Vol.4,

The nodular cast iron samples were prepared with the normal nodularizing process, in which the important antinodularizing elements Pb, Bi and Al were added respectively in order to research the influence of them on the nodularization of the graphites. The nodular graphites were extracted from the nodular cast iron by the electrolytic technique. The distribution of trace elements in nodular and deformed graphite were measured by Scanning Proton Microprobe (SPM). Most of the adding elements Pb, Bi and Al existed in matrix as impurities, a part of them intruded into the nodular graphites. A new suggestion of Ti antinodularizing properties had been proposed. The influence of Pb, Bi and Al on the nodularization was indirectly performed through Ti. Therefore, Ti is one of the most important antinodularizing elements.

423

A study on the behavior of p, p'-DDT in flooded soil was conducted from 1990 to 1991. ¹⁴C-p,p'-DDT was used as a tracer. TLC, ARG techniques were used. A chromatography scanner was used to determine the radioactivity in spots of TLC plates. The behavior of DDT in flooded soil is different from that in upland soil. The dissipation of DDT was faster, DDT and its metabolites moved down faster, and more radioactivity became to bound residue in flooded soil as compared with those in upland situation. In extracts, DDT, DDD, DDE, DDA and an unidentified product were detected and their amounts were changed with time. About 90 % of the DDT disappeared and DDD became the key component of extractable residue within 8 weeks in flooded soil, whereas DDT took about 80% of the methanol extractable residue in 43 rd week sample of upland soil.

328

Cenozoic basalts in the eastern part of Liaoning-Jilin contain abundant mantle-derived inclusions. The rock types of the ultramafic inclusions are composed mostly of spinel lherzolite and a few websterites. In order to study the origin of inclusions, the concnetrations of several trace elements have been measured in samples by NAA. According to geochemical characteristics of trace elements, there are two types of spinel lherzolite inclusions. The first type is refractory residues left after partial melting of the upper mantle and the second type is metasomatizing refractory residues. The websterites inclusions formed by segregation of basaltic melt derived from high degree of melting of mantle source rocks.

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Positron lifetimes in polyethylene glycol (PEG) polymer have been measured as a function of polymerization degree N (N = 25-500). It is observed that all the positron parameters are strongly dependent on N when N ≤ 250, and then tend to constant levels when N ≥ 250. The variations of the longest-lived component (I₃, τ₃) show that the size of free-volume holes has a minimum at N = 100 and the hole concentration deereases with N. These trends may be due to the variations in crystallinity, the chain ends, entanglements and the Van der Waals interaction between segments. The variations of the second component (I₂, τ₂) with N reflect the changes of defect properties in crystalline regions of PEG.

369

459

A technique for studying in vivo the production rate and turnover rate constant of mouse brain M-receptors was established. A single injection of 25 mg / kg of Benzilylcholine Mustard to living mice resulted in 90 % irreversible block of brain M-receptors. The time course of the receptor density was then monitored by ³H-QNB binding assay and the production rate and turnover rate constant were calculated from the time course curve with a computer program. It was found that in normal mice the turnover rate constant was about 0.035 h^-1 (half-life was about 20 h) and the production rate was 30-42 fmol / (h · mg protein). Parallel experiments revealed a significant slow down of the turnover of brain M-receptors in hypothyroid mice (turnover rate constant was 0.0257±0.0012 h^-1 in hypothyroid vs. 0.0356 ± 0.0021 h^-1 in normal) while the production rate was not changed significantly. The results suggest that thyroid hormones have a regulatory action on the turnover of brain M-receptors and the elevation of brain M-receptor density together with slow down of the turnover of brain M-receptors is probably one of the important mechanisms relevant to the brain dysfunction in hypothyroidism.

227

The heavy ion irradiation is used for the first time to simulate the radiation damage produced by reactor neutrons in home-made modified stainless steels. The produced radiation damage is investigated by the positron annihilation spectroscopy. No detectable radiation damage is observed in the home-made modified stainless steels irradiated by 81.6 MeV carbon ions to a total dose of 3.3 × 10¹⁶ cm^-2, indicating that the home-made modified stainless steel of this type has good radiation resistant properties.

215

In this paper, various kinds of monomers 2-hydroxyethyl methacrylate (HEMA). 2-hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate (HPMA) and methoxy polyethylene glycol methylacrylate (M-23G) were copolymerized by radiation technique at low temperature (-78℃) and several kinds of copolymer carriers were obtained. Yeast cells were immobilized through adhesion and multiplication of yeast cells themselves on these carriers. The ethanol productivity of immobilized yeast cells with these carriers was related to the monomer composition and water content of copolymer carriers and the optimum monomer composition was 20%:10% in poly (HEA-M23G). In this case, the ethanol productivity of immobilized yeast cells was 26 mg/( ml·h), which was 4 times as high as that of free cells. In this study, the effect of adding of crosslinking reagent (4G) in copolymer on activity of yeast cells immobilized with the carriers were also studied. It was found that the effect of adding crosslinking reagent (4G) in lower monomer composition of poly(HEA-M23G) on the ethanol productivity of immobilized cells was better than that in higher one in this work.

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398

In this paper Al₂O₃ and MgO were studied as targets for the radiation grafting of MAA by electron beams. The reaction conditions and materials were characterized by IR spectroscopy, Scanning electron microscopy, X-ray diffraction methods. It is concluded that grafting copolymerization of inorganic oxides and organic monomers has been confirmed. We focus our attention on using ESR spectrum to study the effects of ionizing radiation on inorganic oxides and the properties of initiating active centers. In addition, the radiation grafting mechanism of inorganic oxides and organic monomers has been primarily investigated.

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