A novel molecular distance edge vector as applied to chemical modeling of quantitative structureretention relationships： Various gas chromatographic retention behaviors of polychlorinated dibenzofurans on different polarityvarying stationary phases

Based on the identical group as a pseudo atom instead of a typical atom, a novel modified molecular distance-edge （MDE） vector μ was developed in our laboratory to characterize chemical structure of polychlorinated dibenzofurans （PCDFs） congeners and/or isomers. Quantitative structure-retention relationships （QSRRs） between the new VMDE parameters and gas chromatographic （GC） retention behavior of PCDFs were then generated by multiple linear regression （MLR） method for non-polar, moderately polar, and polar stationary phases. Four excellent models with high correlation coefficients, R=0.984--0.995, were proposed for non-polar columns （DB-5, SE-54, OV-101）. For the moderately polar columns （OV-1701）, the correlation coefficient of the developed good model is only 0.958. For the polar columns （SP-2300）, the QSRR model is poor with R=0.884. Then cross validation with leave-one out of procedure （CV） is performed in high correlation with the non-polar （Rcv=9920.974） and weakly polar （Rcv=921） columns and in little correlation （Rcv=0.834） with the polar columns. These results show that the new μ vector is suitable for describing the retention behaviors of PCDFs on non-polar and moderately polar stationary phases and not for the various gas chromatographic retention behaviors of PCDFs on the different polarity-varying stationary phases.     

Association of cystatin C level and cardiovascular prognosis for patients with preexisting coronary heart disease： a meta-analysis

The association of circulating levels of cystatin C （CysC） and risk of recurrent cardiovascular events in patients with preexisting coronary heart disease are uncertain. To qualitatively and quantitatively address this issue, we performed a random meta-analysis of results from prospective studies on the topic. We searched elec- tronic and printed sources （up to 16 October 2011） using keywords and retrieved articles for seven prospective studies according to the selection criteria. Data were abstracted and meta-analysis was performed using the random-effects model （RevMan 5.0.23 software）. The cohorts involved 4,576 patients with preexisting coronary heart disease （CHD） and normal or mild chronic kidney disease, and follow-up ranged from 5.6 to 40.6 months. Highest versus lowest baseline CysC level was signifi- cantly associated with increased risk of cardiovascular events （OR 2.30, 95 % CI 1.80-2.94）, all-cause mortality （OR 5.69, 95 % CI 3.70-8.74）, but not with recurrent MI （OR 1.75, 95 % CI 0.77-4.00）. In heterogeneity testing for studies reporting cardiovascular events and all-cause mor- tality, no significant heterogeneity was found, and exclu- sion of any single study did not alter the overall finding. For risk of recurrent MI, significant heterogeneity was found among the five trials （Z2= 13.16, P=0.01, 12 = 70 %） and exclusion of the Taglieri et al. [12] study from the analysis resulted in a rise in relative risk （OR 2.36, 95 % CI 1.09-5.15）. In conclusion, for patients with established CHD, high baseline level of CysC is associated with increased risk of cardiovascular events and all-cause death during long-term follow-up.     

Complex networks theory for analyzing metabolic networks

The completion of the Human Genome Project started the post-genomic era. The hot topic of biologi- cal research is now shifting from the study of single genes or proteins to whole genome analyses. All kinds of “omics” technologies such as genomics, tran…     

Progress in the applications of flux analysis of metabolic networks

The metabolic network has become a hot topic in the area of system biology and flux-based analysis plays a very important role in understanding the characteristics of organism metabolic networks. We review mainly the static methods for analyzing metabolic networks such as flux balance analysis (FBA), minimization of metabolic adjustment (MOMA), regulatory on / off minimization (ROOM), and dynamic flux balance analysis with linear quadratic regulator (DFBA-LQR). Then several kinds of commonly used software for flux analysis are introduced briefly and compared with each other. Finally, we highlight the applications of metabolic network flux analysis, especially its usage combined with other biological characteristics and its usage for drug design. The idea of combining the analysis of metabolic networks and other biochemical data has been gradually promoted and used in several aspects such as the combination of metabolic flux and the regulation of gene expression, the influence of protein evolution caused by metabolic flux, the relationship between metabolic flux and the topological characteristics, the optimization of metabolic engineering. More comprehensive and accurate properties of metabolic networks will be obtained by integrating metabolic flux analysis, network topological characteristics and dynamic modeling.     

Expanded flux variability analysis on metabolic network of Escherichia coli

Flux balance analysis, based on the mass conservation law in a cellular organism, has been extensively employed to study the interplay between structures and functions of cellular metabolic networks. Consequently, the phenotypes of the metabolism can be well elucidated. In this paper, we introduce the Expanded Flux Variability Analysis （EFVA） to characterize the intrinsic nature of metabolic reactions, such as flexibility, modularity and essentiality, by exploring the trend of the range, the maximum and the minimum flux of reactions. We took the metabolic network of Escherichia coli as an example and analyzed the variability of reaction fluxes under different growth rate constraints. The average variability of all reactions decreases dramatically when the growth rate increases. Consider the noise effect on the metabolic system, we thus argue that the microorganism may practically grow under a suboptimal state. Besides, under the EFVA framework, the reactions are easily to be grouped into catabolic and anabolic groups. And the anabolic groups can be further assigned to specific biomass constitute. We also discovered the growth rate dependent essentiality of reactions.     

Expanded flux variability analysis on metabolic network of Escherichia coli

Flux balance analysis, based on the mass conservation law in a cellular organism, has been extensively employed to study the interplay between structures and functions of cellular metabolic networks. Consequently, the phenotypes of the metabolism can be well elucidated. In this paper, we introduce the Expanded Flux Variability Analysis (EFVA) to characterize the intrinsic nature of metabolic reactions, such as flexibility, modularity and essentiality, by exploring the trend of the range, the maximum and the...     

Bow-tie topological features of metabolic networks and the functional significance

Exploring the structural topology of genome-based large-scale metabolic network is essential for in- vestigating possible relations between structure and functionality.Visualization would be helpful for obtaining immediate information about structural organization.In this work,metabolic networks of 75 organisms were investigated from a topological point of view.A spread bow-tie model was proposed to give a clear visualization of the bow-tie structure for metabolic networks.The revealed topological pattern helps to design more efficient algorithm specifically for metabolic networks.This coarse- grained graph also visualizes the vulnerable connections in the network,and thus could have important implication for disease studies and drug target identifications.In addition,analysis on the reciprocal links and main cores in the GSC part of bow-tie also reveals that the bow-tie structure of metabolic networks has its own intrinsic and significant features which are significantly different from those of random networks.     

A collaborative platform for complex product development based on multi-domain unified modeling and simulation

In order to intensify market competition,manufacturing enterprises must improve their product innovation capability.It is difficult to integrate the system modeling,simulation and collaborative process management in complex product development.A collaborative platform for complex product development based on multi-domain unified modeling and simulation is proposed in this paper.The architecture of the platform is firstly stated.The idea and realization of three key technologies,i.e.multi-domain modeling and simulation for complex product,knowledge management for product design and simulation,multi-domain collaborative mechanism,are emphasized.Finally,an industry case is given.The demonstration of the system shows that integration architecture is the effective infrastructure for multi-domain collaborative product development.     

板片空间结构稳定分析中的数值计算模型

分析了板片空间结构体系中板与骨架共同工作问题的力学机理,将接触问题的理论和方法应用到结构稳定问题的研究中,建立了相应的数值计算模型.基于共同工作问题的数值模拟,分析了该结构体系中板与金属骨架之间的接触单元安置、初始接触刚度对结构稳定分析计算的影响,提出了接触单元安置的原则和初始接触刚度选取的合理范围.数值计算结果与试验结果比较表明:该数值计算模型计算结果和试验结果符合较好,能够真实地反映板片空间结构实际的稳定工作状态,是合理和可靠的,而位移完全协调数值模型的结果较试验结果偏高,用于设计偏于不安全.     

一种基于重块平衡原理的砂轮动平衡系统建模方法

研究和分析了砂轮动平衡系统的执行机构平衡头的工作机理,借助电机电势平衡方程式和动力学平衡方程式,给出了系统的建模方法,并推导出其数学模型。     

基于数据处理的计算生态学研究现状

随着计算机技术的发展，计算生态学成为生态学计算领域的一门新兴学科．在查阅国内外计算生态学研究领域的大量资料的基础上，总结得出了计算生态学的研究步骤：生态学信息获取、生态学信息处理、生态学信息分析及分析结果显示；计算生态学的研究现状以及计算生态学需要加强的3个技术领域：数据处理、建模和可视化。     

面向供应链管理的行业信息系统问题域对象建模

基于供应链管理的结构模型和信息流传递模型,提出了一种行业信息系统问题域对象的建模方法.依照供应链的网络结构模型进行问题域的类结构设计,从供应链网络结构模型中的事物抽象出行业信息系统中的问题域类;依照供应链的集中式信息流传递模型进行问题域类的行为设计,将供应链信息流传递模型中的传递行为抽象为问题域的类行为.由此得出行业信息系统的问题域类结构模型和行为模型,并在一个实际应用系统中实现了该模型.