Comparison of the hydrodynamic and Dirac models of the dispersion interaction between graphene and H, He∗{}^{\ast}, or Na atoms

The van der Waals and Casimir-Polder interaction of different atoms with graphene is investigated using the Dirac model which assumes that the energy of quasiparticles is linear with respect to the momentum. The obtained results for the van der Waals coefficients of hydrogen atoms and molecules and atoms of metastable He${}^{\ast}$ and Na as a function of separation are compared with respective results found using the hydrodynamic model of graphene. It is shown that, regardless of the value of the gap parameter, the Dirac model leads to much smaller values of the van der Waals coefficients than the hydrodynamic model. The experiment on quantum reflection of metastable He${}^{\ast}$ and Na atoms on graphene is proposed which is capable to discriminate between the two models of the electronic structure of graphene. In this respect the parameters of the phenomenological potential for both these atoms interacting with graphene described by different models are determined.Comment: 15 pages, 4 figure

Dispersion Interaction of Atoms with Single-Walled Carbon Nanotubes described by the Dirac Model

We calculate the interaction energy and force between atoms and molecules and single-walled carbon nanotubes described by the Dirac model of graphene. For this purpose the Lifshitz-type formulas adapted for the case of cylindrical geometry with the help of the proximity force approximation are used. The results obtained are compared with those derived from the hydrodymanic model of graphene. Numerical computations are performed for hydrogen atoms and molecules. It is shown that the Dirac model leads to larger values of the van der Waals force than the hydrodynamic model. For a hydrogen molecule the interaction energy and force computed using both models are larger than for a hydrogen atom.Comment: 9 pages, 3 figures, to appear in Int. J. Mod. Phys.

Layered nanomaterials for renewable energy generation and storage

This study focuses on potential applications of two-dimensional (2D) materials in renewable energy research.</jats:p

Significance of nutrient media choice for the long-term cultures of leukemic T-lymphoblasts

Correct choice of nutrient media for culturing different types of cells in various applications is one of the most important aspects of modern biotechnology, since chemical composition of the culture media largely contains the necessary metabolites to support certain cells’ growth lines outside the body. Jurkat line of human leukemic T-lymphoblast-like cells (hereinafter Jurkat T-cells) is actively used for in vitro modeling of intracellular signaling and activation of normal blood T-lymphocytes mediated by the T-cell receptor/CD3/ CD4 complex in toxicological studies of immune and secretory responses, to test medicinal substances and ions. Also, Jurkat T-cells are widely used for ex vivo testing in immunology, oncology, toxicology, orthopedics, and traumatology. The existing standards and numerous studies are mainly based on short-term in vitro cultivation of Jurkat T-cells in RPMI 1640 nutrient medium. Meanwhile, the issues of long-term maintenance of the growth of Jurkat T-cells culture are poorly presented in the research literature. This study aimed for studying the activity of Jurkat T-cells over 7 to 14 days of in vitro culture and comparing the relative value of RPMI 1640 and αMEM media for the behavior of immunocompetent tumor cells. Using flow cytometry, multiplex analysis, and phase contrast Cell-IQ microscopy, the proportions of living cells and those dying by apoptosis and necrosis, secretion of cytokines and chemokines, and the dynamics of cell biomass propagation were studied. It was found that the αMEM medium in the complete nutrient medium, as compared with RPMI 1640, is more appropriate to in vitro promotion of cell viability (increased proportion of viable cells by 13.5% at the day 14), their secretory ability for 23 из 27 tested biomolecules, shortened adaptation time (на 32%) in culture before growth initiation, 5-fold increase of the Jurkat Т-cell cellularity by the day 7. Potential significance of the chemical components of nutrient media and secreted biomolecules for these results is discussed. As based on the results obtained, we concluded on superior properties of αMEM medium for long-term in vitro cultures of Jurkat T-cells. Consequently, the in vitro testing of medical devices intended for long-term contact with the body, including those for cancer patients, using Jurkat T-cell leukemia line in RPMI 1640 medium, may lead to wrong predictions on their biocompatibility and potential antitumor activity

Моделирование микроокружения мезенхимных стволовых клеток как перспективный подход к тканевой инженерии и регенеративной медицине (краткий обзор)

One of the promising areas is the design and modification of materials for control over the fate of multipotent mesenchymal stromal cells (MMSCs) that will allow stroma of various human and animal organs and tissues to be constructed. However, the discussion about the existence and functioning of microenvironment for the MMSCs is just beginning to develop. The design of artificial materials that are able to reproduce biomimetically the cellular and tissue microenvironment and based on ideas and main elements borrowed from wildlife is current direction in a development of medical materials technology and tissue bioengineering. Scaffold technology is a promising experimental approach to simulate the properties of natural microenvironment of stem cells. Our aim is a short review of key elements of MMSC microterritories, its advanced investigations and the attempts of modeling in application to tissue bioengineering and regenerative medicine.Одним из перспективных направлений являются разработка и модификация материалов для контроля жизнедеятельности мультипотентных мезенхимных стромальных клеток (ММСК), которые (ре)конструируют строму различных органов и тканей человека и животных. Тем не менее обсуждение вопроса о существовании и функционировании микроокружения ММСК только начинается. Это тормозит дальнейшее развитие клеточной биологии и тканевой инженерии. Дизайн искусственных материалов, способных к биомиметическому воспроизведению клеточного и тканевого микроокружения, основанный на идеях и элементах, заимствованных у природы, является современным направлением в развитии медицинского материаловедения и тканевой инженерии. Скеффолд-технологии – многообещающий экспериментальный подход к моделированию свойств природного микроокружения для стволовых клеток. Цель – краткий обзор ключевых элементов микротерриторий ММСК, его перспективных исследований и попыток моделирования в приложении к тканевой инженерии и регенеративной медицине.

Параметризація кривих фазових проникностей для моделювання витіснення нафти водою і газом при тисках нижче тиску насичення

Numerical modeling of water alternating-gas processes requires adequate representation of dependencies of relative phase permeability for oil, gas and water upon saturation of the reservoir. On the basis of the agreement of lhe results of numerical modeling with laboratory experiments parameterization of Korea functions for phase permeability of Hocene sandstone for oil, gas and water at pressure below the saturation pressure has been carried out. Correlation between meters of membership functions with initial gas saturation, formed as a result of the allocation of oil dissolved gas. has been established