Trifluoromethylation of aliphatic halides with trifluoromethyl copper

A solution of trifluoromethyl copper complex in hexamethylphosphoric triamide was found to be useful for trifluoromethylation of aliphatic halides.     

High-throughput and simultaneous analysis of eight central-acting muscle relaxants in human plasma by ultra-performance liquid chromatography–tandem mass spectrometry in the positive and negative ionization modes

In this report, a high-throughput and sensitive method for analysis of eight central-acting muscle relaxants in human plasma by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) in the positive and negative ionization modes using tolbutamide as internal standard is presented. After pretreatment of a plasma sample by solid-phase extraction with an Oasis HLB cartridge, muscle relaxants were analyzed by UPLC with Acquity UPLC BEH C₁₈ column and Acquity TQD tandem quadrupole mass spectrometer equipped with an electrospray ionization interface. The calibration curves for muscle relaxants spiked into human plasma equally showed good linearities in the nanogram per milliliter order range. The detection limits (signal-to-noise ratio = 3) was as low as 0.1–2 ng/mL. The method gave satisfactory recovery rates, accuracy, and precision for quality control samples spiked with muscle relaxants. To further validate the present method, 250 mg of chlorphenesin carbamate was orally administered to a healthy male volunteer, and the concentrations of chlorphenesin carbamate in plasma were measured 0.5, 1, 2, 4, 6, and 8 h after dosing; their concentrations in human plasma were between 0.62 and 2.44 μg/mL. To our knowledge, this is the first report describing simultaneous analysis of over more than two central-acting muscle relaxants by liquid chromatography–tandem mass spectrometry. This has been realized by the capability of our instrument for simultaneous multiple reaction monitoring of the target compounds in both positive and negative ionization modes. Therefore, the present method seems very useful in forensic and clinical toxicology and pharmacokinetic studies.     

Über die charakteristischen Untergruppen einer endlichen Abelschen Gruppe

Ohne Zusammenfassung     

Hydrostatic compression of the monoclinic form of polyethylene

Lattice constants of the monoclinic form of polyethylene under pressures up to 1.8 GPa at 298 K are investigated by x-ray diffraction. The thermal expansion from 100 K to 300 K at atmospheric pressure is also studied. The equation of state is calculated by Pastine's method, taking into account the zero-point vibration, and is compared with experimental results. The calculated results depend largely on the interatomic potential used and the limit of the interatomic distance for summation of the potentials. A change in the angle γ between the a and b axes results in an anisotropic change in the unit cell dimension with both pressure and temperature; the a and b axes change at nearly the same rate. The monoclinic form may have a higher density than the orthorhombic form at pressures above 1.0 GPa.     

Simultaneous kinetic determination of secondary amines and their isomers by a spectrophotometric stopped-flow method based on the formation of dialkyldithiocarbamates

Secondary amines react with carbon disulphide to form stable dialkyldithiocarbamates at high pH in aqueous Triton X-100 solution. The formation rates of dimethyl-, diethyl-, di-n-propyl-, diisopropyl-, di-n-butyl- and diisobutyldithiocarbamates and pyrrolidinedithiocarbamate were measured by a stopped-flow spectrophotometric method. The reaction rates were a function of the pH of the solution and depended on the size and structure of the amines. The rate of isoalkylamines was far slower than that of the n-alkyl analogues. Individual concentrations of amines were determined in a mixture of di-n- and diisopropylamine and in a mixture of diiso- and di-n-butylamine.     

Waveform stability of a traveling high-field domain in a Gunn diode

We assume that a constant voltage is applied across a sample of a Gunn diode of finite length. When a periodic boundary condition is assumed, the dynamical behavior of the electric field within the sample is described by a nonlinear integral-partial differential equation. By using this equation, we can study the waveform stability of a traveling high-field domain of solitary-wave type which plays an essential role in the Gunn effect. We obtain simple criteria which the sample length and the applied voltage must satisfy for the existence and stability of the high-field domain. The stability analysis is carried out by using Liapunov's second method.     

Conductive polymer-carbon-imidazolium composite: a simple means for constructing solid-state dye-sensitized solar cells

A clay-like conductive material comprising polyaniline-loaded carbon black particles and an ethyleneoxide-substituted imidazolium iodide was prepared. The material was sandwiched between dye-coated porous TiO2 and counter-electrode to form a solid-state dye-sensitized solar cell, which works with overall conversion efficiencies of 3.48% and 4.07% for AM 1.5, 100 mW cm(-2) and 23 mW cm(-2) irradiation, respectively.