Current Intensity Research Articles

Synergistic signal−amplification effect of silver nanowires and bifunctional monomers on molecularly imprinted electrochemical sensor for diuron analysis

Molecularly imprinted polymers (MIP) have been widely owing to their specificity, however, their singular structure imposes limitations on their performance. Current enhancement methods, such as doping with inorganic nanomaterials or introducing various functional monomers, are limited and single, indicating that MIP performances require further advancement. In this work, a dual−modification approach that integrates both conductive inorganic nanomaterials and diverse bifunctional monomers was proposed to develop a multifunctional MIP−based electrochemical (MMIP−EC) sensor for diuron (DU) detection. The MMIP was synthesized through a one−step electrochemical copolymerization of silver nanowires (AgNWs), o−phenylenediamine (O−PD), and 3,4−ethylenedioxythiophene (EDOT). DU molecules could conduct fluent electron transfer within the MMIP layer through the interaction between anchored AgNWs and bifunctional monomers, and the abundant recognition sites and complementary cavity shapes ensured that the imprinted cavities exhibit high specificity. The current intensity amplified by the two modification strategies of MMIP (3.7 times) was significantly higher than the sum of their individual values (3.2 times), exerting a synergistic effect. Furthermore, the adsorption performance of the MMIP was characterized by examining the kinetics and isotherms of the adsorption process. Under optimal conditions, the MMIP−EC sensor exhibits a wide linear range (0.2 ng/mL to 10 μg/mL) for DU detection, with a low detection limit of 89 pg/mL and excellent selectivity (an imprinted factor of 10.4). In summary, the present study affords innovative perspectives for the fabrication of MIP−EC sensor with superior analytical performance.

Synthesis of chromium carbide powder by vacuum-free electric arc plasma method

Chromium carbide powders were synthesized by vacuum-free electric arc method using pure chromium and carbon powder as starting components. The powders obtained in the experimental series were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), laser diffraction and differential thermal analysis. In the experiments, electrical parameters were recorded, and the thermal field generated in the reaction zone was measured using an infrared camera and tungsten‑rhenium thermocouples. The study results show the feasibility of plasma arc discharge synthesis of chromium carbide compounds Cr3C2 and Cr7C3 within 60 s at current intensity of 200 A. SEM analysis of the resulting powder shows that it consists of acute-angled particles of ∼9 to ∼50 μm in size. An updated design of the discharge circuit employed in the study significantly increases the purity of the final product. Vacuum-free electric arc synthesis of chromium carbide has been studied for the first time.

Para-Hydroxy Ni(II)-POCOP Pincer Complexes as Modifiers on Carbon Paste Electrodes and Their Application in Methanol Electro-Oxidation in Alkaline Media

The application of organometallic materials as anodes in fuel cell devices has experienced a notable increase in recent years. However, the use of POCOP pincer complexes remains scarcely explored despite their great relevance in catalysis. Thus, in this work, the electrocatalytic activity to methanol in alkaline media of three Ni(II)-based POCOP pincer complexes—[NiCl{C6H2-4-OH-2,6-(OPiPr2)2}] (a1), [NiCl{C6H2-4-OH-2,6-(OPtBu2)2}] (a2), and [NiCl{C6H2-4-OH-2,6-(OPPh2)2}] (a3)—will be discussed. The complexes were use as modifiers of carbon paste electrodes that were evaluated using cyclic voltammetry considering diverse factors, such as the absence and presence of MeOH, diverse proportions (% w/w) of the complex in the electrode, scan rate, and different MeOH concentrations. Results indicated the presence of a redox pair Ni(II)/Ni(III) with a quasi-reversible behavior in all complexes, the anodic peak currents of which were proportional to the increase in MeOH concentrations (0.05–0.3 mM), and their oxidation potentials varied in the function of the P-substituent in the Ni(II)-POCOPs backbone. Complex a1 exhibited the best current density (429.5 mA cm2 at 0.5 mM) compared to its analogs a2 and a3. The current intensity of all electrodes displays good stability, which remains—with slight changes—up to 100 s. Moreover, a comparison of their catalytic rate constants suggested a great activity in complex a1 (0.52 × 106 cm3 mol−1 s−1) compared to its analogues, implying a great activity in the electro-oxidation of MeOH. Hence, this work opens new opportunities for the electrochemical application of POCOPs complexes for future DMFCs development.

The Preparation and Evaluation of a Hydrochloride Hydrogel Patch with an Iontophoresis-Assisted Release of Terbinafine for Transdermal Delivery.

Background: Terbinafine hydrochloride (TEB) is a broad-spectrum antifungal medication commonly used to treat fungal infections of the skin. This study designed a hydrogel patch assisted by an iontophoresis system to enhance the transdermal permeability of TEB, enabling deeper penetration into the skin layers. Methods: The influences of current intensity, pH levels, and drug concentration on the TEB hydrogel patch's permeability were explored using an adaptive ion electroosmosis system. The pharmacokinetic profile, facilitated by iontophoresis for transdermal permeation, was analyzed through the application of microdialysis technology. Scanning electron microscopy and transmission electron microscopy were employed to assess the impact of ion electroosmotic systems on skin integrity. Results: The cumulative drug accumulation within 8 h of the TEB hydrogel patches, assisted by iontophoresis, was 2.9 and 7.9 times higher than without iontophoresis assistance and TEB cream in the control group, respectively. TEB hydrogel patches assisted by iontophoresis can significantly increase the permeability of TEB, and the AUC(0-8 h) was 3.4 and 5.4 times higher, while the Cmax was 4.2 and 7.3 times higher than the TEB hydrogel patches without iontophoresis, respectively. This system has no significant impact on deep-layer cells. Conclusions: This system may offer a safe and effective clinical strategy for the local treatment of deep antifungal infections.

Mechanism of electroacupuncture for vascular dementia based on proteomics

To explore the potential mechanism of electroacupuncture (EA) for vascular dementia (VD) using tandem mass tag (TMT) quantitative proteomics technology. Among 80 male SPF SD rats, 78 rats which met the selection criteria through the Morris water maze test were selected and randomly divided into a sham surgery group (18 rats) and a surgery group (60 rats). VD model was established by four-vessel occlusion (4-VO) method in the surgery group, and 36 rats with successful modeling were randomly assigned to a model group (18 rats) and an EA group (18 rats). Each group was further divided into three subgroups based on intervention duration, with each subgroup containing 6 rats. Seven days after model establishment, the EA group received EA intervention at left and right "Sishencong" (EX-HN 1) and bilateral "Fengchi" (GB 20), with continuous wave at a frequency of 2 Hz and current intensity of 1 mA, daily for 30 min, with subgroups receiving EA for 7, 14, or 21 d respectively. Cognitive function before and after interventions was assessed using Morris water maze. Proteomic analysis was conducted on the optimal EA subgroup and corresponding sham surgery and model subgroups, identifying differentially expressed proteins and analyzing them through bioinformatics. Differentially expressed target proteins was performed using parallel reaction monitoring (PRM) and Western blot techniques. Compared to the sham surgery group, the model group exhibited prolonged escape latency and reduced number of platform crossings (P<0.01); compared with model group, the EA group showed reductions in escape latency and increased platform crossings after 7, 14, and 21 days of intervention (P<0.01, P<0.05). Compared to the 7 and 14-day intervention, the rats in the EA group of 21-day intervention showed the most significant improvements in reductions of escape latency and increased platform crossings (P<0.01, P<0.05), and was selected for further proteomic, PRM analyses, and Western blot validation. Compared to the sham surgery group, the model group displayed 71 differentially expressed proteins, with 50 up-regulated and 21 down-regulated proteins; compared to the model group, the EA group had 54 differentially expressed proteins, with 30 up-regulated and 24 down-regulated proteins. Functional enrichment and clustering analyses indicated that these proteins were primarily associated with cellular processes, metabolic processes, phagocytosis recognition, immune response, and regulation of extracellular matrix, etc. Enrichment was observed in the mammalian target of rapamycin (mTOR) signaling pathway and neurotrophic factors signaling pathways, involving glycogen synthase kinase 3β (GSK3β) and mitogen-activated protein kinase kinase 2 (Map2k2), with PRM and Western blot findings consistent with the proteomic results. Which meant that compared with the model group, the protein expression of GSK3β and Map2k2 of hippocampus was increased in the EA group (P<0.01, P<0.05). EA at "Sishencong" (EX-HN 1) and "Fengchi" (GB 20) could improve cognitive function in VD rats, with the mechanism involving multiple targets and pathways, potentially related to GSK3β, Map2k2 proteins, and the mTOR and neurotrophic factor signaling pathways.

Effectiveness of McKenzie exercises plus stabilization exercises versus McKenzie exercises alone on disability, pain, and range of motion in patients with nonspecific chronic neck pain: A randomized clinical trial.

Chronic nonspecific neck pain is a common disorder that causes disability and reduced quality of life. Effective conservative treatment options are needed to manage this condition. This randomized trial compared the efficacy of McKenzie exercises alone versus McKenzie plus cervical and scapulothoracic stabilization training for patients with chronic nonspecific neck pain. A randomized controlled trial was conducted in an outpatient physical therapy clinic. 76 patients with chronic (> 3 months) neck pain were randomized to 6 weeks of either McKenzie exercises alone (n= 38) or McKenzie plus stabilization exercise (n= 38). The McKenzie protocol included posture correction, range of motion exercises, and lateral neck stretches. The stabilization program added targeted exercises for the neck and scapula. The combination of McKenzie plus stabilization exercises resulted in significantly greater reduction in current neck pain intensity compared to McKenzie alone at 6 weeks (mean difference: -1.2 points on 0-10 scale, 95% CI -1.8 to -0.6; p< 0.001). Neck disability improved in both groups. Cervical range of motion also improved more with the addition of stabilization, except for extension. Adding specific cervical and scapulothoracic stabilization exercises to a standard McKenzie protocol led to clinically meaningful reductions in neck pain compared to McKenzie therapy alone in patients with chronic nonspecific neck pain. This combined approach can improve outcomes.

Electrochemical biofilter enhances performance of volatile organic compounds abatement

ABSTRACT An electrochemical biofilter (EBF) was developed for enhancing the removal of volatile organic compounds (VOCs) through current. The removal efficiency (RE) of toluene exhibited a notable increase of 15% while the biomass growth rate exhibited a corresponding decline of 46% under an optimal current intensity of 50 mA. Meanwhile, the efficacy of the EBF system was markedly enhanced upon the removal of n-hexane, styrene, dichloromethane, and diisobutylene. The results indicated that there was an 11% to 49% increase in RE and a 0% to 64% reduction in biomass growth rates under the influence of the current. The current stimulation inhibited the accumulation of microorganisms, thereby alleviating biofilm clogging. The relative abundance of gram-positive phyla, including Firmicutes and Actinobacteria, increased by 15% and 23%, respectively, while the traditionally dominant genera within the Proteobacteria phylum, such as Rhodococcus and Dokdonella, exhibited a decline. In addition, the presence of hydrogen peroxide, free chlorine, and superoxides in the leachate indicated that the oxidative reaction increased in EBF system. This study provides an attractive pathway for current stimulation to enhance degradation of VOCs and alleviate biofilm clogging.

Modeling and Optimization of Electrochemical Advanced Oxidation of Clopidogrel Using the Doehlert Experimental Design Combined with an Improved Grey Wolf Algorithm

In this research, the optimization of the electrochemical advanced oxidation treatment for the degradation of Clopidogrel was investigated. This study examined the influence of various experimental parameters including applied current, initial Clopidogrel concentration, and ferrous ion concentration by the use of the Doehlert design within a response surface methodology framework. The improved grey wolf optimizer was applied in order to define the optimum operating conditions. The monitoring of clopidogrel concentration during treatment revealed that complete disappearance of clopidogrel was achieved under an initial clopidogrel concentration of 0.02 mM, current intensity of 0.55 A, Fe2+concentration of 0.7 mM, and a reaction time of 20 min in a solution containing 50 mM Na2SO4 at pH 3. A quadratic polynomial model was developed, and its statistical significance was confirmed through the analysis of variance, demonstrating a high level of confidence in the model (R2 = 0.98 and p-value &lt; 0.05). Furthermore, following electrolysis treatment for 480 min, the synthetic clopidogrel solutions underwent mineralization, achieving a 70.4% removal rate of total organic carbon. Subsequently, the applicability of the optimized process was tested on real pharmaceutical wastewater, and mineralization was investigated under the identified optimal conditions, resulting in a total organic carbon removal rate of 87% after 480 min of electrolysis time. The energy consumption for this system was calculated to be 1.4 kWh·kg−1 of the total organic carbon removed. These findings underscore the effectiveness and potential applicability of the electrochemical advanced oxidation for industrial wastewater treatment.

Unveiling Local Current Behavior and Manipulating Grain Homogenization of Perovskite Films for Efficient Solar Cells.

Achieving high power conversion efficiency in perovskite solar cells (PSCs) heavily relies on fabricating homogeneous perovskite films. However, understanding microscopic-scale properties such as current generation and open-circuit voltage within perovskite crystals has been challenging due to difficulties in quantifying intragrain behavior. In this study, the local current intensity within state-of-the-art perovskite films mapped by conductive atomic force microscopy reveals a distinct heterogeneity, which exhibits a strong anticorrelation to the external biases. Particularly under different external bias polarities, specific regions in the current mapping show contrasting conductivity. Moreover, grains oriented differently exhibit varied surface potentials and currents, leading us to associate this local current heterogeneity with the grain orientation. It was found that the films treated with isopropanol exhibit ordered grain orientation, demonstrating minimized lattice heterogeneity, fewer microstructure defects, and reduced electronic disorder. Importantly, devices exhibiting an ordered orientation showcase elevated macroscopic optoelectronic properties and boosted device performance. These observations underscore the critical importance of fine-tuning the grain homogenization of perovskite films, offering a promising avenue for further enhancing the efficiency of PSCs.

Improved bacterial elimination in wastewater through electrocoagulation: hydrogen generation, adsorption of colloidal bacteria-flocks, and electric field bactericidal action

ABSTRACT Electrocoagulation (EC) has emerged as a promising method for wastewater treatment, offering efficient removal of various contaminants, including bacteria. This study investigates the mechanisms underlying bacterial removal in EC processes, mainly the hydrogen-mediated foam, the effect of operational parameters, including initial pH, current density, and reaction time, and evaluates the associated energy consumption. The EC reactor employed aluminum electrodes and operated at a current intensity of 3.0 A. It demonstrated a notable bacterial removal efficiency, with 120.102 UFC ml−1 of mesophyll floral aerobic bacteria removed through colloid bacteria-flocs precipitation, 440.102 UFC ml−1 via bacterial-bulls flotation from foam, and 117.102 UFC ml−1 through attraction at the electrodes’ plate surface. We found that the EC process leads to the formation of aluminum hydroxide and ferrous hydroxide precipitates, which adsorb bacteria and facilitate their removal from the wastewater via electrostatic forces with an energy consumption of 45 kWh/m3. Overall, this research provides valuable insights into the mechanisms governing bacterial removal in EC and highlights the importance of energy consumption analysis for optimizing wastewater treatment processes.

Harmonic power flow under non-sinusoidal conditions

This article aims to analyze the electric field and the flow of electromagnetic energy in power cables with copper and aluminum cores, without considering the implicit physics of the coating that surrounds the conductor, which is generally composed of XLPE. Computational simulations were carried out with two models of alternating electrical current (AC) intensities, with a frequency of 60 HZ, electrical voltage of 1 kV, in a transient regime, with a phase difference of 120° and considering the lengths of the cables at a value of L = 30 m. Applying a Fourier series expansion to a sinusoidal electric current and expanding to the third term of the series, resulting in a new formulation of the electric current that was called modified electric current. The peculiarity of this research lies in the fact that, through the Fourier series expansion of conventional alternating current, a transformation to a modified current was observed, presenting behavior analogous to that of a Rectifying Diode. The improvements provided by this method include increased efficiency in the transmission of electrical energy, reduction of voltage drops, reduction of losses associated with the Joule-Lenz effect and extension of the useful life of the cable. The results demonstrated that, by modifying the electric current, the electric fields and Poynting vectors were calculated and approached the solutions of Maxwell's equation for conventional electric current, in both types of power cables. In addition, this approach has been observed to be particularly effective for power cables with a length of 30 m, and using the modified current in Maxwell's equations to compare the electric and Poynting fields with those calculated using conventional electric current. Therefore, the results obtained are satisfactory for both power cables.

Intrinsic and extrinsic relaxation mechanisms for controlling spin current intensity in Fe 100−x Co x /Ta bilayers

Controlling the damping parameter in metallic ferromagnetic thin films is a key step for spintronic applications in which spin currents are generated by spin pumping. The coexistence of two states with low and high damping constant values would allow to obtain states of high and low spin current intensity, respectively. We have fabricated Fe 100−x Co x /Ta (with nominal x = 0, 15, 20, 25, 30 and 35) bilayers in which the Fe 100−x Co x layers grow epitaxially and the Ta layer is polycrystalline. We have found the coexistence of Gilbert damping and two magnon scattering mechanisms linked to a sign change in the magnetocrystalline anisotropy constant that allows the manipulation of low and high intensity states of the measured inverse spin Hall effect voltage. Bilayers with lower Co concentrations ( x⩽ 25%) present different relaxation mechanisms (isotropic Gilbert damping and two magnon scattering) and an extra ferromagnetic resonance linewidth broadening produced due to mosaicity. Bilayers with Co concentration x> 25% present a dominating Gilbert damping for all directions in the film plane. However, in this concentration range the damping constant is anisotropic and when the magnetic field is applied along the hard magnetization direction α increases ∼420% with respect to the value obtained for the easy magnetization direction. Coexistence of isotropic Gilbert damping and two magnon scattering generated spin currents 2.5 times larger when the field is applied along the hard magnetization axis compared to the value observed in the easy magnetization axis. Thesefindings make the Fe 100−x Co x /Ta system an excellent candidate for spintronic device applications.

A Numerical Consideration on the Correlation Between Magnitude of Earthquakes and Current Intensity Causing ULF Electromagnetic Wave Emission

A Numerical Consideration on the Correlation Between Magnitude of Earthquakes and Current Intensity Causing ULF Electromagnetic Wave Emission

Design and simulation of artificial retinal stimulation IC with switched capacitor using Si nanowire optical properties.

This study introduces an approach for converting the current from a sensor into controllable voltage. To this end, a switched-capacitor structure was integrated to provide efficient current-to-voltage conversion. The generated voltage was further regulated by an operational amplifier current source, enhancing stability and precision. An n-type metal oxide semiconductor field-effect transistor structure under an H-bridge was integrated into the system to achieve fine-tuned control over current stimulation. This component contributed to voltage regulation and enabled bi-directional control of current flow, offering versatility in adjusting current amplitudes using working and counter electrodes. This dynamic control mechanism was pivotal for effectively controlling the intensity of current stimulation. We applied Verilog-A modeling to simulate the optical characteristics of Si nanowires. The proposed system efficiently converted sensor-derived current into voltage using a switched-capacitor structure. Simultaneously, the precision was enhanced via operational amplifier regulation and n-type metal-oxide-semiconductor field-effect transistor-based H-bridge control. The simulation showed a current stimulus amplitude ranging from 2 to 13 μA for a variable photocurrent of Si nanowires (Rex: 10 kΩ, pulse: 100 Hz, 1 ms). The ability to finely control current stimulation intensity holds promise for diverse applications requiring accurate and adjustable current manipulation. This study contributes to the growing field of sensor technology by offering a unique perspective on the integration of nanostructures and electronic components for an enhanced control and functionality.

Design and optimization of microchannel for enhancement of the intensity of induced signal in particle/cell impedance measurement.

The measured impedance signal of a single particle or cell in a microchannel is of the μA level, which is a challenge for measuring such weak signals. Therefore, it is necessary to improve the intensity for expanding the applications of impedance measurement. In this paper, we analyzed the impact of geometric parameters of microchannel on output signal intensity by using the three-dimensional finite element method. In comparison to conventional microchannels, which are distributed at a uniform height, the microchannels in this design use the height difference to enhance the signal intensity. By analyzing the effects of the geometric dimensions of the constriction channel, main channel height, radius of particles, types of cells, shapes of particles with different ellipticities, and particles spacing on the current signal, we concluded the optimal dimensions of these parameters to improve the intensity of the induced current signal. Through the fabrication of the optimized size of device and experimental demonstration, it is verified that the current signal intensity caused by the particle with a diameter of 10 µm is nearly twice that of the conventional structure with a height of 20 µm, which proves the correctness of the optimization results and the feasibility of this work. In addition, the performance of the device was verified by measuring the mixtures of different size particles as well as non-viable and viable yeast cells.

Electrochemical modification of glassy carbon electrode (GCE) with cobalt ferrite/ reduced graphene oxide composite material comprising polyaniline for dissolved oxygen analysis in water

The study focuses on the enhancement of glassy carbon electrode (GCE) performance through electrochemical modification with a composite material comprising polyaniline (PANi) conducting polymer and CoFe2O4/reduced graphene oxide (CF/rGO) for the analysis of dissolved oxygen in water. Characterization methods, including Fourier-transform infrared spectroscopy (FT-IR) and Scanning Electron Microscope (SEM), were employed to elucidate the chemical bonding of functional groups within the PANi membrane and modified PANi on the surface of the GCE electrodes as well as examine the surface morphology. Electrochemical studies were conducted to evaluate the electrochemical activity of the modified electrodes, GCE/PANi and GCE/PANi/CF/rGO. Electrochemical studies were conducted to evaluate the electrochemical activity of the modified electrodes, GCE/PANi and GCE/PANi/CF/rGO. Notably, the electrochemically active surface area of the modified electrodes significantly increased, from 0,0756 cm2 (GCE), 0,1106 cm2 (GCE/PANi) to 0,1774 cm2 (GCE/PANi/CF/rGO), in addition the peak current intensity (Ip) on the modified electrodes GCE/PANi and GCE/PANi/CF/rGO also increased compared to the unmodified electrode (GCE), Ip increased from 0,0767.10-3 (A) to 0,18 x 10-3 (A), resulting in an increased ability to sense dissolved oxygen in water.

Adsorption−desorption of Zn2+ ions using hydroxyapatite and recovery of zinc by electrochemical precipitation method into deep eutectic solvent

Hydroxyapatite has a nanostructure, the chemical formula of Ca10(PO4)6(OH)2 and a specific surface area of 91.42 m2/g. In this paper, hydroxyapatite is used to adsorb Zn2+ ions as effective adsorbent. The influence of some factors on Zn2+ adsorption capacity and efficiency has been studied. Under the suitable adsorption conditions were hydroxyapatite mass of 0.15 g in 50 mL solution, 50 mg L−1 initial Zn2+ concentration, pH 5.0, exposure time of 60 min at room temperature (25 °C), Zn2+ adsorption efficiency and capacity reached 94.79 % and 15.80 mg g−1, respectively. The process of desorption of Zn2+ from the loaded adsorbent and recovery of metallic Zn was also investigated. Zinc recovery efficiency reached 93.26 % under appropriate conditions such as applied current intensity of 7.5 mA, electrolysis time of 10 h, loaded hydroxyapatite mass of 0.1 g, temperature 60 °C. After desorption process, the adsorbent was regenerated for further studies. The adsorption isotherm was studied based on three Langmuir, Freundlich and Redlich-Peterson models. The adsorption thermodynamics were investigated and calculating the parameters. The adsorption kinetics were examined using two pseudo-first-order and pseudo-second-order kinetic models. The negative value of Gibb’s free energy change showed that the adsorption process was feasible and spontaneous in nature. The positive value of enthalpy change indicated that the process was endothermic. The positive value of entropy change showed increased randomness at the solid and solution interface.

Labrador Coastal Current and productivity variations offshore Nain (Nunatsiavut) during the late Holocene

The Labrador Coastal Current (LCC) transports cold and fresh waters of Arctic origin towards the North Atlantic and has a strong influence on the coastal ecosystems and climate of eastern Canada. Here, we present a multi-decadally resolved record of changes in sea-surface and near-bottom conditions of the LCC during the last 3000 years based on the analysis of biogenic tracers (organic-walled dinoflagellate cysts, carbon, and nitrogen geochemistry) and sedimentary content (sortable silt, magnetic susceptibility, elemental ratios) in the upper 2 m of sediments in a core retrieved offshore Nain, Nunatsiavut. Our data reveal multi-centennial bottom flow strength variability in the LCC, with strong linkages to changes in regional ocean circulation patterns. At about 2100- and 550-years BP, the sedimentological and biogenic tracer data suggest changes in the LCC bottom current intensity (decline and strengthening, respectively) that coincide with shifts in the persistent mode of the North Atlantic Oscillation. Our proxy data suggests increased biological production during the last 500 years compared to the preceding 2500 years, possibly reflecting a gradual decrease length of the sea-ice season. The data show a decline in the LCC strength during periods of increased polar water influence identified in previous palaeoceanographic studies conducted further north, which may be attributed to the trapping of freshwater in sea ice during these periods. Our results highlight the dynamical oceanographic and atmospheric factors that influence the LCC and the coastal ecosystems along its path and confirm that the processes in Baffin Bay impact the Labrador Shelf oceanography.

Screening for optimal parameters for modified pharyngeal electrical stimulation for the treatment of dysphagia after stroke in rats

Pharyngeal electrical stimulation (PES), a novel noninvasive peripheral nerve stimulation technique, can effectively improve neurogenic dysphagia and increase the safety and effectiveness of swallowing in the clinic. However, the lack of animal models for dysphagia has limited the mechanistic research on PES, which affects its wide application. Therefore, determining optimal parameters for PES in rats is needed to enable mechanistic studies. Modified PES (mPES), which has different waves and pulse widths from PES, was used; in previous studies mPES was found to have a neurological mechanism like that of PES. A poststroke dysphagia (PSD) model was established, and rats with dysphagia were grouped into three different intensities (0.1 mA, 0.5 mA, and 1 mA) for the selection of optimal intensity and three different frequencies (1 Hz, 2 Hz, and 5 Hz) for the selection of optimal frequency based on a stimulation duration of 10 min in the clinic. A Videofluroscopic Swallow Screen (VFSS) was used to assess swallowing function in rats before and after mPES treatment. The results showed that the 1 mA group had better swallowing function (p < 0.05) than the model group. Compared with the model group, the 1 Hz and 5 Hz groups had the same improvement in swallowing function (p < 0.05). However, the increase in excitatory signals in the sensorimotor cortex was more pronounced in the 5 Hz group than in the other frequency stimulation groups (p < 0.05). Combining the clinical findings with the above results, we concluded that the optimal stimulation parameter for mPES in rats is “frequency: 5 Hz, current intensity: 1 mA for 10 min/day”, which provides a basis for future basic experimental studies of mPES in animals.

Experimental Study on the Current Pretreatment-Assisted Free Bulging of 304 Stainless Steel Sheets

In order to further improve the microplastic deformation ability and forming performance of metal sheets, a pulse current pretreatment-assisted micro-forming method was proposed. Firstly, a 304 stainless steel sheet was pretreated with current (0–25 A), and the microstructure changes in the sheet under the action of current were analyzed. Then, a current-assisted bulging experiment was carried out from three aspects as follows: current size, mold structure size, and material properties, to explore the influence of different process parameters on the micro-bulging of the sheet. Finally, the forming quality was analyzed and evaluated from the two perspectives of bulging depth and wall thickness uniformity. The research results show that when the current intensity increases from 0 to 25 A, the fibrous distribution in the thickness direction of the sheet is alleviated, the structure is more uniform, the bulging depth shows an increasing trend, and the thinning rate and wall thickness uniformity are improved. When the current intensity reaches 25 A, the bulging depth increases from the original 463 μm to 503 μm, and the thinning rate drops from the most serious 48.52% to 19.4%. At the same time, as the mold size increases, the single-channel aspect ratio (W/H) also increases accordingly. When the mold groove width (W) is 2 mm, the ratio reaches 0.4, the sheet deforms significantly, and the filling effect is better. In addition, the larger the roundness of the convex and concave molds, the more uniform the wall thickness distribution of the bulging parts. Under the same experimental conditions, the bulging depth of the 304 stainless steel sheet is higher than that of TC4 titanium alloy, and it is less prone to springback and is more conducive to plastic deformation.