Materials Literature
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The reaction of Pt2(dba)3 with CO leads rapidly to the formation of platinum nanoparticles. Stabilization of the particles was achieved by octanethiol or various polymers. Spectroscopic studies demonstrate the coordination of thiol at the surface of the particles. The size distribution is quasi monodisperse and center…
We present a theory of resonant quantum tunneling of large spins through thermally activated states. It gives numerical results that are in good agreement with data from recent magnetic quantum tunneling experiments in Mn acetate. We show that neither dipolar fields nor crystal-field perturbations, acting separately,…
The objective of this investigation was to clarify the influence of water-soluble polymers on the dissolution behavior of nifedipine from solid dispersions with combined carriers. All the solid dispersions of nifedipine were prepared by the fusion method using nicotinamide and 4 different water-soluble polymers, hydro…
SIMS and XPS were used to characterise the chemistry of thin plasma polymerised acrylic acid films (ppAAc), and to determine how this was influenced by plasma power. Quartz microbalance weight measurements were used to monitor the effect of power on the deposition rate and identify the uptake of water vapour by the fi…
The dimerization and tendency to form higher aggregates of two isomeric metal-free phthalocyanine compounds with tetracumylphenoxy peripheral substitution at the alpha (1 or 4, 5 or 8, 9 or 12, 13 or 16) and beta (2 or 3, 6 or 7, 10 or 11, 14 or 15) positions has been analysed by spectroscopic measurements. The dimeri…
With the help of bibliometric mapping techniques, we have developed a methodology of “self-organized” structuring of scientific fields. This methodology is applied to the field of neural network research. We propose a field-definition based on the present situation. This is done by letting the data themselves generate…
A series of conjugated porphyrin oligomers have been prepared and the evolution in their electronic properties is discussed; the crystal structure of the dimer is presented, as well as the MALDI TOF mass spectrum of the hexamer.
Kinetics of NO decomposition have been investigated over La0.8Sr0.2CoO3 and La0.4Sr0.6Mn0.8Ni0.2O3 perovskite-type oxides. The NO decomposition reaction was practically first-order for NO in the range 0.1–0.5 vol.% NO. The activity was decreased by the presence of gaseous oxygen up to 9 vol.% with the reaction order b…
In contrast to large-diameter vascular grafts (i.e. larger than 5 mm) which remain excellent for more than 10 years after implantation, small-diameter vascular grafts of both Dacron and Teflon occlude rapidly upon implantation. In this overview article, the strategies used to improve the patency of these small-diamete…
We have performed time resolved diffraction experiments in order to obtain a better insight upon the metastable phases surrounding some thermotropic mesophases of cubic Ia 3 d and Im 3 m symmetries. These metastable phases are columnar hexagonal, smectic or tetragonal, depending on the nature of the mesogenic molecule…
The ternary carbide Ti3SiC2 possesses a unique set of properties that could render it a material of considerable technological impact. The motivation for this work was to enhance the hardness and oxidation resistance of Ti3SiC2 by altering its surface chemistry. Reaction of Ti3SiC2 with single crystal Si wafers in the…
It is shown that the effects of large dc bias and ac driving fields on the dielectric permittivity of single crystals of ${\mathrm{PbMg}}_{1/3}{\mathrm{Nb}}_{2/3}{\mathrm{O}}_{3}$ (PMN) relaxor ferroelectric exhibit very different behavior, including anisotropy and sign of the effect, which is traced up to the high-te…
Calcium chromates with the empirical formulas Ca 10 Cr 6 −O 25 , Ca 3 Cr 2 O 8 , and Ca 5 Cr 3 O 12 , which form at temperatures >900°C at CaO:Cr 2 O 3 molar ratios of 3 in an oxidation atmosphere have been synthesized in the pure state. X‐ray absorption near‐edge structure (XANES) spectroscopy has been used to det…
V-loaded β zeolites can be prepared by a two-step post-synthesis method which consists of first creating vacant T-sites by dealumination of the β zeolite with nitric acid, then contacting them with an ammonium metavanadate solution; the SiOH consumption and the nature of the incorporated V species are characterized by…
This investigation describes the comparative structural characterization of naturally- and synthetically-spun fibers of Bombyx mori fibroin. Wet spinning from 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) solutions was used to spin fibroin fibers with varying degrees of postspinning draw. Quantitative Raman spectroscopy sh…
The thermodynamic principles of the formation of a new class of materials, polydomain heterostructures, are formulated. The polydomain heterostructures can be formed as a result of phase transformations in constrained layers, composed of epitaxial couples or multilayers. Due to the elastic interaction between the laye…
Neutron-powder-diffraction experiments on ${}^{154}{\mathrm{SmNiO}}_{3}$ and ${}^{153}{\mathrm{EuNiO}}_{3}$ at different temperatures have been performed. At variance with the case of Pr and Nd nickelates, the metal-insulator transition temperature in these compounds are different from the N\'eel temperature (${T}_{M\…
In X-ray crystallography, a least-squares structure refinement is used to two purposes: to prove the correctness of the proposed model and to improve it. In electron crystallography, the same tool would be desirable. However, the standard programs for least-squares structure refinement used in X-ray diffraction may gi…
Reduction potential and lipophilicity of the copper(II) bis(thiosemicarbazone) complexes can be independently controlled by alkylation in the diketone backbone and the N-termini of the ligand, allowing optimisation of radiopharmaceuticals strongly selective for hypoxic tissues.
High valent metal–oxo species have been evoked as active intermediates in many different oxidation reactions using manganese or iron porphyrin complexes as catalysts and oxygen atom donors (H2O2, PhIO, NaOCl, KHSO5, ... etc.) or dioxygen associated to a reductant as oxygen atom source. When these metalloporphyrin-cata…