Search

Photoemmssion electron microscopy was employed to real-time and in situ study CO adsorption on the O-saturated AG/Pt(110) composite surface. The results imply that surface species may migrate not only from weakly bound sites to strongly bound sites but also from strongly bound sites to weakly bound sites during heterogenous catalysis reactions.

The temperature programmed reaction spectroscopy (TPRS) and reflection-absorption infrared spectroscopy (RAIRS) are employed to investigate the effect of fluorine substitution on the geometrical orientations and the reaction pathways of CH3CH2(a) and CF3CH2(a) on Ag(111). It was seen that the anchoring of CF3CH2(a) by both Ag-C and Ag...F interactions increases the activation energy of CF3CH2(a) migration compared to CH3CH2(a) migration and thus suppresses migratory coupling and facilitates beta-fluorine elimination.

The reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) are employed for examining the growth of naphthalene films on Ag(111). The surface infrared spectroscopy selection rule is used for the calculation of the molecular orientation of naphthalene.

Ultrafine silicon carbide (SiC) powders were surface-modified using ethyl orthosilicate (TEOS) combined with ethylene glycol. SiC suspensions with favorable rheological properties, low viscosity, and high solid loading were successfully obtained. The mechanisms of the compound surface modification for SiC powders as well as the influences of the compound surface modification not only on functional groups and charge state of the surface for SiC powders but also on the rheological properties of SiC suspensions were investigated in the present study. The results show that under alkaline conditions and acidic conditions, the surface charge states of SiC powders were [Si-OCH2CH2O]−and [Si-OCH2CH2OH2]+, respectively. The absolute value of zeta potential reached the maximum value of 22.69 mV at pH 11. Additionally, with added 1 wt% TEOS and 3 wt% ethylene glycol, the SiC suspensions exhibited good rheological properties, low viscosity and high stability due to the steric hindrance and electrostatic repulsion offered by the [Si-OCH2CH2O]-with a high concentration. [ABSTRACT FROM PUBLISHER]

The interactions of NO2 with Ag(1 1 1) at various temperatures were investigated by means of temperature programmed desorption and reflection–adsorption infrared spectroscopy and found to be sensitively coverage- and temperature-dependent. During dosing at 508 K, NO2 decomposes into NO(g) and O(a). NO2 decomposes at 215 K also, however, NO and O remain adsorbed. The NO(a) occupy threefold-bridged sites and atop sites in sequence. Orientations of the NO(a) axes are affected by neighboring O(a). A sharp and narrow desorption peak (γ-NO) arises for high NO2 doses. During dosing at 90 K, decomposition occurs initially and is followed sequentially by accumulation of NO2(a), NO3(a), N2O4 monolayer and N2O4 multilayer. NO2(a) chemisorbs to form a Ag(1 1 1) μ-N, O-nitrito surface chelate with Cs symmetry. Upon heating, the N2O4 multilayer and monolayer desorb molecularly while most NO2(a) disproportionates into NO(g) or NO(a) and NO3(a) at 165 K. Surface NO3(a) decomposes below 320 K. All surface species except O(a) desorb below 500 K. [Copyright &y& Elsevier]

The proinflammatory cytokine interferon (IFN)-γ has been shown to influence the course of multiple sclerosis (MS). The IFN-γ (IFNG) contains a multiallelic dinucleotide repeat in intron 1. To investigate whether alleles at this locus influence susceptibility to MS, we performed linkage and familial association analyses on 100 sibling pairs from four Nordic countries, and case-control association analysis on 220 intermediately disabled sporadic MS patients and 266 controls. To determine the effect of the polymorphism on disease outcome, we compared genotype frequencies in the most and least disabled octiles of a total cohort of 913 cases. We also measured IFN-γ mRNA levels in unstimulated peripheral blood mononuclear cells from 46 MS patients and 27 controls grouped according to IFNG intron 1 genotype. Both nonparametric linkage analysis and transmission disequilibrium testing of the 100 sibling pairs produced negative results. Genotype frequencies for intermediate-MS patients did not differ significantly from those for controls; nor did genotype frequencies in the benign-MS octile differ significantly from those in the severe-MS octile. Comparison of IFN-γ mRNA levels in genotype-conditioned subgroups revealed no significant differences. Thus, alleles at the IFNG intron 1 dinucleotide repeat appear to affect neither MS susceptibility and severity nor IFN-γ mRNA expression in vivo. [ABSTRACT FROM AUTHOR]

High-spin states in 143Pm have been investigated via the 128Te(19F,4nγ)143Pm reaction using techniques of in-beam γ-spectroscopy. γ-ray singles, γ-γ coincidences, γ-ray anisotropies and DCO ratios have been measured. Based on these measurements, the level scheme of 143Pm has been extended up to an excitation energy of 10535.4 keV, including 48 new γ-rays deexciting 28 new levels. The yrast levels in 143Pm can be understood qualitatively in the framework of a weak-coupling model. [ABSTRACT FROM AUTHOR]