Journal of Analytical Chemistry - In this article, a new spectrofluorometric method was developed for the determination of methamphetamine based on a turn-on luminescence response of captopril... 相似文献
The multiple lump solutions method is employed for the purpose of obtaining multiple soliton solutions for the generalized Bogoyavlensky-Konopelchenko(BK) equation. The solutions obtained contain first-order, second-order, and third-order wave solutions. At the critical point,the second-order derivative and Hessian matrix for only one point is investigated, and the lump solution has one maximum value. He's semi-inverse variational principle(SIVP) is also used for the generalized BK equation. Three major cases are studied, based on two different ansatzes using the SIVP. The physical phenomena of the multiple soliton solutions thus obtained are then analyzed and demonstrated in the figures below, using a selection of suitable parameter values.This method should prove extremely useful for further studies of attractive physical phenomena in the fields of heat transfer, fluid dynamics, etc. 相似文献
The synthesis, characterization, and evaluation of a Schiff base Cu (II) complex functionalized boehmite nanoparticles (Cu-complex-boehmite) as a new catalyst for oxidation of sulfides and thiols in the presence of hydrogen peroxide with complete selectivity and high conversion under solvent-free and mild reaction conditions were reported. Characterization of the catalyst was performed with various physicochemical methods. This effective catalyst was evaluated in terms of activity and reusability. It indicated high catalytic activity, good recoverability and reusability, and supplied the corresponding products in high yields and short reaction times. In addition, it shows notable advantages such as simplicity of operation, heterogeneous nature, easy work up, and it could be used at least eight times with no significant loss of its activity. 相似文献
This research represents a novel detection method of acetone level in the exhaled breath samples (RH=88 %) based on polypyrrole/tungsten oxide (PPy/WO3) nanocomposite sensor. The PPy/WO3 sensor was fabricated by the deposition of nanocomposite on/between interdigitated electrodes (IDEs) through electrospray coating and was then characterized by FE-SEM imaging. In this detection method, the coulometric signal of the sensor was calculated using Fast Fourier Continuous Cyclic Voltammetry (FFTCCV), where cyclic voltammetry (CV) was applied to the sensor in the defined potential rang and then charge changes of the sensor was obtained by integration of the current in all scanned potential ranges. FFTCCV method enhances the sensitivity of the sensor when exposed to the gas mixtures containing acetone. In addition to its fast coulometric response time (≤5 s) in the two linear ranges of 0.7–2.8 ppm and 2.8–28.2 ppm (R2=0.99), FFTCCV method provides the low detection limit of 70 ppb, and high sensitivity toward acetone at the optimum values of the parameters. The fabricated sensor showed great selectivity toward acetone when exposed to humid air and some exhaled gas like carbon dioxide, ammonia, methanol, ethanol and alkyl amines. The results were very satisfying as the sensor was capable to detect different acetone levels in human exhaled breath as non-invasive diagnosis of diabetes with a good correlation (R2≃0.9) to the routine blood sugar test taken by different commercial glucometers results. 相似文献
A reusable and cost-effective magnetic graphite oxide (Fe3O4NPs@GO) nanocomposite was fabricated and applied for pre-purification of paclitaxel from leaf-derived crude extract of Taxus baccata. Furthermore, the potential roles of three crucial criteria (i.e., adsorbent dosage, sorption temperature and agitation/shaking power) on the two responses [i.e., efficiency of plant pigments removal (EPPR) and efficiency of taxol purity (ETP)] were examined and simultaneously optimized through response surface methodology. The nanocomposite was accurately characterized using TEM, AFM, BET, FT-IR, Raman and VSM. Moreover, for both proposed second-degree polynomial regression models, highly significant correlations were achieved between the experimental and predicted data (p < 0.0001). Meanwhile, the optimum conditions to simultaneously acquire the maximum EPPR (94.0 %) and ETP (11.4 %) were recorded as adsorbent dosage of 37.7 g L−1, sorption temperature of 30.7 °C and agitation power of 153.1 rpm; and the predictive results were confirmed using experimental rechecking survey. Interestingly, upon five consecutive treatments, the nanocomposite still exhibited substantial potency in eliminating large amounts of plant pigments and impurities (up to 90 %), without significant reduction on sorption capacity and magnetism thereof. Our results demonstrated that the current nanocomposite, as SPE sorbent for MSPE, could be a simple, fast and reusable approach for HPLC-based purification studies of paclitaxel, and probably other plant secondary metabolites.