Applications of small iridium-based mercury electrodes to high concentrations of depolarizers

Voltammetric and microscopic data on the analytical properties of small iridium-based (127- μm diameter) mercury film electrodes are presented. A method of estimating and controlling the size of the deposit is described. The voltammetric behaviour of electrodes with mercury deposits varying from a film to a near-hemisphere is discussed for linear-scan, differential- and normal- pulse voltammetry. The systems Pb²⁺/Pb, Fe³⁺/Fe²⁺ and Co²⁺/Co, are used to show that, by changing the size of the deposit, either time-dependent or almost time-independent (steady-state) voltammograms can be obtained under the same instrumental conditions. Possible applications to the determination of high concentrations of depolarizers are outlined; voltammetric data for the determination of lead in the range 10–120 mM are presented. The evaluation of diffusion coefficients is discussed.     

Synthesis,Characterization, and Application of Platinum(II) Complexes Incorporating Racemic and Optically Active 4‐Chloro‐5‐Methyl‐1‐Phenyl‐1,2,3,6‐Tetrahydrophosphinine Ligand

An efficient resolution method was elaborated for the preparation of (+)‐4‐chloro‐5‐methyl‐1‐phenyl‐1,2,3,6‐tetrahydrophosphinine oxide using the acidic Ca²⁺ salt of (–)‐O,O‐di‐p‐toluoyl‐(2R,3R)‐tartaric acid. Crystal structure of the diastereomeric complex was evaluated by single crystal X‐ray analysis. Beside this, the absolute P‐configuration was also determined by a circular dichroism (CD) spectroscopic study including theoretical calculations. The tetrahydrophosphinine oxide was then converted to the corresponding platinum complex whose stereostructure was investigated by high‐level quantum chemical calculations. The Pt complex was tested as a catalyst in the hydroformylation of styrene.     

Determination of <Superscript>93</Superscript>Zr in nuclear power plant wastes

A radioanalytical method (based on separation using UTEVA columns and ICP-MS measurement) has been used for determination of ⁹³Zr in 37 nuclear power plant samples. As ⁹³Nb might affect the detection of ⁹³Zr, Monte Carlo activation model was used to calculate the expected ⁹³Zr/^natZr mass ratio, which was compared to measured ones. It was found, that a decontamination factor of 10³ is sufficient to get a measurement uncertainty of less than 10%.     

Application of carbon nanotubes as solid-phase extraction sorbent for analysis of chlorophenols in water samples

The aim of this work was to investigate the efficiency of various MWCNTs as SPE materials for the preconcentration of chlorophenols. The COOH-functionalized MWCNTs and MWCNTs were used as SPE sorbents. To evaluate the capability of MWCNTs for the preconcentration of chlorophenols from water samples, 2,4-chlorophenol, 4-chlorophenol, 2,4,6-chlorophenol, 2,6-chlorophenol, 3,4-chlorophenol, and 2-chlorophenol were used as model compounds. Chlorophenols were extracted with acetone, methanol, ethanol, and dichloromethane, and determined by gas chromatography–mass spectrometry. COOH-functionalized MWCNTs <8 nm were found to be the best sorbent for the tested chlorophenols. For COOH-functionalized MWCNTs <8 nm, the recovery rates for all chlorophenols were higher than 50% when acetone or ethanol was used as eluents. In the case of dichloromethane elution, recovery rates for chlorophenols were from 62.0% for 2,6-DCP to 116.8% for 2,4-DCP; only for 2,4,6-TCP was the recovery rate 30.6%. Similar percentage recoveries were achieved with methanol as the eluent.     

Communication: Experimental proof of symmetry breaking in tilted smectics composed of molecules with axial chirality

For the first time, domains with twisted structures have been established in planar samples of achiral compounds in tilted smectic C phase. This evidences separation of molecular conformers differing in the sense of axial chirality and confirms polar C(2) symmetry of these domains. A simple model considering polar surface anchoring energy and bulk energy of the twist can account for this finding. Conditions for coexistence of twisted and homogeneous domains are discussed.     

Reductive carboxylation of alkyl halides with CO2 by use of photoinduced SmI2/Sm reduction system

Upon visible-light irradiation, reductive carboxylation of alkyl halides takes place by using a SmI₂/Sm mixed system under atmospheric CO₂ to afford the corresponding carboxylic acids in good to excellent yields.     

DSC examination of intestinal tissue following cold preservation

The fact that small bowel is extremely sensitive to cold preservation had encouraged us to compare the conventional histology and differential scanning calorimetry (DSC) methods in intestinal structural changes following experimental cold storage models. Our histological findings showed that longer cold preservation period caused more severe damage in structure of mucosa and crypts, but there were no changes in the muscular layer. According to our DSC data (transition temperature, calorimetric enthalpy) suggest that the thermal destruction of mucosa, muscular layer and total intestinal wall following preservation injury revealed significant differences compared to normal bowel structure.