Materials Literature
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The dc conductivity of a sintered sample of Y 2 O 3 containing an excess of lower‐valent metal (Ml) impurities has been measured at 600° to 1100°C in air as a function of the water vapor pressure (0.4 to 3000 Pa). The logarithm of the p ‐type conductivity vs log P H2o has a slope of – 1/2 in certain regions of F H2o a…
When a nematic liquid-crystal cell is driven by a dc electric field, the capacitance of the cell increases in the first several tens of milliseconds, but after that the capacitance tends to decrease with a rather long relaxation time of the order of 1 s. This phenomenon can be explained by impurity ions which form the…
Densification of two‐dimensional arrays of nearly monosized copper spheres was examined by hot‐stage optical microscopy. The evolution of the particle arrangement was studied with computer methods, and statistical correlations were sought. Color graphics were found useful for displaying the spatial relationship of the…
Abstract Several classes of organosilicon polymers are effective precursors for silicon carbide ceramic compositions. These include polydimethylsilane (via a two‐step process), ‘polysilastyrene’, polycarbosilazanes or polysilazanes, and certain siloxanes, plus the branched polycarbosilanes, branched polysilahydrocarbo…
We report, for the first time to our knowledge, on high-resolution x-ray scattering measurements of the liquid crystal 4'-butoxyphenylester 4-decyloxybenzoic acid (4OP10OB) with emphasis on the smectic-C phase and the smectic-A to smectic-C phase transition. From angular scans in reciprocal space we found that the sme…
Abstract A novel addition polymerization of 1,4‐diethynylbenzene ( 1 ) with 1,4‐benzenedithiol ( 2 ) was studied under UV‐irradiation in toluene solution at −20°C. The addition polymerization was found to proceed rapidly and a pale‐yellowish polymer precipitated with the progress of the reaction ( M̄ n = 7500). A solu…
Abstract A greenhouse experiment was conducted with soil from the A horizon of an acid Mountview silt loam (Typic Paleudult) to measure the relative influence of soil P retention capacity on P availability from Bayovar (also known as Sechura) phosphate rock (Peru) with that from triple superphosphate (TSP). The P rete…
At room temperature, a kink in negative fields appears in the hysteresis loops of Nd-Fe-B permanent magnets. This phenomenon can be related to the fact that the grains at the surface of the magnet exhibit a strongly reduced coercivity compared to those of the bulk. Below 130 K a kink of another nature develops. It is…
Abstract The temperature dependence of electrical resistivity and thermoelectric power of the intercalation compounds of M x TiS 2 (M = Mn, Fe, Co, and Ni; 0 ≦ x ≦ 1/3) with layered structures are measured over the temperature range 1.5 to 300 K. These experimental results can be explained by a simple model, which tak…
A product consisting of two vinylogous amidinium ions is formed when the title compounds gives up two electrons to iodide. The resulting salt forms diamagnetic, blackish-violet crystals. The two mesomeric π-electron systems are almost planar; the sixmembered ring in 1 has a twist-conformation.
The properties of a soluble endoprotease from rat liver were studied. The enzyme was purified in a latent form. It sedimented as a single component with a sedimentation coefficient (S(0)20,w) of 19.8 S. Measurement by quasi-elastic light scattering gave a diffusion coefficient (D(0)20,w) of 2.5 X 10(-7) cm2 X s-1 and…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCopper(II) and nickel(II) trinuclear species with dithiooxamide derivative ligands: structural, magnetic, spectroscopic, and electrochemical propertiesRichard Veit, Jean Jacques Girerd, Olivier Kahn, Francis Robert, and Yves JeanninCite this: Inorg. Chem. 1986, 25, 23, 4175–…
Lonberg and Meyer [Phys. Rev. Lett. 55, 718 (1985)] have recently discovered in polymer nematics the existence of a critical value ${r}_{c}$=0.303 for the ratio r=${K}_{2}$/${K}_{1}$ between the twist and splay Frank elastic constants, below which a periodic splay-twist distortion is energetically favored with respect…
Electrostatic membrane mirrors are potentially useful as aberration generators. To realize this capability, it is necessary to know the influence functions (each giving mirror response to a single electrode) and then to use a fitting procedure to determine the optimal voltage settings for reproducing a desired surface…
The authors present a theory for the static, paramagnetic, spin susceptibility for metals at finite temperatures. It is based on a 'first principles' mean-field theory of itinerant magnetism and provides an expression which resembles that of a classical Heisenberg model added to an itinerant component. The quantities…
The wall-to-wall polymerization contraction of two restorative resins was investigated in butt-joint dentin cavities prepared in extracted human teeth. The cavity diameter was 4 mm, and the cavity depth ranged between 0.5 and 3.0 mm. The width of the maximum marginal contraction gap was measured, using a light microsc…
This paper describes the results of low-energy electron transmission and secondary-electron emission experiments on thin films of long-chain alkanes deposited on metal substrates. The spectral changes due to crystal-melt phase transition were measured in situ in both experiments. The ground-state energy ${V}_{0}$ of t…
The ability of a group of water-soluble metalloporphyrins to cleave DNA has been investigated. Incubation of Mn3+, Fe3+, or Co3+ complexes of meso-tetrakis(N-methyl-4-pyridiniumyl)porphine (H2T4MPyP) with DNA in the presence of ascorbate, superoxide ion, or iodosobenzene results in DNA breakage. Comparisons between th…
Abstract Two conventions have been used to represent smectite formulas in mineral hydrolysis reactions: exchangeable cations are either included in (monophase structure) or excluded from (charged structure) the Standard State phase designation. Replicate mixtures of K‐saturated Belle Fourche montmorillonite, kaolinite…
Auxospore formation and vegetative cell division are described for Mastogloia smithii. This species is unique among raphid diatoms for its cis-type behavioural anisogamy. This results in both auxospores being formed within one gametangial frustule. Auxospore formation in M. smithii has its closest parallels with certa…