Radiation Of Different Wavelengths Research Articles

Антимікробна та противірусна активність нанокомпозитів на основі поліелектролітних комплексів з наночастинками срібла

Recently, nanocomposite materials containing nanoparticles of metals such as silver, copper and zinc oxide have attracted most attention due to their pronounced pharmacological properties, such as antimicrobial, antiviral, antiinflammatory, immunomodulatory ability and high stability in extreme conditions. Polyelectrolyte complexes based on polymers of natural origin, namely polysaccharides of chitosan and pectin, which can stabilize nanoparticles of a smaller size than individual polymers have significant potential for creation of silver-containing nanocomposites. The aim of this article is to study the antimicrobial and antiviral activity of silver-containing nanocomposites based on polyelectrolyte complexes. Methods. Peculiarities of the structural organization of silver-containing nanocomposites were investigated by the method of wide-angle scattering on an XRD-7000 diffractometer. The morphology of Ag nanoparticles in polymer matrixes were studied by transmission electron microscopy method (transmission electron microscope JEOL 100 CXII). The antimicrobial activity of silver-containing nanocomposites was determined by agar diffusion assays against opportunistic pathogens Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. Cytotoxicity and antiviral activity were investigated using the MTT method and staining by gentian violet. Results. Analysis of wide-angle X-ray diffractograms of silver-containing nanocomposites based on polyelectrolyte complexes Na-CMC (pectin) – chitosan showed that at reduction of Ag+ ions to metallic silver, there are two low-intensity diffraction maxima at 2θm ~ 380 and 440 in the diffractograms. These maxima correspond to the crystallographic planes of the face-centered cubic lattice of silver, are characterized by indices (111) and (200), respectively, and confirm the presence of metallic silver in the polymer system. Analysis of micrographs of silver-containing nanocomposites based on Na-CMC and chitosan showed that larger nanoparticles are formed with increasing the molecular weight of chitosan. The dependence of the size of silver nanoparticles on the wavelength of ultraviolet radiation at reduction of silver ion in polyelectrolyte-metal complexes Na-CMC–Ag+–chitosan of low molecular weight was also revealed. In particular, smaller particles are formed under irradiation by light with a shorter wavelength (λ =254 nm) than at λ=365 nm. Silver-containing nanocomposites Na-СMC-Ag-chitosan and pectin citrus-Ag-chitosan, obtained by reduction of Ag+ ions under ultraviolet irradiation at a wavelength λ = 365 nm and λ = 254 nm, exhibit high antimicrobial activity against the test cultures of microorganisms S. aureus, E. coli, and P. aeruginosa C. albicans. No significant dependence of antimicrobial activity on the molecular weight of the studied samples was noted: the obtained data were within close limits and had close values. In addition, no dependence of antimicrobial activity on the type of investigated test cultures of microorganisms was observed either. Nanocomposites based on Na-CMC-chitosan (λ = 365 nm) inhibited infection titer HSV-1 by (3.72–5.45) lgTCID50/mL, whereas the decrease in titer during incubation with samples based on citrus pectin-chitosan was within (2.39–2.42) lgTCID50/mL. A dose-dependent relationship between molecular weight of chitosan and reduction of infection titer was observed. It was found that silver-containing nanocomposites formed by reduction of silver ions in polyelectrolyte-metal complexes under ultraviolet radiation of different wavelengths had no cytotoxic effect on cells of MDCK and BHK. Conclusions. The investigated silver-containing nanocomposites based on Na-CMC (pectin)-chitosan polyelectrolyte complexes show antimicrobial activity against test cultures of S. aureus, E. coli P. aeruginosa, and C. albicans along with antiviral activity against herpes simplex virus type 1 and influenza virus. It was established that the obtained nanocomposites did not show a cytotoxic effect on MDCK and BHK cells. The obtained data allow us to assert that investigated silver-containing nanocomposites are promising antimicrobial means for the development of new effective strategies against microorganisms and viruses and improvement of the population health.

Photochemical processes to cellular DNA damage by UV radiation of different wavelengths: biological consequences

UV radiation of sunlight induces in cellular DNA of different organisms photochemical reactions, which may lead to the development of series biological responses to arising lesions, including apoptosis, mutagenesis, and carcinogenesis. The chemical nature and the amount of DNA lesions depend on the wavelength of UV radiation. Photons of UV radiation in the region B (UVB, 290–320 nm) cause the production of two main defects, namely, cyclobutane pyrimidine dimers and, with a less yield, pyrimidine (6-4) pyrimidone photoproducts; their formation is the result of the direct UVB photon absorption by DNA bases. Photons of UV radiation in the region A (UVA, 320–400 nm) induce only cyclobutane dimers that can be formed by triplet-triplet energy transfer from cellular chromophores, absorbing photons of this UV region, to DNA thymine bases. UVA is much more effective than UVB in the sensitized oxidatively lesion formation in DNA such as single strand breaks and oxidized bases; among those, 8-oxo-dihydroguanine is the most frequent since it can be produced from several oxidation processes. In recent years, multiple papers, reporting novel, more detailed information about molecular mechanisms of photochemical reactions underlying the formation of different lesions in DNA were published. The present review mainly aims at summarizing and analyzing data contained in these publications, particularly regarding oxidative reactions that are initiated by reactive oxygen species and radicals generated by potential endogenous photosensitizers such as pterins, riboflavin, protoporphyrin IX, NADH, and melanin. The role of specific DNA photoproducts in genotoxic processes induced in living systems by UV radiation of different wavelengths, including human skin carcinogenesis, is discussed.

Quantitative analysis of wavelength dependence of thermal perception

In recent years, significant progress has been made in the development of materials that selectively reflect or absorb radiation in specific wavelength ranges. Previous studies have shown that the same intensity of radiation can produce different degrees of thermal perception depending on its wavelength. This difference is thought to be the optical properties of the skin. However, these findings have not been quantitatively verified yet. The purpose of this study is to quantitatively analyze the effects of radiation of different wavelength ranges on thermal sensation. We conducted a human subject experiment and discovered that far-infrared radiation causes a warmer and more uncomfortable sensation than near-infrared radiation. To interpret these results, we developed a new mathematical model that predicts thermal perception caused by radiation of different wavelengths. The model is based on a heat diffusion equation within the skin and considers the optical properties of the skin to simulate thermoreceptor activities in response to given spectral irradiances. Our model explained the observed phenomenon in our and previous experiments, where the same intensity of radiation but at different wavelengths can produce different degrees of thermal perception, in terms of physiological mechanisms. Additionally, the model revealed a hierarchy in thermal sensation, with far-infrared radiation being perceived as the warmest, followed by mid-infrared, visible, and near-infrared radiation. These findings are crucial for designing materials that selectively reflect or absorb radiation in specific wavelength ranges, and for developing heaters that provide efficient heating with low energy consumption.

Study on electron response to near-infrared, ultraviolet and extreme ultraviolet femtosecond laser by first-principle

The phenomenon of laser-induced electronic evolution in semiconductors is an essential issue in laser fabrication, which has been extensively investigated within the near-infrared and visible spectral ranges. However, electronic evolution at short wavelength laser has neither been systematically investigated. In this paper, time-dependent density functional theory is employed to investigate the response in silicon under laser irradiation of different wavelengths. The result shows that shorter wavelength induces the excitation of electrons to higher energy levels, consequently leading to increased impact ionization rates. Such a moderate excitation of energetic electrons even at low-medium intensity is considered as a distinctive feature of extreme ultraviolet light laser, which is expected to further enhance the quality of laser processing.

Stability of monomeric indigo in the electronic ground state: An experimental matrix isolation infrared and theoretical study

Monomers of indigo were investigated using experimental (matrix-isolation) and theoretical methods. For the first time, the infrared spectrum of indigo molecules isolated in low-temperature Ar matrices was recorded and subjected to a detailed theoretical analysis. An excellent agreement between the experimental spectrum of indigo monomers and the spectrum theoretically predicted for the highly-symmetric (C2h) most stable dioxo form of the compound allowed a very reliable assignment of the observed infrared absorption bands. Matrix-isolated monomers of indigo were exposed to UV–vis radiation of different wavelengths. The conducted experiments demonstrated that molecules of indigo do not undergo any structural changes, even under irradiation with short-wavelength UV (λ > 200 nm) light. Theoretical calculations concerning the stability of photoproducts that could be potentially generated from indigo were conducted. The calculations carried out for the species generated by hydrogen-atom transfer from N1′ to O atom attached to the opposite ring revealed that both the oxo-hydroxy and dihydroxy tautomers of indigo should be unstable in the ground electronic state. The calculations carried out for the C2H tautomer (which may be generated by a hydrogen atom shift from N1′ to C2 of the opposite ring) led to optimization of the structure that is potentially stable, but very much distorted from planarity.

Nutritional and Physiological Effects of Postharvest UV Radiation on Vegetables: A Review.

Effective ultraviolet (UV) irradiation has been used as a postharvest technology to reduce decay, delay ripening, and delay senescence in crop products. In this review, the effects of UV radiation of different wavelengths and doses on physiological and phytochemical parameters in postharvest vegetables are discussed in summary, including appearance (color and texture), microbial load, respiration rate, enzymatic antioxidant system, and various bioactive compounds (phenolic compounds, carotenoids, chlorophylls, vitamins, glucosinolates, betalains, and antioxidant activities). In particular, postharvest UV radiation affects oxidative metabolism and increases the antioxidant activity of plant products, which could help delay yellowing and senescence of vegetables, trigger defense responses, and reduce decay and diseases. In some cases, irradiation stimulates the synthesis of bioactive secondary metabolites that may improve the nutritional value of vegetables. The findings presented in this review are very useful and valuable for the preservation and improvement of the nutritional quality of vegetables after harvest. It will also provide scientific support for industrial and commercial applications of UV radiation in postharvest.

Joining Two Switches in One Nano-Object: Photoacidity and Photoisomerization in Electrostatic Self-Assembly.

Multi-switchable supramolecular nano-objects that respond to irradiation of different wavelengths with changes in size and shape have been built from two different water-soluble molecular switches, joined by attachment to the same polyelectrolyte. Accordingly, two wavelength-specific reactions, namely the excited-state proton dissociation of a photoacid and the cis-trans isomerization of an azo dye, are combined in one supramolecular nano-object that is stable in aqueous solution. The concept has potential in the fields of sensors, molecular motors, and transport.

Design of Multi-Wavelength Diffractive Lenses Focusing Radiation of Different Wavelengths to Different Points

We propose a method for calculating the so-called multi-wavelength diffractive lenses (MWDLs) intended for separating and focusing the radiation of L given wavelengths to L given points located in a certain plane perpendicular to the optical axis. The method is based on minimizing the objective function characterizing the deviation of the complex transmission functions of the MWDL from the complex transmission functions of diffractive lenses focusing the design wavelengths to the given points. In the method, the MWDL calculation is reduced to a set of independent pointwise optimization problems, each of which describes the calculation of the MWDL microrelief at one point. The presented results of the numerical simulation of the designed MWDLs confirm high performance of the proposed method. The numerical simulation results are confirmed by the results of experimental investigations, including the fabrication of MWDLs using the direct laser writing technique and the study of the MWDL operation in an optical experiment.

Application of absorption of infra-red radiation and reflection spectra to distinguish different inks of same color in alteration

The main aim of this study is to introduce non-destructive method to distinguish different types of ink of same color. In our daily life, we face many problems of alteration of genuine documents. Such alteration is done by using same color of ink as used in the document. It is not possible to differentiate the altered part by our naked eyes. There are many methods, destructive as well as non-destructive methods, to solve the problem of alteration. We have discussed the non-destructive method using Video Spectral Comparator (VSC)-6000. Analysis is carried out with application of infra-red (IR) radiation of different wavelength and reflection spectra to reach the conclusion. Absorption of infra-red (IR) radiation is found very effective whereas use of reflection spectra is totally failed in this experiment. BIBECHANA 19 (2022) 34-39

Investigation on response of ophthalmic photochromic TRANSITIONS SIGNATURE® VII lens to ultraviolet radiation

The activation and deactivation of photochromic TRANSITIONS SIGNATURE® VII lens under extreme exposure to ultraviolet radiation of 222 W/m2 for more than 144 h are scrutinized. The photoluminescence (PL) spectra upon excitation with ultraviolet radiation of different wavelengths have been investigated. The obtained results show that photochromic TRANSITIONS SIGNATURE® VII gray lenses blocked ultraviolet radiation from 190 nm to 400 nm. The absorbance increases from 0.021 to be about 0.44 upon exposure to ultraviolet radiation of 302 nm for 144 h. The deactivation rate is decreasing exponentially with elapsed time; the absorbance reduces to be half after 5 min. Under extreme exposure to ultraviolet radiation of 302 nm the lens transmittance dynamic range reduces from 21.10 to be 7.20, also the optical band gap is insignificantly decreased from 2.913 eV to 2.869 eV indicating that the lens is non-degradable. TRANSITIONS SIGNATURE® VII lens was irradiated with ultraviolet radiation in the wavelength range from 260 to 400 nm and the photoluminescence (PL) emission spectra were measured. A strong correlation between the PL spectra and the excitation wavelength of ultraviolet radiation was observed. Both the PL integrated area under the peak and its band peak height are associated with the excitation wavelength, peaking at 275 nm and 385 nm, respectively, and then decreasing as the ultraviolet radiation wavelength increased. These results demonstrate that TRANSITIONS SIGNATURE® VII lenses are resistant to all ultraviolet radiation as well as blue light where Chromea7™ is activated.

Antenna designing for efficient rectenna solar cells

The rectenna solar cell is considered to be one of the best photovoltaic devices due its effective light to electric energy conversion performance. New ideas are needed to improve the design of efficient rectenna solar cells. In this paper, we have described a novel design of an antenna associated with a rectifier. Solar spectrum contains radiation of different wavelengths and intensities. The intensity of solar radiation is maxima at around the 500 nm wavelength. The monopole antenna of the length 125 nm (dipole of the length 250 nm) converts the maximum energy of the solar spectrum. Metallic behaving nano rods may be better as the antenna. The carriers of the nano rod should remain free from any bias for highly efficient rectenna solar cells. The pn junction should be used as a rectifier in the rectenna solar cells to get better receiving power. The rectifier(s) position may keep a role to increase the receiving power. Furthermore, we proposed some important analytical investigations that could help to optimize the antenna carrier density.

Targeted and non-targeted effects of radiation in mammalian cells: An overview

Radiation of different wavelengths can kill living organisms, although, the mechanism of interactions differs depending on their energies. Understanding the interaction of radiation with living cells is important to assess their harmful effects and also to identify their therapeutic potential. Temporally, this interaction can be broadly divided in three stages – physical, chemical and biological. While radiation can affect all the important macromolecules of the cells, particularly important is the damage to its genetic material, the DNA. The consequences of irradiation include- DNA damage, mutation, cross-linkages with other molecules, chromosomal aberrations and DNA repair leading to altered gene expression and/or cell death. Mutations in DNA can lead to heritable changes and is important for the induction of cancer. While some of these effects are through direct interaction of radiation with the target, radiation can interact with the surrounding environment to result in its indirect actions. The effects of radiation depend not only on the total dose but also on the dose rate, LET etc. and also on the cell types. However, action of radiation on organisms is not restricted to interactions with irradiated cells, i.e. target cells alone; it also exerts non-targeted effects on neighboring unexposed cells to produce productive responses; this is known as bystander effect. The bystander effects of ionizing radiations are well documented and contribute largely to the relapse of cancer and secondary tumors after radiotherapy. Irradiation of cells with non-ionizing Ultra-Violet light also exhibits bystander responses, but such responses are very distinct from that produced by ionizing radiations.

Effect of Different Wavelengths of Laser Irradiation on the Skin Cells.

The invention of systems enabling the emission of waves of a certain length and intensity has revolutionized many areas of life, including medicine. Currently, the use of devices emitting laser light is not only an indispensable but also a necessary element of many diagnostic procedures. It also contributed to the development of new techniques for the treatment of diseases that are difficult to heal. The use of lasers in industry and medicine may be associated with a higher incidence of excessive radiation exposure, which can lead to injury to the body. The most exposed to laser irradiation is the skin tissue. The low dose laser irradiation is currently used for the treatment of various skin diseases. Therefore appropriate knowledge of the effects of lasers irradiation on the dermal cells’ metabolism is necessary. Here we present current knowledge on the clinical and molecular effects of irradiation of different wavelengths of light (ultraviolet (UV), blue, green, red, and infrared (IR) on the dermal cells.

Investigation of the spectral characteristics of silicon photomultiplier tubes

Успехи прикладной физики, 2021, том 9, No 2165I. R. Gulakov, A. O. Zenevich, and O. V. KocherginaBelarusian State Academy of Communications8/2 F. Skorina st., Minsk, 220114, BelarusE-mail: o.kochergina@bsac.byReceived January 12, 2021Recently multipixel avalanche photodetectors, called silicon photomultipliers are of-ten used to record optical radiation. The influence of ambient temperature and sup-ply voltage on the spectral sensitivity and dynamic range of prototypes of silicon pho-tomultipliers manufactured by JSC "Integral" (Republic ofBelarus) and commercially available photomultipliers KetekRM 3325 and ON Semi FC 30035 has been investigated in this article. It was determined that the spectral sensitivity maxi-mum of silicon photomultipliers is shifted to the short-wavelength region andcorre-sponds to the wavelength of optical radiation of 470 nm. It is shown that an increase in the supply voltage leads to an increase in the sensitivity of the investigated photodetectors, and the dependence of the sensitivity on temperature manifests itself in different ways when exposed to optical radiation of different wavelengths.

Light and Skin.

Sunlight comprises radiation of different wavelengths, of which UVA and UVB are most important with respect to human skin diseases. Next to erythema, edema, and sunburns, UV radiation causes skin cancer. UV radiation of any wavelength is now considered as a class I carcinogen to humans. The mutagenic effects of UV radiation depend on DNA damage following direct absorption by nuclear DNA, resulting in cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidone photoproducts that, if not repaired by nucleotide excision repair pathway, result in characteristic UV signature mutations (C→T or CC→TT transition). In addition, increased formation of reactive oxygen species by UV exposure may cause formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine leading to T→G transversion. In addition, UV radiation has been shown to induce a number of immune modulations that largely result in local and potentially also in systemic immunosuppression, which may not only impair control of dysplastic and neoplastic skin lesions but also affect immuno-pathological and infectious skin diseases. Recent find-ings have shown that ambient doses of high-energy visible light, beyond the UV range, may also cause damage to human skin.

Mass-Independent Sulfur Isotope Fractionation in the Photochemical SO2 Processes under the UV Radiation of Different Wave Length

A series of photochemical experiments with sulfur dioxide were carried out using a xenon lamp (λ > 200 nm), a low-pressure mercury lamp (λ = 184.9 and 253.7 nm), and an UP-213 laser system (λ = 213 nm) as light sources. Based on the isotope data obtained for elemental sulfur (the end product of SO2 photolysis), we revealed specifics in correlations between δ34S, ∆33S, and ∆36S values depending on the spectral characteristics of the incident radiation. Our studies showed that the Archean Δ33S/δ34S and Δ36S/Δ33S ratios could be reproduced in the SO2 photolysis experiments by combining spectral composition of the radiation, the intensity of the spectral components, and the partial pressure of SO2. The results of the experiments suggest that the UV radiation with wavelengths less than 200 nm was a determining factor in the production of sulfur isotopic anomalies in the Archean atmosphere.

Влияние различных спектров видимого света на антиоксидантную активность растений

Growing plants under conditions of closed soil using various technologies allowed physiologists to influence their metabolism. The most "environmentally friendly," and not fully studied, are technologies using light of various spectral composition that affects growth, leaf anatomy, secondary plant metabolites and chloroplast ultrastructure. The problem of directed regulation of components of the production process of phytocenoses during artificial irradiation is an urgent task. The authors have previously published data on the effect of ultraviolet radiation on the biochemical properties of plants. As a continuation of these studies, the purpose of the present work was to study the effect of various spectra of visible light on the antioxidant activity of plants. Influence of monochromatic LED irradiation of different wavelength at equal power of radiation on seed germination and change of total antioxidant activity of Abyssinian and sugar beets is studied in the paper. The level of antioxidant activity during sprouting in the light decreased by 17.8-26.7% compared to dark sprouting, which can serve as an indicator of a decrease in the level of stressful effects. At the same time, with an increase in the level of stress (in the red light version – a decrease in the biomass of 100 sugar beet sprouts by 41.8%), there was an increase in the total antioxidant activity by 8.6%, which, according to the literature, may be associated with the activation of plant antioxidant systems as an adaptive reaction to stress. The stimulating effect of irradiation of seeds and sprouts with green light (520 nm) is shown – increase of biomass of 100 sprouts by 45.8% of sugar beet compared to the recommended GOST dark germination, in nougat – by 27.8%. Genetic differences in the reaction of germination of seeds of two crops to monochromatic radiation of different wavelength are established and the need to develop differentiated modes of radiation of seeds when growing microzelenium is justified.

Tuning Redox Potential of Gold Nanoparticle Photocatalysts by Light.

Metallic nanoparticle-based photocatalysts have gained a lot of interest in catalyzing oxidation-reduction reactions. In previous studies, the poor performance of these catalysts is partly due to their operation that relies on picosecond-lifetime hot carriers. In this work, electrons that accumulate at a photostationary state, generated by photocharging the catalysts, have a much longer lifetime for catalysis. This approach makes it possible to determine and tune the photoredox potentials of the catalysts. As demonstrated in a model reaction, the photostationary state of the photocatalyzed oxidative etching of colloidal gold nanoparticles using FeCl3 was established under continuous irradiation of different wavelengths. The photoredox potentials of the nanoparticles were then calculated using the Nernst equation. The potentials can be tuned to a range of 1.28 to 1.40 V (vs SHE) under irradiation of different wavelengths in the range of 450 to 517 nm. The effects of particle size or optical power on the photoredox potentials are small compared to the wavelength effect. Control over the photoredox potential of the particles using different excitation wavelengths can potentially be used to tune the activities and selectivities of metallic nanoparticle photocatalysts.

Rb2CO3-decorated In2O3 nanoparticles for the room-temperature detection of sub-ppm level NO2

The Rb2CO3-decorated In2O3 sensor is prepared for detection of NO2 at room temperature under light irradiation. Physical and chemical properties of the materials and structures are thoroughly investigated by various analytical tools of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy, thereby confirming the formation of the Rb2CO3/In2O3 p-n junction at the interface. The Rb2CO3-decoration effect on In2O3 sensor is examined under light irradiation of different wavelengths and intensities. Rb2CO3-decoration exhibits much higher sensing performance than pure In2O3 sensor, and furthermore, the visible light irradiation improves in the response level and sensing kinetics. The sensor detects less than 100 ppb NO2. In addition, the Rb2CO3-decorated In2O3 sensor shows high selectivity, stability, repeatability, and linearity. The ultimate performance of the nanostructured sensor is elucidated by the depletion model of the conduction type gas sensors. The effect of humidity on the sensing performance is also investigated.

Effect of photobiomodulation therapy as an adjunct to scaling and root planing in a rat model of ligature-induced periodontitis: a histological and radiographic study.

This study aimed to histologically and radiographically evaluate the effectiveness of low-intensity laser irradiation of different wavelengths (660 or 808nm) as an adjunct to scaling and root planing in the treatment of experimental periodontitis in rats. Periodontitis was induced by placing a ligature around the mandibular first molar of the rats. In total, 40 Wistar rats were randomly divided into five groups (n = 8 each): control (CG), periodontal disease (PD), scaling and root planing (SRP), SRP + 660nm laser (GL660) and SRP + 808nm laser (GL808). Groups with laser use received radiation at 6 points in the first molar. The animals were euthanized at baseline and at 7 and 14days after the interventions. Mandibles were surgically removed for histomorphometric and radiographic assessment of periodontal tissues. The GL660 group showed lesser bone loss than the PD group (P < 0.05) and greater alveolar bone margin after 14days, indicating a better long-term treatment response (P < 0.05). These findings suggest that SRP with the 660nm laser as an adjunct results in more favorable radiographic and histological responses than the 808nm laser.