Electron paramagnetic resonance of Gd3+ aqua complexes in vitrified aqueous solutions and Gd3+ aqua ions adsorbed on the capillary surface

Electron paramagnetic resonance (EPR) spectra of Gd3+ aqua complexes are measured in dilute aqueous solutions of Gd(NO3)3 (C < 0.2 M) at room temperature. A partial resolution of the fine structure observed in the spectra is characteristic of solid disordered systems and results in an increase in the effective width of the EPR line with a decrease in the Gd3+ concentration. This phenomenon is explained in terms of adsorption of Gd3+ aqua ions on the surface of the measuring capillaries. The fine structure is revealed in the EPR spectra of Gd(NO3)3 aqueous solutions, namely, the Gd(NO3)3 solutions vitrified at a temperature of 77 K (with an addition of 10-15 vol % glycerol) and Gd(NO3)3 solutions quasi-vitrified at 298 K (with an addition of 70-90 vol % glycerol). Analysis of the EPR spectra demonstrates that these solutions contain two types of aqua complexes with fine structure parameters D1 = 180 G and D2 = 580 G. Reasoning from a comparison with x-ray diffraction data, the fine structure parameters D1 and D2 are assigned to higher symmetric eight-coordinate and lower symmetric nine-coordinate Gd3+ aqua complexes, respectively. © 2003 MAIK "Nauka/Interperiodica"

Structural transformations and phase transitions in aqueous solutions of gadolinium nitrate in the course of freezing

The microstructure of Gd(NO3)3 aqueous solutions in the course of cooling at different rates is investigated using electron paramagnetic resonance. The local concentrations of Gd3+ ions in microregions are estimated, the concentration boundary at which the solution is completely vitrified throughout its volume is revealed, and the temperature of vitrification of liquid microregions (eutectic temperature) and the eutectic composition are determined. It is found that the adsorption of Gd3+ aqua ions on the capillary surface affects the crystallization of water and the process of concentration of the solute. It is demonstrated that the anomalous experimental dependence δH(C0), which is observed for vitrified water-glycerol solutions with a uniform distribution of paramagnetic centers over the sample, agrees well with the theoretical curve in the case when allowances are made not only for the dipole-dipole interactions but also for the inhomogeneous broadening of the EPR lines in the spectra with an incompletely resolved fine structure. © 2003 MAIK "Nauka/Interperiodica"

Russian entrepreneurship in the context of the economic crisis: tendencies, problems and prospects

The objective of the article is to analyze the main trends of entrepreneurship in Russia and identify areas of its activation to support sustainable economic growth and economic security. The article presents the authors’ approach to the definition of entrepreneurial activit

The Main Modern Trends in the Economy and Society in the Development of Tourism

Research aimed to reveal the character of the links between main modern trends in the economy and society and the development of tourism as one of the sectors of the Russian economy, on the one hand, and the type of human activity, on the othe

Spectrum of conditionally pathogenic microflora isolated from the prostate secret in chronic bacterial prostatitis patients

The article represents a description for microbiocenosis of isolated prostate secret. The initial samples were taken on the territory of the Irkutsk region from men diagnosed with chronic bacterial prostatitis in the acute stage. 90 % of samples of isolated prostate secret were tested by cultural method revealed 4l representatives of opportunistic pathogenic microflora. Gram-positive microorganisms were found in most samples (86.7 %). Staphylococcus genus representatives formed the majority in isolated samples of conditionally pathogenic microflora (66.7 %). As for gram-negative representatives (which role in chronic bacterial prostatitis is proven by multiple research), E. coli and K. pneumoniae were isolated. In the half of samples, we revealed bacterial associations consisting mostly of two kinds of microorganisms. Staphylococcus epidermidis was isolated in 70 % of such associations

Properties of Neutral Charmed Mesons in Proton--Nucleus Interactions at 70 GeV

The results of treatment of data obtained in the SERP-E-184experiment "Investigation of mechanisms of the production of charmed particles in proton-nucleus interactions at 70 GeV and their decays" by irradiating the active target of the SVD-2 facility consisting of carbon, silicon, and lead plates, are presented. After separating a signal from the two-particle decay of neutral charmed mesons and estimating the cross section for charm production at a threshold energy {\sigma}(c\v{c})=7.1 \pm 2.4(stat.) \pm 1.4(syst.) \mub/nucleon, some properties of D mesons are investigated. These include the dependence of the cross section on the target mass number (its A dependence); the behavior of the differential cross sections d{\sigma}/dpt2 and d{\sigma}/dxF; and the dependence of the parameter {\alpha} on the kinematical variables xF, pt2, and plab. The experimental results in question are compared with predictions obtained on the basis of the FRITIOF7.02 code.Comment: 9 pages, 9 figures,3 table

PREOPERATIVE CHEMOTHERAPY FOR COLORECTAL CANCER LIVER METASTASES: SHORT-TERM RESULTS

Background. At present liver resection combined with chemotherapy is the only treatment for isolated resectable colorectal cancer liver metastases that potentially can achieve cure. Effective preoperative chemotherapy allows us to evaluate chemoresponsiveness of the tumor and increase metastases resectability.Materials and methods. Between 2006 and 2011, 60 patients with potentially resectable colorectal cancer liver metastases were included in the study. All patients received preoperative oxaliplatin- or irinotecan-based chemotherapy; average duration of treatment was 3.6 ± 0.11 months. Liver resection was performed after chemotherapy: 29 (48.3 %) pts underwent hemihepatectomy, 11 (18.3 %) pts – extended hemihepatectomy and 20 (33.4 %) pts – segmentectomy. Pathologic response in liver metastases was assessed to analyze efficacy of preoperative chemotherapy.Results. Objective response to preoperative chemotherapy was observed in 33 (55 %) pts. 23 (38.3 %) patients had stable disease. The maximum effect of preoperative chemotherapy was achieved in patients with bilobar liver metastases, receiving combination with oxaliplatin – in 23 (63.9 %) cases. Side effects of 334 cycles of preoperative chemotherapy were assessed. In most cases, adverse events were not clinically significant. Side effects of grade III/IV in 18 (5.4 %) cycles were observed in 12 (20 %) patients. 52 (86.7 %) patients underwent R0-resections; 8 pts had R1 (n = 5) и R2 (n = 3) resections of metastases. There were no postoperative deaths. Pathologic response was observed in 55/60 (91.7 %) cases: grade I was seen in 17 (28.3 %) cases; grade II – in 14 (23.3 %); grade III – in 20 (33.3 %) and grade IV – in 4 (6.8 %) cases. Pathologic response of grade III/IV occurred in 63.6 % patients with partial treatment response and 13 % pts – with stable disease (р = 0.01).Conclusions. Highest efficacy of preoperative chemotherapy in combined treatment of colorectal cancer was achieved in patients with bilobar liver metastases. Safety of two-component chemotherapy regimens was confirmed. This study presents significant correlation between preoperative chemotherapy efficacy and pathologic response in liver metastases

Clinical and epidemiological features of sexually transmitted infections among vulnerable populations

Objective of the study was to reveal main clinical and epidemiological peculiarities of various STIs course in MSM group on the basis of foreign scientific literature data.Цель исследования – на основании данных зарубежной научной литературы выявить основные клинико-эпидемиологические особенности течения различных ИППП в группе МСМ

Visual ecology of aphids – a critical review on the role of colours in host finding

We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms. Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region. We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphid–tree interactions imply far-reaching assumptions on aphid responses to colours that are not likely to hold. Finally we also discuss the implications for developing and optimising strategies of aphid control and monitoring