Urea-thiazole/benzothiazole hybrids with a triazole linker: synthesis,antimicrobial potential,pharmacokinetic profile and in silico mechanistic studies

Molecular Diversity - Some urea-thiazole/benzothiazole hybrids with a triazole linker were synthesized via Cu(I)-catalysed click reaction. After successfully analysed by various spectral techniques...     

Copper(II) complexes with N-(2-hydroxyethyl)-2-iminodiacetic acid and imidazoles: crystal structure,spectroscopic studies and superoxide dismutase activity

Abstract  

Two new copper(II) complexes, [Cu(Hhida)(BenzImH)]·H₂O (1) and [Cu(Hhida)(EtImH)]·2H₂O (2) have been synthesized by the interaction of basic copper carbonate with N-(2-hydroxyethyl)-2-aminodiacetic acid (Hhida²⁻) and benzimidazole (BenzImH) or (2-ethylimidazole (EtImH)). The structures of both complexes were studied by single crystal X-ray diffraction. The geometry around the copper(II) atom can be best described as distorted square pyramidal as indicated by the value of the trigonal index τ = 0.32 for (1) and 0.21 for (2). Spectroscopic and electrochemical studies were performed in order to correlate structural features of the complexes with their superoxide scavenger activity. The ability of the complexes to scavenge superoxide anions was also evaluated.     

First evidence of hexameric and heptameric ellagitannins in plants detected by liquid chromatography/electrospray ionisation mass spectrometry

Ellagitannins are bioactive plant polyphenols of which more than 500 individual compounds have been identified from plants. An ellagitannin-rich fraction was isolated by Sephadex LH-20 from Oenothera biennis (common evening primrose) leaves and roots and analysed by high-performance liquid chromatography/diode-array detection coupled to high-resolution mass spectrometry with an electrospray ionisation interface. The high-molecular mass ellagitannins were characterised by their UV spectra, molecular masses and mass spectral fragments. In addition to the previously reported dimers and trimers, an entire series of oligomeric ellagitannins from dimers to heptamers was characterised in both roots and leaves of O. biennis. This is the first report of natural ellagitannins larger than pentamers.     

On sufficiency and duality in multiobjective programming problem under generalized <Emphasis Type="Italic">α</Emphasis>-type I univexity

In this paper, we are concerned with the multiobjective programming problem with inequality constraints. We introduce new classes of generalized α-univex type I vector valued functions. A number of Kuhn–Tucker type sufficient optimality conditions are obtained for a feasible solution to be an efficient solution. The Mond–Weir type duality results are also presented.     

CFD analysis of an oscillating wing at various reduced frequencies

The effect of various reduced frequencies has been examined for an oscillating aspect ratio 10 NACA 0015 wing. An unsteady, compressible three‐dimensional (3D) Navier–Stokes code based on Beam and Warming algorithm with the Baldwin–Lomax turbulence model has been used. The code is validated for the study against published experimental data. The 3D unsteady flow field is simulated for reduced frequency values of 0.1, 0.2 and 0.3 for a fixed mean angle of attack position and fixed amplitude. The type of motion is sinusoidal harmonic. The force coefficients, pressure distributions and flow visualization show that at the given conditions the flow remains attached to the wing surface even at high angles of attack with no clear separation or typical light‐to‐deep category of dynamic stall. Increased magnitude of hysteresis and higher gradients are seen at higher reduced frequencies. The 3D effects are even found at midspan locations. In addition, the rate of decrease in lift near the wing tips compared with the wing root is not much like in the static cases. Copyright © 2008 John Wiley & Sons, Ltd.     

Poly(alkylmethylsiloxanes) thermally immobilized on silica as stationary phases for high-performance liquid chromatography

Modifications have been made to the method of ion-exclusion pre-separation followed by ion exchange with conductivity detection for the determination of trace levels of chloride, sulfate and nitrate in concentrated phosphoric acid. Ion-exclusion separation and pre-concentration of impurity anions is performed using Dionex AS6-ICE and AS11-HC (4 mm) columns, respectively, with water eluent. Final separation is performed using Dionex AG11-HC and AS11-HC (2 mm) columns, KOH gradient elution, and suppressed conductivity detection. Improvements to the method include addition of an autosampler and eluent generator, and use of external standard calibration. These instrumental and procedural changes significantly improve the method's throughput, while the method's capability relative to phosphoric acid specifications is maintained, as verified through statistical evaluation of control sample analyses. Detection limits of 60, 680, and 4,0 ppb (w/w) are obtained vs. semiconductor-grade phosphoric acid specifications of 1000, 12,000, and 5000 ppb for chloride, sulfate, and nitrate, respectively.     

Difference Equations Approach for Multi-Server Queueing Models with Removable Servers

Methodology and Computing in Applied Probability - We consider an extended form of the MX/M/c queue with two types of server groups: Static as well as dynamic (which turn on/off in a...     

Terminal and Internal Alkyne Complexes and Azide-Alkyne Cycloaddition Chemistry of Copper(I) Supported by a Fluorinated Bis(pyrazolyl)borate

Copper plays an important role in alkyne coordination chemistry and transformations. This report describes the isolation and full characterization of a thermally stable, copper(I) acetylene complex using a highly fluorinated bis(pyrazolyl)borate ligand support. Details of the related copper(I) complex of HC≡CSiMe₃ are also reported. They are three-coordinate copper complexes featuring η²-bound alkynes. Raman data show significant red-shifts in C≡C stretch of [H₂B(3,5-(CF₃)₂Pz)₂]Cu(HC≡CH) and [H₂B(3,5-(CF₃)₂Pz)₂]Cu(HC≡CSiMe₃) relative to those of the corresponding alkynes. Computational analysis using DFT indicates that the Cu(I) alkyne interaction in these molecules is primarily of the electrostatic character. The π-backbonding is the larger component of the orbital contribution to the interaction. The dinuclear complexes such as Cu₂(μ-[3,5-(CF₃)₂Pz])₂(HC≡CH)₂ display similar Cu-alkyne bonding features. The mononuclear [H₂B(3,5-(CF₃)₂Pz)₂]Cu(NCMe) complex catalyzes [3 + 2] cycloadditions between tolyl azide and a variety of alkynes including acetylene. It is comparatively less effective than the related trinuclear copper catalyst {μ-[3,5-(CF₃)₂Pz]Cu}₃ involving bridging pyrazolates.