Effect Of Photon Irradiation Research Articles

Effects of photon irradiation in the presence and absence of hindlimb unloading on the behavioral performance and metabolic pathways in the plasma of Fischer rats.

Introduction: The space environment astronauts experience during space missions consists of multiple environmental challenges, including microgravity. In this study, we assessed the behavioral and cognitive performances of male Fisher rats 2months after sham irradiation or total body irradiation with photons in the absence or presence of simulated microgravity. We analyzed the plasma collected 9months after sham irradiation or total body irradiation for distinct alterations in metabolic pathways and to determine whether changes to metabolic measures were associated with specific behavioral and cognitive measures. Methods: A total of 344 male Fischer rats were irradiated with photons (6MeV; 3, 8, or 10Gy) in the absence or presence of simulated weightlessness achieved using hindlimb unloading (HU). To identify potential plasma biomarkers of photon radiation exposure or the HU condition for behavioral or cognitive performance, we performed regression analyses. Results: The behavioral effects of HU on activity levels in an open field, measures of anxiety in an elevated plus maze, and anhedonia in the M&M consumption test were more pronounced than those of photon irradiation. Phenylalanine, tyrosine, and tryptophan metabolism, and phenylalanine metabolism and biosynthesis showed very strong pathway changes, following photon irradiation and HU in animals irradiated with 3Gy. Here, 29 out of 101 plasma metabolites were associated with 1 out of 13 behavioral measures. In the absence of HU, 22 metabolites were related to behavioral and cognitive measures. In HU animals that were sham-irradiated or irradiated with 8Gy, one metabolite was related to behavioral and cognitive measures. In HU animals irradiated with 3Gy, six metabolites were related to behavioral and cognitive measures. Discussion: These data suggest that it will be possible to develop stable plasma biomarkers of behavioral and cognitive performance, following environmental challenges like HU and radiation exposure.

Навчальні експерименти з використанням живих організмів: біоетичні обґрунтування корекції методик

The relevance of the topic of the article is due to two trends in the world and in Ukraine: the spread of research practices that need to be understood in the discourse of bioethics, and attempts to introduce bioethics (or its basic ideas and principles) in the educational process of technical universities. These two trends are combined in the practice of using animals in scientific experiments. Taking into account the fact that a component of such research in not only scientific, but also educational experiments, this topic becomes an urgent problem in the discourse of the philosophy of education. The purpose of the article is to present and analyze the experience of correcting the methods of educational and demonstration experiments using living organisms, which are carried out at the Odessa Polytechnic State University. As examples, the course of laboratory work on the study of the influence of wastewater from foundry dumps on living organisms (specialty 136-Metallurgy) and an experiment to study the effect of photon irradiation on biological objects in the aquatic environment (specialty 163-Biomedical engineering) are described. Guppy fish (Poecilia reticulata Peters) are used in both experiments. The results of the analysis of the correction of the methods of these experiments form the scientific novelty in three aspects: 1) the substantiation of the need for the formation of bioethical competencies is given not only for physicians and veterinarians, but also for engineers of various specialties; 2) an additional principle of bioethics of experiments on animals is proposed and tested - the principle of early stopping of an experiment (educational and demonstration) at a certain stage; 3) it is shown that giving students the opportunity to make decisions about changing the experiment procedure allows them to better understand the boundaries of what is necessary and sufficient, forms their willingness to take responsibility for the result of the experiment and for the lives of people and animals.

Superior Photo-thermionic electron Emission from Illuminated Phosphorene Surface

This work demonstrates that black phosphorene, a two dimensional allotrope of phosphorus, has the potential to be an efficient photo-thermionic emitter. To investigate and understand the novel aspects we use a combined approach in which ab initio quantum simulation tools are utilized along with semiclassical description for the emission process. First by using density functional theory based formalism, we study the band structure of phosphorene. From the locations of electronic bands, and band edges, we estimate the Fermi level and work function. This leads us to define a valid material specific parameter space and establish a formalism for estimating thermionic electron emission current from phosphorene. Finally we demonstrate how the emission current can be enhanced substantially under the effect of photon irradiation. We observe that photoemission flux to strongly dominate over its coexisting counterpart thermionic emission flux. Anisotropy in phosphorene structure plays important role in enhancing the flux. The approach which is valid over a much wider range of parameters is successfully tested against recently performed experiments in a different context. The results open up a new possibility for application of phosphorene based thermionic and photo-thermionic energy converters.

Quantitative assessment of radiation dose and fractionation effects on normal tissue by utilizing a novel lung fibrosis index model

BackgroundNormal lung tissue tolerance constitutes a limiting factor in delivering the required dose of radiotherapy to cure thoracic and chest wall malignancies. Radiation-induced lung fibrosis (RILF) is considered a critical determinant for late normal tissue complications. While RILF mouse models are frequently approached e.g., as a single high dose thoracic irradiation to investigate lung fibrosis and candidate modulators, a systematic radiobiological characterization of RILF mouse model is urgently needed to compare relative biological effectiveness (RBE) of particle irradiation with protons, helium-, carbon and oxygen ions now available at HIT. We aimed to study the dose-response relationship and fractionation effect of photon irradiation in development of pulmonary fibrosis in C57BL/6 mouse.MethodsLung fibrosis was evaluated 24 weeks after single and fractionated whole thoracic irradiation by quantitative assessment of lung alterations using CT. The fibrosis index (FI) was determined based on 3D-segmentation of the lungs considering the two key fibrosis parameters affected by ionizing radiation i.e., a dose/fractionation dependent reduction of the total lung volume and increase of the mean lung density.ResultsThe effective dose required to induce 50% of the maximal possible fibrosis (ED50) was 14.55 ± 0.34Gy and 27.7 ± 1.22Gy, for single and five- fractions irradiation, respectively. Applying a deterministic model an α/β = 4.49 ± 0.38 Gy for the late lung radiosensitivity was determined. Intriguingly, we found that a linear-quadratic model could be applied to in-vivo log transformed fibrosis (FI) vs. irradiation doses. The LQ model revealed an α/β for lung radiosensitivity of 4.4879 Gy for single fraction and 3.9474 for 5-fractions. Our FI based data were in good agreement with a meta-analysis of previous lung radiosensitivity data derived from different clinical endpoints and various mouse strains. The effect of fractionation on RILF development was further estimated by the biologically effective dose (BED) model with threshold BED (BEDTr) = 30.33 Gy and BEDED50 = 61.63 Gy, respectively.ConclusionThe systematic radiobiological characterization of RILF in the C57BL/6 mouse reported in this study marks an important step towards precise estimation of dose-response for development of lung fibrosis. These radiobiological parameters combined with a large repertoire of genetically engineered C57BL/6 mouse models, build a solid foundation for further biologically individualized risk assessment of RILF and functional RBE prediction on novel of particle qualities.

Effects of incident UV light on the surface morphology of MBE grown GaAs

Light-assisted molecular beam epitaxy is a promising technique for improving the growth of metastable semiconductor alloys traditionally grown at low temperatures. The effect of photon irradiation on adatom incorporation dynamics is studied for GaAs homoepitaxy on vicinal surfaces. Irradiation is found to increase the temperature at which the growth mode transitions from layer-by-layer island nucleation to step flow growth and to alter the surface morphology. These surprising changes are discussed in the context of modification of adatom diffusion and incorporation processes.

Effect of photon irradiation on the adsorption of CO2 on polycrystalline Cu

The adsorption and photochemistry of CO 2 on ordered/disordered Cu surfaces were investigated using X-ray photoelectron and high resolution electron loss technique. Physisorbed CO 2 and chemisorbed CO 2 δ− species were isolated on different faces. Studies on the photochemical behavior of physisorbed and chemisorbed species were conducted with 193 nm laser irradiation. No photoinduced reaction occurred with the physisorbed species. Photoinduced dissociation was seen with chemisorbed species. 使用X光电子能谱(XPS)及高分辨电子能量损失谱(HREELS)研究了二氧化碳在铜表面的吸附及其光化学反应. 通过实验条件控制将物理吸附及化学吸附的二氧化碳吸附物种分别分离在规整铜表面及无序铜表面上, 并使用193 nm激光对其照射研究其相应的光化学反应. 结果表明只有化学吸附的二氧化碳物种在光诱导下发生了解理反应, 而物理吸附的二氧化碳未发生反应. The physisorbed CO 2 species and chemisorbed CO 2 d ? species are routinely isolated on the ordered and disordered Cu surfaces. It was found that the photo-induced dissociation occurs only on the chemisorbed species by the 193 nm laser irradiation; while there is no photo-induced dissociation occurred on the physisorbed species.

Brown Spot of Rice is Affected by Photon Irradiance and Temperature

Brown spot, caused by Bipolaris oryzae, is one of the most destructive diseases in rice. In this study, the effect of photon irradiance and temperature on brown spot development was evaluated. The concentration of total soluble sugars (fructose, glucose and sucrose) in rice leaves was also evaluated. Rice plants of cv. ‘Oochikara’ were inoculated with B. oryzae and kept in a greenhouse [20 ± 2°C (night time) and 35 ± 2°C (day time), ≈ 1000 μmol photons/m2/s] or two different mist chambers (25 or 32 ± 2°C, ≈ 15 μmol photons/m2/s at the top canopy). Plants kept in a mist chamber at 32 ± 2°C, under low photon irradiance, showed reduced incubation period (IP) and increase in the rate of lesion expansion. Brown spot severity in rice leaves was 67.8% at 32 ± 2°C, 27.8% at 25 ± 2°C and 11.4% under greenhouse conditions. The highest brown spot severity was found on plants grown under low photon irradiance, in which soluble sugar concentrations were lowest, suggesting that disease development was boosted under these particular growing conditions. Based on the results of this study, a continuous high temperature and low photon irradiance, in the presence of high relative humidity, and low soluble sugars contribute to an increase in brown spot development.

Effect of photon irradiation on structural, dielectric, and insulating properties of Ba0.60Sr0.40TiO3 thin films

The effect of ultraviolet (UV) photon assisted annealing on the structural, dielectric, and insulating properties of barium strontium titanate (BST) thin films was investigated. Isothermal-temporal annealing experiments revealed that the films annealed utilizing UV assist possessed enhanced crystallization and lattice parameters closer to bulk values with respect to conventional thermal annealed films. The leakage current density and dielectric loss of the films was significantly reduced by employing UV-assisted annealing without degradation of film tunability. Mitigation of oxygen vacancies, associated with the UV-assisted annealing, is deemed responsible for the improvement of the dielectric and electrical properties of the BST thin films.

Effects of Photon Irradiation during Plasma Etching Processes for Low-k films

not Available.

Effect of photon irradiation on structure of yttria-doped zirconia thin films grown on semiconductor substrates

Structural changes and atomic-scale interfacial phenomena induced by room temperature ultraviolet (UV) irradiation on yttria-doped zirconia (YDZ) thin films grown on semiconductor substrates have been investigated in detail. Interfacial layer formation, film densification, and changes in crystallinity were observed in films grown on Si, while there was minimal difference in films grown on Ge. No significant grain growth and phase transformation were observed, suggesting that cation related kinetics remains unperturbed under UV exposure. The formation of interfacial layers thicker than room temperature self-limiting thickness suggests that effective local field for oxygen vacancies inside the YDZ film was affected by photon illumination.

Effect of photon irradiation on conductivity of nanoscale yttria-doped zirconia thin films

The effect of photon irradiation on high temperature conductivity of nanoscale yttria-doped zirconia thin films is reported. Nanoscale films show substantial decrease in total conductivity (as high as ∼40%) during ultraviolet (UV) irradiation, while the conductivity of bulk single crystals shows negligible changes. The UV induced conductivity changes are rapid and reversible and activation energies for ion migration remain unaffected. The reduction in conductivity may arise from changes in effective oxygen vacancy concentration. Such UV-influenced alteration of electrical properties offers an elegant route to tailor surface catalytic activity of oxygen ion and mixed conductors used in various solid-state devices.

Effect of photon irradiation on the process of recrystallization of thin metallic films

Recrystallization of thin polycrystalline films of Au, Pt, and Pd obtained by thermal evaporation and condensation in a vacuum on silicon plates that are not warmed up and are coated on both sides with silicon oxide has been studied by transmission electron microscopy. It has been established that the rate of normal grain growth in such films is higher upon photon treatment by the radiation of power xenon lamps (spectral region of 0.2–1.2 μm) than upon heat treatment. A quantitative estimate of the effect revealed indicates a change in the mechanism of the process that controls migration of grain boundaries. The effect is connected with the possible activation of hypersonic waves owing to the coexistence of phonon and electron excitations localized in nanosized regions of metallic films.

The Microcystin Composition of the Cyanobacterium Planktothrix agardhii Changes toward a More Toxic Variant with Increasing Light Intensity

The cyanobacterium Planktothrix agardhii, which is dominant in many shallow eutrophic lakes, can produce hepatotoxic microcystins. Currently, more than 70 different microcystin variants have been described, which differ in toxicity. In this study, the effect of photon irradiance on the production of different microcystin variants by P. agardhii was investigated using light-limited turbidostats. Both the amount of the mRNA transcript of the mcyA gene and the total microcystin production rate increased with photon irradiance up to 60 micromol m(-2) s(-1), but they started to decrease with irradiance greater than 100 micromol m(-2) s(-1). The cellular content of total microcystin remained constant, independent of the irradiance. However, of the two main microcystin variants detected in P. agardhii, the microcystin-DeRR content decreased twofold with increased photon irradiance, whereas the microcystin-DeLR content increased threefold. Since microcystin-DeLR is considerably more toxic than microcystin-DeRR, this implies that P. agardhii becomes more toxic at high light intensities.

Significant enhancement of ion-induced secondary electron current by photons in plasma immersion ion implantation

This paper describes effects of vacuum ultraviolet (VUV) optical emission on the secondary electron emission coefficient (SEEC) in plasma immersion ion implantation (PIII) processes. To examine this, time-resolved in situ SEEC measurements were carried out for square wave-modulated Ar discharges. The SEEC in the activeglow was enhanced in proportion to the SEEC in the afterglow regardless of the ion-bombarding energy. The SEEC enhancement in the activeglow was caused by photon effects, and was explained by synergistic effects of photon irradiation and ion bombardment. Oxygen addition to the Ar discharge also caused a significant increase in the SEEC, and enhanced both ion-induced SEEC and photon enhancement factor.

Photomovement of the swarmers of the brown algae Scytosiphon lomentaria and Petalonia fascia: effect of photon irradiance, spectral composition and UV dose

Photomovement measurements were carried out with swarmers of the brown algae Scytosiphon lomentaria (Lyngb.) Link and Petalonia fascia (O. F. Müll.) as a function of irradiance direction, photon irradiance, spectral composition and ultraviolet radiation (UVR, λ=280–400 nm) dose. Swarmers from both species showed similar photomovement patterns: negative phototaxis occurred under photon irradiances of 10–90 μmol photons m −2 s −1, and no movement was observed at 190 μmol photons m −2 s −1. The translocational velocity measured between 10 and 90 μmol m −2 s −1 ranged from 100 to 200 μm s −1. The accumulation of swarmers presented a peak at 450 nm (waveband of 50 nm), and smaller peaks at 400 and 500 nm; no effect was observed at wavelengths of 550 nm and above. The decline in phototactic index (an estimator of photomovement response) of swarmers was linearly correlated with the logarithm of UVR doses. These data were correlated with levels of natural solar radiation in the field. It is hypothesized that motility of swarmers could be a critical factor in the survival of these species under a scenario of increased UVR.

Effect of photon irradiance and photoperiod on young sporophytes of four species of the Laminariales

Four kelp species (Alaria esculenta, Laminaria digitata, L. hyperborea and L. saccharina) were cultured in the laboratory and pretreated so that gametophytes became mature and sporophytes were produced. Young sporophytes less than 3 weeks old were exposed to various light conditions and their survival or relative growth rate in length (R L), and width (R W) in one experiment, determined. Sporophytes of L. digitata survived poorly in the dark compared with L. hyperborea. The minimum photon irradiance allowing growth in L. hyperborea was about 1 μmol m-2 s-1; 1–2 μmol m-2 s-2 sustained growth in all the species. The growth of all four species was saturated at 20–30 μmol m-2 s-1 of continuous photon irradiance. In shorter daylengths the growth rate was lower both below and above light saturation. Above saturation the growth was considerably faster than would be expected if no photosynthetic products were carried over from the light to the dark period. There was evidence that 2–3 times as much light was neces...

Adsorption and reactivity of CO 2 on the K/Cu(110) interface and the effect of photon irradiation

Adsorption and reactions of CO 2 on Cu(110) with preadsorbed potassium were studied with synchrotron radiation spectroscopy (SRS), X-ray photoelectron spectroscopy (XPS), thermally programmed desorption spectroscopy (TPD) and workfunction measurements. The amount of K was varied between 0.1 ML and several monolayers, and the CO 2 exposures were in the 0.1–10 L range. Although CO 2 does not react with a clean Cu(110) surface, several reaction channels open in the presence of the alkali metal depending on the coverage. Different CO 2 states and dissociated states can be assigned on the basis of energy positions and peak intensities of C(1s) and O(1s) core lines. Both physisorbed CO 2 and a chemisorbed anion, CO − 2, were observed at 110 K. The effects of heating were followed with SRS. The chemisorbed CO − 2 anions react according to 2 CO − 2 → CO 2− 3 + CO a with CO desorbing at 200 K. Carbonate is formed at all K coverages. The presence of CO 2 on the surface stabilizes the alkali metal as demonstrated by the use of selected state thermal desorption. Decomposition of the carbonate occurs in the temperature range 450–550 K due to the reaction CO 3 → CO 2 + O. A comparison is made with published data on CO 2 adsorption on alkali-modified transition metal surfaces with the conclusion that the adsorption characteristics and reactions are similar. It is demonstrated that a photon-induced reaction takes place, involving conversion of a physisorbed CO 2 state to a negatively charged, chemisorbed state. The cross section was determined to be 10 7 barn.

Effect of photon irradiance on the development and activity of VA mycorrhizal infection in Allium porrum

The effects of reduced photon irradiances on the development of Glomus mosseae infection in Allium porrum were investigated. The percentage and intensity of root length infected and the frequencies of arbuscules and vesicles were determined at regular intervals in two experiments. Reduced photon irradiances and inoculation decreased the root/shoot ratio and increased the fresh weight/dry weight ratio, indicating a response by the plant to increase its photosynthetic capacity. Reduced photon irradiances did not significantly affect the percentage or intensity of the root length infected, but significantly reduced the frequency of arbuscules and vesicles within the infection. Numbers of vesicles remained low throughout both experiments, whilst the arbuscules increased to the same levels as in plants grown at higher irradiances by 4–6 weeks, depending upon the severity of the light stress. The addition of P had no effect on any aspect of infection. The activity of the infection was unaffected by all treatments. Implications for the delayed arbuscule development under reduced irradiances are discussed.

Removal of the sulfur passivation overlayer on a (NH4)2Sx-treated GaAs surface by vacuum-ultraviolet irradiation

Effects of photon irradiation on the chemical state of a (NH4)2Sx-treated GaAs surface have been investigated using photoemission and photon-stimulated desorption (PSD) spectroscopic techniques with synchrotron radiation (SR). It is shown that a sulfur-passivation overlayer on the (NH4)2Sx-treated GaAs surface is readily removed by irradiating SR in the vacuum-ultraviolet (VUV) region onto the surface, suggesting the possibility of cleaning the sulfur-passivated GaAs surface by VUV irradiation. The dominant PSD ion product that desorbs from the sulfur-passivated GaAs surface during VUV irradiation is found to be H+. No desorption of sulfur ions is observed, which suggests that sulfur adatoms desorb as neutral species.

Cytoplasmic calcium affects the gating of potassium channels in the plasma membrane ofChara corallina: a whole-cell study using calcium-channel effectors

The action of a wide range of drugs effective on Ca(2+) channels in animal tissues has been measured on Ca(2+) channels open during the action potential of the giant-celled green alga,Chara corallina. Of the organic effectors used, only the 1,4-dihydropyridines were found to inhibit reversibly Ca(2+) influx, including, unexpectedly, Bay K 8644 and both isomers of 202-791. Methoxyverapamil (D-600), diltiazem, and the diphenylbutylpiperidines, fluspirilene and pimozide were found not to affect the Ca(2+) influx. Conversely, bepridil greatly and irreversibly stimulated Ca(2+) influx, and with time, stopped cytoplasmic streaming (which is sensitive to increases in cytoplasmic Ca(2+)). By apparently altering the cytoplasmic Ca(2+) levels with various drugs, it was found that (with the exception of the inorganic cation, La(3+)) treatments likely to lead to an increase in cytoplasmic Ca(2+) levels caused an increase in the rate of closure of the K(+) channels. Similarly, treatments likely to lead to a decrease in cytoplasmic Ca(2+) decreased the rate of K(+) channel closure. The main effect of bepridil on the K(+) channels was to increase the rate of voltage-dependent channel closure. The same effect was obtained upon increasing the external concentration of Ca(2+), but it is likely that this was due to effects on the external face of the K(+) channel. Addition of any of the 1,4-dihydropyridines had the opposite effect on the K(+) channels, slowing the rate of channel closure. They sometimes also reduced K(+) conductance, but this could well be a direct effect on the K(+) channel; high concentrations (50 to 100 μM) of bepridil also reduced K(+) conductance. No effect of photon irradiance or of abscisic acid could be consistently shown on the K(+) channels. These results indicate a control of the gating of K(+) channels by cytoplasmic Ca(2+), with increased free Ca(2+) levels leading to an increased rate of K(+)-channel closure. As well as inhibiting Ca(2+) channels, it is suggested that La(3+) acts on a Ca(2+)-binding site of the K(+) channel, mimicking the effect of Ca(2+) and increasing the rate of channel closure.