Materials Literature
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The thermally stimulated current (TSC) has been used over a wide range of pressure to determine the principal characteristics of the polymers such as the activation volume ΔV, the activation energy ΔE, and the preexponential term τ0 of the Arrhenius-type relaxation time: τ=τ0 exp[(PΔV+ΔE)/kT]. Experimentally, the 6-Po…
The Monchick, Yun, and Mason generalization of the Wang Chang–Uhlenbeck–deBoer formulation of kinetic theory is the starting point for the generalized phase shift (GPS) evaluation of the transport coefficients. It is shown that the expressions for these properties can be written in terms of the rotational energy momen…
Abstract Polyimide fibers were prepared by wet spinning of poly( p , p ′ ‐diaminodiphenylmethanepyro‐mellitamic acid). Density measurements and x‐ray diffraction studies were carried out to study the structure of the resultant polyimide fibers. Polyamic acid as well as undrawn polyimide fibers were essentially amorpho…
dc conductivity measurements have been made as a function of temperature and electric field in bulk amorphous Se, Se-Te, Se-Sb, and Se-Te-Ge, in order to identify the conduction mechanism and to study the effect of various dopants in Se on the conductivity. It is found that the conduction in all the samples, except in…
We report a comprehensive investigation of charge transfer from host to solute atoms in alloys based on alkali metals. The residual resistances of strongly electronegative impurities in quench-condensed dilute alloys clearly indicate the formation of the charge-transfer state. The same effects cause percolative transi…
The structure of the enzyme p-hydroxybenzoate hydroxylase (EC 1.14.13.2) in a complex with its substrate has been determined at a resolution of 2.5 Å. The molecular weight is 43,000 and the dimensions of one molecule are approximately 70 Å × 50 Å × 45 Å. The crystal structure contains dimers of these molecules. Approx…
The spectra of valence and core electronic excitations of polyethylene from 1 to 390 eV were measured with a resolution of 0.11 eV by transmission electron energy loss spectroscopy. Structure at 9.5, 13.2, 14.7, 16.6, 19.6, 21.6 eV and a continuum of core excitations beginning at 287.5 eV was measured and compared wit…
Abstract The dynamic properties of epoxy–amine networks have been studied using a torsion pendulum, and the effect of replacement of resin by monoglycidyl ethers on the beta relaxation has been determined. It is shown that the loss peak is not sensitive to glyceryl units derived from the monofunctional diluents. From…
Through detailed examination of the crystal structure and bonding conditions in the trichalcogenides, it has been possible to gain a deeper understanding of the band structure of these complex materials, and with this of their unusual electronic behavior. The character of the observed semimetallicity in Ta${\mathrm{Se…
High-resolution polarized absorption and fluorescence spectra of ${\mathrm{Pr}}^{3+}$ in LiY${\mathrm{F}}_{4}$ were measured at temperatures between 10 and 300\ifmmode^\circ\else\textdegree\fi{}K. Energy-level assignments were made assuming electric-dipole transition selection rules for ${S}_{4}$ site symmetry. Forty-…
The room-temperature Brillouin spectra of 16 optical glasses of varying composition have been measured. Sound velocities for both transverse and longitudinal waves were determined along with the Pockels electro-optic coefficients ${p}_{12}$ and ${p}_{44}$. The damping parameter for the longitudinal phonons was obtaine…
Various properties of dielectric thin films are discussed in this paper: refractive index and absorption coefficient, light scattering, structure, microstructure, density, gas sorption, chemical composition, homogeneity, adhesion, hardness and mechanical stress, and environmental influences.
Ion mobilities and volume recombination coefficients in sulphur hexafluoride were measured in the pressure range 0.25-21 bar. At higher pressures proportionality between recombination coefficient and the sum of ion mobilities is observed. The mobilities and the recombination coefficient were found to vary with pressur…
The electrical resistivity and temperature coefficient of the resistivity of polycrystalline aluminium films (500-1700 AA) deposited on to a glass substrate were measured in situ at temperatures of 50, 100 and 140 degrees C. The effect of grain boundary scattering was analysed using the Mayadas-Shatzkes theory (1970).…
Infrared absorption and luminescence measurements of substitutional Cr 2+ (d 4 ) in the II-VI compounds ZnS, ZnSe, ZnTe and CdTe are reported. The experimental results are interpreted in the framework of crystal field theory with spin-orbit coupling and a substantial Jahn-Teller interaction in the 5 T 2 ground state a…
The cationic complex (2-hydroxyethanethiolato)(2,2',2''-terpyridine)platinum(II), [(terpy)Pt(HET)]+, binds cooperatively to poly(A).poly(U) by intercalation. The melting temperature of poly(A).poly(U) in low-salt buffer is increased by 6 degrees C in the presence of [(terpy)Pt(HET)]+, indicating stabilization of the d…
Abstract The changes in molecular weight and molecular weight distribution of PVC degraded in presence of maleic anhydride, benzoquinone and anthraquinone were studied by gel permeation chromatography. Chain scission and crosslinking reactions were indicated on the basis of M̄ n and M̄ w of degraded samples. Crosslink…
Surfactants and Interfacial Phenomena Milton J. Rosen Bridging the gap between purely theoretical aspects of surface chemistry and the purely empirical experience of the industrial technologist, this book applies theoretical surface chemistry to understanding the action of surfactants in modifying interfacial phenomen…
The free-volume distribution in a simulated Lennard-Jones liquid is heterogeneous. Chains of holes, appearing as segments rather than a continuous network, have lifetimes that are brief compared with the mean vibration period of the atoms. Larger isolated holes persist for longer times. If the chains are interpreted a…
Carboxyl content of cellulose half-acid ester derivatives was determined by the calcium acetate method and by the absorption of silver from silver meta-nitrophenolate solutions. Both methods utilize the acidity of the carboxyl proton in an ion-exchange reaction, thereby producing a salt. With both the calcium acetate…