Effect Of Current Direction Research Articles

Effect of current direction and muscle activation on motor cortex neuroplasticity induced by repetitive paired-pulse transcranial magnetic stimulation.

Repetitive paired-pulse transcranial magnetic stimulation (TMS) at indirect (I)-wave periodicity (iTMS) can increase plasticity in primary motor cortex (M1). Both TMS coil orientation and muscle activation can influence I-wave activity, but it remains unclear how these factors influence M1 plasticity with iTMS. We therefore investigated the influence of TMS coil orientation and muscle activation on the response to iTMS. Thirty-two young adults (24.2 ± 4.8years) participated in three experiments. Each experiment included two sessions using a modified iTMS intervention with either a posterior-anterior orientation (PA) or anterior-posterior (AP) coil orientation over M1. Stimulation was applied in resting (Experiments 1 and 3) or active muscle (Experiments 2 and 3). Effects of iTMS on M1 excitability were assessed by recording motor evoked potentials (MEPs) and short-interval intracortical facilitation (SICF) with PA and AP orientations in both resting (all experiments) and active (Experiment 2) muscle. For the resting intervention, MEPs were greater after AP iTMS (Experiment 1, P = .046), whereas SICF was comparable between interventions (all P > .10). For the active intervention, responses did not vary between PA and AP iTMS (Experiment 2, all P > .14), and muscle activation reduced the effect of AP iTMS during the intervention (Experiment 3, P = .002). Coil orientation influenced the MEP response after iTMS, and muscle activation reduced the response during iTMS. While this suggests that AP iTMS may be beneficial in producing a neuroplastic modulation of I-wave circuits in resting muscle, further exploration of factors such as dosing is required.

Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current Stressing.

The electromigration behavior of microbumps is inevitably altered under bidirectional currents. Herein, based on a designed test system, the effect of current direction and time proportion of forward current is investigated on Cu Pillar/Ni/Sn-1.8 Ag/Cu microbumps. Under thermo-electric stressing, microbumps are found to be susceptible to complete alloying to Cu6Sn5 and Cu3Sn. As a Ni layer prevents the contact of the Cu pillar with the solder, Sn atoms mainly react with the Cu pad, and the growth of Cu3Sn is concentrated on the Cu pad sides. With direct current densities of 3.5 × 104 A/cm2 at 125 °C, the dissolution of a Ni layer on the cathode leads to a direct contact reaction between the Cu pillar and the solder, and the consumption of the Cu pillar and the Cu pad shows an obvious polarity difference. However, with a bidirectional current, there is a canceling effect of an atomic electromigration flux. With current densities of 2.5 × 104 A/cm2 at 125 °C, as the time proportion of the forward current approaches 50%, a polarity structural evolution will be hard to detect, and the influence of the chemical flux on Cu-Sn compounds will be more obvious. The mechanical properties of Cu/Sn3.0Ag0.5Cu/Cu are analyzed at 125 °C with direct and bidirectional currents of 1.0 × 104 A/cm2. Compared with high-temperature stressing, the coupled direct currents significantly reduced the mechanical strength of the interconnects, and the Cu-Sn compound layers on the cathode became the vulnerable spot. While under bidirectional currents, as the canceling effect of the electromigration flux intensifies, the interconnect shear strength gradually increases, and the fracture location is no longer concentrated on the cathode sides.

A study of tension and deformation of flexible net under the action of current

ABSTRACT With the decrease of fishery resources, offshore fish farm aquaculture has become the current development trend of the marine aquaculture industry. Flexible net are subject to collision by fish and erosion by seawater, which can lead to breakage of the net. In this paper, the validity of the net mesh concentration method is verified by the model tests of others. The effects of current direction, current velocity, and ten different forms of net breakage on net tension and deformation were further analyzed. The results show that under different forms of net breakage, the tension of the net only decreases significantly in the direction of breakage of the net when the net breaks, while there is no significant change in tension in other directions; for the motion of the nodes, which increases only around the break, while the motion of all other nodes does not change significantly.

Effect of electric current direction on the microstructural evolution and mechanical properties of a cold-rolled Cu–Zn alloy during the phase transformation induced by electric current pulses

Abstract

P1067: Continuous theta burst stimulation with monophasic pulses: effect of current direction

P1067: Continuous theta burst stimulation with monophasic pulses: effect of current direction

The Magnetic Field Interference in Dual-Ingot Low Frequency Electromagnetic Continuous Casting

The magnetic field interference was studied by numerical simulation and experimental examination during dual-ingot low-frequency electromagnetic casting process. By using ANSYS software package to mesh and compute, the magnetic field distribution of semi-continuous casting mold region was simulated. The calculated results were verified with the experimental ones and the effects of current direction, shield, silicon sheet and the coil distance on the distribution of magnetic field and ingot were observed. The result indicated that: regardless of current direction, the magnetic field interference among coils appears and the magnetic flux density weakens in the neighbor part of coils. When the current direction of adjacent coils is opposite, the magnetic intensity in ingots is stronger than that of in the same direction. As the distance between coils increases, the magnetic field reduction generated by interference decreases. The magnetic field interference can be alleviated by setting silicon steel sheets or shield.

Effect of Electric Current Direction on Texture Evolution in a Cold Rolled Fe-3%Si Steel under Electric Current Pulses Treatment

The effect of electric current on the recrystallization texture evolution with the rolling direction both parallel and perpendicular to the current flow during electric current pulses (ECP) treatment was investigated. The results showed that the exerted current direction played a great role on the formation of recrystallization texture {111}<112> and Goss texture {011}<100> at the primary stage of recrytallization induced by ECP treatment. However, with the current density increasing, the effect of current direction on texture evolution almost could be ignored and the final texture components in the two cases all are Goss texture.

Texture and Microstructural Evolution under Electric Current Pulses in a Fe-3%Si Steel

The evolution of the recrystallization texture under high current density electric current pulses (ECP) was investigated in a cold-rolled Fe-3%Si steel sheet. Results showed that the preferred nucleation always occurred in the direction parallel to the current direction at the primary stage of recrytallization. With the increment of the current density, the effect of current direction on texture and microstructural evolution was decreased. Due to the different texture component along the layer depth under different current densities, it was also found that the recrystallization nucleation was much easier to occur from the top surface.

The effect of current direction on superconducting properties of BSCCO fibres grown by anelectrically assisted laser floating zone process

The application of an electric current of 200 mA through the molten zone of BSCCOsuperconducting fibres during laser floating zone processing constitutes an upgradefor improving the grain alignment. When a direct electric current (positivelypolarized fibre) passes through the solidification interface, the solidification conditionsapproach equilibrium, favouring the development of a higher amount of 2212 and14/24 stable phases. The new electrically assisted laser floating zone (EALFZ) technique alsoimproves the 2223 phase formation in fibres heat treated at high temperatures(860 °C).However, the 2223 crystals grow perpendicularly to the fibre axis at the interface between the 2212and 14/24 phases, crossing the crystals of the main phase responsible for the current transport, cancellingthe alignment effect. The resultant current density and critical temperature values wereJc77 K = 230 A cm−2 and Tc = 85 K, respectively. When a lower heat treatment temperature was accomplished(820 °C), the 2223 transverse crystals do not develop and a higher current density value ofJc77 K = 510 A cm−2 was achieved, although with a critical temperature ofTc = 90 K.

Effect of Current Direction on the Reliability of Different Capped Cu Interconnects

AbstractThe reliability of Cu M1-V1-M2-V2-M3 interconnects with SiN and CoWP cap layers was investigated. Similar to previously reported results, the reliability of CoWP capped structures is much better than identical SiN capped structures. However, it was also observed that the reliability of CoWP capped interconnects was independent of the direction of electrical current flow. This phenomenon is different from what was observed for SiN capped structures, where M2 lines with electron current flow in the upstream configuration (“via-below”) have about three times larger median-time-to-failure than identical lines in the downstream configuration (“viaabove”). This is because the Cu/SiN interface is the preferential void nucleation site and provides the fastest diffusion pathway in such an architecture. Failure analysis has shown that fatal partially-spanned voids usually had formed directly below the via for “via-above” configuration, and fully-spanned voids occurred in the lines above the vias for “via-below” configuration.On the other hand, failure analysis for CoWP-coated Cu structures showed that partiallyspanned voids below the via do not cause fatal failures in the downstream configuration. This is because the CoWP layer is conducting, and thus able to shunt current around the void. As a result, a large fully-spanning void is required to cause a failure, just like the upstream configuration. Thus the lifetime of an interconnect with a conducting cap layer is independent of whether the current is flowing upstream or downstream.

Effect of current direction on the lifetime of different levels of Cu dual-damascene metallization

Electromigration in the lower metal (M1) and the upper metal (M2) of Cu dual-damascene interconnections has been studied. The failure times of M2 test structures are significantly longer than those of identical M1 structures. It is proposed that this asymmetry is the result of a difference in the location of void formation and growth, which is believed to be related to the ease of electromigration-induced void nucleation and growth at the Cu/Si3N4 interface. Asymmetric via reliability is therefore an intrinsic characteristic of current Cu interconnect technology.

Effect of current direction and K + on polarization of the frog gastric mucosa proton pump

When current was sent from serosa (S) to mucosa (M) across the frog stomach, there was a polarization (POL) of the open circuit potential (OCPD). POL was not affected by NaCl-free solutions, but was decreased by inhibitors of the H + pump. In present experiments, current was sent to clamp the PD (VC) across the mucosa in steps of 20 mV up to 100 mV below the control OCPD, that is, current was sent from M to S. All experiments were performed in NaCl-free solutions. The POL was expressed as a % of the difference between the VC PD and the control OCPD. In 4 mM K + control solutions, the POL was 11.8%; with 10 −3 M omeprazole (H +/K + pump inhibitor), 1.1; with 10 −5 M SCH 28080 (H +/K + pump inhibitor), 3.6; with 10 −3 M famotidine (H 2 blocker), 1.6; and with 10 −2 M M SCN −, 25.4 (inhibition of H + sec, but not of the pump); in 79 mM K + control solutions, 26.2; with 10 −3 M omeprazole, 4.2; with 10 −5 M SCH 28080, 15.9; with 10 −3 M famotidine, 5.6; and with 10 −2 M SCN −, 29.9. POL was higher in high K + than in low K + solutions contrary to what was observed in previous experiments with current sent from S to M. Results are explained on the basis of an electrogenic H +/K +-ATPase pump which includes a H + channel, permeable to K +. With high K + solutions, K + is driven through the H + channel onto the antiporter (ATPase) when current is sent from M to S, resulting in a greater POL of the pump.

Statistical analyses of the effects of a coastal power plant cooling system on underwater irradiance

The authors estimated the effects of a cooling water discharge from a coastal power plant on underwater light levels using 6 years of integrated hourly irradiance measurements which were taken at the sea bottom in water depths of 10–14m. They applied a before-after-control-impact design (BAC1) to the irradiance recordings. The basic BAC1 design estimates the power plant effect as the difference between the means of impact-control differences observed in separate periods after and before the power plant began operation. This design subtracts out constant spatial differences and uniform temporal changes, leaving only the time-by-location interaction which is the power plant effect. They modified the basic BACI analysis in several ways to deal with high natural variability, serial correlation in the data, and the effects of current direction. The daily irradiance data were divided into two sets of days in which the impact stations were downcurrent or upcurrent from the power plant discharge. For downcurrent days, the authors found significant ( p < 0·0.016) reductions in irradiance ranging from 20 to 28% at three impact stations. For the upcurrent days, they found insignificant increases of about 14%.

Effect of current direction on the dynamics of Josephson-junction arrays.

We present an extensive experimental and theoretical study of the effect that the current direction has on the dynamical properties of rf and dc current-biased overdamped Josephson-junction arrays. We show that a strong {ital spatial} {ital symmetry} of the array about the direction of the macroscopic current flow is necessary for arrays to show {ital only} nteger giant Shapiro steps. If this symmetry is broken, arrays will produce {ital both} fractional {ital and} integer giant Shapiro steps. A moving-vortex model and a pendulum model are used to describe our experimental and computational results.

Gradients for isoelectric focussing at low pH

Gradients for isoelectric focusing in the pH range 2–5 were developed by adding acids to commercially available carrier ampholytes (Ampholine, L.K.B.). The effects of current direction, voltage, focussing time, stabilising medium and pH gradient composition were studied to find the optimum focussing conditions. In addition, the electric potential was measured in loco during the run in order to determine the field strength in different parts of the column. Details for the production of suitable acid gradients are given. Using these gradients it was possible to fractionate the R-type vitamin B 12-binding protein of human amniotic fluid into six fractions with isoelectric points between pH 2.3 and 4.2.