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181.
Noura Hemdan Abou‐Taleb Nahed Mahmoud El‐Enany Dina Tawfik El‐Sherbiny Hussein Ibrahim El‐Subbagh 《Journal of separation science》2020,43(6):1195-1202
In this study, an eco‐friendly fast simple method was developed for simultaneous determination of norfloxacin and tinidazole based on thin‐layer chromatography and image‐processing analysis. The binary mixture was separated using reversed phase ‐ thin layer chromatography plates and 30% trifluoroacetic acid only as mobile phase. Mobile phase composition was optimized using Taguchi orthogonal array and Derringer's desirability function. The plates were viewed under UV lamp and photographed by iPhone camera followed by image processing with Fiji software using integrated density as the measured response. As decreasing illumination increases the sensitivity of the method, this method was applied on two different ranges for each drug. The first one was 0.6–6.0 and 0.9–9.0 µg/spot for norfloxacin and tinidazole, respectively measured on the original image with normal illumination. The second one was measured after decreasing the illumination of the captured images at 0.06–0.60 and 0.09–0.90 µg/spot for norfloxacin and tinidazole, respectively. The proposed method was successfully applied for the determination of both drugs in tablets dosage form without interference from the commonly encountered excipients. Analytical Eco‐Scale was used to evaluate the greenness profile of the proposed method and it was found to be excellent green analytical method. 相似文献
182.
Dina Mostafa Mahmoud A. Zaky Ramy M. Hafez Ahmed S. Hendy Mohamed A. Abdelkawy Ahmed A. Aldraiweesh 《Mathematical Methods in the Applied Sciences》2023,46(1):656-674
We present a class of orthogonal functions on infinite domain based on Jacobi polynomials. These functions are generated by applying a tanh transformation to Jacobi polynomials. We construct interpolation and projection error estimates using weighted pseudo-derivatives tailored to the involved mapping. Then, using the nodes of the newly introduced tanh Jacobi functions, we develop an efficient spectral tanh Jacobi collocation method for the numerical simulation of nonlinear Schrödinger equations on the infinite domain without using artificial boundary conditions. The applicability and accuracy of the solution method are demonstrated by two numerical examples for solving the nonlinear Schrödinger equation and the nonlinear Ginzburg–Landau equation. 相似文献
183.
Let Π be a projective plane of order n in Lenz–Barlotti class I.4, and assume that n is a multiple of 3. Then either n=3 or n is a multiple of 9. 相似文献
184.
Eman M. H. Abbas Kamelia M. Amin Wageeh S. El-Hamouly Dina H. Dawood Mohamed M. Abdalla 《Research on Chemical Intermediates》2014,40(2):847-869
A series of new compounds bearing a 1,3-benzothiazol-2-one nucleus have been synthesized using 5,6-dimethyl-3-(2-oxo-propyl)-1,3-benzothiazol-2-one (1) as a key starting compound. The reaction of 1 with some nucleophilic compounds led to the formation of compounds 2, 3, 4, 5a, b, 6 and 7a, b. The thiosemicarbazone derivatives 7a, b were treated with a number of halo ketones to produce the new heterocyclic compounds 9–13, while their reaction with acid anhydrides led to the formation of the derivatives 14 and 15. Also, compound 1 was condensed with different aromatic aldehydes to afford the corresponding chalcones 18–22. The structures of all the novel compounds have been determined by analytical and spectral data. Some of the compounds were selected to be evaluated as anti-inflammatory and analgesic agents. 相似文献
185.
Dina V. Hingorani Dr. Byunghee Yoo Adam S. Bernstein Dr. Mark D. Pagel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9840-9850
This review focuses on exogenous magnetic resonance imaging (MRI) contrast agents that are responsive to enzyme activity. Enzymes can catalyze a change in water access, rotational tumbling time, the proximity of a 19F‐labeled ligand, the aggregation state, the proton chemical‐exchange rate between the agent and water, or the chemical shift of 19F, 31P, 13C or a labile 1H of an agent, all of which can be used to detect enzyme activity. The variety of agents attests to the creativity in developing enzyme‐responsive MRI contrast agents. 相似文献
186.
Multiobjective optimization strategy based on desirability functions used for the microemulsion liquid chromatographic separation and quantification of norfloxacin and tinidazole in plasma and formulations
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Noura Hemdan Abou‐Taleb Dalia Rashad El‐Wasseef Dina Tawfik El‐Sherbiny Saadia Mohamed El‐Ashry 《Journal of separation science》2015,38(6):901-908
The aim of the present study was to optimize a microemulsion liquid chromatography method for the simultaneous determination of norfloxacin and tinidazole binary mixture using a chemometric protocol. Optimization experiments were conducted through a process of screening and optimization. A 27‐4 fractional factorial design was used as screening design. While the location of optimum conditions was established by applying Derringer's desirability function. The optimal mobile phase composition was predicted to be: 3.5% w/v SDS, 10.03% v/v 1‐propanol, 0.5% v/v 1‐octanol, and 0.3% triethylamine in 0.02 M phosphoric acid at pH 6.5. The mobile phase was delivered isocratically at a flow rate of 1 mL/min with UV detection at 290 nm. Tinidazole and norfloxacin were eluted with retention times of 1.8 and 5.8 min, respectively. The calibration plots displayed good linear relationships in the concentration ranges of 0.5–50 and 0.75–75 μg/mL for norfloxacin and tinidazole, respectively. The method was successfully applied for determination of both drugs in pharmaceutical dosage forms and real human plasma. Where the accuracy was proved by the low values of % error and high values of recovery, also the relative standard deviation for the results did not exceed 1.5%, proving the precision of the method. 相似文献
187.
Dina Boyarskaya Margarita Avdontceva Tatiana Chulkova 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(2):155-158
Acidic hydrogen containing 2‐isocyano‐4‐methylphenyl diphenylacetate, C22H17NO2, (I), was synthesized by the base‐promoted reaction between 5‐methylbenzoxazole and diphenylacetyl chloride. Achiral (I) crystallizes in the chiral P212121 space group. The C[triple‐bond]N bond length is 1.164 (2) Å and the angle between the OCO and 2‐isocyano‐4‐methylphenyl planes is 69.10 (16)°. Molecules are linked via C=O...Hphenyl and bifurcated N[triple‐bond]C...Hphenyl/N[triple‐bond]C...Hmethine hydrogen bonds, forming one‐dimensional arrays. 相似文献
188.
189.
Antnio M. dA. Rocha Gonsalves M. Elisa S. Serra Dina Murtinho 《Journal of molecular catalysis. A, Chemical》2006,250(1-2):104-113
A series of pyrrolidine-based β-amino alcohols derived from malic acid, citramalic acid and pantolactone with primary amines was prepared and their activity as chiral ligands in the enantioselective alkylation of benzaldehyde using diethylzinc was studied. 相似文献
190.
Sergey Pasechnik Ildar Nasibullayev Dina Shmeliova Valentin Tsvetkov Liu Zhijian Vladimir Chigrinov 《Liquid crystals》2006,33(10):1153-1165
We present an experimental study of thin liquid crystal (LC) layers under the action of a harmonically varied pressure gradient. Optical measurements were performed to register the linear oscillations of a nematic director related to homeotropic and homeoplanar (hybrid) initial states. In the latter case one of the inner surfaces of the rectangular channels was treated by ultraviolet light to provide a relatively weak planar anchoring. The optical response of hybrid and homeotropic LC cells under an oscillating pressure gradient was investigated in relation to on the amplitude and frequency of the pressure gradient. A hydrodynamic model is developed taking into account the LC polar anchoring strength and the surface viscosity responsible for a fast LC surface dynamics. Our estimates show that the thickness of the boundary layer corresponding to the surface viscosity does not exceed 10-6 m, and further experiments are needed with thinner LC cells and higher frequency oscillations to achieve a more precise value. An oscillating Poiseuille flow in the hybrid cell was found to be useful for characterizing elastic and viscous properties of a weakly anchoring LC surface layer in a fast surface dynamic process. 相似文献