Search Results (48)

Urbanization has profoundly transformed land surface morphology and amplified thermal environmental modifications, culminating in intensified urban heat island (UHI) phenomena. Local climate zones (LCZs) provide a robust methodological framework for quantifying thermal heterogeneity and dynamics at local scales. Our study investigated the Changsha–Zhuzhou–Xiangtan urban agglomeration (CZXA) as a case study and systematically examined spatiotemporal patterns of LCZs and land surface temperature (LST) from 2002 to 2019, while elucidating mechanisms influencing urban thermal environments and proposing optimized cooling strategies. Key findings demonstrated that through multi-source remote sensing data integration, long-term LCZ classification was achieved with 1,592 training samples, maintaining an overall accuracy exceeding 70%. Landscape pattern analysis revealed that increased fragmentation, configurational complexity, and diversity indices coupled with diminished spatial connectivity significantly elevate LST. Rapid development of the city in the vertical direction also led to an increase in LST. Among seven urban morphological parameters, impervious surface fraction (ISF) and pervious surface fraction (PSF) demonstrated the strongest correlations with LST, showing Pearson coefficients of 0.82 and −0.82, respectively. Pearson coefficients of mean building height (BH), building surface fraction (BSF), and mean street width (SW) also reached 0.50, 0.55, and 0.66. Redundancy analysis (RDA) results revealed that the connectivity and fragmentation degree of LCZ_8 (COHESION8) was the most critical parameter affecting urban thermal environment, explaining 58.5% of LST. Based on these findings and materiality assessment, the regional cooling model of “cooling resistance surface–cooling source–cooling corridor–cooling node” of CZXA was constructed. In the future, particular attention should be paid to the shape and distribution of buildings, especially large, openly arranged buildings with one to three stories, as well as to controlling building height and density. Moreover, tailored protection strategies should be formulated and implemented for cooling sources, corridors, and nodes based on their hierarchical significance within urban thermal regulation systems. These research outcomes offer a robust scientific foundation for evidence-based decision-making in mitigating UHI effects and promoting sustainable urban ecosystem development across urban agglomerations. Full article

Umami is a fundamental taste sensation, often described as a delicious and pleasant flavor perception. To enhance or complement the original flavor and meet the tastes of diverse regions, umami dipeptides have been extensively utilized in global food manufacturing. Currently, the application and purification techniques of dipeptides are relatively mature, while their umami mechanisms and molecular modification are both scarce. In this work, the 3D structure of the umami dipeptide target T1R1/T1R3 was first obtained through sequence alignment and homology modeling, then followed by the successful construction of a database containing 400 samples of dipeptides. Subsequently, the complex models of T1R1/T1R3, respectively, with DG (Asp-Gly) and EK (Glu-Lys) (i.e., T1R1_DG/T1R3, T1R1/T1R3_DG, T1R1_EK/T1R3, and T1R1/T1R3_EK) were obtained via molecular docking and virtual screening. Finally, based on comparative molecular dynamics (MD) simulation trajectories, the binding free energy was calculated to investigate receptor–ligand recognition and conformational changes, providing some implications for potential modifications of umami dipeptides. T1R1 tends to bind relatively small umami dipeptides, whereas T1R3 does the opposite, both of which favor the recognition of acidic and hydrophilic dipeptides. By comparing strategies such as hydroxyl introduction and chain length alteration, electrostatic effects may be more important than non-polar effects in molecular design. This work not only explores the recognition mechanism of umami dipeptides with the receptor T1R1/T1R3 showing certain theoretical significance, but also provides feasible suggestions for dipeptide screening and modification having certain application value. Full article

Objectives: Unlike other body parts, unclarified lesions at the end of extremities have unique challenges due to their small size and interference. Traditional imaging methods struggle with low resolution. HFUS enhances resolution, offering a potential diagnostic value. Methods: From January 2019 to October 2023, the clinical and HFUS data of patients with unclarified lesions at the end of extremities were retrospectively analyzed. Independently, the diagnosis was made using two diagnostic modes (Mode A: only clinical information; Mode B: clinical and HFUS information). The diagnostic performance of the two modes was evaluated across different classification methods. Results: For all lesions, the correct rate of Mode B was higher than that of Mode A (52.8% vs. 18.4%, p < 0.001), and the indeterminate rate decreased by 43.0%. For benign lesions (51.0% vs. 18.2%), subungual lesions (40.8% vs. 21.1%), non-subungual lesions (55.6% vs. 17.8%), and common cases (60.9% vs. 20.3%), the diagnostic correct rate of Mode B was also higher than that of Mode A (all p < 0.05). However, there was no significant difference in rare lesions (9.8% vs. 4.9%) and malignant lesions (62.9% vs. 19.4%) between the two modes (both p > 0.05). Moreover, the indeterminate rate for all categories of lesions significantly diminished. Otherwise, Mode B demonstrated strong performance for malignant lesions (85.7% vs. 42.9%, p < 0.001). Conclusions: Adding HFUS can significantly improve the accuracy of diagnosing unclarified lesions at the end of extremities and reduce uncertainty, especially for benign and common lesions. HFUS has also demonstrated better performance in screening for malignant lesions. Full article

Integrating strong mechanical properties and excellent optical properties for self-healing materials is challenging in both academia and industry. Robust self-healing polyurethane elastomers are expected to have superior mechanical properties, transparency, remarkable healing capability, and shape-memory performance via the adjustment of chemical and microphase separation structure. Herein, a robust transparent self-healable 4,4′-diphenylmethane diisocyanate (MDI)-based polyurethane elastomer containing disulfide bonds and branched structure (MPUE-SS) was synthesized. The chemical and topological structures, compatibility of soft–hard phases, and hard domain size of polyurethane could be adjusted via branched structure and mixed chain extender containing disulfide bonds and 1,4-butanediol (BDO), leading to enhanced self-healing, transparency, and mechanical properties. MPUE-SS exhibited a maximal tensile strength of 40 MPa. The microphase separation structure and reduced crystallinity led to a high transparency of about 91%, close to that of alicyclic polyurethane elastomers. After cutting in half and splicing, the MPUE-SS film recovered more than 95% of the original mechanical properties in 24 h. The shape recovery ratio at 40 °C and shape fixity ratio at −20 °C of MPUE-SS were 96.0% and 99.6%, respectively, higher than those of MPUE without disulfide bonds. Therefore, the chemical, topological structures, and microphase separation of polyurethane could be adjusted to achieve desired self-healing, transparency, shape-memory, and mechanical properties. Full article

This study presents a sustainable approach to transform waste cooking oil (WCO) into a multifunctional 3D-printable photocurable elastomer with integrated self-healing capabilities. A linear monomer, WCO-based methacrylate fatty acid ethyl ester (WMFAEE), was synthesized via a sequential strategy of transesterification, epoxidation, and ring-opening esterification. By copolymerizing WMFAEE with hydroxypropyl acrylate (HPA), a novel photocurable elastomer was developed, which could be amenable to molding using an LCD light-curing 3D printer. The resulting WMFAEE-HPA elastomer exhibits exceptional mechanical flexibility (elongation at break: 645.09%) and autonomous room-temperature self-healing properties, achieving 57.82% recovery of elongation after 24 h at 25 °C. Furthermore, the material demonstrates weldability (19.97% retained elongation after 12 h at 80 °C) and physical reprocessability (7.75% elongation retention after initial reprocessing). Additional functionalities include pressure-sensitive adhesion (interfacial toughness: 70.06 J/m² on glass), thermally triggered shape memory behavior (fixed at −25 °C with reversible deformation/recovery at ambient conditions), and notable biodegradability (13.25% mass loss after 45-day soil burial). Molecular simulations reveal that the unique structure of the WMFAEE monomer enables a dual mechanism of autonomous self-healing at room temperature without external stimuli: chain diffusion and entanglement-driven gap closure, followed by hydrogen bond-mediated network reorganization. Furthermore, the synergy between monomer chain diffusion/entanglement and dynamic hydrogen bond reorganization allows the WMFAEE-HPA system to achieve a balance of multifunctional integration. Moreover, the integration of these multifunctional attributes highlights the potential of this WCO-derived photocurable elastomer for various possible 3D printing applications, such as flexible electronics, adaptive robotics, environmentally benign adhesives, and so on. It also establishes a paradigm for converting low-cost biowastes into high-performance smart materials through precision molecular engineering. Full article

This research delves into the causal relationship between government expenditure (GE) and housing price (HP) in China, aiming to validate the dynamic equilibrium model. Given the potential for structural shifts, an analysis of the long-term nexus using the full-sample data casts doubt on the reliability of conventional causality tests. To address this, a time-varying rolling-window methodology is utilized to reassess the dynamic causal interplay between the two variables. The findings subsequently underscore a mutual causal association between HP and GE, indicating that changes in one variable can influence and be influenced by changes in the other. Specifically, HP fluctuations positively and negatively impact GE throughout various sub-periods. Conversely, GE has a beneficial influence on HP, aligning with the dynamic equilibrium model. To maintain a relatively consistent HP level, particularly during structural economic transformations, it is crucial to reinforce preventive controls associated with GE and ensure a rational and stable flow of GE into the real estate market. This strategy contributes to obtaining a more accurate understanding of the real estate market’s condition and development, thereby providing a basis for governmental policy-making and adjustments to preserve market stability and promote healthy growth. Full article

This research explores the distribution, transport, and deposition of calcium carbonate particles in the colorful pools of the Huanglong area under varying hydrodynamic conditions. The study employs Particle Image Velocimetry (PIV) for real-time measurements of flow field velocity and computational fluid dynamics (CFD) simulations to analyze particle behavior. The findings reveal that under horizontal flow conditions, the peak concentration of calcium carbonate escalated to 1.06%, representing a 6% surge compared to the inlet concentration. Significantly, particle aggregation and settling were predominantly noted at the bottom right of the flow channel, where the flow boundary layer is most pronounced. In the context of inclined surfaces equipped with a baffle, a substantial rise in calcium carbonate concentrations was detected at the channel’s bottom right and behind the baffle, particularly in regions characterized by reduced flow velocities. These low-velocity areas, along with the interaction of the boundary layer and low-speed vortices, led to a decrease in particle velocities, thereby enhancing deposition. The highest concentrations of calcium carbonate particles were found in regions characterized by thicker boundary layers, particularly in locations before and after the baffle. Using the Discrete Phase Model (DPM 22), the study tracked the trajectories of 2424 particles, of which 2415 exited the computational channel and nine underwent deposition. The overall deposition rate was measured at 0.371%, with calcium carbonate deposition rates ranging from 4.06 mm/a to 81.7 mm/a, closely matching field observations. These findings provide valuable insights into the dynamics of particle transport in aquatic environments and elucidate the factors influencing sedimentation processes. Full article

The settlement and deformation of abandoned mining tunnels can lead to cracking, deformation, or even the collapse of surface structures. Recently, a dual-direction, four-lane expressway, designed a speed of 100 km/h, is planned to be constructed between Yuanling County and Chenxi County. This expressway will pass through a long-abandoned refractory clay mining area in Chenxi County. This study focuses on this abandoned mining area and employs the Electrical Resistivity Tomography (ERT) method to investigate the underground conditions, aiming to determine the location and scale of the subterranean goaf. A total of five survey lines were deployed for the investigation. The inversion results indicate the presence of five low-resistivity anomalies in the underground structure (with six low-resistivity anomalies identified along line L1). These low-resistivity anomalies are preliminarily interpreted as subsurface cavities. Subsequent borehole verification revealed that the five low-resistivity anomalies correspond to a total of eight water-filled cavities, including six abandoned mining tunnels and two karst caves. At the location K33+260~K33+350, a large low-resistivity anomaly was identified which actually consisted of three closely spaced water-filled abandoned mining tunnels. Additionally, the surrounding strata primarily consisted of fractured mudstone, which has a high water content and thus exhibits low resistivity. These two factors combined resulted in the three water-filled abandoned mining tunnels appearing as a single large low-resistivity anomaly in the inversion profile. Meanwhile, at K33+50~K33+110, two water-filled abandoned mining tunnels were found. These tunnels are far apart along line L1 but are relatively close to each other on the other four survey lines. Consequently, in the inversion results, line L1 displays these as two separate low-resistivity anomalies, while the other four survey lines show them as a single large low-resistivity anomaly. Based on the 2D inversion results, a 3D model of the study area was constructed. This model provides a more intuitive visualization of the underground cavity structures in the study area. The findings not only serve as a reference for the subsequent remediation of the goaf area but also offer new insights into the detection of abandoned mining tunnels. Full article

The airline industry is currently navigating a pivotal period characterized by rapid development and increasing global pressure to reduce carbon emissions. Airlines, as the first to be significantly impacted, must actively manage their carbon footprints, adopt carbon abatement technologies, and address the inherent risks in this transformation. This paper examines the risk factors correlated with the technology transformation of carbon abatement and proposes effective abatement strategies. Using panel data of China Southern Airlines from 2009 to 2023 and applying the Logarithmic Mean Divisia Index (LMDI) method based on the Kaya identity, we analyze the differential impacts of various factors on unit carbon emissions. Multiple scenarios, derived from the influences of these factors, are constructed, and the Monte Carlo algorithm is employed to simulate the impact and volatility of correlated risks in the technology transformation for the abatement of carbon emissions. The findings are as follows: on the one hand, carbon emissions are strongly driven by energy consumption (0.99), flight volume (0.941), flight hours (0.931), transportation turnover (0.923), and take-off frequency (0.833). On the other hand, technology (56%) and scale (54.74%) significantly reduce unit carbon emissions, while take-off frequency negatively impacts emissions (−35.19%). Technology-related risks are controllable and relatively stable, whereas scale-related risks are highly uncertain. Additionally, operation-related risks can be partially hedged to ensure a certain level of risk controllability. Full article

Monocular 3D object detection refers to detecting 3D objects using a single camera. This approach offers low sensor costs, high resolution, and rich texture information, making it widely adopted. However, monocular sensors face challenges from environmental factors like occlusion and truncation, leading to reduced detection accuracy. Additionally, the lack of depth information poses significant challenges for predicting 3D positions. To address these issues, this paper presents a monocular 3D object detection method based on improvements to MonoCD, designed to enhance detection accuracy and robustness in complex environments. In order to effectively obtain and integrate depth information, this paper designs a multi-branch depth prediction with weight sharing module. Furthermore, an adaptive focus mechanism is proposed to emphasize target regions while minimizing interference from irrelevant areas. The experimental results demonstrate that MonoDFNet achieves significant improvements over existing methods, with AP3D gains of +4.09% (Easy), +2.78% (Moderate), and +1.63% (Hard), confirming its effectiveness in 3D object detection. Full article

Saline–alkali environments restrict soybean production in China. Wild soybean genes can be used to improve the alkaline tolerance of cultivated soybean in molecular breeding. The expansin protein family promotes cell wall expansion. In this study, the relative expression levels of expansin family genes in wild soybean treated with 50 mM NaHCO₃ were measured at 0, 3, 6, and 12 h, and the relative expression of GsEXPA8 was found to be higher at 12 h. Wild soybean was treated with abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA), and jasmonic acid (JA), and GsEXPA8 was found to respond to ABA and IAA signals. Sequence analysis shows that GsEXPA8 has DPBB_EXPA and expansin domains. Subcellular localization analysis shows that GsEXPA8 was localized in the cytoplasm in protoplasts and the cell membrane or wall in tobacco, indicating that it has nuclear membrane localization signals. GsEXPA8 overexpression reduced the malondialdehyde content in transgenic plants treated with NaHCO₃ and increased peroxidase activity before treatment. After the transformation of soybean roots from hair roots, GsEXPA8 was found to be expressed in the outer root cells and promote the development of thicker, shorter roots, thereby improving the plant’s alkaline tolerance. Stable GsEXPA8 transformation improved saline alkaline tolerance via the regulation of the alkali stress-related genes GmKIN1, GmRD22, GmDnaJA6, GmNFYC1, and GmMYB14. These findings provide support for further research on alkali-tolerance regulation pathways and molecular breeding for alkali tolerance. Full article

Two-dimensional (2D) nanofluidic channels are emerging as potential candidates for harnessing osmotic energy from salinity gradients. However, conventional 2D nanofluidic membranes suffer from high transport resistance and low ion selectivity, leading to inefficient transport dynamics and limiting energy conversion performance. In this study, we present a novel composite membrane consisting of porous MXene (PMXene) nanosheets featuring etched nanopores, in conjunction with cellulose nanofibers (CNF), yielding enhancement in ion flux and ion selectivity. A mild H₂O₂ oxidant is employed to etch and perforate the MXene sheets to create a robust network of cation transportation nanochannels that effectively reduces the energy barrier for cation transport. Additionally, CNF with a unique nanosize and high charge density further enhances the charge density and mechanical stability of the nanofluidic system. Under neutral pH and room temperature, the PMXene/CNF membrane demonstrates a maximum output power density of 0.95 W·m⁻² at a 50-fold KCl gradient. Notably, this represents a 43% improvement over the performance of the pristine MXene/CNF membrane. Moreover, 36 nanofluidic devices connected in series are demonstrated to achieve a stable voltage output of 5.27 V and power a calculator successfully. This work holds great promise for achieving sustainable energy harvesting with efficient osmotic energy conversion utilization. Full article

Plant architecture is an important agronomic trait that impacts crop yield. The tiller angle is a critical aspect of the plant’s structural organization, which is influenced by both internal and external factors. The genetic mechanisms underlying the tiller angle have been extensively investigated in other plants. However, research on wheat is relatively limited. Additionally, mechanics has emerged as a connection between biochemical signaling and the development of three-dimensional biological forms. It not only reveals how physical interactions at the cellular level influence overall morphogenesis but also elucidates the interplay between these mechanical processes and molecular signaling pathways that collectively determine plant morphology. This review examines the recent advancements in the study of tillering angle in wheat and other plants. It discusses progress in research ranging from observable characteristics to the regulation of genes, as well as the physiological and biochemical aspects, and the adaptability to environmental factors. In addition, this review also discusses the effects of mechanical on plant growth and development, and provides ideas for the study of mechanical regulation mechanism of tillering angle in wheat. Consequently, based on the research of other plants and combined with the genetic and mechanical principles, this approach offers novel insights and methodologies for studying tillering in wheat. This interdisciplinary research framework not only enhances our understanding of the mechanisms underlying wheat growth and development but may also uncover the critical factors that regulate tillering angle, thereby providing a scientific foundation for improving wheat yield and adaptability. Full article

Optical microresonators supporting whispering-gallery modes (WGMs) have become a versatile platform for achieving electromagnetically induced transparency-like (EIT-like) phenomena. We theoretically and experimentally demonstrated the tunable coupled-mode induced transparency based on the surface nanoscale axial photonics (SNAP) microresonator. Single-EIT-like and double-EIT-like (DEIT-like) effects with one or more transparent windows are achieved due to dense mode families and tunable resonant frequencies. The experimental results can be well-fitted by the coupled mode theory. An automatically adjustable EIT-like effect is discovered by immersing the sensing region of the SNAP microresonator into an aqueous environment. The sharp lineshape and high slope of the transparent window allow us to achieve a liquid refractive index sensitivity of 2058.8 pm/RIU. Furthermore, we investigated a displacement sensing phenomenon by monitoring changes in the slope of the transparent window. We believe that the above results pave the way for multi-channel all-optical switching devices, multi-channel optical communications, and biochemical sensing processing. Full article

Corn silage is the main feed in the diet of dairy cows and other ruminant livestock. Silage corn feed is very susceptible to spoilage and corruption due to the influence of aerobic secondary fermentation during the silage process. At present, silage quality testing of corn feed mainly relies on the combination of sensory evaluation and laboratory measurement. The sensory review method is difficult to achieve precision and objectivity, while the laboratory determination method has problems such as cumbersome testing procedures, time-consuming, high cost, and damage to samples. In this study, the external sensory quality grading model for different qualities of silage corn feed was established using hyperspectral data. To explore the feasibility of using hyperspectral data for external sensory quality grading of corn silage, a hyperspectral system was used to collect spectral data of 200 corn silage samples in the 380–1004 nm band, and the samples were classified into four grades: excellent, fair, medium, and spoiled according to the German Agricultural Association (DLG) standard for sensory evaluation of silage samples. Three algorithms were used to preprocess the fodder hyperspectral data, including multiplicative scatter correction (MSC), standard normal variate (SNV), and S–G convolutional smoothing. To reduce the redundancy of the spectral data, variable combination population analysis (VCPA) and competitive adaptive reweighted sampling (CARS) were used for feature wavelength selection, and linear discriminant analysis (LDA) algorithm was used for data dimensionality reduction, constructing random forest classification (RFC), convolutional neural networks (CNN) and support vector machines (SVM) models. The best classification model was derived based on the comparison of the model results. The results show that SNV-LDA-SVM is the optimal algorithm combination, where the accuracy of the calibration set is 99.375% and the accuracy of the prediction set is 100%. In summary, combined with hyperspectral technology, the constructed model can realize the accurate discrimination of the external sensory quality of silage corn feed, which provides a reliable and effective new non-destructive testing method for silage corn feed quality detection. Full article