The interfacial energy of metallic nanoparticles on the boundary with polyatomic alcohols

The interface energy is general factor, which has determined the critical size and equilibrium shape of nanoparticles, velocity of its growth and stability. The electron-statistical method, based on the Thomas-Fermi theory taking into account its current state, allows one to calculate the interfacial energy of metallic objects of different dimensions at the boundary with various media. Based on this method, we have developed a variant for calculating the interfacial energy of the system « low-dimensional metallic phase - polar dielectric film». The polyatomic alcohols (diols), used, for example, as non-aqueous media for the synthesis of metal nanoparticles, were chosen as the external medium. Also we have chosen cobalt nanocrystals as a low-dimensional metallic phase. Expressions are obtained for the external and internal contributions to the interfacial energy of the system, including the polarization correction, due to the presence of a dielectric fluid in the external region of the system. The effect of a limited dielectric fluid layer on the Gibbs boundary coordinate is analyzed. The presence of a dielectric leads to a shift of the Gibbs boundary to the external region of the system, that is, the so-called effect of «pulling the tail» of the electron density is observed. It is shown that with increasing dielectric constant, the magnitude of the polarization contribution increases rapidly in magnitude. The interface energy of a cobalt nanocrystal at the interface with polar polyatomic alcohols is calculated. The interfacial energy of the faces of cobalt nanocrystals decreases nonlinearly with an increase in the linear dimensions of the metal phase. It is shown that the dielectric coating changes the character of the dimensional and orientational dependence in comparison with the interfacial energy of macrocrystals and thin films at the interface with vacuum. With a constant size of the metal phase and an increase in the thickness of the dielectric coating, the interface energy of faces and anisotropy increase. It has been established that 1,2-ethanediol is the most effective surfactant for cobalt particles of the polyatomic alcohols considered in this paper. The dependencies obtained in this work are consistent with the literature data for the thin films of alkaline metals and other system.

Infinite linear waveguide antenna array with metal-dielectric structures in the "floquet channel"

An electrodynamics calculation is performed for an infinite waveguide antenna array in the form of open ends of waveguides, in the near zone of which a metal-dielectric structure is located. This metal-dielectric structure is located in the "Floquet channels" and is a combination of a dielectric coating over the antenna array and horns. In this case, the horns are not a continuation of the waveguides, but are located at some distance from them. The space between the waveguides and the horns is filled with a dielectric. A system of equations that allows calculating the reflection coefficients of incident waves in waveguides is obtained.

Implantable Electrical Connector for Reconnecting Injured Neurons, Approach and Design

In contrast to normal injuries, damages of the nervous system are very difficult to repair. In this paper, a connector is designed to reconnect injured nerve to healthy cells. This cord was designed and tested by the full wave and three dimensional electromagnetic modeling. The connector is comprised of three parts, including the conductor, dielectric coating, and second coating with high conductivity. Electromagnetic characteristics need to be unique to work fine, each part is obtained with regard to the distance between two neurons. The combination of materials with conductivity lower than 100 S/m and relative permittivity lower than 8 creates the connection of two neurons up to 35 cm. The connector is realizable by biocompatible polymers.