Search Results (92)

Compared with vanadium extraction by sodium roasting followed by water leaching, the calcification roasting–sulfuric acid leaching method is considered a promising approach for the comprehensive utilization of vanadium titanomagnetite, as it avoids the introduction of alkali metals. However, during vanadium extraction by sulfuric acid heap leaching, the diffusion of leaching reagents and leaching products was hindered by the deposition of leaching solid products. To address this issue, this study systematically investigated the leaching kinetics and the mechanisms underlying the deposition of leaching solid products. The results indicated that vanadium leaching was governed by a combination of liquid film diffusion and internal diffusion through solid-phase products during days 0–2, and by internal diffusion alone from day 2 to day 9. The primary solid products formed during leaching were calcium sulfate and silica gel. Calcium sulfate precipitated and grew within the pore via two-dimensional nucleation, while silicates formed silica gel through dehydration. By optimizing the sulfuric acid leaching conditions—specifically, maintaining an H⁺ concentration of 2 mol/L, a leaching temperature of 40 °C, and a liquid-to-solid ratio of 5:1—the formation of calcium sulfate and silica gel was effectively suppressed. Under these conditions, the vanadium leaching efficiency reached 75.82%. Full article

Solid Fe catalysts supported on SiO₂ with Lewis and Brönsted acidity were synthesized using sol–gel methodology. FTIR spectroscopy, XRD, Raman spectroscopy, BET isotherms, and SEM characterized the materials. Subsequently, they were used to dehydrate xylose to obtain furfural. It was observed that increasing the metal loading from 0.5% to 1.5% by mass increases the selectivity of furfural up to 40.09%. In addition, the calcination temperature influenced the conversion because materials calcined at 450 °C presented higher xylose conversion than those calcined at 750 °C. Finally, the employed catalysts were active and effective in obtaining furfural from hydrolysates via hydrothermal treatments of a coffee crop’s residual biomass, producing an average of 9.11 mg/g of furfural per gram of biomass. Full article

NASICON-type titanium and zirconium phosphates doped with rare-earth cations, A_0.33M₂(PO₄)₃ (M = Ti, Zr; A = Dy, Y, Yb), were synthesized using the sol–gel method and investigated as catalysts for ethanol dehydration at 300–400 °C. The catalysts were characterized via XRD, SEM, BET, and FTIR spectroscopy. The relationships between the catalyst composition, acidity and the dehydration activity were evaluated. Diethyl ether (DEE) formation is promoted by the presence of the zirconium phosphates (ZrP), while the presence of titanium phosphate (TiP) catalyzes the formation of both ethylene and diethyl ether (DEE). The application of Fourier-transform infrared (FTIR) spectroscopy to the analysis of adsorbed C₆H₆ has revealed the presence of hydroxyl groups exhibiting varying degrees of proton-donating mobility. This finding has enabled the correlation of the structure of the active sites with the process’s selectivity. The results underscore the key function of OH-group localization and framework geometry in the control of form-selective reactions. Full article

Ion-conductive gels (ICGs) are essential for achieving human–machine interfaces, bioelectronic applications, or durable wearable sensors. However, traditional solvent-dependent ICGs face bottlenecks such as dehydration-induced failure and challenges in achieving a balance between conductivity and mechanical properties. Here, this work developed a novel ternary ion-conductive xerogel (PEM-Li ICXG) system based on polyethylene glycol (PEG), poly (2-methoxyethyl acrylate) (PMEA), and LiTFSI. PEM-Li ICXGs exhibit high conductivity (2.7 × 10⁻² S/m), high adhesive capability (0.34 MPa), and solvent-free characteristics. Remarkably, the incorporation of ions into ICXGs simultaneously optimizes their mechanical performance. We demonstrate the application of ICGs in flexible sensors for strain or temperature sensing. The proposed synthesis strategy is straightforward and may further inspire the design of novel high-performance ICXGs. Full article

Polybutylene succinate (PBS) is a biodegradable aliphatic polyester with excellent thermal stability, mechanical properties, and processability. The synthesis of PBS typically employs titanium-based catalysts like tetrabutyl titanate (TBT) to accelerate the reaction. However, TBT acts as a homogeneous catalyst and is non-recyclable. This study aims to minimize the cost of recovering liquid TBT catalyst during PBS synthesis by using TBT-loaded activated carbon for direct esterification and optimizing the process conditions. The catalyst was analyzed using inductively coupled plasma emission spectroscopy, automated specific surface area and pore size analysis, X-ray diffraction, and Fourier-transform infrared spectroscopy. The product was evaluated through infrared spectroscopy, nuclear magnetic resonance hydrogen spectra, and gel permeation chromatography. The optimal process parameters were determined to be an esterification temperature of 170 °C, a polycondensation temperature of 235 °C, an acid-to-alcohol molar ratio of 1:1.2, a catalyst amount of 0.06 g, and a dehydration time of 3 h. Under these conditions, the weight-average molecular weight of PBS reached 47,655, reducing the catalyst usage from 0.5% to 0.3%, resulting in a 24.7% increase in catalytic efficiency compared to TBT, significantly lowering costs. After five cycles of reuse, the weight-average molecular weight of the product remained above 35,000. This study demonstrates that TBT-loaded activated carbon exhibits superior catalytic performance, offering a cost-effective and efficient method for industrial PBS production with broad application potential. Full article

DPR refers to the fact that the reduction in the permeability of the water phase is much greater than the reduction in the permeability of the oil phase when a water-based gel seals porous media. In order to clarify the mechanisms of the gel-plugging pore pathway and the principle of the oil phase and water-phase permeability change, gel-plugging core replacement experiments and NMR T2 scanning experiments were conducted in this work. Based on the nuclear NMR T2 spectroscopy, the core blocked with Cr (III)–acetate–HPAM gel is divided into five stages (a plug injection and seal gel-formation stage, an oil-phase repulsion stage, a stopping-gel reabsorption stage, an oil-phase reinjection stage, and a subsequent water-drive stage) for displacement and scanning, and the signal changes of various phases in the displacement process are studied. The principle of an oil-phase permeability increase after Cr (III)–acetate–HPAM gel plugging, and the principle of a disproportionate decrease in water-phase permeability in the subsequent water-flooding stage were finally revealed. According to the results, the difference in the permeability leads to some diversity in NMR T2 curves, but the final conclusions for the mechanisms are consistent. They show a significant decrease in core permeability of 3.5 × 10⁻³ μm² and 0.8 × 10⁻³ μm² after gel plugging. With the injection of the oil phase, the permeability of the oil phase keeps increasing from 0.13 × 10⁻³ μm² to 0.76 × 10⁻³ μm² in the core permeability of 3.5 × 10⁻³ μm². Similarly, the permeability of the oil phase increases from 0.03 × 10⁻³ μm² to 0.19 × 10⁻³ μm² in the core permeability of 0.8 × 10⁻³ μm². During the oil-phase replacement phase, gel replacement in the large pores is the main cause of the increase in oil-phase permeability, and as the replacement process progresses, the mechanism for the increase in oil-phase permeability changes, and gel dehydration becomes the main mechanism for the increase in oil-phase permeability. Full article

At present, the evaluation perspective of the gel plugging agent assessment method is incomprehensive, due to which the experimental results deviate from the field data. By analyzing the current indoor evaluation methods and the factors controlling the sealing capability of gel plugging agents, an experimental device and method for evaluating the blocking effect of oilfield gel plugging agents has been designed. In contrast to traditional assessment methods, the proposed approach offers advantages such as simple operation, rapid experimentation, and accurate results. The experimental results show that gels selected using conventional methods are inconsistent with the results of plugging displacement tests. This discrepancy can be attributed to the fact that these methods focus solely on cohesive strength while neglecting adhesive strength. Considering that the evaluation perspective of conventional methods is relatively limited, an evaluation method for the sealing effect of the plugging agent was developed. This method comprehensively incorporates factors such as cohesion strength, adhesion capability, shear resistance, and the long-term anti-dehydration performance of the gel. The evaluation results of the method were consistent with the results of the plugging displacement experiments. The newly constructed method defines Γ as the comprehensive evaluation parameter for the gel. A new experimental system with a comprehensive evaluation index (Γ) of 8.97 Pa² was selected. After the profile control of the system, the effluent ratio of the high and low permeability layers reached 1:9, and its erosion resistance was greater than 20 PV. Meanwhile, the profile control effect was also stable. Through verification based on field data, the injection pressure of the system optimized by the proposed method was found to be 2.5 times higher than that of the original system. Meanwhile, the plugging validity period was >2 times of the original system. The test results were consistent with the plugging capability evaluation index. In summary, the performance evaluation method of the designed gel plugging agent was reasonable in principle and the results were accurate and reliable. Therefore, it is considered to be of guiding significance for the selection of efficient profile control plugging agents in oilfields. Full article

The present study investigates the cryopreservation of embryonic axes from the peanut genotype ECU-12466, demonstrating a successful protocol involving a 1 h desiccation on silica gel followed by a 1 h cryoprotection with Plant Vitrificatin Solution 2 (PVS2). The average dimensions of the excised embryonic axes were 5.6 mm in length and 3.5 mm in width, with plumule lengths averaging 2.2 mm. Notably, germination rates for cryopreserved axes ranged from 71.4% to 85.7%, showing resilience to varying desiccation and PVS2 treatment times, particularly at 1 h. Shoot length was significantly enhanced by a 1 h PVS2 exposure, while longer durations resulted in phytotoxic effects. Rooting rates were higher for samples treated with shorter desiccation periods, with 54% rooting achieved at 1 h of PVS2 exposure, contrasting sharply with just 16% at 2 h. The moisture content of the embryonic axes remained stable between 9.3% and 9.5%, indicating no detrimental impact from the applied treatments. To evaluate the protocol’s broader applicability, five additional peanut genotypes (ECU-11401, ECU-11418, ECU-11448, ECU-11469, and ECU-11494) were tested. While cryopreserved samples demonstrated high germination rates of up to 95.4% after 15 days, the rooting success was significantly lower (25.2%) compared to the control group’s 90.9%. Following transplantation, the growth performance varied among genotypes, with a success rate of 93% for ECU-11494. Overall, this study elucidates the critical parameters for optimizing cryopreservation protocols in peanut embryonic axes, contributing to more effective long-term conservation strategies. Full article

To promote the application of freeze-thaw-dehydrated (FTD) potatoes and their gels, this study aimed to investigate the effects of freezing temperature on the physicochemical and gel properties of FTD potato powder and their correlation. The results revealed that, as the freezing temperature decreased, the solubility exhibited an overall downwards trend resulting from soluble solids and amylose liberation. Owing to the better cell integrity at −20 °C, the solubility was greater than that of the other treatment groups. In contrast, the trough viscosity and melting enthalpy increased, and the final viscosity, and setback first increased but then decreased. Regarding the properties of the FTD potato powder gel, the storage modulus, loss modulus, hardness, adhesiveness, chewiness, and consistency first increased but then decreased with decreasing freezing temperature. At a moderate freezing temperature (−20 °C), the solubility and stability of the FTD potato powder were well maintained, and the final viscosity, setback, and hardness reached their highest values. Correlation analysis revealed that, with decreasing freezing temperature, the amount of FTD potato powder initially increased, followed by a decrease in the final viscosity and setback. This trend was positively correlated with the hardness of the FTD potato gel (r = 0.98, r = 0.93). Full article

Background/Objectives: Freeze-drying is a dehydration method that extends the shelf life and stability of drugs, vaccines, and biologics. Recently, its role has expanded beyond preservation to improve novel pharmaceuticals and their carriers, such as hydrogels, which are widely studied for both drug delivery and wound healing. The main aim of this study was to explore the multifunctional role of freeze-drying in improving the physicochemical properties of sodium alginate/poly(vinyl alcohol)-based hydrogels for medical applications. Methods: The base matrix and hydrogels containing a nanocarrier-drug system, were prepared by chemical cross-linking and then freeze-dried for 24 h at −53 °C under 0.2 mBa. Key analyses included determination of gel fraction, swelling ratio, FT-IR, SEM, TG/DTG, in vitro drug release and kinetics, and cytotoxicity assessment. Results: Freeze-drying caused an increase in the gel fraction of the hydrogel with the dual drug delivery system from 55 ± 1.6% to 72 ± 0.5%. Swelling ability was pH-dependent and remained in the same range (175–282%). Thermogravimetric analysis showed that freeze-dried hydrogels exhibited higher thermal stability than their non-freeze-dried equivalents. The temperature at 10% weight loss increased from 194.0 °C to 198.9 °C for the freeze-dried drug-loaded matrix, and from 188.4 °C to 203.1 °C for the freeze-dried drug-free matrix. The average pore size of the freeze-dried hydrogels was in the range of 1.07 µm ± 0.54 to 1.74 µm ± 0.92. In vitro drug release revealed that active substances were released in a controlled and prolonged way, according to the Korsmeyer–Peppas model. The cumulative amount of salicylic acid released at pH = 9.0 after 96 h was 63%, while that of fluocinolone acetonide reached 73%. Both hydrogels were non-toxic to human fibroblast cells, maintaining over 90% cell viability after 48 h of incubation. Conclusions: The results show a high potential for commercialisation of the obtained hydrogels as medical dressings. Full article

Organosilicon materials have shown potential as dehydration agents for waterlogged wooden artifacts. These materials can polymerize under normal conditions to form polymers with favorable mechanical strength, antibacterial properties, and aging resistance. However, the insolubility of most organosilicon hindered their penetration into waterlogged wood, which may lead to an unwanted cracking. This study aimed to evaluate the effectiveness of polydimethylsiloxane (PDMS) and hydroxy-terminated polydimethylsiloxane (PDMS-OH) with low viscosity and moderate reactivity for dehydrating waterlogged wooden artifacts from the Nanhai No.1 shipwreck. Four surfactants ((3–aminopropyl) triethoxysilane (APTES), alkyl polyoxyethylene ether (APEO), tri-methylstearylammonium chloride (STAC), and fatty alcohol polyoxyethylene ether (AEO)) and cosurfactant were employed to transform the two kinds of water-repellent silicone oils into eight groups of highly permeable oil-in-water (O/W) emulsions. Under the catalysis of a neutral catalyst, in situ polymerization occurred within the wood cells. Group P2-2 formulated with PDMS-OH and APEO showed the best efficiency in maintaining the dimensions of the wood during dehydration. The dehydrated wood exhibited a natural color and texture with a minimal volume shrinkage rate of 1.89%. The resulting polymer adhered uniformly to the cell walls, effectively reinforcing the wood cell structure. The weight percent gain of the wood was only 218%, and the pores of the cell lumen were well maintained for future retreatment. This method effectively controlled the sol–gel reaction process of the organosilicon and prevented damage to the wooden artifact during the dehydration process. Moreover, the dehydrated wood samples only experienced a low weight gain of 17% at 95% relative humidity (RH), indicating their great environmental stability. Full article

Polyvinyl alcohol (PVA) hydrogels have a wide range of applications in the pharmaceutical and biomedicine fields due to their exceptional biophysical properties. The study focuses on preparing and characterizing capsule-shaped PVA hydrogels to enhance their biocompatibility and porosity for controlled glucose release and cell proliferation. The hydrogels were prepared using different concentrations (Cs) and molecular weights (MWs) of PVA, with two different lengths, A (10 mm) and B (20 mm), to control glucose release over 60 min. The preparation process involved PVA gel preparation and PVA hydrogel formation. A total of 500 µL of glucose was injected into all dehydrated hydrogels in groups A and B. Glucose release was studied by immersing the hydrogels in saline at 37 °C with stirring at 500 rpm. The SUP-B15 cell line was grown in six A1 hydrogels for biocompatibility testing. The results indicate that all hydrogels remained stable at 37 °C without degrading. Those with a higher C and MW exhibited a denser and less porous structure, lower glucose storage capacity, and higher elongation at break. Significant differences in glucose release, diffusion speed, and flux were observed, which were more evident in A1 > A4, B1 > B4, and B1 > A1 over 60 min. A1 and B1 had higher values because their higher porosity distribution allowed glucose to diffuse more easily. B1, being larger, has more glucose due to its increased length. The cell growth response and viability at 48 h in contact with the hydrogels was similar to that of the control (4.5 × 10⁵ cells/mL, 98.5% vs. 4.8 × 10⁵ cells/mL, 99.7% viability), thus demonstrating biocompatibility. The hydrogels effectively released glucose over 60 min, with variations based on porosity, C, MW, and length, and demonstrated good biocompatibility with the cell line. Full article

In order to further enhance the erosion resistance of cement concrete pavement materials, this study constructed an apparent rough hydrophobic structure layer by spraying a micro-nano substrate coating on the surface layer of the cement concrete pavement. This was followed by a secondary spray of a hydroxy-silicone oil-modified epoxy resin and a low surface energy-modified substance paste, which combine to form a superhydrophobic coating. The hydrophobic mechanism of the coating was then analysed. Firstly, the effects of different types and ratios of micro-nano substrates on the apparent morphology and hydrophobic performance of the rough structure layer were explored through contact angle testing and scanning electron microscopy (SEM). Subsequently, Fourier transform infrared spectroscopy and permeation gel chromatography were employed to ascertain the optimal modification ratio, temperature, and reaction mechanism of hydroxy-silicone oil with E51 type epoxy resin. Additionally, the mechanical properties of the modified epoxy resin-low surface energy-modified substance paste were evaluated through tensile tests. Finally, the erosion resistance of the superhydrophobic coating was tested under a range of conditions, including acidic, alkaline, de-icer, UV ageing, freeze-thaw cycles and wet wheel wear. The results demonstrate that relying solely on the rough structure of the concrete surface makes it challenging to achieve superhydrophobic performance. A rough structure layer constructed with diamond micropowder and hydrophobic nano-silica is less prone to cracking and can form more “air chamber” structures on the surface, with better wear resistance and hydrophobic performance. The ring-opening reaction products that occur during the preparation of modified epoxy resin will severely affect its mechanical strength after curing. Controlling the reaction temperature and reactant ratio can effectively push the modification reaction of epoxy resin through dehydration condensation, which produces more grafted polymer. It is noteworthy that the grafted polymer content is positively correlated with the hydrophobicity of the modified epoxy resin. The superhydrophobic coating exhibited enhanced erosion resistance (based on hydrochloric acid), UV ageing resistance, abrasion resistance, and freeze-thaw damage resistance to de-icers by 19.41%, 18.36%, 43.17% and 87.47%, respectively, in comparison to the conventional silane-based surface treatment. Full article

Trail runners (TRs) must carry an extra load of equipment, food (bars and gels) and liquids, to delay the anticipation of fatigue and dehydration during their competitions. Therefore, we aimed to evaluate how an extra load can influence the metabolic level. Thirteen well-trained trail runners performed a randomized crossover study (total n = 39), completing three treadmill running sessions with a weighted vest of 0%, 5% and 10% of their body mass during a combined test (rectangular test + ramp test). In addition, biomarkers of oxygen metabolism, acid–base and electrolyte status pre-, during and post-test, as well as the rectangular from capillary blood of the finger and time to exhaustion, were analyzed. Repeated-measures ANOVA showed no significant difference between conditions for any of the analyzed biomarkers of blood gas. However, one-way ANOVA showed a significant difference in trial duration between conditions (p ≤ 0.001). Tukey’s post hoc analysis observed a significant decrease in time to exhaustion in the weighted vest of 10% compared to 0% (p ≤ 0.001) and 5% (p ≤ 0.01) and 5% compared to 0% (p = 0.030). In addition, repeated-measures ANOVA detected a significant difference in pH in the group x time interaction (p = 0.035). Our results show that increasing the weighted vest (5% and 10%) anticipates fatigue in runners trained in TR. In addition, increasing the load decreased pH by a smaller magnitude at 10% compared to 0% and 5% at the end of the exercise protocol. Full article

Organic–inorganic hybrid silica materials, incorporating an organic group bridging two silicon atoms, have demonstrated great potential in creating membranes with excellent permselectivity. Yet, the large-scale production of polymer-supported flexible hybrid silica membranes has remained a significant challenge. In this study, we present an easy and scalable approach for fabricating these membranes. By employing a sol–gel ultrasonic spray process with a single-pass method, we deposited a thin and uniform hybrid active layer onto a porous polymer substrate. We first optimized the deposition conditions, including substrate temperature, the binary solvent ratio of the silica sol, and various ultrasonic spray parameters. The resulting flexible hybrid silica membranes exhibited exceptional dehydration performance for isopropanol (IPA)/water solutions (IPA: 90 wt%) in the pervaporation process, achieving a water flux of 0.6 kg/(m² h) and a separation factor of around 1300. This work demonstrates that the single-pass ultrasonic spray method is an effective strategy for the large-scale production of polymer-supported flexible hybrid silica membranes. Full article