Materials Literature
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Excellent mechanical properties such as high-strength, low weight, fatigue life, and impact resistance, as well as advanced manufacturing methods and flexibility of the stacking sequence make polymer matrix composites attractive candidates for use in several performance-oriented structures. However, relatively little…
We examine collective effects in an ensemble of close-packed ultrasmall CdSe quantum dots by comparison of optical properties of dense and diluted thin film composites. Studies of absorption spectra, photoluminescence excitation spectra and electroabsorption of diluted and condensed structures along with numerical sim…
Micro- vs. macro-phase separation in binary blends of poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide) diblock copolymers, H. Frielinghaus, N. Hermsdorf, K. Almdal, K. Mortensen, L. Messé, L. Corvazier, J. P. A. Fairclough, A. J. Ryan, P. D. Olmsted, I. W. Hamley
The spectra of porphyrins meso-substituted by 4-dimethylaminophenyl groups and protonated at the central pyrrole nitrogens show strong new bands in the visible (450–600 nm) and far-red (700–780 nm). On complete protonation the observed spectra are essentially normal except for enhanced intensity in the farthest red ba…
Dense, fine‐grained 0.65PMN·0.35PT ceramics were fabricated by reactive sintering of a mixture of metal oxides at 1000°C. The fine nature of the precursor powder resulted in rapid, direct transformation to perovskite PMN–PT at 600°C. Because of the fine structure of the perovskite, no excess PbO was required for sinte…
The purpose of this work is to establish the critical surface conditions leading to the initiation of stress-corrosion cracks on the as-supplied surfaces of three unidirectional E-glass/polymer composites with modified polyester, epoxy and vinyl ester resins subjected to a nitric acid solution without mechanical loads…
Molybdenum hemicarbide was investigated by angle-dispersive, x-ray diffraction in a diamond anvil cell at high pressure and by theoretical methods. Mo 2 C is highly incompressible with a bulk modulus of 307(5) GPa and a first pressure derivative of 6.2(3). Ab initio calculations give values ranging from 291 to 307 GPa…
Carbon nanotubes are known to be metallic or semiconducting, depending on their helicity and diameter. However, boron nitride (BN) nanotubes are the only nanotubular product known to date that are predicted to have stable insulating properties that are independent of their atomic structure and morphology. Thus, the BN…
Bis-dioxolene bridged dinuclear metal complexes of general formula M2(CTH)2(diox-diox)(PF6)n (n = 2, 3; M = Co(III), Cr(III); CTH = tetraazamacrocycle) have been synthesized using the bis-bidentate ligand 5,5'-di-tert-butyl-3,3',4,4'-tetrahydroxybiphenyl. These complexes were characterized by means of ESR, UV-vis, tem…
Anodic alumina membranes (AAMs) with highly ordered nanochannel arrays were prepared by anodizing aluminum in acid solutions. X-ray diffraction reveals the amorphous nature of AAMs. The photoluminescence (PL) excitation spectra of AAMs consist of a broad band centred at 235 nm and a narrow band peaking around 360 nm u…
Thermogravimetric analysis was carried out to investigate the thermal decomposition behavior of a commercial fire retarded (FR) and a non-fire retarded (NFR) flexible polyurethane foam. The effects of the heating rate and the reaction atmosphere on the thermal decomposition process were studied at three different heat…
The x-ray crystallographic structure of selenomethionyl cytosine-5'-monophosphate-acylneuraminate synthetase (CMP-NeuAc synthetase) from Neisseria meningitidis has been determined at 2.0-A resolution using multiple-wavelength anomalous dispersion phasing, and a second structure, in the presence of the substrate analog…
The comonomer composition and its distribution have been investigated for poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HH)], which was bacterially synthesized by Ralstonia eutropha from coconut oil as a carbon source. Using a chloroform/heptane mixed solvent, they were fractionated into several fractions w…
The clinical usefulness of antitumor chemotherapy has been strongly limited by the lack of specificity of most anticancer drugs, which act also against healthy cells. The aim of this work was to design, synthesize, and evaluate a macromolecular prodrug of Cytarabine, a known antitumor drug, which is a specific substra…
The effects of lead content on the structure and electrical properties of Pb((Zn 1/3 Nb 2/3 ) 0.5 (Zr 0.47 Ti 0.53 ) 0.5 )O 3 ceramics were investigated. Specimens with various lead concentrations were prepared by the conventional oxide‐mixing method. When the lead concentration was slightly less than the stoichiometr…
Abstract The sol—gel reaction of tetraethoxysilane produced the fine and well-dispersed in situ silica particles in the “green” natural rubber (NR) matrix before curing. This new method was developed for a NR/silica composite material, and a good reinforcement effect of in situ silica was observed on the NR vulcanizat…
A series of novel human-made functional fibers (biofibers) based on chitin and chitosan are prepared by the wet-spinning and the post chemical modification of chitosan fiber. The wet-spinning gives rise to a series of biofibers: chitin, chitosan, chitin-cellulose, chitosan-cellulose, chitin-silk fibroin, chitin-glycos…
Production of chitosan was conducted using two Mucoralean strains, Mucor racemosus and Cunninghamella elegans. Chitosan was extracted from mycelia of M. racemosus and C. elegans at different growth phases on YPD medium. In both fungi, chitosan was rapidly produced, while highest yield of extractable chitosan was found…
Gear hobbing is an efficient method to manufacture high quality and performance toothed wheels, although it is associated with complicated process kinematics, chip formation and tool wear mechanisms. The variant cutting contribution of each hob tooth to the gear gaps formation might lead to an uneven wear distribution…
The dry etching mechanism of lead zirconate titanate (PZT) films was studied in high density CF 4 and Cl 2 /CF 4 inductively coupled plasmas. The concentrations of atomic Cl and F as well as the flux and energy of bombarding ions were monitored as a function of etching parameters such as etching gas ratio, substrate b…