Hydrogen-oxygen and carbon monoxide adsorption on Ir, Ir?Pt and Ir?Pd alumina-supported catalysis

From dispersity studies and adsorption isotherms on alumina supported Ir, Ir–Pt and Ir–Pd catalysts, the ratios of O/M=1 and CO/M=1 are obtained. Electron microscopiec results agree with chemisorption data.

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Ir, Ir–Pt Ir–Pd, , O/M=1 CO/M=1. - .

     

Dicationic intermediates involving protonated amides: dual modes of reactivity including the acylation of arenes

In the Br?nsted superacid CF(3)SO(3)H (triflic acid), amides are able to form reactive, dicationic electrophiles. It is shown that these dicationic intermediates participate in two distinctly different types of electrophilic reactions. The protonated amide increases the reactivity of an adjacent electrophilic group, and the protonated amide group itself shows enhanced reactivity arising from an adjacent cationic charge. In the latter case, several types of amides are even capable of reacting with benzene by Friedel-Crafts acylation. [reaction--see text]     

The effect of temperature correction on the measured thickness of formaldehyde zones in diffusion flames for 355 nm excitation

The temperature dependent corrections of the formaldehyde laser induced fluorescence raw signal are discussed for the 355 nm excitation, which is widely available as the third harmonic of Nd-YAG lasers. The temperature dependence of the HCHO partition function is calculated explicitly and the effect of quenching corrections is discussed in view of the absence of experimental data on collision cross-sections. Particular reference is made to the case of HCHO layers in hydrocarbon diffusion flames. It is shown that the thickness of such layers is not affected drastically by the calculated corrections, which has implications for the estimate of the scalar dissipation rate in diffusion flames.     

Precision measurement of the neutron spin asymmetryA(n)(1) and spin-flavor decomposition in the valence quark region

We have measured the neutron spin asymmetry A(n)(1) with high precision at three kinematics in the deep inelastic region at x=0.33, 0.47, and 0.60, and Q(2)=2.7, 3.5, and 4.8 (GeV/c)(2), respectively. Our results unambiguously show, for the first time, that A(n)(1) crosses zero around x=0.47 and becomes significantly positive at x=0.60. Combined with the world proton data, polarized quark distributions were extracted. Our results, in general, agree with relativistic constituent quark models and with perturbative quantum chromodynamics (PQCD) analyses based on the earlier data. However they deviate from PQCD predictions based on hadron helicity conservation.     

Fast lithium ion diffusion in the ternary layered nitridometalate LiNiN

The structure, Li+ diffusion dynamics, and magnetic properties of the layered nitridonickelate(II), LiNiN, have been investigated by powder X-ray diffraction, 7Li solid-state NMR, and SQUID magnetometry and compared and contrasted with those of the Li+ fast ion conductor, Li3N. The replacement of Li+ by Ni2+ with concomitant generation of Li+ vacancies has profound effects on ionic diffusion and electronic properties. The nitridonickelate, akin to its binary parent, displays rapid Li+ ion diffusion but, by contrast, the diffusion process is confined only to the Li-N planes. Further, replacement of Li by Ni leads to a transition from semiconducting to metallic behavior, likely mediated through the creation of infinite, 1D Ni-N chains of increased covalency.     

Isodifferential derivative approach to the spectrophotometric determination of nickel and cobalt mixtures

A graphical method for measuring derivative amplitudes in binary mixtures with overlapping spectra is described. The method is based on the interference-free character of the isodifferential points in the derivative calibration graphs. Cobalt and nickel mixtures are analyzed in the range 0.01–2.5 μg ml^?1 by the formation of coloured chelates with benzyl-2-pyridylketone 2-pyridylhydrazone, with relative standard deviations ?1.5%.     

Palladium-catalyzed intermolecular alpha-arylation of N-protected 2-piperidinones

[reaction: see text] The alpha-arylation of the zinc enolate of N-protected 2-piperidinones with aryl bromides in the presence of a palladium catalyst is described as a general method.     

Polarization transfer in the 4He(e-->,e'p-->)3H reaction up to Q2=2.6 (GeV/c)2

We have measured the proton recoil polarization in the 4He(e-->,e(')p-->)4H reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.