Characterization of Al2O3-ZrO2 mixed oxide catalytic supports prepared by the sol-gel method

A series of Al₂O₃-ZrO₂ mixed oxides was prepared by the sol-gel method with variable amounts of ZrO₂ between pure alumina and pure zirconia. Textural, bulk and surface characterization of the samples was carried out by nitrogen physisorption (S_BET, porosity), surface acidity, zero point charge (ZPC), thermal analysis (DSC, TGA), X-ray diffraction (XRD) and FT-Raman spectroscopy. The textural results show that at low zirconia contents, higher surface areas than those of pure alumina are obtained, and that the mixed oxides samples show a bimodal pore size distribution different from that of a mechanical mixture of the pure oxides. Also, in the zirconia-rich samples, higher surface areas than for pure zirconia are stabilized. The ZPC results indicate the formation of a surface composition equivalent to the bulk composition of the two oxides. The acidity measurements show that, as the density of acid sites in the mixed oxides increases steadily with zirconia content, a sharp increase is observed between the zirconia-rich mixed oxides and the pure ZrO₂. It appears possible then to tune the acidity of the mixed oxide by changing its composition. The XRD and FT-Raman results show that the incorporation of alumina in the support stabilizes the metastable cubic and tetragonal zirconia phases, possibly by a matrix effect which constrains the size of the ZrO₂ particles below the critical size beyond which the crystallization and transformation process to a more stable zirconia phase occurs.     

Solid Fuel Combustion Wastes at CHPP in the Arctic Zone of the Russian Federation: Utility in Eco-Geopolymer Technology

Glass and Ceramics - A complex of physicochemical studies was conducted: chemical analysis, x-ray phase analysis, differential thermal analysis, microstructure analysis of ash-slag waste (ASW) from...     

Recombinant Cathepsin L of Tribolium castaneum and Its Potential in the Hydrolysis of Immunogenic Gliadin Peptides

Wheat gliadins contain a large amount of glutamine- and proline-rich peptides which are not hydrolyzed by human digestive peptidases and can cause autoimmune celiac disease and other forms of gluten intolerance in predisposed people. Peptidases that efficiently cleave such immunogenic peptides can be used in enzyme therapy. The stored product insect pest Tribolium castaneum efficiently hydrolyzes gliadins. The main digestive peptidase of T. castaneum is cathepsin L, which is from the papain C1 family with post-glutamine cleavage activity. We describe the isolation and characterization of T. castaneum recombinant procathepsin L (rpTcCathL1, {"type":"entrez-protein","attrs":{"text":"NP_001164001","term_id":"281427798","term_text":"NP_001164001"}}NP_001164001), which was expressed in Pichia pastoris cells. The activation of the proenzyme was conducted by autocatalytic processing. The effects of pH and proenzyme concentration in the reaction mixture on the processing were studied. The mature enzyme retained high activity in the pH range from 5.0 to 9.0 and displayed high pH-stability from 4.0 to 8.0 at 20 °C. The enzyme was characterized according to electrophoretic mobility under native conditions, activity and stability at various pH values, a sensitivity to various inhibitors, and substrate specificity, and its hydrolytic effect on 8-, 10-, 26-, and 33-mer immunogenic gliadins peptides was demonstrated. Our results show that rTcCathL1 is an effective peptidase that can be used to develop a drug for the enzyme therapy of various types of gluten intolerance.     

Formal methods of situational analysis: Experience from their use

The problems of sociological data and knowledge representation for the situational analysis of labour relations are described. It is suggested that the technologies for searching for empirical laws are described step by step by the JSM method for the automated generation of hypotheses using the research material that was obtained by a group of authors on two firms. Conclusions are made as to the potentialities and scope of the method.     

Binding of Kingella kingae RtxA Toxin Depends on Cell Surface Oligosaccharides,but Not on β2 Integrins

The Gram-negative coccobacillus Kingella kingae is increasingly recognized as an important invasive pediatric pathogen that causes mostly bacteremia and skeletal system infections. K. kingae secretes an RtxA toxin that belongs to a broad family of the RTX (Repeats in ToXin) cytotoxins produced by bacterial pathogens. Recently, we demonstrated that membrane cholesterol facilitates interaction of RtxA with target cells, but other cell surface structures potentially involved in toxin binding to cells remain unknown. We show that deglycosylation of cell surface structures by glycosidase treatment, or inhibition of protein N- and O-glycosylation by chemical inhibitors substantially reduces RtxA binding to target cells. Consequently, the deglycosylated cells were more resistant to cytotoxic activity of RtxA. Moreover, experiments on cells expressing or lacking cell surface integrins of the β₂ family revealed that, unlike some other cytotoxins of the RTX family, K. kingae RtxA does not bind target cells via the β₂ integrins. Our results, hence, show that RtxA binds cell surface oligosaccharides present on all mammalian cells but not the leukocyte-restricted β₂ integrins. This explains the previously observed interaction of the toxin with a broad range of cell types of various mammalian species and reveals that RtxA belongs to the group of broadly cytolytic RTX hemolysins.     

Preparation and properties of copper indium diselenide CuInSe2

Polycrystalline alloys in the Cu-In-Se ternary system of specified compositions are synthesized using an original silica apparatus designed by the authors and the temperature-time conditions also specially chosen for this synthesis. The region of existence of CuInSe₂-based solid solutions in the Cu-In-Se system, the temperature of the polymorphic transformation of the CuInSe₂ compound from the chalcopyrite modification into the sphalerite modification, and the melting temperature of the sphalerite modification are determined experimentally.