Search Results (716)

To address the poor temperature resistance of conventional gel breakers, the uncontrollable gel-breaking time, and the risk of secondary reservoir damage during temporary plugging of fractured formations with polymer gels, a high-temperature-resistant double-shell encapsulated gel breaker, UF-EC/SA, was prepared using oil-phase phase separation combined with in situ polymerization. In this material, urea-formaldehyde resin (UF) served as the outer shell, ethyl cellulose (EC) as the inner shell, and sulfamic acid (SA) as the core. Unlike conventional single-shell persulfate or directly added acid breakers, this double shell design integrates a thermally resistant UF barrier, a diffusion-controlling EC layer, and an acid core to delay premature gel degradation while enabling subsequent cleanup. The physical structure and sustained-release behavior of the capsules were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), and conductivity measurements. The compatibility between the encapsulated breaker and the polymer gel, as well as the effects of salinity and breaker dosage on the rheological properties of the gel, were investigated. The regulatory effects of temperature and capsule dosage on gel-breaking performance were studied in detail. In addition, high-temperature/high-pressure displacement experiments were conducted to evaluate the temporary plugging performance of the gel containing the encapsulated breaker in fractured cores and packed-sand tubes. The results showed that the prepared capsules had good sphericity and a dense shell structure, with an encapsulation efficiency of 76.7%. The capsules exhibited temperature resistance up to 150 °C and favorable sustained-release characteristics. The UF-EC/SA breaker showed good compatibility with the polymer gel and did not inhibit gelation within the temperature range of 80–150 °C or at dosages of 0–16 wt.%. The gel maintained good mechanical strength even in highly mineralized brines. At 150 °C and a capsule dosage of 16 wt.%, the gel was completely broken within 2.5 d; the residue concentration was only 351 mg/L, and the residue size was mainly distributed within 100–500 um. The high-temperature/high-pressure displacement tests demonstrated that the gel containing 16 wt.% capsules achieved a maximum breakthrough pressure of 5.16 MPa in a 3 mm wedge-shaped fracture core, and the pressure remained stable for 5 d. After gel breaking, the residue could be readily flowed back, indicating excellent synergy between temporary plugging and subsequent gel breaking. Therefore, the UF-EC/SA encapsulated breaker provides a new technical option for efficient gel breaking in high-temperature fractured formations. Full article

Objectives: this study aimed to develop and optimize an intranasal delivery system for Eplerenone (EPL) by incorporating Eplerenone-loaded liposomes (Elip) into an in situ gel system (Elip-GG). The goal was to prolong the residence time of the drug in the nasal cavity and ensure sustained release. Methods: Elip and unloaded liposomes were prepared using the thin-film hydration method. Key formulation variables such as encapsulation efficiency (EE%), mean particle size (MPS), polydispersity index (PDI), and zeta potential (ZP) were optimized. The Elip was then incorporated into a gellan gum (GG) in situ gel to form Elip-GG. The Elip-GG formulation was evaluated based on parameters such as pH, viscosity, rheological behavior, mechanical properties, and in vitro release. Results: the optimal Elip formulation exhibited an EE of 86.3%, a mean particle size of 86.56 nm, a PDI of 0.29, and a ZP of −29.86 mV. The cumulative drug release from the Elip-GG formulation exceeded 93% after 2.5 h. The Elip-GG formulation significantly increased the sustained release of Eplerenone when administered intranasally, offering a promising alternative to oral and parenteral delivery methods for hydrophilic antihypertensive drugs. Full article

Background/Objectives: Insomnia severely impairs quality of life. Oral melatonin (MEL) suffers from poor brain delivery. Intranasal administration bypasses the blood–brain barrier, but rapid mucociliary clearance shortens drug retention, and MEL poor water solubility limits its nasal dissolution. Traditional in situ gels have “gelation-first, spreading-second” defects, causing uneven distribution. Herein, we developed a two-step sequential ion-triggered in situ gel combined with MEL liposomes (MEL-Lips-Gel) to enhance solubility, achieve instant uniform coating, and prolong retention for efficient nose-to-brain delivery. Methods: MEL-Lips were dispersed in alginate (first component) and calcium gluconate served as the second component. After sequential spray, the two components mix and form an ion-crosslinked gel. Rheology, in vivo fluorescence imaging, in vitro release, open-field/sucrose preference tests, and H&E staining were performed. Results: MEL-Lips showed uniform size and good encapsulation. The sequential system achieved instant widespread spreading and rapid gelation, significantly prolonged nasal retention, enabled sustained brain delivery, and reversed insomnia-induced hyperactivity and anxiety-like behaviors more effectively than oral MEL, intranasal MEL solution, liposomes alone, or non-liposomal gel, with good nasal safety. Conclusions: This sequential ion-triggered liposome-in-gel strategy synergistically overcomes rapid clearance (via gel) and poor solubility (via liposomes), enhancing nose-to-brain delivery of melatonin and providing a promising platform for insomnia therapy. Full article

In the present research, lanthanum ferrite nanoparticles (LaFeO₃ NPs) and lanthanum ferrite polypyrrole (LaFeO₃/PPy) nanocomposites were synthesized and evaluated for electrochemical sensing of TNZ in biological and pharmaceutical samples. LaFeO₃ NPs were synthesized using the sol–gel auto-combustion method, whereas LaFeO₃/PPy nanocomposites were produced through an in situ chemical oxidative polymerization process. The obtained materials were subjected to comprehensive characterization by multiple analytical techniques, including XRD, which confirms an orthorhombic crystal structure; SEM micrographs of LaFeO₃ NPs and LaFeO₃/PPy nanocomposites exhibit a highly agglomerated structure with non-uniform particle distribution and a more homogeneous, smoother surface morphology, respectively, with an average size of <70 nm. The LaFeO₃/PPy nanocomposites exhibited an electron-transfer process governed by diffusion, as evidenced by cyclic voltammetry (CV) analysis. Using differential pulse voltammetry (DPV), the sensor achieved quantitative detection across a linear concertation range of 0.1–230 µM (R² = 0.997), with a detection limit (0.023 µM). The developed sensor demonstrated excellent stability, remarkable sensitivity, and high reproducibility, confirming reliability and suitability (RSD% < 4.0) for the quantitative determination of TNZ in both biological and pharmaceutical matrices. Full article

The corrosion behavior and time-dependent mechanism of 22MnB5 steel featuring a thinned Al-Si coating (60 g/m²) were systematically investigated in a chloride ion wet–dry cyclic environment, motivated by the demand for thinning and toughening development of aluminum-silicon coatings. A periodic immersion accelerated corrosion test using 3.5% NaCl solution was conducted, together with macro/microscopic morphology observation (SEM/EDS), phase analysis (XRD, FTIR), and electrochemical measurements (polarization curves, EIS). The Al-Si coated steel was studied over corrosion periods of 1, 8, 10, and 20 days to elucidate its corrosion behavior, interfacial evolution, and failure mechanism. The results indicated that the corrosion process exhibited a three-stage evolution: stable protection, rapid failure, and dynamic equilibrium. At the initial stage (1 day), a dense Al₂O₃ passive film formed on the coating surface, providing excellent substrate protection, with a corrosion current density of only 1.77 µA/cm² and a maximum charge-transfer resistance (R₂) of 652 Ω·cm². In the middle stage (8 days), Cl⁻ permeated through the cracked film, triggering selective dissolution of Al, while Si was enriched in situ to form a porous residual layer; the corrosion current density (I_corr) sharply increased to 13.25 µA/cm², and R₂ dropped to its minimum of 156.6 Ω·cm². Corrosion products at this stage were mainly Al₂O₃ and SiO₂, accompanied by small amounts of iron oxyhydroxides and hydroxides, and local coating failure began to appear. During the later stage (10–20 days), the corrosion products evolved into γ-FeOOH, α-FeOOH, and Fe₂O₃, which, together with an amorphous SiO₂ gel network enriched at the interface, formed a dual-layer composite rust layer. R2 consequently recovered from 156.6 Ω·cm² at 8 days to 424 Ω·cm² at 20 days, indicating a reduced corrosion rate and entry into a stable inhibition stage. The critical failure mechanism is that Cl⁻ preferentially penetrates the surface of the Al₂O₃ passive film, disrupting the metastable state of the coating and thereby creating pathways for corrosive media intrusion. The findings of this study can provide technical support for the safe application of such as-received coatings in non-load-bearing components with heat and corrosion resistance requirements. Full article

Using the gel-grown method to control the morphology of crystals attracts extensive attention. Potassium dihydrogen phosphate (KDP) is a nonlinear optical crystal with a high laser damage threshold. Here, we studied the crystallization of KDP in silica gel. The kebab-like KDP crystals (multiple KDP crystals aligning along a straight line) were prepared in the silica gel. In situ observation revealed that the kebab-like crystals were obtained through secondary nucleations on preformed needle-like crystals. Further investigation revealed that the hydroxyl groups on the gel network have an important influence on the formation of kebab-like KDP crystals. The hydroxyl groups on the gel networks can form hydrogen bonds with the phosphoric acid group of the KDP crystal and hinder the growth of the prismatic KDP faces, which leads to the preformation of needle-like crystals. Additionally, the influence of the acetic acid concentration and antisolvent on morphology was also studied. Full article

Mullite fiber materials are widely used in high-temperature thermal insulation applications, especially in aerospace thermal protection systems, due to their excellent thermal stability and low thermal conductivity. However, the material exhibits poor resistance to infrared radiative heat transfer at elevated temperatures. Accordingly, a dual-opacifier system composed of TiO₂ and K₂Ti₆O₁₃ binary whiskers was proposed as an effective strategy for enhancing thermal insulation performance. MF/TiO_2w and MF/TiO_2w/K₂Ti₆O_13w were fabricated in this study using a sol–gel method combined with in situ whisker growth. The results show that upright and interlaced K₂Ti₆O₁₃ and TiO₂ whiskers were uniformly grown on the fiber surface, contributing to a high infrared reflectance of 97.7% in the wavelength range of 2.5–10 μm. Under a front-side temperature of 1000 °C, the modified mullite fiber-based material exhibits a backside temperature of 177.8 °C, corresponding to a reduction of 71.8 °C compared with the original sample (249.6 °C), demonstrating significantly enhanced thermal insulation performance. In addition, the composite exhibits an ultralow density of less than 0.20 g/cm³. The as-prepared thermal insulation material shows a high rebound rate of 76.5% at a strain of 30%, indicating good elasticity. The results demonstrate that the developed composite exhibits excellent infrared shielding and structural stability, confirming that the binary whisker strategy effectively enhances the thermal insulation performance of the mullite fiber-based materials, highlighting its potential for high-temperature aerospace applications. Full article

This study reports a dual composition-interface engineering strategy for high-performance La_1−xSr_xCoO₃/NiFe-LDH hierarchical heterojunction. Porous La_1−xSr_xCoO₃ microspheres were synthesized through a gel route. Then it was used as an in situ–formed template to grow NiFe-LDH nanosheets. The hierarchical design inhibits nanosheet aggregation and ensures robust interfacial contact, mitigating the intrinsic instability of physical mixtures. The prepared composite displays superior OER performance in 1.0 M KOH, delivering an overpotential of 237.8 mV at 10 mA cm⁻² and a Tafel slope of 85.06 mV dec⁻¹. These values exceed those of the original samples and commercial RuO₂ and the composite exhibits excellent long-term stability under harsh alkaline conditions. Complemented by DFT calculations, we further indicate that Sr doping coupled with the heterointerface induces substantial electronic structure reconstruction. This effectively switches the OER mechanism from conventional AEM to the thermodynamically more favorable LOM, overcoming the intrinsic scaling relation constraints of AEM. Full article

For personalized treatments, including soft tissues repair, the use of in situ bioprinting is of increased interest. Many soft tissues, such as sphincters, have poorly known mechanical properties and a complex structure, with limited options for a medical practitioner to assess where the injections should be made and how much should be injected. The rate of injection and its variation have a direct implication on pain sensation for patients, but post-injection efficacy largely depends on the ability of the hydrogel to adapt to local loads and displacements, keeping the 3D structure compliant to the surrounding tissues. Such a method is known as ‘in situ bioprinting’. There are, however, limited data regarding hydrogels’ functionalities for such applications, and many commercial hydrogels, as medical devices, are used off-label. This study aims to introduce an innovative, robust, and reliable approach for evaluating the ejection-related mechanical properties of various commercial hydrogels. The ejectability of six clinically approved hydrogels was assessed through their rheological properties, characterized by measuring apparent viscosity using a mechanical testing device in a novel setup combined with the dynamic syringe pump analysis (for a pre-set constant ejection rate). It was shown that a well-established power-law approximation offers a straightforward, less computationally intensive approach than more complex models that attempt to account for viscosity, shear rate, and wall slip. It assesses hydrogel performance within an actual system, including the syringe and nozzle, rather than just characterizing the material in isolation, thus making it particularly valuable for predicting how gels will behave under real conditions. This method can be adapted for specific clinical bioprinting applications, including sphincter repair, lipoatrophy correction, or deep dermal/transdermal targets, optimizing speed, flow rate, and applied force. Full article

The long-term exposure of asphalt pavement to ultraviolet radiation causes significant performance degradation and reduces its service life. To enhance the UV resistance of asphalt, nanocomposite modifiers have been incorporated through mechanical blending. However, their effectiveness has been largely limited by poor component uniformity. To address this issue, UV-resistant antioxidant nano-TiO₂ was employed to modify the UV-shielding of layered porous carbon (PC), resulting in the synthesis of nano-TiO₂ intercalated PC (TiO₂/PC). The PC nanosheet was modified by TiO₂ nanoparticles via in situ growth, significantly improving the dispersion homogeneity of TiO₂. Comprehensive characterization (SEM/EDS/FT-IR/XPS) confirmed the successful synthesis of TiO₂/PC with well-defined interfacial bonding. Compared to control samples (PC, TiO₂, and TiO₂ + PC), the asphalt modified by TiO₂/PC-2 composite demonstrated superior UV aging resistance, lower physical aging indices and reduced rheological aging parameters. Moreover, TiO₂/PC modifier prominently suppressed the formation of oxidative groups (C=O/S=O), improved the colloidal stability, and delayed the sol–gel transition of the modified asphalt. The synergistic UV shielding mechanism was attributed to the enhanced UV absorption of TiO₂, multi-reflection and scattering within the PC matrix, and the radical scavenging capabilities of both components. These results provide new design insights for developing anti-UV aging modifiers for asphalt pavements. Full article

The fabrication of complex architectures remains a central challenge in 3D bioprinting, as the low mechanical properties of hydrogels limit the range of achievable geometries. Four-dimensional (4D) bioprinting can address these limitations by enabling programmed shape-morphing behavior; however, in most approaches, this functionality is introduced after hydrogel formation, limiting the complexity of the resulting deformation. Here, a proof-of-concept strategy is presented, in which shape-morphing is directly encoded during fabrication. By modulating light exposure time layer-by-layer in vat photopolymerization, spatial variations in crosslinking density are introduced in situ within Gelatin Methacryloyl (GelMA) hydrogel constructs. Exposure times in the range of 20–70 s were investigated, enabling controlled bending of the printed structures upon immersion in aqueous media, with radii of curvature between 11 and 20 mm depending on the geometry. This approach allows deformation pathways to be programmed during printing, without requiring additional materials or post-processing steps. The morphing behavior was further supported by finite element simulations, which reproduced the experimentally observed deformation and enabled prediction of the shape change. In addition, high cell viability (>95%) was maintained after material contact and UV exposure. Overall, this study demonstrates that swelling-driven actuation can be encoded during fabrication. Although demonstrated on simplified geometries, this approach provides a versatile framework for process-driven shape-morphing and represents a step toward more spatially resolved and potentially volumetric 4D bioprinting strategies. Full article

This study investigates the synthesis and kinetic behavior of a magnetic biochar derived from avocado seed biomass for the removal of hexavalent chromium (Cr(VI)) from aqueous solutions. Magnetite (Fe₃O₄) was synthesized through different routes, including nitrogen-assisted coprecipitation, redox-controlled coprecipitation, polyol, sol–gel, and sonochemical methods, to evaluate their structural properties and iron incorporation efficiency. Based on compositional and crystallographic analyses, the coprecipitation under an inert atmosphere exhibited improved phase purity and higher Fe₃O₄ content, which was selected for in situ incorporation onto biochar produced by pyrolysis at 450 °C. The resulting magnetic material and composite were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), confirming the suitability of the synthesis method and the successful deposition of magnetite onto the porous carbon matrix while preserving its structural integrity. Batch adsorption experiments were conducted at pH 2.0 to evaluate the effect of adsorbent dose and initial Cr(VI) concentration. The adsorption process reached equilibrium within 120 min and was better described by the pseudo-second-order kinetic model (R² ≥ 0.98), suggesting that chemisorption governs the rate-controlling step, with diffusion phenomena contributing but not dominating the overall mechanism. The maximum adsorption capacity predicted by the kinetic model reached 42.49 mg g⁻¹ at an initial concentration of 100 mg L⁻¹. The results demonstrate that avocado-seed-derived magnetic biochar represents a sustainable and effective material for chromium-contaminated water treatment, integrating agro-industrial waste valorization with enhanced adsorption performance and magnetic separability. Full article

Limited ionic conductivity and unstable interfaces, primarily caused by poor solid–solid contact, pose significant challenges to the stable cycling of solid-state batteries. In this study, an interfacial in situ polymerization strategy is proposed to construct a poly(1,3-dioxolane) (PDOL) gel electrolyte layer between a poly(vinylidene fluoride) (PVDF)-based solid polymer electrolyte and the electrodes. This approach aims to address interfacial compatibility issues in solid-state lithium metal batteries. By precisely tuning the composition of the gel precursor and employing characterization techniques such as FTIR and NMR, the efficient ring-opening polymerization of 1,3-dioxolane (DOL) was confirmed, achieving a high conversion rate of 90%. The precursor was drop-cast onto the PVDF-based electrolyte/electrode interfaces before cell assembly. Electrochemical evaluations revealed that the in situ formed solidified interlayer significantly enhanced interfacial compatibility and ion transport, yielding a high Li⁺ transference number (0.341), an exceptional critical current density (1.4 mA cm⁻²), and remarkable cycling stability exceeding 1600 h in Li||Li symmetric cells. Furthermore, full cells incorporating LiFePO₄ cathodes demonstrated excellent rate capability and long-term cyclability, retaining 98.7% of their capacity after 1000 cycles. These results collectively underscore the effectiveness of this in situ solidification strategy in optimizing the interface structure and improving the overall performance of PVDF-based solid-state batteries. Full article

Polymer gel profile control technology can effectively modify water flow channels in water-flooded oil reservoirs and enhance oil recovery. However, most polymer gel systems exhibit poor performance, such as low strength, not suitable for high-temperature and high-salinity reservoir conditions, leading to ineffective water shutoff. To address this challenge in complex formations of high-temperature, high-salinity fractured reservoirs, a temperature- and salt-tolerant polymer gel system with delayed crosslinking was developed based on the concept of slow hydrogen-bond crosslinking. Laboratory evaluations demonstrated that a gel system formulated with 0.4 wt% HPAM and 0.2 wt% PEI (HPAM/PEI) achieved a gel strength grade of G index. Even at 100 °C or a salinity of 200,000 ppm, the HPAM/PEI system maintained a gel strength grade of F, indicating excellent temperature resistance and shear stability. The slow hydrogen-bond crosslinking mechanism endowed the system with delayed gelation characteristics. Sandpack and core flooding experiments confirmed that the HPAM/PEI system could form high-strength gels in situ with low polymer retention. After treatment, the permeability of the core was reduced by over 99%, and the effective blocking duration exceeded 12 months. This study provides a theoretical foundation for applying the HPAM/PEI gel system in deep profile control and water shutoff in high-temperature and high-salinity reservoirs. Full article

The continuous drive for higher efficiency in gas turbines has led to increased combustion temperatures, making the thermal shock resistance of thermal insulation tiles a critical factor limiting performance. Corundum–mullite multiphase ceramics are widely used in such applications; however, their performance is often constrained by an inherent trade-off between mechanical strength and thermal shock resistance. In this work, a synergistic modification strategy based on rare-earth disilicate phases was developed, wherein Y₂O₃ and SiC were incorporated into a corundum–mullite matrix to enable in situ formation and controlled distribution of Y₂Si₂O₇ via gel casting. During sintering, Y₂Si₂O₇ acts as a transient liquid phase, facilitating densification and grain boundary strengthening; upon thermal shock, it migrates to fill and heal grain boundaries and microcracks, thereby significantly enhancing thermal shock resistance. The optimized sample S5, sintered at 1400 °C, exhibited a bulk density of 2.12 g/cm³ and a bending strength of 68.43 MPa. Notably, after 30 thermal shock cycles (air cooling from 1000 °C to RT), its bending strength increased to 79.71 MPa, corresponding to a 16.48% enhancement. This work provides an effective strategy for incorporating rare-earth disilicates into multiphase ceramics and offers valuable guidance for the development of high-performance components for gas turbines. Full article