Search Results (4,359)

In this study, the structural and electrochemical performance of Nb₂CT_x MXene-based composite electrodes modified with activated carbon (AC) derived from food waste was systematically investigated for supercapacitor applications. Three composites with Nb₂CT_x:AC mass ratios of 90:10 (MXAC1), 80:20 (MXAC2), and 70:30 (MXAC3) were prepared and comparatively evaluated. SEM/EDS, XRD, HR-TEM, XPS, and BET analyses revealed that, in the MXAC2 composite, activated carbon was homogeneously distributed between the MXene layers, effectively suppressing restacking and promoting the formation of a hierarchical micro/mesoporous structure. XPS results confirmed the preservation of the Nb–C framework and the enrichment of surface functional groups (–O, –OH, and –F). BET analysis demonstrated that MXAC2 possesses an optimized pore architecture that facilitates efficient ion diffusion. Electrochemical measurements revealed that the MXAC2 electrode exhibited the highest specific capacitance at all scan rates and current densities. At 5 mV·s⁻¹, MXAC2 achieved a specific capacitance of 651.84 F·g⁻¹ and maintained a substantial capacitance even at a high current density of 4 A·g⁻¹. EIS analysis confirmed the very low charge transfer resistance (0.023 Ω) and enhanced capacitive behavior for MXAC2. Additionally, MXAC2 has high cycle stability, demonstrating 82.15% capacitive retention and 92.45% coulombic efficiency after 10000 cycles. These results indicate that food waste-derived AC-optimized Nb₂CT_x MXene composite materials are a strong candidate for sustainable and high-performance supercapacitor electrodes. Full article

This study introduces a novel anticorrosion coating for copper based on an epoxy matrix reinforced with a berberine-loaded graphene oxide (BBR@GO) nanocomposite. The BBR@GO was synthesized via a simple, non-covalent functionalization method, leveraging π-π stacking interactions between the planar berberine molecule and the graphene oxide surface. The successful loading of berberine was confirmed by Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDS). The BBR@GO nanocomposite was incorporated into an epoxy resin at 0.1 wt.% loading and applied to a copper substrate. The corrosion protection performance of the BBR@GO/EP coating was systematically evaluated in 3.5 wt.% NaCl solution for 27 days using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The BBR@GO/EP coating exhibited a total impedance of 5.31 × 10⁸ Ω·cm² after 27 days, which was 17 times higher than the pure epoxy (EP) coating. The corrosion current density (i_corr) was reduced to 2.59 × 10⁻⁸ A·cm⁻², a four-fold decrease compared to the EP coating. Post-immersion analysis confirmed the excellent durability of the BBR@GO/EP coating and the retention of berberine within the matrix. The enhanced performance is attributed to the synergistic effect of the physical barrier provided by the well-dispersed GO nanosheets and the inhibitive action of the retained berberine molecules at the coating–metal interface. Full article

Monitoring the concentration of doxorubicin (DOX) was critical for tumor treatment, but existing methods failed to cross cell membrane. Here, an electrochemical platform for intracellular DOX detection in MCF-7 cells based on membrane-permeation strategy was developed. A modified gold electrode was prepared via electrodepositing AuNPs and assembling SH-DNA. Concurrently, the silica nanosphere/gold nanocluster-circular transmembrane peptide (SiO₂/AuNCs-iRGD) composite nanoparticles with membrane permeability, tumor targeting, and imaging capability were synthesized. After co-incubation of SiO₂/AuNCs-iRGD with MCF-7 cells and DOX, followed by co-incubation with the DNA-modified electrode, intracellular DOX intercalated into the DNA backbone, and redox-generated electrons were transferred to the electrode to produce a concentration-correlated electrochemical signal. The modification of the electrode, the morphology of the composite nanoparticles and the detection process were characterized by means of SEM, TEM, CV, EIS, DPV, fluorescence spectroscopy and laser confocal imaging. Under the optimized conditions, the proposed method exhibited a wide detection range of 0.05–300 μmol/L, with a detection limit of 0.01 μmol/L. Moreover, the modified electrode demonstrated satisfactory regenerability, and the proposed method showed excellent reproducibility and stability. The development platform could offer a new strategy for real-time assessment of drug concentration within cultured breast cancer cells in vitro. Full article

Over the past few decades, ionic liquids (ILs) have gained attention as electrolytes, although concerns about their environmental persistence and toxicity challenge their status as green solvents. In this framework, choline chloride (ChCl) offers a more sustainable alternative due to its low toxicity, biodegradability, and cost-effectiveness. Although ChCl has a high melting point, its combination with hydrogen bond donor compounds (HBDs) can result in liquid mixtures at much lower temperatures, known as deep eutectic solvents (DESs). This study presents a comparative evaluation of three ChCl-based DESs, glyceline, ethaline, and reline (obtained from mixtures of ChCl and glycerol, ethylene glycol, and urea), with a focus specifically on their potential as electrolyte candidates for supercapacitors. Using differential scanning calorimetry (DSC), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and nuclear magnetic resonance (NMR), we assess their thermal, electrochemical, and structural properties. All DESs displayed amorphous behavior and a strong tendency to remain liquid even at very low temperatures. Among them, ethaline showed the most promising electrochemical performance, exhibiting the lowest resistivity and the highest capacity. Full article

Three types of gradient plasma-assisted chemical vapour deposition (PACVD) coatings were produced on WC-Co hardmetal substrates: a TiN coating, a gradient TiCN coating with alternating TiN/TiCN layers and a multilayer TiBN system of TiN/TiB₂ layers. Their corrosion behaviour in a chloride environment was compared using direct current and alternating current electrochemical techniques. Potentiodynamic polarization, linear polarization and electrochemical impedance spectroscopy were carried out in 3.5 wt.% NaCl at temperature 20 ± 2 °C in a three-electrode cell with a saturated calomel electrode (SCE) reference. After 1000 s open circuit stabilization, TiN coating showed superior corrosion resistance with E_corr = 15 mV vs. SCE, versus TiCN (E_corr = −281 mV) and TiBN (E_corr = −304 mV). Linear polarization resistance/Tafel analysis showed significantly higher polarization resistance of TiN (R_p = 1559 kΩ∙cm²) than TiCN (195.4 kΩ∙cm²) and TiBN (243.6 kΩ∙cm²), with the lowest corrosion current density, j_corr = 10.97 nA∙cm⁻² and corrosion rate v_corr = 117.2 × 10⁻⁶ mm∙y⁻¹. TiCN showed the highest j_corr (360.8 nA∙cm⁻²) and v_corr (3.32 × 10⁻³ mm∙y⁻¹). Electrochemical impedance spectroscopy fitting with a R(QR) circuit confirmed this, with the highest charge transfer resistance at the substrate–electrolyte interface (R_ct) for TiN (8.198 × 10⁴ Ω∙cm²), lower for TiBN (7.929 × 10⁴ Ω∙cm²) and lowest for TiCN (1.435 × 10⁴ Ω∙cm²), indicating TiN as the best barrier and TiCN as the most permeable. Full article

The current study aimed to investigate sleep problems in children with Attention Deficit Hyperactivity Disorder (ADHD) within a framework highlighting emotion regulation (ER), emotional intensity (EI), oppositional defiant symptoms, and internalizing symptoms. A total of 100 children with ADHD and 50 controls aged 6–14 were recruited from University Hospital, and were assessed with semi-structured interviews. Parents completed the Children’s Sleep Habits Questionnaire, Conners’ Parent Rating Scale–Revised-Short, Emotion Regulation Scale for Children–Adult Form, and the Revised Children Anxiety and Depression Scale-Parent. Group comparisons, correlations, multiple regressions, and serial mediation models were conducted, adjusting for age, gender, and other covariates. After correction for multiple comparisons, sleep parameters and internalizing symptoms did not differ between groups. In the ADHD group, total sleep problems were correlated with ADHD and oppositional symptoms, EI, ER, and internalizing symptoms. Regression models indicated that internalizing symptoms predicted total sleep problems, while EI predicted night wakings. Across mediation models, internalizing symptoms consistently mediated associations between ADHD/oppositional symptoms and total sleep problems, with EI/ER contributing indirectly via internalization. Findings suggest that sleep problems related to ADHD are related to pathways of emotional distress, emphasizing the importance of assessing internalizing symptoms concurrently with behavioral/emotional processes during the evaluation of sleep problems. Full article

Nenestatins (NENs) belong to benzo[b]fluorene-containing atypical angucyclines, a structurally diverse class of microbial natural products. Bioinformatic analysis of the NEN biosynthetic gene cluster (nes BGC) from the deep-sea sediment-derived Micromonospora echinospora SCSIO 04089 implicated Nes5 as an α/β hydrolase. The targeted inactivation of the nes5 gene led to the accumulation of five new analogs, NENs E–I (1–5), together with the known monomer homo-dehydrorabelomycin E (6). Their structures were elucidated by comprehensive spectroscopic analysis and electronic circular dichroism calculations. Notably, both NEN A and NEN B were absent in the Δnes5 mutant, indicating that Nes5 is essential for their biosynthesis; however, the exact function of Nes5 requires further exploration. Full article

Titanium dioxide (TiO₂) nanotube arrays (NTAs) were constructed on Ti foil to immobilize Cu₂ZnSnS₄-TiO₂ (CZTS-T/NTAs) via the sol–gel dip-coating technique. The films were characterized by X-ray diffraction (XRD) patterns, field-emission scanning electron microscope–energy dispersive spectroscopy (FESEM-EDX), ultraviolet–visible diffuse reflectance spectra (UV–Vis/DRS), and electrochemical impedance spectroscopy (EIS) techniques. The photocatalytic property of CZTS-T/NTAs was evaluated by the photodegradation of Basic Blue 41 under visible light irradiation. We show that CZTS-T/NTAs have an energy band gap of 2.23 eV, which leads to excellent potential trapping or facilitates the transition of charge carriers under visible light. The parameters R₀ and C₀ of the experimental EIS data, by fitting the proposed electrical circuit, were also discussed. Decreasing R₀ led to an increase in cell capacitance, which resulted in increased carrier generation at the interface between the catalyst and solution and thus an increased photodegradation yield. The response surface methodology (RSM) and central composite rotatable design (CCRD) were used to optimize the effects of the experimental parameters in the degradation process by four key variables (pH, dye concentration, irradiation time, and hydrogen peroxide (H₂O₂) concentration). As a result, the optimized conditions attained a considerable degradation of 95.25%. We also proposed the possible photodegradation mechanism of the photocatalyst. Notably, the proposed catalyst after six consecutive reuse runs retained activity. Full article

The accelerated spread of generative artificial intelligence (GAI) is transforming firm-level production processes and performance outcomes, yet its implications for energy efficiency remain understudied. Using panel data on Chinese listed companies, this study examines how advances in GAI influence firms’ energy intensity (EI). The empirical evidence indicates that greater development of GAI is associated with a significant reduction in firms’ EI. Mechanism analyses reveal that GAI decreases EI by promoting firms’ human capital structure and dynamic capabilities. Furthermore, the negative relationship between GAI development and EI is larger when stronger informal environmental regulations are in place and for firms that have better internal environmental governance. This study extends prior research on the environmental implications of traditional AI and enriches the literature on GAI by moving beyond productivity and innovation outcomes. Our findings enhance the understanding of how dynamic technology evolution in AI reshapes the landscape of energy consumption and have important implications for efforts to improve energy efficiency under digital transformation. Full article

Catalytic ozonation often suffers from a low ozone utilization rate and incomplete mineralization of organic pollutants. To address these challenges, we designed and prepared a novel catalyst via a one-step thermal polymerization method, anchoring single-atom manganese on a glucose-derived carbon network-modified C₃N₅ framework (Mn/C-C₃N₅). Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) on an FEI Titan Themis Z microscope confirmed the atomic dispersion of Mn sites, while Raman spectroscopy using a Renishaw inVia Reflex laser micro-Raman spectrometer verified the successful incorporation of a graphitic carbon network within the C₃N₅ matrix. Moreover, electrochemical analyses, including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) performed on a Bio-Logic SP-150 electrochemical workstation, demonstrated that the integration of the conductive carbon matrix substantially enhanced the interfacial charge transfer capability. The optimized Mn/C-C₃N₅ catalyst demonstrated exceptional performance in phenol mineralization, achieving a 97% total organic carbon (TOC) removal within 60 min, a remarkable improvement compared to pristine C₃N₅ (30%). Furthermore, the catalyst exhibited excellent operational stability, preserving more than 95% of its original activity over five repeated runs. Mechanistic investigations, including electron paramagnetic resonance (EPR) spectroscopy and radical quenching experiments, revealed that the Mn/C-C₃N₅ system accelerated the generation of multiple oxidizing radicals (•O₂⁻, ¹O₂, and •OH), with •OH identified as the predominant reactive species responsible for complete mineralization. This work establishes an integrated catalytic platform and provides fundamental insights into electronic structure modulation for designing advanced oxidation catalysts. Full article

High-entropy amorphous materials are attracting increasing attention due to their excellent corrosion resistance and radiation tolerance in nuclear environments. In this study, novel Al₂Cr₁₆Fe₅₀V₂₀Ti₁₂ high-entropy alloy (HEA) coatings with thicknesses of 900 nm and 1400 nm were synthesized via magnetron sputtering and systematically evaluated for their structural, electrochemical, and mechanical performance. X-ray diffraction confirmed the amorphous nature of the coatings, while scanning electron microscopy revealed a denser, defect-free, and more uniform morphology in the thicker coating. Electrochemical testing in a 3.5 wt.% NaCl solution demonstrated a tenfold reduction in corrosion current density and nearly a twofold increase in charge transfer resistance for the 1400 nm coating, attributed to its improved passive film stability. Finite element modeling validated the experimental load–displacement behavior and revealed well-confined and uniformly distributed stress and strain fields within the coating. These findings establish the 1400 nm Al₂Cr₁₆Fe₅₀V₂₀Ti₁₂ coating as a promising candidate for protective applications in chloride-rich and radiation-intense nuclear systems. Full article

Aims: The aim of this study is to characterise corneal epithelial thickness profiles after Descemet membrane endothelial keratoplasty (DMEK) and compare it with healthy controls, focusing on inferior–superior (I–S) epithelial thickness differences and their relationship with age. Methods: This single-centre observational study included 36 post-DMEK eyes with at least 6 months’ follow-up and 36 healthy control eyes. High-resolution spectral-domain anterior segment OCT maps were analysed for central epithelial thickness (CET, defined as the mean epithelial thickness within the central 2 mm zone [E2.0]) and peripheral sectors to derive inferior (E–I) and superior (E–S) values (between 2 and 7 mm), with the I–S difference computed at a 3 mm radius; group comparisons used t-tests and correlations used Pearson’s r (α = 0.05). Central corneal thickness (CCT) was also compared between groups. Results: Post-DMEK eyes had significantly lower mean CCT than controls (525.7 ± 98.4 μm vs. 544.71 ± 27.8 μm, p = 0.04). Central epithelial thickness did not differ between groups (post-DMEK 53.7 ± 5.5 μm vs. controls 52.7 ± 3.3 μm, p = 0.62), but the I–S epithelial difference was greater after DMEK (5.9 ± 4.3 μm) than controls (3.0 ± 2.2 μm, p < 0.01), indicating a more pronounced inferior thickening pattern. Age showed no significant relationship with epithelial thickness in controls, and only very weak or non-significant correlations with central thickness and I–S difference in post-DMEK eyes, indicating no clinically meaningful age effect postoperatively. Conclusions: DMEK restores central epithelial thickness to values comparable to normal eyes, while accentuating the physiologic inferior–superior epithelial gradient, consistent with localised postoperative epithelial remodelling rather than global epithelial thickening or thinning. Corneal stromal remodelling may result in lower CCT post-DMEK versus controls, and age does not meaningfully influence epithelial distribution after surgery. Full article

Electric impedance spectrum (EIS) is attracting attention in many areas of science, ranging from electrochemistry and material science to medical diagnosis. Interestingly, theoretical description often stops at material constants and specific physical mechanisms are represented by equivalent circuit elements, which is also motivated by the common use of various bridge methods. This specifically applies to biological samples, which exhibit a rich variety of responses to the electric field. Here, we present a step further from the description that utilizes equivalent circuit elements. We demonstrate how alteration of the mesoscopic structure affects the EIS in a biological sample: a cucumber under thermal treatment that comprises a cooling and warming phase. As the freezing temperature of water is exceeded during the cycle, the cucumber becomes frosted, which leads to unrecoverable changes in the internal structure, with no change of chemical composition. The experimental evidence is complemented by theoretical analysis, based on a novel approach to modeling non-stationary problems, derived from the stationary Poisson–Boltzmann equation. We demonstrate a qualitative agreement between the theoretical and the experimental results, and discuss the procedure for tuning the model. We also demonstrate that, of the temperature variations of the position of the beta dispersion, the one related to the mesoscopic structure, can be used to assess the ionic strength of the material, determine the microscopic diffusion constant, or reflect the changes in mesoscopic structure, depending on experimental protocol. Full article

In this paper, the Distribution of Relaxation Times (DRT) method is introduced for analyzing aging and failure conditions in lithium-ion (Li-ion) batteries, addressing challenges associated with its implementation. While Electrochemical Impedance Spectroscopy (EIS) and Equivalent Circuit Models (ECMs) are commonly used to monitor battery performance, their interpretation is often complicated by overlapping semicircles in impedance spectra. The DRT technique resolves this issue by deconvolving relaxation times, enabling the separation of individual electrochemical processes and providing a clearer understanding of aging and failure conditions. The peaks of lower frequency components in DRT plots, specifically the charge transfer and diffusion processes, are key indicators of the battery failure point. When these two processes merge, it signals that the battery can no longer function, marking a critical failure point in Li-ion batteries. Identifying failure conditions and aging in Li-ion batteries using DRT offers a more advanced approach compared to ECM, as it delivers greater detail in the electrochemical processes that contribute to performance degradation. The analysis of two kinds of different Lithium-Ion battery cells based on the DRT reveals the specific aging and failure patterns, particularly in later battery life stages. The findings demonstrate the potential of DRT as a real-time indicator to monitor the status and the lifecycle of the battery. Full article

Combined oral contraceptive pills (COCPs) are commonly used by reproductive-aged women with overweight or obesity, but their metabolic effects remain understudied. This pilot study examined the feasibility of recruiting and retaining women with overweight or obesity initiating COCPs and evaluated changes in body weight, body composition, energy intake (EI), eating behaviors, and cardiometabolic markers. Premenopausal women aged 18–40 years with a body mass index between 25 and 45 kg/m² initiating COCPs (n = 10) or using nonhormonal contraception (NHC; n = 10) were followed for six months. Outcome measures included body weight, body composition, EI, eating behavior questionnaires, ecological momentary assessment of appetite and satiety, and fasting laboratory measures. There were no between-group differences in changes in weight, EI, or appetite. Binge-eating severity decreased in COCP users and increased in NHC users, though the within-group change in COCP users was not statistically significant. Exploratory analyses demonstrated increases in hemoglobin A1c and triglycerides among COCP users compared to NHC users, while bioavailable testosterone decreased in COCP users only. This study demonstrates high retention and feasibility among women with overweight/obesity undergoing intensive dietary and metabolic monitoring. Although weight outcomes were similar between groups, these preliminary findings identify potential metabolic signals warranting confirmation in adequately powered studies. Full article