı (RO-yağı) örnekleri farklı zamanlarda (75, 170, 360 ve 720 saat) UV ışınlamasına maruz bırakılmıştır. Farklı zamanlarda UV ışınlamasından sonra, RO-yağındaki toplam fenol ve antioksidan içerikleri Folin Ciacalteu ve DPPH yöntemleri ile belirlenmiştir. UV ışınlamasından sonra RO-yağının renk değişimi UV görünür spektrofotometre ile belirlenmiştir. Ultraviyole bölgesindeki spesifik emilim katsayıları K232 ve K270 (spesifik yok olma), bozunma sonrası RO-yağının oksidasyon aşamasını tahmin etmek için ölçülmüştür. UV ışınlamasından sonra RO-yağının serbest yağ asidi (FFA) titrasyon yöntemi ile belirlenmiştir. Analiz sonuçlarına göre, RO-yağın asitlik değerleri 720 saatlik UV’den sonra kaplanmamış cam şişeye kıyasla 20 kez korunmuştur. BNNSs/PVB kaplama ayrıca, uzun süreli UV ışınlaması altında RO yağlarının toplam fenol, antioksidan içerikleri ve oksidasyon durumunun korunmasında etkili olmuştur., UV absorbers are used to reduce the harmful effects of UV rays and to ensure that the properties of the materials are adequately protected. To protect against UV rays, one of the UV absorber molecules can reduce the combined energy of radiation to thermal energy that provides less energy in a photophysical process. Inorganic materials such as metal oxide semiconductors can effectively absorb UV irradiation and exhibit good heat-resistance properties. TiO2, CeO2, and ZnO are inorganic compounds with UV protective properties. Since some of these compounds are colored, their use is limited. Boron nitride nanosheets (BNNSs) are alternative UV inhibitors to these inorganic compounds. In this study BNNSs/PVB multilayer thin films were produced for the protection of glass packages using the dip-coating method. Riviera olive oil (RO-oil) samples in the both coated and uncoated bottle were exposed to UV irradiation for different times (75, 170, 360 and 720 hours). After the UV irradiation at different times, the total phenol and antioxidant contents in RO-oil were determined by Folin Ciacalteu and DPPH methods. The color change of RO-oil after UV irradiation was determined by UV visible spectrophotometer. Specific absorption coefficients K232 and K270 in the ultraviolet region were measured to determine the oxidation degree of RO-oil after degradation. Free fatty acid (FFA) of RO-oil after UV irradiation was determined by the titration method. According to the results of the analysis, the acidity values of RO-oil were preserved 20 times compared to the uncoated glass bottle after 720 hours UV. BNNSs/PVB coating was also effective in preserving total phenol, antioxidant contents and oxidation state of RO-oils under long term UV irradiation.

Whey proteins are widely used as ingredients in the form of aggregates to obtain certain functionalities in food applications. The aim of this study was to understand how UV illumination generates aggregates of α-lactalbumin (α-LA) as an alternative to heat treatments traditionally used for industrial production of protein aggregates. Absorption of UV light by α-LA caused cleavage of disulfide bonds and release of thiol groups, which resulted in primarily disulfide-mediated aggregation. This process mediated efficient aggregation with up to 98% monomer conversion into aggregates through formation of intermolecular disulfide bonds, while only minor levels of non-reducible cross-links were observed. SDS-PAGE analysis revealed that illumination led to formation of dimeric, trimeric and oligomeric forms of α-LA. LC-MS/MS analysis showed that all of the four native disulfide bonds in α-LA were cleaved by UV illumination but to different extents, and the extent of cleavage was found to be higher in the absence of calcium. Seventeen different non-native disulfides were formed after 24 h of UV illumination. Two di-tyrosine bonds were identified (Tyr103-Tyr103 and Tyr36-Tyr103) alongside di-tryptophan (Trp118-Trp118) and tyrosine-tryptophan (Tyr50-Trp60) cross-links. In addition, Trp60, Trp118, Cys73, Cys91, Cys120, Phe80, Met90, His68 and His107 were found to be oxidized up to 12% as compared to a non-illuminated control. Our work illustrates that light exposure can be used for generation of α-LA aggregates, but optimization of the illumination conditions is required to reduce oxidative damage to Trp, Cys, Phe, Met and His residues.

Riboflavin (RF) was considered to be possessed of photoactivity to generate reactive oxygen species (ROS) under ultraviolet (UV) light, which is thought to be a favorable antibacterial candidate. Herein, RF was incorporated into chitosan (CS) coatings and treated under UV with different exposure times (2, 4, and 6 h) to improve the physicochemical and antibacterial properties. The results showed that the light transmittance and antibacterial performance of chitosan coatings gradually increased with the extension of the UV irradiation time. The antibacterial ability of chitosan coatings correlated with the generation of ROS: ∙OH and H2O2, which achieved 1549.08 and 95.48 μg/g, respectively, after 6 h irradiation. Furthermore, the chitosan coatings with UV irradiation also reduced the pH value, total volatile basic nitrogen (TVB-N), ΔE, and total viable counts (TVC) and improved sensory attributes of pork. In conclusion, the UV irradiated chitosan coatings could be used as an environmentally friendly antimicrobial packaging material to effectively delay the spoilage of pork, maintain its sensory quality and prolong its shelf life.

A photochemical treatment with UV multi-wavelength irradiation was applied to investigate the degradation of the saponins mixture obtained from alfalfa leaves. The photo-degradation was studied in an aqueous solution at a pH range of 4–7 and temperature range of 20–80 °C. The samples were irradiated for 80 min using a mid-pressure mercury lamp with emission wavelengths between 250 and 740 nm. The dependence of the absorbed radiation on the concentration of alfalfa saponins was evaluated, and a linear dependence was found for the range of concentrations experimented throughout the photo-degradation. The alfalfa saponins mixture absorbed radiation between 470 and 610 nm with a maximum absorption peak at 543 nm. This means that any lamp emitting within this wavelength range could produce some degree of photo-degradation. A reaction mechanism was proposed, matching the experimental pseudo-first-order kinetic model that best fitted the evolution of the saponins mixture concentration. The photo-degradation rate was found to increase with increasing temperature and decreasing pH value, causing a reduction of 80% in the concentration of the alfalfa saponins mixture after 80 min at pH 4 and 80 °C.

PLA and its blends are the most extensively used materials for various biomedical applications such as scaffolds, implants, and other medical devices. The most extensively used method for tubular scaffold fabrication is by using the extrusion process. However, PLA scaffolds show limitations such as low mechanical strength as compared to metallic scaffolds and inferior bioactivities, limiting their clinical application. Thus, in order to improve the mechanical properties of tubular scaffolds, they were biaxially expanded, wherein the bioactivity can be improved by surface modifications using UV treatment. However, detailed studies are needed to study the effect of UV irradiation on the surface properties of biaxially expanded scaffolds. In this work, tubular scaffolds were fabricated using a novel single-step biaxial expansion process, and the surface properties of the tubular scaffolds after different durations of UV irradiation were evaluated. The results show that changes in the surface wettability of scaffolds were observed after 2 min of UV exposure, and wettability increased with the increased duration of UV exposure. FTIR and XPS results were in conjunction and showed the formation of oxygen-rich functional groups with the increased UV irradiation of the surface. AFM showed increased surface roughness with the increase in UV duration. However, it was observed that scaffold crystallinity first increased and then decreased with the UV exposure. This study provides a new and detailed insight into the surface modification of the PLA scaffolds using UV exposure.

Inactivated vaccines are promising tools for tackling the COVID-19 pandemic. We applied several protocols for SARS-CoV-2 inactivation (by β-propiolactone, formaldehyde, and UV radiation) and examined the morphology of viral spikes, protein composition of the preparations, and their immunoreactivity in ELISA using two panels of sera collected from convalescents and people vaccinated by Sputnik V. Transmission electron microscopy (TEM) allowed us to distinguish wider flail-like spikes (supposedly the S-protein’s pre-fusion conformation) from narrower needle-like ones (the post-fusion state). While the flails were present in all preparations studied, the needles were highly abundant in the β-propiolactone-inactivated samples only. Structural proteins S, N, and M of SARS-CoV-2 were detected via mass spectrometry. Formaldehyde and UV-inactivated samples demonstrated the highest affinity/immunoreactivity against the convalescent sera, while β-propiolactone (1:2000, 36 h) and UV-inactivated ones were more active against the sera of people vaccinated with Sputnik V. A higher concentration of β-propiolactone (1:1000, 2 h) led to a loss of antigenic affinity for both serum panels. Thus, although we did not analyze native SARS-CoV-2 for biosafety reasons, our comparative approach helped to exclude some destructive inactivation conditions and select suitable variants for future animal research. We believe that TEM is a valuable tool for inactivated COVID-19 vaccine quality control during the downstream manufacturing process.

Photocatalytic coatings have potential as an air purifying technology for removal of pollutants such as NOx gases, which are converted into and immobilized as nitrate via photo-oxidation. This work is an investigation of the photocatalytic conversion of nitrite into nitrate in the aqueous phase. The study of this reaction is important to understand the mechanism through which the immobilization of the NOx species as nitrates takes place during NOx conversion, especially in humid environments. We investigate the photocatalytic performance of TiO2 nanoparticles (Aeroxide® P25) and the corresponding photocatalytic coatings prepared using acrylic binder (TiO2 NP-acrylic) towards the photo-conversion of nitrite. The combination of a simple colorimetric method (Griess test) for nitrite quantification and UV–vis spectroscopy for nitrite and nitrate analysis is shown to be a useful method for monitoring the nitrite conversion. Photocatalytic tests with suspended TiO2 nanoparticles show that the nitrite conversion benefits from lower pH, higher temperature and higher concentration of the photocatalyst. The advantage of lower pH is attributed to electrostatic attraction between TiO2 with adsorbed H3O+ and NO2−, which facilitates transport of nitrite to the active surface. When the photocatalyst is immobilized in a coating the factor of primary significance is the pigment volume concentration relative to critical pigment volume concentration (λ), as the nitrite conversion increases linearly with λ in the range 0.6–1.2. This is attributed to the creation of a more porous structure that facilitates the access of nitrite and light to the active TiO2 surface sites.

Shelf life of peanuts is determined by their susceptibility to lipid oxidation. However, oxidation stability tests require accelerated conditions to speed up oxidation processes. This work aimed to test the use of UV radiation to accelerate the oxidation in peanuts. Shelled and fried peanuts were irradiated for 3 and 7 days, respectively with a UV lamp. The content of fatty acids, tocopherols, and volatile compounds was determined followed by colour and sensory properties of samples. Obtained results were compared with samples heated for 2 months at 70 °C in an oven. Tocopherol content showed oxidation process had just started after 3 days of UV irradiation. Moreover, aldehydes content increased 8.40 times and 11.77 times at 3 days and 7 days, respectively. Aroma, odour, sweetness scores, and a* value of peanuts were lower and permanency and rancity scores were higher after the oxidation process. Thermal treatment showed an increase in colour and b* value and a reduction in a crunchiness score highlighting temperature possible causes chemical changes which are not related to the oxidation process. Acceleration of oxidation with UV radiation can be used to study peanuts oxidation with less impact on sample colour and crunchiness when the sensorial analysis was performed. The authors would like to acknowledge the Packaging, Transport and Logistics Research Center (ITENE) and the Generalitat Valenciana (FEDEGENT/2018/021) for their financial support.

The transmission of pathogens via surfaces poses a major health problem, particularly in hospital environments. Antimicrobial surfaces can interrupt the path of spread, while photocatalytically active titanium dioxide (TiO2) nanoparticles have emerged as an additive for creating antimicrobial materials. Irradiation of such particles with ultraviolet (UV) light leads to the formation of reactive oxygen species that can inactivate bacteria. The aim of this research was to incorporate TiO2 nanoparticles into a cellulose-reinforced melamine-formaldehyde resin (MF) to obtain a photocatalytic antimicrobial thermoset, to be used, for example, for device enclosures or tableware. To this end, composites of MF with 5, 10, 15, and 20 wt% TiO2 were produced by ultrasonication and hot pressing. The incorporation of TiO2 resulted in a small decrease in tensile strength and little to no decrease in Shore D hardness, but a statistically significant decrease in the water contact angle. After 48 h of UV irradiation, a statistically significant decrease in tensile strength for samples with 0 and 10 wt% TiO2 was measured but with no statistically significant differences in Shore D hardness, although a statistically significant increase in surface hydrophilicity was measured. Accelerated methylene blue (MB) degradation was measured during a further 2.5 h of UV irradiation and MB concentrations of 12% or less could be achieved. Samples containing 0, 10, and 20 wt% TiO2 were investigated for long-term UV stability and antimicrobial activity. Fourier-transform infrared spectroscopy revealed no changes in the chemical structure of the polymer, due to the incorporation of TiO2, but changes were detected after 500 h of irradiation, indicating material degradation. Specimens pre-irradiated with UV for 48 h showed a total reduction in Escherichia coli when exposed to UV irradiation.

Highlights • A comprehensive kinetic model was developed for 7+ AOPs with 540+ reactions. • Intermediates were considered for the tuning and validation of the model. • The effect of anions on the reactivity followed PDS/CuO > H2O2/UV > other PDS/PMS. • Anions affected the importance of different reactions based on sensitivity analysis. • This model can be easily applied to many complex AOPs and different contaminants., As one of the most powerful approaches to mechanistically understanding complex chemical reactions and performing simulations or predictions, kinetic modeling has been widely used to investigate advanced oxidation processes (AOPs). However, most of the available models are built based on limited systems or reaction mechanisms so they cannot be readily extended to other systems or reaction conditions. To overcome such limitations, this study developed a comprehensive model on phenol oxidation using over 540 reactions, covering the most common reaction mechanisms in nine AOPs—four peroxymonosulfate (PMS), four peroxydisulfate (PDS), and one H2O2 systems—and considering product formation and the effects of co-existing anions (chloride, bromide, and carbonate). Existing models in the literature were first gathered and then revised by correcting inaccurately used reactions and adding other necessary reactions. Extensive model tuning and validation were next conducted by fitting the model against experimental data from both this study and the literature. The effects of anions were found to follow PDS/CuO > H2O2/UV > other PDS or PMS systems. Halogenated organic byproducts were mainly observed in the PMS systems in the presence of halides. Most of the 543 reactions were found to be important based on the sensitivity analysis, with some anions-involved reactions being among the most important, which explained why these anions substantially altered some of the reaction systems. With this comprehensive model, a deep understanding and reliable prediction can be made for the oxidation of phenol (and likely other phenolic compounds) in systems containing one or more of the above AOPs., Graphical abstract Image, graphical abstract

In this paper, the photocatalytic degradation of organic pollutants was investigated using Ag/ZnS nanoparticles at different noble metal loadings. The photocatalysts were prepared at room temperature by two different methods: photodeposition and chemical reduction. The obtained samples were characterized by Specific surface area measurement, X-ray photoelectron spectroscopy, X-ray Powder diffraction, ultraviolet–visible diffuse reflectance and Raman spectroscopy. The X-ray photoelectron spectroscopy spectra showed that Ag is present on ZnS surface as intermediate state between nanostructured Ag0 and Ag2O. Moreover, the addition of silver caused a significant change of the absorption spectrum of bare ZnS, resulting in higher absorbance in the visible region, due to the Ag surface plasmon band. Methylene blue (MB) was used to evaluate the photocatalytic activity of the prepared samples. The best photocatalytic activity was observed using the sample at 0.1 wt% Ag loading prepared by chemical reduction method. In particular, the almost complete MB degradation was achieved using UV-LEDs as light sources and 6 g L−1 of catalyst dosage. Finally, the optimized photocatalyst was also effective in the degradation of phenol in aqueous solution under UV irradiation.

As a part of the European Space Agency mission "EXPOSE-R2" on the International Space Station (ISS), the BIOMEX (Biology and Mars Experiment) experiment investigates the habitability of Mars and the limits of life. In preparation for the mission, experimental verification tests and scientific verification tests simulating different combinations of abiotic space- and Mars-like conditions were performed to analyze the resistance of a range of model organisms. The simulated abiotic space- and Mars-stressors were extreme temperatures, vacuum, and Mars-like surface ultraviolet (UV) irradiation in different atmospheres. We present for the first time simulated space exposure data of mosses using plantlets of the bryophyte genus Grimmia, which is adapted to high altitudinal extreme abiotic conditions at the Swiss Alps. Our preflight tests showed that severe UVR

Humic acid (HA) has complex molecular structure and is capable of adsorption, ion exchange, and chelation with organic and inorganic pollutants in water bodies, worsening water quality and jeopardizing human health and ecological environment. How to effectively remove HA from water is one of the research focuses of this paper. In this study, the UV-activated sodium perborate (SPB) synergistic system (UV/SPB) was established to eliminate HA in water. The effects of initial HA concentration, SPB dose, and initial pH value on the HA elimination were determined, and the main mechanisms of the synergy and HA degradation were explored. The outcomes show that the HA elimination ratio by the sole UV and only SPB system were only 0.5% and 1.5%, respectively. The HA removal of UV/SPB reached 88.8%, which can remove HA more effectively than other systems. Free radical masking experiment proved that hydroxyl radical produced by SPB activation is the main active substance for HA removal. The results of UV-vis absorption spectrum, absorbance ratio, specific UV absorbance, and excitation–emission matrix spectroscopy verified that the UV/SPB system can effectively decompose and mineralize HA.

Poly(ethylene glycol) diacrylate (PEGDA) microgels with tuneable size and porosity find applications as extracellular matrix mimics for tissue-engineering scaffolds, biosensors, and drug carriers. Monodispersed PEGDA microgels were produced by modular droplet microfluidics using the dispersed phase with 49–99 wt% PEGDA, 1 wt% Darocur 2959, and 0–50 wt% water, while the continuous phase was 3.5 wt% silicone-based surfactant dissolved in silicone oil. Pure PEGDA droplets were fully cured within 60 s at the UV light intensity of 75 mW/cm2. The droplets with higher water content required more time for curing. Due to oxygen inhibition, the polymerisation started in the droplet centre and advanced towards the edge, leading to a temporary solid core/liquid shell morphology, confirmed by tracking the Brownian motion of fluorescent latex nanoparticles within a droplet. A volumetric shrinkage during polymerisation was 1–4% for pure PEGDA droplets and 20–32% for the droplets containing 10–40 wt% water. The particle volume increased by 36–50% after swelling in deionised water. The surface smoothness and sphericity of the particles decreased with increasing water content in the dispersed phase. The porosity of swollen particles was controlled from 29.7% to 41.6% by changing the water content in the dispersed phase from 10 wt% to 40 wt%.

Atmospheric particulate matter (PM) contains various chemicals, some of which generate in vivo reactive oxygen species (ROS). Owing to their high reactivity and oxidation ability, ROS can cause various diseases. To understand how atmospheric PM affects human health, we must clarify the PM components having oxidative potential (OP) leading to ROS production. According to previous studies, OP is exhibited by humic-like substances (HULIS) in atmospheric PM. However, the OP-dependence of the chemical structures of HULIS has not been clarified. Therefore, in this study, humic acid (HA, a model HULIS material) was exposed to ozone and ultraviolet (UV) irradiation, and its OP and structures were evaluated before and after the reactions using dithiothreitol (DTT) assay and Fourier transform infrared (FT-IR), respectively. The OP of HA was more significantly increased by UV irradiation than by ozone exposure. FT-IR analysis showed an increased intensity of the C=O peak in the HA structure after UV irradiation, suggesting that the OP of HA was increased by a chemical change to a more quinone-like structure after irradiation.

We report the effects of ultraviolet (UV) irradiation and storage on the performance of ZnO-based inverted quantum-dot light-emitting diodes (QLEDs). The effects of UV irradiation on the electrical properties of ZnO nanoparticles (NPs) were investigated. We demonstrate that the charge balance was enhanced by improving the electron injection. The maximum external quantum efficiency (EQE) and power efficiency (PE) of QLEDs were increased by 26% and 143% after UV irradiation for 15 min. In addition, we investigated the storage stabilities of the inverted QLEDs. During the storage period, the electron current from ZnO gradually decreased, causing a reduction in the device current. However, the QLEDs demonstrated improvements in maximum EQE by 20.7% after two days of storage. Our analysis indicates that the suppression of exciton quenching at the interface of ZnO and quantum dots (QDs) during the storage period could result in the enhancement of EQE. This study provides a comprehension of the generally neglected factors, which could be conducive to the realization of high-efficiency and highly storage-stable practical applications.

Ultraviolet (UV) irradiation is an important risk factor in cataractogenesis. Lens epithelial cells (LECs), which are a highly metabolically active part of the lens, play an important role in UV-induced cataractogenesis. The purpose of this study was to characterize cell compounds such as nucleic acids, proteins, and lipids in human UV C-irradiated anterior lens capsules (LCs) with LECs, as well as to compare them with the control, non-irradiated LCs of patients without cataract, by using synchrotron radiation-based Fourier transform infrared (SR-FTIR) micro-spectroscopy. In order to understand the effect of the UV C on the LC bio-macromolecules in a context of cataractogenesis, we used the SR-FTIR micro-spectroscopy setup installed on the beamline MIRAS at the Spanish synchrotron light source ALBA, where measurements were set to achieve a single-cell resolution with high spectral stability and high photon flux. UV C irradiation of LCs resulted in a significant effect on protein conformation with protein formation of intramolecular parallel β-sheet structure, lower phosphate and carboxyl bands in fatty acids and amino acids, and oxidative stress markers with significant increase of lipid peroxidation and diminishment of the asymmetric CH3 band.

Thin films of transparent conductive Al doped ZnO (AZO) thin films were produced via sol-gel spin coating route. Structural, optical, and electrical properties were explored for several dopant concentrations. Formation of crystalline AZO was verified by X-ray Diffraction (XRD) Analysis and structural analysis were carried out later from the XRD data. Highest band gap of 3.67 eV was found for 2 mol % AZO thin films. The average transmittance was found to be 84.19% in the visible spectra for the corresponding thin films. 2 mol% AZO also exhibited a minimum resistivity of 2.05 Ω-cm with a maximum value of figure of merit. Prolonged UV irradiation was applied to 2 mol % AZO thin films prior to annealing. It significantly modified the surface morphology of the film and provided shielding near UVA (315–378 nm) spectrum. This also enhanced the conductivity of the thin film by 3-fold compared to non-UV treated sample and decreased optical band gap significantly., Thin film; Sol-gel; Optoelectronic; Burstein-moss effect; UV irradiation; UV blocking.

Due to the COVID19 pandemic, solutions to automate disinfection using UV-C combined with mobile robots are beginning to be explored. It has been proved that the use of these systems highly reduces the risk of contagion. However, its use in real applications is not being as rapid as it needs to be. One of the main market input barriers is the fear of degrading facilities. For this reason, it is crucial to perform a detailed study on the degradation effect of UV-C light on inert materials. This experimental study proves that, considering exposition times equivalent to several work years in hospital rooms, only the appearance of the material is affected, but not their mechanical functionalities. This relevant result could contribute to accelerate the deployment of these beneficial disinfection technologies. For that purpose, a colorimetry test, tensile strength test, and analysis of the surface microstructure were carried out. The results showed that polymers tend to turn yellow, while fabrics lose intensity depending on the color. Red is hardly affected by UV-C, but blue and green are. Thus, this study contributes to the identification of the best materials and colors to be used in rooms subjected to disinfection processes. In addition, it is shown how the surface microstructure of the materials is altered in most of the materials, but not the tensile strength of the fabrics. This research was partially funded by the Spanish Ministry of Science and Innovation under the contract COI-20201089 .

The research on emerging pollutants in wastewater has become a worldwide issue of increasing environmental concern, especially considering the growing interest in wastewater reuse. However, the latter implies additional post-treatment after the conventional activated sludge processes, in order to produce a safer effluent. Our work aimed at determining the efficiency of reducing the toxicity associated with organic micropollutants (OMPs) in secondary wastewater effluents, using 3 different post-treatment technologies (granular activated carbon (GAC), sand biofiltration and UV irradiation): in particular, target chemical analysis of the OMPs most commonly founded in wastewater was coupled with effect-based assays (estrogenicity and mutagenicity). While chemical analysis assessed satisfactory performances for all 3 technologies in the abatement of selected OMPs, biological assays evidenced another perspective: both GAC and sand biofilters were significantly able to make the estrogenic load plummet; however, the UV system was ineffective in estrogenicity abatement, and its effluent exhibited also a slight mutagenicity, likely due to photo-transformation by-products. These results indicate that a synergistic combination of chemical analysis and biological assays can drive to a proper gauging of post-treatment technologies, taking into account not only the removal of OMPs, but also their overall toxicity This work was conceived within a Short Term Scientific Mission (STSM) of the Water2020 Cost Action ES1202: Conceiving Wastewater Treatment in 2020 | Energetic, environmental and economic challenges. Authors from Universidade de Santiago de Compostela belong to the Galician Competitive Research Group GRC 2013-032 and to the CRETUS Strategic Partnership (AGRUP2015/02). All these programmes are co-funded by FEDER (UE) SI

UV radiation is one of the main contributors to skin photoaging by promoting the accumulation of cellular senescence, which in turn induces a proinflammatory and tissue-degrading state that favors skin aging. The members of the sirtuin family of NAD(+)-dependent enzymes play an anti-senescence role and their activation suggests a promising approach for preventing UV-induced senescence in the treatment of skin aging. A two-step screening designed to identify compounds able to protect cells from UV-induced senescence through sirtuin activation identified shikimic acid (SA), a metabolic intermediate in many organisms, as a bona-fide candidate. The protective effects of SA against senescence were dependent on specific activation of SIRT1 as the effect was abrogated by the SIRT1 inhibitor EX-527. Upon UV irradiation SA induced S-phase accumulation and a decrease in p16INK4A expression but did not protect against DNA damage or increased polyploidies. In contrast, SA reverted misfolded protein accumulation upon senescence, an effect that was abrogated by EX-527. Consistently, SA induced an increase in the levels of the chaperone BiP, resulting in a downregulation of unfolded protein response (UPR) signaling and UPR-dependent autophagy, avoiding their abnormal hyperactivation during senescence. SA did not directly activate SIRT1 in vitro, suggesting that SIRT1 is a downstream effector of SA signaling specifically in the response to cellular senescence. Our study not only uncovers a shikimic acid/SIRT1 signaling pathway that prevents cellular senescence, but also reinforces the role of sirtuins as key regulators of cell proteostasis.

The effect of prolonged ultraviolet (UV) irradiation on the performance of superhydrophobized birch and acetylated birch wood was investigated. The surface modification of the wood was based on a newly developed method using silicone nanofilaments. The combination of surface modification and acetylation of wood showed good wetting resistance also after 600 h of UV exposure, with water contact angles greater than 140° and water uptake 30 times lower by weight than that of the non-surface-modified wood as determined by multicycle Wilhelmy plate measurements. Scanning electron microscopy images revealed that the silicone nanofilaments can still be observed on the wood samples after UV irradiation. The surface-modified wood samples exhibited significant color change after UV exposure. FTIR spectra showed that lignin was degraded on both the non-surface-modified wood surfaces and the wood surface-modified with the silicone nanofilaments.

DNA damage response (DDR) in eukaryotes is largely regulated by protein phosphorylation. In archaea, many proteins are phosphorylated, however, it is unclear how the cells respond to DNA damage through global protein phosphorylation. We previously found that Δrio1, a Rio1 kinase homolog deletion strain of Sulfolobus islandicus REY15A, was sensitive to UV irradiation. In this study, we showed that Δrio1 grew faster than the wild type. Quantitative phosphoproteomic analysis of the wild type and Δrio1, untreated and irradiated with UV irradiation, revealed 562 phosphorylated sites (with a Ser/Thr/Tyr ratio of 65.3%/23.8%/10.9%) of 333 proteins in total. The phosphorylation levels of 35 sites of 30 proteins changed with >1.3-fold in the wild type strain upon UV irradiation. Interestingly, more than half of the UV-induced changes in the wild type did not occur in the Δrio1 strain, which were mainly associated with proteins synthesis and turnover. In addition, a protein kinase and several transcriptional regulators were differentially phosphorylated after UV treatment, and some of the changes were dependent on Rio1. Finally, many proteins involved in various cellular metabolisms exhibited Riol-related and UV-independent phosphorylation changes. Our results suggest that Rio1 is involved in the regulation of protein recycling and signal transduction in response to UV irradiation, and plays regulatory roles in multiple cellular processes in S. islandicus.

Highlights • Hydroxychloroquine (HCQ) has the potential to be a persistent pollutant in water. • Electrochemical oxidation with BDD anode (EO) degraded HCQ in all tested conditions. • EO led to the release of Cl− ions and conversion of organic nitrogen to NO3 − and NH4 +. • EO combined with UV light or ultrasound enhanced degradation kinetics and efficiency. • Due to higher production of oxidants, EO combined with UV light used much less energy., In this work, the degradation of hydroxychloroquine (HCQ) drug in aqueous solution by electrochemical advanced oxidation processes including electrochemical oxidation (EO) using boron doped diamond (BDD) and its combination with UV irradiation (photo-assisted electrochemical oxidation, PEO) and sonication (sono-assisted electrochemical oxidation, SEO) was investigated. EO using BDD anode achieved the complete depletion of HCQ from aqueous solutions in regardless of HCQ concentration, current density, and initial pH value. The decay of HCQ was more rapid than total organic carbon (TOC) indicating that the degradation of HCQ by EO using BDD anode involves successive steps leading to the formation of organic intermediates that end to mineralize. Furthermore, the results demonstrated the release chloride (Cl−) ions at the first stages of HCQ degradation. In addition, the organic nitrogen was converted mainly into NO3− and NH4+ and small amounts of volatile nitrogen species (NH3 and NOx). Chromatography analysis confirmed the formation of 7-chloro-4-quinolinamine (CQLA), oxamic and oxalic acids as intermediates of HCQ degradation by EO using BDD anode. The combination of EO with UV irradiation or sonication enhances the kinetics and the efficacy of HCQ oxidation. PEO requires the lowest energy consumption (EC) of 63 kWh/m3 showing its cost-effectiveness. PEO has the potential to be an excellent alternative method for the treatment of wastewaters contaminated with HCQ drug and its derivatives.

This work focuses on the development of electro-absorption and photoelectro-absorption technologies to treat gases produced by a synthetic waste containing the highly volatile perchloroethylene (PCE). To do this, a packed absorption column coupled with a UV lamp and an undivided electrooxidation cell was used. Firstly, it was confirmed that the absorption in a packed column is a viable method to achieve retention of PCE into an absorbent-electrolyte liquid. It was observed that PCE does not only absorb but it was also transformed into phosgene and other by-products. Later, it was confirmed that the electro-absorption process influenced the PCE degradation, favoring the transformation of phosgene into final products. Opposite to what is expected, carbon dioxide is not the main product obtained, but carbon tetrachloride and trichloroacetic acid. Both species are also hazardous but their higher solubility in water opens possibilities for a successful and more environmental-friendly removal. The coupling with UV-irradiation has a negative impact on the degradation of phosgene. Finally, a reaction mechanism was proposed for the degradation of PCE based on the experimental observations. Results were not as expected during the planning of the experimental work but it is important to take in mind that PCE decomposition occurs in wet conditions, regardless of the applied technology, and this work is a first approach to try to solve the treatment problems associated to PCE gaseous waste flows in a realistic way.

Summary In response to transcription-blocking DNA damage, cells orchestrate a multi-pronged reaction, involving transcription-coupled DNA repair, degradation of RNA polymerase II (RNAPII), and genome-wide transcription shutdown. Here, we provide insight into how these responses are connected by the finding that ubiquitylation of RNAPII itself, at a single lysine (RPB1 K1268), is the focal point for DNA-damage-response coordination. K1268 ubiquitylation affects DNA repair and signals RNAPII degradation, essential for surviving genotoxic insult. RNAPII degradation results in a shutdown of transcriptional initiation, in the absence of which cells display dramatic transcriptome alterations. Additionally, regulation of RNAPII stability is central to transcription recovery—persistent RNAPII depletion underlies the failure of this process in Cockayne syndrome B cells. These data expose regulation of global RNAPII levels as integral to the cellular DNA-damage response and open the intriguing possibility that RNAPII pool size generally affects cell-specific transcription programs in genome instability disorders and even normal cells., Graphical Abstract, Highlights • Specific RPB1 K1268 ubiquitylation targets RNAPII for UV-induced proteolysis • RPB1 K1268 ubiquitylation is required for surviving DNA damage • Control of the RNAPII pool via degradation regulates the transcriptome after UV • Lack of transcription recovery in Cockayne syndrome is caused by unstable RNAPII, Control of the pool of available RNA polymerase II shapes how cells respond to UV stress and the efficacy of the resulting damage response.

International audience; Diverse DNA repair mechanisms are essential to all living organisms. Some of the most widespread repair systems allow recovery of genome integrity in the face of UV radiation. Here, we show that the hyperthermophilic archaeon Thermococcus nautili possesses a remarkable ability to recovery from extreme chromosomal damage. Immediately following UV irradiation, chromosomal DNA of T. nautili is fragmented beyond recognition. However, the extensive UV-induced double-stranded breaks (DSB) are repaired over the course of several hours, allowing restoration of growth. DSBs also disrupted plasmid DNA in this species. Similar to the chromosome, plasmid integrity was restored during an outgrowth period. Intriguingly, the topology of recovered pTN1 plasmids differed from control strain by being more positively supercoiled. As reverse gyrase (RG) is the only enzyme capable of inducing positive supercoiling, our results suggest the activation of RG activity by UV-induced stress. We suggest simple UV stress could be used to study archaeal DNA repair and responses to DSB.

TiO2-graphite composites (TiO2-G) were prepared using different contents of powder graphite (G) and the obtained samples were characterized by different chemical-physical techniques. XRD and Raman results confirmed the presence of titania in anatase phase and, moreover, Raman spectra evidenced the presence of a band due to the graphite nanoparticles in the composite with an intensity that increased with the increasing of G content. From the UV–vis diffuse reflectance spectra it was evident a background absorption in the visible light region for TiO2-G composites whereas the band-gap energy value was similar to pure TiO2 and did not change with the increase of G content. Pure TiO2 and TiO2-G photocatalysts were used in the photocatalytic treatment of a solution containing paracetamol under UV light irradiation and the results are shown in terms of paracetamol degradation and total organic carbon (TOC) removal, evidencing an enhancement of photocatalytic performances due to the presence of G in the composites if compared with pure TiO2. The optimal G loading in TiO2-G composites was equal to 0.026 wt%, allowing to obtain the almost complete paracetamol degradation after 120 min of UV irradiation and a TOC removal of about 88% after 180 min of irradiation time.

Investigations of the influence of chemical and physical factors on the conformational and functional properties of enzymes make a significant contribution to the study of the mechanism of action of industrially important proteins. The aim of the work was to evaluate the effect of chemical reagents and UV irradiation on the catalytic properties of Penicillium canescens α-galactosidase. Enzyme activity was assessed with p-nitrophenyl-α-D-galactopyranoside. Studies of the functionally active glycosidase groups were carried out on the basis of inhibitory and kinetic analysis using Dixon and Luinuiver-Burke methods with help of specific chemical reagents. A significant decrease in the activity of α-galactosidase in the presence of carbodiimi­des, diethylpyrocarbonate, the reagents on sulfhydryl groups was shown. A UV-induced decrease in enzyme activi­ty in the dose range of 900-7200 J/m2 was noted. Based on the data obtained, the imidazole group of histidine, carboxyl groups of C-terminal amino acids and the SH-groups of cysteine are assumed to play an important role in the manifestation of the activity of P. canescens α-galactosidase.

Phenol is considered as one of the major environmental concerns due to its characteristics including chronic toxicity, biological stability, and increasing the toxicological intermediates after biological degradation. Therefore, the aim of this study was to evaluate the photo-degradation of phenol using the titanium dioxide (TiO2) photo-catalyst on ordered mesoporous carbon (CMK-3) support under UV irradiation. In this study, the effects of some parameters including pH value (4, 5, 6, 7, 8, 9, 10), TiO2/CMK-3 concentration (0.05, 0.1, 0.15, 0.3, 0.5 g/L), irradiation time (30, 60, 90, 120, 150 min), and phenol concentration (50, 100, 150 and 200 mg/L) were assessed. The properties of the CMK-3 and TiO2/CMK-3 were compared using the transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and N2 adsorption-desorption isotherm. The results revealed that the process studied was remarkably affected by the parameters, and the optimum values of the parameters were as follows: pH=6, TiO2/CMK-3 concentration =0.15 g/L, phenol concentration = 100 mg/L, and irradiation time=150 min. The phenol degradation efficiency and total organic carbon (TOC) removal efficiency for phenol were 96% and 74%, respectively. Moreover, the stability greater than 7 times for the studied photo-catalyst was indicative of its high potential to be used in photo-degradation processes for the elimination of pollutants.

This paper reports the effects of pre-oxidation processes including ozone and ultraviolet (UV) irradiation prior to chloramination on microbiologically assisted monochloramine decay. Water samples with varying water qualities were pre-oxidated by ozone and UV irradiation, followed by determination of chemical and microbiological monochloramine decay (F m ). Both ozone and UV could effectively improve the reduction of microbial-like compounds responsible for monochloramine decay in treated water samples. Reductions in F m values were observed for ozone contact times (Ct) greater than 5 mg min/L and UV doses greater than 30 mJ/cm 2 . However, UV was less effective than ozone in reducing F m values in raw water samples. Complete removal of the microbiological component of the decay for raw water samples was not found either with ozone (even with Ct of 50 mg min/L) or UV (even with UV dose of 120 mJ/cm 2 ). The effects of pre-oxidation processes on chemical (k c ) and microbial (k m ) decay coefficients were assessed. Increasing both ozone Ct and UV dose ahead of chloramine did not affect the chemical decay component, but they changed the microbiological component of decay. Changes in organic matter after ozonation were also characterized using three-dimensional fluorescence excitation–emission matrix (3D-FEEM) spectroscopy, and correlations between 3D-FEEM spectroscopy results and F m values were found. Intensities of humic-like, fulvic-like, microbial protein-like and aromatic protein-like substances were reduced by pre-ozonation. Based on the 3D-FEEM results, we can confirm that the slowdown of monochloramine decay rate is due to the reduction of marine humic-like substances and soluble microbial protein-like compounds by pre-ozonation. Refereed/Peer-reviewed