On a representation of fully nonlinear elliptic operators in terms of pure second order derivatives and its applications

We give a method of representing fully nonlinear elliptic operators given by boundedly inhomogeneous functions in terms of operators acting only on pure second order derivatives. We also discuss possible applications of such representations to using .finite di.erence approximations for solving the corresponding equations.     

Potential of fluorescence polarization immunoassay for the detection of Aspergillus fumigatus galactomannan

Russian Chemical Bulletin - Galactomannan (GM) is a specific polysaccharide antigen of opportunistic mold fungi of the genus Aspergillus. The detection of GM in patients’ biological fluids is...     

Modeling of the Earth’s rotary—oscillatory motions in the three-body problem: Interpolation and prognosis

A mathematical model of oscillations of the Earth??s pole and uneven Earth??s rotation due to gravitational tidal forces produced by the Moon and the Sun is constructed using the dynamic Euler??Liouville equations. It is established that high-frequency lunar influences contribute appreciably when modeling the prognosis of the Earth??s pole oscillations. The developed theoretical models for Earth??s rotation parameters account for small-scale high-frequency influences of gravitational nature (short-periodic disturbances due to the Moon with combination frequencies) and geophysical nature. Statistically convincing theoretical interpolations and prognoses on long-term (from one year to several years) and short (15?C25 days) time intervals compared to highly accurate observational and measuring data of the International Earth Rotation and Reference Systems Service (IERS) are provided.     

Quantitative determination of n-alkanethiols in air and in a blended gas mixture of methane with air by gas chromatography/differential mobility spectrometry

Mixtures of n-alkanethiols, in solution with equi-molar amounts from 0.5 to 360 ng per compound, were determined using gas chromatography (GC) with a differential mobility spectrometer, operated with a flow of air at ambient pressure, as the GC detector. A homologous series of n-alkanethiols with carbon number from two to six showed baseline resolution in the GC separation and positive and negative ion chromatograms were produced simultaneously for the alkanethiols. Differential mobility spectra showed compensation voltages characteristic of each alkanethiol and plots of ion intensity, retention time, and compensation voltage yield contour plots illustrating the second dimension of analytical selectivity provided by the detector. Another yet undeveloped dimension of analytical information was found in the dependence of mobility coefficients on electric field. Mass-analysis of ions from thiols showed a hydrogen abstracted ion, protonated monomers, and proton bound dimers. Linear ranges were narrow and the minimum detectable limits were ~1 ng. Response in positive polarity provided a ten-fold improvement in detection limits though spectra were more complex than for negative ions. In a methane-rich air atmosphere, intended to simulate ambient air or the detection of leaks from natural gas pipelines, the response to thiols with negative ions was not degraded by the methane up to 50% v/v, the highest level tested.     

Molecular structural nonuniformity of ultradispersed diamond-containing material and the reasons why it arises

An analysis of IR spectra, Raman spectra, and X-ray diffraction intensity curves for diamond-containing materials obtained by the detonation method under different conditions and purified by different methods was used to examine the structural nonuniformity of diamond-containing particles and the reasons why it arises.     

Luminescence spectra of Ho3+ in distorted parity-breaking HoF63− octahedra

Low temperature luminescence spectrum of holmium ions in monoclinic Rb₂KHoF₆ crystal was found to be well analyzable by the comparison with earlier studied cubic Cs₂NaHoF₆. The manifestation of the local symmetry influence on the strength of individual lines is found to be distinctive. In the absence of structural data, the local symmetry of holmium in Rb₂KHoF₆ is proved to be a non-centrosymmetric one. The concentration quenching of holmium luminescence in Rb₂KHoF₆ is found to be rather modest.     

Ion-exchange sorption of silver(I) chloride complexes from aqueous HCl solutions

The ion-exchange sorption of silver(I) chloride complexes from 1–4 M aqueous solutions of HCl on a series of Purolite anionites with various functional groups was studied. The ion-exchange equilibria in the systems were found to be anomalous according to Raman spectroscopy, which does not significantly affect the sorption properties of the ionites.     

Large plastic strains in the problem of high-speed loading of an aluminum ribbon

A method for numerical simulation of the motion of the plane liner in a magnetic compressor based on a combination of the transverse and longitudinal two-dimensional models is proposed. The method permits modeling the interaction of the liner ribbon with the rigid basement for the liner kinematic characteristics close to the experimental ones. Three different model are considered to justify the choice of the mathematical model of an elastoplastic body which would be suitable for solving similar problems. A series of computations is performed, and the results and scope of each of the models are analyzed.