Search Results (456)

With the development of rocket technology, achieving high-precision landing has become a key technical challenge in the field of aerospace. To cope with this challenge, we propose a lossless convexification algorithm based on the integral pseudospectral method in this paper. Firstly, for the fuel optimization problem, the continuous dynamic equations and constraints are discretized with high accuracy using an integral-type pseudospectral method. By constructing a global integration matrix at Legendre–Gauss nodes, the original complex continuous problem is effectively transformed into a discrete form that is more tractable for numerical optimization. Secondly, the non-convex constraints are transformed using the lossless convexification technique, thereby reformulating the original problem as a second-order cone programming (SOCP) problem. The effectiveness of the proposed algorithm is validated through numerical simulations, which demonstrate high landing accuracy, robustness, and fuel efficiency. These results highlight the algorithm’s high performance and strong potential for practical application in space missions. Full article

Current research predominantly focuses on the microbial-driven processes of soil organic nitrogen mineralization, often overlooking the significant contributions of abiotic pathways mediated by reactive minerals. While manganese oxides are known to promote the abiotic mineralization of organic nitrogen, the influence of key environmental factors on this process remains poorly understood. This study established a simulated system to investigate the effects of dissolved oxygen and pH on the γ-MnO₂-mediated abiotic nitrogen mineralization of peptone. The results showed that under an air atmosphere at pH 5.0–8.0, the rate of nitrogen mineralization from peptone catalyzed by γ-MnO₂ initially increased and then subsequently decreased. Dissolved oxygen was identified as a major electron acceptor in the peptone nitrogen mineralization process, playing a critical role in its rate and extent. Direct oxidation by Mn (IV) and Mn (III) within γ-MnO₂ accounted for 72.5% of the peptone nitrogen mineralization, and reactive oxygen species generated on the mineral surface accounted for 27.5% through a catalytic oxidation mechanism. This study provides a preliminary analysis of how key environmental factors influence the abiotic mineralization of protein-derived organic nitrogen, which is expected to deepen the understanding of soil organic nitrogen mineralization mechanisms, enrich the knowledge of nitrogen cycling in agricultural ecosystems, and provide a theoretical basis for efficient nitrogen management in farmland. Full article

Plant fungal diseases pose a serious threat to crop production and safety, and natural products are one of the important directions for the development of new green fungicides. This study found that the extract of Murraya euchristifolia had significant antifungal activity, and a main antifungal coumarin (1) was isolated by bioassay-guided fractionation. The structure of 1 was identified by NMR and MS spectroscopic data as a fused bis-furan coumarin (microminutinin) which was first isolated from the Murraya genus and exhibited strong broad-spectrum antifungal activity against eight plant pathogenic fungi from different families and genera. The EC₅₀ value of 1 (11.33 μg/mL) against Pestalotiopsis theae (the most sensitive to 1) was slightly higher than that (7.03 μg/mL) of the positive drug (80% carbendazim WP), indicating that 1 has the potential to serve as a lead compound for botanical fungicides. The bioassay results against P. theae in vivo indicated that 1 also has the potential for field application. Scanning electron microscopy and optical microscopy revealed that 1 disrupted the morphological structure of mycelium, causing hyphae to twist, shrink, and even crack and severely reducing hyphal branching. Furthermore, propidium iodide staining proved that microminutinin destroyed the integrity of the cell membrane, causing leakage of cellular components. In addition, calcofluor white staining and chitin content changes illustrated that microminutinin disrupted the cell wall structure. This research provides compound sources and a theoretical basis for the development of botanical fungicides. Full article

While biodegradable plastics alleviate plastic pollution, their degradation-derived biodegradable microplastics (BMPs) pose new ecological risks, necessitating efficient quantification methods. This study explores a label-free approach by leveraging the intrinsic fluorescence of common biodegradable polyesters (PLA, PHB, PBS, PBAT, PCL). We find that biodegradable microplastics exhibit two types of characteristic fluorescence emission: one originating from molecular functional groups and the other originating from the chromophore formed by the aggregation of conjugated groups. Using PBAT as a model, we confirm that fluorescence intensity depends on the BMPs’ size and shape. Under 380 nm excitation, concentration-dependent signals are observed at 436 nm (indirectly from PBAT-enhanced water Raman scattering) and 465 nm (directly from PBAT intrinsic fluorescence), leading to successful linear models between BMPs’ mass concentration and fluorescence intensity over 100–500 mg/L, with correlation coefficients (R²) of 0.877 and 0.963, respectively. Compared with the fluorescence labeling method, the intrinsic fluorescence approach achieves comparable R² while exhibiting lower signal intensity (~10³). Nevertheless, its operational simplicity offers a distinct advantage for the rapid quantification of pre-isolated and purified microplastics. Full article

In recent years, renewable energy generation (RPG) has experienced rapid growth, and large-scale hydro–wind–photovoltaic storage (HWPS) bases have been progressively developed in southwest China, where hydropower resources are abundant. Ensuring the small-signal stability of such large-scale integrated systems has become a critical challenge. While considerable research has focused on the small-signal stability of grid-connected wind, photovoltaic, or energy storage systems (ESSs), studies on the stability of large-scale HWPS bases remain limited. Moreover, emerging grid codes require power electronic devices to maintain synchronization under unbalanced grid conditions. The time-varying rotating transformations introduced by positive-sequence (PS) and negative-sequence (NS) control render the conventional Park transformation ineffective. To address these challenges, this study develops a linear time-periodic (LTP) model of a large-scale HWPS base using trajectory linearization. Based on Floquet theory, the impacts of RPG station and ESS control parameters on system stability are analyzed. The results reveal that under the considered scenario, these control parameters may induce oscillations over a relatively wide frequency range. Specifically, low PLL and DVC bandwidths (BWs) are associated with the risk of low-frequency oscillations, whereas excessively high BWs may lead to sub-synchronous oscillations. The validity of the analysis is verified through comparison with time-domain simulations of the nonlinear model. Full article

Background/Objectives: The Sox transcription factor family is critical for gonadal development and sex differentiation in animals, yet its roles in chelonians, particularly in the Chinese soft-shelled turtle (Pelodiscus sinensis), have rarely been investigated. Methods: This study cloned and analyzed the cDNA sequences of Sox3 and Sox30 genes from P. sinensis, examining their amino acid sequences and structural properties. Real-time quantitative PCR (RT-qPCR) was used to assess the expression of these two genes in different adult tissues and at various stages of embryonic gonadal development. Additionally, the effects of exogenous hormones (17β-estradiol, E₂ and 17α-Methyltestosterone, MT) on the expression of Sox3 and Sox30 were also investigated. Results: The results indicated that Sox3 showed significantly elevated expression in female gonads, kidney, brain, liver, lung, spleen, and muscle relative to male counterparts, displaying a female-biased expression pattern. In contrast, Sox30 showed a male-biased pattern, with higher expression in male gonads, spleen, muscle, brain, and liver than in females, showing expression. Both genes were expressed at low levels. Exogenous hormone treatments revealed that MT significantly downregulated Sox3 expression in female embryos, whereas E₂ significantly enhanced Sox3 expression in male embryos. Furthermore, MT treatment significantly upregulated Sox30 expression in female embryos, and E₂ treatment also significantly increased Sox30 expression in male embryos. Conclusions: These findings suggest that Sox3 and Sox30 play crucial roles in the gonadal development of P. sinensis, with Sox3 potentially involved in ovarian development and Sox30 in testicular maturation. Both genes are regulated by exogenous hormones, highlighting their importance in sex differentiation and gonadal development. This study provides valuable theoretical insights for further exploration of the molecular mechanisms of sex regulation in reptiles. Full article

Precision dicing with diamond wheels is a key technology in semiconductor dicing, integrated circuit manufacturing, aerospace, and other fields, owing to its high precision, high efficiency, and broad material applicability. As a critical processing stage, a comprehensive analysis of dicing technologies is essential for improving the machining quality of hard-and-brittle optoelectronic materials. This paper reviews the core principles of precision diamond wheel dicing, including dicing processes and blade preparation methods. Specifically, it examines the dicing mechanisms of composite and multi-mode dicing processes, demonstrating their efficacy in reducing defects inherent to single-mode approaches. The review also examines diverse preparation methods for dicing blades, such as metal binder sintering and roll forming. Furthermore, the roles of machine vision and servo control systems are detailed, illustrating how advanced algorithms facilitate precise feature recognition and scribe line control. A systematic analysis of key components in grinding wheel dicer is also conducted to reduce dicing deviation. Additionally, the review introduces models for tool wear detection and discusses material removal mechanisms. The influence of critical process parameters—such as spindle speed, feed rate, and dicing depth—on dicing quality and kerf width is also analyzed. Finally, the paper outlines future prospects and provides recommendations for advancing key technologies in precision dicing, offering a valuable reference for subsequent research. Full article

Chemosensory systems are essential in insect behavior, with several key genes associated with these systems emerging as potential targets for pest control. Porphyrophora sophorae (Archangelskaya, 1935), a destructive pest of Chinese licorice (Glycyrrhiza uralensis, Fabaceae), poses a significant threat to the healthy cultivation of licorice. However, the molecular mechanisms underlying its host detection and olfactory recognition remain poorly understood. In this study, we present the first identification of odorant-binding proteins (OBPs) and olfactory receptors (ORs) from the transcriptome of P. sophorae. The identified OBPs contain six conserved cysteine residues, while predictive analysis suggests that PsopOrco may contain six transmembrane domains. Phylogenetic analysis demonstrated that the majority of these olfactory proteins are closely related to OBPs and ORs found in other scale insects. Using RT-qPCR, we assessed the anatomical structures expression of these genes and found that PsopOBP3, PsopOBP6, and PsopOrco were predominantly expressed in the antennae. Additionally, expression levels of OBPs and ORs varied across different tissues, suggesting anatomical structure regulation. These findings expand the gene repertoire of P. sophorae and provide valuable resources for further functional analysis of these key olfactory genes. Full article

The SHB fault-controlled condensate gas reservoir is the largest ultra-deep carbonate gas reservoir in China, and the accuracy of dynamic reserve calculation is an important basis for developing the development plan. The fault-controlled condensate gas reservoir has some problems, such as “ultra-deep, ultra-high temperature, supercritical”, strong heterogeneity of reservoir space, and difficulty in obtaining real underground reservoir parameters, which seriously affect the results of dynamic reserve evaluation. Combining the quasi-steady flow equation and the flow resistance of a gas well, a new flow material balance method based on the original apparent formation pressure and daily production data is proposed to effectively calculate the dynamic reserves of a gas reservoir. By comparing the calculation results of various dynamic reserves calculation methods for the SHB condensate gas reservoir, it is proven that this method can effectively calculate the dynamic reserves of gas wells and has important guiding significance for the calculation of dynamic reserves of fault control body condensate gas reservoirs. Full article

Unmanned aerial vehicle (UAV) hyperspectral remote sensing imaging systems have demonstrated significant potential for water quality monitoring. However, accurately obtaining water-leaving reflectance from UAV imagery remains challenging due to complex atmospheric radiation transmission above water bodies. This study proposes a method for water-leaving reflectance inversion based on air–ground collaborative correction. A fully connected neural network model was developed using TensorFlow Keras to establish a non-linear mapping between UAV hyperspectral reflectance and the measured near-water and water-leaving reflectance from ground-based spectral. This approach addresses the limitations of traditional linear correction methods by enabling spatiotemporal synchronization correction of UAV remote sensing images with ground observations, thereby minimizing atmospheric interference and sensor differences on signal transmission. The retrieved water-leaving reflectance closely matched measured data within the 450–900 nm band, with the average spectral angle mapping reduced from 0.5433 to 0.1070 compared to existing techniques. Moreover, the water quality parameter inversion models for turbidity, color, total nitrogen, and total phosphorus achieved high determination coefficients (R² = 0.94, 0.93, 0.88, and 0.85, respectively). The spatial distribution maps of water quality parameters were consistent with in situ measurements. Overall, this UAV hyperspectral remote sensing method, enhanced by air–ground collaborative correction, offers a reliable approach for UAV hyperspectral water quality remote sensing and promotes the advancement of stereoscopic water environment monitoring. Full article

Wetland loss and human activities are forcing migratory waterbirds to rely on alternative habitats such as croplands, yet their adaptive habitat use across contrasting landscape contexts remains unclear. The Bar-headed Goose (Anser indicus) is a key indicator species in the wetland ecosystems of the Yunnan–Guizhou Plateau. Comparing differences in its wintering habitat selection and utilization is of great significance for understanding its ecological adaptation mechanisms and formulating regional wetland conservation strategies. In this study, we compared the diurnal habitat use during the wintering period of Bar-headed Geese at three wetlands (Nianhu, Caohai, and Napahai) representing distinct landscape contexts. We used GPS satellite tracking and dynamic Brownian bridge movement modeling, combined with random forest analysis of environmental variables, to quantify diurnal habitat use and selection at each site. Our results revealed significant regional differences in habitat use. In the agriculture-dominated wetlands (Nianhu and Caohai), geese primarily utilized cropland and marsh habitats (Nianhu: cropland 45.88% ± 30.70%, marsh 42.55% ± 33.17%; Caohai: cropland 62.33% ± 12.16%, marsh 28.61% ± 13.62%). In contrast, at Napahai, which is dominated by natural habitats, geese primarily used grassland (65.92% ± 20.01%) and marsh (26.85% ± 21.88%), with minimal use of cropland (4.21% ± 7.00%). Diurnal habitat selection was influenced by multiple environmental factors, with distinct regional differences identified through random forest modeling. In Nianhu, key factors included distance to supplemental feeding site, distance to grassland, distance to woodland, and distance to open water. In Caohai, distance to grassland, distance to nocturnal roost site, distance to settlement, and distance to open water were significant drivers. In Napahai, distance to nocturnal roost site, distance to open water, and distance to marsh were the most influential (all with p < 0.01), reflecting flexible behavioral responses. Based on these findings, we recommend region-specific conservation management strategies. Specifically, supplemental feeding at Nianhu should be strictly regulated. Agricultural planning in farming areas should account for the habitat needs of wintering waterbirds. Grassland and marsh habitats at Napahai should also be more effectively protected. Full article

Understanding the non-equilibrium dynamical processes in two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures is essential for elucidating their photoelectric behaviors. In this work, we investigate the electronic structure, electric field modulation, and transient optical performance of the MoSe₂/WSe₂ heterostructure using first principles and nonadiabatic molecular dynamics (NAMD) methods. Applying an external electric field effectively modulates the bandgap and band arrangement of MoSe₂/WSe₂ heterostructure, along with a transition from indirect to direct bandgap during which the type-II band alignment can be maintained. Specifically, the ultrafast interlayer photogenerated electron transfer time is 72 fs, and the interlayer electron-hole recombination time can be as long as 357 ns, which is longer than that of the intralayer recombination in the constituent monolayers (110 ns for MoSe₂ and 288 ns for WSe₂), yielding an ultrahigh charge separation efficiency of up to 99.99%. The significant time difference in the processes of photoinduced charge transfer and recombination can be attributed to the corresponding different nonadiabatic coupling averaged values, mainly determined by the electron–phonon coupling and energy difference. The carrier dynamics mechanism revealed in the MoSe₂/WSe₂ heterostructure is conducive to the development of 2D ultrafast optoelectronic devices. Full article

Background and Methods: To address the need for dietary interventions in sub-healthy populations and promote sustainable utilization of agricultural by-products, we isolated Pinus pumila hypoglycemic peptide (PHP) from nut oil meal through enzymatic extraction, ion exchange and gel chromatography purification, and simulated gastric digestion. Results: PHP exhibited significant inhibitory activity against α-amylase and α-glucosidase. In type 2 diabetic mice, PHP significantly ameliorated the “three-more-one-less” syndrome, reduced glycosylated hemoglobin and insulin levels, mitigated liver and kidney tissue lesions, and improved glucose and lipid metabolic disorders—effects partly supported by its enhancement of intestinal barrier function via restoring gut microbiota diversity. Gut microbiota analysis revealed that PHP exerts hypoglycemic effects by regulating gut microbial composition: increasing SCFA-producing taxa, reducing pro-inflammatory/metabolic disorder-associated taxa, and normalizing the Firmicutes/Bacteroidetes ratio. KEGG pathway analysis demonstrated that PHP mediates synergistic hypoglycemic effects by regulating carbohydrate metabolism, amino acid metabolism, and cofactor/vitamin metabolism. Conclusions: This work provides a theoretical foundation for developing natural functional foods from agricultural by-products, supporting PHP’s potential as a dietary supplement for metabolic regulation. Full article

Prussian blue (PB) and its analogs (PBAs) are considered ideal cathode materials for sodium-ion batteries (SIBs) due to the following merits, including high redox potential, simple synthesis methods, and excellent structural stability. Herein, we synthesized a high-entropy PB cathode material, Na_1.20Mn_0.38Fe_0.15Ni_0.14Co_0.15Cu_0.16[Fe(CN)₆]_0.82□_0.18·0.38H₂O (HE-HCF), through a facile co-precipitation method. The five transition metals in HE-HCF have similar atomic sizes and electronegativity, collectively occupying the high-spin Fe-HS sites. The manganese-based system design reduces the preparation cost, and the high-entropy doping approach further decreases the content of crystalline water in the structure. Benefiting from the synergistic effects of the multiple component elements, HE-HCF demonstrates a capacity retention rate of 72.7% at 0.1 A g⁻¹. Moreover, it even maintains 85.3% of its initial capacity after 1000 cycles at 1 A g⁻¹. Electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) analyses further confirm that HE-HCF exhibits low charge transfer resistance and a small reaction activation energy. Full article

Extreme pantograph–catenary contact force (PCCF) oscillations pose a serious challenge to the stable coupling between pantograph and catenary in high-speed railway systems. This paper introduces an active compensation control framework CPO-LQR-BC-SAC, which combines optimized Linear Quadratic Regulator (LQR) baseline control with behavior cloning (BC) and Soft Actor-Critic (SAC) deep reinforcement learning. First, the Crowned Porcupine Optimization algorithm (CPO) is used to offline tune the LQR weighting matrix, producing a high-performance CPO-LQR controller that significantly reduces PCCF fluctuation. Next, a dual model-based offline control law provides “expert” adjustments that further suppress extreme contact force values. Observing that superimposing these offline-tuned actions onto real-time CPO-LQR outputs yields further suppression gains, we developed the BC-SAC compensatory controller to provide corrective control actions. In this scheme, expert actions guide the SAC policy via a behavior cloning loss term in its loss function, and a decaying imitation weight ensures a balance between imitation and exploration. Simulation results demonstrate that, compared to both CPO-LQR and the idealized offline control law, the proposed CPO-LQR-BC-SAC framework achieves over 77% reduction in PCCF standard deviation and exhibits the ability to generalize across different pantograph types, confirming its effectiveness and robustness as a practical solution for mitigating extreme PCCF oscillations. Full article