Search Results (2,555)

Mixed steel/polyethylene gas distribution pipelines are increasingly used in congested urban environments where conventional layouts are restricted by existing underground utilities, safety constraints, and site-specific construction conditions. In such systems, buried steel transition sections may become particularly vulnerable to electrical perturbation and corrosion, especially when installed near electrified transport infrastructure. This paper presents a field case study on a recently installed mixed steel/polyethylene gas distribution pipeline located on Lunca Street, Petroșani, Romania, approximately parallel to an electrified railway. Electrical and electrochemical investigations were carried out eight months after installation and included 24 h monitoring of pipe-to-soil potential versus Cu/CuSO₄, 24 h monitoring of alternating current pipe-to-soil voltage, mixed alternating current and direct current signal visualization, and coating insulation resistance measurements. The results showed that alternating current pipe-to-soil voltage was present at all monitored points, with weighted mean values ranging from 0.41 to 1.23 Vrms, while pipe-to-soil potential values ranged from −0.120 to −0.238 V versus Cu/CuSO₄. Although the measured average coating insulation resistance remained relatively high, the combined electrical and electrochemical data indicate that alternating current interference associated with the nearby electrified railway is the most plausible dominant contributing source of the recorded electrical perturbation. Within the analyzed site perimeter, no other nearby electrical infrastructures with comparable interference potential were identified. The highest alternating-current exposure and the least favorable electrochemical values were recorded on the longer metallic segment, showing that metallic length and local configuration strongly influenced the severity of the effect. A mitigation strategy based on polarized electrical decoupling and dedicated grounding is proposed as a practical means of improving electrical safety and reducing corrosion risk in the exposed and buried steel sections. Full article

Electric field distortion remains a fundamental challenge to the operational reliability of HVDC cable accessories, where localized stress intensifies space charge injection and accelerates insulation degradation. While nonlinear conductive composites incorporating functional fillers such as ZnO have shown potential for adaptive field grading, their dynamic interaction with space charge under non-uniform fields has yet to be fully resolved. This study experimentally examines the spatiotemporal evolution of space charge in double-layer dielectric structures comprising linear low-density polyethylene (LLDPE) and ZnO-based nonlinear composites, using the laser-induced pressure pulse (LIPP) technique. Localized field enhancement is introduced via metallic pin defects embedded on the cathode side. Comparative analysis reveals that composites with 40 vol% ZnO microvaristors markedly suppress charge injection compared to conventional semiconductive ethylene-vinyl acetate (EVA) layers. Specifically, interfacial charge accumulation during polarization is reduced by 71%, and residual charge density after depolarization decreases by 88%, leading to a more uniform internal field distribution. These findings provide direct experimental evidence of the field-regulating mechanism of nonlinear composites from the perspective of charge dynamics, supporting their application in intelligent HVDC insulation systems. Full article

Soliton molecules offer practical advantages in high-speed optical communication, precision spectroscopy, and micromachining. In all-normal dispersion fiber lasers, group velocity dispersion broadens the pulse duration, hindering the attainment of the nonlinearity dispersion balance essential for soliton molecule formation. Consequently, the generation of soliton molecules in such lasers is a technically demanding task. Here, we report an all-normal dispersion fiber laser, mode-locked via nonlinear polarization evolution (NPE) and Lyot filtering. By adjusting the intracavity polarization, this setup allows direct control over pulse interactions, enabling the generation of stable soliton molecules, soliton bound states, and multipulse states. A spectral modulation period of up to 0.95 nm is achieved. In addition, different types of solitons, such as soliton singlets and soliton molecules in tightly and loosely bound states, are observed. Full article

Green inclusive growth is a crucial strategic choice for achieving high-quality development in China. This study constructs an indicator system encompassing economic, social, and ecological dimensions to quantitatively measure the level of green inclusive growth across 31 provinces (cities, autonomous regions) in China from 2001 to 2021. The regional disparities, spatiotemporal evolution trends, and convergence characteristics are analyzed using the Dagum Gini coefficient, kernel density function, and σ-convergence and conditional β-convergence. The findings indicate the following: (1) China’s green inclusive growth generally exhibits a “high in the east, low in the west” spatial distribution pattern, with western regions demonstrating a catching-up trend. (2) The regional disparities in China’s green inclusive growth levels are showing a trend of gradual narrowing, though imbalances within eastern and western regions remain relatively pronounced. (3) The kernel density curve of China’s green inclusive growth maintains a “unimodal” shape, with no significant polarization or multi-polar differentiation. (4) Both the national level and the four major regional clusters exhibit σ-convergence and conditional β-convergence in green inclusive growth, demonstrating the effectiveness of policies aimed at reducing regional disparities. (5) Social capital, human capital, technological innovation, material capital investment, foreign direct investment, urbanization level, and government fiscal expenditure all have a positive promoting effect on China’s green and inclusive growth. These results provide decision-making references for promoting coordinated regional development and guiding the inclusive and green transformation of China’s economic growth. Full article

We present a minimal model that isolates the effect of hopping asymmetry on the thermal redistribution of particles in a bilayer graphene system composed of one pristine and one doped layer. The behavior of the system is governed by a single control parameter $\alpha$, which uniformly reduces the intralayer hopping in the doped sheet and defines the only source of spectral asymmetry. Particle conservation fixes the total density at all temperatures, so thermal effects appear exclusively as a redistribution relative to the zero-temperature reference state. This redistribution is quantified by the temperature-induced change of the layer populations, which measures how thermal occupation modifies the particle density in each layer without creating or destroying carriers. With this, the difference between the thermal population corrections of the doped and pristine layers defines the polarization. Thus, thermal excitations probe the asymmetric spectrum, exposing the intrinsic layer imbalance. Results show that for $0<\alpha <1$, band deformation produces unequal occupations between doped and pristine layers, and temperature amplifies this imbalance. The resulting polarization increases monotonically with temperature and systematically with hopping reduction, establishing a direct quantitative link between microscopic spectral asymmetry and macroscopic thermally induced layer imbalance. Full article

Nickel-based superalloy GH3625 is widely used in extreme environments due to its exceptional high-temperature strength and corrosion resistance; however, optimizing its comprehensive performance through precise microstructural control remains a critical challenge. In this study, the effect of withdrawal rate (10–200 μm/s) on the microstructural evolution, mechanical properties, and corrosion resistance of GH3625 alloy was investigated using a liquid-metal-cooled directional solidification system. The microstructural characteristics, elemental segregation, and phase distributions were systematically analyzed via OM, SEM, and EDS, followed by uniaxial tensile and electrochemical polarization tests. The results show that with increasing withdrawal rate, the solid–liquid interface morphology evolves from cellular to cellular-dendritic and finally to fully dendritic. Correspondingly, the primary dendrite arm spacing decreases from 270.4 μm to 100.2 μm, and the secondary dendrite arm spacing decreases from 66.5 μm to 12.3 μm. The area fraction of the detrimental Laves phase first decreases and then increases, reaching a minimum at 100 μm/s. Correspondingly, the yield strength increases from 282 MPa to 409 MPa, and the corrosion resistance is optimized at 100 μm/s. The microstructure–property relationships are discussed based on second-phase strengthening theory and microstructural refinement. This study provides a theoretical basis and practical process windows for optimizing directional solidification parameters to achieve enhanced mechanical and corrosion performance in GH3625 alloy. Full article

This study investigates the dynamic patterns of global financial risk transmission across 11 major economies and four key asset classes (stocks, bonds, foreign exchange, and gold) using daily data spanning 2012 to 2025. To capture the non-linearities of extreme market stress, we construct a multilayer directed network based on least absolute shrinkage and selection operator (LASSO) penalized quantile regression at the 5% lower tail. We estimate tail risk spillovers using a one-year rolling window approach and identify systemically important nodes via an extended PageRank algorithm applied to the resulting adjacency tensors. Empirical results suggest that the rankings of systemically important countries undergo significant re-orderings during crisis periods. We find robust statistical evidence that the Herfindahl–Hirschman Index (HHI) of risk concentration provides forward-looking information regarding structural polarization and systemic fragility. These observed associations remain consistent across alternative quantile thresholds, varying lag lengths, and alternative rolling window specifications. Our results provide granular insights for policymakers monitoring cross-asset contagion and provides a framework for institutional investors to assess potential tail-risk hedging strategies within an increasingly interconnected multilayer architecture. Full article

With the development of the information society, display technologies are evolving toward greater flexibility and advanced performance. Dye-based polyvinyl alcohol (PVA) complex films have gained widespread attention for their excellent resistance to high temperature and humidity. This review systematically summarizes the research progress of dye-based polarizers using PVA as the substrate, focusing on their preparation principles, film properties, and impacts on optical performance. Strategies to enhance optical properties and durability are discussed, including dye molecular optimization, formulation design, control of the dyeing process, and PVA substrate film modification. Notably, improving interfacial interactions between dyes and PVA enhances molecular orientation and stability, while PVA modification improves mechanical properties, water resistance, thermal stability, and flame retardancy. By demonstrating these enhanced comprehensive properties, this review highlights the potential of PVA–based films to serve as high-performance platforms for the development of next-generation multifunctional optical and display materials. Finally, the challenges and development directions of dye-based PVA complex films for optical applications in harsh environments are prospected. This review provides a theoretical basis and technical pathway for the design and development of next-generation high-performance composite polarizers. Full article

Covalent organic frameworks (COFs) have become a research hotspot in photocatalytic materials in recent years due to their highly ordered structures, tunable topologies, and excellent optoelectronic properties. However, the relationship between linker polarity and the direction of optical electron transfer between adjacent structural units remains poorly understood. This study employs density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations to systematically investigate the effects of polarity reversal in imine and acylhydrazone linkers, as well as different fragment models, on the effective optical net electron transfer. To this end, four representative fragment models (K01–K04) were constructed to simulate linear, multi-connected, and branched environments. The results show that, across all models, the direction of the effective optical net electron transfer from phenyl unit (Ph) to UnitB ($Q_{\mathit{P}\mathit{h}\to \mathit{U}\mathit{n}\mathit{i}\mathit{t}\mathit{B}}$) is highly consistent with the polarity direction of the linker. In imine-linked systems, when the dipole moment of the linker aligns with the intrinsic dipole moment direction between Ph and UnitB, the absolute value of $Q_{\mathit{P}\mathit{h}\to \mathit{U}\mathit{n}\mathit{i}\mathit{t}\mathit{B}}$ is significantly enhanced; in acylhydrazone-linked systems, only K02 and K03 exhibit similar behavior, while K01 and K04 show no obvious enhancement. These findings provide important guidance for designing efficient photocatalytic COFs: tuning the linker orientation to match the intrinsic polarity of adjacent structural units can significantly improve the efficiency of optical net electron transfer between them. Full article

Global urbanization has long been hampered by the “metrocentric priority” paradigm, with small towns—core hubs for urban–rural integration—severely undervalued in practical value. Amid China’s transition to high-quality urban–rural integration, unbalanced small town development has become a critical bottleneck for county-level factor flows, demanding systematic research to unlock their strategic value and resolve urban–rural dual predicaments. Existing studies suffer from scientific gaps including unidirectional linear cognition, insufficient complex system thinking, and weak interpretation of regional heterogeneity, remaining at the stage of static correlation description and failing to reveal the two-way reciprocal feedback logic between small towns and urban–rural integration. Meanwhile, the application of complex system theory in urban–rural research is still confined to theoretical narratives, which hinders the advancement of research from descriptive analysis to mechanism interpretation. Taking Henan Province (a typical agricultural and populous province reflecting China’s urban–rural development) as a case, this study builds a “local emergence–global synergy” framework based on complex system theory, establishes a dual indicator system for small towns’ multidimensional performance and county-level urban–rural integration, and integrates spatial statistical analysis, bidirectional regression and coupling coordination models to explore their cross-scale spatiotemporal evolution and reciprocal feedback during 2019–2023. Findings show the following: (1) The multidimensional performance of small towns presents a pattern characterized by polarized expansion of high-value regions and overall improvement of low-value regions, while county-level urban–rural integration evolves into a polycentric structure featured by central dominance and southern growth. (2) There is a significant two-way asymmetric relationship between small towns’ multidimensional performance and county-level urban–rural integration: the positive effect is significantly stronger than the reverse effect, and both direct impacts are significantly weakened after introducing economic variables, indicating that economic development serves as a key transmission channel. (3) The coupling mechanism presents three evolutionary paths with pronounced core–periphery spatial heterogeneity. Grounded in complex system theory, this study constructs a systemic analytical framework of “local emergence of small-town subsystems and global synergy of county-level systems”, verifies the core proposition of two-way interactions between subsystems and the overall system in the urban–rural complex giant system, and enriches the localized application of complex system theory and the urban–rural continuum theory in traditional agricultural regions of China. This study provides a foundational empirical paradigm for the in-depth exploration of nonlinear characteristics and threshold effects in future research. It offers theoretical support for policy formulation of county-level urban–rural integration in traditional agricultural regions of China, and it provides Chinese experiences for the Global South with similar contexts to explore inclusive urbanization pathways, promoting cross-cultural dialogue and practical transformation of urban–rural integration theory. Full article

In this investigation, the nonlinear dust-acoustic waves in the lunar terminator region are studied in a three-component complex plasma comprising Boltzmann-distributed electrons and ions and inertial, cold, negatively charged dust grains. The fluid model is reduced, via the reductive perturbation technique, to a planar Korteweg–de Vries (KdV) equation that governs the evolution of small-amplitude dust-acoustic structures in this environment. Hirota’s direct method is then employed to derive exact multiple-soliton solutions, which allow us to examine the parameter dependence of dust-acoustic solitons and to characterize their overtaking collisions. The analysis shows that the soliton polarity and amplitude are controlled by the equilibrium electron–ion density ratio and the electron-to-ion temperature ratio, and that multi-soliton interactions remain elastic, with only finite phase shifts after collision. In the second part of the study, the planar integer KdV model is generalized to a time-fractional KdV (FKdV) equation to incorporate nonlocal temporal memory effects in the dust-acoustic dynamics. This FKdV equation is analyzed using two analytical approximation schemes: the Tantawy technique, recently proposed as a direct and rapidly convergent approach to fractional evolution equations, and the new iterative method, a widely used high-accuracy scheme in the fractional literature. For both methods, higher-order approximations are constructed, and their absolute and global maximum residual errors are quantified. The results demonstrate that the Tantawy technique provides compact approximations with superior accuracy and stability compared with the new iterative method for the present FKdV-soliton problem. The combined integer- and fractional-analytic framework provides a physically transparent framework for understanding how nonlinearity, dispersion, and fractional memory jointly shape dust-acoustic solitary structures in the electrostatically complex lunar terminator plasma, which is of paramount interest for future lunar missions like Luna-25 and Luna-27. Full article

PVDF has expanded the application of ferroelectric materials in flexible and wearable electronics due to its flexibility, corrosion resistance, ease of processing, and low cost. However, the polarization of ferroelectric polymers is low, with a bottleneck value of 10 µC cm⁻². In this study, flexible ferroelectric composite films comprising Ca₂Nb₃O₁₀ (CNO) nanosheets and PVDF were fabricated via direct ink writing (DIW). By modulating the nozzle-to-substrate height in conjunction with flow-induced shear within the syringe and the application of additional shear force at the nozzle, effective alignment of low-content (2 wt.%) CNO nanosheets dispersed in a highly fluid ink was achieved. The enhanced orientation degree of the CNO nanosheets increased the breakdown strength of the PVDF–CNO composite films to 524 MV/m. Furthermore, the remanent polarization (P_r) was significantly increased by 207% compared to pure PVDF films, reaching a value of 11.6 µC cm⁻². This study provides a simple and efficient DIW-based strategy for improving filler orientation in composites and demonstrates the substantial enhancement in dielectric and ferroelectric properties achievable through such filler alignment. Full article

Atherosclerosis (AS) is a cardiovascular disease characterized by diverse etiological factors and complex pathological mechanisms. In recent years, the role of long non-coding RNAs (lncRNAs) in AS has received increasing attention. Research shows that lncRNAs regulate key biological processes involved in AS, such as vascular endothelial function, proliferation and migration of vascular smooth muscle cells (VSMCs), macrophage polarization, and lipid metabolism, through various mechanisms, including epigenetic modification, transcriptional regulation, and post-transcriptional control. As important components of traditional medicine, Chinese herbal monomers and compounds have been found to modulate the expression of lncRNAs, thereby improving vascular endothelial function, reducing lipid deposition, and inhibiting inflammatory responses, ultimately exerting anti-atherosclerotic effects. This review systematically examines the role of lncRNAs in the disease mechanism of AS and summarizes recent advances in Traditional Chinese Medicine (TCM) interventions targeting lncRNA expression for the treatment of AS, offering new insights and directions for the prevention and management of AS with Chinese medicine. Full article

Titanosilicates are Lewis acid catalysts widely applied in liquid-phase olefin epoxidation; however, in the presence of water, their performance is often limited by structural instability, active-site deactivation, and competing side reactions. This review critically examines hydrophobization strategies—based on controlled reduction in silanol groups or incorporation of organic functionalities—and discusses the experimental approaches used to evaluate surface hydrophobicity, including water adsorption measurements, infrared spectroscopy of silanols, contact angle analysis, and complementary spectroscopic methods. Although direct quantitative comparison among studies is hindered by differences in reaction systems and the lack of standardized catalytic metrics, consistent trends emerge. Lower silanol densities are generally associated with improved preservation of isolated tetrahedral Ti (IV) sites, higher H₂O₂ utilization efficiency, and reduced secondary epoxide ring-opening, leading to enhanced activity and selectivity under comparable conditions. These improvements are attributed to decreased local water activity, suppression of non-productive oxidant decomposition, and stabilization of Ti-peroxo intermediates responsible for direct epoxidation. Incorporation of organic groups produces a similar beneficial effect when introduced in moderate amounts, increasing surface hydrophobicity without significantly perturbing Ti coordination. However, beyond an optimal loading, catalytic performance declines due to pore blockage, diffusion limitations, and partial masking of active sites, revealing a threshold behavior. Fluoride also plays a dual role: when used during synthesis, it influences the insertion and distribution of framework Ti, whereas as a post-treatment, it primarily regulates silanol density and surface polarity while preserving active sites. Finally, hydrophobicity cannot be considered independently, as its impact depends on the solvent, oxidant, olefin nature, and active-site location, which collectively govern activity, selectivity, and catalyst stability. Full article

Bioelectricity plays a vital role in regulating cellular behavior. During the process of tissue repair and regeneration, surface electrical signals provided by biomaterials are found to be helpful. The characteristics of these electrical signals typically vary depending on the specific tissue repair requirements. In this study, zinc oxide nanorod (ZNR) arrays were loaded onto a poly(vinylidene fluoride-trifluoroethylene) (PVTF) substrate via the hydrothermal method. The nanorods were subsequently tilted by uniaxial stretching to form a ZNR/PVTF composite film with in-plane, horizontally aligned ZNRs along the stretching direction on the surface. The distribution of ZNRs created a heterogeneous potential across the PVTF substrate. Under ultraviolet (UV) irradiation, the surface potential of the ZNRs increased by approximately 76 mV due to a photoelectric response, enabling the formation of an adjustable millivolt-level surface potential. After corona polarization, the dipoles within the PVTF were aligned to achieve piezoelectric properties. The existence of oriented surface ZNRs enhanced the piezoelectric response of the ZNR/PVTF film, allowing for volt-level dynamic electrical signals through a force-voltage coupling mechanism. The output voltage increased from 1.32 V (PVTF) to 2.42 V (ZNR/PVTF) under the same 30° bending condition. Moreover, the ZNR/PVTF film exhibited excellent short-term biocompatibility toward bone marrow stem cells (BMSCs). Overall, this work presents an effective strategy for generating multiscale electrical signals through external field applications, demonstrating strong potential for tissue repair and regeneration. Full article