Polyelectrolyte screening effects on the dissolution of whey protein gels at high pH conditions

The literature reports an optimum NaOH concentration for the alkaline cleaning of whey deposits or gels; at NaOH concentrations higher than this optimum, cleaning proceeds much more slowly. Although this phenomenon is of great importance in the cleaning of dairy equipment, no conclusive physical explanation has yet been presented. In this study, we present strong evidence that the dissolution rate is affected by the equilibrium-swelling ratio in β-lactoglobulin (βLg) gels. The swelling ratio is greatly reduced in the presence of salts due to the polyelectrolyte screening effect of the cations. This has been observed in free-swelling βLg gels using gravimetrical analysis and in the uniaxial swelling of WPC gel deposits using fluid dynamic gauging. At high dissolution pH (>13.3), the high Na⁺ concentration reduces swelling in spite of the high surface charge of the protein. It is proposed that the reduction of the free volume inside the gel impedes the transport of the protein aggregates out of the NaOH penetration zone. We have also observed that the final dissolution rate of gels pre-soaked in 1 M NaOH or NaCl is similar, despite the difference in pH, and much lower than for untreated gels: the high Na⁺ concentration in the soaked gels hinders swelling, inhibiting the disentanglement of the protein clusters regardless of the high pH.     

镀银纤维分布均匀性与织物抗菌性的关系

探讨镀银纤维在纱线、织物中的分布均匀性对抗茵性的影响.采用琼脂平皿法分别对镀银纤维、镀银纤维介入织物不同技术路线的纱线及其嵌织织物试样的抗茵性进行了测试与分析,结果表明:镀银纤维具有良好的抗菌溶出性,进行抗菌织物设计时,在满足临界用量要求的前提下,可选择混纺、包芯、交捻、交织等多种技术手段开发抗茵织物,但应注意不同的技术手段对分布均匀性要求的差异.     

聚乳酸纤维定量分析方法的研究

通过聚乳酸纤维的溶解特性进行系统的研究,结合现有的检测标准,用化学溶解试验法测试,推荐性地提供8种聚乳酸纤维混纺产品的定量分析方法。经过验证,这8种方法与现有的国内外标准的再现性和重复性相当,结果可靠,因其使用的是实验室分析的常规试剂和常规试验方法,其分析安全、操作简易。     

家蚕蛹甲壳素的H_2O_2脱色及冷冻溶解研究

用4%H2O2溶液在pH11和温度75℃条件下对蚕蛹甲壳素进行漂白,能获得理想的白度(66.5)。以8%NaOH/10%Urea为混合溶剂,冷冻溶解脱色甲壳素。结果表明:脱色甲壳素白度越高溶解度越高;冷冻温度在-20℃及以下,溶剂中水分子才能结晶并破坏甲壳素结晶结构;而且溶剂体系为NaOH/Urea水溶液时最好,添加有机相(如乙醇、丙酮、DMSO)会使甲壳素溶解率下降甚至不溶。     

A facile dissolution strategy facilitated by H2SO4 to fabricate a 2D metal-free g-C3N4/rGO heterojunction for efficient photocatalytic H2 production

A 2D g-C₃N₄(pPCN)/rGO heterojunction for photocatalytic hydrogen production is fabricated by a facile dissolution strategy facilitated by H₂SO₄. The bulk g-C₃N₄ (CN) can be directly exfoliated into ultrathin protonated g-C₃N₄ (PCN) nanosheets under the assistance of H₂SO₄, and PCN can be further modified by rGO in a dissolved state under the electrostatic self-assembly process. The nanocomposite exhibits a large surface area (146.47 m²/g) and intimate contact interfaces between pPCN and rGO due to the specific synthesis method. Based on the DRS, PL and photoelectrochemical analyses, the introduction of rGO can greatly improve the light absorption and photogenerated charge carrier separation and transfer of g-C₃N₄. The optimal pPCN/2 wt% rGO nanocomposite shows an efficient photocatalytic H₂ evolution rate of 715 μmol g^?1 h^?1 under visible light irradiation, which is 2.6 and 13 times higher than those obtained on pPCN and CN. In addition, a photocatalytic mechanism over a 2D pPCN/rGO heterojunction is proposed. This work offers a new effective strategy for fascinating gC₃N₄based nanocomposites with promising hydrogen generation.     

用溶解-吸光法测定麻棉混纺纱的混纺比

介绍了一种测定麻棉混纺纱混纺比的方法 ,该方法将麻棉混纺纱经硫酸半溶解 ,然后测定其溶液的吸光值 ,求得混纺比。     

棉纤维与可溶性纤维混纺毛巾用纱的开发

为开发水溶性PVA纤维棉混纺毛巾用纱,根据水溶性PVA纤维长度整齐度好、回潮率低、遇高温易熔融的特点,设计了纺纱工艺流程.对两种原料分别制条,采用条混工艺,头道混并为1根PVA条与5根精梳棉条并合,合理配置了各工序工艺参数,车间温度控制在29℃以下,结果表明:精梳棉/水溶性PVA纤维80/2018 tex成纱质量良好,满足了客户要求.     

Dissolution tests as a tool for predicting bioaccessibility of nutrients during digestion

Bioaccessibility and bioavailability of active ingredients (like vitamins, antioxidants, etc.) into food systems is often compromised by factors like low permeability and/or solubility within the gut, lack of stability during food processing (temperature and oxygen) as well as in the gastrointestinal tract (pH, enzymes, presence of other nutrients). Moreover, little is known on the influence of food structure and breakdown in the gut on nutrient release. The possibility of predicting the release of nutrients from food matrices under simulated gastrointestinal conditions is of great relevance in order to define which food matrix is best for which nutrient, as well as for looking at the interaction of ingredients with the enzymes involved in the digestive process. This study explores the potential relevance of dissolution tests as a tool for predicting bioaccessibility of nutrients during in vitro digestion. Whey protein hydrogels containing green tea extract (GTE) were chosen for this study. Different simulated in vitro gastrointestinal conditions (GI) were applied throughout the dissolution experiments and the GTE was analysed by UV–vis absorption spectroscopy. It was possible to distinguish between two different release kinetics when experiments were performed in simulated gastric or intestinal media. In the gastric step, the kinetic of GTE release was lower than in an intestinal environment, suggesting that more GTE is released and available for absorption into the intestine than in the stomach. The present study shows that it is possible to use the dissolution tester as a screening method to mimic nutrient release from a food matrix in the gastrointestinal tract.     

Numerical investigation of light gas release,stratification and dissolution in TH22 test facility using 3-D CFD code GASFLOW-MPI

An accurate prediction of the hydrogen behaviors in the accident and management process is a crucial topic for both the hydrogen safety assessment and safety analysis in the confined enclosure like the containment of the nuclear power plant (NPP). Hence, the hydrogen behaviors including the transient light gas release, stratification and dissolution in the TH22 test facility for the NPP containment are analyzed and compared using the 3-D CFD code GASFLOW-MPI in this study. In this paper, the light gas helium is adopted as a substitute for the hydrogen in the calculations in accordance with the experiment. Firstly, the detached eddy simulation (DES) turbulence model, 3-D numerical model and experiment setup are introduced. Then, the hydrogen behaviors with the GASFLOW-MPI including the light gas release, stratification and dissolution are analyzed and validated with the experiment data. In addition, the velocity profiles, light gas concentrations, dimensionless numbers and temperature distributions are evaluated for the characteristics of the hydrogen behaviors. The results indicate that the calculation results agree well with the experiment data. Foremostly, the relative errors between the calculation results and experiment data during the phase of the dissolution of the light gas cloud are within 11.9%. Meanwhile, the relative errors of the time for the complete dissolution during the phase of the dissolution of the light gas cloud are within 5.0%. For the light gas release and stratification phase, the jet flow dominates as the Froude (Fr) number exceeds 10 during the time t = 600 s–800 s. Additionally, the time averaged centerline velocity and light gas concentration after the potential core region decay with a slop of 1/z which coincide with the theoretical jet limit. Lastly, the light gas concentrations and temperature distributions in all three phases are captured clearly with the GAFLOW-MPI. It demonstrates that the GASFLOW-MPI can accurately described the details of the related hydrogen behaviors in the accident and management process in the confined enclosure like the NPP. This paper can provide guidance for the numerical computation of the hydrogen safety issues in the confined space.