Materials Literature
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The phonon-drag contribution to the thermoelectric power is calculated at low temperatures in polar semiconductor heterostructures. Carries are assumed to interact with longitudinal acoustic phonons through deformation potential and with both longitudinal and transverse acoustic phonons through piezoelectric field. Th…
We discuss a rate-theory model of polymer crystallization that exhibits many of the morphological and kinetic features observed in the laboratory. The interplay between the growth of the lamellar crystals in directions along the molecular direction and at right angles to it is discussed, together with some of the impl…
Comprehensive (0.05--3-eV) spectroscopic measurements are reported for poly(3-hexylthienylene), P3HT, during photoexcitation (i.e., photoinduced absorption) and after doping with ${\mathrm{NOPF}}_{6}$. A one-to-one correspondence between the photoinduced and doping-induced spectral changes is observed, typical of cond…
The boron carbides are composed of twelve-atom icosahedral clusters which are linked by direct covalent bonds and through three-atom intericosahedral chains. The boron carbides are known to exist as a single phase with carbon concentrations from about 8 to about 20 at. %. This range of carbon concentrations is made po…
Different ratios of boron to carbon ions were implanted into diamond maintained at liquid-nitrogen temperature. After implantation, the diamonds were heated to 500 \ifmmode^\circ\else\textdegree\fi{}C by dropping them onto a platform situated in a vertical tube furnace, and then annealed for 1 h. This was followed by…
We report a picosecond pump–probe study of 55 Å cadmium sulfide microcrystallites embedded in polymer films. Large negative absorbance changes at wavelengths corresponding to energies near the band gap are observed. This absorption bleaching and the associated changes in refractive index are mainly responsible for the…
It is shown that large scale MCSCF linear response (MCLR) calculations can be carried out efficiently using an iterative algorithm where the linear transformations are carried out directly, i.e., without explicitly constructing the MCLR matrices. Calculations are presented on H2O of frequency dependent polarizabilitie…
Injection luminescence in the ultraviolet is observed from a cubic boron nitride pn junction diode made at high pressure. Microscopic observation and spectroscopic studies show that the light emission occurs near the junction region only in the forward-bias condition. The spectra extend from ∼215 nm to the red, having…
Single-particle and collective microscopic dynamics of a classical Yukawa fluid are analysed on the basis of simple memory function and mode-coupling theories. Thermodynamic states for different screening regimes are correlated in terms of an effective hard-sphere packing fraction. The longitudinal current fluctuation…
prednisolone followed by a reducing course of oral prednisolone.She improved clinically and her erythro- cyte sedimentation rate settled to 19 mm in the first hour after 10 days.The tracheostomy tube was removed after 12 days and good movement was seen in both vocal cords.Her recovery was further compli- cated by an e…
The conductivity of the following six new low-dimensional compounds is reported: (Me 4 N)(Ni(dmit) 2 ), (Et 4 N)(Ni(dmit) 2 ), (Pr 4 N)(Ni(dmit) 2 ), (Bu 4 N)(Ni(dmit) 2 ), (Bu 4 N)(Pt(dmit) 2 ) and (Et 4 N) 0.5 (Pd(dmit) 2 ). Semiconducting behaviour is found for all the compounds investigated, with activation energi…
Accurate rheological data for silicate melts and crystal‐melt, melt‐vapor, and crystal‐melt‐vapor suspensions of both natural compositions and simple binary and ternary systems are useful in constraining theories of momentum transport in magmatic systems and theories of melt structure. Data addressing these problems a…
We derive stability criteria for arbitrary strained heterostructures. The criteria are based on evaluating the excess stress as a continuous function of position within a structure for the two well-known Matthews–Blakeslee [J. W. Matthews and A. E. Blakeslee, J. Cryst. Growth 27, 118 (1974)] dislocation mechanisms for…
We have used x-ray diffraction to study oriented strands of hexa-hexylthiotriphenylene discotic liquid crystals. The low-temperature ${D}_{\mathrm{ho}}$ phase consists of a triangular array of columns with periodic positional and incommensurate helical intracolumn order. A three-column superlattice results from the fr…
Be measuring the degree of linear polarization we identify the orbital and spin contributions to the x-ray magnetic scattering in holmium. When the incident x-ray energy is tuned through the ${L}_{\mathrm{III}}$ absorption edge, we observe a fiftyfold resonant enhancement of the magnetic signal, and resonant integer h…
Discussion des developpements recents dans le domaine de l'application des terres rares aux materiaux magnetiques et electroniques
The shock-heated molecular-beam technique was used to obtain vibrationally excited oxygen molecules. The vibrational distributions of these diatomic molecules, in argon gas as the ``carrier'' gas of a shock-heated molecular beam, have been calculated by considering atomic recombination, collisional excitation, and dee…
<div class="htmlview paragraph">Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were…
Abstract The versatility of poly(vinyl chloride) is largely a result of its capability to be modified by a wide variety of formulating additives, especially plasticizers and fillers. These additives vary widely with respect to their chemical composition, and the concentrations used in PVC, which impart significant eff…
The presence of Ca (concentration, ca. 0.4 mM) in the growth medium causes cells of Desulfovibrio vulgaris (Hildenborough) to aggregate, leading to a decrease in plating efficiency. When the Ca concentration in the medium was reduced 20-fold, cell aggregation did not occur and the plating efficiency increased from an…