A hydrotalcite-supported platinum (Pt/HT) catalyst was found to be a highly active and selective heterogeneous catalyst for glycerol oxidation in pure water under atmospheric oxygen pressure in a high glycerol/metal molar ratio up to 3125. High selectivity toward glyceric acid (78 %) was obtained even at room temperature under air atmosphere. The Pt/HT catalyst selectively oxidized the primary hydroxyl group of 1,2-propandiol to give the corresponding carboxylic acid (lactic acid) as well as glycerol. The activity of the catalyst was greatly influenced by the Mg/Al ratio of hydrotalcite. Glycerol conversion increased with increasing the Mg/Al ratio of hydrotalcite (from trace to 56 %). X-ray absorption fine structure (XAFS) measurements indicated that the catalytic oxidation activity was proportional to the metallic platinum concentration, and more than 35 % of metallic platinum was necessary for this reaction. TEM measurements and titration analysis by using benzoic acid suggested that the solid basicity of hydrotalcite plays important roles in the precise control of platinum size and metal concentration as well as the initial promotion of alcohol oxidation.

The fracture toughness and resistance-curve behavior of relatively coarse-scale, niobium/niobium aluminide (Nb/Nb 3 Al) laminated composites have been examined and compared to other Nb/Nb 3 Al composites with (in situ) Nb particulate or microlaminate reinforcements. The addition of high aspectratio Nb reinforcements, in the form of 20 vol. pct of 50-to 250-m-thick layers, was seen to improve the toughness of the Nb 3 Al intermetallic matrix by well over an order of magnitude, with the toughness increasing with Nb layer thickness. The orientation of the laminate had a small effect on crack-growth resistance with optimal properties being found in the crack arrester, as compared to the crack divider, orientation. The high fracture toughness of these laminates was primarily attributed to large (ϳ1-to 6-mm) crack-bridging zones formed by intact Nb layers in the crack wake; these zones were of sufficient size that large-scale bridging (LSB) conditions generally prevailed in the samples tested. Resistance-curve modeling using weight function methods permitted the determination of simple approximations for the bridging tractions, which were then used to make smallscale bridging (SSB) predictions for the steady-state toughness of each laminate.

In this study, a sulfonated oxidized activated carbon (SO 3 H-OAC) catalyst was prepared through oxidation of activated carbon (OAC) followed by sulfonation and characterized by different characterization techniques such as FTIR, Pyridine-FTIR, XRD, TPD-NH 3 /CO 2 , BET, TGA, Raman, and elemental analysis. The as-synthesized SO 3 H-OAC catalyst bearing sulfonyl hydroxide (−SO 3 H), hydroxyl (−OH), and carboxyl (−COOH) functional groups with strong Brønsted base and acid sites could demonstrate an excellent bifunctional activity in conversion of glucose into 5-hydroxymethylfurfural (HMF) in a biphasic THF/H 2 O-NaCl solvent system (3:1 v/v), achieving almost 93% HMF yield and selectivity at 160 °C in 3 h. The catalyst could also show a remarkable recyclability and was used for 5 recycles without substantial loss in catalytic activity. A comprehensive mathematical model was also developed to evaluate the consecutive conversion of glucose, and respective kinetic parameters were identified by an inverse modeling technique using COMSOL Multiphysics software. Based on numerical modeling, activation energies of 54.6 and 26.6 kJ/mol were respectively achieved for glucose isomerization to fructose and consecutive fructose dehydration to HMF, signifying that fructose could convert into HMF more readily than glucose.

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