Current Response Research Articles

Identification of Commercial Stainless-Steel Mesh Size for Electrochemical Oxygen Evolution Reaction.

The study examines the oxygen evolution reaction (OER) electrocatalytic efficiency of various stainless-steel mesh (SSM) sizes in electrolytic cells. Stainless steel is chosen due to its widespread availability and stability, making it an economically viable option. The primary objective of this investigation is to determine the optimal stainless-steel mesh size among those currently widely available on the market. The classification of stainless-steel mesh sizes as SS304 is confirmed by the minimal compositional variations observed across all mesh sizes through cyclic voltammetry (CV) and X-ray fluorescence (XRF) analyses. Remarkably, CV experiments carried out at different scan rates indicate that SSM 200 has the maximum specific electrochemical surface area (ECSA). As a result, SSM 200 demonstrates superior performance in terms of current density response and shows the lowest overpotential in the alkaline medium compared to other stainless-steel mesh sizes. Stability tests conducted under constant voltage further confirm the remarkable stability of SSM 200, making it an ideal anode for electrolytic cell applications. These findings emphasize the cost-effectiveness and high stability of SSM 200, presenting intriguing possibilities for future research and advancements in this field.

Dilemmas in Regulation

AbstractFour topics related to the operation of regulatory systems are considered. These concern the matters of dealing with globally sub‐optimal decisions made by regulators, the problem of specifying boundaries between groups of regulated entities in the application of regulation, dealing with a situation in which there are multiple regulators, and the alignment of regulation across jurisdictional borders. It is argued that current responses to these dilemmas tend to add to levels of inefficiency in the economy, with consequences for growth. Options for resolving them are considered, including new approaches to the design of regulation.

Design of Solar Energy Based System Using Artificial Neural Network Controller

A key component of energy generation and the safe operation of the electrical system is solar energy. The solar energy system for producing the required voltage is presented in this paper. It is managed by an artificial neural network (ANN) controller, which performs significantly better than a conventional PI controller. It aids in lowering the system's total harmonic distortion (THD). The sole PI controller, which produces an erratic output response, is utilized in conventional wind turbines. It is swapped out in the suggested system for an ANN controller, which offers smooth voltage and current response. Two inputs and two outputs are used in the system's development. Six pulse-fired IGBTs that reduce excess voltage and current in the circuit operate this system. The MATLAB/Simulink tool was used to create the results, which were shown to be superior to traditional results. To regulate the impact of a variable power factor, an output variable load is connected. Every outcome has been validated and confirmed to be superior than traditional outcomes.

High-Performance Solar-Blind Photodetector Based on (010)-Plane β-Ga2O3 Thermally Oxidized from Nonpolar (110)-Plane GaN.

A high-performance planar structure metal-semiconductor-metal-type solar-blind photodetector (SBPD) was fabricated on the basis of (010)-plane β-Ga2O3 thermally oxidized from nonpolar (110)-plane GaN. A full width at half maximum of 0.486° was achieved for the X-ray rocking curve associated with (020)-plane β-Ga2O3, which is better than most reported results for the heteroepitaxially grown (-201)-plane β-Ga2O3. As a result of the relatively high crystalline quality, a dark current as low as 6.30 × 10-12 A was achieved at 5 V, while the photocurrent reached 1.86 × 10-5 A under 254 nm illumination at 600 μW/cm2. As a result, the photo-to-dark current ratio, specific detectivity, responsivity, and external quantum efficiency were calculated to be 2.95 × 106, 2.39 × 1012 Jones, 3.72 A/W, and 1815%, respectively. Moreover, the SBPD showed excellent repeatability and stability in the time-dependent photoresponse characteristics with fast relaxation time constants for the rise and decay processes of only 0.238 and 0.062 s, respectively. This study provides a promising approach to fabricate the device-level (010)-plane β-Ga2O3 film and a new way for the epitaxial growth of (010)-plane β-Ga2O3 and (110)-plane GaN as mutual substrates.

Gender and non-communicable diseases in Mexico: a political mapping and stakeholder analysis

BackgroundMexico and other low- and middle-income countries (LMICs) present a growing burden of non-communicable diseases (NCDs), with gender-differentiated risk factors and access to prevention, diagnosis and care. However, the political agenda in LMICs as it relates to health and gender is primarily focused on sexual and reproductive health rights and preventing violence against women. This research article analyses public policies related to gender and NCDs, identifying political challenges in the current response to women’s health needs, and opportunities to promote interventions that recognize the role of gender in NCDs and NCD care in Mexico.MethodsWe carried out a political mapping and stakeholder analysis during July–October of 2022, based on structured desk research and interviews with eighteen key stakeholders related to healthcare, gender and NCDs in Mexico. We used the PolicyMaker V5 software to identify obstacles and opportunities to promote interventions that recognize the role of gender in NCDs and NCD care, from the perspective of the political stakeholders interviewed.ResultsWe found as a political obstacle that policies and stakeholders addressing NCDs do not take a gender perspective, while policies and stakeholders addressing gender equality do not adequately consider NCDs. The gendered social and economic aspects of the NCD burden are not widely understood, and the multi-sectoral approach needed to address these aspects is lacking. Economic obstacles show that budget cuts exacerbated by the pandemic are a significant obstacle to social protection mechanisms to support those caring for people living with NCDs.ConclusionsMoving towards an effective, equity-promoting health and social protection system requires the government to adopt an intersectoral, gender-based approach to the prevention and control of NCDs and the burden of NCD care. Despite significant resource constraints, policy innovation may be possible given the willingness among some stakeholders to collaborate, particularly in the labour and legal sectors. However, care will be needed to ensure the implementation of new policies has a positive impact on both gender equity and health outcomes. Research on successful approaches in other contexts can help to identify relevant learnings for Mexico.

Convenient Size Analysis of Nanoplastics on a Microelectrode.

Chemical recycling is a promising approach to reduce plastic pollution. Timely and accurate size analysis of produced nanoplastics is necessary to monitor the process and assess the quality of chemical recycling. In this work, a sandwich-type microelectrode sensor was developed for the size assessment of nanoplastics. β-Mercaptoethylamine was modified on the microelectrode to enhance its surface positive charge density. Polystyrene (PS) nanoplastics were captured on the sensor through electrostatic interactions. Ferrocene was used as an electrochemical beacon and attached to PS via hydrophobic interactions. The results show a nonlinear dependence of the sensor's current response on the PS particle size. The size resolving ability of the microelectrode is mainly attributed to the small size of the electrode and the resulting attenuation of the electric field strength. For mixed samples with different particle sizes, this method can provide accurate average particle sizes. Through an effective pretreatment process, the method can be applied to PS nanoplastics with different surface properties, ensuring its application in evaluating different chemical recycling methods.

Iterative addition of parallel non-local effects to full wave ICRF finite element models in axisymmetric tokamak plasmas

Abstract The current response of a hot magnetized plasma to a radio-frequency wave is non-local, turning the electromagnetic wave equation into an integro-differential equation. Non-local physics gives rise to wave physics and absorption processes not observed in local media. Furthermore, non-local physics alters wave propagation and absorption properties of the plasma. In this work, an iterative method that accounts.
for parallel non-local effects in 2D axisymmetric tokamak plasmas is developed,
implemented, and verified. The iterative method is based on the finite element method
and Fourier decomposition, with the advantage that this numerical scheme can describe
non-local effects while using a high-fidelity antenna and wall representation, as well as
limiting memory usage. The proposed method is implemented in the existing full wave
solver FEMIC and applied to a minority heating scenario in ITER to quantify how
parallel non-local physics affect wave propagation and dissipation in the ion cyclotron
range of frequencies (ICRF). The effects are then compared to a reduced local plane
wave model, both verifying the physics implemented in the model, as well as estimating
how well a local plane wave approximation performs in scenarios with high single pass
damping. Finally, the new version of FEMIC is benchmarked against the ICRF code
TORIC.

Diazo-functionalised immunoelectrochemical sensor for the detection of ochratoxin a in foods

Ochratoxin A (OTA) is a toxic fungal metabolite that is commonly found in cereals and animal feed. It is economically damaging and potentially hazardous to human health. Herein, we propose an electrochemical immunosensor for the rapid detection of OTA using anti-OTA antibodies and diazonium-functionalized, screen-printed electrodes. We attached 4-aminobenzoic acid to an electrode surface, activated the carboxyl groups on the surface with carbodiimide, and attached an antibody to the diazo layer. Subsequently, we used bovine serum protein as a blocker to prevent non-specific antigens from binding to the antibody. We evaluated the performance of the sensor by cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. The sensor is highly specific and sensitive, has good linear responses in the range 20–200 ng/mL, a limit of detection of 0.5 ng/mL, and good recoveries of 90.5%–100.9% in spiked samples. It can be stored at 4 °C for approximately 2 weeks, and is highly stable, with a current response variation of no more than 4.6%.

Employing Piper longum extract for eco-friendly fabrication of PtPd alloy nanoclusters: advancing electrolytic performance of formic acid and methanol oxidation.

Advancement in bioinspired alloy nanomaterials has a crucial impact on fuel cell applications. Here, we report the synthesis of PtPd alloy nanoclusters via the hydrothermal method using Piper longum extract, representing a novel and environmentally friendly approach. Physicochemical characteristics of the synthesized nanoclusters were investigated using various instrumentation techniques, including X-ray photoelectron spectroscopy, X-ray diffraction, and High-Resolution Transmission electron microscopy. The electrocatalytic activity of the biogenic PtPd nanoclusters towards the oxidation of formic acid and methanol was evaluated chronoamperometry and cyclic voltammetry studies. The surface area of the electrocatalyst was determined to be 36.6 m2g-1 by Electrochemical Surface Area (ECSA) analysis. The biologically inspired PtPd alloy nanoclusters exhibited significantly higher electrocatalytic activity compared to commercial Pt/C, with specific current responses of 0.24mAcm - 2 and 0.17mAcm - 2 at synthesis temperatures of 180°C and 200°C, respectively, representing approximately four times higher oxidation current after 120min. This innovative synthesis approach offers a promising pathway for the development of PtPd alloy nanoclusters with enhanced electrocatalytic activity, thereby advancing fuel cell technology towards a sustainable energy solution.

Shewanella baltica in a Microbial Fuel Cell for Sensing of Biological Oxygen Demand (BOD) of Wastewater

Geobacter and Shewanella are the most characterized electroactive bacteria genera. Unlike genus Geobacter that is strictly anaerobic, Shewanella can grow under both oxic and anoxic environments and is capable of metabolizing a wider substrate range. In the present study, the use of strain Shewanella baltica 20 in MFC-based biosensor for BOD monitoring is reported. The S. baltica strain 20 was isolated from river sediment in Hungary. The bacterium could form a biofilm, oxidized glucose, and transferred electrons to produce current when they were enriched on the anode in an air cathode microbial fuel cell (MFC). The tested MFC system demonstrated linearity in the current response to glucose from 50 to 300 mg/L. The electrical efficiency was determined from the polarization curve using the method of Varying Circuit Resistance (VCR) with an external load probed from 10 Ω to 220 kΩ. The maximum power production was 1.2 mW/m2 at an external load of 40 kΩ. Studying the effect of external resistors on the MFC performance showed that the MFC reached higher saturation for 500 mg/L of glucose at lower resistances of 100 and 470 Ω, in comparison to 300 mg/L at 1000 Ω. The results show that the response of the MFC can potentially be tuned by adjusting the external load. Our preliminary study suggests that Shewanella baltica strain 20 may be used for online monitoring of BOD (biological oxygen demand) in wastewater.

Decoration of atomic PdxAuy (1 ≤ x + y ≤ 4) clusters on polyaniline in electrochemical sensing of 1-propanol

Atomic PdxAuy (1 ≤ x + y ≤ 4) clusters are decorated on polyaniline to be used as the catalytic electrode in electrochemical sensors. The current responses in the oxidation of 1-propanol are used to reveal the catalytic activity. Effects of the size, decoration sequence, and composition of the atomic metal clusters decorated on the PANI on the catalytic activity are evaluated. Regarding the size, an odd-even size effect is observed in the atomic pure metal clusters, which the even-numbered pure metal clusters show a higher catalytic activity than the odd-numbered pure metal clusters. For the decoration sequence, the catalytic activity is high when the same metal is decorated in the first two cycles of the cyclic atomic electrodeposition process. For the composition effect, the atomic metal clusters show a high catalytic activity in the oxidation, in the region of second oxidation peak, when there are more Au in the atomic metal clusters.

Development of Amperometric Enzyme Biosensor for Determination of Heavy Metal Ions in aqueous samples

An amperometric urease inhibition-based biosensor was developed to detect Pb2+ and Cr3+ ions in water matrix. The modified GCE/ZnO/urease electrode was developed by immobilizing ZnO nanoparticles and urease using gelatin and glutaraldehyde as crosslinking agent. With urea as a substrate, ZnO catalytic activity was examined through cyclic voltammetry. Working conditions of the biosensing system were optimized in terms of current generated in the presence of substrate (urea) as a function of different variables. Optimal sensor activity (current response) was obtained with a urease loading of 4 µl and ZnONPs concentration of 1.5 mg/L. For solution parameters, optimum pH was in the range of 7.0-7.5, optimum temperature was 35oC, optimal substrate concentration 40 µl. Evaluation of some key biosensing properties revealed relatively stable biosensor activity within the first 7 days, good reproducibility with an RSD of 3.61%. Limits of detection (LOD) for the biosensor ranged from 0.04 - 0.07 while limits of quantitation (LOQ) ranged from 0.22- 0.13 ppm. Applying the developed biosensor to real samples was evaluated by analysing water samples from Kasuwangada River in Mubi North Local Government Area. The system showed good percentage recovery of the added heavy metal standard (0.05 – 0.25 ppm). Percentage recovery within the acceptable range of 98.00% to 103.00% was observed for Pb2+, 92.00% - 102.00 % recovery for Cr3+. Analysis of real samples and assessment of obtained results against a standard method (AAS) showed minimal differences. The developed biosensor showed sufficient sensitivity to the analysed sample and gave quantitative information on the Pb2+ and Cr3+content of the sample. Keywords: Biosensor, Heavy Metals, Urease enzymes, Inhibition studies, Enzyme activity

Land Fragmentation and Heirs Property: Current Issues and Policy Responses

Land fragmentation continues to be a challenge throughout the world, the United States, and particularly in the rapidly growing Southeast, as well as every state with a metropolitan area that abuts rural lands. With a United States population expected to grow to more than 500 million by 2060, it will present exceptional challenges for planners and policy makers to preserve important agricultural lands for farms and forests to provide both food and fiber, as well as to provide a host of ecosystem services and enhance the quality of life for our growing population. These issues of fragmentation are extremely substantial for African American, other minority, and limited-income landowners in the U.S. South, who often lack wills and have lands that are broken up into small parcels, or have divided ownership rights in one parcel, when passed on to heirs. Existing efforts can be expanded to provide tools and incentives for the owners of hiers property and other working lands to preserve them, and state and municipal planners will need to promote development plans and practices thoughtfully and strategically in order to prevent the projected loss of nearly 18 million acres of working lands by the year 2040.

ZnPc based multifunctional devices designed as fast capacitors, rectifiers, infrared detectors and microwave resonators adequate for 6 G technology applications

Herein Zinc phthalocyanine (ZnPc) based multifunctional devices are fabricated and characterized. The device fabrication included formation of an Au nanosheets onto n-Si wafers and coating these nanosheets with 500 nm thick ZnPc layer. Silver and platinum were used to form a Schottky and an ohmic contacts with n-Si and ZnPc, respectively. The device hybrid structure (Ag/n-Si/Au/p-ZnPc/Pt; abbreviated as ASZ) is composed of Ag/n-Si Schottky arm and p- and n- layers forming pn junction separated by Au nanosheets. Electrical and photoelectrical measurements on the ASZ devices have shown their ability to perform as conventional metal-oxide-semiconductor capacitors (CMOS). These CMOS devices showed light and frequency controlled charge accumulation, depletion and inversion mechanisms within the range of 1.0–50 MHz. The flat band and threshold voltages of the ASZ capacitors are engineered by the imposed ac signal frequency and by infrared (IR) light. In addition, ASZ devices performed as biasing controlled IR photosensors and as current rectifiers. A rectification ratio of 103, IR light sensitivity of 39, specific detectivity of .96 ×109 Jones and current responsivity exceeding 9.0 mA W−1 are recorded at biasing voltage of 4.5 V. Moreover ASZ devices displayed microwave resonator characteristics presented by negative capacitance effect, resonance –antiresonance phenomena and high microwave cutoff frequency. The latter is larger than 10 GHz nominating the device for 6 G technology applications.

A high-performance terahertz detector based on a graded channel GaN high-electron-mobility transistor with a recessed gate

A novel recessed gate graded AlGaN high-electron-mobility transistor (RGGA HEMT) for high-sensitivity terahertz (THz) detectors is reported, which exhibits significant potential for high-sensitivity THz detectors, and consequently. The simulation results indicate the exceptional field-effect factor of the proposed RGGA HEMT, which is largely attributed to the three-dimensional electron gas generated by the graded AlGaN barrier layer and the subsequent enhancement of channel conductance. The responsivity and noise equivalent power reach 58mA/W and 43pW/Hz respectively at 227GHz by utilizing a technical computer-aided design platform. As compared to conventional structure GaN HEMT experimental data, the current responsivity is improved by 2.64 times, and the NEP is reduced by 43.4%. The unprecedented improvement in detection performance renders the RGGA HEMT a highly promising approach for future THz real-time single-pixel imaging applications at room temperature.

Synthesis and transformation of graphene-like structures from bamboo waste for photoelectrochemical devices

This study presents a sustainable and versatile approach to synthesize graphene-like structures from bamboo waste for application in photoelectrochemical (PEC) devices. Due to its high cellulose content, bamboo, a locally available and renewable resource, is a perfect precursor for producing graphene-like materials. The synthesis process involves bamboo waste pyrolysis, followed by treatments with different solvents: ultrapure water (UPW), NaOH, and green tea extract. Characterization techniques confirmed the successful transformation of bamboo waste into carbon-rich, graphene-like materials with varying surface properties. The electrochemical characterization showed that the graphene-like materials could transfer electrons very well with a high current response compared to charcoal as a precursor. PEC evaluations revealed their potential as photoanodes, exhibiting efficient light absorption and charge carrier separation. This research emphasizes the significance of bamboo waste as a valuable precursor for eco-friendly graphene-like materials, offering a sustainable pathway for developing efficient PEC devices and green energy technologies.

A Surfactant-Electropolymer modified dual sensor for the monitoring of norepinephrine at nanomolar levels in biological samples and pharmaceutical formulations

This paper focuses on the surface modification of a Glassy carbon electrode (GCE) using poly-terephthalic acid and poly-4-amino-3-hydroxy-1-naphthalenesulfonic acid (poly-(TERE-AHNSA)/GCE) by a simultaneous electropolymerization of respective monomers for the first time from the best of our knowledge, which is a simple and cost-effective method. FTIR, AFM, and SEM-EDX examinations were used to confirm the developed electrode. The adapted electrode is then used for the monitoring and determination of clinically significant norepinephrine (NE) using electroanalytical techniques such as differential pulse and cyclic voltammetry. The electrooxidation of NE on poly-(TERE-AHNSA)/GCE occurred at a potential of +0.216 V in phosphate buffer solution (PB) of pH 6.0 and showed a higher current response compared to electrodes developed with separate electropolymers. This enhanced response is likely due to the synergistic effect of both polymer layers obtained through electropolymerization, which increases the surface area. The developed sensor exhibits favorable characteristics, including a lowest detection limit (LOD) of 2.08 nM, a linear range spanning from 5.0 nM to1600.0 μM which is the widest range ever reported, as well as improved sensitivity and selectivity, surpassing previous reports. The linearity analysis was also performed utilizing a screen-printed electrode (SPE), yielding linear ranges of 100.0 nM–600.0 μM. With a recovery rate ranging from 98 to 105%, the developed sensor shows great potential as a reliable tool for electroanalysis of NE in blood, urine, and pharmaceutical samples.

Transient response mitigation using type-2 fuzzy controller optimized by grey wolf optimizer in converter high voltage direct current

Long high voltage direct current (HVDC) transmission link is commonly used to transmit electrical energy via land or under-sea cable. The long HVDC avoids reactive power losses (RPL) and power stability problems (PSP). On the contrary, the RPL and PSP phenomena occur in long high voltage alternative current-link (HVAC) caused by the high reactive component in the HVAC-link. However, the HVDC produces a high and slow transient current response (TCR) on the high value of the up-ramp rate. Interval type-2 fuzzy (IT2F) control on converter-side HVDC is proposed to mitigate this TCR problem. The IT2F is optimized by grey wolf optimizer (GWO) to adjust input-output IT2F parameters optimally. The performance of IT2F-GWO is assessed by the minimum value of integral time squared error (ITSE), peak overshoot, and settling time of the TCR. The IT2FC-GWO performance is validated by the performance of IT2F control that is optimized by genetic algorithm (IT2F-GA) and proportional integral (PI) controller. Simulation results show that the IT2F-GWO performs better with small ITSE, low peak overshoot, and shorter settling times than competing controllers.

Nitrate Sensor with a Wide Detection Range and High Stability Based on a Cu-Modified Boron-Doped Diamond Electrode

This paper describes an electrochemical sensor based on a Cu-modified boron-doped diamond (BDD) electrode for the detection of nitrate-contaminated water. The sensor utilizes the catalytic effect of copper on nitrate and the stability of the BDD electrode. By optimizing the electrolyte system, the linear detection range was expanded, allowing the sensor to detect highly concentrated nitrate samples up to 100 mg/L with a low detection limit of 0.065 mg/L. Additionally, the stability of the sensor was improved. The relative standard deviation of the current responses during 25 consecutive tests was only 1.03%. The wide detection range and high stability of the sensor makes it suitable for field applications and the on-site monitoring of nitrate-contaminated waters.

Label-free simultaneous detection of quinolone antibiotic residues using an origami paper–based electrochemical immunosensor

Label-free electrochemical sensors have gained popularity as point-of-care devices because they do not require complicated labeling procedures. However, they have difficulties detecting multiple analytes simultaneously. In this study, we developed a novel label-free electrochemical immunosensor on an origami paper–based analytical device (oPAD) for the simultaneous detection of quinolone antibiotics, in which norfloxacin (Nor) and enrofloxacin (Enr) were used as a model. The oPAD was designed with two antibody zones, each zone contains different antibodies. The oPAD has two thionine- and ferrocenecarboxylic acid-coated reagent zones, as redox species, which will generate the response current signals for the detection of quinolone antibiotics. The simultaneous current responses of thionine and ferrocenecarboxylic acid decreased proportionately when exposed to Nor and Enr concentrations, respectively. Under optimal conditions, this device provided linear range at concentrations of 0.01–10 µg/mL for the detection of Nor and Enr and limit of detection was calculated as 2.02 and 1.70 ng/mL, respectively. Moreover, this device demonstrates performance comparable to standard methods for the simultaneous detection of Nor and Enr in milk, honey, and fish. Therefore, label-free electrochemical immunosensors provide a highly potent, inexpensive, and portable method for detecting multiple quinolone antibiotics simultaneously on a single device.