Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of polyphenylene from a cis-dihydrocatechol biologically produced monomerD. G. H. Ballard, A. Courtis, I. M. Shirley, and S. C. TaylorCite this: Macromolecules 1988, 21, 2, 294–304Publication Date (Print):February 1, 1988Publication History Published online1 May 20…
Methods have been developed that allow facile X-ray data collection for biological macromolecules at cryogenic (near liquid N2) temperatures. The crystals are first transferred from their mother liquor to a hydrocarbon environment, then mounted with a standard glass fiber (no capillary), and flash cooled in situ with…
A lattice-dynamical formalism using the rigid-ion model due to Born and Huang is applied to the ferroelectric crystals ${\mathrm{PbTiO}}_{3}$ and ${\mathrm{BaTiO}}_{3}$, in the tetragonal phase. The model includes short-range interactions of axially symmetric type between various ions in the primitive cell and long-ra…
A method is described which assigns indices to a set of single-crystal reflections recorded by the rotation-oscillation technique using a fixed X-ray wavelength. It is assumed that the space group and approximate unit-cell parameters are known. The unknown crystal orientation is determined directly from the observed d…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPoly(lactones). 9. Polymerization mechanism of metal alkoxide initiated polymerizations of lactide and various lactonesHans R. Kricheldorf, Martin Berl, and Nico ScharnaglCite this: Macromolecules 1988, 21, 2, 286–293Publication Date (Print):February 1, 1988Publication Histo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElemental carbon cagesT. G. Schmalz, W. A. Seitz, D. J. Klein, and G. E. HiteCite this: J. Am. Chem. Soc. 1988, 110, 4, 1113–1127Publication Date (Print):February 17, 1988Publication History Published online1 May 2002Published inissue 17 February 1988https://pubs.acs.org/doi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermally irreversible photochromic systems. Reversible photocyclization of diarylethene derivativesMasahiro Irie and Masaaki MohriCite this: J. Org. Chem. 1988, 53, 4, 803–808Publication Date (Print):February 1, 1988Publication History Published online1 May 2002Published in…
Some sintered oxides based on were found to exhibit appreciable proton conduction under hydrogen‐containing atmosphere at high temperature. The verification of proton conduction was made by studying the EMF of various gas cells using the specimen ceramics as the solid electrolyte. The protonic conductivity in the dope…
We discuss measurement of the local thickness t of a transmission microscope specimen from the log-ratio formula t = lambda ln (It/I0) where It and I0 are the total and zero-loss areas under the electron-energy loss spectrum. We have measured the total inelastic mean free path lambda in 11 materials of varying atomic…
A brief review is given of model theories of the displacive structural instability in ferroelectrics. Particular attention is paid to the idea of compensation of the contributions of the short-range forces and the long-range internal field dipole forces to the square of the frequency of critical lattice vibrations. A…
A detailed model is developed for calculating the local distortion near Eu 2+ impurity sites in the alkali halides. The ionic positions obtained using this model are then used to carry out a superposition model analysis of the spin-Hamiltonian parameters. The results are consistent with results obtained for Eu 2+ and…
We have studied the dynamics of the phase separation between a dilute lyotropic lamellar phase (smectic) and an isotropic phase in a quaternary (water, sodium dodecyl sulfate, pentanol, dodecane) system. Observation of the phase separation with small-angle light scattering on an oriented sample allows us to demonstrat…
A density-functional theory for the transitions from isotropic to plastic crystal and to nematic fluid in a fluid of prolate hard ellipsoids is presented. Direct correlations are computed with a variational technique based on the Percus-Yevick equation for the correlation functions. As anisotropy is increased from the…
Fifty different mineral samples were tested as potential heterogeneous or epitaxial nucleants for four commonly crystallized proteins. It was found, by conventional protein crystallization techniques, that for each protein there was a set of mineral substrates that promoted nucleation of crystals at lower critical lev…
The authors describe a model of halogen-bridged mixed-valence linear chain complexes (transition-metal ions bridged by halogen ions) incorporating electrons coupled to on-site and inter-site phonons. They show that the charge-transfer situation appropriate to many members of the class corresponds to a charge-density w…
The tetragonal-orthorhombic phase transition in arsenic pentoxide has been studied by X-ray powder diffraction and is found to be a proper ferroelastic transition. The spontaneous strain behaves as the order parameter following Landau theory with epsilon s varies as mod T c -T mod beta , beta = 1 / 2 , T c =578 K. The…
Previously collected high-resolution neutron-diffraction data from KH 2 PO 4 (KDP) at room temperature have been re-analysed, including careful correction for thermal diffuse scattering, absorption and extinction and similar, new data have been obtained from 95%-deuterated KH 2 PO 4 (DKDP). This has made possible, for…
Received 16 November 1987DOI:https://doi.org/10.1103/PhysRevLett.60.238©1988 American Physical Society
In situ Fourier-transform infrared spectra of polyaniline give clear evidence for an insulator-to-metal transition in the first oxidation step and a metal-to-insulator transition in the second oxidation step. The former originates from a pure protonic mechanism without intercalation of counter ions whereas in the latt…
An amorphous silicon structure is obtained with a computer simulation based on a new moleculardynamics technique in which the interatomic potential is derived from a parameter-free quantum-mechanical method. Our results for the atomic structure, the phonon spectrum, and the electronic properties are in excellent agree…