Irradiation Regimes Research Articles

Comparative Characteristics of Cerebral Neuronal Patterns after Single and Prolonged Radiation Exposure

The aim of the study was to conduct a comparative assessment of radiation-induced patterns in cerebral neurons after a single and prolonged exposure to radiation.Material and methods. The experiment was carried out in compliance with the rules of bioethics, on 240 white outbred male rats at the age of 4 months, exposed to a single or prolonged exposure to γ-quanta of 60Со in total doses of 0.1; 0.2; 0.5 and 1.0 Gy. Neuromorphological and histochemical methods were used to assess morphometric and tinctorial parameters of nerve cells, the content of protein and nucleic acids, as well as the activity of some dehydrogenases in the early (1st day) and long-term periods (up to 18 months) of the postradiation period. Statistical processing of the results was carried out using Statistica 6.1 software packages, parametric methods were used (Student's t-test, regression and variance analysis), the significance level was 95%.Results. Despite a number of features of neuromorphological indicators dynamics, these irradiation regimes do not cause functionally significant changes in neurons. Among the influencing factors (radiation dose and time elapsed after irradiation), the radiation dose has a greater effect on the structural and functional state of neurons, but the elapsed time levels the resulting changes and most neuromorphological parameters do not have significant differences with the control. The revealed changes, as a rule, have a borderline character, and the level of their significance fluctuates around the indicators of age control within insignificant limits. One can find out a certain instability of the structural and functional organization and tension of the functioning of neurons under the irradiation regimes under consideration. At the same time, in the early periods of observation, more pronounced fluctuations in neuromorphological parameters occur with prolonged radiation exposure, and in later periods – with a single one. In general, no significant differences in the response of neurons to single and prolonged irradiation at the same total dose were found.Conclusion. No significant radiation-induced changes in the state of neurons have been established for all dose-time parameters and modes of exposure. The irradiation dose has a greater effect on neurons, but the time elapsed after irradiation regimens the resulting changes and the majority of neuromorphological parameters have no significant differences from the control. The considered modes of irradiation do not have significant differences among themselves by the response of neurons.

Temperature Rise at the Pulp-Dentin Junction for a Multi-Layered Composite Restoration using the Finite Element Method

Objectives: During the light-curing process of composite restoration, excessive heat can be produced, which can potentially lead to pulp necrosis (death). In this study, we aimed, based on the Finite Element Method (FEM), to assess the risk of pulp damage during the light-curing process by investigating the influence of light-curing devices, under various irradiation regimes, on the temperature increase at the pulp-dentin junction, during a one-layer or multi-layered deep composite restoration. Methods: A Three-dimensional finite element method model of typical geometry and material properties, as commonly reported in the literature, was employed in COMSOL Multiphysics simulations in order to determine the temperature increase in the pulp. Various combinations of light intensities, durations, and irradiation regimes were investigated for the two cases, of shallow and deep multi-layered composite restoration. Results: Results of light-curing composite resins within enamel; indicate that the temperature rise during the curing process was within the safety margins. Results of light-curing composite resin restorations closer to the pulp with thin remaining dentin, indicate a temperature increase that could be sufficient to cause thermal injury in the pulp. Modulating the light output marginally, reduced the temperature rise while reducing the intensity and increasing the curing duration which was consistently more effective in this respect. Conclusion: The results clearly demonstrate that with currently adopted standard procedures, there exists a risk of thermal injury during multi-layered composite restorations with thin remaining dentin; it is thus important to establish appropriate curing regimes that would lead to minimal temperature increase during deep composite restorations and hence reduce the risk of thermal injury to the pulp.

ИЗМЕНЕНИЯ НЕЙРОНОВ КОРЫ ГОЛОВНОГО МОЗГА ПРИ ОДНОКРАТНОМ И ФРАКЦИОНИРОВАННОМ ГАММА-ОБЛУЧЕНИИ

Purpose: Comparative assessment of radiation-induced changes in neurons of the cerebral cortex after a single and fractionated exposure to ionizing radiation in doses of 0.1 – 1.0 Gy.
 Material and methods. The study was carried out in compliance with the rules of bioethics on 180 white outbred male rats at the age of 4 months. by the beginning of the experiment, exposed to a single or fractionated exposure to γ-quanta of 60Co in total doses of 0.1; 0.2; 0.5 and 1.0 Gy. Neuromorphological and histochemical methods were used to assess morphometric and tinctorial parameters of nerve cells, as well as changes in the content of protein and nucleic acids in neurons in the early and late periods of the post-radiation period. Using one-way analysis of variance, a comparative assessment of neuromorphological indicators under various modes of radiation exposure is given.
 Results: In the control and irradiated animals throughout their life, undulating changes in the indicators of the state of the neurons of the brain occur with a gradual decrease by the end of the experiment. Despite a number of features of the dynamics of neuromorphological parameters, these irradiation regimes do not cause functionally significant changes in the neurons of the cortex. However, in some periods of the post-radiation period, the changes under the studied irradiation regimes were multidirectional and did not always correspond to age control. Significant differences in the response of neurons to these modes of radiation exposure in the sensory and motor areas of the cerebral cortex have not been established.
 Conclusion: No functionally significant radiation-induced changes in neurons were found either with single or fractionated irradiation. At the same time, different modes of irradiation in general caused the same type of changes in neurons. However, in some periods of observation, changes in neuromorphological parameters under the studied irradiation regimes were not unidirectional and differed from age control, which indicates a possible risk of disturbances in the functioning of the nervous system against the background of other harmful and dangerous factors.

Deposition of silver on the surface of microparticles of zirconium and molybdenum oxides during their synthesis by laser ablation in liquid

The deposition of silver on the surfaces of micro- and nanoparticles of zirconium, molybdenum, and their oxides, obtained by laser ablation of pure metals in aqueous solutions of silver nitrate, is investigated experimentally. Different irradiation regimes and reagent concentrations are approved. The experimental results indicate a possibility of continuous or partial coating (decorating) with silver the surfaces of nanostructures of oxides of the aforementioned metals; using such systems as substrates, one can increase the Raman scattering amplitude. Silver-coated zirconium and molybdenum oxides can be applied in the diagnostic techniques based on the phenomenon of surface-enhanced Raman scattering.

Woody plants seedlings irradiation lighting parameters by using LED transmitters in small-sized irradiation installations

The use of planting material with a root-balled tree system is one of the promising directions for creating artificial plantations. It is associated with radical changes in the cultivation of planting material and significant changes in the forest crops production technology [1]. The technology of widespread, woody plants year-round cultivation in the artificial environment can be implemented by using small-sized forms of cultivation structures - irradiation chambers and cabinet units, grow boxes, phytotrons, etc. In this case, the main technological operation is the light regime necessary for plants: with the radiation spectrum necessary for their development and growth, with the required intensity and irradiation regime. The results of photobiological studies on the qualitative indicators of woody plants grown in phytotron conditions under irradiation by radiation with different proportions in the blue-red and blue-green-red ranges of the photosynthetically active radiation zones are presented. The photosynthetically active radiation spectral variants, providing the highest or extremely close to it productivity of the indicated crops, were established. The complex and ambiguous nature of the photosynthetically active radiation main spectral ranges influence on the photoenergy and photoregulatory processes in plants, which ensure their productivity, is indicated, which makes it impossible to determine the general unified requirements for the artificial irradiation optimal parameters for growing plants.

Local Polarization Reversal by Ion Beam Irradiation in SBN Single Crystals Covered by Dielectric Layer.

Formation of the domain structure by ion beam irradiation was studied in thermally depolarized Ce-doped strontium barium niobate single crystals covered by a dielectric layer. Three types of irradiation regimes were used: dot exposure, stripe exposure, and line exposure. The dependences of the domain size and depth on the irradiated dose were measured. The circular shape of the isolated domains with partially switched broad domain boundary was obtained. Isotropic domain growth was attributed to the step generation at the wall by merging with the residual nanodomains that appeared after thermal depolarization. The obtained linear dose dependence of the switched area was attributed to the screening of the depolarization field by the injected charge. The shape distortion of the domains growing in the neighborhood with already created ones was attributed to the electrostatic interaction of the approaching charged domain walls. The obtained results can be applied for the creation of precise domain patterns with arbitrary orientation and shape to produce nonlinear optical devices with improved characteristics, including electrically tunable diffractive optical elements.

Influence of Ionizing Radiation on the Corrosion Resistance of ZnNi/SiO2 Composite Coatings

The influence of x-ray radiation on the protective properties of ZnNi/SiO2 composite coatings has been investigated experimentally, and the optimal regimes of their electrodeposition on irradiation by the method of complete factor experiment have been revealed. It is shown that the action of x-ray radiation on the electrolytes used for electrodeposition of ZnNi/SiO2 leads to an increase in their dispersive power, which makes it possible to form composite coatings with the metal uniformly distributed over the surface and, correspondingly, with elevated corrosion resistance. It has been found that the action of x-ray radiation on the process of electric deposition of ZnNi/SiO2 coatings promotes formation of layers with enhanced anticorrosion properties. Based on experimental data and according to the method of complete factor experiment, the influence of variations in the x-ray radiation exposure dose power and concentration of SiO2 nanoparticles in the electrolyte on the dispersive power of electrolytes and corrosion resistance of ZnNi/SiO2 coatings has been considered. Regression equations have been obtained, an analysis of the coefficients of which allowed the conclusion that a maximum increase in the dispersive power and a decrease in the rate of appearance of corrosion products on ZnNi/SiO2 coatings are achieved on combination of two factors: addition of SiO2 nanoparticles to the electrolyte and irradiation of the electrolyte by x-ray radiation in the process of coating deposition. The developed statistical model allows one to adequately determine the optimal concentrations of SiO2 nanoparticles in an electrolyte and the regime of x-ray irradiation for obtaining coatings with enhanced anticorrosive properties.

Comparative investigation of 5-aminolevulinic acid and hexyl aminolevulinate-mediated photodynamic diagnostics and therapy of cervical dysplasia and vulvar leukoplakia

This study aims to conduct a comparative analysis of aminolevulinic acid and its hexyl aminolevulinate (HAL) for photodynamic diagnostics and therapy of cervical dysplasia and vulvar leukoplakia in continuous and pulsed laser irradiation mode. The fluorescence intensity of protoporphyrin IX (PpIX) in the cervix epithelium was five times higher after the application of HAL compared with the application of aminolevulinic acid. Increased intensity of fluorescence of PpIX in vulvar tissues complicated by leukoplakia was not observed with 5-aminolevulinic acid and its HAL. Intraepithelial changes in patients with cervical dysplasia were absent after photodynamic therapy (PDT) in continuous irradiation mode. Repeated PDT was prescribed to several patients with vulvar leukoplakia after pulsed light irradiation. Pulse irradiation made it possible to avoid the use of various types of anesthesia in patients. In the regime of continuous irradiation, pain sensations of varying degrees from a burning sensation to sharp pains were observed in patients in the zone of photodynamic exposure. The results presented in this paper will help to optimize the PDT process of cervical dysplasia and leukoplakia using 5-aminolevulinic acid or HAL.

Effects of Low-level Laser Therapy on Fibroblast Density in Achilles Tendon Rupture Healing

Objective: To investigate the effect of low-level laser therapy (LLLT) on fibroblast proliferation as a part of the tendon healing cascade. Methods: This was an unpaired comparative experimental animal laboratory study with one control groups and two experimental groups, each consisted of 10 Sprague Dawley rats. The experimental groups 1 and 2 were given infrared irradiation for 15 minutes and 30 minutes per day, respectively, after having their achilles tendon partially cut. Histological assessment was carried out to assess the fibroblast density in healing site after three weeks on intervention. Results: The median values of fibroblast density in group 1, group 2, and control group were 1, 2, and 1, respectively, with a p-value of 0.014. No significant difference (p = 0.123) was identified on Mann-Whitney test between the fibroblast density of group 1 and group 2. The same was also true forgroup 1 and control group (p = 0.315). A significant difference was found between group 2 and control group (p = 0.005). Conclusions: A regime of LLLT irradiation of 30 min/day for two weeks (1080 J cm-2) improves the fibroblast proliferation amidst tendon healing in a partially injured achilles tendon in a rat model, which is not seen in the regime with a 15 min/day duration. This emphasizes the significance of irradiation time to improve tendon healing, despite the deficient understanding of the mechanism.

Special Aspects of High-Intensity Low-Energy Ion Implantation

Numerical simulations and experimental studies of surface and subsurface layers of different materials are performed in order to determine their real temperatures as a function of the regimes of high-intensity ion irradiation. The integral temperature of the target is measured using an electrically insulated thermocouple. A KLEIBER 740-LO high-temperature pulsed pyrometer is used to measure the dynamic variation of the local temperature. A contribution from the shock-wave mechanism into the mass transfer of the implanted impurity is studied during hot high-intensity ion implantation.

Численное исследование динамики нагрева золота ультракороткими дихроматическими импульсами лазерного излучения

The interaction of femtosecond laser pulses of moderate intensity with metals by the example of gold is studied. The main attention is paid to dichromatic regimes of laser irradiation corresponding to a new trend in the field of laser pro-cessing of materials. Based on the two-temperature approximation, a new model is created which involves a dichro-matic source of the laser radiation energy and also takes into account the influence of the electron temperature on the reflection coefficient of the irradiated material and thermophysical properties of its electronic subsystem. For numerical implementation of the model, an implicit divergent finite-difference scheme is created with an improved method for describing the melting process in comparison with previous works. The model calculations have shown that the absorption of the laser energy by gold depends on the sequence of two pulses at different wavelengths and the delay time between them, and for correct description of the absorbed energy, it is necessary to take into account the change of the reflection coefficient of the surface during irradiation. The developed model may be of interest for optimizing the processing of materials with ultra-short dichromatic laser pulses.

Влияние облучения низкоэнергетическими ионами гелия на спектральный коэффициент отражения монокристаллических молибденовых зеркал

The results of a comparative study of the effect of irradiation with helium ions on the optical properties of single-crystal molybdenum mirrors with crystallographic orientations <110> and <111> are presented. The irradiation regime corresponds to the conditions in plasma cleaning systems of the entrance mirrors from contamination in optical diagnostics of ITER while helium is using as a working gas. As a result of such irradiation, a change in specular reflection and diffuse scattering of the mirror occurs, which is practically independent of the initial structure of the surface layer of the mirror and the duration of the irradiation process. Authors explain the observed changes in the optical characteristics of the mirror by the formation of nanosized bubbles in the surface skin layer. Rayleigh scattering of incident radiation on these bubles decreases the intensity of specular reflection and increases diffuse scattering. A model of the formation and growth of nanosized bubbles and their effect on optical properties is proposed. The obtained results should be taken into account when analyzing experimental data in optical diagnostics of ITER after removing contaminants using helium, when choosing a working gas for mirror cleaning, and also for the formation of a nanoporous structure in a thin surface layer of metals.

Mouse Genomic Associations With <i>ex vivo</i> Sensitivity to Simulated Space Radiation

Exposure to ionizing radiation is marked by NASA as a major health hazard for deep space exploration missions. Ionizing radiation sensitivity is determined by both genomic and environmental factors. Understanding their contributions is crucial for designing experiments in model organisms, selecting therapeutic irradiation regimes for cancer patients and evaluating the risk of deep space radiation exposure in astronauts. We identified single nucleotide polymorphisms in 15 strains of mice associated with spontaneous and ionizing radiation-induced ex vivo DNA damage. We mapped them to pathways related to carcinogenesis, nervous system damage and immune activation, including some located within the protein coding regions of genes that were predicted to interfere with protein functions. We anticipate that the identification of genes and pathways associated with DNA damage in response to ionizing radiation will improve the selection of mouse models for ionizing radiation research, inform functional validation studies and identify targets for space travel countermeasures.

INVESTIGATION OF THE INFLUENCE OF UHF ELECTROMAGNETIC FIELD ON THE OUTPUT OF ROLLED GROATS OF WHEAT SPELT

Wheat spelt is a promising crop. A high food value and high-quality biochemical composition of grains make wheat spelt favorably remarkable for groats production. Preservation of the food value is an important task of food production, but regimes of grain processing must provide good culinary quality and consumption safety. The aim of our work is to study regimes of irradiation and humidification of wheat spelt grains, influencing the output and culinary quality of the ready product; development of recommendations as to production of rolled groats. There is studied an influence of different regimes of water-thermal processing on the total output of groats and rolled groats of the highest sort. The reliable connection between the output of rolled groats of the higher sort and duration of irradiation by the electromagnetic field of the ultrahigh frequency and grain humidification has been established. No essential connection as been established between humidification and the total output of groats. The duration increase of UHF-irradiation (>120–140 s) conditions the essential growth of dust middlings and decrease of rolled groats of the highest sort. The long-term irradiation (180 s) conditions the decrease of groats boiling duration by 17 % comparing with the short-term processing (20 s). The established influences of the factors are preconditions for transferring obtained technological solutions and their use under conditions of existing groats factories of different productivity

Influence of a pulsed (flashing) light-emitting diode (LED) phyto-irradiator on the efficiency of rooting of garden strawberry micro-cuttings in vitro

All greenhouse phyto-irradiators implement a constant regime of plant irradiation. For example, phyto-irradiators turn on at 6 am and turn off at 10 pm. The article contains the results of a study of the influence of pulsed (flashing) light on the growth and development of meristemic plants of garden strawberry varieties ‘Brighton’ and ‘Korona’ in vitro. The ability to use flashing light is based on the features of photosynthesis, which includes light-dependent and light-independent (dark) reactions. A flashing LED phyto-irradiator and a continuously operating fluorescent irradiator (control sample) were compared. Experiments have shown that the use of flashing LED phyto-irradiator increased the rooting rate of strawberry micro-cuttings by 5-10%, depending on the varieties. For the variety ‘Korona’ there was an increase in the number of fully developed leaves to 7.2 pieces (6.0 pieces in the control sample) and, as a consequence, an increase in the leaf surface area of microplants from 262.2 mm2 to 348.0 mm2. For the ‘Brighton’ variety, everything was the other way around: under the flashing LED phyto-irradiator, the number of fully developed leaves decreased to 4.5 pieces (5.6 pieces in the control sample). The use of a flashing LED phyto-irradiator prevented the elongation of microplants in both varieties. At the end of the experiment, all strawberry microplants were rooted and met the standard requirements for rosette height, number of fully developed leaves, and root length.

Red/NIR Thermally Activated Delayed Fluorescence from Aza-BODIPYs.

The search for long-lived red and NIR fluorescent dyes is challenging and hitherto scarcely reported. Herein, the viability of aza-BODIPY skeleton as a promising system for achieving thermal activated delayed fluorescent (TADF) probes emitting in this target region is demonstrated for the first time. The synthetic versatility of this scaffold allows the design of energy and charge transfer cassettes modulating the stereoelectronic properties of the energy donors, the spacer moieties and the linkage positions. Delayed emission from these architectures is recorded in the red spectral region (695-735 nm) with lifetimes longer than 100 μs in aerated solutions at room temperature. The computational-aided photophysical study under mild and hard irradiation regimes disclose the interplay between molecular structure and photonic performance to develop long-lived fluorescence red emitters through thermally activated reverse intersystem crossing. The efficient and long-lasting NIR emission of the newly synthesized aza-BODIPY systems provides a basis to develop advanced optical materials with exciting and appealing photonic response.

Laser Power Converter Modules with a Wavelength of 809–850 nm

We consider a high-efficiency photovoltaic module optimized for conversion of monochromatic radiation with a wavelength of 809–850 nm. The module includes four photovoltaic converters with a total area of 16 cm2, which operate with laser radiation of a power higher than 1 W and ensure a working voltage higher than 4 V. In the development and obtaining AlGaAs/GaAs structures for receiver-converters of radiation, we have used the method of epitaxy from the liquid phase and the method of metalorganic vapour-phase epitaxy. When the photovoltaic module operates in the regime of uniform irradiation of the light-detecting surface, the efficiency of conversion of a high-power (6.2 W) laser radiation exceeds 60%.

The LED phyto lighting for improving the environmental friendliness of growing and productivity of lettuce varieties with red and green leaves

The intensively developing area of modern phytophysiology is the ecological plants physiology, which important section is the ecology of photosynthesis, by which we understand the intensity and photosynthesis productivity dependence on environmental factors, primarily on optical radiation. The urgent problem of growing plants under artificial conditions is to increase energy efficiency, reduce energy intensity and degree of environmental impact. Using LED irradiators with the function of controlling the spectral composition and optical radiation power, it is possible to increase photosynthesis efficiency and vegetable crop productivity in greenhouses. The comparative study of the effect of sodium lamp radiation and LED irradiators with different spectral composition on the growth and productivity lettuce varieties with red leaves (Anthony, Lolo-Rossa) and with green leaves (Levistro, Lifli), was conducted. The research results showed the different susceptibility of lettuce varieties to the spectral composition of radiation. For the Anthony, Levistro and Lolo-Rossa lettuce varieties, LED radiation application provided the positive effect on plant productivity (8-20%) compared to sodium lamps, and simultaneous reduced in energy consumption of the irradiation system by 40 - 50%. Diodes emission increase in the blue region of the spectrum had a significant positive effect on the synthesis of anthocyanins in the culture of lettuce varieties with red-leaves, compared to sodium lamps. For these varieties, a variable irradiation regime is necessary with a change in the spectrum and increase in the proportion of blue radiation towards the end of growth.

Evaluation of ex vivo melanogenic response to UVB, UVA, and visible light in facial melasma and unaffected adjacent skin

BackgroundThe independent role of solar radiation in the differential melanogenesis between melasma and adjacent skin is unknown. ObjectivesTo assess the melanogenic responses of skin with facial melasma and of the adjacent skin to UVB, UVA, and visible light, in an ex vivo model. MethodsThis was a quasi-experimental study involving 22 patients with melasma. Facial melasma and adjacent skin samples were collected and stored in DMEM medium, at room temperature. One fragment was placed under the protection from light, while another was exposed to UVB, UVA, and visible light (blue-violet component): 166 mJ/cm2, 1.524 J/cm2, and 40 J/cm2, respectively. Subsequently, all samples were kept for 72 hours in a dark environment and stained by Fontana-Masson to assess basal layer pigmentation, dendrites, and melanin granulation. ResultsEffective melanogenesis was observed in the basal layer in melasma and in the normal adjacent skin after all irradiations (p < 0.01), with the following median increment: UVB (4.7% vs. 8.5%), UVA (9.5% vs. 9.9%), and visible light (6.8% vs. 11.7%), with no significant difference between anatomical sites. An increase in melanin granulation (coarser melanosomes) was observed only after irradiation with UVA and only in the skin with melasma (p = 0.05). An increase in the melanocyte dendrite count induced by UVB radiation was observed in both anatomical sites (p ≤ 0.05). Study limitationsUse of an ex vivo model, with independent irradiation regimes for UVB, UVA, and visible light. ConclusionsMelanogenesis induced by UVB, UVA, and visible light was observed both in melasma and in the adjacent skin. The morphological patterns suggest that different irradiations promote individualized responses on the skin with melasma.

Characterization of novel polydiacetylene gel dosimeter for radiotherapy

Polymer gel dosimeters are instrumental for clinical and research applications in radiotherapy. These dosimeters possess the unique ability to record dose distribution in three dimensions. A Polymer gel dosimeter is composed of organic molecules in a gel matrix, which upon irradiation polymerize to form a conjugated polymer with optical absorbance proportional to the irradiated dose. Other required characteristics of a radiotherapy clinical dosimeter are soft-tissue equivalency, linear dose-response in a range of clinical treatments, and long term stability for the duration of the analysis. The dosimeter presented in this paper is based on diacetylene bearing fatty acid aggregates embedded in a soft-tissue equivalent gel matrix, Phytagel™, which upon irradiation polymerize to form a blue phase polydiacetylene with a strong optical absorption. Initial characterization showed that PDA-gel irradiated with 160 kV x-ray responded linearly to the irradiated dose, and the calculated diffusion coefficient is what is very low. It was also found that the percentage depth dose (PDD) curve of the PDA-gel in a 4 × 4 cm2 field, irradiated with 6 MV x-rays, was with good agreement with the literature. PDA-gel has the potential to detect absorbed dose in a range of clinical radiological irradiation regimes.