Search Results

You are looking at 1 - 10 of 18 items for

  • Author or Editor: D. S. Yu x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

We introduce a new class of sequences called NBVS to generalize GBVS, essentially extending monotonicity from “one sided” to “two sided”, while some important classical results keep true.

Restricted access

Summary By employing a novel idea and simple techniques, we substantially generalize the Turán type inequality for rational functions with real zeros and prescribed poles established by Min [5] to include L p spaces for 1≤ p ≤ ∞ while loosing the restriction ρ > 2 at the same time.

Restricted access

Abstract  

The international community presently lacks the ability to determine the quality and credibility of environmental measurements that is required to make sound decisions in matters related to international security, public health, and investment-related considerations. The ultimate goal of the work described in this article is to develop a credible information base including measurement capability for determination of environmental contamination and the potential for proliferation of material components of chemical or nuclear weapons. This study compared the accuracy obtained by six Russian and six U.S. laboratories for samples representative of classes of trace metals, dioxin-furans, and radioactive substances. The results obtained in this work indicate that current estimates for laboratory accuracy are likely overly optimistic. The weaknesses discovered by this prototype U.S. — Russia, study also exist within the broader international community of laboratories. Further work is proposed to address the urgent need for the international community to improve performance evaluations for analytical measurements.

Restricted access

Abstract  

Late-Quaternary material of various rodent species remnants (lower jaws and teeth) of different depth and age burials from zoogenic deposits in karstic cavities of the Urals (Russia) has been analyzed by thermogravimetry, differential thermal analysis, differential scanning calorimetry, and inductively coupled plasma mass spectrometry. Exothermic peaks position and shape as well as quantitative values of mass loss and heat effects (especially parameters of organic matter combustion at 200–600 °C) were found to vary significantly depending on bone’s age and fossilization conditions. On the basis of correlation between bone organic component and corresponding concentrations of some trace elements, three different types of fossilization had been proposed. The obtained values of the organic contents in the bone remnants of similar type and location were used to identify different age admixtures as well as chronologically systematize large sample collections.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors:
Yu D. Perfiliev
,
V. S. Rusakov
,
L. A. Kulikov
,
A. A. Kamnev
, and
K. Alkhatib

Summary  

Resonant lines observed in source experiments are usually significantly broader thanthosein the corresponding absorber experiments. In order to explain this phenomenon, the model of a trapped electron has been proposed. Auger electrons emitted, for instance, after electron capture by 57Со or after the converted isomeric transition of119mSn, as well as secondary electrons, may be trapped in the vicinity of the nucleogenic ion. An asymmetric distribution of quadrupole splittings in the resulting emission Mössbauer spectra is thus a consequence of electron capture by lattice traps located at different distances from the daughter ion. Estimates of quadrupole splitting values, which may be causedby trapped electrons located at different distances from the nucleogenic atom, support the above mentioned model.

Restricted access

Abstract  

Neutron activation analysis has been applied to determine the purity of super-enriched176Yb as well as a diagnostic to optimize yields from the P.A.R.I.S. mass separator at Orsay. In 25 mass separations carried out during 3 months, 910 mg of super-enriched176Yb2O3 were recovered from the original 7 g of176Yb2O3 (97.5% enrichment). Neutron activation analysis has shown that only two per thousand of the initially present174Yb remained in the super-enriched product. Using this176Yb super-enriched (99.998%) target, micro-quantities of the high spin (16+) isomer178m2Hf were produced by the (,2n) reaction at the U-200 cyclotron in Dubna. Quantities of about 2·1012 atoms of this isomer have been irradiated by thermal neutron at the ORPHEE Reactor, Saclay. Only the neutron capture giving rise to the isomeric state 25/2 of179Hf has been measured, by detection -rays of this 25.1 days isomer. A cross section of 45±5 barns was obtained for178m2Hf(n,)179m2Hf.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors:
S. Rosenberg
,
V. Zaloznikh
,
Yu. Zolotarev
,
D. Zajtsev
,
V. Kozic
, and
N. Myasoedov

Abstract  

A method has been developed for the analysis of deuterium water solutions of tritiated glycine and alanine complex isotopic mixtures by using high resolution3H (at 266.8 MHz) and1H (at 250.13 and 500.13 MHz) NMR spectra. Approaches have been worked out for the determination of quantitative composition of mixtures and spectral parameters.

Restricted access

Abstract  

A method for synthesizing tritium- or deuterium-labeled amino acids, peptides and biogenic amines through high temperature solid state catalytic isotope exchange (HSCIE) is proposed. The dependence of the degree of isotope exchange in HSCIE on the structure of the compound, the reactivity of hydrogen at different carbon atoms and the conditions of the process has been examined. If HSCIE is performed in the temperature range of 373 to 413K, the selectivity of isotopic label incorporation comes to 70% or higher. When the tritium label is introduced into peptides, they retain the configuration of asymmetric atoms, even upon the substitution of tritium for hydrogen at the -carbon atoms of the amino acid residues. HSCIE at 453–513K leads to an even distribution of the isotopic label over the organic compound molecule. The results of3H NMR spectroscopy highlighting the distribution of the tritium label in the organic compound molecules are presented. The configuration of asymmetric atoms in amino acids is preserved to a high extent upon 80–90% substitution of isotopes for hydrogen atoms.

Restricted access

Abstract

In this paper, we studied the inhibitory effect of oleanolic acid (OA) on non-enzymatic glycosylation and the improvement of glycometabolism in insulin resistant (IR) human liver tumour (HepG2) cells. The anti-glycosylation activity of OA was determined by bovine serum albumin (BSA) fructose model. The results showed that OA moderately inhibited the formation of the intermediates of non-enzymatic glycosylation, fructosamine and α-dicarbonyl compounds, and strongly inhibited the formation of advanced glycation end products (AGEs). In addition, we analysed the effect of OA on glycometabolism induced by palmitic acid (PA) in HepG2 cells. The results showed that OA had almost no impact on HepG2 cell viability at concentrations lower than 30 µM. With the increase of OA concentration, glucose production in IR HepG2 cells decreased, while glycogen content increased. Meanwhile, OA has a significant inhibitory effect on reactive oxygen species (ROS) levels in IR-HepG2 cells. Those results suggested that OA could be a promising natural blood glucose decreasing substance in the pharmaceutical and functional food industries.

Restricted access