Materials Literature
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New photoisomerizable chiral dopants have been studied. The dopants used were menthone derivatives, a chiral stilbene derivative and a nematic copolymer of a menthone derivative and a benzoyloxybenzonitrile derivative. NMR, HPLC and UV results showed that the E-Z-isomerization of all the compounds indicated proceeded…
The structures of carbonaceous deposits obtained through laser ablations using targets composed of C, Ni, and Co under various Ar gas pressures were studied. The pressure dependence of the target's surface morphology and the structure was also studied. When the pressure was 100 Torr or below, only carbon was evaporate…
Polystyrene/polyethylene composites have been prepared by the heterogeneous radical polymerization of styrene within supercritical carbon dioxide−swollen high density polyethylene (HDPE) substrates. Composition of the composites can be controlled with reaction time and initial ratio of styrene to HDPE. The polystyrene…
Alloys of NiTi have gained popularity in biomedical applications; however, Ni is known to cause toxic and allergic reactions in the body, and concerns have been expressed regarding the material's biocompatibility. In this study, coupons of equiatomic NiTi were prepared by four methods, namely, mechanically polishing t…
A large single crystal (about 30 mm in diameter by 20 mm long) of the Pb(Zn 1/3 Nb 2/3 )O 3 –PbTiO 3 (PZN–PT) solid solution system was successfully grown using the vertical Bridgeman method and its properties were investigated. No defects such as flux inclusions were observed on as-polished {100} plates, except in a…
MCM-41 materials of six different pore diameters were prepared and characterized using X-ray diffraction, transmission electron microscopy, helium pycnometry, small-angle neutron scattering, and gas adsorption (argon at 77.4 and 87.4 K, nitrogen and oxygen at 77.4 K, and carbon dioxide at 194.6 K). A recent molecular…
The use of nitroxide-mediated ‘living’ free radical procedures as a synthetic tool for obtaining polymers with well defined and complex macromolecular architectures is discussed. The preparation of linear homo, block, and random co-polymers by ‘living’ free radical procedures have been demonstrated for a variety of sy…
Three bimetallic assemblies, PPh 4 [Ni(pn) 2 ][M(CN) 6 ]·H 2 O (M = Fe ( 1 ), Cr ( 2 ), Co ( 3 ); pn = rac- 1,2-diaminopropane), have been prepared and structurally and magnetically characterized. Assembly 2 crystallizes in the monoclinic system of the space group P 2/ c (No. 13) with a = 12.927(2) Å, b = 8.454(2) Å,…
Nanocomposites, consisting of a hard magnetic rare earth–transition metal phase exchange coupled to soft magnetic α-Fe or α-(Fe,Co), exhibit enhancement of the remanent magnetization due to exchange coupling across interfaces between grains. Modeling studies have shown that crystallite sizes of less than 20 nm are gen…
Abstract Fusion-bonded epoxy coating is extensively used to enhance the corrosion resistance of reinforcing steel. The bond strength between these bars and the concrete is expected to be less than that of the uncoated bars and it may be further impaired due to prolonged exposure to thermal variations. This investigati…
The die upset of hot pressed NdFeB magnets modifies the equiaxed grains to platelets, develops the c-axis texture parallel to press direction, and improves magnetic properties. The mechanism of c-axis alignment has been suggested to be a combination of grain-boundary sliding and anisotropic grain growth in a direction…
An analysis is given of recent electron paramagnetic resonance (EPR) experiments in manganite materials displaying colossal magnetoresistance behavior. These experiments have established that in highly homogeneous samples characterized by a single resonance line, the EPR linewidths above the critical region associated…
Oxomolybdenum phthalocyanine (MoOPc) and tin phthalocyanine (SnPc), which both have a pyramidal molecular shape, were deposited onto sapphire by organic molecular beam deposition. The crystalline phase of these films was determined to be triclinic by X-ray diffraction and absorption spectra with reference to previousl…
Electrical charging of insulating samples during XPS is of direct concern for referencing the binding energy scale. Results are presented on charging of composite insulating samples that consist of an organic overlayer of polystyrene (PS) or polydimethylsiloxane (PDMS) deposited on NaCl particles. The samples were ana…
A formulation consisting of 300ppm sodium salt of phenyl phosphonic acid (PPA) and 50ppm Zn 2+ is 95 per cent efficient in inhibiting the corrosion of mild steel in a neutral aqueous environment containing 60ppm chloride. A higher concentration of Zn 2+ lowered inhibition efficiency. This is due to the formation of an…
The temperature dependence of the magnetic moment measured by a superconducting quantum interference device magnetometer in ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Na}}_{x}{\mathrm{MnO}}_{3}$ $(x=0.1,\phantom{\rule{0ex}{0ex}}0.15,\phantom{\rule{0ex}{0ex}}0.2)$ ferromagnetic perovskites is compared with the temperatu…
The objective of this study was to provide a contribution to a database on the heavy metal status of tropical soils. We assessed the partitioning of Al, Cd, Cu, Fe, Mn, Pb, and Zn in A horizons of Costa Rican soils used for coffee cultivation. These soils are subject to heavy metal inputs as a result of the regular us…
Experiments of quasi static hydrostatic and uniaxial strain compression, and of shock wave propagation performed on 9% and 17% porous aluminum are presented, analyzed, and compared. Quasi static experiments show the influence of coupling between void collapse and plasticity induced in the matrix on the material macros…
After the logging and fires of the late nineteenth century, the upland stump prairies of Michigan's Upper Peninsula, which had previously supported dense forest, have remained deforested. Surrounding areas in similar geomorphologic settings have returned to forest. We investigated whether soil B horizon properties hav…
We measure the refractive index and the absorption of porous silicon layers in the millimetric and submillimetric wavelength range using the terahertz time-domain spectroscopy technique. For the studied range of porosity (55%–76%), the refractive index of porous silicon is rather well described by mixture theories, in…