Materials Literature
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New siloxane-containing poly(azomethine-ester)s were synthesized by polycondensation reactions in solution, starting from three different azomethine mesogenic bisphenols: 4, 4'-oxo-bis(4-hydroxybenzylideneaniline), 1, 4-bis(4-hydroxybenzylideneamino)-phenylene, and 4, 4'-methylene-bis(4-hydroxybenzylideneaniline), and…
A commercial TiO 2 ‐excess BaTiO 3 powder has been sintered and its microstructure analyzed for crystallographic facetting via both scanning and transmission electron microscopy (SEM and TEM). Facetted grain surfaces are developed initially from {111} at a low temperature of 1215°C, which are then altered to {111} and…
The micro and macromechanical transformation behavior of single and polycrystalline shape memory alloys was investigated using in situ optical microscopy. An interference filter was used on the microscope to enhance observation of grain boundaries and martensitic plate formation and growth. Experiments on CuAlMnZn pol…
Modeling the effects of stress birefringence is critical for polarization sensitive optical systems. Optical design and optomechanical software tools to model stress birefringence are discussed and illustrated for three examples. The first example compares retardance in calcium fluoride lenses as a function of shape.…
This study reports the covalent immobilization of poly(acrylic acid) (PAAC) onto thin films deposited using radio-frequency glow discharge from a vapor of n -heptylamine (HApp). The successful immobilization of PAAC onto HApp was demonstrated by XPS analyses and AFM colloid probe force measurements. The force profiles…
Ab initio calculations of organic and organometallic molecules at RHF, B3LYP and MP2 levels and 6-31G(d), 6-31+G(d), 6-311G(d) and 6-311+G(d) basis sets were executed. They were used to estimate the 35 Cl NQR frequencies of these molecules. A satisfactory agreement between experimental and estimated NQR frequencies wa…
Galvanic influence of Alloy 33 (UNS R20033) and titanium (Grade 2) on copper was studied in lithium bromide (LiBr) solutions (400, 700, and 850 g/L chromate containing commercial solution). Temperature effect was also analyzed by imposing a heating/cooling cycle to the samples during a 10-h period (from 25°C to 80°C a…
The densification of aluminum nitride using Ca 12 Al 14 O 33 as a sintering aid has been studied with emphasis on the effect of using coarse or fine powder, the amount of sintering aid, the sintering temperature, and embedding. Both crystalline and amorphous grain boundary phases were observed. Significant weight loss…
Abstract A useful and desirable method of synthesizing nanoscale organic‐inorganic composites is to intercalate polymers into layered silicates by melt intercalation. Nanocomposites of poly(ethylene oxide) with a sodium montmorillonite and an organoions exchanged bentonite have been prepared by melt intercalation. The…
A Landau-Zener multi-crossing method has been used to investigate the tunnel splittings in high-quality Mn 12 -acetate single crystals in the pure quantum relaxation regime and for fields applied parallel to the magnetic easy axis. With this method several individual tunneling resonances have been studied over a broad…
Dissolution of BaCO 3 and its effect on the dispersion behavior of aqueous BaCO 3 suspensions at various pH values have been investigated. The amount of leached Ba 2+ decreases with increasing pH value, which agrees with thermodynamically calculated results. The dissolution of BaCO 3 also causes an increase in pH valu…
We have recently reported the synthesis of one-dimensional nanobelt structures of ZnO, SnO2, In2O3, CdO, Ga2O3, and PbO2 by evaporating the desired commercial metal oxide powders at high temperatures (Science (2001), 291, 1947). The as-synthesized oxide nanobelts are pure, structurally uniform, single crystalline, and…
We present recent results on frequency upconversion (UPC) obtained in fluoroindate glasses (FIG) doped with Ho 3+ , Tm 3+ and Nd 3+ ions and codoped with Pr 3+ /Nd 3+ and Yb 3+ /Tb 3+ ions. The results for the Ho 3+ -doped samples show strong evidence of energy transfer (ET) between Ho 3+ ions resonantly excited at 64…
Cooperative interactions within ion-pair networks of hyperthermostable proteins are thought to be a major determinant for extreme protein stability. While the favorable thermodynamic contributions of optimized electrostatics in general as well as those of pairwise interactions have been documented, cooperativity betwe…
Lewis-base adducts of tris(β -diketonato)lanthanide(III) complexes were prepared, where the β -diketone is para -alkoxy-substituted 1,3-diphenyl-1,3-propanedione. These compounds are the first examples of liquid crystalline lanthanide complexes in which the mesomorphism is introduced via a β -diketonate ligand. Depend…
Orthorhombic and rhombohedral single nanocrystalline KNbO3 with different morphologies was synthesized respectively at a relatively low temperature by simply changing the reaction solvent; a conceivable reaction process was illustrated based on the finding of a hexahedral intermediate product during the formation of K…
Thin films of CuPc of various thicknesses have been deposited ontoclean glass substrates using thermal evaporation technique at roomtemperature. The structural studies, using X-ray diffractometry and IR spectralanalysis, showed that the films are mainly of β- form with preferentialorientation of the plane (100). The d…
This research was carried out in three of the most important basins of the Colombian Amazon (Upper Solimões, Iça and Japurá Rivers). The creeks and lakes that were studied contain abundant diatom species, particularly those of the genus Eunotia. Ten species are described; five of them are registered for the first time…
Abstract Substrate‐supported polythianaphthene (PTN) films have been electrochemically synthesized by direct oxidation of thianaphthene on platinum or stainless steel electrode in mixed electrolytes of boron trifluoride diethyl etherate (BFEE) and trifluoroacetic acid (TFA). The oxidation potentials of the monomer in…
There is a current need for a small diameter vascular graft due to the limited supply of autogenous grafts and the failure of synthetic grafts due to thrombosis and/or intimal hyperplasia. The use of living cells and tissues to fabricate a small diameter graft (i.e., tissue engineered blood vessel, TEBV) could be usef…