Vol.18,

674

²¹³Bi disintegrates (97.91±0.03) % by β^- emission to the levels in ²¹³Po, and (2.09±0.03) % through α decay to ²⁰⁹Tl. The evaluation of the complete decay scheme and data of ²¹³Bi 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 ²¹³Bi decay scheme was re-built.

741

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.

599

Reaction of p-tert-oxocalix[4]arene in acetonitrile (CH₃CN) 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 CH₃CN. The formation mechanism of phenoxyl radical was quite different from that in cyclohexane (C₆H₁₂), which was cooperation of two-photon process and one-photon process.

525

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 dipoles forming in the process of the low energy ions irradiation can effectively enhance the field emission.

497

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 ¹²C⁶⁺ 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 G₂/M stage arrest induced by the ¹²C⁶⁺ 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.

435

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.

560

The study was to evaluate factors affecting outcome of ¹³¹I therapy in hyperthyroidism for optimizing the method. Data from 213 patients who received ¹³¹I treatment from July 2003 to July 2005 in our department were retrospectively analyzed. Factors possibly contributing to the outcome of the ¹³¹I therapy were analyzed, including gender, age, history of antithyroid drug, thyroid volume, duration of disease and radioactive iodine uptake rate. Multivariate analysis was done. The rates of euthyroidism and hypothyroidism were 69% and 8.5%, respectively, after one time ¹³¹I therapy. Multivariate analysis of the patients showed no statistically significant factors affecting the outcome of ¹³¹I therapy. The study showed that ¹³¹I dose can be directly calculated, and this simplifies the dose-determined method and individualizes the therapy.

605

807

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 ²⁴¹Am was obtained.

453

This paper describes the definition of nuclear security that has been changing from the cold war age to the post-911 period, and clarifies the close relationship and yet a clear distinction between nuclear security, nuclear safety and nuclear safeguard. Based on analyses of the current state of nuclear security activities in China as well as the requirements and the law infrastructure, a legislative and regulatory framework of nuclear security and the mandate of a regulatory body in China are recommended.

613

An observable experiment facility for low-temperature molten materials to be dropped into water was set up in this study to investigate the mechanism of the vapor explosion. The effect of the fuel and coolant interaction (FCI) on the vapor explosion during the severe accidents of a fission nuclear reactor has been studied. The experiment results showed that the molten material temperature has an important effect on the vapor explosion behavior and pressure. The increase of the coolant temperature would decrease the pressure of the vapor explosion.

527

Results of environmental radioactivity monitoring around Qinshan Nuclear Power Plant (QNPP) are reported in this paper. From 1992 to 2005, concentrations of ⁹⁰Sr, ¹³⁷Cs and ³H in terrestrial freshwater are (4.4±1.7) mBq•L^-1, (0.3±0.1) mBq•L^-1 and (1.6±0.5) Bq•L^-1, respectively, and (2.8±2.4) Bq•L^-1 of ³H in rainwater. Concentrations of ⁹⁰Sr, ¹³⁷Cs and ³H in the seawater samples collected from sea area nearby QNPP are (5.4±4.1) mBq•L^-1, (0.7±0.2) mBq•L^-1 and (1.0±0.5) Bq•L^-1, respectively. Concentrations of ⁹⁰Sr, ¹³⁷Cs and ³H in the total waste water discharged from NPP-I are (4.0±1.8) m Bq•L^-1, (1.0±0.5) mBq•L^-1 and (2.8±2.2) Bq•L^-1, respectively, and (1.4±0.4) Bq•L^-1 of ³H in seawater sampled from No.1 outlet. Atomspheric ³H concentration in 1993~2005 at two monitoring sites is (78.9±96.3) and (64.2±40.2) mBq•m^-3, respectively, with an increasing trend after 2003. Atmospheric ¹⁴C concentrations at the two sites are in the same levels as the background and data of the reference site.

546