Crystal engineering concept has been utilized to modify the physico-chemical parameters of a naturally occurring alkaloid, quinine sulphate, by exploring its H-bond interactions to generate different forms. Quinine sulphate is found to exist in four different crystal forms. The Forms I and II depict endo/exo events suggesting conversion of metastable low melting forms to higher melting and stab...

By using density functional theory on [FeFe]-hydrogenase mimics we deconvolute the function of pendant amine bases in proton transfer to and from the metal center. By dividing the high free energy barrier into one high enthalpy-low entropy barrier and one with a low enthalpy-high entropy, a lower free energy barrier is reached.

58 | CrystEngComm, 2015, 17, 58–72 This journal is © The R a University of Granada, Department of Mineralogy and Petrology, Granada, Spain. E-mail: [email protected] b Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Reymonta 25, 30-059 Kraków, Poland c KU Leuven, Department of Civil Engineering, Leuven, Belgium † Electronic supplementary information (ESI) available: Sol...

Unlike the case of conventional drug formulations, dissolution tests have hitherto not been required for herbal medicinal products commercially available in South Africa. This study investigated dissolution of the South African Sutherlandia frutescens using selected flavonoid glycosides as marker compounds. Dissolution of markers was assessed in three dissolution media at pH 1.2, 4.5 and 6.8, a...

The enthalpy relaxation behavior of Ti41.5Cu37.5Ni7.5Zr2.5Hf5Sn5Si1 bulk metallic glass (BMG) was investigated in this study. It is found that relaxation behavior follows the general characteristics for amorphous materials: the annealing time dependence of recovery enthalpy follows a stretched exponential function with the mean relaxation time obeying an Arrhenius law. In addition, the equilibr...

In this paper we continue our study of the Kelvin-Helmholtz (KH) instability in relativistic planar jets following the long-term evolution of the numerical simulations which were introduced in Paper I. The models have been classified into four classes (I to IV) with regard to their evolution in the nonlinear phase, characterized by the process of jet/ambient mixing and momentum transfer. Models...

The standard enthalpy of formation of a compound is the energy associated with the reaction to form the compound from its component elements. The standard enthalpy of formation is a fundamental thermodynamic property that determines its phase stability, which can be coupled with other thermodynamic data to calculate phase diagrams. Calorimetry provides the only direct method by which the standa...

clarithromycin (cla), a broad-spectrum macrolide, is a poorly soluble drug with dissolution rate limited absorption. the aim of this investigation was to prepare cla nanoparticles from a ternary ground mixture in the presence of sodium lauryl sulfate (sls) and polyvinyl pyrrolidone (pvp) as co-grinding water-soluble compounds, in order to improve the drug dissolution rate. different weight rati...

Here we study the carbonate dissolution history of the deep SE Atlantic as evidenced in proxy records in Core T89-40 from the Walvis Ridge, spanning the last 1.1 million years. All dissolution proxy records (fragmentation index, ratio of planktonic and benthic foraminifera, sand fraction and number of planktonic foraminifera per gram sediment) show similar patterns, unique events, and these pro...

The goal of this study is to use the model system described earlier to make direct measurements of the enthalpy of helix formation at different temperatures. For this we studied model alanine peptides in which helix formation can be triggered by metal (La(3+)) binding. The heat of La(3+) interaction with the peptides at different temperatures is measured by isothermal titration calorimetry. Cir...