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An important component of modern biomedicine is the development and use of hybrid bioactive nanomaterials with a hierarchical structure. The unique physical and chemical properties of low-dimensional aluminum oxyhydroxide nanomaterials with an irregular structure make it a promising base for the creation of hierarchical nanoagents with biological activity. Therefore, it is of fundamental and applied importance to study the interaction of organic molecules and ions of a biological medium with irregular fragments of folded (crumpled) two-dimensional aluminum oxyhydroxide nanostructures. This paper uses all-atom molecular dynamics models to investigate numerically the interaction of AlOOH fragments with a biomolecule and the formation of a hybrid nanocomplex in the zone of a nanosheet defect. The free energy of hybrid complex formation in the region with an irregular structure of AlOOH is estimated using steered molecular dynamics. It is shown by the example of a defect observed as nanosheet folding with a kink that the irregular regions of low-dimensional nanomaterial can play a major role in the adsorption of ions of a biological medium and the formation of hierarchical organo-inorganic complexes with bioactive molecules. [ABSTRACT FROM AUTHOR]

The strong surface electric charge density of clay mineral host nanolayers enables their use as host-guest nanohybrids in many different areas of application. In particular, layered double hydroxides (LDH) of metals have found applications in medicine. Drug-LDH or gene-LDH nanohybrids are used for targeted delivery of biomedical agents to diseased cells or cancer cells. Fragments of the LDH host nanolayers may remain both within the cell and in the extracellular medium after drug delivery. How these charged nanosheets affect the cell electrostatics is still poorly understood. In the present paper, the idealized case of a single pure Mg2/Al-LDH nanolayer interacting with the extracellular anion environment was investigated to estimate the order of magnitude of a possible shift of the cell membrane equilibrium potential. An approximate dependence of the change in the chloride equilibrium membrane potential on the concentration of pure Mg2/Al-LDH nanosheets was determined. [ABSTRACT FROM AUTHOR]

Main attention of the research is focused on the role of vortex-like structures in the velocity fields of the strengthening coating and substrate under contact loading by hard conical indenter. The peculiarities of velocity vortex formation and propagation, as well as its interaction with structural elements are studied. One of possible application of the study is non-destructive technique for detecting nanoscale defects in surface layer of a material using frequency analysis of the friction force. Possibilities of this technique are studied based on 3D simulation. [ABSTRACT FROM AUTHOR]

Molecular dynamics investigation of metal crystallite with bcc lattice under nanoindentation was carried out. Potentials of interatomic interactions were calculated on the base of the approximation of the Finnis-Sinclair method. For clarity and simpler indentation data interpretation, an extended cylindrical indenter was used in the investigation. The features of the bcc iron structural response at nanoindentation of surfaces with different crystallographic orientations were revealed. Generation of structural defects in the contact zone always resulted in the decrease in the rate of growth of the reaction force. [ABSTRACT FROM AUTHOR]

A molecular dynamics model was constructed to describe material loading on the atomic scale by the mode identical to friction stir welding. It was shown that additional vibration applied to the tool during the loading mode provides specified intensity values and continuous thermomechanical action during welding. An increase in additional vibration intensity causes an increase both in the force acting on the workpiece from the rotating tool and in temperature within the welded area. [ABSTRACT FROM AUTHOR]

Hydrophobic and functionalized nanoparticles of different sizes and shapes have a various biomedical application, in particular anticancer therapy. It is known that charged nanoparticles may bind lipids and membrane proteins as well as cause lipid bilayer disruption. We have performed preliminary molecular dynamic simulations to investigate the effect of positively charged synthetic nanofilm, imitating a fragment of the two-dimensional folded AlOOH structure, on the POPE/POPG lipid membrane. It has been shown that the synthetic nanofilm with frozen coordinates tightens the membrane and binds lipid headgroups. Furthermore, the presence of the positively charged nanofilm perturbs the cation concentration in the near-surface membrane region. [ABSTRACT FROM AUTHOR]

The paper undertakes a study of plastic deformation in a titanium crystallite under mechanical loading (uniaxial tension and indentation) in terms of atomic mechanisms of its generation and development. The molecular dynamics method with many-body interatomic potentials is employed. It is shown that there is a threshold strain, at which a crystal reveals the generation of local structural transformations associated with changes in atomic configurations of the first and second coordination spheres. The onset of plastic deformation in a crystallite is accompanied by a stepwise decrease in potential energy. The effect of free surfaces and grain boundaries on the generation of local structural transformations in a titanium crystallite is investigated. [ABSTRACT FROM AUTHOR]

Shock wave properties generated by impulse mechanical loading and base state structure of dusty plasma system versus the change of dusty particle charges with height were investigated in the framework of the molecular dynamics method. Spherically symmetric electrostatic confinement was used as the boundary conditions. Interactions between dusty particles were described using Debye-Huckel potential. Particle charges decreased linearly with the increase of height. Shape of dusty plasma crystals with taking into account a variable particle charge was simulated. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of nanoparticle formation in simultaneous electric explosion of conductors is performed. Interatomic interaction is described using potentials calculated in the framework of the embedded atom method. High-rate heating results in failure of the conductors with the formation of nanoparticles. The influence of the heating rate, temperature distribution over the specimen cross-section and the distance between simultaneously exploded conductors on the structure of formed nanoparticles is studied. The calculation results show that the electric explosion of conductors allows the formation of nanoparticles with block structure. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulation was performed to study the features of nucleation and development of plastic deformation in copper crystallites in nanoindentation with different crystallographic orientations of their loaded surface: (011), (001), and (111). Atomic interaction was described by a potential constructed in terms of the embedded atom method. It is shown that behavior of the crystallite reaction force correlates well with a change in the fraction of atoms involved in local structural rearrangements. The generation of local structural changes decreases the slope of the crystallite reaction force curve or results in an extremum due to internal stress relaxation. Analysis of structural changes in the material being indented demonstrates that the orientation of its loaded surface greatly affects the features of nucleation and development of plastic deformation. [ABSTRACT FROM AUTHOR]