Search Results (6,799)

The dynamic strain aging (DSA) behavior of an extruded Mg–3Gd–1Zn (wt.%) alloy was investigated under compressive deformation at intermediate temperatures (150–250 °C) and strain rates ranging from 5 × 10⁻⁵ to 10⁻³ s⁻¹. The as-extruded alloy exhibited equiaxed grains (~20 µm), with all alloying elements retained in solid solution and a weak basal texture. Serrated flow was observed under different temperature and strain-rate conditions. The critical strain, which denotes the onset of serrations, decreased with increasing temperature and increased with strain rate. Notably, the temperature dependence of the critical strain exhibited anomalous non-linear behavior, with a sharp increase at 250 °C, attributed to the formation of low-mobility Gd–Zn clusters/precipitates that depleted mobile solutes from the matrix. In situ synchrotron radiation diffraction revealed the activation of {10.2}⟨10.1⟩ tensile twinning as the dominant deformation mechanism, with periodic plateaus in twin intensity coinciding with macroscopic stress serrations. HAADF-STEM analysis confirmed Gd and/or Zn segregation at twin boundaries and dislocations, leading to the formation of nanoscale clusters during deformation. The overall mechanical response is rationalized by a temperature-dependent competition between solute diffusion and solute clustering at elevated temperatures. Full article

The thermomechanical deformation behavior of high-entropy alloys (HEAs) is governed by complex interactions among strain, strain rate, and deformation temperature, necessitating robust constitutive models for accurate flow stress prediction and process optimization. In this study, a novel Zerilli–Armstrong (NZA) constitutive model was developed to characterize the hot deformation behavior of FeCoCrNi HEA. The proposed NZA model incorporates enhanced descriptions of strain hardening and deformation-temperature coupling to improve prediction accuracy. The predictability of the proposed NZA model was systematically evaluated and compared with that of the original Zerilli–Armstrong (ZA) and modified Zerilli–Armstrong (MZA) models using key statistical indicators, including the correlation coefficient (R), average absolute relative error (AARE), and root mean square error (RMSE). The findings demonstrate that the NZA model exhibits superior predictive performance, achieving an excellent correlation coefficient (R) of 0.997, a low AARE of 4.22%, and an RMSE of 5.82 MPa. These results confirm the reliability and effectiveness of the proposed constitutive framework in accurately describing the thermomechanical flow behavior of FeCoCrNi HEA over a wide range of deformation conditions. The proposed NZA model provides a robust framework for optimizing hot-forming processes and improving the manufacturing performance of HEA-based components while promoting sustainable manufacturing through reduced material consumption, enhanced energy efficiency, and support for SDGs 9 and 12. Full article

Palmatine chloride (berbericinine, C₂₁H₂₂ClNO₄) is a protoberberine alkaloid found in several plants, including Rhizoma Coptidis, Cortex Phellodendri, Rhizoma Corydalis, Guduchi (Tinospora cordifolia), and Tinospora sagittata roots. Palmatine chloride (PA) is known as an inhibitor of dopamine generation. However, its effect on endoplasmic reticulum (ER) stress-related macrophage activation caused by endotoxin (lipopolysaccharide) is not yet well known. In this study, the effects of PA on pyroptotic responses of mouse macrophages (RAW 264.7) activated by endotoxin were investigated using Griess reagent assay for nitric oxide (NO) production, fluo-4 assay for cytosolic calcium release, dihydrorhodamine 123 assay for hydrogen peroxide production, multiple cytokine assay for cytokine production, real-time PCR for inflammatory gene transcriptions, and flow cytometry assay for p38 MAPK activation. Preliminary experiments using THP-1 human monocytic cells demonstrated that PA was not cytotoxic and significantly reduced basal NO production. Results revealed that PA significantly reduced excessive production levels of NO, hydrogen peroxide, pro-inflammatory cytokines (such as interleukin (IL)-6, CCL3 (MIP-1α), and CSF2 (GM-CSF)), and cytosolic calcium release in endotoxin-stimulated RAW 264.7, but significantly increased the production of anti-inflammatory cytokine IL-10. PA inhibited endotoxin-induced transcripts of Chop, Stat1, Fas, and c-Fos in activated RAW 264.7. It also decreased p38 MAPK phosphorylation and level of Fas in RAW 264.7 stimulated by endotoxin. To further interpret these findings, a network pharmacology-informed analysis based on large-scale literature mining was performed, supporting the multi-target regulatory role of PA in ER stress-related pathways. Briefly, PA exerts anti-inflammatory effects on endotoxin-stimulated RAW 264.7 via the calcium-CHOP pathway, consequently reducing endotoxin-induced production of pro-inflammatory mediators (NO, cytokines, etc.) and relieving ER stress-related pyroptotic cascade. Full article

The design of intravascular ultrasound (IVUS) catheters involves inherently coupled acoustic, hemodynamic, and structural requirements. Existing design strategies, which often rely on empirical geometric refinement or single-physics optimization, are limited in their ability to simultaneously ensure acoustic transmission efficiency, flow compatibility, and mechanical reliability. A multiphysics topology optimization method for the integrated design of IVUS catheters under acoustic–fluid–structure interactions is proposed in this paper. A density-based design variable is introduced to characterize the material distribution within the design domain, and consistent interpolation schemes are employed to relate this variable to the effective acoustic properties in the Helmholtz equation, the Brinkman penalization coefficient in the incompressible Navier–Stokes equations, and the elastic stiffness tensor in the structural equilibrium equation. The optimization problem is formulated as a normalized multi-objective minimization of acoustic transmission loss, flow resistance, and structural compliance, subject to constraints on material volume, received acoustic energy, wall shear stress, and structural displacement. Density filtering and smooth Heaviside projection are incorporated to regularize the design field and promote well-defined material boundaries. An adjoint sensitivity formulation is further developed to enable efficient gradient evaluation for the coupled system. Compared with the initial design, the average acoustic transmission efficiency has increased by $59.01\%$, the shear stress has decreased by $53.87\%$, and the stiffness matching rate has reached $98.27\%$. The objective function converged after 35 iterations, demonstrating the numerical stability of the proposed acoustic–fluid–structure topology optimization framework. Full article

Indian metropolitan cities such as Mumbai grapple with rapid urbanisation, extreme urban density, high built-up areas, loss of green cover, and shrinking open spaces, resulting in increased impermeable surfaces, urban heat island effects, and frequent flooding occurrences. Modern stormwater management has increasingly been characterised by integrated grey-green approaches; however, cities in the Global North benefit from established policies, technical expertise, and financial resources that enable the systematic and large-scale integration of Blue-Green Infrastructure (BGI) through district-wide geospatial assessment frameworks, unlike many cities in the Global South. Despite growing interest in nature-based stormwater solutions, there remains a dearth of geospatial empirical research from India examining the placement, distribution, performance, and functionality of BGI integrated with existing stormwater management systems in cities such as Mumbai. Furthermore, hydrological modelling using tools such as the Storm Water Management Model (SWMM) for the design, planning, and implementation of BGI in Indian cities remains largely unexplored. This study explores the role of BGI strategies in improving urban stormwater management within high-density Indian cities under a 25-year return period extreme rainfall scenario. Using an integrated approach that combines QGIS-based spatial analysis with EPA-SWMM hydrologic-hydraulic modelling, the research examines runoff behaviour, identifies flooding hotspots, and evaluates the effectiveness of Low Impact Development (LID)-based BGI measures such as permeable pavements, infiltration trenches, and green roofs applied at the ward level in Mumbai’s F/North and G/North Wards. Detailed land use classification, spatial mapping, and rainfall simulation corresponding specifically to a 25-year return period rainfall event was used to assess pre- and post-intervention conditions. The findings indicate that the applied BGI measures led to a 12.6% reduction in peak runoff (137.6 m³/s to 120.2 m³/s) and a 5.5% decrease in total runoff volume (783,510 m³ to 740,410 m³). More importantly, the peak flooding flow rate decreased by 45% (94.1 m³/s to 51.7 m³/s), demonstrating that BGI measures can efficiently reduce peak flooding flows by extending runoff hydrographs during extreme rainfall events. These findings are specifically applicable to the simulated 25-year return period extreme rainfall scenario and may vary under different rainfall intensities or return periods. Less extreme events could potentially experience even greater relative reductions or prevent flooding altogether, while also easing downstream hydraulic loads. Overall, strategically placed BGI interventions can significantly reduce surface runoff and peak flow, thereby enhancing stormwater resilience within spatially constrained urban environments. This study provides a replicable, data-driven framework for catchment-scale stormwater planning in dense Indian cities under extreme rainfall conditions, offering practical insights into methods, local contextual considerations, and spatial planning strategies for policymakers and urban planners seeking to retrofit and adapt existing infrastructure under increasing hydrologic stress and climate variability. Full article

After long-term waterflooding in offshore oilfields, the remaining oil becomes highly dispersed and discontinuous. To address the limitations of classical waterflooding theory in describing the effects of microscopic oil occurrence and stress differences on oil-phase flow, this study investigated oil–water two-phase flow during heavy-oil waterflooding using core samples from the Bohai Oilfield. The evolution of the oil-phase starting pressure gradient at different water-cut stages was measured through core two-phase steady-state displacement experiments. By combining in situ core CT scanning with pore-scale phase-field simulations, the multi-form start-up mechanisms and microscopic causes of the oil phase were clarified. The fractal characteristics of the reservoir pore structure were further incorporated to establish a calculation method for the multi-form start-up resistance of the oil phase. The results show that, as the water cut increases, the starting pressure gradient of the oil phase exhibits a nonlinear increasing trend. At a water cut of 90%, the oil-phase starting pressure gradient is approximately 7–8 times that of the pure oil phase. Meanwhile, the oil phase gradually transforms from a continuous phase to a discontinuous phase, with a smaller pore radius and a larger surface area per unit volume. Owing to the Jamin effect, capillary force exerts a stronger influence on oil-phase flow, resulting in a significant increase in the starting pressure gradient during the ultra-high water-cut stage. These findings provide a pore-scale explanation for the increase in oil-phase starting pressure gradient during ultra-high water-cut waterflooding and offer a theoretical basis for the sustainable development of mature offshore oilfields. Full article

To address surface quality defects caused by traditional mechanical polishing of gears, such as machining scratches and large surface waviness, this study proposes a novel immersed chemical-mechanical polishing (CMP) process for gear finishing. Numerical simulations were conducted in FLUENT to analyze the gear surface stress distribution and polishing fluid flow trajectories under different process conditions. The Euler–Euler method and RNG k–ε turbulence model were used to optimize process parameters and clarify the formation mechanism of ultra-smooth tooth surfaces. Experimental results for spiral bevel gears show that the proposed immersed CMP process effectively improves surface quality. The tooth profile roughness was reduced from Ra 1.531 μm to 0.509 μm, and surface scratches were significantly alleviated. These results confirm the feasibility and effectiveness of the proposed process. This study provides a reliable approach for efficient and precision polishing of complex-structured gears and extends the application of CMP technology to non-planar mechanical components. Full article

Coronary artery vasospasm (CAV) is a transient, reversible constriction of the epicardial coronary arteries that reduces coronary blood flow and may cause myocardial ischemia. Despite its clinical significance, CAV remains underdiagnosed and can present as chest pain, acute coronary syndrome, malignant arrhythmias or sudden cardiac death. Vasospasm may occur in both angiographically normal coronary arteries and at sites of pre-existing atherosclerotic stenosis. The pathophysiology of CAV is multifactorial and involves vascular smooth muscle cells (VSMCs) hyperreactivity, endothelial dysfunction, chronic inflammation and autonomic dysregulation. VSMCs contraction is mediated by phosphorylation of the myosin light chain (MLC) through calcium (Ca²⁺)/calmodulin-dependent myosin light chain kinase (MLCK), while relaxation is regulated by myosin light chain phosphatase (MLCP). Increased intracellular Ca²⁺ levels and enhanced Ca²⁺ sensitivity contribute to excessive vasoconstriction. Rho-kinase (ROCK) plays a pivotal role in sustained vasospasm by inhibiting MLCP, thereby promoting prolonged smooth muscle contraction. Endothelial dysfunction contributes to CAV by disrupting normal vascular tone regulation, largely as a result of decreased nitric oxide (NO) mediated vasodilation. Chronic low-grade inflammation and oxidative stress exacerbate both endothelial dysfunction and VSMCs contraction. Understanding these molecular mechanisms is essential for identifying novel therapeutic targets. Emerging treatment strategies, including ROCK inhibitors, endothelin receptor antagonists and anti-inflammatory agents, may improve outcomes in patients with refractory CAV. Full article

Sodium butyrate (NaBu), a short-chain fatty acid and histone deacetylase inhibitor, has been reported to influence protein acetylation and cellular function; however, its effects on boar spermatozoa remain poorly understood. This study evaluated the effects of NaBu on sperm function and global protein acetylation in fresh after 24 h storage and frozen–thawed boar spermatozoa. Semen samples collected from boars (n = 4), with three ejaculates per boar, were supplemented with 0, 0.5, 0.75, or 1 mM NaBu, stored for 24 h at 17 °C, and subsequently cryopreserved. Sperm motility, mitochondrial membrane potential, membrane integrity, apoptosis-like changes, and chromatin status were assessed using CASA, flow cytometry, and fluorescence microscopy, whereas global protein acetylation was assessed by Western blotting. In fresh semen after 24 h storage, NaBu did not significantly affect the evaluated sperm functional parameters, whereas frozen–thawed spermatozoa showed significant changes in selected functional parameters, particularly total and progressive motility at 0.5 mM. Selected mitochondrial membrane potential parameters were also affected in frozen–thawed samples, while membrane integrity, apoptosis-like changes, and chromatin status remained largely unaffected. NaBu did not significantly alter global protein acetylation levels in either fresh after 24 h storage or frozen–thawed spermatozoa. Considerable inter-individual variability between boars was observed. These findings indicate that NaBu may affect selected in vitro functional properties of frozen–thawed boar spermatozoa; however, the observed functional changes were not associated with detectable statistically significant changes in global protein acetylation under the conditions tested. Further studies are needed to determine whether specific acetylated proteins, metabolic pathways, or stress-response mechanisms are involved. Full article

This paper advances pump energy optimization by shifting the analytical focus from nominal efficiency to energy-optimal operating areas derived directly from in-field measurements. A structured experimental methodology is presented for reconstructing pump performance under real hydraulic and electrical conditions using existing systems and variable frequency drives. High-resolution datasets obtained from in-field testing are densified and normalized to map the operational area of pumps across flow, head, and rotational speed. The Best Electricity Use Point (BEUP) is identified as an energy-optimal area rather than a single operating point, accounting for system-level losses. Application to a municipal water supply pumping station on Kos Island (Greece) demonstrates that real operating behavior deviates substantially from manufacturer specifications and that BEUP-oriented control enables systematic reductions in energy consumption while improving hydraulic stability and mechanical stress conditions. The proposed framework supports a transition from static efficiency concepts to adaptive, measurement-driven pump operation. Full article

This article proposes a gas-only continuation framework for steady-state loadability analysis in natural gas transmission networks based on a direction-free reformulation of the General Flow Equation (GFE). The proposed formulation introduces signed pipe flows directly as state variables, thereby representing bidirectionality intrinsically. As a result, flow reversals are handled without switching logic, while the branch geometry and criticality mechanism of the underlying gas-network equilibrium map are preserved. On this basis, a Gas Continuation Method (GCM) is developed to trace equilibrium branches directly in native gas-load space under specified gas-load stress. The method distinguishes the last admissible operating point from the mathematical critical point and incorporates a formal diagnosis to determine whether the detected limiting condition is consistent with a Saddle-Node Bifurcation (SNB). The proposed framework is validated on a three-node benchmark, a realistic Belgian gas transmission network, and a 40-node test system. The results show accurate agreement with Newton–Raphson (NR) solutions in the regular operating regime, robust branch tracing near limiting conditions where standalone NR loses convergence, and consistent handling of signed pipe flows under load-induced flow reversal and under algebraic orientations assigned a priori opposite to the solved physical flow. The Belgian and 40-node cases further show that the operational admissibility limit may precede the mathematical critical point, so pressure-based feasibility and branch-level criticality emerge as related but distinct notions. These features make the proposed methodology a rigorous and practical tool for identifying admissibility limits, interpreting critical behavior, and assessing loadability margins in gas transmission networks. Full article

The constitutive analysis model and hot processing map of the ZM6 alloy across various deformation conditions were investigated during hot compression experiments. True stress-strain curves within 300–450 °C and 0.0001–0.1 s⁻¹ were obtained from compression tests on a Gleeble-1500 platform. The results showed that higher strain rates (e.g., 0.1 s⁻¹) induced pronounced work hardening, whereas high temperatures (300–400 °C) combined with low strain rates (10⁻⁴ s⁻¹) promoted conditions conducive to dynamic recrystallization (DRX), leading to a softening tendency of steady-state flow stress. Additionally, a modified strain-compensated constitutive model was built for flow stress prediction. Material constants were plotted as fifth-order polynomial functions of strain (0.025–0.80) for precise stress predictions. The derived activation energy (Q = 182.38 kJ/mol) falls within the typical range for Mg-RE alloys. Leave-one-temperature-out cross-validation showed average AARE values of 7.2–9.8%, demonstrating the model’s interpolation capability and its sensitivity to extrapolation. Cross-validation within the training dataset showed reasonable consistency between experimental and predicted stresses (R > 0.997, AARE < 4.35%). Using the dynamic materials model, hot processing maps identified safe deformation zones and instability zones of the ZM6 alloy. Flow instability was observed at strain rates >0.01 s⁻¹, particularly at low temperatures (300–350 °C). Optimal processing windows appeared in high-energy dissipation (η > 30%) regions, e.g., 400–450 °C/10⁻⁴–10⁻³ s⁻¹. Optical microscopy confirmed that at high temperatures (≥400 °C) and low strain rates (≤0.001 s⁻¹), a uniform, fine-grained, fully recrystallized structure can be obtained, whereas low temperatures (350 °C) and high strain rates (0.1 s⁻¹) produce coarse elongated grains with limited DRX, consistent with the instability regime predicted by the processing maps. Under intermediate conditions (e.g., 400 °C, 0.01 s⁻¹), a bimodal grain distribution indicates incomplete recrystallization. Although EBSD analysis was not performed in this study, the optical microstructures directly validate the predicted safe and unstable windows. Together, all these findings provide preliminary model-based guidance for optimizing hot working parameters to balance microstructural stability and processing efficiency. Full article

Background: Low-flow, low-gradient aortic stenosis with reduced left ventricular ejection fraction is a heterogeneous condition with challenging severity assessment. Aortic valve calcification reflects fibro-calcific remodeling, while oxidative stress plays a key role in its pathogenesis. Serum uric acid, a marker of oxidative stress, may be associated with valvular calcification. This study investigated the relationship between serum uric acid levels and aortic valve calcification in this population. Methods: This retrospective study included 85 patients. Aortic valve calcification was quantified using computed tomography with the Agatston method, and patients were categorized as true severe or pseudo-severe according to sex-specific calcium thresholds. Of the patients, 57 were classified as true severe and 28 as pseudo-severe aortic stenosis. Results: Patients with higher calcification burden had significantly elevated serum uric acid levels (6.77 ± 1.57 vs. 5.08 ± 1.10 mg/dL, p < 0.001). Serum uric acid showed a modest correlation with aortic valve calcium score (ρ = 0.339, p = 0.002) and remained independently associated with CT-defined true severe low-flow, low-gradient aortic stenosis in multivariable analysis. ROC analysis yielded an area under the curve of 0.823 and identified a serum uric acid threshold of 5.45 mg/dL associated with a greater likelihood of CT-defined true severe low-flow, low-gradient aortic stenosis. Conclusions: Serum uric acid is associated with CT-derived aortic valve calcification and may provide insight into underlying fibro-calcific remodeling in this population. Full article

Dense granular materials under low confining stress and low shear velocity—conditions relevant to low-pressure powder handling, near-surface transport, and the upper layers of stored bulk solids—remain insufficiently characterized at the microstructural level. We perform three-dimensional discrete element method (DEM) simulations of annular shear of monodisperse glass spheres at σ = 1 kPa and v = 0.01 m/s, corresponding to an inertial number I ≈ 1.06 × 10⁻³ at the quasi-static limit of the dense flow regime. The steady-state friction coefficient stabilizes at μ_ss ≈ 0.78, consistent with the quasi-static limit of the μ(I) framework. The solid volume fraction decreases monotonically from φ ≈ 0.50 at the base to φ ≈ 0.35 near the top, while the tangential velocity decays exponentially with depth (decay length δ_s ≈ 10 mm). Particle trajectory tracking reveals a sharp kinematic transition near z ≈ 5–6 mm separating a quasi-rigid basal layer (z ≲ 5 mm) from an upper shear-active zone (z ≳ 6 mm). The contact force distribution follows an exponential decay P($f$/$⟨f⟩$) ∝ exp(−β·$f$/$⟨f⟩$) with β ≈ 0.45, with strong force chains selectively concentrated in the upper zone. Together, these four microstructural descriptors co-locate within a single transition band, providing quantitative benchmarks for material characterization and constitutive modelling at the lower boundary of dense flow. Full article

Chronic coronary syndromes (CCSs) are increasingly recognized as complex immunometabolic vascular disorders in which coronary microvascular dysfunction (CMD), persistent low-grade inflammation, oxidative stress, and maladaptive cellular remodeling contribute to ischemic symptoms and adverse outcomes beyond epicardial stenosis. CMD represents a heterogeneous condition comprising both functional and structural endotypes and constitutes a major determinant of myocardial ischemia, heart failure progression, and adverse cardiovascular outcomes, even in the absence of obstructive coronary artery disease. Emerging evidence indicates that immunometabolic reprogramming of endothelial cells, vascular smooth muscle cells, and immune cells sustains microvascular dysfunction in CCSs. Metabolic shifts toward glycolysis, mitochondrial dysfunction, redox imbalance, and dysregulated lipid metabolism promote chronic inflammatory activation within the coronary microenvironment. Convergent mitochondrial stress (including NAD⁺ decline) and redox injury promote endothelial senescence and increase susceptibility to regulated cell death, progressively limiting vasodilatory reserve and predisposing to microvascular rarefaction. Pyroptosis and ferroptosis-like lipid peroxidation further exacerbate endothelial barrier disruption and inflammatory amplification. In parallel, inflammasome activation, iron-dependent lipid peroxidation, impaired autophagy, and endoplasmic reticulum stress form interconnected molecular networks that amplify vascular injury through self-reinforcing mechanisms. This narrative review integrates mechanistic and translational evidence linking immunometabolic dysregulation, mitochondrial stress, thromboinflammatory signaling, endothelial senescence, and regulated cell death to distinct CMD endotypes. We propose a systems-level framework in which coronary microvascular dysfunction is conceptualized as an immunometabolic vascular network disorder, with reduced coronary flow reserve (CFR)—often termed myocardial flow reserve (MFR) in PET studies—emerging as the integrative functional endpoint of these interacting molecular perturbations and a robust predictor of major cardiovascular events. Full article