Search Results (4,880)

With the development of shipping to harsh marine environment, it is very important to understand the transient behavior of a marine diesel engine in high sea conditions. Wave-induced hull motion will lead to severe load fluctuations and air-fuel ratio imbalance. In this study, an integrated simulation platform coupled with environmental loads, hull dynamics, propeller characteristics and a high-fidelity thermodynamic engine model was constructed to explore the response characteristics of the propulsion system. The model integrates a zero-dimensional multi-zone combustion method, turbocharger dynamic characteristics and an incremental PID governor, and has been verified based on the bench test data of TBD234V12 diesel engine and the 20 m Wigley standard ship. The simulation results under the sea conditions from level 7 to 9 show that the transient load has a nonlinear amplification effect. Specifically, from sea state 7 to sea state 9, the engine load fluctuation range expands by 2.0 times, while the main peak amplitude of speed fluctuation increases by 3.7 times. Furthermore, the peak exhaust pressure rises by 1.8 times, and the exhaust temperature fluctuation amplitude broadens by 35%. Frequency domain analysis further identified the low-frequency energy concentration phenomenon in the exhaust pressure spectrum and the precursor characteristics of compressor surge. The research results quantify the deterioration law of thermodynamic stability and mechanical stress under wave disturbance, and provide an important reference for the formulation of an engine robust control strategy and fatigue life assessment under high sea conditions. Full article

This paper presents a numerical assessment of bending-fatigue durability in the tooth root region of cylindrical involute gears. Multiple gear pairs were modelled with different numbers of teeth and varying gear rim thicknesses. The generated geometry was implemented in the ANSYS 2025 R2 software suite, where the maximum normal stresses at critical locations in the tooth root region were determined through numerical simulation. A deformation-based method derived from Socie’s models was applied to estimate the duration of the phase leading up to fatigue crack formation in terms of load cycle accumulation. The gear geometry, together with the generated finite element mesh, was transferred to the FRANC2D/L version 4 software suite, where fatigue crack propagation was numerically simulated. Numerical analysis provided effective stress intensity factors, which then enabled an estimation of the number of load cycles required for an initiated crack to grow to the critical length associated with tooth failure. The total fatigue life in the tooth root region was evaluated as the sum of load cycles in the crack initiation phase and the crack propagation phase up to the critical crack length. The results show that all analysed factors exhibit very high resistance to fatigue fractures in the tooth root region. Furthermore, for gears with a rim thickness ratio greater than 0.7, the fatigue crack propagates through the tooth and reaches the fracture toughness limit of the material (K_Ic), whereas for lower rim thickness ratios, crack propagation occurs through the gear rim itself. Full article

The low-cycle fatigue failure of drive shafts under complex service conditions constitutes a critical issue that undermines the structural integrity and service safety of the transmission system in special vehicles. To improve the prediction accuracy of the low-cycle fatigue life of drive shafts, a low-cycle fatigue life prediction method for the drive shaft that accounts for load effects and strength degradation is proposed. A fatigue life prediction model that accounts for the mean stress effect and fatigue strength degradation is proposed by introducing dynamically degrading fatigue strength into the mean stress-refined SWT (Smith–Watson–Topper) model. A fatigue cumulative damage model that considers load interactions and fatigue strength degradation is also proposed, in which the load ratio is introduced to quantitatively describe the extent of the influence of load interactions on the damage process. Furthermore, the dynamically degrading fatigue strength is incorporated into the M-H (Manson–Halford) model. Finally, the stress–strain responses at the critical locations of the drive shaft are analyzed using the finite element model, and the fatigue life of the drive shaft under the load spectrum is calculated using the improved fatigue life prediction model and the improved fatigue cumulative damage model. The results indicate that the improved life prediction method, which considers load effects and strength degradation, can effectively enhance the accuracy of fatigue life prediction for the drive shaft. Full article

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent global health concern. Although pharmacotherapies such as Resmetirom and semaglutide have recently gained approval by FDA/EMEA, therapeutic options remain limited, necessitating the exploration of novel natural compounds. Our previous research indicated that lycopene exerts protective effects against MASLD; however, its underlying molecular mechanisms remain incompletely understood. The present study aimed to investigate whether lycopene alleviates MASLD by modulating mitophagy, with a focus on the PINK1/Parkin pathway. C57BL/6J mice were fed with high-fat diet for 12 weeks to induce MASLD and daily gavage of lycopene (10/40 mg/kg). In vitro, AML12 cells were treated with lycopene and Mdivi-1 to assess the role of PINK1/Parkin-mediated mitophagy against lipid accumulation, oxidative stress, and apoptosis. The results found that lycopene supplementation significantly ameliorated HFD-induced weight gain, dyslipidemia, hepatic steatosis, pathological liver injury, and elevated serum liver enzymes. It reduced hepatic reactive oxygen species (ROS) overproduction and suppressed the mitochondrial apoptotic pathway, as evidenced by decreased cytochrome c release and caspase cascade activation. Concurrently, lycopene restored ATP levels and mitochondrial membrane potential, improved ultrastructural integrity, and balanced mitochondrial dynamics by downregulating DRP1 and upregulating MFN2 and OPA1. Crucially, lycopene activated PINK1/Parkin-mediated mitophagy, leading to an increased LC3-II/LC3-I ratio and Beclin1 expression, alongside decreased levels of mitochondrial proteins TOM20 and COX IV. In vitro, the lycopene partially reversed the exacerbating effects of Mdivi-1 on lipid accumulation, ROS generation, apoptosis, and the suppression of the PINK1/Parkin pathway. Collectively, lycopene ameliorates MASLD by activating PINK1/Parkin-mediated mitophagy and improving mitochondrial homeostasis, thereby reducing hepatic lipid accumulation and attenuating hepatocyte apoptosis. Full article

15Cr14Co12Mo5Ni2, as a new type of low-carbon high-alloy aviation gear steel, has shown significant application potential in the transmission systems of aero engines due to its excellent high-temperature performance. In this paper, the aviation gear steel 15Cr14Co12Mo5Ni2 was treated by a carburizing and quenching process. The microstructure distributions of the carburized and quenched aviation gear steel at different austenitization temperatures (1020 °C, 1050 °C and 1080 °C) were analyzed by OM, SEM and EBSD. Subsequently, the axial tension–compressive fatigue tests (stress ratio R = −1) were carried out using a high-frequency fatigue testing machine after heat treatment at different austenitization temperatures, and the stress–number of cycles (S-N) curves were obtained by fitting the number of fatigue fracture cycles. The fracture morphologies were observed by SEM and the fracture mechanisms were analyzed. The research results show that the distribution of the microstructure and carbides exhibits gradient characteristics, and the carbide content decreases and the effective carburized layer depth decreases from 0.65 mm to 0.45 mm with increasing austenitization temperature, and the main carbide types are M₂₃C₆ and M₇C₃. The fatigue life of 15Cr14Co12Mo5Ni2 gear steel decreases as the austenitization temperature increases. Within the selected temperature range of 1020 °C, 1050 °C, and 1080 °C in this study, the fitted fatigue strengths at a given fatigue life of 10⁶ cycles are 192 MPa, 183 MPa, and 158 MPa, respectively. No obvious crack initiation site can be directly observed from the fracture morphologies of all specimens. Based on the characteristics of crack propagation, it is inferred that the crack source is located in the core or near-core region, and the cracks propagate outward from the core and the propagation rate accelerates with the increasing austenitization temperature, eventually fracturing in the carburized layer. The fracture mechanism of 15Cr14Co12Mo5Ni2 gear steel at the austenitization temperatures of 1020 °C was a mixed mode of intergranular and cleavage brittle fracture, while at 1050 °C and 1080 °C, it was mainly brittle fracture accompanied by local ductile fracture. Full article

This study evaluated the effects of dietary Elionurus muticus essential oil (EMEO) on growth performance, physiological responses, and resistance to car transport stress in Nile tilapia (Oreochromis niloticus). Fish were fed experimental diets for 60 days and subsequently subjected to 6 h of transport stress. Five diets were tested: 0.00 (control), 0.25, 0.50, 1.00, and 1.50 mL EMEO kg⁻¹, in triplicate (10 fish per 500 L tank; stocking density 0.4 kg L⁻¹). Citral was the major EMEO compound (73.91%). Increasing dietary EMEO levels improved growth performance and reduced the feed conversion ratio. Before transport, EMEO supplementation increased erythrocyte counts and plasma glucose levels, while reducing hematocrit and hepatic aspartate aminotransferase (AST) activity (p < 0.05). After transport, plasma glucose, hematocrit, and hepatic AST values decreased, whereas hepatic glycogen and hemoglobin levels increased with higher EMEO inclusion (p < 0.05). Also, post-transport, EMEO-fed fish showed enhanced intestinal digestive enzyme activity (lipase and amylase) and antioxidant capacity (superoxide dismutase and ferric reducing antioxidant power) but increased protein carbonyl levels. Lipid peroxidation (malondialdehyde) was reduced at intermediate EMEO levels (p < 0.05). Histological analyses indicated no tissue damage and suggested improved liver and intestinal function with increasing EMEO inclusion. Overall, dietary supplementation with 1.00 mL EMEO kg⁻¹ is recommended to enhance growth performance and metabolic adjustment and to improve physiological status to withstand transport stress in Nile tilapia. Full article

In vitro methods rely on costly chemical inputs, such as synthetic nutrients, prompting us to search for sustainable alternatives. This study evaluated wastewater generated from the cigarette butt (CB) recycling process as a potential growth stimulant additive for in vitro plant cultivation. Seeds of Brachiaria ruziziensis Germain & Evrard were sown on agar media containing increasing CB wastewater concentrations from 0 to 25% v/v (CB0 to CB25, respectively) under controlled conditions. Germination was monitored over 10 days, and functional and physiological traits of shoot and root systems were assessed at the end. Responses were concentration-dependent and consistent with hormesis. Low concentrations, particularly CB2, enhanced germination (92.2% vs. ~67% in CB0), shoot elongation (~6 vs. 3.4 cm), and total biomass (~47 vs. ~33 mg fresh weight), while maintaining total chlorophyll and increasing carotenoids (147.8 vs. 103.3 µg g⁻¹ FW) and chlorophyll a/b ratio (2.1 vs. 1.5). Contrarily, higher concentrations (≥CB10) reduced germination (47.6% at CB25), strongly inhibited root growth (0.5 cm at CB25), decreased total biomass (~19 mg at CB25), led to growth disorders, and reduced pigment stability. These inhibitory effects were associated with the accumulation of CB-derived compounds, including high nicotine levels and unbalanced nutrients. At low concentrations, coordinated root aerenchyma formation and modulation of stomatal density indicated anatomical plasticity under mild stress conditions, although their physiological significance remains to be clarified. Overall, CB recycling-derived wastewater can act as an effective growth stimulant for B. ruziziensis in vitro when applied at low concentrations, offering a potential alternative for plant biotechnology while contributing to waste valorization. Full article

Marine invertebrates are characterized by high species diversity, a wide distribution, ease of culture, low cost, short life cycles and high sensitivity to pollutants, which makes them excellent models for observing toxic effects and elucidating underlying mechanisms. This paper reviews representative species from three phyla—Arthropoda, Mollusca, and Echinodermata—under both single emerging contaminant exposure and combined exposure scenarios, and analyzes the reproductive and neurotoxic impacts of these contaminants on marine invertebrates. Neurotoxicity is mediated by several key mechanisms: inhibition of acetylcholinesterase activity; disruption of neurotransmitter balance, oxidative stress; and cellular damage, interference with embryonic neural development and axis specification, and impairment of neural cell differentiation and migration. Reproductive toxicity impairs reproductive development by disrupting endocrine signaling, inducing oxidative stress, downregulating reproduction-related genes and damaging gonadal structure. Studies have shown that, besides environmental factors, contaminant concentration is closely correlated with toxic potency and differing concentration ratios can lead to either antagonistic or synergistic effects in combined toxicity. Current research has largely focused on single or binary contaminant systems, whereas studies on multi-contaminant mixtures and their interactions with multiple environmental factors remain limited. Future research should prioritize combined exposure to multiple contaminants, long-term multigenerational observations and the development of comprehensive ecological risk assessment models and monitoring standards, thereby providing a scientific basis for marine ecological conservation. Full article

Background/Objectives: Sebocytes, the primary cell type in sebaceous glands (SGs), produce a lipid mixture called sebum that is released onto the skin surface and is required for skin homeostasis. The lipid receptor Peroxisome Proliferator-Activated Receptor gamma (PPARγ) regulates sebocyte proliferation and lipid synthesis and is involved in acne development. As inhibition of PPARγ has been shown to reduce insulin-induced lipogenesis and Akt/mTOR signalling in SZ95 sebocytes, we here investigated the effects of PPARγ deletion on lipid homeostasis and autophagic stress responses and how the secretomes affect dermal fibroblasts. Methods: SZ95 sebocytes wildtype (WT) and PPARγ knockout (KO) were shifted to low serum and EGF-deficient conditions permissive for autophagy. Untargeted and targeted HPLC-MS/MS analyses were used to analyze native and oxidized lipids, respectively. Protein levels of LC3I/II and p62 were assessed using immunoblots and immunofluorescence microscopy to investigate the autophagic flux. Dermal fibroblasts were exposed to conditioned media. Results: In low serum culture media, KO SZ95 sebocytes displayed significantly altered levels of 23 lipid classes. We observed a significant increase in ether-linked fatty acids as components of complex lipids and detected elevated levels of phospholipid hydroperoxides and aldehydolipids in the KO sebocytes. KO SZ95 sebocytes failed to show the typical responses to lipoxidative stress, such as elevated p62 crosslinking or inclusion body formation, and had reduced LC3II/I ratios as compared to WT cells. PPARγ KO conditioned media promoted a trend towards an inflammatory fibroblast phenotype. Conclusions: These findings suggest that PPARγ in sebocytes may alter the lipidome, elevate redox stress, and affect the autophagic machinery, which could cause accumulation of oxidized lipids and other potentially harmful compounds in sebocytes. Full article

The rehabilitation of the loggerhead sea turtle, Caretta caretta, involves stressors like handling and confinement. To assess physiological stress responses during rehabilitation, twenty-five C. caretta hospitalized at C.Re.Ta.M. were monitored over a two-month period at three time points (T0, T1, and T2). The cohort included 12 juveniles (CCL: 30.6 ± 5.7 cm) and 13 subadults (CCL: 52.5 ± 10.4 cm). Heterophil/lymphocyte ratios (H/L), corticosterone (CORT), glucose (Glu), creatine kinase (CK), and uric acid (UA) plasma concentrations were assessed. Two-way repeated-measure ANOVA revealed significant time effects on H/L ratio (p < 0.0001), CORT (p < 0.0001), Glu (p = 0.0002), CK (p < 0.0001), and UA (p < 0.05), with a significative group x time interaction observed for CK (p = 0.016), CORT (p = 0.006) and UA (p = 0.035). No group effect was observed in any of the data. In the juvenile group, H/L (p < 0.01) and CORT (p < 0.001) were significantly lower at T2 compared to T0. At the T0 point, CORT levels were significantly higher in juveniles compared to the subadult group. In subadults, significant decreases in H/L ratio (p < 0.001), Glu (p < 0.01), CK (p < 0.001), and UA (p < 0.05) were observed at both T1 and T2 relative to T0. At T0, CK levels were significantly higher in subadults compared to juveniles. No significant correlations were found between CORT and the other measured parameters. Our results suggest that the rehabilitation period is a safety period during which the animals reestablish their homeostasis despite captivity conditions. However, further studies are needed to define other causes of variations in stress levels in rehabilitating C. caretta. Full article

Accurate prediction of Rate of Penetration (ROP) in carbonate formations remains constrained by the arbitrary selection of geomechanical input parameters in empirical drilling models. This study presents the first systematic field-based evaluation of sixteen geomechanical properties—grouped into three categories: strength parameters (uniaxial compressive strength (UCS), confined compressive strength (CCS), shear strength, thick-walled cylinder strength (TWC), friction angle, and cohesion), elastic moduli (Young’s modulus, shear modulus, bulk modulus, bulk compressibility, dynamic combined modulus (DCM), Poisson’s ratio, brittleness index), and in situ stress parameters (overburden pressure, minimum, and maximum horizontal stresses)—to identify optimal predictors for ROP modeling across PDC bit sizes of 12.25″ and 8.5″. Continuous wireline log data from two vertical carbonate wells in the Middle East (Well A: 1000–3370 m; Well B: 1945 to 3128 m; total intervals of 2370 m and 1183 m, respectively) penetrating formations comprising limestone, dolomite, sandstone, shale, anhydrite, and marly limestone were used. All sixteen geomechanical properties were computed using Interactive Petrophysics (IP) software with lithology-specific empirical correlations and validated against laboratory core measurements (R² = 0.79–0.95). Pearson and Spearman correlation analyses quantified parameter–ROP relationships, and the Al-Abduljabbar empirical model, recalibrated via multiple nonlinear regression, served as the evaluation framework. DCM consistently exhibited the strongest negative correlation with ROP across both bit sizes and achieved the highest model accuracy (R² = 0.54, AAPE = 25.33%), significantly outperforming the Bourgoyne and Young model (R² = 0.26, AAPE = 36.55%). A statistically validated scale-dependent effect was identified: Fisher’s Z-transformation tests confirmed that the correlation reversal between CCS and UCS across bit sizes is statistically significant (CCS: Z = −16.84, p < 0.001; UCS: Z = −6.75, p < 0.001), establishing CCS as the superior predictor at 12.25″ and UCS as the superior predictor at 8.5″—a finding not previously reported in the ROP literature. This reversal is attributed to the larger contact area of the 12.25″ bit, which promotes confinement-dominated rock failure better described by CCS, whereas the smaller bit produces localized stress concentration better represented by UCS. These results establish that (1) optimal geomechanical input selection is bit-size dependent, (2) nonlinear modeling outperforms linear frameworks for strength–ROP relationships, and (3) parameter relevance outweighs coefficient tuning in model robustness. DCM is recommended as the most operationally practical universal input, requiring only conventional compressional sonic and density logs. This study provides a systematic framework for geomechanical parameter selection with direct implications for drilling optimization in heterogeneous carbonate reservoirs. Full article

Deep Earth TK-1, China’s first 10,000 m scientific exploration well, encountered severe wellbore instability during sidetracking at a depth of approximately 9500 m under ultra-deep, high-stress conditions (maximum horizontal stress ${\sigma }_H$ = 230 MPa, minimum horizontal stress ${\sigma }_h$ = 200 MPa). To clarify how the original wellbore affects the stability of the sidetracked wellbore, single- and dual-well numerical models were established in COMSOL Multiphysics using the solid mechanics module and finite element method. The stress redistribution around the wellbore was analyzed before and after the collapse of the main wellbore, and the influences of well spacing and breakout geometry were quantified. The results show that a stress-relief “safe zone” forms along the direction of maximum horizontal stress before collapse and expands after collapse, allowing safer sidetracking within this range. In the dual-well model, the maximum stress difference around the sidetracked wellbore increases with well spacing and eventually approaches that of a single circular wellbore. The safe zone boundary was quantified for well spacings between 2.0 m and 3.5 m, depending on the major-axis enlargement ratio of the collapsed main wellbore. A larger major-axis enlargement ratio reduces far-field stress interference and expands the safe zone, whereas changes in the minor-axis enlargement ratio have little effect. These findings provide theoretical support for optimizing sidetracking design in ultra-deep wells. Full article

The study investigated the effects of high-intensity interval training (HIIT) on cardiorespiratory fitness, hormonal, and psychological markers in adolescents. Twenty-eight healthy male adolescents were randomized to a HIIT group or a non-training control group. HIIT comprises three sessions per week for 10 weeks, alternating 30 s runs at high-intensity and low-intensity. VO_2max was estimated using the incremental running test. Plasma testosterone and cortisol were assessed by ELISA methods. Depression, anxiety, and stress scores were determined using the Depression Anxiety Stress Scales-21. Data were analyzed using two-way ANOVA with repeated measures. Significant “group × time” interactions were detected for VO_2max, testosterone, cortisol, testosterone-to-cortisol ratio, and stress score, but not for anxiety and depression scores. HIIT resulted in increased VO_2max (p < 0.001, d = 1.04), testosterone (p = 0.005, d = 0.52), and testosterone-to-cortisol ratio (p = 0.008, d = 1.05), and decreased cortisol (p = 0.036, d = 1.09) and stress score (p = 0.020, d = 0.98). Ten-week HIIT resulted in an improvement in physical fitness, steroid hormonal balance, and self-reported stress symptoms, but no changes in depressive and anxiety symptoms in comparison to the control group. The findings should be interpreted with caution due to limitations, including the small sample size and the lack of assessment of sex-related differences. Further research is required to elucidate the topic. Full article

Deepwater shallow gas sediments and the weakly consolidated overburden are sensitive to depletion-induced effective stress redistribution. Since deepwater shallow gas has only recently begun to be treated as a commercially available natural gas resource, it lacks models to quantify the coupled flow and geomechanical behaviors in such environments. In this study, we propose a semi-analytical model for a shallow gas layer and its overburden sediments, where pore pressure evolution is described by vertical transient diffusion and the stress response is represented by an OCR-dependent (overconsolidation ratio-dependent) in situ stress field with depletion-induced effective stress increments. Pre-yield compressibility is characterized by a stress-dependent nonlinear elastic law, and post-yield deformation is approximated by a Mohr–Coulomb-based yield-controlled plastic correction for engineering purposes. The formulation is used in the base case and during a parametric sensitivity analysis. In the base case, the final settlement is 0.597 m, of which 45.3% is elastic and 54.7% is plastic. The sediments begin to yield after approximately 115 d of production, and the final yielded-thickness fraction reaches 0.268. The sensitivity analysis shows that friction angle, maximum drawdown, gas-layer thickness, and OCR magnitudes predominantly affect the final settlement and yielded-thickness response, while gas-layer permeability has an insignificant effect. Furthermore, the comparison reveals that the depletion timescale governs the stress evolution rate, while depletion pressure drawdown magnitude dictates deviatoric stress evolution and long-term settlement. Considering the engineering condition for the development of typical deepwater shallow sediments, the feasible production parameters should be in the low-to-moderate drawdown and slow depletion range. A practical operating window is approximately 3.6~4.0 MPa maximum drawdown with a depletion timescale of about 340~400 d. This study can provide quantitative insights into the potential commercial production of gas layers in deepwater shallow sediments. Full article

Underground Compressed Air Energy Storage (CAES) is a promising large-scale energy storage technology, yet its long-term operational safety is constrained by progressive tensile damage accumulation in lining structures under cyclic thermo-mechanical loading. Conventional steel-lined caverns are costly, while ordinary reinforced concrete linings require excessive reinforcement due to their limited tensile capacity, compromising the economic viability of CAES. This study proposes a Reinforced-Steel Fibre Concrete (R-SFC) lining as the structural load-bearing layer of CAES caverns, in which the steel fibres provide tensile and crack-propagation resistance and the rebars contribute supplementary tensile capacity. A 2D coupled thermo-mechanical damage-plasticity finite element model was developed in COMSOL Multiphysics and verified using published in situ monitoring data from operating CAES caverns. Parametric analyses of the steel fibre volume fraction, lining thickness, rebar diameter, and cavern diameter were then performed. The results show that the R-SFC lining significantly improves crack propagation resistance, reducing the maximum tensile damage by 41.3% relative to conventional reinforced concrete while lowering steel consumption. Within the lining–rock system, the concrete lining and the surrounding rock jointly resist the radial compressive load, while the steel fibres and rebars bear the hoop tensile stress. A thickness-to-diameter ratio of 1/8 to 1/5 is identified as the recommended geometric design range to balance lining damage against surrounding rock loading. Finally, an MOPSO algorithm coupled with a PSO-BP surrogate model is employed to balance lining tensile damage against cavern dimensions, yielding optimised parameter combinations particularly suitable for cavern diameters around 4 m. The study findings may provide a new lining solution and design reference for cost-effective and high-reliability underground gas storage. Full article