Trends in the ionicity in the average valence V materials

An ionicity scale is given for average valence V materials. The scale is derived via the methods of the Phillips spectroscopic theory.     

The influence of the microscopic structure of surfaces on the optical properties of metals

The review outlines the state-of-the-art in the field of studies on the optical properties of metal surfaces. The use of recent theory has been examined to explain the results obtained in certain individual experiments on the surface modulation spectroscopy, outer photoemission and the surface Raman effect. The dependence of the surface plasmon spectrum on the surface microscopic structure has been given special consideration. It has been shown how information about the electronic structure of a surface, and the effect of adsorption on this structure in particular, can be extracted from the optical measurement data.     

The QCD Pomeron with optimal renormalization

It is shown that the next-to-leading order (NLO) corrections to the QCD Pomeron intercept obtained from the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation, when evaluated in non-Abelian physical renormalization schemes with Brodsky-Lepage-Mackenzie (BLM) optimal scale setting, do not exhibit the serious problems encountered in the scheme. A striking feature of the NLO BFKL Pomeron intercept in the BLM approach is that it yields an important approximate conformal invariance. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 3, 161–166 (10 August 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

FTIR studies of collagen model peptides: complementary experimental and simulation approaches to conformation and unfolding

X-ray crystallography of collagen model peptides has provided high-resolution structures of the basic triple-helical conformation and its water-mediated hydration network. Vibrational spectroscopy provides a useful bridge for transferring the structural information from X-ray diffraction to collagen in its native environment. The vibrational mode most useful for this purpose is the amide I mode (mostly peptide bond C=O stretch) near 1650 cm-1. The current study refines and extends the range of utility of a novel simulation method that accurately predicts the infrared (IR) amide I spectral contour from the three-dimensional structure of a protein or peptide. The approach is demonstrated through accurate simulation of the experimental amide I contour in solution for both a standard triple helix, (Pro-Pro-Gly)10, and a second peptide with a Gly --> Ala substitution in the middle of the chain that models the effect of a mutation in the native collagen sequence. Monitoring the major amide I peak as a function of temperature gives sharp thermal transitions for both peptides, similar to those obtained by circular dichroism spectroscopy, and the Fourier transform infrared (FTIR) spectra of the unfolded states were compared with polyproline II. The simulation studies were extended to model early stages of thermal denaturation of (Pro-Pro-Gly)10. Dihedral angle changes suggested by molecular dynamics simulations were made in a stepwise fashion to generate peptide unwinding from each end, which emulates the effect of increasing temperature. Simulated bands from these new structures were then compared to the experimental bands obtained as temperature was increased. The similarity between the simulated and experimental IR spectra lends credence to the simulation method and paves the way for a variety of applications.