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排序方式: 共有1769条查询结果,搜索用时 218 毫秒
61.
Chia-Hung Kuo Hsin-Hung Chen Jiann-Hwa Chen Yung-Chuan Liu Chwen-Jen Shieh 《International journal of molecular sciences》2012,13(9):11694-11704
Wax esters are long-chain esters that have been widely applied in premium lubricants, parting agents, antifoaming agents and cosmetics. In this study, the biocatalytic preparation of a specific wax ester, cetyl octanoate, is performed in n-hexane using two commercial immobilized lipases, i.e., Lipozyme® RMIM (Rhizomucor miehei) and Novozym® 435 (Candida antarctica). Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) are employed to evaluate the effects of reaction time (1–5 h), reaction temperature (45–65 °C), substrate molar ratio (1–3:1), and enzyme amount (10%–50%) on the yield of cetyl octanoate. Using RSM to optimize the reaction, the maximum yields reached 94% and 98% using Lipozyme® RMIM and Novozym® 435, respectively. The optimum conditions for synthesis of cetyl octanoate by both lipases are established and compared. Novozym® 435 proves to be a more efficient biocatalyst than Lipozyme® RMIM. 相似文献
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63.
Athira Mohanan Michael T. Nickerson Supratim Ghosh 《Journal of the American Oil Chemists' Society》2020,97(12):1319-1333
Use of oleogels prepared from hydrocolloids has recently gained considerable attention as an alternative for trans and saturated fats. Lately, pulse proteins such as faba bean protein and pea protein have been successfully used to prepare oleogels using a foam-templated approach. Although the pulse proteins are healthy oleogelators, high oil loss and low quality of cake baked using pulse protein-stabilized oleogels due to its poor rheological properties challenged its use. The present study explored whether the addition of small amount of high-melting monoglyceride (MAG) or candelilla wax (CW) can be used to improve the oil binding capacity, rheological properties, and baking qualities of pulse protein-stabilized oleogels composed of 5% faba bean or pea protein concentrate with 0.25% xanthan gum foams. Different concentrations (0.5–3%) of MAG or CW were dissolved in canola oil at 80 °C, followed by addition into the freeze-dried protein-polysaccharide foams (pH 7) and quickly transferred to a refrigerator to facilitate the formation of oleogels. The crystallized additives were found to be reinforcing the protein foam network in the oleogels. With increase in concentration of CW and MAG, the oil binding capacity, firmness, cohesiveness, and storage moduli of the oleogels were increased. Oleogels with and without MAG or CW were then characterized and tested for their performance as a shortening replacer in model baked cakes. Findings showed improved textural properties of cake upon addition of MAG in the foam-templated oleogels, however, compared to the shortening, negative effect on cake hardness and chewiness was still observed with the oleogels. 相似文献
64.
One of the most fascinating properties of materials in nature is the superhydrophobic and self‐cleaning capabilities of different plant surfaces. This is usually achieved by the hydrophobic cuticles that are made of cutin and contain wax crystals both within them and on their surfaces. Here, bioinspired n‐hexatriacontane wax films are deposited via thermal evaporation and it is shown that the surface evolves in time via self‐assembly. This leads to a dramatic change in the wetting properties with a transition from hydrophobic to superhydrophobic characteristics, which takes place within several days at room temperature. This phenomenon is investigated and strain‐induced recrystallization is proposed to be the mechanism for it. This work could become the basis for the inspiration and production of tuned, time‐dependant, temperature‐sensitive, variable‐wettability surfaces. 相似文献
65.
Two bacteria (B1 and B2) were isolated from soil-contaminated sites. The surface properties of biosurfactants produced by these bacteria were determined. These bacteria were given a good resistance to NaCl concentration up to 20%. The surface activity was detected with maximum value at pH7 with B1, whereas B2 was not affected by the change pH (3–12). The biosurfactants of these bacteria were added as a mixture or individual to crude oil given the good result in reducing the pour point. The infrared spectrum of wax or asphaltene fractions of Egyptian crude oil untreated and treated with biosurfactants was detected. 相似文献
66.
The influence of the concentration of paraffin wax on the penetration rate, P, and the average diffusion coefficient, D, of kerosene in an SBR–NR composite and also on the coefficient of viscosity were investigated. All decreased with the addition of wax. Also, the effect of the concentration of paraffin wax on both the current–voltage characteristics and the temperature dependence of the dc electrical conductivity were studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3169–3177, 2001 相似文献
67.
溶剂型木器涂料中蜡助剂的选择 总被引:3,自引:0,他引:3
通过对蜡的来源,蜡助剂加工方法的介绍,探讨了蜡的物性特点和作用机理,阐明了蜡助剂在溶剂型木器涂料中的作用及其选择原理. 相似文献
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69.
Transient Electronics: Thermally Triggered Degradation of Transient Electronic Devices (Adv. Mater. 25/2015) 下载免费PDF全文
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