Materials Literature
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Formation of the nacre of a shell is mimicked here to synthesize layered polymer/calcium carbonate composites such as that shown in the Figure. The combination of insoluble chitin or chitosan solid matrices with soluble acidic macromolecules such as poly(acrylic acid) is used to induce thin-film crystallization of CaC…
Dicyanoaurate(I) and dicyanoargentate(I) ions undergo significant oligomerization in aqueous and methanolic solutions. The absorption edges of K[Au(CN) 2 ] and K[Ag(CN) 2 ] solutions undergo progressive red shifts with an increase in concentration up to near the saturation limits, whereupon total red shifts of 13.4 ×…
The magnetic structures of the hexagonal ${\mathrm{YMnO}}_{3}$ and ${\mathrm{ScMnO}}_{3}$ oxides (space group ${P6}_{3}cm)$ have been studied by neutron-diffraction experiments on powder samples. This study has been complemented with magnetic susceptibility and specific-heat measurements. They confirm that ${\mathrm{Y…
We present a versatile density functional approach (DFT) for calculating the depletion potential in general fluid mixtures. For the standard situation of a single big particle immersed in a sea of small particles near a fixed object, the system is regarded as an inhomogeneous binary mixture of big and small particles…
We have used Brillouin light scattering to make a detailed study of the behavior of the glass transition temperature T(g) in ultrathin, free-standing polystyrene films. The glass transitions were experimentally identified as near discontinuities in the thermal expansion. The effects of film thickness, molecular weight…
The aim of this paper is to present the results of characterization of the particle shapes of six standard transition aluminas samples using transmission and scanning electron microscopies; selected area electron diffraction, in parallel with X-ray powder diffraction were used for confirmation of the different transit…
Electrical and optical properties of CuAlO2, a p-type conducting transparent oxide, were examined for the thin films prepared by the pulsed laser deposition technique. The indirect and direct allowed optical band gaps were evaluated to be ∼1.8 and ∼3.5 eV, respectively. The conductivity at 300 K was ∼3×10−1 S cm−1 and…
Recent observations of charged colloidal particles trapped at the air-water interface revealed long-range interparticle attractive forces, not accounted for by the standard theories of colloidal interactions. We propose a mechanism for attraction which is based on nonuniform wetting causing an irregular shape of the p…
Nanocomposite materials were obtained using glycerol plasticized starch as the matrix and a colloidal suspension of cellulose whiskers as the reinforcing phase. The cellulose whiskers, prepared from tunicin, consisted of slender parallelepiped rods with a high aspect ratio. After mixing the raw materials and gelatiniz…
Oxidative stress is an unavoidable consequence of life in an oxygen-rich atmosphere. Oxygen radicals and other activated oxygen species are generated as by-products of aerobic metabolism and exposure to various natural and synthetic toxicants. The "Oxygen Paradox" is that oxygen is dangerous to the very life-forms for…
Diatoms are the world's largest contributors to biosilicification and are one of the predominant contributors to global carbon fixation. Silicon is a major limiting nutrient for diatom growth and hence is a controlling factor in primary productivity. Because our understanding of the cellular metabolism of silicon is l…
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…