Green and mild laccase-catalyzed aerobic oxidative coupling of benzenediol derivatives with various sodium benzenesulfinates

The oxidative coupling reaction between hydroquinone or catechols and various sodium benzenesulfinates was investigated using the laccase from Trametes versicolor, in the presence of O₂ in a phosphate buffer solution at room temperature to afford sulfonyl benzenediols in 75–95% yield.     

Potentiodynamic and cyclic voltammetric behaviour of a lead electrode in NaOH solution

Summary The electrochemical behaviour of lead in NaOH solution was studied by potentiodynamic and cyclic voltammetric techniques in combination with X-ray diffraction analysis. The active dissolution of lead involves a small shoulderA1 followed by a peakA1 prior to a passive region. The shoulderA1 is assigned to the electroformation of a Pb(OH)₂ film, whereas peakA1 is due to the formation of PbO. Beyond the passive region, the current density increases again, forming a small shoulderA2 and a peakA2 prior to the oxygen evolution potential. The shoulderA2 and the peakA2 are correlated to the electrooxidation of PbO to Pb₃O₄ and PbO₂, respectively. The intensity of the anodic peaks increases with increasing alkali concentration, temperature and scan rate. In cyclic voltammetry, the reverse scan shows two cathodic peaksC1 andC2 which are correlated to the electroreduction of PbO and PbO₂ respectively, to Pb.

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Potentiodynamisches und cyclovoltammetrisches Verhalten einer Bleielektrode in NaOH-Lösung

Zusammenfassung Das elektrochemische Verhalten von Blei in NaOH wurde mittels potentiodynamischer und cyclovoltammetrischer Techniken unter Zuhilfenahme der Röntgenbeugungsanalyse untersucht. Die aktive Auflösung von Blei verläuft über eine SchulterA1, die von einem einer passiven Region vorgelagerten PeakA1 gefolgt wird. Die SchulterA1 wird der elektrochemischen Bildung eines Pb(OH)₂-Films, der PeakA1 der Bildung von PbO zugeschrieben. Jenseits der passiven Region steigt die Stromdichte wieder an, und vor Erreichen des Sauerstoffpotentials treten eine kleine SchulterA2 und ein PeakA2 auf, die mit der Elektrooxidation von PbO zu Pb₃O₄ und PbO₂ korrelieren. Analog dazu beobachtet man in der cyclischen Voltammetrie zwei kathodische PeaksC1 undC2, die der Elektroreduktion von PbO und PbO₂ zu Pb entsprechen. Die Intensität der anodischen Peaks steigt mit steigender Alkalikonzentration, Temperatur und Scangeschwindigkeit.

     

Characterization of a Novel Tellurite Selective Electrode

Tellurium was determined by introducing a solid membrane for the selective determination of tellurite ion. An electrode composed of a compressed disk containing a mixture of HgTeO₃and Hg₂Cl₂was found to give a typical Nernstian response of 29 mV/concentration decade for the concentration range 10⁻⁵to 10⁻¹M). The connection was made by Hg metal instead of aqueous inner filling. The optimum pH was 3.5–10.5. The selectivity of the electrode toward several inorganic and organic anions was estimated. The electrode was applied to the determination of tellurium in binary mixtures with a mean recovery of 98.99% and relative standard deviation range of 0.19–0.51%.     

Determination of uranium and thorium concentrations in some West Malaysian limestones using neutron activation and delayed neutron analysis

Concentrations of uranium and thorium in some West Malaysian limestones have been determined using neutron activation and delayed neutron analyses. These limestones are mainly calcium carbonates and contain uranium and thorium in concentrations of about a few parts per million.     

Investigation on Impurity Profiling and Degradation Behavior of WCK 771

Chromatographia - WCK 771 is a novel antibacterial drug recently launched in India for the treatment of acute bacterial skin and skin structure infections (ABSSSI). This report describes...     

On the natural convection of nanofluids in diverse shapes of enclosures: an exhaustive review

Journal of Thermal Analysis and Calorimetry - The ultimate goal of the present review paper is to summarize and discuss the findings of the most recently published literature on natural convection...     

A New Approach for Synthesis of 2-Thioxocytosine-5-carbonitrile as Antimicrobial Agents

Russian Journal of General Chemistry - A highly efficient synthetic methodology for the preparation of 2-thioxocytosine was achieved by the nucleophilic addition of thiourea to...     

Simultaneous determination of novel β-lactamase inhibitor WCK 4234 and Meropenem in dog plasma by LC–MS/MS and its application to preclinical pharmacokinetic study

A precise and accurate liquid chromatography–tandem mass spectrometric (LC–MS/MS) bioanalytical method has been developed and validated for the simultaneous quantification of WCK 4234 and meropenem (MEM) in dog plasma. Protein precipitation using acetonitrile was employed as a sample preparation approach. Cefepime was used as an internal standard. The developed method was selective, sensitive (limit of quantification, 0.075 μg/ml for both drugs), accurate (recovery > 90%), precise (CV < 10%) and linear (r² ≥ 0.99, concentration range 0.075–120 μg/ml for both analytes). The developed method was successfully applied for the determination of both drugs in plasma to assess the pharmacokinetics in beagle dogs. WCK 4234 + MEM in a 1:1 ratio at 15 + 15 and 30 + 30 mg/kg doses were administered by the intravenous route. The mean plasma concentration and area under the concentration–time curve of WCK 4234 ranged from 38.3 to 77.4 μg/ml and from 47.8 to 77.1 μg h/ml, respectively, and the values for MEM ranged from 52.2 to 115.3 μg/ml and 70.5 to 133.6 μg h/ml respectively. The elimination half-life of WCK 4234 and MEM was around 0.8 h.