Search Results (2,435)

Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycemia, and the diaphragm—the primary respiratory muscle—is adversely affected by this diabetic process. The aim of this study is to investigate the effects of zinc sulfate (ZnSO₄) treatment on diaphragm muscle contractile dynamics, calcium homeostasis, apoptosis, and fibrosis in an 18-month-old female Type 2 diabetic rat model. Thirty-two 18-month-old female Wistar rats were randomly divided into four groups: Control (CON), CON + ZnSO₄, Diabetes Mellitus (DM), and DM + ZnSO₄. The DM model was induced by a high-fat diet and administration of 30 mg/kg streptozotocin (STZ); after the disease was confirmed, ZnSO₄ was administered intraperitoneally at a daily dose of 10 mg/kg to the treatment groups. The mechanical functions of the diaphragm muscle were evaluated using a post-rest potentiation protocol in an isolated organ bath; qPCR analyses (Caspase-3, TGF-β1, SERCA 2a) were performed to investigate cellular apoptosis, fibrosis, and calcium regulation. Compared with the CON group, the DM group exhibited a severe ~90% reduction in diaphragmatic contraction force (CF) and a ~97% decline in maximal contraction/relaxation velocities (±dF/dt_max) (p < 0.0001), which strongly correlated with a 30% suppression of SERCA2a gene expression (p < 0.01). Concomitantly, apoptotic Caspase-3 (~2.6-fold) and profibrotic TGF-β1 (~3.1-fold) mRNA levels were significantly elevated (p < 0.0001). In the DM + ZnSO₄ group, daily zinc treatment (10 mg/kg/day, i.p. for 6 weeks, initiated 4 weeks after diabetes confirmation) did not reverse the elevated Caspase-3 and TGF-β1 expressions (p > 0.05). However, SERCA2a expression was fully preserved back to control levels (p < 0.05 vs. DM), leading to a substantial ~3-fold improvement in CF and velocities (p < 0.05 to p < 0.0001 vs. DM). On the other hand, the healthy CON + ZnSO₄ group exhibited a physiological slowing of contractility (~53% decrease in CF), without histological damage, likely due to a competitive antagonism between excess divalent zinc (Zn²⁺) and calcium (Ca²⁺) on myofilaments. Although zinc cannot reverse the structural apoptotic and fibrotic remodeling in the aged diabetic diaphragm, it successfully rescues functional contractility by preserving SERCA2a transcriptional expression. Full article

Inefficient xanthate transport and poorly defined circulation paths can limit the conditioning of low-grade lead–zinc tailings. A Venturi-assisted composite conditioning tank was therefore evaluated using ANSYS Fluent 2025 R2 (Ansys Inc., Canonsburg, PA, USA). The volume of fluid (VOF) model described the air–slurry free surface, the renormalization group (RNG) k–ε model and multiple reference frame (MRF) approach represented the impeller-induced mean flow, and a transient user-defined scalar (UDS) described the transport of a generic normalized xanthate tracer. The slurry phase was represented as a generic homogeneous equivalent medium rather than as a fully characterized solid–liquid suspension. The Venturi throat generated a local low-pressure region and stable reagent suction; at a tailings inlet velocity of 2.50 m·s⁻¹, the reagent-branch inlet mass flow rate was 2.825 × 10⁻⁴ kg·s⁻¹. Parameter comparisons identified 350 r·min⁻¹, an impeller installation height of 370 mm, and an annular gap width of 60 mm as the preferred combination. The calculated impeller power increased from 0.211 kW at 200 r·min⁻¹ to 2.304 kW at 400 r·min⁻¹. Increasing the speed from 350 to 400 r·min⁻¹ raised power consumption by 60.9% but average velocity by only 5.8%. Compared with a conventional tank, the composite tank formed a coherent impeller–lower connecting–annular upflow–upper recirculation pathway, providing more favorable hydrodynamic conditions for xanthate transport and potential reagent–particle contact. Full article

Bearing-grade PEEK composites are intended to improve sliding performance, but filler addition does not necessarily reduce friction. This study compared the dry sliding tribological behaviour of neat PEEK and hybrid PEEK containing PTFE, graphite, and carbon fibre against 42CrMo4+QT steel. Ring-on-block tests were performed at nominal PV values of 0.3–3.2 MPa·m/s, contact pressures of 0.87–5.82 MPa, and sliding velocities of 0.26–0.55 m/s. Each material–condition combination was tested using three independent specimens. Coefficient of friction was calculated from simultaneously measured tangential and normal forces, and subsurface temperature was recorded continuously. Initial and post-test surfaces were examined using optical and extended depth-of-field microscopy. Group mean COF values ranged from 0.052 to 0.123. Hybrid PEEK exhibited a higher numerical mean COF than neat PEEK in all six operating conditions, with relative differences of approximately 1.53–8.36%. Two-factor ANOVA estimated an overall hybrid-minus-neat difference of +0.003388 COF units (95% CI 0.001279–0.005496; p = 0.0029), whereas none of the six condition-specific neat–hybrid comparisons was significant after Holm correction. Initial temperature, maximum temperature, and baseline-normalised temperature rise were reported for every specimen and treated descriptively. Both materials reached stable sliding states without seizure or uncontrolled thermal escalation. Post-test EDF observations showed a denser pattern of fine grooves on neat PEEK, whereas hybrid PEEK exhibited comparatively smoother intervening regions interrupted by fewer but locally deeper features. Mass changes remained close to the capability of the applied balance and did not permit quantitative wear-rate comparison. The results show that the investigated hybrid formulation did not provide a dry-friction reduction advantage over neat PEEK under the tested conditions. Full article

Relative age effect (RAE) and biological maturation can significantly impact athlete selection. This study examined the presence of RAE in youth team invasion sports and assessed whether the timing of maturity influences body size and lower-body explosive strength. Athletes were grouped by age category (U14, U16, U18), and the distribution of birth quartiles was analyzed. Maturity timing was estimated using age at peak height velocity (APHV), and lower-body explosive strength was evaluated through jumping performance. Comparisons across age groups showed progressive increases in body size and jumping performance with advancing age, consistent with pubertal changes in fat-free mass and neuromuscular function. The birthdate distribution indicated an overrepresentation of relatively older athletes (U16 and U18), suggesting that selection bias may intensify with age around the pubertal window. Regression analyses showed that earlier APHV was significantly associated with greater body size after controlling for chronological age (CA) (p ≤ 0.01), although CA remained the strongest predictor. In contrast, APHV did not significantly explain additional variance in jumping performance, suggesting that anthropometrics, training exposure, and movement technique likely contributed. The current findings underscore the role of biological maturation in body size and the need for youth sport systems to include structured strength and conditioning programs that optimize lower-body muscle power. Full article

This paper presents a mathematical model to investigate how waves and currents interact with a flexible perforated floating membrane in finite water depth within the framework of linear wave theory. The perforated flexible membrane is modeled based on Darcy’s law and the one-dimensional string equation. The complex dispersion relation in the presence of current velocity is derived from the Green’s function technique using a fundamental source potential solution. The dispersion curve is analyzed by comparing the phase and group velocities for different water depths. Further, a physical model associated with the effect of current on a moored finite floating perforated flexible membrane integrated with a vertical wall is formulated. Then, the theoretical solution of a physical boundary value problem near a vertical rigid wall is obtained using the matching technique and the roots of the dispersion relation derived from the Green’s function technique. Numerical simulations are provided to verify the convergence of the series solution and the accuracy of the obtained analytical findings are evaluated against previously published analytical and experimental datasets. Further, several numerical results on the membrane deflection, hydrodynamic coefficients, and horizontal force on the wall for various structural parameters, mooring stiffness, and current velocities are analyzed. It is observed that the present analysis with this perforated membrane breakwater will be helpful to coastal and marine engineers to understand the influence of current velocity. Full article

The rapid advancement of autonomous driving technologies makes the effective coordination of vehicle groups a critical requirement for ensuring both safety and efficiency in smart urban environments. Although individual autonomous vehicles may operate correctly in isolation, their collective behavior can still lead to emergent issues such as deadlocks or collisions arising from complex inter-vehicle interactions. To address this challenge, we propose a hybrid automaton-based control framework for autonomous vehicle groups that integrates both normal and emergency operational modes to jointly guarantee safety and performance. In this paper, we present the formal specification and verification of the proposed system using rewriting logic and the Maude tool. Our main contributions are threefold: (1) the construction of detailed hybrid automata models that capture vehicle dynamics and decision-making; (2) the development of formal specifications in Maude from these models; and (3) the systematic verification of key system properties, including core safety invariants, such as collision avoidance, obstacle stopping, and velocity bounds. The verification results demonstrate that the proposed model consistently upholds safety conditions, ensures that vehicles come to a safe stop before encountering obstacles, and effectively prevents collisions within the group. Full article

El Niño–Southern Oscillation (ENSO) modulates tropical South American rainfall, but its Colombian expression is filtered by terrain, rainfall regime, moisture pathways, and atmospheric state. We quantify ENSO-related sensitivity of standardized precipitation anomalies in the Colombian Andes and Orinoquia using Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS v2.0; 1981–February 2026), station records from Colombia’s Institute of Hydrology, Meteorology, and Environmental Studies (IDEAM), ERA5 atmospheric fields, and 1981–2010 climatologies. CHIRPS reproduced station-derived standardized anomalies ($r=0.94$ in the Andes; $r=0.91$ in Orinoquia), supporting regional anomaly analysis while retaining cautious comparison framing. Lagged associations with the Oceanic Niño Index (ONI) were evaluated for lags 0–6 months using effective sample size, block-bootstrap confidence intervals, and maximum-lag tests. ENSO sensitivity was stronger and more coherent in the Andes: annual lag-1 ONI–precipitation correlation was $-0.374$, with marked December–February and June–August responses. El Niño minus La Niña composites of column water vapor, 850-hPa moisture-flux convergence, 500-hPa vertical velocity, and Convective Available Potential Energy (CAPE) revealed seasonally heterogeneous moisture and convergence responses, but coherent positive $\omega$ anomalies over the Andes in DJF and JJA, consistent with reduced ascent. CAPE was significantly higher in MAM–SON, whereas the positive DJF difference was not statistically significant, showing that thermodynamic instability alone did not determine rainfall. Orinoquia did not exhibit a comparably consistent four-variable atmospheric signature. An elevation-stratified analysis showed a modest lowland-to-upland strengthening that plateaued above approximately 1000 m. A strictly antecedent ONI-lag model retained modest fixed-split skill in the Andes ($R^2=0.138$) but negligible skill in Orinoquia ($R^2=0.003$). The results support regional diagnosis, not causal or operational claims. Full article

To address the challenges associated with operational ventilation in high-altitude tunnels, this study investigates the distribution patterns of ventilation flow fields and optimizes the spatial layout parameters of jet fans to determine the most effective configuration. Using a case study from the Zhuohe Expressway tunnel, numerical simulations were conducted to analyze four key design parameters: the lateral clear distance (L) between two jet fans in a single group, the vertical distance (H) from the fan center to the tunnel lining, the axial distance (T) from the fan to the tunnel entrance, and the longitudinal spacing (S) between two groups of fans. The results indicate that for a single-fan group, when the parameter L is 1.25D (D is the fan diameter), pressure rise and comprehensive influence coefficients reach peak values of 20.090 Pa and 0.886, respectively. As well as the parameter H between 1.20 m and 1.25 m, the diffusion of the vertical wind field velocity is continuously reduced due to the constraint of the tunnel lining on Section BB of the tunnel fan’s symmetry axis, and the interference of the tunnel lining on the stable flow state of the fan’s outlet airflow is relatively small. Moreover, parameter T has a relatively low sensitivity impact on the increase in pressure and the variation of the influence coefficient. When the parameter T is within the range of 50 m to 100 m, the airflow at the entrance of the tunnel is smoothly connected with the airflow at the suction section of the fan. Additionally, the pressure rise and the influence coefficient increase by the parameter T. Both the fan’s pressure rise and the influence coefficient reach their maximum values when the parameter T is 100 m. Furthermore, in the case of two-fan groups, the gas is fully mixed in the tunnel when the parameter S is 150 m, and the fan pressure rise and the influence coefficient increase as well as parameter S. The gas between the two sets of fans has been fully mixed in the parameter S at 175 m, and the pressure rise and the coefficient influence reach their maximum values of 40.231 Pa and 0.887, respectively. In light of these findings, the following optimal parameters ranges are recommended for similar tunnel ventilation designs: parameter L is 1.25D for two jet fans within a single group, parameter H is between 1.20 m and 1.25 m, parameter T is 100 m from the tunnel entrance, and parameter S is between 150 m and 175 m for two groups of fans. Full article

In the mining process of shallow-buried and close-distance coal seam groups in western China, the interconnected collapse fractures between the overlying goaf and the surface form large-area composite goafs, which aggravate surface air leakage and elevate oxygen levels within the goaf. This, in turn, leads to hazardous conditions such as CO over-limits and O₂ deficiency at the working face’s return air corner, which seriously threatens the respiratory health of underground operators and the safe production of mines. Taking the 104 working face of a coal mine in Shenfu-Dongsheng Mining Area as the engineering background, this paper comprehensively adopts SF₆ tracer gas test, fuzzy cluster analysis, and CFD numerical simulation methods to systematically study the distribution characteristics of three-dimensional air leakage channels in composite goafs and their influence mechanism on gas migration in goafs, and proposes a dynamic pressure equalization ventilation (PEV) regulation technology system. The research results show that a multi-dimensional three-dimensional air leakage channel of “surface-interlayer-own layer-roadway” exists in the research area, in which the surface fracture air leakage velocity is about 0.068 m/s, and the interlayer and internal goaf air leakage velocity is about 0.384 m/s. The atmospheric pressure difference between the working face and the surface is the main controlling factor inducing the O₂ deficiency disaster of the working face. Every 100 Pa change in atmospheric pressure difference causes an O₂ concentration fluctuation of about 0.30% at the return air corner, and the critical pressure difference for activating PEV is determined to be 300 Pa. Setting the PEV regulation point at the return air outlet of the working face and adopting the combined dynamic regulation system of fans and air windows can realize accurate pressure balance between the working face and the overlying composite goaf. Full article

To address the broadband noise distribution, complex excitation sources, and insufficient low-frequency attenuation of conventional porous acoustic packages in commercial vehicle cabs, this study proposes a PU–six-cavity Helmholtz metamaterial composite acoustic package for broadband noise reduction. The proposed structure consists of a 30 mm PU porous layer for mid-to-high-frequency dissipation and a 30 mm six-cavity Helmholtz metamaterial layer for low-frequency absorption, forming a 60 mm composite acoustic package. A full-vehicle acoustic model of a commercial vehicle cab was established in VA One to identify the A-weighted sound pressure level (SPL) spectrum at the driver position. The results show that the PU porous acoustic package improves the mid- and high-frequency noise response, whereas pronounced peaks remain in the low- and low-to-mid-frequency ranges. To enhance these bands, the six sub-cavities of the Helmholtz metamaterial were tuned to 200, 250, 315, 400, 500, and 630 Hz through spatial partitioning and cavity grouping. COMSOL (version 6.1) simulations and particle velocity distributions confirmed the multi-peak absorption mechanism and the selective excitation of the corresponding sub-cavities. The composite structure was further validated through impedance-tube measurements, full-vehicle acoustic simulations, and in-vehicle tests. The VA One simulation shows that the total A-weighted SPL at the driver position decreases from 68.25 dB for the PU porous package to 66.01 dB after introducing the six-cavity Helmholtz metamaterial, corresponding to an additional reduction of 2.24 dB. A preliminary in-vehicle test under a stationary idling condition shows that the total A-weighted SPL near the driver’s ear decreases from 55.83 dB(A) to 54.56 dB(A). These results demonstrate that the proposed PU–six-cavity Helmholtz metamaterial composite acoustic package combines broadband porous dissipation with low-frequency resonant absorption, providing a feasible solution for broadband noise control in commercial vehicle cabs. Full article

Second- and third-order elastic constants (SOEs and TOEs) are essential parameters for characterizing the nonlinear elastic behavior of metallic materials. However, their determination in small-diameter slender rods remains challenging due to the stringent requirements of existing bulk-wave acoustoelastic and resonant ultrasound methods on the specimen dimensions and measurement conditions. This study proposes a two-stage guided-wave acoustoelastic inversion method for identifying the second- and third-order elastic constants of isotropic metallic rods. A high-accuracy forward model based on the wave finite element (WFE) method is developed to calculate the L(0,1) guided-wave dispersion and acoustoelastic responses under different combinations of elastic constants and uniaxial prestress. The sensitivity characteristics of group velocity dispersion and acoustoelastic coefficients are systematically investigated to provide a basis for objective function construction and test frequency selection. A surrogate-assisted Covariance Matrix Adaptation Evolution Strategy (CMA-ES) is employed to solve the resulting ill-conditioned and non-separable inversion problem. Numerical validations demonstrate that the proposed method can accurately recover both SOEs and TOEs while substantially reducing the computational cost of iterative inversion. Full article

High-purity SiC powder is an important feedstock for SiC crystal growth, but thermal-field regulation becomes difficult during large-batch synthesis. This study examined an α-SiC powder-synthesis furnace with upper and lower induction-coil groups through numerical simulations and 70 kg synthesis experiments. A representative two-dimensional axisymmetric model was used to compare eight cases with different coil-turn or numerical power allocations. Redistributing the coil turns changed $E_1$, $E_2$, volumetric Joule heat density, $Q$, and the resulting temperature and calculated gas-phase velocity-magnitude fields. From C01 to C04, the maximum calculated temperature decreased from 2501.10 to 2359.13 K, while $\Delta T$ decreased from 242.57 to 76.20 K. Increasing the upper-coil numerical power raised the temperature level while reducing $\Delta T$ to 152.41 K. Increasing the lower-coil numerical power also raised the temperature level, but increased $\Delta T$ to 292.26 K. Equal-total-power comparisons showed that axial power allocation affected $T_{\mathrm{m}\mathrm{a}\mathrm{x}}$ and $\Delta T$. XRD identified 6H-SiC as the detected crystalline phase in both analyzed middle-region specimens, although X-ray-amorphous carbon could not be excluded. The specimens also differed in macroscopic appearance, measured impurity concentrations, and local nitrogen concentration profiles. Because the experimental conditions were maintained nominally unchanged except for the upper-coil current, these specimen-level differences may be associated with altered internal thermal conditions. Such changes may affect local equilibrium, supersaturation, and species transport, providing a possible link to the observed material differences. The numerical results identify coil-turn allocation and axial power allocation as variables for regulating the calculated furnace fields. Full article

Clarifying the dynamic mechanism of rock pillar fracture and its rock burst-inducing mechanism is fundamental for the prevention and control of rock burst disasters in steeply inclined extra-thick coal seam groups. In this study, field monitoring, theoretical analysis, and numerical simulation were combined to investigate the rebound vibration behavior and rock burst-inducing mechanism of fractured rock pillars, and corresponding mitigation measures for rock pillar-induced rock bursts were proposed. The results indicate that instantaneous rock pillar fracture induces reciprocating rebound vibration behavior within the coal seam rock pillar, causing the velocity, displacement, and strain energy density of the rock pillar to remain in a persistent fluctuation state. Meanwhile, periodic mutual conversion between strain energy and kinetic energy occurs throughout the vibration process. During any vibration cycle, the rock pillar cannot recover to its initial equilibrium position, resulting in a sharp increase in the loads acting on the floor side of the B3–6 coal seam and a significant decrease in the loads acting on the roof side of the B1–2 coal seam. Consequently, the B3–6 coal seam remains subjected to transient dynamic loading, whereas the B1–2 coal seam experiences transient unloading after rock pillar fracture. This asymmetric transient loading mechanism is identified as the intrinsic reason for the higher rock burst proneness of the B3–6 coal seam. Based on the dynamic response characteristics of the stope coal rock system, staggered-level mining of the B1–2 and B3–6 coal seams and slotting presplitting in the B3 roadway were proposed as mitigation measures for rock pillar-induced rock bursts. When the stagger distance of the working face increases from 25 m to 100 m, the stress drop of the B3–6 coal seam is 22.9%~28.7%. When the slotting depth of the rock pillar increases from 25 m to 80 m, the stress of the B3–6 coal seam decreases by 9.88%~24.1%. These findings provide theoretical support and engineering guidance for rock burst prevention and control in steeply inclined coal seam. Full article

Background: Women’s cricket is rapidly expanding at the elite youth level, yet limited research has comprehensively examined the physical, positional, and developmental characteristics underpinning performance in elite under-19 (U19) female players. In particular, the role of biological maturation and relative age effects in shaping physical performance within this population remains poorly understood. Objective: This study aimed to characterise the anthropometric and physical profile of elite U19 female cricketers, examine positional differences, assess the presence of relative age effects (RAE), and evaluate the applicability of maturity offset estimation in this cohort. Methods: Ninety elite U19 female cricketers representing six regional high school teams were assessed using a cross-sectional design. Anthropometric measures, strength, power, sprint performance, and agility were evaluated. Maturity status was estimated using both the original and modified maturity offset equations, and birth quartiles were used to assess RAE via a chi-squared test. Between-group differences were analysed using ANOVA. Results: Statistically significant positional differences were observed for vertical jump, isometric strength, and sprint performance (p < 0.05), with spin bowlers demonstrating lower power and slower sprint times, and seam bowlers exhibiting greater maximal strength. No differences were observed in anthropometry or agility. Birth quartile distribution was relatively uniform, indicating no clear RAE. Maturity offset estimates indicated that players were well beyond peak height velocity; however, both original and modified estimates demonstrated limited variability and a tendency to overestimate maturity timing in this cohort. Conclusions: Elite U19 female cricketers demonstrate role-specific physical profiles driven primarily by strength, power, and speed rather than anthropometry or maturity status. The absence of a clear RAE and limited applicability of maturity offset methods highlight the need for performance-based, position-specific approaches to training and talent identification in female cricket. Full article

Background/Objectives: Angiogenesis plays a central role in the progression of cervical intraepithelial neoplasia (CIN) to cervical cancer (CC). Transvaginal Doppler ultrasonography (TVDUSG) offers a non-invasive means of assessing hemodynamic changes associated with neoplastic transformation. This study aimed to evaluate the diagnostic performance of uterine artery (UA) Doppler parameters across the full cervical disease spectrum and their associations with adverse prognostic features and clinicopathological features in CC. Methods: This prospective observational cohort study enrolled 170 patients who were divided into four groups: controls, CIN 1, CIN 2–3, and CC. All underwent TVDUSG prior to treatment. Pulsatility index (PI), resistance index (RI), peak systolic velocity (PS), end-diastolic velocity (ED), PS/ED ratio, ED/PS ratio, and time-averaged maximum velocity were recorded. ROC curve analysis was performed to assess diagnostic performance. Results: PI and RI increased progressively from controls to CC, while ED declined across groups (all p < 0.001). In patients with CC, PI correlated with tumor volume and was elevated in those with advanced-stage, parametrial and lymph node involvement (all p < 0.001). ROC analysis revealed strong diagnostic performance for PI in distinguishing CC from controls (AUC = 0.861, sensitivity 80.0%, specificity 80.4%); however, PI showed limited ability to distinguish cervical cancer specifically from high-grade CIN (AUC = 0.593). Conclusions: UA Doppler parameters, particularly PI, are associated with cervical neoplastic severity and adverse prognostic features in CC. TVDUSG may serve as a practical, non-invasive adjunct in the preoperative evaluation of cervical neoplasia, especially where advanced imaging is unavailable. Full article