G. V. Savostyanov

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.

Laser structuring of carbon nanotubes in the albumin matrix for the creation of composite biostructures

Abstract. This paper presents the composite biostructures created by laser structuring of the single-walled carbon nanotubes (SWCNTs) in an albumin matrix. Under the exposure of femtosecond laser radiation, the heating of the albumin aqueous solution causes liquid water to evaporate. As a result, we obtained a solid-state composite in the bulk or film form. Using the molecular dynamic method, we showed the formation of a framework from SWCNTs by the example of splicing of the open end of one nanotube with the defect region of another nanotube under the action of the laser heating. Laser heating of SWCNTs up to a temperature of 80°C to 100°C causes the C─C bond formation. Raman spectra measured for the composite biostructures allowed us to describe the binding of oxygen atoms of amino acid residues of the albumin with the carbon atoms of the SWCNTs. It is found that the interaction energy of the nanotube atoms and albumin atoms amounts up to 580  kJ/mol. We used atomic force microscopy to investigate the surface of the composite biostructures. The pore size is in the range of 30 to 120 nm. It is proved that the proliferation of the fibroblasts occurred on the surface of the composite biostructures during 72 h of incubation.

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).

Stimulation of the specific conductivity of the biocompatible nanomaterial layers by laser irradiation

The conductivity of layers (thickness ~ 0.5-20 μm) of composite nanomaterials consisting of bovine serum albumin (BSA) with single-walled carbon nanotubes (SWCNTs) has been studied. The BSA/SWCNT composite nanomaterial was prepared according to a route map, some steps of which are: the preparation of an aqueous dispersion based on BSA and SWCNT; preparation of substrates; deposition of BSA/SWCNT dispersion on substrates; application of water paste from SWCNT on substrates; irradiation of layers by lasers when they were in a liquid state; drying of samples; carrying out electrical and temperature measurements. Half of the layer was covered with a light-tight hollow box and the other half of the layer was laser irradiated. The laser irradiation of the layer was carried out for about 20 sec, at which time the layers completely became dry, while the other half of the layer remained in liquid. Conductivity was increased (70 ÷ 650) % by laser irradiation of the layers when they were in the liquid state. Maximum values of specific conductivity for BSA/SWCNT-1 S/m layers, and for layers SWCNT - 70 kS/m. The investigated electrically conductive layers of 99 wt.% BSA/0.3 wt.% SWCNT are promising for medical practice.

A new hybrid model to simulate interaction between DNA and carbon nanostructure

A new hybrid mathematical model allowing us to investigate the interaction between the components of the DNA + carbon nanostructure molecular complex on the atomic and molecular levels are developed. Within the developed model we proposed to describe the carbon nanostructures by means of the methods and approaches of atomistic modeling, and to describe the DNA molecule using the methods and approaches of coarse-grained modeling. A coarse-grained structure of DNA is built based on 3-Site-Per-Nucleotide model. The proposed hybrid model has been implemented in the original software complex for molecular modeling KVAZAR using modern IT-solutions. The novelty of the model is concluded to a finding the weight coefficients for the interaction of large particles, simulating DNA, and conventional particle, simulating carbon nanostructure, and also for the intermolecular interactions. On the basis of established regularities for interaction between DNA and carbon nanostructures we will develop the model of the sensor device.

Laser structuring of carbon nanoframe in a protein matrix for the creation of 3D composite materials and coatings for applications in tissue engineering

The results of experimental creation of nanocomposites using femtosecond laser are presented. We have theoretically proved the formation of a carbon nanotube frame in a protein matrix during laser structuring of single-walled carbon nanotubes. We have selected the technological parameters of synthesis of nanocomposites, which provide the proliferation of living cells.

Enhancement of the conductivity of nanomaterial layers by laser irradiation

The conductivity of layers (thickness 0.5 ÷ 50 μm) of composite nanomaterials consisting of bovine serum albumin (BSA) with single-walled carbon nanotubes (SWCNTs) has been studied. The aqueous dispersion of BSA / SWCNT was deposited on different substrates using the silk screening method. Conductivity was increased (30 ÷ 700) % by laser irradiation of the layers when they were in the liquid state. The investigated layers are promising for use in medical practice.

Simulation of the formation for molecular compounds of nanotubes with different chirality indexes to create new molecular devices on their basis

The main property of carbon nanotubes that determinates their wide application in electronics is a change of the chirality for ideal structure of a nanotube at implementing of structural Stone-Wales defect (pentagon-heptagon pairs) to its atomic framework. This property allows us to create nanotube-based different electronic devices (diodes, transistors, resistors), similar to traditional silicon devices. Nanotube with incorporated defect can be considered as a metalsemiconductor heterojunction. On the basis of this heterojunction semiconductor elements of very small size can be implemented, less than the current silicon elements. To create devices based on metal-semiconductor heterojunction is necessary to know the mechanisms of formation of the molecular compounds of nanotubes with different chirality. The aim of this work is a theoretical study of the formation of the molecular compounds of nanotubes with different chirality leading to the appearance of the metal-semiconductor heterojunction using molecular modeling methods. The object of investigation is a heterojunction formed by the compound of nanotubes with chirality indices (13,10) and (14, 10). To identify regularities of change in the electronic structure of the compound nanotubes we calculated the density of electronic states (DOS) for the heterojunction, and for each of its constituent chiral tubes. Also, we carried out a numerical evaluation of the reaction enthalpy of formation of the heterojunction. Based on these results it can be concluded that the investigated molecular compounds can be used to create highly sensitive sensors.

Atomic structure of energetically stable composites, based on carbon nanotubes and graphene

The investigation of energy stability of composites based on graphene sheets and carbon nanotubes was investigated. The dependence of enthalpy of formation from geometry parameters, such as length and diameter of nanotubes, distance between nanotubes on graphene sheet, of composites parts, optimal geometry for most energy sustainable composites were found.