Materials Literature
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Ordering at short-length scales is a universal feature of the glassy state. Experiments on boron oxide and other materials indicate that ordering on mesoscopic-length scales may also be universal. The high-resolution nuclear magnetic resonance (NMR) measurements of oxygen in boron oxide glass presented here provide ev…
A simple method is presented for calculating approximate static and dynamic vibrational hyperpolarizabilities. It involves determining electrical properties in the presence of a static field with and without geometry optimization. This method is readily applicable to all tensor components of a general polyatomic molec…
Various size-consistent approaches to the calculation of molecular hyperpolarizabilities are analyzed based on the double perturbation theory. General equations for the nth-order response property with respect to an external time-independent field are derived on the basis of the Rayleigh–Schrödinger perturbation theor…
Three supramolecular bischromophoric systems featuring zinc(II) and iron(III) porphyrins have been synthesized to evaluate the relative magnitudes of electronic coupling provided by hydrogen, sigma, and pi bonds. Laser flash excitation generates the highly reducing singlet excited state of the (porphinato)zinc chromop…
We develop a lattice gas model for the nonequilibrium dynamics of microemulsions. Our model is based on the immiscible lattice gas of Rothman and Keller, which we reformulate using a microscopic, particulate description so as to permit generalisation to more complicated interactions, and on the prescription of Chan an…
We present a microscopic derivation, without electrodynamical assumptions, of $B(x,y,H(t))$, $M(H(t))$, and $J_c(H(t))$, in agreement with experiments on strongly pinned superconductors, for a range of values of the density and strength of the pinning sites. We numerically solve the overdamped equations of motion % dy…
Abstract The mechanism of radiation vulcanization of natural rubber with 2‐ethyl hexyl acrylate (2EHA) monomer was investigated using electron spin resonance spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The primary radicals formed in the arcylate molecule were found to abstract the allylic hydrogens…
Abstract There kinds of dimeric aluminates (2DH‐306, 2DH‐324, and 2DH‐335) have been used for surface modification of calcium carbonate (CaCO 3 ) particles. The dimeric aluminates were shown to have an appreciable coupling effect at the interfaces between the light calcium carbonate (L‐CaCO 3 ) and polypropylene (PP)…
Abstract Epoxy functionalized siloxanes (EFS) are a novel class of UV curable monomers that can be rapidly photopolymerized to give transparent coatings and composites. Thin films of these materials have been subjected to low Earth orbit exposure to atomic oxygen (AO) aboard the space shuttle. It was found that UV cur…
The x-ray photoelectron valence band spectrum and x-ray emission valence-band spectra (Ti K _beta_5, Ti L_alpha, O K_alpha) of Bi4Ti3O12 are presented (analyzed in the common energy scale) and interpreted on the basis of a band-structure calculation for an idealized I4/mmm structure of this material.
The S=1/2, nearest-neighbor, kinetic Ising model has been used to model magnetization switching in nanoscale ferromagnets. For this model, earlier work based on the droplet theory of the decay of metastable phases and Monte Carlo simulations has shown the existence of a size dependent spinodal field which separates de…
Following ozone oxidation of polyester microfibers of 3.5 mum average diameter and 0.83 m(2)/g specific area, the fiber surface was subjected to graft polymerization of acrylic acid and subsequently immobilized with serologically active proteins including Staphylococcus aureus protein A, a specific antigen, and a spec…
The effect of pH on the transfer of deuteroporphyrin from dimyristoylphosphatidylcholine (DMPC) unilamellar vesicles to human serum albumin is investigated using a stopped-flow with fluorescence detection. The kinetics of this process allows for the determination of the rate constants for the porphyrin exist from the…
Dethiobiotin synthetase (DTBS) catalyzes the penultimate step in biotin biosynthesis, the formation of the ureido ring of dethiobiotin from (7R,8S)-7,8-diaminononanoic acid (7,8-diaminopelargonic acid, DAPA), CO2, and ATP. Solutions of DAPA at neutral pH readily formed a mixture of the N7- and N8-carbamates in the pre…
The crystal structures of six complexes of homodimeric Escherichia coli dethiobiotin synthetase with a variety of substrates, substrate analogs, and products have been determined to high resolution. These include (1) the binary complex of dethiobiotin synthetase and the N7-carbamate of 7,8-diaminononanoic acid, (2) th…
We report the growth and characterization of epitaxial Ba0.5Sr0.5TiO3/SrRuO3/ZrO2 on Si for potential charge storage applications. Both Ba0.5Sr0.5TiO3 (BST) and SrRuO3 (SRO) are grown (110)-oriented on yttrium-stabilized ZrO2 (YSZ) (100)-buffered Si. These films show a high degree of crystallinity with minimal interdi…
Visible light emission from porous silicon can be stimulated by applying a positive bias to a formic acid/sodium formate liquid junction cell. The emission lasts for 45 min at +2.75 V applied potential (<5 mA/cm2, power conversion efficiency ≳10−2%) and is reliably generated from n- or p-type porous silicon. An…
The influence of size on the dielectric behaviour of ferroelectrics is discussed using phenomenological Landau theory. Three types of free-standing geometry are used in our calculations-film, cylinder and sphere. For films, there is a size-driven phase transition (i.e. a transition from a ferroelectric state to a para…
We find that the reduction of the switchable polarization in BaTiO3 crystals via repeated polarization reversals (fatigue) is accompanied by the trapping of electronic charge and atomic scale distortions in the perovskite oxygen octahedron. The distortions are proposed to involve oxygen vacancies.
The quantum Hall effect is investigated in the organic conductor (TMTSF${)}_{2}$P${\mathrm{F}}_{6}$ (TMTSF is tetramethyltetraselenafulvalene) under hydrostatic pressure. Under a pressure of $p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}9$ kbar, the sequence of the quantum Hall numbers $L\phantom{\rule{0ex}{0ex…