Synthesis of trifluoromethyl-substituted heteroaromatic aldehydes

Trifluoromethylation of furfural and thiophene-2-carbaldehyde trifluoroacetates with XeF₂ and CF₃COOH afforded 5-trifluoromethylfuran-2-carbaldehyde and 5-trifluoromethylthiophene-2-carbaldehyde. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1623–1625, July, 2005.     

Magnetic configurations in the region of a nanocontact between ferromagnetic bars

A numerical solution to the Landau-Lifshitz and magnetostatics equations is used to study the residual magnetic configurations as functions of magnetic and geometrical parameters in the region of a magnetic nanocontact between oppositely magnetized ferromagnetic electrodes in the form of bulk bars. The conditions for the emergence of antiparallel orientations of adjacent spins and the domain wall in the conducting channel are determined.     

Calibration parameters for the probing tip of a magnetic force microscope in the field of a test current loop

The subject of discussion is calibration of the tip of a magnetic force microscope using the field of a ring-shaped current loop. To calculate the calibration parameters, the magnetic contribution from the extended tip of the probe in the field of the current loop to the rigidity of the cantilever is approximated by the contribution from a point magnetic dipole and magnetic “charge” in terms of the theoretical model adopted. Three simplified models of the conic tip (with a sharpened, blunted, and rounded top) are considered. The calculated dependences of the effective calibration parameters on the radius of the current loop are compared with experimental data. It is found that the model of a uniformly magnetized tip in the form of a blunted cone provides the best fit to the experiment. The calculation results may be helpful in simulating images obtained with a magnetic force microscope and numerically testing magnetic objects.     

Influence of a magnetic field on the Jahn-Teller band effect in a conducting ferromagnet

A simplified model of the Jahn-Teller band effect in a conducting ferromagnet with two degenerate subbands with the peak density of states of itinerant electrons is considered. It is found that the martensite transition temperature in a narrow-band conductor as a function of the position of the Fermi level near the peak of the energy density of states varies nonmonotonically in the narrow spin electron subband. The magnetic field dependence of the martensite-austenite structural phase transition temperature in the ferromagnet is analyzed. The developed theory and calculated data for the electron density of states in Ni₂MnGa are used as the basis for estimating the variation of the martensite transition temperature with the magnetic field (?T _m /?H), which demonstrates a satisfactory agreement with experimental data for the Heusler alloy Ni_2+x Mn_1?x Fe_yGa_1?y .     

Empirical calculation of fatty acid and glycerol composition in evaluating drug quality

Based on empirical indices of the composition and quality of drugs prepared from oil-bearing plant material, an algorithm for calculation of the fatty acid and glycerol composition is developed that can be used for screening evaluation of potential counterfeits and identification of poor-quality products.     

Synthesis of azolylethyl benzhydryl ethers,analogs of diphenhydramine

Alternative approaches to the preparation of azolylethyl benzhydryl ethers have been studied. It was shown that the reaction of diphenylmethyl halide with 2-(azol-1-yl)ethanol in the presence of triethylamine is the optimum way. An efficient method for the synthesis of 2-(imidazol-1-yl)ethanol using phase-transfer catalysis has been developed.     

Application of 150GHz quasi-optical EPR and endor systems to examination of materials for polarized nuclear targets

Some possibilities of mm and submm magnetic resonance spectrometers using a two-mirror open resonator as the sensor is demonstrated. A comparative analysis of sensitivity has been performed for spectrometer, with cavity and open resonators. Absorption spectra of the HMBA Cr^V complex in propylene glycol and ethylene glycol were investigated at 4.2 K.     

Oxidation of secondary cycloalkanols by the lead tetraacetate-metal halide system

Conclusions Secondary cyclic alcohols with C₅-C₈ ring size are oxidized by the lead tetraacetate-metal chloride or bromide system in three directions: with ring cleavage and the formation of -haloalkanals and without ring cleavage with the formation of the corresponding ketones and also, for C₇-C₈, 1,4-epoxycycloalkanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2538–2542, November, 1988.