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  • Author or Editor: K. Wang x
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Abstract  

The detection of characteristic gamma rays emitted promptly by elements after capture of neutrons is used as a means of radioanalytic analysis. Here it is shown that the method can be used for the measurement of the nitrogen (and therefore protein) content of small animals, those with mass around 3 kg.

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A scaled-up SRCCC apparatus equipped with a 40-L column was constructed on the basis of separations of crude broccoli seed extract and crude radish seed extract using a conventional SRCCC instrument. Scaled-up separation of 500 g of crude broccoli seed extract with n-butanol-acetonitrile-10% (NH4)2SO4 aqueous solution 1:0.5:2 (υ/υ) as solvent system yielded 61.5 g glucoraphanin product of purity 91.2%. Separation of 500 g crude radish seed extract with the same solvents in the ratio 0.5:1:2 (υ/υ) afforded 26.7 g glucoraphenin product of purity 94.5%. Recovery of glucoraphanin and glucoraphenin from the crude extracts was 98.3 and 98.9%, respectively. The results demonstrated that this SRCCC technology is useful for separation of glucosinolates from plant extracts.

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The spatial distribution of neutrons was measured at the muon science laboratory of KEK by the activation detector method using an imaging plate for the radioactivity measurement. It was confirmed that this method is highly sensitive to detect the average neutron dose of 10 µSv/h. The distribution of thermal and epithermal neutrons was also measured in the experimental room. The cadmium ratio inside the experimental room is one except for the neutron leakage point. The spatial distribution of neutrons inside the concrete shield of KENS was measured by the same method. Aluminum and gold foils were used for the measurement of fast and thermal neutrons, respectively. Two dimensional change of the reaction rate of the 27Al(n,α)24Na reaction shows a good agreement with the results calculated by the Monte Carlo simulation using MARS14 code. Thermal and epithermal neutron flux ratio on the beam axis was measured by the cadmium ratio method. The flux ratios were about 30 and almost constant for every slot except for the surface of the shield, because the cadmium ratio is 2. This method was very useful to measure the activity of many pieces of detector simultaneously without any efficiency and decay correction. Wide dynamic range and high sensitivity are also the merit of this method.

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Abstract  

This article presents results of the experimental investigation on the adsorption of the water vapor on silica gel. Two independent experimental methods has been used, viz. the constant-volume-variable-pressure (CVVP) system and variable pressure thermogravimetry (TG). Results from these two methods are compared with each other. Also the isosteric heat of adsorption of this system has been determined from the equilibrium data. The silica gels investigated here are Fuji Davison type 'A' and type 'RD'. Adsorption isotherm of water vapor have been measured under a variety of conditions all referring to chiller operation cycles, i.e. temperatures from 303 to 358 K and pressures from 500 to 7000 Pa. The data collected from the two independent experiments compare very favorably with each other and their trends are consistent with those of the adsorption chiller manufacturer. This lends significant weight to our experimental data on silica gel+water systems as being valuable to the adsorption chiller manufacturers and the scientific community.

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Abstract  

The effects of Al2O3 and SiO2 additives on the crystallization of calcium phosphate glasses were studied. When the Al2O3 content was higher than 7 mol%, surface devitrification occurred in the glasses. However, for glasses with Al2O3 contents higher than 10 mol%, bulk devitrification predominanted. For the glasses with SiO2, a surface devitrification mechanism predominanted. Non-isothermal DTA techniques were applied in order to establish the devitrification mechanism, and the kinetic parameters of crystal growth were obtained. The parameter m depends on the mechanism and morphology of devitrification of calcium phosphate, glass containing SiO2 as additive, the values of m being lower than 1.2. These results indicate that the devitrification is controlled by the reaction at the glass-crystal interface, or occurs from surface nuclei.

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Abstract  

A total reflection X-ray fluorescence (TXRF) analyzer with a special structure is described. Its short X-ray path (about 15 cm) resulted in a high sensitivity, low power consumption and small volume. The structure with double total reflection path is suitable for easy change of exciting source to cover a large element range. The minimum detection limit (MDL) of 6 pg for Co under Cu exciting source and 22 pg for Sr under Mo tube. Some significant works were done, such as the detemination of sulfur content in fuel oils, the non-destructive analysis of an ancient bronze utensil and the regular analysis of tap water.

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The effect of itaconic acid (IA) content and heating rate on the stabilization reactions in poly(acrylonitrile-co-itaconic acid) (P(AN-co-IA)) was investigated by differential scanning calorimetry (DSC) with peak-resolving method. Increasing IA content was effective in decreasing the initial temperature and the heat evolved, and found to enhance oxidative reactions to some extent. While, promoting heating rate resulted in a shift of the exotherm to a higher temperature and a more rapid liberation of heat. The percentage of area of the first exothermic peak increased with increasing heating rate, which would be attributed to the enhancement of the free radical cyclization reactions.

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Fingernails of pathologically diagnosed normal people, light esophageal epitheliosis patients, severe esophageal epitheliosis patients and esophageal cancer patients were irradiated and their elemental contents were determined by INAA. Multivariate statistical treatment of Ca, Cl, K. Mg, Se and Zn data shows that esophageal cancer patients are distinguishable from non-cancer patients. The accuracy computed by neural networks is greater than 80%.

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The effects of bentonite density and fulvic acid on the sorption and diffusion of 90Sr2+in compacted bentonite were investigated by using a capillary method. The experiments were carried out at pH 7.0±0.1 in the presence of 0.01M NaClO4. The results suggest that the sorption and diffusion of 90Sr2+in compacted bentonite decreases with increasing the density of compacted bentonite. The presence of FA enhances the sorption of Sr2+, but reduces the diffusion of Sr2+in compacted bentonite. The porosity of the compacted bentonite plays an important role in the sorption and diffusion behavior of 90Sr2+. Using the calculated effective diffusion coefficients the long-term relative concentration distribution of strontium was evaluated in compacted bentonite.

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In 1951, unsaturated prairie soil was contaminated with fission products and actinides. Fifty years later, in 2001, soil samples were collected from the contaminated site. This paper describes the techniques used to analyze these samples, including gamma-spectroscopy (GS) for 137Cs, neutron activation analysis (NAA/GS) for 238U, liquid scintillation counting (LSC) for 90Sr and inductively coupled plasma mass spectroscopy (ICP-MS) for 238U and 113mCd. As expected, ICP-MS was found to have the lowest detection level, while the techniques were ranked in order of increasing uncertainty as GS, NAA/GS, ICP-MS and LSC.

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