卡尔曼滤波用于酶反应动力学的研究

在分析化学计量学的研究中,卡尔曼滤波已获得了较广泛的应用。在动力学分析方面,应用卡尔曼滤波方法的研究工作也越来越引起人们的兴趣。Rutan 等人曾用扩展的卡尔曼滤波(EKF)——动力学分析法,研究了 Cu 置换 Pr—DCTA 及反式 CrCl_2(H_2O)_4~+水解为 CrCl(H_2O)~(2+)的速率常数,用 EKF 拟合2-与3-维 P-硝基苯膦酸的酶促反应,以及酯水解参数等。本文以过氧化氢组织电极采用卡尔曼滤波法研究了酶反应的动力学,获得了一些有意义的结果。     

响应面法优化波纹巴非蛤酶解工艺的参数

应用响应面分析法分别优化波纹巴非蛤蛋白2段酶解的条件,第一段酶解使用胰蛋白酶,以蛋白质利用率为响应值;第二段酶解用木瓜蛋白酶,以肽得率为响应值.最终确定第一段酶解的最优条件为:酶与底物质量比为0.4:100,酶解时间为3h,酶解温度为52.0℃;第二段酶解的最优条件为:酶与底物的质量比为0.25:100,酶解时间为7.62 h,酶解温度为57.0℃,在此条件下,肽得率为54.35％,与模型的预测值55.67％接近.经2段酶解的上清液中小分子肽平均含量为2.25％.     

壳聚糖酶解产物分子量分布优化控制研究

在壳聚糖酶解产物分子量分布模拟的基础上,运用遗传算法,对壳聚糖酶解过程产物分子量分布的优化控制进行研究。以酶解原料壳聚糖的脱乙酰度、水解度作为优化参数,以特定范围分子量的酶解产物最大得率为目标,研究优化过程的实现技术,得到了适于壳聚糖酶解产物分子量分布优化控制的算法。经实验验证,优化结果可靠。研究结果表明,遗传算法能有效地运用于壳聚糖酶解产物分子量分布的优化控制。     

樱桃根际土壤特征及其评价

为探讨樱桃植株生长发育对根际土壤因子的影响,评价其根际生态环境,对土壤的pH值、速效养分、酶及微生物等19种指标的根际分布特征和相互关系进行了分析。结果表明,土壤pH值、氧化还原电位(Eh)、碱解氮、蛋白酶、过氧化氢酶、细菌及总菌数表现为根际负效应([R/S)<1],速效磷、速效钾、交换性钙、交换性镁、有效铁、有效锰、有效铜、脲酶、中性磷酸酶、放线菌及真菌表现为根际正效应([R/S)>1],有效锌根际效应不显著。脲酶、中性磷酸酶及蛋白酶3种水解酶活性与pH值及Eh的特征向量和载荷较大,可将其归为同一类综合指标,反映或评价以根际碱解氮为代表的土壤肥力状况。pH值、碱解氮等化学指标,土壤酶、微生物等生物活性指标在一定程度上可反映樱桃根际生态环境状况。     

辣根过氧化物酶脂膜生物传感器的研究

以微孔纤维素滤膜为载体,制成辣根过氧化物酶人造双分子层脂膜,组装到自制探头中,构成脂酶膜生物传感器。测定了该膜酶的动力学参数K_m和V_m,最适温度和最适pH值,并和自由酶进行了对比。用蒸馏水配制的双氧水溶液作为模拟试样,测定了该膜膜电位差△φ(mV)和H_2O_2浓度C_(H_2O_2)(μmol/L)的线性关系:拟合直线的相关系数K=0.97。     

正己烷裂解反应自由基模型的理论研究

采用量子化学法研究了模型化合物正己烷裂解过程,并计算其动力学参数。依据自由基理论,建立由216个基元反应组成的正己烷裂解反应自由基模型,用CBS-QB3法计算链引发和终止反应动力学参数,用MPW1B95/6-311+G(2d,2p)法计算链增长反应动力学参数。根据动力学参数计算结果,忽略相对不重要的反应,将模型简化为160个基元反应。模拟计算表明,在相同的裂解条件下,简化模型模拟结果与完整模型模拟结果一致,各组分相差不大于0.1%wt;建立的动力学模型对主要产物收率预测较好,与实验值相差小于0.7%wt,可正确地预测正己烷裂解产物的组成和各组分含量沿反应管长度的分布,为进一步研究复杂的烃裂解过程提供了基础。     

尿素水解系统的模拟与分析

结合NH₃-CO₂-Urea-H₂O（ACUW）体系扩展型UNIQUAC气液平衡模型、经验型液相焓值模型以及尿素水解反应动力学模型,建立了针对尿素水解系统的过程模拟数学模型并实现模拟计算,模拟结果能较好地描述尿素水解装置的实际情况。借助模拟程序分析了蒸汽流量、操作压力及进料组成对尿素水解系统的出气氨水比、排液氨含量的影响,可为企业的操作优化、节能减排提供理论指导和参考。     

复杂网络演化的舆论动力学模型及仿真分析

针对舆论传播过程中复杂动力学演化问题,提出一种基于传播动力学的舆论动态演化模型。首先,构建舆论及舆论演化模型,通过方程变换求出静态解;其次,引入Fokker-Planck方程对舆论演化渐近行为进行分析,得到稳态解决方案并求解,构建复杂网络与模型的关联并提出仿真研究实验目的;最后,通过对舆论演化模型及引入Fokker-Planck方程的舆论意见模型进行仿真分析,并以真实微博舆论数据为例进行实证分析,研究舆论在复杂网络中传播和演化的实质。实验结果表明舆论网络演化渐近行为与度分布相一致,网络舆论传播中的连接方式会受到节点意见影响,模型能有效描述微博舆论传播网络形成和演化过程的动力学行为。     

通用遗传算法估算化学及生化反应动力学参数

遗传算法是一种借鉴生物界自然选择和进化机制发展起来的高度并行、随机、自适应的搜索方法。MATLAB通用遗传算法工具箱GAOT本着使用群体搜索技术,将种群代表一组问题的解,通过对当前种群施加选择、交叉和变异等一系列遗传操作,从而得到新的一代种群,并逐步使种群进化到包含近似最优解状态的原则,对苯热裂解脱氢反应及产赖氨酸分批发酵动力学模型参数进行了估算。与文献中已有的结果相比,模型计算值与实验值的吻合程度相似或更优。所用方法也可用于以微分方程组为数学模型的这类过程的参数估算或寻优,从而研究者可以更加集中注意力于深入解决与数学模型本身有关的问题。     

全自动酶免分析仪定量分析系统研究

为了提高酶免分析仪检测精度,建立了基于改进遗传算法的多组分定量分析校正模型。通过自适应寻优空间技术和小生境技术,对遗传算法进行改进。采用全息凹面光栅作为分光元件,搭建扫描式紫外可见分光光度实验系统,对食品工业中最常见的苋菜红和胭脂红二组分混合水溶液进行定量分析,并与最小二乘回归方法进行了比较。实验结果表明：改进遗传算法预测精度与最小二乘法相近,对苋菜红和胭脂红的预测均方根误差（ RMSEP）分别为0.88,1.71μg/mL;收敛速度明显快于传统遗传算法,为多组分同时测定提供了新的思路。     

Theoretical investigation of enzymatic hydrolysis of polypeptides in nanofluidic channels

Label-free detection of enzymes using nanofluidic channels requires enzymes to diffuse into a nanochannel and react with substrates already immobilized on the nanochannel surfaces. A theoretical model is necessary to predict the reaction progress in the confined space and translate it to the electrical readouts of the nanochannel. In this paper, enzymatic hydrolysis of polypeptides in nanofluidic channels is considered and a 1-D model is developed that accounts for various reaction kinetics, enzyme diffusion and non-specific adsorption. The polypeptides have multiple cleavage sites which can be cleaved in different orders depending on the type of enzyme. Here it is shown that this process creates two types of reaction fronts inside the nanochannel which advance linearly with time once they are fully developed. Such constant reaction rates can be predicted by an analytical model. The numerical simulations are validated against the experimental results of trypsin–polylysine reaction in nanochannels, and a good agreement between the two is observed. This study deepens our understandings of enzymatic reactions in nanoscale-confined spaces and can guide the development of a fast-response, label-free enzyme sensor based on nanochannels.     

在Maple平台上应用最小二乘法估算动力学参数

以大量实验数据为基础在Maple平台上运用最小二乘法,估算了气相苯加氢反应中反应速率常数及苯的吸附平衡常数,结果较为满意;并且估算了CO与Cl_2在活性炭表面上催化合成光气的反应中动力学的最优参数,计算值与实验值的最大相对误差不超过5%;最后推算了NO与H_2反应的反应速度方程式,计算值与文献值很相似。应用这种方法既克服手工计算的繁琐、工作量大的缺点,还能提高计算的精度,大大地方便了化学反应速率式的确定。     

Separation of CO2 by single and mixed aqueous amine solvents in membrane contactors: fluid flow and mass transfer modeling

Removal of carbon dioxide from gas mixtures is of vital importance for the control of greenhouse gas emission. This study presents a numerical simulation using computational fluid dynamics of mass and momentum transfer in hollow-fiber membrane contactors. The simulation was conducted for physical and chemical absorption of CO₂. A mass transfer model was developed to study CO₂ transport through hollow-fiber membrane contactors. The model considers axial and radial diffusions in the contactor. It also considers convection in the tube and shell side with chemical reaction. The model equations were solved by numerical method based on finite element method. Moreover, the simulation results were validated with the experimental data obtained from literature for absorption of CO₂ in amine aqueous solutions as solvent. The simulation results were in good agreement with the experimental data for different values of gas and liquid velocities. The simulation results indicated that the removal of CO₂ increased with increasing liquid velocity in the tube side. Simulation results also showed that hollow-fiber membrane contactors have a great potential in the area of gas separation specially CO₂ separation from gas mixtures.     

非均匀表面两阶段吸附模型的改进

非均匀表面两阶段吸附模型是适用于各种类型吸附等温线的表面活性剂固液界面吸附热力学模型，为了更好地反映第3组分（助剂、第二表面活性剂、无机盐和碱等），对表面活性剂吸附的影响。本文对非均匀表面两阶段吸附模型进行改进，导出了新的能用于有极限吸附和无极限吸附体系的吸附等温方程式。用此方法式关联含第3级分体系的吸附实验结果，计算值和实验值符合很好。     

Sufficient conditions for the preservation of the boundedness in a numerical method for a physical model with transport memory and nonlinear damping

Departing from a finite-difference scheme to approximate solutions of a nonlinear, hyperbolic partial differential equation which generalizes the Burgers–Huxley equation from fluid dynamics, we investigate conditions on the model coefficients and the computational parameters under which positive and bounded initial data evolve into positive and bounded new approximations. The model under investigation includes nonlinear coefficients of damping and advection, and the reaction term extends the reaction law of the classical Fisher–Kolmogorov–Petrovsky–Piscounov equation. The method can be expressed in vector form in terms of a multiplicative matrix which, under certain parametric conditions, becomes an M-matrix. Using the fact that every M-matrix is non-singular and that the entries of its inverse are positive, real numbers, we establish sufficient conditions under which the method provides new, positive and bounded approximations from previous, positive and bounded data and boundary conditions. The numerical results confirm the fact that the conditions derived here are sufficient for the positivity and the boundedness of the approximations; moreover, computational experiments evidence the fact that the method still preserves these properties for values of the model and the numerical parameters outside of the analytic regions of positivity and boundedness. We point out that our simulations show a good agreement between the numerical approximations computed through our method and the corresponding, analytical solutions.     

Identification of Contact Dynamics Parameters for Stiff Robotic Payloads

This paper investigates and demonstrates the feasibility of identifying contact dynamics parameters for stiff robotic payloads using a robotic system. The contact dynamics model for stiff payloads is motivated, and theoretical parameter values and bounds are provided. Then, the effect of nonidealities such as surface roughness and plastic deformation on the theoretical values is demonstrated. A row-wise-scaled total least-squares parameter estimation algorithm is proposed and applied to experimental data measured using the special purpose dexterous manipulator task verification facility manipulator at the Canadian Space Agency. The experimental results are compared to a separate set of experiments with a material testing machine as well as finite-element modeling results. Finally, the experimental findings are generalized by providing guidelines for the maximum identifiable payload stiffness as a function of the position resolution, the maximum exertable force, and the structural stiffness of the robotic system.     

A combined QM/MM study of the nucleophilic addition reaction of methanethiolate and N-methylacetamide

A combined quantum mechanical (QM) and molecular mechanical (MM) method was used to study the nucleophilic addition reaction of methanethiolate to N-methylacetamide (NMA) in the gas phase and aqueous solution. At the B3LYP/aug-cc-pVDZ//HF/6-31 + G(d) level, the ion-dipole complex was found to be the global minimum on the potential energy surface in the gas phase with a binding energy of 21.2 kcal/mol. The complex has a C-S distance of 4.33 A, and no stabilized tetrahedral intermediate was located. The computed potential of mean force in water shows that solvent effects stabilize the reactants over the tetrahedral adduct by 36.5 kcal/mol, and that the tetrahedral intermediate does not exist for the present reaction in water. The present study provides an initial step for modeling the cysteine protease hydrolysis reactions in enzymes.     

基于动态均衡分析的网格资源宏观调价策略

针对现有网格资源调价研究中多采用静态均衡分析而未考虑动态均衡分析和宏观干预调价的问题，提出一种基于动态均衡分析的宏观调价策略。先结合网格特点建立改进的非线性非均衡调价模型，然后对该模型进行动态性和稳定性分析，并根据分析结果提出宏观调价策略。通过实验验证了模型均衡点的存在性和稳定性，以及调价策略的正确性。     

微型直接甲醇燃料电池的三维数值模拟研究

运用计算流体力学软件COMSOLTM建立了微型直接甲醇燃料电池(μDMFC)三维数值模型,并用MEMS工艺制作电池进行实验验证.模型耦合了连续性方程、电化学反应方程和动量方程等.通过对模型求解,输出了平均电流密度和电压等参数.分析了扩散层和催化层结构参数对电池性能的影响,结果表明:过厚的催化层对电池性能提升并无太大帮助,在增大电催化剂Pt担量前提下应尽量减小催化层厚度.     

MATLAB用于化学吸收过程动态模拟

建立了典型的带有一、二级化学反应气液吸收过程的数学模型,然后采用MATLAB的dsolve和ode功能函数,对模型中的液膜内扩散-反应方程和液相主体吸收方程进行求解,部分计算结果还与实验值进行了比较,结果表明MATLAB可实现化学吸收动态过程的快速、高效、准确模拟。