Silver nanoparticles coat polyquercetin (Qu) and multi-walled carbon nanotube (MWCNT) complex films were prepared using an
electrochemical coupling strategy on platinum electrode (Ag/Qu/MWCNT/Ch/Pt). The new composite material was characterized
by means of field emission scanning electron microscopy, X-ray photoelectron spectroscopy spectra, X-ray diffraction, and
electrochemical techniques, which confirmed that polyquercetin plays an important role to obtain a great deal of uniformly
dispersed silver nanoparticles and MWCNT complex film with a diameter of 10 ± 6 nm. The resulting Ag/Qu/MWCNT/Ch/Pt electrode
shows a significant electrocatalysis for the redox of cysteine (CysH). The stripping chronopotentiometric analysis of CysH
has been successfully used with a satisfying effect. A linear range of 1 × 10−10 to 9 × 10−8 M was obtained with a detection limit of 3 × 10−11 M (3σ) and sensitivity of 35 μA/nM. The films were also robust, surviving up to 100 consecutive cyclic voltammograms and
sonication. 相似文献
Quartz crystal resonators (QCRs) with circular electrodes have been widely used for various liquid and gas sensing applications. In this work,quartz crystal resonators with elliptical electrodes were studied and tested for liquid property measurement. Mindlin’s theory was used to optimize the dimension and geometry of the electrodes and a 5-MHz QCR with minimum series resistance and without any spurious modes was obtained. A series of AT-cut QCRs with elliptical electrodes of different sizes were fabricated and their sensing performances were compared to devices with circular electrodes. The experimental result shows that the device with elliptical electrodes can obtain lower resonance impedance and a higher Q factor,which results in a better loading capability. Even though the sensitivities of devices with elliptical and circular electrodes are found to be similar,the sensor with elliptical electrodes has much higher resolution due to a better frequency stability. The study indicates that the performance of QCRs with elliptical electrodes is superior to that of traditional QCRs with circular electrodes. 相似文献
The electrochemical behaviors of melamine (MEL) were studied at paraffin-impregnated graphite electrode in PBS (pH 7.0) and 0.5 M H2SO4. Various methods including UV–vis thin-layer spectroelectrochemistry, infrared spectra (IR) and electrochemicatry have been performed to investigate the characteristics. In 0.1 M PBS (pH 7.0), MEL loses two electrons to form a dication, which couples head-to-head with a neutral molecule of MEL to form a dimer accompanying the production of azocompound, the dimer plays a role of a monomer in the following polymerization. In 0.5 M H2SO4, unstable MEL mostly hydrolyzes to form ammeline, ammelide, s-triazine-2,4,6-trion, and tricyanic acid, respectively; The hydrolysis could be accelerated by electrochemical method; Meanwhile, MEL associates tricyanic acid to give a plane molecule cake by hydrogen bonding. The spectra responses of MEL at 205 and 234 nm are linearly increasing in a same concentration range of 1.0 × 10−7–1.0 × 10−5 M in 0.5 M H2SO4 (determination limit, 1 × 10−8 and 3 × 10−8 (3σ)). The proposed method was successfully applied to the determination of MEL in real sample.
A series of 1-[(1,3,4-thiadiazol-2-yl)methyl]-1H-1,2,4-triazole derivatives were prepared and evaluated for their antifungal
activities. The chemical structures of these compounds were determined by means of elemental analyses, 1H NMR, and X-ray crystallography. Quantitative structure–activity relationship (QSAR) studies were performed on these compounds
using physicochemical parameters as independent parameters and antifungal activity as a dependent parameter, where antifungal
activity correlated best (r > 0.9) with hydrophobic parameters (π) and indicator (H). Moreover, the results are interpreted on the basis of a multiple regression model. The model has been internally and externally
validated. Furthermore, the domain of applicability which indicates the area of reliable predictions is defined. 相似文献
A series of 5-((1H-1, 2, 4-triazol-1-yl)methyl)-4H-1,2,4-triazole derivatives were prepared and evaluated for their antifungal
activities. Quantitative structure–activity relationship studies were performed on these compounds using physicochemical parameters
as independent parameters and antifungal activity as a dependent parameter, where antifungal activity correlated best (correlation
coefficient r > 0.8) with physicochemical parameters (Hammett’s constants σp, F) and van der Waals volume V1. Results are interpreted on the basis of multiple regression and cross-validation methodology. Furthermore, the domain of
applicability which indicates the area of reliable predictions is defined.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Chemical structures of A1–26 and A39; synthetic procedures; synthesis schemes; mps, yields, 1H NMR; elemental analyses of compounds and single crystal X-ray diffraction of compounds. 相似文献
Silver (Ag) nanoparticles were directly electrodeposited on multi-walled carbon nanotubes (MWCNT) in AgNO3/LiNO3 containing EDTA (ethylenediaminetetraacetic acid). The structure and nature of the resulting Ag/MWNT composite were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), and the distribution shape of Ag nanoparticles was found to be dependent on the presence of EDTA. The modified electrode showed excellent electrocatalytic activity to redox reaction of hydrogen peroxide and the mechanism of hydrogen peroxide was partly reversible procession with oxidation and reduction peaks at 0.77 and -0.83 V, respectively. The oxidation and reduction peak currents were linearly related to hydrogen peroxide concentration in the range of 1×10^-6-3×10^-4 and 1 ×10^-8-7× 10^-4 mol·L^-1 with correlation coefficients of 0.996 and 0.986, and 3s-detection limit of 9 × 10^-7 and 7 × 10^-9 mol·L^-1. 相似文献
Under an aid of ultrasonic, tetraoxalyl ethylenediamine melamine resin-coated multiwalled carbon nanotubes were prepared for Ni(II) sensing in aqueous solution. The processes involved the fabrication of tetraoxalyl ethylenediamine melamine resin by one pot way, the coating of tetraoxalyl ethylenediamine melamine resin at multiwalled carbon nanotubes (MWCNTs), and the determination of Ni(II). The present materials were carefully examined by Fourier transform infrared spectroscopy, field emission scanning electron microscope, and electrochemistry techniques. A great deal of amorphous microsphere could be observed for tetraoxalyl ethylenediamine melamine resin with an average diameter of 1.2 μm, and MTE could evenly adhere at the surface of MWCNTs by the ultrasonic. Tetraoxalyl ethylenediamine melamine resin-coated multiwalled carbon nanotube-modified paraffin-impregnated graphite electrode was successfully used for the determination of Ni(II) by differential pulse adsorptive anodic stripping voltammetry. The current responses (?0.3 V) were linearly increased depending on the concentration from 1?×?10?11 to 3?×?10?10 M (i (μA)?=?11.1?+?7.9 c (1?×?10?12 M); R?=?0.9901, 3σ?=?7?×?10?12 M). 相似文献