381 research outputs found

    Adhesive coatings based on aligned arrays of carbon nanostructures

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    This work was financially supported by Russian Foundation for Basic Research (projects 16-29-14023 and 18-32-00652) and Internal grant of the Southern Federal University (project VnGr-07/2017-26)

    Application of Probe Nanotechnologies for Memristor Structures Formation and Characterization

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    This chapter presents the results of experimental studies of the formation and investigation of the memristors by probe nanotechnologies. This chapter also perspectives and possibilities of application of local anodic oxidation and scratching probe nanolithography for the manufacture of memristors based on titanium oxide structures, nanocrystalline ZnO thin film, and vertically aligned carbon nanotubes. Memristive properties of vertically aligned carbon nanotubes, titanium oxide, and ZnO nanostructures were investigated by scanning probe microscopy methods. It is shown that nanocrystalline ZnO films manifest a stable memristor effect slightly dependent on its morphology. Titanium oxide nanoscale structures of different thicknesses obtained by local anodic oxidation demonstrate a memristive effect without the need to perform any additional electroforming operations. This experimentally confirmed the memristive switching of a two-electrode structure based on a vertically aligned carbon nanotube. These results can be used in the development of designs and technological processes of resistive random access memory (ReRAM) units based on the memristor devices

    Some generic aspects of bosonic excitations in disordered systems

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    We consider non-interacting bosonic excitations in disordered systems, emphasising generic features of quadratic Hamiltonians in the absence of Goldstone modes. We discuss relationships between such Hamiltonians and the symmetry classes established for fermionic systems. We examine the density \rho(\omega) of excitation frequencies \omega, showing how the universal behavior \rho(\omega) ~ \omega^4 for small \omega can be obtained both from general arguments and by detailed calculations for one-dimensional models

    Vertically Aligned Carbon Nanotubes Production by PECVD

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    This chapter presents the results of experimental studies of the PECVD technological mode parametersā€™ influence on the formation of catalytic centers and carbon nanotubesā€™ (CNTsā€™) growth processes. This chapter also presents the ability to regulate the growth parameter for the controlled production of CNTs with the required geometric parameters, properties, and growth mechanisms. The results of experimental studies of the heating temperature and activation time effects on the catalytic center formation will be presented. This chapter also shows the effects of growth temperature, heating rate, and the activation time on the geometric and structural parameters of the carbon nanotubes. Experimental studies were carried out with the use of AFM, SEM, TEM, and EXAFS techniques. The results can be used in the development of technological processes for creating ultrafast energy-efficient electronic component base with carbon nanostructures, particularly nanoelectromechanical switches, flexo- and piezoelectric generators, gas sensors, and high-performance emitters

    Study of the dependence of Young's modulus of vertically aligned carbon nanotubes on their aspect ratio

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    The reported study was funded by RFBR according to the research projects No.16-29-14023 ofi_m, No.18-32-00652 and by grant of the Southern Federal University (project No. VnGr-07/2017-26)

    Morbidity Rate Forecasting for 2014 as Regards Tick-Borne Viral Encephalitis in the Territory of the Russian Federation Based on Multi-Factor Regression Models

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    Morbidity forecasting as regards tick-borne viral encephalitis has been carried out using three various methods. Demonstrated is the fact that variability consistency among the actual values accounting the numbers of seeking medical aid because of tick bites and estimated values within the current quasi-cycle is 31.4 %. Developed have been multi-factor regression models for medical aid encounters on the occasion of tick bites and for tick-borne viral encephalitis morbidity. Identified are the most significant factors which characterize specific prophylaxis, acaricide treatment, and abundance of infected ticks; estimated is the impact of the factors on the forecasting. Maximum level of interdependency has reached 78 %: in case with seroprevention it has come up to 64 %, vaccination - 11.5 %, acaricide treatments - 4 %, and abundance of infected ticks - 3%. It has been outlined that a 20 % extension of areas for acaricide treatments leads to a 5% decrement in medical aid encounters, while a 20% reduction - to an almost 7 % rise, respectively. Thus evaluation of the significance of the preventive and curative interventions is of a crucial importance while developing Territorial prevention programmes if undertaken along with consistent application of acaricide treatments

    Scanning Probe Techniques for Characterization of Vertically Aligned Carbon Nanotubes

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    This chapter presents the results of experimental studies of the electrical, mechanical and geometric parameters of vertically aligned carbon nanotubes (VA CNTs) using scanning probe microscopy (SPM). This chapter also presents the features and difficulties of characterization of VA CNTs in different scanning modes of the SPM.Ā Advanced techniques for VA CNT characterization (the height, Youngā€™s modulus, resistivity, adhesion and piezoelectric response) taking into account the features of the SPM modes are described. The proposed techniques allow to overcome the difficulties associated with the vertical orientation and high aspect ratio of nanotubes in determining the electrical and mechanical parameters of the VA CNTs by standard methods. The results can be used in the development of diagnostic methods as well as in nanoelectronics and nanosystem devices based on vertically aligned carbon nanotubes (memory elements, adhesive structures, nanoelectromechanical switches, emission structures, etc.)

    Generation of small-scale structures in the developed turbulence

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    The Navier-Stokes equation for incompressible liquid is considered in the limit of infinitely large Reynolds number. It is assumed that the flow instability leads to generation of steady-state large-scale pulsations. The excitation and evolution of the small-scale turbulence is investigated. It is shown that the developed small-scale pulsations are intermittent. The maximal amplitude of the vorticity fluctuations is reached along the vortex filaments. Basing on the obtained solution, the pair correlation function in the limit rā†’0r\to 0 is calculated. It is shown that the function obeys the Kolmogorov law r2/3r^{2/3}.Comment: 18 page

    Hard loss of stability in Painlev\'e-2 equation

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    A special asymptotic solution of the Painlev\'e-2 equation with small parameter is studied. This solution has a critical point tāˆ—t_* corresponding to a bifurcation phenomenon. When t<tāˆ—t<t_* the constructed solution varies slowly and when t>tāˆ—t>t_* the solution oscillates very fast. We investigate the transitional layer in detail and obtain a smooth asymptotic solution, using a sequence of scaling and matching procedures
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