Materials Literature
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The objective of this study was to evaluate the Kelowna multiple element extractant and some EDTA and DTPA modifications for simultaneous determination of potassium and sodium in acid and calcareous soils. To that end, the relationships between K and Na concentrations extracted with 1 N NH 4 OAc and the Kelowna multip…
Ceria‐doped tetragonal zirconia (Ce‐TZP)/alumina (Al 2 O 3 ) composites were fabricated by sintering at 1450° to 1600°C in air, followed by hot isostatic pressing (postsintering hot isostatic pressing) at 1450°C and 100 MPa in an 80 vol% Ar–20 vol% O 2 gas atmosphere. Dispersion of Al 2 O 3 particles into Ce‐TZP was u…
Abstract We have found, that heteropolyacids (HPA) are efficient initiators of cationic polymerizations, including polymerizations of cyclic ethers and acetals, providing high‐molecular‐weight polymers. In several systems (e. g. THF, 1,3‐dioxolane) the degree of polymerization is given by the ratio of concentrations o…
Although toroidal cores wound from grain-oriented silicon iron strip are basically simple devices used in many applications, their magnetic properties are known to vary in a complex manner with core dimensions. The theoretical effects of radial magnetic field and flux density variation, interlamina normal flux, and wi…
The anodic behavior of iron in 0.032 mol·L−1 NaCl/0.003 mol·L−1 NaHCO3 and 1 mol·L−1 Na2SO4/0.003 mol·L−1 NaHCO3 solutions containing 0.05 mol·L−1 H2S at ambient temperature was studied using cyclic voltammetry and the potentiostatic technique. In both solutions, a nonprotective film of mackinawite (Fe(1+x)S) was form…
A photoelectron diffraction study of Ta(100), employing the surface shifted 4 f core levels, has been performed to determine its first interplanar spacing. Photoemission intensities of the bulk and surface shifted 4 f core levels were measured as a function of photon energy at normal emission and near the 〈111〉 symmet…
The observation of a new critical point in liquid-crystal phase transitions is reported. Detailed tilt angle, polarization, and susceptibility measurements of a ferroelectric liquid crystal in the presence of an applied dc electric field show that a first-order transition between the polarized smectic-A phase and the…
Phase transitions of aqueous suspensions of droplets of smectogens have been studied using the collective Cotton-Mouton (CM) technique. Two compounds were examined: NPOOB and 8OCB. A statistical model (previously developed for suspensions of nematogens) has been adapted to describe the collective CM effect in these sy…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of organosilicon compounds. 255. Preparation and x-ray crystal structure of the first pentacoordinate silylsilicatesMitsuo Kira, Kazuhiko Sato, Chizuko Kabuto, and Hideki SakuraiCite this: J. Am. Chem. Soc. 1989, 111, 10, 3747–3748Publication Date (Print):May 1, 19…
As a first phase in the investigation of the feasibility of storing light water reactor spent fuel in air, oxidation tests were performed on nonirradiated UO2 pellets over the temperature range of 150 to 345°C. The objective of the tests was to determine the important independent variables that affect the oxidation be…
The molecular transport of small molecules through polymer films has been the subject of active research over almost three decades [1–8]. The main thrust in this area is either to accumulate a large body of experimental data to assess the stability of polymer films for extreme serviceability or to develop new theories…
Electrochromic films of a series of binary composite hydroxides of nickel and other metals (in a ratio of about 1:10) were deposited cathodically from mixed nitrate solutions onto transparent, conducting substrates. Visible spectra of the composite hydroxides were generally similar to those for nickel hydroxide, itsel…
Plasma chemical vapor deposition (CVD) at 13.56 MHz has been used to produce diamond particles in two different inductively coupled systems with a mixture of methane and hydrogen. The effect of a diamondlike carbon (DLC) overcoating on silicon, niobium, and stainless-steel substrates has been investigated and in the c…
The functions and expression pattern of urea cycle enzymes have undergone considerable changes during the course of evolution. Sequence analyses shows that urea cycle enzymes from mammals are homologous to microbial enzymes of the arginine-metabolic pathway. Recently, an unexpected relationship was found between argin…
The geometrical and insulating properties of regular arrays of oxide masked silicon trenches formed by reactive ion etching have been utilized to enable in situ x-ray photoelectron spectroscopy of specific parts of the trench structures. Different surface portions of the sample structure are differentiated by using (i…
The nitronyl nitroxide 2-phenyl-4,4,5,5-tetramethyl-4,5-dihydr1oH- -imidazolyl- 1- oxy 3-oxide (NITPh) is reduced in the reaction with manganese(I1) hexafluoroacetylacetonate (Mn(hfac),) to yield l-hydroxy-2-phenyl-4,4,5,5-tetramethyl-4,5-dihydro-l~- imidazole (IMHPh). A solid compound of formula [Mn(hfac),(IMHPh)],(N…
The initial response of the unit fibrous cell to an externally applied shear stress is assumed to involve both the bending of fiber sections and slippage at contact points. The criterion used to determine whether a contacting fiber will bend the contacted fiber section or whether it will slip along it depends on the r…
This paper describes novel molecular dynamics simulations of a model amorphous polymer which resembles polyethylene. Methylene groups are represented as single interaction sites and both torsional and angle bending potentials are included. New parameters for both inter- and intramolecular potentials are used as compar…
We have determined the coercive voltage Ec as a function of thickness d for PZT ferroelectric memories. For thick films (≫ 1μm), Ec ∼ d−1/3 , in accord with the theory of Kay and Dunn [Phil Mag. 7, 2027 (1962)]; for submicron films, Ec ∼ d−4/3 , in accord with Neel's theory for coercive magnetic field Hc in thin magne…
To investigate the effects of angle bending terms on the structure of amorphous silica, three different potential models have been developed for the molecular dynamics simulation of vitreous silica.