Search Results (1,637)

Portable air-breathing electrochemical devices, particularly polymer electrolyte membrane fuel cells (PEMFCs), offer simple, lightweight, and compact power generation by using atmospheric oxygen as the oxidant. Their performance, however, depends strongly on cathode plate geometry that governs reactant transport, thermal and water management, and mechanical integrity. Conventional manufacturing has historically restricted this architectural design space. This perspective examines how additive manufacturing (AM) enables three-dimensional geometries that can overcome these constraints. An open columnar cathode plate for air-breathing PEMFCs is used as a case study to show how manufacturing-enabled design can improve passive transport, increase the hydrogen conversion efficiency, and integrate multiple functions within a compact component. The same design philosophy can then be extended to metal–air batteries, microbial fuel cells, direct methanol fuel cells, electrolyzers, CO₂ electrochemical reactors, and electrochemical sensors. Finally, the remaining barriers and future opportunities associated with advanced materials, computational design, topology optimization, artificial intelligence, and digital manufacturing are discussed. Overall, AM is presented as a design-enabling platform for next-generation portable electrochemical devices. Full article

Pancreatic ductal adenocarcinoma (PDAC) is defined by significant desmoplastic reaction composed of cancer-associated fibroblasts (CAFs), pancreatic stellate cells (PSCs), extracellular matrix (ECM), immune cells, and abnormal vascularization. This stromal compartment is by no means a passive fibrotic reaction; rather, it contributes to tumor progression and treatment resistance through physical and biological mechanisms. The accumulation and remodeling of collagen, hyaluronic acid, and other ECM components lead to tissue stiffness and increased tissue pressure, compress intratumoral vessels, impair blood flow, promote hypoxia, and limit homogeneous drug delivery. Simultaneously, heterogeneous CAF populations send out paracrine, metabolic, and immunomodulatory signals that can either promote or inhibit tumor growth. Such opposing features may contribute to the inconsistent or unfavorable outcomes observed in attempts to comprehensively reduce the PDAC stroma. Pancreatic neuroendocrine neoplasms (PanNENs), especially well-differentiated pancreatic neuroendocrine tumors (PanNETs), have typically been considered highly vascularized tumors with a relatively limited stromal component. New findings challenge this simplified view. In subgroups of clinically aggressive PanNETs, fibrosis, reduced microvascular density, and CAF-rich stromal phenotypes have been observed. Recent findings also suggest spatially organized interactions between CAFs and the tumor that may promote epithelial–mesenchymal plasticity, invasion, and metastasis. Nonetheless, it remains unknown whether fibrosis in PanNETs constitutes a mechanically relevant barrier to drug delivery comparable to that observed in PDAC. This mini-review explores the desmoplastic barrier in PDAC as a frame of reference, evaluates new findings on stromal and vascular remodeling in PanNETs, and underscores the need to define tumor-specific stromal and vascular phenotypes rather than assuming a common desmoplastic mechanism across all malignant pancreatic tumors. Full article

Bone morphogenetic protein-2 (BMP-2) is a potent osteoinductive factor, but rapid loss of bioactivity, short local retention, burst release, and diffusion into surrounding tissues reduce dose efficiency and may necessitate supraphysiological doses associated with local adverse effects. Hydrogels offer tunable platforms for controlling BMP-2 localization, exposure, and presentation. This review classifies BMP-2-delivering hydrogels by their dominant delivery logic into passive spatial confinement, reservoir-unit-integrated delivery, stimuli-responsive delivery, and programmable biointeractive systems. It then evaluates whether material-level control translates into retained bioactivity, cellular responses, bone regeneration, spatially confined bone formation, and clinically relevant outcomes across conventional and complex-host models. Selected systems preserve BMP-2 activity after chemical modification, immobilization, or triggered release and improve bone formation, structural repair, or spatial localization in specific models. Nevertheless, prolonged retention or greater material complexity does not consistently improve repair, and evidence for true dose sparing remains limited. Outcomes depend on actual bioactive exposure, material degradation, tissue ingrowth, host conditions, and auxiliary components. Translation therefore requires formulation-specific links among dose, bioactive exposure, repair efficacy, local safety, and reproducible manufacturing. Full article

The phase-shifted full-bridge high-frequency-link (PSFB-HFL) inverter adopts a DC to sinusoidal-half-wave to sinusoidal-wave conversion structure, which uses few passive components with small parameter values, and the switching frequency of the subsequent stage is low, resulting in low losses. This makes it well suited for airborne applications requiring large currents on the low-voltage side and a high step-up ratio, and it has the potential to realize combined three-phase output. To meet the dynamic-performance requirements of this structure, this paper adopts a peak current control strategy. However, this control method suffers from a sub-harmonic oscillation problem, for which a corresponding slope compensation scheme is designed. Furthermore, based on the small-signal model of the Buck converter, an accurate small-signal model of the PSFB peak current inner loop, based on the average value of the filter inductor current, is derived. Accordingly, a voltage-outer-loop PI controller is designed to implement closed-loop control and improve the dynamic performance of the system. An experimental prototype of a PSFB-HFL inverter with a 28 V DC input and a rated power of 4 kW was built. Experimental results show that the proposed control strategy ensures robust large-signal stability, maintaining high-quality sinusoidal waveforms under varying load conditions, thus verifying the effectiveness and engineering feasibility of the PSFB-HFL inverter. Full article

Rural residential buildings in China’s Central Plains region suffer from poor envelope thermal performance, resulting in severe thermal discomfort and excessive energy consumption for both winter heating and summer cooling. This study presents a systematic three-in-one envelope retrofit strategy (roof, exterior walls, and windows, with supplementary door replacement) tailored to the region’s cold climate zone (GB 50176-2016, Zone IIB; HDD18 = 2309 °C·d, CDD26 = 131 °C·d), which experiences hot summers and cold winters and thus requires both effective winter insulation and summer heat protection, utilizing cost-effective materials suitable for rural construction. A typical brick-concrete rural residence in Anyang was selected as the case study building. Field measurements of indoor thermal conditions were conducted over 72 h in winter to characterize baseline performance. An Ecotect simulation model was developed and calibrated against measured data using actual hourly meteorological observations from the Anyang National Meteorological Station for the monitored period; the CSWD Typical Meteorological Year (TMY) file was used for the annual simulation. To address concerns regarding discontinued software, key annual load results were cross-validated against an independent EnergyPlus v22.2 model using identical geometry and envelope inputs, yielding agreement within 5%. The proposed retrofit scheme retains the existing 240 mm solid brick walls, adds external insulation consisting of 100 mm EPS panels for walls and 50 mm XPS panels installed at ceiling level within the attic (without disturbing the existing asbestos-cement roof sheeting, in accordance with strict asbestos-handling protocols) for roofs, and replaces single-glazed windows with 6 + 12A + 6 insulated hollow glass units. The results demonstrate that the optimized envelope significantly reduces overall heat transfer coefficients: wall U-value decreases from 1.79 to 0.32 W/(m²·K), roof U-value from 2.46 to 0.48 W/(m²·K), and window U-value from 6.40 to 2.40 W/(m²·K). The passive adaptability index (PAI)—the annual proportion of free-running hours within the fixed 18–28 °C screening band specified in Table 4.3.1 of GB/T 50785-2012—improves from 0.41 to 0.68, and annual heating and cooling energy consumption is reduced by 50.4% (49.6% when the supplementary door replacement is excluded; (123 − 62)/123 = 49.6%). Under this fixed-band screening criterion, indoor operative temperature lies within the band for 68% of annual hours, compared with 41% in the baseline; these figures are fixed-temperature-range screening results rather than a formal adaptive-comfort evaluation. A Glaser method condensation analysis confirms no interstitial condensation risk in the externally insulated EPS wall assembly. This study provides validated, region-specific technical parameters and demonstrates that a coordinated three-component envelope retrofit can achieve over 50% energy savings while substantially improving indoor thermal conditions as measured by the fixed 18–28 °C screening band in rural Central Plains buildings; a formal adaptive thermal comfort evaluation was not conducted and is identified as future work. The material-cost-based simple payback is approximately 5.5 years (CNY 19,500 ÷ CNY 3550/year); including estimated rural labor and scaffolding costs (CNY 4000), the full project payback is approximately 6.6 years (CNY 23,500 ÷ CNY 3550/year). The findings offer practical guidance for large-scale rural building energy retrofitting programs in cold climate zones of China with transitional characteristics. Full article

Input current ripple reduction in DC-DC boost converters is a persistent challenge because input current ripples are driving up filter requirements, electromagnetic interference (EMI), and stress on sources and loads. This ultimately limits power density and efficiency in many applications, from photovoltaic systems to fuel cells and electric vehicle powertrains. While classical interleaving and passive filtering approaches have been proposed, recent years have brought promising advances in magnetic coupling, higher switching frequency, novel interleaved topologies, and control-based reduction strategies. The current state of the art offers a solid foundation, and further investigations could help enable a more comprehensive comparison and better guide the selection of the most appropriate approach according to performance objectives. An increasing number of recent publications are focusing on the topic of current ripple reduction. Indeed, a recent analysis of international scientific databases shows a steady increase in publications addressing current ripple in DC-DC converters, reflecting both the intensifying demands of modern power electronics applications and the recognition that traditional solutions may not be the most suitable for next-generation converters and systems. This review fills that gap in the case of DC-DC boost converters, where the literature remains fragmented, and a unified comparison of these approaches is still lacking. It compiles, analyses, and compares all current techniques for reducing input current ripple, covering passive filter and inductor sizing methods, component-level improvements such as coupled inductors and wide-bandgap devices, interleaving-based converter architectures, closed-loop control strategies, and hybrid approaches that combine multiple techniques based on papers published over the last decade (2016–2026). More particularly, the dependence of LC filter sizing on the duty cycle and switching frequency is examined, mutual inductance design for ripple cancellation is explored, and the operation of destructive interference in parallel-phase and multilevel converter configurations is compared. The techniques reviewed in this paper highlight remarkable results: A 60–90% ripple reduction by using magnetic coupling at 50% duty cycle, near-zero input current ripple with multiphase interleaving in N-phase converters with optimal phase shift, and dynamic ripple suppression across wide operating ranges through advanced control. The review concludes with a qualitative comparison of the main input current ripple reduction technique families in terms of advantages, limitations, application domains, and reduction potential, and discusses opportunities for hybrid passive–active strategies in next-generation high-efficiency boost converters. Full article

DC-signal injection into the secondary $xy$ subspace is commonly used in multiphase drives for online stator-resistance estimation and winding-condition monitoring because it can be decoupled from the fundamental torque-producing excitation. Under open-phase post-fault operation, however, the post-fault current constraints unavoidably couple part of this injected DC signal into the zero-sequence subspace. The resulting zero-sequence current can establish a stationary third-spatial-harmonic field and produce an additional speed-dependent braking torque. This paper experimentally and analytically investigates how this braking effect depends on winding connection and coil pitch in six-phase induction machines. Dual three-phase (D3P), asymmetrical six-phase (A6P), and symmetrical six-phase (S6P) connections are evaluated using two separate 1.1 kW reconfigurable prototypes of the same machine rating and principal geometry but with different stator coil pitches. Isolated rotational tests at several DC-injection levels are used to characterize the braking-torque–speed behavior. A combined rotational–standstill single-subspace characterization procedure is also proposed to obtain practical local estimates of the associated zero-sequence equivalent-circuit quantities. The results show that D3P is much less susceptible to the braking effect because of third-harmonic MMF cancellation, whereas A6P and S6P exhibit substantially higher braking torque. Moreover, 5/6 chording provides an effective passive means of suppressing this undesirable component. Full article

Grounding systems are essential components of electrical infrastructures, ensuring personnel safety, equipment protection, and operational reliability. In the context of smart cities, these systems have evolved from passive safety elements to critical assets within interconnected cyber-physical infrastructures. Simultaneously, advances in Artificial Intelligence (AI), the Internet of Things (IoT), digital twins, and predictive analytics have created new opportunities for improving the design, monitoring, maintenance, and resilience of electrical systems. This study presents a systematic review of AI applications in grounding systems and smart city electrical infrastructures following the PRISMA 2020 methodology. The literature search was conducted exclusively in the Scopus database, and 179 studies were included in the final synthesis. The review analyzes the scientific literature published between 2015–2026 and examines four major thematic classification dimensions: (i) the role of grounding systems in smart city infrastructures, (ii) AI-based design and optimization methods, (iii) intelligent monitoring, fault detection, predictive maintenance, and digital twins, and (iv) sustainability, resilience, and future implementation challenges. The thematic classification provides the organizational structure for the evidence synthesis, while a separate set of seven assessment axes is used to comparatively evaluate the technological capabilities and integration potential of the main AI technology families. The findings were synthesized by distinguishing between evidence directly addressing grounding systems and evidence from adjacent smart-grid and electrical-infrastructure domains. Direct grounding-system studies indicate that Machine Learning (ML), Deep Learning (DL), optimization algorithms, and intelligent sensing can support grounding design, condition assessment, fault diagnosis, and maintenance-related tasks, although the available evidence remains limited and heterogeneous. In adjacent electrical-infrastructure domains, AI-based approaches report high fault-detection performance, enable real-time condition monitoring, and support predictive maintenance strategies associated with reductions in downtime and maintenance costs. These findings provide transferable methodological insights for intelligent grounding-system management but should not be interpreted as direct evidence of performance improvements in grounding systems. The review also identifies critical research gaps, including the lack of standardized frameworks, limited large-scale deployments, interoperability challenges, cybersecurity concerns, and the need for explainable and trustworthy AI solutions. The study concludes that AI has the potential to become a foundational technology for the development of intelligent, adaptive, and resilient grounding systems that support the sustainability, reliability, and resilience objectives of future smart cities. Full article

Background/Objectives: Healthcare-associated infections (HAIs) disproportionately burden low- and middle-income countries, but no such description has been published for Uzbekistan. We describe national trends in reported HAIs over 2015–2024 with their regional and clinical distribution and review the country’s infection prevention and control (IPC) regulations against the eight World Health Organization (WHO) Core Components. Methods: We analysed the complete national series of reported HAI cases for 2015–2024 (ten annual counts; 817 cases in 2024, disaggregated by region and HAI type), with official population denominators. Trend was assessed by the Mann–Kendall test, log-linear average annual percentage change (AAPC) and the Theil–Sen slope estimator, with 2020 treated separately as pandemic-affected. The five binding national IPC instruments in force were reviewed against each Core Component using five pre-specified criteria. Results: Reported incidence fell from 3.95 to 2.16 per 100,000 population (45.3%; Mann–Kendall p = 0.007; Theil–Sen slope −0.186 per 100,000 per year, 95% confidence interval (CI) −0.293 to −0.110). The fall in 2020 was isolated (1.00), with an underlying decline of about 6% per year otherwise (AAPC −6.36%, 95% CI −8.34 to −4.33). Tashkent city accounted for 31.7% of cases and had the highest incidence (8.19 per 100,000) and bed density; Jizzakh (3.55) and Navoi (3.44) had elevated incidence at close to average bed density. Surgical site infections were the most frequently reported HAI type (44.1%). Of the eight Core Components, one met all five criteria, six met some and one none; verification was the most frequent shortfall, absent for seven of eight. Conclusions: This is the first decade-long description of reported HAIs in Uzbekistan. Incidence declined substantially, but passive case-finding and the 2020 disruption mean the data cannot separate a fall in occurrence from a fall in detection. Standardised case definitions and facility-level denominators are the first priority among the eight corrective actions proposed. Full article

Thermal management limits the performance of densely integrated electronics. Heat-sink surfaces are conventionally passive elements dedicated to heat rejection. Here we show that one conformal single-walled carbon nanotube (SWCNT) coating renders such a surface dual-functional. The coating comprises p- and n-type SWCNT films whose porous, mesh-like network enlarges the effective surface area and raises the emissivity. It converts part of the rejected heat into electricity through the Seebeck effect. We applied the coating to an alumite-insulated aluminum screw, a compact model of an extended heat-sink surface. Under forced convection at 3.0 m/s, the coating lowered the hot-side temperature of the screw by up to 22 K, from 341.8 K to 319.4 K. Cooling was optimal at 75% axial coverage. Repeated runs and an independently fabricated device confirmed this optimum. The apparent heat-transfer coefficient, defined on the total heater input and on the metallic reference area, rose 1.6-fold, from 172 to 278 W/(m²·K). At full coverage, the same layer generated 0.72 mV and 1.0 nW per p–n pair. The cooling optimum and the power optimum occur at different coverages, which yields a practical design freedom. These results recast the surfaces of cooling components as multifunctional, thermally active layers. Full article

Solid-state transformers (SSTs) are pivotal for next-generation power systems, yet their widespread adoption is hindered by reliability uncertainties under diverse operational conditions. This paper introduces a mission-profile-aware, physics-of-failure (PoF) reliability assessment framework that explicitly links operating conditions, degradation mechanisms, and statistical uncertainty. The approach combines PoF models for stress-sensitive components with handbook-based reliability models for passive elements, employing Joint Electron Device Engineering Council (JEDEC)-aligned statistical methods for failure rate extraction. Quantitative failure-in-time (FIT) estimates are integrated into a physics-informed Failure mode and effects analysis (FMEA), replacing subjective occurrence rankings with FIT-derived quantitative occurrence ratings while retaining explicit severity and detection criteria. The framework is demonstrated on a 10 kW Type-IV SST across multiple mission profiles and ambient temperatures. The results reveal that the system-level mean time between failures (MTBF) varies from 4.6 to over 8 years, with gate-driver electronics and DC-link capacitors dominating FIT contributions. Mission-dependent shifts in failure mechanisms highlight the inadequacy of single MTBF metrics. This scalable framework provides a foundation for reliability-oriented SST design, qualification, and deployment. Full article

Background: Amplitude rise time is a critical acoustic cue for speech perception, yet its neurophysiological processing remains uninvestigated in autism spectrum disorder characterized by communication deficits, sensory abnormalities and often speech delay. This study examined whether children with autism spectrum disorder differ from typically developing peers in auditory event-related potential components across a continuum of rise times. Methods: Electroencephalography was recorded during passive presentation of pure tones with five rise time values (15, 30, 60, 120, 240 ms) in 42 children (21 with autism spectrum disorder, 21 typically developing, aged 4–10 years). Linear mixed models were used to analyze latencies and amplitudes of P1 and N2 components. Results: Children with autism spectrum disorder showed a less systematic pattern of neural modulation across rise times compared to typically developing peers. P1 amplitude was reduced at 15 and 60 ms (trend at 30 ms), with no significant group differences at longer rise times. N2 latency showed an atypical decrease at 60 ms compared to 30 ms, contrasting with the systematic increase observed in typically developing children. P1N2 amplitude reached a minimum at 60 ms in autism spectrum disorder, whereas typically developing children showed a gradual decrease across rise times. Conclusions: These findings provide the first evidence of atypical neurophysiological processing of rise time in children with autism spectrum disorder, with the most pronounced differences in the range of rapid acoustic onsets. Group differences were not detected at longer rise times, suggesting a selective rather than global deficit in temporal envelope processing. Full article

High-temperature lithium-ion battery operation (approaching 100 °C) is challenging due to accelerated degradation of critical cell components, limiting their use in many applications. In this work, we investigate the cycling performance and thermal stability of LiNi_0.33Mn_0.33Co_0.33O₂ (NMC111) and LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) cathodes in coin cells with various additives designed for 100 °C operation. A full-factorial design of experiments varied cathode composition and electrolyte additives, including vinylene carbonate (VC) and lithium difluorophosphate (LiDFP), to statistically evaluate their effects on capacity retention, internal cell resistance, and coulombic efficiency at 100 °C. Cells with NMC111 cathodes, featuring either additive, demonstrated superior thermal stability and markedly longer cycle lives at 100 °C compared to NMC811 cells with additives. NMC811 cells exhibited a higher initial specific capacity, as expected for Ni-rich cathodes, but suffered rapid capacity fade at 100 °C. The LiDFP additive further accelerated capacity loss in NMC811 cells, whereas VC provided minimal performance improvements. Further, the addition of LiDFP generally lowered the cells’ DC resistance, while NMC111 or cells with VC exhibited higher DC resistances. Interestingly, LiDFP exhibited lower, less stable coulombic efficiencies, whereas the addition of VC led to higher, more stable coulombic efficiencies. Energy-dispersive X-ray spectroscopy showed higher fluorine content on both electrodes in cells with low impedance and low capacity retention (cells without VC or with NMC8111), suggesting that these systems promote the formation of lithium fluoride-containing compounds on the electrode interphases, which consume lithium inventory, reduce interphase impedance, and fail to passivate the electrodes. These changes were present under open-circuit conditions and, to a greater extent, during cycling at elevated temperatures, suggesting that parasitic interphase-forming reactions were both chemical and electrochemical. Overall, the results highlight that NMC111 cathodes paired with additives to improve the stability of the solid electrolyte interface and cathode electrolyte interface can enable significantly improved cycle life at 100 °C, whereas Ni-rich NMC811 cathodes are prone to faster performance degradation at elevated temperatures. Full article

High-temperature sodium heat pipes are promising passive heat-transfer components, yet numerical redesign is often disconnected from manufactured and power-tested hardware. This study develops a reference-anchored constrained bi-objective optimization framework based on the common nominal configuration shared by 139 manufactured and power-tested sodium heat pipes at 700 °C and a 4 kW total heat load. Five structural variables determine total mass and thermal resistance under a fixed rated cooling boundary, while eight nonlinear constraints represent wick geometry, five heat-transfer limits, hoop stress, and guide-contact/heat-leak feasibility. A staged workflow separates lexicographic sequential quadratic programming (SQP) endpoint construction, genetic algorithm (GA)-based global candidate generation, augmented-Tchebycheff scalarization, multistart SQP refinement, and independent ε-constraint verification. The scan retained 134 of 420 designs as feasible. The minimum-mass and minimum-resistance endpoints were 1.4837 kg at 0.1280 K/W and 0.0699 K/W at 2.4528 kg, respectively. The endpoint-seeded original GA produced 40 nondominated points, whereas the proposed hybrid method produced 119 nondominated points and recovered 23 of 27 unsupported points identified by the dense ε-constraint reference. The framework delivers numerical design candidates for prototype manufacture and rated power testing; its engineering value is to narrow prototype choices, identify constraint-controlled trade-offs, and connect batch-tested hardware with subsequent redesign and power-test validation. Full article

Cereal crops increasingly encounter drought, salinity and alkalinity, heat, waterlogging, potentially toxic elements, and compound stresses that constrain productivity and grain quality. Secondary metabolites, also referred to as specialized metabolites in the recent literature, represent a dynamic component of cereal stress adaptation rather than a passive catalogue of stress markers. This review aims to synthesize current evidence on how specialized-metabolite pathways contribute to abiotic stress responses in cereals, with particular emphasis on regulatory mechanisms, evidence strength, chemical form, subcellular localization, recovery, and translational relevance. We critically assess evidence from transcriptomics, metabolomics, genetic perturbation, biochemical assays, multi-omics integration, and physiological studies across major cereal crops and evaluate evidence according to causal, associative, and in vitro categories. The evidence reveals that perturbations at the plasma membrane, cell wall, chloroplast, mitochondrion, and endomembrane system levels generate reactive oxygen species, Ca²⁺ signatures, phospholipid signals, and hormone changes that are decoded by CDPK/CPK, CBL–CIPK, SnRK2, and MAPK cascades. These signaling networks converge on MYB–bHLH–WD40, WRKY, NAC, ERF/AP2, HSF, and bZIP regulators and redirect carbon and reducing power through phenylpropanoid, flavonoid, lignin, carotenoid, terpenoid, benzoxazinoid, cyanogenic, and related pathways. Comparative analysis across rice (Oryza sativa L.), wheat (Triticum aestivum L.), maize (Zea mays L.), barley (Hordeum vulgare L.), oat (Avena sativa L.), sorghum (Sorghum bicolor L.), and millets shows conserved regulatory features but substantial crop-, genotype-, tissue-, developmental-stage-, and dose-dependent variation. Functional evidence further indicates that enzyme activity, chemical modification, transport, and subcellular compartmentation can determine whether metabolites contribute to ROS buffering, photosynthetic and membrane protection, cell-wall reinforcement, osmotic or ionic homeostasis, toxic-ion sequestration, or signaling. The review also identifies important limitations in current research, including overreliance on associative omics evidence, insufficient consideration of combined stresses and rehydration, growth–defence trade-offs, and limited field and reproductive-stage validation. To distinguish growth dilution from genuine biosynthetic increases, absolute metabolite content per grain or organ should be measured alongside concentration per unit dry weight. We conclude that improving cereal resilience requires context-dependent and experimentally validated coordination of regulators, biosynthetic enzymes, chemical modification, transport, and compartmentation rather than indiscriminate elevation of total specialized-metabolite concentration. Full article