Tilings by Regular Polygons
Patterns in the plane from Kepler to the present, including recent results and unsolved problems.
Materials Literature
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Synthesis and Properties of Aromatic and Extended Chain Polyamides
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and Properties of Aromatic and Extended Chain PolyamidesP. W. MorganCite this: Macromolecules 1977, 10, 6, 1381–1390Publication Date (Print):November 1, 1977Publication History Published online1 May 2002Published inissue 1 November 1977https://pubs.acs.org/doi/10.1…
Phosphorus-31 NMR studies on molybdic and tungstic heteropolyanions. Correlation between structure and chemical shift
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhosphorus-31 NMR studies on molybdic and tungstic heteropolyanions. Correlation between structure and chemical shiftRene Massart, Roland Contant, Jean Marc Fruchart, Jean Pierre Ciabrini, and Michel FournierCite this: Inorg. Chem. 1977, 16, 11, 2916–2921Publication Date (Pr…
Random Decrement Technique for Modal Identification of Structures
Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.
The Protein Data Bank
The Protein Data Bank is a computer-based archival file for macromolecular structures. The Bank stores in a uniform format atomic co-ordinates and partial bond connectivities, as derived from crystallographic studies. Text included in each data entry gives pertinent information for the structure at hand (e.g. species…
The crystal structure of Prussian Blue: Fe4[Fe(CN)6]3.xH2O
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe crystal structure of Prussian Blue: Fe4[Fe(CN)6]3.xH2OH. J. Buser, D. Schwarzenbach, W. Petter, and A. LudiCite this: Inorg. Chem. 1977, 16, 11, 2704–2710Publication Date (Print):November 1, 1977Publication History Published online1 May 2002Published inissue 1 November 1…
The effect of Brownian motion on the bulk stress in a suspension of spherical particles
The effect of Brownian motion of particles in a statistically homogeneous suspension is to tend to make uniform the joint probability density functions for the relative positions of particles, in opposition to the tendency of a deforming motion of the suspension to make some particle configurations more common. This s…
Quantum Limit of Ferroelectric Phase Transitions inKTa1−xNbxO3
Dielectric and elastic constants of $\mathrm{K}{\mathrm{Ta}}_{1\ensuremath{-}x}{\mathrm{Nb}}_{x}{\mathrm{O}}_{3}$ are presented as a function of $x$ and of the temperature. For $x=8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, the system exhibits the characteristics of a ferroelectric at the displacive li…
Chemical shifts and effective charges in ternary and complex systems
Effective charges, q, in ternary and complex systems are estimated. The semiempirical method of Suchet (1965) is extended to ternary compounds such as manganites and ferrites while the semi-experimental method of Gianturco and Coulson (1968) is applied to complex Co-Zn ferrites and cobalt complexes. An attempt is made…
Uniaxial stress studies of the 2.498 eV (H4), 2.417 eV and 2.536 eV vibronic bands in diamond
Abstract The H4 vibronic band is the dominant end product of annealing irradiated diamonds which contain impurity nitrogen in one specific aggregated form, the ‘B’ form. This paper reports uniaxial stress experiments on the H4 zero phonon line, and establishes it unambiguously as a (110) electric dipole transition at…
Electrical Conductivity in Doped Polyacetylene
Doped polyacetylene forms a new class of conducting polymers in which the electrical conductivity can be systematically and continuously varied over a range of eleven orders of magnitude. Transport studies and far-infrared transmission measurements imply a metal-to-insulator transition at dopant concentrations near 1%.
Magnetic, electrical, and thermal studies of the V1−xRexO2 system with 0 ≦x ≦ 0.15
The insulator–metal transition of VO2 and VO2 doped with Re is studied by means of DTA, X-ray diffraction, magnetic susceptibility, and electrical conductivity measurements. A linear decrease of the transition temperature of 18 K/at% Re is observed. The low-temperature phase is found to be temperature-independent para…
Photoluminescence in GaSe
Photoluminescence of GaSe is measured between 4.2 and about 40 K. The spectra of many samples are classified into three types. The first type has only one broad peak at about 2.04 eV, and the second type has two sharp lines at 2.096 and 2.088 eV followed by some lines at the lower energy side. The last one contains a…
A mössbauer study of Ca2+-containing magnetites
The substitution of Ca2+ ions in magnetite is studied, mainly by Mössbauer spectroscopy. The Ca2+ ions are located at the tetrahedral sites and the conduction electrons can be described by a band model. The magnetite structure can at most contain 6.67 wt% of Ca. The presence of a Ca2+ ion at an A-site decreases the hy…
Vacancy formation volume in indium from positron-annihilation measurements
An equilibrium method for the determination of the vacancy formation volume in many metals is provided by the trapping of positrons at vacancies. Utilizing a Bridgman press and angular-correlation counting techniques, the vacancy formation volume in metallic indium has been determined to be 6.1 \ifmmode\pm\else\textpm…
A new hypothesis on ultrasonic interaction with nematic liquid crystal
The visible interaction of low-intensity ultrasonic waves with a nematic liquid crystal may be explained simply by the hypothesis of a torque tending to orient LC molecules perpendicular to the vibrations. It is shown how this torque can be related to anisotropic attenuation of ultrasound and minimization of propagati…
Thermal boundary resistance at metal-epoxy interfaces
Measurements of the thermal impedance across copper-epoxy-copper sandwiches have been made over a temperature range of 0.05-10 K. The data are consistent with the suggestion that only low-frequency phonons contribute to thermal transport across the sandwich. As a result the apparent thermal boundary resistance at the…
Observation of color centers inα- and Naβ- alumina by electron energy loss and optical spectroscopies
We have measured the Auger, electron-energy-loss, and optical-transmission spectra of $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ and Na $\ensuremath{\beta}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ from 0 to 45 eV and from 3 to 6 eV, respectively. Although Auger measurements were not ab…
Confined-carrier luminescence of a thin In1−xGaxP1−zAsz well (x∼0.13, z∼0.29, ∼400 Å) in an InP p-n junction
A thin (∼400 Å) LPE In1−xGaxP1−zAsz ’’trap’’ on the p-type side of an InP junction [Eg(InP)−Eg(InGaPAs) ≡ΔE∼245 meV], is filled by injection to a high enough density to make it possible to observe confined-particle states and laser modes in a 70-meV (≳600 Å) range. The position of the modes is in good agreement with t…
Raman scattering from in-plane lattice modes in low-stage graphite-alkali-metal compounds
Low-temperature Raman scattering results for stage 1, 2, and 3 graphite-alkali-metal intercalation compounds are reported for in-plane modes using the Brewster-angle back-scattering geometry. Detailed full spectra are presented for stage 1, 2, and 3 compounds of graphite-Rb at 77 K. Particular attention is given to th…