Materials Literature
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The performance of hybrid exchange functionals is investigated within the framework of Density Functional Theory (DFT), in describing the properties of cubic and tetragonal ferroelectric phases of BaTiO3. A variable fraction ξ of non-local HF exchange is mixed with Becke's GGA formulation, and coupled with the LYP cor…
We develop and solve a continuum theory for the piezoelectric response of one-dimensional nanotubes and nanowires, and apply the theory to study electromechanical effects in boron-nitride nanotubes. We find that the polarization of a nanotube depends on its aspect ratio, and a dimensionless constant specifying the rat…
High-grade MgB2(0001) films were grown on Mg(0001) by means of ultra-high-vacuum molecular beam epitaxy. Low energy electron diffraction and x-ray diffraction data indicate that thick films are formed by epitaxially oriented grains with MgB2 bulk structure. The quality of the films allowed angle-resolved photoemission…
The electronic properties and the molecular orientation of Zn-tetraphenyl-porphyrin films deposited on Si(111) have been investigated using synchrotron radiation. For the first time we have revealed and assigned the fine structures in the electronic spectra related to the HOMOs and LUMOs states. This is particularly i…
Complex response function obtained in reflection spectroscopy at terahertz range is examined with algorithms based on dispersion relations for integer powers of complex reflection coefficient, which emerge as a powerful and yet uncommon tools in examining the consistency of the spectroscopic data. It is shown that the…
The ladder theory, in which the Bethe-Goldstone equation for the effective potential between two scattering particles plays a central role, is well known for its satisfactory description of the short-range correlations in the homogeneous electron liquid. By solving exactly the Bethe-Goldstone equation in the limit of…
Based on a hopping model we show how the mixed alkali effect in glasses can be understood if only a small fraction c(V) of the available sites for the mobile ions is vacant. In particular, we reproduce the peculiar behavior of the internal friction and the steep fall ("vulnerability") of the mobility of the majority i…
We report on an ab initio study of the structural and electronic properties of B- and P-doped Si nanoclusters. The neutral impurities formation energies are calculated. We show that they are higher in smaller nanoclusters and that this is not related to the structural relaxation around the impurity. Their dependence o…
We have used molecular dynamics simulations to construct a microcanonical caloric curve for a 1415-atom Ni icosahedron. Prior to melting the Ni cluster exhibits static solid-liquid phase coexistence. Initially a partial icosahedral structure coexists with a non-wetting melt. However at energies very close to the melti…
The experimental results relevant for the understanding of the microscopic dynamics in liquid metals are reviewed, with special regard to the ones achieved in the last two decades. Inelastic neutron scattering played a major role since the development of neutron facilities in the 1960s. The last ten years, however, sa…
While the behaviour of large amounts of liquid is dictated by gravity, surface forces become dominant at small scales. They have for example the remarkable ability to make droplets stick to their substrates (even if they are inclined), which is a practical issue in many cases (windshields, window panes, greenhouses, o…
Abstract The bistrimethylsilyl derivatives of six different diphenols were polycondensed with 2,6‐difluoropyridine in N ‐methylpyrrolidone in the presence of K 2 CO 3 . On the basis of previous studies, the reaction conditions were optimized for almost quantitative conversions. The feed ratio was systematically varied…
The usage of nanoscale ferroelectric films as tunnel barriers in electronic devices offers a unique possibility to study the physics of ultrathin ferroelectric materials by means of electronic transport. In this letter, we simulate the current-voltage characteristics of a metal-ferroelectric-metal tunnel junction by u…
The Forum Section of Toxicological Sciences is designed to include discussions and commentaries on relevant and timely issues facing toxicologists and to provide an interface between toxicology and public policy. In 2004, a series of articles to discuss approaches to carcinogenicity risk assessment was developed which…
Abstract Selective graft modifications of polypropylene (PP) are demonstrated in which desirable functionality is introduced without the degradation that accompanies conventional radical‐mediated processes. A range of modification strategies is presented, each exploiting triallyl trimellitate (TATM) or its derivatives…
Abstract Biodegradable poly( tert ‐butyl acrylate)–poly[( R )‐3‐hydroxybutyrate]–poly ( tert ‐butyl acrylate) triblock copolymers based on bacterial poly[( R )‐3‐hydroxybutyrate] (PHB) were synthesized by atom transfer radical polymerization. The chain architectures of the triblock copolymers were confirmed by 1 H NMR…
Abstract Polyaniline (PANI) thin films with high optical activity are prepared electrochemically on indium tin oxide (ITO) substrates by polymerizing aniline in the presence of aniline oligomers and optically active camphor sulfonic acid (CSA). These optimized PANI chiral thin films have an anisotropic factor of 0.03…
The crystal structures, magnetic structures, and phase transformation of the off-stoichiometric Ni53Mn25Ga22 were studied by neutron powder diffraction at different temperatures. It is shown that Ni53Mn25Ga22 has a tetragonal I4/mmm structure from 20Kto403K. An abrupt jump in unit-cell volume around room temperature,…
Abstract AB‐type block copolymers with poly(trimethylene carbonate) [poly(TMC); A] and poly(ethylene oxide) [PEO; B; number‐average molecular weight ( M n ) = 5000] blocks [poly(TMC)‐ b ‐PEO] were synthesized via the ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of monohydroxy PEO with st…
The first and second hyperpolarizability beta and gamma are obtained for formaldehyde oligomers (H2CO)n (n = 1-7) using computational methods. We have used the finite field (FF) approach and hyperpolarizability density analysis (HDA) to predict the microscopic first and second nonlinear hyperpolarizability of the form…