Dissolution and Quantification of Tantalum-Containing Compounds: Comparison with Niobium

Dissolution and quantification of different tantalum compounds was undertaken as part of the development of local processes for the beneficiation and separation of tantalum and niobium from different mineral ores. Dissolution of Ta metal powder, TAN-1 CRM, TaF5, TaCl5 and Ta2O5 was undertaken with different acid, alkaline fluxes as well as with microwave digestion while quantification was performed using ICP-OES analysis. The success of the different dissolution methods was evaluated on percentage recovery basis, the results discussed and finally compared with those obtained from the corresponding niobium compounds. Quantification results obtained from this study clearly indicated that the percentage recovery of tantalum depended on i) the type of tantalum source and ii) the dissolution process of the different tantalum compounds. Excellent recoveries were obtained with water soluble TaF5 and TaCl5 with 101(1) and 100(2)% respectively. Low tantalum recovery was obtained for Ta metal and Ta2O5 with microwave digestion in the presence of strong acids (4.1(8) and 9.7(8) %, respectively in the presence of H2SO4) and acidic fluxes (1.5(5) % with K2S2O7). Improved recoveries were obtained using basic fluxes for both the metal and the oxide. Fluxing the metal with KOH resulted in a 85(3) % Ta recovery while a maximum of 68(4) % Ta recovery was obtained for Ta2O5. Tantalum recoveries of between 75(10) and 90(6)% were obtained for TAN-1 CRM (Ta present as Ta2O5) and 95(6)% for Ta2O5 with Li2B4O7 as fluxing agent on the removal of the excess of boric acid prior to analysis. A stability study indicated constant recovery in a basic medium while a decrease of up to 10 % in tantalum recovery was obtained in an acidic environment. A comparison with the niobium results obtained in a previous study highlighted the different acid/base properties of the two oxides as well as a possible alternative dissolution/ separation step for the two elements from the mineral ore.Keywords: Dissolution, microwave, fluxes, tantalum, recover

Transmission of Schistosoma japonicum in Marshland and Hilly Regions of China: Parasite Population Genetic and Sibship Structure

The transmission dynamics of Schistosoma japonicum remain poorly understood, as over forty species of mammals are suspected of serving as reservoir hosts. However, knowledge of the population genetic structure and of the full-sibship structuring of parasites at two larval stages will be useful in defining and tracking the transmission pattern between intermediate and definitive hosts. S. japonicum larvae were therefore collected in three marshland and three hilly villages in Anhui Province of China across three time points: April and September-October 2006, and April 2007, and then genotyped with six microsatellite markers. Results from the population genetic and sibling relationship analyses of the parasites across two larval stages demonstrated that, within the marshland, parasites from cattle showed higher genetic diversity than from other species; whereas within the hilly region, parasites from dogs and humans displayed higher genetic diversity than those from rodents. Both the extent of gene flow and the estimated proportion of full-sib relationships of parasites between two larval stages indicated that the cercariae identified within intermediate hosts in the marshlands mostly came from cattle, whereas in the hilly areas, they were varied between villages, coming primarily from rodents, dogs or humans. Such results suggest a different transmission process within the hilly region from within the marshlands. Moreover, this is the first time that the sibling relationship analysis was applied to the transmission dynamics for S. japonicum

Acculturation, resilience, and the mental health of migrant youth : a cross-country comparative study

202305 bcwwAccepted ManuscriptRGCOthersWorldwide Universities Network (WUN) Research Development Fund; University of Bristol; National Health & Medical Research Council (NHMRC) Career Development Fellowship; National Research Foundation Incentive Funding; University of York; University of Auckland postgraduate fundingPublishe

MC1R Genotype and Plumage Colouration in the Zebra Finch (Taeniopygia guttata): Population Structure Generates Artefactual Associations

Hoffman J, Krause ET, Lehmann K, Krüger O. MC1R Genotype and Plumage Colouration in the Zebra Finch (Taeniopygia guttata): Population Structure Generates Artefactual Associations. PLoS ONE. 2014;9(1): e86519.Polymorphisms at the melanocortin-1 receptor (MC1R) gene have been linked to coloration in many vertebrate species. However, the potentially confounding influence of population structure has rarely been controlled for. We explored the role of the MC1R in a model avian system by sequencing the coding region in 162 zebra finches comprising 79 wild type and 83 white individuals from five stocks. Allelic counts differed significantly between the two plumage morphs at multiple segregating sites, but these were mostly synonymous. To provide a control, the birds were genotyped at eight microsatellites and subjected to Bayesian cluster analysis, revealing two distinct groups. We therefore crossed wild type with white individuals and backcrossed the F1s with white birds. No significant associations were detected in the resulting offspring, suggesting that our original findings were a byproduct of genome-wide divergence. Our results are consistent with a previous study that found no association between MC1R polymorphism and plumage coloration in leaf warblers. They also contribute towards a growing body of evidence suggesting that care should be taken to quantify, and where necessary control for, population structure in association studie

Factors Affecting Disclosure in South African HIV-Positive Pregnant Women

To provide understanding of social and psychological factors that affect disclosure of HIV status among women diagnosed HIV-positive in pregnancy, 438 HIV positive women attending antenatal clinics in Pretoria, South Africa were invited to participate in a longitudinal study. A total of 293 (62%) women were enrolled from June 2003 to December 2004. Questionnaires assessing sociodemographics and psychological measures were administered during pregnancy and at 3 months postdelivery. At enrollment, 59% had disclosed to their partners and 42% to others. This rose to 67% and 59%, respectively, by follow-up. Logistic regression analysis identified being married (adjusted odds Ratio [AOR] 2.32; 95% confidence interval [CI] 1.20–4.47), prior discussion about testing (AOR 4.19; CI 2.34–7.49), having a partner with tertiary education (AOR 2.76; CI 1.29–5.88) and less experience of violence (AOR 0.48; CI 0.24–0.97) as factors associated with having disclosed to partners prior to enrollment. Better housing (AOR 1.26; CI 1.06–1.49), less financial dependence on partners (AOR 0.46; CI 0.25–0.85), and knowing someone with HIV (AOR 2.13; CI 1.20–3.76) were associated with prior disclosure to others. Increased levels of stigma at baseline decreased the likelihood of disclosure to partners postenrollment (AOR 0.91; CI 0.84–0.98) and increased levels of avoidant coping decreased subsequent disclosure to others (AOR 0.84; CI 0.72–0.97). These results provide understanding of disclosure for women diagnosed as HIV positive in pregnancy, and identify variables that could be used to screen for women who require help