An analytical method for determination of radioactivity concentration of ⁴¹Ca in waste concrete of the decommissioned nuclear power plant, using a low energy photon spectrometer was investigated. In the present days, the standard source of ⁴¹Ca is not available for efficiency calibration, therefore, alternative standard sources of ⁵⁵Fe were used to determine counting efficiency for ⁴¹Ca, considering some corrections based on the difference of photon attenuation. The minimum detectable radioactivity concentration was 1/5 to 1/60 of the clearance level (⁴¹Ca:100Bq/g) for counting time of 1000 to 80000 seconds. It was proved that the method was practical, simple and of low cost, compared to other methods using expensive instruments such as AMS.

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In order to quantitatively evaluate the influence of tritium(³H or T)on ecosystem and the reactivity of materials having H atoms, the hydrogen isotope exchange reaction(T-for-H exchange reaction)between L-norvaline and HTO vapor was observed at 50-70°C in the gas-solid system. Applying the A"-McKay plot method to data obtained in the reaction, the rate constants of the functional groups in the material were obtained. Comparing these rate constants, following seven matters have been found in the T-for-H exchange reaction. (1)The reactivity of the functional groups in L-norvaline increases with increasing temperature. (2)As to L-norvaline, (A)the temperature dependence of each functional group increases with the following order:COOH group > NH₂ one. (B)the reactivity of COOH group is 2.2 times greater than that of NH₂ one. (3)As to the influence of the substituent, the reactivity of COOH group is larger than that of the NH₂ one. (4)It seems that the reactivity of the amino acid follows Taft equation. (5)Applying Taft equation, the ratio of influence of polar effect to steric one is10:0 in NH₂ group, and is 3:7 in COOH one. (6)Using the A"-McKay plot method, the reactivity of each functional group in an amino acid is able to be nondestructively, quantitatively and simultaneously analyzed without using masking reagent. (7)The method used in this work may be useful to quickly determine the reactivity of the functional groups in the materials.

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We determined the sulfur isotope ratio of sulfates(δ³⁴S)involved in desert sand and loess distributed over arid and semi-arid area of China. δ³⁴S of sand and loess samples in Taklimakan Desert and neighborhood area, Zhungar Basin to Turpan Basin area and Qaidam Basin to Mu-us Desert area ranged from +4.08 to +29.5‰, +3.59 to +9.05‰, and +4.18 to +22.0‰, respectively. δ³⁴S of Northeastern area were +8.80 and −0.66‰. δ³⁴S of evaporite from Zhungar Basin to Turpan Basin area ranged from +10.45 to +10.98‰.

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It has already passed more than 30 years since small-angle neutron scattering (SANS) technique was applied in structural analyses. SANS is now one of common tools in structure investigations and SANS instruments can be found in any neutron scattering facilities. In particular, SANS plays an important role in the field of soft matter, such as polymer, micelles, gels, vesicles, as well as biological systems and metallurgy. Here, I give a brief survey on (1)the utility of SANS in structural studies, (2)experimental aspects of SANS, and (3)some results obtained so far.

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Solution scattering method has been used as a technique for structure analysis of biological macromolecule in solution for a long time. Here we show the new method to determine ab initio shape and internal structure of biological macromolecules in solution using dummy atoms. The method has been originally developed by Dr. Svergun, and shown to be useful for low resolution structure analysis of biological macromolecule. In the method, a multiphase model of a particle built from densely packed dummy atoms is constructed in the first stage. Simulated annealing is then employed to minimize the difference between the scattering data-sets obtained experimentally and calculated from the multiphase model while minimizing the interfacial area. Validity of the method is assessed in several protein structures, which have been determined by X-ray diffraction at high resolution, by comparing their crystal structures with the solution structures restored by this method. We also compare neutrons and X-rays in terms of structure analyses of biological macromolecule in solution under the high pressure/temperature conditions and various solvent conditions.

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