Materials Literature
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A UV-vis microspectroscopy methodology for monitoring the speciation and macrodistribution of catalyst-precursor species inside catalyst-support bodies at the initial stages of catalyst preparation has been developed. The setup is based upon optical-fiber technology and allows spatially resolved analysis of bisected c…
It has been well accepted that polyethylene imine (PEI) is an effective dispersant for silicon carbide (SiC) in aqueous media. However, after the addition of sintering additives (Al 2 O 3 and Y 2 O 3 ), this dispersing effect is reduced significantly. In this work, a second dispersant, citric acid, was used to resolve…
Palladium-surface-metallized polyimide films were prepared by an unusual macromolecular-matrix-mediated, single-stage synthetic protocol first reported by Taylor et al. ( J. Am. Chem. Soc. 1980, 102, 876). Several Pd(II) complexes, [PdCl 2 (SMe 2 ) 2 ], [PdBr 2 (SMe 2 ) 2 ], and Pd(CF 3 COO) 2, were dissolved in the p…
Abstract To improve the processability and prevent the thermal degradation of poly(vinyl chloride) (PVC), various plasticizers and heat stabilizers have to be compounded. Phthalic plasticizers and metal soap stabilizers are usually used with epoxides as costabilizers. Epoxidized soybean oil (ESO), is one of the most c…
In this paper, poly(vinyl pyrrolidone) (PVP) was selected as a dispersant for preparation of high concentrated silicon carbide (SiC) slurries in an ethanol (EtOH)/methyl ethylene ketone (MEK) solvent system. The interactions between (1) solvent and powders, (2) the solvent and dispersant, and (3) dispersant and powder…
Oxidation of SiC compositionally graded (SCGed) graphite coated with HfO 2 derived from HfCl 4 by a sol–gel process was performed at 1500° and 1600°C in a flowing gas mixture of Ar and O 2 (80/20 kPa). SCGed graphite was produced by reaction of graphite with either molten Si or SiO gas at 1450°C. The sol–gel‐derived H…
The phenomenon of Cavitation gives rise to a number of interesting physicalchemical effects which can be employed to isolate and oxidize contaminants in water. The micro bubbles generated by pressure pulses inside a liquid act as small reactors, reaching extreme P-T conditions during short periods of time and generati…
Abstract Mineral scales are formed in cooling water systems and they cause heat transfer problems. Much research has been carried out to reduce the carbonate and sulphate scales of calcium. To inhibit the scale formation in cooling water systems, vinyl acetate–acrylic acid (VA–AA) and vinyl acetate– methacrylic acid (…
The bonding structure of highly ordered fullerenelike (FL) carbon nitride $(\mathrm{C}{\mathrm{N}}_{x})$ thin films has been assessed by x-ray absorption near-edge spectroscopy (XANES). Samples with different degrees of FL character have been analyzed to discern spectral signatures related to the FL microstructure. Th…
In our continuing efforts to prepare macroporous monoliths of functional inorganic materials through novel template-free routes, we present here routes to porous NiO starting from Ni−Zn oxalates, and to porous ZnFe 2 O 4 starting from Zn−Fe oxalates. Monolithic Ni has been prepared from porous NiO by hydrogen reductio…
Porous Si 3 N 4 ceramics were synthesized by pressureless sintering of green compacts prepared using slip casting of slurries containing Si 3 N 4 , 5 wt% Y 2 O 3 +2 wt% Al 2 O 3 , and 0–60% organic whiskers composed of phenol–formaldehyde resin with solids loading up to 60 wt%. Rheological properties of slurries were…
The physical and mechanical properties of 12 glasses from the Y–(Mg,Ca)–Si–Al–O–N and (Mg,Ca)–Si–Al–O–N systems were investigated. The effect of the substitution of magnesium for calcium through two series of glasses, one consisting of oxides glasses and the other of glasses containing 6 at.% of nitrogen (15 e/o N), w…
Oriented mesostructured surfactant-silica nanocomposite thin films with a 2D hexagonal mesostructure of cylindrical micelles were prepared by evaporation-induced self-assembly using two different nonionic Brij surfactants and studied by small-angle X-ray scattering in symmetric reflection (SRSAXS) and grazing incidenc…
Yb 3+ , Ho 3+ : Lu 2 O 3 nanocrystalline powders were synthesized by a reverse‐strike co‐precipitation method using NH 4 HCO 3 and NH 3 ·H 2 O as precipitators. X‐ray diffraction analysis and field emission scanning electron microscopy observation showed that the phase composition of the powders was cubic and the part…
Abstract The novel nanosuperabsorbent copolymer (NSAP) was synthesized by grafting copolymerization of acrylamide (AM) and acrylic acid (AA) onto starch with montmorillonite (MMT) initiated using 60 Co γ‐ray irradiation. NSAP was characterized by IR spectroscopy and X‐ray diffraction (XRD). Different synthesis paramet…
Abstract Carboxymethylation of cellulosic material (average degree of polymerization 2600) containing 76.5% cellulose and 23.6% xylose isolated from cotton ( Gossypium ) linters was studied under varying reaction conditions with respect to maximum degree of substitution (DS). The influence of reaction conditions on th…
Excited states of free-base porphyrin isomers, porphycene (Pc), corrphycene (Cor), and hemiporphycene (hPc), were studied by the Symmetry-Adapted Cluster (SAC)/SAC-Configuration Interaction (CI) method. The absorption peaks of the porphyrin isomers were assigned on the basis of the SAC-CI spectra. The X, Y, X', and Y'…
The equilibrium swelling and phase behavior of monodomain nematic networks in nonmesomorphic solvents have been investigated as a function of temperature. The gels thermoreversibly undergo a phase transition between the swollen isotropic and shrunken monodomain nematic states with accompanying an anisotropic shape cha…
Acetate kinase catalyzes the reversible magnesium-dependent synthesis of acetyl phosphate by transfer of the ATP gamma-phosphoryl group to acetate. Inspection of the crystal structure of the Methanosarcina thermophila enzyme containing only ADP revealed a solvent-accessible hydrophobic pocket formed by residues Val(93…
Abstract A poly(vinyl alcohol) (PVA)/silica (SiO 2 ) nanocomposite was prepared with a novel self‐assembled monolayer technique, and its morphology and thermal properties were studied with different material characterization instruments. The treated SiO 2 nanoparticles were dispersed in the PVA matrix homogeneously, a…