氢供体组与辣根过氧化酶活性光谱研究

对邻苯二酚-苯胺和苯酚-氨基安替吡啉构成的两组测定HRP酶活性的体系进行了研究和比较。紫外可见光光谱和高效液相色谱分析表明,在HRP催化过程中,邻苯二酚-苯胺氢供体对会生成为一种粉红色产物,该产物最大吸收波长在510咖,可用于HRP的活性测量。且与常规使用的苯酚-氨基安替吡啉氢供体对的情况相比,具有更高的灵敏度、更低的检测限值和很好的重复性,在对HRP分别进行20次酶活测量,所得相对标准偏差仅为2．9％。使用邻苯二酚-苯胺氢供体对的方法可计算得到酶动力学参数Km（12．5mM）和Vmax（12．2mMmin^-1mg^-1）。     

Discriminative functional analysis of human movements

This paper investigates the use of statistical dimensionality reduction (DR) techniques for discriminative low dimensional embedding to enable affective movement recognition. Human movements are defined by a collection of sequential observations (time-series features) representing body joint angle or joint Cartesian trajectories. In this work, these sequential observations are modelled as temporal functions using B-spline basis function expansion, and dimensionality reduction techniques are adapted to enable application to the functional observations. The DR techniques adapted here are: Fischer discriminant analysis (FDA), supervised principal component analysis (PCA), and Isomap. These functional DR techniques along with functional PCA are applied on affective human movement datasets and their performance is evaluated using leave-one-out cross validation with a one-nearest neighbour classifier in the corresponding low-dimensional subspaces. The results show that functional supervised PCA outperforms the other DR techniques examined in terms of classification accuracy and time resource requirements.     

Observer-based reliable control for Lipschitz nonlinear networked control systems with quadratic protocol

International Journal of Control, Automation and Systems - In this paper, observer-based reliable control problem for nonlinear networked control systems (NCSs) with quadratic protocol (QP) in...     

镍离子增强辣根过氧化物酶法合成联苯研究

通过2 mM Ni2+孵化辣根过氧化物酶,可制备活化辣根过氧化物酶(Ni2-HRP),实验验证了Ni2-HRP的活性和稳定性,并对Ni2-HRP催化2-二叔丁基苯酚反应的生成物进行了CC/MS,HPLC和核磁共振鉴定,确定为2,4,2′,4′-四羟基-5,5′-二叔丁基联苯,是一种几乎无毒的化合物,可作为制药前体的使用...     

Artificial neural network–genetic algorithm for estimation of crop evapotranspiration in a semi-arid region of Iran

This study compares the daily potato crop evapotranspiration (ET_C) estimated by artificial neural network (ANN), neural network–genetic algorithm (NNGA) and multivariate nonlinear regression (MNLR) methods. Using a 6-year (2000–2005) daily meteorological data recorded at Tabriz synoptic station and the Penman–Monteith FAO 56 standard approach (PMF-56), the daily ET_C was determined during the growing season (April–September). Air temperature, wind speed at 2 m height, net solar radiation, air pressure, relative humidity and crop coefficient for every day of the growing season were selected as the input of ANN models. In this study, the genetic algorithm was applied for optimization of the parameters used in ANN approach. It was found that the optimization of the ANN parameters did not improve the performance of ANN method. The results indicated that MNLR, ANN and NNGA methods were able to predict potato ET_C at desirable level of accuracy. However, the MNLR method with highest coefficient of determination (R ² > 0.96, P value < 0.05) and minimum errors provided superior performance among the other methods.     

A new electrochemical biosensor for hydrogen peroxide using HRP/AgNPs/cysteamine/p-ABSA/GCE self-assembly modified electrode

An electrochemical hydrogen peroxide biosensor was designed by immobilizing horseradish peroxidase (HRP) on Ag nanoparticles/cysteamine/p-aminobenzene sulfonic acid/glassy carbon (GC) electrode. Ag nanoparticles can act as tiny conduction centers on electrodes that adsorb redox enzymes, facilitating the transfer of electrons with no requiring any loss of biological activity. The forerunner film was first electropolymerized on the glassy carbon electrode with p-aminobenzene sulfonic acid (p-ABSA) by cyclic voltammetry. The cysteamine (CA) was bound on the surface of the film by electrostatic force, then Ag nanoparticles were immobilized on the cysteamine monolayer, and lastly HRP was adsorbed onto the surfaces of the Ag nanoparticles. A dramatic decrease in the overvoltage of H₂O₂ was observed with improved sensitivity, which makes the modified electrodes of great promise for oxidase-based amperometric biosensors. The biosensor responded to H₂O₂ in the linear range from 1.2×10⁶ mol/L to 9.8×10³ mol/L with a detection limit of 1.1×10⁸ mol/L. Moreover, the obtained biosensor exhibited good accuracy and high sensitivity.     

Regional Estimation of Reference Evapotranspiration in Arid and Semiarid Regions

Evapotranspiration is critical to many applications including water resource management, irrigation scheduling, and environmental studies. Many models based on meteorological data have already been developed to estimate reference evapotranspiration (ET0) in various climatic and geographical conditions. The main purpose of this study was to evaluate the performances of the Makkink, Priestley-Taylor, and Hargreaves models versus the Penman-Monteith FAO-56 (PMF-56) method in arid and semiarid regions of Iran during 1993–2005 and to identify the alternative ET0 model that presents results closest to the PMF-56 method. Additionally, a regional estimation of monthly ET0 with the best-performed model is presented by using the spatially distributed physical parameters and geographical information system. The results indicated that the Hargreaves model was the best model to estimate ET0 in eastern arid and semiarid regions of Iran. The spatial distribution maps of ET0 showed that ET0 values increased from north to south as the aridity increased in the study area. The estimated total monthly ET0 revealed a significant variation during the growing seasons (April–September) so that the study region experienced the highest and lowest ET0 values of 250 and 80 mm in July and April, respectively.     

An Improved Estimation of the Angstrom–Prescott Radiation Coefficients for the FAO56 Penman–Monteith Evapotranspiration Method

The FAO56 Penman–Monteith (FAO56-PM) method is known as the standard method for estimating reference evapotranspiration (ET₀) in a variety of climate types. Global solar radiation (R_s) is one of the essential inputs of this model, which is usually estimated from the Angstrom–Prescott (AP) method. The major drawback of the FAO56 pre-defined AP coefficients application is that the AP coefficients might need local calibration, to estimate ET₀ accurately. The aim of this study is to compare the effect of the FAO56 pre-defined AP coefficients (i.e. a and b) and the locally calibrated ones, on estimating daily ET₀ in 15 sites over Iran. Using long-term (1980–2007) experimental global solar radiation data (R_s), new locally calibrated (a) and (b) coefficients are suggested and new ET₀ values are determined accordingly. It was found that the range of the calibrated AP coefficients (a, b) are climate dependent and locally different from those of recommended by the FAO56-PM method. Estimated ET₀ at daily scale, improved up to 72.7 % when the calibrated AP coefficients were applied instead of FAO56 pre-defined AP coefficients. Based on the results, applying the FAO56 pre-defined AP coefficients (i.e. a?=?0.25 and b?=?0.50) in northern subtropical-humid and southern hot climates caused larger ET₀ errors. By contrast, the least ET₀ errors were found in cool arid and cool semi-arid inland climates, locating about 1,330 above sea level. The correlations between the calibrated AP coefficients and geographical factors are also discussed in this research.     

Pyrus biossieriana Buhse leaf extract: An antioxidant,antihyperglycaemic and antihyperlipidemic agent

The antihyperglycaemic, antihyperlipidemic and antioxidant effects of wild pear (Pyrus biossieriana Buhse) leaf extract were investigated. An alloxan-induced rat model of hyperglycaemia was used to evaluate the antihyperglycaemic, antihyperlipidemic and antioxidant properties of the Pyrus biossieriana Buhse leaf extract. The arbutin content of Pyrus biossieriana Buhse leaves, measured by HPLC, was 12.6 dry weight percent. Administration of the Pyrus biossieriana Buhse leaf extract (at doses of 500 and 1000 mg/kg/day) significantly reduced the increase in serum glucose concentration seen in alloxan-treated hyperglycaemic rats. Both concentrations of the extract enhanced serum insulin levels compared to the control group. Both high and low doses of the extract decreased serum triacylglycerol (TG) and cholesterol (CHOL) levels as compared to controls. Serum antioxidant levels were significantly higher in rats treated with low (500 mg/kg/day) and high (1000 mg/kg/day) doses of Pyrus biossieriana Buhse extracts at 24, 48 and 72 h after alloxan injection than in control rats. This study demonstrated that Pyrus biossieriana Buhse leaf extract reduces blood glucose and lipid levels and increases antioxidant status in rats with alloxan-induced hyperglycaemia.     

Self-assembly electrode based on silver nanoparticle toward electrogenerated chemiluminescence analysis of glucose

Electrogenerated Chemiluminescence (ECL) involves applying a certain electric potential to a chemical reaction, resulting in the oxidation or reduction of the substance which reacts to produce light. We determined the amount of glucose by its reaction to glucose oxidase (GO _X ) on the surface of the proposed modified electrode, which results hydrogen peroxide (H₂O₂) as side product. After that the reactions between luminol and H₂O₂ under oxidizing conditions generate dependent light which can be used to analyze. In the current article at first we proposed a convenient method to obtaining a self-assembly modified electrode. A nano based modified glassy carbon (GC) electrode (Glucose oxidase/Ag nanoparticles/cysteamine (CA)/p-aminobenzene sulfonic acid/GC electrode) was prepared, and the ECL behavior of luminol in the presence of glucose was examined. Compared to the bare GC electrode, the modified electrode incorporating glucose oxidase significantly enhanced the response of the ECL biosensor to glucose due to the enhanced specificity of the modified surface to enzymatic reaction, and the sensitivity of the luminol ECL reaction. Under optimal conditions, the electrode was established to respond linearly to glucose in the concentration range 5.0×10^?7 to 8.0×10^?3 mol/L, and the detection limit was established to be a glucose concentration of 4.0×10^?8 mol/L.