Search Results (401)

A series of silica-supported, nitrogen-doped carbon-encapsulated cobalt–nickel alloy catalysts (Co_xNi_y@NC/SiO₂) was successfully synthesized and systematically evaluated for the liquid-phase hydrogenation of 1-nitronaphthalene to 1-naphthylamine. Physicochemical characterization confirmed that the incorporation of nickel promotes the formation of Co–Ni alloys and modulates the electronic structure of the catalysts. The catalytic performance was found to be highly sensitive to the Co/Ni ratio, with Co₂Ni₁@NC/SiO₂ exhibiting the most outstanding activity. Under optimized reaction conditions (90 °C, 0.6 MPa H₂, 5.5 h), both the conversion of 1-nitronaphthalene and the selectivity toward 1-naphthylamine reached approximately 99%. The catalyst also demonstrated excellent stability and recyclability, attributed to the protective nitrogen-doped carbon shell and the synergistic interaction between the Co–Ni alloy and M–N_x active sites. This work provides a new strategy for designing efficient and robust non-noble-metal catalysts for hydrogenation reactions. Full article

This study addresses the issues of poor stability and difficulty in recovery of free horseradish peroxidase (HRP) by developing a multi-level composite immobilized carrier that combines high loading capacity with long-term stability. The SiO₂@MnO₂@MAF-7 core–shell structured carrier was prepared via a solvothermal self-assembly method. Three immobilization strategies—adsorption, covalent cross-linking, and encapsulation—were systematically compared for their immobilization efficacy on HRP. The material structure was analyzed using techniques such as specific surface area analysis (BET), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) to characterize the material structure. Enzyme kinetic parameter determination experiments were conducted to systematically evaluate the performance advantages of the immobilized enzyme. BET analysis showed that SiO₂@MnO₂@MAF-7 had a specific surface area of 251.99 m²/g and a mesoporous area of 12.47 nm, and its HRP loading was 50.37 U/mg (immobilization efficiency 85.03%). Compared with free HRP, the Km value of the immobilized enzyme was decreased by 42%, the activity retention rate was increased by 35–50% at 80 °C and pH 4–9, and the activity was maintained by 65% after five repeated uses. In this study, MAF-7 was combined with MnO₂/SiO₂ for HRP immobilization for the first time, and the triple effect of rigid support-catalytic synergy-confined protection synergistically improved the stability of the enzyme, providing a new strategy for the industrial application of oxidoreductases. Full article

Acidic agricultural soils are frequently challenged by co-occurring heavy metal contamination and greenhouse gas (GHG) emissions. While biochar is widely used for integrated remediation, the specific role of silicon (Si) in modulating its effectiveness in cadmium (Cd) stabilization and nitrous oxide (N₂O) mitigation remains insufficiently understood. This study evaluated the co-remediation efficacy of two types of high-Si (bamboo leaves, ML; rice straw, RS) and two types of low-Si (Camellia oleifera leaves, CL; Camellia oleifera shells, CS) biochar, produced at 450 °C, within a Cd-contaminated and nitrogen-fertilized acidic soil. Results from a 90-day incubation showed that while all biochar effectively immobilized Cd, the low-Si CL biochar exhibited a superior stabilization efficiency of 66.2%. This enhanced performance was attributed to its higher soil organic carbon (SOC) and moderate dissolved organic carbon (DOC) release, which facilitated robust Cd²⁺ sorption and complexation. In contrast, high-Si biochar was more effective in mitigating cumulative N₂O emissions (up to 67.8%). This mitigation was strongly associated with an elevated abundance of the nosZ gene (up to 48.1%), which catalyzes the terminal step of denitrification. Soil pH and DOC were identified as pivotal drivers regulating both Cd bioavailability and N₂O dynamics. Collectively, low-Si biochar is preferable for Cd stabilization in acidic soils, whereas high-Si biochar is more effective at elevating pH and reducing N₂O emissions. These findings emphasize that optimizing co-remediation outcomes necessitates a targeted approach, selecting biochar based on the specific contamination profile and desired environmental benefits. Full article

Melanoma is one of the most aggressive skin cancers and requires innovative therapeutic strategies to overcome the limitations of conventional therapies. In this work, upconversion nanoparticles coated with mesoporous silica and functionalized with folic acid (UCNP@mSiO₂-FA) were developed as a targeted nanocarrier system for the delivery of doxorubicin (DOX). The UCNPs were synthesized via thermal decomposition, coated with mesoporous silica shells, and functionalized with folic acid (FA) to enable receptor-mediated targeting. DOX was then loaded into the mesoporous silica coating by adsorption, yielding UCNP@mSiO₂-FA-DOX. The different UCNPs were characterized for size, composition, colloidal stability, and loading and release of DOX. This comprehensive physicochemical characterization confirmed a high DOX loading efficiency and a slightly increased drug release under acidic conditions, mimicking the tumour microenvironment. In vitro assays using four melanoma cell lines (A375, B16-F10, MNT-1, and SK-MEL-28) revealed an excellent biocompatibility of UCNP@mSiO₂-FA and a significantly higher cytotoxicity of UCNP@mSiO₂-FA-DOX compared to unloaded UCNPs, in a dose-dependent manner. Cell cycle analysis demonstrated G2/M phase arrest after treatment with UCNP@mSiO₂-FA-DOX, confirming its antiproliferative effect. Overall, UCNP@mSiO₂-FA-DOX represents a promising nanoplatform for targeted melanoma therapy, combining active tumour targeting and enhanced anticancer efficacy. Full article

In the present study, thin-layered core–shell Gd₂O₃@SiO_1.5R (R is C₃H₆NH₂) structures were synthesized by gas-phase surface modification of a Gd₂O₃ core with a 3-aminopropyltriethoxysilane (APTES) shell for the first time. The proposed method consists of two consecutive steps carried out in a fixed-bed reactor. The first step involves APTES adsorption on the Gd₂O₃ surface, followed by APTES hydrolysis by water vapor. The organosyloxane shell formation was confirmed by transmission and scanning electron microscopy, IR spectroscopy, and thermogravimetric data. X-ray attenuation coefficients of Gd₂O₃ and Gd₂O₃@SiO_1.5R samples were determined by photon-counting computed tomography in a phantom study. The SiO_1.5R shells in the synthesized Gd₂O₃@SiO_1.5R samples had minimal thickness and did not affect the attenuation coefficients of Gd₂O₃. Full article

Magnetite (Fe₃O₄) nanoparticles are biocompatible, non-toxic, and easily functionalized. Coating them with mesoporous silica (mSiO₂) offers high surface area, pore volume, and tunable surface chemistry for drug loading. In this study, Fe₃O₄ magnetic nanoparticles were synthesized and coated with mSiO₂ shells enriched with calcium ions (Ca²⁺), aiming to enhance bioactivity for bone regeneration and tissue engineering. Different synthesis routes were tested to optimize shell formation Their characterization confirmed the presence of a crystalline Fe₃O₄ core with partial conversion to maghemite (Fe₂O₃) post-coating. The silica shell was mostly amorphous and the optimized samples exhibited mesoporous structure (type IVb). Calcium incorporation slightly altered the magnetic properties without significantly affecting core crystallinity or particle size (11.68–13.56 nm). VSM analysis displayed symmetric hysteresis loops and decreased saturation magnetization after coating and Ca²⁺ addition. TEM showed spherical morphology with some agglomeration. MTT assays confirmed overall non-toxicity, except for mild cytotoxicity at high concentrations in the Ca²⁺-enriched sample synthesized by a modified Stöber method. Their capacity to induce human periodontal ligament cell osteogenic differentiation, further supports the potential of Fe₃O₄/mSiO₂/Ca²⁺ core–shell nanoparticles as promising candidates for bone-related biomedical applications due to their favorable magnetic, structural, and biological properties. Full article

Multimodal nanocomposites that combine optical and magnetic functionalities are of great interest for applications such as imaging and temperature sensing. Ternary CuInS₂ (CIS)-based quantum dots (QDs) offer low toxicity, strong near-infrared (NIR) emission, and high photostability, making them promising for optical nanothermometry and imaging. In this study, CIS QDs were synthesized using an aqueous cysteine-mediated approach. Manganese ferrite (MnFe₂O₄) nanoparticles were prepared as the magnetic component due to their non-toxicity and superparamagnetic properties. To integrate both functionalities, QDs and magnetic nanoparticles (MNPs) were encapsulated in silica and then combined to form multimodal CIS/MnFe₂O₄/SiO₂ nanocomposites. The structure and morphology of the materials were characterized by TEM and XRD, while their optical properties were examined using UV–Vis, photoluminescence (PL) spectroscopy. This design ensured optical isolation, preventing fluorescence quenching while maintaining colloidal stability. The obtained composites exhibited PL in the NIR region and a thermosensitivity of 2.04%/°C. TEM analysis confirmed uniform silica shell formation and successful integration of both components within the composite. The materials also retained the superparamagnetic behavior of MnFe₂O₄, making them suitable for combined optical and magnetic functionalities. These results demonstrate the potential of CIS/MnFe₂O₄/SiO₂ nanocomposites as multifunctional platforms for optical imaging, temperature monitoring, and magnetically modulated effects. Full article

This study presents a sustainable and efficient method for fabricating core–shell structured palladium catalysts using a bacterial template and sol–gel synthesis. This synthesis aligns with green chemistry principles by minimizing waste and enhancing resource efficiency. Our results demonstrate that the bacterial template effectively stabilizes Pd nanoparticles (NPs), preventing significant agglomeration during synthesis and subsequent calcination under different atmospheres and final temperatures. The catalyst samples were characterized by SEM, TEM, XRD, and TGA. The 1 wt% Pd/R@SiO₂ catalyst exhibited high activity in the Suzuki–Miyaura cross-coupling reaction, achieving competitive yields. Furthermore, the catalyst demonstrated a stable performance over five consecutive cycles. This work underscores the potential of biotemplated synthesis as a versatile and eco-friendly platform for producing high-performance, tunable catalysts. Full article

This study systematically benchmarks the performance of four single soft magnetic powders—water-atomized Fe–Si–Cr (FeSiCr), silica-coated reduced iron powder (RIP), silica-coated carbonyl iron powder (CIP), and phosphate-coated CIP (CIP-P)—to establish quantitative relationships between powder attributes, deformation substructure, and high-frequency loss for molded power inductors (100 kHz–1 MHz). We prepared toroidal compacts at 200 MPa and characterized them by initial permeability (μ_i), core-loss (P_cv(f)), partitioning (P_cv(f) = K_hf + K_ef², K_h, $K_{\mathrm{e}}$: hysteresis and eddy-current loss coefficients), and EBSD (electron backscatter diffraction)-derived microstrain metrics (Kernel Average Misorientation, KAM; low-/high-angle grain-boundary fractions). Corrosion robustness was assessed using a 5 wt% NaCl, 35 °C, 24 h salt-spray protocol. Our findings reveal that FeSiCr achieves the highest μ_i across the frequency band, despite its lowest compaction density. This is attributed to its coarse particle size (D₅₀ ≈ 18 µm) and the resulting lower intragranular pinning. The loss spectra are dominated by hysteresis over this frequency range, with FeSiCr exhibiting the largest K_h, while the fine, silica-insulated Fe powders (RIP/CIP) most effectively suppress K_e. EBSD analysis shows that the high coercivity and hysteresis loss in CIP (and, to a lesser extent, RIP) are correlated with dense, deformation-induced subgrain networks, as evidenced by higher mean KAM and a lower low-angle grain boundary fraction. In contrast, FeSiCr exhibits the lowest KAM, with strain confined primarily to particle contact regions. Corrosion testing ranked durability as FeSiCr ≳ CIP ≈ RIP ≫ CIP-P, which is consistent with the Cr-rich passivation of FeSiCr and the superior barrier properties of the SiO₂ shells compared to low-dose phosphate. At 15 A, inductance retention ranks CIP (67.9%) > RIP (55.7%) > CIP-P (48.8%) > FeSiCr (33.2%), tracking a rise in effective anisotropy and—for FeSiCr—lower M_s that precipitate earlier roll-off. Collectively, these results provide a microstructure-informed selection map for single-powder formulations. We demonstrate that particle size and shell chemistry are the primary factors governing eddy currents (K_e), while the KAM-indexed substructure dictates hysteresis loss (K_h) and DC-bias superposition characteristics. This framework enables rational trade-offs between magnetic permeability, core loss, and environmental durability. Full article

Pickering emulsions have emerged as promising multiphase systems owing to their high stability and diverse applications in materials and chemical engineering. However, achieving precise and stimuli-responsive regulation of emulsion type, particularly reversible phase inversion between oil-in-water and water-in-oil states under fixed formulation without additional stabilizers, remains a considerable challenge. In this work, we developed a sol–gel strategy, i.e., in situ hydrolysis and condensation of silane precursors to form a silica shell directly on responsive microgels, to produce H-SiO₂@P(NIPAM-co-MAA) hybrid microgels. The resulting hybrid particles simultaneously retained pH and temperature responsiveness, enabling the transfer of these properties from the polymeric network to the emulsion interface. When employed as stabilizers, the hybrid microgels allowed the controlled formation of Pickering emulsions that remained stable for one week under testing conditions. More importantly, they facilitated in situ reversible phase inversion under external stimuli. Overall, this work establishes a sol–gel approach to fabricate organic–inorganic hybrid microgels with well-defined dispersion and uniform silica deposition, while preserving dual responsiveness and enabling controlled phase inversion of Pickering emulsions. Full article

The synthesis of lanthanide fluorescent nanoparticles and the investigation of their fluorescence sensing applications have attracted a great deal of attention in materials science over the past decades. In this study, we designed and synthesized a core–shell fluorescent nanoparticle based on dual-center emission from the europium and terbium complexes, and demonstrated its application as a ratiometric fluorescence sensor for the detection of 2,6-pyridinedicarboxylic acid (DPA). The europium complex is embedded in the inner core, providing a stable fluorescence signal at 617 nm, while the terbium complex is positioned in the outer shell and exhibits a fluorescence “Turn-ON” response at 545 nm upon interaction with DPA molecules. The fluorescence intensity ratio F₅₄₅/F₆₁₇ exhibits a sensitive response to the DPA concentration. Experimental results demonstrate that the as-prepared SiO₂@Eu@SiO₂@Tb nanoparticle exhibits a linear response in the DPA concentration range of 10–100 μM, with a detection limit (LOD) of 1.38 μM and well selectivity for DPA sensing. This strategy offers new insights into the development of novel lanthanide-based ratiometric fluorescence sensors. Full article

A green and cost-effective method was employed to efficiently synthesize conductive silica–silver (SiO₂/PCPA/Ag) core–shell structured microspheres. The SiO₂ microspheres were initially functionalized with poly(catechol-polyamine), followed by the in situ reduction of Ag ions to Ag nanoparticles on the surface of the SiO₂ microspheres using an electroless plating process. Analysis using scanning electron microscopy confirmed the successful formation of a dense and uniform silver layer on the surface of the SiO₂ microspheres. The valence state of the silver present on the surface of the SiO₂ microspheres was determined to be zero through analyses conducted using an X-ray photoelectron spectrometer and X-ray diffractometer. Consequently, the SiO₂/PCPA/Ag microspheres, upon initial preparation, demonstrated a notable conductivity of 1005 S/cm, which was further enhanced to 1612 S/cm following additional heat treatment aimed at rectifying defects within the silver layer. The resulting rubber composites displayed a low electrical resistivity of 5.4 × 10⁻³ Ω·cm and exhibited a significant electromagnetic interference (EMI) shielding effectiveness exceeding 100 dB against both X-band and Ku-band frequencies, suggesting promising potential for utilization as a material for conducting and EMI shielding purposes. Full article

Two types of spherical mold samples—designated PW1 (reference) and PW2 (modified) were prepared using the dip-and-sprinkle method. Both samples consisted of seven layers, but PW2 was differentiated by the incorporation of 5 wt.% ground walnut shell chips into the fifth layer of its structure. The aim of this modification was to assess the feasibility of employing biodegradable organic additives to generate controlled porosity after thermal decomposition, thereby enhancing gas transport through the mold structure. The gas permeability of the samples was determined across a broad temperature range from 25 to 950 °C using a dedicated, custom-built test rig developed for elevated-temperature permeability assessments. The results revealed that the inclusion of walnut shell chips significantly increased the gas permeability of the molds by approximately 42% at ambient temperature and 36% at 950 °C, attributable to the formation of stochastically distributed macro-voids upon burnout of the organic additive. The study demonstrates that selective layer modification using natural waste materials can be a viable method for tailoring functional properties of ceramic molds, offering a cost-effective, sustainable, and easily scalable alternative to conventional pore-forming strategies. Full article

Precise remote temperature sensing at the micro- and nanoscale is a growing necessity in modern science and technology. We report a series of luminescent tris-acetylacetonate lanthanide complexes, Ln(acac)₃(H₂O)₂ (Ln = Eu (1Eu), Tb (1Tb), Yb (1Yb)); acac⁻ = acetylacetonate), operating as self-referenced thermometers in the 290–350 K range, both in the solid state and when embedded in hybrid nanoparticles. Among the investigated systems, the Eu³⁺ complex exhibits excellent lifetime-based thermometric performance, achieving a maximum relative sensitivity (S_rmax) of 2.9%·K⁻¹ at 340 K with a temperature uncertainty (δT) as low as 0.02 K and an average temperature uncertainty ($\overline{\delta T}$) of 0.5 K, placing it among the most effective ratiometric lanthanide-based luminescent thermometers reported to date. The Yb³⁺ analog enables intensity-based thermometry in the near-infrared domain with a good sensitivity S_rmax = 0.5%·K⁻¹ at 293 K, δT = 0.5 K at 303 K, and $\overline{\delta T}$ = 1.6 K. These molecular thermometers were further incorporated into the shell of Prussian Blue@SiO₂ core–shell nanoparticles. Among the resulting hybrids, PB@SiO₂-acac/(1Tb/1Eu) (with a Tb/Eu ratio of 2/8) stood out by enabling ratiometric temperature sensing based on the Eu³⁺⁵D₀ → ⁷F₂ lifetime, with satisfactory parameters (S_rmax = 0.9%·K⁻¹, δT = 0.21 K at 303 K, and $\overline{\delta T}$ = 1.1 K). These results highlight the potential of simple coordination complexes and their nanohybrids for advanced luminescent thermometry applications. Full article

To address the problems of eutrophication exacerbation in water bodies caused by low carbon-to-nitrogen ratio (C/N) wastewater and the limited nitrogen removal efficiency of conventional constructed wetlands, this study proposes the use of biochar (Corncob biochar YBC, Walnut shell biochar HBC, and Manure biochar FBC) coupled with intermittent aeration technology to enhance nitrogen removal in constructed wetlands. Through the construction of vertical flow wetland systems, hydraulic retention time (HRT = 1–3 d) and influent C/N ratios (1, 3, 5) were regulated, before being combined with material characterization (FTIR/XPS) and microbial analysis (16S rRNA) to reveal the synergistic nitrogen removal mechanisms. HBC achieved efficient NH₄⁺-N adsorption (32.44 mg/L, Langmuir R² = 0.990) through its high porosity (containing Si-O bonds) and acidic functional groups. Under optimal operating conditions (HRT = 3 d, C/N = 5), the CW-HBC system achieved removal efficiencies of 97.8%, 98.8%, and 79.6% for NH₄⁺-N, TN, and COD, respectively. The addition of biochar shifted the dominant bacterial phylum toward Actinobacteriota (29.79%), with its slow-release carbon source (TOC = 18.5 mg/g) alleviating carbon limitation. Mechanistically, HBC synergistically optimized nitrogen removal pathways through “adsorption-biofilm (bacterial enrichment)-microzone oxygen regulation (pore oxygen gradient).” Based on technical validation, a dual-track institutionalization pathway of “standards-legislation” is proposed: incorporating biochar physicochemical parameters and aeration strategies into multi-level water environment technical standards; converting common mechanisms (such as Si-O adsorption) into legal requirements through legislative amendments; and innovating legislative techniques to balance precision and universality. This study provides an efficient technical solution for low C/N wastewater treatment while constructing an innovative framework for the synergy between technical specifications and legislation, supporting the improvement of watershed ecological restoration systems. Full article