Materials Literature
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Due to the discrete directional nature of processes such as crystallographic slip, the orientation of slip planes relative to a fixed set of loading axes has a direct effect on the magnitude of the external load necessary to induce dislocation motion (yielding). The effect such geometric or textural hardening has on t…
We have found, at high EM magnification, on ultrathin sections of shock-frozen, freeze-dried, embedded pieces of the developing hard tissues, that the primary crystallites consist of strands composed of nanometer-sized apatitic islands, which rapidly coalesce to needles and afterward to platelets. By small-area electr…
In this paper are presented data on the preparation and characterization of different oxide electrodes. RuO 2 –TiO 2 , IrO 2 –TiO 2 , and SnO 2 –Sb 2 O 5 mixed-oxide films have been taken as model systems. For the first, the traditional preparation method based on the pyrolysis of precursor salt deposits was adopted.…
New cyclolinear polymers from bifunctional organic molecules and cyclotriphosphazenes containing two reactive groups have been synthesized. The reaction between 2,2-bis(4-hydroxyphenoxy)-bis[spiro(2′,2“- dioxy-1′,1”-biphenylyl)]cyclotriphosphazene 3, obtained by the reaction of 2,2-bis(4-methoxyphenoxy)- bis[spiro(2′,…
Recent results from low-frequency Raman scattering experiments on different types of glass formers are discussed. In particular, fast relaxations above T g in the frequency range 1010Hz < v < 1013Hz are described. Both fragile and non-fragile glass formers exhibit similar dynamics which qualitatively can be reproduced…
The electrochemical polarization behavior of the copper‐containing Al 2024‐T3 alloy in deaerated 0.01 M NaCl saturated with a number of solid inhibitors demonstrates that one of the compounds examined, barium metaborate, exhibits an inhibiting power in excess of that of zinc chromate. Electrochemical polarization of a…
We present spectra of three M subdwarfs which are common proper motion companions to F or G subdwarfs of known metallicity. The assumption that the companions have the same composition allows us to test the Gizis (1997, AJ, 113, 806) M subdwarf classification system and its correspondence to metallicity. The results a…
Equilibria constants for the simultaneous liquid-phase syntheses of methyl tert- butyl ether (MTBE) and ethyl tert- butyl ether (ETBE) were determined experimentally in the temperature range 313−353 K at 1.6 MPa. To achieve etherification equilibria, the macroporous sulfonic acid resin Bayer K-2631 was used as the cat…
To derive the absorbed dose to water from a standard of absorbed dose to graphite, the metrology laboratories which apply such a method usually make use of cavity ionization chambers as transfer instruments. In addition, the BNM-LPRI has tested, as such instruments, two types of Fricke dosimeter in its cobalt-60 beam.…
Abstract We report on the atmospheric corrosion of different cast statue bronzes in humid air containing ppb levels of SO 2 and SO 2 +NO 2 . In addition, copper, tin, zinc, and lead samples were studied in these environments. The samples were exposed to synthetic atmospheres with careful control of pollutant concentra…
Interconnected, microporous thin films have been prepared by formation of organic−inorganic hybrid materials via a sol−gel process. The spin-coating solution was obtained by hydrolyzing tetramethoxysilane (TMOS) with different portions of methyltrimethoxysilane (MTMS) under acidic catalyst. The organo−silicon groups i…
Abstract In contrast to extended solids, nanometer size crystals convert from one structure to another by single nucleation events, and the transformation obey simple kinetics. Barrier heights are observed to increase in nanocrystals of larger size, but also depend on the nature of the nanocrystal surface. These resul…
The magnetic properties of four diphenylverdazyls ( 2 − 5 ) with electron acceptor groups in the 3-position were studied by measuring the magnetic susceptibility and heat capacity. The crystal structures of 3 and 4 were determined, and for 2 the crystal structure analysis led to an improved refinement. Verdazyl 2 was…
We present results on the product distribution obtained from the polymerization of the dicyanate monomer of bisphenol A carried out under different reaction conditions. Small quantities of side-products were observed using both size exclusion chromatography and high-pressure liquid chromatography for samples polymeriz…
Extensive analyses of the electronic absorption, magnetic circular dichroism (MCD), and fluorescence emission and excitation spectra of peripherally-substituted tetrabenzotriazaporphyrin (TBTrAP) and tetranaphthotriazaporphyrin (TNTrAP) complexes are reported. ZINDO calculations of the UV−visible absorption spectra of…
The influence of precracking techniques in the crack growth behavior of yttria‐stabilized tetragonal zirconia polycrystals (Y‐TZP) is investigated. Load‐bridge and cyclic‐compression precracking enhance subsequent tensile crack growth rates, in comparison to results that are found with precracks that are extended unde…
Abstract Nanocrystalline ZrO 2 ‐ and Y 2 O 3 ‐powders with grain sizes from 5‐20 nm were prepared by the Inert Gas Condensation method. The powders were mixed in different fractions, pressed into green bodies and sintered to ceramic samples with 35‐49 nm average grain size. The phase, grain size and specific surface a…
The cryptand L can accommodate a Co(II) ion inside the cavity at the tren end, forming a CoN4 complex. The Co(II) ion further accepts a SCN- anion, forming a distorted trigonal bipyramidal complex. The Co(II) cryptate can act as an efficient catalyst for oxygenation of organic substrates using molecular oxygen and 2-m…
A detailed study of the electrical and magnetic properties of polycrystalline ${\mathrm{La}}_{0.52}{\mathrm{Gd}}_{0.15}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_{3}$ has been carried out. This perovskite-type compound should be a canted ferromagnetic metal at low temperatures. The magnetization and conductivity show consider…
Attachment of four oligomeric (MW 550) ethylene glycol chains to tetraphenylporphyrin results in a highly viscous, room temperature melt a hybrid redox polyether that is highly concentrated in porphyrin sites (∼0.4 M) and will dissolve LiClO 4 electrolyte. Microelectrode voltammetry in undiluted, free base and Co and…