Search Results (163)

To address the issue of the low compression–tension ratio in the traditional parallel bond model (PBM), this study proposes an improved PBM incorporating a random distribution strategy of strong–weak contact groups. An L₂₇(3¹²) orthogonal experimental design was employed to construct 27 sets of numerical simulation schemes. Combined with Pearson correlation coefficient analysis and multivariate regression, the influence of twelve microscopic parameters on seven of the macroscopic mechanical properties of sandstone was systematically investigated, including elastic modulus (E), Poisson’s ratio (v), uniaxial compressive strength (σ_c), internal friction angle (φ), cohesion (c), crack damage stress ratio (σ_cd/σ_c), and compressive–tensile strength ratio (σ_c/σ_t). Based on these analyses, a quantitative relationship model between the macro and micro parameters was established and validated through numerical simulation and experimental comparison. The proposed method provides a theoretical foundation for the mechanical modeling of sandstone and the inversion of microscopic parameters. Full article

Introduction: This study aims to elucidate the impact of AQP1 on cardiac function and the intestinal microbiota in mice with chronic heart failure and to further investigate the broad effects of AQP1 on the gut microbiota composition in these mice. Methods: AQP1 knockout mice were used as the experimental group, with wild-type mice serving as the control group. The study evaluated the effects of AQP1 on various physiological parameters, including blood pressure, heart rate, cardiac function, cardiac color Doppler ultrasound, and 24 h urine collection. Additionally, the high-throughput sequencing of gut microbiota was performed to identify key microbial communities. Results: The deletion of the AQP1 gene did not significantly alter key cardiovascular metrics such as systolic blood pressure (SBP), mean blood pressure (MBP), or left ventricular mass (LV mass). However, we found that AQP1 knockout affected 24 h urine output in mice. Echocardiography results showed that AQP1 expression influenced LV mass, LVAW; d, and LVPW; s. Moreover, substantial differences were observed in the intestinal microbiota profiles between AQP1 knockout mice with heart failure and their wild-type counterparts. These findings suggest that AQP1 may contribute to cardiac dysfunction in mice with chronic heart failure through the regulation of gut microbiota. Conclusion: Our investigation provides initial insights into the role of AQP1 in modulating the intestinal microbiota in a murine model of heart failure. However, the precise mechanisms underlying this association require further exploration and detailed analysis. Full article

The proportion of granular ice in sea ice layers has markedly increased due to global warming. To investigate the uniaxial compressive behavior of granular sea ice, we conducted a series of experiments using natural piled and level ice samples collected from the Bohai Sea. A total of 311 specimens were tested under controlled temperature conditions ranging from −15 °C to −2 °C and strain rates varying from 10⁻⁵ to 10⁻² s⁻¹. The effects of porosity, strain rate, and failure modes were studied. The results show that both the uniaxial compressive strength and uniaxial compressive elastic modulus were dependent on strain rate and porosity. Granular sea ice exhibited a non-monotonic strength dependence on strain rate, with the strength increasing in the ductile regime and decreasing in the brittle regime. In contrast, the elastic modulus increased monotonically with the strain rate. Both the strength and elastic modulus decreased with increasing porosity. Level ice consistently demonstrated higher strength and an elastic modulus than piled ice at equivalent porosities. Unified parametric models were developed to describe both properties across a wide range of strain rates encompassing the ductile-to-brittle (DBT) regime. The experimental results show that, as porosity decreased, the transition strain rate of granular sea ice shifted from 2.34 × 10⁻³ s⁻¹ at high porosity (45%) to 1.42 × 10⁻⁴ s⁻¹ at low porosity (10%) for level ice and 1.87 × 10⁻³ s⁻¹ to 1.19 × 10⁻³ s⁻¹ for piled ice. These results were compared with classical columnar ice models. These findings are useful for informing the design of vessel and coastal structures intended for use in ice-covered waters. Full article

Soybean cyst nematodes (SCNs) are a significant disease that causes yield loss and reducing seed quality in soybeans (Glycine max). Developing SCN-resistant soybean varieties can minimize the need for insecticide use and reduce yield loss. Cinnamate-4-hydroxylase (C4H) and laccase (Lac) are key enzymes in the lignin synthesis pathway. In this study, SCN stress significantly promoted lignin accumulation in soybean roots and upregulated the expression of lignin signaling pathway genes GmC4H (Glyma.02G236500), GmLac55 (Glyma.13G076900), and GmLac85 (Glyma.20G051900). Using Agrobacterium rhizogenes-mediated transformation, the pNI900 expression vector was introduced into the soybean cultivar Williams 82 to generate GmLac55-overexpressing plants. The overexpression of GmLac55 enhanced soybean roots resistance to SCN and inhibited the further development of J2 larvae. Our study presents a strategy for increasing SCN resistance in soybean through Agrobacterium-mediated targeted mutagenesis of the GmLac55 gene. Full article

Triple-negative breast cancer (TNBC) poses significant challenges due to its high aggressiveness, poor prognosis, and the lack of effective targeted therapies. Paclitaxel (PTX) is a chemotherapeutic agent commonly used in the treatment of TNBC; however, its efficacy is often compromised by drug resistance mediated by autophagy. This study investigated the synergistic effects of the autophagy inhibitor 3-methyladenine (3-MA) and PTX in a TNBC nude mouse model. Monitoring tumor volume and employing HE staining, immunofluorescence, and transmission electron microscopy revealed that PTX monotherapy induced tumor autophagy, characterized by the accumulation of LC3B/VPS34 proteins and an increase in autophagosomes. However, the co-administration of 3-MA reversed this process, significantly decreasing the tumor growth rate. Immunofluorescence and qPCR demonstrated that the combination group had fewer Ki-67-positive cells and more Caspase-3-positive cells, along with upregulated expression of autophagy-related genes and Caspase-family apoptosis genes. Consequently, this study suggests that inhibiting autophagy with 3-MA disrupts the autophagy-mediated protective mechanism of tumor cells, promoting the activation of apoptotic signals and enhancing the antitumor activity of PTX. These findings may offer new molecular mechanistic insights and potential therapeutic strategies for overcoming PTX resistance in TNBC. Full article

The rational calculation of groundwater buoyancy directly impacts the safety of underground engineering. However, there is still no consensus on whether the reduction of groundwater buoyancy should be considered, and a theoretical explanation and quantification of buoyancy reduction in clayey soils is lacking. Based on laboratory engineering model tests, this study observed and analyzed the phenomenon of buoyancy reduction in saturated clayey soils. The contact area ratio of gravity water, calculated from geotechnical test data, was compared with the reduction slope. The experimental results indicated that the reduction slope of the fitted line between the static water head in the silty clay layer and the buoyancy water head was 0.8692. And theoretical analysis showed that the distribution of interparticle pore water pressure tends to attenuate from the pore center to the soil particle surface, suggesting a reduction in buoyancy head compared to the groundwater level. The reduction slope is theoretically equal to the contact area ratio of gravity water. Additionally, since limitations in current techniques for generalizing the soil–water constitutive models affect the reduction slope, this study proposes a method for determining the buoyancy reduction slope in saturated clayey soil based on the theory that interparticle pore water pressure distribution attenuates from the pore center to the soil particle surface. This method could potentially change the existing conceptual framework for buoyancy design in underground structures. Full article

Low phosphorus (P) stress impacts nitrogen (N) metabolism in soybeans. This study investigated the effects of exogenous cytokinin (Trans-Zeatin) on soybean N metabolism under low P stress by treating seeds with Trans-Zeatin and analyzing N accumulation, ¹⁵N abundance, nodule N fixation accumulation, nodule N fixation rate, nodule nitrogenase activity, soluble protein content, and free amino acid profiles. The results showed that exogenous cytokinin enhanced N accumulation in aboveground tissues, roots, and nodules, as well as nodule N fixation accumulation and fixation rate (from day 35 onward) under low P stress. Additionally, it promoted both acetylene reduction activity (ARA) and specific nitrogenase activity (SNA) in soybean nodules. By increasing the absorption of fertilizer-derived N, exogenous cytokinin alleviated the inhibitory effects of low P stress on the early growth and development of soybeans. Notably, under low P conditions, exogenous cytokinin significantly elevated the soluble protein content in nodules. However, the underlying mechanisms governing changes in free amino acid profiles require further investigation. This study provides a theoretical foundation for developing strategies to regulate soybean N metabolism under low P stress. Full article

To comparatively evaluate the suitability of superhydrophobic and superhydrophilic coatings for photovoltaic (PV) module surfaces in arid and low-rainfall regions, this study investigates their dust deposition mitigation performance under anhydrous conditions and assesses the impact of dust reduction on PV power generation efficiency. An experimental platform for dust deposition and a PV output measurement system were constructed to evaluate the performance of coated PV modules. The open-circuit voltage (U_oc), short-circuit current (I_sc), maximum power (P_max), and dust deposition mass were measured before and after dust exposure. Additionally, the influence of coating properties on dust deposition behavior and the correlation between dust deposition density and PV output power were systematically examined. The experimental data reveal a linear relationship between PV output power loss and dust deposition density. Dust accumulation decreases monotonically with panel tilt angle, while displaying a non-monotonic response to wind speed, peaking at 3.9 m/s. Under optimal conditions (60° tilt angle and 5.2 m/s wind speed), minimal dust deposition densities were observed: 0.25 g/m² for superhydrophobic coated PV modules versus 1.11 g/m² for superhydrophilic coated surfaces. Both superhydrophobic and superhydrophilic coatings demonstrated effective dust deposition inhibition in anhydrous environments. However, the dust deposition mitigation efficiency of the superhydrophobic coating (88.7%) is significantly better than that of the superhydrophilic coating (46.2%) under the working conditions of a large inclination angle (60°) and high wind speed (5.2 m/s). These findings provide critical experimental evidence for optimizing self-cleaning coating selection in PV modules deployed in arid regions. Full article

Reconstructing hyperspectral images (HSIs) from RGB images is an effective technique to overcome the high cost of spectrometers. Recently, Transformers have shown potential in capturing long-range dependencies for spectral reconstruction. However, few Transformer models attempt to simultaneously capture both spatial and spectral correlations in HSIs. Within this study, we introduce an integrated spatial–spectral hybrid Transformer (SSHFormer) framework designed to capture the interplay between spatial and spectral features in HSIs, with the aim of incrementally enhancing the fidelity of the reconstructed HSIs. In SSHFormer, we propose a spatial–spectral multi-head self-attention (SSMA) mechanism, which utilizes dilated convolution to extract non-local spatial features while maintaining parameter efficiency and applies the attention mechanism to the channel dimension to model inter-spectral correlations. Additionally, a 3D feedforward network (3DFFN) is proposed for SSHFormer, which leverages 3D convolution to fuse the spatial and spectral information, enabling more comprehensive feature extraction. Experimental results demonstrate that our SSHFormer achieves state-of-the-art (SOTA) performance on public datasets. Full article

With rapid urbanization, urban underground space (UUS) development has become crucial for sustainable urban growth. This paper systematically reviews geological suitability evaluation (GSE) methods for UUS, integrating theoretical frameworks, indicator systems, and assessment techniques. We establish a comprehensive evaluation framework based on environmental strategic assessment (ESA) principles, analyzing key geological factors, including rock/soil properties, hydrogeological conditions, geological hazards, and existing underground structures. The study compares weighting methods (AHP, EWM, CRITIC) and comprehensive evaluation models (FCE, TOPSIS, BNM), highlighting their advantages and application scenarios. A case study of Xiong’an New Area demonstrates how multi-layer UUS planning integrates geological constraints with sustainable development goals. The results show that combining 3D geological modeling with hybrid evaluation methods significantly improves decision-making accuracy. The review provides practical guidance for optimizing UUS utilization while addressing current challenges in indicator selection, weight rationalization, and heterogeneity management. Full article

To elucidate the regional flavor characteristics of sun-dried green tea (SDT) and their underlying influencing factors, a comprehensive analysis was conducted using metabolomics and flavoromics approaches. This study systematically examined SDT samples and their corresponding tea garden soils from 13 distinct regions in Yunnan Province. The results revealed that the SDT samples could be classified into two distinct groups based on their flavor profiles. Compared to the regions of Pa Sha (PS), Bang Dong (BD), Dong Ban Shan (DBS), Dong Guo (DG), Su Hu (SH), Gua Feng Zhai (GFZ), and Wu Liang Shan (WLS), the regions of Xin Nong (XN), Ba Ka Nuan (BKN), Mang Ang (MA), Man Nuan (MN), Bing Dao (BDao), and Bin Shan (BS) exhibited a significant upregulation of the tea polyphenols (TP)/free amino acids (FAA) ratio. The former group was characterized by a sweet mellow taste, while the latter displayed a stronger taste profile. Furthermore, the analysis of volatile compounds demonstrated that geraniol and linalool were significantly upregulated in the PS, BD, DBS, DG, BS, and BDao regions, which were associated with tender and floral aromas. In contrast, isophorone, 2-pentyl furan, 1-octanol, D-limonene, and benzaldehyde were markedly enriched in the XN, BKN, MA, MN, SH, GFZ, and WLS regions, contributing to sweet and honey-like aromatic profiles. Altitude and mineral element phosphorus are potential key factors affecting the regional flavor differences in SDT. Specifically, SDT cultivated at higher altitudes and in soils with elevated available phosphorus content exhibited a greater likelihood of accumulating sweet mellow and floral compounds. This study provides scientific evidence for understanding the characteristic flavor profiles of SDT across different regions, offering valuable insights into the factors contributing to regional flavor differentiation in tea production. Full article

Owing to the alternating processes of rainfall and evaporation, the compacted loess employed in ground and roadbed construction frequently experiences drying and wetting (D-W) cycles. These cycles are prone to induce substantial deformation of the soil mass, posing a risk to the integrity of buildings and infrastructure. Consequently, this study delved into the effects of D-W cycles on the deformation behavior of compacted loess, considering varying initial dry densities and water contents. To achieve a profound understanding of the deformation characteristics of the compacted loess, we meticulously monitored the resistivity ratio, crack ratio, and microstructure throughout the tests. Furthermore, a constitutive model was developed to forecast the deformation of compacted loess under D-W cycles. The findings revealed that both the vertical strain and crack ratio exhibited an upward trend with the increase in D-W cycle numbers, while they exhibited a downward trend as dry density increased. Notably, water content was identified as a significant factor affecting both the crack ratio and resistivity ratio. Additionally, the occurrence and progression of D-W cycles and cracks led to a slight increase in particle abundance and the proportion of total pore area. Meanwhile, during the wetting process, the infiltration of water softened the cementing substances, resulting in a disruption of the connections between aggregates. This made it much easier for cracks in the soil to expand after the sample dried. The constitutive model was meticulously constructed by incorporating yield surfaces that account for decreasing and increasing water contents. The validity of the proposed model was substantiated through a comparative analysis of the measured and calculated data. This comprehensive investigation furnishes a theoretical foundation for assessing the stability of compacted loess ground and roadbeds subjected to D-W cycles. Full article

Phosphorus is an indispensable nutrient for nitrogen metabolism in soybeans. In this study, two P levels were established, 1 mg/L (low-P stress) and 31 mg/L (normal P, CK), by combining ¹⁵N labeling with real-time quantitative PCR and the UHPLC-MS/MS method, to analyze soybean nitrogen accumulation, ¹⁵N abundance, nodule nitrogen fixation accumulation, nodule nitrogen fixation rate, soluble protein content, the relative expression of phosphorus transporters, amino acid changes, and metabolic pathways. The impacts of phosphorus stress on soybean nitrogen metabolism were explored from the perspectives of nitrogen accumulation and protein metabolism. The results demonstrated that low-P stress promoted the absorption of fertilizer nitrogen by aboveground parts, roots, and nodules of soybeans. However, it significantly inhibited nitrogen accumulation (11.09–95.41%), nodule nitrogen fixation accumulation (21.54–96.21%), and nodule nitrogen fixation rate (2.95–37.75%). The soluble protein content in both leaves and nodules decreased remarkably, while the relative expression of GmPT7 was upregulated in leaves, roots, and nodules under low-P stress. A total of 70 amino acids exhibited alterations, among which 26 amino acids were involved in 37 metabolic pathways, playing a crucial role in regulating the effects of low-P stress on soybean nitrogen metabolism. This study identifies significant alterations in nitrogen accumulation, nodule nitrogen fixation, and the expression of phosphorus transporter genes, providing insights into the metabolic pathways involved in soybean’s adaptation to phosphorus deficiency. This research provides a solid theoretical foundation for further in-depth investigations into the physiological and molecular mechanisms of soybean response to low-P stress. Full article

With the development of the new power system with a high proportion of new energy and a high proportion of power electronic equipment, various problems caused by high-frequency oscillation will seriously affect the daily normal operation of the power system. For the existing active oscillatory suppression strategies, the impedance characteristics of other frequency bands will be affected, which may cause new oscillation problems in other frequency bands, namely the negative effect of oscillatory suppression strategy. In response to such phenomena, we conducted research on the mechanism of negative effects and optimize the control strategies accordingly. First, an analysis model of the grid-connected inverter was established. The concept of the damping factor was proposed based on the relationship between passive damping and active damping. The feasibility of the oscillation suppression mechanism based on the damping factor was demonstrated, and the negative effect mechanism of the oscillation suppression strategy was clarified. Secondly, a control strategy based on the superposition of active damping was proposed, which not only solved the negative effect of the oscillation suppression strategy but also avoided the shift of the inherent resonance point. Finally, the theory was verified based on the MATLAB R2022a/Simulink simulation platform. Full article

Inspired by C. Alexandru, to achieve a balance between tracking accuracy and equipment cost and between single-axis tracking brackets and dual-axis tracking brackets, a kind of quasi-biaxial solar tracker, whose approximate two-axis motions are driven by a single motor, is studied in this paper. Firstly, considering the changes in the total number of sunny days and declination angle in a certain period of time, the characteristic day of the tracker in this period is set. Then, based on the variations in the Sun’s azimuth and elevation angle on the characteristic day, a quasi-biaxial solar tracker mechanism is designed. Its azimuth angle movement is directly driven by a single motor, while the elevation angle movement is driven by the same motor through a bevel gear and a cam mechanism. The solar irradiance of the photovoltaic module of the solar tracker is analyzed using PVsyst software. Through 3D modeling-aided design, a prototype of the solar tracker is built and then relative experiments are conducted to study the performance of the quasi-biaxial solar tracker. Simulation analysis and physical model experiments show that the quasi-biaxial solar tracker works and achieves a relative compromise between tracking accuracy and cost. Full article