Processes to produce superconducting Nb3Sn powders from Nb-Sn oxide

The superconducting compound Nb₃Sn was produced by the reduction of the oxides or hydroxides of niobium and tin. The procedure consists of the following three steps; (i) preparation of the mixed oxides or hydroxides, (ii) direct alloy reduction, and (iii) homogenizing heat treatment of the reduced metal powders. For mixing the two oxides, two methods were tried: the simultaneous precipitation from the aqueous solution and the solidification of the molten oxides. These mixed oxides were reduced by ca!ciunn or magnesium vapour in the temperature range 973 to 1373 K. After calcium or magnesium oxide was removed by leaching the fine compound powder had an A-15 type crystal structure, but showed a relatively low superconducting critical temperature (T _c). The isothermal annealing improvedT _c to 18.0 K.     

Improved heat and solvent resistance of a pressure‐sensitive adhesive thermally processable by isocyanate dimer dissociation

Methods that do not involve use of an organic solvent are being considered for manufacturing environmental‐friendly pressure‐sensitive adhesive tapes. Among these methods, the hot‐melt method exhibits high productivity but is somewhat limited in terms of performance. Hot‐melt‐fabricated pressure‐sensitive adhesives require heating fluidization and cooling solidification, and it is extremely difficult to improve their heat resistance. We examine thermally processable pressure‐sensitive adhesives with a completely new structure, fabricated based on the thermal dissociation of the isocyanate dimer. This enables thermal processing of materials softened by thermal dissociation. Fabrication of crosslinkable pressure‐sensitive adhesive becomes possible through a reaction of isocyanate caused by dissociation of its dimer. It is found that improving thermal and solvent resistances, which are disadvantages associated with conventional hot‐melt pressure‐sensitive adhesives, is potentially possible with the pressure‐sensitive adhesive reported here. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41444.     

Water vapor solubility of poly(lactic acid) films modified the surface by vacuum ultraviolet irradiation

Surface modification of poly(lactic acid) (PLA) film is performed via 172 nm excimer lamp irradiation. Effects on water vapor solubility and physical properties via vacuum ultraviolet (VUV) irradiation are studied systematically. After VUV irradiation, water vapor solubility increases approximately 11–43% in the low‐pressure region and approximately 20–38% in the high‐pressure region as surface hydrophilicity increased. The increase is attributed to hydrogen bonding with the carboxyl groups because of VUV radiation. The modified layer is significantly swelling after water vapor sorption. The hydrophilic layer forms a thickness of 2–3 μm from the irradiated surface via VUV radiation, but no changes are observed inside the irradiated film. Therefore, PLA film solubility after irradiation is enhanced by hydrophilicity and the swelling effect of the surface. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42200.     

Highly unsaturated fatty acid might act as an antioxidant in emulsion system oxidized by azo compound

Now it is recognized that DHA is oxidatively stable fatty acid compared with linoleic acid (LA) in emulsified system, although DHA is oxidatively unstable in a bulk system. In fact, an emulsified mixture of DHA and LA behaves as in a bulk system, namely the oxidative stability of DHA becomes lower than that of LA. Therefore, in this study, tridocosahexaenoate (DDD) and glycerol trilinoleate (LLL) were separately emulsified using TritonX-100 as an emulsifier and DDD emulsion was mixed with the oxidizing LLL emulsion using a water-soluble radical initiator, 2,2'-azobis(2-aminopropane) dihydrochloride. As a result, DHA suppressed the oxidation of LA, while DHA was not significantly oxidized. This suppression ability was examined using glycerol trieicosapentaenoate, glycerol trilinolenate, or glycerol trioleate instead of DDD and it was found that this activity was increased with the increasing number of double bonds in the structure. Furthermore, the same type of experiment was carried out using a lipid-soluble radical initiator, 2,2'-azobisisobutyronitrile and the similar result was obtained. These results indicated that a highly polyunsaturated fatty acid might act as an antioxidant in an emulsion system oxidized by an azo compound.     

Antioxidant Effects of Herbal Tea Leaves from Yacon (Smallanthus sonchifolius) on Multiple Free Radical and Reducing Power Assays,Especially on Different Superoxide Anion Radical Generation Systems

Yacon (Smallanthus sonchifolius), a native Andean plant, has been cultivated as a crop and locally used as a traditional folk medicine for the people suffering from diabetes and digestive/renal disorders. However, the medicinal properties of this plant and its processed foods have not been completely established. This study investigates the potent antioxidative effects of herbal tea leaves from yacon in different free radical models and a ferric reducing model. A hot‐water extract exhibited the highest yield of total polyphenol and scavenging effect on 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH) radical among four extracts prepared with hot water, methanol, ethanol, and ethylacetate. In addition, a higher reducing power of the hot‐water extract was similarly demonstrated among these extracts. Varying concentrations of the hot‐water extract resulted in different scavenging activities in four synthetic free radical models: DPPH radical (EC₅₀ 28.1 μg/mL), 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) cation radical (EC₅₀ 23.7 μg/mL), galvinoxyl radical (EC₅₀ 3.06 μg/mL), and chlorpromazine cation radical (EC₅₀ 475 μg/mL). The yacon tea‐leaf extract further demonstrated superoxide anion (O₂^?) radical scavenging effects in the phenazine methosulfate‐NADH‐nitroblue tetrazolium (EC₅₀ 64.5 μg/mL) and xanthine oxidase assay systems (EC₅₀ 20.7 μg/mL). Subsequently, incubating human neutrophilic cells in the presence of the tea‐leaf extract could suppress the cellular O₂^? radical generation (IC₅₀ 65.7 μg/mL) in a phorbol 12‐myristate 13‐acetate‐activated cell model. These results support yacon tea leaves may be a good source of natural antioxidants for preventing O₂^? radical‐mediated disorders.     

Effect of cellular inositol content on ethanol tolerance of Saccharomyces cerevisiae in sake brewing

The effect of cellular inositol content on the ethanol tolerance of sake yeast was investigated. In a static culture of strain K901 in a synthetic medium, when cells were grown in the presence of inositol in limited amount (L-cells), the inositol content of cells decreased by one-third that of cells grown in the presence of inositol in sufficient amount (H-cells). L-cells exhibited a higher death rate constant than H-cells in the presence of 12-20% ethanol, while no difference in specific ethanol production rate in the presence of 0-18% ethanol between the two cell types was observed. L-cells leaked more intracellular components, such as nucleotides, phosphate and potassium, in the presence of ethanol than H-cells. L-cells exhibited a lower intracellular pH value than H-cells, which represented the lowering of cell vitality by the decrease in H(+) extrusion activity. Furthermore, the plasma membrane H(+)-ATPase activity of L-cells was approximately one-half of that of H-cells. Therefore, it was considered that the decrease in viability in the presence of ethanol due to inositol limitation results from the lowering of H(+)-ATPase activity, which maintains the permeability barrier of the yeast membrane, ensuring the homeostasis of ions in the cytoplasm of yeast cells. It is assumed that the lowering of H(+)-ATPase activity due to inositol limitation is caused by the change in lipid environment of the enzyme, which is affected by inositol-containing glycerophospholipids such as phosphatidylinositol (PI), because in the PI-saturated mixed micellar assay system, the difference in H(+)-ATPase activity between L- and H-cells disappeared. In the early stage of sake mash, inositol limitation lowers the ethanol tolerance due to the decrease in H(+)-ATPase activity as in static culture. In the final stage of sake mash, the disruption of the ino1 gene responsible for inositol synthesis, resulted in a decrease in cell density. Furthermore, the ino1 disruptant, which was not capable of increasing the cellular inositol level in the final stage, exhibited a significantly higher methylene blue-staining ratio than the parental strain. It was suggested that the yeast cellular inositol level is one of the important factors which contribute to the high ethanol tolerance implied by the increased cell viability in the presence of ethanol.     

K(ATP) channels contribute to the cardioprotection of preconditioning independent of anaesthetics in rabbit hearts

The contribution of ATP sensitive potassium (K(ATP)) channels to the infarct-size limiting effect of preconditioning is considered to be anaesthetic-dependent in the rabbit heart. It has previously been reported that ischaemic preconditioning prevents ischaemia-induced reductions in activities of sarcolemmal adenylate cyclase (AC) and Na+, K(+)-ATPase. Anaesthetic dependency of the role of K(ATP) channels in the preservation of these enzyme activities, induced by ischaemic preconditioning, as well as that induced by activation of A1-adenosine receptors, was examined in rabbits anaesthetized with either pentobarbital or ketamine-xylazine and subjected to 20 min of regional ischaemia. Adenylate cyclase and Na+, K(+)-ATPase activities were lower in the ischaemic than in the non-ischaemic region of the hearts in control rabbits, but not in animals subjected to ischaemic preconditioning, or those pretreated with the A1-adenosine receptor agonist R(-)-N6-(2-phenylisopropyl) adenosine. The protective effects of both ischaemic preconditioning and A1-adenosine receptor activation were prevented by 6 mg/kg, but not 3 mg/kg, of the K(ATP) channel blocker, glibenclamide, in rabbits anaesthetized with pentobarbital, while these effects were prevented by 3 mg/kg of the blocker in rabbits anaesthetized with ketamine-xylazine. Moreover, K(ATP) channel opener, cromakalim, prevented the ischaemia-induced decreases in enzymatic activities in rabbits subjected to either type of anaesthesia. Thus, although the antagonistic effect of glibenclamide is blunted under pentobarbital, compared to ketamine-xylazine anaesthesia, K(ATP) channels contribute to preservative actions independent of the type of anaesthesia in the rabbit heart.     

The effect of small dose of topiroxostat on serum uric acid in patients receiving hemodialysis

Introduction : Topiroxostat, a recently developed xanthine oxidase inhibitor, is expected to have fewer adverse effects than allopurinol because it has different mechanism of action from alloprinol. However, its dosage, usage and safety have not been established in patients with impaired renal function or those undergoing dialysis at the development since no studies was conducted in these patients. Methods : Cross over clinical trial using 3 months of allopurinol and topiroxostat on 27 maintain Japanese HD patients were carried out. The effects on oxidative stress status of both drugs were also evaluated by measuring oxidation reduction potential. Findings : Twenty‐five of twenty‐seven patients completed study. The mean serum uric acid levels in the topiroxostat‐treated arm was significantly lower than it in the allopurinol‐treated arm time‐dependently (P < 0.0001). Corrected oxidative stress ratio defined as biological antioxidant potential/diacron reactive oxygen metabolites was significantly increased in topiroxostat‐arm (*P = 0.0035), but not in allopurinol‐arm (P = 0.1429). No significant difference was seen in diacron reactive oxygen metabolites, biological antioxidant potential, static oxidation‐reduction potential, and capacity oxidation‐reduction potential between pre and post treatment of both drugs. Discussion : It is suggested that a low dose of topiroxostat decreased serum uric acid sufficiently to maintain it below 7.0 mg/dL in patients receiving hemodialysis.