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1,074 results on '"Nikolaev, E."'

9. Activated hopping transport in nematic conducting aerogel at low temperatures

Author

Tsebro, V. I., Nikolaev, E. G., Lugansky, L. B., Kutuzov, M. S., Khmel'nitskii, R. A., Tonkikh, A. A., and Khar'kovskii, A. I.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

The transport properties of nematic aerogels, which consist of highly oriented Al$_2$O$_3\cdot$SiO$_2$ nanofibers coated with a graphene shell with a large number of defects, are studied. The temperature dependences of the electrical resistivity in the range of 9-40K strictly follow the formula derived to describe the variable range hopping (VRH) conductivity, in which exponent $\alpha$ changes from 0.4 to 0.9 when the number of layers in the graphene shell decreases from 4-6 to 1-2. The dependence of $\alpha$ on the shell thickness can be explained by a simultaneous change in the dimensionality of hopping transport and the character of the energy dependence of the density of localized states near the Fermi level. The fact that $\alpha$ approaches unity at the minimum graphene shell thickness indicates a gradual transition from VRH transport to nearest neighbor hopping (NNH) transport. The magnetoresistance measured at T = 4.2 K is negative, increases significantly with decreasing graphene shell thickness, and is approximated by a formula for the case of weak localization with a good accuracy. The phase coherence lengths are in a reasonable relation with the graphene grain sizes. The conducting aerogels under study complement the well-known set of materials that exhibit hopping electron transport at low temperatures, which is characteristic of media with strong carrier localization, and also a negative magnetoresistance, which usually manifests itself under weak localization conditions., Comment: 15 pages, 11 figures, 4 tables

Published
2022
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29. Local Diamagnetic Susceptibility of Quasi-Two-Dimensional Graphite

Author

Nikolaev, E. G., Kotosonov, A. S., Shalashugina, E. A., Troyanovskii, A. M., and Tsebro, and V. I.

Subjects
Condensed Matter - Materials Science
Abstract

A sample of quasi-two-dimensional graphite (QTDG) whose magnetic properties are described within the Dirac fermion model is investigated by the nuclear magnetic resonance (NMR) and scanning tunneling microscopy (STM) techniques. The broad spectrum of the sample points to a large dispersion of crystallite sizes in this system, which is also confirmed by STM data. It is established that the local diamagnetic susceptibility may substantially exceed the average value over the sample and reaches an abnormally high value of $-1.3\times 10^{-4}$ emu/g at $T = 4.2$ K, which is greater than the corresponding value of highly oriented graphite by a factor of four., Comment: 9 pages, 3 figures

Published
2014
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43. Photometric properties of Local Volume dwarf galaxies

Author

Sharina, M. E., Karachentsev, I. D., Dolphin, A. E., Karachentseva, V. E., Tully, R. Brent, Karataeva, G. M., Makarov, D. I., Makarova, L. N., Sakai, S., Shaya, E. J., Nikolaev, E. Yu., and Kuznetsov, A. N.

Subjects
Astrophysics
Abstract

We present surface photometry and metallicity measurements for 104 nearby dwarf galaxies imaged with the Advanced Camera for Surveys and Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope. In addition, we carried out photometry for 26 galaxies of the sample and for Sextans B on images of the Sloan Digital Sky Survey. Our sample comprises dwarf spheroidal, irregular and transition type galaxies located within ~10 Mpc in the field and in nearby groups: M81, Centaurus A, Sculptor, and Canes Venatici I cloud. It is found that the early-type galaxies have on average higher metallicity at a given luminosity in comparison to the late-type objects. Dwarf galaxies with M_B > -12 -- -13 mag deviate toward larger scale lengths from the scale length -- luminosity relation common for spiral galaxies, h \propto L^{0.5}_B. The following correlations between fundamental parameters of the galaxies are consistent with expectations if there is pronounced gas-loss through galactic winds: 1) between the luminosity of early-type dwarf galaxies and the mean metallicity of constituent red giant branch stars, Z ~ L^0.4, 2) between mean surface brightness within the 25 mag/sq.arcsec isophote and the corresponding absolute magnitude in the V and I bands, SB_25 ~ 0.3 M_25, and 3) between the central surface brightness (or effective surface brightness) and integrated absolute magnitude of galaxies in the V and I bands, SB_0 ~ 0.5 M_L, SB_e ~ 0.5 M_e. The knowledge of basic photometric parameters for a large sample of dwarf galaxies is essential for a better understanding of their evolution., Comment: 14 pages, 11 figures, 2 tables, MNRAS accepted

Published
2007
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49. Mesoscopic phase separation in La2CuO4.02 - a 139La NQR study

Author

Nikolaev, E. G., Brom, H. B., and Zakharov, A. A.

Subjects
Condensed Matter - Superconductivity
Abstract

In crystals of La2CuO4.02 oxygen diffusion can be limited to such small length scales, that the resulting phase separation is invisible for neutrons. Decomposition of the 139La NQR spectra shows the existence of three different regions, of which one orders antiferromagnetically below 17K concomitantly with the onset of a weak superconductivity in the crystal. These regions are compared to the macroscopic phases seen previously in the title compound and the cluster-glass and striped phases reported for the underdoped Sr-doped cuprates., Comment: 4 pages, RevTeX, 5 figures, to be published in PRB

Published
2000
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50. The interaction between criminal-executive inspections, and psychological center working with motivation and mental state convicted conditionally

Author

Nikolaev E. V. and Struchkova V. N.

Subjects
motivation, mental health, probation, criminal-executive inspection, psychological center, Psychology, BF1-990
Abstract

The article discusses the changes of motivation and mental States, people on probation and parole in the age of from 18 up to 35 years, whose main reason for conviction – robbery, robbery, use of psychoactive substances. The selected audience is predominantly men. Describes a psychological study of the personalities of probation and parole citizens on the basis of the tests: CHOICE lusher, a Test questionnaire G. Shmishek and K. Leongard (a technique of accentuation of character and temperament), Neurotic personality traits (NL) modification of L. I. Wasserman, B. V. Iovlev. The concept of development criminally-executive system of the Russian Federation until 2020 provides for the further development of alternatives to imprisonment. It is expected therefore making the activity of criminal-Executive inspection (UII) social focus, providing for the re-socialization of convicts in close cooperation with civil society institutions. Most urgently today is the question of socio-psychological and educational work with convicts. The involvement of the public, rehabilitation centers and other organizations in the process of social adaptation and rehabilitation of convicted persons is in the spirit of the time and demand of the main provisions of the concept of development UIS the Russian Federation until 2020. The development provides for UII at the same time as the introduction of innovative technologies in the field of social, psychological and educational work with convicts, and to raise the level of professional training of their employees.

Published
2017
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