Automized procedures for the determination of ozone and ammonia contents in air by using the chromatomembrane method for gas-liquid extraction

Chromatomembrane cells (CMC) operate as unique manifolds for extraction and preconcentration procedures in computer controlled flow-injection-analysis (FIA). By coupling to an ion chromatograph and to a conductometer, respectively, instrumentation is obtained that allows the pretreatment and the detection of ozone- and ammonia-containing samples after absorption of the gaseous constituents of air inside a chromatomembrane cell. The analysis of air even in the presence of liquid aerosols is discussed.     

A New Type of Charge-Density-Wave Pinning in Orthorhombic TaS3 Crystals with Quenching Defects

Diminishing in the concentration of quenching defects during thermocycling of orthorhombic TaS₃ samples in the temperature range below the Peierls transition temperature T < T_P is observed. It makes it possible to study the character of pinning of the charge density wave by these defects. A number of fundamental differences from pinning by ordinary local pinning centers—impurities and point defects—have been found. We conclude that quenching defects are extended (non-local) objects (presumably, dislocations) that can diffuse from the crystal during low-temperature thermocycling due to their strong interaction with the charge density wave, which is intrinsic for Peierls conductors. The presence of these defects leads to a previously unknown non-local type of the charge-density-wave pinning that acts on T_P and the threshold field for the onset of charge-density-wave sliding, E_T, differently in comparison with the local pinning centers.

     

New chiral 1,4,2-oxazaphosphorinanes bearing a free hydroxy group

Russian Chemical Bulletin - New chiral 3-aryl-2-hydroxy-2-oxo-5-R-1,4,2-oxazaphosphorinanes were obtained by a three-step one-pot synthesis, which included the preparation of imines from...     

4-Methylamino antipyrine determination in human plasma by high-performance liquid chromatography tandem mass spectrometry

In the present study, a simple and rapid method for metamizole metabolite 4-methylamino antipyrine (MAA) determination in human plasma was developed, validated and successfully applied to a clinical trial. Chromatographic separation was achieved in HILIC mode on a YMC-Pack SIL column (100 × 2.0 mm; S-5 μm, 30 nm), with a mobile phase consisting of acetonitrile, water and formic acid. Protein precipitation of a small plasma volume using acetonitrile was selected for sample preparation. The multiple reaction monitoring transitions in the positive ionization mode were m/z 218.2 → 56.2 for MAA and m/z 221.2 → 56.2 for MAA-d3 (IS, internal standard). Concentration levels of MAA calibration standards were in the range of 0.100–20 μg/ml. Metamizole conversion into MAA in both water and organic media was investigated, and the level of the conversion in commercially available injection solutions was estimated.     

Stable and reproducible supramolecular motif in the crystal structure of sulfonamides of the benzothiazine series fused to an epoxybornane moiety

Russian Chemical Bulletin - The crystal structures of four sulfonamides of the benzothiazine series, fused to an epoxidized norbornane moiety and containing various substituents in the para...     

On Existence of Attractors in Dissipative Three-Dimensional Systems

International Applied Mechanics - The theorems on the birth of attractors from homoclinic loops are proved. Applications of the theorems are considered.     

Opening of the pyridine ring in the system 1,1,1-trifluoro-4-phenylbut-3-yn-2-one–water. Stereoselective synthesis of 5-{[(1Z)-4,4,4-trifluoro-3-oxo-1-phenylbut-1-en-1-yl]amino}penta-2,4-dienal

Russian Journal of Organic Chemistry -     

1-R-2-[(1E,3E)-4-Aminobuta-1,3-dien-1-yl]-1H-benzimidazoles. Synthesis and some transformations

7-Nitropyridobenzimidazolium salts are cleaved with secondary amines to form 2-[(E,E)-4-aminobuta-1,3-dienyl]-1H-benzimidazoles. The latter react with dimethyl acetylene-dicarboxylate to yield 4a-[(E,Z,E)-6-amino-4,5-dimethoxycarbonylhexa-1,3,5-trien-1-yl]-1,2,3,4-tetra(methoxycarbonyl)-4a,5-dihydropyrido[1,2-a]benzimidazoles.