Materials Literature
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Fundamental notions concerning absolute structure and absolute configuration, and their determination from single-crystal diffraction measurements, are presented and reviewed. A glossary of terms with definitions useful in this field is provided. For absolute structure and its determination, the separate but interacti…
The structural, dielectric and piezoelectric properties of [Bi 0.5 (Na 1- X K X ) 0.5 ]TiO 3 ceramics were studied for the compositional range, X =0–1.0. The samples were prepared by a conventional sintering technique. From X-ray diffraction results, it was found that the morphotropic phase boundary (MPB) between (Bi…
We have studied the work function and density of states (DOS) of multiwall carbon nanotubes (MWNTs) using ultraviolet photoelectron spectroscopy (UPS). Raw MWNTs were purified by successive sonication, centrifugation, sedimentation, and filtration processes with the aid of a nonionic surfactant. The purified MWNTs sho…
The high strength to weight ratio of magnesium alloys makes them extremely attractive for applications in transport or aerospace technology. However, their corrosion behavior is a major issue and one reason why they are still not as popular as aluminum alloys. This papers reviews the corrosion mechanisms of magnesium…
Measurements were made of the Kerr constants of several mineral and silicone oils. The results indicate that these oils can be used to improve the sensitivity of measurements of the quadratic electro-optical effect in crystals. The possibility of using the electro-optical Kerr response of oils to determine experimenta…
Aqueous D 2 O solutions of lithium (0.5, 1, and 3 M) and sodium (1 and 3 M) perchlorate have been studied by FT-IR spectroscopy in their glassy states at 80 K, and their IR spectra compared with those of 1.0 M D 2 O solutions recorded from 300 to 235 K. Evidence for strongly increasing contact-ion pairing in going fro…
The three-dimensional silver-selenoarsenate RbAg2As3Se6 is a kinetic product in the methanolothermal reaction between RbCl, AgBF4 and Li3AsSe3. It contains [As3Se6]3- rings, connected by formal “Ag22+“ dumb-bell units to form a three-dimensional framework structure [Ag2As3Se6]-. The ability of the Ag22+ units to adapt…
The published data are surveyed and a comparative crystal-chemical analysis is presented for the structures of compounds containing mercury in low oxidation states as cluster Hgn groups with covalent Hg–Hg bonds. The geometry of compounds with Hg–Hg and Hg–X bonds (X = O, S, Se, N or Hal) is analysed and the types of…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTFormation and Interconversion of Ruthenium−Silene and 16-Electron Ruthenium Silyl ComplexesVladimir K. Dioumaev, Karl Plössl, Patrick J. Carroll, and Donald H. BerryView Author Information Department of Chemistry and Laboratory for Research on the Structure of Matter,…
A method has been developed for the condensation of droplets onto individual textile fibers in the environmental scanning electron microscope. It can be seen how the drops formed surround the fibers as long as the fiber surface is smooth. In this case they adopt an unduloid shape. The images produced of the droplets a…
Lysozyme folds through two competing pathways. A fast pathway leads directly from a collapsed state to the native protein, whereas folding on a slow pathway proceeds through a partially folded intermediate (I(1)). At NaCl concentrations above 100 mM, a second transient intermediate (I(2)) is induced as judged by the a…
The stability of europium(III) complexes with benzocrown ether derivatives 2 − 4 containing carboxylic functions with methylene spacers of different length was found to vary surprisingly little. In sharp contrast, the hydrolytic activity of these catalysts against bis( p -nitrophenyl)phosphate (BNPP) varied by a facto…
The five reduced polyoxomolybdate anions [HSiMo 12 O 40 ] 4 - (HI β ), [H 2 SiMo 12 O 40 ] 4 - (H 2 II β ), [H 5 SiMo 12 O 40 ] 3 - (H 5 IV β ), [SiMo 14 O 44 ] 4 - (SiMo 14 ), and [Si 2 Mo 28 O 84 (H 2 O) 2 ] 6 - (Si 2 Mo 28 ) have been synthesized as tetramethylammonium salts, by hydrothermal reactions, and characte…
A series of 11 chiral dopants with an atropisomeric core derived from 4,4‘-dihydroxy-2,2‘,6,6‘-tetramethyl-3,3‘-dinitrobiphenyl were synthesized in optically pure form. These compounds were doped into five different smectic C (S C ) liquid crystal hosts to induce a ferroelectric S C * liquid crystal phase, and the red…
High-level ab initio calculations with a variety of G2-based methods have been used to determine the structures and heats of formation of the alkali and alkaline earth oxides and hydroxides (M 2 O, MOH with M = Li, Na, and K; M‘O, M‘(OH) 2 with M‘ = Be, Mg, and Ca). Standard G2 theory, which is normally very reliable…
A new series of side-group liquid-crystal polymers, the poly[ω-(4-methoxybiphenyl-4‘-yloxy)alkyl acrylate]s, has been synthesized in which the spacer length is varied from 3 to 12 methylene units. The thermal behavior of the polymers has been characterized using differential scanning calorimetry and polarized light mi…
A series of merocyanine dye dimers tethered at different sites with spacers ranging from 0 to 5 methylene groups and the corresponding monomer have been synthesized. The formation, structure, and excited-state properties of the consequent merocyanine dye “aggregates” in solutions and in rigid glass have been studied b…
Metallophthalocyanines have been prepared with 18-crown-6 residues at the four peripheral benzo sites (McrPc). Metal centers employed have been H 2 (free base), Zn(II), and Cu(II). In ethanol solution containing potassium acetate, such species incorporate K + cations into the crowns, one K + per crown, and are monomer…
MCM-48 and SBA-1 samples were characterized using powder X-ray diffraction and nitrogen adsorption in a wide range of relative pressures. X-ray diffraction provided direct evidence for the high degree of pore structure ordering for the materials under study. Nitrogen adsorption showed that highly ordered MCM-48 materi…
Self-assembled natural and synthetic clay−polymer films have been prepared by sequential adsorption of poly(diallyldimethylammonium chloride) (PDDA) and clay particles onto mica. The influence of pH, polymer concentration, and clay particle size on the building and roughness of mono- and multicycle depositions was inv…