Materials Literature
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PURPOSE: To assess the degree and regional pattern of first-pass brain enhancement using dynamic MR imaging. MATERIALS AND METHODS: Ultrafast MR imaging (1.06-second acquisition time per image) was performed in 19 healthy subjects following a bolus IV injection of a gadolinium contrast agent; 36 patients with suspecte…
Corrosion layers grown on stainless steels (AISI 302, 316), polarized at the pitting potential in alkaline solutions containing chloride, were identified by Raman spectroscopy. Several binary alloys such as Fe-10Ni, Fe-6Mo, and Fe-18Cr, were studied to separate the influence of the different alloy elements. A comparis…
The second and third virial coefficients are estimated for a semidilute suspension of macromolecular rods interacting by van der Waals forces. Whenever the attractive interaction becomes strong enough to be noticeable, it is no longer quantitatively correct to adopt a second virial approximation. Nevertheless, the sta…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTime-resolved observation of photochemical phase transition in polymer liquid crystalsTakeo Sasaki, Tomiki Ikeda, and Kunihiro IchimuraCite this: Macromolecules 1992, 25, 14, 3807–3811Publication Date (Print):July 1, 1992Publication History Published online1 May 2002Publishe…
The electronic and geometric structures of paramagnetic iron dinitrosyl complexes have been investigated using electron spin resonance, infrared spectroscopy, and X-ray crystallography. It is concluded that these compounds are best described as 17 electron complexes with a d 9 configuration rather than the d 7 configu…
Abstract Passive films formed in 1N HCI at different potentials on mechanically polished samples of the alloy Fe 70 Cr 10 P 13 C 7 were studied by XPS surface analysis. The thickness of the films increases with the applied potential; at 0.4 V/SCE (saturated calomel electrode) a discontinuity is observed. The passive f…
We present inverse photoemission spectroscopy (IPE) data from the nearly perfect and defective TiO2(110) surfaces. In the spectra from the nearly perfect surface, features appearing ∼1 and ∼4 eV above the Fermi level are identified as the primarily Ti-derived 2t2g levels and 3eg levels. This result is consistent with…
The eutectic composition between Y 4 Al 2 O 9 and Y 2 O 3 was determined using electron probe microanalysis (EPMA) on directionally solidified specimens with hypo‐ and hypereutectic compositions. The microstructures of the specimens as a function of composition differ considerably with small deviation from the eutecti…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and structure of a new microporous anionic derivative of germanium dioxide: [Ge18O38(OH)4]8-[(C2N2H10)2+]4.cntdot.2H2ORichard H. Jones, Jiesheng Chen, John Meurig Thomas, Ashley George, Michael B. Hursthouse, Ruren Xu, Shougui Li, Yuqin Lu, and Guangdi YangCite thi…
A graded refractive index silicon oxynitride (SiOxNy) thin film was prepared on a silicon substrate by ion assisted deposition. Spectroscopic ellipsometry (SE) was used to optically analyze the film. The measured SE spectra (2500–8200 Å) were analyzed with several fitting models, whose construction was based on an Aug…
Abstract The reactions occurring during melt‐mixing of poly(ethylene terephthalate) and bisphenol‐A polycarbonate have been reconsidered. Certain evidence leads us to conclude that two reactions, usually disregarded in the literature, occur, which have to be considered in the general scheme along with the already desc…
Diffusion experiments using polystyrene (PS) molecules of three different topologies, linear, ring, and microgel, were performed. Tracer diffusion of linear PS in ring matrices was found to be nearly identical to that in linear matrices, a surprising result in view of current theories for matrix-dependent tracer diffu…
Adsorption and electron stimulated processes of NH3 on rutile TiO2(110) have been studied by means of x-ray photoemission spectroscopy (XPS) and low-energy ion scattering (LEIS). Defects, mostly surface oxygen vacancies, can be produced easily on TiO2 surfaces by thermal treatment or by rare gas ion sputtering. We hav…
Tyrosine phosphorylation of 42-kDa mitogen-activated protein kinase (p42mapk) occurs during expression of the recombinant protein in Escherichia coli, as well as during in vitro phosphorylation of the protein purified from this source. Structural analyses were performed to identify the site(s) of tyrosine phosphorylat…
Four methods for partial discharge (PD) detection in gas-insulated substations were considered. Laboratory tests were carried out to determine the efficiency of these methods to detect defects and to discriminate among different defect types. The sensitivity of the methods is compared and the applicability of the meth…
We report on experiments to determine the feasibility of using refractory transition metal carbides as stable field emission cathodes. Applications of such cathodes could include radiation immune microcircuitry, radio frequency (rf) vacuum microelectronic amplifiers, flat panel displays, e-beam lithography, and other…
It has been argued that, in systems that have disorder too large to be described by a Gaussian, x-ray-absorption fine-structure (XAFS) spectroscopy alone cannot define the radial distribution function (RDF) because of the lack of low-k data. We show that the low-k data can, under certain conditions, be reconstructed u…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTZero field splitting and exchange interactions in bis(cyclopentadienyl)titanium(III) dinuclear compounds with short metal-metal distances: synthesis, x-ray structure, and EPR spectroscopy of methoxo- and ethoxo-bridged dimersEdmond Samuel, John Frank Harrod, Didier Gourier,…
The biocompatibility of radiofrequency plasma polymerized films (less than 100 nm thick) deposited on biomedical polymer supports has been characterized by in vitro and in vivo methods. The polymer interface materials covered a wide range of elemental composition and surface properties, and were prepared from N-vinyl-…
ABSTRACT The average size and shape of a polymer coil confined in a slit between two parallel plates depends on the distance L between the plates. On the basis of numerical results, four different regimes can be distingubhed. For large values of L the coil is essentially unconfined. For intermediate values the coil or…