Fission of 232Th, 238U, 244Pu, 248Cm induced by Xe and Kr ions at coulomb barrier energies

Excitation functions and angular distributions have been measured for the fission of ²³²Th, ²³⁸U, ²⁴⁴Pu and ²⁴⁸Cm induced by ⁸⁶Kr and ¹³⁶Xe ions at energies in the vicinity of the Coulomb barrier. No large differences as a function of either target or projectile were found. These results suggest that the main process occuring is not Coulomb fission.     

The information matrices of the parameters of multiple mixed time series

Closed form matrix equations are given for the information matrix of the parameters of the vector mixed autoregressive moving average time series model.     

Dissociative electron transfer in donor-peptide-acceptor systems: results for kinetic parameters from a density functional/polarizable continuum model

The main structural and electronic factors playing a role in intramolecular dissociative electron transfer of a simple donor-peptide-acceptor (D-peptide-A) model have been investigated by an integrated computational protocol based on the density functional theory, its time-dependent extension, and the polarizable continuum model. Our results allow us to elucidate the electronic states involved in the process and how they are perturbed by the orientation of the donor and the acceptor with respect to the peptide chain and by the presence of the solvent. We also report a semiquantitative estimation of the rate constant governing electron transfer obtained by a direct quantum mechanical evaluation of all the terms entering the kinetic expressions based on the Marcus theory and its extensions.     

Strategies for examination of Alzheimer’s disease amyloid precursor protein isoforms

We describe a proteomics procedure using bioinformatics, immunoprecipitation, two-dimensional gel electrophoresis, Western blotting, in-gel digestion, LC–MS, MALDI–MS, and MS–MS for isolation and identification of amyloid precursor protein (APP) isoforms APP₆₉₅, APP₇₅₁, and APP₇₇₀. Retinoic acid-induced Ntera 2 cell line, derived from a human teratocarcinoma cells, was the in-vitro source of APP. Initial isolation of whole APP was performed by immunoprecipitation, using AB10, a monoclonal antibody raised to amino acids 1–17 of the β-amyloid peptide sequence, which is present in all three alpha secretase-cleaved isoforms of interest. The next stage was separation of whole APP into its isoform components by two-dimensional gel electrophoresis. Because of low APP concentrations, detection by the usual staining methods, for example Sypro Ruby, able to detect low picomole concentrations, did not enable visualisation of the isoforms. Western analysis, however, enabled primary detection of APP, because of the inherent sensitivity of antibodies raised to specific isoform regions. This initial visualization acted as a template for excision of isoforms from 2D gels, which were then subjected to peptide mass mapping. Initial theoretical digestion of each isoform revealed the presence of specific peptides, which were then used as “tags” for isoform detection.     

Deformations of 2k-Einstein structures

It is shown that the space of infinitesimal deformations of 2k-Einstein structures is finite dimensional on compact non-flat space forms. Moreover, spherical space forms are shown to be rigid in the sense that they are isolated in the corresponding moduli space.     

Impact of grain-dependent boron uptake on the electrochemical and electrical properties of polycrystalline boron doped diamond electrodes

A combination of high-resolution electrical and electrochemical imaging techniques, in conjunction with cathodoluminescence (CL), is used to investigate the electrochemical behavior of oxygen-terminated highly doped polycrystalline boron doped diamond (BDD). The BDD has a dopant density approximately 5 x 10(20) atoms cm(-3), grain size ca. 5-40 microm, and thickness 500 microm. CL imaging demonstrates that boron uptake is nonuniform across the surface of BDD, and conducting atomic force microscopy (C-AFM) highlights how this impacts on the local conductivity. While C-AFM shows no evidence for enhanced grain boundary conductivity, two characteristic conductivity domains are found with resistances of ca. 100 kOmega and ca. 50 MOmega. With the use of scanning electrochemical microscopy (SECM), local heterogeneities are also observed in the electroactivity of the BDD surface, consistent with the two different types of conducting regions. Local currents of the magnitude expected for metal-like behavior are observed in some regions, suggesting degenerative doping of the grains (supported by CL studies). In other regions, slower electron transfer is apparent. However, even for the reduction of Ru(NH(3))(6)(3+), which occurs at potentials far negative of the flat-band potential for oxygen-terminated BDD, all areas of the surface show some electroactivity. This study highlights that the spatially heterogeneous conductivity and corresponding electroactivity of BDD are readily resolved using a combination of C-AFM, SECM, and CL.     

Reviews

Ion Implantation, Proceedings from the European Conference on Ion Implanatation, Reading, September 7–9 1970 Peter Peregrinus Limited, Southgate House, Stevenage Herts, England. England 1970, 241 pages. Price: $6.00

Lectures in Theoretical Physics Volume XI-C: Atomic Collision Processes Editors: S. Geltman, K. T. Mahanthappa and W. E. Brittin. Gordon and Breach 1969, pp xiii + 337.     

Deformation and rigidity results for the 2k‐Ricci tensor and the 2k‐Gauss‐Bonnet curvature

We present several deformation and rigidity results within the classes of closed Riemannian manifolds which either are 2k‐Einstein (in the sense that their 2k‐Ricci tensor is constant) or have constant 2k‐Gauss‐Bonnet curvature. The results hold for a family of manifolds containing all non‐flat space forms and the main ingredients in the proofs are explicit formulae for the linearizations of the above invariants obtained by means of the formalism of double forms.