Synthesis and biological activity of new 1,3-dioxolanes as potential antibacterial and antifungal compounds

A series of new enantiomerically pure and racemic 1,3-dioxolanes 1-8 was synthesized in good yields and short reaction times by the reaction of salicylaldehyde with commercially available diols using a catalytic amount of Mont K10. Elemental analysis and spectroscopic characterization established the structure of all the newly synthesized compounds. These compounds were tested for their possible antibacterial and antifungal activity. Biological screening showed that all the tested compounds, except 1, show excellent antifungal activity against C. albicans, while most of the compounds have also shown significant antibacterial activity against S. aureus, S. epidermidis, E. faecalis and P. aeruginosa.     

Investigation of Generalized Relative Permeability Coefficients for Electrically Assisted Oil Recovery in Oil Formations

Evaluation of relative permeability coefficients is one of the key steps in reliable simulation of two-phase flow in porous media. An extensive body of work exists on evaluation of these coefficients for two-phase flow under pressure gradient. Oil transport under an applied electrical gradient in porous media is also governed by the principles of two-phase flow, but is less understood. In this paper, relative permeability coefficients under applied electric field are evaluated for a specific case of two- phase fluid flow in water-wet porous media, where the second fluid phase is oil. It is postulated that the viscous drag on the oil phase, exerted by the electro-osmotic flow of the water phase, is responsible for the transport of oil in the absence of a pressure gradient. Reliable prediction of the flow patterns necessitates accurate representation and determination of the relative permeability coefficients under the electrical gradient. The contribution of each phase to the flow is represented mathematically, and the relative permeability coefficients are evaluated through electro-osmotic flow measurements conducted on oil bearing rock cores.     

Structural elucidation of the tetrasaccharide pool in enoxaparin sodium

Low-molecular-weight heparins (LMWHs) are produced from heparin by various depolymerization strategies, which result in a reduction of the average molecular weight of the polysaccharide chains, a reduction of the anti-factor IIa activity (and a concomitant increase in the anti-factor Xa/anti-factor IIa ratio), and introduction of process-related structural signatures. Numerous techniques have been developed to characterize LMWHs and to measure the type and extent of structural modifications that are introduced as a function of the depolymerization process. We present here an analysis of the tetrasaccharide pool of enoxaparin sodium, a LMWH produced by chemical β-elimination of heparin benzyl ester. We identify the predominant sequences present within the tetrasaccharide pool and demonstrate that this pool provides a sensitive, specific readout of the physicochemical process conditions used to generate enoxaparin sodium.     

Statistical approximation properties of q-Bleimann,Butzer and Hahn operators

The main aim of this study is to introduce a new generalization of q-Bleimann, Butzer and Hahn operators and obtain statistical approximation properties of these operators with the help of the Korovkin type statistical approximation theorem. Rates of statistical convergence by means of the modulus of continuity and the Lipschitz type maximal function are also established. Our results show that rates of convergence of our operators are at least as fast as classical BBH operators. The second aim of this study is to construct a bivariate generalization of the operator and also obtain the statistical approximation properties.     

Optimizing product assortment under customer-driven demand substitution

The problem of product assortment and inventory planning under customer-driven demand substitution is analyzed and a mathematical model for this problem is provided in this paper. Realistic issues in a retail context such as supplier selection, shelf space constraints, and poor quality procurement are also taken into account. The performance of three modified models, one that neglects customers’ substitution behavior, another that excludes supplier selection decision, and one that ignores shelf space limitations, are analyzed separately with computational experiments. The results of the analysis demonstrate that neglecting customer-driven substitution or excluding supplier selection or ignoring shelf space limitations may lead to significantly inefficient assortments. The effects of demand variability and substitution cost on optimal assortment and supplier selection decisions as well as on the optimal revenue are also investigated. The main contribution of this paper is the development of a practical and flexible model to aid retailers in finding optimal assortments to maximize the expected profit.     

Phase transitions in nonequilibrium electron-hole systems of Si/SiGe/Si nanoheterostructures

The exciton condensation in a Si_1?x Ge _x solid solution layer of Si/Si_1?x Ge _x /Si heterostructures with the formation of electron-hole liquid has been investigated by low-temperature photoluminescence spectroscopy. In the temperature range above the critical temperature of the transition from an exciton gas to electron-hole liquid, a Mott transition from an exciton gas to electron-hole plasma has been found and investigated.     

Structural,Morphological and Optical Properties of Well-Ordered CdO Nanostructures Synthesized by Easy-Economical Chemical Bath Deposition Technique

In this Study, Cadmium Oxide (CdO) nanostructures were synthesized by using Chemical Bath Deposition Technique. The synthesized process was carried out at room temperature. The structural and optical properties of nanostructures was characterized by XRD, SEM and UV-Vis techniques. As a result, the CdO nanostructures are oriented along (111) plane of cubic crystal structure. The morphology of CdO nanostructures showed interconnected prism-like and cauliflower-type cluster nanostructure. The UV results of this structures with high absorbtion coefficient are observed to be in accordance with the CdO nanoparticles.     

Electroanalytical Behaviour of a Nanoarray Self-Assembled Thiocholesterol Gold Electrode

Thiocholesterol forms a self-assembled monolayer (SAM) on polycrystalline gold, offering a defect-rich hydrophobic surface. This SAM gold electrode has been exploited in batch and flow injection analysis (FIA) as it allows selective detection of hydrophobic analytes such as phenothiazines in presence of potentially interfering species such as ascorbic acid. Several phenothiazines have been investigated. Quantification has been achieved in FIA, in a broad linear concentration range: 0.5–100?μM. The stability of the modified electrode allows more than 500 sample injections in FIA.     

Determination of chromatographic dissociation constants of some carbapenem group antibiotics and quantification of these compounds in human urine

The dissociation constant values (_s^spK_a) of some carbapenem group drugs (ertapenem, meropenem, doripenem) in different percentages of methanol–water binary mixtures (18, 20 and 22%, v/v) were determined from the mobile phase pH dependence of their retention factor. Evaluation of these data was performed using the NLREG program. From calculated pK_a values, the aqueous pK_a values of these subtances were calculated by different approaches. Moreover, the correlation established between retention factor and the pH of the water–methanol mobile phase was used to determine the optimum separation conditions. In order to validate the optimized conditions, these drugs were studied in human urine. The chromatographic separation was realized using a Gemini NX C₁₈ column (250 × 4.6 mm i.d., 5 µm particles) and UV detector set at 220 and 295 nm. Copyright © 2013 John Wiley & Sons, Ltd.     

Electrooxidation of pimozide and its differential pulse voltammetric and HPLC-EC determination

The oxidative behaviour of pimozide was studied in hydroalcoholic media (10+90 methanol-H₂O, pH range 2-7.5) at carbon based electrodes. Pimozide was irreversibly oxidized at high positive potentials, resulting in the formation of a couple with a reduction and re-oxidation peak at much lower potentials. The response was evaluated with respect to pH, scan rate, addition of surfactant and other variables. Using differential pulse voltammetry (DPV), the drug yielded a well-defined voltammetric response in Britton-Robinson buffer, pH 2.1 at +1.1 V (versus Ag/AgCl) on glassy carbon electrode. The process could be used to determine pimozide concentrations in the range 8×10⁻⁷-1×10⁻⁴ M. Applicability to tablets and human serum analysis was illustrated. Furthermore, a high-performance liquid chromatographic method with electrochemical detection (HPLC-EC) was developed, which allowed pimozide to be detected down to a level of 2.7×10⁻¹⁰ M (0.25 ppb).