Materials Literature
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In the liquid crystalline phases of many organic materials molecular end chains take part in the ordering process. For a single chain, this ordering is calculated by exact summation over all conformations of a chain in the molecular field due to the neighboring molecules. The nematic orientational ordering of a system…
The susceptibility of an array of fine nickel particles was measured as a function of temperature from 1.5 to 300 \ifmmode^\circ\else\textdegree\fi{}K at a frequency of 5 kHz. The particles were formed by cosputtering nickel with Si${\mathrm{O}}_{2}$ or ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ and varied in diameter betw…
The structure and resistivity of vanadium dioxide films close to the metal-semiconductor transition have been studied as a function of stoichiometry. Unit-cell volume is shown to go through a minimum and the transition temperature and resistivity ratio through a maximum at the apparent stoichiometric oxygen level. The…
Abstract We have proposed a new hypothesis that the acid sites on binary metal oxides are formed by an excess of a negative or positive charge in the mixed oxides and that whether the charge is excess or not, and whether it is positive or negative, are determined by the coordination numbers and valences of the positiv…
The present review is devoted to discussion of the principal stages of development of mirror electron microscopy. In the mirror electron microscope (MEM) the electron beam is reflected in a retarding electric field near the sample surface, and as a result the object being studied is not subjected to bombardment by the…
Light scattering has been used to study phase separation near the critical point in a binary mixture of methanol and cyclohexane. The intensity measurements are in conformity with the spinodal decomposition theory of Cahn. Measurements were also made of the spectral width of the scattered light in the phase separation…
The previously termed "anomalous" properties of the various polytypes of ${d}^{1}$ Ta${\mathrm{S}}_{2}$, Ta${\mathrm{Se}}_{2}$, etc. are attributed to charge-density waves, their periodic structure distortions, and the superlattices they induce.
The paramagnetic spectra of Gd 3+ and Fe 3+ in monoclinic zirconia single crystals have been investigated in the Q-band. In both cases a unique type of defect was observed, thus confirming that the trivalent ion has no O 2- vacancy in nearest-neighbour positions. The spectra were fitted to the most general spin hamilt…
The optical absorption coefficients and the temperature dependence of the edge in amorphous As 2 S 3 have been measured at temperatures down to 10 K. The temperature coefficients of the gap at a fixed absorption level ( delta E/ delta T) alpha , can be separated into two components. The first is attributed to electron…
The published data on the specific heat and susceptibility of Fe(NH 4 ) 2 (SO 4 ) 2 6H 2 O are analysed to find the energies, wavefunctions and magnetic axes appropriate to the Fe 2+ ions at temperatures below 20 K. Two ambiguities are solved by experiment. The dependence on temperature of the crystal susceptibility a…
Data necessary to determine the activation energy and volume of the creep process in zinc have been obtained in the temperature range 1.5 to 80 °K by means of a differential technique. While calculating the activation parameters the influence of quantum phenomena on fluctuation-induced dislocation motion over local ba…
The authors have discussed earlier the photomagnetoelectric effect in graded-band-gap semiconductors assuming symmetrical band-edge gradients. The present paper rewrites the continuity equation under asymmetric band-edge gradients, and includes the effects of position-dependent minority carrier lifetime, electron and…
The heat and entropy of the transformation ice III–IX has been measured by a differential calorimetric technique as −0.32 cal K−1 mol, compared with the value −0.805 cal K−1 mol expected if ice III were fully disordered and ice IX were fully ordered within the limitations of the ice rules. It seems likely that there i…
Contrary to recent claims, no correlation of useful predicting power exists between the tendency of a nematic liquid to align transverse to a solid surface and the difference between the surface free energies of the nematic liquid and of the substrate. Observations that lead to this conclusion are reported for systems…
The ion-pair interaction potentials obtained by using the modle presented in our previous paper are applied to some ionic crystals. The calculated lattice properties of alkali-halide and alkaline-earth-dihalide crystals agree quite well with experimental data. The polymorphic transitions of alkali-halide crystals at h…
We determine bandwidths and critical-point positions with respect to the valence-band edge for the valence bands of several extensively studied semiconductors (with an accuracy of about 0.3 eV) by using photoemission densities of states derived from photoemission spectra obtained in the 24-78-eV photon energy range. T…
Electronic transport has been investigated in ${\mathrm{As}}_{2}$(${\mathrm{Se}}_{1/3}$ ${\mathrm{Te}}_{2/3}$${)}_{3}$ and Ge(${\mathrm{Se}}_{1/3}$${\mathrm{Te}}_{2/3}$ ${)}_{2}$ amorphous semiconductors through measurements of photoconductivity, optical absorption, dark conductivity, thermoelectric power, and field e…
Mutant adenylosuccinate lyases of Bacillus subtilis were prepared by site-directed mutagenesis with replacements for His141, previously identified by affinity labeling as being in the active site [Lee, T. T., Worby, C., Dixon, J. E., and Colman, R. F. (1997) J. Biol. Chem. 272, 458-465]. Four substitutions (A, L, E, Q…
The spectra of corona discharges in air at atmospheric pressure, in a 0·6 m point-plane gap under positive impulse voltage, have been measured in the near-ultraviolet and visible regions. Two types of corona discharges have been investigated: the first corona which develops from the electrode tip; and the leader coron…
A technique is presented which enables the recovery of the probability distribution for single scattering from plural-scattering electron energy loss data. Neither the scattering parameter t/λ nor details of the component processes need be known. The computational method uses Fourier series in order to overcome a numb…