Effect Of 60Co Γ-irradiation Research Articles

Mutagenic Effect of 60Co γ-Irradiation on Rosa multiflora 'Libellula' and the Mechanism Underlying the Associated Leaf Changes.

Gamma (γ)-irradiation can induce changes in plant morphology, cellular physiological activities, and genetic material. To date, there has been limited research on the molecular basis of leaf morphological abnormalities and physiological changes in irradiated rose plants. In this study, Rosa multiflora ‘Libellula’ plants were treated with 60Co γ-rays. The irradiation resulted in the distortion of blade morphology. Additionally, the leaf chlorophyll content decreased, whereas the accumulation of reactive oxygen species increased. The differentially expressed genes between the control and 2–3 plants irradiated with 50 Gy were analyzed by RNA-seq technology, which revealed genes related to chlorophyll metabolism were differentially expressed. The expression levels of genes related to the regulation of antioxidant enzyme synthesis were downregulated. An RNA-seq analysis also identified the differentially expressed regulatory genes involved in leaf morphology development. Four genes (RcYABBY1, RcARF18, RcARF9, and RcWOX8) were selected, and their expression patterns in different leaf development stages and in various plant organs were analyzed. Furthermore, virus-induced gene silencing technology was used to verify that RcYABBY1 is involved in the morphogenesis of R. multiflora ‘Libellula’ leaves. The results of this study are useful for clarifying the molecular, physiological, and morphological changes in irradiated rose plants.

Growth of nanostructures on surface of NaCl powder under gamma irradiation

The work was aimed at studying what kinds of nanostructures grow on the surface of pure NaCl powder under effect of 60Co γ-irradiation at 140 R/s in air at 300 K, taking into account that non-irradiated surface is not perfect and may contain nanophases due to contact with wet air. Indeed, XRD has found 36v%NaCl, 16v%NaC1O3, 33v%NaOH, 14v%NaH and 1v%Na2O, all cubic phases except orthorhombic NaOH. Energy dispersion system in SEM has confirmed deficit of Cl below the stoichiometric ratio Na/Cl. After 60Co γ-irradiation to 105 R the part of Cl-containing phases decreased to 24v% due to additional losses of Cl, while NaH phase increased up to 46v%. The following higher dose 0.7×106 R caused the decrease of NaCl to 8v% (where Cl1-) and some recovery of NaClO3 up to 28v% (where Cl5+), growth of NaH to 50v% and 3v%Na hexagonal. The sizes of phases determined by Scherrer formula vary within 5-100 nm. Such mutual nanophase transformations indicate that Cl does not leave the surface and suggest nuclear reactions 35Cl17 → 18O8 + 16O8 + 1H1 and 37Cl17 → 18O8 + 16O8 + 3T1 under exposure to 1.17 and 1.33 MeV γ-quanta fluxes 2.9×1016 - 1.8×1017cm-2.

Influence of [formula omitted]-irradiation and ultrasound treatment on current mechanism in Au-SiO2-Si structure

The effect of 60Co γ-irradiation (5·107 rad) and ultrasound treatment (4 MHz, 2 W/cm2, up to 60 min) on current-voltage characteristics is experimentally investigated in an Au-SiO2-Si structure. The change in the current mechanism is analysed in terms of a modifying defect system. The irradiation is shown to enhance the space charge limited current and trap-assisted tunneling current. Experimental observations of the acoustically induced low temperature annealing of the Pb and E′ centers, which causes the partial recovery of irradiated silicon MOS structure characteristics, are highlighted.

The Effect of 60Co γ-Irradiation on the Structure and Thermostability of Alkaline Lignin and Its Irradiation Derived Degradation Products

To elucidate the degradation mechanism of lignin treated by irradiation, alkaline lignin was used as the material treating with different dosage (0, 100, 200, 400, 600, 800, 1000, 1200 kGy). The morphology, molecular weight, structure, thermostability and degradation products of alkaline lignin irradiated by gamma ray were investigated by a set of experiments. The results observed in scanning electron microscopy showed that there were more cracks and small protuberances on the morphological surface of irradiated-lignin in comparison with untreated lignin. The gel permeation chromatography results showed that weight-average molecular weight and number-average molecular weight of lignin decreased from 17829 and 590 Da to 13526 and 444 Da, respectively, when irradiation dose increased from 0 to 1200 kGy. The absorption bands of hydroxyl group at 3237 cm−1 detected by Fourier transform infrared (FT-IR) analysis decreased with irradiation dose increased from 0 to 1200 kGy. FT-IR and solid state 13C nuclear magnetic resonance (13C CP/MAS NMR) confirmed that benzene ring skeleton structure of lignin disrupted when the absorbed dose was > 800 kGy. Thermogravimetry/differential thermogravimetry curves revealed thermostability and activated energy (Ea) of lignin were slightly decreased after irradiated. The irradiation derived degradation products of lignin were analyzed by gas chromatography and mass spectrometry, indicated presence of 22 aromatic compounds and 18 aliphatic acids. Moreover, the relative peak area of aromatic compounds and aliphatic acids in un-irradiated lignin (0 kGy) were 4.48 ± 0.42 and 23.81 ± 1.85%, respectively, and these two types of degradation products reached a maximum of 23.81 and 6.10% at 800 and 1200 kGy, respectively. In summary, the findings in this work provide a basic scientific support on the mechanism of irradiation and full utilization of lignin.

Effect of 60Co γ-irradiation on the nature of electronic transport in heavily doped n-type GaN based Schottky photodetectors

GaN Schottky photodetectors are fabricated on heavily doped n-type GaN epitaxial layers grown by the hydride vapour phase epitaxy technique. The effect of 60Co γ-radiation on the electronic transport in GaN epilayers and Schottky detectors is studied. In contrast to earlier observations, a steady rise in the carrier concentration with increasing irradiation dose is clearly seen. By considering a two layer model, the contribution of interfacial dislocations in carrier transport is isolated from that of the bulk layer for both the pristine and irradiated samples. The bulk carrier concentration is fitted by using the charge balance equation which indicates that no new electrically active defects are generated by γ-radiation even at 500 kGy dose. The irradiation induced rise in the bulk carrier concentration is attributed to the activation of native Si impurities that are already present in an electrically inert form in the pristine sample. Further, the rise in interfacial contribution in the carrier concentration is governed by the enhanced rate of formation of nitrogen vacancies by irradiation, which leads to a larger diffusion of oxygen impurities. A large value of the characteristic tunnelling energy for both the pristine and irradiated Au/Ni/GaN Schottky devices confirms that the dislocation-assisted tunnelling dominates the low temperature current transport even after irradiation. The advantage of higher displacement energy and larger bandgap of GaN as compared to GaAs is evident from the change in leakage current after irradiation. Further, a fast recovery of the photoresponse of GaN photodetectors after irradiation signifies their compatibility to operate in high radiation zones. The results presented here are found to be crucial in understanding the interaction of 60Co γ-irradiation with n+-GaN epilayers.

Effect of 60Co γ-irradiation on structural and optical properties of thin films of Ga10Se80Hg10

Thin films of Ga10Se80Hg10 have been deposited onto a chemically cleaned Al2O3 substrates by thermal evaporation technique under vacuum. The investigated thin films are irradiated by 60Co γ-rays in the dose range of 50–150 kGy. X-ray diffraction patterns of the investigated thin films confirm the preferred crystallite growth occurs in the tetragonal phase structure. It also shows, the average crystallite size increases after γ-exposure, which indicates the crystallinity of the material increases after γ-irradiation. These results were further supported by surface morphological analysis carried out by scanning electron microscope and atomic force microscope which also shows the crystallinity of the material increases with increasing the γ-irradiation dose. The optical transmission spectra of the thin films at normal incidence were investigated in the spectral range from 190 to 1100 nm. Using the transmission spectra, the optical constants like refractive index (n) and extinction coefficient (k) were calculated based on Swanepoel’s method. The optical band gap (Eg) was also estimated using Tauc’s extrapolation procedure. The optical analysis shows: the value of optical band gap of investigated thin films decreases and the corresponding absorption coefficient increases continuously with increasing dose of γ-irradiation.

On the kinetics of electron processes in 60Co γ-irradiated n-Ge single crystals

Variations in the main electrical parameters of n-Ge single crystals with different doping levels under the effect of 60Co γ-irradiation are investigated. A noticeable increase in the carrier mobility in the irradiated samples is observed in some dopant concentration range and the nature of this effect is explained. It is demonstrated that the electron-mobility variation under the action of γ-irradiation in the initial n-Ge crystals with an oxygen impurity and in the annealed crystals have opposite signs. It is established that the oxygen complexes formed in the samples during annealing and the local lattice stresses near these complexes play a key role in the radiation-induced mobility increase. It is clarified that the radiation resistance of the electron mobility significantly depends on the crystallographic orientation of the investigated samples.

Effect of 60Co γ-irradiation on postharvest quality and selected enzyme activities of Pleurotus nebrodensis

Freshly harvested Pleurotus nebrodensis fruit bodies were exposed to four different doses (0.8–2.0 kGy) of 60Co γ-irradiation and various physiological changes associated with postharvest deterioration, as well as the activities of selected enzymes (proteinase, polyphenoloxidase, superoxide dismutase, catalase) thought to play a role in the process of deterioration, were monitored during 22 days of subsequent storage at 4 °C and 65–70% relative humidity. An irradiation dose of 1.2 kGy significantly delayed (by 6–9 days) the onset of fruit body softening, splitting and browning compared with non-irradiated controls and test samples subjected to lower or higher irradiation doses. Irradiation with 1.2 and 1.6 kGy also had a positive effect on other indicators of mushroom tissue senescence, resulting in smaller decreases in soluble protein levels and more protracted increases in proteinase activity. Peak levels of polyphenoloxidase activity, widely recognized as causing postharvest browning of mushroom tissue, were also significantly lower ( P < 0.05) in fruit bodies exposed to 1.2 kGy compared with non-irradiated controls. Our data increase our understanding of the effects of γ-irradiation on the biochemical changes associated with postharvest deterioration in P. nebrodensis, and improve the prospects of more targeted strategies for extending the shelf life of both this and other mushrooms.

Physical aging effects in selenide glasses accelerated by highly energetic γ-irradiation

Effect of 60Co γ-irradiation on As–Se glasses stored for 20 years and subjected to saturated natural physical aging is studied using differential scanning calorimetry. It is shown that γ-irradiation activates further physical aging, which leads to an increase in glass transition temperature and endothermic peak area near glass transition region for As x Se 100− x samples with x < 30. The observed changes are associated with additional structural relaxation of radiation-modified glass network.

Synthesis of persulfate containing poly ( N-vinyl-2-pyrrolidone) (PVP) hydrogels in aqueous solutions by γ-induced radiation

The effect of 60Co γ-irradiation on aqueous solutions of poly( N-vinyl-2-pyrrolidone) (PVP) in the presence of persulfate anion has been investigated. The gelation dose of PVP and persulfate containing PVP aqueous solutions has been determined. At low concentrations of persulfate (1.00–3.50%), gelation percentages exhibited a decreasing trend by increasing persulfate content in aqueous solutions of the polymer. The gelation doses of persulfate containing polymer solutions were calculated by the Charlesby–Pinner equation. It was observed that the gelation dose values were shifted to higher values by increasing persulfate concentration in solution. The ratio of the chain scission and crosslinking yields ( G( s)/ G( x)) was also determined. The results showed that the G( s)/ G( x) ratios were smaller than one for PVP aqueous solution system, whereas those obtained for persulfate containing PVP aqueous solutions were higher than unity. The results implied that the chain scission of polymer is more effective than crosslinking in the presence of persulfate. Mechanism of the crosslinking and/or degradation and structure–property relationship of PVP and PVP/persulfate hydrogel systems were investigated by Fourier transformation infeared and thermal analysis (differential scanning calorimetry, thermal gravimetric analysis and differential thermai analysis) methods.

Study of gamma-radiation-induced optical effects in Ge–Se–Cd for possible industrial dosimetric applications

The effect of 60Co γ-irradiation on the optical properties of the amorphous chalcogenide semiconductor, Ge 14Se 71Cd 15 is studied. γ-radiation-induced darkening is observed after irradiation of the thin film samples for doses up to 500 kGy. The changes in the optical absorption coefficient have been attributed to the amorphous network rearrangements and the degree of disorder caused by the γ-irradiation. The dosimetric characteristics of Ge 14Se 71Cd 15 for γ-irradiation measurements are proposed. The absorption coefficient was found to increase with the increase of dose in a nearly linear manner. The optical energy gap was found to decrease with the increasing dose. The values of the absorption coefficient in the absorption edge region are suitable control parameters of the proposed dosimeter material, which is characterized by the sensitivity and reproducibility of measurements. The proposed dosimeter material has a minimum detectable effect at a dose of 100 kGy. This makes the material a good candidate for dosimetry in high-dose industrial applications such as sterilization.

Study of gamma-radiation-induced optical effects in Ge?Se?Cd for possible industrial dosimetric applications

The effect of 60Co γ-irradiation on the optical properties of the amorphous chalcogenide semiconductor, Ge14Se71Cd15 is studied. γ-radiation-induced darkening is observed after irradiation of the thin film samples for doses up to 500 kGy. The changes in the optical absorption coefficient have been attributed to the amorphous network rearrangements and the degree of disorder caused by the γ-irradiation. The dosimetric characteristics of Ge14Se71Cd15 for γ-irradiation measurements are proposed. The absorption coefficient was found to increase with the increase of dose in a nearly linear manner. The optical energy gap was found to decrease with the increasing dose. The values of the absorption coefficient in the absorption edge region are suitable control parameters of the proposed dosimeter material, which is characterized by the sensitivity and reproducibility of measurements. The proposed dosimeter material has a minimum detectable effect at a dose of 100 kGy. This makes the material a good candidate for dosimetry in high-dose industrial applications such as sterilization.

｀６０´Ｃｏγ線照射によるラット唾液腺導管の変化に関する免疫組織化学的研究

Cytokeratin distribution in salivary glands was detected by use of polyclonal antikeratin antiserum (TK) and monoclonal antibodies (KL 1, RGE 53, and RPN 1164).The salivary glands of male rats received either 17. 82 Gy or 27.97Gy 60Coγ irradiation in a single exposure and were then compared immunohistochemically with those of normal rats.The following results were obtained.1. Polyclonal anti-keratin antiserum (TK), which reacts with 41-65 KD keratins, stained almost all ducts in normal glands.RPN 1164 (No.8 keratin) staining was negative in intercalated ducts of normal parotid and submandibular glands, but strongly positive in both striated and excretory ducts of these glands.Monoclonal antibody KL 1 (55-57 KD keratins) and RGE 53 (No.18 keratin) did not bind to any ductal or acinar epithelia.2. Only in the sublingual gland were acini positive for TK staining, possibly indicating myoepithelial cells.3. No effects of 60Coγ irradiation were apparent regarding keratin distribution in the intercalated duct.4. In striated duct cells, positive staining was lost in basal and perinuclear portions and restricted in apical cytoplasm by 60Coγ irradiation.5. Also, in the excretory duct, the basal side of the cells exhibited weakened staining following 60Coγ irradiation.6. Although the histology suggested that 60Coγ irradiation diminished in size of the granular convoluted tubule, no remarkable changes in keratin deposition were found.7. In striated ducts, changes in keratin distribution following 60Coγ irradiation were the most significant in the parotid and the least in the sublingual gland.Also this reaction depended upon the doses of 60Co used.The present findings suggested that negative or weakened staining at the basal and perinuclear portions of striated duct cells specifically reflects the primary or secondary cell damage produced by 60Coγ irradiation.Since the distribution of cytoskeletal proteins in the cytoplasm reflects certain pathological conditions, immunohistochemical detection of these proteins seem to have a diagnostic value with respect to cellular injury.

Effects of 60Co γ-irradiation on the synthesis of nucleic acids in the posterior silk gland and on the cocoon shell weight of the silkworm, Bombyx mori

Effects of 60Co γ-irradiation on the synthesis of nucleic acids in the posterior silk gland and on the cocoon shell weight of the silkworm, Bombyx mori

NMR Measurements on 60Co γ-Ray Irradiated Polytetrafluoroethylene with High Radiation Doses

The effects of 60Co γ-irradiation and post-irradiation heat treatment on NMR line of PTFE are studied over the temperature range -50°C to 50°C for a total dose of 8.9×108R. Lowering of transition temperature associated with crystalline regions of PTFE, narrowing of the line width of broad component, broadening of the line width of narrow component, and appearance of very sharp line component are observed in the NMR line shape of the irradiated PTFE. When the irradiated PTFE is annealed near the melting temperature, the very sharp line component disappears and the transition temperature shifts to higher temperature, differing from that of the unirradiated PTFE. This difference is considered to be associated with the decrease in the average molecular weight of the irradiated PTFE. Changes resulting from post-irradiation heat treatment can be attributed to the removal of defects and low molecular weight products trapped within PTFE. No charge is observed in the line width or narrow component by post-irradiation heat treatment.