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Optimal proportioning of concrete aggregates using a self-adaptive genetic algorithm
Adil Amirjanov,Konstantin Sobolev 한국계산역학회 2005 Computers and Concrete, An International Journal Vol.2 No.5
A linear programming problem of the optimal proportioning of concrete aggregates is discussed; and a self-adaptive genetic algorithm is developed to solve this problem. The proposed method is based on changing a range of variables for capturing the feasible region of the optimum solution. A computational verification of this method is compared with the results of the linear programming.
Uma, Sitharaman,Vasilchikova, Tatyana,Sobolev, Alexey,Raganyan, Grigory,Sethi, Aanchal,Koo, Hyun-Joo,Whangbo, Myung-Hwan,Presniakov, Igor,Glazkova, Iana,Vasiliev, Alexander,Streltsov, Sergey,Zvereva, American Chemical Society 2019 Inorganic chemistry Vol.58 No.17
<P>A new oxide, sodium-iron antimonate, Na<SUB>2</SUB>FeSbO<SUB>5</SUB>, was synthesized and structurally characterized, and its static and dynamic magnetic properties were comprehensively studied both experimentally by <I>dc</I> and <I>ac</I> magnetic susceptibility, magnetization, specific heat, electron spin resonance (ESR) and Mössbauer measurements, and theoretically by density functional calculations. The resulting single-crystal structure (<I>a</I> = 15.6991(9) Å; <I>b</I> = 5.3323 (4) Å; <I>c</I> = 10.8875(6) Å; S.G. <I>Pbna</I>) consists of edge-shared SbO<SUB>6</SUB> octahedral chains, which alternate with vertex-linked, magnetically active FeO<SUB>4</SUB> tetrahedral chains. The <SUP>57</SUP>Fe Mössbauer spectra confirmed the presence of high-spin Fe<SUP>3+</SUP> (3d<SUP><I>5</I></SUP>) ions in a distorted tetrahedral oxygen coordination. The magnetic susceptibility and specific heat data show the absence of a long-range magnetic ordering in Na<SUB>2</SUB>FeSbO<SUB>5</SUB> down to 2 K, but <I>ac</I> magnetic susceptibility unambigously demonstrates spin-glass-type behavior with a unique two-step freezing at <I>T</I><SUB>f1</SUB> ≈ 80 K and <I>T</I><SUB>f2</SUB> ≈ 35 K. Magnetic hyperfine splitting of <SUP>57</SUP>Fe Mössbauer spectra was observed below <I>T</I>* ≈ 104 K (<I>T</I><SUB>f1</SUB> < <I>T</I>*). The spectra just below <I>T</I>* (<I>T</I><SUB>f1</SUB> < <I>T</I> < <I>T</I>*) exhibit a relaxation behavior caused by critical spin fluctuations, indicating the existence of short-range correlations. The stochastic model of ionic spin relaxation was used to account for the shape of the Mössbauer spectra below the freezing temperature. A complex slow dynamics is further supported by ESR data revealing two different absorption modes presumably related to ordered and disordered segments of spin chains. The data imply a spin-cluster ground state for Na<SUB>2</SUB>FeSbO<SUB>5</SUB>.</P><P>A new oxide, sodium−iron antimonate, Na<SUB>2</SUB>FeSbO<SUB>5</SUB>, was synthesized, and its structural and magnetic properties were studied. The system does not undergo a long-range magnetic order in agreement with the fact that it is a one-dimensional magnetic chain system. The mapping analysis based on density functional theory calculations shows a strong one-dimensional, antiferromagnetic intrachain exchange coupling of ∼200 K.</P> [FIG OMISSION]</BR>
Systems of mechanized and reactive droplets powered by multi-responsive surfactants
Yang, Zhijie,Wei, Jingjing,Sobolev, Yaroslav I.,Grzybowski, Bartosz A. Macmillan Publishers Limited, part of Springer Nat 2018 Nature Vol.553 No.7688
Although ‘active’ surfactants, which are responsive to individual external stimuli such as temperature, electric or magnetic fields, light, redox processes or chemical agents, are well known, it would be interesting to combine several of these properties within one surfactant species. Such multi-responsive surfactants could provide ways of manipulating individual droplets and possibly assembling them into larger systems of dynamic reactors. Here we describe surfactants based on functionalized nanoparticle dimers that combine all of these and several other characteristics. These surfactants and therefore the droplets that they cover are simultaneously addressable by magnetic, optical and electric fields. As a result, the surfactant-covered droplets can be assembled into various hierarchical structures, including dynamic ones, in which light powers the rapid rotation of the droplets. Such rotating droplets can transfer mechanical torques to their non-nearest neighbours, thus acting like systems of mechanical gears. Furthermore, droplets of different types can be merged by applying electric fields and, owing to interfacial jamming, can form complex, non-spherical, ‘patchy’ structures with different surface regions covered with different surfactants. In systems of droplets that carry different chemicals, combinations of multiple stimuli can be used to control the orientations of the droplets, inter-droplet transport, mixing of contents and, ultimately, sequences of chemical reactions. Overall, the multi-responsive active surfactants that we describe provide an unprecedented level of flexibility with which liquid droplets can be manipulated, assembled and reacted.
First detection of a G1-like H9N2 virus in Russia, 2018
Sharshov, Kirill,Kurskaya, Olga,Sobolev, Ivan,Leonov, Sergey,Kabilov, Marsel,Tatyana, Alikina,Alekseev, Alexander,Derko, Anastasiya,Yushkov, Yuriy,Saito, Takehiko,Uchida, Yuko,Mine, Junki,Irza, Victor The Korean Society of Veterinary Science 2019 大韓獸醫學會誌 Vol.59 No.1
Worldwide, avian influenza H9N2 viruses of different lineages are the most widespread viruses in poultry. However, to date, cases in Russia have not been documented. In this study, we report the first detection of a G1-like H9N2 virus from poultry sampled at live-bird markets in Russia (Far East region) during the winter of 2018 (isolate A/chicken/Amur_Russia/17/2018). We assume there has been further circulation of the A/chicken/Amur_Russia/17/2018 H9N2 virus in the Russian Far East with possible distribution to other regions or countries in 2018-2019.
Matthew R. Boyett,Alireza Tavakkoli,Dmitri Sobolev 한국해양과학기술원 2013 Ocean science journal Vol.48 No.3
Molecular analysis of cyanobacterial mat communities indicated that cyanobacteria, ammonia-oxidizing Archaea (AOA), and ammonia-oxidizing bacteria (AOB) coexist in those systems, competing for ammonium; this situation would imply competitive exclusion. We attempted to model how ammonia utilization niche partitioning occurs, and how ammonium levels can influence the interaction between those groups in a one-dimensional diffusionlimited system using Michaelis-Menten kinetics to describe ammonium consumption by each of those three groups. In our model, AOAs were able to dominate ammonium uptake by the community under most circumstances, except for unrealistically high (millimolar) levels of ammonium, where AOBs gained advantage. Cyanobacteria were unable to effectively compete for ammonium with either AOBs or AOAs throughout the mat at all ammonium concentrations and cell counts, suggesting that the presence of AOAs or AOBs forces cyanobacteria into nitrogen fixation mode. Such interaction can make cyanobacterial mats a net nitrogen source, as well as provide a carbon-independent energy transfer pathway from primary producers to the rest of the ecosystem.
Plate tectonics on the Earth triggered by plume-induced subduction initiation
Gerya, T. V.,Stern, R. J.,Baes, M.,Sobolev, S. V.,Whattam, S. A. Nature Publishing Group, a division of Macmillan P 2015 Nature Vol.527 No.7577
Scientific theories of how subduction and plate tectonics began on Earth—and what the tectonic structure of Earth was before this—remain enigmatic and contentious. Understanding viable scenarios for the onset of subduction and plate tectonics is hampered by the fact that subduction initiation processes must have been markedly different before the onset of global plate tectonics because most present-day subduction initiation mechanisms require acting plate forces and existing zones of lithospheric weakness, which are both consequences of plate tectonics. However, plume-induced subduction initiation could have started the first subduction zone without the help of plate tectonics. Here, we test this mechanism using high-resolution three-dimensional numerical thermomechanical modelling. We demonstrate that three key physical factors combine to trigger self-sustained subduction: (1) a strong, negatively buoyant oceanic lithosphere; (2) focused magmatic weakening and thinning of lithosphere above the plume; and (3) lubrication of the slab interface by hydrated crust. We also show that plume-induced subduction could only have been feasible in the hotter early Earth for old oceanic plates. In contrast, younger plates favoured episodic lithospheric drips rather than self-sustained subduction and global plate tectonics.