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排序方式: 共有1375条查询结果,搜索用时 15 毫秒
71.
Deny Hartono Xinyan Bi Kun‐Lin Yang Lin‐Yue Lanry Yung 《Advanced functional materials》2008,18(19):2938-2945
A new air‐supported liquid crystal (LC) system for analyzing interfacial phenomena that occur based on the molecular interaction between LCs and adsorbed molecules of interest at the aqueous/LC interface is reported. Compared with existing LC‐based detection systems, the miniature system reported here requires less sample and involves simpler preparation. Using this system, the enzymatic hydrolysis of various phospholipases such as phospholipase A2 (PLA2), phospholipase C (PLC) and phospholipase D (PLD) are characterized. The hydrolysis of phospholipid monolayers self‐assembled at aqueous/LC interface induces an orientational response from the LCs. As a result, an optical signal that reflects the spatial and temporal distribution of phospholipids during the enzymatic reaction can be generated in a real‐time manner. When well‐known phospholipase inhibitors are introduced together with respective phospholipases, no orientational response of LCs is observed. In the case of inhibitors MJ33 and compound 48/80, cross‐inhibitions among phospholipases are also observed. This work demonstrates that the air‐supported LC system provides a facile label‐free assay for characterizing phospholipase activities and for screening enzyme inhibitors. It could potentially be useful for different high throughput and cost‐effective enzyme screening assays. 相似文献
72.
Zakir Hossain Kenji Fukunaga Masatoshi Tanouchi Koretaro Takahashi 《European Journal of Lipid Science and Technology》2009,111(9):877-883
An animal experiment was conducted to assess the antitumor effects of chitosan‐coated liposomes on myeloma SP2. The animal experimental groups designed for myeloma SP2 tumor‐bearing BALB/c mice were provided with five different drinks: (I) control (double‐distilled water); (II) squid phospholipid liposomes alone 1.0 mg/mL; (III) chitosan alone 5.0 mg/mL; (IV) squid phospholipid liposomes 1.0 mg/mL with chitosan 5.0 mg/mL in the form of a simple mixture; and (V) squid phospholipid liposomes 1.0 mg/mL coated with chitosan 5.0 mg/mL. At 20 days after implantation of the myeloma SP2 cells into mice, oral administration of the experimental drinks was provided for 35 days. There was significant suppression of tumor growth when chitosan and squid phospholipids were administered simultaneously in a simple mixture or as chitosan‐coated liposomes. Matrix metalloproteinase (MMP)‐2 and MMP‐9 activity was significantly less in the serum of mice that consumed chitosan‐coated liposomes than in control mice. We found that decreased tumor burden was related to MMP secretion. Therefore, chitosan‐coated marine phospholipid liposomes might be useful as potential agents for the treatment of myeloma SP2. 相似文献
73.
Fractionation of soybean phospholipids by high-performance liquid chromatography with an evaporative light-scattering detector 总被引:4,自引:0,他引:4
Tong Wang Earl G. Hammond James L. Cornette Walter R. Fehr 《Journal of the American Oil Chemists' Society》1999,76(11):1313-1321
Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) from 23 soybean lines with a wide range of fatty acid compositions
were resolved into seven fractions by high-performance liquid chromatography (HPLC). Fraction identities were assigned from
fatty acid compositions determined by gas chromatography (GC). A mass detector, i.e., an evaporative light-scattering detector,
was used for HPLC quantification. The detector response was a power function of PC and PE concentrations. Various correction
methods were applied to the detector response to obtain the best agreement between phospholipid (PL) fatty acid compositions
determined by GC and that calculated from the corrected HPLC fraction percentages. The corrected HPLC fraction composition
also was compared with that calculated from stereospecific distribution data using a 1-random-2-random hypothesis. Correlation
between PL-fatty acid and HPLC-fraction percentages showed that genetic modification of soybean oil composition caused changes
in PL species, which alter physical properties and may alter the physiological functions of PL in biomembranes. 相似文献
74.
Brice Calvignac Elisabeth Rodier Jean-Jacques Letourneau Pauline Vitoux Jacques Fages 《The Journal of Supercritical Fluids》2010,55(1):96-106
This study presents the development of an improved technique for viscosity measurements under high pressure. The apparatus is based on the principle of the falling ball viscometer, implemented in a high-pressure autoclave fitted with visualisation windows. The originality here is that the balls fall through a tube open at both ends with a diameter slightly greater than that of the balls, allowing a simplified modelling and numerical simulation. A numerical approach has been used for viscosity determination. Calculations have been made with COMSOL Multiphysics® with the laminar Navier-Stokes model for Newtonian mixtures. It includes the specific hydrodynamic effects without the need for a calibration fluid. However, validation experiments were carried out at atmospheric pressure with dimethylsulfoxide (DMSO) at 298, 308 and 318 K and with cocoa butter at 313 and 353 K, with values of viscosity in the range from 1.4 to 45.4 mPa s. Comparative measurements with literature data have been conducted with cocoa butter saturated with carbon dioxide at 313 and 353 K and for pressures ranging from 0.1 to 25 MPa. At 313 K, viscosity varies from 45.4 mPa s to 3.1 mPa s while at 353 K it varies from 12.4 to 1.9 mPa s. For both isotherms tested, within the range 0-15 MPa, the higher the CO2 dissolution in the cocoa butter, the lower the viscosity. However, this decrease in viscosity is more pronounced at the lowest temperature. Above 15 MPa the CO2 dissolution effect on viscosity becomes insignificant, i.e. within the experimental error, due to a counter effect linked with the high hydrostatic pressure. Furthermore, the limits of use of this method have been determined. This technique is revealed as reliable and can therefore be used with other binary systems. 相似文献
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78.
以酿酒酵母菌和植物乳杆菌作为发酵剂,探讨白砂糖和黄油对面包感官品质、比容和体积、质构、挥发性风味物质的影响。结果表明:白砂糖和黄油可显著改善面包的外观、色泽、组织结构、弹性、气味和口感等;可使面包的体积提高13.80%,硬度降低35.35%,弹性降低37.91%。在挥发性风味物质主成分方面,电子鼻检测结果表明,白砂糖和黄油使面包样品形成的风味主成分区域几乎无重叠,显著改变面包样品中挥发性物质主成分,对面包中氮氧化物、硫化合物、芳香族化合物、芳烃化合物、甲烷类和乙醇等化合物的产生影响显著。在挥发性风味物质含量方面,气相离子迁移色谱检测结果表明,白砂糖和黄油显著影响面包样品挥发性风味物质的种类和含量。其中,乙酸甲酯、乙酸异戊酯、己酸乙酯、糠醛等物质的含量明显增加。这些酯类物质既是挥发性风味物质,又是发酵香气成分中的主要呈香物质。综上可知,白砂糖和黄油在改善面包的食味品质方面发挥着重要作用。 相似文献
79.
柱前衍生-固相萃取-高效液相色谱法测定黄油中七种生物胺 总被引:1,自引:0,他引:1
研究柱前衍生-固相萃取-反相高效液相色谱法测定黄油中7种生物胺(色胺、酪胺、组胺、腐胺、尸胺、精脒、精胺)残留的方法。黄油样品经甲醇提取去除蛋白和脂肪,提取液经柱前衍生,衍生后通过ODS-C18固相萃取柱净化、富集,InertsilODS-3色谱柱分离,荧光检测器检测,外标法定量,流动相为乙腈和水梯度洗脱20min,流速为1mL/min。对添加3个不同含量水平的7种生物胺,5次平行实验的变异系数(CV)为3.52% ̄6.75%,检测低限为2.71×10-5 ̄1.36×10-3μg/mL,平均回收率为80.4% ̄89.1%。 相似文献
80.
Smoke-dried beef was pre-processed with water or by pressure cooking, weight losses were 50 and 54% respectively, with the rate of drying faster in the latter. There was a greater loss of total lipid and triglycerides in pressure cooked samples but the reverse was true for the phospholipids. The proportions of saturated and monoenoic fatty acids were slightly higher in the water cooked products although total unsaturation was slightly lower, the values being 37 and 39%, respectively. The fatty acid composition of the phospholipids was similar for both treatments except that the levels of polyenoic fatty acids were 16.4 and 14.43%, respectively in water and pressure cooked samples. Of the polyenes C20:4 accounted for about 75% of the fatty acids in the water cooked samples, compared with 40% with pressure cooking. After 60 weeks of storage at room temperature, pressure cooked samples were found to be more stable oxidatively: malonaldehyde was the principal oxidative by-product in both treatments. 相似文献