The voltammetric behavior of isoniazid and hydrazine at an overoxidized polypyrrole modified glassy carbon electrode has been investigated. The obtained cyclic voltammograms showed that their oxidation peaks were overlapped and it is difficult to determine them individually from a mixture without separation. To overcome this limitation, a procedure was proposed for resolution of overlapped voltammetric signals from mixtures of isoniazid and hydrazine. In this procedure, genetic algorithm was used for the selection of potentials for partial least squares. A feed forward artificial neural network with back propagation error algorithm was used to process the nonlinear relationship between currents and concentrations of hydrazine and isoniazid. The proposed method was suitable for determination of isoniazid in pharmaceutical tablets and detection of hydrazine impurities in the same samples. 相似文献
An easy and mild way to construet 13-hydroxy-9,15-cyclo GA skeletons was reported and it could be used as a general protocol in the synthesis of GAs with this structure. 相似文献
The acoustic impedances of matching layers and their thicknesses are the most important and influential parameters in the performance of airborne ultrasonic transducers. In this paper, the optimum thicknesses of the matching layers of the narrow band transmitter ultrasonic transducer regarding transmission coefficient were determined by individual calculations using a genetic algorithm. The genetic algorithm was chosen because it is a powerful tool in the optimization domain. The results show that the permitted thickness variation is 0.0005% for one matching layer, and this value can be increased to 0.0031%, which corresponds to the permitted thickness variation for five matching layers. Approximately 55% enhancement in the transmission coefficient is theoretically possible, and 42% enhancement was observed experimentally when the genetic algorithm was applied to calculate the matching layer thicknesses in place of the quarter wavelength equation that is conventionally used for the determination of layer thickness. To verify our approach, the effect of the thickness variation on the transmission coefficient has been investigated experimentally for three, four and five matching layers. The experimental results displayed good agreement with the theoretical predictions. 相似文献
Computational models to predict the developmental toxicity of compounds are built on imbalanced datasets wherein the toxicants outnumber the non-toxicants. Consequently, the results are biased towards the majority class (toxicants). To overcome this problem and to obtain sensitive but also accurate classifiers, we followed an integrated approach wherein (i) Synthetic Minority Over Sampling (SMOTE) is used for re-sampling, (ii) genetic algorithm (GA) is used for variable selection and (iii) support vector machines (SVM) is used for model development. The best model, M3, has (i) sensitivity (SE) = 85.54% and specificity (SP) = 85.62% in leave-one-out validation, (ii) classification accuracy of the training set = 99.67%, (iii) classification accuracy of the test set = 92.59%; and (iv) sensitivity = 92.68, specificity = 92.31 on the test set. Consensus prediction based on models M3–M5 improved these percentages by 5% over M3. From the analysis of results we infer that data imbalance in toxicity studies can be effectively addressed by the application of re-sampling techniques. 相似文献
In this work, the determination of gallic acid was performed using surface-renewable carbon paste electrodes fabricated with multi-walled carbon nanotubes (MWCNT) and a mixture of N-octylpyridinium hexafluorophosphate (OPyPF6) ionic liquid with mineral oil (MO) as binder. This system shows remarkable amperometric sensor characteristics and promotes a better electronic transfer. An electroanalytical study of gallic acid shows a linear range from 4.98±0.25 to 74.1±2.2 μmol L−1, with R2=0.9958 and an experiment a limit of detection of 2.70±0.08 μmol L−1 (S/N=3), and a sensitivity of 0.029 μA μmol−1 L. 相似文献
A unique approach of developing a bar code version of lateral-flow enzymatic-based assay for the semi-quantification of hydrogen peroxide is described. The proposed assay system is mainly composed of a goat anti-mouse IgG-horseradish peroxidase conjugate (Gt anti-M IgG-HRP)-coated nitrocellulose (NC) membrane and a peroxidase substrate pad. Unlike the bar code immunochromatographic assay which depends on the stepwise capture of analyte, the principle of enzyme-based bar code lateral-flow assay is based on the different reaction time on successive lines due to the delay in 3,3′,5,5′-tetramethylbenzidine (TMB) release. Hydrogen peroxide (H2O2) acts as a limiting factor which controls the rate of the enzymatic conversion of TMB to blue color complex. The system expresses the concentration of H2O2 in micromole range as three distinct ladder bars in 9 min therefore without the need of any reading device. The major advantages of this assay are its easily readable result, and also its simplicity and low-cost in production offers a cheaper alternative for testing those expensive biosensors might not be available to the third world countries. By incorporating with H2O2-generating oxidoreductases, the assay can be further extended to detect a variety of analytes with clinical and environmental importance. Glucose was chosen to be the model analyte where the proposed system gave signal response at between 5 μM and 100 μM. 相似文献
We have developed a novel Hill-climbing genetic algorithm (GA) for simulation of protein folding. The program (written in C) builds a set of Cartesian points to represent an unfolded polypeptide’s backbone. The dihedral angles determining the chain’s configuration are stored in an array of chromosome structures that is copied and then mutated. The fitness of the mutated chain’s configuration is determined by its radius of gyration.
A four-helix bundle was used to optimise simulation conditions, and the program was compared with other, larger, genetic algorithms on a variety of structures. The program ran 50% faster than other GA programs. Overall, tests on 100 non-redundant structures gave comparable results to other genetic algorithms, with the Hill-climbing program running from between 20 and 50% faster. Examples including crambin, cytochrome c, cytochrome B and hemerythrin gave good secondary structure fits with overall alpha carbon atom rms deviations of between 5 and 5.6 Å with an optimised hydrophobic term in the fitness function. 相似文献