Fabrication of flexible conductive silk fibroin/polythiophene membrane and its properties

Silk fibroin (SF) film is an insulating material, which can be combined with polythiophene derivatives with electrical conductivity to obtain a flexible conductive material. In this work, poly(3,4-ethylenedioxythiophene) (PEDOT) was used to graft a silk protein film. The hydroxyl radical is formed by activation and oxidation of the silk protein film polymerized with the PEDOT radical formed by oxidation of 3,4-ethylenedioxythiophene to obtain a conductive silk film. The SF/PEDOT film, when tested, showed excellent electrical conductivity with resistance up to 63 Ω·cm−2, good flexibility, mechanical properties, fastness, and biocompatibility.

Metal-wire-embedded alumina insulating material using micro and nanoscale 3D printing for surface flashover mitigation in vacuum

Micro and nanoscale 3D printing technic is applied to fabricate functional insulating material which mitigates surface discharge in vacuum based on the microscopic electron multipactor suppression. The proposed alumina ceramic insulator design consists surface-embedded thin metal wires which introduce a local gradient of secondary electron emission yield, such that the trajectories of multipactor electrons are distorted by accumulated negative surface charges and the secondary electron emission avalanche across the insulator surface is intermitted. Considerable increases of surface flashover threshold and surface charging reduction are verified by experiment. Also, additional efforts are made to determine the optimal size and spatial distribution of the metal wire. A convex-shape flashover voltage trace is observed when increasing the wire width, suggesting a trade-off between the multipactor mitigation and the insulator strength. Wire position between the adjacency of cathode triple junction and middle of the insulator is proved to be favorable for flashover mitigation. The physical details of surface flashover mitigation by the proposed insulator design are revealed by an ab initio particle-in-cell (PIC) simulation code, corroborating the experiment from microscopic aspect.

Thermal insulating materials on liquid glass binder

The article discusses the possibility of creating new inorganic heat-insulating materials based on liquid glass binder and mineral fillers. Within the framework of the article, the influence of various additives such as sawdust, chalk, coal and graphite on the physical and technical properties of an inorganic heat-insulating material is considered. The authors of the article proposed the compositions and conditions for obtaining materials that meet the regulatory requirements for materials and products for building thermal insulation

Enhancement of gain using a multilayer superstrate metasurface cell array with a microstrip patch antenna

This research presents a new idea in the use of wireless communication antennas: it uses a multi-layered array of cells called a superstrate multi-layer metasurface (MTM) and is placed in front of a patch of microstrip antenna to absorb surface waves and prevent them from passing through the insulating material, which reduces the permeability of the insulator and thus improves the Antenna properties, The proposed hexagonal cell with resonators is placed on the flame resistant (FR4) substrate, with a relative permittivity of 4.3 and an area (14×14) mm2 . It was tested when the metasurface layer is 4 mm in front of the patch and the distance between the metasurface layers is 2 mm. The optimum distances were calculated by the sweep parameter, and the improved antenna gain and the input reflection coefficient were obtained together. (S11) has been improved from -31.217 to -38.338 dB and, the gain from 3.28 dB to 6.554 dB.

Methodology for assessing the degree of moisture ingress into the insulation of traction electric motors of diesel locomotives

Objective: To develop a method for assessing the degree of moisture absorption by the traction electric motor (TEM) insulation. Methods: Based on the analysis of one-dimensional diffusion of liquid into the insulating material of the TEM windings, it has been shown that cracks increase its saturation with liquid. The proposed analytical solution for anisotropic diffusion of liquid into a cracked insulating material has been investigated. Results: An analytical model has been developed that describes the ideal moisture absorption according to the Fick's law, and it has been shown that it is suitable for calculating the diffusion of moisture into the insulating materials of the TEM windings. Practical importance: Further research should be aimed at obtaining material properties in a moisture-controlled environment