Electric Current Changes Research Articles

Nanopore Testing: A Paradigm Shift in Ovarian Cancer Screening

Nanopore Testing: A Paradigm Shift in Ovarian Cancer Screening

Energy saving using a frequency converter in asynchronous motor operating modes

This scientific article discusses asynchronous motors using single-season and multi-season sizes, their optimized modes for scalar and vector control. First of all, detailed information was given about the operating modes of the optimizer, followed by changes in voltage, magnetic current and electric current. With scalar control, mode optimizers are optimized for maximum and minimum electric current, while with vector control, optimization is achieved through direct or indirect action on the rotor. Based on the above, complex optimization methods are considered in detail and graphs from their mathematical model are presented. In this case, the conditional minima of the electric current in the lower region and the local minima of the electric current in the lower region are shown on the graphs. The data obtained were compared with complex optimization and extraterrestrial characteristics. As a result of the article, the mentioned methods proposed a scheme of the final optimization structure and a system of equations that mathematically represent them all. The results obtained showed that even with the help of a simple circuit, optimal control of asynchronous motors can be achieved with good results when using optimizers of complex modes, rather than scalar or vector current control. In the future, the control of this method will become the basis for solving energy-saving problems achieved through the use in asynchronous motors with a short-circuited rotor, which are regulated by a frequency switch located in pumping plants of industrial enterprises.

Rapid and Quantitative Detection of Lung Cancer Biomarker ENOX2 Using a Novel Aptamer in an Electrochemical DNA-Based (E-DNA) Biosensor.

To overcome early cancer detection challenges, diagnostic tools enabling more sensitive, rapid, and noninvasive detection are necessary. An attractive cancer target for diagnostic blood tests is human Ecto-NOX disulfide-thiol exchanger 2 (ENOX2), expressed in most human cancer types and regularly shed into blood sera. Here, we developed an electrochemical DNA-based (E-DNA) biosensor that rapidly detects physiologically relevant levels of ENOX2. To identify ENOX2-binding aptamers that could potentially be used in a biosensor, recombinantly expressed ENOX2 was used as a binding target in an oligonucleotide library pull-down that generated a highly enriched ENOX2-binding aptamer. This candidate aptamer sensitively bound ENOX2 via gel mobility shift assays. To enable this aptamer to function in an ENOX2 E-DNA biosensor, the aptamer sequence was modified to adopt two conformations, one capable of ENOX2 binding, and one with disrupted ENOX2 binding. Upon ENOX2 introduction, a conformational shift to the ENOX2 binding state resulted in changed dynamics of a redox reporter molecule, which generated a rapid, significant, and target-specific electrical current readout change. ENOX2 biosensor sensitivity was at or below the diagnostic range. The ENOX2 E-DNA biosensor design presented here may enable the development of more sensitive, rapid, diagnostic tools for early cancer detection.

Comparative study of the current-carrying tribological properties of carbon graphite composites with different hardnesses

To investigate the effect of sliding speed and electrical current on the current-carrying friction performance of carbon brushes with different hardnesses. In this paper, two carbon-graphite material samples with different hardnesses manufactured by a powder metallurgical process were prepared. And a pin-disc current-carrying friction tester was used for testing. The results showed that the difference in hardness has a noticeably different effect on the sliding contact resistance and interface temperature rise of the material. As the electric current changes, the material with low hardness exhibited good adaptability. Then, the adhesive wear occurred for all materials of different hardnesses, and it changed to abrasive wear mainly with increasing electrical current. As the sliding speed increased, the wear rate of low-hardness material dropped, while the opposite trend was observed for high-hardness material. The increased sliding speed does not generate remarkable damage to the contact surface of the high-hardness material, which demonstrated good resistance to mechanical shocks.

The influence of temperature on the electrical conductivity of GaN piezoelectric semiconductors

GaN is an excellent material choice for power devices due to its excellent properties such as super wide bandgap width and high electron mobility. However, the problem of temperature affects the thermo reliability and hinders the potential of GaN devices. In this paper, the electrical properties of GaN under temperature have been studied by the combination of numerical simulation and experimental research. The electric current change and electrical resistivity of polarized and depolarized GaN semiconductor samples were tested in an environment-test cabinet. Based on the influence of temperature, the expression of the resistivity curve vs temperature was established for polarized and depolarized GaN samples. It is shown that the resistivity model predictions are consistent with experimental results. The I–V characteristic curves under different temperatures were also measured. Thus, such a model is instructive to the reliable design of GaN high-temperature devices. The findings will be instructive to the optimal design of GaN electronic components.

Study on Output Characteristics of 20 kV/100 ns Nonlinear GaAs Photoconductive Semiconductor Switch

In this paper, the output electric pulse characteristics of gallium arsenide photoconductive semiconductor switch (GaAs PCSS) with bias voltage of 20 kV and pulse width of about 100 ns are studied. By designing the reflection and transmission optical paths, the absorption rate of the trigger optical of the GaAs PCSS at a wavelength of 1064 nm was measured to be 24.8%. When the bias voltage is 16 kV-20 kV, the avalanche multiplication rates of carriers are calculated respectively. The relationship between the output current waveform and the residual charge in the energy storage capacitor is analyzed when the bias voltage is 20 kV. And the trend of GaAs PCSS electric field intensity and current waveform change with time. This research will be helpful for the application design of GaAs PCSS under the nonlinear mode with special requirements, and has important significance for the application of frontier science.

Sensitive and Specific Detection of Estrogens Featuring Doped Silicon Nanowire Arrays.

Estrogens and estrogen-mimicking compounds in the aquatic environment are known to cause negative impacts to both ecosystems and human health. In this initial proof-of-principle study, we developed a novel vertically oriented silicon nanowire (vSiNW) array-based biosensor for low-cost, highly sensitive and selective detection of estrogens. The vSiNW arrays were formed using an inexpensive and scalable metal-assisted chemical etching (MACE) process. A vSiNW array-based p-n junction diode (vSiNW-diode) transducer design for the biosensor was used and functionalized via 3-aminopropyltriethoxysilane (APTES)-based silane chemistry to bond estrogen receptor-alpha (ER-α) to the surface of the vSiNWs. Following receptor conjugation, the biosensors were exposed to increasing concentrations of estradiol (E2), resulting in a well-calibrated sensor response (R 2 ≥ 0.84, 1-100 ng/mL concentration range). Fluorescence measurements quantified the distribution of estrogen receptors across the vSiNW array compared to planar Si, indicating an average of 7 times higher receptor presence on the vSiNW array surface. We tested the biosensor's target selectivity by comparing it to another estrogen (estrone [E1]) and an androgen (testosterone), where we measured a high positive electrical biosensor response after E1 exposure and a minimal response after testosterone. The regeneration capacity of the biosensor was tested following three successive rinses with phosphate buffer solution (PBS) between hormone exposure. Traditional horizontally oriented Si NW field effect transistor (hSiNW-FET)-based biosensors report electrical current changes at the nanoampere (nA) level that require bulky and expensive measurement equipment making them unsuitable for field measurements, whereas the reported vSiNW-diode biosensor exhibits current changes in the microampere (μA) range, demonstrating up to 100-fold electrical signal amplification, thus enabling sensor signal measurement using inexpensive electronics. The highly sensitive and specific vSiNW-diode biosensor developed here will enable the creation of low-cost, portable, field-deployable biosensors that can detect estrogenic compounds in waterways in real-time.

Design of an omnidirectional camouflage device with anisotropic confocal elliptic geometry in thermal-electric field

SummaryThe designed confocal elliptical core-shell structure can realize the omnidirectional camouflage effect without disturbing temperature and electric potential profiles as the directions of heat flux and electric current change. Based on the anisotropy of the confocal ellipse, the anisotropic effective parameters of the confocal elliptical core-shell structure are derived under different heat flux and electric current launching. Then, the matrix material should be anisotropic as the effective parameters to satisfy the omnidirectional camouflage effect, which is demonstrated numerically. In addition, we present a composite structure to realize the anisotropic matrix. The experimental results show that the camouflage device embedded in the composite structure can eliminate the scattering caused by the elliptical core under different directions of heat flux and electric current, thus achieving the omnidirectional thermal-electric camouflage effect experimentally. The omnidirectional camouflage effect in thermal and electric fields can greatly widen the application fields of this device with anisotropic geometry.

Molecular Recognition by Silicon Nanowire Field-Effect Transistor and Single-Molecule Force Spectroscopy.

Silicon nanowire (SiNW) field-effect transistors (FETs) have been developed as very sensitive and label-free biomolecular sensors. The detection principle operating in a SiNW biosensor is indirect. The biomolecules are detected by measuring the changes in the current through the transistor. Those changes are produced by the electrical field created by the biomolecule. Here, we have combined nanolithography, chemical functionalization, electrical measurements and molecular recognition methods to correlate the current measured by the SiNW transistor with the presence of specific molecular recognition events on the surface of the SiNW. Oxidation scanning probe lithography (o-SPL) was applied to fabricate sub-12 nm SiNW field-effect transistors. The devices were applied to detect very small concentrations of proteins (500 pM). Atomic force microscopy (AFM) single-molecule force spectroscopy (SMFS) experiments allowed the identification of the protein adsorption sites on the surface of the nanowire. We detected specific interactions between the biotin-functionalized AFM tip and individual avidin molecules adsorbed to the SiNW. The measurements confirmed that electrical current changes measured by the device were associated with the deposition of avidin molecules.

The characteristics of microplasma discharge propagation over 
 the titanium surface covered with a thin oxide film

The propagation and structure of a microplasma discharge initiated in vacuum by a pulsed plasma flow with a density of 1013 cm–3 on the surface of a titanium sample covered with a 
 thin continuous dielectric titanium oxide film with a shickness of 2–6 nm were studied experimentally when the electric current of the discharge changes from 50 A to 400 A. 
 It was found that the microplasma discharge glow visually at the macroscale has a branched structure of the dendrite type, which at the microscale consists of a large number 
 of brightly glowing “point” formations – cathode spots localized on the metal surface. The resulting erosion structure on the titanium surface is visually “identical” to the structure of 
 the discharge glow and consists of a large number of separate non-overlapping microcraters with characteristic sizes from 0.1–3 μm, which are formed at the sites of localization of 
 cathode spots at distances of up to 20 μm from each other. It was found that the propagation of a single microplasma discharge over the titanium surface covered with a thin oxide film a 
 thickness of 2–6 nm occurs at an average velocity of 15–70 m/s when the amplitude of the discharge electric current changes in the range of 50–400 A. In this case, the microplasma 
 discharge propagation on the microscale has a “jumping” character: the plasma of “motionless” burning cathode spots, during their lifetime 1 μs, initiates the excitation of new 
 microdischarges, which create new cathode spots at localization distances of 1–20 μm from the primary cathode spots. This process repeated many times during a microplasma dis-
 charge pulse with a duration from 0.1 ms to 20 ms.

Threshold behaviors of direct and Hall currents in topological spin-Hall effect

We study spin-dependent direct and Hall conductivities in the threshold region of Fermi energy, ɛF=2J, where J is the exchange integral between the conduction electron spins and the skyrmion spin texture. For ɛF at the threshold value and above the spin-down electrons are allowed to exist. We find the two in the direct and four narrow peaks in the Hall conductivities for Fermi energies slightly below the threshold value. The found effects are dramatic because the electric current changes by approximately eight times in the narrow range of gate voltages (∼4 meV). The values of the peaks strongly depend on skyrmion size. For small and very large skyrmion sizes the peak amplitudes are small compared to the conductivity absolute values. At the skyrmion radius a=6nm and very light conduction electrons, m∗∼10−2me, the extrema are the most pronounced. The temperature evolution reveals the strong smearing effect where the peak-wise behavior completely disappears at room temperatures. Spin transistor could be considered for possible applications where in the narrow region of gate voltage the sharp conductivity change occurs.

Removal of Pathogenic pollutants using electrocoagulation using aluminium electrodes

Pathogenic contamination of fresh waste bodies is some of the most harmful types of water contamination where in aquatic environment the pathogenic microorganisms can reproduce, which may pollute the marine environment overall. In addition, there are serious side effects with microbial infection. Some many pasteurization processes, like membrane separation and additives, have therefore been used to remove microorganisms from wastewater. Most of these processes are inefficient or hazardous, like the chemical treatment. Lately, electrocoagulation process, due to the environmental safety and comparatively low operational costs, has paid considerable attention to remove pathogenic contamination of sewage treatment plant effluent. During this analysis, the consequences of the changing of the electrical current change from 0.5 to 1.5 mA/cm2 were examined on the ability of aluminium-based electrocoagulation unit for sewage treatment by disabling pathogenic pollutants. The findings demonstrated that the density of the current was increased to increasing the E. coli elimination (an indicator of pathogenic pollutants removal) to reach a current density of 2 mA/cm2 the strongest deactivation (83.2%). Rising the current density increases the bacterial removal. However, the increase in the current density increases the treatment cost.

Gas emission from human skin positions detected by vertical-channel organic semiconductor sensor

The gas emitted from the human skin is collected and measured by the highly sensitive room-temperature organic semiconductor gas sensor with vertical electrical channel. Among various positions, palms give the highest signal and heads follow. The signals are collected from 4 healthy men and 4 healthy women. The response is defined as the percent of electric current change at 5 V in 30 s after the measurement. By comparing the responses from sensors made by three different organic materials, the dominant component from the palm has different pattern from ammonia. Gas chromatography study suggests aldehydes in the palm gas. Different people show consistent results but slightly depending on sex. The body skin measurement can be extended to patients in order to establish the connection between skin gas and the diseases situations.

DYANMIC ANALYSIS OF SHAPE MEMORY ALLOY OSCILLATORS IN ACTIVE SUSPENSION SYSTEM

Smart materials have a growing technological importance due to their unique thermomechanical characteristics. Shape memory alloys belong to this class of materials being easy to manufacture, relatively lightweight, and able to produce high forces or displacements with low power consumption. These aspects could be exploited in different applications including vibration control. A dynamic vibration absorber (DVA) can be used as an effective vibration control device. It is essentially a secondary mass, attached to an original system via a spring and damper. The natural frequency of the DVA is tuned such that it coincides with the frequency of unwanted vibration in the original system. This work aims to develop a dynamic vibration absorber with the help of shape memory alloy (SMA) springs in order to attenuate the vibration for a range of excitation frequencies. The experimental apparatus consisted of low-friction cars free to move in a rail. A shaker that provides harmonic forcing excites the system. Special attention is dedicated to the analysis of vibration reduction that can be achieved by considering different approaches exploiting temperature variations promoted either by electric current changes or by vibration absorber techniques. The results established that adaptability due to temperature variations is defined by modulus of stiffness

Current-Dependent Dynamics of Bidirectional Self-Folding for Multi-Layer Polymers Using Local Resistive Heating

Abstract The purpose of this paper is to characterize the dynamics and direction of self-folding of pre-strained polystyrene (PSPS) and non-pre-strained styrene (NPS), which results from local shrinkage using a new process of directed self-folding of polymer sheets based on a resistively heated ribbon that is in contact with the sheets. A temperature gradient across the thickness of this shape memory polymer (SMP) sheet induces folding along the line of contact with the heating ribbon. Varying the electric current changes the degree of folding and the extent of local material flow. This method can be used to create practical three-dimensional (3D) structures. Sheets of PSPS and NPS were cut to 10 × 20 mm samples, and their folding angles were plotted with respect to time, as obtained from in situ videography. In addition, the use of polyimide tape (Kapton) was investigated for controlling the direction of self-folding. Results show that folding happens on the opposite side of the sample with respect to the tape, regardless of which side the heating ribbon is on, or whether gravity is opposing the folding direction. The results are quantitatively explained using a viscoelastic finite element model capable of describing bidirectional folds arising from the interplay between viscoelastic relaxation and strain mismatch between polystyrene and polyimide. Given the tunability of fold times and the extent of local material flow, resistive-heat-assisted folding is a promising approach for manufacturing complex 3D lightweight structures by origami engineering.

Simulation of Hall Effect in Semiconductor for Current Sensors Applications

Hall effect simulation program was designed using a numerical direct and iterative method. The validity of this program was checked by comparing it with practical results. This program can be used as the basis for designing electrical current sensors, magnetic sensors, and integrated circuits depending on Hall effect, Moreover the program support researchers for their practical tests. The designed program was used to study the effect of different parameters on the designing of sensors built on the Hall effect, these parameters are magnetic field, electrical current, type of semiconductor, and the dimension of material. The results showed that the Hall voltage is sensitive to the magnetic field and electric current changes, while the hall voltage is constant with a variation of the sample dimensions. The results showed that the Hall experiment is sensitive to these parameters, especially to the thickness. The simulation software results will enhance the practical applications of the sensors.

Research of a bi-directional DC-DC converter integrated in electric car power installation

This article presents the results of the simulation study of the bi-directional DC converter, including the time diagrams of the electric vehicle speed, voltage and current changes in various experiments, Also presented are the results of efficiency change and charge level, when using a bi-directional converter as well as without using it. The HFEDC (Highway Fuel Economy Driving Schedule) model was chosen for the simulation of the electric vehicle drive model using units simulating standardized driving cycles and as an algorithm for changing the vehicle’s control signal. Studies of the operating modes of the electrical equipment and the electric vehicle with the DC voltage conversion device in the power circuit of the DC source have been carried out by computer simulation in specialized programs for the study of dynamic systems. The simulation model of the reversible DC converter in the electrical power equipment of an electric vehicle was constructed on the basis of mathematical models of the individual elements reflecting their real physical properties. The present solution is the use of two-way DC voltage converters in the power conversion systems of modern electric drives, including the electric propulsion systems of prospective vehicles improves the efficiency of these systems.

Bioremediation of polycyclic aromatic hydrocarbons contaminated soil under the superimposed electric field condition

An innovative superimposed electric field (SEF) was designed with the aim to achieve uniform removal of polycyclic aromatic hydrocarbons (PAHs) in soil. Also the influence of SEF on the bioremediation efficiency of PAHs was investigated in compared with the common electric field (CEF). Five experiments were conducted in this study, namely EK-CEF (applied CEF), EKB-CEF (CEF enhanced bioremediation), EK-SEF (applied SEF), EKB-SEF (SEF enhanced bioremediation), and Bio (bioremediation). The results indicated that electric field with periodically reversed polarity could effectively prevent the occurrence of large changes in soil pH, temperature, and electric current. The electric field intensity of SEF was concentrated in the range of 0.5–1.5 V/cm, and the difference between the maximum and minimum PAHs removal percentage in EK-SEF was just 5.4%, in comparison to 14.8% in EK-CEF. The bioremediation promoting effect did not show significant difference between SEF and CEF. Compared to Bio, the removal percentages of the 5-ring and 6-ring PAHs attributed to the degrading bacteria were much higher in EKB-SEF and EKB-CEF. Moreover, the microbial number increased with the distance away from electrodes, and the microbial community changed correspondingly. All these would be resulted in differences removal efficiencies among different PAHs components. Despite its intrinsic advantages, the influence of SEF on soil physicochemical and biological properties needs further study.

Electron microscopy observation of electric field-assisted sintering of stainless steel nanoparticles

The intrinsic role of electrical current on the electric field-assisted sintering (EFAS) process of stainless steel 316L nanoparticles has been revealed by both ex situ and in situ experiments. A novel device on the Si chip has been designed and fabricated to fit into the sample holder of a transmission electron microscope for these experiments. The evolution of nanoparticle morphology and microstructures during the EFAS process has been studied using scanning electron microscopy and transmission electron microscopy, which has been combined with the simultaneous measurement of the electric voltage and current changes. A preliminary four-stage mechanism for the EFAS process of stainless steel 316L nanoparticles has been proposed based on these experimental investigations.

Dynamic modelling of alkaline self-pressurized electrolyzers: a phenomenological-based semiphysical approach

This paper proposes a phenomenological based semiphysical model (PBSM) for a self-pressurized alkaline electrolyzer. The model, based on mass and energy balances, represents the dynamic behaviour of hydrogen and oxygen production using electrolysis. The model allows to anticipate operational variables as dynamic responses in the concentrations of the electrolytic cell, and variations in both, level and pressure, at the gas separation chambers due to the change in electric current. The model parameters have been adjusted based on experimental measurements taken from an available prototype and through a suitable identification process. Simulation results replicate the current dynamic response of the experimental self-pressurized electrolyzer assembly. This model proves to be useful in the improvement of the control of gas production rate in this kind of assemblies, both as a validated simulation platform and as a source of reduced order models for model-based control design.