Search Results (58)

This study investigates the repetitive overload turn-off behavior of a 1200 V/15 A trench field-stop IGBT using a clamped inductive load circuit. The DC-link voltage is set to 600, 800, and 1000 V, while the external circuit configuration and the 2 ms pulse interval remain unchanged. The displayed sequences at 600 and 800 V exhibit no destructive failure. Under the 1000 V condition, 24 of 30 devices fail, and the cycle-to-failure ranges from 6 to 27. Before failure, the peak V_CE, turn-off current, and E_off reach 1248.1 V, 80.2 A, and 12.87 mJ, respectively. During the final destructive event, V_CE first recovers to approximately 1.16 kV and then collapses toward zero, while I_C re-grows to approximately 106.8 A. A statically validated two-dimensional simulation model shows pulse-to-pulse temperature accumulation, mobility reduction, expansion of the high-field and impact-ionization regions, and persistence of an electron-rich transport path near the trench-gate active region. Post-failure SEM reveals a filament-like damage trace, emitter-side Al damage, damaged trench-gate structures, and contiguous multi-cell ablation. The combined evidence indicates that repetitive heating progressively strengthens the coupling among carrier transport, electric-field concentration, avalanche generation, current localization, and self-heating, which leads to delayed localized electrothermal instability. An auxiliary RC-IGBT comparison further confirms that the repetitive overload turn-off boundary depends on the device technology and operating conditions. Full article

To address the issues of low voltage levels and insufficient reliability in dynamic regulation and voltage stabilization in existing high-voltage power supplies for electron-curtain accelerators, this paper presents a 150 kV/30 kW DC high-voltage power supply specifically designed for electron-curtain accelerators. The main circuit employs an LC high-frequency resonant topology and a step-up transformer with eight secondary windings, utilizing a parallel step-up and series output architecture to increase the output voltage level. During the charging phase, a dual-closed-loop frequency conversion scheme combined with duty cycle feedforward is employed to accelerate charging speed, while the voltage stabilization phase utilizes hysteresis burst control to improve accuracy. Simulation results indicate that the system can charge to 155 kV in 102 ms, with a voltage ripple less than 0.1%, a linear regulation of 0.01%, and a load regulation of 0.5%. Tests on a low-voltage prototype confirmed that the power devices can achieve zero-current soft switching, with a resonant current peak of 40 A and overall efficiency reaching 96%. The accompanying filament power supply can stably output 24 V/20 A, and the closed-loop voltage regulation is stable and reliable, providing technical support for the engineering application of high-voltage power supplies in high-power electron beam accelerators. Full article

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen frequently associated with chronic and biofilm-related infections, largely driven by quorum sensing (QS)-related genes/phenotypes. In this study, we investigated the antivirulence activity of an engineered M13-derived phage-display particle (P9b), selected for specific binding to P. aeruginosa, which acts as a non-lytic modulator of QS through specific binding to a bacterial surface target. P9b induced a transient delay in early planktonic growth, without affecting long-term proliferation. In contrast, P9b significantly reduced biofilm-associated metabolic activity and pyocyanin production, consistent with an effect on QS-regulated pathways. Transcriptional analysis revealed significant downregulation of key QS regulators (lasI, lasR, rhlI, and rhlR) and modulation of phenazine biosynthesis genes (phzM downregulation and phzS upregulation), suggesting interference with QS-dependent regulatory circuits. Notably, P9b retained binding capacity and antibiofilm activity across clinically relevant P. aeruginosa isolates. Overall, these findings indicate that P9b acts as a selective, non-lytic modulator of virulence-associated traits, attenuating QS-regulated phenotypes without bactericidal effects. This study supports the potential of engineered filamentous phages as targeted antivirulence platforms for the development of innovative strategies against persistent and biofilm-associated infections. Full article

Electrical stimulation enhances functionality and accelerates maturation in biofabricated tissues, which are particularly important for muscle tissue engineering applications. Accordingly, there is demand for 3D-printable electrically conductive cytocompatible scaffolds that enable patient-specific geometries and localized electrical stimulation, as well as incorporate further maturation-promoting geometrical cues. Filament-based scaffolds from fused filament fabrication could overcome current limitations in geometric freedom, size and partially cytotoxic additives. In this study, biodegradable polylactic acid (PLA)-based conductive filaments incorporating graphene nanoplatelets (GNPs) or carbon nanofibers (CNFs) were developed via melt-mixing extrusion to possibly enable the electrical functionalization of muscle scaffolds. A two-stage process combining twin-screw and single-screw extrusion was preferred to allow for higher filler incorporation. Filament morphology, printability, electrical conductivity, and cytocompatibility were systematically evaluated. Homogeneous filaments containing up to 16 wt.% GNPs or 3.6 wt.% CNFs were successfully produced and processed by fused filament fabrication into scaffold geometries supporting myoblast orientation. Electrical conductivity was measured above 16 wt.% GNPs, with up to 2.7 µS/m, with printed constructs capable of connecting a circuit. GNP-based filaments were cytocompatible, supporting myoblast attachment and elongated morphology. An adjustable electrical stimulation setup demonstrated improved muscle maturation and contractile responses of C2C12 myoblasts, highlighting biodegradable conductive filaments’ potential for electrically active muscle tissue scaffolds. Full article

Elucidating the pathophysiological mechanisms of mental disorders remains a critical challenge in psychiatric research. Recent studies have highlighted the potential involvement of cytoskeletal and molecular motor abnormalities in the development of mental disorders such as schizophrenia and autism spectrum disorder (ASD). Although schizophrenia and ASD differ clinically, both disorders are increasingly regarded as neurodevelopmental conditions and share vulnerabilities in synapse formation and neural circuit maturation. This review synthesizes the latest findings on the relationship between cytoskeletal and molecular motor abnormalities and mental disorders. The cytoskeleton, composed of microtubules, actin filaments, and intermediate filaments, along with molecular motors such as kinesins, dyneins, and myosins, plays crucial roles in neurodevelopment, synapse formation, and neurotransmission. In schizophrenia, decreased expression of the microtubule-associated protein MAP2 and abnormalities in the DISC1 gene have been reported, potentially leading to dendritic morphological abnormalities and neurodevelopmental disorders. Additionally, abnormalities in molecular motors such as KIF17 and KIF1A have been implicated in schizophrenia pathophysiology. Myosin Id has been identified as a risk gene for ASD. Furthermore, abnormalities in actin-related proteins such as SHANK3 and CYFIP1 have been shown to cause synaptic dysfunction. These findings suggest that mental disorders arise from complex pathologies involving multiple cytoskeletal and molecular motor-related protein abnormalities. Future research should focus on elucidating the functions of individual proteins and adopting a comprehensive approach that includes glial cells. Advances in this field may deepen our understanding of the pathophysiological mechanisms of mental disorders and potentially lead to the development of novel therapeutic strategies. Full article

Conductive thread is an integral aspect of smart textiles in the domain of electronic textiles (e-textiles). This study unveils the development of twelve distinct variants of conductive threads using the twisting method: the fusion of copper filament with cotton and polyester threads. The threads are coated with a carbon paste solution enriched with dissolved sea salt. The carbon paste is obtained from non-functional dry cell batteries, conventionally categorized as hazardous electronic waste (e-waste), which underscores an economically viable and environmentally sustainable approach. Experiments proved that each variant demonstrates minimal electrical resistance. The lowest resistance, 0.0164 ± 0.0001 Ω/cm, was achieved by Carbon-Coated Cotton Twisted Copper Thread-II. Comparative evaluation with commercially available conductive threads, including Bekaert Bekinox^® VN type (12/1x275/100z), indicated comparable or moderately lower resistance values for the developed copper-based threads. Mechanical–electrical stability under bending, twisting, and wash–dry cycles confirmed consistent conductive performance with minimal resistance variation. Practical demonstrations further validated the integration of the threads into fabric-based flexible circuits and wearable electronic systems. These findings demonstrate that twisted copper-based conductive threads derived from sustainable coating materials provide a promising alternative for smart textile and wearable electronic applications. Future research should focus on scalable fabrication, enhanced coating fixation, and long-term durability assessment. Full article

Betatrons offer advantages such as a compact structure and the absence of complex radio-frequency systems which make them well suited for industrial non-destructive testing and high-energy X-ray imaging. However, with the increasing miniaturization of betatrons, the design of the electron injection unit faces new technical challenges, and conventional electron injection schemes are no longer suitable for small-size betatrons. In this study, an electron injection unit is designed based on the operating characteristics of small-size betatrons. The proposed unit consists of a half-bridge filament drive circuit, a pulsed high-voltage circuit, and an injection current feedback circuit. The experimental results demonstrate that the optimal dose rate is achieved when the injection current is adjusted within a range of 0–1.2 A, with a nominal injection current of 0.8 A, fully satisfying the operational requirements of small-size betatrons. Compared with traditional electron injection schemes, the proposed design features a more compact circuit structure and provides an efficient and accurate solution for electron injection in electron accelerator systems. Full article

Coupling microbial catalysis with electrochemical stimulation offers a promising strategy for heavy metal remediation. This study investigates how potentiostatic control influences the bioreduction of hexavalent chromium (Cr(VI)) by Bacillus cereus strain DIF1 in a bioelectrochemical system. Cr(VI) reduction was evaluated under various applied cathodic potentials, and the highest reduction efficiency (91.45%) was achieved at +0.04 V after 24 h. This performance significantly surpassed that of the abiotic control (82.55%) and the open-circuit biotic control (9.25%), indicating that the applied potential enhances microbial Cr(VI) reduction beyond contributions from abiotic processes alone. Cyclic voltammetry (CV) revealed a distinct redox feature at +0.04 V with no corresponding reverse peak, indicating kinetically favored electron transfer during Cr(VI) reduction under this condition. Microscopic imaging confirmed that, under the applied potential, Bacillus cereus DIF1 formed filamentous connections, exhibited higher chromium accumulation on bacterial cells than on the surrounding carbon paper electrode, and developed a robust biofilm on the cathode surface. The system maintained consistent Cr(VI) reduction performance over three consecutive cycles, demonstrating good short-term operational reproducibility. These findings highlight the critical role of precise electrochemical control in modulating microbial Cr(VI) reduction and provide mechanistic insights into the interplay between electrode potential and bacterial activity. Full article

This study investigates the tribo-corrosion behavior of Ti6Al4V biomedical alloy, when sliding against fused filament fabrication (FFF) 3D-printed polyether ether ketone (PEEK) pins in a phosphate-buffered saline (PBS) solution. This research aims to evaluate wear mechanisms and electrochemical responses under simulated physiological conditions, providing critical insights for enhancing the durability and performance of biomedical implants. Potentiodynamic polarization tests demonstrate that the Ti6Al4V alloy possesses excellent corrosion resistance, which is further enhanced under sliding conditions compared to the test without sliding. When tested against 3D-printed PEEK, the alloy exhibits a mixed wear mechanism characterized by both abrasive and adhesive wear. Open-circuit potential (OCP) measurement of Ti6Al4V demonstrates the alloy’s superior electrochemical stability, indicating high corrosion resistance and a favorable coefficient of friction. These findings highlight the potential of 3D-printed PEEK as a viable alternative for biomedical applications, offering rapid patient-specific prototyping, tunable mechanical properties, and improved surface adaptability compared to conventional materials. Full article

Axon guidance, a fundamental process in neural circuit formation, is intricately regulated by Fibroblast Growth Factors (FGFs) and their receptors (FGFRs) through dynamic cytoskeletal remodeling. FGF signaling, mediated by heparan sulfate proteoglycans or Klotho co-factors, activates key downstream pathways: PI3K-Akt, JAK-STAT, PLCγ, and RAS-MAPK. These pathways orchestrate actin filament dynamics, microtubule stability, and the organization of intermediate filaments. These pathways converge on Rho GTPases, cofilin, profilin, and tau to balance the cytoskeletal assembly−disassembly cycles, enabling growth cone navigation. Unresolved questions, such as the mechanisms underlying FGF-mediated growth cone steering, highlight critical future research directions. This review integrates structural, molecular, and functional insights into how FGF-FGFR interactions regulate axon pathfinding, emphasizing the crosstalk between signaling cascades and cytoskeletal plasticity. Elucidating these mechanisms not only advances our understanding of neural development but also opens therapeutic avenues for neuro-developmental disorders, nerve injury, and neurodegenerative diseases by targeting FGF-driven cytoskeletal dynamics. Full article

Additive manufacturing (AM) techniques make fabricating complex designs, prototypes, and end-user products possible. Conductive polymer composites find applications in flexible electronics, sensor fabrication, and electrical circuits. In this study, thermoplastic polyurethane (TPU)-based conductive polymer composite samples were fabricated via fused filament fabrication (FFF). The effects of three important process parameters, including infill density (ID), layer thickness (LT), and fan speed (FS), on various mechanical properties (tensile and compressive properties) were investigated. It was observed that all the considered process parameters affect the mechanical properties, and they are significant parameters, as per the analysis of variance (ANOVA). From scanning electron microscopy (SEM) and optical microscopy, various combinations of parameters such as low ID, high LT, and high FS resulted in the formation of defects such as voids, cracks, and warping, which resulted in low mechanical properties. Finally, process parameter optimization was performed, resulting in a conductive polymer composite with the best possible combination of mechanical properties at high ID, low LT, and medium FS. Full article

Additive manufacturing enables new design solutions across various engineering fields. This work presents a method to enhance the sustainability of adhesive joints by designing joints that can be disassembled and repaired multiple times. The approach involves the use of a Multi-Material Additive Manufacturing process to produce substrates with integrated circuits and electrical resistance, printed using a conductive filament. This resistance can be used to heat the thermoplastic adhesive layer up to 110 °C, allowing for reversibility in the assembly process and enabling joint re-use and repair without constraints on the component’s materials and thicknesses. The joints tested after successive assembly/disassembly operations reach maximum strength during the first iteration, which decreases by around 50% after five repair iterations. The focus of the work is on the feasibility of this process, but it is expected that performance can be improved after process optimization. This result could be highly valuable for enabling component in-service healing and the design for demanufacturing and remanufacturing. Full article

Reaction system (RS) belongs to a type of qualitative computing model inspired by biochemical reactions taking place inside biological cells. It concerns more the interactions and causality among reactions rather than concrete concentrations of chemical entities. Many biochemical processes and models can be represented in the form of reaction systems so that complex relations and ultimate products of a variety of reactions can be revealed qualitatively. The reaction system works in parallel mode. Software simulation of this kind of model may suffer from the penalty of inefficient parallelism for the limited performance of CPU/GPU, especially for the simulation of large-scale models. Considering potential applications of reaction systems in disease diagnoses and in drug developments, hardware implementation of reaction systems provides a better way to accelerate computations involved. In this paper, an FPGA implementation method of a reaction system called RSFIM is proposed. Two small-scale models, i.e., the reaction system of intermediate filaments self-assembly and heat shock response, are implemented on FPGA, achieving a computing speed of $2\times {10}^8$ steps per second. For large-scale models, the ErbB reaction system is implemented, obtaining a speedup of $7.649\times {10}^4$ compared with its highest performance GPU simulation so far. The reaction system binary counter, which is a quantitative model, is also implemented by the Boolean explanation of the qualitative character of the reaction system. FPGA implementation of reaction systems opens a novel research line to speed up the simulations of reaction systems and other biological models in the perspective of parallel digital circuits. Full article

The question as to why deoxidized SrTiO_3−δ becomes metallic and superconducting at extremely low levels of oxygen vacancy concentration has been a mystery for many decades. Here, we show that the real amount of effused oxygen during thermal reduction, which is needed to induce superconducting properties, is in the range of only 10¹⁴/cm³ and thus even lower than the critical carrier concentrations assumed previously (10¹⁷–10¹⁹/cm³). By performing detailed investigations of the optical and electrical properties down to the nanoscale, we reveal that filaments are forming during reduction along a network of dislocations in the surface layer. Hence, a reduced epi-polished SrTiO_3−δ crystal has to be regarded as a nano-composite consisting of a perfect dielectric matrix with negligible carrier density, which is short-circuited by metallic filaments with a local carrier density in the range of 10²⁰/cm³. We present that electro-degradation leads to a more pronounced evolution of filamentary bundles and thus can generate a superconducting state with higher T_C than thermal reduction. These findings indicate that traditional homogeneous models of superconductivity in self-doped SrTiO_3−δ need to be revised, and we propose an alternative explanation taking into account the coexistence of metallic dislocation cores with polar insulating regions allowing for polaronic coupling. Full article