Materials Literature
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Abstract The application of some polymers as nucleating agents for polypropylene has been examined. Among various polymeric nucleating agents, polycyclopentene was found to be a superior nucleating agent to typical organic nucleating agents. When polycyclopentene was added to polypropylene, the crystallization tempera…
A quantitative study of the effect of electric field on the stripe domains formed by layer deformation in chiral smectic A liquid crystals is presented. X-ray diffraction studies reveal that the angle between the layer normals in adjacent stripe domains increases with increasing electric field. A simple model is prese…
Thin films of (La1−xCax)MnO3 prepared by laser ablation deposition are ferromagnetic when 0.2≤x≤0.5 with Tc≊250 K. These films show strong Faraday rotation both in the vicinity of the 2p(O)→3d(Mn) charge-transfer absorption at approximately 3.0 eV (θF≳40 000°/cm), and in the vicinity of the 3d(t2g)→3d(eg) excitation a…
We demonstrate that the Hubbard correlation among Ni $3d$ electrons is able to reproduce the insulating character of NiO, the correct value of the gap, the orbital character of the valence band edge, and the presence of satellite structures. We have determined the quasiparticle spectra starting from the complex single…
Abstract The properties of the composite of polypropylene (PP) and chemithermomechanical pulp reactively treated with bismaleimide‐modified PP or premodified pulp have been investigated. The results were compared with the properties of unmodified composites of PP and pulp. The effect of some flame retardants on the pr…
We report the production of smooth and well-ordered C(100) surfaces by exposure to a pure hydrogen plasma. A two domain 2×1 surface reconstruction is observed by low energy electron diffraction with half-order spots visible using incident electrons with energies as low as 13 eV. High-resolution electron energy loss sp…
A large cavity is found in the remarkably stable, self-assembled dimers that form spontaneously from covalently linked zinc porphyrin/pyridine compounds. This cavity recognizes terephthalamides through the formation of hydrogen bonds (picture right; R = NH(alkyl), N(alkyl)2).
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…