A two‐phase adaptive finite element method for solid–fluid coupling in complex geometries

In this paper we present a method to solve the Navier–Stokes equations in complex geometries, such as porous sands, using a finite‐element solver but without the complexity of meshing the porous space. The method is based on treating the solid boundaries as a second fluid and solving a set of equations similar to those used for multi‐fluid flow. When combined with anisotropic mesh adaptivity, it is possible to resolve complex geometries starting with an arbitrary coarse mesh. The approach is validated by comparing simulation results with available data in three test cases. In the first we simulate the flow past a cylinder. The second test case compares the pressure drop in flow through random packs of spheres with the Ergun equation. In the last case simulation results are compared with experimental data on the flow past a simplified vehicle model (Ahmed body) at high Reynolds number using large‐eddy simulation (LES). Results are in good agreement with all three reference models. Copyright © 2010 John Wiley & Sons, Ltd.     

Hyperbolic smoothing and penalty techniques applied to molecular structure determination

This work considers the problem of estimating the relative positions of all atoms of a protein, given a subset of all the pair-wise distances between the atoms. This problem is NP-hard, and the usual formulations are nonsmoothed and nonconvex, having a high number of local minima. Our contribution is an efficient method that combines the hyperbolic smoothing and the penalty techniques that are useful in obtaining differentiability and reducing the number of local minima.     

Enantioselective Iridium-Catalyzed Allylic Arylation

We describe herein the development of the first iridium-catalyzed allylic substitution using arylzinc nucleophiles. High enantioselectivities were obtained from the reactions, which used commercially available Grignard reagents as the starting materials. This methodology was also shown to be compatible with halogen/metal exchange reactions. Its synthetic potential is demonstrated by its application towards the formal synthesis of (+)-sertraline.     

Determination of intracellular glutathione and cysteine using HPLC with a monolithic column after derivatization with monobromobimane

An optimized high‐performance liquid chromatography (HPLC) method is used to show that, as myoblasts differentiate into multinucleated muscle fibers, there is a shift to a more oxidized cell redox state. The HPLC method incorporated derivatization with monobromobimane for the determination of the reduced (GSH) and oxidized (GSSG) forms of glutathione and the reduced (Cys) and oxidized (CysSS) forms of cysteine. The derivatization was optimized to improve the sensitivity of the approach; the limits of detection for glutathione and cysteine were 3 × 10^?8 and 5 × 10^?8 M , respectively. Copyright © 2009 John Wiley & Sons, Ltd.     

The Interaction of Serum Albumin with Cholesterol Containing Lipid Vesicles

In this paper, the interaction of both human blood serum (the primary fraction of which is serum albumin) and pure human serum albumin (HSA) with surface immobilised lipid vesicles was measured by combined Surface Plasmon Resonance (SPR) and Surface Plasmon enhanced Fluorescence (SPEFS), and fluorescence microscopy. It was found that both blood serum and HSA showed specific binding to vesicles which contained cholesterol, resulting in increased membrane permeability and release of encapsulated fluorescent dye. This effect was not seen with heat inactivated blood serum, heat inactivated HSA or in vesicles not containing cholesterol. These results suggest that HSA may have a physiological role over and beyond that of fatty acid carrier, possibly acting to regulate vascular endothelial cell cholesterol concentration.     

Toxicological determination and in vitro metabolism of the designer drug methylenedioxypyrovalerone (MPDV) by gas chromatography/mass spectrometry and liquid chromatography/quadrupole time‐of‐flight mass spectrometry

A method for the toxicological screening of the new designer drug methylenedioxypyrovalerone (MDPV) is described; with an emphasis on its application for anti‐doping analysis. The metabolism of MDPV was evaluated in vitro using human liver microsomes and S9 cellular fractions for CYP450 phase I and uridine 5′‐diphosphoglucuronosyltransferase (UGT) and sulfotransferase (SULT) phase II metabolism studies. The resulting metabolites were subsequently liquid/liquid extracted and analyzed using gas chromatography/mass spectrometry (GC/MS) as trimethylsilyl (TMS) derivatives. The structures of the metabolites were further confirmed by accurate mass measurement using a liquid chromatography/quadrupole time‐of‐flight (LC/QTOF) mass spectrometer. The studies demonstrated that the main metabolites of MDPV are catechol and methyl catechol pyrovalerone, which are in turn sulfated and glucuronated. The method for the determination of MDPV in urine has been fully validated by assessing the limits of detection and quantification, linearity, repeatability, and accuracy. This validation demonstrates the suitability for screening of this stimulant substance for anti‐doping and forensic toxicology purposes. Copyright © 2010 John Wiley & Sons, Ltd.