An enzyme immunoanalytical system based on sequential cross-flow chromatography

A new enzyme immunoanalytical concept that can be used for point-of-care testing has been investigated. Enzyme as a tracer requires a separate reaction step for signal generation, which follows the completion of immune complex formation with analyte (e.g., Hepatitis B surface antigen) in a sample. This has been a major factor limiting its utilization within the laboratory. We carried out such sequential processes employing chromatographic analysis, using two crosswise-arranged membrane pads in vertical and horizontal directions. The vertically arranged pads were the same as those in the usual format for pregnancy testing, for instance, with the exception of the use of horseradish peroxidase (HRP) as tracer. By placing the horizontally arranged pads on each lateral side of the signal generation pad in the vertical arrangement, they were employed to supply substrate to the enzyme present in the immune complexes. The substrate flow was initiated after the antigen-antibody bindings to produce a signal, which was typically a color change in proportion to the analyte concentration. Under optimal conditions, the use of HRP labeling increased the detection capability of the assay approximately 30 times compared to that of gold colloids. Potential advantages of using the concept investigated are (1) provision of a rapid and simple immunoassay, (2) satisfaction of a clinical need for highly sensitive determination of analyte, and (3) utilization of relatively inexpensive, portable quantitation means.     

Bipolar ion detector based on sequential conversion reactions

This work demonstrates the feasibility of a novel scintillation detector with greater detection efficiency than that of chevron-type microchannel plate (MCP) detectors. The detection mechanism involves sequential conversion reactions induced by ion-surface impacts. Identical detection conditions can be utilized to monitor both positive and negative ions in mass spectrometers. The proposed detector comprises an ion beam guiding device, a negatively biased washer-shaped conversion dynode, and an aluminum-coated scintillation detector. The beam guide changes the electric field around the washer-shaped conversion dynode, and it allows the primary and secondary ions to propagate toward the scintillation phosphor and the conversion dynode, respectively. The detection is achieved by the detection of electron-induced luminescence on a phosphor. The amplification efficiency of this bipolar ion detector increases as the conversion dynode voltage increases. For ions with a mass-to-charge ratio of up to 90 000, the sensitivity of the BID is 1.4-14.4 times that of the MCP. Further improvement of the sensitivity can be achieved by increasing the conversion dynode voltage or the ion acceleration voltage. Results of this study demonstrate that this detector is a promising alternative for efficient ion detection.     

一种高效的基于位图序列模式挖掘算法

为实现在大型事务数据库中挖掘有价值的序列数据,提出了一种基于位图的高效的序列模式挖掘算法(SMBR)。SMBR算法采用位图表示数据库的方法,提出一种简化的位图表示结构。该算法首先由序列扩展和项扩展产生候选序列,然后通过原序列位图和被扩展项位图位置快速运算生成频繁序列。实验表明,应用于大型事务数据库,该方法不仅能有效地提高挖掘效率,而且挖掘处理过程中产生的临时数据所需的内存大大降低,能够高效地挖掘序列模式。     

叉流再生器性能试验研究

搭建叉流再生器性能试验台,利用Celdek规整填料作为气液接触介质,再生剂选用LiCl-H2O溶液,选取再生量和再生效率作为再生性能的评价指标。试验分析空气、溶液进口参数对再生性能的影响,并利用试验数据建立适用于LiCl-H2O溶液的再生效率和传质系数的试验关联式。最后将试验结果与文献中的相关结果进行比较,结果表明:不同的再生剂对再生性能的影响基本相同;当溶液浓度较低时(LiCl-H2O溶液≤32%),使用LiCl-H2O溶液比使用LiBr-H2O溶液的再生量大,而溶液浓度较高时,情况反之。     

Kinetic chromatographic sequential addition immunoassays using protein A affinity chromatography.

A new type of chromatographic immunoassay based on sequential addition is described. On a protein A column, the antibody, the sample containing the antigen, and then a known amount of antigen are sequentially injected. This assay is designed to shorten analysis times and reduce complexity of dual-column chromatographic immunoassays, circumvent desorption buffer interferences common to affinity chromatography, and eliminate the need for tagged molecules. This new technique is named kinetic immunochromatography sequential addition (KICQA). Because of its kinetic nature, flow rate will have a large effect on KICQA, and the impact of changing flow rate is studied extensively. By use of various amounts of antibody, the dynamic range of KICQA is shown to be selectable over 2.5 orders of magnitude. Finally, KICQA was used to determine transferrin and albumin in human serum. Both analytes show good agreement with their respective reference methods, and an albumin assay was performed in under 1 min.     

基于序贯蒙特卡洛法的自相关过程控制

针对参数未知的自相关过程在线质量控制问题,研究了基于序贯蒙特卡洛法(SMC)的过程控制策略。在给出过程状态空间方程模型的基础上,分析了由于参数未知使得运用Kalman滤波求解控制策略时存在的困难;通过设置未知参数的先验分布,运用序贯蒙特卡洛法得到各参数的后验估计,进而获得了使过程损失最小的控制策略。给出了仿真,以分析控制策略的有效性,结果表明所得到的控制策略具有较好的控制效果。     

Adaptive charting schemes based on double sequential probability ratio tests

Sequential probability ratio test (SPRT) control charts are shown to be able to detect most shifts in the mean or proportion substantially faster than conventional charts such as CUSUM charts. However, they are limited in applications because of the absence of the upper bound on the sample size and possibly large sample numbers during implementation. The double SPRT (2‐SPRT) control chart, which applies a 2‐SPRT at each sampling point, is proposed in this paper to solve some of the limitations of SPRT charts. Approximate performance measures of the 2‐SPRT control chart are obtained by the backward method with the Gaussian quadrature in a computer program. On the basis of two industrial examples and simulation comparisons, we conclude that the 2‐SPRT chart is competitive in that it is more sensitive and economical for small shifts and has advantages in administration because of fixed sampling points and a proper upper bound on the sample size. Copyright © 2008 John Wiley & Sons, Ltd.     

Maximum time interval error assessment based on the sequential reducing data volume

This paper deals with the problem of efficient assessment of maximum time interval error (MTIE) for a series of observation intervals. The method expands the concept of the extreme fix method, which also is briefly described. Then the idea of the extreme fix with sequential data reducing method of MTIE estimate calculation is thoroughly developed. The mechanism of sequential reducing data volume is explained. The time efficiency of the method proposed is evaluated through comparison of the time taken to compute MTIE estimate by means of this method and the method resulting directly from the MTIE estimator formula (the direct method) as well as the extreme fix method of the MTIE estimate calculation. Distinctive performance of the method proposed is confirmed by the MTIE calculation experiment     

基于Stochastic Kriging模型的不确定性序贯试验设计方法

不确定性研究中需要计算大量重复样本,这无疑对计算量较大的数值模拟提出了巨大的挑战.通过试验设计方法可以有效地减少不确定性研究中的计算量,然而,目前考虑不确定性的试验设计方法研究大多仍专注于传统试验设计方法.针对这一问题,为了通过更为合理的计算资源分配得到更精准的不确定性评估,基于有限样本的Stochastic Kriging模型提出了针对不确定性问题的三阶段序贯试验设计方法.首先,通过特定位置的采样对IMSE进行简化,构建了预选步进信息选取策略,通过预选增量样本总个数以及各取样位置处的分布信息,达到随机代理模型目标精度要求;同时,基于IMSE构建了基于步进信息的单轮选点试验设计准则,以同时考虑设计变量的取样位置及其分布信息.由算例与传统方法的对比分析可知,所建立方法通过等量的采样得到了精度更高的随机代理模型,验证了其在不确定性问题中的可行性和优势.     

Effect of particle size on the performance of cross-flow microfiltration

The effects of particle size on the cake properties and the performance of cross-flow microfiltration are studied. A particulate sample with a wide size distribution range from submicron to micron is used in experiments. The probabilities of particle deposition are analyzed based on a force analysis. Since themajor forces in determining the particle deposition and packing in the filter cake are different for submicron and micron particles, the particle size plays an important role in the filtration performance. Cake properties, such as mass, porosity and average specific filtration resistance of the cake, are calculated theoretically and compared with experimental data. Except for the overestimation of the mean particle size for about 1 μm, the calculated results of the pseudo-steady filtration rate and cake properties under various operating conditions agree fairly well with the experimental data.     

Two-Dimensional detection in ion chromatography: sequential conductometry after suppression and passive hydroxide introduction

An improved method that uses sequential suppressed and nonsuppressed IC for the sensitive detection of both common anions and very weak acid anions is described. After suppressed conductometric detection of an electrolytically generated hydroxide eluent and an electrolytic suppressor, the eluent is passed into a membrane device where KOH is passively introduced into the eluent stream using Donnan forbidden leakage. A second conductivity detector then measures the conductivity of the stream. The background conductance of the second detector is typically maintained at a relatively low level of 20-30 microS/ cm. The weak acids are converted to potassium salts that are fully ionized and are detected against a low KOH background as negative peaks. The applicability of different commercially available cation exchange membranes was studied. Device configurations investigated include planar, tubular, and a filament-filled annular helical (FFAH) device. The FFAH device provided more effective mixing of the penetrated hydroxide with the eluent stream, resulting in a noise level of < or = 7 nS/cm and a band dispersion value of less than 82 microL. Optimal design and performance data are presented.     

Frost formation and heat transfer on circular cylinders in cross-flow

When humid air comes into contact with a surface whose temperature is below the dew point of water vapour in air and also below the freezing point, frost deposition takes place over the surface. Previous studies indicate that the heat transfer rate increases at the initial stages of deposition since the rough frost surface acts as a finned one. As the frost thickens, however, the insulating effect of the frost layer predominates resulting in a reduction in the heat transfer rate. This paper presents a transient model to predict the frosting process over a circular cylinder in a cross-flow of humid air. the transfer parameters are computed employing a numerical solution of the momentum, energy and diffusion boundary-layer equations along with the continuity equation, using a finite difference scheme. Empirical correlations for thermal conductivity and density are utilized for closure purposes. Model results are compared with existing experimental data and with numerical data of previous investigators and are found to agree well in the applicable temperature and humidity ranges of the frost density and conductivity correlations.     

Transient behaviour of finned-tube cross-flow heat exchangers

Three different approaches are developed for the prediction of transient performance of cross-flow finned-tube, liquid/gas heat exchangers for the step change in the inlet temperature of the hot fluid. These are called the zero solid capacity, one solid capacity and two solid capacity approaches (ZCA, OCA and TCA respectively). In the analysis using ZCA, the heat capacities of the wall and fins are added to the capacities of the hot and cold fluids. The temperature variation of both fluids between inlet and exit is assumed to be linear, and the effective rate of heat transfer is assumed to be proportional to the difference of the average temperatures on both sides. In the analysis using OCA the fins and tube wall are considered as one thermal capacity and the thermal resistance between them is neglected. However, in the analysis using TCA the capacities of the fins and tube wall are considered separately. Energy equations for the hot and cold fluid, tube wall and the fins, if they are to be considered, are derived for each of these approaches and solved numerically using a finite-difference method. The variation of the dimensionless exit temperature of the hot and cold fluid with time is obtained for a step change in the inlet temperature of the hot fluid. To show the appreciability of these approaches, an experimental study is performed and the numerical results are compared with the experimental results.     

Method for the sequential online analysis of enzyme reactions based on capillary electrophoresis

We have developed an easy-to-operate and effective method for performing the sequential online analysis of enzyme reactions based on capillary electrophoresis (CE). The system was constructed by passing two capillaries through a sample vial at a distance of 5 μm between the capillary ends. Direct online sample injection and sequential CE analysis were achieved by periodically switching the high-voltage power supply off and on, without any physical disturbance of the capillary inlet. The sample was injected via concentration diffusion with in-column derivatization of the amino acids occurring at the interface of the capillaries. High reproducibility of the sequential injections was demonstrated with relative standard deviation values (n = 20) of 1.01%, 1.25%, and 0.80% for peak height, peak area, and migration time, respectively. Sequential online CE enzyme assay of a glutamate pyruvate transaminase catalyzed enzyme reaction was carried out by simultaneously monitoring the substrate consumption and the product formation every 30 s from the beginning to the end of the reaction. The Michaelis constants for the reaction were obtained and were found to be in good agreement with the results of traditional off-line enzyme assays. Our method has great potential for usage in sequential online CE analysis of chemical reactions with in-column chemical derivatization of the analytes for ultraviolet or laser-induced fluorescence detection.     

基于序贯层次Kriging模型的微型飞行器机身结构设计优化

在基于仿真模型的工程设计优化中,采用高精度、高成本的分析模型会导致计算量大,采用低精度、低成本的分析模型会导致设计优化结果的可信度低,难以满足实际工程的要求。为了有效平衡高精度与低成本之间的矛盾关系,通过建立序贯层次Kriging模型融合高/低精度数据,采用大量低成本、低精度的样本点反映高精度分析模型的变化趋势,并采用少量高成本、高精度的样本点对低精度分析模型进行校正,以实现对优化目标的高精度预测。为了避免层次Kriging模型误差对优化结果的影响,将层次Kriging模型与遗传算法相结合,根据6σ设计准则计算每一代最优解的预测区间,具有较大预测区间的当前最优解即为新的高精度样本点。同时,在优化过程中序贯更新层次Kriging模型,提高最优解附近的层次Kriging模型的预测精度,从而保证设计结果的可靠性。将所提出的方法应用于微型飞行器机身结构的设计优化中,以验证该方法的有效性和优越性。采用具有不同单元数的网格模型分别作为低精度分析模型和高精度分析模型,利用最优拉丁超立方设计分别选取60个低精度样本点和20个高精度样本点建立初始层次Kriging模型,采用本文方法求解并与直接采用高精度仿真模型求解的结果进行比较。结果表明,所提出的方法能够有效利用高/低精度样本点处的信息,建立高精度的层次Kriging模型;本文方法仅需要少量的计算成本就能求得近似最优解,有效提高了设计效率,为类似的结构设计优化问题提供了参考。     

Application of sequential quadratic programming based on active set method in cleaner production

Clean Technologies and Environmental Policy - On the platform of general chemical process simulation software (it was named Optimization Engineer, OPEN), a general optimization algorithm for...     

Digital holographic microscopy with sequential off-axis illumination directions based on spatial light modulator

Digital holographic microscopy (DHM) with time-sequential off-axis illumination directions can synthesize a large aperture, and thus have a higher spatial resolution than the one with on-axis illumination. In this paper, time-sequential off-axis illumination directions are generated by a spatial light modulator (SLM) in DHM, and the residual phases along different illumination directions are suppressed by using the phase compensation technique, as such the image with resolution enhancement is reconstructed. The usage of SLM enables shifting the illumination for different orientations and phase shifts without mechanical motion. The experiments have been conducted to verify the feasibility of this method on the residual phase suppression.     

系统组织工程技术优化的正丁胺含量离子色谱检测

该文采用系统组织工程技术(ZTSO)快速优化并建立正丁胺含量测定的离子色谱法。选用AcelaimTMTrinityTM P1(3.0 mm×100 mm,3μm)为色谱柱,18 mmol/L乙酸铵(用乙酸调p H 3.4)∶乙腈(56∶44,ν∶ν)为淋洗液,在柱温37℃,流量0.15 m L/min的条件下等度洗脱,电导检测器检测,20 min内完成正丁胺的含量测定。结果表明:正丁胺质量浓度在10.01~500.5μg/m L范围内线性关系良好(r2=0.999 8),检测限为5.05μg/m L(S/N≥3),定量限为10.01μg/m L(S/N≥10),日内和日间精密度分为0.33%和0.90%,正丁胺供试品溶液在24 h内稳定(RSD=0.54%),3批正丁胺原料的平均含量为99.79%(RSD=0.125%),3批肿瘤血管抑制剂XY03中正丁胺的平均含量为20.32%(RSD=4.09%),热干燥时,XY03中铵盐的下降率与其溶解度呈正相关。ZTSO技术具有较好的条件优化功能,所建立的方法快速、简便和准确,是正丁胺或含正丁铵盐化合物含量测定的较好方法。     

Coupling of sequential injection chromatography with multivariate curve resolution-alternating least-squares for enhancement of peak capacity

Flow-through low-pressure chromatographic separations capitalized on the sequential injection chromatographic (SIC) concept are for the first time coupled to second-order multivariate regression models based on multivariate curve resolution-alternating least-squares (MCR-ALS) for outperforming current chromatographic methods in terms of resolution efficiency. The proposed SIC-MCR-ALS method involving sequential injection separation on short monolithic columns along with isocratic elution fosters ultrafast reversed-phase separations of complex multicomponent mixtures regardless of peak overlapping and retention parameters. The ruggedness of SIC systems is enhanced by removing the solenoid valves from the flow network, thus diminishing the column back pressure effects. As a consequence, the flow setup admitted mobile-phase flow rates much higher than those traditionally enabled in SIC. To ascertain the improved peak capacity of the SIC-MCR-ALS procedure, five phenolic species commonly used in disinfectant products and featuring similar UV spectra and close retention times in short reversed-phase silica-based monolithic phases are selected as model compounds and determined in just 1 min using mobile-phase flow rates of >or=2 mL min(-1). Notwithstanding the fact that the five phenolic derivatives coelute in a single chromatographic band, thus rendering resolution values ranging from 0.05 to 1.11, the concentration profiles and the pure spectra of each individual phenol species could be concurrently obtained. Quantitative validation of the chromatographic-chemometric method demonstrated both the reliability of the results and the enhanced resolution of mixtures with regard to former SIC systems with no need for thorough optimization of the separation conditions.