Efficient Synthesis of Octacosanol Linoleate Catalyzed by Ionic Liquid and Its Structure Characterization

Octacosanol, as the major active policosanol, has attracted much attention due to the potential beneficial effects for human health. However, free octacosanol has a high melting point, poor oil solubility and low bioavailability, which greatly restricts its practical application. In this study, we report a highly efficient method for an ionic liquids (IL)‐catalyzed synthesis of octacosanol ester by direct esterification with linoleic acid. The synthesized product was purified, subsequently characterized by FT‐IR, MS and NMR and finally confirmed to be octacosanol linoleate. The reaction parameters were investigated and the conversion reached 91.3 ± 4.8 % under the optimum conditions: IL 1‐butylsulfonate‐3‐methylimidazolium hydrogen sulfate ([BSO₃HMim][HSO₄]) as catalyst, IL dose 1.5 % (related to the mass of both reactants), 1:1 molar ratio of octacosanol to linoleic acid, 80 °C, and 1 h. The melting point and oil solubility of octacosanol were greatly improved by esterification with linoleic acid, facilitating the incorporation into a variety of oil‐based systems.     

藜麦红曲固态发酵及其抗氧化活性研究

目的 利用固态发酵的方法提高藜麦的功能性,并探究发酵产物的抗氧化活性。方法 选取5株红曲菌进行藜麦固态发酵,筛选出最优菌株,以红曲色素为指标进行单因素实验,并进行响应面优化实验。提取发酵产物中的色素,并采用紫外可见全波长扫描分光光度法及高效液相色谱法进行测定;采用Folin-Ciocaltue法和苯酚硫酸法对发酵产物中的多酚和多糖进行测定;并对发酵产物进行抗氧化活性研究。结果 5株红曲菌株中用C100发酵藜麦产色素能力最强。通过单因素和响应面优化,确定了发酵的最佳条件:装麦量26g,接种量5 mL,发酵时间9 d。藜麦经红曲发酵后多酚多糖变化明显,多酚是发酵前的4.93倍,多糖是发酵前的1.36倍。抗氧化研究表明:藜麦红曲发酵产物有一定的超氧阴离子清除能力,较强的清除铁离子还原能力、2,2-联氮-双-3-乙基苯并噻唑啉-6-磺酸二铵盐以及羟基自由基能力。结论 红曲固态发酵提高了藜麦产品功能性和可食用价值,具有广阔的市场前景。     

Development of a scintillation detector for real-time measurement of space proton effective dose

In this study, a scintillation detector was developed to measure the space proton effective dose for astronauts based on the proton effective dose conversion coefficients provided by International Commission on Radiological Protection Report No. 116. In the Monte Carlo N-Particle Transport Code X(version 2.6.0) simulation process, by modulating the depth and solid angle of truncated conical holes in an iron shell from lower-energy protons to higher-energy protons, the energy deposited in the scintillator by isotropic protons was nearly proportional to the corresponding effective dose, with a maximum relative deviation of 13.28% at thirteen energy points in the energy range of 10–400 MeV. Therefore, the detector can monitor proton effective dose indirectly in real time by measuring the deposited energy. We calibrated the photoelectric conversion efficiency of the detector at the cobalt source, tested the response of the detector in the energy range of 30–100 MeV in unidirectional proton field, and validated the simulation with the experimental results.     

The improving effect of spray-drying encapsulation process on the bitter taste and stability of whey protein hydrolysate

Although whey protein hydrolysate (WPH) possesses good physiological functionality, its bitter taste and hygroscopic property limit its direct utilization as food ingredient. The aim of this work was to encapsulate whey protein hydrolysate by spray drying using maltodextrin or maltodextrin/??-cyclodextrin mixture as wall materials to attenuate the bitter taste and enhance the stability of whey protein hydrolysate. Hygroscopicity, glass transition temperature, bitter taste, and morphology of non-encapsulated WPH and encapsulated WPH were evaluated. Solubility, particle size, bulk density, and moisture content were also measured. Compared with the non-encapsulated WPH, the encapsulated WPH exhibited significantly lower hygroscopicity and higher glass transition temperature. The bitterness of both maltodextrin-encapsulated WPH and maltodextrin/??-cyclodextrin-encapsulated WPH was significantly lower than that of the original non-encapsulated WPH. Morphological analysis by scanning electron microscopy showed that the microcapsules of the spray-dried encapsulated WPH were matrix-type with less link bridge and had a continuous wall with many concavities. In addition, encapsulation process did not exert negative effect on the solubility of whey protein hydrolysate. The results indicated that encapsulation with maltodextrin and ??-cyclodextrin as carriers was helpful to attenuate the bitter taste and enhance the stability of whey protein hydrolysate.     

多壁碳纳米管分散固相萃取-液质联用技术测定 茶叶中草甘膦、草铵膦、氨甲基膦酸残留量

摘 要：目的 建立茶叶中草甘膦、草铵膦和氨甲基膦酸残留量的超高效液相色谱串联质谱分析方法。方法 样品经水提取后采用分散固相萃取技术,以多壁碳纳米管（MWCNTS）和N-丙基乙二胺键合固相吸附剂（PSA）吸附提取液中的杂质,上清液用9-芴基氯甲酸酯（FMOC-Cl）衍生。衍生物用BEH C18进行分离,以乙腈-4 mmol乙酸铵水溶液为流动相,电喷雾正离子模式电离（ESI ）,多反应监测模式检测（MRM）,外标法定量。结果 方法的线性范围是0.1?1 μg/mL,相关系数大于0.999,定量限为10 μg/kg,以绿茶为基质,三种物质添加水平分别为0.25、0.50、1.00 mg/kg,回收率范围分别为草甘膦95%~116%,草铵膦98%~118%,氨甲基膦酸74%~84%,精密度均小于6.79%（n=6）。结论 该方法具有简便快速、灵敏度高、准确性强等特点,适合于测定茶叶中草甘膦、草铵膦和氨甲基膦酸的含量。     

抗食源性病原菌细菌素的筛选及特性研究

目的 筛选一种抗食源性病原菌的细菌素,并对其稳定性进行研究.方法 以食源性病原菌Bacillus cereus ATCC 14579、Listeria monocytogenes LM201、Listeria monocytogenes LM605为指示菌,采用琼脂扩散法筛选细菌素产生菌,通过离子交换树脂法和高效液相色...     

基于PXI总线的工程车辆液压自动检测系统设计

介绍了一种工程装备液压系统性能自动检测系统.该系统以PXI总线系统构成硬平台,可更换适配器构成液压系统测试传感器与测试资源的物理连接与各种信号的调理,以LabWindows/CVI构成软平台,实现了从仪器自检-系统标定-自动检测-数据处理分析-打印测试报告等的自动化处理.实践表明,该系统拥有优良的可扩展性和工程实用性,在液压系统检测和故障诊断领域具有广阔的应用前景.     

超临界水冷混合堆快谱区组件物理——热工分析

提出了超临界水冷混合堆快谱区多层燃料组件设计方案.应用MCNP程序为该组件建立计算模型,并进行了相应的物理计算;同时运用子通道分析程序STAFAS对多层燃料组件子通道进行了初步的稳态热工分析.计算结果表明:超临界水冷混合堆快谱区多层燃料组件燃料转换比超过1.0,并且获得负的冷却剂空泡反应性系数;燃料包壳表面最高温度约为595℃,低于设计准则规定的上限值,同时组件各子通道出口冷却剂温度均匀性较好.通过对燃料棒径敏感性分析可知,较大棒径组件燃料转换比较大,但也会导致热通道包壳表面温度峰值升高.     

视觉跟踪模糊自调节PI控制算法

视觉跟踪系统是一个非线性时变系统,传统控制方法往往难以胜任。因此,本文提出一种新的视觉跟踪控制算法——模糊自调节PI控制算法,以跟踪三维平动刚体目标。与传统基于图像的视觉伺服控制算法相比,该控制算法有两个优点：①以二值目标图像的矩特征为图像特征,因而无需图像特征匹配;②模糊调节器根据闲环系统响应的不同阶段,在线调节PI参数,从而改善了闭环系统的整体性能。仿真结果表明,本文提出的模糊自调节PI控制算法不仅简单快速,且具有较高控制精度。