Energetics and dynamics for NO and CO dissociation on Cu(100) and Cu(111)

The dissocn. of NO and CO has been studied on cluster models representing the copper (100) and -(111) single-crystal faces using d. functional quantum calcns. For each surface, several possible reaction paths are proposed, for which we fully optimized the reactant, product, and transition states at the local d. level (LDA). Nonlocal d. functional calcns. (NLDA) were then performed on these optimized geometries. The clusters we used, varying in size between 13 and 31 atoms, produced dissocn. barriers and energies that were reasonably well converged with cluster size. Classical transition-state theory was used to calc. the rates of dissocn. and recombination on the basis of computed frequencies of the predicted transition state and the reactant and product states. The transition states for NO and CO dissocn. on all surfaces can be described as \"tight\" transition states corresponding to preexponentials for dissocn. in the range 1010-1013 s-1. The dissocn. barrier for NO is significantly lower than that for CO. In addn., the more open Cu(100) surface is more reactive toward dissocn. than the close-packed Cu(111) surface. Nonlocal corrections to the LDA functional were found to have a small effect on dissocn. barrier height, but the effect was found to be more profound on the recombination barrier and overall dissocn. energie

Anhydrous deuterium beta alumina Powder diffraction studies at 4.2K, 298K, 573K and 720K

SIGLEAvailable from British Library Document Supply Centre- DSC:9091.9(MPD/NBS--279) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Associations between schistosomiasis and HIV-1 acquisition risk in four prospective cohorts: a nested case-control analysis

Introduction Globally, schistosomes infect approximately 200 million people, with 90% of infections in sub-Saharan Africa. Schistosomiasis is hypothesized to increase HIV-1 acquisition risk, and multiple cross-sectional studies reported strong associations. We evaluated this hypothesis within four large prospective cohorts. Methods We conducted nested case-control analyses within three longitudinal cohorts of heterosexual HIV-1 serodiscordant couples and one female sex worker (FSW) cohort from Kenya and Uganda. The serodiscordant couples studies were conducted between 2004 and 2012 while the FSW cohort analysis included participant follow-up from 1993 to 2014. Cases HIV-1 seroconverted during prospective follow-up; three controls were selected per case. The presence of circulating anodic antigen in archived serum, collected prior to HIV-1 seroconversion, identified participants with active schistosomiasis; immunoblots determined the schistosome species. Data from serodiscordant couples cohorts were pooled, while the FSW cohort was analysed separately to permit appropriate confounder adjustment. Results We included 245 HIV-1 seroconverters and 713 controls from the serodiscordant couples cohorts and 330 HIV-1 seroconverters and 962 controls from the FSW cohort. The prevalence of active schistosomiasis was 20% among serodiscordant couples and 22% among FSWs. We found no association between schistosomiasis and HIV-1 acquisition risk among males (adjusted odds ratio (aOR) = 0.99, 95% CI 0.59 to 1.67) or females (aOR = 1.21, 95% CI 0.64 to 2.30) in serodiscordant couples. Similarly, in the FSW cohort we detected no association (adjusted incidence rate ratio (aIRR) = 1.11, 95% CI 0.83 to 1.50). Exploring schistosome species-specific effects, there was no statistically significant association between HIV-1 acquisition risk andSchistosoma mansoni(serodiscordant couples: aOR = 0.90, 95% CI 0.56 to 1.44; FSW: aIRR = 0.83, 95% CI 0.53 to 1.20) orSchistosoma haematobium(serodiscordant couples: aOR = 1.06, 95% CI 0.46 to 2.40; FSW: aIRR = 1.64, 95% CI 0.93 to 2.87) infection. Conclusions Schistosomiasis was not a strong risk factor for HIV-1 acquisition in these four prospective studies.S. mansoniwas responsible for the majority of schistosomiasis in these cohorts, and our results do not support the hypothesis thatS. mansoniinfection is associated with increased HIV-1 acquisition risk.S. haematobiuminfection was associated with a point estimate of elevated HIV-1 risk in the FSW cohort that was not statistically significant, and there was no trend towards a positive association in the serodiscordant couples cohorts.Host-parasite interactio