A new way of preparing Y–Ba–Cu–O (YBCO) high-temperature superconducting (HTSC) materials has been developed using the sol–gel processing technique based on new and convenient precursors that are stable in air and have high compatibility with each other. For the preparation of HTSC materials, instead of unstable copper alkoxides, the use of chelate type copper compounds as highly effective and stable precursors has been suggested. These have been prepared by the reaction of copper hydroxide with the corresponding (mono, di, tri)ethanolamines. A new method of preparing yttrium precursors on the basis of coordination acetylacetonate type polymer has been suggested. A reaction with bidentate type complex forming solvents such as 2-alkoxyethanols results in the formation of the complex type yttrium alkoxides. Superconducting YBCO ceramic materials have been developed, both films (applied on yttrium stabilized zirconia) and powders, using the sol–gel method based on the new yttrium and copper precursors. X-ray and thermal analyses of the synthesized materials have been carried out. The transition temperature into the superconducting state, T(0)c, and the temperature interval of this transition, ΔT, have been found to be T(0)c = 84 and 88 K and ΔT = 4 and 3 K for YBa2Cu3O7−x bulk ceramics and thin films, respectively.

Two cystatins were purified from tissue extract of bovine brain by alkaline treatment, acetone fractionation, gel chromatography on Sephadex G-75, and affinity chromatography on S-carboxymethyl-papain-Sepharose. One of the inhibitors had a relatively high molecular mass, 25 kDa (HMM-cystatin) with pI 4.7, and the other, 11 kDa (LMM-cystatin) with pI 5.23. Both inhibitors showed considerable stability at pH 2 and 80 degrees C. The cystatins inhibited papain, ficin, and cathepsins B and H, but not trypsin, chymotrypsin, thermolysin, nagarse, and cathepsin D. Ki values for the complexes of papain and the inhibitors were estimated to be 2.8 x 10(-10) M for HMM-cystatin and 1.3 x 10(-9) M for LMM-cystatin. Both purified cystatins prevented degradation of substance P by soluble fraction and lysosomal extract obtained from synaptosomes, but did not suppress the cleavage of the peptide by synaptosomal plasma membranes.

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225ChemInform Abstract Propargyl alcohol (I) reacts with vinyl-or phenylethynylcarbinol (II) in the presence of a mercury-boron fluoride catalyst to give the 1,4-dioxane derivatives (III). (NMR-, IR-data).