Optimization of localized 19F magnetic resonance spectroscopy for the detection of fluorinated drugs in the human liver.

Fluorine MR spectroscopy ((19)F MRS) is an indispensable tool for assessing the pharmacokinetics of fluorinated drugs. Since the metabolism of 5-fluorouracil (5FU), a frequently used cytotoxic drug, is expected to be different in normal liver and in tumor tissue, spatial localization is required for detection by MRS. In this study, three independent signal-to-noise ratio (SNR) optimizations were combined to enable chemical shift imaging (CSI) as a localization method in the detection of 5FU and its metabolites in tumor tissue. First, the hardware was optimized by using circularly polarized coils together with integrated preamplifiers. Second, the optimal pulse angle (Ernst angle) was determined on the basis of T(1) relaxation time measurements of 5FU. Finally, averaging of CSI phase-encoding steps was optimized by using the applied Hamming filter as a weighting function. The combination of these three methods enables the in vivo detection of 5FU and alpha-fluoro-beta-alanine (FBAL) by (19)F MRS, localized in three dimensions in tumor and liver tissue at a time resolution of 4 min at 1.5 Tesla.     

On the synthesis of time‐varying LQG weights and noises along optimal control and state trajectories

A general approach to control non‐linear uncertain systems is to apply a pre‐computed nominal optimal control, and use a pre‐computed LQG compensator to generate control corrections from the on‐line measured data. If the non‐linear model, on which the optimal control and LQG compensator design is based, is of sufficient quality, and when the LQG compensator is designed appropriately, the closed‐loop control system is approximately optimal. This paper contributes to the selection and computation of the time‐varying LQG weighting and noise matrices, which determine the LQG compensator design. It is argued that the noise matrices may be taken time‐invariant and diagonal. Three very important considerations concerning the selection of the time‐varying LQG weighting matrices are turned into a concrete computational scheme. Thereby, the selection of the time‐varying LQG weighting matrices is reduced to selecting three scalar design parameters, each one weighting one consideration. Although the three considerations seem straightforward they may oppose one another. Furthermore, they usually result in time‐varying weighting matrices that are indefinite, rather than positive (semi) definite as required for the LQG design. The computational scheme presented in this paper addresses and resolves both problems. By two numerical examples the benefits of our optimal closed‐loop control system design are demonstrated and evaluated using Monte Carlo simulation. Copyright © 2005 John Wiley & Sons, Ltd.     

膜生化反应器处理垃圾焚烧厂渗沥液的试验研究

采用成套膜生化反应器(MBR)小试设备对垃圾焚烧厂的渗沥液处理进行了可行性试验研究,并选取了COD、NH3-N的去除率作为主要考察指标.试验表明:膜生化反应器(MBR)工艺技术可行,COD、NH3-N的去除率分别可达99%和98%以上,其出水指标分别达到GB 16889-1997生活垃圾填埋污染控制标准中的三级和二级标准.     

Design and conduct of occupational epidemiology studies: I. Design aspects of cohort studies

Cohort and case-control studies are two standard approaches for investigating the etiology of occupational diseases. This paper, which is the first of a four-part series, contains a review of the design features of occupational cohort studies. Topics discussed include the basic features of prospective and historical cohort studies, options for defining the cohort, disease incidence ascertainment, and considerations involved in planning an occupational cohort study. Subsequent papers in this series will focus on data analysis of occupational cohort studies and the design and analysis of occupational case-control studies.     

外语多媒体软件界面设计的认知策略模式

外语学习软件界面的设计除了应注意实现软件功能的技术因素、表现媒体的物理性状以及信息内容的学科把握 ,还应对软件界面的内容组织方略、交互通达方式、语用认知功能等方面提出要求。界面设计的出发点 ,应该是学生、学习任务及其相应的学习活动。应该根据需求分析、学习者分析、任务和内容分析来确定目标和步骤。外语教学应以语言能力、交际能力、学习策略能力为目标 ,界面设计应以此为据选择表现媒体、结构层次、交互方式和技术手段。     

The logical structure and validity of experimental designs in pharmacokinetics and clinical pharmacology

Much of the literature on research design in clinical pharmacology and pharmacokinetics emphasizes statistical concerns, thus suggesting that a primary ingredient of a valid research design is an appropriate plan for statistical analysis of data. However, statistical validity is only one of several ways to evaluate an experimental study. The present paper reviews the underlying logic and sources of invalidity of experimental drug research suggesting influences and factors which may deceive or lure an experimenter into erroneous conclusions.     

Polynomial matrix solution of H2 optimal control problem for state‐space systems

A polynomial matrix solution to the H₂ output feedback optimal control problems is obtained for systems represented in state‐equation form. The proof does not invoke the separation principle but is obtained in the z‐domain. The cost function includes weighted states, which allows the so‐called standard system model problem to be solved. This encompasses the class of inferential control problems. The results also enable the two‐degree‐of‐freedom optimal control solution properties to be explored. Copyright © 2002 John Wiley & Sons, Ltd.     

小鼠持续性脑缺血后NMDA受体亚单位表达的变化

目的：研究小鼠持续性脑缺血后不同脑区NMDA受体亚单位表达的变化及其与病理损伤之间的联系。方法：采用大脑中动脉阻断法制作小鼠持续性脑缺血模型，取缺血后不同时间的皮层、海马、皮层下脑组织，用免疫印迹技术测定NMDA受体亚单位ζ1和ε1及ε2蛋白的含量。同时作冰冻切片和苏木素伊红染色，计算相应脑区神经元密度。结果：NMDA受体ζ1和ε1及ε2亚单位表达的改变发生于缺血后5h内，皮层下3个亚单位表达均明显增加，海马则各亚单位表达变化不一。脑梗塞灶和相关脑区神经元密度显著减小均出现于缺血后5h，相关脑区神经元死亡严重程度依次为皮层下组织和海马CA1区及大脑颞叶皮层Ⅲ－Ⅳ层。结论：小鼠持续性脑缺血，缺血侧脑组织NMDA受体亚单位ζ1和ε1及ε2表达的变化发生在明显的病理损害之前，表达变化程度因脑区不同，与相关脑区神经元损害的程度相应。     

Heparin effect on ionised calcium concentration

The effect of heparin on plasma ionised calcium was studied by adding it in increasing amounts to whole blood from 10 normal subjects. There was no significant change in ionised calcium from the addition of 1 U/ml but a significant fall of 0.02 mmol/1 when 2 U/ml were added and a progressive further fall with increasing concentrations. Heparin from three different manufacturers produced similar results. The effect of heparinisation in vivo was studied during regular haemodialysis on 10 patients with chronic renal failure. Following intravenous injection of 10000 U of heparin there was a consistent and significant fall averaging 0.03 mmol/l.     

维胺酯-β-环糊精包合物的研究

应用３因素８水平的均匀设计方法，优化出维胺酯－β－环糊精包合物最佳制备条件，所得包合物的包合率为９９．３％，其表观稳定常数为１３９４Ｍ－１．