Analytic evaluation of integrals in variational calculations of scattering theory

Analytic procedures are presented for the evaluation of the free-free exchange integrals which occur in the variational approach to scattering theory. Expressions are obtained which are suitable for numerical calculation on a computer. The method is based on a (known) analytic formula for the complex Laplace transform of the exponential integral function.     

Bifunctional Adhesion Promoter for Grafting Polypyrrole Films on Metal/Metal Oxide Surfaces

A new class of pyrrole derivatives, ω-[(3-phenyl) pyrrol-1-yl] alkyl phosphonic acids with long chains of 10 and 12 carbon atoms were synthesised to graft polypyrrole layers on metal/metal oxide surfaces. These compounds are bifunctional containing two reactive moieties, pyrrole as the polymerisable group and phosphonic acid as the anchoring group. Contact angle measurements and X-ray photoelectron spectroscopy (XPS) confirmed adsorption with phosphonic acid group attached to the surface. Surface plasmon resonance (SPR) spectroscopy indicated that adsorption starts in seconds and is completed in few hours. Adsorption is followed by surface induced polymerisation with further monomer. We obtained dense and homogeneous polypyrrole films, which were characterised for their morphology and thickness by atomic force microscopy (AFM). The derivatives form a strongly bonded composite of metal with polymer.     

Sunitinib LC–MS/MS Assay in Mouse Plasma and Brain Tissue: Application in CNS Distribution Studies

Sunitinib malate is a multi-targeted tyrosine-kinase inhibitor, currently in clinical trials for glioma. Previously developed methods for preclinical studies in species such as mice have either employed high-performance liquid chromatography (HPLC) or did not describe a detailed analytical method, which could be employed by other preclinical laboratories. In this paper, we have developed and validated a simple, sensitive high-performance liquid chromatography tandem mass-spectrometric method (LC–MS/MS) for the determination of sunitinib concentration in mouse plasma and brain tissue homogenate using dasatinib-free base as the internal standard. A single step liquid–liquid extraction method was used for both the matrices. Since sunitinib exhibits light-induced E/Z isomerism, all sample preparation was done in light-protected conditions. Separation was performed on a ZORBAX Eclipse XDB C18 column 4.6 × 50 mm, 1.8 μm. The mobile phase consisted of 20 mM ammonium formate (with 0.1 % formic acid): acetonitrile (70:30, v/v) pumped isocratically at a flow rate of 0.25 mL min⁻¹ with a total run-time of 13 min. The retention times of sunitinib and dasatinib were 7.8 and 5.5 min, respectively. The calibration curve was linear over the range from 1.95 to 500 ng mL⁻¹ in both plasma and brain tissue homogenate with 1.95 ng mL⁻¹ as the lower limit of quantification (LLOQ) for both the matrices. Inter- and intra-day accuracy and precision was <15 % for low QC, med QC and high QC and <20 % for LLOQ. The method was applied to a pharmacokinetic study in FVB wild-type mice to determine the plasma and brain concentrations after a single oral sunitinib malate dose of 20 mg kg⁻¹.

     

Proteome-Based Profiling of Hypercellulase-Producing Strains Developed Through Interspecific Protoplast Fusion Between Aspergillus nidulans and Aspergillus tubingensis

Thirty heterokaryons, formed by protoplast fusion of Aspergillus nidulans and Aspergillus tubingensis, were selected on the basis of their ability to grow on 2-deoxyglucose (0.2 %, w/v) and intermediate spore color. These heterokaryons were studied for cellulase production using shake flask and solid substrate cultures at 40 °C. Fusants 51 and 28 exhibited appreciably higher levels of endoglucanase, cellobiohydrolase, β-glucosidase, and FPase activities when compared with parental strains. Employing proteomic-based approaches, the differential expression of proteins in secretome of fusants and parental strains were analyzed using two-dimensional electrophoresis. The expression of some of the proteins in the fusants was found to be up/downregulated. The upregulated proteins in the fusant 51 were identified by liquid chromatography–mass spectroscopy as endoxylanase, endochitinase, β-glucosidase, as well as hypothetical proteins. The cellulases produced by fusants 28 and 51 showed improved saccharification of alkali treated rice straw when compared with the parental strains.     

Deactivation of He 23S by thermal electrons

The rate coefficient for deactivation of the metastable 2³S state of He by impact of thermal electrons is deduced from recent calculations of inelastic electron-He cross sections. The deactivation rate is found to be nearly constant with temperature. Computed values range between 2.82 and 3.03 (10^?9 cm³/sec) for T between 0 and 2000°K. De-excitation cross sections are given for low-energy incident electrons.     

Block ionomer complex micelles with cross-linked cores for drug delivery

Soft polymeric nanomaterials were synthesized by template-assisted method involving condensation of the poly(ethylene oxide)-b-polycarboxylate anions by metal ions into core-shell block ionomer complex micelles followed by chemical cross-linking of the polyion chains in the micelle cores. The resulting materials represent nanogels and are capable of swelling in a pH-dependent manner. The structural determinants that guide the self-assembly of the initial micelle templates and the swelling behavior of the cross-linked micelles include the block ionomer structure, the chemical nature of metal ions, the structure of the cross-links and the degree of cross-linking. The application of these materials for loading and release of a drug, cisplatin, is evaluated. These cross-linked block ionomer micelles have promise for delivery of pharmaceutical agents. The text was submitted by the authors in English. This work was supported by the grants from U.S.A. National Institute of Health CA116590 (T.B.), National Science Foundation DMR-0513699 (A.V.K. and T.B.) and Department of Defense USAMRMC 06108004 (A.V.K.).     

Evaluation of an index based on van't Hoff equation to predict PEG-drug eutectic composition

Five poorly soluble drugs namely hydrochlorothiazide, menadione, propylthiouracil, quinine sulfate and sulfamerazine were used to evaluate the ability of an index (I _c) based on the van't Hoff equation to predict the eutectic composition at a higher heating rate than previously published. The term I _c is a dimensionless index which has been defined in the literature and is used to predict eutectic composition. This current work uses this study to determine if the correlation holds true at the higher heating rate of 10°C min^-1. The maximum deviation was observed for quinine sulfate, for which the predicted eutectic composition was 10% lower than what was observed with the DSC. It can be concluded that the Index developed here has a good correlation with the experimentally determined eutectic composition. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sunitinib LC–MS/MS Assay in Mouse Plasma and Brain Tissue: Application in CNS Distribution Studies

Sunitinib malate is a multi-targeted tyrosine-kinase inhibitor, currently in clinical trials for glioma. Previously developed methods for preclinical studies in species such as mice have either employed high-performance liquid chromatography (HPLC) or did not describe a detailed analytical method, which could be employed by other preclinical laboratories. In this paper, we have developed and validated a simple, sensitive high-performance liquid chromatography tandem mass-spectrometric method (LC–MS/MS) for the determination of sunitinib concentration in mouse plasma and brain tissue homogenate using dasatinib-free base as the internal standard. A single step liquid–liquid extraction method was used for both the matrices. Since sunitinib exhibits light-induced E/Z isomerism, all sample preparation was done in light-protected conditions. Separation was performed on a ZORBAX Eclipse XDB C18 column 4.6 × 50 mm, 1.8 μm. The mobile phase consisted of 20 mM ammonium formate (with 0.1 % formic acid): acetonitrile (70:30, v/v) pumped isocratically at a flow rate of 0.25 mL min^?1 with a total run-time of 13 min. The retention times of sunitinib and dasatinib were 7.8 and 5.5 min, respectively. The calibration curve was linear over the range from 1.95 to 500 ng mL^?1 in both plasma and brain tissue homogenate with 1.95 ng mL^?1 as the lower limit of quantification (LLOQ) for both the matrices. Inter- and intra-day accuracy and precision was <15 % for low QC, med QC and high QC and <20 % for LLOQ. The method was applied to a pharmacokinetic study in FVB wild-type mice to determine the plasma and brain concentrations after a single oral sunitinib malate dose of 20 mg kg^?1.     

Synthesis of Specially Designed Adhesion Promoter for Grafting Polypyrrole

Summary: Adhesion of conducting polymers to the metal/metal oxide surfaces is not strong. An attempt was made to modify these reactive metal surfaces by N-derivatised pyrroles. ω-(pyrrol-1-yl alkyl) phosphonic acids with different chain lengths were successfully synthesized and characterized. These derivatives were studied for their adsorption and self-assembling phenomena onto Ti/TiO₂, Ta/Ta₂O₅ and Al/Al₂O₃. Various analytical tools were used to characterize the modified surface. Contact angle measurements indicated an increase in hydrophobicity after adsorption that was further confirmed by Surface Plasmon Resonance (SPR). X-ray Photoelectron Spectroscopy (XPS) studies showed that the molecules are oriented in a fashion such that phosphonic acid group is attached to the metal surface and pyrrole is pointing away from the surface. The oxidation potential of these derivatives was higher than pyrrole as expected. Surface polymerisation was successfully attempted on the modified metal substrates. The polymerised surface was examined under Scanning Electron Microscope (SEM). The new compounds not only function as self-assembling molecules, they also exhibit a new class of reactive functionalized derivatives that can be used as monomers for polymerisation.