Materials Literature
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Quasielastic x-ray scattering from thermally populated phonons in crystalline niobium was recorded using a charge-coupled device over a large angular range. The patterns, displayed on a logarithmic intensity scale, reveal rich features. Theoretical patterns based on a lattice dynamics calculation are generated, and a…
The glass transition behavior of dried polystyrene (PS) samples adsorbed on silica, originally cast from carbon tetrachloride, has been studied using modulated differential scanning calorimetry (MDSC). The adsorbed amounts of the polymers on silica were very small, ranging from about 2 to 0.4 mg polymer/m 2 silica. Th…
A post-synthesis hydrothermal restructuring method is introduced as a convenient route to synthesize high quality MCM-48 silica with controllable pore size. Using tetraethyl orthosilicate as the silica source and cetyltrimethylammonium bromide (CTAB) as the template, the pore size could be tailored from 2.6 to 4.2 nm…
The adsorption state of ammonia (NH 3 ) on the ZnO(101̄0) surface has been investigated using photoelectron spectroscopy (PES) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The core-level and valence-band PES measurements reveal that ammonia adsorbs molecularly via its N atom on ZnO(101̄0) and t…
In-situ observations of crystallisation in minerals and organic polymers have been made by simultaneous, time-resolved small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) techniques. In isotactic polypropylene slow quiescent crystallisation shows the onset of large scale ordering prior to crysta…
A new conjugated copper-complexed polyrotaxane has been prepared by electropolymerization of a thiophene derivative; the rings are threaded onto a multi-1,10-phenanthroline (phen) axle, copper(I) acting as a template. The presence of CH3 groups ortho to the nitrogen atoms of the phen nuclei belonging to the conjugated…
Fluorescence decay curves for the ${}^{4}{\stackrel{\ensuremath{\rightarrow}}{{G}_{5/2}}}^{6}{H}_{7/2}$ transition of ${\mathrm{Sm}}^{3+}$ ions in lithium fluoroborate glasses for different lanthanide concentrations have been measured as a function of pressure up to 21 GPa at room temperature. At ambient conditions, f…
We made small-angle neutron scattering (SANS) study of a Pluronic L64 micellar system in aqueous solution at high polymer concentrations (wt %), 35%<c<53%, in a temperature range where a kinetic glass transition has been observed by photon correlation spectroscopy and zero shear viscosity measurements. We analyze SANS…
Large-scale aligned carbon nanofiber/nanotube patterns have been fabricated by a feasible and inexpensive direct photolithography technique using ordinary black-and-white film as a photomask. Using a calcination/reduction protocol, transition metal salts in the photoresist are transformed to metallic dots, which act a…
Direct electron transfer of horse heart cytochrome c is measured at a nanocrystalline boron-doped diamond thin-film electrode. A quasi-reversible, diffusion-controlled cyclic voltammetric response is observed for untreated diamond. The peak currents change linearly with the concentration, and importantly, there is no…
Mesoporous silica MCM-41 may be restructured by performing secondary synthesis (i.e., recrystallisation) in which calcined MCM-41 is used as silica source. The influence of a number of factors on the recrystallisation has been investigated. The factors investigated are, (1) the time allowed for hydrothermal recrystall…
We have examined the critical adsorption transition for a nonreversible random walk chain (NRRW) and a self-avoiding walk chain (SAW) at the surface and have identified the critical adsorption point. We then examine the partition coefficient of a NRRW chain and a SAW chain confined in a slit with two adsorbing walls n…
The novel atrane-like six-coordinate (RO)(2)TaL complexes [where R = Me or Et and L = tris(2-oxy-3,5-dimethylbenzyl)amine] containing three six-membered rings have been synthesized and characterized. The R = Me complex is the first group 5 representative of this class of compounds structurally characterized by X-ray m…
Acid hydrolysis of cellulose fibers produces suspensions of colloidal cellulose nanocrystals. At low concentrations these suspensions are isotropic, while at high concentrations the cellulose rods spontaneously organize into a chiral nematic liquid crystal phase. We have studied the effect of adding high molecular wei…
Self-assembly of metallic nanostructures using 2D templates consisting of surfactant systems at the air/water interface is demonstrated (see Figure). The morphology of the resulting nanostructures can be partially controlled by adjusting parameters such as the molecular structure of the surfactant, the chemical proper…
The axial phenol group is protonated and the equatorial phenoxyl group antiferromagnetically coupled to the cupric center in the complex [CuII(LH)(OAc)].+ (see picture), which can be considered as both a structural and functional model of galactose oxidase. This complex reproduces the features of the enzyme chemistry.…
Four long-chain phenyl glucoside amphiphiles possessing a saturated or unsaturated long alkyl chain group as the self-assembling unit of a highly organized molecular architecture were synthesized. Their self-assembling properties were investigated by EF-TEM, SEM, CD, FT-IR, and XRD. Compound 2 possessing one double bo…
During this study different raw materials, activating agents, and preparation variables were used to compare the behavior of carbon materials with different morphologies in methane storage applications. Two different types of carbon materials have been prepared: (i) chemically activated carbons prepared from an anthra…
Supramolecular hydrogels (see Figure for structure) are spontaneously formed by mixing aqueous dispersions of short-“legged” ammonium amphiphiles and fluorescent anions. Energy transfer between donor (naphthalene) and acceptor (anthracene) anions is shown to be more efficient in the hydrogels compared to that in dilut…
A new photochromic amorphous molecular material based on an azobenzene, BFlAB, has been designed and synthesized. BFlAB readily forms an amorphous glass with a glass-transition temperature of 97 °C and exhibits photochromism in the amorphous solid film as well as in solution. The BFlAB amorphous film forms a surface r…