Materials Literature
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Synthetic polyamides (nylons) are generally hard to be decomposed under natural environmental conditions either through biological or hydrolytic processes.'-4 Their high resistance to degradation is caused mainly by the high symmetry of their molecular structures and strong interchain hydrogen bondings, which result i…
Two-stage melting is observed in a confined monolayer of colloidal particles with dipole interactions. The defects observed are consistent with those predicted for the crystal, hexatic, and fluid phases. The bond-orientational correlation function shows a clear hexatic-to-fluid transition, and the ensemble's potential…
Abstract Blends of poly(3‐hydroxybutyrate)–poly(3‐hydroxyvalerate) (PHBV) and poly( L ‐lactides) (PLLA) have been prepared by solvent casting. Compatibility, thermal behavior, morphology, and mechanical properties of systems with various compositions were studied using differential scanning calorimetry (DSC), dynamic…
An upswing for porphyrin isomers! Until the discovery of porphycene, the possibility that tetrapyrrolic macrocycles isomeric to porphyrin could exist was completely ignored. Now a new porphyrin isomer, termed corrphycene, has been synthesized as its tetraethyltetramethyl derivative 1 through a reductive carbonyl coupl…
The influence of local order around the titanium site on Ti 2p X-ray absorption spectra is studied for rutile, anatase and brookite. This is done by a configuration interaction based calculation of Ti L 2,3 X-ray absorption edge shapes, explicitly taking into account the exact first-neighbour surroundings of the catio…
We have applied the Finite Element Method to the self-consistent electronic structure calculations of molecules and solids for the first time. In this approach all the calculations are performed in "real space" and the use of non-uniform mesh is made possible, thus enabling us to deal with localized systems with ease.…
Thin films of ZnO have been deposited on glass and silicon substrates by the pulsed laser deposition technique employing a KrF laser (λ=248 nm). The influence of the deposition parameters, such as substrate temperature, oxygen pressure, and laser fluence on the properties of the grown films, has been studied. All the…
A new technique is required which enables tailoring of the morphology of a metallic nanostructured material down to the 10 nm length scale. Using nanoporous nuclear track etched membranes as templates for electrodeposition, an assembly of wires with diameters as low as 30 nm could be obtained. Alternating the electrod…
In situ atomic force microscope observations were made of the adsorption of anions (1- or 2-) of the organic diacid 5-benzoyl-4-hydroxy-2-methoxybenzenesulfonic acid from aqueous solution onto the (0001) surface of hydrotalcite (HT), a layered clay. This adsorption process is believed to mimic the ion-exchange reactio…
Competing magnetically ordered structures in polymerized orthorhombic A1C60 are studied. A mean-field theory for the equilibrium phases is developed using an Ising model and a classical Heisenberg model to describe the competition between inter- and intra-chain magnetic order in the solid. In the Ising model, the limi…
The atomically smooth SrTiO(3) (100) with steps one unit cell in height was obtained by treating the crystal surface with a pH-controlled NH(4)F-HF solution. The homoepitaxy of SrTiO(3) film on the crystal surface proceeds in a perfect layer-by-layer mode as verified by reflection high-energy electron diffraction and…
Abstract A series of thin films of an axially substituted silicon phthalocyanine, PcSi(OsiCH3C6H5OH)2, were made by spin coating and vacuum evaporation techniques. Electronics spectra of these films exhibit a bathochromic shift of the Q band compared with that of a chloroform solution. This bathochromic shift is ascri…
Summary Jarring implies heavy loads on the drillstring. The highest load on the drillpipe before jarring is at the rig floor. This paper discusses loads on drillpipe before, under, and after jarring. We show that for most situations, the shock wave from the jar impact does not imply additional load on the drillpipe co…
Article Magnesium-Gadolinium and Magnesium - Gadolinium- Yttrium Alloys / Magnesium-Gadolinium- und Magnesium-Gadolinium — Yttrium Legierungen was published on December 1, 1994 in the journal International Journal of Materials Research (volume 85, issue 12).
Abstract 125 Te nuclear spin relaxation (NSR) and electrical conductivity measurements were performed on ultrapure single-crystalline paratellurite (α -TeO 2 ) between about 50 K and the melting point (1007 K) at various oxygen partial pressures (1 bar -10 -4 bar). At elevated temperatures the NSR rate 1 / T 1 and con…
Abstract Sterically overcrowded unsymmetrical porphyrins bearing ten and eleven phenyl groups are synthesized using mixed condensation of diphenylpyrrole with benzaldehyde and formaldehyde and characterized by FAB-MS, UV-VIS, and NMR spectra.
We have grown powders and ceramics of Lead Titanate (PbTiO3) doped with Lanthanum and Copper. The incorporation of Cu ions does not change the lattice properties of PbTiO3: La. On the other hand, we demonstrate that the conductivity properties of PbTiO3: La, Cu may be swept over 12 orders of magnitude.
Diamond film thermistors were fabricated from polycrystalline diamond films grown on sintered Si3N4 by microwave plasma chemical vapor deposition. An undoped diamond layer and a zigzag or rectangular pattern of B-doped semiconducting diamond were successively deposited by a selected-area deposition technique. For ohmi…
The hysteresis behaviour of the nematic-cholesteric phase transition in liquid crystals is closely connected with the alignment of the liquid crystal molecules on the surfaces of treated solid substrates. We have investigated the hysteresis as a function of rubbing strength, using rubbing technology that controls the…
Abstract The effect of end conditions and testing procedures on the measured strength of 100- by 200-mm (4- by 8-in.) concrete cylinders were evaluated. Concretes representing three strength levels: 50, 75, and 120 MPa (7000, 11 000, and 17 000 psi) were prepared. Cylinder end conditions included grinding and capping…