高效液相色谱/质谱联用测定保健食品中的伐地那非

为测定保健食品中伐地那非，建立了高效液相色谱质谱联用（HPLC—ES／MS）的测定方法。该方法以紫外定量，质谱定性。色谱条件为RP—C18色谱柱，流动相：0．2％甲酸水溶液＋乙腈=65＋35（体积分数）；流速1ml／min；进样量5μl；检测波长254nm。质谱采用电喷雾正离子模式（ESI＋），扫描范围为：200-700（m/z）。伐地那非在3．6—450μg/ml范围内，浓度与峰面积呈良好的线性关系，定量检出限为18ng，最低检出限为0．9ng（S/N=6）。本方法流动相简单，分析时间短且试样预处理简单，灵敏度高，借助质谱的定性能力，可大大提高方法可靠性和抗干扰能力，能准确快速地测定保健食品中的伐地那非。     

交联甘薯淀粉十二烯基琥珀酸酯制备条件研究

采用环氧氯丙烷为交联剂,十二烯基琥珀酸酐为酯化剂,对甘薯淀粉进行双重化学变性,以峰值粘度和取代度作为评价指标,通过正交试验和响应面分析,得出制备高粘度,适宜取代度的交联甘薯淀粉琥珀酸酯最优制备条件:即交联剂用量为0.28％,交联反应pH值为10.2,交联反应时间为3h,酯化剂用量为7％,酯化反应pH值为9.1,反应温度为24℃。     

部分糊化淀粉浆液黏度与浆液性能相关性分析

探讨部分糊化淀粉浆液黏度对浆液性能影响的规律。以玉米淀粉为原料,采用蒸汽升温方式分别在62℃~67℃制备了6种不同黏度的部分糊化淀粉浆液,对浆液的黏度、糊化度、结晶度、粒径和膨胀势进行测试,并应用SPSS统计软件的相关分析与线性回归分析功能对测试结果进行了相关性分析。结果表明:部分糊化淀粉浆液的黏度与结晶度呈负相关,结晶度随黏度的增大而降低;黏度与平均粒径、膨胀势呈极显著正相关,平均粒径和膨胀势值均随黏度的增加而明显增大;黏度与平均粒径、膨胀势呈明显的线性关系。认为通过相关性分析可以建立起部分糊化淀粉浆液的评价分析方法,运用此方法,可以直观、有效地对部分糊化淀粉浆液黏度性质进行评价分析。     

高效液相色谱-串联质谱法测定水产品中的喹乙醇

为测定水产品中喹乙醇的残留量,建立了高效液相色谱-串联质谱联用(HPLC-MS/MS)的测定方法。均质后的试样经水提取、液-液分配净化后,采用ZORBAXSB-C18色谱柱,并以0·1%乙酸 乙腈(70 30,体积分数)为流动相,色谱分离后直接进入串联质谱检测器。采用电喷雾正离子,多反应监测(MRM)模式检测,外标法定量。方法的检出限为10μg/kg,浓度在0·5~500μg/L范围内,线性良好(r=0·9989),添加浓度在10~500μg/kg时,不同水产品基质的回收率在74·3%~93·5%之间,相对标准偏差(RSD)小于5·6%。本方法检出限低,回收率高,定性可靠,定量准确,适合于水产品中喹乙醇残留的检测。     

基于COSMOSworks的钢板焊接件的工程分析

机械零件的工程分析是产品设计的一个重要组成部分,随着计算机辅助技术的发展,运用计算机对机械零件进行相关的工程问题分析已成为一个重要的发展方向.SolidWorks 作为三维CAD软件的代表,也提供了相应的CAE功能,本文就该问题进行专门的探讨.     

Oat lipids

Oats are a significant world crop. While nutritional interest in food oats has concentrated on oats as a source of dietary fiber, the lipid component has both nutritional and technological potential. Thus, the lipid fraction of the oat grain determines in large measure its energy content and has a significant impact on nutritional quality. The oat lipids mediate the pasting properties of oat starch and hence influence functionality. Lipids are also implicated in the flavor/off-flavor attributes of oats. These aspects of oat lipids are reviewed together with analytical methods for assessing the lipid content of oats.     

低温乙烯贮存装置C02/C03压缩机振动原因及对策

对低温乙烯贮存装置闪蒸气压缩机振动原因进行了分析。并据此提出了减小振动的措施,从而使压缩机得以稳定运行,且延长了运行周期。     

Nondestructive determination of fatty acid composition of husked sunflower (Helianthus annua L.) seeds by near-infrared spectroscopy

Determination of the fatty acid composition of sunflower (Helianthus annua L.) seeds by near-infrared (NIR) spectroscopy was examined. Sunflower seeds were husked (removed from their hulls by a husking machine or manually with a knife). NIR spectra of these seeds were scanned from 1100 to 2500 nm at 2-nm intervals in a whole-grain cell with a wideangle moving drawer for machine-husked seeds or in a single-grain cup for a manually husked single-grain seed. The extracted oils from machine-husked seeds also were scanned by sandwiching them between a pair of slide glasses to create a thin layer and by placing them on a syrup cup. For extracted oil, the absorption band around 1720 nm filled out to the shorter wavelength region in the NIR second-derivative spectra as the percentage of the linoleic acid moiety increased, because linoleic acid absorbs in this region. On the other hand, for husked seeds and for a single-grain seed, as the percentage of linoleic acid increased, the trough at 1724 nm where oleic and saturated acids absorb decreased in the second-derivative NIR spectra. Determination of the fatty acid composition of sunflower seeds could be carried out successfully according to the NIR spectral pattern for both extracted oil (r=−0.989) and kernel seed (r=−0.993). This is important, especially for a manually husked single-grain seed (r=−0.971), because it can still be germinated after such nondestructive analysis.     

镶装式密封环热应力的有限元分析

通过圆柱面过盈联接公式计算镶装式密封环过盈量,采用有限元分析方法建立了二维轴对称模型,并施加了合理的边界条件,得出了镶装式密封环最小过盈量和最大过盈量的应力场和温度场分布。     

试井资料确定平面压力分布场方法研究

本文以数值试井技术为依托进行试井资料确定平面压力分布场方法研究,形成了一种以数值试井为主、集动静态分析和油藏工程方法于一体的综合分析方法,解决了中低渗砂岩油藏开发中注采对应关系、水驱开发状况确定等难题。在介绍数值试井基本特点的基础上,阐述了数值试井的技术原理和参数敏感性分析,并介绍了该技术在中原油田的应用实例和效果。