查看更多>>摘要：A nondestructive X-ray analysis technique combining transmission tomography, fluorescence tomography and Compton tomography based on synchrotron radiation is described. This novel technique will be an optional experimental technique at SSRF's hard X-ray micro-focusing beamline under construction at present An experimental result of combined X-ray tomography is obtained in NE-5 A station of PF. The reconstructed images of test objects are given.
查看更多>>摘要：~(213)Bi disintegrates (97.91±0.03) % by β~- emission to the levels in ~(213)Po, and (2.09±0.03) % through α decay to ~(209)Tl. The evaluation of the complete decay scheme and data of ~(213)Bi including the recent new measurements are presented in this report. The Limitation of Relative Statistical Weight Method (LWM) was applied to average numbers throughout the evaluation. The uncertainty assigned to the average value was always greater than or equal to the smallest uncertainty of the values used to calculate the average. The half-life is determined to be 45.59±0.06 minutes. All known measured gamma-ray relative emission probabilities have been examined. And the gamma-ray emission probability of the reference γ line of 440.44keV is recommended to be (26.1 ±0.3) %. The calculated internal conversion coefficients and their uncertainties have been used to obtain the complete decay intensity balance. The other decay characteristics are calculated using the ENSDF analysis program. Finally the new ~(213)Bi decay scheme was re-built.
查看更多>>摘要：ESR studies were done on UV-ray irradiated silk fabric samples at room temperature. Different types of UV lamps were used and similar ESR signals were observed. The results indicate that UV-rays can produce free radicals for graft-copolymerization of monomer onto silk fibers without external additives or co additives, Also, radicals in silk fabrics irradiated by UV-rays are purer than that irradiated by γ-rays. The study suggests that UV-lights may be a better tool to improve properties of silk fabrics by grafting monomers onto the polymer chains.
查看更多>>摘要：Reaction of p-tert-oxocalix[4]arene in acetonitrile (CH_3CN) by 308nm laser pulses was investigated to understand its mechanism as polymer stabilizer. Four main absorption bands were observed at 300nm, 400nm, 460nm and 540nm. The 300nm absorption was assigned to the absorption of phenoxy radical, and the 460nm and 540nm were triple state absorption. It was concluded that the relative stable phenoxy radical mediate was formed through intramolecular energy transition of carbonyl triplet after laser excitation in CH_3CN. The formation mechanism of phenoxyl radical was quite different from that in cyclohexane (C_6H_(12)), which was cooperation of two-photon process and one-photon process.
查看更多>>摘要：An effective method by low energy carbonhydrogen ion treatment to enhance field emission of the carbon nanotubes (CNTs) is demonstrated. Comparing with control, field emission (FE) currents of the CNTs by carbonhydrogen ion irradiation increased, and the turn-on field and the threshold field decreased significantly. The structure characteristic revealed by transmission electron microscopy demonstrates that CNTs are coated by nano-graphite particles after being treated with low energy carbonhydrogen ion and that there are large quantities of defects and grain boundaries in the coated layer. It is considered that the coating layer can decrease the effective surface work function of CNTs and correspondingly increase field emission. In addition, the defects, the grain boundaries and the C-H di poles forming in the process of the low energy ions irradiation can effectively enhance the field emission.
查看更多>>摘要：To investigate effects of nitric oxide on cellular radio-sensitivity, three human glioma cell lines, i.e. A172, A172 transfected green fluorescence protein (EGFP) gene (EA172) and A172 transfected inducible nitric oxide synthesis (iNOS) gene (iA172), were irradiated by ~(12)C~(6+) ions to 0, 1 or 2Gy. Productions of nitric oxide and glutathione (GSH) in A172, EA172 and iA172 were determined by chemical methods, cell cycle was analyzed by flow cytometry at the 24th hour after irradiation, and survival fraction of the cells was measured by colorimetric MTT assay at the 5th day after irradiation. The results showed that the concentrations of nitric oxide and GSH in iA172 were significantly higher than in A172 and EA172; the G_2/M stage arrest induced by the ~(12)C~(6+) ion irradiation was observed in A172 and EA172 but not in iA172 at the 24th hour after exposure; and the survival fraction of iA172 was higher than that of EA172 and iA172. Data suggest that the radio-sensitivity of the A172 was reduced after the iNOS gene transfection. The increase of GSH production and the change of cellular signals such as the cell cycle control induced by nitric oxide may be involved in this radio-resistance.
查看更多>>摘要：The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) > SHA (HA from the surface) > THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was achieved at a suitable uranium concentration (10 mg·L~(-1) U(Ⅵ) for SHA and THA, 20 mg·L~(-1) U(Ⅵ) for FHA), the adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g) ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.
查看更多>>摘要：The study was to evaluate factors affecting outcome of ~(131)I therapy in hyperthyroidism for optimizing the method. Data from 213 patients who received ~(131)I treatment from July 2003 to July 2005 in our department were retrospectively analyzed. Factors possibly contributing to the outcome of the ~(131)I therapy were analyzed, including gender, age, history of antithyroid drug, thyroid volume, duration of disease and radioactive iodine uptake rate. Multivari-ate analysis was done. The rates of euthyroidism and hypothyroidism were 69% and 8.5%, respectively, after one time ~(131)I therapy. Multivariate analysis of the patients showed no statistically significant factors affecting the outcome of ~(131)I therapy. The study showed that ~(131)I dose can be directly calculated, and this simplifies the dose-determined method and individualizes the therapy.
查看更多>>摘要：The gas magnification of multi-gap resistive plate chamber (MRPC) is very difficult to be measured using the present instruments thoroughly in the world. The gas magnifications about ～10~7 were obtained in the various operation-high-voltages of multi-gap resistive plate chamber (MRPC) by means of Monte-Carlo simulation and the presented experiment method.
查看更多>>摘要：A compact gamma-ray detector with good spatial resolution for emission computed tomography (E-CT) applications has been developed. The detector is composed of NaI(Tl) scintillation pixels array and Hamamastu R2486-05 PSPMT. Having a pixel size of 2 mm × 2 mm and an overall dimension of 48.2 mm × 48.2mm × 5 mm, it has 484 pixels in a 22×22 matrix. An average spatial resolution of 2.5mm (FWHM) was achieved. The slope of position linearity is constant within 10% in a range of 40mm. After corrections, the average value of differential non-linearity and absolute non-linearity were 0.16mm and 0.535mm respectively, and a 17% at FWHM of total energy resolution for ~(241)Am was obtained.
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