Materials Literature
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The electronic-energy band structure, site, and angular-momentum decomposed density of states (DOS) and charge-density contours of perovskite ${\mathrm{BaTiO}}_{3}$ in the paraelectric phase are calculated by the first-principles tight-binding linear muffin-tin orbitals method with the atomic-sphere approximation usin…
Although it has long been recognized that dynamics in supercooled liquids might be spatially heterogeneous, only in the past few years has clear evidence emerged to support this view. As a liquid is cooled far below its melting point, dynamics in some regions of the sample can be orders of magnitude faster than dynami…
The elastic constants of wood cell wall were theoretically analyzed using two cell wall unit models and three sets of elastic constants for lignin-hemicellulose matrix. The Young's modulus of the cell wall layers in the direction perpendicular to the microfibril orientation increased remarkably with increasing Young's…
Periplasmic Escherichia coli L-asparaginase II with Y25F mutation in the active-site cavity has been obtained by recombinant techniques. The protein was crystallized in a new hexagonal form (P6(5)22). Single crystals of this polymorph, suitable for X-ray diffraction, were obtained by vapor diffusion using 2-methyl-2,4…
The adsorption of cationic tetradecyltrimethylammonium bromide (TTAB) from aqueous solution on two series of powdered MCM-41 aluminosilicates (referred to as SiAl x C n, where x is the mole Si:Al ratio and n the chain length of the surfactant template) has been studied at 298 K under the conditions of free pH of the a…
Structural changes occurring during a stretching process have been studied with the uniaxially and biaxially drawn PTMT films. The stress-induced crystallization has been observed from the stress−strain curve showing abrupt increase of stress at a specific draw ratio (dr = 2.5) at which the density was found to increa…
The self-diffusion coefficients have been determined for five generations of poly(propylene imine) dendrimers in methanol at three different temperatures 5, 25, and 45 °C over the whole concentration range. Pulsed field gradient spin echo NMR has been used. The Stokes−Einstein hard sphere radii have been calculated in…
Modifications in electronic and structural aspects of RuO 2 films electroprecipitated onto Au electrodes induced by changes in the applied potential have been examined in situ in aqueous 0.50 M H 2 SO 4 by Ru K-edge X-ray absorption spectroscopy (XAS). The Fourier transform of the k 3 -weighted extended X-ray absorpti…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDifferential Reactivity between Interconvertible Side-On Peroxo and Bis-μ-oxodicopper Isomers Using Peralkylated Diamine LigandsViswanath Mahadevan, Mark J. Henson, Edward I. Solomon, and T. D. P. StackView Author Information Department of Chemistry, Stanford Universit…
We have investigated the phase transition between two distinct mesoporous silicas: SBA-15, comprising a hexagonally packed arrangement of cylindrical pores (6−12 nm in diameter), and mesocellular silica foams (MCF), consisting of spherical voids (22−42 nm in diameter) interconnected by “windows” of ∼10 nm. Both SBA-15…
The switching effects in Sb x Se 1- x (0⩽ x ⩽0.9) thin films have been investigated. The annealing of the films at 323 K improves the switching characteristics and decreases the threshold voltage V th . The threshold switching voltage and threshold activation energy ε s were found to decrease linearly on increasing th…
Some of the physical properties of x CuO-50 PbO-(50- x )B 2 O 3 glasses were studied. The transformation temperature shows a minimum value at about 20 mol% CuO. The infrared spectra reveal that in this glass the fraction of four-coordinated boron atoms would be minimal. Up to a content of 30 mol% CuO there is a limite…
Chlorocobalt(III) tetraphenylporphyrin, (Cl)CoIIITPP, reacts with potassium cyanide in dichloromethane or benzene containing 18-crown-6 to give a green solution of [crown-K+][(CN)2CoIIITPP-]. The molecular structure of [crown-K+][(CN)2CoIIITPP-] is identified by X-ray crystallography. In methanol, (Cl)CoIIITPP plus KC…
In this study, we synthesized the mesoporous materials under a shear flow at relatively low temperatures using the wormlike micellar solution of a cationic surfactant cetyltrimethylammonium bromide (CTAB). The additive sodium salicylate (NaSal) enhanced the microstructure evolution by forming the micron-order flexible…
The thermal stability of rabbit skeletal muscle glycogen phosphorylase b was characterized using enzymological inactivation studies, differential scanning calorimetry, and analytical ultracentrifugation. The results suggest that denaturation proceeds by the dissociative mechanism, i.e., it includes the step of reversi…
Metal nanoparticles grown within the nanostructured matrix of the amphiphilic polymer poly(octadecylsiloxane) (PODS) are investigated here by transmission electron microscopy. Due to its silanol groups and alkyl chain, PODS forms a bilayered nanostructure containing an intercalated layer of water within an aqueous env…
Rare earth elements find a wide range of applications in metallurgy, fuel cells, the coloring of glass and ceramics, and the production of magnets, but their separation is difficult, leading to high prices. In his Perspective, Fray discusses the separation process reported by Uda et al., which greatly reduces the numb…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTLiquid-Crystalline Ion-Conductive Materials: Self-Organization Behavior and Ion-Transporting Properties of Mesogenic Dimers Containing Oxyethylene Moieties Complexed with Metal SaltsToshihiro Ohtake, Yasuyuki Takamitsu, Kaori Ito-Akita, Kiyoshi Kanie, Masahiro Yoshizawa, Tomohi…
The pulsed laser deposition (PLD) of Y 2 O 3 from a pure yttrium ablation target is performed for the first time and is shown to replace advantageously PLD from yttria targets. The films were grown on optical-quality MgO(100) and sapphire(0001) substrates, the former yielding films with poorer crystalline quality beca…
Two-dimensional spatially resolved microfocus X-ray diffraction has been used to investigate spherulites of pure bacterial poly(3-hydroxybutyrate) (PHB) and of a blend of natural and synthetic atactic PHB (a-PHB) crystallized at a relatively high temperature (Tc = 140 degrees C). Both samples investigated contained pr…