Action Of UV Research Articles

Influence of production method on the structure and photocatalytic activity of CeO<sub>2</sub>/Au nanocomposite

Two methods for preparing mesoporous CeO2/Au nanocomposites were compared: template synthesis and photochemical modification of fibrous cerium(IV) oxide with gold nanoparticles. The composition, structure, morphology of the obtained nanocomposites, as well as the specific surface area and pore size distribution were studied by a complex of physicochemical methods: X-ray phase analysis, X-ray spectral microanalysis, scanning electron microscopy, low-temperature nitrogen adsorption, and electron spectroscopy. The catalytic properties of the obtained nanocomposites were studied in methyl orange photodegradation reactions. It is shown that the CeO2/Au catalyst obtained by the photochemical modification method has the highest photocatalytic activity both under the action of UV and visible light.

Oxidative stress and protection against it in bacteria

Microorganisms are exposed to reactive oxygen species (ROS) that are formed in various ways, in particular, as a result of respiration or other intracellular processes, during metal-catalyzed Fenton reactions, as a result of the action of UV- and X-radiation, under the influence of some antimicrobial drugs, or during the host immune oxidative-burst response against infection agents. In this review, we take a look at the mechanisms of microbial cell damage, including damage of lipids and proteins. Lipid peroxidation (LPO) is one of the main molecular mechanisms involved in oxidative damage to cellular structures. A variety of products are formed during LPO reactions: alkoxyl radicals, peroxyl radicals, hydroperoxides, diene conjugates, carbonyl compounds, aldehyde adducts with biopolymers, alcohols, esters, etc. These products include cytotoxic and highly reactive compounds. Free radical reactions of protein damage occur via hydrogen atom abstraction from α-carbon or SH-, NH2-groups of aminoacids and electron abstraction from nucleophile centers of proteins resulting in the fragmentation of proteins, their denaturation and the formation of amino acid radicals. Bacteria show a significant adaptive potential to the influence of stress agents, including ROS. We summarized the data on bacterial antioxidant protection, ROS redox sensors, and regulators of bacterial cell response to ROS exposure, focusing on the features of anaerobic microorganisms, as their responses to the oxidative damage are the least studied, and many problems remain unsolved. This review contains information about changes in fatty acid composition of lipids of the plasma membrane to maintain the necessary fluidity, and, thus, counteract the effects of various stressing agents, including ROS. The main modifications of the fatty acid composition of lipids important for the regulation of membrane fluidity are described, in particular, via changes in the degree of lipid saturation, cis/trans isomerization, and synthesis of cyclopropane fatty acids.

Combined action of cerianite, uv and direct sunlight irradiation for the removal of violet crystal and methylene blue from aqueous solution

Combined action of cerianite, uv and direct sunlight irradiation for the removal of violet crystal and methylene blue from aqueous solution

Совместное воздействие УФ излучения и ультразвуковой кавитации на сапрофитную и условно-патогенную микрофлору холодноводных УЗВ

The paper considers the combined effect of ultraviolet radiation (UV) and ultrasonic cavitation (ultrasonic) as part of ultrasonic filtration systems on representatives of saprophytic and conditionally pathogenic microflora of water. Ultrasound examination (25 kHz) is a promising method of purification in aquaculture due to the possibility of inactivation of microorganisms in agglomerates that are not exposed to UV. As a result of the study of the cultivated microflora, it was found that ultraviolet radiation and the combined effect of UV and ULTRASOUND have a significant effect on the quantity and quality of saprophytic microflora of water. It is shown that the studied modes of operation led to a significant decrease (at p <0.05) in the occurrence of the genus Escherchia relative to the control (without exposure to ultrasound and UV). The total contamination of UV water decreased to 1.2×102 CFU/ml with UV operation and to 1.1×102 CFU/ml with the combined action of UV and ultrasound. The UV sterilizer showed low efficiency in relation to Enterobacter cloacae, while the combined effect of UV and ultrasound led to a significant decrease in CFU to 0.94 ± 0.05 Log10.

Photocatalytic Decomposition of Azo Dyes and Phenols Using Polymer Composites Containing Nanostructured Poly(Titanium Oxide) Doped with Gold or Silver Nanoparticles under Light Irradiation in a Wide Wavelength Range

The photocatalytic properties of poly(titanium oxide) (PTO) dispersed in optically transparent polymeric matrices of different natures under the action of both UV and visible light on aqueous solutions of azo dyes and phenols were investigated. PTO in materials forms clusters of mixed polymorphic modification—anatase and rutile—with an average size ~12 nm. With a one-electron transition Ti4+ + e− → Ti3+ accompanied by a reversible break of the Ti-O bond, the formation of electron-hole pairs and, consequently, active oxygen species occurs in PTO under UV irradiation. The PTO band gap in nanocomposites is 3.11–3.35 eV. Its doping with gold and silver nanoparticles with sizes from ~10 to ~30 nm reduces the PTO band gap by up to 2.11 eV, which leads to the operating wavelength range extension of the materials. It provides the enhancement of nanocomposites’ photocatalytic properties under UV irradiation and is the reason for their high activity under visible light action. It was found that azo dyes decompose by ~90% in this case. A phenol and para-nitrophenol conversion of 80–90% was proven at ~60 min upon their aqueous solutions’ visible-light irradiation at the nanocomposite concentration in a solution of 0.5 g/L.

Фотокаталитическое разложение растворов метилового оранжевого на поверхности нанопористых слоев меди, серебра и их йодидов

The efficiency of photocatalytic decomposition of methyl orange solutions on the surface of nanoporous layers of copper, silver and their iodides has been studied. It is shows that nanoporous layers on metal substrates have two absorption bands: they absorb radiation in the UV and Vis spectral range. The process of decomposition of methyl orange molecules on the surface of metal-semiconductor nanostructures Cu-CuI and Ag-AgI occurs under the action of UV and Vis irradiation. While transparency of the methyl orange solution increases.

Reactions of oxygen atoms with fluoroform and its radiolysis products: matrix isolation and ab initio study.

The investigation of the reactions of oxygen atoms with fluoroform (CHF3) molecules and products of their degradation present significant interest for better understanding of the impact of chemically inert fluorinated compounds on atmospheric chemistry and may provide a deeper insight into mechanisms of chemical processes occurring under the action of hard UV and ionizing radiation. In the present study we applied a matrix isolation technique with FTIR spectroscopic detection combined with ab initio calculations to address this issue. It was found that the reactions of "hot" (translationally excited) O(1D) atoms produced by X-ray or UV radiation from appropriate precursors (N2O or H2O) resulted in the formation of carbonyl fluoride (COF2) and its complex with HF. The complex was detected and characterized for the first time. Singlet oxygen atoms also probably react with the products of radiation-induced degradation of fluoroform (CF3 and CF2). Additionally, the reaction of "hot" O(3P) atoms with fluoroform may occur to a certain extent yielding the CF3 radical. No evidence for the reactions of thermal O(3P) atoms with CHF3 or products of its degradation was found under the experimental conditions used. The implications of the results of this model study for understanding the evolution of fluoroform in the upper layers of the stratosphere and ionosphere are discussed.

Photoactive Cu-Containing ZnO-ZnAl-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=- nanocomposites

Photoactive Cu-containing ZnO-ZnAl2O3 nanocomposites were synthesized by the polymer-salt method. To study the structure and properties of materials, the methods of luminescent spectroscopy and X-ray phase analysis were used. It has been shown that the resulting nanocomposites are capable of photogeneration of singlet oxygen under the action of UV and blue light. The synthesized materials consist of nanosized hexagonal ZnO crystals and cubic ZnAl2O4 crystals doped with Cu. The study of luminescent properties showed that nanocomposites can be used as down-converters of light that convert radiation from the UV-C range to UV-A and the visible spectral range. Keywords: singlet oxygen, nanoparticle, luminescence, ZnO, ZnAl2O4.

Фотоактивные Cu-содержащие нанокомпозиты ZnO-ZnAl-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=-

Photoactive Cu-containing ZnO-ZnAl2O3 nanocomposites were synthesized by the polymer-salt method. To study the structure and properties of materials, the methods of luminescent spectroscopy and X-ray phase analysis were used. It has been shown that the resulting nanocomposites are capable of photogeneration of singlet oxygen under the action of UV and blue light. The synthesized materials consist of nanosized hexagonal ZnO crystals and cubic ZnAl2O4 crystals doped with Cu. The study of luminescent properties showed that nanocomposites can be used as down-converters of light that convert radiation from the UV-C range to UV-A and the visible spectral range.

Degradation Effect of UV Synergistic Biomass Activated Carbon Materials on Phenol Pollutants in Water

The purpose of the study is to purify the water containing phenol pollutants. The degradation effect of phenol pollutants in water is studied through the combined action of UV and biomass-activated carbon. First, the phenol solution is prepared in the laboratory to simulate the polluted water. Second, the phenol adsorption effects of UV synergistic biomass activated carbon, biomass activated carbon and ordinary industrial activated carbon under different influencing factors are compared by experiments. Finally, the results are analyzed and the conclusions are drawn. The results show that the UV synergistic biomass activated carbon has the strongest degradation ability for phenol, and the highest removal rate is 66.5% when the shaking time is 65 minutes. The adsorption ability of the industrial activated carbon for phenol is the worst. When the initial concentration of phenol is 25mg/L, the maximum phenol removal rate is 96.8%. The maximum phenol removal rate of biomass activa ted carbon appears in the initial concentration of phenol and the phenol removal rate is 60 mg/L. The reaction temperature has little effect on the phenol removal rate of UV synergistic biomass activated carbon and biomass activated carbon. The phenol removal ability of UV synergistic biomass activated carbon and biomass activated carbon reaches the highest when the dosage of activated carbon is 2.0 g, and the rates are 96.4% and 91.1%, respectively. When the pH of the solution is 7, the removal rate of UV synergistic biomass activated carbon reaches a maximum of 97%. When the pH of the solution is 6, the removal rate of biomass-activated carbon reaches the maximum. When the pH of the ordinary industrial activated carbon is 7, the removal rate is the maximum. Due to different influencing factors, UV synergistic biomass activated carbon has the strongest phenol degradation ability. This study provides a reference for the purification of polluted water.

Radiation-induced transformations of difluoromethane in noble gas matrices

Difluoromethane (CH2F2) is considered as an ecologically friendly alternative to conventionally used chlorofluorocarbons for various applications. Being photochemically inert in the broad UV range, this molecule can be decomposed only through the action of hard vacuum UV or ionizing radiation, while the corresponding mechanisms are poorly studied. In this work we report the results of model investigations of the X-ray induced decomposition of isolated CH2F2 in solid noble gas matrices at 6 K. The radiation-chemical yields of difluoromethane were found to decrease from 1.3 to 0.1 molecule/100 eV with decreasing the ionization energy of matrix (from Ne to Xe), which indicates significance of the “hot” ionic channels. Difluorocarbene (CF2) was detected as one of the principal radiolysis products in all the matrices, whereas the CHF⋯HF complex was detected in Ne, Ar, and Kr. Annealing of the irradiated samples results in thermally induced reactions of trapped H and F atoms yielding a number of various species, including the noble gas compounds. The radiolysis mechanism, nature of matrix effects and possible implications for atmospheric chemistry are discussed.

Spectrophotometry and spectrofluorimetry to analyze the destruction of pharmaceuticals during wastewater treatment by enhanced oxidation

The work is devoted to the treatment of wastewater from pharmaceuticals by enhanced oxidation. Some studies have shown the high degree and speed of pharmaceutical degradation under the action of a hydroxyl radical formed by the combined action of UV and H2O2 (enhanced oxidation, which was fully confirmed by a decrease in absorption in the UV spectrum. This paper shows that, unlike spectrophotometry, the spectrofluorimetry method can be used in the analyzing the process of destruction of hard-to-degrade pharmaceuticals. The object of the study was synthetic alkaloid vinpocetine, which has an indole core. Vinpocetine solutions were irradiated in a laboratory setup which included a TUV 30w / GTV low-pressure argon-mercury lamp (Philips) for 5–15 min, and also irradiated for 1-10 minutes after adding hydrogen peroxide at a concentration of 100 mg / L). The spectrophotometry method showed an increase (instead of a decrease) in the absorption spectra with an increase in the duration of UV irradiation. Under the same conditions, the spectrofluorimetry method recorded a decrease in the signal intensity in the registration and excitation spectra, and under enhanced oxidation, the appearance of new bands characteristic of the phenolic group.

COMBINED PHOTOINDUCED PATHOLOGY OF THE SKIN AND EYES IN PATIENTS WITH DERMATOHELIOSIS

Modern information on the mechanisms of the damaging effect of UV radiation on the skin and the eye is presented, constitutional phototype skin (according to the Fitzpatrick scale) and clinical stages of skin photoaging are described (according to R. Glogau). The range of clinical changes arising on the background of solar elastosis can vary depending on the anatomical site of the lesion and include a number of dermatoses included in the concept of solar elastosis syndromes, resulting in the development of malignant dermatoses. Depending on the type of UV exposure - sporadic short-term or systematic long-term, acute and chronic pathological processes caused by the action of UV may develop. The development of eyelid neoplasms (basal cell, metatypical, squamous cell carcinoma, melanoma), solar keratosis of the conjunctiva, pterygium, cataract, and macular retinal degeneration may result from the systematic UV irradiation of the organs of vision.

Effect of the Composition of Mesoporous Titania–Silica Oxide Photocatalysts on Their Activity During the Destruction of Methylene Blue in Aqueous Solutions

Mesoporous titania–silica oxide materials of various compositions with high crystallinity and predominantly in the anatase modification were produced by hydrolysis and subsequent heat treatment of a mixture of titanium tetrachloride and oligodimethylsiloxane (ODMS) containing terminal Si–Cl groups. The synthesized samples were tested as photocatalysts in the destruction of methylene blue dye in aqueous solutions. The highest activity, significantly exceeding the activity of commercial TiO2, the highest specific surface area, and porosity was exhibited by the photocatalyst prepared from 33 wt.% ODMS. The photocatalysts are active not only under the action of UV but also of visible light. This may be due to the effect of carbon doping of TiO2 during ODMS decomposition, which increases the light absorption and improves the separation of the photogenerated charges.

A rare cause of squamous cell carcinoma which develops at an early age: Epidermodysplasia verruciformis

Epidermodysplasia verruciformis ( Lewandowsky- Lutz Syndrome), is characterized with premalignant lesions which commonly infected by Human papillomavirus (HPV) and immune deficiency due to Human papillomavirus or other causes. When mutation-inducing action of UV added on lesions that infected HPV, they usually transform actinic keratosis, Bowen's disease, and invasive squamous cell carcinoma, rarely basal cell carcinoma (BCC) on, especially in areas exposed to the sun in particular the forehead. Here, we present a case of an adult patient with epidermodysplasia verruciformis with squamous cell carcinoma who has consanguineous parents and a sibling with whom she had same skin lesions. In the light of this case, treatment of squamous cell carcinoma based on epidermodysplasia verruciformis is presented. Keywords: Hepatitis B, HIV, Skin Neoplasms, Squamous cell carcinoma

New opportunities to valorize biomass wastes into green materials. II. Behaviour to accelerated weathering

The use of agricultural wastes as component of biodegradable materials represents a benefit for the environment, as well as for local economy. Our investigation has focused on the possibility to expand the use of some agriculture by-products by turning them into new biodegradable composites and to investigate their behaviour to accelerated weathering. We found that polylactic acid was more affected by the combined action of temperature, humidity and UV radiation as compared to composite materials. The tensile strength decreased by 73.66% for polylactic acid as matrix, 26% for the composite comprising celery root fibres, 3% for the composite comprising Asclepias syriaca fibres and 1% for the composite with poplar seed hair fibres. An increase of 31% was registered for the material comprising pomace, which can be explained by biomass composition, where lignin is the major component. The increase of storage modulus with ageing could be related with the increase of rigidity and chain packing, which can be connected to an enhanced density induced by ageing. All composites showed increased water sorption capacity values, while Atomic Force Microscopy images revealed the deterioration of the surface of the materials exposed to the combined action of UV, temperature and humidity. Scanning Electron Microscopy images of weathered materials evidenced some voids between the filler particles and the polylactic acid matrix, but most of the filler particles were still kept intact within the matrix. The economic study evidenced a great potential for achieving green materials at reasonable costs. The obtained results indicate that different biomass wastes can be used as filler for a polylactic acid matrix. In the pursuit of sustainable waste management, our findings can play a significant role in elaborating a business model.

Gas-filled radioluminescent light sources and prospects for their further development

Luminescence of various inorganic compounds of rare earth elements as radioluminophores was studied with the aim of fabricating weak permanent light sources. Under the action of UV and tritium radiation, all the luminophores tested emit light of different colors. In the tritium gas medium, six luminophores showed emission, and for three of them (Y2O3:Eu, Y2O3:Eu, Bi, Gd2O3:Eu) the emission brightness was acceptable for practical use. Attempt to prepare permanent light sources with new types of luminophores using a phosphoric acid solution as a binder demonstrated the need for searching for a new binder firmly fixing the luminophore on the glass surface.

Green synthesis of SnO2 nanoparticles and its photocatalytic activity of phenolsulfonphthalein dye

Tin oxide (SnO2) nanoparticles were prepared using Persia Americana seed methanolic extract by calcining stannous chloride precursors at 300–500°C by green synthesis method. Synthesized SnO2 NPs were confirmed via characterization techniques such as UV–visible spectroscopy (UV), X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray analysis (EDAX). The results of characterization technique states that the synthesized nanoparticles were in the size of 4nm and further we have undergone catalytic degradation of organic dye named phenolsulfonphthalein (phenol red). The result showed that SnO2 NPs shows much degradation activity by the catalytic action of long UV exactly at 365nm.

Advanced oxidation (H2O2 and/or UV) of functionalized carbon nanotubes (CNT-OH and CNT-COOH) and its influence on the stabilization of CNTs in water and tannic acid solution

The properties of carbon nanotubes (CNTs) functionalized with –OH and –COOH groups during simulated water treatment with H2O2 and/or UV were tested. There following properties of CNTs were investigated: specific surface area, elemental composition (CHN), dynamic light scattering, Raman spectroscopy, X-ray photoelectron spectroscopy and changes in the CNTs structure were observed using transmission electron microscopy. Treatment of CNTs with H2O2 and/or UV affected their properties. This effect, however, was different depending on the functionalization of CNTs and also on the factor used (UV and/or H2O2). H2O2 plays a key role as a factor modifying the surface of CNT-OHs, whereas the properties of CNT-COOHs were most affected by UV rays. A shortening of the nanotubes, exfoliation, the opening of their ends, and changes in the surface charge were observed as a result of the action of UV and/or H2O2. The changes in observed parameters may influence the stability of the aqueous suspensions of CNTs.

Promising equipment for greenhouse wastewater treatment

The article presents the experimental results of greenhouse wastewater treatment by means of cavitation. It is noted that the use of ultrasonic cleaning has drawbacks. It is found that the use of hydrodynamic cavitation for wastewater treatment is a promising direction. It is noted that in effluents with residues of phenolic compounds, treatment is improved when using oxidizing agents such as hydrogen peroxide. A design of cavitation reactor for wastewater treatment using an ultrasonic radiation was proposed. The reactor was tested in an industrial environment and showed good treatment results. It was found that at simultaneous action of hydrodynamic cavitation and UV, the germicidal effect occurs. Due to this, pathogenic organisms are destructed. The article illustrates the experimental setup and cavitation reactor.