Action Of Radiation Research Articles

Molecular mechanisms of effects of ionizing radiation action. Irradiation effect on protein (literary review)

Target effects (direct and indirect effects of ionizing radiation). When exposed to ionizing radiation, it damages vital intracellular biomolecules which leads to multiple damage to cells and tissues as well as pathophysiological diseases such as inflammation, immunosuppression, etc. Such damage can be caused by direct ionization of biomolecules, but in almost 70% of cases due to indirect radiolysis of intracellular water with the formation of reactive oxygen species and free radicals, which ultimately causes oxidative stress.Non-target effects (abscopal effect, adaptive response, bystander effect, genomic instability). Over the past 25 years, many studies have explored the molecular mechanisms underlying in nontargeted effects (also known as effects not aimed at DNA). It is shown that these effects are the result of a huge dynamic and complex process induced in irradiated cells, transmitted to neighboring cells and, to some extent, to the whole body through activation of the immune system.The irradiation effect on protein. Under the direct action of ionizing radiation on a protein, an electron is knocked out of it, resulting in a defective site devoid of an electron, which migrates along the polypeptide chain due to the transfer of electrons until it reaches a site with increased electron-donor properties. At this point, free radicals arise in the side chains of amino acids. Under the indirect effect of ionizing radiation, the formation of free radicals occurs when protein molecules interact with the products of water radiolysis.

Nanoscale study on adhesion performance and aging degree prediction of warm mix asphalt under UV aging condition

Compared with hot mix asphalt, warm mix asphalt ( WMA) has inferior adhesion performance, and ultraviolet (UV) aging will further weaken the adhesion performance of WMA. There are, however, few investigations on the aging mechanism under conditions of single UV radiation, and the majority of current research on UV aging is conducted under the combined action of UV radiation and oxygen. In this paper, an indoor accelerated experimental equipment for UV aging was developed, and two experimental schemes of oxygen isolation condition and light-oxygen coupling condition were designed. The developed UV aging tests were carried out on WMA this for 0–50–100–150 and 200 h. The nano adhesion properties were studied by atomic force microscopy ( AFM) and gel permeation chromatography ( GPC) experiments. The characterization method of WMA nano adhesion performance was proposed using correlation analysis. In addition, the nonlinear differential equations between nano-indexes and aging time were established by the Verhulst model. The results showed that the generation of microcracks and the increase of large molecular weight during UV aging will decrease WMA adhesion performance, and the degradation is more significant under the light-oxygen coupling conditions. Moreover, the correlation coefficients between large molecular weight and nano-adhesion under two UV aging conditions were higher than 0.90, showing that large molecular weight could characterize the degradation of nano-adhesion of WMA after UV aging. The saturation characteristics of the honeycomb structure area ratio were prominent, and the coefficient of determination of the nonlinear equations were higher than 0.93 for both two UV aging conditions. The aging model can be used to accurately characterize and predict the WMA UV aging state through the variation of honeycomb structure area ratio.

MICROWAVE TECHNOLOGY OF LIQUID-GLASS HEAT-INSULATING MATERIALS BASED ON A GRANULAR PRODUCT

The paper investigates the properties of liquid glass thermal insulation products obtained on the basis of granular products under the influence of microwave radiation. Due to the volumetric heat release in the thickness of the liquid glass composition, it is possible to obtain homogeneously structured materials by applying the technology of simultaneous porosization with volumetric expansion of both granules and binder. Thanks to volumetric heating and the mechanism of "non-thermal" effect of microwave radiation on the processing objects, the duration and temperature of their heating is significantly reduced, as well as the operational properties of the products are improved. The properties of materials obtained by this technology are compared with the properties of materials obtained by binding pre-swollen granules. It was proved that the simultaneous swelling of granules with a binder made it possible to obtain materials of a monolithic, uniformly porous structure with high physical and mechanical parameters and an order of magnitude lower indicators of water absorption and sorption moisture due to the dense packing of the granules and the uniform distribution of the binder in the intergranular space. The developed technology for the production of composite materials in the form of heat-insulating products of various configurations by means of simultaneous porosization with volume expansion of granules and binding under the action of microwave radiation allows to obtain materials with a better set of operational characteristics than in the case of binding pre-swollen granules at lower energy costs for their production because it excludes the stage of separate swelling of the granules. The resulting composite thermal insulation materials do not deform and have a fairly high strength for their average density. They are practically incompressible, and this is a very important fact, since the compression of heat insulating materials over time leads to an increase in its thermal conductivity and a decrease in the heat-shielding properties of the structure.

Tailoring Photoprotection of Polylactide with New Isobornyl Derivatives of Phenol and Aniline.

This article is devoted to the development of new photostabilizers for polylactide (PLA), a polymer that is an environmentally friendly alternative to polymers and is based on fossil raw materials. We have elucidated the role of the reaction center of two potential PLA photoprotectors: N-isobornylaniline and 2-isobornylphenol, in reactions occurring in a polymer matrix under the action of UV-C radiation. PLA samples with the photostabilizers were irradiated under a wavelength of 253.7 nm for 4, 8 and 12 h. The effectiveness of the photostabilizers was evaluated based on FTIR spectrometric data, 1H and 13C NMR, scanning electron microscopy and simultaneous thermal analysis (TG-DSC). Both stabilizers led to the protection of ester bonds between monomer units of PLA. However, 2-isobornylphenol proved to be more effective at a concentration of 0.05 wt.%, while the optimal concentration of N-isobornylaniline was 0.5 wt.% by weight. TG-DSC showed that the addition of N-isobornylaniline led to an increase in PLA resistance to thermal decomposition; the temperature of the onset of weight loss increased by 2.8 °C at 0.05 wt.% and by 8.1 °C at 0.5 wt.% of N-isobornylaniline. The photoprotector 2-isobornylphenol, on the contrary, reduced the thermal stability of PLA.

Determination of the resistance of water-repellent properties to ultraviolet radiation on self-hydrophobized surface textures of AISI 304 steel

In this work, the object of the study were femtosecond laser textured steel samples. Using a femtosecond laser to texture the surface both in the direct-beam mode, which provides microtextures, and in the reflection mode, which leads to the formation of LIPSS-type nanostructures on the surface. Such hybrid complexes are optimal in terms of water repellency as they embody the principle of hierarchical textures. This approach is one of the promising ways to solve the problem of scaling the process of obtaining superhydrophobic metal surfaces. The aim of the work is to establish the stability of water-repellent properties of micro- nanotextures obtained on the surface of AISI 304 steel after spontaneous hydrophobization under the action of UV radiation. The study of the obtained textured surface by scanning electron microscopy to confirm the presence of nanotexture and by energy-dispersive X-ray spectroscopy to establish the elemental composition of the obtained microtexture were made in the work. The paper shows that the water repellency of AISI 304 steel surfaces textured at micro and nano levels by femtosecond laser after long exposure to the atmosphere increases to a superhydrophobic state with the value of contact angles up to 155°. It has been shown that such surfaces are sensitive to UV radiation. Depending on the type of structure, the loss of hydrophobicity under experimental conditions occurs in 15-45 minutes of exposure, and complete hydrophilization of the surface occurs after 100 minutes of irradiation. As a result, the obtained self-hydrophobic surfaces are not suitable for operation under the influence of sunlight. However, ultraviolet radiation can be used to pre-clean such surfaces from adsorbed organic contaminants.

Morphological substantiation of laser exposure parameters and modes for surgical treatment of intrauterine pathology

Introduction No data on experimentally substantiated parameters and modes of diode laser radiation allowing a minimally traumatic surgical treatment of intrauterine pathology have been found in the literature.The aim of the investigation was to substantiate experimentally the optimum parameters and modes of diode laser radiation in the treatment of intrauterine pathology based on the study of morphological changes in the endometrium.Materials and methods 48 endometrial samples were exposed to 10-40 W diode laser power in a constant mode and 15 samples - in a pulsed mode with 3 different sets of laser exposure parameters. The data were statistically processed using Microsoft Excel spreadsheets, version 16.49. The differences were considered statistically significant at р<0.05.Results Width of the ablation zone, lateral coagulation and hyperthermic exposure zone was calculated at the most optimal parameters of laser energy (20 W), achieving adequate cutting and bleeding properties of the laser. The most effective in the pulsed mode of laser operation was 30 W amplitude power of radiation, the pulse duration of 100 ms, the duration of the interval between pulses of 50 ms, the average power of 20 W.Discussion Comparative analysis of morphometric parameters in the action of laser radiation in the constant mode with a radiation power of 20 W and in the pulsed mode with an average laser power of 20 W has shown that the structural parameters have significantly lower values in the pulsed laser mode.Conclusion Optimal cutting properties of the laser are observed when constant laser irradiation with a power of 20 W is used. The best cutting and bleeding properties were demonstrated by the pulsed laser mode with an average power of 20 W, amplitude power of 30 W, pulse duration of 100 ms, and inter-pulse interval of 50 ms.

Charged Hybrid Microstructures in Transparent Thin-Film ITO Traps: Localization and Optical Control

In the present study, we propose a new transparent thin-film ITO surface radio-frequency (RF) trap. Charged hybrid microstructures were localized in the developed ITO trap. We show, analytically and experimentally, that the position of the localization zones in the trapped hybrid structure are stable. The transfer of charged particles between localization zones was studied under the action of gravity-compensating laser radiation. We highlight the advantages of transparent thin-film ITO traps to investigate and manipulate charged particles.

Development of Aedes aegypti L. under the action of light radiation at different wavelengths

Aedes aegypti is a holometabolous insect, vector of medical importance for arboviral transmission, and has shown the ability to develop chemical larvicides resistance, which are the worldwide used to control mosquitoes’ population because of their low cost. Due to the well-known photophobia, a striking characteristic of the behavior of A. aegypti larvae, this study aimed to observe the development of this insect in its larval stage under the action of certain ranges of light radiation and its possible biological effects. For that, the experiments used larvae in L1, observed during seven days under the action of LEDs (light-emitting diode) that emitted light at different wavelengths, with six different colors, one for each experiment. Some were tested with a light-dark interval every 10 minutes and others every two minutes, with three repetitions. At the end, mosquitoes, pupae and larvae were counted and the data submitted to statistical evaluation. The experiment showed a significant difference between the control and the different wavelengths used, when exposed at two-minute intervals. LEDs that emitted blue (λ = 457.9 nm) and white (λ = 448.58 nm) wave frequencies were the most promising for the development of equipment that could act synergistically with other forms of control in order to improve its efficiency.

Space radiation quality factor for Galactic Cosmic Rays and typical space mission scenarios using a microdosimetric approach

Space radiation exposure from omnipresent Galactic Cosmic Rays (GCRs) in interplanetary space poses a serious carcinogenic risk to astronauts due to the—limited or absent—protective effect of the Earth’s magnetosphere and, in particular, the terrestrial atmosphere. The radiation risk is directly influenced by the quality of the radiation, i.e., its pattern of energy deposition at the micron/DNA scale. For stochastic biological effects, radiation quality is described by the quality factor, Q, which can be defined as a function of Linear Energy Transfer (LET) or the microdosimetric lineal energy (y). In the present work, the average Q of GCR for different mission scenarios was calculated using a modified version of the microdosimetric Theory of Dual Radiation Action (TDRA). NASA’s OLTARIS platform was utilized to generate the radiation environment behind different aluminum shielding (0–30 g/cm2) for a typical mission scenario in low-earth orbit (LEO) and in deep space. The microdosimetric lineal energy spectra of ions (Zge 1) in 1 μm liquid water spheres were calculated by a generalized analytical model which considers energy-loss fluctuations and δ-ray transport inside the irradiated medium. The present TDRA-based Q-values for the LEO and deep space missions were found to differ by up to 10% and 14% from the corresponding ICRP-based Q-values and up to 3% and 6% from NASA’s Q-model. In addition, they were found to be in good agreement with the Q-values measured in the International Space Station (ISS) and by the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD) which represent, respectively, a LEO and deep space orbit.

УДАЛЕНИЕ ЭКОТОКСИКАНТОВ ИЗ ВОДНЫХ РАСТВОРОВ С ПОМОЩЬЮ МЕХАНОАКТИВИРОВАННОГО АНАТАЗА ПОД ДЕЙСТВИЕМ ОСВЕЩЕНИЯ

A significant improvement in the ability to remove ecotoxicants, hexavalent chromium and methylene blue dye, from aqueous solutions under the action of short-wave visible radiation was shown for anatase modification after mechanical activation.

Study of the radioprotective properties of fumaric acid and 3-hydroxypyridine fumarate under the action of ionizing radiation on human cells

In the modern world, such a situation has developed that the development of nuclear energy and the use of sources of ionizing radiation in various fields of activity have created a potential threat of radiation hazard to humans. In this connection, the actual direction is the study of ways to increase the radioresistance of human cells and tissues to the action of ionizing radiation. In addition, radioprotective compounds are also important in radiotherapy, since normal tissues of patients must be protected from radiation damage when using high doses of radiation in the treatment of malignant neoplasms. However, the radioprotectors currently used have some disadvantages. The aim of this work is to study the radioprotective properties of fumaric acid and 3-hydroxypyridine fumarate under the action of gamma radiation and radiation of 12C ions on tumor (SK-N-BE neuroblastoma) and normal (hTERT fibroblasts) human cells. The effect of radiation was evaluated according to the criteria of cell survival in culture, doubling time and clonogenic activity. It has been shown that the use of fumaric acid and 3-hydroxypyridine fumarate has a radioprotective effect on normal and tumor cells when they are irradiated with gamma radiation at doses of 1, 4, 6 and 10 Gy. The use of fumaric acid and 3-hydroxypyridine fumarate does not have a radioprotective effect on tumor cells when they are irradiated with 12C ions. A comparative analysis of the results of the action of the preparations with gamma rays and 12C ions showed a significant dependence of the manifestation of modifying properties on the quality of radiation. The study of cell doubling time showed that the presence of drugs in the control did not increase this indicator. On the contrary, under the action of gamma radiation at a dose of 10 Gy, the preparations reduced the doubling time of fibroblasts by more than two times and the doubling time of neuroblastoma cells by almost 1.5 times. The data obtained indicate that the antioxidant properties of the studied preparations open up new possibilities for modifying the action of ionizing radiation in the treatment of oncological diseases. The use of fumaric acid and 3-hydroxypyridine fumarate will reduce the radiation load on healthy cells, including reducing the effect of secondary products on healthy cells beyond the Bragg peak under the action of carbon ion therapy.

Polymer composition with phenanthrenequinone for recording relief holographic gratings

The formation of periodic reliefs of the thickness of photosensitive polymer layers after recording holographic gratings in them and stimulating material deformations by reversible plasticization in a non-solvent liquid is considered. The phenomenon was studied for the composition of a copolymer with side anthracene groups — phenanthrenquinone. Phenantrenquinone transfers the energy of electronic excitation to oxygen molecules entering through the open surface of the polymer layer which then cause the oxidation of anthracene fragments. Holographic gratings with a period of 2–5 μm were recorded by laser radiation at a wavelength of 532 nm in layers about 1 μm thick. The photoreliefs were formed during the subsequent swelling of the layer in the medium of a hydrocarbon developer. The photosensitized oxidation of the anthracene groups of the new polymer under the action of optical radiation in the spectral range 408–532 nm was studied using the electron absorption spectra. It is shown that approaching the excitation wavelength to the long-wavelength absorption maximum of phenanthrenquinone (410 nm) makes it possible to increase the sensitivity of the material layer by a factor of 15 compared to layers with methylene blue as a photosensitizer. It has been experimentally established that the amplitude of weak periodic reliefs of a deformation nature (height less than 0.01 μm), which appear immediately after the recording of holographic gratings, increases many times during the treatment of the layer with liquid hydrocarbon. Their maximum value reaches 25 % of the thickness of the recording layer. Presumably, the deformation of the inhomogeneously irradiated layer is stimulated by the transfer of the polymer material into a highly elastic state during its swelling. Photoreliefs are stable after drying. Their strength can be increased by photocrosslinking the material as a result of photodimerization of residual anthracene groups under uniform irradiation with light at a wavelength of 365 nm. The non-sinusoidality of the photorelief reduces the diffraction efficiency achievable with total reflection to values less than 0.20. The studied polymer composition can be used to form relief-phase diffractive optical elements by radiation in the blue-green region of the spectrum, provided by a number of high-power laser sources.

A study of indirect action’s impact on simulated neutron-induced DNA damage

Objective. The risk of radiobiological stochastic effects associated with neutrons is strongly energy dependent. Recent Monte Carlo studies simulating neutron-irradiated nuclear DNA have demonstrated that this energy dependence is correlated with the relative biological effectiveness (RBE) of neutrons to inflict DNA damage clusters that contain difficult-to-repair double-strand breaks. However, these previous investigations were either limited to modeling direct radiation action or considered the effects of both direct and indirect action together without distinguishing between the two. In this study, we aimed to quantify the influence of indirect action in neutron irradiation scenarios and acquire novel estimations of the energy-dependent neutron RBE for inducing DNA damage clusters due to both direct and indirect action. Approach. We explored the role of indirect action in neutron-induced DNA damage by integrating a validated indirect action model into our existing simulation pipeline. Using this pipeline, we performed track-structure simulations of monoenergetic neutron irradiations (1 eV to 10 MeV) in a nuclear DNA model and analyzed the resulting simple and clustered DNA lesions. We repeated the irradiation simulations for 250 keV x-rays that acted as our reference radiation. Main results. Including indirect action significantly increased the occurrence of DNA lesions. We found that indirect action tends to amplify the damage due to direct action by inducing DNA lesions in the vicinity of directly-induced lesions, resulting in additional and larger damage clusters. Our neutron RBE results are qualitatively similar to but lower in magnitude than the established radiation protection factors and the results of previous similar investigations, due to the greater relative impact of indirect action in photon-induced damage than in neutron-induced damage. Significance. Although our model for neutron-induced DNA damage has some important limitations, our findings suggest that the energy-dependent risk of neutron-induced stochastic effects may not be completely modeled alone by the relative potential of neutrons to inflict clustered lesions via direct and indirect action in DNA damage.

Thermal Behavior of Biodegradable Compositions of Polylactide and Poly(3-hydroxybutyrate) with Chitosan and the Effect of UV Radiation on Their Structure

The negative influence of water pollution by heavy metals ions on human health represents a serious ecological problem which requires effective methods in the search for its solution. The creation of eco-friendly biodegradable polymer materials capable of performing the sorption of the water media of heavy metals followed by decomposition into harmless substances after the end of their service life presents an actual task. To this aim, binary compositions synthesized from natural raw polyesters polylactide (PLA) and poly(3-hydroxybutyrate) (PHB) with polysaccharide chitosan, corresponding to these requirements, were obtained in the liquid phase. The polyesters have mechanical characteristics close to the characteristics of synthetic polymers, while the chitosan containing the amino groups is capable of performing the sorption of heavy metals. The use of compositions on their base allows one to create the new inexpensive biodegradable sorbents stable in aqueous media as well as apply them as packing materials. The sorption capacity of PLA–chitosan and PHB–chitosan compositions in relation to iron ions from aqueous solutions was explored by a method of X-ray fluorescence analysis and it was established that the sorption of Fe3+ ions by PHB–chitosan composition is more than twice as high as that by the PLA–chitosan composition (2.30 and 0.66 wt. %, correspondingly, after sorption from 0.008 mol/L FeCl3 solution during 24 h). A comparative study of thermophysical parameters and the degree of crystallinity of PLA and PHB, as well as in their initial compositions and compositions, containing sorbed iron ions, was carried out by DSC method. The DSC analysis of the PLA–chitosan and PHB–chitosan compositions, containing sorbed iron ions, showed a slight decrease in the values of Tg, Tcc, and Tm as well as an increase in the enthalpy of cold crystallization and a reduction in the degree of crystallinity of these polyesters. At the same time, an increasing of the thermal stability of polyester compositions in the presence of iron ions was established. The influence of UV irradiation on the structure of PLA and PHB for 2, 5, 24, and 144 h was analyzed by FTIR spectroscopy and significant changes in the spectrum were observed. Based on the analysis of the IR spectra of PHB and PLA, it was concluded that, under the action of UV radiation, the destruction of ester bonds takes place, which is expressed in the appearance of intense bands characterizing the formation of new structural units, resulting in the decrease in the molecular weight of polyesters.

TUDY OF THE INITIAL MAGNETIC PERMEABILITY OF LiTiZnMnFERRITES OBTAINED BY LIQUID-PHASE SINTERING UNDER RADIATION-THERMAL AND THERMAL CONDITIONS

The measuring the temperature dependence of the initial permeability was used to study the features of phase and structural transformations in lithium-titanium ferrites as a function of time, heating and cooling rates, and the temperature of liquid-phase sintering under thermal and radiation-thermal heating. Ferrite was synthesized from powder mixture by solid-phase synthesis. A low-melting additive bismuth dioxide was used to obtain the ferrite ceramics by liquid-phase sintering. RT sintering was carried out by heating the samples with a pulsed (1.5–2.0) MeV electron beam. It was established that the additive leads to a less defective state of sintered ferrites, while the action of radiation enhances this effect in the early stages of sintering. The regularities of the influence of the heating and cooling rates of compacted samples on the change in the initial magnetic permeability of sintered ferrites are established.

The origin of loud claps during endovenous laser treatments.

Optoacoustic and ultrasound methods have shown that the loud "claps" perceived by patients and medical staff during endovenous laser ablation (EVLA) are caused by volumetric blood boiling when large vapor-gas bubbles appear and collapse under the action of laser radiation, which is well absorbed in water. Acoustic effects when using lasers in the near infrared range (1.94, 1.47, and 0.97 μm) were studied in an experiment with non-deaerated water, as well as in EVLA. The nature of these acoustic signals was investigated using high-speed video recording. It turned out that the amplitude of the emerging acoustic pulses in the case of surface boiling, which prevails when using lasers with a wavelength of 0.97 μm, is two orders of magnitude smaller than in the case of volumetric boiling (1.94 and 1.47 μm). The reasons for the decrease in sound effects in this case are associated with numerous microbubbles at the tip of the laser fiber. The results obtained may be useful for further understanding of the mechanisms of EVLA.

Estimating the impact of indirect action in neutron-induced DNA damage clusters and neutron RBE

Background: Neutron radiation protection factors indicate that the risk of neutron-induced stochastic biological effects is higher compared with other types of ionising radiation, and has strong energy dependence. Recent Monte Carlo studies simulated neutron radiation on a nuclear DNA model and demonstrated that the energy-dependent radiobiological risk of neutrons can be correlated with the induction of DNA damage clusters, particularly those that contain difficult-to-repair double-strand breaks. The main limitation of these studies is that only direct radiation action was investigated. Thus, for a more comprehensive understanding of pre-repair neutron-induced DNA damage, indirect action must be modelled and its impact must be quantified. Methods: An open-source algorithm for indirect action available in the TOPAS-nBio track structure Monte Carlo toolkit was adapted into our group’s existing TOPAS and TOPAS-nBio simulation pipeline for neutron and photon radiation. We performed 100 independent simulated irradiations of monoenergetic neutrons from 1 eV to 10 MeV on our existing custom-built nuclear DNA model, and scored various types of DNA damage due to direct and indirect action. The yields of DNA damage were stratified according to the damage-inducing action. For the resulting clusters of DNA damage, we determined the average cluster length and lesion count per cluster. This procedure was also performed for 250-keV x-ray photons that served as our reference radiation. We estimated neutron relative biological effectiveness (RBE) by dividing the neutron-inflicted yield of DNA damage clusters by photon-inflicted counterparts. Finally, we compared our RBE results with established radiation protection factors and previous studies that modelled direct action alone. Results: The inclusion of indirect action increased the yield of DNA damage significantly (the increase varies with damage type). We found that the majority of neutron-induced DNA damage events were isolated simple lesions due to indirect action, while most clustered lesions were hybrid in nature (i.e. contain lesions due to direct and indirect action). As for cluster properties, the inclusion of indirect action increased the average length of clusters by approximately 50% and the number of lesions per cluster by approximately 25%. Our estimated energy-dependent neutron RBE for inducing DNA damage clusters follows similar trends as the established radiation protection factors and the previous direct-action-only estimates, but is lower in magnitude. We found that this lower magnitude is due to the greater impact of indirect action in the yield of photon-induced clustered DNA damage compared with neutron-induced clustered lesions. Conclusion: Indirect action has significant effects on radiation-induced DNA damage clusters in terms of yield, length, and lesion count per cluster, and serves to amplify the effects of direct action. The energy-dependent risk of neutron-induced stochastic effects is likely related to, but not completely explained by, the induction of DNA damage clusters. For a more complete model of neutron RBE, the investigation of factors such as DNA damage repair and non-targeted radiation effects is recommended.

Microwave technology of thermal insulation materials based on liquid glass as an alternative to foam glass

An energy-saving and environmentally friendly microwave technology is proposed for producing composite thermal insulation materials based on liquid glass, which are not inferior to foam glass in terms of their properties. It is shown that the use of microwave radiation allows fabricating volumetrically grouted materials by simultaneous porization of the granules and the binder. In such a way, a monolithic structure of products is formed, where the space between the granules is filled with the swollen binder limited by a denser surface layer. It has been proven that the use of microwave radiation allows achieving heating and softening of the entire mass of the liquid-glass composition due to the internal acceleration of the movement of water molecules, their friction, and release of thermal energy, and not due to high temperature from the outside. This has made it possible to carry out swelling at a lower temperature and during a much shorter heat treatment time than at the traditional convective heating, because the sample layer is heated almost instantly under microwave exposure and the liquid glass composition reaches a pyroplastic state in a few seconds. It has been determined that a part of the energy of electromagnetic radiation is transformed into heat, which contributes to intensive porization with the volumetric expansion of the liquid-glass composition. The other part of the energy is directed to structural changes in the material leading to the improvement of its properties, which is associated with the "non-thermal" microwave radiation action.

Assessment of Thermochromic Packaging Prints’ Resistance to UV Radiation and Various Chemical Agents

Thermochromic inks, also known as color changing inks, are becoming increasingly important for various applications that range from smart packaging, product labels, security printing, and anti-counterfeit inks to applications such as temperature-sensitive plastics and inks printed onto ceramic mugs, promotional items, and toys. These inks are also gaining more attention as part of textile decorations and can also be found in some artistic works obtained with thermochromic paints, due to their ability to change color when exposed to heat. Thermochromic inks, however, are known to be sensitive materials to the influence of UV radiation, heat fluctuations, and various chemical agents. Given the fact that prints can be found in different environmental conditions during their lifetime, in this work, thermochromic prints were exposed to the action of UV radiation and the influence of different chemical agents in order to simulate different environmental parameters. Hence, two thermochromic inks with different activation temperatures (one being cold and the other being body-heat activated), printed on two food packaging label papers that differ in their surface properties were chosen to be tested. Assessment of their resistance to specific chemical agents was performed according to the procedure described in the ISO 2836:2021 standard. Moreover, the prints were exposed to artificial aging to determine their durability when exposed to UV radiation. All tested thermochromic prints showed low resistance to liquid chemical agents as the color difference values were unacceptable in all cases. It was observed that the stability of thermochromic prints to different chemicals decreases with decreasing solvent polarity. Based on the results obtained after UV radiation, its influence in terms of color degradation is visible on both tested paper substrates, but more significant degradation was observed on the ultra-smooth label paper.

RESEARCH OF THE TECHNOLOGICAL MODE OF THE PROCESS OF PORIZATION OF LIQUID GLASS COMPOSITE MATERIALS FOR THERMAL INSULATION IN THE CONDITIONS OF UHF RADIATION

The paper presents the results of research into the technological regime of the process of liquid-glass composition porization under the action of microwave radiation to achieve effective removal of all types of water and obtain heat-insulating materials with high operational properties. It was established that with a radiation power of 500 W in a vacuum environment without rotation of the sample, despite the achieved high temperature value of 110-115 oC, intense swelling was not observed. The decrease in the mass of the sample is due to the mechanism of water removal using a vacuum, which is reduced to a higher mass transfer rate without a vaporization stage. In a vacuum environment, with sample rotation, intense swelling and the formation of a large number of “craters” on the surface of the sample and large through pores in the macrostructure are observed. At atmospheric pressure, there is a sharp drop in temperature at the beginning of the process, which indicates insufficient power of microwave radiation to intensify the swelling process due to significant condensation of moisture on the surface of the sample. With a higher radiation power of 650 W in a vacuum environment, a sharp rise in temperature occurs at the beginning of the process to 90-95 oC, which is due to the beginning of intensive vaporization of free and constitutional water and the creation of a pressure gradient in the sample and its gradual decrease to 55-60 oC, which leads before drying the material. That is, it is impractical to obtain these materials in a vacuum environment, since there are competing processes of water mass transfer and its evaporation. The most optimal conditions for obtaining composite TIMs are the output power of the installation of 650 W and atmospheric pressure. At the very first minute of the process, the temperature rises sharply to 85-90 0C, which slowly increases to 115-120 0C and does not change further. This period is characterized by the most intensive swelling process. The process itself was characterized by ease of adjustment, and the obtained sample has an attractive appearance and a low average density.