Materials Literature
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Thorough Raman and infrared (IR) reflectivity investigations of nominally pure ${\mathrm{SrTiO}}_{3}$ ceramics in the 10--300 K range have revealed a clear presence of the polar phase whose manifestation steeply increases on cooling. The Raman strengths of the Raman-forbidden IR modes are proportional to ${\ensuremath…
The crystal structure of 3-picoline (3-methylpyridine, C6H7N) has been determined at 120 (2) K following in situ crystal growth from the liquid. The molecules pack in a herring-bone-type arrangement in the non-centrosymmetric space group Pna21.
TEM analyses enable a priori investigation of smectic bilayer structures in an amorphous−liquid crystalline (LC) diblock copolymer. A newly synthesized copolymer with 85 wt % LC phase segregates into a layered morphology in both bulk and thin film studies. The microstructure has a periodicity of ∼70 Å and forms highly…
Computer simulations of systems of soft repulsive spherocylinders (SRS) of aspect ratio (L/D) equal to 4 have been carried out using the parallel molecular dynamics program GBMOLDD. At sufficiently high densities the system forms stable nematic and smectic-A liquid crystalline phases. Results are presented for a serie…
Silyl ether-coupled poly(epsilon-caprolactone)s (PCLs) with stepwise degradation profiles were synthesized via the cross-dehydrocoupling polymerizations between 1,4-bis(dimethylsilyl)benzene (BDSB) and telechelic, diol-terminated PCL macromonomers. With the presence of 10 wt % palladium on activated carbon as the cata…
Gold nanoclusters on MgO powder were prepared from adsorbed [Au(CH 3 ) 2 (C 5 H 7 O 2 )] and characterized by infrared and X-ray absorption spectroscopies. Treatment of the samples in He or H 2 at increasing temperatures removed CH 3 and C 5 H 7 O 2 ligands and caused the gold to aggregate into nanoclusters of increas…
The same intercalated structure, as determined by X-ray diffraction, is obtained whether EVA-based nanocomposites are prepared starting from an organo-modified montmorillonite (compound 1) or from a Na+ montmorillonite compatibilized by reactive processing using an alkylammonium bromide (compound 3) equivalent to the…
A new flexible approach is developed to fabricate uniform nanocrystals and nanowires of binary compound semiconductor PbS inside the channels of mesoporous silica SBA-15. The approach combines functionalization of the channel surface with thiol groups, absorption of Pb 2+, and heating in N 2 atmosphere at high tempera…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTEffect of Rehybridization on the Electronic Structure of Single-Walled Carbon NanotubesM. A. Hamon, M. E. Itkis, S. Niyogi, T. Alvaraez, C. Kuper, M. Menon, and R. C. HaddonView Author Information Departments of Chemistry and Chemical and Environmental Engineering Univ…
There is increasing interest in many-body perturbation theory as a practical tool for the calculation of ground-state properties. As a consequence, unambiguous sum rules such as the conservation of particle number under the influence of the Coulomb interaction have acquired an importance that did not exist for calcula…
We propose here a device for measuring the ellipticity of light. Its core element is a polarization diffraction grating. As far as we know, no other similar device has been developed so far. To record the grating holographically we used a Mordant Pure Yellow azodye in a matrix of gelatin. This media acquires relativel…
Abstract Poly(N‐substituted urethane)s with an alkyl or ligo(ethylene oxide) monomethyl ether side chain were synthesized by the reaction operating in the following two‐step process: first, by metalation of the starting polymer with potassium tertiary butoxide ( t ‐BuOK) and then by treatment of the obtained urethane…
We have identified the yeast open reading frame YER175c as the gene encoding the trans-aconitate methyltransferase of Saccharomyces cerevisiae. Extracts of a yeast strain with a disrupted YER175c gene demonstrate a complete loss of activity toward the methyl-accepting substrates trans-aconitate, cis-aconitate, DL-isoc…
The quantitative analysis of the vibrational properties of carbon nanotubes is a key issue for the interpretation of Raman experiments. In particular, a reliable characterization of the atomic structure of single-wall carbon nanotubes produced under various conditions is mainly based on the interpretation of low-frequ…
We studied the melting of the charge order in the half-doped tetragonal perovskite ${\mathrm{La}}_{1.5}{\mathrm{Sr}}_{0.5}{\mathrm{CoO}}_{4}$ by elastic neutron scattering. We found that diffuse peaks, corresponding to the breathing-type modulation of oxygen positions in the ${\mathrm{CoO}}_{6}$ octahedra, disappear a…
Abstract The kinetics and mechanisms of the solution imidization of polyamic acid resulting from a diamine, bis(4‐aminophenoxy‐3,5‐dimethylphenyl)naphthylmethane, and a dianhydride, 3,3′4,4′‐diphenylsulfonetetracarboxylic dianhydride, were studied at three various temperatures (145, 165, and 180 °C). The results were…
(TaSe 4 ) 2 I is a quasi-one-dimensional (1D) electrical conductor. It exhibits a phase transition at T CDW = 263 K towards a charge-density-wave (CDW) state at low temperatures. We report a full structure refinement of the incommensurately modulated structure in the CDW state at T = 110 K against synchrotron radiatio…
The structure of the organic:inorganic layered material DAZOP[MnCr(ox)3]·0.6CH3CN [DAZOP = 4-(4-dimethylamino-phenylazo)-1-methyl-pyridinium], which has 61 independent atoms in the asymmetric unit, has been solved from laboratory powder X-ray diffraction data using a novel real-space simulated annealing approach. The…
A powder x-ray diffraction experiment was performed on cubic ${\mathrm{HfW}}_{2}{\mathrm{O}}_{8}$ and ${\mathrm{ZrW}}_{2}{\mathrm{O}}_{8}$ from 90 to 560 K. The lattice parameter and absolute negative thermal expansion coefficient of ${\mathrm{HfW}}_{2}{\mathrm{O}}_{8}$ are smaller than those of ${\mathrm{ZrW}}_{2}{\m…
Abstract High‐pressure rheological behavior of polymer melts containing dissolved carbon dioxide (CO 2 ) at concentrations up to 6 wt % were investigated using a high‐pressure extrusion slit die rheometer. In particular, the steady shear viscosity of poly(methyl methacrylate), polypropylene, low‐density polyethylene,…