Search Results (403)

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

Bored pile waste slurry generated during bridge substructure construction exhibits high water content and stable colloidal properties, resulting in difficult solid–liquid separation and severe environmental risks. To improve solid–liquid separation and facilitate efficient disposal, this study systematically investigated the flocculation and dewatering performance of the slurry using three typical flocculants (Anionic polyacrylamide (APAM), cationic polyacrylamide (CPAM), and polymeric aluminum chloride(PAC)) through sedimentation tests, supernatant purification monitoring, particle size analysis, zeta potential measurements, and specific filtration resistance tests. The results show that flocculant type and dosage significantly affect treatment efficiency. Organic flocculants outperform inorganic PAC in both particle aggregation and dewatering improvement. Among them, APAM exhibits a prominent low-dose advantage; at an optimal dosage of 0.2–0.3% (corresponding to a pure reagent dosage of 10–15 mg/L based on wet slurry), it effectively reduces the slurry water content and lowers supernatant suspended solids below the 50 mg/L discharge standard within 80 min. Mechanistically, PAC provides primarily electrostatic neutralization, whereas APAM and CPAM achieve composite flocculation through charge neutralization, adsorption bridging, and sweep capture. Benefiting from efficient low-dose neutralization and long-chain bridging effects, APAM significantly reduces filtration resistance and forms stable flocs. Overall, an APAM dosage of 10–15 mg/L is the optimal scheme for in situ treatment of bored pile waste slurry, providing technical support for the efficient management and controlled disposal of engineering slurry under similar geological conditions. Full article

The ubiquitous use of the plant hormone indole-3-acetic acid (IAA) or auxin in modern agriculture has led to its emergence as a water contaminant, necessitating efficient removal technologies. Addressing the need for high-performance sorbent materials, this study reports the synthesis and characterization of four novel nanocomposites based on halloysite (Hal), bentonite (Ben), sepiolite (Sep), and diatomaceous earth (DE) functionalized with silver nanoparticles (AgNPs). Successful immobilization and morphological features were confirmed via XRD and SEM-EDS. Crucially, post-adsorption EDS analysis provided direct solid-state evidence of pollutant capture through the distinct quantification of organic carbon. High-Performance Liquid Chromatography (HPLC) tests demonstrated that all functionalized materials exhibited a drastically enhanced IAA adsorption capacity over their pristine counterparts during a 96-h kinetic monitoring window. Kinetic profiling revealed a biphasic adsorption pathway characterized by a rapid initial sequestration within the first 10 h followed by a diffusion-limited equilibration, while thermodynamic modeling converged excellently with Langmuir and Sips equations, confirming a surface-confined chemisorption mechanism governed by uniform monolayer deposition. Notably, the performance ranking was found to be primarily governed by the architectural accessibility of the silicate frameworks rather than the absolute magnitude of their specific surface area. Furthermore, solution-phase spectroscopic studies coupled with Dynamic Light Scattering (DLS) and Zeta Potential measurements unraveled a robust, surface-confined ligand exchange mechanism. Rather than triggering colloidal aggregation, IAA coordination induced a controlled, systematic development of an organic molecular shell around the individual silver cores. This work underscores the potential of these engineered AgNPs@silicate platforms as sustainable, high-efficiency materials for the environmental remediation of emerging phytohormone contaminants. Full article

Biopolymers have emerged as effective stabilizing and capping agents in the green synthesis of metal nanoparticles due to their biocompatible, hydrophilic, and eco-friendly nature. Among these, bacterial polysaccharides, particularly exopolysaccharides (EPSs), offer distinct advantages over plant, algal, and fungal derived polymers, owing to their unique chemical structure rich in negatively charged functional groups that facilitate interactions with metal ions and enhance nanoparticles’ stability. Despite their properties, the practical application of AgNPs is often limited by aggregation, colloidal instability, and uncontrolled ion release. To address these challenges, in the present study, EPS-stabilized silver nanoparticles (AgNPs) were synthesized using a green approach. The synthesized biogenic AgNPs were immobilized with natural zeolite, a porous inorganic material, to improve stability and regulate functionality. The resulting catalytic material was partially characterized using structurally using spectrophotometry (UV-Vis), scanning electron microscope - energy dispersive X-ray analysis (SEM-EDAX), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FTIR). Furthermore, the synthesized green catalyst was evaluated for its photocatalytic degradation against synthetic dyes (methylene blue). In addition, its antibacterial potential was also assessed through determination of inhibitory concentration (IC₉₀) and minimum bactericidal concentration (MBC₉₉), highlighting its potential as a multifunctional biomaterial for environmental and biomedical applications. Full article

This work is an extension of our previous work on UV-assisted green synthesis of silver nanoparticles (AgNPs) from water hyacinth leaf extract, which is focused on using their unique biogenic capping layer to mitigate matrix interference in clinical diagnostics. The synthesized AgNPs were evaluated for uric acid (UA) detection and used to fabricate a plasmonic colorimetric biosensing platform. The results show that the biosynthesized AgNPs effectively act as optical signal transducers in an uricase-based enzymatic system, in which the natural capping shield provides excellent electrosteric protection, providing excellent colloidal stability without non-specific aggregation in complex matrices. A linear correlation between absorbance and UA concentration was observed in the range of 100–500 µM (R² = 0.99). The limit of detection (LOD) calculated by the 3σ/slope approach was 25.89 µM. The sensor showed good repeatability with a relative standard deviation (RSD) below 5%, and stability studies showed that the AgNPs retained more than 90% of their initial response after 14 days. Recovery studies in spiked human serum showed satisfactory accuracy (96.3–103.4%), confirming a high tolerance to endogenous interfering species (e.g., ascorbic acid and glutathione) without pre-purification steps. Importantly, the working range covers clinically relevant uric acid concentrations found in human serum. The obtained results point to the potential of waste-derived green-stabilized AgNPs as a robust plasmonic-based colorimetric biosensing platform for the clinical monitoring of uric acid, successfully combining ecological valorization with high-performance, matrix-tolerant diagnostics. Full article

The origin and metallogenic role of pyrite in sandstone-hosted uranium deposits remain difficult to constrain because pyrite may record both early diagenetic reduction and later ore-fluid overprinting. Here, pyrite and associated uranium minerals from mineralized and barren sandstones of the Middle Jurassic Zhiluo Formation in the Yahewan uranium deposit, southern Ordos Basin, were investigated using petrography, SEM-BSE imaging, EPMA, LA-ICP-MS trace-element analysis, and in situ sulfur isotope analysis. Pyrite occurs mainly as framboidal, colloidal, pore-filling, fracture-filling, and massive aggregates and is commonly associated with organic matter and coffinite or coffinite-like U-silicate minerals. Most pyrite domains show low Co/Ni ratios, suggesting a predominantly authigenic to sedimentary–diagenetic origin. High U, Mo, V, W, Se and As occur mainly in pyrite-rich microdomains, but high-U analyses are interpreted cautiously because some signals may include contributions from adjacent coffinite or coffinite-like U-silicate phases, fracture-hosted uranium minerals, or mixed ablation. Together, the petrographic, trace-element and sulfur isotope data support a two-stage model in which early organic matter and authigenic/biogenic pyrite created local reducing microenvironments that were later overprinted by U-bearing basinal fluids. Full article

Nanotechnology currently offers two approaches to tumor therapy. The first involves coating the surface of nanoparticles with high-affinity molecules for targeted delivery. The second involves directing the nanoparticles to the desired area of the body using an external magnetic field. Such nanoparticles are often made of magnetic metals (iron, nickel, cobalt, etc.), but in living systems, the main problem with such nanoparticles is their toxicity. To address the toxicity issue, various barriers and coatings are primarily used. In this work, a laser technology for producing multifunctional nanocomposites based on graphene-coated iron nanoparticles decorated with gold nanoparticles was developed. Graphene-coated iron nanoparticles (200 nm) were synthesized using laser ablation in isopropanol. The presence of a graphene coating on the surface of the iron nanoparticles was confirmed by TEM, Raman spectroscopy, and luminescence analysis. A technology for depositing gold nanoparticles approximately 10 nm in size onto the graphene shell of the resulting iron nanoparticles was invented. The essence of the technology lies in creating critical conditions in a nanoparticle colloid, leading to intense aggregation with each other. Multifunctional nanocomposites based on graphene-coated iron nanoparticles decorated with gold nanoparticles did not exhibit acute toxicity to cell cultures under normal conditions. Moreover, under the combined influence of an alternating magnetic field and laser radiation, nanocomposites damaged 96% of neuroblastoma cells in culture. Full article

Bovine milk represents a highly complex colloidal system whose physicochemical stability depends on the organization of milk fat globules, casein micelles, membrane-associated phospholipids, and somatic cellular components. Mechanical separation procedures such as centrifugation induce redistribution of dispersed colloidal fractions and structural perturbations within the milk matrix, potentially enabling fraudulent reduction of somatic cell count while preserving bulk compositional parameters. In the present study, we investigated whether advanced deep learning architectures could identify centrifugation-associated structural alterations in bovine milk using microscopy image representations. A total of 16,472 microscopy images obtained from centrifuged and non-centrifuged milk samples were analyzed using Swin Transformer V2 and ConvNeXt-Base architectures. Both models successfully detected centrifugation-associated structural perturbations and substantially outperformed the previously analyzed InceptionC baseline. ConvNeXt-Base achieved 87.30% classification accuracy together with 86.85% balanced accuracy and 86.59% harmonic average of recalls following totalogit aggregation. Importantly, Swin Transformer V2 demonstrated strong monotonic relationships between logit metrics and centrifugation ratio (r = 0.640–0.651, p < 0.01), indicating sensitivity to progressive image-level changes associated with increasing centrifugation ratio. Collectively, the obtained findings demonstrate that microscopy-derived deep learning representations capture structural information associated with centrifugation-induced changes in bovine milk, supporting the applicability of AI-assisted microscopy for detecting processing-related alterations in complex dairy systems. Full article

Nanobubbles have attracted increasing interest in food systems because they can modify gas dispersion, interfacial transport, washing performance, preservation processes, and the structures of dispersed matrices. However, their behavior cannot be interpreted based on bubble size alone. Proteins, polysaccharides, lipids, salts, colloidal particles, gas composition, and processing conditions can alter interfacial adsorption, gas transfer, bubble persistence, and matrix organization in food systems. This review examines the physicochemical mechanisms proposed to explain nanobubble persistence and functionality, with an emphasis on surface charge, interfacial adsorption, gas supersaturation, confinement, and interactions with food biopolymers. A central distinction is made between passive nanobubble-containing systems and externally activated systems involving hydrodynamic cavitation, ultrasound, plasma, pressure fluctuations, and reactive gases. Under passive conditions, nanobubbles mainly act as gas–liquid interfaces that influence local transport and adsorption. In activated systems, microbial inactivation, reactive oxygen species formation, and apparent mass-transfer enhancement often arise from external energy input, gas chemistry, turbulence, and transient supersaturation rather than from nanobubbles alone. Interfacial stability is used here as an organizing concept to connect nanobubble persistence, food-matrix interactions, generation methods, characterization limitations, and interpretation of reported technological effects. Current methods, such as dynamic light scattering and nanoparticle tracking analysis, provide useful size and concentration estimates but cannot unambiguously distinguish nanobubbles from protein aggregates, fat droplets, micelles, polysaccharide assemblies, and other colloidal structures in complex matrices. Therefore, reliable interpretation requires complementary methods, appropriate controls, and standardized reporting of gas composition, generation method, energy input, matrix properties, and processing conditions. Thus, nanobubble-containing technologies show promise for food processing; however, their value depends on the separation of nanoscale interfacial effects from concurrent hydrodynamic, chemical, and matrix-dependent phenomena. Full article

In this study, carbon quantum dots (CQDs) were synthesized from various lignocellulosic and hemicellulosic biomass precursors via a semi-hydrothermal torrefaction process, and their structural, optical, colloidal, and photocatalytic properties were systematically investigated. Biomass sources including Oriental thuja cone (Thuja orientalis), sawdust, tea waste, apricot kernel shell, walnut shell, sugar beet pulp, hazelnut residue, soybean residue, and chitosan were used to evaluate the effect of precursor composition on CQDs characteristics. UV–Vis spectroscopy confirmed the formation of CQDs in all samples, exhibiting characteristic π–π* and n–π* transitions, while significant variations in absorption intensity and spectral behavior were observed depending on biomass type. Dynamic light scattering and zeta potential analyses revealed that most CQDs exhibited aggregation tendencies, with limited systems showing improved colloidal stability due to electrostatic and/or steric stabilization. The synthesized CQDs were combined with TiO₂ and their influence on the photocatalytic degradation of Reactive Black 5 under UV irradiation was investigated. Although high decolorization efficiencies (85–98%) were achieved, total organic carbon removal remained lower (2.6–41.4%), indicating incomplete mineralization. The highest mineralization efficiencies were observed for TiO₂ systems modified with sawdust- and thuja-derived CQDs. Overall, the results demonstrate that the photocatalytic performance of CQDs-modified TiO₂ systems is governed not only by optical properties but also by surface functionalization, colloidal stability, and charge carrier dynamics. The findings highlight the critical role of biomass composition in determining CQD properties and provide a comparative framework for designing sustainable nanomaterials for environmental applications. Full article

Hybrid organic–inorganic composites based on biopolymers and nanoclays are attracting increasing interest for the development of functional materials in biomedical and agricultural applications. In this work, elongated alginate/halloysite nanotube (Alg/HNT) composite filaments were fabricated through a wet-spinning process assisted by syringe-based extrusion. Alg/HNT dispersions with different inorganic/organic ratios were first screened in terms of colloidal stability and injectability in order to identify suitable formulations for extrusion. The influence of key processing parameters, including the extrusion flow rate and calcium chloride concentration in the coagulation bath, was then systematically investigated to elucidate their effect on filament morphology and structure. Optical and scanning electron microscopy revealed that filament diameter can be tuned by varying the CaCl₂ concentration, while partial alignment of alginate chains along the extrusion direction was observed. Halloysite nanotubes were homogeneously distributed within the polymer matrix, mainly as micro-sized aggregates. Finally, the nanotubes were chemically functionalized with caffeine, as a model molecule, and incorporated into the alginate filaments, demonstrating the feasibility of introducing specific functionalities into wet-spun Alg/HNT composite fibers. These results establish a reproducible strategy for the fabrication of alginate/HNT filaments with tunable morphology and functionalizable nanotube interfaces, providing a versatile platform for the development of sustainable hybrid biopolymer materials. Full article

The valorization of secondary biomass streams is an important step toward more resource-efficient biorefinery concepts and reduced dependence on fossil-based materials. In this study, agricultural and forest residues, namely Atlas cedar cones, mixed conifer cones, hazelnut shells, walnut shells, coffee silverskin, and cocoa shells, were investigated as feedstocks for producing colloidal lignin particles. Lignin-rich extracts were obtained by Organosolv pretreatment using 60 wt% aqueous ethanol, followed by particle formation through solvent shifting and purification by ultrafiltration. A particular novelty of this work is that highly different feedstocks were processed under identical Organosolv and solvent-shifting conditions, enabling a direct comparison of their suitability for colloidal lignin particle production within one consistent process route. The feedstocks differed markedly in extractive content and chemical profile, as shown by sequential Soxhlet extraction and qualitative GC-MS screening. Despite these differences in extract composition, solvent shifting yielded colloidal lignin particles with largely similar properties. Dynamic light scattering showed hydrodynamic diameters of 65–88 nm immediately after precipitation for all samples except cocoa shell, which formed strong agglomerates. The ultrafiltration step further introduced an industry-relevant downstream purification stage by removing most water-soluble low-molecular-weight compounds before product evaluation. After purification and redispersion, particle sizes ranged from 121 to 389 nm, indicating partial aggregation but overall successful recovery of stable colloidal dispersions. All purified particle suspensions exhibited comparable antioxidant activity in the FRAP (ferric reducing antioxidant power) assay, ranging from 12.3 to 18.4 mg lignin per mg ascorbic acid equivalents. These results demonstrate that even chemically diverse biomass side streams can be converted into purified colloidal lignin suspensions with similar colloidal behavior and functional performance. The findings highlight the potential of low-value agricultural and forest residues as promising raw materials for lignin-based antioxidant and material applications. Full article

Carbon dots (CDs) are emerging nanomaterials with promising applications in food science. Recent reports have shown that carbon dots are inherently present in heat-treated foods and beverages. However, the occurrence of carbon dots in traditional Korean beverages has not yet been investigated. In this study, carbon dots were isolated from three Korean beverages, Nurungji tea, barley tea, and green tea, and characterized using TEM, DLS, ζ-potential, UV-absorbance, photoluminescence (PL), FTIR and XPS analyses. All three beverages contained quasi-spherical (<10 nm) CDs, consistent with quantum dots whose optical properties depend on their size. DLS and ζ-potential measurements (−40 mV for cereal tea and −14 mV for green tea) confirmed their colloidal stability without aggregation in the beverages. PL spectroscopy exhibited excitation-dependent emission with a bathochromic shift, peaking at 412–438 nm, and FTIR spectra revealed abundant O-H, N-H, C=O, and C-N functional groups, reflecting oxygen and nitrogen doping that modulate redox reactions. Due to these surface functional groups, CDs demonstrated excellent antioxidant activity, with green tea CDs achieving 100% scavenging activity at 12.5 µg/mL, while barley and Nurungji CDs reached 100% and 78% scavenging activities at 100 µg/mL, respectively. In the cytotoxicity test using L929 fibroblast cells, grain tea CDs showed a survival rate of over 90% at concentrations of 6.25–100 µg/mL, and green tea CDs showed a survival rate of over 90% at concentrations up to 25 µg/mL, which is consistent with the literature on the biocompatibility of CDs. These results confirm that beverage-derived CDs are non-toxic and powerful antioxidants, reaffirming the safety and functionality of traditional Korean food. Full article

Several bioactive compounds, including phenolic and flavonoid substances, have been identified in the aqueous leaf extract of Schinus terebinthifolius (ALE). These compounds are active ingredients in green nanoparticle biosynthesis. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), zeta potential analysis, and FTIR spectral analysis were used to characterize copper oxide nanoparticles (CuNPs) and silver nanoparticles (AgNPs). According to TEM results, AgNPs exhibited somewhat larger diameters (12 ± 4 nm), were spherical with significant aggregation, and displayed a fairly uniform distribution, while CuNPs were primarily quasi-spherical with a narrow size range of about 4–5 nm. CuNPs showed a much more negative zeta potential value of −25.8 mV, indicating good to high colloidal stability, whereas AgNPs had a zeta potential of −15.5 mV, suggesting moderate stability. The main compounds included chlorogenic acid (10,375.28 µg/g), gallic acid (7015.59 µg/g extract), ellagic acid (1571.29 µg/g extract), and rutin (1485 µg/g extract). The antifungal activity of CuNPs and AgNPs was tested at concentrations of 6, 12, 25, 50, and 75 μg/mL on Quercus rubra wood against Fusarium circinatum and Pythium tardicrescens. The greatest inhibition of F. circinatum growth was observed with CuNPs and AgNPs at 75 µg/mL, showing fungal inhibition percentages (FIPs) of 61.48 and 60.74%, respectively. CuNPs and AgNPs at 75 µg/mL exhibited moderate activity against P. tardicrescens, with FIPs of 21.48% and 15.92%, respectively. The MICs for AgNPs and CuNPs were 1.5 and 85 µg/mL with F. circinatum and P. tardicrescens, respectively. Overall, CuNPs and AgNPs demonstrated potential antifungal activity against F. circinatum but moderate activity against P. tardicrescens compared to the control. This ALE from S. terebinthifolius is rich in flavonoids and phenolic compounds, including gallic acid, chlorogenic acid, rutin, ellagic acid, and p-coumaric acid, as identified by HPLC analysis. These biomolecules act as both capping agents, which stabilize the nanoparticles, and reducing agents. Using S. terebinthifolius ALE’s rich phytochemical profile as a reducing and stabilizing agent provides an environmentally friendly method for the green synthesis of CuNPs and AgNPs. Full article

Molybdenum blue dispersions were synthesized via an ion-exchange approach using hydroquinone and glucose as reducing agents to clarify the influence of reductant chemistry on redox evolution and colloidal stability. Electrolyte-free conditions enabled controlled self-assembly of reduced polyoxomolybdate clusters. UV–Vis spectroscopy revealed characteristic absorption bands at ~750 and ~1100 nm associated with intervalence charge transfer in mixed-valence Mo⁵⁺/Mo⁶⁺ clusters, with hydroquinone stabilizing more deeply reduced clusters, while glucose-derived systems demonstrated a higher degree of reduction with a higher ratio of reducing agent to metal. Time dependence of oxidation–reduction potential and optical density measurements demonstrated prolonged redox equilibration and gradual self-organization over several weeks. Dynamic light scattering confirmed the formation of nanoclusters with comparable hydrodynamic diameters of approximately 3.5 nm for both reducing agents. Raman and FT-IR spectroscopy indicated structurally similar polyoxomolybdate frameworks. In contrast, electrokinetic measurements revealed pronounced differences in surface chemistry and stability: hydroquinone-derived dispersions exhibited robust, pH-independent electrostatic stabilization, whereas glucose-derived systems showed weaker, pH-dependent stabilization and rapid electrolyte-induced aggregation. These results demonstrate that the nature of the reducing agent has an impact on the synthesis and colloidal behavior of molybdenum blue dispersions synthesized by the ion-exchange route. Full article