scholarly journals Charge carriers drift induced THz amplification in dual-layer graphene structure

2021 ◽  
Vol 2015 (1) ◽  
pp. 012094
Author(s):  
I.M. Moiseenko ◽  
V.V. Popov ◽  
D.V. Fateev
Keyword(s):  
Electric Current ◽  
Direct Current ◽  
Spatial Dispersion ◽  
Charge Carriers ◽  
Frequency Range ◽  
Direct Electric Current ◽  
The Real ◽  
Layer Graphene

Abstract The terahertz plasmon amplification in structure based on graphene with spatial dispersion of its hydrodynamic conductivity is investigated theoretically. The spatial dispersion of graphene conductivity is related to accounting of charge carriers pressure forces and direct current in graphene. It was shown that the real part of graphene conductivity becomes negative at THz frequency range due to direct electric current in graphene.

scholarly journals Усиление терагерцовых электромагнитных волн в структуре с двумя слоями графена при протекании постоянного электрического тока: гидродинамическое приближение

2021 ◽  
Vol 55 (8) ◽  
pp. 649
Author(s):  
И.М. Моисеенко ◽  
В.В Попов ◽  
Д.В. Фатеев
Keyword(s):  
Electric Current ◽  
Room Temperature ◽  
Spatial Dispersion ◽  
Terahertz Wave ◽  
Charge Carriers ◽  
Amplification Efficiency ◽  
Terahertz Frequency ◽  
Terahertz Frequency Range ◽  
Direct Electric Current ◽  
Graphene Layers

The amplification of electromagnetic terahertz radiation in a structure with two layers of hydrodynamic graphene with a direct electric current is studied theoretically. The hydrodynamic conductivity of graphene is investigated. It is shown that the real part of the graphene conductivity can be negative in the terahertz frequency range at the drift velocities of charge carriers in graphene that are lower than the phase velocity of the electromagnetic wave. For small wavevectors of a terahertz wave incident on a graphene structure, the spatial dispersion insignificantly contributes to the hydrodynamic graphene conductivity. Because of this, the amplification efficiency does not depend on the direction of currents in each of the graphene layers. It is shown that graphene with direct electric current can be used to create THz amplifiers operating at room temperature.

The Isotope Effect of a Direct Electric Current through Liquid and Solid Metals

1956 ◽  
Vol 11 (1) ◽  
pp. 71-75
Author(s):  
E. Haeffner ◽  
Th. Sjöborg ◽  
S. Lindhe
Keyword(s):  
Liquid Metal ◽  
Electric Current ◽  
Isotope Effect ◽  
Direct Current ◽  
Capillary Tube ◽  
Isotope Separation ◽  
Direct Electric Current ◽  
Separation Effect ◽  
A Current

The isotope separation effect of a direct electric current in a liquid metal is demonstrated by passing a current through mercury, which is enclosed in a capillary tube. The second part of the paper deals with an attempt of establishing an isotope effect when a direct current is passed through an uranium wire.

scholarly journals Stimulation of Osteogenesis by Direct Electric Current (Review)

2019 ◽  
Vol 25 (3) ◽  
pp. 185-191
Author(s):  
E. N. Ovchinnikov ◽  
M. V. Stogov
Keyword(s):  
Stem Cells ◽  
Electric Current ◽  
Direct Current ◽  
English Language ◽  
Direct Electric Current ◽  
Metal Implants ◽  
Electromagnetic Stimulation ◽  
Analytical Review ◽  
Differentiation And Proliferation ◽  
Stimulation Of

Background. Stimulation of osteogenesis in the treatment of certain orthopedic and trauma pathologies is a necessary element to ensure the best clinical outcome. The purpose of the present analytical review is to analyze the literature data in respect of evaluating the approaches and possibilities to stimulate osteogenesis using direct current. Methods. The search for literature data was performed in the open electronic databases of scientific literature PubMed and eLIBRARY under the following keywords and their combinations: “osteogenesis”, “reparative osteogenesis”, “direct electric current”, “orthopaedics”, “traumatology”, “electric current” (in Russian as well as in English language ). Results. According to some fundamental research, the stimulating effect of direct current lies is both in stimulating differentiation and proliferation of osteoblasts, and in stimulating differentiation of stem cells, mainly mesenchymal stem cells of bone marrow and adipose tissue, in the process of osteogenesis. The following stimulating technologies were developed and clinically tested to date: 1 — direct exposure of bone to the direct current; 2 — capacitive coupled stimulation; and 3 — inductive coupled (electromagnetic) stimulation. Analysis of clinical practice demonstrated that the first technology is most effective in terms of osteoreparation, but less safe than technology 2 and 3. It should be noted that there are no clear indications and modes of application for the abovementioned methods. Based on the data collected in the present analysis, technology 1 is considered by authors as the most promising. Safety of technology 1 can be enhanced by application of metal implants as electrodes in case those are planned to be used for medical reasons: wires, rods, staples, fixators, etc. Conclusion. Use of electric current to stimulate bone formation is a promising method which requires clarification in respect of indications and application modes.

scholarly journals A Radio Frequency Electric Current Enhances Antibiotic Efficacy against Bacterial Biofilms

2004 ◽  
Vol 48 (12) ◽  
pp. 4662-4664 ◽  
Author(s):  
R. Caubet ◽  
F. Pedarros-Caubet ◽  
M. Chu ◽  
E. Freye ◽  
M. de Belém Rodrigues ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Electric Current ◽  
Direct Current ◽  
Bacterial Biofilms ◽  
Direct Electric Current ◽  
Bioelectric Effect ◽  
Alternating Electric Current ◽  
Antibiotic Efficacy ◽  
Polar Parts ◽  
Biofilm Matrix

ABSTRACT Bacterial biofilms are notably resistant to antibiotic prophylaxis. The concentration of antibiotic necessary to significantly reduce the number of bacteria in the biofilm matrix can be several hundred times the MIC for the same bacteria in a planktonic phase. It has been observed that the addition of a weak continuous direct electric current to the liquid surrounding the biofilm can dramatically increase the efficacy of the antibiotic. This phenomenon, known as the bioelectric effect, has only been partially elucidated, and it is not certain that the electrical parameters are optimal. We confirm here the bioelectric effect for Escherichia coli biofilms treated with gentamicin and with oxytetracycline, and we report a new bioelectric effect with a radio frequency alternating electric current (10 MHz) instead of the usual direct current. None of the proposed explanations (transport of ions within the biofilm, production of additional biocides by electrolysis, etc.) of the direct current bioelectric effect are applicable to the radio frequency bioelectric effect. We suggest that this new phenomenon may be due to a specific action of the radio frequency electromagnetic field upon the polar parts of the molecules forming the biofilm matrix.

Mechanical and Microwave Dielectric Properties of Csf/Si3N4 Composites

2007 ◽  
Vol 546-549 ◽  
pp. 1661-1664
Author(s):  
Xiao Yan Wang ◽  
Fa Luo ◽  
Dong Mei Zhu ◽  
Wan Cheng Zhou ◽  
Hong Huan Wu
Keyword(s):  
Carbon Fibers ◽  
Microwave Dielectric Properties ◽  
Xrd Analysis ◽  
Network Analyzer ◽  
Hot Press ◽  
Frequency Range ◽  
The Real ◽  
Microwave Dielectric ◽  
Hot Press Sintering ◽  
Sintering Method

Csf/Si3N4 composites were prepared by hot-press sintering method using α-Si3N4 power, short chopping carbon-fiber and sintering additives. XRD analysis showed that the α-Si3N4 was almost completely transferred into β-Si3N4. The SEM micrographs of fractured surfaces showed that special network developed by rod-like β- Si3N4 grains. The flexure strength of 590±10MPa, and fracture toughness of 7.94±0.1MPa·m1/2 were achieved for the samples incorporated with 0.5wt% the carbon fibers .The microwave dielectric property of Csf/Si3N4 composites was measured at a frequency range of 8.2~18GHz by E8362B PNA series network analyzer. The real part (ε ′ ) of the permittivity of the Csf/Si3N4 composites increases from 10 to 58 with the rise of the content of carbon fibers in the composites, as well as the imaginary part increases from 0.03 to 98 at frequency of 9.375GHz. A strong frequency dependence of the real part was observed both in X and Ku bands.

A Frequency Reconfigurable Antenna based on Few Layer Graphene

2021 ◽  
Vol 36 (5) ◽  
pp. 542-547
Author(s):  
Sheng-lan Wang ◽  
Jing-Song Hong ◽  
Yan Deng ◽  
Zhi-jian Chen
Keyword(s):  
Experimental Evidence ◽  
Bias Voltage ◽  
Direct Current ◽  
Surface Impedance ◽  
Microstrip Line ◽  
Reconfigurable Antenna ◽  
Layer Graphene ◽  
Direct Current Bias ◽  
Few Layer Graphene ◽  
Frequency Reconfigurable Antenna

In this paper, a frequency reconfigurable antenna was presented. This antenna is made up of a square loop and a microstrip line with a gap, in which the few layer graphene (FLG) sheet is located to achieve frequency reconfigurable. FLG is likes a lumped resistor with resistance. And the surface impedance can be adjusted by applying a direct current bias voltage, which obtains two work modes that imitate switch. Additionally, the experimental evidence show the proposed frequency reconfigurable antenna can provide a tunable bandwidth.

Antimicrobial Efficacy of Exposure of Medical Metal Implants to Direct Electric Current

2022 ◽  
Author(s):  
E. N. Ovchinnikov ◽  
N. V. Godovykh ◽  
O. V. Dyuryagina ◽  
M. V. Stogov ◽  
D. N. Ovchinnikov ◽  
...  
Keyword(s):  
Electric Current ◽  
Antimicrobial Efficacy ◽  
Direct Electric Current ◽  
Metal Implants

Properties of Bi and BiSb Nano-Dimensional Layers in Thz Frequency Range

2020 ◽  
Vol 312 ◽  
pp. 206-212
Author(s):  
Ivan L. Tkhorzhevskiy ◽  
Anton D. Zaitsev ◽  
Petr S. Demchenko ◽  
Dmitry V. Zykov ◽  
Aleksei V. Asach ◽  
...  
Keyword(s):  
Phase Shift ◽  
Time Domain ◽  
Terahertz Wave ◽  
Film Structure ◽  
Charge Carriers ◽  
Frequency Range ◽  
Terahertz Time Domain Spectroscopy ◽  
Antimony Content ◽  
Mobility Of Charge Carriers ◽  
Substrate Film

In the present paper we demonstrate and compare different properties of Bi and Bi1-xSbx thin films placed on polyimide (PI) substrate in frequency range from 0.2 to 1.0 THz. Bi films with a thickness of 40, 105 and 150 nm have been studied as well as 150 nm Bi1-xSbx solid solutions with Sb concentration of 5, 8, 12 and 15 %. An effective refractive index and permittivity of whole substrate/film structures have been derived by using terahertz time-domain spectroscopy (THz-TDS) method. These measurements have shown the positive phase shift in PI substrate with a thickness of 42 μm and revealed that it is barely transparent in studied frequency range, but the whole substrate/film structure provides the negative phase shift of terahertz wave. It was shown that the permittivity depends on mobility of charge carriers which is driven by film thickness and antimony content.

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