Materials Literature
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Various macrokinetic models, namely, the Avrami, the Tobin, and the Ozawa models, were applied to describe the crystallization process of syndiotactic polypropylene (s-PP) under nonisothermal conditions. Both Avrami and Tobin models were shown to provide a fair description of the experimental data. The Avrami exponent…
Highly substituted porphyrins exhibit significantly distorted, nonplanar conformations in the solid state. The crystallographically determined degree of nonplanarity correlates with a bathochromic shift of the absorption maxima in solution. In addition, nonplanar porphyrins with meso aryl groups show increasing in-pla…
Reaction of 3-(2-pyridyl)pyrazole with 3,3′-bis(bromomethyl)biphenyl resulted in the new ligand L1 which contains two bidentate chelating pyrazolyl/pyridine fragments separated by a meta-biphenyl spacer; this ligand is designed to act only as a bridging ligand, as the two bidentate sites are too far apart to co-ordina…
The effect of entanglements on the glass transition and structural relaxation behaviors has been studied for polystyrene (PS) and phenolphthalein poly(ether sulfone) (PES-C) samples by fast evaporation of the solution of concentrations varying from above the overlapping concentration to far below it, and compared to t…
The influences of solution pH, cation concentration, treatment temperature, time, and ZnO/Ga2O3 molar ratio of the starting solution on the crystallite size, morphology, lattice parameters and chemical composition of hydrothermally synthesized ZnGa2O4 spinel particles were investigated. Nanocrystalline ZnGa2O4 spinel…
A series of tri-component copolymers was synthesized by ring opening copolymerization of cyclic lactones, i.e. glycolide, L-lactide, and caprolactone, using stannous octoate as a catalyst. Various techniques, including FT-IR, 1H NMR, DSC, X-ray diffraction, tensile strength, and contact angle measurements, were used t…
A porous polyurethane vascular prosthesis with an internal diameter of 5 mm was studied. The graft carries a coating of immobilized dipyridamole (Persantin(R)) on the surface of its lumen. Dipyridamole is a potent nontoxic inhibitor of platelet activation/aggregation, and also a strong inhibitor of vascular smooth mus…
Compositional and temperature dependencies of saturation magnetization (M/sub s/) and uniaxial magnetocrystalline anisotropy (K/sub u/) are determined using single crystal CoCr-alloy thin films. Temperature dependencies of M/sub s/ and K/sub u/ are stronger with increasing Cr content. M/sub s/(OK) and Curie temperatur…
Differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and small-angle neutron and X-ray scattering (SANS and SAXS, respectively) have been used to investigate the solid-state morphology of blends of linear (high-density) and model short-chain branched (linear-low-density) polyethylenes (HDPE…
The properties of the [Ru(NH3)5NO]3+ and [Ru(CN)5NO]2− ions are investigated by density functional theory and compared with those of [Fe(CN)5NO]2−. DFT calculations show that the electronic ground-state potential surface of these nitrosyl complexes has local minima (metastable states) with oxygen-bonded NO (MS1), i.e.…
The control of the polymorphism and architectural crystal assembly of calcium carbonate minerals in gels formed by means of collagenous matrices with entrapped polypeptides is reported. It has been observed that the calcium carbonate polymorphic selectivity is related to the local supersaturation within the microenvir…
Supercritical carbon dioxide (CO2) was used in extrusion for the improvement of polymer blend properties. Various extruder configurations using a twin-screw extruder and a single-screw extruder were designed for investigating the effects of dissolved supercritical CO2 on the viscosity and morphological properties of p…
1D crystals of lanthanide halides of the form LnCl3 (Ln = La, Nd, Sm, Eu, Gd, Tb or Yb) have been inserted into single-walled carbon nanotubes (SWNTs) using the molten salt capillary filling method; ca. 20–40% of all the observed SWNTs were filled with melts in the range 650–910 °C with no observable damage to the car…
Pancreatic juice is supersaturated with calcium carbonate. Calcite crystals therefore may occur, obstruct pancreatic ducts, and finally cause a lithiasis. Human lithostathine, a protein synthesized by the pancreas, inhibits the growth of calcite crystals by inducing a habit modification: the rhombohedral (10 14) usual…
A wire beam electrode (WBE) has been used, in conjunction with the electrochemical noise resistance method, to determine the kinetics of nonuniform corrosion of mild steel in a carbon dioxide saturated brine. Local electrochemical parameters including corrosion potential, galvanic current, and electrochemical noise re…
Electroactive conducting polymers (ECPs) continue to be of considerable interest as components of corrosion‐resistant coating systems. ECPs, in addition to being conductive, are redox active materials, typically with potentials that are positive of iron and aluminum. Thus, as with chromate, interesting and potentially…
Submicron-sized anionic polystyrene latices have been coated with uniform layers of copper compounds by aging dispersions of the polymer colloid in the presence of aqueous solutions of Cu(NO3)2, urea, and poly(N-vinylpyrrolidone) at 85 °C. The thickness and morphology of the deposited layers can be altered by suitable…
We have found a photoinduced phase transition (PIPT) in the mixed-valence (MV) gold complex ${\mathrm{Cs}}_{2}{\mathrm{Au}}_{2}{\mathrm{Br}}_{6}$ from the MV state (ambient pressure phase) to the single-valence (SV) phase (high-pressure phase) in the pressure region from 6.4 to 6.8 GPa. We have observed an accumulatio…
Coordination to the axial position of the metalloporphyrin Ru(TTP)(CO) is an effective means to end-cap the 1,2-bis(4,4′-dipyridinium)ethane dication·dibenzo[24]- crown-8 [2]pseudo-rotaxane and generate the stable porphyrinic [2]rotaxane 4.
A convenient procedure for the synthesis of porphyrin derivative dyads is described. The dyads consist of a free base porphyrin covalently linked to a zinc porphyrin or ferrocene by an amide bond. 5-(4-Substituted phenyl)-10,15,20-tris(4-methylphenyl) porphyrins were synthesized from meso-(4-methylphenyl) dipyrrometha…