Thermodynamic properties of the aurochloride solute complex AuCI2- at temperatures of 350-500 °C and pressures of 500-1500 bars. Propriétés thermodynamiques du complexe aqueux auro-chloré AuCl2-de 350 à 500°C et de 500 à 1500 bars

The state of gold in chloride solutions has been studied by the solubility method over a temperature range 350-500 °C and a pressure range 0.5-1.5 kbars as a function of acidity, ion CI' concentration and oxygen fugacity. The formation of the AuCl₂ complex have been calculated for the reaction : Au(s)+ HCl⁰ + Cl⁻ + 0.25 O₂(g)= AuCl₂₋+ 0.5 H₂O Our experimental data (lg K°) appear in agreement with a number of experimental data sets from literature using the model of S hock and Helgeson (1988). Using this approach we approximated the AuCl₂₋ thermodynamic properties over a wide range of temperatures (25-750 °C) and pressures (1-1500 bars).L'état de l'or dans les solutions chlorurées a été étudié par la méthode de solubilisation pour des températures allant de 350 à 500 °C et des pressions de 0,5 à 1,5 kb, en fonction de l'acidité des solutions, de la concentration en ion Cl- et de la fugacité de l'oxygène. La formation de l'ion AuCl₂₋ a été démontrée. Les valeurs de la constante d'équilibre ont été calculées pour la réaction : Au(s)+ HCl⁰ + Cl⁻ + 0.25 O₂(g)= AuCl₂₋+ 0.5 H₂O Nos données expérimentales (log K°) apparaissent en bon accord avec une série d'autres données expérimentales de la littérature si on utilise le modèle de S hock et Helgeson (1988). Avec cette approche, les propriétés thermodynamiques de AuCl₂₋ ont été étudiées dans une large gamme de températures (25-750 °C) et de pressions (1-1500 bars).Zotov Alexandr V., Baranova Nina N. Thermodynamic properties of the aurochloride solute complex AuCI2- at temperatures of 350-500 °C and pressures of 500-1500 bars. Propriétés thermodynamiques du complexe aqueux auro-chloré AuCl2-de 350 à 500°C et de 500 à 1500 bars. In: Sciences Géologiques. Bulletin, tome 42, n°4, 1989. Thermodynamique des processus naturels. Thermodynamics of natural processes pp. 335-342

Experimental study of gold-hydrosulphide complexing in aqueous solutions at 350 500°C, 500 and 1000 bars using mineral buffers

International audienceThe solubility of gold was measured in KCl solutions (0.001 0.1 m) at near-neutral to weakly acidic pH in the presence of the K-feldspar-muscovite-quartz, andalusite-muscovite-quartz, and pyrite-pyrrhotite-magnetite buffers at temperatures 350 to 500°C and pressures 0.5 and 1 kbar. These mineral buffers were used to simultaneously constrain pH, f(S2), and f(H2). The experiments were performed using a CORETEST flexible Ti-cell rocking hydrothermal reactor enabling solution sampling at experimental conditions. Measured log m(Au) (mol/kg H2O) ranges from ?7.5 at weakly acid pH to ?5.9 in near-neutral solutions, and increases slightly with temperature. Gold solubility in weakly basic and near-neutral solutions decreases with decreasing pH at all temperatures, which implies that Au is the dominant Au species in solution. In more acidic solutions, solubility is independent of pH. Comparison of the experimentally measured solubilities with literature values for Au hydrolysis constants demonstrates that at 350°C AuHS(aq)0 dominates Au aqueous speciation at the weakly acidic pH and f(S2)/f(H2) conditions imposed by the pyrite-pyrrhotite-magnetite buffer. In contrast, at temperatures >400°C AuHS(aq)0 becomes less important and AuOH(aq)0 predominates in weakly acid solutions. Solubility data collected in this study were used to calculate the following equilibrium reaction constants: Au+HS(aq)0=AuHS(aq)0+0.5H,K and Au+HS(aq)0+HS=Au(HS)2?+0.5H,K The calculated log K values are ?5.25 ± 0.35 and ?5.92 ± 0.36 at 350°C (500 1000 bars) and 400°C/1000 bars, respectively. The log K values are ?1.68 ± 0.42 at 350°C/500 bars, ?1.40 ± 0.41 at 350°C/1000 bars, ?2.14 ± 0.42 at 400°C/ 500 bars, ?1.75 ± 0.40 at 400°C/1000 bars, ?1.87 ± 0.40 at 450°C/1000 bars, and ?1.80 ± 0.40 at 500°C/1000 bars. Equilibrium constants for both reactions are retrograde with respect to temperature, but this effect is more pronounced for AuHS0(aq) than for Au(HS)2?. The K values? dependence on temperature, as well as the calculated values of K are consistent with the data of Benning and Seward (1996). The calculated values of K are between those determined by Benning and Seward (1996) and Gibert et al. (1998)

Expression of Cytochrome c3 from Desulfovibrio vulgaris in Plant Leaves Enhances Uranium Uptake and Tolerance of Tobacco

Cytochrome c3 (uranyl reductase) from Desulfovibrio vulgaris can reduce uranium in bacterial cells and in cell-free systems. This gene was introduced in tobacco under control of the RbcS promoter, and the resulting transgenic plants accumulated uranium when grown on a uranyl ion containing medium. The uptaken uranium was detected by EM in chloroplasts. In the presence of uranyl ions in sublethal concentration, the transgenic plants grew phenotypically normal while the control plants’ development was impaired. The data on uranium oxidation state in the transgenic plants and the possible uses of uranium hyperaccumulation by plants for environmental cleanup are discussed

Vaccinal Prevention of the Diseases Caused by Human Papillomavirus: Evidence-Based Medicine. Review of Clinical Guidelines

The article is devoted to the urgent problem of papillomavirus infection, the extremely high prevalence of which determines the key contribution to the structure of morbidity and mortality from oncological diseases. A chronic persistent course, resulting in benign and malignant tumors in the infection atrium, makes scientists seek new ways of treatment. A specific vaccinal prevention is recognized to be the only reliable protection method today. The article is an updated review of the clinical guidelines developed and approved by the professional association «Union of Pediatricians of Russia» in 2016 for a vaccinal prevention of the diseases caused by human papillomavirus, first published on pediatr-russia.ru. The widespread introduction of vaccines against human papillomavirus, which have confirmed the clinical efficacy and safety, can significantly reduce the global burden of diseases associated with papillomavirus infection

Characterizing neuroanatomic heterogeneity in people with and without ADHD based on subcortical brain volumes

Background Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder. Neuroanatomic heterogeneity limits our understanding of ADHD’s etiology. This study aimed to parse heterogeneity of ADHD and to determine whether patient subgroups could be discerned based on subcortical brain volumes. Methods Using the large ENIGMA-ADHD Working Group dataset, four subsamples of 993 boys with and without ADHD and to subsamples of 653 adult men, 400 girls, and 447 women were included in analyses. We applied exploratory factor analysis (EFA) to seven subcortical volumes in order to constrain the complexity of the input variables and ensure more stable clustering results. Factor scores derived from the EFA were used to build networks. A community detection (CD) algorithm clustered participants into subgroups based on the networks. Results Exploratory factor analysis revealed three factors (basal ganglia, limbic system, and thalamus) in boys and men with and without ADHD. Factor structures for girls and women differed from those in males. Given sample size considerations, we concentrated subsequent analyses on males. Male participants could be separated into four communities, of which one was absent in healthy men. Significant case–control differences of subcortical volumes were observed within communities in boys, often with stronger effect sizes compared to the entire sample. As in the entire sample, none were observed in men. Affected men in two of the communities presented comorbidities more frequently than those in other communities. There were no significant differences in ADHD symptom severity, IQ, and medication use between communities in either boys or men. Conclusions Our results indicate that neuroanatomic heterogeneity in subcortical volumes exists, irrespective of ADHD diagnosis. Effect sizes of case–control differences appear more pronounced at least in some of the subgroups

Alirocumab and cardiovascular outcomes after acute coronary syndrome

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Alirocumab and Cardiovascular Outcomes after Acute Coronary Syndrome

BACKGROUN