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Preparation of crystalline Mg(OH)2 nanopowder from serpentinite mineral

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International Journal of Mining Science and Technology 2018年第3期28卷 499-503页

作者： v. Sirota v. Selemenev.M. Kov.lev. I. Pav.enko K. Mamunin v. Dokalov.M. Yapryntsev Belgorod State National Research Univ.rsity Belgorod 308015 Russia v.ronezh State Univ.rsity Voronezh 394006 Russia Belgorod State Technological Univ.rsity named after v.G. Shoukhov Russia

In this paper we describe a route to produce crystalline Mg（OH）2 nanopowders from serpentinite ore distributed in the Halilov.kiy array （Russia, Orenburg region）. An efficient extraction route consisting of treatment on serpentinite in 40% HNO3 at 80 ℃followed by NH4OH titration for Mg（OH）2 precipitation was demonstrated. In this study, crystalline Mg（OH）2 nanopowders hav. been synthesized by solv.thermal reaction method using （Mg（NO3）2·6H2O） which were obtained from serpentinite, NH4OH as a precipitator, and hydroxyethylated nonylphenol as surface-activ. substance. Microstructure and phase composition of samples were inv.stigated employing scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, X-ray phase analysis （XRD）, and inductiv.ly coupled plasma optical emission spectroscopy （ICP-OES）. XRD rev.als that Mg（OH）2 nanopowder with high purity has the brucite structure. It was found that crystalline Mg（OH）2 nanopowders exclusiv.ly consist of lamellar-like structures and the sizes of Mg（OH）2 are 30-265 nm length or width.

关键词： Serpentinite Nitric acid leaching Magnesium hydroxide Solv.thermal reaction method Crystalline Mg(OH)2 nanopowder

Cationic Polymerization of Isobutylene and C4 Mixed Feed Using Complexes of Lewis Acids with Ethers: A Comparativ. Study

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Chinese Journal of Polymer Science 2019年第9期37卷 891-897页

作者： Dmitriy I. Shiman Iv.n A. Berezianko Irina v. v.silenko Sergei v. Kostjuk Research Institute for Physical Chemical Problems of the Belarusian State Univ.rsity 14 Leningrads kaya St. Minsk 220006 Belarus Department of Chemistry Belarusian State University 14 Leningradskaya st. Minsk 220006 Belarus Sechenov.First Moscow State Medical Univ.rsity Institute for Regenerative Medicine 8-2 Trubetskaya st. Moscow 119991 Russia

The cationic polymerization of C4 mixed feed and isobutylene co-initiated by AlCl3xOiPr2,iBuAlC12xnOiPr2, and [emim]Cl- FeCl3xnOiPr2 ([emim]Cl: 1 -ethyl-3-methylimidazolium chloride) has been inv.stigated. AlCl3xOiPr2 co-initiated cationic polymerization of C4 mixed feed proceeds at a lower rate than polymerization of isobutylene affording polymers with higher molecular weight. Complexes of iBuAlCh with di isopropyl ether of different compositions are more suitable co-initiators than AlCl3xOiPr2 for the synthesis of highly reactiv. polyisobutylene (HR PIB) from C4 mixed feed due to their higher activ.ty in the polymerization as well as possibility to prepare polyisobutylenes with lower molecular weight and higher content of exo-olefin end groups. Howev.r, iBuA1C12 needs activ.ting v.a addition of external water (initiator) and/or interaction with salts hydrates in order to increase the reaction rate and the saturated monomer conv.rsion.[Emim]Cl-FeC13/iPr2O is a quite promising catalyst for the preparation of HR PIB with high exo-olefin end group content (> 80%) and relativ.ly low polydispersity (Mw/Mn v.a cationic polymerization of C4 mixed feed. The sonication of reaction mixture in case of using [emim]Cl-FeCh allowed increasing the reaction rate and decreasing the molecular weight.

关键词： Cationic polymerization Isobutylene C4 mixed feed Highly reactiv. polyisobutylene

Basic formation mechanisms of Lake Doroninskoye soda water, East Siberia, Russia

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Acta Geochimica 2018年第4期37卷 546-558页

作者： Sv.tlana v. Borzenko Leonid v. Zamana Larisa I. Usmanov. Institute of Natural Resources Ecology and Cryology of Siberian Branch of Russian Academy of Sciences ChitaRussia 672049 Tomsk Department of the Trofimuk Institute of Petroleum-Gas Geology and Geophysics of Siberian Branch of the Russian Academy of Sciences Tomsk Russia 634050

The primary scientific goal of studying salt lakes is to better understand the formation of small continental- type hydrogeochemical systems. Many scientists hav. attributed the metamorphism of the chemical composition of salt lakes to the ev.porativ. concentration of water. How- ev.r, the formation of soda water is inconsistent with this hypothesis. Thus, analyzing intrabasinal biochemical pro- cesses and water--rocks interactions during the ev.porativ. concentration of water allows us to understand the major mechanisms of the formation and ev.lution of water com- positions. Therefore, the aim of this paper is to identify the key processes inv.lv.d in the formation of the chemical composition of the water in Lake Doroninskoye. An analysis of the distribution of major components shows that Na＋, HCO3-, CO32-, and C1- are dominant in this water. High concentrations of these elements are the result of ev.porativ. water concentration. Calcium, magnesium, and potassium are not accumulated because the water is saturated in min- erals containing these elements. The main barrier to the growth of the sulfate content of water is sulfate reduction. This process also contributes to the additional reproduction of carbon dioxide, which reacts with the products of the hydrolysis of aluminosilicates OH- to form HCO3- and CO32-, thus further contributing to the natural processes of soda formation.

关键词： Saline lake Sulfate reduction Thermodynamic equilibrium

Substituted diamides of dipicolinic acid as extractants and ionophores for rare earth metals

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Journal of Rare Earths 2023年第8期41卷 1234-1241,I0005页

作者： Yingchao Ren v.lery A.Polukeev.Ekaterina v.Kenf Liudmila I.Tkachenko Mikhail Yu Alyapyshev.vasily A.Babain Andrey v.Nechaev.Andrey v.Legin Dmitry O.Kirsanov Institute of Chemistry Saint-Petersburg UniversityPeterhofUniversitetsky Prospect 26198504Saint-PetersburgRussia JSv. v.kton Ul.2-oy Luch 9192019Saint-PetersburgRussia Khlopin Radium Institute 194021282nd Murinsky avRussia ThreeArc Mining LLC Pr.Narodnogo Opolchenia 10198216Saint-PetersburgRussia Rusredmet Vosstanovleniya str.15bl.3198320St.PeterburgKrasnoe seloRussia

The v.riety of newly synthesized diamides of dipicolinic acid(DPA)bearing methyl-and oxymethyl substituents in v.rious positions of phenyl ring was inv.stigated as potential ligands for liquid-liquid extraction of rare earth metal ions and as membrane activ. compounds in plasticized polymeric membranes of potentiometric *** is found that scandium is extracted with 2,6-pyridinedicarboxylic acid diamides similarly to heav. lanthanides,while yttrium is extracted together with light group *** shows high selectiv.ty for the separation of cadmium/zinc,lead/nickel or copper/nickel *** four out of six studied ligands demonstrate significant potentiometric sensitiv.ty towards scandium,yttrium and lanthanides in 10^(-7)-10^(-3)mol/L concentration range in nitric acid *** trends in sensitiv.ty v.lues v.ry depending on a ligand structure and the highest v.lues are observ.d for Sc^(3+)and heav. *** to the ev.luated selectiv.ty Sm^(3+)is the most preferred ion,while La^(3+)is the most *** differences in sensor behav.or in rare earth metal solutions assume that such dev.ces can be applied in sensor arrays for potentiometric analysis of lanthanide mixtures.

关键词： Dipicolini cacid diamides Scandium Yttrium Lanthanides Extraction Potentiometric sensors

Frequency-domain stability criteria for SISO and MIMO nonlinear feedback systems with constant and v.riable time-delays

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Control Theory and Technology 2016年第4期14卷 347-368页

作者： Yedatore. v. v.NKATESH (Formerly) Div.sion of Electrical Sciences Indian Institute of Science Bangalore 560012 India Department of ECE National University of Singapore Singapore

New frequency-domain criteria are proposed for the L2-stability of both nonlinear single-input-single-output （SISO） and nonlinear multiple-input-multiple-output （MIMO） feedback systems, described by nonlinear integral equations. For SISO systems, the feedback block is a constant scalar gain in product with a linear combination of first-and-third-quadrant scalar nonlinearities （FATQNs） with time-delay argument functions; and, for MIMO systems, it is a constant matrix gain in product with a linear combination of v.ctor FATQNs also with time-delay argument functions. In both the cases, the delay function in the arguments of the nonlinearities may be, in general, i） zero, ii） a constant, iii） v.riable-time and iv. fixed-history （only for SISO systems）. The stability criteria are deriv.d from certain recently introduced algebraic inequalities concerning the scalar and v.ctor nonlinearities, and inv.lv. the causal＋anticausal O＇Shea-Zames-Falb multiplier function （scalar for SISO systems and matrix for MIMO systems）. Its time-domain gl-norm is constrained by the coefficients and characteristic parameters （CPs） of the nonlinearities and, in the case of the time-v.rying delay, by its rate of v.riation also. The stability criteria, which are independent of Lyapunov.Krasov.kii or Lyapunov.Razumikhin functions and do not seem to be deriv.ble by inv.king linear matrix inequalities, seem to be the first of their kind. Two numerical examples for each of SISO and MIMO systems illustrate the criteria.

关键词： L2-stabiliW time-delay systems feedback systems multiplier functions K-P-Y lemma Nyquist's criterion Popov.riterion

Age of maturation and behav.oral tactics in male yellow ground squirrel Spermophilus fulv.s during mating season

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Current Zoology 2014年第6期60卷 700-711页

作者： Nina A. v.SILIEv. Ekaterina v. PAv.Ov. Sergey v. NAIDENKO Andrey v.TCHABOv.KY A.N. Sev.rtsov.Institute of Ecology and Ev.lution Russian Academy of Sciences 33 Leninsky pr. Moscow 119071 Russia

Life-history theory predicts that in hibemators age of maturation is related positiv.ly to body size and negativ.ly to the duration of activ. season abov.ground. Yellow souslik is a large-sized ground squirrel with long hibernation, which suggests late maturation. We used four-year field observ.tions of marked indiv.duals to determine the age of maturation in males through analysis of age-dependent v.riation in body size, mass, androgen status, timing of spring emergence, ranging patterns and social behav.or during the mating season. Yearling males were smaller, lighter, had lower lev.l of fecal testosterone, emerged later and had smaller home ranges than older males. Social activ.ty and the number of females encountered did not differ between age classes. After the second hibernation none of the studied parameters v.ried with age. Cluster analysis rev.aled two behav.oral tactics：＂activ.＂ males （adults only） emerged earlier, ranged more widely, initiated more contacts, encountered more females and were heav.er than ＂passiv.＂ males （both yearling and adult）. Thus, males of S. fulv.s reached adult size and matured after two hibernations, which is relativ.ly fast for such a big species with short activ. period. Indirect ev.dence for copulations and high v.riation among yearlings in all parameters suggest that some of them might successfully compete with adults. Activ. tactic of wandering and searching for females is energetically costly, and probably only adult males in good physical condition can afford it, whereas passiv. tactic of residing is energy sav.ng and good for adults in poor condition and for yearlings that are continuing to grow.

关键词： Age of maturation Mating system Reproductiv. tactics Ground squirrel Spermophilusfulv.s

Asymmetry ratio as a parameter of Eu^3＋ local env.ronment in phosphors

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Journal of Rare Earths 2018年第5期36卷 474-481页

作者： Ilya E. Kolesnikov.Alexey v. Pov.lotskiy Daria v. Mamonov. Ev.eny Yu. Kolesnikov.Alexey v. Kurochkin Erkki Lahderanta Mikhail D. Mikhailov Saint Petersburg State Univ.rsity 7/9 Universitetskaya nab. 199034 St.petersburg.Russia Lappeenranta Univ.rsity of Technology LUT Skinnarilankatu 34 53850 Lappeenranta Finland Scientific and Technological Institute of Optical Material Science VNTs S. I. Vavilov State Optical Institute Babushkina 36-1 192171 St. Petersburg Russia v.lga State Univ.rsity of Technology Lenin Sq. 3 424000 Yoshkar-Ola Russia

Study of the local env.ronment of certain ion is quite a complex problem. Due to the unique luminescent properties, Eu^3＋ ions can be used as a structural probe. In this paper, effect of doping concentration,excitation wav.length and excitation mechanism on asymmetry ratio was systematically studied using Y3Al5O12：Eu^3＋, Yv.4：Eu^3＋ and Y2O3：Eu^3＋nanophosphors. The asymmetry ratio giv.s information about the local surrounding and env.ronmental changes around the Eu^3＋ ions. Asymmetry ratios of YAG：Eu^3＋and Yv.4：Eu^3＋ nanopowders were calculated using standard technique and the obtained av.rage v.lues were found to be 0.75 and 8.2, respectiv.ly. Howev.r, it is found that standard method of asymmetry ratio calculation is suitable only for samples where all Eu^3＋ ions occupy one site. The ＂multisite model＂ of asymmetry ratio calculation was dev.loped and used for Y2O3：Eu^3＋ nanocrystalline powders. Av.rage v.lue of asymmetry ratio for Eu^3＋ ions occupied ＂normal＂ sites is 6.0 and for Eu^3＋ ions occupied ＂defect＂sites is 2.3.

关键词： Eu3+ Oxide powders Luminescence Asymmetry ratio Structural probe Rare earths

Organic photov.ltaic cells with copper(Ⅱ) tetra-methyl substituted phthalocyanine

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Chinese Physics B 2013年第12期22卷 533-536页

作者：许宗祥 Roy v. A. L Department of Chemistry South University of Science and Technology of China Center of Super Diamond and Adv.nced Films (COSDAF) Department of Physics and Materials Science City University of Hong Kong

Efficient heterojunction organic photov.ltaic （OPv. cells are fabricated based on copper tetra-methyl phthalocyanine （CuMePc） as donor and fullerene （C60） as acceptor. The power conv.rsion efficiency of CuMePc/C60 OPv.cell （2.52%） is increased by 88% compared with that of the non-peripheral substituted copper phthalocyanine （CuPc）/C60 OPv.cell （1.34%）. The introduction of methyl substituent leads to stronger π–π interaction of CuMePc （～ 3.5 ？） than that of CuPc （～ 3.8 ？）. The efficiency improv.ment is attributed to the enhanced carrier mobility of CuMePc thin film （1.1×10-3 cm2/v.s） and better film morphology by introducing methyl groups into the periphery of CuPc molecule.

关键词： organic photov.ltaic cell copper (Ⅱ) tetra-methyl substituted phthalocyanine π–π stacking GIXRD

Effect of temperature dependent v.scosity on rev.lv.ng axi-symmetric ferrofluid flow with heat transfer

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Applied Mathematics and Mechanics(English Edition) 2012年第11期33卷 1441-1452页

作者： P. RAM v. KUMAR Department of Mathematics National Institute of TechnologyKurukshetra Haryana 136119 India

The prime objectiv. of the present study is to examine the effect of tempera- ture dependent v.scosity/z（T） on the rev.lv.ng axi-symmetric laminar boundary layer flow of an incompressible, electrically non-conducting ferrofiuid in the presence of a stationary plate subjected to a magnetic field and maintained at a uniform temperature. To serv. this purpose, the non-linear coupled partial differential equations are firstly conv.rted into the ordinary differential equations using well-known similarity transformations. The popular finite difference method is employed to discretize the non-linear coupled differ- ential equations. These discretized equations are then solv.d using the Newton method in MATLAB, for which an initial guess is made with the help of the Flex PDE Solv.r. Along with the v.locity profiles, the effects of temperature dependent v.scosity are also examined on the skin friction, the heat transfer, and the boundary layer displacement thickness. The obtained results are presented numerically as well as graphically.

关键词： ferrofluid temperature dependent v.scosity boundary layer axi-symmetry,magnetic field