Phase equilibrium data and thermodynamic modeling of the system (CO2 + biodiesel + methanol) at high pressures

The main objective of this work was to investigate the high pressure phase behavior of the binary systems {CO₂(1) + methanol(2)} and {CO₂(1) + soybean methyl esters (biodiesel)(2)} and the ternary system {CO₂(1) + biodiesel(2) + methanol(3)} were determined. Biodiesel was produced from soybean oil, purified, characterized and used in this work. The static synthetic method, using a variable-volume view cell, was employed to obtain the experimental data in the temperature range of (303.15 to 343.15) K and pressures up to 21 MPa. The mole fractions of carbon dioxide were varied according to the systems as follows: (0.2383 to 0.8666) for the binary system {CO₂(1) + methanol(2)}; (0.4201 to 0.9931) for the binary system {CO₂(1) + biodiesel(2)}; (0.4864 to 0.9767) for the ternary system {CO₂(1) + biodiesel(2) + methanol(3)} with a biodiesel to methanol molar ratio of (1:3); and (0.3732 to 0.9630) for the system {CO₂ + biodiesel + methanol} with a biodiesel to methanol molar ratio of (8:1). For these systems, (vapor + liquid), (liquid + liquid), (vapor + liquid + liquid) transitions were observed. The phase equilibrium data obtained for the systems were modeled using the Peng–Robinson equation of state with the classical van der Waals (PR-vdW2) and Wong-Sandler (PR–WS) mixing rules. Both thermodynamic models were able to satisfactorily correlate the phase behavior of the systems investigated and the PR–WS presented the best performance.     

87Sr solid-state NMR as a structurally sensitive tool for the investigation of materials: antiosteoporotic pharmaceuticals and bioactive glasses

Strontium is an element of fundamental importance in biomedical science. Indeed, it has been demonstrated that Sr(2+) ions can promote bone growth and inhibit bone resorption. Thus, the oral administration of Sr-containing medications has been used clinically to prevent osteoporosis, and Sr-containing biomaterials have been developed for implant and tissue engineering applications. The bioavailability of strontium metal cations in the body and their kinetics of release from materials will depend on their local environment. It is thus crucial to be able to characterize, in detail, strontium environments in disordered phases such as bioactive glasses, to understand their structure and rationalize their properties. In this paper, we demonstrate that (87)Sr NMR spectroscopy can serve as a valuable tool of investigation. First, the implementation of high-sensitivity (87)Sr solid-state NMR experiments is presented using (87)Sr-labeled strontium malonate (with DFS (double field sweep), QCPMG (quadrupolar Carr-Purcell-Meiboom-Gill), and WURST (wideband, uniform rate, and smooth truncation) excitation). Then, it is shown that GIPAW DFT (gauge including projector augmented wave density functional theory) calculations can accurately compute (87)Sr NMR parameters. Last and most importantly, (87)Sr NMR is used for the study of a (Ca,Sr)-silicate bioactive glass of limited Sr content (only ~9 wt %). The spectrum is interpreted using structural models of the glass, which are generated through molecular dynamics (MD) simulations and relaxed by DFT, before performing GIPAW calculations of (87)Sr NMR parameters. Finally, changes in the (87)Sr NMR spectrum after immersion of the glass in simulated body fluid (SBF) are reported and discussed.     

Efficient and eco-friendly synthesis of iodinated aromatic building blocks promoted by iodine and hydrogen peroxide in water: a mechanistic investigation by mass spectrometry

The reaction of aromatic and heteroaromatic compounds with molecular iodine in the presence of aqueous hydrogen peroxide using water without any co-solvent at 50 °C for 24 h produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in very good yields. In addition, a mechanistic investigation for the iodination process was carried out by mass spectrometry.     

Development and validation of a rapid and sensitive LC-ESI-MS/MS method for ondansetron quantification in human plasma and its application in comparative bioavailability study

The validation of a high throughput and specific method using a high‐performance liquid chromatography coupled to electrospray (ES+) ionization tandem triple quadrupole mass spectrometric (LC‐ESI‐MS/MS) method for ondansetron quantification in human plasma is described. Human plasma samples were extracted by liquid–liquid extraction (LLE) using methyl tert‐butyl ether and analyzed by LC‐ESI‐MS/MS. The limit of quantification was 0.2 ng/mL and the method was linear in the range 0.2–60 ng/mL. The intra‐assay precisions ranged from 1.6 to 7.7%, while inter‐assay precisions ranged from 2.1 to 5.1%. The intra‐assay accuracies ranged from 97.5 to 108.2%, and the inter‐assay accuracies ranged from 97.3 to 107.0%. The analytical method was applied to evaluate the relative bioavailability of two pharmaceutical formulations containing 8 mg of ondansetron each in 25 healthy volunteers using a randomized, two‐period crossover design. The geometric mean and respective 90% confidence interval (CI) of ondansetron test/reference percent ratios were 90.15% (81.74–99.44%) for C_max and 93.11% (83.01–104.43%) for AUC_0–t. Based on the 90% confidence interval of the individual ratios (test formulation/reference formulation) for C_max and AUC_0‐inf, it was concluded that the test formulation is bioequivalent to the reference one with respect to the rate and extent of absorption of ondansetron. Copyright © 2010 John Wiley & Sons, Ltd.     

Electrochemical Sulphenylation/Cyclization of Quinones: A Rapid,Green, and Efficient Access to Cytotoxic Compounds

Undivided electrochemical cells enable economical preparation of sulphur-containing naphthoquinones through electrochemical sulphenylation of quinoidal compounds. The environmentally friendly and efficient protocol eliminates the use of chemical oxidants and facilitates the synthesis of the desired molecules. This approach offers an efficient and versatile method to synthesize quinones that exhibit cytotoxicity against cancer cell lines.     

Molten Salts-Driven Discovery of a Polar Mixed-Anion 3D Framework at the Nanoscale: Zn4Si2O7Cl2, Charge Transport and Photoelectrocatalytic Water Splitting

Mixed-anion compounds widen the chemical space of attainable materials compared to single anionic compounds, but the exploration of their structural diversity is limited by common synthetic paths. Especially, oxychlorides rely mainly on layered structures, which suffer from low stability during photo(electro)catalytic processes. Herein we report a strategy to design a new polar 3D tetrahedral framework with composition Zn₄Si₂O₇Cl₂. We use a molten salt medium to enable low temperature crystallization of nanowires of this new compound, by relying on tetrahedral building units present in the melt to build the connectivity of the oxychloride. These units are combined with silicon-based connectors from a non-oxidic Zintl phase to enable precise tuning of the oxygen content. This structure brings high chemical and thermal stability, as well as strongly anisotropic hole mobility along the polar axis. These features, associated with the ability to adjust the transport properties by doping, enable to tune water splitting properties for photoelectrocatalytic H₂ evolution and water oxidation. This work then paves the way to a new family of mixed-anion solids