Fast diffusion of graphene flake on graphene layer

Diffusion of a graphene flake on a graphene layer is analyzed and a new diffusion mechanism is proposed for the system under consideration. According to this mechanism, rotational transition of the flake from commensurate to incommensurate states takes place with subsequent simultaneous rotation and translational motion until the commensurate state is reached again, and so on. The molecular dynamics simulations and analytic estimates based on ab initio and semi-empirical calculations demonstrate that the proposed diffusion mechanism is dominant at temperatures T ~ Tcom, where Tcom corresponds to the barrier for transitions of the flake between adjacent energy minima in the commensurate states. For example, for the flake consisting of ~ 40, 200 and 700 atoms the contribution of the proposed diffusion mechanism through rotation of the flake to the incommensurate states exceeds that for diffusion of the flake in the commensurate states by one-two orders of magnitude at temperatures 50 - 150 K, 200 - 600 K and 800 - 2400 K, respectively. The possibility to experimentally measure the barriers to relative motion of graphene layers based on the study of diffusion of a graphene flake is considered. The results obtained are also relevant for understanding of dynamic behavior of polycyclic aromatic molecules on graphene and should be qualitatively valid for a set of commensurate adsorbate-adsorbent systems.Comment: 33 pages, 6 figure

Obesity in Russia: modern view in the light of a social problems

The purpose of the article is to highlight the social aspects of stress as a syndrome of adaptation to the current situation in Russian society in order to justify the consideration of society as a factor contributing to the development and spread of overweight and obesity among the Russian population. The problem of the conditions and quality of everyday life of a significant part of the population of our country is raised, which are accompanied by an increased stress level of everyday life events. A modern Russian society, possessing an immanently inherent systemic quality - a stressful property, combined with the specificity of a hypodynamic lifestyle, is a powerful and systemically active factor that provokes the development and spread of obesity and overweight. The stress factors of modern society, generated by the disorder and non-complementarity of the work of social institutions, instability in the economic and political spheres are analyzed. Food family traditions, food paradigm, leisure activity of Russians are studied. The irrationality of the use of food by mankind is discussed. The proposed measures to combat and prevent obesity

Tecnologias e dispositivos de microondas que separam a pele da pele de coelho

The purpose of this work is the development of microwave technology and de-vices separating fur from rabbit skins in a continuous mode at reduced operating costs. They developed the method for the action of the ultrahigh frequency electro-magnetic field (UFEF), which provides the reduction of fur fiber holding power in the meat fabric of rabbit skins with simultaneous combing and gathering. They calcu-lated the mathematical dependences describing the dynamics of multicomponent raw material heating with the change of dielectric and physicomechanical parameters in the process of UFEF. They calculated and visualized the electromagnetic field distri-butions in the developed resonators, on the basis of which they substantiated the ef-fective parameters of the electrodynamic system: the maximum property, the quality of resonators and the electric field strength. They substantiated the complex of struc-tural and technological parameters of devices with new structural design of working chambers by a multi-criteria evaluation of the technological process for the separation of fur from rabbit skin. They manufactured and tested the microwave device under production conditions for the separation of fur from rabbit skin, and adjusted the op-erating modes, which allow to reduce operating costs. They evaluated the technical and economic efficiency of microwave technology introduction for the processing of fur and the devices for rabbit farms; they developed practical recommendations for the operation of microwave units to separate fur from rabbit skins.El propósito de este trabajo es el desarrollo de la tecnología de microondas y los dispositivos que separan la piel de los cueros de conejo en un modo continuo a costos operativos reducidos. Desarrollaron el método para la acción del campo electromagnético de frecuencia ultraalta (UFEF), que proporciona la reducción del poder de retención de la fibra de la piel en el tejido de carne de la piel de conejo con el peinado y la recolección simultáneos. Calcularon las dependencias matemáticas que describen la dinámica del calentamiento de materias primas de componentes múltiples con el cambio de los parámetros dieléctricos y fisicomecánicos en el proceso de la UFEF. Calcularon y visualizaron las distribuciones del campo electromagnético en los resonadores desarrollados, sobre la base de los cuales fundamentaron los parámetros efectivos del sistema electrodinámico: la propiedad máxima, la calidad de los resonadores y la intensidad del campo eléctrico. Ellos sustentaron el complejo de parámetros estructurales y tecnológicos de los dispositivos con un nuevo diseño estructural de las cámaras de trabajo mediante una evaluación de múltiples criterios del proceso tecnológico para la separación de la piel del cuero del conejo.  Fabricaron y probaron el dispositivo de microondas en condiciones de producción para la separación de la piel de la piel de conejo, y ajustaron los modos de operación, lo que permite reducir los costos operativos. Evaluaron la eficiencia técnica y económica de la introducción de la tecnología de microondas para el procesamiento de pieles y los dispositivos para granjas de conejos; desarrollaron recomendaciones prácticas para el uncionamiento de las unidades de microondas para separar las pieles de los cueros de conejo.O objetivo deste trabalho é o desenvolvimento de tecnologia e dispositivos que separam a pele de peles de coelho em um modo contínuo a custos operacionais reduzidos microondas. Eles desenvolveram o método para a acção do campo electromagnético de alta frequência ultra-(UFEF), que fornece pele de coelho carne tecido de pele para retenção de fibras de energia reduzido com cabelo e recolha simultânea. Calcularam as dependências matemático para descrever a dinâmica do aquecimento materiais multicomponentes com a mudança de dieltricos e parâmetros fisicomecánicos no processo de UFEF. Eles calculado e visualizado as distribuições de campo eletromagnético em ressonadores desenvolvidos, com base na qual fundamentar os parâmetros reais do sistema electrodynamic: a propriedade máximo, a qualidade dos ressonadores e intensidade do campo elétrico. Eles sustentadas parâmetros estruturais e tecnológicas complexas dos dispositivos com um novo design estrutural das câmaras de trabalho através de uma avaliação multi-critérios do processo tecnológico para a separação de couro pele de coelho. Eles fabricado e testado o dispositivo de micro-ondas, sob condições de produção para a separação da pele da pele de coelho, e modos de operação ajustados, reduzindo assim os custos operacionais. Eles avaliaram a eficiência técnica e econômica da introdução de tecnologia de microondas para o processamento de dispositivos fazendas de peles e de coelho; desenvolveu recomendações práticas para a operação de unidades de microondas para separar peles de peles de coelho

Nanotube-Based NEMS: Control vs. Thermodynamic Fluctuations

Multi-scale simulations of nanotube-based nanoelectromechanical systems (NEMS) controlled by a nonuniform electric field are performed by an example of a gigahertz oscillator. Using molecular dynamics simulations, we obtain the friction coefficients and characteristics of the thermal noise associated with the relative motion of the nanotube walls. These results are used in a phenomenological one-dimensional oscillator model. The analysis based both on this model and the Fokker-Planck equation for the oscillation energy distribution function shows how thermodynamic fluctuations restrict the possibility of controlling NEMS operation for systems of small sizes. The parameters of the force for which control of the oscillator operation is possible are determined.Comment: 40 pages, 12 figure

State Priorities in the Petrochemistry of Russia: Sustainable Development, “Green” Industry and Energy Efficiency

This research aims at diagnosing such priority areas for the development of petrochemicals in Russia as sustainable development and energy efficiency, at identifying trends and forecasting the development of the industry, taking into account the greening of the industry. Achieving the goal is based on the use of methods such as graphical, comparative, economic and mathematical (neural network modeling, correlation regression analysis), and prognostic. The article contains an assessment of the achievement of the Sustainable Development Goals focused on energy saving and environmental protection; forecasting the level of greenhouse gas emissions in Russia based on the construction of a neural network and a regression model; comparative analysis of the rates of transition to sustainable development of chemical production and production of coke and petroleum products in the Russian economy. The scientific results of the research are a neural network model trained on the indicators of sustainable and energy efficient development of the Russian economy, on the basis of which the relationship between the level of greenhouse gas emissions, the energy intensity of GDP and the share of electricity from renewable energy sources is formalized; a predictive model that made it possible to calculate future values of greenhouse gas emissions depending on the target values of predictive variables; features of the greening of petrochemical industries in Russia.Keywords: petrochemical industry, state priorities, sustainable development, green industry, energy efficiency, Russia.JEL Classifications: О14, D24, С41DOI: https://doi.org/10.32479/ijeep.11364</p

Barriers to motion and rotation of graphene layers based on measurements of shear mode frequencies

Both van der Waals corrected density functional theory and classical calculations show that the potential relief of interaction energy between layers of graphite and few-layer graphene can be described by a simple expression containing only the first Fourier components. Thus a set of physical quantities and phenomena associated with in-plane relative vibration, translational motion and rotation of graphene layers are interrelated and are determined by a single parameter characterizing the roughness of the potential energy relief. This relationship is used to estimate the barriers to relative motion and rotation of graphene layers based on experimental measurements of shear mode frequencies.Comment: 16 pages, 1 figur