Search Results (4,400)

Interactions between resveratrol and biological or carrier systems play a key role in determining its bioavailability, stability, and delivery performance. These interactions involve proteins, lipids, cyclodextrins, nucleic acids, polysaccharides, and other formulation matrices, and are governed by noncovalent forces such as hydrogen bonding, hydrophobic interactions, π–π stacking, and desolvation effects. This review examines how complementary spectroscopic, calorimetric, structural, and computational techniques are used to characterize resveratrol interactions. Fluorescence, UV–visible spectroscopy, circular dichroism, FTIR, NMR, ITC, DSC, X-ray diffraction, molecular docking, and molecular dynamics simulations are discussed according to their contribution to binding analysis, conformational assessment, thermodynamic interpretation, structural organization, and complex stability. By integrating these approaches, this review provides a technique-oriented framework for understanding resveratrol binding and guiding the development of more stable resveratrol-based carrier systems and bioactive formulations. Full article

The development of durable and practical polymer-supported photocatalytic materials that are suitable for use in continuous-flow systems has become an increasingly pressing issue in the field of water treatment. In this study, FeTiO₃/BiOCl heterojunction structures were synthesized at different ratios and integrated into a poly(vinylidene fluoride) (PVDF) matrix to develop photocatalytic thin-film systems. The resulting materials were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and UV–visible diffuse reflectance spectroscopy (UV-DRS) analyses. In photocatalytic experiments conducted under visible light, a 66.3% removal of doxycycline was achieved for pristine FeTiO₃ within 180 min, whilst the FTO@BiOCl(III) composite reached 74.4%. In the PVDF-based thin-film system, the film catalyst demonstrated a removal efficiency of 68.9%. When the pH effect was investigated, the highest total removal of 90.3% was achieved under pH 6.0 conditions. Radical scavenging experiments revealed that superoxide radicals were the predominant active species (a decrease to 30.5% in the presence of benzoquinone (BQ). In experiments conducted in the air-lift reactor system, the P-FTO@BiOCl(III) film achieved approximately 65% removal after 9 h and maintained its structural stability. The PVDF-supported FeTiO₃/BiOCl heterojunction thin-film system offers a noteworthy alternative for environmental applications due to its suitability for continuous systems, structural stability and effective photocatalytic performance. Full article

Ternary heterojunction photocatalysts enhance the separation and transport of photogenerated charge carriers, thereby boosting their redox activity for use in environmental and sustainable energy applications. This study focuses on the synthesis of a TiO₂/Bi₂O₃/g-C₃N₄ heterojunction composite via a ceramic method with TiO₂ loadings of 80%, 85%, and 90% (denoted 80T-BC, 85T-BC, and 90T-BC, respectively) to investigate structure–property–performance relationships in photocatalytic dye degradation. The structural, optical, and morphological properties of the synthesised materials were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance UV–Vis spectroscopy (DRS). The photocatalytic performance was evaluated by measuring the degradation of Rhodamine B under visible light irradiation. Under optimised conditions (pH 6, initial RhB concentration of 5 mg/L, and a reaction time of 120 min), a degradation rate of 99% was achieved. Furthermore, the semiconductor demonstrated significant antibacterial activity against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. This study presents a promising strategy for modifying TiO₂-based semiconductors by incorporating different metal oxides. The formation of the resulting heterojunction significantly enhances photocatalytic efficiency, demonstrating strong potential for practical environmental remediation. Full article

Moldy pear core constitutes a severe internal defect that compromises fruit quality. This study proposes a nondestructive detection method for Korla pear moldy core using Vis/NIR spectral signals, aimed at supporting post-harvest quality control and automated industrial sorting. We collected spectral signals from pears and quantified the moldy pear core area to classify samples into healthy (S = 0%), slightly moldy (0 < S ≤ 10%), and severely moldy (S > 10%) categories. We constructed a three-tier comparative framework to evaluate the progression from conventional machine learning to advanced deep learning: traditional methods using univariate selection (US) and random forest (RF) for feature extraction followed by support vector machine (SVM) classification; 1D-ResNet for direct processing of spectral signals; and two-dimensional approaches transforming signals into improved gramian angular field (IGAF) or Laplacian pyramid Markov transition field (LPMTF) images processed through deep belief network (DBN), MobileNetv3, and Vision Transformer (ViT). The LPMTF-ViT combination delivered the best performance with 98.98% test accuracy and 94.44% external validation accuracy, significantly exceeding traditional approaches and 1D-ResNet. This innovative approach delivers effective technical support for early-stage, nondestructive detection of internal fruit defects. It also establishes a scalable foundation for automated industrial inspection systems, potentially reducing post-harvest losses while ensuring premium quality control in modern fruit supply chains. Full article

Polydopamine (PDA) is a promising biomimetic material, but its structural complexity hinders rational control over its light absorption properties. The purpose of this study was to develop a simple post-synthetic method to tune the absorption spectrum of PDA using Bobbit’s salt (4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium salt) as a mild oxidant. Conventional PDA nanoparticles were treated with Bobbit’s salt either in pure water or in a 1:1 methanol–water mixture to obtain two modified samples. Structural analysis conducted using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and mass spectrometry demonstrated that Bobbit’s salt selectively oxidized catechol units to ortho-benzoquinone moieties, with the C–O/C=O ratio decreasing from 71:29 in the untreated PDA to 51:49 in the water-treated sample, while nitrogen functionalities remained unchanged. Consequently, the sample prepared in pure water showed generally lower absorbance across the visible–near-infrared range, whereas the sample prepared in the methanol–water mixture exhibited enhanced ultraviolet absorption but reduced near-infrared absorption. When coated onto polyvinylidene fluoride membranes, the water-treated PDA produced a brighter and more reddish-yellow appearance. On transparent poly(methyl methacrylate) substrates, the same coating also enhanced ultraviolet blocking and reduced visible transmittance. These findings conclude that Bobbit’s salt is an effective and selective reagent for tailoring the optical properties of PDA, with potential applications in protective coatings and light-modulating materials. Full article

The fabrication of SERS nanotags with efficient antibody loading and high signal enhancement remains a challenging task for combining surface-enhanced Raman spectroscopy (SERS) and lateral flow immunoassay (LFIA). In this study, bimetallic Au^DTNB@PDA^DTNB@Ag nanoparticles with a polydopamine (PDA)-based internal nanogap were synthesized and functionalized with anti-prolactin monoclonal antibodies to produce SERS nanotags. Here, polydopamine serves both as a spacer providing a nanogap between the core and the shell, and as a reaction layer to capture Raman reporter 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB) within the nanogap. Regimes (conditions, protocols) for conjugating antibodies to Au^DTNB@PDA^DTNB@Ag were selected to preserve both the binding affinity for the target analyte and the Raman activity of the SERS nanotag. The SERS nanotag provides plasmonic absorption for visible colorimetric readout, as well as strong SERS signals for highly sensitive quantitative immunoassay. Measuring the Raman intensities of DTNB in the test zone after performing LFIA made it possible to determine prolactin with a detection limit of 0.2 ng/mL in the working range from 1 to 10 ng/mL. The achieved limit of detection was 10-fold lower than the LFIA coupled with colorimetric readout (4.7 ng/mL). The recoveries of prolactin from spiked serum samples were in the range of 70.2–82.6% with relative standard deviations of 2.3–6.8%. Overall, the Au^DTNB@PDA^DTNB@Ag nanotag demonstrated high stability, Raman activity, and specificity, indicating that the SERS nanotag with PDA-assisted internal nanogap is promising for use in SERS immunoassay of other target analytes. Full article

Heat transport properties of serpentine minerals are important to the thermal state of subduction zones, but available data contain systematic errors from contact losses, radiative gains, deformation with pressure (P), and/or modelling short-comings. Here, laser flash analysis (LFA) provides thermal diffusivity (D) within ±3% as a function of temperature (T) of perpendicularly oriented, nearly pure Mg₃Si₂O₅(OH)₄ polymorphs, Al-rich lizardite with minor brucite, three serpentinites, plus chrysotile and lizardite near Ni₃Si₂O₅(OH)₄. Visible spectra show that Fe is mostly ferric and Cr³⁺ occasionally occupies tetrahedral sites. The proposed coupled substitution of Al³⁺ + OH⁻ replacing Si⁴⁺ + O²⁻ accounts for extra OH⁻ peaks in infrared spectra. Rietveld refinements and infrared spectra reveal that serpentine dehydration in LFA runs begins near 800 K. Thermal conductivity (K) vs. T is calculated within ~±5% from D, available heat capacity data, and ambient density. For antigorite, D and K are strongly anisotropic whereas chrysotile has extreme differences, but lizardite is nearly isotropic. A thermodynamic identity provides ∂(lnK)/∂P = 11 ± 1% Gpa⁻¹ for soft serpentine, double that of hard olivine. Lizardite becomes more thermally conductive than olivine near the 1 bar decomposition temperature, which increases with P. Through feedback, and because released H₂O vapor carries heat upwards, P,T conditions in serpentinized slabs follow the decomposition phase boundary during subduction. Full article

In the present study, innovative active gelatin–chitosan films enriched with blackberry (ACTIVE-BF) and sage flower (ACTIVE-SF) extracts were developed and comprehensively characterised with regard to their physicochemical, functional and environmental properties. The incorporation of phenolic compounds increased the film’s UV–Vis (ultraviolet–visible spectroscopy) absorbance, confirming the presence of chromophoric groups and the improvement of light-barrier properties. FTIR (Fourier Transform Infrared Spectroscopy) analysis revealed hydrogen bond formation and intermolecular interactions between polyphenols and the –OH/–NH groups of the biopolymer matrix, which enhanced the structural stability of the films. Adding blackberry and sage extracts slightly increased the hydrophilicity and solubility of the films (40–48%), without significantly affecting their water vapour transmission rate (531–547 g/m²·d). The obtained films exhibited strong antioxidant activity, with FRAP (Ferric Reducing Antioxidant Power) values ranging from 17.75 to 40.83 mM Trolox/mg, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging capacity between 42.58 and 46.88%, and metal chelating ability up to 50.82%. During the nine-day storage of salmon fillets at 4 °C, the active films effectively inhibited microbial growth (reduction of 1.5–2.1 log CFU/g) while maintaining pH stability (6.2–6.4). Respiration activity confirmed environmental safety. The developed materials represent biodegradable, multifunctional films with high potential for application as sustainable active packaging for perishable food products. Full article

Halloysite nanotubes (HNTs), composed of an aluminosilicate framework, are naturally abundant, biocompatible, and sustainable clay minerals with a tubular morphology and tunable surface chemistry, making them attractive platforms for targeted, multifunctional drug delivery systems. In this study, a zinc ferrite integrated halloysite nanocomposite (ZnFe₂O₄/HNT) was developed via a one-pot synthesis approach for sustained release of cisplatin (Cp), aiming to reduce systemic toxicity and enhance cell-specific activity. The nanocomposites were further functionalized by integrating Cp (Cp: ZnFe₂O₄/HNT ratio 0.05) and folic acid (ZnFe₂O₄/HNT/Cp: FA ratio 0.05), followed by PEGylation (0.17 µL/mg of ZnFe₂O₄/HNT/Cp/FA/PEG). The structural and surface characteristics, phase, interfacial interactions (FA and Cp), and colloidal stability of nanoformulations were systematically investigated using powder X-ray diffraction analysis (XRD), Fourier transformed infrared (FT-IR) spectroscopy, zeta potential analysis, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HRTEM), and diffuse reflectance UV–visible (DRS-UV-Vis) spectroscopy. The results confirmed that ZnFe₂O₄ integration preserved the clay’s tubular framework while inducing nanocrystallization of both ferrite and cisplatin, indicating molecular dispersion within the clay matrix. Functionalization with FA (ZnFe₂O₄/HNT/Cp/FA) promoted amide bond linkage, modulated Cp-FA interactions, and significantly enhanced cumulative Cp release compared to the non-functionalized system ZnFe₂O₄/HNT/Cp (10.3% at 72 h vs. 34.4% at 72 h) under tumor acidic conditions (pH 6.6). PEGylation maintained the controlled release profile while improving dispersion stability. In vitro cytotoxicity studies revealed that FA-conjugated nanocomposites exhibited enhanced, time-dependent anticancer activity against HeLa cervical cancer cells, with reduced toxicity toward normal fibroblasts, indicating preferential cellular uptake via folate receptor-mediated mechanism. Overall, this work demonstrates that FA-functionalized ZnFe₂O₄/HNT nanocomposite provides an effective clay-based platform for modulating Cp release and enhancing folate receptor protein-mediated targeted therapy for cervical cancer. Full article

This study investigates how structural dimensionality affects the optoelectronic behavior of organic lead–halide hybrid perovskites. Using the chiral cation R-1-phenylethylammonium (PEA), which is known to be able to form both one-dimensional (1D) and two-dimensional (2D) lead–iodide frameworks, we synthesize 1D $\left(\mathrm{PEA}\right){\mathrm{PbI}}_3$ and 2D ${\left(\mathrm{PEA}\right)}_2{\mathrm{PbI}}_4$ compounds through tailored crystallization and deposition routes. X ray diffraction confirms structural purity, while ultraviolet photoelectron spectroscopy (UPS) provides insight into the electronic structure and photoresponse. Both materials exhibit a surface photo-voltage (SPV) under visible illumination, reaching a maximum work function shift of 1.5 eV for the 2D phase and 0.4 eV for the 1D phase in the thin-film samples. These results suggest that the 1D phase exhibits a reduced tendency for iodide-vacancy formation, which may result in a more stable response under visible illumination, accompanied by faster relaxation dynamics and more anisotropic charge transport. Overall, our findings highlight the central role of electronic confinement in shaping photoinduced processes in hybrid perovskites and support the consideration of structural dimensionality as a key design parameter for the design of next-generation optoelectronic materials. Full article

Because of high visible and near-infrared (VNIR) reflectance, and deep shortwave infrared (SWIR) absorption, snow and ice are unique among terrestrial land cover. As such, both are well-suited to mapping and monitoring using optical remote sensing. However, to date, almost all studies of snow and ice spectroscopy have been limited to single or small numbers of specific cryospheric environments. These studies serve a diversity of objectives, but together also suggest the importance of the global continuum of snow and ice composition and spectroscopy. The continuum of snow and ice composition gives rise to the characteristics that allow different types of snow and ice to be distinguished optically. Particularly with imaging spectrometers. Characterization of this continuum of reflectance can facilitate development of physical models to quantify snow and ice composition and abundance, particularly in the presence of other types of land cover. In this study, a collection of ~140,000,000 visible through SWIR (VSWIR) reflectance spectra, collected by NASA’s EMIT imaging spectrometer from 56 diverse cryospheric environments, is used to characterize the continuum of snow and ice reflectance. This continuum is characterized using linear dimensionality reduction to quantify the dimensionality and topology of the spectral feature space of snow and ice. The resulting spectral feature space is effectively two-dimensional with a planar spectral feature continuum bounded by dry and wet snow, ice and dark targets (e.g., shadow, water). Because of the near collinearity of snow and ice endmember reflectances, linear spectral mixture models based only on these endmembers are ill-posed and unstable to inversion. However, in landscapes where sufficiently homogeneous seasonal snow is present with other land cover types, the standardized spectroscopic mixture model based on the Substrate, Vegetation and Dark (SVD) continuum can be extended with an instance-specific snow endmember (SVD + snow) to yield plausible areal fraction estimates with small misfits to observed spectra. More generally, the snow–ice-dark continuum can also be represented accurately with an optimal normalized difference index exploiting compositionally distinct differential absorptions at ~650 and ~1230 nm to distinguish dry from wet snow from white and blue ice. This optimized index, referred to as the Continuous Cryosphere Index (CCI), minimizes BRDF effects of topographic slope and aspect relative to illumination, while avoiding the saturation that causes the Normalized Difference Snow Index (NDSI) to conflate wet snow with white and blue ice reflectance. In addition to imaging spectrometers like EMIT, operational sensors like MODIS, VIIRS and WorldView-3 have spectral bands near 650 nm and 1230 nm, so they could also be used for CCI mapping. Full article

Three types of graphene–single crystal titanium dioxide composite (GR–TiO₂SCs) were prepared using the hydrothermal method, employing TiF₄ and graphite as raw materials with hydrofluoric acid serving as the morphology-directing agent. The phase composition and morphological features of the resultant composites were systematically characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction. These complementary characterization results clearly demonstrate that graphene and TiO₂ single crystals have been successfully hybridized to form a well-defined heterostructure, rather than a simple physical mixture. Photocatalytic performances were evaluated by monitoring the photodegradation behaviors of methylene blue, rhodamine B, and methyl orange solutions under simulated light irradiation, with real-time concentration variations recorded by UV–visible absorption spectroscopy. The composite sample in which TiO₂SCs were in situ grown and uniformly anchored onto graphene oxide substrates effectively suppressed the self-stacking and agglomeration of individual crystallites, thus delivering the best photocatalytic response. Increased exposure of the active catalytic interfaces of TiO₂SCs was found to play a key role in elevating the overall photocatalytic activity. The hierarchical assembly protocol developed in this work provides a feasible pathway for the rational design of functional composites with controllable microstructures and tailored properties, which can be further extended to the development of advanced sensing materials. Full article

Indium hafnium oxide thin-film transistors (TFTs) were prepared by the sol-gel method, and their crystal structures, surface morphologies, chemical compositions, optical and electrical properties were systematically investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-Vis) spectroscopy, and a semiconductor parameter analyser. We mainly study the effects of hafnium doping on indium oxide-based thin-film transistors through the following electrical properties, including field-effect mobility (μ FE), carrier concentration, on/off current ratio (Ion/Ioff), threshold voltage (Vth), and subthreshold slope (SS). The oxygen defects concentration decreased from 25.83% to 17.82% when Hf doping was increased to 5 mol%. The effect of Hf doping on the structure, as well as the properties of the Hf-InO_x thin films, was explored and it was found that Hf as a carrier inhibitor can effectively suppress the carrier concentration. This reduces the oxygen vacancy defects and improves the electrical performance of In₂O₃TFTs devices. The doped thin-film transistor exhibits excellent electrical properties with a mobility (μ) of 11.69 cm²/Vs, a threshold voltage (V_TH) of 1.68 V, a subthreshold slope (SS) of 0.68 V/dec, and an on/off current ratio (I_on/I_off) of 10⁷ when the Hf doping level is 3 mol%. Research indicates that the Hf-InO_x thin film prepared by the sol-gel method is a low-cost, high-performance, and widely applicable active layer material. Full article

Hafnia (hafnium oxide) nanostructures, both unmodified and silica-modified with minor and major silica content, were synthesized using an adapted sol–gel method with D-L tartaric acid as an internal template. After thermal treatment, structural non-stoichiometry and light absorptive properties were identified in the resulting hafnium-based nanostructures, indicating their potential for various applications, including photocatalysis. The ability of these materials to photogenerate reactive oxygen species (ROS), namely superoxide anion radicals (•O₂₋) under simulated solar light (AM 1.5) and singlet oxygen (¹O₂) under visible light (λ > 390 nm), was evaluated and monitored by UV–Vis and photoluminescence spectroscopy. Functionalization of hafnium-based oxides with protoporphyrin IX was employed to enhance singlet oxygen photogeneration. The reactivity of the generated (¹O₂) was assessed by quenching of DL α-tocopherol photoluminescence under visible light irradiation. Photocatalytic experiments conducted under anaerobic conditions demonstrated the ability of the hafnia-based nanostructures to reduce 1,4-benzoquinone (BQ) to 1,4-hydroquinone (H₂Q). Furthermore, embedding the hafnia-based powders into polyvinyl alcohol hydrogels enabled the obtainment of photoactive coatings on glass substrates, for which their mechanical properties were evaluated using force–distance spectroscopy measurements. Morphological and structural characterization of the materials was performed using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), X-ray diffraction and fluorescence (XRD, XRF), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption measurements, UV–Vis spectroscopy, photoluminescence (PL) spectroscopy, and zeta potential measurements. These investigations revealed that adding silica induces significant modifications in the morphology, texture, and structure of the hafnia, thereby enhancing the functional properties of the resulting materials. Full article

This study successfully developed an efficient one-dimensional confinement strategy to encapsulate polyoxometalate NiMo₆ clusters densely and uniformly within the cavities of a single-walled carbon nanotube (SWCNT), constructing a unique core–shell NiMo₆@SWCNT composite electrocatalyst. Comprehensive characterization including high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible absorption spectroscopy (UV-Vis) systematically confirmed the uniform dispersion and structural integrity of NiMo₆ within the SWCNT channels. Key evidence encompasses: (1) EDS elemental mapping revealing high co-localization of Ni/Mo signals inside the lumens; (2) transmission electron microscopy (TEM) images confirming the effectiveness of the filling process. The composite achieved an exceptionally low overpotential of 308 mV to drive a current density of 10 mA cm⁻² (significantly outperforming pure NiMo₆ at 365 mV and pristine SWCNT at 519 mV), exhibited a remarkably low Tafel slope of 96.64 mV dec⁻¹, possessed a high electrochemical active surface area (10.75 mF cm⁻²), and very low charge transfer resistance. Critically, it showed negligible current density decay during prolonged chronoamperometric operation over 35,000 s (>9.7 h). This work not only validates the confined encapsulation as a viable strategy for fabricating highly active polyoxometalate/carbon composites, but also elucidates that the performance enhancement stems from a “triple synergy”: the intrinsic catalytic activity of NiMo₆, the highly conductive/mass-transport network provided by SWCNT, and the synergistic effects arising from the confined interface—namely stress regulation and electronic coupling. This insight provides a novel perspective for designing high-performance non-precious metal electrocatalysts. Full article