Search Results (1,156)

We investigate the structure of correlation singularities for the Laguerre–Gauss beam of order $n=0$ and $m=2$ in the transverse plane during the propagation of the beam in the beam-wander model. We explicitly derive analytical expressions for the cross-spectral density of the corresponding beam order and the analytic expressions representing the singular behavior. We also verify that the singular points disappear at certain z values and reappear at other z values as shown in the previous numerical study. We investigate the dependence of the absolute value of the complex degree of coherence $\mu$ on the parameter $\delta$ of the beam-wander model during the propagation of the Laguerre–Gauss beam in the corresponding order. The complex degree of coherence depends not only on $\delta$ but also on the relative positions of two transverse observation points ${\mathit{\rho }}_1$ and ${\mathit{\rho }}_2$, as well as on the propagation variable z for the fixed values of the beam waist and the wavelength of the Laguerre–Gauss beam. Experiments on $\mu$ can demonstrate the range of the applicability of the beam-wander model in the turbulent atmosphere. Finally, we examine the orbital angular momentum flux density of the beam and confirm that the general behaviors of the previous studies also hold for $m=2$. Full article

Sintering is a key processing route to consolidate nuclear fuel powders into dense compacts, yet the atomic-level mechanisms governing the sintering of actinide compounds remain poorly understood. Herein, the sintering kinetics and structural evolution of uranium mononitride (UN) nanoparticles are investigated using molecular dynamics (MD) simulations. A three-stage sintering mechanism is revealed based on the symmetrical dual nanoparticle models: initial surface diffusion and neck formation, followed by interface amorphization driven by shear stress, and finally, lattice reconstruction and recrystallization, which peak during the cooling process. By studying the effect of sintering temperature, we find that near-complete densification with good structural integrity is achieved at 1900 K, whereas further increasing the temperature (to 2000 K) led to microstructural instability and near-overburning. In addition, holding time exhibits a clear saturation effect, with variations in holding time showing no significant impact on sintering morphology or density. Therefore, sintering temperature is the dominant factor determining sintering quality. The atomic level insights provided by this work reveal the nonlinear temperature dependence and time saturation effect of UN nanoparticle sintering, and provide a theoretical basis for the prediction, design, and optimization of nuclear fuel sintering process. Full article

Laser Wireless Power Transmission (LWPT), as a revolutionary energy supply technology, holds broad application prospects in areas such as drone endurance, space solar energy transmission, and power supply in remote regions. The core efficiency of this technology primarily depends on the energy concentration and uniformity of the light spot at the receiving end. Through systematic simulation analysis, this paper studies the spot uniformity and energy transmission efficiency of Gaussian beams, vortex beams, and flat-topped beams under different atmospheric conditions (turbulence intensity, visibility) and transmission distances. By quantitatively analyzing key indicators such as light spot non-uniformity and power density within the bucket, the advantages and disadvantages of the three beam types are comprehensively evaluated. The results indicate that the flat-topped beam is the optimal choice for short-distance laser energy transfer under favorable atmospheric conditions, while the vortex beam exhibits the best overall performance and robustness in medium and strong turbulence transmission environments. This study provides a theoretical basis for beam selection in different application scenarios. Full article

Green total factor productivity (GTFP), as an important indicator considering both economic development and environmental protection, has prompted countries around the world to actively explore ways to improve it in the context of the global transition to a green economy. The Low-Carbon City Policy (LCCP) implemented by the Chinese government, along with the National Big Data Comprehensive Pilot Zone Policy (NBDCPZ), which serve as key carriers of green regulation and digital innovation, respectively, play an important role in improving green total factor productivity (GTFP) and achieving high-quality economic development. This study aims to deeply explore whether there is a collaborative enabling effect of the Low-Carbon City Policy (LCCP) and the National Big Data Comprehensive Pilot Zone Policy (NBDCPZ) on green total factor productivity (GTFP) and to reveal the internal mechanism by which they improve GTFP through green technological innovation and industrial agglomeration. Specifically, based on the panel data of 269 prefecture-level cities in China from 2006 to 2022, a “dual-pilot” policy is constructed through LCCP and NBDCPZ, and a multi-period difference-in-differences model (DID) is used to evaluate the collaborative effect of the “dual-pilot” policy on GTFP. The results show that the “dual-pilot” policy has a significant collaborative effect on green total factor productivity (GTFP), and its enabling effect is more obvious than that of the “single-pilot” policy. These conclusions still hold after a series of endogeneity and robustness tests. Mechanism analysis shows that the “dual-pilot” policy can also improve green total factor productivity (GTFP) through green technological innovation and industrial agglomeration. Heterogeneity analysis reveals that the collaborative enabling effect of the “dual-pilot” policy is influenced by geographical location and population density. Specifically, the “dual-pilot” policy significantly promotes green total factor productivity (GTFP) in coastal cities and those with high population density. These research results provide a scientific basis for formulating green development policies in China and other countries, as well as a direction for subsequent research on the collaborative enabling effect of multiple policies. Full article

Compared to traditional marine productivity, marine new-quality productivity (MNQP) is composed of advanced productive forces driven by the deepening application of new technologies, is characterized by the rapid emergence of new industries, new business models, and new modes of operation, and is marked by a substantial increase in total factor productivity in the marine economy. It has, therefore, become a new engine and pathway for China’s development into a maritime power. The main research approaches and conclusions of this paper are as follows: ① Using a combined order relation analysis method–Entropy Weight Method (G1-EWM) weighting method that integrates subjective and objective factors, we measured the development level of China’s MNQP from 2006 to 2021 across two dimensions: “factor structure” and “quality and efficiency”. The findings indicate that China’s MNQP is developing robustly and still holds considerable potential for improvement. ② Utilizing Gaussian Kernel Density Estimation and Spatial Markov Chain analysis to examine the dynamic evolution of China’s MNQP, the study identifies breaking the low-end lock-in of MNQP as crucial for accelerating balanced development. Spatial imbalances in China’s MNQP may exist both at the national level and within the three major marine economic zones. ③ To further examine potential spatial imbalances, Dagum Gini decomposition was employed to assess regional disparities in China’s MNQP. The DER polarization index and EGR polarization index were used to analyze spatial polarization levels, revealing an intensifying spatial imbalance in China’s MNQP. ④ Finally, geographic detectors were employed to identify the factors influencing spatial imbalances in China’s MNQP. Results indicate that these imbalances result from the combined effects of multiple factors, with marine economic development emerging as the core determinant exerting a dominant influence. The core conclusions of this study provide theoretical support and practical evidence for advancing the enhancement of China’s MNQP, thereby contributing to the realization of the goal of building a maritime power. Full article

This study critically examines the relationship between neoliberal environmentalism and green certification systems by quantitatively analyzing LEED-certified buildings in Istanbul. It explores how green building practices intersect with market-oriented urban environmental governance through an analysis of the spatial distribution, ownership types, access typologies, and functional uses of certified projects. The findings reveal that nearly 80% of LEED-certified buildings in Istanbul are developed by private companies, and that 88.6% of these buildings are private spaces with limited or no public access. These projects are predominantly high-end offices or residential developments, with a large share holding “Gold” certification. Correlation analysis identifies an inverse relationship between LEED project density and socioeconomic vulnerability, raising critical questions about spatial justice and equity in access to sustainable urban environments. This study contributes to the growing body of critical literature that frames urban sustainability not merely as a technocratic checklist of standards but as a normative and contested terrain in which justice, equity, and inclusivity must be placed at the center. Full article

Metamaterials (MMs)-based terahertz (THz) biosensors hold promise for clinical diagnosis, featuring label-free operation, simple, rapid detection, low cost, and multi-cell-type discrimination. However, liquid around cells causes severe interference to sensitive detection. Most existing MMs-based cell biosensors detect dead cells without culture medium (losing original morphology), hindering stable, sensitive multi-cell discrimination. Here, a terahertz biosensor composed of a microcavity and MMs can be used to detect and discriminate multiple cell types within suspension. Its detection mechanism relies on cellular size (radius)/density in suspension, which induces effective permittivity (ε_eff) differences. By designing MMs’ split rings with luxuriant gaps, the biosensor achieves a theoretical sensitivity of ~328 GHz/RIU, enabling sensitive responses to suspended cells. It shows a robust, increasing frequency shift (610–660 GHz) over 72 h of cell apoptosis. Moreover, it discriminates nerve cells, glioblastoma (GBM) cells, and their 1:1 mixture with obviously distinct frequency responses (~650, ~630, ~620 GHz), which suggests effective and reliable multi-cell-type recognition. Overall, this study and its measurement method should pave the way for metamaterial-based terahertz biosensors for living cell detection and discrimination, and this technology may inspire further innovations in tumor investigation and treatment. Full article

Background: Artificial intelligence (AI) is transforming medicine by supporting data-driven diagnosis, prognosis, and personalized care. In rheumatology, AI applications are rapidly expanding in imaging, disease monitoring, and therapeutic decision support. This review aimed to summarize current evidence on AI in osteoporosis and chronic inflammatory rheumatic diseases, with a focus on methodological robustness and clinical applicability. Methods: A narrative review was conducted following SANRA criteria. PubMed and the Cochrane Library were systematically searched for studies published between January 2015 and July 2025 using MeSH terms and free-text keywords related to AI, osteoporosis, and inflammatory rheumatic diseases. A total of 323 articles were included. Results: Machine learning and deep learning models show strong performance in osteoporosis for predicting bone mineral density (BMD), bone loss, and fractures. In chronic inflammatory rheumatic diseases, AI improves imaging interpretation, particularly for sacroiliitis. AI tools also demonstrate potential for predicting disease risk and activity, diagnostic support and treatment response. Hybrid models combining imaging, clinical, and biological data appear particularly promising. However, most studies rely on retrospective single-center datasets, with limited external validation, suboptimal explainability, and scarce evidence of real-world implementation. Conclusions: AI holds significant promise for advancing diagnosis and personalized management in osteoporosis and rheumatic diseases. However, major challenges persist, including heterogeneous data quality, inconsistent methodological reporting, limited clinical validation, and barriers to integration into routine practice. Bridging the gap between algorithmic performance and clinical impact will require prospective studies, robust validation frameworks, and strategies to build trust among clinicians and patients. Full article

A new family of highly uniform, cubic-shaped Cu₃VS_xSe_4−x (CVSSe; 0 ≤ x ≤ 4) nanocrystals based on earth-abundant materials with intermediate bandgaps (IB) in the visible range is reported, synthesized via a hot-injection method. The IB transitions and optical band gap of the novel CVSSe nanocrystals are investigated using ultraviolet-visible spectroscopy, revealing tunable band gaps that span the visible and near-infrared regimes. The composition-dependent relationships among the crystal phase, optical band gap, and photoluminescence properties of the novel IB semiconductors with progressive substitution of Se by S are examined in detail. High-resolution transmission electron microscopy and scanning electron microscopy characterization confirm the high crystallinity and uniform size (~19.7 nm × 17.2 nm for Cu₃VS₄) of the cubic-shaped nanocrystals. Density functional theory (DFT) calculations based on virtual crystal approximation support the experimental findings, showing good agreement in lattice parameters and band gaps across the CVSSe series and lending confidence that the targeted phases and compositions have been successfully realized. A current conversion efficiency, i.e., incident photon-to-current efficiency, of 14.7% was achieved with the p-type IB semiconductor Cu₃VS₄. These novel p-type IB semiconductor nanocrystals hold promise for enabling thin film solar cells with efficiencies beyond the Shockley–Queisser limit by allowing sub-band-gap photon absorption through intermediate-band transitions, in addition to the conventional direct-band-gap transition. Full article

Boron is a promising fuel, but its oxide layer impedes combustion. Alloying boron with other high-energy metals can significantly enhance its combustion performance. In this study, we sintered highly reactive lithium-containing Mg-Al-Li-B alloys using magnesium, aluminum–lithium alloy, and boron powder as raw materials. The effects of sintering temperature and holding time on the microstructure were investigated, and the combustion heat value and oxidation resistance of the alloy were tested. Results indicate that sintering temperature significantly influences phase formation: increasing temperature boosts phase content while reducing metallic phases, with 1100 °C identified as the optimal sintering temperature. Holding time had no discernible impact on the phase composition or combustion heat value of the sintered alloy. Alloying enhances material density, thereby increasing volumetric heat value. Thermal oxidation performance tests demonstrate that Li addition significantly lowers the alloy’s oxidation reaction temperature and activation energy, enhancing its reactivity. This high-heat-value, highly reactive alloy holds significant potential for application in pyrotechnics and propellants. Full article

Soils represent the largest reservoir of organic carbon (OC) in terrestrial ecosystems, storing approximately 1500 Gt C. Forest and grassland ecosystems contribute 39% and 34% to global terrestrial carbon stocks, with soils holding about 44% and 89% of forest and grassland carbon, respectively. Land-use changes, such as the conversions between forest and grassland ecosystems, can strongly influence soil carbon accumulation, though the direction and magnitude remain uncertain. Comparative data from paired-plot studies of forest and grassland soils are still limited. In this study, we conducted pairwise comparisons of total OC and total nitrogen (TN) stocks in mature forest and climax grassland soils along a climatic and pedogenic gradient encompassing Retisols, Luvisols, and Chernozems. Relationships between OC and TN stocks (0–10 cm) and soil physicochemical properties—OC and TN contents, bulk density, pH, clay content, and humus fractional composition, as well as biological indicators—the abundance of culturable fungi and bacteria, microbial biomass carbon, potential metabolic activity, and activities of laccase and dehydrogenase, were evaluated. Strong positive correlations were found between OC and TN stocks and OC and TN contents (r = 0.62–0.99), pH (r = 0.79–0.81), clay content (r = 0.70–0.87), and the fraction of humic acids bound with calcium (r = 0.73). OC stocks also correlated strongly with dehydrogenase activity (r = 0.85–0.95). At 0–10 cm depth, OC stocks were higher in grassland soils than in forest soils by factors of 1.6–1.7 in Retisols and 1.4–1.5 in Chernozems. Similarly, TN stocks were 1.6–2.0 times greater in grasslands across all soil types. Community-level physiological profiling revealed higher potential metabolic activity in forest soils compared with grasslands, with the strongest differences in Retisols and Luvisols, while contrasts were attenuated in Chernozems. Overall, the results highlight the fundamental role of organo-mineral interactions and calcium binding in OC stabilization, as well as the likely involvement of dehydrogenase activity in the biogenic formation of calcium carbonates that contribute to this process. Full article

To achieve the resource utilization of solid waste generated from the papermaking process, this study proposes a method for preparing sintered bricks by partially replacing shale with paper-mill sludge. The brick samples were prepared through a process of mixing in proportion, extrusion molding, drying and roasting. An orthogonal experimental design was employed to investigate the effects of sintering temperature, raw material proportion, and holding time on the physical and mechanical properties of the bricks. The results indicate that the optimal technological parameters are determined as follows: a raw material proportion (paper-mill sludge:shale) of 30:70, a sintering temperature of 1050 °C, a holding time of 8 h, and a heating rate of 1 °C/min. Under these conditions, the produced paper-mill sludge–shale bricks exhibited a compressive strength of 14.91 MPa, a flexural strength of 8.26 MPa, a water absorption of 12.7%, and a bulk density of 1712 kg/m³. These performance indicators meet the requirements for Grade MU10 specified in the national standard Sintered Common Bricks (GB/T 5101-2017). Regarding microscopic analysis, the SEM results reveal significant liquid-phase sintering within the brick body at 1050 °C, while XRD analysis confirmed the presence of stable quartz, alumina, and hematite phases, which contribute to enhancing the mechanical properties and densification of the bricks. Full article

Populus euphratica is a key constructive species in desert ecosystems and plays a vital role in maintaining their stability. However, effective automated methods for accurately delineating its distribution outlines are currently lacking. This study used the mainstream area of the Tarim River as a case study and proposed a technical solution for identifying the distribution outline of Populus euphratica using multi-source thematic classification data. First, cropland thematic data were used to optimize the accuracy of the Populus euphratica classification raster data. Discrete points were removed based on density to reduce their impact on boundary identification. Then, a hierarchical identification scheme was constructed using the alpha-shape algorithm to identify the boundaries of high- and low-density Populus euphratica distribution areas separately. Finally, the outlines of the Populus euphratica distribution polygons were smoothed, and the final distribution outline data were obtained after spatial merging. The results showed the following: (1) Applying a closing operation to the cropland thematic classification data to obtain the distribution range of shelterbelts effectively eliminated misclassified pixels. Using the kd-tree algorithm to remove sparse discrete points based on density, with a removal ratio of 5%, helped suppress the interference of outlier point sets on the Populus euphratica outline identification. (2) Constructing a hierarchical identification scheme based on differences in Populus euphratica density is critical for accurately delineating its distribution contours. Using the alpha-shape algorithm with parameters set to α = 0.02 and α = 0.006, the reconstructed geometries effectively covered both densely and sparsely distributed Populus euphratica areas. (3) In the morphological processing stage, a combination of three methods—Gaussian filtering, equidistant expansion, and gap filling—effectively ensured the accuracy of the Populus euphratica outline. Among the various smoothing algorithms, Gaussian filtering yielded the best results. The equidistant expansion method reduced the impact of elongated cavities, thereby contributing to boundary accuracy. This study enhances the automation of Populus euphratica vector data mapping and holds significant value for the scientific management and research of desert vegetation. Full article

The possibility of transforming debris from a ceramic clinker into high quality foam granulate is discussed. The foaming process, which was carried out at temperatures 150–200 °C higher than the production process, was studied by HSM and DTA-TG coupled with MS. Phase and structural transformations were investigated by XRD and SEM, respectively. The results highlight that the foaming mechanism is related to the release of oxygen due to a reduction in Fe³⁺ to Fe²⁺ after the melting of hematite and the dissolution of pseudobrookite present in clinker waste. Granules obtained after 30 min of holding at 1280 °C are impermeable to water and, depending on the cooling applied, have a density between 0.4 and 0.7 g/cm³, porosity between 70 and 85 vol %, and compressive strength between 0.7 and 1.1 MPa. These results meet the requirements for high-quality fire-resistance lightweight aggregates. Full article

This review explores strategies to enhance meat quality in poultry, focusing on both management and genetic methods. Poultry meat quality is influenced by many factors, including rearing conditions, nutrition, animal welfare, and post-slaughter processing. Key management factors such as stocking density, ventilation, temperature, and humidity are emphasized for their significant impact on bird welfare and the resulting meat texture, color, and microbial stability. Welfare-enhancing practices like gentle handling, environmental enrichment, and thermal comfort are highlighted for their direct effects on stress levels and meat properties such as water-holding capacity and pH. Innovations in slaughtering and chilling techniques, including electrical and gas stunning and rapid chilling, are shown to preserve meat quality and prevent common defects like pale, soft, and exudative (PSE) or dark, firm, and dry (DFD) meat. The review also underscores the importance of hygiene protocols, hazard analysis and critical control points (HACCP) systems, and traceability technologies to ensure food safety and foster consumer trust. On the genetic front, it discusses conventional selection, marker-assisted selection (MAS), and genomic selection (GS) as tools for breeding birds with better meat quality traits, including tenderness, intramuscular fat, and resistance to conditions like woody breast. Functional genomics and gene editing are identified as the leading edge of future advances. Ultimately, the review advocates for an integrated approach that balances productivity, quality, animal welfare, and sustainability. As consumer expectations increase, the poultry industry must adopt precise, science-based strategies across the entire production process to reliably deliver high-quality meat products. Full article