Oxygen-free Medium Research Articles

(ZnCd)S, (ZnCd)Se and Zn(SeTe) downconverting phosphors

The efficiency of (ZnCd)S, (ZnCd)Se and Zn(SeTe) solid solutions, doped with copper and chlorine, as x-ray downconverting phosphors for photodetectors is investigated. It is found, that the phosphors based on the solid solutions of the group II-VI wide-bandgap compounds and prepared in oxygen-free medium, can increase the photodetectors sensitivity to x-ray radiation more than one order of magnitude and enhance the detectors photocurrent versus radiant flux characteristics linearity.

Group II-VI Downconverting Phosphors

ABSTRACTThe efficiency of group II-VI solid solutions doped with chlorine and copper as X-ray downconverting phosphors for photodetectors is investigated. It is found that the phosphors based on the group II-VI compounds and prepared in oxygen-free medium can increase the photodetectors sensitivity to X-ray radiation more than one order of magnitude and enhance the photodetectors photovoltage versus X-ray radiant flux characteristic linearity.

Evidence for stimulation of the K-Cl cotransport system by phenazine methosulfate

The effects of phenazine methosulfate (PMS), a known generator of oxygen free radicals, on ion transport in human erythrocytes were studied. The treatment of the red blood cells with 0.1–0.8 mM PMS caused the concentration-dependent increase of K loss from the cells in K-free sodium chloride medium. The PMS-dependent K efflux from the cells in oxygen-free medium, being in equilibrium with argon, did not differ from the control. After substitution of Cl − ions in the medium by NO 3 −, PMS caused only a small activation of K loss. PMS at a concentration of 0.8 mM was found to increase passive K transport in erythrocytes (ouabain-furosemide-resistant 86Rb influx) and at the same time to decrease active transport of K (ouabain-sensitive influx of 86Rb). Furosemide-sensitive cotransport of K was not affected by 0.8 mM PMS. The influx of 22Na in the red blood cells was also independent of the presence of 0.2–1.0 mM PMS in the bath medium. The results obtained suggest that PMS stimulated the reversible K-Cl cotransport in human erythrocyte membranes. This effect of PMS resembles the action of the well-known SH-alkylating agent, N-ethylmaleiroide.

Effects of anoxia and inhibitors of energy metabolism on potassium and sodium homeostasis in neurons of gastropod mollusk

The effect of anoxia and inhibitors of energy metabolism on intracellular concentrations of potassium and sodium, membrane potentials, permeability, active and passive ouabain-sensitive transport of potassium (determined with86Rb) was studied in neurons of the freshwater planorbis mollusk (Planorbarius corneus). X-ray microanalysis showed that incubation of isolated ganglia in oxygen-free medium induced no change in intracellular concentrations of potassium and sodium. In the presence of cyanide, absorption of oxygen by the ganglia ceased, but accumulation of86Rb decreased insignificantly. The membrane potential and permeability did not depend on addition of cyanide. Desoxyglucose, an inhibitor of glycolysis, decreased86Rb accumulation more than cyanide did. In the presence of inhibitors of both glycolysis and respiration, which excluded the possibility of mutual compensation of oxidation and glycolytic sources of energy supply,86Rb accumulation decreased to the highest degree. A hypothesis was formulated on the paramount importance of glycolytic ATP for maintaining ion homeostasis of the nerve cells. The problem of functionally facilitated compartmentation of intracellular energy sources is discussed.

Developmental changes in energy metabolism ofSchistosoma mansoni and physiological role of oxygen in maintaining parasite function

The time course of the conversion from a cyanide-sensitive to a cyanide-insensitive energy metabolism in immatureSchistosoma mansoni was followed by correlating transitions in CO2 and lactate formation with physiological properties of the parasite. Volume conducted electrical potentials and measurement of CO2 evolution indicate that 3-hr posttransformational schistosomula are highly sensitive to 1 mM cyanide. By 24 hr after transformation, evolution of CO2 under control conditions is reduced by 77% from 3-hr levels, while lactate excretion rises by 84%. At the 24-hr stage, neither cyanide nor rotenone affects the frequency or magnitude of endogenous electrical transients, but cyanide does eliminate 83 % of the already reduced levels of CO2 evolved in 24-hr schistosomula. The adult parasite evolves a low level of CO2 which is reduced by 88% in the presence of 1 mM cyanide. No significant Pasteur effect is detected, however, and endogenous electrical activity as well as mechanical responses of the adult musculature are unaffected by cyanide exposure. Furthermore, adult schistosomes were not adversely affected in terms of the physiological parameters measured by 24-hr incubations in oxygen-free medium. Adults were only marginally affected by 24-hr exposure to several respiratory inhibitors, but responded rapidly to some uncouplers of oxidative phosphorylation, including 2,4-DNP, carbonyl cyanide 3-chlorphenylhydrazone, and closantel. Our results indicate that schistosomula continue to rely on cyanide-sensitive respiratory components for at least 3 hr after transformation; by 24 hr, however, the parasites are metabolically similar to the adult stage, i.e, they depend on lactate fermentation for most of their energy requirements.

Selectivity and depth of microbial plugging in Berea sandstone cores

The depth of plugging by the in situ growth of either injected or indigenous microorganisms was investigated using Berea sandstone cores with pressure taps located along the length of the core. The continuous injection of aerobically prepared sucrose-mineral salts medium with 5% NaCl and 0.1% NaNO3 resulted in large permeability reductions (70–98%). The plugging was localized at the inlet and outlet faces of the cores, and was attributed to microbial biomass production at the inlet face and biogas accumulation at the outlet face. Batch addition of aerobic medium resulted in more uniform permeability reduction along the core's length, but the magnitude of the permeability reduction was not as large (about 65%). The semi-continuous injection of oxygen-free medium resulted in a slower but a more uniform permeability reduction throughout the core compared to cores which received aerobically prepared medium. The selectivity of the process was investigated in a dual core system where two cores of 240 and 760 mdarcy permeability were connected parallel to each other without crossflow. Initially, about 85% of the total fluid flow passed through the high permeability core. After the addition ofBacillus species and medium, the flow pattern changed and about 85% of the total fluid passed through the low permeability core. These results show that the in situ growth of microorganisms can selectively plug high permeability zones and that control of the process may be achieved by alterations in the method of nutrient injection.

Intermembrane inclusions induced by anoxia in heart and skeletal muscle mitochondria.

Heart and skeletal muscle from rats of different ages were incubated in vitro in an oxygen-free medium supplied with substrates in order to investigate the effect of anoxia on muscle fine structure, particulary on the mitochondria. In skeletal muscle fibers anoxia has been found to induce changes similar to those previously described in ischemic muscles in vivo namely giant mitochondria, apparently derived by mitochondrial fusion, and intermembrane inclusions with a paracrystalline structure. The plate-like inclusions are mostly located in the intracristal spaces and are closely associated to cristal membranes even in markedly swollen mitochondria. Identical inclusions have been observed in cardiac muscle cells following anoxic injury, whereas they are never found in non-muscle cells such as endothelia, fibroblasts and nerve fibers. Cardiac and skeletal muscle fibers from newborn rats maintained in an oxygen-free medium show mitochondrial swelling but no intermembrane inclusions. The different response of mitochondria from developing vs adult striated muscle to anoxia may be due to changes during postnatal development in the quality or quantity of the protein component(s) involved in paracrystal formation.

Amination of 5-azacinnoline with aromatic amines

The 5-azacinnoline molecule was subjected to quantum-mechanical calculation by the Huckel method. The formation of 4-amino derivatives in the case of the reaction of 5-azacinnoline with aliphatic amines in the presence of an oxidizing agent and of 4,4′-bis(5-azacinnolinyl) in the case of dimerization in an oxygenfree medium was substantiated theoretically. The possibility of reactions with anions of aromatic amines was predicted by means of the Klopman method. It is shown that, in practice, the reaction is actually accelerated and that, in conformity with theory, the reaction center is the nitrogen atom of the aromatic amine. Possible products involving reaction with the participation of the pcarbon atom of the arylamine were not recorded. As in the case of aliphatic amines, the formation of a dimer was observed in an oxygen-free medium. The structures of the compounds obtained were proved by means of a combination of physicochemical methods.

Intermediate complexes in oxidation reactions catalyzed by Rh(I) compounds

1. Paramagnetic Rh(II)O2− and Rh(II)RO2complexes of similar structure are formed in solutions containing triphenylphosphine Rh(I) complexes, both in the presence of O2 and in the presence of a hydroperoxide in an oxygen-free medium. 2. Addition of a hydroperoxide promotes coordination of the Rh(I) compound with both oxygen and RO2.. 3. The Rh(II)RO2 complexes coordinate olefins. 4. The effectiveness of the hydroperoxides in oxidational olefin isomerization can be correlated with the ability to oxidize Rh(I) to Rh(II).

Gamma-Radiolysis of Aqueous Solution of Histidine

The dependence of Gi(-M) values of histidine on the concentration of irradiated 10(-4) - 10(-1)M solutions, pH and the presence of O2, N2O and sec-butyl alcohol was investigated. In oxygen-free medium the maximum radiation sensitivity of histidine was found at pH 5--8; in oxygenated solutions it was shifted to the 6--1 pH range. The formation of radiation products was also studied. The course of radiation decomposition of histidine depends on the presence of oxygen and on the pH of irradiated solution.

ねり製品の保藏の研究-III

Various experiments have been conducted to prolong storage time of fish-cake by the helpof chemical preservatives, such as nitrofurazone, dehydro-acetic acid and hydrogen peroxide etc, however, there were found too much difficulties left unsolved to apply them directly for daily practice of the industry. E. NOGUCHI and S. HIGASA reported certain packaging materials are useful for the purpose of fish-cake preservation and stated that non-sugard fish-cake stuffed in polyethylene or vinyl chloride casing showed neither bacterial slime on their surface nor putrefactive odor after 7 day's storage. In the present report, also the results of several experiments concerning the preserving effect of plastic casing for fish-cakes are described. As will be seen in Table 1, very little increase in the amounts of volatile basic nitrogen, an index of spoilage, were found for non-sugared fish-cake which had been stuffed in polyethylene casing during 5 day's storage at 30°C. Also similar results, as shown in Table 2, has been obtained for non-sugared fish-cake which was stored under anaerobic condition by eliminating oxygen from the medium with al kaline pyrogallol solution. On the basis of above findings, it will be inferred that preservative effect due to plastic casing for fish-cake is chiefly dependent upon the extent of airtightness which can be attained when fish-cake is stuffed in these casing. But addition of some fermentable sugars was found to be as inadequate for the preservation of fish-cake by plastic casing, because such glucose and sucrose are known as very favorable carbohydrate source for accelerating the growth of some kinds of micro-organisms under anaerobic condition. Therefore, in the case of sugared fish-cake, sole use of plastic casing or keeping in oxygenfree medium is not enough to expect complete preservation of the products. Much production of lactic acid was observed for both samples of sugar added fish-cakes, which were preserved in polyethylene casings or under anaerobic condition. It is not so easy to avoid putrefaction of these sugared fish-cake products only by the aid of plastic casings. E. F. GALE has already proved that occurrence of amino acid decarboxylation is likely assisted by the growth of micro-organisms under acidic enviroment. Much amounts of lactic acid produced and decrease is pH value of the product could be pointed out as the features of progress in putrefaction of sugar containing fish-cake products. Meanwhile, in the course of spoilage of sugared fish-cake no appreciable increase in the amount of histamine was detected by colorimetry of diazo reaction, after isolating histamine with cotton acid succinate. Moreover, in the sample of fish-cake added l00mg per cent of histidine, histamine could not be produced in measurable amount as shown in Table 7.