Reduction of light elements loss in polymer foils during MeV-proton irradiation by application of an aluminum coating

Backscattering and forward-scattering spectrometry with 2.2 MeV-protons have been applied to detect light elements including H, C, N and O in polymer foils of aromatic polyimide (PI), polyethylene telephthalate (PET) and polyethylene naphthalate (PEN). In the case of PI, no significant loss of H, C, N and O was observed during proton irradiation. In the case of PET and PEN, on the other hand, all the light elements gradually decreased as irradiation fluence increased and the contents of 15%-H, 14%-C, 47%-O in PET and 7%-H, 5%-C 31%-O in PEN were eventually released up to a fluence of 2.1 × 10¹⁶ protons/cm². An aluminum thin film (thickness ∼0.1 μm) was sputter-deposited on the upper surface of 4 μm thick PET and PEN foils to prevent the release of light elements. In Al coated PEN foil, for example, the losses of H, C and O were 2%, 0.5% and 22% of the starting contents, respectively, considerably smaller than those found for uncoated PEN. Thus the Al coating was found to be an effective method to suppress the loss of constituent elements.     

线粒体基因组D-loop区变异及辐射诱发突变

线粒体基因组D环区作为非编码区,控制着mtDNA的复制与转录,由于自身的结构和功能特点,极易发生变异.变异形式包括突变和多态性,这些变异在疾病的发生和发展过程中起着非常重要的作用.此外,本文还简要介绍了辐射诱导的D环区突变的研究现状及其前景.     

水溶液中环己丁酸的伽玛射线辐射降解研究

采用^60Coγ-射线辐射降解环己丁酸,通过对辐照前后化学需氧量（CODcr）与pH值变化的分析,研究了不同环己丁酸浓度、初始pH值、H202初始浓度和吸收剂量对环己丁酸的辐射降解效果的影响。结果表明：在相同剂量条件下,环己丁酸初始浓度越高,CODcr去除率越低;酸性条件更利于溶液中CODcr的去除;H202与γ-射线辐照之间具有显著的协同效应,H202初始浓度为1mmol·L-1时,其对40mg·L-1环己丁酸的辐射降解的促进效果达到最好。环己丁酸水溶液的CODcr浓度变化服从一级反应动力学方程。     

Effect of high temperature annealing on ferromagnetism induced by energetic ion irradiation in FeRh alloy

Effects of thermal annealing on ion-irradiation induced ferromagnetism of Fe-50at.%Rh bulk alloy and the related structural change were investigated by means of superconducting quantum interference device (SQUID) and extended X-ray absorption fine structure (EXAFS), respectively. Depending on the annealing temperature from 100 to 500 °C, the magnetization induced by 10 MeV iodine ion irradiation and the lattice structure of the alloy were remarkably changed. After 500 °C annealing, the magnetization and the lattice ordering of the alloy become similar to the states before the irradiation. The experimental result indicates that the thermal relaxation of irradiation-induced atomic disordering dominates the magnetic state of ion-irradiated Fe-50at.% Rh alloy.     

碳离子辐照诱导的甜高梁花粉生活力及花粉母细胞减数分裂的研究

为研究重离子辐照突变株的细胞遗传学变化,以碳离子辐照选育出的甜高粱早熟突变株KFJT-1及其对照品种KFJT-CK为材料,比较研究了两者之间花粉生活力大小以及花粉母细胞减数分裂的差异。结果发现：KFJT-1的花粉生活力以及花粉总数大于KFJT-CK;KFJT-1花粉母细胞减数分裂大多进入第二次减数分裂时,KFJT-CK花粉母细胞集中在第一次减数分裂;在KFJT-1减数分裂末期II,出现了两组分裂时期不一致、3分体以及不均等分裂畸变状况,畸变率仅为4．5％,说明KFJT-1在生长繁殖过程中修复了大部分由于物理诱变造成的染色体畸变,且能稳定遗传。这些结果从生殖细胞水平进一步说明碳离子辐照早熟突变株KFJT-1较未突变株KFJT-CK成熟期早,且各项指标均优于KFJT-CK。     

Study of the magnetic modifications of Fe3O4 ferrite thin films induced by 2.03 GeV Kr ions irradiation

The effect of 2.03 GeV Kr²⁶⁺ ions irradiation on antiphase boundaries (APBs) of polycrystalline Fe₃O₄ ferrite thin films has been investigated. The structure, magnetic and electrical transport properties of samples were characterized. The initial crystallographic structure of the Fe₃O₄ remains unaffected after Kr-ion irradiation, but the magnetic and electrical transports properties are sensitive to swift heavy ions (SHI) irradiation and exhibit different behaviors depending on the Kr-ion fluence range. The energy deposition is mainly due to the electronic energy loss (S_e) and the large value of energy transferred induces an unusual density of defects, stress and heat annealing effect in the samples, which can affect on the arrangement of magnetic moments and APBs density strongly. On the basis of our observations we conclude that the production, accumulation and free of the defects and stress induced by SHI irradiation is more dominant in the case of the magnetic and electrical transport properties modifications of the Fe₃O₄ thin films.     

The selection and characterization of the mutants in bioflocculant bacteria C8 induced by 3 MeV helium ion irradiation

A 3 MeV He²⁺ beam was used to irradiate C8 (a flocculant-producing bacteria) with a fluence ranging from 10¹¹ to 10¹³ ions/cm². The effects on the survival ratio, TTC-dehydrogenase activity, flocculating activity and RAPD analysis are reported. The survival ratio curve caused by irradiation is proved to be “saddle-shaped”. Eleven mutants were obtained, all of which had a significant change in dehydrogenase activity and most showed a positive change in flocculating activity. RAPD measurements were used to analyse the DNA of mutants with a flocculating activity over 80%, which indicated that all their DNA had been changed by irradiation.     

Effect of additive ions on the optical density and stability of the color centers induced by X-ray irradiation in soda-lime silicate glass

To apply radiation-induced coloration of glasses as a reversible glass-coloring technique, we studied the influence of various additive ions incorporated into a soda-lime silicate glass on the optical density and stability of the color induced by X-ray irradiation. Absorption spectra before and after irradiation are discussed in the comparison with those of the undoped soda-lime silicate glass. Additive ions were incorporated as metal oxides, namely TiO₂, V₂O₅, Fe₂O₃, ZnO, Ga₂O₃, GeO₂, ZrO₂, Nb₂O₃, MoO₃, Ag₂O, In₂O₃, SnO, SnO₂, CeO₂, Eu₂O₃, Ta₂O₅, WO₃ and Bi₂O₃. Among them, TiO₂, GeO₂, Nb₂O₃, MoO₃, Ag₂O, In₂O₃, Eu₂O₃, Ta₂O₅, WO₃ and Bi₂O₃ have a large effect on optical density. The optical densities in the visible region for glasses doped with these oxides were much stronger than for undoped soda-lime silicate glass. On the other hand, incorporation of Fe₂O₃, SnO and CeO₂ reduced the optical density. Over longer periods the coloration of the undoped glass was one of the most stable while those of the Fe₂O₃, SnO and CeO₂-doped glasses soon faded.