Materials Literature
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There have been a number of recent investigations of diffusing particles in the presence of traps. Among many applications of this process, we find phenomena such as reaction rates, biological models, and dielectric relaxation. In this paper we present a theory for the absorption probability density for a walker in th…
Abstract The structure analyses of the quartz-type form of GaPO 4 crystals were carried out by using X-ray diffraction intensities at six points of temperatures from 293 K to 747 K. Temperature dependence of the thermal and positional parameters of atoms was examined by applying the conventional harmonic structure-fac…
Abstract The form under which Ti occurs in kaolinitic materials from various environments has been investigated using second derivative diffuse reflectance spectroscopy. The position of the absorption edge may be used as a diagnostic band to determine Ti-phases (anatase, rutile, Ti-gels). Ti-oxides may be detected in…
We have used perturbed-angular-correlation (PAC) spectroscopy to measure static and fluctuating electric-field gradients (EFG's) at the M sites in the pyrochlore ceramic materials, ${\mathit{R}}_{2}$${\mathit{M}}_{2}$${\mathrm{O}}_{7}$ (R=Nd, Sm, Eu, and Gd; M=Zr and Hf). Samples were doped with a small concentration…
Abstract Redox potentials of nonplanar metallododecaphenylporphyrins (MDPP) are determined by cyclic voltammetry. Oxidation processes of MDPP are selectively shifted to negative potentials in comparison with those of planar metalloporphyrins.
PURPOSE: To produce biodurable small diameter microporous vascular grafts with self-sealing properties for vascular access, for peripheral vascular and potentially for coronary artery bypass. The prosthesis should retain compliance and pulsatile flow in situ using a unique modus operandi permitting wall compression wh…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSubstitution chemistry of gallium for titanium in nonlinear optical KTiOPO4: syntheses and single-crystal structures of KGaF1-.delta.(OH).delta.PO4 (.delta. .apprxeq. 0.3) and KGa0.5Ge0.5(F,OH)0.5PO4William T. A. Harrison, Mark L. F. Phillips, and Galen D. StuckyCite this: C…
Effect of Ce, Co, and Sn Substitution on Gas Phase and Electrochemical Hydriding/Dehydriding Properties of LaNi5 , Sridhar Kumar, M. P., Zhang, Wenlin, Petrov, Konstantin, Rostami, Abbas A., Srinivasan, Supramaniam, Adzic, G. D., Johnson, J. R., Reilly, J. J., Lim, Hong S.
The effect of mixed mode loading on the fracture toughness of engineering materials is rationalized in terms of the operative fracture mechanism as well as the deformation field ahead of the crack tip. It was found that mixed mode fracture is of utmost importance in materials which fail by stable ductile fracture caus…
Work‐like silica gel hollow tubes have been prepared using a sol‐gel method. The tubes (see Figure), wich are porous, mostly have one end closed, although occasionally tubes with both ends closed are produced. The preparation method, which involves the hdyrolysis of tetraethylorothosilicate in a mixture of ethanol, am…
In this work we present the analysis of the x-ray-absorption spectra at the silicon ${\mathit{L}}_{2,3}$ and K edges in amorphous ${\mathrm{SiO}}_{2}$ and \ensuremath{\alpha} quartz. This analysis consists in the comparison between experimental data and several calculations based on multiple scattering theory. An exte…
We studied the electronic conduction characteristics of sol-gel ferroelectric Pb(Zr 0.4 Ti 0.6 )O 3 thin-film capacitors by evaluation of time-dependent leakage current ( I-t ) and current-voltage ( I-V ) characteristics along with other dielectric properties. We derived an experimental formula to explain the leakage…
Some spectroscopic methods require solubilization or crystallization of proteins in heavy water because of the large difference in neutron scattering properties between protons and deuterons. In order to quantify the impact of slightly different physical properties of D 2 O and H 2 O, lysozyme solubility curves have b…
Abstract The polymerization of ethylene and 1‐octene by a recently developed homogeneous constrained geometry catalyst produces elastomers and plastomers with narrow molecular weight distributions, short chain branching compositions and the unique presence of long chain branching. Particular morphology and network str…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTToward New Electronic, Magnetic, and Optical Materials: Structure and Properties of the First Homobimetallic Tetrathiafulvalene Tetrathiolate Building BlockRichard D. McCullough, John A. Belot, Arnold L. Rheingold, and Glen P. A. YapCite this: J. Am. Chem. Soc. 1995, 117, 39…
Abstract A phenomenological approach to evaluating the agglomeration rate of growing crystals is presented. Crystals larger than the Kolmogoroff microscale collide because of the fluctuating velocity field. Bridges between the crystals form as a result of competition between crystalline growth and the turbulent veloci…
Three‐dimensional (3D) carbon fiber reinforced SiC and Si 3 N 4 composites have been fabricated using repeated infiltration of an organosilicon slurry under vacuum and pressure. Open porosity of the infiltrated body was reduced from 40% after the first infiltration to approximately 8% after the seventh cycle. Further…
Using TiH 2 and BN as raw materials, the reaction process of TiH 2 and BN in the temperature range 1000°‐1600°C was studied. Then TiN‐TiB 2 composites were prepared by reactive hot pressing. The effects of Ni addition on the sinterability and the mechanical properties of the composites were discussed. A composite cont…
Analytical expressions for calculating the electron paramagnetic resonance parameters D, a, and F are developed using a complete diagonalization procedure for 3${\mathit{d}}^{5}$ ions in a low-symmetry field. As illustrations, the formulas have been applied to RbCdF:${\mathrm{Mn}}^{2+}$, ${\mathrm{RbMnF}}_{3}$:${\math…
The energy-overlap problem in Laue diffraction often makes a Laue diffraction data set incomplete in a systematic way: low-resolution reflections more commonly overlap with other reflections than do reflections at higher resolution. We describe the development and testing of a harmonic deconvolution procedure that res…