Solubility of Hesperetin in Mixed Solvents

The study of the solubility of important biomolecules such as flavonoids is essential to support the design of several separation processes in the food and pharmaceutical industries. Following our previous studies, new solubility data of hesperetin in the mixed solvents water + acetone, water + ethanol, and water + methanol were measured, at 298.2 K, by the isothermal shake-flask method. The results obtained show three solid–liquid phase diagrams with distinct features. Additionally, the solid crystals obtained from the solubility studies were analyzed by powder X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis indicating that, depending on the mixed solvents composition, two different crystal structures of hesperetin, already described in the literature, can be obtained, corresponding either to the anhydrous or the monohydrate forms

Antimicrobial Stewardship Programs: Role in Optimizing Infectious Disease Outcomes

Given increasing trends in antimicrobial resistance and the resulting limited treatment options, the treatment of hospital-acquired infections poses a significant challenge to healthcare providers. Optimization and conservation of current antimicrobials are necessary. Antimicrobial stewardship programs aim to optimize the use of antimicrobial agents through a multidisciplinary effort utilizing different strategies (prospective audit and feedback, formulary restriction and preauthorization, education, guidelines and clinical pathways, antimicrobial order forms, de-escalation, pharmacokinetic/pharmacodynamic dose optimization) either alone or in combination. Effective antimicrobial stewardship programs are proactive, sustainable, and capable of optimizing antimicrobial choices, dosages, and durations to decrease the emergence of antimicrobial resistance. Hospital resources and personnel dictate the most feasible strategies to achieve these outcomes. DOI: 10.2165/0115677-200816060-00005Antibacterials, Disease-management-programmes

Phenylnaphthalenes: Sublimation Equilibrium, Conjugation, and Aromatic Interactions

In this work, the interplay between structure and energetics in some representative phenylnaphthalenes is discussed from an experimental and theoretical perspective. For the compounds studied, the standard molar enthalpies, entropies and Gibbs energies of sublimation, at <i>T</i> = 298.15 K, were determined by the measurement of the vapor pressures as a function of <i>T</i>, using a Knudsen/quartz crystal effusion apparatus. The standard molar enthalpies of formation in the crystalline state were determined by static bomb combustion calorimetry. From these results, the standard molar enthalpies of formation in the gaseous phase were derived and, altogether with computational chemistry at the B3LYP/6-311++G­(d,p) and MP2/cc-pVDZ levels of theory, used to deduce the relative molecular stabilities in various phenylnaphthalenes. X-ray crystallographic structures were obtained for some selected compounds in order to provide structural insights, and relate them to energetics. The thermodynamic quantities for sublimation suggest that molecular symmetry and torsional freedom are major factors affecting entropic differentiation in these molecules, and that cohesive forces are significantly influenced by molecular surface area. The global results obtained support the lack of significant conjugation between aromatic moieties in the α position of naphthalene but indicate the existence of significant electron delocalization when the aromatic groups are in the β position. Evidence for the existence of a quasi T-shaped intramolecular aromatic interaction between the two outer phenyl rings in 1,8-di­([1,1′-biphenyl]-4-yl)­naphthalene was found, and the enthalpy of this interaction quantified on pure experimental grounds as −(11.9 ± 4.8) kJ·mol^–1, in excellent agreement with the literature CCSD­(T) theoretical results for the benzene dimer