Search Results (5,179)

Shell-and-tube heat exchangers serve as critical energy conversion equipment in marine nuclear power systems, where their thermal performance directly determines operational safety and reliability. This study proposes a kind of shark-skin bionic structure tube to enhance compactness and power density. Key findings are: (1) The microstructures induce intensive secondary flows and helical vortices, substantially disrupting the thermal boundary layer and amplifying near-wall perturbations. Maximum enhancement reaches 56.7% in heat transfer coefficient and 33.1–58.3% in heat exchange capacity, with PEC consistently maintained at 1.25–1.30. (2) Fouling deposition significantly degrades heat transfer performance. The fouling layer is simplified using a homogenized model, where the thickness reaches 0.20 mm, the heat transfer capacity of the shark-skin bionic structure tube becomes essentially equivalent to that of a smooth tube, and the heat transfer enhancement effect is largely lost. (3) This study reveals the coupling mechanism between enhanced heat exchange and fouling deposition. On a macroscopic scale, the design and manufacturing of a shark-skin bionic structure tube are achieved, laying a theoretical and design foundation for the development of a new generation of marine heat exchangers with high anti-fouling performance. Full article

Sustainable language education necessitates scalable, accessible learning environments that foster long-term learner autonomy and reduce educational inequality. While online courses have democratized access to language learning globally, persistent deficiencies in instructor-student interaction and learner engagement compromise their sustainability. The “face effect,” denoting the influence of instructor facial appearance on learning outcomes, remains underexplored as a resource-efficient mechanism for enhancing engagement in digital environments. Furthermore, effective measures linking psychological engagement to sustained learning experiences are notably absent. This study addresses three research questions within a sustainable education framework: (1) How does instructor identity, particularly facial appearance, affect second language learners’ outcomes and interactivity in scalable online environments? (2) How can digital human technology dynamically personalize instructor appearance to support diverse learner populations in resource-efficient ways? (3) How does instructor identity influence learners’ flow state, a critical indicator of intrinsic motivation and self-directed learning capacity? Two controlled experiments with Japanese language learners examined three instructor identity conditions: real teacher identity, learner self-identity, and idol-inspired identity. Results demonstrated that the self-identity condition significantly enhanced oral performance and flow state dimensions, particularly concentration and weakened self-awareness. These findings indicate that identity-adaptive digital human instructors cultivate intrinsic motivation and learner autonomy, which are essential competencies for lifelong learning. This research advances Sustainable Development Goal 4 (Quality Education) by demonstrating that adaptive educational technology can simultaneously improve learning outcomes and psychological engagement in scalable, cost-effective online environments. The personalization capabilities of digital human instructors provide a sustainable pathway to reduce educational disparities while maintaining high-quality, engaging instruction accessible to diverse global populations. Full article

Background/Objectives: There is a growing acknowledgment of the role of endothelial dysfunction as an outcome predictor and therapeutic target in heart failure (HF). Flow-mediated dilation (FMD) and the reactive hyperemia index (RHI) are non-invasive diagnostic measures of endothelial dysfunction. In this meta-analysis, we aimed to highlight the importance of endothelial dysfunction, as measured by FMD and RHI, and its association with clinical outcomes, including mortality, hospitalization, and exercise capacity in patients with HF. Methods: We reviewed observational studies assessing clinical outcomes of HF patients with and without impaired FMD and/or RHI. Searches around electronic research databases were conducted using predetermined keywords. Meta-analysis was subsequently performed on selected studies that assessed adverse events in patients with HF. Our primary outcome was adverse events, which include mortality, disease progression, hospitalization, and complications (stroke, myocardial infarction, and heart attack). Results: This review included 16 studies, with a total of 1890 participants. Meta-analysis demonstrated that lower FMD in patients with HF had a significantly higher risk of adverse events (HR 1.44, 95% CI 1.15–1.82; p = 0.002; I² = 80%, random-effects model). In contrast, lower RHI was not associated with an increased risk of adverse events (HR 1.32, 95% CI 0.96–1.82; p = 0.09; I² = 87%, random-effects model). Conclusions: Endothelial dysfunction is associated with adverse endpoints in HF. FMD showed consistent prognostic values, while RHI’s prognostic significance is less clear and requires further investigation. Full article

Polymerase chain reaction (PCR) is vital in biological and medical research, but microfluidic PCR chips often suffer from limited reagent processing capacity and slow thermal response under high flow rates. To address this, we designed three serpentine microfluidic chips with double-sided heaters: a standard serpentine chip (case 1), one with unchamfered channel expansion areas (case 2), and one with chamfered expansions (case 3). Using numerical simulations, we analyzed temperature, velocity, and pressure distributions at flow rates of 75, 125, and 175 μL/min. At 175 μL/min, case 2 showed a 41% higher pressure drop than case 1, but also demonstrated significantly improved thermal performance: the constant-temperature zones were extended by 30 mm, 10 mm, and 30 mm at 95 °C, 72 °C, and 55 °C, respectively; the temperature gradient in expansion zones increased by 1.6 times; and the maximum temperature difference decreased by 80%. Case 2 achieved the best trade-off between thermal performance and flow resistance, making it suitable for high-flow-rate PCR applications. Full article

Extrusion of AlZnMgCu alloys is associated with a very high plastic resistance of the materials at forming temperatures and significant friction resistance, particularly at the contact surface between the ingots and the container. In technological practice, this translates into high maximum extrusion forces, often close to the capacity of hydraulic presses, and the occurrence of surface cracking of extruded profiles, resulting in a reduction in metal exit speed (production process efficiency). The accuracy of mathematical material models describing changes in the plastic stress of a material as a function of deformation, depending on the forming temperature and deformation speed, plays a very important role in the numerical modelling of extrusion processes using the finite element method (FEM). Therefore, three mathematical material models of the tested aluminium alloy were analysed in this study. In order to use the results of plastometric tests determined on the Gleeble device, they were approximated with varying degrees of accuracy using the Hnsel–Spittel equation and then implemented into the material database of the QForm-Extrusion^® programme. A series of numerical FEM calculations were performed for the extrusion of Ø50 × 3 mm tubes made of 7075 aluminium alloy using chamber dies for two different billet heating temperatures, 480 °C and 510 °C, and for three different material models. The metal flow was analysed in terms of geometric stability and dimensional deviations in the wall thickness of the extruded tube and its surface quality, as well as the maximum force in the extrusion process. Experimental studies of the industrial extrusion process of the tubes, using a press with a maximum force of 28 MN and a container diameter of 7 inches, confirmed the significant impact of the accuracy of the material model used on the results of the FEM numerical calculations. It was found that the developed material model of aluminium alloy 7075 number 1 allows for the most accurate representation of the actual conditions of deformation and quality of extruded tubes. Moreover, the material data obtained on the Gleeble simulator made it possible to determine the limit temperature of the extruded alloy, above which the material loses its cohesion and cracks appear on the surface of the extruded profiles. Full article

In Mediterranean climate regions, water scarcity, seasonal droughts and hydrological extremes are exacerbated by climate change. In these areas, small dams are increasingly used as decentralized water infrastructure for water supply, especially in agricultural areas. However, several challenges must overcome when planning and managing small reservoirs. This review combines evidence from case studies to analyze the benefits and challenges of small dams. The findings show that small reservoirs may offer a wide array of ecological, agricultural, hydrological, and socio-economic benefits when strategically planned and properly maintained, providing water and contributing to groundwater recharge, vegetative restoration, and biodiversity conservation, while simultaneously controlling flash floods in a cost-effective and participatory manner. On the other hand, evaporation losses and sedimentation may affect water quality and reduce storage capacity. In addition, small dams may negatively affect river ecosystems. Persistent disturbance of downstream flow and sediment regime contributes to altered river morphology and habitat, with effects on biota, and may reduce river system resilience. These impacts are context-dependent, influenced by dam density, geomorphic setting, and climate. Finally, this study highlighted the importance of governance and maintenance practices. Polycentric and participative systems may promote more adaptable responses to water stress, whereas fragmented institutions exacerbate trade-offs between water supply and ecological integrity. Full article

Simulation studies of adsorption in complex effluents are challenging due to nonlinear interactions between sorbents, adsorbates and carrying flows. This study investigates effluents from oil and textile industries, characterised by their heavy metal content and chemical oxygen demand. It examines the process in a continuous-flow laboratory-scale adsorption system. Results were validated using process modelling based on mass and energy conservation, applied to an industrial adsorber. The model described surface sorption mechanisms on bioactivated carbon at the molecular level and predicted breakthrough curve profiles, integrated with Aspen Plus ^® adsorption simulation under industrially relevant conditions. Experimental data and model predictions showed good agreement, with relative deviations ranging from 0.2% to 24.6%. Differences in adsorption capacities between oily and textile effluents highlighted the influence of coexisting constituents. At the same time, the varied behaviour of identical components supported the hypothesis of multifactorial effects in complex mixtures. The optimisation study, using Response Surface Methodology with a Central Composite design, evaluated factors such as bed height, feed rate, and adsorption cycle time, achieving enhanced removal efficiencies of 62% for chemical oxygen demand and 25% for suspended solids. Full article

Background: Chronic inflammation and the development of cancer are closely linked, with components that comprise the tumour microenvironment—including proinflammatory cytokines—exerting essential tumourigenic effects. These proinflammatory cytokines include IL-1β, which has been reported to be overexpressed in several cancers and shown to activate several signalling pathways. These pathways may involve kinases such as AKT (serine/threonine kinase) and Src (Proto-oncogene tyrosine-protein kinase), and have a broad capacity to activate nuclear factors, including NF-κB (Nuclear Factor kappa-light-chain-enhancer of activated B cells), which can regulate the transcription of genes encoding proteins such as cIAP1 (Cellular Inhibitor of Apoptosis Protein 1), Bcl-2 (B-cell lymphoma 2), and cyclin D1, thereby regulating processes like apoptosis and cell cycle inhibition. Objectives: The aim of this study was to investigate the role of IL-1β (Interleukin-1 beta) in regulating cell death and proliferation in RS4:11 leukaemic lymphoblasts via the PI3K (Phosphoinositide 3-kinase)/AKT/Src/NF-κB pathway using an in vitro experimental approach. Methods: We employed flow cytometry to determine the expression levels and phosphorylation status of various proteins; proliferation was assessed using the CCK-8 kit, and apoptosis was evaluated with the Annexin V kit. Results: Our findings indicate that the IL-1β-activated signalling pathway modulates these cellular processes in leukaemic lymphoblasts. Conclusions: We therefore conclude that IL-1β exerts significant effects on cell death and proliferation in leukaemic lymphoblasts through the PI3K/AKT/NF-κB pathway, with the study’s findings indicating that an inflammatory environment may promote such lymphoblasts to acquire neoplastic characteristics. As such, the proteins involved in the effects evaluated in this work could be considered as potential therapeutic targets for the treatment of Acute Lymphoblastic Leukaemia (ALL). Full article

At present, the continuous growth of renewable energy integration and power grid load demand has placed higher requirements on the transmission capacity and power flow control capability of power systems. Owing to its flexible and controllable power flow characteristics, DC transmission technology has been introduced into AC grid structures, making AC/DC hybrid power grids an important development trend. However, the increasingly prominent power flow security issues caused by the complex coupling characteristics between AC and DC systems pose new challenges. First, this paper conducts an in-depth analysis of the operating mechanisms and power flow coupling characteristics of AC/DC hybrid transmission sections under various operating conditions. To address the dual challenges of insufficient utilization of transmission capacity and power flow security, a novel AC-like AC/DC power flow coordinated optimization strategy is proposed. Based on phase angle coordinated control, the autonomous response capability of the DC system is leveraged to perform real-time control and optimization of transmission power on lines, maximizing the capacity utilization of AC/DC hybrid transmission section while satisfying security and stability requirements. Finally, simulation studies based on a transmission network containing two four-machine AC systems verify that the proposed strategy fully meets the security and stability requirements of AC/DC hybrid power grids, providing reliable technical support for the coordinated development of future AC/DC grids. Full article

The capacity of traditional distribution networks is limited. After large-scale distributed power sources are connected, it is difficult to consume them at the same voltage level, which can lead to transformer reverse overloading and voltage limit violations. Although the unified power flow controller (UPFC) excels in flexible power flow regulation and power quality optimization, existing research on it is mostly focused on the transmission grid, focusing on device topology, power flow control, etc. Fault protection is also targeted at high-voltage and ultra-high-voltage domains and only covers a single overvoltage or overcurrent fault. Research on the protection of the unified power flow controller in a distribution network (D-UPFC) remains scarce. A key challenge is the absence of fault protection schemes that are compatible with the unified power flow controller in a distribution network, which cannot meet the requirements of the distribution network for monitoring and protecting multiple fault types, rapid response, and equipment economy. This paper first designs a protection device centered on the distribution thyristor bypass switch (D-TBS), completes the thyristor selection and transient energy extraction, optimizes the overvoltage protection loop parameter, then builds a three-level coordinated protection architecture, and, finally, verifies through functional and system tests. The results show that the thyristor control unit trigger is reliable and the total overvoltage response delay is 1.08 μs. In the case of a three-phase short-circuit fault in a 600 kVA/10 kV system, the distribution thyristor bypass switch can rapidly reduce the secondary voltage of the series transformer, suppress transient overcurrent, achieve isolation protection of the main equipment, provide a reliable guarantee for the engineering application of the distribution network unified power flow controller, and expand its distribution network application scenarios. Full article

In arid regions, rainfall is scarce, summer-concentrated, and prone to extreme events, while evaporation exceeds precipitation, creating fragile ecosystems that need scientific stormwater management for flood resilience. Sponge cities, through the implementation of green infrastructure, can alleviate urban flooding, improve rainwater utilization, and enhance the urban ecological environment. Under the “dual carbon” target, sponge city construction has gained new developmental significance. It must not only ensure core functions and minimize construction costs but also fully leverage its carbon reduction potential, thereby serving as a crucial pathway for promoting urban green and low-carbon development. Therefore, this study focused on Xining, a typical arid city in Northwest China, and couples the Non-dominated Sorting Genetic Algorithm-III (NSGA-III) with the Storm Water Management Model (SWMM) to construct a multi-objective optimization model for Low Impact Development (LID) facilities. The layout optimization design of LID facilities is conducted from three dimensions: life cycle cost (LCC), rainwater utilization rate (K), and carbon emission intensity (CI). Hydrological simulations and scheme optimizations were performed under different design rainfall events. Subsequently, the entropy-weighted TOPSIS method was utilized to evaluate and compare these optimized schemes. It is shown by the results that: (1) The optimized LID schemes achieved a K of 76.2–80.43%, an LCC of 2.413–3.019 billion yuan, and a CI of −2.8 to 0.19 kg/m²; (2) Compared with the no-LID scenario, the optimized scheme significantly enhanced hydrological regulation, flood mitigation, and pollutant removal. Under different rainfall return periods, the annual runoff control rate increased from 64.97% to 80.66–82.23%, with total runoff reduction rates reaching 46.41–49.26% and peak flow reductions of 45–47.62%. Under the rainfall event with a 10-year return period, the total number of waterlogging nodes decreased from 108 to 82, and the number of nodes with a ponding duration exceeding 1 h was reduced by 62.5%. The removal efficiency of total suspended solids (TSS) under the optimized scheme remained stable above 60%. The optimized scheme is highly adaptable to the rainwater management needs of arid areas by prioritizing “infiltration and retention”. Vegetative swales emerge as the primary facility due to their low cost and high carbon sink capacity. This study provides a feasible pathway and decision-making support for the low-carbon layout of LID facilities in arid regions. Full article

The power allocation in Vanadium Redox Flow Battery (VRB) energy storage systems faces a conflict between long-term lifespan and real-time power coupling. Using a single-layer optimization method to directly address multiple objectives simultaneously may lead to conflicts among these objectives. Therefore, this paper presents a multi-objective two-layer optimization allocation strategy. Its core is hierarchical scheduling for long/short-term goals to optimize multi-attribute objectives precisely. A two-layer model comprising an initial allocation layer and an operational optimization layer is constructed to ensure the prioritization of long-term lifespan objectives based on a predefined hierarchical structure. The initial allocation layer focuses on the long-term objective of energy storage capacity lifespan, by prioritizing minimal capacity degradation. A differential evolution algorithm is then applied to perform preliminary allocation of the total power demand. The operational optimization layer aims to achieve optimal State of Charge (SOC) balance across all units and minimize power losses. An Adaptive Multi-Objective Harris Hawks Optimizer (ASAMOHHO) based on adaptive simulated annealing is established to find the Pareto optimal solution set, and ultimately determining the real-time power allocation plan for each unit. Comparative simulations with conventional methods were conducted, and the results demonstrate that the proposed strategy provides an efficient and practical solution for efficient VRB scheduling. Full article

To achieve the upcycling of annually upsurging lignocellulosic wastes, the artificial humification of furfural residue is investigated under hydrothermal conditions with the objective of producing a high-concentration nitrogen-phosphorus-potassium (NPK) suspension fertilizer. Through orthogonal analysis, process conditions are optimized as a liquid-to-solid (aqueous KOH to furfural residue) ratio of 15, a reaction time of 5 h and a hydrothermal temperature of 160 °C. Subsequently, we screen out a formulation of suspension agents to stabilize the alkaline leachate, in which 0.50% sodium lignosulfonate, 0.20% xanthan gum and 0.05% potassium sorbate are incorporated via wet ball-milling. The Herschel–Bulkley equation well fits the rheological characteristics of the resulting suspension fertilizer with R² value exceeding 0.99. This suspension system is thus determined as one pseudoplastic non-Newtonian fluid. Due to higher static viscosity, it demonstrates superior anti-agglomeration capacity within a temperature range of 15–55 °C, while flowing smoothly through pipes during high-speed spraying onto the soil relied on its shear thinning. These findings provide novel insights for the high-value utilization of bio-waste and the development of new fertilizers with less consumption of energy and water. Full article

This scoping review examines public health communication across nine Eastern European and Central Asian states—Armenia, Azerbaijan, Belarus, Kazakhstan, Kyrgyzstan, Russia, Tajikistan, Turkmenistan, and Uzbekistan—highlighting how these systems have transitioned from Soviet-era legacies to contemporary practices. Eligibility criteria included the English- and Russian-language literature published from 1998 onwards, focusing on nine post-Soviet states. Sources of evidence comprised searches in Google Scholar, ScienceDirect, SSRN, Heliyon, MEDLINE/PubMed, and official government websites. Data were charted by three independent reviewers using a standardized form, with discrepancies resolved by senior reviewers. The review identifies persistent gaps in communication during health crises, with a particular focus on the COVID-19 pandemic, where centralized and hierarchical information flows often undermine transparency and responsiveness, as well as further increased health inequalities between rural and urban health outcomes. Despite ongoing reforms, the communication dimension of healthcare systems remains underdeveloped. Findings reveal that centralized and top-down communication remains a dominant feature across the region, hindering timely dissemination of information and limiting the capacity to counter misinformation, as both misinformation and disinformation sometimes emerge from the government. Ultimately, this review contributes a critical analysis of these systematic communication failures and underscores the need to strengthen public health communication and reduce health inequalities. To do it, governments must prioritize transparency, disclose decision-making processes, and rely on evidence-based messaging to build trust. Effective crisis response requires not only government leadership but also the active engagement of the medical and patient communities, supported by civil society and independent media. This review points out the need for more inclusive, transparent, and trust-oriented communication strategies to enhance public health preparedness and resilience in nine Eastern European and Central Asian contexts. Full article

This study assesses the environmental implications of reusing used electrical and electronic equipment (UEEE) in Slovenia. Reuse operations at four centres Ponovne Uporabe were analysed by integrating material flow analysis with a simplified life cycle assessment approach. Four scenarios were evaluated: S1 (optimistic reuse), S2 (conservative reuse), S3 (no reuse), and S4 (full reuse), each varying in allocation of materials to reuse, recycling, and incineration, as well as in the assumed reuse effectiveness. The results show that S4 (full reuse) achieved the highest emissions reduction of 7.87 kg CO₂-eq per kg of material input, highlighting the substantial environmental benefits of reuse over recycling. Optimistic reuse (S1), which assumes full substitution, also yields significant environmental benefits of 7.82 kg CO₂-eq per kg of material input. In contrast, S3 (the no-reuse scenario), in which materials are diverted mainly to recycling, results in an emission reduction of 5.2 kg CO₂-eq per kg of material input. S2 (conservative reuse), applying a conservative reuse factor, shows the lowest emission avoided at 4.1 kg CO₂-eq per kg of material input. Although based in Slovenia, this study offers transferable insights for countries aiming to scale reuse systems. The results highlight that maximizing environmental benefits within the circular economy model requires system supports, including design for reuse, durability, reparability, effective preparation for reuse operations, supportive policy frameworks and adequate financial and infrastructural capacity. Full article