388 research outputs found
Autoresonance in a Dissipative System
We study the autoresonant solution of Duffing's equation in the presence of
dissipation. This solution is proved to be an attracting set. We evaluate the
maximal amplitude of the autoresonant solution and the time of transition from
autoresonant growth of the amplitude to the mode of fast oscillations.
Analytical results are illustrated by numerical simulations.Comment: 22 pages, 3 figure
Behaviour pattern of rock mass haulage energy intensity in deep pits
A significant portion of mineral deposits developed by open-pit mining is opened to the full depth by road transport ramps without the use of combined transport. In most cases, this is dictated by the high rate of a pit deepening and multi-stage development. In this study, the energy intensity of rock mass (RoM) haulage from the working zone of a pit to the surface is considered at several hierarchical levels. Mineframe software was used to study 3D-models of open pits with different slope angles in order to test the method of analytical calculation of a pit volume that allowed ensuring accuracy under a wide range of mining conditions. The findings of the research are as follows: with an increase in the pit bottom diameter, the zone of stabilization of rock mass lifting (haulage) height shifts to greater target depths. An increase in the pit slope angles entails shifting the weighted average height to deeper elevations. By increasing the pit target depth, combined modes of transport become more economical in comparison with dump trucks due to an increase in the total volume of rock mass. Depending on the comparison purpose, it was proposed to use different types of energy intensity. For a broad estimation of the rationality of the pair “scheme of opening – mode of transport” for open pits, the ratio of potential energy intensities of rock mass haulage of a considered option of a pit opening and its basic option without transport berms was used. The ratio of potential energy intensities as a function of a pit depth was determined. The values of total energy intensity of rock mass haulage from a pit to the surface were also established
ADAPTING PORTAL DECOMPRESSION FOR ELEVATION OF EFFICACY OF PORTOSYSTEMIC SHUNTING OPERATIONS IN PORTAL HYPERTENSION
Purpose: to improve the results of portosystemic shunting surgical interventions using of procedures of adapting portal decompression during preoperation period. Materials and Methods: the results of transjugular intrahepatic portosystemic shunt (TIPS procedure) in 113 patients were analyzed. In 60 cases the procedure of adapting portal decompression during a period 3-5 weeks using selective vasoconstrictor octreotide in complex with non-selective beta-blockers.Results: during the follow-up postoperative period in group of patients who were undergone for adapting portal decompression the restitution of clinical and laboratory data was noticed and does not increase occurrence of hepatic insufficiency in comparison with control group.Summary: using of adapting portal decompression in preoperative period before TIPS procedure in patients with complicated portal hypertension is effective for prophylaxis of making worse of hepatic insufficiency
Composition, properties, and structure of palladium(II) chlorides in aqueous solution
The composition, stability, and structure of palladium(II) chloride complexes in hydrochloric acid media have been determined using nuclear-magnetic relaxation, magnetochemical methods, and Rayleigh light scattering. The predominant form in solution for palladium(II) concentrations greater than 0.005 moles/liter is the octahedral Pd6Cl12 or Pd6Cl14 2-, which has antiferromagnetic properties in contrast with the paramagnetic properties of the mononuclear aquachloride. The polarizability anisotropy of Pd-Cl bonds with terminal and bridging chlorine atoms has been determined. © 1991 Plenum Publishing Corporation
Resistance of <i>Rhodococcus ruber</i> biofilms to CuO nanoparticles depending on exopolymer matrix composition
Background. The widespread use of copper oxide nanoparticles (CuO NPs) increases their release into the environment, which leads to accumulation in trophic chains. Bacterial biofilms are more resistant to physico-chemical factors compared to planktonic cells due to an exopolymer matrix (EPM) consisting of polysaccharides, proteins, lipids and nucleic acids. Rhodococcus actinobacteria are promising for environmental biotechnology due to biodegradation of petroleum products, pesticides and other organic pollutants, as well as bioaccumulation of heavy metals. The aim. To investigate effects of CuO NPs on the viability of Rhodococcus ruber IEGM 231 cells in biofilms and the dynamics of EPM components. Methods. R. ruber biofilms were grown on microscopy cover glass with CuO NPs and EPM components were studied using confocal laser scanning microscopy (CLSM) by differentiating staining with LIVE/DEAD to determine the number of living and dead cells, Nile Red for lipids, FITC for proteins and Calcofluor White for betapolysaccharides. Results. It was found that R. ruber biofilms grown in a mineral medium with1.0 vol.% n-hexadecane are more resistant to CuO NPs compared to biofilms growing in a rich culture medium (meat-peptone broth). This was due to more intensive EPM formation, which plays a major role in protecting cells from the bactericidal action of nanometals. A weak stimulating effect of a low (0.001 g/l) concentration of CuO NPs on biofilm formation was registered. Dynamics and localization of main EPM components were monitored during prolonged (24–72 h) biofilm cultivation with CuO NPs. When exposed to high (0.01–0.1 g/l) concentrations of CuO NPs, a consistently high lipid content and an increase in concentrations of polysaccharides and proteins were revealed. Conclusion. Understanding the complex interaction mechanisms of nanometals and biofilms will contribute to the development of effective biocatalysts based on immobilized bacterial cells. Also, the obtained data can be used to combat unwanted biofilms with the help of metal nanoparticles
Model of vocational school, high school and manufacture integration in the regional system of professional education
© 2015, Canadian Center of Science and Education. All rights reserved. Integration of vocational, high schools and manufacture contributes to qualified personnel for the regional oil industry effective training. So this article is aimed at the model development of vocational, high school and manufacture integration in the regional system of vocational education. The basic approach to the structural-functional model development of vocational, high school and manufacture integration in the regional system of vocational education is an integrative one, taking into consideration the integrated system “vocational school-high school-manufacture” components in their unity and cooperation, giving it the integrity and structural and functional stability. Structural-functional model of vocational, high school and manufacture integration in the regional system of vocational education includes functional-target, organizational-structural, content, process and result components
Two-Stage Rotational Disordering of a Molecular Crystal Surface: C60
We propose a two-stage mechanism for the rotational surface disordering phase
transition of a molecular crystal, as realized in C fullerite. Our
study, based on Monte Carlo simulations, uncovers the existence of a new
intermediate regime, between a low temperature ordered state,
and a high temperature disordered phase. In the intermediate
regime there is partial disorder, strongest for a subset of particularly
frustrated surface molecules. These concepts and calculations provide a
coherent understanding of experimental observations, with possible extension to
other molecular crystal surfaces.Comment: 4 pages, 2 figure
Assessment of the possibility for large-scale 238Pu production in a VVER-1000 power reactor
The paper presents the estimates for the possibility for large-scale production of 238Pu in the core of a VVER-1000 power reactor. The Np-fraction of minor actinides extracted from transuranic radioactive waste is proposed to be used as the starting material. The irradiation device with NpO2 fuel elements is installed at the reactor core center. The NpO2 fuel lattice pitch is varied and the irradiation device is surrounded by a heavy moderator layer to create the best possible spectral conditions for large-scale production (~ 3 kg/year) of conditioned plutonium with the required isotopic composition (not less than 85% of 238Pu and not more than 2 ppm of 236Pu). Plutonium with such isotopic composition can be used as the thermal source in thermoelectric radioisotope generators and in cardiac pacemakers. It has been demonstrated that the estimated scale of the 238Pu production in a VVER-type power reactor exceeds considerably the existing scale of its production in research reactors
Chemical genetic screen identifies lithocholic acid as an anti-aging compound that extends yeast chronological life span in a TOR-independent manner, by modulating housekeeping longevity assurance processes
In
chronologically aging yeast, longevity can be extended by administering a
caloric restriction (CR) diet or some small molecules. These life-extending
interventions target the adaptable target of rapamycin (TOR) and
cAMP/protein kinase A (cAMP/PKA) signaling pathways that are under the
stringent control of calorie availability. We designed a chemical genetic
screen for small molecules that increase the chronological life span of
yeast under CR by targeting lipid metabolism and modulating housekeeping
longevity pathways that regulate longevity irrespective of the number of
available calories. Our screen identifies lithocholic acid (LCA) as one of
such molecules. We reveal two mechanisms underlying
the life-extending effect of LCA in chronologically aging yeast. One
mechanism operates in a calorie availability-independent fashion and
involves the LCA-governed modulation of housekeeping longevity assurance
pathways that do not overlap with the adaptable TOR and cAMP/PKA pathways.
The other mechanism extends yeast longevity under non-CR conditions and
consists in LCA-driven unmasking of the previously unknown anti-aging
potential of PKA. We provide evidence that LCA modulates housekeeping
longevity assurance pathways by suppressing lipid-induced necrosis,
attenuating mitochondrial fragmentation, altering oxidation-reduction
processes in mitochondria, enhancing resistance to oxidative and thermal
stresses, suppressing mitochondria-controlled apoptosis, and enhancing
stability of nuclear and mitochondrial DNA
Results of multidisciplinary survey in the Laptev Sea in August-September, 2015
Data on oceanographic conditions and species composition of plankton, benthic and demersal fish and invertebrates are presented, obtained in the complex survey over the external shelf of the Laptev Sea in August-September 2015. The zooplankton abundance was low, with only local increases up to 400 mg/m3. Species diversity of fish and nekton invertebrates in the bottom trawl catches was low, too: 26 fish species and 2 species of cephalopods. Mean biomass of fish was estimated as 4.3 t/km2 (in total 132. 103 t within the surveyed area of 30,500 km2). All fish species were distributed sparse. Arctic cod was the most abundant and occurred over the whole surveyed area, with large-sized fish dominating at the bottom and medium-sized (9-15 cm) fish - in the pelagic layer, other commercial species were greenland halibut and deepwater redfish caught on the continental slope. Bottom invertebrates in trawl catches were presented by 6 species of shrimp and 12 taxonomic groups of different rank, with predominance of starfish, brittle stars and sponges; gastropods were represented by 11 species, with Neptunea heros dominating by mass (42 %). Macrobenthos in samples of the bottom sampler was presented by 20 taxonomic groups, with predominance of polychaetes, bivalves and sipunculoids
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