Materials Literature
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Space-filling models of yeast hexokinase, adenylate kinase, and phosphoglycerate kinase drawn by computer clearly portray the bilobal character of these phosphoryl transfer enzymes, and the deep cleft which is formed between the lobes. A dramatic conformational change occurs in hexokinase as glucose binds to the botto…
Non-radiative energy transfer from optically excited Dy3+ to Ho3+ is studied in calibo glass. An experimental investigation is made to the nature of excited Dy3+ donors in presence of Ho3+ acceptors. The time dependence of luminescence decay following the pulsed excitation illustrates the transient behaviour, characte…
An X-ray study is made of the high-temperature and low-temperature phases of Ni(NH3)6(ClO4)2. At room temperature, the unit cell is regular, of the CaF2 type, with lattice constant ac = = 11.44 Å. The monoclinic cell of the low-temperature phase has, at T = 100 K, the constants am = (8.19 ± 0.01) Å, bm = (11.76 ± 0.01…
The structure and properties of grain boundaries are considered during superplastic deformation on the basis of recent concepts of the interaction between lattice dislocations and grain boundaries. It is shown that the boundaries contain both, lattice and grain boundary dislocations. The presence of these extraneous d…
The magnetization behaviour is investigated in a pulsed magnetic field up to 50 kOe at 80 ≦ T ≦ ≦ 220 K for hydrogen solid solutions in Fe65(Ni1–xMnx)35 invars containing 0, 4.5, 10, 17, 24, 29, and 35 wt% Mn. The alloys are enriched in hydrogen to hydrogen/metal atomic ratio n ⪅ 1 using exposures to PH2 ≦ 70 kbar. Th…
The optical anisotropy induced in films of some chalcogenide vitreous semiconductors (ChVS) by linearly polarized light is studied. The spectral responses of the photoinduced dichroism are compared with the transmission spectra of the illuminated films. The phenomenon of photoinduced anisotropy is associated with the…
The present investigation deals with amorphous polystyrene crazing behavior at both the molecular and macroscopic levels. The nature of the amorphous state is considered from the perspective of statistical fluctuation theory, especially when a mechanical force field is acting on the polymer. Past crazing studies have…
The electronic state of CuCr 2 Se 4 is investigated by means of the polarized neutron diffraction technique. From the measured form factors of copper and chromium atoms, the magnetic moments are determined to be -0.07±0.02 (µ B /Cu) and 2.64±0.04 (µ B /Cr), respectively. Further, the uniform polarization existent thro…
Ultrasonic velocities and attenuations of Rb 2 ZnCl 4 were measured as functions of temperature. The observed anomalies of the velocities are discussed in relation to the incommensurate soft mode.
An experimental study of shear viscosity η(\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}), principal normal stress difference N1(\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}), storage modulus G′(ω), dynamic viscosity η′(ω), and filament e…
A phenomenological thermodynamic model suited for the interpretation of the high spin⇌low spin transition in solid transition metal complexes is described. The model is based on the idea of the spin transition taking place through a significant phonon-assisted coupling between the electronic state of the primary spin…
Almost-temperature-independent mobility (ATIM) has been observed above about 100 K for electrons in anthracene, naphthalene, and As2S3. The conduction-band structure of all these crystals is almost two- dimensional with a very narrow bandwidth in one (c′) direction, and it is in this c′ direction that the ATIM has bee…
High-quality films of Sn-doped In2O3 (ITO) have been prepared by ion-beam sputtering at deposition temperatures below 100 °C. As in the case of rf-sputtered films, the electrical and optical properties of these films depend strongly on the O2 partial pressure during deposition. As-deposited films with low electrical r…
Phase transitions in KCaCl 3 and RbCaCl 3 were investigated by means of optical and dilatometric measurements. It was suggested from these investigations that on heating from room temperature both crystals transform from the orthorhombic phase to the tetragonal phase and then to the cubic phase. This transition sequen…
Surface soft-x-ray absorption (SSXA) spectroscopy using synchrotron radiation has been applied to study oxygen chemisorption on aluminum (100), (110), and (111) single-crystal surfaces. Evidence is presented of oxygen-related extrinsic surface resonances above the Fermi level on all faces. From analysis of the SSXA sp…
The mechanical shear degradation of polydisperse polyisobutene and monodisperse polystrene in oils of different viscosities in the concentration range of 0.1% to 1% was studied using a high-shear concentric cylinder viscometer under laminar and uniform well-defined shear field conditions. Molecular weight distribution…
The permeation of water has been measured through polyimide film over a range of thicknesses, temperatures, and relative humidities. The concentration of absorbed water was found to depend on the relative humidity and not on the temperature or sample thickness, reaching a maximum of one water molecule per repeat unit…
The diffusion coefficients for titanium and niobium radioactive tracers were simultaneously measured in Ti, ${\mathrm{Ti}}_{94.6}$${\mathrm{Nb}}_{5.4}$, ${\mathrm{Ti}}_{80.4}$${\mathrm{Nb}}_{19.6}$, and ${\mathrm{Ti}}_{64.3}$${\mathrm{Nb}}_{35.7}$ over the temperature range from 950\ifmmode^\circ\else\textdegree\fi{}C…
The primary features of the Raman and infrared spectra of $A{X}_{2}$ tetrahedral glasses are associated with the edges of the vibrational bands calculated by Sen and Thorpe. The dominant Raman peak is assigned to a singular matrix element rather than a peak in the density of vibrational states. Simple expressions are…
The pinning of charge-density waves by impurities is considered in systems that exhibit at least short-range order in three dimensions. Impurities are classified into strong and weak with quite different pinning properties. The pinning of spin-density waves is weak and the phase values at impurity sites are almost ran…