Differential sample charging in ESCA

An ESCA study of some “intermediate” conductors demonstrates a differential charging effect when the sample block is biased. The variation of the intensity and width of the peak from silver 3d electrons in silver iodide is used to show how the flux of the beam, the conductivity of the sample, the size and polarity of the bias and the grid mounting alter the effect. The results suggest that in unbiased samples differential sample charging contributes significantly to the width of peaks.     

Differential sample charging in ESCA

An ESCA study of some “intermediate” conductors demonstrates a differential charging effect when the sample block is biased. The variation of the intensity and width of the peak from silver 3d electrons in silver iodide is used to show how the flux of the beam, the conductivity of the sample, the size and polarity of the bias and the grid mounting alter the effect. The results suggest that in unbiased samples differential sample charging contributes significantly to the width of peaks.     

Squeeze flow of a power-law fluid between non-parallel plates

Squeeze flow in the gap between non-parallel circular plates of radius R is discussed. The test material is assumed to be a power-law fluid, with a no-slip boundary condition at the plates. If the mean separation between the plates is h, and the angle of inclination between the plates is ? ? h/R, the force on the plates is perturbed only at O(?²) and is increased by less than 10% if ? < 0.35h/R. A torque O(?) tends to return the plates to a parallel configuration.     

Acceleration of the GAMESS‐UK electronic structure package on graphical processing units

The approach used to calculate the two‐electron integral by many electronic structure packages including generalized atomic and molecular electronic structure system‐UK has been designed for CPU‐based compute units. We redesigned the two‐electron compute algorithm for acceleration on a graphical processing unit (GPU). We report the acceleration strategy and illustrate it on the (ss|ss) type integrals. This strategy is general for Fortran‐based codes and uses the Accelerator compiler from Portland Group International and GPU‐based accelerators from Nvidia. The evaluation of (ss|ss) type integrals within calculations using Hartree Fock ab initio methods and density functional theory are accelerated by single and quad GPU hardware systems by factors of 43 and 153, respectively. The overall speedup for a single self consistent field cycle is at least a factor of eight times faster on a single GPU compared with that of a single CPU. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

Photoelectron spectroscopic studies of the formation of hydroxyapatite films on titanium pretreated with etidronic acid

X‐ray photoelectron spectroscopy in the core and valence band region was used to study the formation of hydroxyapatite films on the surface of titanium. The approach used achieves the adhesion of hydroxyapatite by the initial formation of a thin, mainly oxide‐free, etidronate film on the metal. In this approach, it was not possible to prepare hydroxyapatite films of any reasonable thickness on the titanium surface without prior treatment with etidronic acid. Because hydroxyapatite is a principal component of teeth and bones, it is likely that the coated metals will have desirable biocompatible properties. The hydroxyapatite film showed no changes when the film was exposed to air, water, and 1 m sodium chloride solution as representative components of the environment of the film in the human body. These films formed on titanium may find application in medical implants. The thin hydroxyapatite and etidronate film on the metal show differential charging effects that caused a doubling of some of the spectral features. Copyright © 2012 John Wiley & Sons, Ltd.     

The Combined Role of Catalysis and Solvent Effects on the Biginelli Reaction: Improving Efficiency and Sustainability

The traditional Biginelli reaction is a three‐component condensation between urea, benzaldehyde and an acetoacetate ester to give a dihydropyrimidinone. An investigation into catalytic and solvent effects has returned the conclusion that the diketo–enol tautomerisation equilibrium of the dicarbonyl reactant dictates the yield of the reaction. Whereas the solvent is responsible for the tautomerisation equilibrium position, the catalyst only serves to eliminate kinetic control from the reaction. Generally, to preserve reaction efficiency and improve sustainability, bio‐derivable p‐cymene was found to be a useful solvent. The metal–enolate intermediate that results from the application of a Lewis acidic catalyst often cited as promoting the reaction appears to hinder the reaction. In this instance, a Brønsted acidic solvent can be used to return greater reactivity to the dicarbonyl reagent.