Search Results (459)

A warm-up is a critical procedure in sports science for enhancing muscular performance and optimizing subsequent athletic activities. However, the physiological and athletic performance effects of a warm-up are often transient, diminishing rapidly during the period of inactivity after the warm-up, which is known as the warm-up transition phase. In this study, a multi-functional thermoregulation wearable composite film of graphene–MXene–bacterial cellulose/polyethylene glycol (G-M-BC/PEG) was developed by integrating MXene (a two-dimensional material with good photothermal conversion performance) and graphene into a bacterial cellulose aerogel framework, subsequently impregnated with polyethylene glycol (PEG-2000). The film showed stable structure, efficient solar photothermal conversion and storage (SPCS), and improved mechanical properties. Under 1 sun irradiation, the optimized G-M-BC/PEG wearable film showed excellent SPCS performance, sustaining a temperature plateau of 38–40 °C for 10 min after the xenon lamp was switched off under 1 sun irradiation, with a leakage rate of only 5.32% after five cycles. By constructing a biomimetic sports human body model, the composite aerogel was shown to significantly elevate muscle surface temperature and effectively mitigate heat loss during the transition phase. In the warm-up effectiveness and sports performance tests, the wearable film improved 200 m sprint performance by 0.8% ± 0.4% (p = 0.039). It also maintained subjective thermal sensation during the warm-up transition phase, with no significant decline at 5 or 10 min after the warm-up and a significant decrease only at 15 min (p = 0.02), while thermal comfort remained stable, suggesting improved neuromuscular readiness. This research provided a novel strategy for the fabrication of advanced aerogel-based wearable devices aimed at precision thermal management and athletic performance optimization. Full article

Geometrical dot gain represents a fundamental physical phenomenon influencing tonal reproduction in halftone printing, particularly in offset and flexographic processes. However, a formally defined analytical framework capable of determining the tonal conditions of equal geometrical dot gain, particularly for hybrid screening design and tonal consistency optimization, has not yet been clearly established. In this study, a geometrical analytical model is formulated to determine the transition points of equal geometrical dot gain between AM and FM screening. Two analytical approaches were applied. The first compares the total contour length of halftone elements in both screening technologies, while the second relates the AM dot diameter to predefined FM microdot sizes. Calculations were performed for eight AM screen rulings (120–340 lpi) and six FM microdot diameters (20–50 μm) under predefined geometrical conditions (2540 dpi output resolution and circular dot shape). The results indicate that transition points predominantly occur within the highlight tonal region and systematically shift toward higher tonal percentages with increasing screen ruling. Both analytical procedures, although conceptually different, yield identical results, confirming the internal consistency of the model. The analytically determined transition points provide a geometrically justified basis for defining switching zones in hybrid and XM screening systems, enabling improved tonal stability and more consistent screening transitions. Full article

This study evaluates the effectiveness of laser cleaning techniques for the non-contact removal of unwanted deposits from the surface of contemporary urban mural paintings. Two sets of mock-up samples, painted with popular graffiti spray paints on lime-based plaster, and artificially contaminated, were subjected to various cleaning procedures using Nd:YAG lasers operated in Q-switched (QS), long Q-switched (LQS) or short free-running mode (SFR). A multi-analytical approach—including X-ray fluorescence spectroscopy (XRF), Fourier-transform infrared spectroscopy (FTIR), colorimetry, and hyperspectral imaging (HSI)—was used to identify pigments and binders, and to evaluate cleaning efficiency and pigment preservation. XRF and FTIR were useful in understanding the composition of the sprays, while colorimetric ΔE values quantified cleaning efficiency and potential damage, and hyperspectral reflectance and LSU (linear spectral unmixing) abundance maps provided spatial distribution insights into contaminant removal and pigment preservation. The results demonstrate that laser cleaning effectiveness and selectivity are strongly dependent on the operational regime and fluence. In particular, long Q-switched laser irradiation at moderate fluence levels achieved effective contaminant removal with minimal chromatic and chemical alteration of the original paint layers. These findings support the development of tailored, sustainable, and non-contact laser cleaning protocols for the conservation of contemporary urban murals and contribute to the establishment of objective, multi-parameter criteria for evaluating cleaning outcomes in street art conservation. Full article

This article describes a non-isolated boost DC–DC configuration that uses a two-winding coupled inductor (CI) together with two synchronous power switches to acquire ultra-high voltage conversion at relatively low duty cycles. The proposed structure combines a quadratic gain stage with the coupled inductor to realize a substantial output voltage boost. The overall conversion ratio can be flexibly adjusted through two independent design factors: the duty cycle of the switches and the turns ratio of the coupled inductor providing additional degrees of freedom for optimization. The main merits of the converter are its very high voltage gain (VG), reduced voltage stress (VS) on the active switches, continuous input current, common ground between input and output, soft-switching operation for diodes D₃ and D₄, and the possibility of using a synchronized gate-drive scheme. The paper thoroughly examines the operating intervals, steady-state behavior, design procedure, and efficiency performance, and also develops a dynamic model for control-oriented analysis. To highlight its strengths, the proposed topology is systematically compared with several existing high-gain converters. Finally, experimental outcomes obtained from a 400-W laboratory prototype operating at 50 kHz confirm the feasibility and effectiveness of the proposed converter in achieving high voltage gain, reduced device voltage stress, and high efficiency under practical operating conditions. Full article

In-stent restenosis (ISR) remains a clinically relevant cause of recurrent ischemia and repeat revascularization despite progressive refinements in stent design and implantation technique. Contemporary data indicate that restenosis-related target lesion revascularization (TLR) has declined from bare-metal stent (BMS) to early- and newer-generation drug-eluting stents (DESs), yet ISR continues to accumulate over long-term follow-up and is associated with worse outcomes than PCI for de novo lesions. Mechanistically, ISR is a time-dependent, heterogeneous process dominated early by neointimal hyperplasia—triggered by mechanical endothelial injury, delayed re-endothelialization, inflammation/oxidative stress, vascular smooth muscle cell phenotypic switching, and extracellular matrix deposition—and later by in-stent neoatherosclerosis, which may confer a higher-risk plaque substrate and overlap with thrombotic complications. Clinically, ISR frequently presents as an acute coronary syndrome (ACS) rather than stable symptoms, underscoring the prognostic relevance of prompt recognition and mechanism-informed management. Patient-level risk determinants repeatedly reported across cohorts include diabetes mellitus, chronic kidney disease, dyslipidemia, hypertension, and smoking, while lesion/procedural factors include small vessel caliber, long/complex or bifurcation lesions, multiple stent layers, and suboptimal stent expansion. Intravascular imaging (OCT/IVUS) is central to phenotyping ISR mechanisms (e.g., underexpansion, calcific neoatherosclerosis, stent fracture, homogeneous hyperplasia) and can guide targeted prevention and therapy. This review synthesizes current evidence on ISR biology and risk factors to support risk stratification, preventive strategies, and individualized management. Full article

The perioperative management of biologic and immunomodulatory therapies in patients undergoing orthopedic surgery poses a clinical challenge, primarily due to the increased risk of postoperative infections. Biologic agents, particularly TNF inhibitors and interleukin-targeting drugs, may impair host immune responses, potentially increasing the risk of surgical site infections (SSIs), delayed wound healing, and systemic infections. However, abrupt discontinuation of these therapies can lead to disease flare-ups, which themselves may complicate recovery and rehabilitation. In addition, discontinuation of biologics can lead to drug tolerance and unresponsiveness when they are restarted and thereby need switching to another biologic. Recent studies suggest that the infection risk is particularly elevated with ongoing biologic therapy during major surgeries, especially in procedures involving prosthetic implants. Guidelines generally recommend withholding biological disease-modifying antirheumatic drugs (bDMARDs) for at least one dosing cycle prior to surgery, when feasible, while maintaining non-biologic DMARDs in most cases. The decision must be individualized, taking into account the pharmacokinetics of each drug, the type of surgery, the patient’s comorbidities, and the activity of the underlying disease. Close coordination among rheumatologists, orthopedic surgeons, and infectious disease specialists is essential to minimize perioperative complications and optimize patient outcomes. Full article

The control of 400 Hz Ground Power Units (GPUs) in the range of several hundreds of kW poses distinct challenges, as the switching frequency ($f_{sw}$) must be constrained to limit switching losses. This constraint typically results in low ratios of the switching and LC filter natural frequencies ($f_n$) relative to the fundamental frequency. Notably, without mitigation, such systems often face stability issues or non-minimum phase behavior when $f_n<f_s/3$ (where $f_s$ is the sampling frequency). To address these challenges, this paper introduces a single-loop voltage control strategy for a 400 Hz voltage-source inverter (VSI) featuring a robust voltage decoupling scheme. Crucially, this decoupling allows the system to maintain minimum phase characteristics and operate with positive gains even when $f_n<f_s/3$, effectively solving the stability problems inherent to this operating region. The proposed architecture employs a proportional-resonant (PR) controller, with parameters systematically tuned to achieve maximum system damping based on stability regions dependent on the ratio between the sampling and natural frequencies. Validated through simulation and experimental procedures, the proposed method demonstrates precise voltage tracking and a robust dynamic response, proving its suitability for high-power, high-fundamental-frequency applications. Full article

Workers with upper-limb disabilities face difficulties in performing manufacturing tasks requiring fine manipulation, stable handling, and multistep procedural understanding. To address these limitations, this paper presents an integrated collaborative workcell designed to support disability-inclusive manufacturing. The system comprises four core modules: a JSON-based collaboration database that structures manufacturing processes into robot–human cooperative units; a projection-based augmented reality (AR) interface that provides spatially aligned task guidance and virtual interaction elements; a multimodal interaction channel combining gesture tracking with speech and language-based communication; and a personalization mechanism that enables users to adjust robot behaviors—such as delivery poses and user-driven task role switching—which are then stored for future operations. The system is implemented using ROS-style modular nodes with an external WPF-based projection module and evaluated through scenario-based experiments involving workers with upper-limb impairments. The experimental scenarios illustrate that the proposed workcell is capable of supporting step transitions, part handover, contextual feedback, and user-preference adaptation within a unified system framework, suggesting its feasibility as an integrated foundation for disability-inclusive human–robot collaboration in manufacturing environments. Full article

Aerospace power systems, including satellites in low earth orbit (LEO) and geostationary earth orbit (GEO), face stringent thermal constraints to minimize size, weight, and power (SWaP). Gallium nitride (GaN) devices offer superior radiation hardness—critical for the harsh space environment—and MHz-level switching capabilities. This high-frequency operation minimizes passive components, particularly magnetics, thereby reducing the overall volume. However, above 10 MHz, magnetic cores become impractical due to material limitations. To address these issues, this article proposes a design methodology for a GaN-based quasi-square-wave (QSW) buck converter integrated with a PCB air-core inductor. First, the impact of the switching frequency and dead time on the zero-voltage switching (ZVS) condition is elaborated. Then, a power loss model accounting for various loss mechanisms is presented. To overcome high GaN body diode reverse conduction loss, an auxiliary diode is employed. Based on the model, a design procedure is developed to optimize the inductor for 10 MHz operation while maximizing efficiency. To validate the design, a 28 V/12 V, 18 W prototype was built and tested. Experimental results demonstrate a peak efficiency of 86.5% at 10 MHz. The auxiliary diode improves efficiency by 4%, verifying reverse conduction loss mitigation. Thermal analysis confirms a full-load case temperature of 62.2 °C, providing a 47.8 °C safety margin compliant with aerospace derating standards. These findings validate the solution for high-frequency, space-constrained aerospace applications. Full article

This paper examines the contrasting yet complementary approaches of the Constrained Disorder Principle (CDP) and Stefan Hell’s deterministic optical nanoscopy for managing noise in complex systems. The CDP suggests that controlled disorder within dynamic boundaries is crucial for optimal system function, particularly in biological contexts, where variability acts as an adaptive mechanism rather than being merely a measurement error. In contrast, Hell’s recent breakthrough in nanoscopy demonstrates that engineered diffraction minima can achieve sub-nanometer resolution without relying on stochastic (random) molecular switching, thereby replacing randomness with deterministic measurement precision. Philosophically, these two approaches are distinct: the CDP views noise as functionally necessary, while Hell’s method seeks to overcome noise limitations. However, both frameworks address complementary aspects of information extraction. The primary goal of microscopy is to provide information about structures, thereby facilitating a better understanding of their functionality. Noise is inherent to biological structures and functions and is part of the information in complex systems. This manuscript achieves integration through three specific contributions: (1) a mathematical framework combining CDP variability bounds with Hell’s precision measurements, validated through Monte Carlo simulations showing 15–30% precision improvements; (2) computational demonstrations with N = 10,000 trials quantifying performance under varying biological noise regimes; and (3) practical protocols for experimental implementation, including calibration procedures and real-time parameter optimization. The CDP provides a theoretical understanding of variability patterns at the system level, while Hell’s technique offers precision tools at the molecular level for validation. Integrating these approaches enables multi-scale analysis, allowing for deterministic measurements to accurately quantify the functional variability that the CDP theory predicts is vital for system health. This synthesis opens up new possibilities for adaptive imaging systems that maintain biologically meaningful noise while achieving unprecedented measurement precision. Specific applications include cancer diagnostics through chromosomal organization variability, neurodegenerative disease monitoring via protein aggregation disorder patterns, and drug screening by assessing cellular response heterogeneity. The framework comprises machine learning integration pathways for automated recognition of variability patterns and adaptive acquisition strategies. Full article

Nonlinear single-input single-output (SISO) systems operating under parametric uncertainty often exhibit bifurcations, multistability, and deterministic chaos, which significantly limit the effectiveness of classical linear, adaptive, and switching control methods. This paper proposes a novel synthesis framework for self-organizing control systems based on catastrophe theory, specifically within the class of elliptic catastrophes. Unlike conventional approaches that stabilize a predefined system structure, the proposed method embeds the control law directly into a structurally stable catastrophe model, enabling autonomous bifurcation-driven transitions between stable equilibria. The synthesis procedure is formulated using a Lyapunov vector-function gradient–velocity method, which guarantees aperiodic robust stability under parametric uncertainty. The definiteness of the Lyapunov functions is established using Morse’s lemma, providing a rigorous stability foundation. To support practical implementation, a data-driven parameter tuning mechanism based on self-organizing maps (SOM) is integrated, allowing adaptive adjustment of controller coefficients while preserving Lyapunov stability conditions. Simulation results demonstrate suppression of chaotic regimes, smooth bifurcation-induced transitions between stable operating modes, and improved transient performance compared to benchmark adaptive control schemes. The proposed framework provides a structurally robust alternative for controlling nonlinear systems in uncertain and dynamically changing environments. Full article

High voltage (HV) test environments require dependable visual status indicators to maintain operator safety; however, directly supplying these indicators from HV sources introduces substantial electrical and operational hazards. This work addresses these challenges through the design and implementation of a compact Flyback DC–DC converter that provides galvanic isolation and a stable low-power output specifically intended for LED-based safety beacons. While utilizing Discontinuous Conduction Mode (DCM) and valley-switching to minimize thermal stress, the primary innovation of this design lies in the rigorous optimization of the isolation barrier and PCB architecture to meet HV safety standards (such as IEC 60950-1) within a minimal physical footprint. Transformer parameters were determined using analytical design procedures and subsequently verified by circuit-level simulations, which confirmed correct DCM operation as well as rapid startup behavior without output overshoot. A two-layer PCB was designed in accordance with IPC-2221B standard, with particular emphasis on minimizing parasitic effects and thereby improving overall performance. Experimental characterization demonstrated stable output regulation and a strong correlation between measured and simulated waveforms. The proposed system enhances safety in HV laboratory settings while achieving a compact form factor and supporting a wide input voltage range. Full article

In both research and industrial settings, it is often necessary to expand the input/output channels of measurement instruments using relay-based multiplexer boards. In research activities in particular, the need for a highly flexible and easily configurable solution frequently leads to the development of customized systems. To address this challenge, we developed a system optimized for automated direct current (DC) measurements. The result is based on a $4\times 4$ switching platform that simplifies measurement procedures that require instrument routing. The platform is based on a custom-designed circuit board controlled by a microcontroller. We selected bistable relays to guarantee contact stability after switching. We finally developed a system architecture that allows for straightforward expansion and scalability by connecting multiple platforms. We share both the hardware design source files and the firmware source code on GitHub with the open-source community. This work presents the design and development of the proposed system, followed by the performance evaluation. Finally, we present a test of our designed system applied to a specific case study: the DC analysis of complex resistive networks through multi-point resistance measurements using only a single voltmeter and current source. Full article

To address the challenges of system failures and equipment damage caused by excitation inrush currents and overvoltages during no-load energization of high-speed locomotive transformers, a simulation model was developed utilizing PSCAD electromagnetic transient simulation software. This study establishes a no-load switching simulation model for rolling stock transformers within PSCAD, analyzing variations in overvoltage and excitation inrush current amplitudes across different phase angles. Additionally, it compares excitation inrush current amplitudes under varying residual magnetism conditions. A phase-selective control strategy is proposed, integrating the hysteresis characteristics of the transformer core. The model’s accuracy is validated against empirical data obtained from a city train. Employing the Jiles–Atherton hysteresis model, the residual magnetism of the transformer core is quantified. Based on measured data, a relationship curve between switching phase and residual magnetism is fitted, enabling calculation of the optimal closing angle through the phase selection procedure. This approach effectively mitigates overvoltage and excitation inrush current hazards, thereby enhancing the operational safety of the train system. Full article

(1) Background: The systemic right ventricular (SRV) dysfunction and severe tricuspid regurgitation (TR) remain significant challenges in patients with congenitally corrected transposition of the great arteries (ccTGA) or following atrial switch procedures. Currently, there is no established, evidence-based medical therapy specifically designed for SRV failure, and treatment approaches are largely extrapolated from left ventricular heart failure (HF) guidelines. This therapeutic gap highlights the need for tailored pharmacologic strategies and optimized perioperative management in this unique population. The optimal timing of surgical intervention and the role of modern HF therapy are still under active investigation. (2) Methods: We present a case series of four patients (three adults and one child) with SRV dysfunction and severe TR, who underwent staged treatment consisting of optimized medical therapy followed by surgical tricuspid valve (TV) replacement. Medical therapy included positive inotropes, sacubitril/valsartan, sodium-glucose co-transporter 2 inhibitors (iSGLT2), beta-blockers, mineralocorticoid receptor antagonists (MRAs), and loop diuretics. (3) Results: All patients demonstrated clinical and hemodynamic improvement prior to surgery, with an increase in systemic ventricular ejection fraction (SVEF > 40%) and cardiac index. TV replacement was performed with favorable early postoperative outcomes and preserved ventricular function at mid-term follow-up. No mortality or major adverse events occurred during follow-up. One case of acute cystitis was associated with dapagliflozin. In all patients, postoperative SVEF remained >40%, and no recurrence of significant TR was observed. (4) Conclusions: A stepwise approach combining modern heart failure therapy and elective TV replacement in patients with SRV dysfunction and TR is safe and effective. Preoperative optimization leads to improved ventricular function and may enhance surgical outcomes. These findings support the integration of contemporary pharmacotherapy in the management strategy for SRV failure. Full article