EPR of Irradiation Induced Centers in Some VitreousMatrices Containing Copper

Boro-germanate glasses containing copper, i.e., xCuO(1-x)[GeO2·B2O3] subjected to gamma irradiation, were studied by means of EPR. Comparisons were made with the xCuO·(1-x)[Na2B4O7] system. Irradiation induced centers were detected. These are: electron trapped at a hydrogen compensated germanium ion centers; boron oxygen hole centers and electron trapped at an oxygen vacancy centers. Strong dependence of the paramagnetic irradiation-induced centers concentration on the CuO content of the sample was evidenced.

Protective Effects of Shikonin on Brain Injury Induced by Carbon Ion Beam Irradiation in Mice

Radiation encephalopathy is the main complication of cranial radiotherapy. It can cause necrosis of brain tissue and cognitive dysfunction. Our previous work had proved that a natural antioxidant shikonin possessed protective effect on cerebral ischemic injury. Here we investigated the effects of shikonin on carbon ion beam induced radiation brain injury in mice. Pretreatment with shikonin significantly increased the SOD and CAT activities and the ratio of GSH/GSSG in mouse brain tissues compared with irradiated group （P〈0.01）, while obviously reduced the MDA and PCO contents and the RO$ levels derived from of the brain mitochondria.

Ar（12+）Induced Irradiation Damage in Bulk Metallic Glass(Cu47Zr45Al8)98.5Y1.5

The highly charged ion Ar^12＋ with an energy of 3 Me V is used for irradiating metallic glass （Cu47Zr45Al8）98.5Y1.5 and polycrystalline metallic W at the irradiation fluences of 1× 10^14 ions/cm2, 1 × 10^15 ions/cm^2 and 1 × 10^16 ions/cm^2. The main structure of metallic glass remains an amorphous phase under different irradiation fluences according to x-ray diffraction analysis. The scanning electron microscope observation on the morphologies indicates that no significant irradiation damage occurs on the surface and cross section of the metallic glass sample after different fluences of irradiation, while a large area of irregular cracks and holes were observed on the surface of metallic W at a fluence of 1 ×10^16 ions/cm^2, with cracks and channel impairments at a certain depth from the surface. The root-mean-square （rms） roughness of metallic glass increases with increasing fluence of Ar^12＋, while the reflectance decreases with increasing irradiation fluence. A nano-hardness test shows that the hardness of metallic glass decreases after irradiation. Under certain a higher capability of resistance to Ar^12＋ irradiation in conditions, metallic glass （Cu47 Zr45Al8 ）98.5 Y1.5 exhibits comparison with polycrystalline W.

Analysis of variation in temperature-responsive leaf color mutant lines induced from Gamma irradiation in rice(Oryza sativa L.)

Eight lines of temperature-responsive leaf colormutants induced by applying 300 Gy Gamma-ray irradiation to Thermo-sensitive genic malesterile line 2177s,were obtained through con-tinuous selection in seven generations..Theleaves of these lines started to become greenafter the fourth leaf extension,and except

Proton irradiation-induced cracking and microstructural defects in UN and (U,Zr)N composite fuels

Proton irradiation with a primary ion energy of 2 MeV was used to simulate radiation damage in UN and(U,Zr)N fuel pellets.The pellets,nominally at room temperature,were irradiated to peak levels of 0.1,1,10 dpa and 100.0 dpa resulting in a peak hydrogen concentration of at most 90 at.%.Microstructure and mechanical properties of the samples were investigated and compared before and after irradiation.The irradiation induced an increase in hardness,whereas a decrease in Young’s modulus was observed for both samples.Microstructural characterization revealed irradiation-induced cracking,initiated in the bulk of the material,where the peak damage was deposited,propagating towards the surface.Additionally,transmission electron microscopy was used to study irradiation defects.Dislocation loops and fringes were identified and observed to increase in density with increasing dose levels.The high density of irradiation defects and hydrogen implanted are proposed as the main cause of swelling and consequent sample cracking,leading simultaneously to increased hardening and a decrease in Young's modulus.

Carbon Ion Irradiation Induces Reduction of β-tubulin in Sperm of Pubertal Mice

Microtubules are involved in a variety of cellular functions such as cell division, intracellular transport, maintenance of cell polarity and flagella and ciliary motility. The heterogeneity of tubulin and microtubule-associated proteins is responsible for these different microtubule functions. Many studies have confirmed that the structure and function of the different α-tubulin and β-tubulin subunits can affect the microtubule. The sperm axoneme microtubule has linear fiber filaments which are polymerized by heterodimeric a and β-tubulin, each with a molecular mass of approximately 50 kD[1].

TEM Foil Preparation from Irradiated Metallic Materials： A Practical Approach

This paper focuses on work related to post irradiation examination of 300-series austenitic stainless steel taken from reactor vessel internals of PWR. High neutron irradiation dose in NNP＇s leads to a degradation of microstructure of the material in a nano-metric scale. Hence, it is important to characterize the irradiated materials to understand the physical basis of the degradation mechanisms. Microstructural characterization of neutron-irradiated materials by TEM requires enhanced sample preparation methodologies, which commonly needs general improvements regarding particular experiment to be performed. In this study, the authors have developed methodology specialized in 1 mm TEM thin foil preparation from a deformed shank of a broken miniaturized tensile specimen. TEM foil size in current studies is smaller than standard because of the small shank diameter and high radioactivity of the studied material. The reduction of the TEM foil radioactivity to minimum is crucial to perform EDX chemical analysis and to increase the EDX detector lifetime. This paper describes whole process from bulk sample handling, including remote-controlled material cutting in shielded hot-cells and disc polishing in glow-boxes, up to the final procedure of electrolytic-polishing of electron transparent 1 mm TEM foils. Eventually, results of TEM microanalysis of radiation-induced defects were present.

Photodynamic Therapy Mediated by 5-Aminolevulinic Acid Suppresses Gliomas Growth by Decreasing the Microvessels

Although 5-aminolevulinic acid（5-ALA）-mediated photodynamic therapy（PDT） has been demonstrated to be a novel and effective therapeutic modality for some human malignancies, its effect and mechanism on glioma are still controversial. Previous studies have reported that 5-ALA-PDT induced necrosis of C6 rat glioma cells in vitro. The aim of this study was to further investigate the effect and mechanism of 5-ALA-PDT on C6 gliomas implanted in rats in vivo. Twenty-four rats bearing similar size of subcutaneously implanted C6 rat glioma were randomly divided into 3 groups： receiving 5-ALA-PDT（group A）, laser irradiation（group B）, and mock procedures but without any treatment（group C）, respectively. The growth, histology, microvessel density（MVD）, and apoptosis of the grafts in each group were determined after the treatments. As compared with groups B and C, the volume of tumor grafts was significantly reduced（P〈0.05）, MVD was significantly decreased（P〈0.001）, and the cellular necrosis was obviously increased in group A. There was no significant difference in apoptosis among the three groups. The in vivo studies confirmed that 5-ALA-PDT may be an effective treatment for gliomas by inhibiting the tumor growth. The mechanism underlying may involve increasing the cellular necrosis but not inducing the cellular apoptosis, which may result from the destruction of the tumor microvessels.