Search Results (5,403)

The Guangdong–Hong Kong–Macao (GHM) region (especially the Greater Bay Area), a low-lying economic hub in southern China, faces complex particulate matter (PM_2.5) pollution dynamics under the combined influence of monsoonal systems and global warming. While long-term PM_2.5 reductions are documented, phase-specific trends remain obscured. Here, we analyze high-resolution ChinaHighPM2.5 dataset observations (2000–2023) using moving averages and piecewise regression to quantify abrupt shifts in interannual and seasonal PM_2.5 trends across the region. We identify 2014 and 2016 as critical breakpoints for annual PM_2.5 concentration (Mean_-5y-Year) and its linear acceleration rate (k_-5y-Year), respectively. Critical breakpoints delineate phases where declines persisted but decelerated. Prior to 2014, the PM_2.5 levels exhibited an upward trend (+0.203 µg·m⁻³·a⁻¹, p > 0.05), which reversed sharply post-2014 (−2.046 μg·m⁻³·a⁻¹, p < 0.01). Spatially, breakpoints clustered post-2014 for concentrations, while acceleration rate shifts reveal a latitudinal divergence near 23° N (23.873°~22.812° N); southern areas transitioned earlier (2010–2011) versus post-2014 in the north. Post-inflection declines are strongest toward the GBA urban core, with winter and autumn driving seasonal improvements (winter: steepest decline −2.646 μg·m⁻³·a⁻¹; autumn: largest trend reversal Δ−3.961 μg·m⁻³·a⁻¹), while improvement rates narrowed post-2016 (Δk = +0.527 µg·m⁻³·a⁻²). This study establishes that apparent regional PM_2.5 reductions mask significant spatiotemporal heterogeneity, underscoring the necessity of phase-specific analysis for effective pollution control in climatically vulnerable megaregions. Full article

This study examines the carbonation behavior and CO₂ storage potential of a Ca-rich alkali-activated binder produced entirely from industrial residues-ladle furnace slag (LFS), coal ash (CA), and cement kiln dust (CKD). The system was designed as a one-part alkali-activated material (AAM), with CKD acting as an internal activator, and subjected to ambient curing, water curing, and accelerated CO₂ curing at ambient pressure. Phase evolution, microstructural development, and pore-structure characteristics were investigated using X-ray diffraction, FTIR spectroscopy, DSC–TG analysis, scanning electron microscopy, and X-ray micro-computed tomography, together with measurements of density, water absorption, and compressive strength. Loss-on-ignition measurements combined with chemical analysis were further used to quantify CO₂ uptake and evaluate the degree of carbonation of the binder system. CO₂ curing fundamentally altered the reaction pathway of the binder, shifting it from hydration-dominated to carbonation-controlled phase evolution, leading to the decomposition of calcium-bearing hydrates and complete carbonation of non-hydraulic γ-belite with the formation of vaterite, aragonite, and calcite. These transformations induced pronounced microstructural densification, reflected in a near-doubling of compressive strength (>48 MPa), increased apparent density, reduced water absorption, and simplified pore-network topology. A preliminary carbon footprint assessment indicates that the production of 1 m³ of the developed LFS–CA–CKD concrete generates about 14.36 kg CO₂-eq, while the carbonation process enables significant CO₂ sequestration, resulting in a net negative carbon balance. The results demonstrate that controlled carbonation is an effective post-treatment strategy for waste-derived alkali-activated binders, enabling simultaneous performance enhancement and permanent CO₂ sequestration. Full article

Zinc oxide (ZnO) and zinc sulfide (ZnS) nanocomposites represent promising multifunctional photocatalysts due to their complementary band structures and synergistic charge separation. ZnO–ZnS nanocomposites with varied ZnS content were synthesized to elucidate the composition–structure–property relationships governing their multifunctional performance. Structural characterization using XRD, SEM/EDS, Raman spectroscopy, and XPS confirmed the coexistence of wurtzite crystalline phases of ZnO and ZnS. SEM analysis revealed ZnS fine deposition on the ZnO surface. XPS measurements showed a gradual increase in the amount of ZnS on the ZnO surface with increasing sulfide content and a shift in the valence band maximum from 2.32 eV (pure ZnO) to 0.77 eV (pure ZnS). Optical measurements (IR, UV–Vis diffuse reflectance, photoluminescence) demonstrated that, despite the evolution of vibrational and luminescence features characteristic of ZnS, the apparent band gap remained nearly constant at 3.16–3.18 eV across the series. Photocatalytic methylene blue (MB) degradation followed pseudo-first-order kinetics, peaking for ZN_2 (1% ZnS, k_app = 103 × 10⁻³ min⁻¹), which is 1.7 times higher than for pure ZnO. This enhanced performance is consistent with an S-scheme-like heterojunction that facilitates electron migration to the ZnS conduction band while retaining ZnO valence band holes for oxidation. Scavenging experiments confirmed that electrons dominate MB degradation (k_app up to 185.1 × 10⁻³ min⁻¹ with EDTA/t-BuOH/Ar), outperforming hole-mediated pathways. Antibacterial assays against Staphylococcus aureus revealed good antimicrobial activity for all nanoparticles. The nanocomposite’s antibacterial activity was similar across all samples and was only slightly lower than that of pure ZnS and ZnO. Full article

CsPbBr₃ perovskite quantum dots (QDs) have attracted significant attention for optoelectronic applications owing to their outstanding optical properties, yet achieving controlled synthesis with high stability under mild conditions remains a challenge. The room-temperature synthesis of CsPbBr₃ perovskite quantum dots using a coprecipitation method is systematically investigated in this work, with an emphasis on how the structural and optical properties of the QDs are influenced by the Br/Pb ratio and OA/OAm ratio. The findings show that controlling the Br/Pb and OA/OAm ratios can effectively influence the size, crystalline phase, and surface passivation properties of CsPbBr₃ quantum dots. The photoluminescence peak shifts blue and the bandgap widens when the Br/Pb ratio rises due to a decrease in quantum dot size. This is mainly explained by more effective surface covering by Br⁻ ions and increased quantum confinement effects. The resultant quantum dots demonstrate ideal optical performance at a Br/Pb ratio of 75 and an OA/OAm ratio of 1.5, with dense ligand coverage, superior defect passivation, and markedly improved stability under UV irradiation and in aqueous environments. Variations in the Br/Pb and OA/OAm ratios affect the binding configuration and coverage of ligands on the quantum dot surface, thereby influencing the relationship between non-radiative recombination and the quantum confinement effect. The LED fabricated with the as-synthesized high-performance quantum dots demonstrates a wide color gamut, covering 129.45% of the NTSC standard, indicating strong potential for display applications. Full article

This study experimentally investigated the movement, combustion, and potassium (K) and chlorine (Cl) migration behaviors of three biomass types: densified wood pellets (heavy), corn straw (lightweight), and wheat straw (lightweight, friable). The experiments were conducted under conditions representative of industrial coal-fired circulating fluidized bed (CFB) boilers, with a temperature range of 850–950 °C and a fluidization velocity of 6–8 m/s. Results show that densified wood pellets sink into the dense-phase zone and release volatiles slowly, in about 50 s. As the volatiles are nearly fully released, the pellets fracture multiple times along their length, eventually forming nearly spherical particles. Their movement and combustion processes closely resemble those of coal, making them suitable for direct co-firing in coal-fired CFB boilers. Conversely, corn straw and wheat straw exhibit low density, high volatile release rates (2 and 10 times that of wood pellets, respectively), rapid char fragmentation and abrasion, and high inherent K and Cl content (with >50% of K and >90% of Cl released). These properties lead to particle segregation, shortened gas-phase combustion time, an upward shift in heat release distribution, and potential risks such as high-temperature KCl corrosion, HCl dew point corrosion, ash slagging, and bed agglomeration. Therefore, untreated corn straw and wheat straw are unsuitable for co-firing in conventional coal-fired CFB boilers. This study provides essential data and engineering guidance: strict quality control is necessary for wood pellets to prevent Cl contamination, while pretreatment is mandatory for straw fuels. These findings offer practical insights for implementing diverse biomass co-firing strategies in coal-fired CFB boilers. Full article

Soccer goalkeeper diving saves demand precise inter-segmental coordination to intercept shots under uncertainty, yet preparatory postures and kinematic adaptations between declared (D) and undeclared (ND) conditions remain underexplored in youth athletes. This study analyzed lower-limb kinematics and Continuous Relative Phase (CRP) in 10 elite youth male goalkeepers (14.3 ± 0.3 years) performing dives in different conditions using inertial sensors (Xsens MVN Awinda, 60 Hz) on a natural grass pitch. Data were time-normalized across the dive cycle and analyzed using Statistical Parametric Mapping 1D ANOVA to compare kinematic and coordination differences between conditions and preferred side. ND high dives showed significantly shorter total duration (1.02 ± 0.13 s vs. 1.09 ± 0.12 s) and take-off (0.19 ± 0.05 s vs. 0.21 ± 0.05 s) compared to the D condition. Pronounced laterality emerged in hip internal/external rotation (ipsilateral: 0–100%), with CRP alterations only in the ipsilateral ankle-hip/knee during preferred-side low dives (13–74%, p < 0.001), indicating tighter segmental coupling and reduced phase lag between joints from mid-stance to push-off. D condition appeared to favor mediolateral CoM shifts for reach optimization, while ND emphasized anteroposterior readiness. These findings highlight CRP’s sensitivity to coordination under uncertainty and reveal laterality effects in preferred-side low dives. Full article

Coaxial cable plays a vital role in the wide application of telecommunications, network, and television broadcasting and other fields, with its transmission performance directly affecting signal quality and transmission efficiency. In practical applications, the length of the cable and the terminal load state of the connection often affect the stability of the signal. In order to solve this problem, we used STMicroelectronics STM32F407VET6 (STMicroelectronics, Geneva, Switzerland) as the master controller in this system, and deduced the length of the cable by analyzing the functional relationship between the length of the cable and the open circuit frequency. An open cable is regarded as a capacitor, and any two core wires are regarded as two plates of a flat capacitor. The linear relationship between open frequency and length is used to detect the length of the coaxial cable. The system then determines whether the terminal load is capacitance or resistance based on the detected frequency. If no frequency is detected, then the load is considered resistance. The system detects the resistance value of the resistor through series voltage division. If a frequency is detected, this indicates that the load is capacitance. At this time, the system uses an RC oscillation circuit composed of HGSEMI ICL8038 (Huagao Semiconductor Co., Ltd., Wuxi, China) for testing, and provides the phase shift required by the corresponding signal through the RC network, so as to detect the capacitance value. Finally, we successfully designed a coaxial cable length and terminal load detection system based on STM32F407VET6. Through this system, the user can accurately understand the length of the coaxial cable and the load of the connection terminal, which provides a reliable guarantee for the stability of signal transmission. Full article

The global population explosion and accelerated industrialization have led to an increasing shortage of fossil fuels and environmental contamination, underscoring the urgent need to develop innovative energy storage technologies to improve energy utilization efficiency. As pivotal components in thermal energy storage (TES) systems, phase change materials (PCMs) enable spatiotemporal matching between thermal energy supply and demand through latent heat absorption and release during phase transitions. Organic PCMs are considered ideal candidates for thermal energy storage due to their high energy storage density, stable phase transition temperature, low supercooling, and negligible phase separation. However, inherent drawbacks such as low thermal conductivity, liquid leakage, limited light absorption, and lack of functionality have hindered their widespread application in advanced thermal management systems. Herein, we systematically summarize cutting-edge functionalization strategies for PCMs, progressing from conventional methods like thermal conductive particle blending and microencapsulation to the emerging design of 3D porous thermally conductive skeletons, including metal foams, boron nitride aerogels, carbon-based aerogels, and MXene aerogels. These frameworks not only enhance thermal transport via continuous conductive pathways and impart shape stability through capillary encapsulation but also, when integrated with photo-thermal, electro-thermal, and magneto-thermal conversion properties, enable broad applications in solar photo-thermal/photo-thermo-electric conversion, thermal management of electronics and batteries, building efficiency, and wearable thermal regulation. The review further addresses current challenges and future directions, highlighting scalable 3D framework fabrication, the shift to active thermal management, and innovative applications beyond conventional domains. By establishing a microstructure–property–application correlation, this work provides valuable insights for developing next-generation high-performance multifunctional phase change composites. Full article

The impact of boron (B) on the microstructure evolution and stabilization of mechanical properties in the IN718 superalloy during aging at 680 °C for 3000 h is investigated. The results indicated that B had negligible effects on grain size and the intragranular γ″ phase growth. In contrast, it effectively suppressed the precipitation and growth of the δ phase during long-term aging, which is attributed to grain boundary segregation of B that retards the diffusion of alloying elements. Adding B could improve the impact toughness and stability of the creep properties of the alloy. The primary mechanism is that the addition of B enhances grain boundary cohesion and suppresses the coarsening of the δ phase, while the beneficial effect of B on mechanical stability becomes negligible during the later stages of aging, as the severe coarsening of grain boundary phases offsets the enhanced grain boundary cohesion resulting from B segregation. Furthermore, the presence of slip bands was observed in the creep deformation mechanism of B-added alloys, which is likely attributable to B promoting dislocation slip at grain boundaries. With prolonged aging time, the dominant creep deformation mechanism in the B-modified alloy shifts from being primarily governed by twinning and dislocation slip to a mechanism involving twinning, stacking fault shearing γ″ phase, and dislocation slip. Full article

Background and Objectives: Polyethylene (PE) mulching enhances crop productivity through microclimate optimization but introduces synthetic polymer-derived compounds into agricultural soils. Despite widespread use, biochemical and microbial impacts of PE mulch emissions remain poorly understood. This study investigated the impact of PE mulch emissions on soil metabolomes and microbial communities during field pea (Pisum sativum L.) cultivation. Methods: A 75-day field experiment compared PE-mulched and non-mulched soils across five temporal sampling points (T0–T4). Headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry was used to identify PE-derived organic compounds in mulched soils. Microbial community structure was assessed through the phospholipids derived fatty acids (PLFA) approach, whereas mass spectrometric untargeted metabolomics was used to characterize the soil biochemical profiles. Results: Analysis identified 18 PE-derived organic compounds (n-alkanes, phthalates, and additives) in the mulched soils. PE mulching significantly increased bacterial abundance (anaerobic bacteria, actinomycetes, and aerobic bacteria) but suppressed all functional fungal guilds, particularly saprotrophic fungi (30% reduction) and arbuscular mycorrhizal symbionts. PE-derived organic compounds were associated primarily with the first RDA axis (RDA1), which alone explained 44.6% of the metabolome variance. These compounds presented strong positive correlations with organic nitrogen compounds and lipids and negative correlations with benzenoids and nucleotides. Pathway analysis revealed perturbations in energy metabolism, lipid metabolism, and xenobiotic degradation pathways. Conclusions: PE mulch emissions differentially shift soil microbial communities and metabolic networks, with bacterial proliferation contrasting with fungal suppression. These findings highlight the complex trade-offs between agronomic benefits and soil biological impacts, emphasizing the need for sustainable mulching alternatives. Full article

A four-quadrant low-coherence envelope detection method was proposed for measuring the surface spacing of optical components, eliminating the requirement for precise control of the delay line scanning step to generate a π/2 phase shift. The method employs an orthogonal polarization Mach–Zehnder (MZ) fiber interferometer, illuminated by a broadband superluminescent diode (SLD), and a four-quadrant polarization-resolved detector to simultaneously acquire spatially phase-shifted interference signals carrying surface spacing information. The interference envelope is directly demodulated to extract surface spacing, thereby decoupling measurement accuracy from mechanical stepping constraints. To enable real-time, high-precision calibration of the delay line, two complementary schemes were implemented: wavelength division multiplexing (WDM)-based calibration and dual optical path calibration. Experimental results confirm that the dual-path scheme exhibits weak dependence on scanning velocity and remains stable across a wide speed range. Repeat measurements of the surface spacing of a 1 mm thick sapphire plate yielded a standard deviation (STD) of 1.3 μm. By relaxing the strict π/2 phase shift condition traditionally imposed on scanning step size, this method improves operational efficiency while maintaining measurement reliability—providing a robust and broadly applicable solution for metrology, including lens surface spacing and transparent plate thickness characterization. Full article

This study addresses the challenges posed by weakly cemented strata in mine tunnels, where surrounding rock softens and deforms upon water exposure, which promotes the development of seepage pathways, and exhibits insufficient stability in bolt (cable) support systems. This study conducts laboratory grouting tests using silica sol on typical weakly cemented sandstone from Xinjiang mining areas. The mineral composition and pore structure were characterized using XRD, SEM, and mercury porosimetry. The injectable mixing ratio parameters for silica sol and the catalyst were determined through viscosity-time evolution tests. Grouting was performed using a custom-built constant-pressure grouting apparatus. After curing, unconfined compressive strength (UCS) and porosity-permeability tests were conducted to evaluate the micro-mechanism of grouting effects on the mechanical and permeability properties of weakly cemented sandstone. The results indicate: (1) The sandstone exhibits a high clay mineral content of 39.8%, dominated by illite. Its pores are primarily small-scale (10–100 nm), accounting for 79.31% of the total pore volume. This scale matches that of silica sol nanoparticles (approximately 9–20 nm), facilitating slurry penetration into micro-pores; (2) microscopic analyses reveal that silica sol effectively reconstructs pore structures through permeation filling and surface coating. Compared to KCl-induced gelation (with approximately 8% gel coverage), NaCl-induced gelation forms a more continuous gel film with more complete pore filling, achieving coverage of around 22%. Furthermore, the larger surface area of the gel aggregates indicates a more thorough filling of micro- and nano-pores, effectively enhancing rock mass compactness. (3) Permeability decreased from 6.91 mD to 3.55 mD, a reduction of 48.6%, while porosity decreased from 16.94% to 13.55%, showing a phased reduction during the grouting process; (4) following pressure grouting stabilization, the uniaxial compressive strength of sandstone increased appropriately by approximately 7–14%, while the elastic modulus rose by about 18–28%. The failure mechanism shifted from shear brittleness to a shear-tension composite state, with enhanced post-peak bearing capacity. These findings provide support for optimizing silica sol grouting parameters in weakly cemented strata tunnels and for the synergistic reinforcement of rock mass permeability and strength. Full article

Long COVID is associated with persistent fatigue, exercise intolerance, and microcirculatory dysfunction. Altered red blood cell (RBC) rheology, including impaired deformability and increased aggregation, may contribute to these symptoms, yet the effects of exercise interventions remain unclear. This longitudinal pilot study tested whether an individualized, symptom-responsive exercise program improves RBC rheology in Long COVID. A total of 170 (110 f/60 m) participants entered a five-phase training protocol; 15 completed all phases and formed a predefined finisher subgroup. RBC aggregation and deformability, hematological parameters, and coagulation- and iron-related markers were assessed across phases; RBC morphology was additionally analyzed in finishers at baseline and completion. In the total cohort, aggregation indices decreased across training phases, accompanied by prolonged aggregation half-time, while hematological, coagulation, and iron markers remained largely unchanged. The deformability changes were not uniform in the full cohort; however, finishers showed a deformability shift after completion. Importantly, morphologically abnormal RBC decreased in finishers, and these changes correlated with deformability, suggesting that improved rheology is linked to reduced RBC abnormalities. Prospectively, larger controlled studies are needed to confirm these results and to evaluate whether exercise-induced rheological improvements translate into functional and symptomatic benefits. Full article

Phase measuring deflectometry (PMD) is widely employed in automotive intelligent manufacturing for high-precision, large-area inspection of specular and free-form surfaces. However, the conventional three-frequency four-step phase-shifting method requires multiple projected patterns, which reduces measurement efficiency and exhibits poor robustness on highly curved surfaces. To overcome these limitations, this study proposed a novel encoding and decoding strategy that utilized only four phase-shifted fringes and one additional unequal phase-shifted fringe for phase retrieval and unwrapping. Moreover, an amplitude symmetry-based segmentation algorithm was introduced for background segmentation, and a phase self-correction approach was developed to mitigate jump errors in the fringe order map caused by surface imperfections. Experimental results demonstrated that the proposed method significantly improved the measurement efficiency compared with the conventional approach while improving measurement accuracy. Full article

Background: Early diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM) remains challenging. Although ECG and morphological abnormalities at diagnosis are well-described, their temporal evolution has not been systematically evaluated. This study characterized the prevalence and longitudinal progression of electrical and structural cardiac abnormalities preceding ATTR-CM diagnosis. Methods: We retrospectively analyzed patients with confirmed ATTR-CM evaluated at a specialist amyloidosis center between 2006 and 2023. Diagnosis was established by grade 2–3 myocardial uptake on 99mTc-DPD scintigraphy. Standard 12-lead ECGs and transthoracic echocardiograms were reviewed at diagnosis and at baseline, 3–5 years earlier. Results: Sixty-three patients (79% men; mean age 77 ± 8 years) were studied, including 33 (52%) with hereditary ATTR (ATTRv) and 30 (48%) with wild-type ATTR (ATTRwt). Overall, 95% had a NAC score ≤ 2, consistent with less advanced disease at diagnosis. During the prediagnostic phase, 79% of patients exhibited pathological ECGs. Non-specific ST–T abnormalities (40%), prolonged QTc (38%), left-axis deviation (35%), first-degree AV block (33%) and anterior infarction pattern (33%) were each observed in at least one-third of patients. From baseline to diagnosis, significant prolongation was observed in the PR interval (+26 ms), QRS duration (+11 ms), and QTc interval (+22 ms) (p < 0.001 for all), and a leftward shift observed in the electrical axis (−12.03°, p = 0.011). Low voltage was uncommon at both time points. Although interventricular septal thickness increased significantly (+3.42 mm; p < 0.001), left ventricular ejection fraction and dimensions were relatively stable. Conclusions: In this proof-of-concept study, electrical remodeling precedes functional changes and outperforms low voltages to raise clinical suspicion of ATTR-CM. Full article