Head-to-head bisbenzazole derivatives as antiproliferative agents: design,synthesis, in vitro activity,and SAR analysis

Molecular Diversity - In the present work, a series of bisbenzazole derivatives were designed and synthesized as antiproliferative agents. The antiproliferative activity of these compounds was...     

Molecularly Imprinted Polypyrrole for DNA Determination

In this study graphite electrodes modified by a thin DNA‐imprinted polypyrrole layer, which was able to bind specific target‐DNA, are reported. For this aim, electrochemical synthesis of polypyrrole was performed on a pencil graphite electrode by cyclic voltammetry (CV) or by potential pulse sequences (PPS). The modified electrode surface was used for electrochemical determination of target‐DNA by differential pulse voltammetry. According to our best knowledge this is a first report on the application of DNA‐imprinted polymer for the determination of target‐DNA. The results showed that the molecularly imprinted polypyrrole (MIPPy) layer that formed on the carbon electrode surface was sensitive for target‐DNA, while the nonimprinted polypyrrole layer was not sensitive to the same target‐DNA. Comparison of electrodes modified using PPS and CV techniques is presented.     

Separation and direct UV detection of lanthanides complexed with pyridine-2-carboxylic acid by capillary electrophoresis

Separation and detection of lanthanides by capillary zone electrophoresis in the presence of pyridine-2-carboxylic acid (picolinic acid) as UV-absorbing complexing agent were investigated. The resolution of partially complexed positively charged complexes is improved by using two buffer ligands competing with picolinic acid for metal ions. When hydroxyisobutyric acid (HIBA) and formic acid are used together as competing ligands, this provides complete separation of all 14 lanthanides with good peak shapes. An on-column separation of 14 lanthanides was achieved in only 9 min using 0.8 mmol/l picolinic acid, 10 mmol/l HIBA and 25 mmol/l formic acid at pH 4.7. Determination of lanthanide complexes was performed by direct detection at 210 nm. Detection limits (signal-to-noise ratio=3) are ca. 0.53-0.96 microg/ml.     

Surface modification and characterization of phenanthroline nanofilms on carbon substrate

Modification of glassy carbon (GC) surfaces with phenanthroline derivatives (PDs) such as 5‐amino‐1,10‐phenanthroline (5AP) and 5,6‐diamino‐1,10‐phenanthroline (56DAP) is described in this study. Surface modification experiments were performed by cyclic voltammetry (CV) scanning from + 1.2 to + 2.7 V at scan rate of 100 mV/s applying 30 potential scans in acetonitrile (CH₃CN) containing 1 mM PDs and 100 mM tetrabutylammoniumtetrafluoroborate (TBATFB). The presence of PDs on GC electrode was confirmed using CV, electrochemical impedance spectroscopy (EIS), contact angle measurements and ellipsometry and comparing with the results of bare GC electrode. A mechanism was proposed for the electrochemical modification of the GC electrode surface with PDs. The structure of the 5AP and 56DAP films was also discussed in the light of electrochemical and spectroscopic data. The complex‐forming ability of the modified surfaces against metal cations was investigated by square‐wave voltammetry (SWV). It was shown that surfaces having 1,10‐phenanthroline ligands with different functional groups were quite useful for the determination of transition metal ions. Copyright © 2010 John Wiley & Sons, Ltd.     

Towards an understanding of the marine fouling effects on VIV of circular cylinders: a probe into the chaotic features

Nonlinear Dynamics - The current paper addresses the possibility of chaotic dynamics in the VIV response of cylinders covered by marine biofouling. The fouling was simulated by machining uniformly...     

Direct determination of bromide ions in seawater by capillary zone electrophoresis using polyethyleneimine-coated capillaries

A rapid and simple capillary electrophoretic method was developed for the direct determination of bromide ion in seawater. We have found an effective method, based on the use of polyethyleneimine-coated capillaries and the addition of sodium chloride to the background electrolyte. The use of coated capillaries with a cationic polymer changes the direction of the electroosmotic flow in the capillary, which favors the migration speed of the bromide ion and enables the use of low salt concentrations in the separation electrolyte. Bromide ion in seawater can be determined within 2 min using this system and 20 mmol L^-1 NaCl-containing separation electrolyte. The detection limit for the bromide ion was 0.45 g ml^-1. The method was applied to the determination of bromide ion in seawater samples collected from the Bosphorus and the Black Sea. Bromide contents in samples from 0 to 72 m depths varied between 33.2 and 72.8 mg L^-1 with a mean 3.0% RSD.     

Separation and direct UV detection of lanthanides complexed with cupferron by capillary electrophoresis

Separation and detection of lanthanides by capillary zone electrophoresis in the presence of cupferron (N-nitroso-N-phenylhydroxylamine) as UV absorbing complexing agent were investigated. The resolution of partially complexed positively charged cupferron complexes is improved by using a buffer ligand competing with cupferron for metal ions. When hydroxyisobutyric acid (HIBA) is used as buffer and competing ligand, it provides complete separation of all 14 lanthanides with good peak shapes. An on-column separation of 14 lanthanides was achieved in only 7 min using 0.1 mmol/l cupferron, 15 mmol/1 HIBA at pH 4.9. The separation efficiencies for the optimum separation condition are between 77,000 and 208,000 theoretical plates. Determination of lanthanide complexes was performed by direct UV detection at 210 nm. Detection limits (signal-to-noise ratio=3) are ca. 0.24-0.47 microg/ml for lanthanides. Under optimum conditions, the complete separation of thorium and uranium from mixed lanthanides was achieved.     

Effect of cationic surfactant adsorption on the rheological and surface properties of bentonite dispersions

In this study, the adsorption, bridging, and intercalation effects of a cationic surfactant, benzyldimethyltetradecyl ammonium chloride (BDTDACl), on bentonite clay suspensions was investigated. The adsorption, rheological behaviors, and colloidal properties of the clay dispersions were determined as a function surfactant concentration. Adsorption isotherms were obtained using the batch-equilibrium technique. The rheological behavior of the clay suspensions was obtained by shear stress-shear rate measurements within 0-350 s-1 shear rates. The structure of the composite particles was analyzed by using X-ray diffraction analysis and it was found that the expansions of basal d-spacings are less than 16.80 A, suggesting a monolayer structure.     

A molecular dynamics study on iridium

In this study, molecular dynamics simulations are performed by using a modified form of Morse potential function in the framework of the Embedded Atom Method (EAM). Temperature-and pressure-dependent behaviours of bulk modulus, second-order elastic constants (SOEC), and the linear-thermal expansion coefficient is calculated and compared with the available experimental data. The melting temperature is estimated from 3 different plots. The obtained results are in agreement with the available experimental findings for iridium.