Presence Of Conduction Research Articles

Role of oxygen vacancy in controlling the resistive switching mechanism for the development of conducting filaments in response of homo and hetero electrodes: Using DFT approach

In the realm of progression of internet of things, artificial intelligence and cloud services, nonvolatile memory devices such as, resistive random access memory (RRAM) emulated the vision of building internet of everything. In this study, robustness of homo- (Ag–Ag, and Pt–Pt), and hetero- (Ag–Pt) top, and bottom electrodes material without and with incorporated oxygen vacancies (Vos) in Sr4Ti4O12 RS layer were investigated. Presence of conductivity in the absence of external electric field proves the presence of nonvolatile memory behavior. Observed RS behavior (in the range of a few Angstroms) may be used to resolve the scalability issue of the proposed RRAM device system. At the same time, oxygen vacancies (Vos) introduced additional functionalities like: additional reduction sites, and reduction of leakage current by quantizing the conduction within RS material. Diffusion barrier elucidated the diffusion mechanism of oxygen vacancies in the considered heterostructure to understand the energy state and the type of RS conduction mechanism. Potential energy line ups, formation energy and electronic properties identified the Vos as principal sites for reduction of Ag atoms by forming metal oxide (Ag-Vos) complex. It is predicted that ReSET, and hence high resistance state (HRS) is harder to achieve with homo-electrodes. The findings of this study provides the effective solution to scalability, stability, and low power consumption in the realm of Pt–Sr4Ti4O12–Ag (with 2Vos mediated in RS layer) based RRAM devices.

Suction influence on magneto-convective fluid flow embedded in a permeable media under internal friction

This work examines the natural convection flow of an incompressible, viscous, and electrically conducting fluid down a vertical flat plate in the presence of conduction, as well as the effects of suction, magnetic field, viscous dissipation, porous medium, and heat generation. The governing momentum and energy equations have numerical solutions. The impacts of suction, heat production, magnetic, porosity, and viscous dissipation parameters on two-dimensional flow are discussed. Graphical representations of the velocity profile, temperature distribution, skin friction, rate of heat transfer, and surface temperature distribution are shown. The presence of porous media and improving suction values improves the friction drag but diminishes the energy transfer. The thermal production parameter raises the energy inside the flow but diminishes the heat transfer coefficient. This work attempts to offer important insights into these intricate processes by examining the effects of controlling factors including magnetic fields, porous medium, and suction parameters. This research conclusion may find applications in coolers, heat exchangers, and environmental remediation technologies that are more effective, advancing engineering and sustainable practices.

The choice of method of electroneuromyogaphy in remote consequences of gunshot and mine-blast injuries of limb nerves

Objective. Clarification of the nature of damage and degree of functional disorders in the remote consequences of gunshot and mine-blast injuries of limb nerves using neurophysiological techniques (NP) of functional diagnostics (stimulation and needle electromyography), correlation of these data with the nerve damage characteristics determined during surgical interventions (operative findings). Materials and methods. 480 military personnel and civilians, men aged 18-64 years (average age 33.5 years), with gunshot and mine-blast injuries of limb nerves (LNI) within 1 to 11 months after injury were examined. A total of 1400 EMG studies were conducted. Clinical-neurological methods were used to determine the level, degree, and nature of LNI. Results. Among the examined 480 patients, complete nerve damage was detected in 299, and partial in 181. Causes of nerve damage included: shrapnel, gunshot, mine-blast injuries, nerve rupture due to bone fractures, injuries by sharp objects, iatrogenic damage. In 62.3% of cases of complete LNI surgical interventions were performed using the technique of neurotization using branches of donor nerves. Provided anatomical integrity of nerve structures and presence of conductivity during EMG testing, external or internal neurolysis was performed. Surgical intervention timing: up to 6 months post-injury - 68.1% of cases; up to 3 months - 31.9%. Based on the results of comprehensive clinical-NP research, adapted schemes for assessing NP data corresponding to each pathohistological type of LNI were developed, and NP criteria for classifying consequences of LNI into three degrees of severity of functional deficit - mild, moderate, and severe were proposed. Conclusions. Criteria for choosing the optimal NP diagnostic methodology for the remote consequences of gunshot and mine-blast injuries of limb nerves have been determined. Comprehensive clinical-instrumental diagnostics allows to objectify the level and degree of limb nerve damage, signs of neuromuscular apparatus recovery, provides information for planning of the surgical tactics and subsequent rehabilitation therapy.

Acute impact of vein of marshall ethanol infusion combined with anatomical ablation validated by pacing in redo ablation of persistent atrial fibrillation

Abstract Background Catheter ablation with radiofrequency in persistent atrial fibrillation (PeAF) has limited success and a significant proportion of patients requires redo ablation. Several trials showed that addition of vein of Marshall ethanol infusion (Vom-EI) to catheter ablation, compared with catheter ablation alone, increases the possibilities of remaining free of AF. No data are available about the effect on VoM-EI in Pe-AF patients that undergo a redo ablation. Purpose We evaluated acute impact on lesion formation post-VoM-EI and the mitral line block validation after a methodical approach including VoM-EI and check of pulmonary vein isolation (PVI), roof-line, mitral line (ML) and cavo-tricuspid isthmus line in a population of PeAF patients undergone redo ablation. We aimed also the results of a short follow-up. Methods Consecutive patients undergoing redo ablation for PeAF were enrolled. All patients underwent check of PVI, left atrium (LA) roofline and cavotricuspid isthmus line and, if necessary, ablation was completed. In all patients, after a detailed electroanatomical map of the LA (filter at 0.05-0.5 mV if the patient was in sinus rhythm or 0.05-0.3 mV in the case of AF), we proceeded with the VoM-ETHO. LA map was thus repeated to assess the extension of the newly-formed low voltage area (LVA). According to the newly-formed LVAs, the validation of mitral line was obtained by the evidence of bidirectional block. In presence of conduction through the mitral line also after endocardial revision, we proceeded to mapping and ablating in the CS epicardial gaps in the "anchored wall" or in the "free-wall"of the great cardiac vein (GCV). Results Twenty consecutive patients (64±8 years and 65% male) undergone redo ablation for AF with VoM-EI were included in this study. All patients underwent PVI in the previous procedure but only in 11 roof line has been performed. In twenty patients (52%) reconnection of PV was observed (12/20 in right superior pulmonary vein). In 4/11 roof line was not complete. The medium value of basal LA-LVAs was 3.38土5.27 cmq and the newly-formed LVAs after the VoM-EI procedure was 9.21土5.63 cmq. All patients achieved bidirectional block validated across ML: in 8/20 after epicardial gaps ablations into the anchored wall of GCV and in 6/20 after epicardial gaps ablation in the free wall of GCV. The ML procedural time was 18.82土12.79 minutes. The number of radiofrequency irrigation was 20.11土10.56. No major complications occurred. Five patients had VOM dissection without consequences. During a short follow-up period (6土5 months), only one patient had AF recurrences after the blanking period of one month. Conclusions VoM ethanol ablation added to PVI and linear lesions in the context of a methodical and anatomical approach during redo ablation of PeAF patients seems to have promising results and to be safe. Longer follow-up is needed to understand the role of this technique in redo ablation.

Effect of temperature in formation of nanocrystal on chemically deposited (Cd-Zn) S: CdCl2; La, Eu films

Results of Photoconductivity (PC) and Photovoltaic (PV) studies for (Cd-Zn)S: CdCl2;La,Eu films presented in different temperature of depositions along with Thiophenol (TP) and Poly Vinyl Chloride (PVC) using as a capping agent. Films have been characterized using Photoconductivity excitation spectra, optical absorption, Photoluminescence (PL), X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). The band gap of such films is evaluated by Photoconductivity excitation spectra and optical absorption. The direct optical band gap of such films was found in the range 2.74-3.04 eV for different deposition temperature. These changing of band gap suggesting the quantum confinement effect in the developed nanoscale size of the particles. The PL spectra of both films nanoparticles showed emission peaks at 436nm, 461nm, 480nm, 504nm and 536nm respectively. SEM micrograph shows the morphological structure and better growth conduction in presence of capping agent at low temperature deposition. Results of XRD studies are associated to different prominent lines of CdS and ZnS. Both studies represent average particle sizes of the order 5.49 – 9.125Å.

Variation of Thermal Conductivity on Two-Dimensional Hydromagnetic Flow of Thermophoretic Forces: Impact of Suction/Blowing

The novelty of thermal conductivity is the transmission of warmth from warmer to cooler portions of a body ensuing in balancing of temperature. Owing to importance of thermal conductivity in engineering technologies, a finite difference scheme is developed to study the originality of thermal conductivity in a two-dimensional fluid motion in assembly with thermophoretic forces, variable thermal conductivity and viscous dissipative heat over a permeable horizontal surface. The thermophoretic effect is included in the concentration boundary layer equation and the formulation has adopted by Talbot-Cheng-Scheffer-Willis (1980). A suitable similarity transformation is adapted to convert the leading PDEs to non-linear ordinary differential equations in non-dimensional form. A well-tested, numerically stable finite difference scheme in connection with Bvp4c is employed via MATLAB code for the conservation of equations under the appropriate transformed boundary conditions. The impact of thermophoretic forces and thermal conductivity in presence of suction/blowing over the fluid velocity and temperature are significant. The thermal conductivity of a substantial is an important property that assistances in the growth of active boiler/refrigerating machineries. In this study, thermophoretic forces (TP) and thermal conductivity (β) enhances the fluid velocity in presence of blowing, while they declines the velocity due to suction. The validity and accuracy of the present model have been checked and found adequate agreement with the previous studies. The importance of such analysis over a horizontal surface have numerous manufacturing, industrial and engineering applications in plastic sheets extrusion, polymer extraction, blowing of glass, manufacture of paper, thermo-electronics and rubber sheets.

Anolyte Enhances Catalyst Utilization and Ion Transport Inside a CO2 Electrolyzer Cathode

Electrochemical CO2 reduction is a promising technology to capture and convert CO2 to valuable chemicals. High Faradaic efficiencies of CO2 reduction products are achieved with zero-gap alkaline CO2 electrolyzers with a supporting electrolyte at the anode (anolyte). Herein, we investigate the effect of anolyte on the electrode properties such as catalyst utilization, ionic accessibility etc. of a CO2 reduction cathode using electrochemical techniques and cell configurations that avoid the complexities related to co-electrolysis. Using 1M KOH as the anolyte and a Cu gas-diffusion-electrode with low Nafion content as the model CO2 reduction electrode, we find that electrode capacitance (proxy for electrochemically active surface area) and ionic conductivity inside the cathode increase approximately 4 and 447 times, respectively, in presence of KOH. Liquid anolyte wets the electrode’s pore structure more efficiently than capillary condensation of feed water vapor. The ionomer coverage is very low, and its distribution inside the electrode is highly fragmented. Surface ion conduction mechanisms inside the electrode are orders of magnitude lower than the bulk ion conduction in presence of anolyte. This study shows that when an anolyte (e.g., KOH) is used, catalyst utilization and ionic accessibility inside the electrode increase significantly.

Impact of thermal conductivity on a horizontal absorbent isothermal wall in a porous medium with heat source and thermophoretic forces: Application of suction/blowing

AbstractThe implanted porous media plays a key role in the performance of the fluid flow. To study the novelty of porous media in a two‐dimensional fluid motion associated with thermophoretic forces, viscous dissipative heat, and variable thermal conductivity over a permeable horizontal surface, we have adopted appropriate similarity transformation to convert the prominent partial differential equations to nonlinear ordinary differential equations in nondimensional form. MATLAB Bvp4c code is employed for the conservation of equations with the appropriate converted boundary conditions and this finite difference scheme is found stable. Furthermore, we have performed a comparison test for validity and accuracy test and established a satisfactory agreement with former literature. The effect of porosity and thermal conductivity in presence of suction/blowing over the fluid velocity and temperature are significant. In this study, the fluid velocity is enhanced for heat generation and thermal conductivity in presence of blowing. The importance of porous media and such study can be experienced in various branches like petroleum engineering, hydrogeology, biophysics, material science, and so forth.

Intrinsic anomalous Hall conductivity of Dirac band in presence of the normal magnetic field

We have studied the intrinsic contribution to anomalous Hall conductivity in presence of the normal magnetic field. A semiclassical approach for calculating the Hall conductivity in presence of the nontrivial Berry phase is used. This method is based on the semiclassical equations of motion with anomalous velocity correction and the Boltzmann transport equation. We present the formulation of anomalous Hall conductivity in this approach. We perform explicit calculations for a two-dimensional system which is described by Dirac Hamiltonian. At zero magnetic field, our results coincide with previous results which are obtained both using the semiclassical method and Kubo formalism. For the strong magnetic field, Hall conductivity decreases as a power-law. The exponent of the power-law behavior for the infinite energy band is 1/3 and for the finite energy band, there is a crossover from 1/3 to1.

Positive magnetoconductivity and inelastic scattering time at low temperatures with magnetic field in InSb semiconductor

In this work, we investigate the temperature dependence of the perpendicular electrical conductivity in presence of magnetic field of InSb sample measurements obtained by Abboudy [16]. First we determine the value of the critical magnetic field BC for which the metal insulator transition (MIT) occurs. On the metallic side of the MIT, we are interested in the study of positive magnetoconductivity as a function of magnetic field by modeling it with complex theoretical models. The validity of these models is tested by calculating and comparing the inelastic scattering time τ ε for each model used.

Thermal analysis through cylindrical porous fin having insulated tip: a hybrid nanomaterial approach

Two kinds of hybrid nanomaterial flow through cylindrical fin are examined under the presence of conduction, convection and radiation. Darcy law model is used to develop the heat equation. With the help of Maple, the non-dimensional thermal equation is numerically solved using the fourth and fifth order of Runge–Kutta Fehlberg. The impact of convection parameter, wet porous parameter, radiation parameter, power law index, ambient temperature and solid volume fraction are discussed through the graphs. It is found that higher values radiation parameter reduces the temperature whereas solid volume fraction enhances the temperature.

Dynamical evolution of anisotropic response of type-II Weyl semimetal TaIrTe4 under ultrafast photoexcitation

Layered type-II Weyl semimetals, such as WTe2, MoTe2, and TaIrTe4 have been demonstrated as a supreme photodetection material with topologically enhanced responsivity and specific sensitivity to the orbital angular momentum of light. Toward future device applications with high performance and ultrafast response, it is necessary to understand the dynamical processes of hot carriers and transient electronic properties of these materials under photoexcitation. In this work, mid-infrared ultrafast spectroscopy is performed to study the dynamical evolution of the anisotropic response of TaIrTe4. The dynamical relaxation of photoexcited carriers exhibits three exponential decay components relating to optical/acoustic phonon cooling and subsequent heat transfer to the substrate. The ultrafast transient dynamics imply that TaIrTe4 is an ideal material candidate for ultrafast optoelectronic applications, especially in the long-wavelength region. The angle-resolved measurement of transient reflection reveals that the reflectivity becomes less anisotropic in the quasi-equilibrium state, indicating a reduction in the anisotropy of dynamical conductivity in presence of photoexcited hot carriers. The results are indispensable in material engineering for polarization-sensitive optoelectronics and high field electronics.

Enhancement of thermal conductivity in presence of macroscopic polarization fields: Role of dispersive transverse phonon modes in nanoscale GaN

The macroscopic polarization effects on lattice thermal conductivity of GaN is theoretically investigated. The explicit contributions from dispersive low and high frequency transverse and longitudinal phonons modes to thermal conductivity are investigated in the presence of polarization fields. Our numerical calculations of the thermal conductivity including polarization fields for the different dimension samples obtain good fit with experimental reports. The significant increase in thermal conductivity is observed at room temperature in presence of macroscopic polarization fields and in the low temperature region effect is found to be negligible. Contribution from high frequency transverse mode phonons to the total thermal conductivity is dominant in nanoscale dimension GaN samples in presence of polarization fields.

Phonon Thermal Hall Effect in Strontium Titanate

It has been known for more than a decade that phonons can produce an off-diagonal thermal conductivity in the presence of a magnetic field. Recent studies of thermal Hall conductivity, κ_{xy}, in a variety of contexts, however, have assumed a negligibly small phonon contribution. We present a study of κ_{xy} in quantum paraelectric SrTiO_{3}, which is a nonmagnetic insulator and find that its peak value exceeds what has been reported in any other insulator, including those in which the signal has been qualified as "giant." Remarkably, κ_{xy}(T) and κ(T) peak at the same temperature and the former decreases faster than the latter at both sides of the peak. Interestingly, in the case of La_{2}CuO_{4} and α-RuCl_{3}, κ_{xy}(T) and κ(T) peak also at the same temperature. We also studied KTaO_{3} and found a small signal, indicating that a sizable κ_{xy}(T) is not a generic feature of quantum paraelectrics. Combined to other observations, this points to a crucial role played by antiferrodistortive domains in generating κ_{xy} of this solid.

Bulk and Few‐Layer 2D, p‐MnPS3 for Sensitive and Selective Moisture Sensing

AbstractIn this study, the humidity sensing properties of two dimensional (2D), few‐layer p‐MnPS3 is explored. Few‐layer of p‐MnPS3 is obtained by exfoliating highly oriented bulk crystals and assembled as thin films on various substrates. The performance of p‐MnPS3 thin film sandwiched between two similar metal electrodes (Ag or Au) toward various levels of moisture under ambient conditions is investigated. The results depict that p‐MnPS3 nanosheets based humidity sensors are highly sensitive and show fast response and recovery times with good repeatability. It is observed that the resistance of the films decreases five to six orders of magnitude with a change in relative humidity (RH) from 0% to 98%. A fast response time of ≈1–2 s and recovery time of ≈4 s are observed. The mechanism of sensing is understood based on AC impedance spectroscopy. Extrinsic mechanism such as filamentary conduction is ruled out based on the data obtained using devices with different channel lengths. Ionic conduction within the channel is mainly responsible for the observed increase in conductivity in presence of moisture. The humidity sensors are shown to be effective in monitoring human respiration as well as water evaporation on skin without physical contact.

Heliborne Time Domain Electromagnetic Data Aiding Delineation of Carbonaceous Shale in Southwestern Part of Bijawar Basin and its Implication on Basinal Stratigraphy

Geophysical methods are tools to unravel concealed geological features that enhance knowledge. Heliborne time domain electromagnetic (TDEM) survey carried out over volcano-sedimentary sequence of Palaeoproterozoic Bijawar basin indicated presence of conductor in the western part of the basin. Subsequently boreholes drilled intercepted rhythmites made up of carbonaceous shale and dolomite within Bajno dolomite Formation. Measurement of conductivity on core samples established the high conductive carbonaceous shale as the contributor for TDEM response. TDEM signature indicate widespread presence of rhythmites in the western part of Bijawar basin reflecting different hydrodynamic condition from other parts of Bajno dolomite. Thus, Bajno dolomite Formation is classified into two members viz. Tigoda member and Sarwa member.

Hydroxide Ion Highway Constructed by Orderly Aligned Quaternary Ammonium Groups in Anion Exchange Membranes

Self-assembly of Gemini surfactants (maleic alkylene group diethylbis [octyl dimethyl bromide], abbreviated as G16-2-16) were used to form reversed micelles by introducing sodium salicylate (NaSal) into chloroform solution of PSF (polysulfone). The rheological measurements indicated that micelles had been formed. The internal surface of micelles were full of orderly arranged quaternary ammonium (QA) groups as cationic active sites. Then we characterized the composite membranes which were introduced micelles, it turned out that, the OH− conductivity in presence of NaSal was higher than the absence one, indicating that the formation of reversed micelles arranged the cationic active sites more orderly, resulted in improving the anionic conductivity by 40–80%, especially under low values of water uptake and ion exchange capacity condition, which provided a kind of approach of enhancing OH− migration efficiency without sacrificing its dimensional stability and mechanical properties. The composite membranes also showed an outstanding thermal stability. And 240 h high temperature alkaline-stable test (10 M NaOH) revealed that the largest decline of OH− conductivity was only round about 4%, which showed excellent alkaline resistance stability.

Analysis of Conduction and Radiation Heat Transfer in a Differentially Heated 2‐D Square Enclosure

Radiative heat transfer with and without conduction in a differentially heated 2‐D square enclosure is analyzed. The enclosure with diffuse gray boundaries contains radiating and/or conducting gray homogeneous medium. Radiatively, the medium is absorbing, emitting and scattering. On the south boundary, four types of discrete heated regions, viz., the full boundary, the left one‐third, left two third and middle one third, are considered. In the absence of conduction, distributions of heat flux along the south boundary are studied for the effect of extinction coefficient. In the presence of conduction, distributions of radiation, conduction and total heat fluxes along the south boundary are analyzed for the effects of extinction coefficient, scattering albedo, conduction–radiation parameter, and south boundary emissivity. Effects of these parameters on centerline temperature distribution are also studied. To assess the performance of three commonly used radiative transfer methods, in all cases, the radiative transfer equation is solved using the discrete ordinate method (DOM), the conventional discrete ordinate method (CDOM) and the finite volume method (FVM). In the combined mode problem, with volumetric radiative information known from one of the three methods, viz., DOM, CDOM, and FVM, the energy equation is solved using the finite difference method (FDM). In all cases, the results from FDM‐DOM, FDM‐CDOM, and FDM‐FVM are in good agreement. Computationally, all three sets of methods are equally efficient.

The Alternative Expression of Lichtenecker's Logarithmic Mixture Formula and Its Application to the Broadband Dielectric Spectroscopy of BaTiO3-Ni0.5Zn0.5Fe2O4 Composites

The experimental data of xBaTiO3 – (1-x)Ni0.5Zn0.5Fe2O4 (BT-NZF) composites with volume ratios x = 0.466, 0.567 and 0.67 are analysed using Lichtenecker's logarithmic mixture formula and its newly suggested alternative expression. Application of Lichtenecker's logarithmic mixture formula is limited by the influence of conductivity to the response of the effective permittivity. Therefore an alternative expression, that allows constituents behaviour of the composite to be described separately by changing frequency with a fixed volume fraction, is suggested. For the present purpose, it is assumed that the real part of each component has no dispersion and is equal to the static permittivity of pure material, while the imaginary part is dependent on the presence of conductivity. By applying the alternative expression for each of the composition over a broad frequency and temperature ranges separately, the parameters obtained are analysed and compared. The composite with the volume ratio of x = 0.466 exhibits moderate deviation from the other two compositions, presumably caused by the difference in their homogeneities, defectivities, grain-size effects and/or microstructural changes during the preparation and sintering process.

Relaxation dielectric spectra in the presence of conductivity

A concept of analyzing complex dielectric spectra under the assumption of a simultaneous contribution from two dispersion mechanisms to the dielectric response is proposed. It allows describing complex dielectric spectra of ferroelectrics and some conducting materials with unusual dispersions.