Search Results (101)

Eleutherococcus sessiliflorus is a medicinal shrub widely used in East Asian traditional medicine, yet field-based studies on environmental influences remain limited. In this study, branches from 26 cultivation sites across South Korea were analyzed for relationships among growth traits, soil and climatic conditions, and two major compounds, chlorogenic acid (CGA) and eleutheroside E (EleuE). Growth traits varied widely, with plant height ranging from 1.06 to 4.20 m. CGA content was relatively stable across sites (0.292–0.708 mg/g), while EleuE showed greater variability (0.038–0.264 mg/g). The combined content of CGA and EleuE showed a weak positive correlation with thorn density (r = 0.236, p = 0.037). Plant height and basal diameter were positively correlated with temperature indices (annual average temperature r = 0.410, p < 0.001; annual maximum temperature r = 0.341, p = 0.002), whereas thorn density decreased with soil electrical conductivity, potassium, and magnesium but increased with sand and precipitation. Principal component analysis and correlation networks highlighted distinct clusters separating growth traits from EleuE–environment associations. These findings demonstrate that growth performance in E. sessiliflorus is strongly influenced by thermal regimes, while EleuE accumulation responds to soil texture and light availability, providing an empirical foundation for site-specific cultivation strategies and standardized quality management. Full article

This paper investigates the combustion characteristics of promising decarbonized fuel mixtures—methane/hydrogen (CH₄/H₂) and ammonia/hydrogen (NH₃/H₂)—with a focus on how they interact with external electric fields. The key findings are that these flames possess significant electrochemical properties, allowing for non-intrusive control over their stabilization, shape, and structure using relatively weak electric fields. The research combines experimental techniques like volt-ampere characteristic (VAC) measurement and advanced Hilbert visualization to analyze flame deformation, temperature distribution, and species concentration. Two orientations of the electric field were considered: transverse and longitudinal. For the transverse field, an assessment of the degree of flame deformation was made, indicating the preservation of the laminar combustion regime. In the longitudinal electric field, a change in the combustion stabilization mode was observed, which was detected through visualization and current-voltage characteristics (CVC). Full article

To comprehensively explore the net carbon balance within cropland systems subject to diverse tillage practices (Down-slope cultivation (CK), Subsoiling tillage (SF), Ridge to district field (RF), Ridge to district field + subsoiling tillage (RF-S), Transverse slope planting (TP), Transverse slope planting + ridge to district field (TP-R), Transverse slope planting + subsoiling tillage (TP-S)), a series of well-designed field experiments were meticulously carried out. The CO₂ emission intensity of soil heterotrophic respiration, CH₄ emission intensity, carbon loss in runoff, carbon emissions from farmland materials, dry matter mass and carbon content of different crop organs after harvest were measured for the six different tillage practices. Moreover, the annual and seasonal variations in farmland soil carbon pools under different treatments were analyzed using the net carbon flux (NCF) of the cropland system. The results indicated that, under different tillage practices, the CO₂ emission intensity of soil heterotrophic respiration in each regime across different years generally exhibited a pattern of increasing initially and then decreasing, reaching its peak during the filling stage (pod-setting stage). The RF regime significantly reduced the CO₂ emissions from soil heterotrophic respiration (p < 0.05). The CH₄ emissions in each regime across different years also demonstrated an overall tendency of rising initially and subsequently declining, with an alternating positive–negative pattern, reaching its peak during the jointing stage (branching stage). The SF regime significantly decreased the CH₄ emissions (p < 0.05). The regimes with cross-slope tillage significantly reduced the carbon loss in runoff (p < 0.05). Throughout every year, the NPP of crops under the TP-S regime attained its peak value (p < 0.05). The RF regime effectively increased the NPP of crops, reduced the soil heterotrophic respiration CO₂ emissions and the carbon loss in runoff, and its NCF value reached the maximum level (p < 0.05), presenting a weak carbon “source”. Overall, ridged-field (RF) effectively curbs greenhouse gas emissions, boosts farmland carbon sequestration, and mitigates soil fertility decline. Full article

We numerically investigate instabilities toward bimeron crystals and multiple-Q magnetic states induced by an in-plane external magnetic field in centrosymmetric magnets with magnetic anisotropy. By focusing on the interplay between easy-plane single-ion anisotropy and bond-dependent anisotropy originating from relativistic spin–orbit coupling in crystalline environments, we construct the magnetic phase diagram of an effective spin model with competing momentum-resolved interactions using simulated annealing. Our analysis reveals that the bimeron crystal is stabilized within the regime of weak bond-dependent anisotropy, independent of its sign, whereas increasing the strength of bond-dependent anisotropy drives the system into a topologically trivial triple-Q magnetic state. The obtained bimeron crystal is characterized by finite scalar spin chirality and triple-Q modulations in both the in-plane and out-of-plane spin components. These findings demonstrate that centrosymmetric easy-plane magnets provide a fertile platform for realizing nontrivial topological spin textures without relying on Dzyaloshinskii–Moriya interactions, thereby opening new avenues for inducing emergent topological transport phenomena in centrosymmetric materials. Full article

The basic structural concepts in the study of monatomic fluids at equilibrium are presented in this entry. The scope encompasses both the classical and the quantum domains, the latter concentrating on the diffraction and the zero-spin boson regimes. The main mathematical objects for describing the fluid structures are the following n-body functions: the correlation functions in real space and their associated structure factors in Fourier space. In these studies, the theory of linear response to external weak fields, involving functional calculus, and Feynman’s path integral formalism are the key conceptual ingredients. Emphasis is placed on the physical implications when going from the classical domain (limit of high temperatures) to the abovementioned quantum regimes (low temperatures). In the classical domain, there is only one class of n-body structures, which at every n level consists of one correlation function plus one structure factor. However, the quantum effects bring about the splitting of the foregoing class into three path integral classes, namely instantaneous, total thermalized-continuous linear response, and centroids; each of them is associated with the action of a distinct external weak field and keeps the above n-level structures. Special attention is given to the structural pair level $n=2$, and future directions towards the complete study of the quantum triplet level $n=3$ are suggested. Full article

Desert steppe ecosystems, characterized by water limitation and high sensitivity to global climate change and anthropogenic disturbance drivers, experience profound alterations in carbon (C) cycling processes driven by the multiplicative interactions among grassland grazing, altered precipitation regimes, and elevated atmospheric nitrogen deposition. However, how historical grazing legacies modulate ecosystem responses to concurrent changes in nitrogen deposition and precipitation regimes remains poorly resolved. To address this, we conducted a field experiment manipulating water and nitrogen addition across grazing intensities (no grazing, light grazing, moderate grazing, heavy grazing) in a Stipa breviflora desert steppe. Over three consecutive growing seasons (2015–2017), we continuously monitored net ecosystem CO₂ exchange (NEE), ecosystem respiration (ER), and gross ecosystem production (GEP) to quantify ecosystem CO₂ fluxes under these interacting global change drivers. Results revealed that water and nitrogen addition did not alter seasonal CO₂ flux dynamics across grazing intensities. Light grazing enhanced ecosystem C sink capacity, whereas heavy grazing reduced NEE and GEP, diminishing C sink strength. Water addition significantly increased CO₂ fluxes, strongly correlated with soil moisture. Nitrogen addition exerted a weak C source effect in a water-deficient year but enhanced the C sink in a water-rich year. Nitrogen plus water addition significantly boosted C sink potential, though this effect diminished along the grazing pressure gradient. Our findings demonstrate that the impacts of climate change on soil C fluxes in desert steppes are mediated by historical grazing intensity. Future manipulative experiments should explicitly incorporate grazing legacy effects, and integrate this factor into C models to generate reliable predictions of grassland C dynamics under global change scenarios. Full article

This study presents a comparative benchmarking analysis of G20 nations’ agri-food competitiveness across five critical pillars: food security and nutrition, trade and geopolitics, environmental sustainability, fiscal regimes, and entrepreneurship support. Using a structured benchmarking framework with 13 performance indicators sourced from internationally recognized datasets, the research delivers a comprehensive evaluation of national agri-food systems. The analysis reveals significant disparities in transparency, policy coherence, and investment in innovation across member states. Countries such as the United States, Germany, and Australia emerge as leaders, driven by integrated policy frameworks, trade surpluses, and sustainable production practices. Others fall behind due to import dependence, fragmented governance, or weak innovation ecosystems. Canada performs consistently in trade metrics but is hindered by high emissions intensity, infrastructure constraints, and a lack of a cohesive national food strategy. Theoretically, this work contributes to the emerging field of agri-food system diagnostics by operationalizing a cross-pillar benchmarking methodology applicable at the national level. Practically, it offers policymakers a decision-support tool for identifying structural gaps and setting reform priorities. The framework enables governments, trade partners, and multilateral institutions to design targeted interventions aimed at boosting food system resilience, economic competitiveness, and sustainability in an era of rising geopolitical and environmental volatility. Full article

This study investigates pre-seismic ionospheric anomalies preceding the 2023 Jishishan Ms6.2 earthquake using total electron content (TEC) data derived from BDS geostationary orbit (GEO) satellites. Multi-scale analysis integrating Butterworth filtering and wavelet transforms resolved TEC disturbances into three distinct frequency regimes: (1) high-frequency perturbations (0.56–3.33 mHz) showed localized disturbances (amplitude ≤ 4 TECU, range < 300 km), potentially associated with near-field acoustic waves from crustal stress adjustments; (2) mid-frequency signals (0.28–0.56 mHz) exhibited anisotropic propagation (>1200 km) with azimuth-dependent N-shaped waveforms, consistent with the characteristics of acoustic–gravity waves (AGWs); and (3) low-frequency components (0.18–0.28 mHz) demonstrated phase reversal and power-law amplitude attenuation, suggesting possible lithosphere–atmosphere–ionosphere (LAI) coupling oscillations. The stark contrast between near-field residuals and far-field weak fluctuations highlighted the dominance of large-scale atmospheric gravity waves over localized acoustic disturbances. Geometry-based velocity inversion revealed incoherent high-frequency dynamics (5–30 min) versus anisotropic mid/low-frequency traveling ionospheric disturbance (TID) propagation (30–90 min) at 175–270 m/s, aligning with theoretical AGW behavior. During concurrent G1-class geomagnetic storm activity, spatial attenuation gradients and velocity anisotropy appear primarily consistent with seismogenic sources, providing insights for precursor discrimination and contributing to understanding multi-scale coupling in seismo-ionospheric systems. Full article

Arginine plays a critical role in biomolecular interactions due to its guanidinium side chain, which enables multivalent electrostatic and hydrogen bonding contacts. In this study, atomistic molecular dynamics simulations were conducted across a broad concentration range (26–605 mM) to investigate the thermodynamic and structural features of arginine self-assembly in aqueous solution. Key observables—including hydrogen bond count, radius of gyration, contact number, and isobaric heat capacity—were analyzed to characterize emergent behavior. A three-regime aggregation pattern (dilute, cooperative, and saturated) was identified and quantitatively modeled using the Hill equation, revealing a non-linear transition in clustering behavior. Spatial analyses were supplemented with trajectory-based clustering and radial distribution functions. The heat capacity peak observed near 360 mM was interpreted as a thermodynamic signature of hydration rearrangement. Trajectory analyses utilized both GROMACS tools and the MDAnalysis library. While force field limitations and single-replica sampling are acknowledged, the results offer mechanistic insight into how arginine concentration modulates molecular organization—informing the understanding of biomolecular condensates, protein–nucleic acid complexes, and the design of functional supramolecular systems. The findings are in strong agreement with experimental observations from small-angle X-ray scattering and differential scanning calorimetry. Overall, this work establishes a cohesive framework for understanding amino acid condensation and reveals arginine’s concentration-dependent behavior as a model for weak, reversible molecular association. Full article

Papapetrou showed that the covariant derivative of a Killing vector field satisfies Maxwell’s equations in vacuum. Papapetrou’s result is extended, in this article, and it is shown that the covariant derivative of a Killing vector field satisfies Maxwell’s equations in non-vacuum backgrounds as well if one allows electromagnetic currents of purely geometric origin. It is then postulated that every Killing vector field gives rise to a physical electromagnetic field and, in a non-vacuum background, a physical electromagnetic current—hereafter called Killing electromagnetic field and Killing electromagnetic current, respectively. It is shown that the Killing electromagnetic field of the flat FLRW (Friedmann–Lema$\hat{\mathrm{i}}$tre–Robertson–Walker) universe comprises a Killing magnetic field and a rotational Killing electric field; an upper bound on the Killing magnetic field is derived, and it is found that the upper bound is consistent with the current observational bounds on the cosmic magnetic field. Next, the time-like Killing vector of the Schwarzschild spacetime is shown to give rise to a radial Killing electric field. It is also shown that in the weak field regime—and far from the matter distribution—the back reaction of the radial Killing electric field changes the Schwarzschild metric to the Reissner–Nordström metric, establishing a partial converse of Wald’s result. Drawing upon Rainich’s work on Rainich–Riemann manifolds, the etiological question of how a physical electromagnetic field can arise out of geometry is discussed; it is also argued that detection of the Killing electric field of flat FLRW spacetime may be within the current experimental reach. Finally, this article discusses the relevance of Killing electromagnetic currents and the aforementioned transmutation of Schwarzschild spacetime to Reissner–Nordstrom spacetime, to Misner and Wheeler’s program of realizing “charge without charge”. Full article

Snow avalanches occur in snow-covered highland mountains and represent one of the most significant natural hazards pertaining to the field of geoscience. Although some insight into the formation of avalanches has been provided, a comprehensive overview or critical review of the latest research is currently lacking. This paper reviews recent advances on the formation process of dry slab avalanches and provides a guiding framework for further research. The formation of avalanches is the consequence of a series of fracture processes in the snowpack, which is usually induced by the failure of a weak layer underlying a snow slab layer. The parameters at each stage of avalanches’ formation are reviewed from theoretical, experimental and simulation perspectives. In terms of the onset of crack propagation, the understanding of the mechanical process has gone through a transition from shear theory, to the anticrack model and supershear. The critical length shows divergent trends with snowpack parameters and slope angles, and there is a lack of consensus in different models. The specific fracture energy is also an essential component in determining fracture propagation. Within cracks’ dynamic propagation, the crack propagation speed includes both the sub-Rayleigh regime and supershear. The crack speed exceeds the shear wave speed in the supershear mode. When the crack propagation reaches a specific distance, the slab undergoes a tensile fracture and the cracking’s arrest. The numerical simulation allows a complete reproduction of the initial failure, the crack’s dynamic propagation and slab fracture. In the future, a unified model is necessary through refining the formative mechanism and integrating it with the avalanche flow. This work offers a comprehensive understanding of the mechanics of the formation and release of avalanches, useful for both modelers and experimentalists. Full article

Quasibound states in the continuum (qBICs) have aroused much attention as a feasible stage to investigate optical strong coupling due to their extremely high-quality factors (Q-factors) and extraordinary electromagnetic field enhancement. However, current demonstrations of strong coupling based on qBICs have primarily focused on the visible spectral range, while research in the near-infrared (NIR) regime remains scarce. In this work, we design a nanograting metasurface supporting Friedrich–Wintgen bound states in the continuum (FW BICs). We demonstrate that FW BIC formation stems from destructive interference between Fabry–Pérot cavity modes and metal–dielectric hybrid guided-mode resonances. To investigate the qBIC–exciton coupling system, we simulated the interaction between MoTe₂ excitons and nanograting metasurfaces. A Rabi splitting of 55.4 meV was observed, which satisfies the strong coupling criterion. Furthermore, a chiral medium layer is modeled inside the nanograting metasurface by rewriting the weak expression and boundary conditions. A mode splitting of the qBIC–chiral medium system in the circular dichroism (CD) spectrum demonstrates that the chiral response successfully transferred from the chiral medium layer to the exciton–polaritons systems through strong coupling. In comparison to the existing studies, our work demonstrates a significantly larger CD signal under the same Pascal parameters and with a thinner chiral dielectric layer. Our work provides a new ideal platform for investigating the strong coupling based on quasibound states in the continuum, which exhibits promising applications in near-infrared chiral biomedical detection. Full article

Wellbore instability is a major constraint in large-scale shale oil extraction. This study focuses on the shale–sandstone interbedded shale oil reservoirs in the Chang 7 area, delving into the evolutionary principles governing wellbore stability in horizontal drilling operations within these formations. A geological feature analysis of shale–sandstone reservoir characteristics coupled with rigorous mechanical experimentation was undertaken to investigate the micro-mechanisms underpinning wellbore instability. The Mohr–Coulomb failure criterion applicable to sandstone and the multi-weakness planes failure criterion of shale were integrated to analyze the stress distribution of surrounding rocks within horizontal wells, facilitating the computation of collapse pressure and fracture pressure. A finite element model of wellbore stability in shale–sandstone horizontal drilling was established, and then we conducted a comprehensive analysis of the impacts of varying elastic moduli, Poisson’s ratio, and in-situ stress on wellbore stability. The findings reveal that under varying confining pressures, the predominant failure mode observed in most sandstone samples is characterized by inclined shear failure, coupled with a reduced incidence of crack formation. The strength of shale escalates proportionally with increasing confining pressure, resulting in a reduced susceptibility to failure along its inherent weak planes. This transition is characterized by a gradual shift from the prevalent mode of longitudinal splitting towards inclined shear failure. As the elastic modulus of shale rises, the discrepancy between circumferential and radial stresses decreases. In contrast, with the increasing elastic modulus of sandstone, the gap between circumferential and radial stresses widens, potentially inducing potential instabilities in the wellbore. An increase in sandstone’s Poisson’s ratio corresponds to a proportional increase in the difference between circumferential and radial stresses. Under reverse fault stress regimes, wellbore collapse and instability are predisposed to occur. Calculations of collapse pressure and fracture pressure reveal that the safety density window is minimized at the interface between shale and sandstone, rendering it susceptible to wellbore instability. These research findings offer significant insights for the investigation of wellbore stability in interbedded shale–sandstone reservoirs contributing to the academic discourse in this field. Full article

Stem cells therapies offer a promising approach in translational oncology, as well as in regenerative medicine due to the tropism of these cells to the damage site. To track the distribution of stem cells, the latter could be labeled by MRI-sensitive superparamagnetic (SPM) iron oxide nanoparticles. In the current study, magnetic properties of the magnetic nanoparticles (MNPs) incorporated into the bone marrow-derived fetal mesenchymal stem cells (FetMSCs) were evaluated employing nonlinear magnetic response measurements. Synthesized dextran-coated iron oxide nanoparticles were additionally characterized by X-ray diffraction, transmission electron microscopy, and dynamic light scattering. The MNP uptake by the FetMSCs 24 h following coincubation was studied by longitudinal nonlinear response to weak alternating magnetic field with registration of the second harmonic of magnetization. Subsequent data processing using a formalism based on the numerical solution of the Fokker–Planck kinetic equation allowed us to determine magnetic and dynamic parameters and the state of MNPs in the cells, as well as in the culture medium. It was found that MNPs formed aggregates in the culture medium; they were absorbed by the cells during coincubation. The aggregates exhibited SPM regime in the medium, and the parameters of the MNP aggregates remained virtually unchanged in the cells, indicating the preservation of the aggregation state of MNPs inside the cells. This implies also the preservation of the organic shell of the nanoparticles inside FetMSCs. The accumulation of MNPs by mesenchymal stem cells gradually increased with the concentration of MNPs. Thus, the study confirmed that the labeling of MSCs with MNPs is an effective method for subsequent cell tracking as incorporated nanoparticles retain their magnetic properties. Full article

The simulation of the transport properties of confined, low-dimensional fluids can be performed efficiently by means of multi-particle collision (MPC) dynamics with suitable thermal-wall boundary conditions. We illustrate the effectiveness of the method by studying the dimensionality effects and size-dependence of thermal conduction, since these properties are of crucial importance for understanding heat transfer at the micro–nanoscale. We provide a sound numerical evidence that the simple MPC fluid displays the features previously predicted from hydrodynamics of lattice systems: (1) in 1D, the thermal conductivity $\kappa$ diverges with the system size L as $\kappa \sim L^{1/3}$ and its total heat current autocorrelation function $C\left(t\right)$ decays with the time t as $C\left(t\right)\sim t^{-2/3}$; (2) in 2D, $\kappa$ diverges with L as $\kappa \sim \ln \left(L\right)$ and its $C\left(t\right)$ decays with t as $C\left(t\right)\sim t^{-1}$; (3) in 3D, its $\kappa$ is independent with L and its $C\left(t\right)$ decays with t as $C\left(t\right)\sim t^{-3/2}$. For weak interaction (the nearly integrable case) in 1D and 2D, there exists an intermediate regime of sizes where kinetic effects dominate and transport is diffusive before crossing over to the expected anomalous regime. The crossover can be studied by decomposing the heat current in two contributions, which allows for a very accurate test of the predictions. In addition, we also show that, upon increasing the aspect ratio of the system, there exists a dimensional crossover from 2D or 3D dimensional behavior to the 1D one. Finally, we show that an applied magnetic field renders the transport normal, indicating that pseudomomentum conservation is not sufficient for the anomalous heat conduction behavior to occur. Full article