Materials Literature
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The electronic structure of finite-length armchair carbon nanotubes has been studied using several ab-initio and semi-empirical quantum computational techniques. The additional confinement of the electrons along the tube axis leads to the opening of a band-gap in short armchair tubes. The value of the band-gap decreas…
The lowest energy structures of ${\mathrm{Au}}_{n}$ ( $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}38,55,75$) nanoclusters are obtained by unconstrained dynamical and genetic-symbiotic optimization methods, using a Gupta $n$-body potential. A set of amorphous structures, nearly degenerate in energy, are found…
Experimental observations of various deformation and fracture modes under compression of single multiwalled carbon nanotubes, obtained as a result of embedment within a polymeric film, are reported. Based on a combination of experimental measurements and the theory of elastic stability, the compressive strengths of th…
The emission spectrum of high quality ZnO epilayers is studied from room temperature up to 550 K. At room temperature and low excitation power a single emission peak is observed which may be identified with the free exciton from its peak energy and dependence on temperature. However, when excitation intensities exceed…
Surfactant micellar templates used for synthesis of MCM-41 mesoporous oxides are revealed to serve as a hydrophobic carrier for bringing nonpolar inorganic precursors selectively into the one-dimensional channels of MCM-41. Stepwise calcination of MCM-41 incorporating ferrocene thereby gives rise to a sharp and intens…
In this research, oligomeric polyalkyl phosphate-type polyols (P% = 14–17) were synthesized from ethylene glycol or 1,4-butanediol (PBE or PBB) by means of butyl phosphorodichloridate, which was prepared from phosphorus oxychloride and butanol. These polyols were then reacted with isocyanate to form the corresponding…
The room-temperature resonance Raman (RR) spectra of nickel(II) porphine have been simulated for excitation within the Q-band optical transition, taking into account both coordinate-independent (Condon) as well as coordinate-dependent (non-Condon) contributions to the Raman scattering amplitude of each vibration. Comp…
A latex of poly(β-hydroxyoctanoate) was obtained from Pseudomonas oleovorans grown at high cell density on sodium octanoate. A fermentation using a pH-stat control of octanoate concentration as well as the purification steps using sodium hypochlorite were described. It was observed that latex stabilization occurred sp…
We have prepared and characterized a mesoporous material where the framework, of both the as-synthesized and calcined materials, is composed of ZrO 2 -doped 25-Å TiO 2 anatase crystallites. The nanocrystalline framework is structured about a surfactant-templated, disordered porous network with a uniform pore diameter…
Low-dimensional metals exhibit a wealth of interesting phenomena associated with the special topology of their Fermi surfaces. These Fermi surfaces contain a very rich information concerning not only the dimensionality of the conductivity but also the possibility of different metal-to-insulator or metal-to-metal trans…
The syntheses and characterization of [2,3,7,8,12,13,17,18-octafluoro-5,10,15,20-tetraphenylporphinato]cobalt, Co(F(8)TPP), and [2,3,7,8,12,13,17,18-octafluoro-5,10,15,20-tetrakis(pentafluorophenyl)porphinato]cobalt, Co(F(28)TPP), are reported. Co(F(28)TPP).2tol (tol = toluene) crystallizes in the monoclinic space gro…
Polymer blends incorporating poly (ethylene terephthalate) (PET), polyamide-6 (PA-6), and a reactive compatibilizer (low molecular weight bisphenol-A epoxy resin—E-44) were prepared with the following E-44 weight percent concentrations: 0, 0.3, 0.6, 1, 3, 5, and 10. The samples was studied by a scanning electron micro…
A hybrid layered compound [{K(18-cr)(2-PrOH)(2)}{Mn(acacen)}(2){Fe(CN)(6)}] has been prepared by the reaction of [Mn(acacen)(Cl)] with [K(18-cr)(H(2)O)(2)](3)[Fe(CN)(6)].3H(2)O in an ethanol/2-propanol mixed solvent (18-cr = 18-crown-6-ether, acacen = N,N'-ethylenebis(acetylacetonylideneiminate)). It crystallizes in t…
Detailed bulk magnetization and magnetic susceptibility measurements are reported for representative examples of the series of ferrimagnetic tris-oxalato-ferrate(II,III) salts with general formula AFe II Fe III (C 2 O 4 ) 3 (A = quaternary ammonium, phosphonium, or arsonium). The compounds all crystallize in two-dimen…
The solution structure of Abeta(1-40)Met(O), the methionine-oxidized form of amyloid beta-peptide Abeta(1-40), has been investigated by CD and NMR spectroscopy. Oxidation of Met35 may have implications in the aetiology of Alzheimer's disease. Circular dichroism experiments showed that whereas Abeta(1-40) and Abeta(1-4…
The effects of antifoam on the control of foam formation during the demineralization of crab shell in the preparation of chitin were evaluated. Foam formation was markedly controlled by addition of antifoam and decreased with increasing antifoam concentrations. At 1.00 mL of antifoam/L of 1 N HCl, the performance of a…
The many A 5 B 3 phases that exhibit hexagonal Mn 5 Si 3 -type structures by and large have a nearly unique abilities to bind diverse heteratoms Z in a preformed cavity within a chain of confacial trigonal antiprisms of A. The historical development of this chemistry as interstitially stabilized Nowotny phases and rec…
A new poly(ester amide) derived from L-alanine has been synthesized and characterized. The polymer has good fiber- and film-forming properties, as well as other characteristics like thermal stability and solubility in chloroform, which enhance its processing facilities. Degradation studies show that both pH and temper…
Xylan with glucuronic acid functionalities, separated from birchwood, was converted into hydrogels by dissolving it together with chitosan in acidic conditions. The hydrogels were formed at certain xylan/chitosan compositions. The mechanism of the gel formation was investigated with FTIR. Complexation between glucuron…
The regulation of Escherichia coli glutamine synthetase (GS) by reversible adenylylation has provided one of the classical paradigms for signal transduction by cyclic cascades. Yet, many mechanistic features of this regulation remain to be elucidated. We examined the regulation of GS adenylylation state in a reconstit…