Search Results (733)

This work explores a novel and efficient synthetic approach to a new class of boron cluster derivatives via the nucleophilic addition of stabilized phosphorus ylides, Ph₃P=CHR² (R² = COOEt, CN), to a series of nitrilium salts of the closo-decaborate anion, [2-B₁₀H₉NCR¹]⁻ (R¹ = Me, Et, ⁿPr, ⁱPr, Ph). The reaction proceeds regio- and stereospecifically, affording a diverse range of iminoacyl phosphorane derivatives, [2-B₁₀H₉NH=C(R¹)C(PPh₃)R²]⁻, in high isolated yields (up to 95%). The obtained compounds (10 examples) were isolated as tetrabutylammonium or tetraphenylphosphonium salts and thoroughly characterized by multinuclear NMR (¹¹B, ¹H, ¹³C, ³¹P), high-resolution mass spectrometry, and single-crystal X-ray diffraction. The reaction feasibility was found to be strongly influenced by the steric hindrance of the R¹ group. Furthermore, the practical utility of these novel hybrids was demonstrated by employing the [2-B₁₀H₉NH=C(CH₃)C(COOC₂H₅)=PPh₃]⁻ anion as a highly effective membrane-active component in ion-selective electrodes. The developed tetraphenylphosphonium (TPP⁺) sensor exhibited a near-Nernstian response, a low detection limit of 3 × 10⁻⁸ M, and excellent selectivity over a range of common inorganic and organic cations, showcasing the potential of closo-borate-based ionophores in analytical chemistry. Full article

To address the issue of low fertilizer proportioning accuracy in irrigation and fertilization systems due to neglecting the influence of target ions in raw water, this study designed a high-precision online automatic water–fertilizer mixing device that can directly mix raw water (without water purification treatment) with fertilizer stock solution. This device is capable of preparing mixed fertilizer solutions containing N, K, and Ca elements. It employs ion-selective electrodes and flow meters for online detection and feedback of target ion concentrations in the fertilizer solution and flow rate information, and adopts an online fertilizer mixing control strategy that uses a constant raw water flow rate and a fuzzy PID control method to dynamically adjust the pulse frequency of metering pumps, thereby changing the injection volume of nutrient solution. Simulation and experimental analyses show that the piping system of the device is reasonably designed, ensuring stable and smooth fertilizer injection. The temperature-compensated concentration detection models for the three target ions in the fertilizer solution, constructed using a stepwise fitting method, achieve average relative detection errors of 1.94%, 1.18%, and 2.87% for K⁺, NO₃⁻, and Ca²⁺, respectively. When preparing single-element or mixed fertilizer solutions, the device achieves an average steady-state error of no more than 4% and an average steady-state time of approximately 40 s. Compared with deionized water, the average relative errors for potassium ions, nitrate ions, and calcium ions when preparing fertilizer solutions with raw water are 1.33%, 1.12%, and 1.19%, respectively. Compared with the theoretical errors of fertilizer preparation with raw water, the fertilizer proportioning errors of this device for potassium ions, nitrate ions, and calcium ions can be reduced by a maximum of 10.55%, 66.84%, and 62.71%, respectively, which is superior to the performance requirements for water–fertilizer integration equipment specified in the national industry standard DG/T 274-2024. Additionally, the device achieves accurate and stable fertilizer proportioning with safe and reliable operation during 6 h of continuous operation. This device significantly reduces the impact of raw water on fertilizer proportioning accuracy, improves the adaptability of the device to irrigation water sources, and provides theoretical basis and technical support for water-fertilizer integration systems in cost-sensitive agriculture. Full article

This review presents a critical and comparative analysis of carbon-based electrochemical sensing platforms for the determination of heavy metal ions in water, with emphasis on Pb²⁺, Cd²⁺, and Hg²⁺. The growing discharge of industrial and mining effluents has led to persistent contamination of aquatic environments by toxic metals, creating an urgent need for sensitive, rapid, and field-deployable analytical technologies. Carbon-based nanomaterials, including graphene, carbon nanotubes (CNTs), and MXene, have emerged as key functional components in modern electrochemical sensors due to their high electrical conductivity, large surface area, and tunable surface chemistry. Based on reported studies, typical detection limits for Pb²⁺ and Cd²⁺ using differential pulse voltammetry (DPV) on glassy carbon and thin-film electrodes are in the range of 0.4–1.2 µg/L. For integrated thin-film sensing systems, limits of detection of 0.8–1.2 µg/L are commonly achieved. MXene-based platforms further enhance sensitivity and enable Hg²⁺ detection with linear response ranges typically between 1 and 5 µg/L, accompanied by clear electrochemical or optical signals. Beyond conventional electrochemical detection, this review specifically highlights self-sustaining visual sensors based on MXene integrated with enzyme-driven bioelectrochemical systems, such as glucose oxidase (GOD) and Prussian blue (PB) assembled on ITO substrates. These systems convert chemical energy into measurable colorimetric signals without external power sources, enabling direct visual identification of Hg²⁺ ions. Under optimized conditions (e.g., 5 mg/mL GOD and 5 mM glucose), stable and distinguishable color responses are achieved for rapid on-site monitoring. Overall, this review not only summarizes current performance benchmarks of carbon-based sensors but also identifies key challenges, including long-term stability, selectivity under multi-ion interference, and large-scale device integration, while outlining future directions toward portable multisensor water-quality monitoring systems. Full article

This paper reviews tab-to-busbar interconnections in lithium-ion battery packs, focusing on resistance welding (RW), laser beam welding (LBW), and ultrasonic welding (USW). The functional roles of tabs and busbars and typical material choices (Al-, Cu-, and Ni-plated Cu) are outlined. Subsequently, the processes are compared in terms of heat input, interfacial metallurgy, electrical resistance, mechanical robustness, and manufacturability. USW, as a solid-state method, suppresses porosity and limits Al-Cu intermetallic growth, but is sensitive to thickness, stack geometry, and tool wear. LBW enables high-speed, automated production with precise energy delivery, yet requires careful control to mitigate spatter, porosity, and brittle IMCs in dissimilar joints. RW remains cost-effective and flexible but can suffer from electrode wear and variability with highly conductive stacks. This review also summarizes the effect of the busbar material (Al versus Cu) and thickness on the connection resistance and temperature increase under a high current. No single process is universally superior, and the selection should match the stack-up, reliability targets, and production constraints. This paper aims to provide an overview of recent and conventional research trends for each welding method and to introduce selected non-traditional approaches, thereby presenting a range of viable options for future applications. Full article

Real-time monitoring is essential for maintaining water quality and optimizing aquaculture productivity. Ion-selective electrodes (ISEs) are widely used to measure key parameters such as pH, nitrate, and dissolved oxygen in aquatic environments. However, these sensors are prone to fouling, the non-specific adsorption of organic, inorganic, and biological matter, which leads to potential drift (e.g., 1–10 mV/h), loss of sensitivity (e.g., ~40% in 20 days), and reduced lifespan (e.g., 3 months), depending on membrane formulation and environmental conditions. This review summarizes current research from mostly the last two decades with around 150 scientific studies on fouling phenomena affecting ISEs, as well as recent advances in fouling detection, cleaning, and antifouling strategies. Detection methods range from electrochemical approaches such as potentiometry and impedance spectroscopy to biochemical, chemical, and spectroscopic techniques. Regeneration and antifouling strategies combine mechanical, chemical, and material-based approaches to mitigate fouling and extend sensor longevity. Special emphasis is placed on environmentally safe antifouling coatings and material innovations applicable to long-term monitoring in aquaculture systems. The combination of complementary antifouling measures is key to achieving accurate, stable, and sustainable ISE performance in complex water matrices. Full article

Simultaneous detection of multiple neurochemicals and toxic metal ions in real time remains a major analytical challenge in neurochemistry and environmental sensing. In this study, we present a novel, biocompatible, laser-trimmed four-bore carbon fiber microelectrode (CFM) platform capable of ultra-fast, multi-analyte detection using fast-scan cyclic voltammetry (FSCV). Each of the four carbon fibers, spaced nanometers apart within a glass housing, was independently functionalized and addressed with a distinct waveform, allowing the selective and concurrent detection of four analytes without electrical crosstalk. To validate the system, we developed two electrochemical detection paradigms: (1) selective electrodeposition of gold nanoparticles (AuNPs) on one fiber for enhanced detection of cadmium (Cd²⁺), alongside dopamine (DA), arsenic (As³⁺), and copper (Cu²⁺); and (2) Nafion-modification of two diagonally opposing fibers for discriminating DA and serotonin (5-HT) from their interferents, ascorbic acid (AA) and 5-hydroxyindoleacetic acid (5-HIAA), respectively. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis confirmed surface modifications and the spatial localization of electrodeposited materials. Electrochemical characterization in tris buffer, which mimics artificial cerebrospinal fluid, demonstrated enhanced analytical performance. Compared to single-bore CFMs, the four-bore design yielded a 28% increase in sensitivity for Cd²⁺ (147.62 to 190.02 nA µM⁻¹), 12% increase for DA (10.785 to 12.767 nA µM⁻¹), and enabled detection of As³⁺ with a sensitivity of 0.844 nA µM⁻¹, which was not possible with single-bore electrodes within the mixture of analytes. Limits of detection improved twofold for both DA (0.025 µM) and Cd²⁺ (0.005 µM), while As³⁺ was detectable down to 0.1 µM. In neurotransmitter-interference studies, sensitivity increased by 39% for DA and 33% for 5-HT with four-bore CFMs compared to single-bore CFMs, despite modest Nafion diffusion onto adjacent fibers. Overall, our four-bore CFM system enables rapid, selective, and multiplexed detection of chemically diverse analytes in a single scan, providing a highly promising platform for real-time neurochemical monitoring, environmental toxicology, and future integration with AI-based in vivo calibration models. Full article

The accurate monitoring of metal ions is essential for applications that include environmental protection, food safety, and biomedical diagnostics. These areas depend on highly sensitive and selective methods for detecting both toxic and biologically relevant ions. Electrochemical sensors have emerged as promising devices due to their excellent sensitivity, cost-effectiveness, and ease of use. Within these sensor systems, ionophores, either synthetic or natural ligands that exhibit selective ion binding, are fundamental in boosting analytical performance. This review outlines the current progress of ionophore-based electrochemical sensors for metal-ion analysis, emphasizing material selection, architectural strategies, and practical applications. Key classes of ionophores, such as crown ethers, calixarenes, Schiff bases, porphyrins, and oxime derivatives, are discussed with an emphasis on their recognition mechanisms. We also examine strategies for incorporating ionophores into diverse electrochemical sensor configurations and explore recent advances in technologies, such as all-solid-state sensor construction and the development of portable analytical devices. This review bridges the chemistry of ionophores with sensor engineering and serves as a resource for the rational development of advanced platforms for metal-ion sensing. Full article

Continuous use of clear aligners modifies the oral environment and may favor bacterial colonization. Integration of topical fluoride-based agents could strengthen enamel and reduce biofilm formation. This study evaluated the effects of a galenic fluoride-mint spray (225–250 ppm fluoride and 1–2% peppermint essential oil) on salivary fluoride concentration and bacterial biofilm during orthodontic treatment. Ten patients using 3D-printed nighttime aligners were enrolled. Saliva samples were analyzed with an ion-selective electrode (ISE) at baseline, immediately after inserting the sprayed aligners and after 15, 30, 45 min post application. Biofilm morphology was qualitatively assessed by scanning electron microscope (SEM) in three aligners: unused, worn 14 nights without spray, worn 14 nights with spray. Salivary fluoride increased from 0.7–0.8 mg/L at baseline to 5.96 mg/L when the spray was applied on a new aligner and 8.42 mg/L on a used aligner, then progressively decreased, returning close to baseline at 45 min with the new aligner and remaining higher with the used aligner. SEM images showed mature and heterogeneous biofilm on used aligners without the spray, while aligners with nightly spray application exhibited qualitatively reduced and less organized surface deposits. The fluoride- and mint-based spray rapidly increases salivary fluoride and reduces biofilm formation on nighttime clear aligners, improving preventive oral health during orthodontic treatment. Full article

The rapid expansion of the electrode foil industry has led to the generation of large volumes of acidic wastewater containing strong acids (sulfuric and hydrochloric) and metal ions (such as aluminum and copper). The generated wastewater poses serious environmental challenges, including infrastructure corrosion, soil acidification, and toxicity to aquatic life. This review evaluates three primary treatment approaches: neutralization (adjusting pH and removing metals), ion adsorption (selective recovery of metals and acid recycling), and membrane separation (precision resource recovery). Neutralization is cost-effective for pH adjustment and metal removal but is limited by secondary pollution and low resource recovery. Ion adsorption allows for the targeted recovery of metals and recycling of acid, although it faces challenges related to high costs and scalability. Membrane separation offers accurate separation and resource recovery but is affected by fouling and high energy requirements. Future research should focus on integrated treatment strategies, AI-driven process optimization, and the development of advanced materials to enhance sustainable wastewater management. These efforts aim to provide a scientific basis and technical reference for wastewater treatment in the electrode foil industry. Full article

This study investigated the potential of a commercially available birch biochar, previously used as a soil amendment, for the adsorption of Pb²⁺ ions from aqueous solutions. For the first time, direct potentiometry with a lead ion-selective electrode was used for continuous in situ real-time monitoring of the adsorption process. The biochar demonstrated a maximum adsorption capacity of 14.21 mg/g (Langmuir model) and a high affinity for Pb²⁺. Kinetic analysis revealed a two-stage process limited by intraparticle diffusion. A significant decrease in pH and power-law dependencies between the adsorption parameters and the liquid/solid ratio confirmed ion exchange as the primary mechanism. Additionally, the biochar’s surface characteristics and accessibility for large molecules were evaluated by methylene blue adsorption, yielding a specific surface area of 4.0–6.6 m²/g. This value, being an order of magnitude lower than the BET surface area, highlighted the microporous nature of the biochar and its limited accessibility for bulky organic cations, providing crucial context for interpreting the lead adsorption mechanisms. The biochar effectively reduced the lead concentration to levels meeting the standards for irrigation water, demonstrating its dual application not only as an amendment but also as an effective and stable sorbent for water purification, while direct potentiometry proved to be a promising method for studying such processes. Full article

This study investigates all-solid-state batteries employing multifunctional metallic current collectors/electrodes that remain electrochemically inert toward an alkali-based Na ion solid electrolyte. Inconel 625 was evaluated as the positive current collector in combination with aluminum as the negative electrode and the ferroelectric electrolyte Na2.99Ba0.005OCl. The inertness of both electrodes enabled the construction of a robust device architecture that behaved as a true battery, exhibiting a two-phase equilibrium discharge plateau at ~1.1 V despite the absence of traditional Faradaic reactions. After a one-month rest period, the cell was sequentially discharged through external resistors and retained full functionality for one year. Cyclic voltammetry confirmed a stable electrochemical response over repeated cycling. The final long-term discharge under a 9.47 kΩ load produced a steady ~0.92 V plateau and delivered a total capacity of 35 mAh (~2.3 mAh·cm⁻²). Post-mortem analyses revealed excellent chemical and mechanical stability of Inconel 625 after extended operation, while aluminum showed superficial surface degradation attributed to residual moisture, with X-ray diffraction indicating the formation of aluminum hydroxide. Scanning Kelvin probe measurements guided electrode selection and provided insight into interfacial energetics, whereas scanning electron microscopy confirmed interface integrity. Complementary density functional theory simulations optimized the crystalline bulk and surfaces of Inconel, demonstrating interfacial stability at the atomic scale. Overall, this work elucidates the fundamental driving forces underlying traditional battery operation by studying a “capacity-less” system, highlighting the central role of interfacial electrostatics in sustaining battery-like discharge behavior in the absence of redox-active electrodes. Full article

This study presents the design and application of an electrochemical sensor for selective detection of lead ions (Pb²⁺) based on ionophore-modified raspberry-like Fe₃O₄–Au nanostructures. The material was engineered with a magnetic Fe₃O₄ core, coated with polyethyleneimine (PEI) to facilitate nucleation, and subsequently decorated with Au nanoparticles, providing a raspberry-like (Fe₃O₄@PEI@AuNPs) nanostructure with high surface area and excellent electrochemical conductivity. Surface functionalization with Lead Ionophore IV (ionophore thiol) introduced Pb²⁺-selective binding sites, whose presence and structural evolution were verified by TEM and Raman spectroscopy. The Fe₃O₄ core endowed strong magnetic properties, enabling facile manipulation and immobilization onto screen-printed carbon electrodes (SPCEs) via physical adsorption, while the Au nanoparticles enhanced electron transfer, supplied thiol-binding sites for stable ionophore anchoring, and increased the effective electroactive surface area. Operational conditions were systematically optimized, with acetate buffer (HAc/NaAc, pH 5.7) and chronoamperometric preconcentration (CA) at −1.0 V for 175 s identified as optimal for differential pulse voltammetry (DPV) measurements. Under these conditions, the sensor exhibited a linear response toward Pb²⁺ from 0.025 mM to 2.00 mM with superior sensitivity and reproducibility compared to conventional AuNP-modified SPCEs. Furthermore, the ionophore-modified Fe₃O₄–Au nanostructure-based sensor demonstrated outstanding selectivity for Pb²⁺ over competing heavy metal ions (Cd²⁺, Hg²⁺, Cr³⁺), owing to the specific coordination interaction of Lead Ionophore IV with target ions. These findings highlight the potential of raspberry-like Fe₃O₄@PEI@AuNP nanostructures as a robust and efficient electrochemical platform for the sensitive and selective detection of toxic heavy metal ions. Full article

Capacitive de-ionization (CDI) holds great promise for water desalination, while the widely used activated carbon (AC) electrodes suffer from a low salt adsorption capacity (SAC) and poor long-term stability due to the co-ion effect and electrode oxidation. Inspired by membrane-based CDI, we deposited polyethyleneimine (PEI), an ion exchange polymer with positive charge and ion selectivity, onto an AC electrode to serve as an anode for addressing these issues. Firstly, compared to traditional AC and commercial AEM-AC, the PEI-doped AC (PDAC) anode delivered a superior SAC of 36.3 mg/g, as the positively charged PEI enhanced electrostatic attraction, suppressed the co-ion effect, and offered extra sites. However, it showed poor cycling stability with 77.1% retention, owing to mass loss and anode oxidation. We further developed an electrode coated with a PEI-based membrane (PMAC), which exhibited a balanced performance with a high SAC of 33.4 mg/g and significantly improved long-term retention of 97.5%. The hydrophilic PEI membrane, strongly adhered to the AC surface, shortened the ion diffusion resistance and effectively prolonged the electrode lifespan. A systematic comparison between AC, AEM-AC, PDAC, and PMAC revealed the mechanism for PMAC’s notable enhancement. These findings establish a framework for designing novel CDI electrodes and advancing sustainable water desalination. Full article

Silver nanoparticles (AgNPs) are extensively utilized in cosmetics and healthcare products, creating an urgent need for sensitive quantification methods. We report the first application of a metal–organic framework for electrochemical AgNPs sensing in cosmetic samples. A glassy carbon electrode was modified with polyethyleneimine-encapsulated MOF-235 (PEI-MOF-235/GCE); the PEI layer enriches AgNPs through Ag–N coordination, whereas the high-surface-area MOF catalyzes their oxidative dissolution. Under optimized conditions (catalyst loading 1.4 µg mm⁻³, pH 4.3 PBS), differential-pulse voltammetry provided a linear range of 10–100 ng L⁻¹ and a detection limit of 3.93 ng L⁻¹ (S/N = 3). The sensor exhibited excellent stability (RSD ≤ 4.7%) and good anti-interference capability toward common aquatic ions. Compared with a standard HPLC method, recoveries in spiked cosmetic samples were 97.9–102.6%. This MOF-based strategy offers a sensitive, selective, and field-deployable platform for routine monitoring of trace AgNPs. Full article

Traditional medical techniques are constrained by macro-scale detection methods, making it difficult to capture dynamic changes at the cellular level. The miniaturization and high-throughput capabilities of integrated circuit technology enable precise manipulation and real-time monitoring of biological processes. In this study, COMSOL Multiphysics 6.3 software was used to model electrode units, simulating the interaction between cells and their biological environment. From the perspective of electrode arrays, the influence of varying electrode-cell contact areas on electrical signals was investigated, and the structure and layout of the microelectrode array (MEA) were optimized. The research explored the relationship between cellular activity and electrical properties, as well as the effect of cellular activity on membrane permeability. Simulation results demonstrated that larger electrode coverage areas improve potential distribution. The intact phospholipid bilayer and functional membrane proteins of living cells create a significant current-blocking effect, with impedance values reaching 10⁵–10⁶ Ω·cm². In contrast, apoptotic or necrotic cells exhibit structural damage and ion channel inactivation, leading to significantly enhanced membrane permeability, with impedance decreasing by 1–2 orders of magnitude. Further simulations involved modeling microfluidic channels to study cellular behavior within them. Frequency response analysis and Bode plots revealed that impedance differences between low and high frequencies could distinguish living cells (higher impedance) from apoptotic cells (lower impedance). Therefore, Bode plot analysis can assess membrane permeability and infer cellular health or apoptotic state. Additionally, this study examined micro-nanofabrication techniques, particularly the lift-off process for microelectrode fabrication, and optimized photoresist selection in photolithography. Full article