An improved error bound for a finite element approximation of a model for phase separation of a multi-component alloy

Using the approach of Rulla (1996 SIAM J. Numer. Anal. 33, 68-87)for analysing the time discretization error and assuming moreregularity on the initial data, we improve on the error boundderived by Barrett and Blowey (1996 IMA J. Numer. Anal. 16,257-287) for a fully practical piecewise linear finite elementapproximation with a backward Euler time discretization of amodel for phase separation of a multi-component alloy.     

Crystal face specificity of nitrogen adsorption on a platium field emission tip

The adsorption of nitrogen on platinum is studied with a field emission microscope equipped with a probe-hole assembly to enable quantitative emission measurements on individual crystal faces. The results are implemented by photoelectric measurements on platinum films. Adsorption at 80 K is found to result in a large and face-specific decrease in the work function. On crystal planes containing B₅ and B₆ sites this decrease is larger than on those exposing B₃ and B₄ sites only. No significant crystal face specificity is found, however, for the rate of temperature programmed desorption of nitrogen. It follows that the heat of nitrogen adsorption is essentially equal for faces with B₃, B₄, B₅ and B₆ sites. This result is at variance with certain postulates in the literature.     

Rh/NaY催化剂上合成气选择一步生成乙酸

在合成气(CO+H₂)催化转化反应中,含适当助剂(如Mn、Fe、V等)的负载型Rh催化剂能够有选择地催化生成C₂含氧化合物,某些氧化物载体本身也会成为Rh催化剂的助剂^[1～3].