凝胶渗透色谱净化-气相色谱-质谱法测定肉品中的甲氧滴滴涕

建立肉品中甲氧滴滴涕残留的气相色谱-质谱(GC-MS)分析方法。采用均质提取方法提取样品中的甲氧滴滴涕,经凝胶渗透色谱净化,浓缩定容后用GC-MS检测分析,外标法定量。样品添加水平为0.005、0.01、0.02mg/kg时,甲氧滴滴涕的回收率在82.8%～103.2%之间,方法检测限为0.001mg/kg。本方法操作简便、准确、灵敏度高,净化效果好,满足残留分析要求。     

超高效液相色谱-质谱联用法快速测定豆酱中PC、LPC和GPC的含量

建立快速、简单、准确测定豆酱中活性成分磷脂酰胆碱(PC)与其降解产物溶血磷脂酰胆碱(LPC)和甘油磷脂酰胆碱(GPC)含量的超高效液相色谱-质谱联用(UPLC-MS)分析方法。将豆酱样品经过预处理后,以乙腈、醋酸铵为流动相,使用Waters ACQUITY UPLC超高效液相色谱仪,经ACQUITY UPLC BEH HILIC色谱柱(2.1×100mm,粒径1.7μm)分离,利用质谱定性定量测定其含量。质谱在电喷雾正离子模式下,对m/z782、m/z520和m/z258进行选择离子监测。该方法下PC、LPC和GPC分别在0.191～1.910μg/mL,0.236～2.360μg/mL和0.016～0.160μg/mL范围内峰面积和浓度呈良好的线性关系,相关系数R2PC=0.9959、R2LPC=0.9986和RG2PC=0.9991;PC、LPC和GPC的最低检测限分别为0.05、0.07、0.005μg/mL,最低定量限分别为0.19、0.24、0.016μg/mL;方法的平均回收率为93.2%～97.8%,相对标准偏差为1.5%～3.5%。此方法准确,灵敏度高,样品处理简单,分析时间短,可快速测定豆酱中PC与其降解产物LPC和GPC含量。     

Real-time comparison of a number of predictive controllers

Many model predictive control (MPC) algorithms have been proposed in the literature depending on the conditionality of the system matrix and the choice of its cost-function. This paper presents the newer MPC schemes such as extended predictive control (EPC) and shifted MPC as well as other well known forms. The control performance of these controllers are compared using two systems that are slow and fast reacting. The closed-loop responses are compared and the differences and similarities are explained on the basis of the structure of the control schemes. Disturbance rejection and the tracking of various setpoint trajectories are performed with good closed-loop results from all the controllers. It was found that the controllers that were specifically designed to reduce the system matrix ill-conditionality such as EPC and generalized predictive control provided better control performance when compared to other MPC methods.     

Simplified modeling and generalized predictive position control of an ultrasonic motor

Ultrasonic motors (USM's) possess heavy nonlinear and load dependent characteristics such as dead-zone and saturation reverse effects, which vary with driving conditions. In this paper, behavior of an ultrasonic motor is modeled using Hammerstein model structure and experimental measurements. Also, model predictive controllers are designed to obtain precise USM position control. Simulation results indicate improved performance of the motor for both set point tracking and disturbance rejection.     

液闪法研究~(14)C-尿素在小鼠体内的吸收及分布和排泄

本文报道应用液体闪烁测量方法研究14C-尿素在小鼠体内的吸收、分布和排泄。小鼠口服14C-尿素后,血药浓度时间曲线符合二房室开放模型。吸收速率常数Ka为3.64/h,分布相半衰期T1/2(α)为0.72h,消除相半衰期T1/2(β)为5.15h,清除速率常数CL为0.617L-1.Kg-1.h-1,表观分布容积Vd为5.59L/Kg,达峰时间Tmax为0.11h,峰浓度Cmax为1.57KBq/mL。在所测12种组织中均有14C-尿素存在,0.25h肾中放射性最高,心,肝,脾,肺,肠,胃较多,2h肺中放射性最高,脂肪最少。24h肝中放射性最高。24h粪尿排出给药量的65%,其中46%经尿排出,19%经粪排出。     

新型有机硅自洁耐沾污机理的研究

以有机硅树脂低聚物为主要成分制备的耐沾污剂，不仅具有优异的自洁耐沾污性能，而且固化迅速。用FTIR、GPC等分析仪器对有机硅低聚物的结构与性能进行了表征测试，并通过SEM、接触角测量仪等对影响有机硅防污剂的耐沾污因素及机理进行了研究。     

Dissolution of softwood kraft pulps by direct derivatization in lithium chloride/N,N‐dimethylacetamide

A method for the characterization of the molar mass distributions (MMDs) of softwood kraft pulps dissolved in 0.5% lithium chloride (LiCl)/N,N‐dimethylacetamide (DMAc) by size exclusion chromatography is presented. The method is based on derivatization with ethyl isocyanate and the dissolution of samples in 8% LiCl/DMAc. In this study, the derivatization of hardwood kraft pulps did not influence the MMD. In the case of softwood pulps, however, the derivatization decreased the proportion of the high‐molecular‐mass material and increased the proportion of the low‐molecular‐mass material, which resulted in a distribution similar to the MMD of a hardwood kraft pulp. The results suggest that associations between hemicellulose and cellulose in the softwood kraft pulp were ruptured during derivatization. This led to a more correct estimation of the MMD of derivatized softwood kraft pulps than obtained by the dissolution of nonderivatized samples. This new method offers several advantages over derivatization with phenyl isocyanate: a precipitation step is not necessary, it is possible to follow the lignin distribution in the samples, and the method allows very high levels of dissolution of softwood kraft pulps up to a κ number of around 50. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 424–431, 2004     

Reverse atom transfer radical polymerization of stearyl methacrylate using 2,2′‐azobisisobutyronitrile as the initiator

The living/controlled radical polymerization of stearyl methacrylate was carried out with a conventional radical initiator (2,2′‐azobisisobutyronitrile) in N,N‐dimethylformamide in the presence of a 2,2′‐bipyridine complex of hexakis(N,N‐dimethylformamide)iron(III) perchlorate. The polymerization mechanism was thought to proceed through a reverse atom transfer radical polymerization. The molecular weights of resulting poly(stearyl methacrylate) increased with conversion, and the resulting molecular weight distributions were quite narrow. The rates of polymerization exhibited first‐order kinetics with respect to the monomer. A probable reaction mechanism for the polymerization system is postulated to explain the observed results. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1236–1245, 2002     

4‐chloro‐3‐methylphenyl methacrylate copolymers with 2,4‐dichlorophenyl methacrylate: Synthesis,characterization, and antimicrobial activity

4‐Chloro‐3‐methylphenyl methacrylate (CMPM) and 2,4‐dichlorophenyl methacrylate (2,4‐DMA) were synthesized by reacting methacryloyl chloride with 4‐chloro‐3‐methylphenol (CMP) and 2,4‐dichlorophenol (2,4‐DP), respectively. Homo and copolymers of CMPM and 2,4‐DMA were obtained from different monomer feed ratios, using 2,2′‐azobisisobutyronitrile as initiator in toluene at 70°C. IR‐spectroscopy was employed to characterize the resulting homo and copolymers. Copolymer compositions were determined by ultraviolet (UV) spectroscopy. Fineman–Ross method was used to calculate the reactivity ratios of the monomers. Average molecular weight and polydispersity index were obtained by gel permeation chromatography (GPC). Thermogravimetric analyses (TGA) and differential thermal analysis (DTA) of copolymers were carried out under a nitrogen atmosphere. Antimicrobial effects of the homo and copolymers were also investigated for various microorganisms such as bacteria, fungi, and yeast. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:439–448, 2006     

基于神经网络预测误差修正的广义预测控制

针对建模误差对预测控制的影响,提出一种基于神经网络预测误差修正的广义预测控制算法.被控对象采用递推最小二乘法(RLS)辨识其线性模型;预测误差由前馈神经网络进行建模,并用Powell快速优化方法训练网络.该方法无需预先离线训练神经网络,即可投入闭环控制,并具有理想的稳定性、跟踪性能和鲁棒性.仿真结果表明该算法能够有效地控制复杂系统.