Materials Literature
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Abstract H 2 and CO 2 transport properties were investigated on semicrystalline poly(ethylene‐2,6‐dicarboxylate naphtalene) (PEN) films and biaxially stretched films and analyzed in terms of solubility and diffusion. The decrease of the permeability observed on the thermally crystallized samples has been described by…
We present a stochastic model of dynamically interacting grains in one dimension, in the presence of a low vibrational intensity, to investigate the effect of shape on the statics and dynamics of the compaction process. Regularity and irregularity in grain shapes are shown to be centrally important in determining the…
Abstract Clays of a soil sequence with five profiles in the Val Genova (northern Italy) along an elevation gradient with climate ranging from moderate to Alpine were investigated with XRD using several diagnostic treatments. Smectites developed in the surface horizons of podzolic soils either from chlorite through the…
In situ methods are ideally suited for the study of the development of property-critical structural features during materials processing. As an example of their potential in the area of complex oxide electroceramics, here, we apply in situ synchrotron powder diffraction to investigate the ordering processes responsibl…
In this paper we compare the results of three ferroelectric materials that exhibit unusual smectic-A (SmA) phases. These phases have been assigned to chiral analogs of the de Vries SmA phase. Several experimental techniques have been employed for this investigation. The possible molecular structures of de Vries SmA* p…
Interpolyelectrolyte complex (IPEC) formation between sodium poly( l -glutamate) and poly(amido amine) dendrimer in aqueous solution containing 0.25 M NaCl was studied as a function of pH by light scattering. The formation of soluble IPECs upon protonation of the dendrimer at 11 > pH > 9.1 was followed from the increa…
Ternary vapor−liquid equilibria (VLE) of selected aqueous azeotropic systems in the presence of differently branched hydroxyl functional components (additives) have been measured. Three azeotropic mixtures, ethanol + water, 2-propanol + water, and tetrahydrofuran + water, were chosen. The additives used were nonvolati…
Durch Ausfüllen der Poren in der Kristallisations-Vorstufe mit Kohlenstoff bleibt die zweidimensionale hexagonale Ordnung von gemischtem Niob-Tantal-Oxid erhalten. Beim Erhitzen unter Inertgas kristallisiert das Produkt, ohne dass die mesoporöse Struktur verlorengeht. Das Kohlenstoff-Templat kann durch Calcinierung an…
Abstract Well crystallized ZnO powders with various morphologies such as hour glass‐shaped, shortened prismatic, flake‐like and prismatic form have been synthesized by adopting the system of Zn(Ac) 2 ‐KOH‐H 2 O via a hydrothermal process at 200 °C for 2 h. It was found that the as‐synthesized hour glass‐shaped ZnO cry…
As a model catalyst, gold and iridium were co-deposited on a single crystal of rutile TiO2 using the deposition precipitation method in order to clarify the synergetic effect of the combination of Au with Ir on the catalytic performance of the oxidative decomposition of odour and dioxins. Analyses by means of high-res…
We report neutron scattering results on the spin dynamics in the paramagnetic (PM) and ferromagnetic (FM) states of the 50% hole-doped manganites ${\mathrm{Pr}}_{1/2}{\mathrm{Sr}}_{1/2}{\mathrm{MnO}}_{3}$ and ${\mathrm{Nd}}_{1/2}{\mathrm{Sr}}_{1/2}{\mathrm{MnO}}_{3}.$ In the PM phase, these systems exhibit two kinds o…
The bulk (Fe,Ti,O) phase diagram is strongly modified at the nanometer scale: instead of the mixture of the rhombohedral and pseudo-brookite phases normally present in the micrometer range, a single fcc phase is stabilized for grain size lower than 25 nm. The existence of a single phase permits the formation of small…
By means of a multistep synthetic procedure a dimanganese complex has been prepared, in which a N,N'-bridging pyrazolate ligand spans two CpMn(CO)(2) subunits in a highly preorganized chelate arrangement. The Xray crystallographic analyses of the Mn(I)Mn(I) complex K(+)1(-) and of its non-chelate precursor complex elu…
We study the action of a strong electric field on a nematic, topologically stabilized with director n perpendicular to E. Above a threshold field the nematic order on the cell midplane is "melted" and rapidly reconstructed with n axially E. In a Landau-de Gennes model, we show that the observed transient "melted" stat…
Abstract Soils developed on Pleistocene andesitic lava flows and fluvial detritus in the Atlantic coastal plain of Costa Rica display a clay mineral assemblage that includes 10 Å and 7 Å halloysite and lesser amounts of kaolinite and dioctahedral vermiculite. Other secondary minerals include gibbsite, goethite, hemati…
The effect of mixing surfactants (anionic, zwitterionic, and nonionic) and alcohols on the sonoluminescence (SL) generated by 3.5 ms pulses of 515 kHz ultrasound in air-saturated aqueous solutions has been examined. Each surfactant/alcohol system influenced the SL in significantly different ways. It was concluded that…
A molecular-dynamics study of the flow of thermal and mechanical energies and the Kapitza conductance across both ideal and imperfect interfaces formed by two dielectric thin films is presented. The numerical experiments were achieved on a three-dimensional lattice configuration consisting of two kinds of fcc lattice…
Polycondensation normally proceeds in a step-growth reaction manner to give polymers with a wide range of molecular weights. However, the polycondensation of potassium 5-cyano-4-fluoro-2-propylphenolate ( 1 ) proceeded at 150 °C in a chain polymerization manner from an initiator, 4-fluoro-4‘-trifluoromethylbenzophenon…
The carryover of surfactant ahead of contact lines on hydrophilic surfaces results in unusual wetting behavior of surfactant solutions, such as the autophobic effect. This carryover of surfactant ahead of the contact line is due to the strong interactions between the hydrophilic surface and the headgroup of ionic and…
We study a lattice model with two-body interactions that reproduces in three dimensions many features of structural glasses, such as cage effect and vanishing diffusivity. While having a crystalline state at low temperatures, it does not crystallize when quenched, even at the slowest cooling rate used, which makes it…