Materials Literature
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The origin of the difference in the switching properties of ferroelectric thin films and bulk ferroelectrics is discussed. The ideas of the size effects which may account for this difference are critically reviewed. It is shown that the two often used models (the Janovec-Kay-Dunn surface nucleation size effect and the…
Three genes encoding enzymes involved in the biosynthesis of pyrimidines have been found to constitute an operon in Lactococcus lactis. Two of the genes are the well-known pyr genes pyrDb and pyrF, encoding dihydroorotate dehydrogenase and orotidine monophosphate decarboxylase, respectively. The third gene encodes a p…
Two crystalline compounds based on the Zn-tetra (4-carboxyphenyl)porphyrin building block have been prepared and structurally analysed by x-ray diffraction in order to ellucidate the characteristic supramolecular aggregation modes of this functionalized metalloporphyrin moiety. Crystals of the 1:1 complex with sec-phe…
Other| August 01, 1996 Crystal chemistry and IR spectroscopy of Cl- and SO 4 -bearing cancrinite-like minerals P. Ballirano; P. Ballirano Universita di Roma "La Sapienza", Dipartimento di Scienze della Terra, Rome, Italy Search for other works by this author on: GSW Google Scholar A. Maras; A. Maras Search for other w…
Coverage-dependent adsorption studies of benzoic acid on a Cu(110) single crystal surface resulted in a sequence of novel, large periodicity structures containing differently oriented benzoate species, as shown by LEED, STM and FTIR. At low coverage, only flat-lying benzoate species are present and faceting of step ed…
Many of the physical pictures used to rationalize the phenomenology of glassy dynamics rest upon a consideration of spatial fluctuations in the relaxation kinetics of the glass-forming liquid. We examine the wide ranging consequences which flow from assuming the existence of transient kinetic inhomogeneities. These co…
We have fabricated perovskite superlattices consisting of two ferromagnetic metallic oxides: ${\mathrm{La}}_{0.67}$${\mathrm{Ca}}_{0.33}$Mn${\mathrm{O}}_{3}$ (LCMO) and SrRu${\mathrm{O}}_{3}$ (SRO). We have investigated the magnetotransport and magnetic properties of a series of samples, in which the layer thickness o…
Macromolecular X-ray crystallography underpins the vigorous field of structural molecular biology having yielded many protein, nucleic acid and virus structures in fine detail. The understanding of the recognition by these macromolecules, as receptors, of their cognate ligands involves the detailed study of the struct…
Liquid- and solid-like particles in a glass are defined via the Lindemann criterion of melting. Due to structure inhomogeneity the amplitude of the mean-square thermal atomic displacements ⟨ r 2 ⟩ varies spatially. This situation defines a percolation problem for liquid- and solid-like clusters. There are two percolat…
A linear arrangement of guest molecules in perhydrotriphenylene inclusion compounds can lead to supramolecular materials with optimized physical properties. Through cocrystallization, different guests displaying pronounced nonlinear optical properties were incorporated within the channels of the host species (shown on…
Conventionally solidified samples of decagonal Al70Co11Ni19 annealed at 1050degreesC for 12h, studied by electron diffraction and high-resolution transmission electron microscopy (HRTEM), display sharp spots in their diffraction patterns and almost no diffuse background scattering. Detailed geometric analysis of tilin…
We report on both polar and nonpolar light-induced orientation of a polyimide of high glass transition temperature (Tg ≈ 210 °C) with nonlinear optical azo dye molecules in the side chain. This photoinduced orientation is shown to occur at room temperature, i.e., at least 190 °C below the Tg value of the polymer, whic…
We justify the application of the theory of the kink-type motion for interphase boundaries for perovskites at first-order phase transitions and obtain a criterion for separating two mechanisms for the front motion---the latent heat transfer and the relaxation of the order parameter. Calculations of the velocity of the…
Outlines an approach to the problem of simulating the drape of fabrics. The approach is based on representing fabrics as two‐dimensional continua and using the differential geometry of surfaces to describe the shape of the draped fabric and to deduce deformation measures. The approach follows the philosophical approac…
Transparent polymeric materials with high heat resistance and low water absorption were designed based on the alternating copolymers of N-substituted maleimide (RMI) with isobutene (IB). The N-substituent of the maleimide significantly affected the glass transition temperature (Tg) and water absorption of the copolyme…
The preparation of filled two-component semi-interpenetrating polymer networks (semi-IPNs) is described and the results of an investigation of their morphology by means of dynamic mechanical spectroscopy are considered. The influence of an active dispersed filler (γ-Fe2O3) on the semi-IPNs phase structure is studied.…
Abstract Low‐molecular‐weight polystyrene was nitrated to different levels. The nitrated polystyrene was blended with different molecular weights of poly(acrylic acid), PAA. The glass transition temperatures ( T g ) for the mixtures were investigated by differential scanning calorimetry. A single T g was observed for…
Abstract The crystal structure of christelite Zn 3 Cu 2 · (SO 4 ) 2 (OH) 6 · 4 H 2 O (space group P [unk]; lattice parameters a = 5.4143(8) Å, b = 6.336(1) Å, c = 10.470(3) Å, α = 94.32(3)°, β = 90.06(2)°, γ = 90.27(2)°) was solved using direct methods and difference Fourier-syntheses. The structure was refined to a f…
Other| August 01, 1996 Lattice-dynamical evaluation of atomic displacement parameters of minerals and its implications; the example of diopside Tullio Pilati; Tullio Pilati CNR, Centro per lo Studio delle Relazioni tra Struttura e Reattivita Chimica, Milan, Italy Search for other works by this author on: GSW Google Sc…
A percolation model for conducting polymers is proposed in terms of a random resistor network. The macroscopic conductivity at the critical polymer density is studied. Substantial deviations have been detected from the standard conducting behavior in percolating structures generated with a large difference between int…