Alloy-composition-dependent oxygen reduction reaction activity and electrochemical stability of Pt-based bimetallic systems: a model electrocatalyst study of Pt/PtxNi100-x(111).

The oxygen reduction reaction (ORR) activity and electrochemical stability of well-defined n monolayer (ML)-Pt/PtxNi100-x(111) (n = 2 and 4; x = 75, 50, and 25) model electrocatalyst surfaces were investigated in this study. The initial activity of the as-prepared two-monolayered Pt-covered PtxNi100-x(111) substrates (2ML-Pt/PtxNi100-x(111)) increased with increasing Ni composition in the PtxNi100-x(111) substrate. In particular, 2ML-Pt/Pt25Ni75(111) showed the initial activity that was 25 times higher than that of clean Pt(111) although the higher Ni composition resulted in destabilization of the catalyst upon the application of potential cycles (PCs). As for 4ML-Pt/PtxNi100-x(111), activity enhancements were insensitive to alloy composition and thicker Pt shell layers stabilized the catalyst against PC applications. In particular, the activities of 4ML-Pt/Pt50Ni50(111) and 4ML-Pt/Pt25Ni75(111) gradually increased during 1000 PCs probably because of the PC-induced mono-atomic heights and nanometer-size islands that had (110) and (100) steps introduced into the topmost (111) terraces. Thus, the simultaneous tuning of core-alloy composition and Pt shell thickness is vital for developing practical, highly efficient Pt-based alloy ORR electrocatalysts.

Isolation of nebulin from rabbit skeletal muscle and its interaction with actin.

Nebulin is about 800 kDa filamentous protein that binds the entire thin filament of vertebrate skeletal muscle sarcomeres. Nebulin cannot be isolated from muscle except in a completely denatured form by direct solubilization of myofibrils with SDS because nebulin is hardly soluble under salt conditions. In the present study, nebulin was solubilized by a salt solution containing 1 M urea and purified by DEAE-Toyopearl column chromatography via 4 M urea elution. Rotary-shadowed images of nebulin showed entangled knit-like particles, about 20 nm in diameter. The purified nebulin bound to actin filaments to form loose bundles. Nebulin was confirmed to bind actin, alpha-actinin, beta-actinin, and tropomodulin, but not troponin or tropomyosin. The data shows that full-length nebulin can be also obtained in a functional and presumably native form, verified by data from experiments using recombinant subfragments.

Suppressive effects of whey protein hydrolysate on sucrose-induced hyperglycemia in silkworms.

Silkworms are useful for evaluating substances that suppress postprandial hyperglycemia by oral administration. In this study, orally administered whey protein hydrolysate (WPH), obtained by enzymatic treatment of whey protein, suppressed sucrose-induced hyperglycemia in silkworms in a dose-dependent manner. WPH also inhibited glucose-induced hyperglycemia in silkworms. These findings suggest that WPH contains a bioactive peptide that inhibits glucose uptake from the intestinal tract and thereby suppresses sucrose-induced hyperglycemia.