Materials Literature
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Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) were used to investigate the local structure of Pd supported on ZSM-5, which was affected by the acid sites of support and the adsorption of nitrogen oxide. After the thermal treatment of the initially ion-exchanged Pd am…
Analytical second derivatives for combined QM/MM calculations have been formulated and implemented in the CHARMM program interfaced with the ab initio quantum mechanical GAMESS and CADPAC programs. This makes possible evaluation of vibrational frequencies and infrared intensities in large systems that cannot be treate…
The atomic structure of a carbon nanotube can be described by its chiral angle and diameter and can be specified by a pair of lattice indices $(n,m).$ The electronic and mechanical properties are critically dependent on these indices. Scanning tunneling microscopy (STM) is a useful tool to investigate carbon nanotubes…
We combine a density functional theory (DFT) with a self-consistent field model (SCF) to calculate the phase behavior of thin, oblate colloidal particles that are coated with surfactants and dispersed in a polymer melt. These coated particles represent organically modified clay sheets. By integrating the two methods,…
The structure of amorphous carbon at densities of 2.0, 2.6, 2.9, and 3.2 ${\mathrm{g}/\mathrm{c}\mathrm{m}}^{3}$ has been investigated using Car-Parrinello ab initio molecular dynamics. The networks were generated by rapidly cooling samples of 125 atoms to form a solid amorphous structure. The important structural att…
The authors have shown accelerated endothelialization on polyethylene terephthalate (PET) grafts preclotted with autologous bone marrow. Bone marrow cells have a subset of early progenitor cells that express the CD34 antigen on their surfaces. A recent in vitro study has shown that CD34(+) cells can differentiate into…
Second electron affinities of Au_N and Ag_N clusters and the dissociation energies for fission of the Au_N^{2-} and Ag_N^{2-} dianions are calculated using the finite-temperature shell-correction method and allowing for triaxial deformations. Dianionic clusters with N > 2 are found to be energetically stable against f…
Excitonic spectra are calculated for free-standing, surface passivated, InAs quantum dots using atomic pseudopotentials for the single-particle states and screened Coulomb interactions for the two-body terms. We present an analysis of the single particle states involved in each excitation in terms of their angular mom…
A convenient method for the systematic introduction of a variety of organoimido ligands at terminal oxo sites in the hexamolybdate cluster [Bu 4 N] 2 [Mo 6 O 19 ] is described, consisting of reaction with the appropriate organic isocyanate RNCO (R = n -butyl, cyclohexyl, 2,6-diisopropylphenyl) in pyridine solution. Si…
Polycrystalline samples of the strongly distorted $R{\mathrm{NiO}}_{3}(R=\mathrm{H}\mathrm{o},\mathrm{}\mathrm{Y},\mathrm{}\mathrm{E}\mathrm{r},\mathrm{}\mathrm{T}\mathrm{m},\mathrm{}\mathrm{Y}\mathrm{b},\mathrm{}\mathrm{Lu})$ perovskites have been prepared under high hydrostatic pressure, at 20 kbar. The crystal stru…
Crystallographic data, electrical and thermal transport measurements, and heat-capacity data are reported for several compounds with the filled skutterudite structure: ${\mathrm{Tl}}_{x}{\mathrm{Co}}_{4\ensuremath{-}y}{\mathrm{Fe}}_{y}{\mathrm{Sb}}_{12}$ and ${\mathrm{Tl}}_{x}{\mathrm{Co}}_{4}{\mathrm{Sb}}_{12\ensurem…
We investigate the thermal conductivity of bulk silicon crystals based on molecular-dynamics (MD) simulations. If it is taken that the system size must be larger than the phonon mean free path, several hundreds of millions of atoms must be computed for crystals with large thermal conductivity values such as Si. We dem…
Analytical expressions for the velocities of the longitudinal and the torsional sound waves in single-walled carbon nanotubes are derived using Born's perturbation technique within a lattice-dynamical model. These expressions are compared to the formulas for the velocities of the sound waves in an elastic hollow cylin…
A study of thermal conductivities perpendicular to the interfaces in ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}{/\mathrm{S}\mathrm{b}}_{2}{\mathrm{Te}}_{3}$ superlattices is presented. The lattice thermal conductivities in these short-period superlattices are less than those in homogeneous solid-solution alloys and exhibit a…
BiFeO 3 , when forming a solid solution with BaTiO3, shows structural transformations over the entire compositional range. Above 70 mole % of BiFeO3 the structure is rhombohedral and below 4 mole %, it is tetragonal. In between the structure is cubic. The ferroelectric TC decreases with increasing composition of BaTiO…
Diamond has some of the most extreme physical properties of any material, yet its practical use in science or engineering has been limited due its scarcity and expense. With the recent development of techniques for depositing thin films of diamond on a variety of substrate materials, we now have the ability to exploit…
Chirality-dependent van Hove singularities (vHs) of the one-dimensional electronic density of states (DOS) are discussed in connection with resonant Raman spectroscopy. The effect of trigonal warping on the energy dispersion relations near the Fermi energy splits the peaks of the density of states for metallic nanotub…
The perchloratoiron(III) complexes of a series of 2,6-disubstituted tetraphenylporphyrin ligands, where the 2,6-phenyl substituents were -H, -F, -Cl, -Br, or -OMe, as well as two 2,4,6-phenyl-substituted complexes, where the substituents were -Me and -OMe, have been investigated as a function of temperature by 1H NMR…
L-Malate (MalDH) and L-lactate (LDH) dehydrogenases belong to the same family of NAD-dependent enzymes. LDHs are tetramers, whereas MalDHs can be either dimeric or tetrameric. To gain insight into molecular relationships between LDHs and MalDHs, we studied folding intermediates of a mutant of the LDH-like MalDH (a pro…
The phase properties of 14 tetra- n -alkylammonium and -phosphonium salts with chloride, bromide, iodide, and perchlorate as anions and alkyl chain lengths from heptyl to octadecyl have been examined as neat solids and as gelators in thermally reversible organogels. These gelator structures are among the simplest inve…