邻苯三酚红多壁碳纳米管糊电极为传感器分析制药和生物样品中异丙基肾上腺素

异丙基肾上腺素(ISPR)是一种重要的邻苯二酚胺类药物,广泛用于治疗心脏疾病.然而,过量服用该药对人体非常危险.本文采用邻苯三酚红修饰多壁碳纳米管糊电极(PGRMMWCNTPE)制备了一种新型传感器,用于高灵敏度检测水溶液中的ISPR.采用计时电流法、循环伏安法和方波伏安法考察了PGRMMWCNTPE电极电催化氧化ISPR性能.通过伏安数据计算了ISPR氧化的催化反应速率常数、电子传递系数和扩散系数.在ISPR浓度0.8–570μmol/L范围内建立了线性标准曲线,检测限为0.47μmol/L ISPR.将该传感器用于尿液和药物样品中ISPR检测得到满意结果.     

Erratum to: The Electrochemical Study of Glucose Oxidase on Gold_Coated Magnetic Iron Oxide Nanoparticles

Journal of Analytical Chemistry - An Erratum to this paper has been published: https://doi.org/10.1134/S1061934822340019     

A comparative study in the prediction of thermal conductivity enhancement of nanofluids using ANN-MLP,ANN-RBF,ANFIS, and GMDH methods

In this work, four types of data mining methods, namely adaptive neuro-fuzzy inference system, artificial neural network—multilayer perceptron algorithm (ANN-MLP), artificial neural network—radial basis function algorithm (ANN-RBF), and group method of data handling (GMDH) have been used to predict the enhancement of the relative thermal conductivity of a wide range of nanofluids with different base fluids and nanoparticles. The total number of experimental data used in this work is 483 from 18 different nanofluids. The input parameters are thermal conductivity of base fluid and nanoparticles, volume fraction percent, the average size of nanoparticles, and temperature. Although the results showed that all four models are in relatively good agreement with experimental data, the ANFIS method is the best. The average absolute relative deviations (AARD%) between the experimental data and those of obtained using ANFIS, ANN-MLP, ANN-RBF, and GMDH methods were calculated as 2.7, 2.8, 4.2, and 4.3, respectively, for the test sets and as 1.1, 2.4, 3.9, and 4.5, respectively, for the training sets. Comparison between the predictions of the proposed ANN-MLP, ANN-RBF, ANFIS, and GMDH models and those predicted by traditional models, namely Maxwell and Bruggeman models showed that much better agreements can be obtained using the four models especially ANFIS model. Accordingly, the ANFIS method can able us to predict the relative thermal conductivity of new nanofluids in different conditions with good accuracy.

     

Extraction of nanofibers from polymer blends: A brief review

This review is about the naturally formed and intentionally produced nanofibrils or nanofibers (NFs) that have been extracted and utilized or expected to be used for special applications. The diameter of NFs ranges between a few to a few hundred nanometers. Methods to arrange synthetic NFs assembly in yarns or pads forms have been examined. High throughput productions, versatility of various thermoplastics, and less environmental pollution are the advantages of the methods of extraction, which seems to make it as an economical process. It can also be used for the polymers that are difficult to be converted to NFs by electrospinning. The process is challenging and scientifically fascinating to attract the investigators. There are many more polymers to be considered, and there are many more envisioned applications that have to be practiced in the future. A theoretical base is needed for the evaluation of the effects of polymer flow parameters on the extracted NFs properties.     

Fractional-Order Legendre Functions and Their Application to Solve Fractional Optimal Control of Systems Described by Integro-differential Equations

In this paper, we introduce a set of functions called fractional-order Legendre functions (FLFs) to obtain the numerical solution of optimal control problems subject to the linear and nonlinear fractional integro-differential equations. We consider the properties of these functions to construct the operational matrix of the fractional integration. Also, we achieved a general formulation for operational matrix of multiplication of these functions to solve the nonlinear problems for the first time. Then by using these matrices the mentioned fractional optimal control problem is reduced to a system of algebraic equations. In fact the functions of the problem are approximated by fractional-order Legendre functions with unknown coefficients in the constraint equations, performance index and conditions. Thus, a fractional optimal control problem converts to an optimization problem, which can then be solved numerically. The convergence of the method is discussed and finally, some numerical examples are presented to show the efficiency and accuracy of the method.     

Efficient Ce(NO3)3 x 6H2O-catalyzed solvent-free synthesis of 3,4-dihydropyrimidin-2(1H)-ones

Cerium(III) nitrate hexahydrate efficiently catalyzes the three-component Biginelli reaction under solvent-free conditions of an aldehyde, a beta-keto ester or beta-diketone and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones or -thiones in excellent yields.     

Performance of gold- and silver-coated magnetic nanoparticles as carriers for horseradish peroxidase

Noble metal nanoparticles have a great potential for biological studies. In the present work, gold-coated magnetic nanoparticles (GMNPs) and silver-coated magnetic nanoparticles (SMNPs) were synthesized at different conditions and used as carrier for the immobilization of horseradish peroxidase (HRP). UV/Vis spectroscopy and scanning electron micrograph were used for nanoparticles characterization. Also surface conductivity of MNPs, GMNPs and SMNPs was investigated by LCR meter to be 34.5, 78 and 57.4 μS, respectively. The change in secondary structure, enzymatic activity, direct electrochemistry and HRP bioactivity were studied in the presence of either GMNPs or SMNPs. The attached HRP on GMNPs and SMNPs showed quasi-reversible cyclic voltammograms with the formal potential of ?305 and ?269 and peak separation of 230 and 302 mV, respectively. In addition, HRP/GMNPs/Au and HRP/SMNPs/Au electrodes responded to hydrogen peroxide in the linear concentration range from 0.72 to 25.92 and 1.62 to 19.62 μM, respectively.     

Design and Synthesis of Nanosensor Based on CdSe Quantum Dots Functionalized with 8-Hydroxyquinoline: a Fluorescent Sensor for Detection of Al<Superscript>3+</Superscript> in Aqueous Solution

A novel nanosensor based on CdSe quantum dots (QDs) capped with 8-hydroxyqunoline (HQ) was developed for Al³⁺ ions determination in aqueous solutions. The method is based on the fluorescence enhancement of the HQ functionalized QDs in the presence of Al³⁺ ions, due to the strong interaction between Al³⁺ and HQ. Prepared nanosensor exhibited an acceptable selectivity and sensitivity for Al³⁺ ions in the presence of other metal ions. Plot of Log(I/I₀) against Log[Al³⁺] shows a good linearity in the range of 0.02–3.0 mM, and the method could be used for detection of Al³⁺ ions concentration in aqueous solutions.