The P(bth)2- anion as a Janus head staple between lithium and manganese (bth = benzothiazol-2-yl, C7H4NS)

Deprotonation of HP(bth)2 (1) affords the lithium phosphanide [(Et2O)2Li(bth)2P], (2) with both nitrogen atoms coordinated to the lithium atom while in the heterobimetallic complex [Li(bth)2P{Mn(CO)2Cp}2](n) (3) additionally the phosphorus atom micro-bridges two Mn(CO)2Cp residues.     

Laser-induced molecular beam epitaxy of group-III nitrides

nitrides by laser-induced molecular beam epitaxy (LIMBE). The requirements for the formation of high-quality, monocrystalline layers are much stronger than those for polycrystalline films. We have modified and improved the conventional pulsed laser deposition. In our process, we use metallic targets in a nitrogen environment instead of ceramic or pressed powder nitrides and we employ picosecond laser pulses with high energy (>1 mJ) and high repetition rate (2 kHz). We have grown GaN, AlN, InN, InGaN and Mg-doped GaN on sapphire (0001).     

Structural and electrochemical characterization of nickel hydroxide obtained by the new synthesis route of electrodialysis. a comparison with spherical β-Ni(OH)2

Both structural and electrochemical properties of non-doped nickel hydroxide produced by a new synthesis route of electrodialysis are investigated. A comparison with two spherical β-type Ni(OH)₂ is made. Structural characterization is carried out by X-ray diffraction, vibrational spectroscopy and thermal analysis. Electrochemical properties are studied by cyclic voltammetric and chronoamperometric experiments. The material obtained by electrodialysis is found to have a highly defective structure, which corresponds to a complex electrochemical behavior. More particlarly, it is shown that this new nickel hydroxide is more stable regarding the β → γ transformation. Project financed by the E.U. under the Brite Euram program (#BRPR-CT97-0515) Paper presented at the 6th Euroconference on Solid State Ionics, Sept. 12–19, 1999, Cetraro, Calabria, Italy     

Frequency-dependent protonic conduction and high resolution 1H NMR of KDP around 298 K

Measurements of the dc conductivity, polarisation conductivity, and high resolution ¹H NMR have been carried out on KDP (KH₂PO₄) around 298 K. Comparisons between the different results are reported and an interpretation is proposed in order to clarify the protonic motion within the bulk material.     

A Levenberg–Marquardt Scheme for Nonlinear Image Registration

This paper presents a Levenberg—Marquardt scheme to obtain a displacement vector field u(x)=(u ₁(x),u ₂(x)) ^t , which matches two images recorded with the same imaging machinery. The displacement vector should transform the image location x=(x ₁,x ₂) ^t of an image T, such that the grey level are equal to another image R. The so-called mono-modal image registration problem leads to minimize the nonlinear least squares functional D(u(x))=R(x)–T(x–u(x))².To apply the Levenberg—Marquardt method, we replace the nonlinear functional D by its linearization around a current approximation. The resulting quadratic minimization problem is ill-posed, due to the fact that determining the unknown components of the displacements merely from the images is an underdetermined problem. We use an auxiliary Lagrange term borrowed from linear elasticity theory, which incorporates smoothness constraints to the displacement field. Finally, numerical experiments demonstrate the robustness and effectiveness of the proposed approach.This revised version was published online in October 2005 with corrections to the Cover Date.     

Calculation of the Stokes and Aerodynamic Equivalent Diameters of a short reinforcing fiber

A concern about all reinforcing fibers is the extent to which they are respirable. The degree of respirability of a particle is frequently estimated in terms of its aerodynamic equivalent diameter being less than a certain value (typically 3.5 to 7 μ). However, the aerodynamic equivalent diameter, like the Stokes diameter, is only defined exactly for spheres, which is far from the shape of acicular fibers. Thus, it is useful to be able to calculate, based on actual fiber diameter and aspect ratio, the effective Stokes and aerodynamic equivalent diameters of various fibers. The present paper derives simple expression for relating the two effective diameters to actual fiber dimensions. Calculated results are compared with experimental data for glass fiber and three fractions of phosphate fiber [1], which is a short, reinforcing inorganic fiber. Agreement is seen to be good. Phosphate fiber was fractionated using a sedimentation technique described in the paper. The resulting fractions were characterized by semi-manual measurements of micrographic dimensions and compared with results obtained from particle size instruments based on sedimentation principles. Based on these results, a large weight fraction of phosphate fiber is predicted not to be respirable.