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Abstract  

DSC and TG studies were carried out on γ -radiation processed Indian natural products of medicinal importance, namely Ashwagandha (Withania Somnifera), Amla (Emblica Officinalis) and Hartiki (Terminalia chebula). DSC thermoanalytical curves were recorded from 35 to 400C in air and nitrogen atmosphere. Similarly, TG thermoanalytical curves were taken from 35 to 700C in air and nitrogen atmosphere. Irradiated products gave significantly different thermoanalytical profiles in comparison to non-irradiated samples. The differences were observed above decomposition temperature of 200C and were non-linear with respect to radiation dose. Partial oxidation of the products during irradiation in air could be responsible for the observed differences.

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Abstract  

When a biological system is either accidentally or intentionally exposed to radiation, the energy absorbed triggers a number of successive events including damage to living tissues. Major radiation damage is due to the aqueous free radicals generated by the radiolysis of water. These free radicals act as molecular marauders and in turn damage DNA, mitochondrial membrane, lipid, cellular protein, resulting in cellular dysfunction and mortality. In view of the above mentioned facts an experiment was conducted to study the genotoxic effects of γ radiation and its dose effectiveness. The present experiment was conducted on samples of plasmid pBR322 DNA as the in vitro experimental model devoid of any DNA repair and replication machinery. The samples were exposed to different doses of gamma radiations from 1 to 200 Gy. Exposure of plasmid pBR322 DNA to γ radiation resulted in production of single strand breaks as a result of which, the supercoiled (SC) form was converted to relaxed form (RL). Exposure of radiation, even at very low dose of 1 Gy, exhibited a significant damage to DNA resulting in about 70% SC form and 30% RL form of DNA. At a dose of 10 Gy the SC form was reduced to about 37% and further 5% at a dose of 50 Gy with about 88.5 and 6.5% RL and linear (L) forms of DNA respectively. Thus, the disappearance of supercoiled form of plasmid pBR322 DNA was found to be directly related to radiation dose and exhibited a radiation dose dependent pattern.

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Xylopia aethiopica (XA) (Annonaceae) possesses great nutritional and medicinal values. This study was designed to investigate the effects of XA fruit methanol extract on oxidative stress in brain of rats exposed to whole body γ-radiation (5 Gy). Vitamin C (VC) served as standard antioxidant. Forty-four rats were divided into 4 groups of 11 rats each. One group served as control, two different groups were treated with XA and VC (250 mg/kg), 6 weeks before and 8 weeks after irradiation, and fourth group was only irradiated. Rats were sacrificed 1 and 8 weeks after irradiation. The antioxidant status, viz. Lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) and glutathione (GSH) were estimated. Results indicate a significant increase ( p < 0.05) in levels of brain LPO after irradiation. LPO increased by 90% and 151%, after 1 and 8 weeks of irradiation, respectively. Irradiation caused significant ( p < 0.05) decreases in levels of GSH and GST by 61% and 43% after 1 week and, 75% and 73%, respectively, after 8 weeks of exposure. CAT and SOD levels were decreased by 62% and 68%, respectively, after 8 weeks of irradiation. Treatment with XA and VC ameliorated the radiation-induced decreases in antioxidant status of the animals. These suggest that XA could have beneficial effect by inhibiting oxidative damage in brain of exposed rats.

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Abstract  

The influence of -radiation on iodinedoped poly (3-pentylthiophene) has been studied. Doping accompanied by -radiation brings about a decrease of iodine release rate. An increased dopant concentration in the poly (3-pentylthiophene) leads to an increased conductivity, which may be accounted for by the formation of bipolarons in the irradiated and doped samples.

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Abstract  

The influence of -radiation on the structure of Langmuir-Blodgett (LB) layers of poly (3-hexadecylthiophene) in mixtures containing stearic and linolenic acids has been studied. The action of -photons leads to structural changes in the conducting polymer backbone as well as to disrupting oriented LB film structures.

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Abstract  

Following radiation treatment, a number of polyurethane samples were synthesized from hydroxyl-terminated polybutadiene and toluene diisocyanate: the equivalence ratio of NCO/OH was varied over 0–2.0 and the -dose over 0–720 kGy. Understanding of the chemical behavior is attempted through the observation of mechanical properties of the solid cross-linked prepolymer. With lower NCO content the ultimate stress increased with dose and the ultimate strain decreased; cross-linking and urethane formation occurred. With higher NCO, allophanate formation predominated. The stress-strain properties were markedly influenced by the presence of a small fraction of additives. A suitable mechanism is proposed.

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Abstract  

An analytical method has been developed for the determination of Se, Br, Sr, Ag, Cd and In in some mixtures applying (γ, γ′)-type reactions. This method provides a high degree of selectivity and precision if the concentration of the element in the sample is a few per cent or more. Using an 80-kCi60Co gamma-radiation source, as low as 0.002–0.14% impurities could be determined in 50-g samples; this corresponds to 1–70 mg quantities of the particular elements.

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Abstract  

Sorption of Li+, Cs+ and Sr2+ on hydrous titanium oxide and magnetite as a function of pH in the presence and absence of -rays has been studied. pH-titrations of the irradiated hydrous oxides have also been carried out. It has been shown that the sorption characteristics of these oxides are not altered by -irradiation and the uptake of metal ions is governed by the equilibrium pH of the solution. Certain physical changes observed on irradiating of the hydrous oxide samples in water are discussed.

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Abstract  

Thermal investigation has allowed us to show the changes undergone by a sort of nitrile-butadiene rubber (NBR) as a consequence ofγ-radiation-induced ageing. The parameters of the processes, which occur at progressive heating of the investigated samples, were determined. It was shown that for γ-irradiated samples the activation parameters corresponding to the thermo-oxidative process leading to solid products are correlated through the relation of compensation effect. Also, it was shown that, by γ-irradiation, NBR undergoes a relatively rapid change of its thermal behaviour which can be due to structural changes.

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