Correlation Between Enzyme Activity and Stability of a Protease, an Alpha-Amylase and a Lipase in a Simplified Liquid Laundry Detergent System, Determined by Differential Scanning Calorimetry

Enzymes used during washing in laundry detergents have become a universal tool to lower energy consumption and to generate a broad, consumer-relevant, cleaning effect. However, the stability of these enzymes remains a major obstacle, particularly in liquid products, due to increased interaction between the enzymes and the other components of the detergent. The process of formulation involves extensive shelf-life stability studies where residual enzyme activities are correlated with formulation variations. As a way to improve the formulation process, we evaluated the possible use of differential scanning calorimetry (DSC) as a tool to predict enzyme stability in liquid detergents. Thus, residual enzyme activity after incubation in a multitude of formulations was determined and compared to thermodynamic data obtained by DSC. The enzymes tested were a protease, an alpha-amylase and a lipase. We found a strong linear correlation between DSC-derived data, in particular T _max (temperature at peak maximum of the transition from the folded to unfolded state) and enzyme activity studies with R ²-values: 0.98 (protease), 0.99 (amylase) and 0.98 (lipase), respectively. Thus, a higher T _max for the same enzyme in a particular formulation is directly proportional to longer storage stability. These results suggest a new way of greatly accelerating this type of formulation study, allowing estimation of enzyme compatibility with a specific formulation on a daily, rather than the weekly or monthly basis used at present.     

Effect of Silica Nanoparticles on the Performance of Polysulfone Membranes for Olefin‐Paraffin Separation

The separations of ethylene/ethane and propylene/propane using polysulfone‐silica nanocomposite membranes were studied. Silica nanoparticles were prepared via sol‐gel method and the membranes by phase inversion. Characterization by Fourier transform spectroscopy and scanning electron microscopy indicated a good distribution of silica nanoparticles in the polymer matrix and also a good compatibility between the two phases. The performances of the prepared membranes in ethylene‐ethane and propylene‐propane separation were evaluated. The results showed the increments in gas permeability and selectivity by silica. Higher silica contents increased the solubility coefficient and reduced the diffusion coefficient of gases. The plasticization pressure of polysulfone was increased by incorporating the silica nanoparticles in polymer.     

碳化法纳米SiO2表面结构研究

采用红外、热重、N2吸附等分析方法,研究了碳化法制备的纳米SiO2表面羟基、孔隙结构和吸油值等随陈化pH值、陈化时间及干燥温度的变化关系.实验结果表明,在不同陈化pH值下SiO2凝聚反应速率不同,陈化pH值由2升高到5,凝聚反应加快,颗粒表面羟基含量由1.54个/nm2减少到1.44个/nm2,平均孔径由11.51 nm增大到23.06 nm,吸油值由1.70 cm3/g升高到1.81 cm3/g;在不同陈化时间下SiO2颗粒间凝聚反应进程不同,陈化时间由10 min延长到90 min,颗粒表面羟基含量由1.48个/nm2减少到1.40个/nm2,平均孔径、吸油值变化不明显;在不同干燥温度下颗粒表面羟基脱除程度不同,干燥温度由100℃升高到500℃,表面羟基脱除增多,羟基含量由1.43个/nm2减少到0.70个/nm2,平均孔径由13.2 nm增加到41.07 nm,吸油值由1.82 cm3/g升高到2.00 cm3/g.     

不同植物基绿色表面活性剂在浓缩洗涤剂和洗衣凝珠配方中应用探讨

洗涤剂浓缩化和绿色化是日化洗涤行业发展的趋势.本文重点探讨了几种植物基绿色表面活性剂对浓缩丝毛洗涤剂、浓缩+洗衣液和洗衣凝珠的低温浊点、泡沫性能、去污力等性能的影响.结果 发现,在本实验条件下,脂肪酸甲酯乙氧基化物(FMEE)、天然油脂改性乙氧基化物(SOE)、乙氧基化天然油脂改性磺酸钠物(SNS)的低温稳定性相比AE...     

Increased Metal Utilization in Carbon‐Supported Pt Catalysts by Adsorption of Preformed Pt Nanoparticles on Colloidal Silica

Pt/C electrocatalysts, aimed at maximizing the electrochemical surface area (ECSA) and consequently the specific mass activity of fuel cell reactions, are obtained by firstly depositing Pt nanoparticles on colloidal silica (Pt‐silica), followed by the adsorption of the latter onto a carbon support. This method of catalyst preparation increases Pt metal utilization and generates accessible void space in the interpenetrating particle network of carbon and silica for the facile transport of reactants and products. Both electrochemical hydrogen adsorption/desorption and CO oxidation measurements show an increase in the ECSA using this approach. Methanol electrooxidation is used as a test reaction to evaluate the catalytic activity. It is found that the silica modified catalyst is three times as active as a catalyst prepared without silica, under otherwise identical conditions.     

The Effect of Coatings on the Affinity of Lanthanide Nanoparticles to MKN45 and HeLa Cancer Cells and Improvement in Photodynamic Therapy Efficiency

An improvement in photodynamic therapy (PDT) efficiency against a human gastric cancer cell line (MKN45) with 5-aminolevulinic acid (ALA) and lanthanide nanoparticles (LNPs) is described. An endogenous photosensitizer, protoporphyrin IX, biosynthesized from ALA and selectively accumulated in cancer cells, is sensitizable by the visible lights emitted from up-conversion LNPs, which can be excited by a near-infrared light. Ten kinds of surface modifications were performed on LNPs, NaYF₄(Sc/Yb/Er) and NaYF₄(Yb/Tm), in an aim to distribute these irradiation light sources near cancer cells. Among these LNPs, only the amino-functionalized LNPs showed affinity to MKN45 and HeLa cancer cells. A PDT assay with MKN45 demonstrated that amino-modified NaYF₄(Sc/Yb/Er) gave rise to a dramatically enhanced PDT effect, reaching almost perfect lethality, whereas NaYF₄(Yb/Tm)-based systems caused little improvement in PDT efficiency. The improvement of PDT effect with the amino-modified NaYF₄(Sc/Yb/Er) is promising for a practical PDT against deep cancer cells that are reachable only by near-infrared lights.