Materials Literature
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The three-dimensional structure of a penicillin-sensitive D-alanyl-carboxypeptidase-transpeptidase has been determined by x-ray crystallography to a resolution of 2.8 angstroms. The site of binding of the beta-lactam antibiotics penicillin and cephalosporin has been located. These findings constitute direct observatio…
An electron transmission experiment is used to study the low-energy total cross sections in Na, K, Rb, Cs and Hg. A shape resonance is observed in Na at 0.08+or-0.02 eV and in Hg at 0.42+or-0.03 eV. In Rb evidence is found for the existence of a shape resonance below 0.05 eV. The results are compared with the availabl…
The dynamic structure factor and its generalization for transverse excitations for the normal modes of a Lennard-Jones glass are calculated. The results are compared with those for a polycrystal. The longitudinal dispersion curve shows a remarkably deep minimum at the wave vector where the structure factor has a peak.
Incoherent quasielastic neutron scattering (IQNS) has been used to investigate the molecular motions of adamantanone in its plastic phase. They can be described on the basis of a model allowing 120° jumps around the crystallographic [111] directions together with 90° rotations around the molecular twofold symmetry axi…
Abstract The copolymerization of monomethyl intaconate (MMI) with styrene (St) initiated with 2,2′‐azoisobutyronitrile in solvents differing in dielectric constants and capability to form hydrogen bonds was investigated. The IR‐ and 1 H NMR spectroscopic studies of the monomer mixtures in four solvents have shown an i…
NMR spectra from $2H$-Ta${\mathrm{Se}}_{2}$ are analyzed to obtain charge-density-wave parameters versus temperature. It is shown that there is a major orthorhombic distortion within each Se-Ta-Se layer, implying unexpectedly strong interlayer coupling. Evidence is also given for the existence of a significant interac…
Abstract The synthesis and phase behaviour of a series of polymers having liquid crystalline sidechains and a poly(acrylic acid) backbone are described. These polymers show a dependence of the phase transition temperatures on molecular weight. In copolymers of two liquid crystalline acrylic esters, induced smectic pha…
A dynamic theory of the amplitude dependent dislocation hysteresis is developed, emphasising the importance of the quasi-particle–dislocation interaction for the non-linear response of the real crystal to the high-frequency ultrasonic wave propagation. A strong frequency dependence of the sound attenuation rate is pre…
The differential cross sections of α- 7 Li and α- 12 C elastic scattering have been measured at energies E α =5 and 6 MeV. The results are interpreted by using real phase-shift analysis. It has shown that the real phase-shifts interpreted the α- 12 C scattering data very well at the energies investigated. The α- 7 Li…
Nematic as well as phase-change guest-host liquid crystal displays are shown to be dual-frequency addressable by using liquid crystalline hosts with suitable static and dynamic dielectric properties, thus rendering them multiplexable. Positive as well as negative optical contrasts and fast turn-off times can be achiev…
A simple phenomenological model of the electronic structure of the pseudogap of an amorphous semiconductor is considered, and used as the starting point for a systematic investigation of the processes that determine the nature of the photoluminescence. Many of the most striking features of these materials are shown to…
The relationship between dipole-field sums and Lorentz tensor components in single crystals is described and used to develop a method for computing the tensor components via rapidly convergent sums of Bessel functions. The method is used to compute Lorentz factors for simple, body-centered, and base-centered orthorhom…
The phonon dispersion curves for graphite intercalation compounds (GIC's) are calculated for the case of potassium, rubidium, and cesium intercalates. The model is based on the staging periodicity in these compounds in that it assumes that the symmetry of the graphite crystal is preserved upon intercalation. The effec…
The crystallographic parameters of compounds MnAs 1- x P x (0≦ x ≦0.275) are determined as a function of temperature between about 100 and 600 K. It is found that these crystals except for MnAs take a MnP type structure in low temperature side and transform to a NiAs type at critical temperatures. These structural tra…
Elastic scattering by a small inhomogeneous sphere, comprised of two concentric spherical regions, may be abnormally low if the dielectric constant of the external medium is intermediate between those of the two regions. When one of these regions is a metal with a real negative dielectric constant, there may also be v…
The (111) and (110) surfaces of Pt, clean, oxidized, and covered by CO, have been investigated for surface $4f$ core-level binding-energy shifts. For the (111) face the surface $\mathrm{Pt}4{f}_{\frac{7}{2}}$ core level was shifted by 0.40\ifmmode\pm\else\textpm\fi{}0.05 eV to lower binding energy relative to the bulk…
We report on careful line shape studies of slow motional and orientation dependent ESR spectra of a deuterated liquid-crystal-like spin probe dissolved in a benzilidene-derivative (40,6) and in cyanobiphenyl derivative (S2 and 5CB) liquid crystals. The simulation of the ESR spectra is based on the Lanczos algorithm re…
The experimental data of the ${\mathrm{Zn}}_{3}$${\mathrm{P}}_{2}$ absorption edge are analyzed for single crystals and thin films. The isotropic Kane band-structure model, with the introduction of a valence-level splitoff due to crystal-field interaction is used to calculate the absorption coefficient. The best fit t…
The lattice dynamics of pristine graphite is presented with the use of a Born---von K\'arm\'an model. With the consideration of interactions to fourth neighbor both intraplane and interplane, good agreement is simultaneously obtained with ir, Raman, and inelastic neutron scattering measurements of lattice modes and wi…
The heating rate is an important, though often neglected experimental variable in TL measurements. Lithium fluoride (TLD-100) samples have been heated at rates up to 100 degrees C s -1 during TL readout. The change in TL glow peak intensities and (Mg 2+ -V - ) dipole concentration during readout have been investigated…