Search Results (167)

Electrical stimulation is increasingly explored as a strategy to accelerate the development of electroactive biofilms in microbial fuel cells (MFCs), yet its integration with photosynthetic MFCs (pMFCs) remains insufficiently understood. This study evaluated how short-term anodic stimulation (0.5–5 V, 4 days) affects biofilm formation and COD removal, and how subsequent operation with photosynthetic cathodes—Chlorella sp., Arthrospira platensis and Tetraselmis subcordiformis—modulates anodic microbial communities and functional potential. Stimulation at 1 V yielded the best activation effect, resulting in the highest voltage output, power density and fastest COD removal kinetics, whereas 5 V inhibited biofilm development. During pMFC operation, Chlorella produced the highest voltage (0.393 ± 0.064 V), current density (0.14 ± 0.02 mA·cm⁻²) and Coulombic efficiency (~19%). Arthrospira showed moderate performance, while Tetraselmis generated no current despite efficient COD removal. 16S rRNA sequencing revealed distinct cathode-driven community shifts: Chlorella enriched facultative electroactive taxa, Arthrospira promoted sulfur-cycling bacteria and Actinobacteria, and Tetraselmis induced strong methanogenic dominance. Functional prediction and qPCR confirmed these trends, with Chlorella showing increased pilA abundance and Tetraselmis displaying enriched methanogenic pathways. Overall, the combined use of optimal anodic stimulation and photosynthetic cathodes demonstrates that cathodic microalgae strongly influence anodic redox ecology and energy recovery, with Chlorella-based pMFCs offering the highest electrochemical performance. Full article

This work reports on the effects of surface pre-treatment and EPD process parameters on the nanomechanical and adhesive performance of chitosan-based composite coatings fabricated on a Ti13Zr13Nb alloy. Three different coating systems were prepared: chitosan–Cu (series A), chitosan–HAp (series B), and HAp–Cu (series C). Coatings were deposited from suspensions at different voltages (10–30 V) and for various times (1–2 min) onto polished, anodized, and laser surface-treated titanium alloy substrates. Microstructural, nanomechanical, and adhesion properties were characterized by means of SEM, nanoindentation, and nanoscratch testing, respectively. Chitosan–Cu coatings exhibited the highest hardness (up to 8.2 GPa) and stiffness due to the homogeneous dispersion of Cu nanoparticles and strong interfacial bonding to the underlying anodized TiO₂ layer. Chitosan–HAp coatings were softer (0.05–0.13 GPa) and highly plastic, particularly after laser surface treatment due to their specific porous, polymer-dominated structure. HAp–Cu coatings exhibited an intermediate mechanical behavior with a hardness between 0.1 GPa and 2.9 GPa and enhanced elastic recovery (Wp/We ≈ 3.5–4.7), particularly for anodized substrates. The nanoscratch test results showed that the HAp–Cu coatings exhibited the highest adhesion Lc (≈150–173 mN), confirming a synergistic effect of hybrid composition and heat treatment on interfacial toughness. The present data demonstrate that the optimization of anodizing and EPD processing parameters allows for the manipulation of the mechanical integrity and adhesion of bioactive chitosan-based coatings for titanium biomedical applications. Full article

The turbine mortise is a critical structural feature of turbine disks, and its manufacturing quality directly determines the performance and service life of aircraft engines. With the increasing application of advanced nickel-based superalloys, severe tool wear in conventional mechanical broaching of turbine mortises has emerged as a key limitation, substantially elevating production costs. Electrochemical broaching (ECB), which removes material through anodic dissolution reactions, eliminates tool wear and thus offers low cost and efficiency advantages, making it a promising method for turbine mortise fabrication. In this study, COMSOL Multiphysics 6.2 was employed to simulate the multiphysics field comprising the electric field, flow field, temperature field, bubble ratio, and dynamic mesh and elucidate the evolution of the electric field during the ECB process. ECB experiments of specimens on Inconel 718 were conducted under different feed speeds. On this basis, optimal processing parameters were identified. The results of the mid-position ECB experiments revealed five distinct dissolution states: pre-processing, pre-transition, stable dissolution, post-transition, and post-processing stages. A material dissolution mechanism model for the ECB process was established. Finally, fir-tree turbine mortises were successfully manufactured on Inconel 718 using a self-developed specialized electrochemical machining system at a feed speed of 70 mm/min. The mortise profile demonstrated dimensional deviations of (+16 to −21) μm, with working surface variations maintained within ±5 μm. The machined surfaces exhibited uniform and dense morphology with a surface roughness of Ra 0.275 μm. Three sets of mortise specimens processed under identical parameters showed excellent consistency, presenting a maximum deviation in profile removal thickness of +4.1 μm. The tool cathode was repeatedly reused without any detectable wear. Full article

The recent increase in end-of-life (EoL) lithium-ion batteries (LiBs) has become a significant concern worldwide. Most studies in the literature have primarily focused on recovering cathode active metals from black mass (BM), whereas the separation of anode–cathode foils, plastics, and casing metals which are the essential components of LiBs has received relatively little attention. To reduce costs and maximize the recovery of valuable metals in subsequent hydrometallurgical or pyrometallurgical processes, EoL LiBs require appropriate pre-treatment. This study aims to scrape off the BM adhering to the electrode foils resulting from gradual crushing and subsequently separate the plastics and copper (Cu) from other metals through a two-step selective flotation process. The results demonstrated that plastics, due to their natural hydrophobicity, could be effectively removed using a frother, achieving more than 95% recovery with less than 5% metallic contamination. Following plastic flotation, Cu particles were floated in the presence of 3418A, yielding a Cu concentrate containing 65.13% Cu with a recovery rate of 96.4%. Additionally, the aluminum (Al) content in the non-floating material, remaining in the cell, increased to approximately 77%. Full article

Recycling of lithium-ion batteries (LIBs) requires efficient separation of active material from current collectors to enable high-quality recovery of both the coating and the metal foil. In this study, a water-based delamination process for anode foils was systematically investigated under variations in temperature, particle size, ultrasonic power, and prior mechanical stressing of the particles. Mechanically cut and pre-folded foil pieces were treated in a batch setup at different temperatures (room temperature to 100 °C) and ultrasonic power levels (50 and 100%). Results show that higher temperatures strongly promote delamination, with 100% removal of the active layer achieved on the smooth foil side at 80 °C without ultrasonic treatment. Ultrasonic treatment at moderate power (50%) yielded greater delamination than at full power (100%), likely due to more effective cavitation dynamics at moderate intensity. Mechanical pre-stressing by folding significantly reduced delamination, with three folds effectively preventing separation. In comparison, mechanically comminuted particles from a granulator achieved similar delamination to three-folded particles after 5 min treatment, and higher delamination after 30 min. These findings highlight the importance of process parameters in achieving efficient aqueous delamination, providing insights for scaling low-energy recycling processes for LIB production scrap. Full article

The paper presents experimental results for a modified pulsed plasma thruster (PPT) with solid propellant, using a coaxial anode–cathode design. Graphite from pencil leads served as propellant, and a tungsten trigger electrode was tested to reduce carbonization effects. Experiments were performed in a vacuum chamber at 0.001 Pa, employing diagnostics such as discharge current/voltage recording, power measurement, ballistic pendulum, time-of-flight (TOF) method, and a Faraday cup. Current and voltage waveforms matched an oscillatory RLC circuit with variable plasma channel resistance. Key discharge parameters were measured, including current pulse duration/amplitude and plasma channel formation/decay dynamics. Impulse bit values, obtained with a ballistic pendulum, reached up to 8.5 μN·s. Increasing trigger capacitor capacitance reduced thrust due to unstable “pre-plasma” formation and partial pre-discharge energy loss. Using TOF and Faraday cup diagnostics, plasma front velocity, ion current amplitude, current density, and ion concentration were determined. Tungsten electrodes produced lower charged particle concentrations than graphite but offered better adhesion resistance, minimal carbonization, and stable long-term performance. The findings support optimizing trigger electrode materials and PPT operating modes to extend lifetime and stabilize thrust output. Full article

Thallium is a soft metal with a grey or silvery hue. It commonly occurs in two oxidation states in chemical compounds: Tl⁺ and Tl³⁺. Thermodynamically, Tl⁺ is significantly more stable and typically represents the dominant form of thallium in environmental systems. However, in this chemical form, thallium remains highly toxic. This study focuses on the modification of a glassy carbon electrode (GCE) with silver nanostructures stabilised by potato starch derivatives. The modified electrode (GCE/AgNPs-E1451) was used for the determination of trace amounts of thallium ions using anodic stripping voltammetry. Emphasis was placed on assessing the effect of surface modification on key electrochemical performance parameters of the electrode. Measurements were carried out in a base electrolyte (EDTA) and in a real soil sample collected from Bali. The stripping peak current of thallium exhibited linearity over the concentration range from 19 to 410 ppb (9.31 × 10⁻⁸ to 2.009 × 10⁻⁶ mol/dm³). The calculated limit of detection (LOD) was 18.8 ppb (9.21 × 10⁻⁸ mol/dm³), while the limit of quantification (LOQ), corresponded to 56.4 ppb (2.76 × 10⁻⁷ mol/dm³). The GCE/AgNPs-E1451 electrode demonstrates several significant advantages, including a wide detection range, reduced analysis time due to the elimination of time-consuming pre-concentration steps, and non-toxic operation compared to mercury-based electrodes. Full article

This study investigates the corrosion resistance of EN AW 6060 aluminum alloy powder-coated samples, with and without pre-anodizing treatment. The samples were exposed to a 3.5% NaCl solution, which is known for its strong corrosive effects, and their corrosion behavior was evaluated using two electrochemical techniques: Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS). The aim was to assess the effectiveness of powder coatings in enhancing corrosion resistance and to examine the role of surface preparation and prior treatments. Polarization tests provided corrosion current densities and corrosion rates, while EIS data were analyzed using equivalent electrical circuits to evaluate the integrity of the protective layers. The results show that powder coatings significantly improves corrosion resistance compared to uncoated aluminum and the combination of pre-anodizing followed by painting offers the highest protection. These findings confirm the improved performance achieved through multilayer surface treatments and support the application of powder coatings acting as a durable barrier against environmental factors. Full article

Aluminum is widely used in many industries like automotive, aerospace and construction because of its low weight, good mechanical strength and resistance to corrosion. This resistance comes mainly from a passive oxide layer that forms on its surface. However, when aluminum is exposed to harsh environments, especially those containing chloride ions in marine environments, this layer can break down and lead to localized corrosion, such as pitting. This study examined aluminum profiles at different processing stages, including homogenization and aging, anodizing and pre-anodizing followed by painting. Corrosion behavior of samples was studied using two electrochemical methods. Potentiodynamic polarization was used to measure corrosion rate and current density, while Electrochemical Impedance Spectroscopy (EIS) helped to understand the behavior of protective layers and corrosion progression. Tests were carried out in a 3.5% NaCl solution at room temperature. EIS results were analyzed using equivalent circuit models to better understand electrochemical processes. Overall, this study shows how surface treatment affects corrosion resistance and highlights advantages of EIS in studying corrosion behavior in a more reliable and repeatable way. Full article

This study assesses how different anode materials influence neutron production rates (NPRs) in multi-state fusion (MSF) reactors, with a particular focus on the effects of deuterium (D) pre-loading on the anode surface. Three types of mesh anodes were assessed: stainless steel (SS), zirconium (Zr), and D pre-loaded zirconium (ZrD). MSF operates using two electrodes to confine ions to various fusion reactions, including D-D and D-T. The reactor features a negatively biased central cathode and a grounded anode within a vacuum vessel. Neutrons and protons are produced through the application of high voltage (tens of kV) and current (tens of mA) on the system to spark the plasma and start the fusion. Assessments at voltages up to 50 kV and currents up to 30 mA showed that Zr mesh anodes produced higher NPRs than SS ones, reaching 1.912 at 30 kV. This increased performance is attributed to surface fusion processes occurring in the anode. These processes were further modified by the deuterium pre-loading in the ZrD anode, as compared to SS and Zr with 1.832 at 30 kV. The findings suggest that material properties and deuterium pre-loading play significant roles in optimizing the efficiency of MSF reactors and the NPR. Future research may explore the long-term stability and durability of these anode materials under continuous operation conditions to fully harness their potential in fusion energy applications. Full article

Transcranial direct current stimulation (tDCS) can modulate cortical excitability in a polarity-specific manner, yet identical protocols often produce inconsistent outcomes across sessions or individuals. This narrative review proposes that much of this variability arises from the brain’s intrinsic temporal landscape. Integrating evidence from chronobiology, sleep research, and non-invasive brain stimulation, we argue that tDCS produces reliable, polarity-specific after-effects only within a circadian–homeostatic “window of efficacy”. On the circadian (Process C) axis, intrinsic alertness, membrane depolarisation, and glutamatergic gain rise in the late biological morning and early evening, whereas pre-dawn phases are marked by reduced excitability and heightened inhibition. On the homeostatic (Process S) axis, consolidated sleep renormalises synaptic weights, widening the capacity for further potentiation, whereas prolonged wakefulness saturates plasticity and can even reverse the usual anodal/cathodal polarity rules. Human stimulation studies mirror this two-process fingerprint: sleep deprivation abolishes anodal long-term-potentiation-like effects and converts cathodal inhibition into facilitation, while stimulating at each participant’s chronotype-aligned (phase-aligned) peak time amplifies and prolongs after-effects even under equal sleep pressure. From these observations we derive practical recommendations: (i) schedule excitatory tDCS after restorative sleep and near the individual wake-maintenance zone; (ii) avoid sessions at high sleep pressure or circadian troughs; (iii) log melatonin phase, chronotype, recent sleep and, where feasible, core temperature; and (iv) consider mild pre-heating or time-restricted feeding as physiological primers. By viewing Borbély’s two-process model and allied metabolic clocks as adjustable knobs for plasticity engineering, this review provides a conceptual scaffold for personalised, time-sensitive tDCS protocols that could improve reproducibility in research and therapeutic gain in the clinic. Full article

Transcranial direct current stimulation (tDCS) is a safe, well-tolerated method of non-invasively eliciting cortical neuromodulation. It has gained recent interest, especially for its positive clinical outcomes in neurodegenerative diseases such as multiple sclerosis (MS). However, its simultaneous (during tDCS) and cumulative effects (following repeated tDCS sessions) on the regional brain activity during rest need further investigation, especially in MS. This study aims to elucidate tDCS’ underpinnings, alongside its therapeutic impact in MS patients, using concurrent tDCS-MRI methods. In total, 20 MS patients (age = 48 ± 12 years; 8 males) and 28 healthy controls (HCs; age = 36 ± 15 years; 12 males) were recruited. They participated in a tDCS-MRI session, during which resting-state functional MRI (rs-fMRI) was used to measure the levels of the fractional amplitude of low-frequency fluctuations (fALFFs), which is an index of regional neuronal activity, before and during left anodal dorsolateral prefrontal cortex (DLPFC) tDCS (2.0 mA for 15 min). MS patients were then asked to return for an identical tDCS-MRI visit (follow-up) after 20 identical at-home tDCS sessions. Simultaneous tDCS-induced changes in fALFF are seen across cortical and subcortical areas in both HC and MS patients, with some regions showing increased and others decreased brain activity. In HCs, fALFF increased in the right pre- and post-central gyrus whilst it decreased in subcortical regions. Conversely, MS patients initially displayed increases in more posterior cortical regions but decreases in the superior and temporal cortical regions. At follow-up, MS patients showed reversed patterns, emphasizing significant cumulative effects of tDCS treatment upon brain excitation. Such long-lasting changes are further supported by greater pre-tDCS fALFFs measured at follow-up compared to baseline, especially around the cuneus. The results were significant after correcting for multiple comparisons (p-FDR < 0.05). Our study shows that tDCS has both simultaneous and cumulative effects on neuronal activity measured with rs-fMRI, especially involving major brain areas distant from the site of stimulation, and it is responsible for fatigue and cognitive and motor skills. Full article

Background: Youth (ages 16–25) is a key window for mental health interventions, as depression rates significantly increase during this developmental stage. However, transcranial direct current stimulation (tDCS) application in youth depression remains underexplored. To reduce the uncertainty of a future trial, we conducted a review and a pilot randomised controlled trial (RCT) of tDCS for youth depression. Methods: Following the PRISMA guidelines, the first part of this study was a review across databases including PubMed, MEDLINE, PsychInfo, CINAHL, Open Access Theses and Dissertations (OATD), WanFang Data, Chinese Medical Journal, and clinical trial registries up to 20 November 2024, on tDCS treatment for youth depression. The second part of this study was a double-blind pilot RCT assessing feasibility, by comparing active tDCS (five daily 30 min 2 mA anodal tDCS applications over the left dorsolateral–pre-frontal-cortex (DLPFC) with sham tDCS. Feasibility outcomes included recruitment, data collection, attendance, retention and randomisation. Outcomes also included depression severity using the Hamilton Depression Rating Scale (HDRS), safety, tolerability, acceptability, and adequacy of blinding. Mann–Whitney U tests were used for between-group comparison. Results: Fourteen eligible studies were identified, with a pooled HDRS reduction of −9.6 (95% CI: −11.2 to −8.1, p < 0.001), though high risks of bias indicated a research gap. Using parameters derived from the review, we conducted a pilot RCT in which 20 youths were screened and 8 were randomised (aged 16–24; 3 females, 5 males). All randomised participants completed their assigned sessions without dropout or protocol discontinuations. Blinding was adequate, and participants’ willingness to engage improved over time. Both groups showed reductions in HDRS, with a greater mean reduction in the active group (−4.75 ± 2.96) compared to the sham group (−3.75 ± 3.78). No serious adverse events occurred, with only mild headaches and tingling reported. The tolerability profile was comparable. However, the decentralised administration of sessions may have introduced inconsistent tDCS applications. Conclusions: This review highlights a lack of RCTs on tDCS for youth depression. Our pilot trial demonstrates the feasibility of a sham-controlled design in youth depression, justifying larger-scale trials to evaluate the efficacy of tDCS in this population. Full article

This study investigates the failure of a 750A dual-insulated pipeline, where cracks developed along the weld joints during heat supply resumption at the district heating facility. A comprehensive analysis was conducted through visual inspection, mechanical testing, microstructural characterization, finite element analysis (FEA), and electrochemical corrosion testing. The results indicate that cracks were generated in the heat-affected zone (HAZ), primarily caused by galvanic corrosion and thermal expansion-induced stress accumulation. Open circuit potential (OCP) measurements in a 3 M NaCl solution confirmed that the HAZ was anodic, leading to the most vulnerable position to corrosion. Furthermore, localized electrochemical tests were conducted for respective microstructural regions within the HAZ. The results reveal that coarse-grained HAZ exhibited the lowest corrosion potential, giving rise to preferential corrosion, promoting pit formation, and serving as initiation sites for stress concentration and crack propagation. FEA simulations demonstrate that pre-existing microvoids in the HAZ act as stress concentration sites, undergoing a localized stress exceeding 475 MPa. These findings emphasize the importance of controlling microstructural stability and mechanical integrity in welded pipelines, particularly in corrosive environments subjected to thermal stresses. Full article

Metal–organic frameworks (MOFs) are regarded as advanced supercapacitor materials owing to their high surface area, redox-active sites, and porosity. However, their insufficient charge carrier mobility remains a critical limitation for practical application. Integrating MOFs with conductive carbon substrates is an effective strategy to break through this limitation. However, conventional carbon materials often require complex preparation methods and pre-activation steps for use in MOF composites. Herein, multilayer graphene (MLG) mechanically exfoliated from expandable graphite is employed as a substrate, and a van der Waals force-assisted chemical deposition method is developed to directly anchor Ni-MOF onto its surface without requiring pre-activation treatment. To optimize the composite, Ni-MOFs with various mass loadings are synthesized on MLG surface. The morphological characteristics and energy storage performance of these composites are thoroughly characterized. Ni-MOF/MLG-0.30 (with a 70.8% Ni-MOF loading on MLG) features a porous stacking structure of well-crystalline Ni-MOF parallelogram nanosheets on MLG, exhibiting optimal electrochemical performance. The composite achieves 1071.4 F·g⁻¹ at 1 A·g⁻¹, and a capacitance retention of 64.9% at the elevated current density of 10 A·g⁻¹. Meanwhile, the composite maintains 63.2% of its initial capacitance after 5000 charge/discharge cycles at 4 A·g⁻¹. A hybrid supercapacitor is fabricated using Ni-MOF/MLG-0.30 cathode and activated carbon anode, delivering 27.9 Wh·kg⁻¹ energy density at 102.5 W·kg⁻¹ power output. Full article