Materials Literature
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We report Monte Carlo simulations of the nematic-smectic phase transition for a system of hard spherocylinders with infinite length-to-diameter ratio. A finite-size scaling analysis suggests that this system undergoes a first-order phase transition. When combined with other simulations of the phase behavior of spheroc…
Monte Carlo (MC) simulations based exclusively on nearest-neighbor intermolecular interactions reveal the existence of stable long-range deformations and topological defects in a thin nematic film confined between two surfaces with antagonistic (normal and tangential) molecular orientations. Thus the MC technique allo…
We have developed a new compact retarding-potential Mott spin polarimeter and achieved an efficiency of 1.9×10−4 for gold target operating in 25 keV. A novel design of the retarding field electron optics with 0.59 sr collection solid angle for scattered electrons was adopted based on Monte Carlo calculations for the s…
4-Hexadecyloxyphenyl-4-substituted benzoates, Ia-d, and 4-substituted phenyl-4- hexadecyloxy benzoates, IIa-d, with the substituents CH3O, Cl, CN, and NO2, respectively, were prepared and characterized by infrared spectroscopy and the apparent solution dipole moment measured using cyclohexane as a solvent. Smectic A m…
Soluble polypyrrole (PPy) with high conductivity (27 S/cm) has been prepared by chemical polymerization of pyrrol monomer in the presence of β-naphthalene sulphonic acid (NSA) as a dopant. The solubility of the resulting conducting polymer of PPy-NSA in m-cresol increases with increasing the concentration of NSA in th…
2-Aza-21-carba-5,10,15,20-tetraarylporphyrin (CTPPH 2, inverted porphyrin) and its methylated derivatives, acting as ligands, can be structurally related to the following hypothetical tautomers: 2-aza-5,10,15,20-tetraphenyl-21-carbaporphyrin (2-NH-CTPPH); 2-aza-5,10,15,20-tetraphenyl-21-methyl-21-carbaporphyrin (21-H-…
Article A rational approach to the mechanisms of incrustation inhibition by polymeric additives / Wirkungsweise von polymeren Inkrustrationsinhibitoren was published on December 1, 1997 in the journal Tenside Surfactants Detergents (volume 34, issue 6).
We investigate the compatibilizing performance of a random copolymer in the melt state, using transmission electron microscopy. Blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) are chosen as a model system, and a random copolymer of styrene and methyl methacrylate (SMMA) with 70 wt % styrene is used as…
Ceramic samples of Ce 1− x Gd x O 2− y and yttria‐stabilized zirconia (YSZ) were prepared using solid‐state methods. Polished faces of disks of these materials were held in intimate contact in a reaction cell at temperatures ranging from 1000° to 1300°C for durations up to 72 h. XRD, SEM, and microprobe Raman techniqu…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTDivergent/Convergent Joint Approach with a Half-Protected Initiator Core To Synthesize Surface-Block DendrimersKeigo Aoi, Katsuhito Itoh, and Masahiko OkadaView Author Information Department of Applied Biological Sciences, Faculty o…
The corrosion behavior and strength degradation of alumina ceramics with 99%, 99.9%, and 99.99% Al 2 O 3 were studied in water at 300°C and 8.6 MPa for 1 to 10 d. The weight loss in alumina ceramics was mainly attributed to the dissolution of SiO 2 and Na 2 O grain‐boundary impurities. Intergranular corrosion proceede…
Fiber pushout tests were used to quantify the effects of fiber coating thickness on the mechanical properties of two model composite systems: a monazite‐coated (LaPO 4 ‐coated) alumina (Al 2 O 3 ) fiber in an Al 2 O 3 matrix and a LaPO 4 ‐coated yttrium aluminum garnet (YAG) fiber in an Al 2 O 3 matrix. Interface prop…
A model asphalt has been separated into two parts, asphaltene and maltene, through solvent extraction by n-heptane. The interactions of asphaltene and maltene with the triblock copolymer poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) were investigated by transmission electron microscopy (TEM), small-angle X-r…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTPolymeric Organic−Inorganic Hybrid Nanocomposites: Preparation of Polyimide-Modified Poly(silsesquioxane) Using Functionalized Poly(amic acid alkyl ester) PrecursorsJ. L. Hedrick, H.-J. Cha, R. D. Miller, D. Y. Yoon, H. R. Brown, S. Srinivasan, R. Di Pietro, R. F. Cook, J. P. H…
1 H NMR imaging has been used to monitor the enzymatic degradation of poly(3-hydroxybutyrate), PHB, and poly(3-hydroxybutyrate- co -23%-3-hydroxyvalerate), PHB/V, by PHB depolymerase B from Pseudomonas lemoignei . The samples examined were thin films of approximately 200 μm thickness produced by melt casting. Since on…
Previous studies from our laboratory have shown that deletion of residues 321 to 344 of the 9-2 isozyme of 2'-5'-oligoadenylate (2-5(A)) synthetase causes a loss of its enzyme activity (Ghosh, S. K., Kusari, J., Bandyopadhyay, S. K., Samanta, H., Kumar, R., and Sen, G. C. (1991) J. Biol. Chem. 266, 15293-15299). Seque…
We discuss spin and orbital ordering in the twofold orbital degenerate superexchange model in three dimensions relevant to perovskite transition metal oxides. We focus on the particular point on the classical phase diagram where orbital degeneracy is lifted by quantum effects exclusively. Dispersion and damping of the…
Abstract Electrically conductive polymer blends can be prepared by in situ polymerization of pyrrole within another polymer matrix. This may be accomplished using either electrochemical or chemical oxidative polymerization. This paper reviews the literature on this subject.
Micro-Raman spectra for PbZrxTi1—xO3 (PZT) with grain sizes of 60 and 40 nm have been obtained. The results show that the E(TO1) phonon mode of PbTiO3 (‘soft’ mode) displays a decrease in frequency and an increase in linewidth with increasing Zr concentration. A discontinuous behavior in the phonon energy for the soft…
Abstract Polypropylene (PP) composites were prepared with a constant volume fraction of a CaCO 3 filler, which was treated with eight trialkoxy functional silane coupling agents and the routinely used stearic acid, as comparison, The tensile properties of the composites were determined as a function of surface coverag…