Double emulsion (W/O/W) gel stabilised by polyglycerol polyricinoleate and calcium caseinate as mangiferin carrier: insights on formulation and stability properties

Mangiferin (MGF) is a phenolic compound isolated from mango, but its poor solubility significantly limits its use. In this study, MGF was embedded into the inner aqueous phase of W₁/O/W₂ emulsions. Firstly, the dissolution method of MGF was determined. MGF remained stable in solution with pH 13 at 30 min, and its solubility reached 10 mg mL⁻¹. When the pH of MGF solutions was adjusted from pH 13 to pH 6, MGF did not immediately crystallise, providing sufficient time to construct the MGF-loaded W₁/O/W₂ emulsions. Subsequently, the MGF-loaded W₁/O/W₂ emulsions were constructed using polyglycerol polyricinoleate (PGPR) and calcium caseinate (CAS). The formation and stability of the W₁/O/W₂ emulsions were investigated. The MGF-loaded W₁/O/W₂ emulsions stabilised with 1% PGPR and 1% – 3% CAS exhibited a low viscosity, limited loading capacity, and poor stability. Conversely, the MGF-loaded W₁/O/W₂ emulsions stabilised by 3%PGPR–3%CAS exhibited optimal loading capacity (encapsulation efficiency = 95.31% and loading efficiency = 0.91%) and stability, which was attributed to the fact that high viscosity and gel state retarded the migration of inner aqueous phase. These results indicated that the W₁/O/W₂ emulsions stabilised by PGPR and CAS may be a potential alternative for encapsulating mangiferin.     

Fabrication of high-efficiency Yb:Y2O3 laser ceramics without photodarkening

High-efficiency Yb:Y₂O₃ laser ceramics were fabricated using the vacuum-sintering plus hot isostatic pressing (HIP) without sintering additives. High-purity well-dispersed nanocrystalline Yb:Y₂O₃ powder was synthesized using a modified co-precipitation method in-house. The green bodies were first vacuum sintered at a temperature as low as 1430°C and then HIPed at 1450°C. Finally, the samples were air annealed at 800°C for 10 h. Although no sintering aids were used, full density of the samples with excellent optical homogeneity and an inline transmission of 80% at 400 nm could be obtained. Moreover, photodarkening phenomenon was not detected in the ceramics. Preliminary laser experiment with the fabricated ceramics in a two-mirror cavity has demonstrated 32 W continuous-wave (CW) output at ∼1077 nm with an optical-to-optical conversion efficiency of 58.2%. To the best of our knowledge, this is so far the highest CW output power and optical-to-optical conversion efficiency achieved with the Yb³⁺-doped sesquioxide ceramics in a simple two-mirror cavity.     

Ag nanoparticles-polypyrrole-carbon black/mesoporous TiO2 novel nanocomposite as ultrafast visible-light-driven photocatalyst

Effective design and fabrication of novel visible light-oriented photocatalysts is an existing challenging task that requires further dedicated efforts, and it has been always a main concern among the scientific community. This study deals with the design and fabrication of an extremely active and ultrafast ternary photocatalyst based on Ag nanoparticles, polypyrrole doped carbon black (PPy-C) and mesoporous TiO₂ (m-TiO₂). Sol-gel methodology along with sonication and photodeposition routes have been employed for the successful creation of the ternary framework. Ternary photocatalyst composed of uniform spherical titania nanoparticles (10–15 nm in size) perfectly intermingled with the polymeric linkage of PPy-C. Fruitful creation of unique trio photocatalyst between AgNPs, PPy-C and m-TiO₂ was confirmed by XPS and XRD. FTIR analysis further supports the development of nanocomposite photocatalyst. TEM analysis showed uniform spherical m-TiO₂ nanoparticles (10–15 nm in size) covered by PPy-C with compact nodes like appearance interlocked very well among each other. The newly developed Ag@PPy-C/m-TiO₂ ternary photocatalyst exhibited band gap energy in desired visible range of spectra. The photocatalytic efficiency for all created photocatalysts has been evaluated taking Imidacloprid (insecticide derivative) and methylene blue (MB) dye as target pollutants. The novel Ag@PPy-C/m-TiO₂ photocatalyst produced astonishing results with ultrafast removal of both Imidacloprid as well MB dye under visible light irradiation. The newly created ultrafast Ag@PPy-C/m-TiO₂ photocatalyst has removed 96.0% of the insecticide Imidacloprid in only 25 min with almost ? 2.65 times more efficient than bare m-TiO₂ towards the removal of insecticide derivative. The present report offers a highly encouraging and vastly talented Ag@PPy-C/m-TiO₂ ternary photocatalyst, enabling the ideal management of extremely lethal and notorious chemicals.     

Cracking behavior and delamination mechanism of lamellar structured TBC with localized mixed oxides

Mixed oxide (MO) with localized growth feature and high growth rate remarkably affects the lifetime of thermal barrier coatings (TBCs), which indicates that clarifying the ceramic cracking mechanism induced by MO is critical for developing new coatings with high durability. Two kinds of TBC models involving spherical and layered mixed oxides are created to explore the influence of MO growth on the local stress state and crack evolution during thermal cycle. The growth of α-Al₂O₃ is also included in the model. The undulating interface between ceramic coat and bond coat is approximated using a cosine curve. Dynamic ceramic cracking is realized by a surface-based cohesive interaction. The ceramic delamination by simulation agrees with the experimental observation. The effects of MO coverage ratio and growth rate on the TBC failure are also discussed. The results show that the MO growth causes the local ceramic coat to bear the normal tensile stress. The failure mode of coating is turned from α-Al₂O₃ thickness control to MO growth control. Once the mixed oxide appears, local ceramic cracking is easy to occur. When multiple cracks connect, ceramic delamination happens. Suppressing MO formation or decreasing MO growth can evidently improve the coating durability. These results in this work can provide important theoretical guidance for the development of anti-cracking TBCs.     

A modified Kozeny–Carman equation for predicting saturated hydraulic conductivity of compacted bentonite in confined condition

Kozeny–Carman (KC) equation is a well-known relation between hydraulic conductivity and pore properties in porous material. The applications of KC equation to predicting saturated hydraulic conductivities of sands and non-expansive soils are well documented. However, KC equation is incapable of predicting saturated hydraulic conductivity of expansive soil (e.g. bentonite) well. Based on a new dual-pore system, this study modified KC equation for improving the prediction of saturated hydraulic conductivities of bentonites. In this study, an assumption that inter-layer space (micropore) has limited effect on fluid flow performance of compacted bentonite was adopted. The critical parameters including total porosity and total tortuosity in conventional KC equation were replaced by macroporosity and tortuosity of macropore, respectively. Macroporosity and microporosity were calculated by basal spacing of compacted bentonite, which was estimated by assuming that specific surface area is changeable during saturation process. A comprehensive comparison of bentonite's saturated hydraulic conductivity predictions, including modified KC equation proposed in this study, conventional KC equation, and prediction method based on diffuse double layer (DDL) theory, was carried out. It was found that the predicted saturated hydraulic conductivity of bentonites calculated using modified KC equation fitted the experimental data better than others to a certain extent.     

Optimization of hydrogen enrichment via palladium membrane in vacuum environments using Taguchi method and normalized regression analysis

In this study, the separation of hydrogen from gas mixtures using a palladium membrane coupled with a vacuum environment on the permeate side was studied experimentally. The gas mixtures composed of H₂, N₂, and CO₂ were used as the feed. Hydrogen permeation fluxes were measured with membrane operating temperature in the range of 320–380 °C, pressures on the retentate side in the range of 2–5 atm, and vacuum pressures on the permeate side in the range of 15–51 kPa. The Taguchi method was used to design the operating conditions for the experiments based on an orthogonal array. Using the measured H₂ permeation fluxes from the Taguchi approach, the stepwise regression analysis was also employed for establishing the prediction models of H₂ permeation flux, followed by the analysis of variance (ANOVA) to identify the significance and suitability of operating conditions. Based on both the Taguchi approach and ANOVA, the H₂ permeation flux was mostly affected by the gas mixture composition, followed by the retentate side pressure, the vacuum degree, and the membrane temperature. The predicted optimal operating conditions were the gas mixture with 75% H₂ and 25% N₂, the membrane temperature of 320 °C, the retentate side pressure of 5 atm, and the vacuum degree of 51 kPa. Under these conditions, the H₂ permeation flux was 0.185 mol s^?1 m^?2. A second-order normalized regression model with a relative error of less than 7% was obtained based on the measured H₂ permeation flux.     

基于分形理论的黄河内蒙古段河势演变特征及其与凌汛灾害关联研究

寒区河道凌汛灾害河势“弯道效应”的量化评估十分重要。基于分形理论提出河道横断面-纵剖面-平面多维度河势分形维数计算方法及其物理机制，并探讨黄河内蒙古段不同维度河势演变分形特征及其与凌汛灾害的关联关系。结果表明，黄河内蒙古段不同维度河势均具有多尺度自相似分形特征，且具有多年记忆周期的长程相关性；冰坝（严重性冰塞）发生频次与河道主槽弯曲分形维数呈正相关指数型函数关系，与河相系数、深泓点高程和河段平均底坡分形维数负相关，与水深-面积分形维数正相关，总体表明冰坝灾害更易发生于主槽偏移摆动大、蜿蜒曲折、河湾发育程度高的宽浅型弯曲河道，研究成果可为凌汛期冰塞冰坝灾害易发河段诊断及预测提供重要理论依据。