Materials Literature
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Pulse surface breakdown (flashover) and conditioning characteristics of polycrystalline alumina and single crystal quartz in vacuum were investigated. An electrode system which greatly facilitates time-coordinated electrical and optical measurements of surface discharges along insulators was designed and validated. Th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of transannular- and spiro-substituted cyclotriphosphazenes: x-ray crystal structures of 1,1-[N3P3(OCH2CF3)4{O2C12H8}], 1,3-[N3P3(OCH2CF3)4{O2C12H8}], 1,1-[N3P3(OCH2CF3)4{O2C10H6}], and 1,3-[N3P3(OCH2CF3)4}O2C10H6}]Harry R. Allcock, Michael L. Turner, and Karyn B.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReactions of 2-furyl, 2-thienyl, and N-methyl-2-pyrrolyl mercurials with [Et3NH][(.mu.-CO)(.mu.-RS)Fe2(CO)6] complexes. Synthesis of Fe2(CO)6 complexes with bridging .eta.1:.eta.2-furyl and thienyl ligandsDietmar Seyferth, Lea L. Anderson, Fernando Villafane, Martin Cowie, a…
This paper describes the results of numerical simulations for polydisperse sedimentation of equal-sized spheres, e.g. particles of different density. Using the Stokesian dynamics algorithm, mobility matrices are computed for random particle configurations and ensemble averages taken to calculate the mean mobility matr…
High-resolution Brillouin spectroscopy was used to study the elastic properties of ferroelastic ${\mathrm{K}}_{3}$Na(${\mathrm{SeO}}_{4}$${)}_{2}$. The temperature dependence of nine Brillouin modes of the acoustic phonons propagating in the [100], [010], [001], and [011] directions were measured in the temperature ra…
We have shown that clean γ- and α-Al2O3 films, prepared under relatively high pressure oxidation conditions, display methanol chemisorption properties and reactivity that are typical of powder alumina catalysts. Detailed vibrational and electronic information can be obtained for adsorbates on these thin-film oxides an…
We present a theory for calculation of the long-time self-diffusion coefficient of suspensions of interacting colloidal particles without hydrodynamic interactions. The theory follows the idea put forward in the preceding paper [Jan A. Leegwater and Grzegorz Szamel, Phys. Rev. A 46, 4999 (1992)]: The self-friction coe…
The time-differential perturbed-angular-correlation (PAC) method with ion-implanted $^{111}\mathrm{In}$ tracers was employed to study the hyperfine interactions of $^{111}\mathrm{Cd}$ nuclei in the rare-earth sesquioxides ${\mathrm{Sm}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{Gd}}_{2}$${\mathrm{O}}_{3}$, and ${\mathrm{Ho}}_…
The transformation of the decagonal quasicrystalline phase in Al62Cu20Co15Si3 and Al65Cu15Co20 to a normal crystalline phase was studied by electron diffraction and high-resolution electron microscopy. The transformation was induced by electron irradiation at room temperature. In the first stage the decagonal phase tr…
The proposed roles of Cys148 and Asp179 in deoxycytidylate (dCMP) hydroxymethylase (CH) have been tested using site-directed mutagenesis. CH catalyzes the formation of 5-(hydroxymethyl)-dCMP, essential for DNA synthesis in phage T4, from dCMP and methylenetetrahydrofolate. CH resembles thymidylate synthase (TS), an en…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and spectroscopic properties of the encapsulated cobalt(III) complexes derived from the unsymmetrically substituted ligand 5-methyl-5-(4-amino-2-azabutyl)-3,7-dithianonane-1,9-diamine (N4S2)Therese M. Donlevy, Lawrence R. Gahan, Trevor W. Hambley, and Robert Strang…
Abstract Sulphation of cellulose was performed in an homogeneous aprotic system with SO 3 or CISO 3 H, resp., via O‐trimethylsilyl celluloses as reactive intermediates. Na‐cellulose sulphates completely soluble in water and showing small chain degradation could be obtained at DS s ≥ 0.25. The DS s in the range between…
Ceria‐stabilized tetragonal zirconia polycrystals were obtained by thermal treatment of amorphous powder prepared by the sol–gel method. Detailed XRD profile analysis was employed to study microstructural disorder and crystallite size and shape; in particular, no fluctuation of stoichiometry was found, the main cause…
Etude par diffraction RX de la photoisomerisation de [Co(NH 3 ) 5 NO 2 ]Cl 2 . Cristallisation dans C2/c avec Z=4, T=116K. Avant illumination avec une lampe Xe, a=10.176, b=8.692, c=10.746A, β=95.45°, affinement jusqu'a R=0.028. Apres illumination pendant 40min, R=0.042 et pendant 150min, R=0.062. Variations des param…
Very strong sharp lines in luminescence of Tm 3+ have been observed in Li-codoped ZnS:Tm phosphor. In particular, blue emission intensity was stronger as compared with that of infrared emission when the codoped Li concentration in ZnS:Tm was 0.1 at.%. As ZnS:Tm emits a broad band and very weak Tm 3+ lines, the role of…
Unit-cell dimensionsfor synthetic alunite and natroalunite formed at 450°C are a=6.981, c=17.331A and a=6.9786, c=16.696A, respectively. Synthetic alunite-natroalunite solid solutions show a linear variation in c with mole fraction Na, but this trend is obscured in natural samples by heterogeneities in Na content. The…
Experimental studies on the dielectric constants of KH2PO4 type ferroelectrics below the Curie temperature Tc are reviewed with special emphasis to the anomalously large dielectric constant and its abrupt decrease in the low temperature region called domain freezing. The origin of the large dielectric constant below T…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransient effects in the interaction between polypyrrole and methanol vaporPatrice Topart and Mira JosowiczCite this: J. Phys. Chem. 1992, 96, 21, 8662–8666Publication Date (Print):October 1, 1992Publication History Published online1 May 2002Published inissue 1 October 1992h…
Determination de seize structures cristallines des trichloroacetates de cuivre II dimeriques. Dans les cristaux dans lesquels la valeur de -2J est petite (inferieure a 200cm -1 ), la geometrie de coordination autour de l'atome Cu est deformee d'une pyramide carree (SP) vers une bipyramide rhomboedrique (TBP) et la dis…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNitranions and their precursors: charge density rearrangements and nitrogen-15 NMR chemical shift changesCarlo Gatti, Alessandro Ponti, Aldo Gamba, and Giorgio PaganiCite this: J. Am. Chem. Soc. 1992, 114, 22, 8634–8644Publication Date (Print):October 1, 1992Publication Hist…