Materials Literature
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Performed measurements showed that in Na0.5Bi0.5TiO3 single crystals the long-time variation of the electric permittivity is connected with the existence of polar regions. The size and dynamics of the polar regions change with temperature. These regions may be ordered in an external electric field.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-13 NMR investigation of local dynamics in bulk polymers at temperatures well above the glass-transition temperature. 3. cis-1,4-Polybutadiene and cis-1,4-polyisopreneR. Dejean de la Batie, F. Laupretre, and L. MonnerieCite this: Macromolecules 1989, 22, 1, 122–129Publ…
A supported Mn–porphyrin catalyst was prepared by strong adsorption of the tetracationic Mn[meso-tetra(4-N-methylpyridiniumyl) porphyrin](Cl)4+4Cl– on silica, and was found very efficient for cyclo-octene epoxidation (95% yield, 13 turnovers per min) and for alkane hydroxylation, with alcohol yields and alcohol: keton…
The structure of media whose short-range order cannot be extended crystallographically in flat space (disordered metallic and covalent systems, Frank-Kasper phases, quasicrystals, blue phases and various molecular phases) is describable in terms of distributions of defects in a crystal situated in a space of constant…
Long-wavelength magnetic excitations are investigated in the quasiperiodic layered structures consisting of alternating magnetic and nonmagnetic layers, distributed according to the recently introduced generalized Fibonacci sequences. Both periodic and real boundary conditions are used. Spin-wave spectra for Fibonacci…
A cyclic trinuclear porphyrin host has been synthesised; its binding properties show that it has a spacious cavity which prefers an open conformation but which can close around small bidentate ligands such as 4,4′-bipyridyl.
Extending a design concept for liquid-crystalline compounds with large lateral substituents, we have synthesized several new variants of twin compounds: lateral-terminal flexible bound, and lateral-lateral flexible bound with and without ring systems in the flexible spacer. X-ray investigations of the nematic phases o…
Experimental data on the electrical conductivity of conducting polymers is reviewed. Polyacetylene is regarded as a prototype and the conductivity is studied as a function of doping level, temperature, frequency and conjugation length. The consistency of the data with a model of anisotropic variable range hopping is p…
This brief history and review of liquid crystalline polyesters (LCPs) is limited to all-aromatic LCPs except for a description of the discovery of the first thermotropic polymer to be injection molded or melt spun and characterized as being liquid crystalline: an Eastman PET/PHB (p-hydroxybenzoic acid) copolyester (fi…
Microcapsules were prepared using a poly (L-lactic acid) (L = PLA), mol. wt. 43,200, by an emulsification and solvent evaporation technique. Phenobarbitone (PB) was used as a reference drug, (core to polymer ratio, 1:1). Both the o/w and w/o emulsion system were investigated in order to study microcapsule properties a…
Oxidative electropolymerization of cobalt and nickel complexes of tetra-aminophthalocyanine in dimethyl sulphoxide rapidly leads to electrode modification, and the thin polymeric coatings obtained by this method are highly electronically conductive under a wide variety of conditions.
"Encyclopedia of materials science and engineering." International Materials Reviews, 34(1), p. 246
Article The Hot Pressing of Dry-formed Wood-based Composites. Part II. A Simulation Model for Heat and Moisture Transfer, and Typical Results was published on January 1, 1989 in the journal Holzforschung (volume 43, issue 3).
Abstract Porphycene ( 2 ), a planar structural isomer of porphyrin ( 1 ) recognized and synthesized only recently, exhibits short N … N distances allowing exceptionally strong N‐H … N hydrogen bonds to be formed. Although the N 4 ‐coordination hole of 2 is smaller than that of 1 , the new tetrapyrrolic macrocycle is c…
New decagonal alloys in the Al–Ni–Fe and Al–Ni–Co systems have been produced by liquid quenching. Their formations extend in the ranges of 9 to 16 at% Ni and 9 to 21 at% Fe or Co. The whole replacement of Fe or Co in Al75Ni10(Fe or Co)15 alloys by V, Cr, Mn or Ru gives a mixed structure consisting of decagonal, icosah…
Sedimentation and ultrafiltration are important processes for removing solids from suspensions. The Kynch theory describes the transient settling of noncolloidal particles forming an incompressible sediment by providing a solution to the convective conservation equation. This solution predicts the existence of several…
The structure and growth morphology of Al65Cu15Fe20−xCox and Al65Cu20Fe15−xCox alloys have been examined in rapidly solidified, conventionally solidified and fully annealed states. A conventionally solidified Al65Cu15Co20 alloy, which was prepared by the whole substitution of Fe by Co for a stable icosahedral Al65Cu20…
Optical pumping has been used to select Ar atoms in the metastable 3P2 or 3P0 state in a flowing afterglow reactor. The relative concentrations of the two metastable states were assigned from observation of the N2(C,v′) emission spectra. The isolated reactions of the Ar(3P2) and Ar(3P0) atoms with F2, NF3, Cl2, CCl4,…
The first example of transition metal co-ordination to ethereal like oxygens of a 9-metallocrown-3 ether is seen in FeIII[FeIII(salicylhydroximato)(MeOH)(acetate)]3 and leads to an unusual tetranuclear cluster which exhibits both inter- and intra-cluster antiferromagnetic interactions and an S= 5 ground state.
New experiments conducted in a turbulent flow reactor show kinetic characteristics of methanol oxidation that have not been observed previously. Data are presented for methanol oxidation at equivalence ratios in the range of 0.6−1.6 and initial temperatures or 1025-1090 K at atmospheric pressure. At intermediate exten…