The type of convergent boundaries forming in the area of mantle plumes is considered. These convergent boundaries (West Pacific type) are characteristic of the western margin of the Pacific. West Pacific-type boundaries are a regular succession of structures from ocean to continent: island arcs, marginal basins, rift basins, and associated OIB-type volcanics at the continental edge. The convergence zones are up to a thousand kilometers wide. Studies of the history of the part of the Central Asian Fold Belt forming the folded periphery of the Siberian continent have shown that the continent drifted above the African plume or corresponding low-velocity mantle province for most of the Phanerozoic (up to the Early Mesozoic inclusive). This fact determined the West Pacific type of convergent boundaries for the accretionary structures of the Central Asian Fold Belt. The drift of Siberia from African to Pacific province in the Late Cenozoic determined the structure and development of the convergent boundary in the western Pacific, including extensive intraplate magmatism in continental Asia in the Late Mesozoic and Cenozoic.
Regional gravity and magnetic anomalies are interpreted with regard to new geodynamic, geological, and tectonic schemes. Integrated analysis of these data confirms the deep origin of the processes which have created the largest igneous areas and zones of the eastern Central Asian Fold Belt.
We consider the evolution of the tectonic setting and geochemical features of rocks in ultrapure quartz areas of the Baikal region. These are the Chuya uplift of the northern Baikal region, with the Tyya quartz deposit, as well as the Bural-Sar’dag and other deposits in the Gargan block of East Sayan. Similarities are observed in the sedimentation and tectonic evolution of the regions. The conditions of the deposition of quartzites (forearc basins within siliceous-carbonate rocks with slight tholeiitic volcanism and a small amount of terrigenous material) ensure their relative initial purity. Low-grade quartzite-bearing strata are bedded or thrust by collision over an older high-grade basement consisting of a tonalite–trondhjemite–granodiorite association (Gargan block) or active-continental-margin metavolcanics (Chuya uplift). Migmatization of the basement and the intrusion of granitoids therein cause its uplifting, fault displacements, and erosion of the overlying rocks. If the thrusting is associated with retrograde metamorphism of the basement and progressive metamorphism of the cover, backward motion can cause only quartz recrystallization with its purification and the grinding of the other minerals. This leads to the formation of lenses of “superquartzites,” mylonites, cataclasites, and breccias in the autochthon–allochthon suture and within the allochthon.
Natural diamonds from the Ural alluvial deposits have been studied by FTIR spectroscopy. It is shown that these diamonds are similar in some typomorphic characteristics, such as nitrogen content and aggregation state, to the diamonds of the Coromandel (Brazil) and Verkhnee Molodo (Lena region, Yakutia) placers and to the diamonds from kimberlites of the Arkhangel’sk Region but differ significantly in lower contents of hydrogen and higher contents of platelets. The high contents of hydrogen (5–20 cm–1) determined in some diamonds due are to the specific formation of their internal structure and to the presence of inclusions. The nonuniform distribution of nitrogen A- and B-centers throughout the crystal testifies to the zonal structure of diamonds. The temperature conditions of the Ural diamonds formation have been estimated.
Gold-bearing ore occurrences and deposits in jasperoids are objects of a new unconventional type widespread in the West Kalba auriferous belt in eastern Kazakhstan. We present original data on the structural and geologic position and mineralogy of gold-bearing jasperoids of the Baybura ore field, which is a standard object of this type in eastern Kazakhstan. Gold-bearing jasperoids are localized here in shale–carbonate strata of island-arc type (C1) that underwent metasomatism in superintrusive zones of the Kunush complex plagiogranites (C3). Free finely dispersed gold shows typical signs of hypogenous changes. The content of Au varies from 0.1 to 33.5 ppm, and that of Ag, from 0.05 to 2.5 ppm. Based on the data obtained, a geologo-genetic model of the formation of the Baybura gold-bearing jasperoids is proposed. According to the model, the ore deposition is related to the impact of juvenile fluids of plagiogranitic magma on carbonate substrate. The main factors determining the evolution of gold-bearing metasomatites are their localization in zones of high tectonic activity and a drastic change in the acidity–alkalinity regime of solutions in the carbonate environment. Native gold grains are extremely fine and thin and contain a permanent impurity of Hg (0.2–0.7 wt.%). In mineralogical and geochemical features the gold mineralization of the Baybura ore field is similar to that of the Suzdal’ deposit and can be assigned to the Carlin type.
Typomorphic features of native gold and its contents in complex Ti–Zr placers in the southern West Siberian Plain are reported. Three of the placers are of littoral-marine genesis, and two formed under conditions of an alluvial piedmont plain. Native gold from the studied Ti–Zr placers occurs mainly as flattened thin (–0.1 mm) particles which underwent mechanical action. It is marked by a wide fineness variation and the abundance of a very fine (990–1000‰) variety. Most likely, this is chemically transformed clastogenic metal. The gold content of the productive bed (5–30 mg/m
3 native gold and 8–140 ppb bulk gold) is consistent with the dispersion of heavy ore and accessory minerals during mechanical migration in water flows simultaneously with their concentration on geochemical barriers. The native-gold content of complex Ti–Zr placers shows a higher negative correlation with the primary source–placer distance than those of Ti and Zr minerals and a positive correlation with the degree of hydrodynamic reworking (gravity concentration) of transit terrigenous material. On the southern framing of the West Siberian Plain, some regions of northern Kazakhstan are promising for gold of complex Ti–Zr placers as well as fine- and thin-gold placers, gold-bearing weathering crusts, and primary gold deposits.
Quaternary sediments from the borehole DBC-1 drilled in the Darhad Basin, northern Mongolia, have been studied by thermomagnetic (248 samples) and probe microanalysis (9 samples) analyses to determine the origin (cosmic or terrestrial) of native iron. Most of the samples showed extremely low contents of native iron. Only 26 samples have iron in contents sufficient for its reliable identification (10–5–10–3 %). The negligible content of native iron in the Darhad Basin sediments distinguishes them from the earlier studied sediments of different geologic associations of Eurasia and the Atlantic, which we explain by the high sedimentation rate in this basin. However, the bimodal distribution of native-iron contents in the samples with a distinct “zero” mode, similar to that in the objects of Eurasia and the Atlantic, testifies to the predominantly cosmic origin of the native iron.
High-performance algorithms and software have been designed for fast 2D forward modeling and inversion of high-frequency electromagnetic logs to recover the patterns of electrical conductivity and relative permittivity (dielectric constant) of rocks. Forward modeling implies linear representation, with regard to eddy current, of attenuations and phase shifts of electromagnetic fields propagating in 2D conducting formations. In order to improve the modeling quality, the background model is chosen proceeding from the eddy current pattern in a heterogeneous subsurface. The inverse solution is obtained by pseudoinversion of the sensitivity matrix of relative amplitudes and phases. Joint 2D inversion of phase shifts and attenuations improves the reliability of the inferred spatial conductivity distribution and allows estimating permittivity. The reported numerical experiments on inversion of synthetic and field EM logs prove the possibility of estimating the permittivity of complex terrigenous and carbonate reservoirs with water- and oil-filled porosity.
The thermal conductivity of rocks (λ) used previously to estimate heat flow in high-latitude Siberia was assumed to be λ = 1.8–2.0 W/(m·K), according to published evidence, but was almost never measured specially. We measured the thermal conductivity of core samples from boreholes drilled in the northeastern West Siberian Plate and in the Yenisei–Khatanga basin in the 1990s, using two advanced instruments: a comparator and a scanner of thermal conductivity. Altogether there were 305 samples of air-dry sediments (λ
d) from the 1100–4200 m interval of 23 holes, 77 samples of which were then moistened (λ
w). The average thermal conductivities of rocks in dry and wet conditions were found to be λ
d = 1.9 ± 0.2 and λ
w = 2.6 ± 0.1 W/(m·K), respectively. Thus, the true thermal conductivity of sediments, which are saturated with water in this northern area, must be about 20–30 % higher than that assumed in the previous heat flow determinations, and the latter are thus underestimated correspondingly. The updates to the thermal conductivity values imply major revision of the existing ideas of the thermal regime in the Siberian high latitudes. Such a serious revision of geothermal data will obviously require a large amount of additional experimental work.
Groundwater is a very important component of water resources in coastal aquifers in Thoothukudi. It has been established that the groundwaters in the coastal zone of the Zirconium Complex, Pazhayakayal, Thoothukudi district, Tamilnadu, India, are subjected to wave and tidal impact. The groundwater quality was studied by hydrogeological methods, 2D electrical resistivity imaging (ERI) techniques (six profiles), 11 Wenner vertical electrical sounding (VES), and well log analysis. Also, nine geochemical water samples were taken from the study area. The 2D ERI and VES surveys were carried out using WGMD-4 Ltd, Chennai, resistivity meter, multicore cable, and multielectrodes with Wenner array. The collected resistivity data were interpreted using the Res2DINV software. The research shows that the groundwaters are the result of the palaeoriver flow along the Tamirabarani Channel in the western area and of the seawater intrusion in the eastern area. The fresh water is characterized by resistivity of about 10–100 Ohm·m in the study area. The resistivity of 10–50 Ohm·m indicates that the subsurface section is made up of sand, clay, and caliche. Resistivity values of more than 200 Ohm·m are specific for sand dunes. The very low resistivity (<5 Ohm·m) layer might be due to the seawater intrusion in the study area. Six water samples from the well drilled in the coastal area were analyzed, which made it possible to determine the concentrations of major and trace elements in the groundwaters. These data were used to establish the seawater intrusion and coastal environment characteristics in the study area.
Equations of rotationally symmetric motion of an ideal incompressible fluid are considered. A class of solutions to these equations, described by a hyperbolic equation of the fourth order with one space variable, for which an initial boundary-value problem is formulated, is distinguished. The new class of exact solutions of the Euler equations was used to describe the a nonstationary cylindrical vortex in an ideal fluid.
The boundary layer flow and mass transfer toward an exponentially stretching porous sheet are analyzed in this paper. Velocity slip is considered instead of the no-slip condition on the boundary. Self-similar equations are obtained by using similarity transformations. Numerical solutions of these equations are obtained by the shooting method. It is found that the fluid velocity and concentration decrease with increasing slip parameter. The fluid velocity decreases with increasing suction parameter.
An exact solution of the problem of hydraulic fracturing in a permeable medium with continuous fluid injection in a partially penetrated formation is constructed using the Perkins–Kern fracture model. The amount of fluid leakage from the fracture is determined using the pressure field of the fluid filtrate defined by the Shchelkachev equation (of the piezoconductivity type). Universal profiles of the fluid pressure in the fracture and the rate of fluid flow from it are obtained. It is shown that at the Perkins–Kern fracture tip, there is a dramatic increase in the leakage from the fracture.
A. I. Filippov, O. V. Akhmetova, I. F. Kabirov
Keywords: heat-conducting medium, steady-state regime, filtration, temperature, averagely accurate asymptotic method
The problem of the temperature field produced by sources whose position does not depend on the vertical coordinate and which are concentrated in a horizontal permeable layer surrounded by a heat-conducting medium with radial steady-state fluid flow. The problem is solved using an averagely accurate asymptotic method. Analytical expressions for the zero-order approximation and the first coefficient of the expansion. A condition is determined under which the averaged problem for the remainder term has a trivial solution.
An analysis is presented to investigate the influence of viscous dissipation on a free convection flow over a vertical cone with a variable surface heat flux under the action of a transverse magnetic field. The heat transfer characteristics of the free convection flow are investigated numerically. Numerical solutions for transformed governing equations with a variable surface heat flux are obtained. Velocity, temperature, local shear stress, and heat transfer coefficients are calculated for various values of the problem parameters and presented in the graphical form. The effects of the magnetic parameter, the dissipation number, the power-law index, the angle between the cone generatrix and the vertical line, and the Prandtl number on the flow are discussed. For validation of the present numerical results, they are compared with available experimental data and are found to agree well.
N. I. Ostrosablin
Keywords: transversely isotropic medium, elasticity moduli, longitudinal normals, general solution, recursion operators, diagonalization of elliptic system
A dynamic three-dimensional system of linear equations in terms of displacements of the theory of elasticity of transversely isotropic media is given explicit expressions for phase velocities and polarization vectors of plane waves. All the longitudinal normals are found. For some values of the elasticity moduli, the system of equations is reduced to a diagonal shape. For static equations, all the conditions of the system ellipticity are determined. Two new representations of displacements through potential functions that satisfy three independent quasi-harmonic equations are given. Constraints on elasticity moludi, at which the corresponding coefficients in these representations are real, different, equal, or complex, are determined. It is shown that these representations are general and complete. Each representation corresponds to a recursion (symmetry) operator, i.e., a formula of production of new solutions.
A method for describing the piezoelectric effect in a polar material is proposed based on the use of a composite particle model with seven degrees of freedom and a nonzero dipole moment. Based on micropolar theory, a system of equations is obtained which differs from the classical theory of piezoelectricity in the presence of additional terms. It is shown that under certain assumptions, the proposed system of equations becomes the classical system but the piezoelectric moduli depend strongly on the spontaneous polarization vector. It is shown that for anisotropic media with different symmetries, the structure of the third-rank piezoelectric tensors obtained using the proposed micropolar theory coincides with the structure of the tensors obtained using classical theory. For the media considered, dispersion relations are given and it is shown that in the proposed theory, unlike classical theory, the piezoelectric moduli are proportional to the spontaneous polarization.
Yu. N. Ovcharenko
Keywords: V-notch, strain energy density, loading schemes of type I and type II, crack propagation direction, local fracture criterion
Conditions of fracture of the local strain energy density, which were first formulated by Sih for a sharp V-notch with an arbitrary tip angle, are proposed. The edges of the considered V-notch are free from loading. If loading schemes of type I and type II are used, it is shown that the known brittle fracture conditions proposed by Sih contradict one of the basic postulates in fracture mechanics: the greater the intensity of stresses or elastic energy near the V-notch tip, the greater the probability of crack propagation. The proposed new conditions of fracture (in a polar coordinate system) are obtained as a result of independent determination of the energy densities of changes in volume and shape. In this case, the above-mentioned contradiction is eliminated.
In the classical model of an ideal rigid–plastic material without hardening, the governing system of equations is a system of hyperbolic type, and, if hardening is taken into account, the type of the system of equations changes from hyperbolic to elliptical. In this case, the correlation between the experimentally observed strain localization lines and the characteristics of the quasilinear system is violated. It is shown that if dilatancy is taken into account, the system of equations remains hyperbolic.
The wave problem of perturbation propagation along an elastic rod interacting with the medium is investigated using the model of viscoplastic friction. An exact solution of the problem is obtained for an arbitrary time of the loading period. Analysis of the results is performed.
A mathematical model for the closure of a crack-like cavity with cohesive end zones in an isotropic medium is constructed using methods of elastic theory. It is assumed that the interaction between the surfaces of the crack-like cavity under the action of body and surface forces can lead to the formation of contact zones on their surfaces. Determination of the unknown parameters characterizing the closure of the crack-like cavity reduces to a system of singular integrodifferential equations. The integral equations are converted to a system of nonlinear algebraic equations which is solved by the method of successive approximations. The contact stresses, the interaction forces between the faces of the crack-like cavity, and the size of the contact zone in which the faces of the crack-like cavities are closed are determined.
I. V. MILETENKO, N. A. MILETENKO, V. N. ODINTSEV
Institute of Comprehensive Exploitation of Mineral Resources, Russian Academy of Sciences, Kryukovskii tupik 4, Moscow, 111020 Russia
Keywords: rock mass, contact jointing, induced dislocation, underground excavations, stress state, theory of percolation filtration, permeability
The authors offer a new approach to modeling a mining-induced dislocation, based on the calculation of nonuniform stress state of rocks, probabilistic assessment of rock mass strength and the laws of the theory of percolation filtration.
L. A. NAZAROV1,2, L. A. NAZAROVA1,2, A. L. KARCHEVSKY3,2, N. A. MIROSHNICHENKO1 1N.A. Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Krasnyi pr. 54, Novosibirsk, 630091 Russia 2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630091 Russia 3S.L. Sobolev Institute of Mathematics, Siberian Branch, Russian Academy of Sciences, Pr. Akademika Koptyuga 4, Novosibirsk 630090, Russia
Keywords: rock mass, producing formation, pressure, inverse problem, geodesy data, motion, objective function
The article describes the procedure of estimating spatial distribution of pressure in a producing formation under mining by the ground surface geodesy survey data. The numerical experiments show that one-valued solvability of the inverse problem requires the ground surface motion to be measured both in vertical and in horizontal directions.
a:2:{s:4:"TEXT";s:47:"D. V. YAKOVLEV, T. I. LAZAREVICH, S. V. TSIREL’";s:4:"TYPE";s:4:"text";}
a:2:{s:4:"TEXT";s:145:"Mining Geomechanics and Surveying Research Institution—Joint Scientific Center VNIMI, 22-ya liniya 3, Build. 3 B, Saint-Petersburg, 199106 Russia";s:4:"TYPE";s:4:"text";}
Keywords: seismic events, earthquakes, open pit mines, mining operations, curves of time of occurrence, deep faults, seismic station network, P-waves and S-waves, geodynamic monitoring
Based on the plotted times of occurrence of seismic events, their timing within a work week and location of epicenters, it is illustrated that since the 1960s the seismicity in the Kuzbass territory is a complicated natural and mining-induced phenomenon. Since the late 1980s, the natural and mining-induced seismicity has entered the second evolution stage, with clustering of low-energy seismic events and high-power shallow earthquakes in the areas under heavy mining and, in the first instance, at deep open pit mines. The representative event of this kind is the magnitude 5.2 earthquake at the Bachatsky Open Pit Coal Mine on June 19, 2013. It has been found that the natural and mining-induced seismic activity is associated with deep faults that weakly show themselves in the upper layer of the earth crust and the local relief, which is an evidence of their live emergence onto the daylight surface due to the mining effect. The article proposes the comprehensive research program for the natural and mining-induced seismic activity in the Kuzbass area and the development of early identification of seismically active zones.
A. P. BOBRYAKOV
N.A. Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Krasnyi pr. 54, Novosibirsk, 630091 Russia
Keywords: shear, trigger effects, soft loading, faults, friction, slipping
The laboratory modeling of unsteady deformation at interface of a faulting zone, aimed at studying motions over rigid surfaces with an in-between interlayer of pre-stressed granular medium now exposed to trigger destressing, has shown that relationship of the force drop and displacement of rigid boundaries under the trigger destressing is linear. The slope of straight lines characterizes the resultant rigidity of the system and depends on the set of the input parameters: the spring simulating elasticity of fault surfaces; the granular medium simulating the faulting contact friction; the short-term friction drop trigger. It is found that soft loading takes much energy and results in lower force drop but higher displacements under destressing. The author illustrates that the destressing of the granular medium pre-set in the limit state is accompanied with displacement discontinuities at the rigid boundaries and partial drop of the shearing force.
Starting from the colour change upon co-milling a white mixture comprising a metal oxide (MO) and organic solids (OS) with F or N, general features of the mechanochemical reactions at the boundaries between MO and OS were observed, characterized and discussed with the presence of various analytical results. Three parallel streams of the mechanochemical reactions upon co-milling are confirmed, i. e., i) an oxidative decomposition of the organic species, ii) formation of nanostructured carbon, and iii) incorporation of non-oxygen anionic species into oxides via a ligand exchange. In the case of wet milling, complex ion formation in a liquid phase is sandwiched. Case studies were focused on TiO2 as MO and polytetrafluoroethylene (PTFE) or glycine (Gly) as OS.
P. BILLIK1,2, M. GURTH2 and T. TURANYI3 1Faculty of Natural Sciences, Comenius University, Mlynska Dolina, SK-842 15 Bratislava (Slovakia)
E-mail: billik@fns.uniba.sk 2Institute of Measurement Science, Slovak Academy of Sciences, Dubravska cesta 9, 841 04 Bratislava (Slovakia) 3Kadaň Ltd., Lapaška
cesta 458, 951 02 Pohranice (Slovakia)
Keywords: nutation, mechanochemical synthesis, TiO2, powders
Pages: 529–533
Mechanochemical synthesis of TiO2 by using the simple laboratory scale nutating centrifugal ball mill was demonstrated for the first time. In our prototype, the nutation angle in the range of 0–20 deg, besides the speed of rotation of central axes up to 1400 rpm, can be adjusted independently. In order to compare the milling efficiency between Nutator and high-energy planetary ball mill TB-2, the soft mechanochemical reaction between TiOSO4 ⋅ 2H2O and Na2CO3 has been studied. In the case of nutating mill the intensity of diffractions corresponding to TiOSO4 ⋅ 2H2O and Na2CO3 completely disappeared after 5 min milling. In case of the planetary ball mill TB-2, due to the large difference in the centrifugal forces (60gvs 20g), mechanochemical treatment for 1 min leads to similar results and after 10 min, the sample contains mainly rutile TiO2 with trace of TiO2-II.
G. CAGNETTA1, G. INTINI1, L. LIBERTI1, O. I. LOMOVSKY2 and V. V. BOLDYREV2 1Department of Civil, Environmental, Building Engineering and Chemistry, Technical University of Bari, 70123 Bari (Italy)
E-mail: g.cagnetta@gmail.com 2Institute of Solid State Chemistry and Mechanochemistry, Ul. Kutateladze 18, Novosibirsk 630128 (Russia)
Keywords: PAHs, marine sediment, mechanochemical treatment, biological treatment
Pages: 535–543
BIOMEC, a new two-stage process based on a short mechanochemical (MC) pre-treatment followed by biological treatment with purposely selected bacteria (Novosphingobium pentaromativorans), was investigated to detoxify Taranto’s harbour (S. Italy) marine sediments contaminated by polycyclic aromatic hydrocarbons (PAHs) and classified as hazardous waste, according the Italian law (Legislative Decree 152/2006). The experimental results, aimed at determining the overall efficiency of the BIOMEC treatment, indicated that PAHs degradation may be achieved in a very effective (97 %) and fast (<14 days) manner, yielding a non-toxic waste largely reusable as building material. In particular the MC pre-treatment allowed bigger degradation of high MW PAHs; because of their larger aromatic structure, after collisions between sediment particles and milling bodies these congeners may generate more stable free radicals with respect to low MW ones and the probability of their formation is higher, hence they are MC degraded to larger extent. GC-MS analysis of MC degradation products of benzo(a)pyrene (BaP), spiked on clean sediment (taken from Taranto’s harbour too), suggest that the first probable step is an almost complete destruction of BaP rings and the formation of oxidized heavy molecules with residual aromaticity. Then the breakdown of this kind of compounds and the formation of small radicals give origin to many volatile organic molecules which, through an accretion process, form heavier compounds up to graphitization.
J. LANG1, N. SKRYABINA2, D. FRUCHART3, M. DANAIE4 and J. HUOT1
a:2:{s:4:"TEXT";s:438:"1Chemistry and Physics Department, Universitй du Quйbec а Trois-Riviиres, 3351 des Forges, Trois-Riviиres, Quйbec, G9A 5H7 (Canada)
2Department of Physics, Perm State University, Ul. Bukireva 15, Perm 614990 (Russia)
3Institut Nйel BP 166, 38042 Grenoble Cedex 9 (France)
It has recently been shown that Severe Plastic Deformation (SPD), and particularly cold rolling, techniques could be used to obtain nanostructured metal hydrides with enhanced hydrogen sorption properties. Cold rolling is a particularly interesting technique because it is easily scalable to industrial level. We present here the effect of cold rolling on hydrogen storage properties of magnesium and magnesium hydride (MgH2). Commercial magnesium and magnesium hydride were processed in a vertical cold rolling apparatus. For pure magnesium, a highly textured material was obtained after only one roll and first hydrogenation was faster than unprocessed magnesium. In the case of magnesium hydride, after only five rolling passes hydrogen sorption kinetics at 623 K were greatly enhanced without noticeable loss of capacity. The improvement in sorption kinetics is attributed due to the nanocrystalline structure and number of created defects. Investigation of the powder morphology and crystal structure indicates that cold rolling is equivalent to ball milling.
M. SH. AKCHURIN, R. M. ZAKALYUKIN and A. A. KAMINSKY
Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky Pr. 59, Moscow 119333 (Russia)
E-mail: akchurin@ns.crys.ras.ru
Keywords: plastic deformation, twinning, mechanosynthesis, solid-state reactions
Pages: 553–559
A new mechanism of solid-state reactions, based on a mass transfer process due to the plastic deformation is proposed. By the example of the nucleation in the course of the mechanosynthesis of complex oxides, there has been demonstrated a role of twinning processes in the nucleation of spinel (MgAl2O4), lead titanate (PbTiO3) and yttrium-aluminum garnet (Y3Al5O12) under grinding the powders of MgO + Al2O3, TiO2 + PbO and Al2O3 + Y2O3, respectively. It has been proposed that the mechanical twinning is the main mechanism of mechanochemical solid-state reactions.
A. S. ARTEMOV
Prokhorov Institute of General Physics, Russian Academy of Sciences, Ul. Vavilova, 38, Moscow 119991 (Russia)
E-mail: artpoliofan@mail.ru
Keywords: chemical and mechanical polishing, amorphous SiO2 particles, polishers, single crystals, mechanochemical activation
Pages: 561–568
Interpretation of the mechanochemical aspect from the viewpoint of the manifestation of P. A. Rebin-der effect is proposed on the basis of the experimental investigation of the kinetics and mechanism of the processes taking place during chemical mechanical polishing semiconductors, dielectric and metal crystals. The possibility of the tribochemical activation of chemical reactions by the flow of liquid silica sols under the joint action of chemical mechanical factors on the surface is demonstrated. It is established that solid particles promote activation and localization of chemical reactions on the surface of crystals on the atomic scale, and removal of the products of chemical reactions in the nanoscale. As a result, a mirror-smooth surface with subnanosecond relief is formed; containing no micro and nano scratches, pits, etched regions and other microdefects.
A. A. GUSEV1, I. P. RAEVSKY2, E. G. AVVAKUMOV1 and V. P. ISUPOV1 1Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Ul. Kutateladze 18, Novosibirsk 630128 (Russia)
E-mail: gusev@solid.nsc.ru 2Research Institute of Physics, Southern Federal University,
Pr. Stachki 194, Rostov-na-Donu 344090 (Russia)
E-mail: igorraevsky@gmail.com
Keywords: lead ferroniobate, thermal synthesis from iron, niobium and lead oxides using mechanical activation
Pages: 569–575
The synthesis of lead ferroniobate from lead, iron and niobium oxides taken in the stoichiometric ratio was investigated for the purpose of choosing the optimal compositions, conditions of mechanical activation and subsequent thermal treatment. The process was carried out in the presence of the excess of lead oxide to prevent the deviation from the stoichiometry of the ceramics obtained after sintering. The changes of the phase composition of mixtures during mechanical activation and subsequent thermal treatment were followed. It was demonstrated that the most attractive structure and properties are those characterizing lead niobate obtained with some excess of lead oxide over the stoichiometric composition. It was established that with the help of mechanical activation it is possible to vary within a broad range the temperature of the magnetic phase transition for the powders and ceramics of lead ferroniobate.
T. S. DEMINA1, L. V. VLADIMIROV2, T. A. AKOPOVA1 and A. N. ZELENETSKY1 1Enikolopov Institute of Synthetic Polymer Materials, Russian Academy of Sciences, Ul. Profsoyuznaya 79, Moscow 117393 (Russia) E-mail: detans@gmail.com 2Semenov Institutes of Chemical Physics, Russian Academy of Sciences, Ul. Kosygina 4, Moscow 119991(Russia)
Keywords: solid-phase synthesis, chitosan, lactide, grafted copolymers, biocompatible materials
Pages: 577–583
With the use of solid-phase synthesis in an extruder, chitosan and L,D-lactide grafted copolymers were obtained. A mechanism of graft polymerization was proposed, an effect of process conditions exerted on the yield and structure of the target products was studied. Based on the data obtained from fractionation, IR spectroscopy and study of the elemental composition of the fractions, a substitution level has been calculated for the chitosan amino groups that were 0.19–0.41. An average polymerization level for lactide in grafted chains and an effect exerted by the grafting on the solubility of chitosan and physico mechanical characteristics of film materials were determined. Based on the copolymers synthesized, three-dimensional matrices have been obtained for tissue engineering (macroporous hydrogels, spherical microparticles), as well as compatibility and biodegradation rate have been estimated for the materials.
M. A. EREMINA, S. F. LOMAEVA, E. P. ELSUKOV, A. L. ULYANOV and A. A. CHULKINA
Physical-Technical Institute, Ural Branch of the Russian Academy of Sciences, Ul. Kirova 132, Izhevsk 426000 (Russia)
E-mail: mrere@mail.ru
Keywords: mechanical alloying, nanocomposites, copper, cementite
Pages: 585–592
Features of the formation of macro and microstructural state and the phase composition of Cu–30 vol. % Fe3C nanocomposites obtained by mechanical alloying of copper and iron powders in the liquid source of carbon (xylene) followed by thermal treatment were studied by means of X-ray phase analysis, Mцssbauer spectroscopy, scanning electron and optical microscopy, measurement of dynamic magnetic susceptibility. It was demonstrated that iron carbides are not formed during alloying; however, for the alloys obtained by grinding for 96 h, annealing at a temperature above 500 °С leads to the formation of cementite with the volume fraction of about 30 %. The grain size of the copper matrix of this composite is 10 nm, while after annealing at 800 °С it is 30 nm.
A. M. KALINKIN1, T. C. ALEX2, S. K. NATH2, B. I. GUREVICH1, E. V. KALINKINA1, V. V. TYUKAVKINA1 and SANJAY KUMAR2 1Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials, Kola Science Centre of the Russian Academy of Sciences, Ul. Fersmana 26A, Murmansk Region, Apatity 184209 (Russia) E-mail: kalinkin@chemy.kolasc.net.ru 2CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)
Keywords: Zn slag, Cu–Ni slag, geopolymerisation, mechanical activation, carbon dioxide, reactivity, compressive strength
Pages: 593–601
Geopolymerisation behaviour of Imperial Smelting Furnace (ISF) Zn slag and granulated Cu–Ni slag, mechanically activated in air and in CO2 atmosphere (P = 105 Pa) has been studied by XRD, SEM, FTIR, and isothermal conduction calorimetry. Mechanical activation of the slags has been carried out in a centrifugal-planetary mill AGO-2. Geopolymer samples have been prepared by mixing of the mechanically activated slag powders with NaOH solution or liquid glass and curing at (20±2) oC for up to 180 days. It has been observed that the ISF Zn slag and the granulated Cu–Ni slag are suitable for the synthesis of building materials through geopolymerisation. The effect of milling atmosphere on properties of geopolymers is found to be alkaline reagent specific. A suitable combination of the milling atmosphere and alkaline reagent is required to realize the beneficial effect on mechanical properties of the geopolymer.
G. R. KARAGEDOV1, S. S. KOSOLOBOV2, A. V. LATYSHEV2, N. Z. LYAKHOV1 and A. L. MYZ1 1Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Ul. Kutateladze 18, Novosibirsk 630128 (Russia) E-mail: garik@solid.nsc.ru 2Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Pr. Akademika Lavrentyeva 13, Novosibirsk 630090 (Russia)
Keywords: aluminium oxide, nanopowder, synthesis, mechanochemistry
Pages: 603–608
The introduction of α-Al2O3 nanoparticles into the gel formed during the hydrolysis of aluminium nitrate causes a substantial decrease in the temperature of its transition tino thermodynamically stable modification. The higher is the concentration of seeding within the range 0.2–5 mass %, the lower is the temperature of the formation of monophase α-Al2O3. At the sme time, the temperature of phase transition into the α-modification depends on the method of introduction of the seeding into the gel. This may be connected with nonuniform distribution of nanoparticles over its volume. The use of deionized water as a solvent instead of distilled water allows decreasing the temperature of α-Al2O3 formation to 500 °C. Due to the low temperature of the formation of a-phase (<950 °C), the product consists of easily destroyable granules formed by nanoparticles 45–60 nm in size. Nevertheless, the samples formed from powders with close size demonstrate different sintering ability during low-temperature annealing in the air (1300 °C). Their densities vary within the range 67–97 % of the theoretically possible value. This is likely to be connected with the fact that separate particles in granules get grown together under unfavourable conditions.
S. A. KUZNETSOVA1,2, YU. N. MALYAR1, T. P. SHAKHTSHNEIDER3,4, M. A. MIKHAILENKO3, V. A. DREBUSCHAK4,5 and V. V. BOLDYREV3,4 1Institute of Chemistry and Chemical Technology, Siberian Branch of the Russian Academy of Sciences, Ul. K. Marksa 42, Krasnoyarsk 660049 (Russia) E-mail: ksa@icct.ru 2Siberian Federal University, Pr. Svobodny 79, Krasnoyarsk 664041 (Russia) 3Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Ul. Kutateladze 18, Novosibirsk 630128 (Russia) 4Novosibirsk State University, Ul. Pirogova 2, Novosibirsk 630090 (Russia) 5Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Pr. Akademika Koptyuga 3, Novosibirsk 630090 (Russia)
Keywords: betulin diacetate, betulin dipropionate, arabinogalactan, mechanochemical treatment, dissolution, gel-permeation chromatography
Pages: 609–614
Mechanically activated composites of betulin diacetate and dipropionate with water-soluble natural polysaccharide arabinogalactan were obtained. It was established that the composites are characterized by increased concentration of betulin diacyls during their dissolution in water. The formation of molecular complexes of betulin diacetate and dipropionate with arabinogalactan during mechanical activation and during the dissolution of initial and mechanically activated mixtures in water was assumed. The complexes of betulin diacyls with arabinogalactan were also obtained in the form of thin films, readily soluble in water.
E. F. SUTORMINA, L. A. ISUPOVA, A. A. MARCHUK, A. V. KUZNETSOVA and V. A. ROGOV
Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Pr. Akademika Lavrentyeva 5, Novosibirsk 630090 (Russia) E-mail: selena@catalysis.ru
Keywords: substituted cordierite, mechanical activation, ammonia oxidation
Pages: 615–620
An effect of different mechanical activation conditions (different activator types) on the phase composition, texture characteristics of catalysts based on manganese-substituted cordierite ceramics, as well as the activity thereof in the reaction of ammonia oxidation was studied. It is demonstrated that it is preferable to use an energy-intensive planetary ball mill with a high power density, since it provides the preparation of smaller particles. The finely crystallized manganese cordierite with a minor impurities content, low specific surface, low pore volume and a high activity in the reaction of ammonia oxidation is obtained at their subsequent sintering.
O. G. TEREKHOVA1, A. A. MAGAEVA1 and E. P. NAIDEN1,2 1Department of Structural Macrokinetics, Tomsk Scientific Centre, Siberia Branch of the Russian Academy of Sciences, Pr. Akademicheskiy 10/4, Tomsk 634021 (Russia) E-mail: terog@dsm.tsc.ru 2Tomsk State University, Pr. Lenina 36, Tomsk 634050 (Russia)
Keywords: oxide nanoferrimagnetics, mechanochemical synthesis, adsorption onto nanoparticles, magnetofection
Pages: 621–628
A method is presented for producing nanosized oxide ferromagnetics from salt systems with the use of the mechanochemical activation and their fundamental properties are investigated. Results concerning the use of the oxide ferrimagnetics synthesized for the magnetofection of DNA, DNA/RNA sorption, microbial cells, proteins, and contrast agents for MRT diagnostics are reported. It has been found that nanoparticles are non-toxic; their distribution in internal organs and the decrease dynamics, the possibility of using them for medication transport have been demonstrated.
T. A. FEDUSCHAK1, M. A. UYMIN2, A. E. ERMAKOV2, A. S. AKIMOV1, N. N. SCHEGOLEVA2, T. V. PETRENKO1, S. P. ZHURAVKOV3 and A. V. VOSMERIKOV1 1Institute of Petroleum Chemistry, Siberian Branch of the Russian Academy of Sciences, Pr. Akademicheskiy 4, Tomsk 634021 (Russia) E-mail: taina@ipc.tsc.ru 2Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Ul. S. Kovalevskoy 18, Yekaterinburg 620990 (Russia) 3Tomsk Polytechnic University, Pr. Lenina 30, Tomsk 634050 (Russia)
Keywords: mechanical activation, hydrorefining, sulphide catalysts, model reaction, hydrodesulphurisation of dibenzothiophene
Pages: 629–633
For the first time, an approach to a single-stage manufacture of bulky sulphide catalysts using a solid-phase method performed by means of the mechanical activation of a mixture consisting of coarse molybdenum disulphide and cobalt powders, in the presence of detonation nanodiamonds is described. An effect exerted by the mechanical treatment duration, ratio between the initial components and nanodiamonds on the process of nanofragmentation of molybdenum disulphide and activity of catalytic systems obtained in the model reaction of DBT hydrodesulphurisation has been studied.
