M. M. Slepchenkov

Phenomenon of current occurrence during the motion of a C60 fullerene on substrate-supported graphene

This paper studies the patterns of behavior of the fullerene C60 on graphene supported by an SiO2 substrate, taking into account the substrate topology and features of the electronic interaction between graphene and fullerene. It is found that the motion of the C60 molecule acquires a finite character when the substrate has a certain determined degree of curvature. We establish that such a character of motion occurs at a corrugation wavelength of 3.4 nm and wave-depth of 1.6 nm. The motion of the fullerene becomes more precise with deviations of tenths of an angstrom under an external electric field, which allows the motion of the fullerene to be manipulated along the trough. During the investigation of the electronic interaction between graphene and the C60 molecule it was found for the first time that the motion of the fullerene on graphene creates a small current that constantly changes due to the changing distance between the two objects. This physical phenomenon can be used as a physical principle for designing nanodevices.

Atomic structure of energetically stable carbon nanotubes/graphene composites

The atomic structure of energetically stable composites based on carbon nanotubes and graphene has been studied. The energy stability has been determined from the change in the total energy of the studied system. It has been found that the geometric parameters of the nanotube affect the stability of the minimum structural link of the composite. The structural configuration of the composite with armchair nanotubes 12.12 Å in diameter and 18.44 Å in length exhibits the highest stability. It has been shown that the energy stability of the composite increases with an increase in the number of links in it.

Moving of fullerene between potential wells in the external icosahedral shell.

The results of the theoretical investigation of the behavior of fullerenes C20 and C60 inside the icosahedral external shell on example of carbon nanoclusters, C20@С240 and C60@С540, are presented in this article. The multiwell potential of interaction between fullerenes in investigated nanoclusters is calculated to reveal the regularities of moving for internal fullerene in the field of holding potential of the external shell. The possible variants of fullerenes C20 and C60 moving between the potential wells are predicted on base of topology data of the fullerenes relative positioning in nanoparticle and analysis of relief of the energy surface of interaction between fullerenes. The formulated prediction is confirmed by the data of the numerical experiment. The investigation of two‐shell fullerenes allows to conclude that the light fullerene С20 will probably jump between the potential wells already at small temperatures (139–400 K) if the external shell is slightly bigger.

Elastic properties of graphene-graphane nanoribbons

The results of theoretical investigation of the atomic structure, deformations, and elastic properties of graphene-graphane nanoribbons (GGN) are represented here. To study the properties of GGN we applied the empirical method based on the bond-order potential developed by Brenner and the tight-binding method. We calculated the Youngs pseudo-modulus of GGN and the strain energy of GGN subject to axial tension and compression. The curve of the strain energy collapse occurs at the axial compression of 0.03?0.04. Plane atomic network subject to axial compression becomes wave-like. This is a so-called phase transition. Elasticity of armchair-graphene nanoribbons is greater than elasticity of armchair nanotubes and graphane nanoribbons with the same width and length.

Prediction of the stability and electronic properties of carbon nanotori synthesized by a high-voltage pulsed discharge in ethanol vapor

An experimental technique for increasing the yield of carbon-nanotube nanotori using the modified arc synthesis method is proposed. New physical knowledge on the systematic features of the interrelation between the properties of nanotori and atomic-network topology are theoretically established for the first time. The experiments are performed based on new technology for synthesizing nanotori on nickel-catalyst particles by a high-voltage pulsed discharge in ethanol vapor and using atomic-force microscopy. Stability is predicted using an original procedure for calculating local atomic stresses. Simulation shows that the zigzag chirality corresponds to the most stable topology of nanotori. Using the tight binding method, it is shown that, depending on the chirality type, nanotori are divided into two classes, i.e., those with metal and semiconductor conductivity.

Prediction of stability for carbon nanotori

At the present time carbon nanostructures are the main functional material for the development of electronic devices of broad applications. One of the most perspective for practical application forms of carbon nanostructures are nanotori. This paper presents results of prediction the stability of toroidal structures using computer modeling methods. The stability of carbon nanotori are determined by scanning of the local stresses map. Obtained results showed that the highest stability is characterized for carbon nanotori (13, 0) formed by the folding of a zigzag carbon nanotube. These nanotori are characterized by the lowest enthalpy of structure formation (101 eV).

Structure and properties of composites based chitosan and carbon nanostructures: atomistic and coarse-grained simulation

At the present time actual task of the modern materials is the creation of biodegradable biocompatible composite materials possessing high strength properties for medical purposes. One of the most promising biomaterials from a position of creation on their basis super strong nanofibres is chitosan. The aim of this work is a theoretical study of the structural features and physico-mechanical properties of biocomposite materials based on chitosan and carbon nanostructures. As matrix nanocomposite we considered various carbon nano-objects, namely carbon nanotubes and graphene. Using the developed original software complex KVAZAR we built atomistic and coarse-grained models of the biocomposite material. To identify regularities of influence of the configuration of the carbon matrix on the mechanical and electronic properties of biocomposite we carried out a series of numerical experiments using a classical algorithm of molecular dynamics and semi-empirical methods. The obtained results allow us to suggest that the generated biocomposite based on chitosan and carbon nanostructures has high stability and strength characteristics. Such materials can be used in biomedicine as a base material for creating of artificial limbs.

Development of the terahertz emitter model based on nanopeapod in terms of biomedical applications

Model of terahertz radiation sources was developed in this work. This model based on the nanopeapod: carbon nanotube (10, 10) with incapsulated chains of the fullerene C60. Simulation of the nanoemitter action was carried out by means of the molecular-mechanical model. The length of the considered nanotube is equals to 10.3 nm, and radius of this tube is equals to 1.35 nm. It was found that to generate the radiation in terahertz range it is necessary to apply the external field with strength of 1⋅106 V / cm to our system. The moving fullerene C60 has a charge of +3е, and the nanotube has a charge of -3е. It was established that the field emission process from the surface of the nanotube is not observed in this case. The submitter model of nanoemitter works with a frequency 0.36 THz at a field strength of 1⋅106 V / cm.

Theoretical prediction of the energy stability of graphene nanoblisters

The paper presents the results of a theoretical prediction of the energy stability of graphene nanoblisters with various geometrical parameters. As a criterion for the evaluation of the stability of investigated carbon objects we propose to consider the value of local stress of the nanoblister atomic grid. Numerical evaluation of stresses experienced by atoms of the graphene blister framework was carried out by means of an original method for calculation of local stresses that is based on energy approach. Atomistic models of graphene nanoblisters corresponding to the natural experiment data were built for the first time in this work. New physical regularities of the influence of topology on the thermodynamic stability of nanoblisters were established as a result of the analysis of the numerical experiment data. We built the distribution of local stresses for graphene blister structures, whose atomic grid contains a variety of structural defects. We have shown how the concentration and location of defects affect the picture of the distribution of the maximum stresses experienced by the atoms of the nanoblisters.

Investigation of the mechanism for penetration of low density lipoprotein into the arterial wall

Currently, the pathology of the cardiovascular system is an extremely urgent problem of fundamental and clinical medicine. These diseases are caused, mainly, by atherosclerotic changes in the wall of blood vessels. The predominant role in the development of atherosclerosis is attributed to the penetration of various kinds of lipoproteins into the arterial intima. In this paper, we in silico investigated the dynamics of the penetration of low density lipoprotein (LDL) through the intercellular gap using molecular modeling methods. The simulation was carried out in the GROMACS software package using a coarse-grained MARTINI model. During investigation we carried out the LDL self-assembly for the first time. The coarse-grained model of LDL was collected from the following molecules: POPC (phosphatidylcholine) - 630 molecules, LPC (lysophosphatidylcholine) - 80 molecules CHOL (cholesterol) - 600 molecules CHYO (cholesteryl oleate) - 1600 molecules TOG (glycerol trioleate) 180 Molecules. The coarse-grained model of the intercellular endothelial gap was based on a model of lipid bilayer consisting of DPPC phospholipids and cholesterol in a percentage ratio of 70% and 30%, respectively. Based on the obtained results, we can predict the mechanism of LDL diffusion. Lipoproteins can be deformed so as to pass through narrow gaps. Our investigations open the way for the research of the behavior dynamics of LDL moving with the blood flow rate when interacting with the intercellular gaps of the endothelial layer of the vessel inner wall.