Influence Of Ultraviolet Irradiation Research Articles

Issues of using modern organic reagents in the practice of drinking water supply (literature review)

The article contains a literature review devoted to the safe use of modern organic reagents in drinking water supply practice. When conducting a literature search, the following databases were used as follows: Pubmed, Scopus, Web of Science, MedLine, Global Health, RSCI, as well as a search method based on keywords and citations. The purpose of the review is that despite the large number of developed technologies and various reagents, the problem of removing anthropogenic and anthropogenic pollutants from natural water purification cannot be considered to be solved. Water purification technologies are being improved; their effectiveness largely depends on the intensification of reagent treatment.
 In addition to generally accepted laboratory studies of the reagents used in water treatment, it is necessary to conduct production tests to clarify the parameters of the health risk and toxicity of the transformation products formed during the water treatment process, as well as to study the effectiveness and safety of a set of reagents that together enter the water treatment process. The hygienic assessment of reagents should take into account the actual conditions of their use in drinking water supply practice, including further stages of water treatment. This concerns the assessment of the possible destruction of polymers during the production of composite reagents, the assessment of modifying additives included in their composition, the transformation of polymers in water during chlorination, chloramination, ozonation, under the influence of ultraviolet irradiation, and adjustment of a set of mandatory controlled indicators. To conduct these studies, laboratories must have publicly available analytical methods that allow accurately determining the presence of monomers, polymers, as well as various additives and transformation products in concentrations actually present in drinking water.

Influence of ultraviolet irradiation on the optical properties and biological activity of copper nanoparticles prepared by pulsed laser ablation

In this study, we synthesized colloidal copper nanoparticles (CuNPs) utilizing Q-switched Nd:YAG laser ablation on a copper plate immersed in double-distilled water at energies of 200 and 400 mJ, respectively, with 100, 200, 300, 400, and 500 pulses. The size and optical properties of nanoparticles were determined using a UV–Vis spectrophotometer, a transmission electron microscope (TEM), and a field emission scanning electron microscope (FE-SEM). The absorption spectra exhibited two surface plasmon resonance peaks (λSPR), one at 217 nm for copper oxide nanoparticles (CuONPs) and the other at 636 nm for CuNPs, with the increase in laser pulses. Consequently, the optical bandgap increased by roughly 3 eV. The TEM and FE-SEM analyses showed nearly spherical Cu nanoparticles with average diameters of 33 and 38 nm for laser energies of 200 and 400 mJ, respectively. An analysis of x-ray diffraction patterns revealed that CuONPs contained the crystallographic planes of a monoclinic and an orthorhombic crystal system. Additionally, the mean crystallite size of laser-ablated nanoparticles increased with increasing pulse energy. Furthermore, the absorption and optical bandgap of CuNPs increased slightly with an increase in ultraviolet irradiation exposure. The results of our study showed an increased inhibitory effect against both Staphylococcus aureus bacteria and Escherichia coli bacteria when CuNPs were irradiated by ultraviolet type C.

Influence of soft x-ray and ultraviolet irradiations on sensitivity of sensors made with piezoelectret films

Abstract Piezo/ferroelectrets are a kind of cellular electret materials exhibiting piezoelectric effect. Owing to their large piezoelectric activity, flexibility, lightweight, low cost and large area, a list of promising applications have been suggested, including wearable sensors, actuators, micro energy harvesters, and etc. In terms of actual application, one of the most important performance indexes is the stability of piezoelectric response in complex application environments. This article mainly focuses on the influence of soft x-ray and ultraviolet irradiations on piezoelectric sensitivity of two kinds of sensors, made with irradiation cross-linked polypropylene (IXPP) and air-filled parallel-tunnel fluorinated ethylene propylene (FEP) piezoelectret films. A versatile encapsulation process with silica gel for sensor fabrication was introduced to improve the stability against radiations. The results show that soft x-ray irradiation can accelerate the depolarization of the piezoelectrets, while the influence of ultraviolet irradiation on piezoelectrets is not prominent. Encapsulation of the sensors with silica gel may significantly improve their stability under the radiation of soft x-ray. As indicated, the piezoelectric sensitivities of the encapsulated samples, made with IXPP and parallel-tunnel FEP piezoelectret films, are 50.2% and 6.9% of the initial values after 150 min irradiation of the soft x-ray with an energy of 9.5 keV, respectively.

Issues of diagnostics and treatment of vitamin D deficiency in older patients

Vitamin D is a fat-soluble compound that a person obtains from food or synthesizes independently when the skin is exposed to sunlight.
 Vitamin D metabolism is modulated by various intrinsic and extrinsic factors, including genetic polymorphism, skin type (pigmentation), age, health, season, latitude, clothing, and diet. Some of them are modifiable, i.e., they can be controlled by humans.
 To assess the vitamin D level in the body, the recommendation was to determine the concentration of total 25(OH)D in the blood serum, the main circulating form, which reflects both the intake of vitamin D from food and native preparations and the synthesized vitamin D in the skin under the influence of ultraviolet irradiation. This study focused on the diagnosis and treatment of vitamin D deficiency in older patients.
 The age-related problem is associated with a more frequent history of surgery and chronic diseases requiring drug therapy, which in turn can affect the metabolism of this vitamin. Vitamin D deficiency in older people requires constant and long-term use of cholecalciferol; however, the risks of drug interactions and polypharmacy should not be overlooked.
 The diagnosis and treatment of vitamin D deficiency in older people should consider all the characteristics of this group. Moreover, this study presents the features of vitamin D metabolism in older people, nosologies predisposing to the development of vitamin D deficiency, methods for diagnosing and correcting vitamin D deficiency, and relationship between severe COVID-19 and vitamin D levels.
 Further study of possible drug interactions, additional effects of vitamin D, and its contribution to comorbidities is warranted.

The influence of UV irradiation on fish skin collagen films in the presence of xanthohumol and propanediol

Fish skin collagen films are widely used as adhesives in medicine and cosmetology. Ultraviolet (UV) irradiation can be considered as an effective sterilization method for biomaterials, however, it may also lead to material photodegradation. In this work, the influence of xanthohumol and propanediol on the physico-chemical properties of collagen films before and after UV irradiation was studied.Collagen for this research was extracted from silver carp skin and thin films were fabricated by the solution casting methods.The structure of films was researched using infrared spectroscopy. The surface properties of films were investigated using Atomic Force Microscopy (AFM) and contact angle measurements. Mechanical properties were measured as well. It was found that the addition of xanthohumol and propanediol modified the roughness of collagen films and their mechanical properties. UV irradiation led to the water loss from the film and modification of the collagen structure.In the presence of propanediol and xanthohumol the water loss after UV irradiation was smaller than in UV-irradiated collagen films without these additives.

Influence of UV irradiation on mechanical properties and drop-weight impact performance of polypropylene biocomposites reinforced with short flax and pine fibers

The design of biocomposite structures for outdoor applications should consider the influence of ultraviolet (UV) irradiation on the mechanical performances to more accurately determine their durability characteristics and prevent significant damage. Ultraviolet radiation causes the discoloration, surface roughness, mass loss, and degradation of the mechanical properties of biocomposites. In this study, the flexural strength and low-velocity impact response of polypropylene reinforced with short flax or pine fibers, which differed with respect to their physical and chemical properties, were investigated. Flax fibers are twice the length of pine fibers, and exhibit higher cellulose contents. Moreover, flax fibers have been demonstrated to increase the flexural strength and impact resistance of biocomposites. However, under UV irradiation, pine fibers containing more lignin dampened the degradation. Under photo-oxidative conditions, lignin is degraded to protect crystalline cellulose by acting as a light-absorbing compound. Non-destructive techniques such as Fourier transform infrared spectroscopy (FTIR), colorimetry, confocal imaging, acoustic emission, and CT scanning were therefore used to evaluate the effect of UV radiation on the chemical properties, color change, surface roughness, bending behavior, and drop-impact damage.

Влияние антиокислителей на стабильность бета-каротина в мультикомплексных системах

To prevent further degradation of partially oxidized beta-carotene, inclusion complexes based on beta-cyclodextrin and antioxidants (alpha-tocopherol (vitamin E), ascorbic acid, and vanillin) have been developed. The complexes were obtained by the solid-phase method with intensive stirring for four hours with periodic moistening to the state of a paste, then dried in a desiccator at a temperature of 2…5С, and ground to a powder. The content of beta-carotene in the complexes was determined on a Varian-LC 920 high-performance liquid chromatograph with a Hypersil 5 AA-ODS 200 x 2.1 mm column using a diode array detector with automatic control and data processing based on Galaxie software. The influence of antioxidants and beta-cyclodextrin on the stability of beta-carotene in conditions of ultraviolet irradiation and storage at a temperature of 2…5С is considered. It is noted that the best results are observed in complexes with the inclusion of alpha-tocopherol (mass ratio of beta-cyclodextrin: beta-carotene: alpha-tocopherol – 2:1:1) and vanillin (mass ratio of beta-cyclodextrin: beta-carotene: vanillin – 6:3:1). Under the influence of ultraviolet irradiation, the degradation of beta-carotene in the composition of the complex slows down by 4 (alpha-tocopherol) and 3 (vanillin) times. During long-term storage, the oxidation of beta-carotene in complexes with the addition of alpha-tocopherol and vanillin slows down by 60%. The stabilizing effect of ascorbic acid almost has no effect on the stability of beta-carotene in the composition of the complex. At the same time, the processes of complexation between beta-cyclodextrin and antioxidants, as well as other factors, can have a significant effect on the stability of beta-carotene in multicomplex systems.

Influence of ultraviolet irradiation of perennial grasses seeds on their sowing quality

A new direction in pre-sowing seed preparation is environmentally friendly and energyefficient ultraviolet irradiation, which increases germination, reduces seed infection, and improves growth force. In this regard, the experiment of studying the effect of UV irradiation on the sowing qualities and morphophysiological parameters of the seeds of the birds-foot trefoil and awnless brome was laid at the UdmFRC UB RAS in 2019. Use of UV rays of range A with a wavelength of 315–400 nm for 5 min reduced the infection of the birds-foot trefoil seeds by 3.2%, increased the length of the sprout by 0.81 cm and the strength of growth — by 5.4% in comparison with untreated seeds. There was also a tendency for a decrease in seed hardness by 2.5%, an increase in root length by 0.41 cm, and the degree of seedling development by 0.12 points. The most effective for awnless brome seeds was UV treatment for 35 minutes, which led to an increase in germination by 14.5%, a decrease in seed infection by 5.8%. There was also a tendency to improve the morphological parameters of seedlings: the length of the sprout increased by 0.9 cm, the length of the root — by 0.88 cm, the length of the coleoptile — by 0.30 cm. The strength of growth in this variant was 9.3% higher than in the control without treatment. In general, the treatment of perennial grasses seeds with ultraviolet light reduced infection, increased laboratory germination and strength of growth, and reduced seed hardness.

Development of a spatially structured polymeric matrix under UV irradiation of polylactide-based composites filled with aluminosilicate microspheres

The relevance of the study is conditioned by the fact that increased consumption of synthetic polymers leads to an increase in environmental pollution due to the long decomposition time of plastic waste. As a result, it is necessary to develop polymer composites based on a biodegradable polymer matrix, and to improve the performance properties of finished plastic products, it is necessary to purposefully select cheap and affordable inorganic fillers. Thus, the purpose of this study is to investigate the regularities in the generation of a spatially structured polymer matrix under UV irradiation of polylactide-based composites filled with aluminosilicate microspheres (ASM). The leading approach to the given problem is to melt polymer composites of various compositions and to determine the physical, mechanical, and thermophysical characteristics of the prototypes, including the supermolecular structure of the polymer matrix under the influence of ultraviolet irradiation. The study suggests that the filling of polylactide with ASM particles leads to an increase in the elastic modulus, a decrease in the strength at static rupture and resistance to dynamic destructive effects, as well as heat resistance. Small aluminosilicate microspheres, when added to polylactide, perform the function of nucleation and, even with a small content, increase the crystallinity degree by 3.7 percentage points. In the range of ASM content from 1 pph to 10 pph, the absolute value of the crystallinity degree practically does not depend on the filler concentration in the polymer composite. UV (ultraviolet) irradiation in the presence of air oxygen initiates the thermooxidative destruction of polylactide and leads to the establishment of a spatially structured polymer phase using the electrostatic intermolecular interaction of additionally formed oxygen-containing functional groups in macrochains, as well as partial intermolecular crosslinking during recombination of macroradicals. The establishment of spatial structures in the polymer matrix under UV irradiation determines an increase in the resistance of experimental samples to thermal effects. It is manifested in an increase in the bending temperature under load by 7-10 percentage points, a decrease in the crystallinity degree by 1.2-2.6 percentage points, a decrease in the fluidity of the meltage and also an increase in the glass transition and melting temperature. The materials of the study are of practical value for the development of biodegradable composites based on polylactide filled with inorganic components.

Influence of UV irradiation on the diameters and depths of alpha-particle tracks in CR-39 detectors

In this paper, we investigate the impact of ultraviolet (UV) exposure on the bulk etch rate (Vb), track etch rate (Vt), and detector sensitivity of a CR-39 nuclear track detector. The study involves measuring the depths and diameters of alpha particle tracks in the CR-39 detector. The detectors were irradiated with alpha-particles with energy of 3.5 MeV after/or before being exposed to UV radiation at 366 nm for 6 h. The detectors were etched in a 6.25 N NaOH solution at 70 °C for periods of 1–7 h. The results showed that both Vb and Vt for CR-39 exhibited an enhancement when exposed to UV, where, the alpha-particle track diameters and depths increased with UV exposure. Moreover, the study revealed that the track formation time is decreased when the CR-39 detector was irradiated with UV light.

Influence of UV irradiation on the structural and optical properties of Ch-HPQ thin films

The influence of ultraviolet (UV) irradiation on the structural, linear optical and non-linear optical properties of 2-Amino-4-(2-chlorophenyl)-6-ethyl-5-oxo-5,6-dihydro-4H-pyrano [3,2-c] quinoline-3-carbonitrile (Ch-HPQ) thin films is elaborated. The morphology of the UV irradiated, for different irradiation times, Ch-HPQ thin films is studied using both scanning electron microscopy and X-ray diffraction and compared with the UV non irradiated one. The transmittance and reflectance spectra of Ch-HPQ thin films are studied based on spectrophotometric measurements in the spectral range (200–2500) nm. Several parameters (e.g. the molar extinction coefficient, the onset and optical energy gap values) are calculated from the absorption spectra. Dispersion of the studied material is explained by Wemple and Di Domenico single-oscillator model. The influence of UV irradiation on the loss functions is discussed. The theoretical calculations of the non-linear optical parameters such as third order non-linear susceptibility and the non-linear refractive index are investigated from linear optical parameters using semi-empirical relations. The homogeneity of Ch-HPQ thin films are found to be stable under the UV irradiation which recommends using this material in optoelectronic applications.

Facile synthesis of novel NiS-Analcime composite for the efficient photocatalytic degradation of Eriochrome Black T dye

ABSTRACT In this work, novel NiS–Analcime composite was facilely synthesised via ion exchange of analcime with Ni(II) ions then precipitation of Ni(II)-Analcime utilising Na2S. Also, the synthesised composite product was characterised using XRD, FT-IR, TGA, FE-SEM, and UV-Vis techniques. Besides, the synthesised composite was employed as a photocatalyst for the photocatalytic degradation of Eriochrome Black T dye under the influence of ultraviolet irradiation. Moreover, the influence of important operating factors such as time, pH, temperature, dosage of catalyst, and primary concentration of Eriochrome Black T dye was studied. Furthermore, the results confirmed that 50 mg of NiS-Analcime composite decomposed 99.48% of 50 mL of 50 mg/L Eriochrome Black T dye within 100 min at pH = 7.5 and temperature = 25 °C. In addition, the photocatalytic degradation process followed by first-order.

Influence of Ultraviolet Irradiation and Protease on Scale Structure of Alpaca Wool Fibers

Abstract The present research aimed to explore the influence of different felt-proofing methods on alpaca fibers’ scale structure. Dyed alpaca fibers were exposed to a particular wavelength of ultraviolet (UV) light for different periods and treated with protease to analyze the felt property and compare with untreated fibers. Experimental results have shown that alpaca fibers have better shrinkage resistance and dyeability after being exposed to UV light, whereas no recognizable change was obtained on the surface of alpaca fibers’ scale structure by scanning electron microscopy (SEM). In contrary, enzyme-treated alpaca fibers revealed improved dye rate and resistance to shrinkage. Especially, damaged scales on many areas of fiber surface were appeared by SEM, which indicates that UV may have a positive effect on enzyme treatment by damaging alpaca fibers’ surface structure and promoting the amount of protease going into the fibers’ inner layers. Therefore, eventually a better shrinkage resistance was obtained.

Ультрафиолетовая активация строительного песка с учетом фактора дегидратации

The analysis of the influence of ultraviolet irradiation of building sand, which is a filler in a concrete mixture, on the dependence of the strength of concrete on the content of filler is carried out. With an increase in the content of sand due to the hydrophilicity of the surface of its particles in the mixture, the amount of free water required for the hydration of cement and the formation of cement stone decreases. Along with a decrease in the content of binder cement, this factor is an additional reason for a decrease in the strength of concrete with an increase in the content of sand. Ultraviolet irradiation leads to dehydration of the surface of the sand particles and the appearance of hydrophobic centers. As the hydrophobicity of the sand in the concrete mix increases, the content of free water available for cement hydration increases, and the strength of the cement stone increases. The change in the hydrophobicity of the surface of sand particles depending on the time of irradiation is non-monotonic. Therefore, there is an optimal UV activation mode that provides the greatest increase in concrete strength.

Influence of ultraviolet irradiation on physical properties of nano-NiO films for optical applications

NiO nanoparticles (NPs) were prepared by microwave irradiation technique. The resulted NiO NPs were affirmed during chemical precipitation by thermal analysis and X-ray diffraction (XRD) characterization. XRD showed five distinguishable peaks of NiO. The nano-NiO films were fabricated by drop solution, while the films were irradiated by UV light at different exposure periods of 0, 1, 3, and 5 h. The crystalline size of nano-NiO films was decreased from 27 to 16 nm by UV irradiation process. On the other hand, the conductivity of nano-NiO films has been observed to be increased under the effect of UV irradiation. Also, the optical constants were calculated in the range of 300–2500 nm. The mechanism of the electronic transition of the present sample was characterized by the direct allowed transition, whereas the band energy gap of the as-deposited was evaluated to be 3.81 eV and declined to 2.93 eV for the UV-irradiated film exposed to the UV rays for 5 h. However, the calculated non-linear optical parameters have been found to increase as the irradiation time exposure increases.

Influence of UV Irradiation on Corrosion Behavior of 304L SS in 0.1M H<sub>2</sub>SO<sub>4</sub> and 0.5M NaCl

This paper describes an experimental study on the effect of Ultra-Violet (UV) exposure on the electrochemical corrosion behavior of 304L stainless steel in 0.1M H2SO4 and 0.5M NaCl medium. The results of study demonstrate that in NaCl medium, exposure of both UV-A and UV-C shifts the Open Circuit Potential (OCP) in active direction (less noble) as compared to the specimen without UV exposure which indicates less stable passive film. While in sulphuric acid both UV-A and UV-C shifts OCP in noble direction which reflects the stability nature of passive film. In H2SO4 medium, exposure of both UV-A and UV-C assist in improving passivity which is indicated by lower passive current density. In NaCl medium, exposure of both UV-A and UV-C, decrease the pitting corrosion resistance as indicated by lower Epit (pitting potential) and higher Icorr (corrosion current density). In H2SO4 uniform dissolution was observed after each polarization experiment as shown in optical micrographs. In NaCl medium pitting sites are more under both type UV exposures as revealed by microstructure after polarization experiment. EIS (Nyquist plots) showed that exposure of both UV-A and UV-C in NaCl medium specimens have lower polarization resistance (Rp) than without UV exposure. Lower Rp confirms lesser protectiveness of passive film. In case of H2SO4, higher arc radius (Rp) is observed under UV exposure for both UV-A and UV-C.

Structural and tensile characteristics of reduced graphene oxide/poly (vinyl alcohol) composite films: Influence of ultraviolet irradiation

AbstractThe influence of ultraviolet (UV) radiation on the structural and uniaxial tensile characteristics of reduced graphene oxide (rGO)/poly(vinyl alcohol) (PVA) composite films produced by using various contents (0‐10 wt%) of rGO obtained by a microwave‐assisted reduction process was investigated. With increasing rGO content, significant reinforcing effects of the rGO sheets were seen on the tensile characteristics of the unirradiated rGO/PVA composite films, that is, increases in the stiffness and rigidity and decreases in the strain at break values. After UV exposure times from minutes up to 1 hour, for all the rGO contents, the rGO/PVA composite films had improved tensile strength and modulus values as well as considerable improvement in the stress‐strain behavior in spite of great decreases in the strain at break values. The structural changes responsible for the improvement in the tensile strength and Young's modulus of the rGO/PVA composite films were associated with the development of strong intermolecular interactions between the rGO sheets and the PVA polymer chains through the formation of hydrogen bonds. Deterioration of the mechanical characteristics, especially strain at break values, was mainly due to the photodegradation of the structural units induced by UV radiation leading to the formation of some free radicals caused by the chemical bond breakages in the polymer chains as well as the weakening of intermolecular interactions such as hydrogen bonds. Correlation between the changes in the tensile properties and the structure of the rGO/PVA composite films were sought by analyzing tensile testing, fourier transform infrared/attenuated total reflectance (FTIR/ATR), and UV‐visible spectral results.

UV-irradiation effects on tuning LSPR of Cu/Ag nanoclusters in ion exchanged glass matrix and its thermodynamic behaviour

Cu/Ag nanoclusters were grown in a soda-lime glass matrix by an ion-exchange method followed by ultra violet (UV)-irradiation. In this article, the present study has been focused on the nucleation and growth of Cu/Ag nanoclusters under the influence of UV-irradiation. The sizes calculated from the transmission electron microscopy results were closely matched with those obtained from Mie theory-based results. The results revealed that the spherical shaped Cu/Ag nanoclusters were incorporated into the glass matrix under the influence of UV-irradiation and the size of the Cu/Ag nanoclusters varied from 25 nm to 37 nm. The optical, structural, morphological and chemical state were further studied by using UV–Vis. absorption spectroscopy, Raman spectroscopy, X-ray diffraction, Transmission electron microscopy, and X-ray photoelectron spectroscopy. Plasmonic and thermodynamic behaviour of the Cu/Ag nanoclusters were tuned by the UV irradiation and have been explained at variable irradiation time. The distribution and optimization of the Cu/Ag nanoclusters were further investigated using enthalpy (ΔH), entropy (ΔS) and Gibbs energy (ΔG) physicochemical activities and their interdependence for the nucleation and growth of Cu/Ag nanoclusters under the influence of UV irradiation. The UV–irradiation induced and Cu/Ag nanostructure growth process. Their growth impact on optical and thermodynamic properties were explored.

Effect of hydrogen loading and UV irradiation on the gain of Er$^{3+}$-doped fibers

Molecular hydrogen loading and a subsequent 193-nm ultraviolet (UV) irradiation influence on the gain properties of Er3+-doped core silica optical fibers are demonstrated in this work. The dynamics of photoinduced changes’ formation and subsequent dissociation in this fiber type is demonstrated. H2 loading results in less than a 10% fiber-gain decrease, whereas subsequent UV irradiation results in almost twice the gain degradation. Furthermore, UV-induced defects partially dissociate under the influence of 976-nm pump radiation. At least two independent types of gain degradation mechanisms of H2-loaded active fiber under the influence of UV irradiation are shown.

Influence of ultraviolet irradiation on the thermal properties оf polymer composites based on polyepoxide ED-20

Influence of ultraviolet irradiation on the thermal properties оf polymer composites based on polyepoxide ED-20