Search Results (4,089)

The increasing integration of wind energy into modern power systems introduces significant challenges in maintaining frequency stability and power quality due to the stochastic nature of wind speed, particularly in microgrid environments. This study focuses on the modeling and control of a wind energy conversion system based on a Doubly Fed Induction Generator (DFIG) operating in conjunction with an external power supply system. A comprehensive simulation model of the wind energy system was developed in MATLAB (R2023b), incorporating both the wind turbine and power converter subsystems. The control strategy is based on stator flux-oriented vector control, which enables independent regulation of active and reactive power, combined with space vector pulse-width modulation (SVPWM) to improve the performance of the power electronic converters. The system employs a dual-converter structure, where the rotor-side converter ensures bidirectional power flow and the grid-side converter maintains the DC-link voltage. The simulation results demonstrate that the proposed control system ensures fast dynamic response and stable operation under variable wind conditions. In particular, the stator current reaches a steady state within 0.01 s, satisfying the specified technical requirement for transient performance. Additionally, the DC-link voltage is effectively stabilized at approximately 700 V, ensuring reliable operation of the converter system. The use of SVPWM contributes to improved switching performance and efficient synthesis of voltage vectors, enhancing overall system stability. The developed model also confirms the stable operation of the wind energy system within a microgrid, ensuring coordinated interaction between system components under fluctuating wind conditions. Compared to conventional approaches, the applied vector control strategy provides effective decoupling of power components and improved dynamic characteristics for the system. The results obtained validate the effectiveness of the proposed modeling and control approach for small-scale wind energy systems and demonstrate its applicability for improving the stability and performance of renewable energy integration in modern power systems. Full article

Carbon-based materials exhibit diverse structural responses to irradiation owing to their distinct dimensionality, degree of graphitization, surface chemistry, and pore architecture. Although irradiation has traditionally been regarded as a source of structural damage, increasing evidence demonstrates that controlled irradiation can be deliberately utilized to tailor defects, surfaces, interfaces, and pore structures, thereby enabling desirable functional properties. This review summarizes recent progress in the irradiation-induced structural evolution and functional applications of four representative carbon-based materials, including graphene-based materials, carbon nanotubes, carbon fibers, and activated carbon/biochar. Particular attention is given to the characteristic irradiation responses of different carbon architectures. In graphene, irradiation predominantly induces vacancies, reconstructed defects, and surface functionalization, providing active sites for environmental remediation. Carbon nanotubes additionally undergo inter-tube cross-linking and welding, enabling enhanced mechanical performance and tunable electronic properties. For carbon fibers, irradiation mainly regulates surface chemistry and fiber matrix interactions, facilitating interface engineering in high-performance composites. In activated carbon and biochar, irradiation modifies pore accessibility, structural disorder, and surface functional groups, thereby influencing adsorption and electrochemical performance. These distinct responses demonstrate that irradiation can evolve from a conventional damage process into a controllable materials-engineering strategy when appropriate irradiation conditions are employed. Finally, current challenges associated with optimal irradiation conditions, quantitative defect identification, and irradiation structure–property relationships are discussed. Based on these distinct responses, we propose an architecture-dependent irradiation–structure–function (A-ISF) framework that links the initial carbon architecture and irradiation conditions to dominant energy-deposition mechanisms, structural evolution pathways, property modulation, and ultimately functional applications. Within this framework, irradiation engineering is interpreted as a competition between beneficial structural modification and excessive radiation damage, giving rise to an application-dependent optimal irradiation window. Full article

Background/Objectives: Alginate hydrogels are widely used in tissue engineering; however, their reported properties vary significantly due to differences in formulations and processing conditions, which limits direct comparison across studies. This study aims to systematically evaluate the relative and combined effects of alginate viscosity grade, polymer concentration, and CaCl₂ crosslinking concentration on hydrogel structural, mechanical, and biological behaviour. Methods: Hydrogels were prepared using three commercially available alginates of low, medium, and high viscosity. Polymer concentration (0.5–2% w/v) and CaCl₂ concentration (2.5–10% w/v) were systematically varied under controlled fabrication conditions. Morphology was analysed using scanning electron microscopy, swelling and water uptake were quantified, mechanical properties were assessed via dynamic mechanical analysis, and cell viability was evaluated using Chinese hamster ovary (CHO) cells encapsulation over 20 days. Statistical analysis was performed using two-way ANOVA. Results: Hydrogel properties were governed by non-linear interactions between formulation parameters. CaCl₂ concentration was identified as the dominant factor influencing structural and biological outcomes, with increasing crosslinking concentration reducing pore size, swelling, and water uptake, and decreasing cell viability by up to ~60%. In contrast, polymer concentration and alginate viscosity grade primarily controlled mechanical behaviour, with increased polymer content and viscosity resulting in higher storage and Young’s moduli. Significant interaction effects confirmed that hydrogel properties are not independently tunable but depend on the combined influence of all parameters. Conclusions: Crosslinking concentration dominates structural and biological responses in alginate hydrogels, while polymer parameters modulate mechanical properties within this constraint. These findings establish a formulation-dependent trade-off between mechanical stiffness and cytocompatibility, providing a comparative framework for rational selection of alginate systems based on application-specific requirements. Full article

Given the pressing need for efficient CO₂ valorization, the precise modulation of metal–support interfaces via strong metal-support interaction (SMSI) have emerged as a pivotal strategy for tuning catalytic activity in CO₂ hydrogenation. However, despite the proliferation of relevant studies, a comprehensive and critical review that systematically evaluates the role of SMSI in this specific reaction remains absent. This work takes oxide-supported metal catalysts as the research object, focusing on the dynamic mechanism of SMSI-induced interface reconstruction and electron transfer. The relevant characterization progress and regulation strategies are systematically reviewed, and the synergistic regulation effect of the two on the reaction pathway is further explored. We analyze the impact of the above factors on the catalytic performance of CO₂ hydrogenation from three aspects: SMSI coverage layer formation, electronic structure optimization, and key intermediate stabilization. At the same time, key descriptors currently used to describe SMSI interface reconstruction and electronic transmission processes are summarized. On this basis, the main challenges faced in existing research are identified, and future directions are discussed, emphasizing the need for breakthroughs in the key issues mentioned above in order to provide a more guiding theoretical basis for the structural design of efficient CO₂ hydrogenation catalysts. Full article

Reliable photovoltaic (PV) monitoring requires meteorological inputs that remain interpretable through horizontal irradiance, module-plane irradiance, temperature, and electrical-output layers. This study evaluates a component-wise WRF–machine-learning–POA–thermal workflow using complementary field datasets: a synchronized 2021 WRF-ML/electrical dataset and an independent 2017 POA/GTI validation dataset. WRF-derived variables were treated as retrospective meteorological inputs for post-processing and forecasting-input assessment. Random Forest, Gradient Boosting, neural networks, mean bias-corrected WRF, and Ridge MOS baselines were tested for GHI correction; empirical, Perez, Hay–Davies, and isotropic models were compared for POA/GTI transposition; and five module temperature models were assessed. In a random 80/20 held-out test, Random Forest and Gradient Boosting reduced irradiance RMSE from 139.66 W/m² for raw WRF to 75.92 and 75.96 W/m², respectively. In blocked temporal validation, however, raw WRF was more stable for month-wise irradiance, and the physics-inspired Ridge baseline was more robust for leave-one-month-out AC/DC power prediction. Perez gave the best POA/GTI agreement, while NOCT and King/Sandia gave the lowest thermal errors. The results support a protocol-dependent, traceable input-chain assessment for PV monitoring and identify the calibration, metadata, and timestamp controls needed before operational power-forecasting claims can be generalized. Full article

BOOLE is a four-face educational platform integrating analog, combinational-logic, and sequential-logic activities with optional AI-assisted component identification and datasheet support. The system was developed through requirements translation, circuit simulation, two-layer PCB design, mechanical review, fabrication, assembly, functional verification, and iterative refinement. A Raspberry Pi 5, Camera Module 3 NoIR, and touchscreen support image capture and local interaction, while an Arduino Mega provides deterministic control of the physical learning faces. Segmented power energizes only the selected face and activity, and removable boards improve maintenance and fault isolation. Hardware demonstrations reproduced the intended voltage-divider, diode threshold/polarity, counter, and sequential-logic states. Ten one-versus-rest classifiers were fine-tuned from a pretrained ViT-Base model using 2000 original photographs, with 200 images for each of ten categories. The dataset was partitioned class-wise into mutually exclusive 80/10/10 training, validation, and final-test sets before augmentation, which was applied only to training data. Final-test accuracy ranged from 91.0% to 99.5%, with precision, recall, F1-score, specificity, balanced accuracy, and confusion matrices also evaluated. A 73-student pilot produced 89–96% positive (Yes) responses across six binary survey items, providing preliminary evidence of learner-perceived effectiveness, engagement, usability, and theory-to-practice support. Overall, BOOLE demonstrates a feasible, serviceable architecture for progressive electronics education. Full article

This study investigates the responses in the resistance of polypyrrole (PPy) and titanium dioxide (TiO₂) single layers and PPy/TiO₂ heterostructures to rectangular pulses of monochromatic LED illumination under controlled relative humidity. Exposure to moisture increases the resistance of PPy while rapidly decreases that of TiO₂, reflecting opposite effects of electron donation from hydroxyl (–OH) groups in adsorbed H₂O on the majority carrier densities of the two materials. Under monochromatic illumination, the resistance of PPy decreases, whereas that of TiO₂ increases accompanied by a brief transient at excitation wavelengths near its optical edge (367 nm and 398 nm). This photoresponse is attributed to photoinduced modifications of carrier density through two opposing processes: photogeneration, which enhances charge carriers, and H₂O photodesorption, which reduces them. A combination of illumination and moisture exposure results in an intensified photoresponse of PPy, thereby enhancing its humidity response. The PPy/TiO₂ heterostructure demonstrates a mixed photoresponse arising from contrasting behaviors of its p-type PPy and n-type TiO₂ components, coupled with charge exchange across the p–n junction. When simultaneously exposed to moisture and monochromatic light, the heterostructure undergoes contrasting photoinduced carrier generation in its two components, which in turn modulates the depletion region in inverse phase with carrier density, thereby intensifying the overall photoresponse. This complementary “push–pull” interaction synergistically enhances both the photoresponse and the humidity response of the PPy/TiO₂ heterostructure. Full article

Copper is a redox-active transition metal that is essential for the assembly and catalytic function of cytochrome c oxidase (Complex IV), the terminal enzyme of the mitochondrial electron transport chain and a principal site of physiological oxygen reduction. Elevated Complex IV activity and respiratory chain uncoupling are among the most consistently replicated biological findings in autism spectrum disorder (ASD), yet the interaction between mitochondrial copper delivery, respiration, and cellular oxidant handling in ASD has not been systematically defined. We treated dermal fibroblasts from 9 children with ASD and 10 typically developing controls with the copper(I)–niacin complex Cunermuspir (0, 50, or 100 µM for 1 or 24 h exposure) and challenged them with graded concentrations (0–5.0 µM) of the redox-cycling agent 2,3-dimethoxy-1,4-naphthoquinone (DMNQ). Mitochondrial respiration was profiled by Seahorse XF respirometry (2133 observations across 28 experiments), and cellular reactive oxygen species (CellROX™ Green) and mitochondrial mass/polarization (MitoTracker™ Deep Red) were quantified by fluorescence imaging. ASD fibroblasts displayed a hypermetabolic, uncoupled respiratory phenotype (~73% higher baseline respiration; ~109% higher proton leak; reduced coupling efficiency). Linear mixed models with polynomial dose terms revealed significant ASD × Cunermuspir complex interactions (ASD × Cunermuspir and/or their higher-order interactions with DMNQ and treatment) for four respiratory parameters. ASD cells exhibited lower steady-state oxidation-dependent CellROX™ Green fluorescence than controls despite greater respiratory uncoupling, as well as lower steady-state MitoTracker™ Deep Red fluorescence; Cunermuspir reshaped the MitoTracker™ DMNQ dose–response in an ASD-selective manner. These findings identify the Cunermuspir-associated modulation of the ASD mitochondrial and oxidant handling phenotype and motivate further mechanistic and translational evaluation. Full article

Perovskite solar cells (PSCs) have emerged as a research hotspot in photovoltaics owing to their high power conversion efficiency (PCE), low fabrication cost, and simple preparation processes. However, their commercialization remains constrained by interfacial defects, non-radiative recombination, and limited scalability. Self-assembled molecules (SAMs), as a critical interfacial engineering tool, can significantly enhance device performance through defect passivation, energy band alignment, and crystallization regulation. Following the main theme of “molecular design—mechanistic understanding—application expansion,” this review systematically summarizes the structure–property relationships between SAMs architecture (anchoring groups, connecting backbones, and terminal functional groups) and their interfacial regulation mechanisms, with a particular focus on the important role of SAMs uniformity in governing interfacial quality, charge carrier transport, and device stability. The article presents multi-scale characterization techniques for evaluating SAMs interfacial properties, reviews the application progress of SAMs in rigid devices, flexible devices, and large-area modules, and finally discusses their future expansion directions in emerging fields such as tandem solar cells, flexible electronics. Full article

Background: Obesity is a multifaceted metabolic disorder characterized by systemic disturbances, particularly impaired energy homeostasis, chronic low-grade inflammation, and mitochondrial dysfunction across the brain, gut, adipose tissue, and liver axes. Objectives: This review aims to examine the metabolic properties and molecular mechanisms of six key phytochemicals (berberine, resveratrol, catechins, capsaicin, thymoquinone, and phycocyanin) and the exercise-induced myokine irisin, and their roles in mitochondrial signaling and metabolic reprogramming. Sources of Evidence: A comprehensive literature search was conducted across major electronic databases, including PubMed, Web of Science, and Scopus, to identify relevant mechanistic, in vivo, and in vitro studies. Results: Both the selected phytochemicals and irisin act as multi-target regulators that modulate key signaling pathways, including AMPK, PI3K/Akt/mTOR, SIRT1, Nrf2, and PPARγ. These phytochemicals and irisin can drive cell- and tissue-specific metabolic reprogramming, promoting the browning of white adipocytes, suppressing de novo lipogenesis in hepatocytes, and enhancing fatty acid oxidation in skeletal myocytes. This synergistic metabolic reprogramming enhances thermogenesis and increases energy expenditure. Conclusions: Co-targeting redox signaling and metabolic pathways via phytochemicals and irisin offers a powerful strategy against obesity. This integrative framework restores multi-organ homeostasis, laying the groundwork for targeted metabolic therapies. Full article

Wearable electronics, particularly dry epidermal electrodes, provide human-connected interfaces for recording biopotential signals. However, their practical utility is often hindered by their limited operational longevity and the resulting environmental burden of electronic waste, as most conventional electrodes are discarded after a single use because of performance degradation. Herein, a reusable, soft, and conductive epidermal electrode is reported, fabricated through the precise incorporation of functional additives. By intentionally modulating the polymer chain architecture, a homogeneous composite is developed that exhibits exceptional flexibility, high conductivity (~100 S/cm), softness (~649 kPa), and stretchability (~234%). This molecular-level design promotes strong intermolecular interactions at the skin–electrode interface, facilitating persistent adhesion and conformability to challenging surfaces, including wet, wrinkled, and stretched skin. These properties enable reliable electrocardiography acquisition through 50 repeated attachment and detachment cycles, over which a commercial Ag/AgCl gel electrode became unmeasurable after 20. The applicability of the electrode to human–machine interfaces is further demonstrated by capturing clear electromyography signals of muscle activity during a rock–paper–scissors game. This low-modulus electrode platform offers a route towards repeated-use wearable healthcare systems and soft-robotics applications, with the potential to reduce the waste associated with single-use electrodes. Full article

The detrimental effect of cigarette smoking has become undeniable, based on decades of research. Twenty years ago, the electronic cigarette was introduced to the market and has since then been presented as the alleged healthy alternative. Clever marketing by the industry has led to a global rise in the number of users, especially adolescents and young adults. Clinicians and scholars have praised the electronic cigarette as a tool for tobacco smoke cessation, hoping for a reduction in burden on healthcare systems. Yet accumulating evidence suggests otherwise. Over the years, several in vitro and in vivo studies in animal models and humans have shown electronic cigarettes to be associated with pulmonary, cancerous and cardiovascular diseases. This review revisits the so-far available clinical evidence concerning cardiovascular diseases and discusses research gaps that still need to be addressed, specifically focusing on patients undergoing cardiac surgery. Full article

The dual active bridge (DAB) converter is one of the most common types of isolated bidirectional power converters in modern spacecraft EPS owing to its galvanic isolation, bidirectionality, soft switching, and good controllability. However, the goal of power transfer maximization often clashes with real-world spacecraft EPS constraints, namely thermal compliance, reliability, and the accuracy of simplified models used for analysis. This paper proposes a physics-informed methodology to derive the practical operating range under single phase shift (SPS) control based on a rigorous piecewise time-domain representation. From this model, the steady-state initial condition, general closed-form RMS current expression, ZVS boundary condition, and ZVS-aware loss model linked to the junction-temperature estimate are derived. The validity domain of the fundamental harmonic approximation (FHA) is evaluated against the exact model across the full (φ, k) space, and a two-dimensional operating map superposing power contours, the ZVS limit, and the thermal limit is presented. For the baseline case study at k = 1.0, the thermal constraint limits the nominal feasible upper phase shift to approximately 35°, while the broader 15–45° range remains useful for design assessment and operation toward 45° requires lower effective resistance and/or improved thermal management. The normalized SPS power-transfer curve retains the same shape under variations in L and f_s, but RMS current, losses, and thermal feasibility must be reassessed for each converter design. The resulting closed-form framework provides a steady-state feasibility-evaluation tool for spacecraft EPS design and offers a computational basis for future supervisory constraint evaluation under varying voltage, load, and thermal conditions. Full article

The accelerating contamination of global ecosystems by heavy metal ions, per- and polyfluoroalkyl substances (PFASs), microplastics and nanoplastics (MNPs), and emerging contaminants demands sensing technologies that are rapid, sensitive, selective, and field-deployable. Quantum dots (QDs) have emerged as leading candidates for environmental sensing; however, their performance is often interpreted empirically rather than through a unified understanding of the underlying excitonic physics. This narrative review presents a mechanistically integrated framework for QD-based environmental sensing, establishing the exciton, the spatially confined electron–hole quasiparticle, as the primary signal carrier in the most analytically powerful QD sensing modalities. A critical distinction is drawn between three categories of signal-generating processes: genuine excitonic transduction (photoinduced electron transfer, trap-state modulation, FRET, charge-transfer exciton formation, and binding energy modulation); non-excitonic optical phenomena, including the inner filter effect and light scattering, which are frequently misattributed as excitonic responses; and partially excitonic processes such as certain electrochemiluminescence pathways. Exciton fundamentals, confinement effects, and the influence of defects, dopants, and surface states are examined across carbon, chalcogenide, perovskite, and III–V QD families. A Defect–Exciton Energy Map is introduced as a rational design tool linking defect characteristics to excitonic response regime and sensing modality. Application of the mechanistic framework to heavy metal ions, PFASs, microplastics, and emerging contaminants demonstrates that sensing performance differences are mechanistically predictable from excitonic parameters rather than being arbitrary outcomes of materials choice. Benchmarking against competing platforms identifies conditions under which QD sensors offer genuine advantages. The roles of density functional theory, molecular dynamics, and machine learning in enabling rational sensor design are assessed. Key challenges, including stability, real-sample validation, standardisation, and toxicity, and future directions, including QD/two-dimensional material heterostructures and circular economy carbon QD platforms, are identified. Full article

Mitigating structural failure and improving the fire safety of concrete infrastructure during severe thermal events depends critically on the high-temperature resilience of Portland cement paste. Given the increasing production of Portland blended cements, understanding their high-temperature behavior is crucial for ensuring the safety of building structures. This study investigates the effects of exposure to high temperatures (up to 1200 °C) on Portland cement pastes containing ground granulated blast furnace slag and quartz powder, focusing on their thermal stability and the chemical reactions occurring under these conditions. In situ X-ray diffraction (XRD) with a heating module was employed to observe real-time phase transformations as the temperature increased, supported by ex situ scanning electron microscopic analysis. The results showed changes in the mineralogical composition, with particular attention to the decomposition of calcium hydroxide and the formation of melilite above 900 °C. These transformations suggest thermal reactions between cement hydrate products (calcium silicates and aluminates) in the presence of slag and quartz powder. Mixtures containing quartz powder exhibited increased porosity and phase transformation shifts at lower temperatures, reflecting the combined effects of quartz addition, reduced reactive binder content, and an increased effective water-to-binder ratio. Notably, lower strength-grade cements containing fly ash (additional alumina source) show higher degrees of formation of calcium–aluminate silicate phases such as melilite upon heating. Compared to conventional studies, the novelty of this study lies in the use of an in situ experimental setup, which uniquely identifies the temperature thresholds of chemical changes and the formation of new phases such as melilite in cement–selected slag mixes, while also capturing their recrystallization upon cooling. Full article