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41.
A simple, efficient, and new method has been developed for the synthesis of thiiranes from epoxides through a one-pot reaction of epoxides with diethyl phosphite in the presence of ammonium acetate or ammonium hydrogen carbonate/sulfur/ and acidic alumina under solvent-free conditions using microwave irradiation. 相似文献
42.
A validated kinetic spectrophotometric method has been developed for the determination of losartan potassium in pure and dosage forms. The method is based on oxidation of the losartan potassium with alkaline potassium permanganate at room temperature (25 ± 1 °C). The reaction is followed spectrophotometrically by measuring the increase in absorbance with time at 603 nm, and the initial rate, fixed time (at 12.0 min) and equilibrium time (at 90.0 min) methods are adopted for constructing the calibration graphs. All the calibration graphs are linear in the concentration range of 7.5–60.0 μg mL?1 and the calibration data resulted in the linear regression equations of n? = ?6.422 × 10?7 + 1.173 × 10?5 C, A =3.30 × 10?4 + 5.28 × 10?3 C and A = ?2.09 × 10?2 + 1.05 × 10?1 C for initial‐rate, fixed time and equilibrium time methods, respectively. The limits of detection for initial rate, fixed time and equilibrium time methods are 0.71, 0.21 and 0.19 μg mL?1, respectively. The activation parameters such as Ea, ΔH?, ΔS?, and ΔG? are also determined for the reaction and found to be 87.34 KJ mol?1, 84.86 KJ mol?1, 50.96 JK?1 mol?1 and ?15.10 KJ mol?1, respectively. The variables are optimized and the proposed methods are validated as per ICH guidelines. The method has been applied successfully to the estimation of losartan potassium in commercial tablets. The performance of the proposed methods was judged by calculating paired t‐ and F‐ values. The analytical results of the proposed methods when compared with those of the reference method show no significant difference in accuracy and precision and have acceptable bias. 相似文献
43.
44.
Seyedeh Hoda Jazayeri Amir Amiri-Yekta Salahadin Bahrami Hamid Gourabi Mohammad Hossein Sanati Mohammad Reza Khorramizadeh 《Applied biochemistry and biotechnology》2018,185(4):986-1003
The rapid growth of global biopharmaceutical market in the recent years has been a good indication of its significance in biotechnology industry. During a long period of time in recombinant protein production from 1980s, optimizations in both upstream and downstream processes were launched. In this regard, one of the most promising strategies is expression vector engineering technology based on incorporation of DNA opening elements found in the chromatin border regions of vectors as well as targeting gene integration. Along with these approaches, cell line engineering has revealed convenient outcomes in isolating high-producing clones. According to the fact that more than 50% of the approved therapeutic proteins is being manufactured in mammalian cell lines, in this review, we focus on several approaches and developments in vector and cell line engineering technologies in mammalian cell culture. 相似文献
45.
46.
Ayman Ben Mabrouk Hamid Kaddami Sami Boufi Fouad Erchiqui Alain Dufresne 《Cellulose (London, England)》2012,19(3):843-853
The microstructure and chemical composition of alfa (Stipa tenacissima) were investigated. The polysaccharide and lignin contents were around 70 and 20 wt%, respectively. From the bleached and
delignified fibers, two types of nanosized cellulosic particles were extracted, namely cellulose nanocrystals and microfibrillated
cellulose (MFC). The former correspond typically to the elementary crystallite units of the cellulose fibers, with a rod-like
morphology and an aspect ratio of about 20. The latter, mechanically disintegrated from oxidized bleached fibres, presents
an entangled fibrillar structure with widths in the range 5-20 nm. The reinforcing potential of the ensuing nanoparticles
was investigated by casting a mixture of acrylic latex and aqueous dispersion of cellulose nanoparticles. Thermo-mechanical
analysis revealed a huge enhancement of the stiffness above the glass transition of the matrix. Significant differences in
the mechanical reinforcing capability of the nanoparticles were reported. 相似文献
47.
M. H. Elnagdi M. A. Selim F. M. Abd El Latif S. Samia 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):1175-1182
5-Acetyl-2-cyanomethyl-4-methylthiazole, 2-aminothiazole, and 5-N-benzoylamino-1,3,4-thiadiazole-2-yl-acetonitrile react with acetone, and malononitrile derivatives in the presence of sulfur to yield the corresponding thiophene derivatives. Also, 4-furylmethylene-2-phenyl-2-oxazolin-5-ones react with thiophenol, and/or thionaphthol to give the thiolester derivatives in one-pot synthesis. The structures of the products were based on IR, 1 H NMR, and elemental analysis. 相似文献
48.
Hamid Reza Momenian Sousan Gholamrezaei Masoud Salavati-Niasari Behnam Pedram Farhang Mozaffar Davood Ghanbari 《Journal of Cluster Science》2013,24(4):1031-1042
In this work Mg(OH)2, Ca(OH)2, CaCO3, SrCO3 and BaCO3 nanoparticles were synthesized via a simple sonochemical reaction at room temperature. Nanoparticles were synthesized via a surfactant-free reaction solvent water. Nanostructures materials were characterized by scanning electron microscopy, X-ray diffraction and fourier transform infrared spectroscopy. The photocatalytic behavior of nanoparticles was evaluated using the degradation of a methyl orange aqueous solution under ultraviolet light irradiation. The results show that metal hydroxide and metal carbonate nanoparticles are promising materials with excellent performance in photocatalytic applications. 相似文献
49.
Afshan Siddiqui Kajal Singh Kanchan Lata Singh Shailendra Kumar Gupta Mohd Safi Ahmad U. N. Tripathi 《应用有机金属化学》2012,26(5):203-211
Mixed ligand complexes of Iron(III) with aspartic acid and 3(2′‐hydroxy phenyl)‐5‐(4′‐substituted phenyl) pyrazolines of type [Fe(C4O4NH6)2(C15H12N2OX)] and [Fe(C4O4NH6)(C15H12N2OX)2], where (C4O4NH6) = aspartate, (C15H12N2OX) = deprotonated 3(2′‐hydroxyphenyl)‐5‐(4′‐substituted phenyl) pyrazolines (X = H, CH3, OCH3, Cl), have been synthesized. These newly synthesized derivatives have been physicochemically characterized by elemental analysis (C, H, N, Cl and Fe), magnetic moment data, thermogravimetric analysis, molar conductance, cyclic voltammetry, spectral analysis (UV–visible, IR, far IR and fast atom bombardment mass spectrometry). Scanning electron microscopy, transmission electron microscopy and X‐ray powder diffraction studies have been carried out for powdered samples, which show nanometric particles of these derivatives. Antibacterial and antifungal potential of free pyrazoline and some iron(III) complexes have been evaluated. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
50.
In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation–Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability. 相似文献