Materials Literature
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Computer simulation by numerically solving the time-dependent Schr\"odinger equation was used to investigate image formation during scanning tunneling microscope (STM) imaging of three-dimensional objects with radii of curvature comparable with that of the STM tip. The results were compared with experiment. When the n…
General topological rules determine the carbon ring structures in arbitrary sp2-bonded structures, particularly nanotube junctions.Received 23 June 1998DOI:https://doi.org/10.1103/PhysRevB.58.12671©1998 American Physical Society
Living ring opening polymerization of ε-caprolactone initiated from the numerous chain-end hydroxymethyl groups of the analogous dendrimeric and hyperbranched polyesters derived from 2,2-bis(hydroxymethyl) propionic acid is described. By controlling the size of the dendritic macromolecule and the molar ratio of ε-capr…
We describe real-space imaging measurements of the interactions and elastic properties of charge-stabilized colloidal crystals. Interactions between charge-stabilized latex spheres self-assembled into colloidal crystals are extracted from single-particle dynamics using new techniques in digital video microscopy. The s…
In order to investigate subtle differences in the local structure and bonding of amorphous ices, glassy liquid water was produced by rapid cooling of micrometer sized water droplets. Samples were first studied with power x-ray diffraction (PXRD) and differential scanning calorimetry (DSC) to ensure that the production…
Hard spheres with a polydispersity above approximately 8% are shown to crystallise into two phase-separated solid phases. A polydispersity above 8% is too large to be tolerated by a single solid phase but phase separation produces two fractions with polydispersities sufficiently narrow to allow them to crystallise. It…
At room-temperature, sodium pentaoxodivanadate, NaV2O5, was found to have the centrosymmetric space group Pmmn. This space group implies the presence of only one kind of V site, in contrast with previous reports [Carpy & Galy (1975). Acta Cryst. B31, 1481–1483] of the non-centrosymmetric P21mn counterpart. This indica…
We report the synthesis and characterization of a series of liquid crystalline polymers substituted with the 4′-methoxybiphenyl-4-yloxy group. The spacer length is varied from 4–8 methylene units. The materials are characterized by polarized light microscopy, differential scanning calorimetry, and X-ray analysis. All…
In this work we construct molecular configurations of an amorphous Lennard-Jones solid, which, for given values of the temperature and stress/pressure, constitute local minima of the free energy under the quasi-harmonic approximation (QHA). From the volumetric behavior of these configurations for various values of the…
Giant magneto impedance (GMI) has been measured in Fe77.5Si13.5B9 wires and Co67Fe3Cr3Si15B12 ribbons. The samples were annealed in order to induce specific anisotropies. An hysteretic behavior of the GMI is observed in both cases. Results show that this hysteretic behavior is related to irreversible changes in the ma…
It is beyond common understanding that the photoluminescence lifetime of the transition ${}^{4}{\stackrel{\ensuremath{\rightarrow}}{{T}_{1}}}^{6}{A}_{1}$ of ${\mathrm{Mn}}^{2+}$ doped in ZnS decreases dramatically by five orders of magnitude from bulk to nanocrystal since the magnetic interactions which usually make t…
We investigate exact eigenstates of tight-binding models on the planar rhombic Penrose tiling. We consider a vertex model with hopping along the edges and the diagonals of the rhombi. For the wave functions, we employ an ansatz, first introduced by Sutherland, which is based on the arrow decoration that encodes the ma…
Electrical measurements of nitrogen doped tetrahedral amorphous carbon (ta-C:N) thin films have revealed a reversible nonvolatile memory effect, related to the excitation and de-excitation of electrons between deep acceptor states and shallow donor states within the mobility gap. This effect is characterized by change…
Abstract A finite element simulation is presented for the prediction of residual stresses resulting from the heat treatment of railroad commuter car wheels during manufacture. The quenching and annealing segments of the wheel manufacturing process are simulated using a decoupled heat transfer and stress analysis. A se…
The drying mechanism of semicrystalline poly(vinyl alcohol) (PVA) was investigated. PVA samples of various molecular weights were crystallized by annealing at temperatures slightly above the glass transition temperature of PVA, and swollen in water for different time periods. The water volume fraction in the sample wa…
Formyltransferase from Methanopyrus kandleri is composed of only one type of subunits of molecular mass 32 kDa. The enzyme requires the presence of lyotropic salts for activity and thermostability. We report here that the enzyme is in a monomer/dimer/tetramer association equilibrium, the association constant being aff…
All of the first-principles electronic-structure calculations for the martensitic structure of NiTi have used the experimental atomic parameters reported by Michal and Sinclair [Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. B37, 1803 (1981)]. We have used first-principles, full-potential, linear muffin…
Polycrystalline samples of dimeric cadmium tartrate, [(Cd,C4H4O6)2H2O)]3H2O [labeled CdT(I)], were studied using impedance measurements and x-ray powder diffraction. The dependence of the real part of the dielectric constant on temperature showed a sharp peak at about 65 °C, revealing a structural phase transition, wh…
Spin-lattice relaxation times of P1 centers in a suite of two natural type Ib, two synthetic type Ib, and one natural type Ia diamonds were measured at 9.6 GHz as a function of temperature in the range 300 K>T>4.2 K. An analysis of the results revealed that for three of the diamonds (two synthetic type I…
We present ab initio molecular-dynamics studies of the graphitization of flat and stepped diamond (111) surfaces. Fully self-consistent calculations were performed within the local-density-functional approximation with ultrasoft pseudopotentials and periodic boundary conditions. We investigated the effects of the syst…