Search Results (479)

Traditional fluorescent probes often exhibit compromised response and specificity due to poor adaptability to varying polar environments. Herein, we present the development of a robust Fe³⁺-specific small-molecule sensor by linking a tetraphenylsilole derivative and rhodamine 6G hydrazide via a Schiff-base π bridge to form a fluorescent donor–acceptor system. The dispersed silole moiety serves as dark donor, while the aggregated state of silole converts into emissive donor. Upon selective binding with Fe³⁺, the molecules are found to undergo fluorescence resonance energy transfer (FRET) and dark resonance energy transfer (DRET) to rhodamine moiety in a polarity-dependent manner. Hence, fluorescence quantitation of Fe³⁺ in both high-organic (>70%) and water-rich solutions (>70%) is successfully achieved with detection limits of 0.083 μM and 0.28 μM, respectively. Further, ratiometric intracellular imaging of Fe³⁺ is demonstrated using the probe. This sensing strategy can offer a promising avenue for the development of polarity-adaptive fluorescent probes targeting other metal ions in complex biological and environmental matrices. Full article

Tourism expansion can stimulate economic activity that can potentially increase energy consumption and environmental pressures. The tourism-induced Environmental Kuznets Curve (T-EKC) literature has focused mainly on CO₂ emissions and has greatly conceptualized economic growth on aggregate indicators, such as GDP. In this way, model specifications might not adequately capture the environmental effects directly associated with tourism activity. Addressing this gap, the present study examines the nonlinear relationship between tourism development and industrial-combustion CO₂ and power-industry methane emissions across Eurozone countries during 1996–2019. Unlike conventional T-EKC studies, internal travel and tourism consumption is employed as a sector-specific measure. Furthermore, primary energy consumption, an energy efficiency measure, and renewables are included in the model specifications to capture structural energy-related dynamics. The empirical analysis discloses heterogeneous relationships across pollutants. An inverted U-shaped relationship is found between tourism consumption and industrial-combustion CO₂ emissions. Methane emissions exhibit a U-shaped relationship. Causality analysis indicates a feedback relationship between tourism consumption and industrial-combustion CO₂ emissions. A unidirectional relationship running from methane emissions to tourism consumption is also justified. The study contributes to the literature by demonstrating that tourism-environment relationships depend on both the pollutant examined and the measurement of tourism-related economic activity. The findings highlight the need for differentiated environmental strategies that combine decoupling-oriented measures for industrial-combustion CO₂ emissions with targeted energy-sector and methane-mitigation policies to support more sustainable tourism growth. Full article

Real-time tissue identification during laser-guided surgery is a critical unmet need for collateral damage avoidance and margin delineation. Laser-Induced Breakdown Spectroscopy (LIBS) is compatible with pulsed laser surgical systems and offers rapid, label-free elemental analysis. This study presents a machine learning pipeline classifying five ex vivo bovine tissue classes, plus one synthetic null-signal control class, from LIBS spectra, designed to control specimen-level data leakage and class imbalance bias. Key contributions are (i) a ‘peak max over baseline’ aggregation strategy suppressing shot noise while preserving emission peaks; (ii) a repeated, group-based cross-validation protocol (GroupShuffleSplit, N = 10) enforcing specimen-level separation; and (iii) a comparison of 30 configurations (10 classifiers × 3 pipelines). Extra Trees with normalization reached the highest weighted F1-score (0.934 ± 0.118); excluding the synthetic control, five-class scores fall to 0.875–0.915 and the ranking changes, so these are the reference figures for biological tissue discrimination. Support Vector Machines were less accurate but more consistent (0.917 ± 0.069). Acquisition takes approximately 3 s per point; inference is sub-millisecond. With five source animals, the best configuration chosen on the same outer splits, and inner tuning that was not group-aware, these estimates are an exploratory step toward real-time guided surgery. Full article

This study investigated twelve gem-quality color-change fluorite specimens exhibiting a purple–blue gradient from Nova Era, Brazil, using colorimetry, Raman spectroscopy, UV-Vis spectroscopy, photoluminescence spectroscopy, EDXRF, and DiamondView imaging to explore the relationship between color depth and coloration mechanism. Raman spectroscopy further revealed enhanced defect-related peaks in dark samples, indicating cumulative irradiation-induced lattice damage. EDXRF analysis revealed that the radioactive element Th was detected exclusively in dark samples, with the darkest specimen reaching 0.184 wt.% Th, confirming that long-term Th-induced irradiation is the primary driver of color deepening. In UV-Vis spectra, the ~583 nm plasmon resonance absorption band of calcium colloids progressively red-shifted and broadened with increasing color depth, indicating elevated colloid concentrations and enhanced aggregation that directly intensify body color. DiamondView fluorescence weakened with deepening color, attributed to the quenching effect of calcium colloids. Photoluminescence spectra showed that the Eu²⁺ emission peak intensified in dark samples, while the broad 700–900 nm emission band systematically blue-shifted, reflecting differential responses of luminescence centers to radiation damage. This study provides non-destructive spectroscopic criteria for the fluorite color-change mechanism without relying on micro-area compositional analysis, establishing an analytical paradigm linking color gradients with spectral characteristics. Full article

This study systematically investigates the effects of gold tailings (GT) sand substitution levels and particle fineness on the rheological behavior, mechanical properties, and microstructural characteristics of Engineered Cementitious Composites (ECC). The results demonstrate that incorporating moderate amounts of GT sand (≤75%) effectively enhances both the compressive strength and fracture toughness of the composite. However, complete substitution (100% GT) significantly increases matrix porosity, leading to a consequent reduction in comprehensive mechanical strength. A critical size-dependent decoupling effect was observed: while the full replacement of fine aggregates with coarse GT severely degrades compressive strength due to excessive void formation, it unexpectedly increases the matrix fracture toughness by inducing significant crack deflection and tortuosity. Conversely, the incorporation of fine GT optimizes the distribution of matrix flaws and fosters a stable fiber pull-out mechanism. Consequently, despite a reduced pseudo-strain hardening (PSH) index, the fine GT-blended ECC achieves a remarkable tensile ductility of up to 3.0% by satisfying the fundamental multiple-cracking energy criteria while maximizing frictional energy dissipation. Furthermore, substituting natural silica sand with GT yields a highly sustainable composite, reducing carbon dioxide emissions by 41% and material costs by 20% without compromising core mechanical performance. Full article

A floating storage and regasification unit (FSRU) provides flexible infrastructure for liquefied natural gas (LNG) import, storage, regasification, and regional distribution. Its operation requires coordinated decisions on vessel deployment, sailing speed, loading and discharge timing, terminal inventory, berth use, and backup pipeline supply, while carbon taxation changes the relative cost of alternative vessel and operating choices. This paper formulates this operational planning problem as a maritime inventory routing problem (MIRP) for an LNG distribution network centered on an FSRU. The MIRP formulation integrates FSRU and terminal inventories, heterogeneous vessel capacities, berth constraints, discrete speed choices, pipeline backup, and direct operational carbon costs. To solve the resulting large model, we use a column generation framework with a labeling algorithm for the pricing subproblem, dual stabilization, and a diving heuristic for integer recovery. Each column represents a complete vessel schedule, and the restricted master problem coordinates schedule selection, task coverage, vessel use, backup supply, and aggregate berth capacity. Computational experiments are conducted on calibrated synthetic instances. A complete enumeration benchmark for a small instance provides a diagnostic check, while larger experiments examine computation time, feasible incumbent values, time discretization, instance size, and sensitivity to carbon taxes. The results show nonlinear responses in cost and emissions: low tax rates produce limited operational changes, intermediate rates induce clearer shifts toward vessels with lower emissions at moderate cost increases, and very high stress test rates yield diminishing marginal emission reductions. These findings show how integrated scheduling can support coordinated FSRU planning under carbon costs, while the observed transition points remain specific to the tested instances. Full article

Silica aerogel films are highly promising matrices for advanced optical applications, yet balancing ultra-high transmittance with structural stability during functionalization remains a critical challenge. Directly incorporating organic dyes often leads to aggregation and severe photodegradation, necessitating a robust host–guest encapsulation strategy. Herein, we report the fabrication of ultra-transparent, fluorescent silica aerogel films via precisely tailored acid/base two-step sol–gel kinetics and dip-coating. The optimized pure silica matrix achieves a peak visible transmittance of 97.4% and sub-nanometer surface smoothness (RMS = 276.7 pm). By utilizing this pristine network, Rhodamine 6G (Rh6G) and Rhodamine B (RhB) dyes were effectively confined within the amorphous mesoporous pores. Notably, RhB exhibited superior matrix integration, indicated by an H4 hysteresis loop transition and a significantly reduced pore volume (0.019 cm³/g). This mesoporous confinement successfully suppressed dye quenching, prolonging the fluorescence lifetimes to 5.22 ns and 5.36 ns for Rh6G and RhB, respectively. Crucially, we elucidate that the electrostatic and hydrogen-bonding interactions between the silica pore walls and the dye’s xanthene rings elevate the excited-state energy, inducing a distinct matrix-driven emission blue shift. This work provides a scalable pathway for high-performance optical coatings and offers deep insights into host–guest interfacial coupling in gel networks. Full article

Two novel multi-layer three-dimensional polymers (Polymer 1 and Polymer 2) were designed and synthesized via a multi-step coupling strategy. Their photophysical properties, aggregation-induced emission (AIE) behaviors, and metal ion sensing capabilities were systematically investigated. Both polymers exhibited typical aggregation-induced emission (AIE) characteristics with significantly enhanced fluorescence upon aggregation in tetrahydrofuran (THF)/water mixtures. Polymer 1 demonstrated selective and sensitive detection of Ag⁺ ions with a detection limit of 2.14 μM, while Polymer 2 showed exceptional recognition toward Ba²⁺ ions with a detection limit of 6.42 μM. Competitive experiments confirmed their good selectivity even in the presence of interfering metal ions. The distinct sensing behaviors were attributed to the different coordination environments provided by the polymer backbones. This work expands the family of multi-layer three-dimensional AIE-active polymers and demonstrates their utility as fluorescent probes for the detection of silver and barium ions. Full article

The premature fracture failure of polycrystalline α-Fe poses lots of hidden safety problems due to hydrogen absorption during human activities. A key challenge for the failure process is understanding the effects of hydrogen on grain boundaries (GBs). The study here demonstrates that the rapid diffusion of hydrogen leads to the formation of hydrogen-induced defects in a very short time. Specifically, hydrogen segregation results in void formation and even aggregation at GBs, which plays a critical role in crack initiation and propagation. The mechanical response of GBs with varying hydrogen levels is investigated using large-scale molecular dynamics (MD) simulations. The analysis shows that hydrogen increases the yield stress, thereby inhibiting dislocation emission from GBs. Additionally, GB damage alters the fracture mode from a mix of intergranular and intragranular fracture without hydrogen to a fully intergranular fracture with multi-site crack nucleation at high hydrogen concentrations (e.g., C_h = 3 at.%). This shift is driven by hydrogen-induced void formation at GBs and hydrogen’s rapid diffusion, which accelerates crack propagation along the grain boundaries. Full article

The manufacturing sector’s significant contribution to global carbon emissions necessitates effective decarbonization. This study evaluates the causal effect of exposure to China’s “Made in China 2025” (MIC) initiative, an industrial policy promoting intelligent manufacturing, on firms’ estimated carbon emissions by exploiting the policy as a quasi-natural experiment. Employing a Difference-in-Differences (DID) model on a panel of Chinese A-share manufacturing firms from 2011 to 2022, we find that exposure to the MIC policy is associated with an approximately 0.5% reduction in firms’ estimated carbon emissions. Although the reduction appears modest at the firm level, its aggregate effect may be substantial given the large scale of China’s manufacturing sector. Various robustness checks confirm the validity and persistence of this effect. Crucially, the environmental benefits are heterogeneous, showing stronger effects in competitive, technology-intensive, and labor-intensive sectors compared to capital-intensive ones. Mechanism analysis reveals that exposure to the MIC policy promotes substantive green innovation, accelerates digital transition through process optimization, and significantly enhances energy efficiency, thereby contributing to lower estimated firm-level carbon emissions. These findings underscore the potential role of intelligent-manufacturing-oriented industrial policies in reconciling industrial growth with climate mitigation and provide micro-level evidence on the environmental effects of policy-induced intelligent manufacturing transformation, extending a literature that has largely focused on economic outcomes. The results also suggest that policymakers should further promote intelligent manufacturing and design sector-specific green technology support policies, particularly for capital-intensive sectors where carbon-reduction effects appear relatively weaker, to maximize carbon reduction benefits. Full article

Graphene-based nanosheets (GNS), including graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphene nanoplatelets (GNPs), have attracted increasing attention for developing high-performance and sustainable cementitious composites. Compared with conventional dispersion strategies, graphene-based coating strategies enable the targeted localization of GNS at critical interfacial transition zones (ITZs), thereby maximizing their reinforcing efficiency while mitigating agglomeration issues. This review systematically summarizes recent advances in GNS coating technologies for cementitious composites, including physical adsorption, chemical assembly, electrophoretic deposition, and in situ growth. The effects of GNS coatings on interfacial engineering, mechanical performance, durability enhancement, and smart functionalities are critically discussed. Existing studies indicate that GNS coatings can improve strength, crack resistance, impermeability, and resistance to chloride ingress, freeze–thaw cycles, and other degradation processes mainly through ITZ densification and microstructure refinement. However, these benefits are strongly dependent on the coating method, substrate type, and stability of the graphene–substrate interface in calcium-rich alkaline pore solutions. In particular, physically adsorbed GO coatings may suffer from desorption or Ca²⁺-induced aggregation, chemically assembled coatings require further validation beyond laboratory-scale systems, and electrophoretic deposition is mainly applicable to electrically conductive substrates. In addition, localized conductive networks created by GNS coatings facilitate multifunctional properties such as self-sensing, electromagnetic shielding, and electrothermal performance. From a carbon-neutrality perspective, the improvements in mechanical properties and durability provide opportunities to reduce material consumption, extend service life, and lower life-cycle carbon emissions. Nevertheless, their carbon-neutral contribution should be verified through quantitative life-cycle assessment rather than inferred directly from strength or durability enhancement alone. Finally, the remaining challenges associated with large-scale implementation, long-term stability, cost-effectiveness, and field-scale validation are discussed. Particular attention is given to the fact that most existing evidence is derived from laboratory-scale specimens rather than real structural elements exposed to service environments. Full article

In this work, we developed a novel, ultrasensitive fluorescence sensing platform for determination of organophosphorus pesticides (OPs), using chlorpyrifos as a representative model analyte. The sensing strategy was constructed upon the key inner filter effect (IFE) between graphitic carbon nitride (g-C₃N₄) nanosheets and silver-coated gold core–shell nanoparticles (Au@Ag NPs). Initially, gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs), and Au@Ag NPs were successfully synthesized, and their fluorescence quenching efficiencies toward g-C₃N₄ were systematically evaluated. Owing to the superior spectral overlap with the fluorescence emission of g-C₃N₄, Au@Ag NPs exhibited the most obvious quenching effect and were thereby selected as the optimal quencher for sensor fabrication. Then, acetylcholinesterase (AChE) catalyzed the hydrolysis of acetylthiocholine (ATCH) into thiocholine. The generated thiocholine then induced aggregation of Au@Ag NPs via electrostatic and Ag-S interactions, which reduced the IFE efficiency and ultimately restored the fluorescence of g-C₃N₄. In contrast, the presence of chlorpyrifos effectively inhibits AChE activity, thereby suppressing ATCH hydrolysis and the subsequent aggregation of Au@Ag NPs. The fluorescence intensity of g-C₃N₄ was quenched by Au@Ag NPs and the signal was low. Under optimal experimental conditions, the response signal was found to be proportional to chlorpyrifos (CPF). This work presents a rapid, cost-effective, and highly sensitive approach for CPF residue analysis, holding great potential for applications in food safety monitoring and environmental surveillance. Full article

Light-converting polymer coatings and films are emerging passive photonic materials for spectral engineering in sustainable and protected agriculture. By absorbing ultraviolet or weakly used spectral components and re-emitting in visible bands that overlap with photosynthetic pigments and plant photoreceptor action regions, these materials can modify the radiation environment without additional electrical energy input. This critical narrative review analyses light-converting polymer films and coatings from a materials and coatings perspective, with emphasis on photophysical mechanisms, polymer matrices, luminophore families, coating fabrication routes, optical transparency, photoluminescence, aggregation phenomena, photostability and scalability. The photobiological background is included as a concise framework that justifies the spectral targets of the conversion process. Rare-earth complexes, inorganic phosphors, quantum dots, aggregation-induced-emission systems and organic dyes are compared as candidate luminophores. Particular attention is devoted to the general challenges associated with organic luminescent coatings, including dispersion, aggregation, optical transparency, photostability, and scalability. A PMMA/PDI coating system is discussed only as an illustrative case study demonstrating these broader materials-design considerations. Extrusion, solution casting, spin-coating, dip-coating and sol–gel processing are evaluated as fabrication strategies for laboratory and large-area greenhouse applications. The work concludes by identifying the main gaps that must be addressed before practical deployment: quantitative UV–Vis and photoluminescence characterization, absolute quantum yield, haze and scattering, thickness and morphology mapping, accelerated UV aging, weathering resistance, toxicity assessment and crop-specific validation. Full article

The mechanical properties and real-time damage evolution of sustainable concrete (SC) containing 100% recycled concrete aggregate (RCA) under the combined action of hybrid steel and polyolefin fibers were studied. Inspired by solving the massive effects on the environment from construction waste, as well as to improve the lower mechanical performance of lower-grade RCA, the effect of combining high-stiffness hooked-end steel fibers and flexible macro-polyolefin fibers within RCA was investigated. Six different mix designs were considered: plain, single-fiber (100% steel and 100% polyolefin) and three hybrid composites with varying fractions of the steel/polyolefin fibers (25/75, 50/50, and 75/25). Compressive, tensile and flexural strengths were determined by mechanical testing. During compressive testing, the damage evolution was monitored using low-cost acoustic emission (AE) as a non-destructive technique. Cumulative hits analysis, amplitude distributions, and the statistical b-value parameter were used for damage characterization. The results show that steel fiber significantly increased compressive strength (an increase of up to 13.8%), and the 50/50 hybrid mix showed a high synergistic effect, yielding the highest tensile (4.86 MPa) and flexural (25.54 MPa) strengths. AE analysis identified different damage fingerprints: Based on amplitude analysis, steel-fiber composites exhibited high-amplitude events (which may be attributable to fiber pull-out); polyolefin-fiber composites generated medium-amplitude events (may have resulted from distributed microcracking); and hybrid mixes displayed a mixed amplitude distribution. The b-value analysis provided insight into progressive damage and revealed that the hybrid fibers induce stable, diffuse damage that prevents the brittle failure of plain recycled aggregate concrete (RAC). The results show that hybrid fiber reinforcement can be a reliable approach to enhance the mechanical performance and crack resistance of RAC. Furthermore, low-cost acoustic emission (AE) serves as an effective non-destructive method for monitoring damage progression within the material. Full article

Poly(9,9-di-n-octylfluorene) (PFO) applications are limited by green emission defects and imbalanced charge transport. To overcome this, novel branched polystyrene-graft-polyfluorene (PSt-g-PFO) copolymers with varying grafting densities were synthesized. The highly branched architecture induces intense steric hindrance, acting as a physical shield to isolate PFO emissive cores. This successfully suppresses detrimental interchain π–π stacking, mitigating the ~530 nm green emission. Furthermore, the moderately grafted PSt-g-PFO2 promotes locally ordered crystalline packing, achieving a maximum electron mobility of 6.16 × 10⁻⁶ cm²/(V·s), an order of magnitude higher than linear PFO. This structural design effectively decouples deleterious aggregation from charge transport. Full article