Materials Literature
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The thermal response of tussah (Antheraea pernyi) silk fibroin films treated with different water–methanol solutions at 20°C was studied by means of dynamic mechanical (DMA) and thermomechanical (TMA) analyses as a function of methanol concentration and treatment time. The DMA curves of α-helix films (treated with ≥80…
We report the results of an optical study of the Mott transition in ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ carried out by time- and frequency-domain spectroscopies. We have observed time-resolved spectra through the Mott transition with oscillations in reflectivity associated with the fully symmetric modes. As a consequen…
We present a band structure study of orbital polarization and ordering in the two-dimensional triangular-lattice transition metal compounds LiVO 2 and NaTiO 2 . It is found that while in NaTiO 2 the degeneracy of t 2 g orbitals is lifted due to the trigonal symmetry of the crystal and the strong on-site Coulomb intera…
A measurement of electrical conductivity and Hall effect has been made for thin film La0.5Sr0.5CoO3−δ (LSCO) prepared on (001) SrTiO3 substrates by pulsed laser deposition under reduced oxygen pressures. A considerable effect of oxygen stoichiometry on electrical resistivity of LSCO thin films has been observed. The s…
The photoconductivity of tetrahedral amorphous carbon (ta-C) and hydrogenated tetrahedral amorphous carbon (ta-C:H) has been studied as a function of temperature, photon energy, and light intensity in order to understand the transport and recombination processes. ta-C and ta-C:H are found to be low mobility solids wit…
The Ginzburg criterion, which is based on the three coefficients in the Landau–Ginzburg (LG) expansion of the Helmholtz free energy density of a nonuniform system, is believed to give a reasonable estimate for the temperature scale on which crossover occurs. To compute the contribution of the square-gradient term in t…
Complete polarizabilities and first hyperpolarizabilities (which include zero-point-vibrational averaging and other vibrational corrections) have been calculated at the self-consistent-field and Møller–Plesset second order perturbation levels of approximation for CH4, CF4, and CCl4. As well as the static values, α(−ω;…
The Raman response of the radial breathing mode in single-wall carbon nanotubes was analyzed for excitation with 10 different laser lines. The line shape was fitted with 14 Voigtian oscillators which could be correlated to tubes of different helicity. The strongest lines were observed between 172 and 199 cm −1 . For a…
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…