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141.
The effect of the oxygen content (\(C_{O_2 } \)) in the gas mixture (20% of SiH4 + 80% of Ar) + O2 and the surface area of an erbium target (SEr) on the composition and Er3+ photoluminescence of amorphous a-SiOx:(H, Er, O) films prepared by dc magnetron sputtering has been investigated. Analysis of the experimental data shows that [Er-O] and [Er-O-Si-O] clusters are formed in the gas plasma due to the competing processes of oxidation and sputtering of Si and Er targets and to the interaction of [Si-O] and [Er-O] clusters with each other and with the oxygen in the gas phase. The discontinuities in the dependences of the contents of erbium-bound oxygen and erbium in a film, and N O Er-O and NEr = f(\(C_{O_2 } \), SEr), at \(C_{O_2 } \) ≈ (5–6.5) mol % supports the hypothesis on the existence of different erbium clusters. The necessary conditions for preparing a-SiOx:(H, Er, O) films with the highest photoluminescence intensity of erbium ions at a wavelength of 1.54 μm are determined. 相似文献
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143.
Kinetics of free radical lipid peroxidation, induced by Fe2+ in presence of ascorbic acid, was studied in phospholipid membranes. The maximal rate of peroxidative oxidation was observed at 2.5 muM concentration of Fe2+, in this case a half of the maximal amount of peroxidative oxidation products was formed within 20-30 min at 20 degrees and at 200 muM concentration of ascorbic acid. The rate of peroxidative oxidation depended on addition of substances modifying the membrane structure (linoleic acid, cetyl trimethylammonium, Tween-60, derivatives of phenothiazol). Charge of the membrane surface was shown to have a distinct effect on the peroxidative oxidation. Loosening of membranes by non-ion detergent (Tween-60) increased the rate of the process, whereas the increase of the membranes rigidity by cholesterol did not cause any effect. Uneffectiveness of cholesterol is discussed with relation to diffusion of radicals, participating in peroxidative oxidation, from depth of the membrane to its surface and in the opposite direction. 相似文献
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149.
The ultrastructure of superficial cells of the normal human cervical squamous epithelium and that in leukoplakia was examined by scanning and transmission electron microscopy. The characteristic appearance of normal cells is described. Changes in the concentration of tonofilaments and formation of keratohyalin granules were revealed in leukoplakia. Alterations in surface microridges were also observed. The latter phenomenon is closely related to a decrease in the number of tonofilaments at the cell periphery. It is possible that the altered microridges do not retain the cushioning protective mucin and maintain the stationary of progressive states of leukoplakia. 相似文献
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