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Search Results: 1 - 10 of 586558 matches for " A. N. Azarevich "
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Hall effect in the vicinity of quantum critical point in Tm1-xYbxB12
N. E. Sluchanko,A. N. Azarevich,A. V. Bogach,V. V. Glushkov,S. V. Demishev,A. V. Levchenko,V. B. Filipov,N. Yu. Shitsevalova,J. Stankiewicz,V. V. Moshchalkov
Physics , 2011, DOI: 10.1134/S1063776112090130
Abstract: The angular, temperature and magnetic field dependences of Hall resistance roH for the rare-earth dodecaboride solid solutions Tm1-xYbxB12 have been studied in a wide vicinity of the quantum critical point (QCP) xC~0.3. The measurements performed in the temperature range 1.9-300 K on high quality single crystals allowed to find out for the first time in these fcc compounds both an appearance of the second harmonic contribution in ro2H at QCP and its enhancement under the Tm to ytterbium substitution and/or with increase of external magnetic field. When the Yb concentration x increases a negative maximum of a significant amplitude was shown to appear on the temperature dependences of Hall coefficient RH(T) for the Tm1-xYbxB12 compounds. Moreover, a complicated activation type behavior of the Hall coefficient is observed at intermediate temperatures for x>0.5 with activation energies Eg~200K and Ea~55-75K in combination with the sign inversion of RH(T) at low temperatures in the coherent regime. The density of states renormalization effects are analyzed within the variation of Yb concentration and the features of the charge transport in various regimes (charge gap formation, intra-gap manybody resonance and coherent regime) are discussed in detail in Tm1-xYbxB12 solid solutions.
Charge transport in Ho$_x$Lu$_{1-x}$B$_{12}$: Separating Positive and Negative Magnetoresistance in Metals with Magnetic Ions
N. E. Sluchanko,A. L. Khoroshilov,M. A. Anisimov,A. N. Azarevich,A. V. Bogach,V. V. Glushkov,S. V. Demishev,V. N. Krasnorussky,V. V. Voronov,N. Yu. Shitsevalova,V. B. Filippov,A. V. Levchenko,G. Pristas,S. Gabani,K. Flachbart
Physics , 2014, DOI: 10.1103/PhysRevB.91.235104
Abstract: The magnetoresistance (MR) $\Delta \rho/\rho$ of cage-glass compound Ho$_x$Lu$_{1-x}$B$_{12}$ with various concentration of magnetic holmium ions ($x$$\leq$0.5) has been studied in detail concurrently with magnetization M(T) and Hall effect investigations on high quality single crystals at temperatures 1.9-120 K and in magnetic field up to 80 kOe. The undertaken analysis of $\Delta\rho/\rho$ allows us to conclude that the large negative magnetoresistance (nMR) observed in vicinity of Neel temperature is caused by scattering of charge carriers on magnetic clusters of Ho$^{3+}$ ions, and that these nanosize regions with AF exchange inside may be considered as short range order AF domains. It was shown that the Yosida relation $-\Delta \rho/\rho$$\sim$$M^2$ provides an adequate description of the nMR effect for the case of Langevin type behavior of magnetization. Moreover, a reduction of Ho-ion effective magnetic moments in the range 3-9$\mu_B$ was found to develop both with temperature lowering and under the increase of holmium content. A phenomenological description of the large positive quadratic contribution $\Delta \rho/\rho$$\sim$$\mu_D^2 H^2$ which dominates in Ho$_x$Lu$_{1-x}$B$_{12}$ in the intermediate temperature range 20-120 K allows to estimate the drift mobility exponential changes $\mu_D$$\sim$$T^{-a}$ with $a$=1.3-1.6 depending on Ho concentration. An even more comprehensive behavior of magnetoresistance has been found in the AF state of Ho$_x$Lu$_{1-x}$B$_{12}$ where an additional linear positive component was observed and attributed to charge carriers scattering on the spin density wave (SDW). High precision measurements of $\Delta\rho/\rho=f(H,T)$ have allowed us also to reconstruct the magnetic H-T phase diagram of Ho$_{0.5}$Lu$_{0.5}$B$_{12}$ and to resolve its magnetic structure as a superposition of 4f (based on localized moments) and 5d (based on SDW) components.
Suppression of Superconductivity in Lu$_x$Zr$_{1-x}$B$_{12}$ : Evidence of Static Magnetic Moments Induced by Non-Magnetic Impurities
N. E. Sluchanko,A. N. Azarevich,M. A. Anisimov,A. V. Bogach,S. Yu. Gavrilkin,V. V. Glushkov,S. V. Demishev,A. L. Khoroshilov,A. V. Dukhnenko,K. V. Mitsen,N. Yu. Shitsevalova,V. B. Filippov,V. V. Voronov,K. Flachbart
Physics , 2015,
Abstract: Based on low temperature resistivity, heat capacity and magnetization investigations we show that the unusually strong suppression of superconductivity in Lu$_x$Zr$_{1-x}$B$_{12}$ BSC-type superconductors in the range $x$$<$0.08 is caused by the emergence of static spin polarization in the vicinity of non-magnetic lutetium impurities. The analysis of received results points to a formation of static magnetic moments with $\mu_{eff}$$\approx$$3\mu_B$ per Lu-ion. The size of these spin polarized nanodomains was estimated to be about 5 ${\AA}$.
Nuevas metodologías aplicadas al estudio de secuencias sedimentarias de plataforma en el basamento Ediacarano-Cámbrico inferior del NO argentino (Formación Puncoviscana)
López de Azarevich,Vanina L.; Azarevich,Miguel B.; Omarini,Ricardo H.;
Serie correlaci?3n geol?3gica , 2010,
Abstract: new methodologies applied to the study of clastic rhythmic sequences of tidal origin in the puncoviscana formation provide a new conception on the paleoenvironments of the basin and constitute a key for the comprehension of paleoastronomic parameters that affected tides at the ediacaran-cambrian boundary in nw argentina. application of fast fourier transforms to lamina thickness variations in tidal rhythmites was developed in last 25 years in old and modern rocks, and implemented in argentina since 2008 in the ediacaran-early cambrian puncoviscana formation. this methodology allows recognition of lunar cycles (synodic, anomalistic, tropical) from patterns obtained in period versus power spectral density graphics, and how these periodic component infuenced in the tidal record. also, this method can be used for calculate the earth-moon distance for time of deposition. so the estimation of lunar retreat rate has been calculated as 7.31 cm/year for the period 620-523 ma and 2.70 cm/years for 523-305 ma.
Estructuras microbiales y algales de zona fótica en la Formación Puncoviscana, provincia de Salta, Argentina
López de Azarevich,Vanina L.; Ace?olaza,Florencio G.; Azarevich,Miguel B.; Omarini,Ricardo H.;
Serie correlaci?3n geol?3gica , 2010,
Abstract: a stratigraphic profle has been described in the puncoviscana formation in palermo oeste locality, salta, were a 63 m-thick sequence was recognized. in the basal section was recognized the presence of microbial and algal structures. lithofacies associations allow interpretation of the sedimentary sequence as tidal fat deposits, within which the biogenic activity had an important roll along the whole registered sedimentation period. recognized sub-environments are shoreface and intertidal. the identifed fossil material consist of: i) diverse trace fossils indicating nereites saltensis biofacies, ii) kinneya, that suggests a development beneath microbial mats, iii) "elephant skin", which development is produced on the surface of microbial mats, iv) algal structures similar to phaeophycaceae, "fucus" group, v) "wrinkle marks", possible associated to mixed biologic and physical process (organic/sedimentary). the recognized group of algae is developed in litoral intertidal to sublitoral zone within the photic zone, and are characteristic of warm to cold relative transparent waters. phaeophycaceae algas has been recognized in all seas around the world and its chronological register varies between the final ediacara and the phanerozoic.
Ritmitas mareales en la formación puncoviscana (S.L.) en la localidad de Rancagua, Noroeste Argentino: Dinámica mareal y consideraciones paleoastronómicas Tidal rhythmites in the Puncoviscana Formation (s.l.) at Rancagua locality, Northwestern Argentina: tidal dynamics and paleoastronomic considerations
Vanina L López de Azarevich,Ricardo H Omarini,Ricardo J Sureda,Miguel B Azarevich
Revista de la Asociación Geológica Argentina , 2010,
Abstract: Las ritmitas mareales constituyen una clara evidencia de sedimentación afectada por las mareas pudiendo preservar los períodos mareales inducidos astronómicamente al momento del depósito. Las investigaciones de secuencias periódicas mareales, acrecionadas vertical o lateralmente, en unidades modernas y antiguas, han experimentado notables avances en los últimos 25 a os, excepto en la transición Neoproterozoico-eocámbrico. La Formación Puncoviscana (NO argentino) está compuesta en la localidad de Rancagua por litofacies de cara de playa hasta plataforma distal, la cual incluye ritmitas mareales de edad neo-proterozoico- cámbrica temprana. Los períodos lunares involucrados en la sedimentación pueden ser aproximados mediante análisis armónicos con transformadas rápidas de Fourier a partir de datos crudos de espesores de láminas. Un sistema semidiurno con períodos tropicales de 26,64 días fue reconocido, a partir del cual se calculó la distancia Tierra-Luna en 3,78 x1010 cm. Estos resultados proporcionan información relevante acerca de la evolución de la órbita lunar a través del tiempo geológico. Los datos sugieren un evento astrofísico singular e irrepetible durante la transición Paleo-Mesoproterozoico con incremento en la velocidad de alejamiento hasta el Cámbrico Temprano, con eventos menores discretos en el Cámbrico Temprano y Paleozoico Superior con disminución del 50% de la velocidad de alejamiento. Tidal rhythmites are clear evidence of sedimentation affected by tides and could preserve tidal periods astronomically induced during the time of deposition. Investigations of tidal periodic sequences lateral or vertically accreted on modern and ancient units had improved notable advances during the last 25 years, but, there are no data on the Neoproterozoic-Early Cambrian transition. The Puncoviscana Formation (NW Argentina) at Rancagua locality is composed by shoreface to offshore lithofacies, which includes tidal rhythmites of Neoproterozoic-Early Cambrian age. Lunar periods involved in sedimentation by tides can be approach by harmonic analysis carried out with fast Fourier transforms from raw data on lamina thickness. A semidiurnal tidal system with tropical periods of 26.64 days was obtained, from which Earth-Moon distance was calculated as 3.78 x1010 cm. These results provide relevant information about the evolution of the lunar orbit through geological time. Results suggest an astrophysical event of singular characteristics during the Paleo-Mesoproterozoic transition with an increment in retreat velocity up to Early Cambrian, with minor discreet e
Nuevos aportes isotópicos para secuencias carbonáticas del Precámbrico superior (Formación Las Tienditas) del NO de Argentina: su implicancia en la evolución de la Cuenca Puncoviscana
López de Azarevich,Vanina L.; Omarini,Ricardo H.; Santos,Roberto V.; Azarevich,Miguel B.; Sureda,Ricardo J.;
Serie correlaci?3n geol?3gica , 2010,
Abstract: the puncoviscana basin registers four geodynamic episodes: a) initial rifting related to breakup of rodinia (800-750 ma), b) passive continental margin: formation of puncoviscana sea and volcan carbonates (750-580 ma), (c) active continental margin: development of tilcarian magmatic arch and las tienditas-tumbaya carbonates (580-550 ma), (d) collision of arequipa-belén- antofalla terrane: tilcarian orogeny with granitoids emplacement (550-525 ma). changing paleogeographic configuration and installation of new oceanic realm during the neoproterozoic generate differences in nutrient distribution together with ice blocks transfer from the poles to equator. this process was related to restricted glacial sequences associated with neoproterozoic cap carbonates, and wide variation of 13 c distribution in sea water that reflects high differences in isotopic curves. although evolution of d18o and d13c in las tienditas formation gives information about a post-gaskier or varanger deposition and paleoenvironmental conditions, detection of the precambiran-cambrian boundary is not so clear. analysis suggests isotopic fractionation in the ocean-atmosphere boundary with fluctuations in nutrient supply, with d13c variation according to biologic productivity in the platform. negative excursion of d13c to -2,16 ‰ pbd is associated with anoxic 13 c-depleted currents. together with terrigenous material supply that produces an increment in the 87sr/86sr isotopic ratio.
Dynamic Changes in Lipid Peroxidation and Antioxidant Level in Rat’s Tissues with Macrovipera lebetina obtusa and Montivipera raddei Venom Intoxication  [PDF]
N. A. Zaqaryan, N. A. Ghazaryan, N. M. Ayvazyan
Journal of Biophysical Chemistry (JBPC) , 2014, DOI: 10.4236/jbpc.2014.54017
Abstract: We investigated the balance of free radicals in different tissues (liver, heart, brain and muscle) of rats in course of in vivo and in vitro processing by Macrovipera lebetina obtusa (MLO) and Montivipera raddei (MR) snake venoms. Chemiluminescence (ChL) levels were examined in tissue assays after incubation (at 37 °C for a period of 10 min) with venom for in vitro experiments and in tissue assays isolated of 10 min after venom injection for in vivo experiments. The TBA-test was also performed to confirm the free radical expression. The activities of antioxidant enzymes (such as superoxide dismutase and glutathione peroxidase) in isolated tissues were detected by spectro-photometry. During the in vitro processing chemiluminescence levels of tissue homogenates significantly decreased, while in course of in vivo intoxication the level of ChL was elevated in brain and liver; lipid peroxidation also increased in brain tissue, but there was no significant balance change in other tissues; the activity of superoxide dismutase mainly correlated with changes of free radical balance during intoxication. On the contrary, the activity of glutathione peroxidase showed the reverse tendencies to change. We suggest that free radicals and their oxidative stresses may play a role in the early stage of intoxication causing the so-named “spreading-effect”, which is very characteristic for the venom of vipers.
Review of the Book “Causality and Reversibility in Irreversible Time”  [PDF]
A. N. Morozov
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.33029
Abstract: The book concerns a number of the most fundamental concepts and problems of modern physics: causality, entanglement and the nature of time. A distinguishing feature of author’s approach is equal attention to both the theoretical and experimental challenges posed by those issues. From very beginning, in Introduction the author points out Kozyrev causal mechanics, suggested about fifty years ago, as an inspirable source of ideas devel-oped him at the modern level of rigor.
Evolving Green Aviation Transport System: A Hoilistic Approah to Sustainable Green Market Development  [PDF]
A. N. Sarkar
American Journal of Climate Change (AJCC) , 2012, DOI: 10.4236/ajcc.2012.13014
Abstract: Aviation is one of the fastest growing industries as well as transportation modes in the world. Global aviation contributes about 2% of global greenhouse gas emissions and supports 8% of the world economic activity in terms of GDP. With the phenomenal growth in air trafficking by the national and international airliners the total carbon space available for flying is getting progressively diminished and the consequential emission levels are also becoming alarming over passage of time. The paper describes the concept of evolution of Green Transport system with focus on manufacturing of green aircraft and sustainable green marketing involving green supply chain. This entails introduction of New and innovative technologies, including aircraft designing, improving operational efficiency, air traffic control & monitoring etc; combined with emission mitigation efforts towards sustainable growth of the industry, can make enormous improvements in emission control and reduction in a planned and system-based manner. These integrated approaches are proposed to be used to harmonize the systems and processes that can essentially constitute the suggested framework of the Green Aviation Transport system. The paper, inter alia, discusses various conceptual, strategic, technological and economic and environmental dimensions of the Green Aviation transport system with focus on creating new Green Marketing opportunities for the aviation industry in future.
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