Pluripolarity of sets with small Hausdorff measure

We show that any set E⊂C ⁿ , n≥ 2, with finite Hausdorff measure? is pluripolar. The result is sharp with respect to the measuring function. The new idea in the proof is to combine a construction from potential theory, related to the real variational integral , , with properties of the pluricomplex relative extremal function for the Bedford–Taylor capacity. Received: 20 May 1999     

Analysis of Slightly Volatile Samples by Atomic-Ionization Spectrometry with Laser Ablation into Flame

The potentialities of laser-enhanced atomic-ionization spectrometry with laser ablation for the analysis of slightly volatile and difficultly ionized samples were studied using lithium polyvanadate as an example. The effect of the cathode voltage and the power of the ablation beam on the signal in the analysis of such samples was studied. The optimum measurement range was determined as a function of the number of subsequent ablation pulses acting upon the same surface point. This minimized the effect of the surface contaminants and the change in ablation conditions as the crater deepened.     

Superposition operator in Sobolev spaces on domains

For an arbitrary open set we characterize all functions on the real line such that for all . New element in the proof is based on Maz'ya's capacitary criterion for the imbedding .     

Optimizing the Conditions of the Experiment in Atomic Ionization Spectrometry with Laser-Induced Evaporation of Material into a Flame

Two ionization signals — selective and nonselective — are recorded on laser-induced evaporation of solid samples into a flame with subsequent exposure to resonance radiation. The magnitudes of the signals depend on many experimental parameters: the composition of the sample, the composition of the environment and gas mixture, etc. The dependences of the nonselective and selective signals on such experimental parameters as the voltage on the cathode and the energy of the vaporizing radiation have been studied. The optimum energy of the vaporizing radiation was 44–48 mJ at the cathode voltage 500–800 V. This has allowed the coefficient of correlation of the calibration graph to be raised up to 0.99. In these conditions, the limit of detection of Li was 0.017%.     

Application of Laser-Induced Breakdown Spectrometry for analysis of environmental and industrial materials

Actual state of affairs, main advantages and problems of Laser-Induced Breakdown Spectroscopy (LIBS) in analysis of industrial materials and environmental samples are discussed. Methods for LIBS sensitivity enhancement such as double-pulse ablation, a combination of LIBS with laser-induced fluorescence, the use of additional sources of excitation (spark) and confinement of plasma by magnetic field or shock wave are compared with respect to figures-of-merit. A set of LIBS approach to qualitative fast classification of materials, especially based on the correlation between parameters of laser plasma and sample properties, are discussed in details. Progress in environmental analysis of soils, sands etc. with the use of LIBS is demonstrated. Detection limits of the most elements in soils and aluminum alloys obtained until now are critically considered.     

Selection of an analytical line for determining lithium in aluminum alloys by laser induced breakdown spectrometry

Possibilities for determining lithium in aluminum alloys by laser spark spectrometry are studied. The optimum conditions for registering the emission signal of lithium at which the effect of the continuous background radiation of the laser plasma attains a minimum are found. The possibility of determining lithium by laser spark spectrometry using the spectral line at 610 nm is studied for the first time. A comparison of the detection limits and sensitivities of determining lithium by emission its lines at 610 and 671 nm has indicated the advisability of using the line 610 nm for the studied alloys. The detection limit calculated using the 3σ test was found to be 230 ppm (610 nm) and 870 ppm (671 nm).     

Gel Filtration of Model Albumin-Analgin Mixture through Sephadex To Isolate Albumin

The preparative isolation of albumin from a model albumin-analgin mixture by filtration through Sephadex G-25 was studied. The conditions providing optimal protein decontamination to remove low-molecular-weight impurities were established, and recommendations on both laboratory and industrial application of this technique were made. Based on laboratory experiments, a commercial installation for production of refined vaccines was designed.     

Application of chromatography–mass spectrometry methods to the control of sport nutrition and medicines marketed via internet

Several sport nutrition products and doping drugs sold in the period from 2014 to 2016 were studied using gas and liquid chromatography coupled with mass-spectrometry. In the study, WADA-banned substances were detected in the composition of pre-workout supplements, fat burners, and prohormones. A series of selective androgen receptor modulators and peptide doping drugs were also studied. It was shown that, in some cases, preparations can be adulterated.