Materials Literature
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The reversible reaction of a monomeric CuII complex to a cyclic hexamer (crystal structures shown below) is the first example interconversion between a potential guest complex and a complex that cannot function as a guest [Eq. (a)]. It is—like in living organisms—controlled by a very common external signal, namely pro…
Why don't we live in β-peptide world? This is a legitimate question in light of new findings by D. Seebach et al. and S. Gellman et al. on the secondary structures of β-peptides. Peptides composed of less than ten β-amino acid residues can from stable, secondary structure motifs like the 31-M-helix shown on the right.…
A highly ordered lamellar mesophase is exhibited by the thermally stable liquid-crystalline gold(I) dicarbene compounds presented here. The crystal structure of one of these compounds is depicted on the right.
The total energy differences between various SiC polytypes (3C, 6H, 4H, 2H, 15R and 9R) were calculated using the full-potential linear muffin-tin orbital method using the Perdew-Wang-(91) generalized gradient approximation to the exchange-correlation functional in the density functional method. Numerical convergence…
Improvement of a superconducting magnet system makes induction of a strong magnetic field easier. This fact gives us a possibility of energy conversion by the Nernst effect. As the first step to study the Nernst element, we measured the conductivity, the Hall coefficient, the thermoelectric power and the Nernst coeffi…
The statistical properties of coherent radiation scattered from phase-ordering materials are studied in detail using large-scale computer simulations and analytic arguments. Specifically, we consider a two-dimensional model with a nonconserved, scalar order parameter (Model A), quenched through an order-disorder trans…
A LMTO implementation of Aversa and Sipe's length-gauge formalism for calculating the full frequency dependent second-harmonic generation in the independent particle approximation is presented. It is applied to GaAs, GaP, 3C-SiC, c-BN and wurtzite and zincblende GaN and AlN. The use of the scissor's operator for corre…
Double exchange (DE), superexchange (SE), and higher-order contributions to the exchange interaction energy between Mn layers in ${\mathrm{LaMnO}}_{3}$ are studied using the linear-muffin-tin-orbital method as generalized to treat noncollinear magnetic configurations. The degree of the internal lattice distortion $(f)…
Photocurrent changes with light soaking have been studied in amorphous ${\mathrm{As}}_{2}{\mathrm{S}(\mathrm{S}\mathrm{e},\mathrm{T}\mathrm{e})}_{3}$ and Se and crystalline ${\mathrm{As}}_{2}{\mathrm{S}}_{3}$ and Se at 10--300 K. In the chalcogenide glasses the photoconductive degradation occurs at 300 K, while at low…
Heat-capacity and magnetic-susceptibility studies have been carried out on ${\mathrm{NiS}}_{2\ensuremath{-}x}{\mathrm{Se}}_{x}$ single crystals for $0.38<~x<~0.58$ and $0<~x<~0.71,$ respectively. These and earlier physical measurements document the gradual evolution, with rising $x,$ of the alloys from goo…
We applied molecular dynamics, density functional theory, and computer graphics techniques to the investigation of the homoepitaxial growth process of the MgO(001) surface. MgO molecules are deposited over the MgO(001) plane one by one at regular time intervals with definite velocities. Any deposited MgO molecule migr…
Two ether-sulfone-dicarboxylic acids, 4,4′-[sulfonylbis(2,6-dimethyl-1,4-phenylene)dioxy]dibenzoic acid (Me-III) and 4,4′-[sulfonylbis(1,4-phenylene)dioxy]-dibenzoic acid (III), were prepared by the fluorodisplacement of 4,4′-sulfonylbis(2,6-dimethylphenol) and 4,4′-sulfonyldiphenol with p-fluorobenzonitrile, and subs…
Copolyamides based on poly(m-phenylene isophthalamide) and poly-(p-phenylene terephthalamide), to which 1,6-diaminohexane units were regularly inserted every 3 or 5 phenylene monomer units, were synthesized. The copolymers were obtained by condensation of individually prepared diamino- and dicarboxylic-building blocks…
Porous Y2O3 ceramic was found to show huge thermopower values up to −50 mV/K at 900–1000 K in vacuum, but not in air. Such huge thermopowers may be generated by the electron gas emitted from the internal surfaces of the pores and are associated with some unknown effects. The nondimensional thermoelectric figure of mer…
Collagen was purified from bovine Achilles tendon and crosslinked with dimethyl suberimidate (DMS) and glutaraldehyde (GTA). Under optimal conditions, the shrinkage temperature (Ts) was raised to 74 degrees C for collagen crosslinked with DMS and to 80 degrees C for those crosslinked with GTA. Crosslinking density mea…
This paper presents the results of dielectric dispersion in Ba 2 NaNb 5(1- x ) Ta 5 x O 15 (BNNT) single crystals over the frequency range 1 kHz to 4 GHz. The fundamental dielectric dispersion occurs above 10 7 Hz and is caused by a soft relaxational mode. This mode gives the main contribution to the high static permi…
Medical-grade silicone elastomers were subjected to accelerated aging in saline to verify the hydrolytic stability of the elastomer. Tensile strength, elongation at break, and the elastomer stress measured at 100% or 200% elongation did not change significantly for peroxide-cured sheeting aged in 37 degrees C or 100 d…
We present a flexible and computationally efficient scheme for calculating electronic eigenstates of semiconductor nanocrystals using Wannier functions. With this method, we compute the band gap of CdS nanocrystals and compare our calculations with experiment. This approach also enables us to study the dependence of t…
We study morphology of chemically reacting binary mixtures quenched into a thermodynamically unstable region. One of the characteristic features of the system which has not been studied so far is that one can change the average volume fraction during the phase separation process. Computer simulations are carried out i…
A multiple–order–parameter theory of ordering on a binary face–centred–cubic (FCC) crystal lattice is developed, and adapted to provide a continuum formulation that incorporates the underlying symmetries of the FCC crystal in both the bulk and gradient–energy terms of the free energy. The theory is used to compute the…