Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Pre-ART HIV-1 DNA in CD4+ T cells correlates with baseline VIRO-immunological status and outcome in patients under first-line ART

Objectives We evaluated the association between pre-ART HIV DNA and HIV-infected participant characteristics at baseline as well as with their response to first-line ART. Methods Four hundred and thirty-three patients from the ICONA cohort, starting first-line ART after the year 2000, were analysed. Pre-ART HIV DNA was quantified with the modified COBAS TaqMan HIV-1 Test and normalized by CD4+ T cells. Linear correlation between pre-ART HIV DNA and other continuous markers (HIV RNA, CD4 count, markers of inflammation and coagulation) at baseline was evaluated by means of Pearson correlation coefficient and a linear regression model. Survival analyses and Cox regression models were used to study the association between pre-ART HIV DNA and time to VIRO-immunoclinical events. Results Pre-ART HIV DNA [median (IQR): 10 \u20ac 702 (3397-36 \u20ac 632) copies/10 6 CD4+ T cells] was correlated with pre-ART HIV RNA [R 2 = +0.44, (P 10 \u20ac 000, 81.1% for 1000-10 \u20ac 000 and 86.4% for 10-1000 copies/10 6 CD4+ T cells; P = 0.0004). Higher pre-ART HIV DNA was also correlated with increased risk of VIROlogical rebound (defined as HIV RNA >50 copies/mL) by 24 months (17.2% for >10 \u20ac 000, 7.4% for 1000-10 \u20ac 000 and 4.3% for 10-1000 copies/10 6 CD4+ T cells; P = 0.0048). Adjusted HRs of all VIROlogical rebound definitions confirmed these findings (P 64 0.02). Conclusions Pre-ART HIV DNA, along with HIV RNA and CD4+ T cell count, should be considered as a new staging marker to better identify people at lower (or higher) risk of viral rebound following achievement of VIROlogical suppression ( 6450 copies/mL)