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231.
Mohamed H. Taha Samir A. Abdel Maksoud Mohsen M. Ali Ahmed M. A. El Naggar Asmaa S. Morshedy Amir A. Elzoghby 《International journal of environmental analytical chemistry》2013,93(12):1211-1234
ABSTRACTThis study reports the removal of organic matters from phosphoric acid using waste-produced bio-charcoal structures. Particularly, the freshly made bio-char species via pyrolysis and two sub-driven acids activated charcoals were applied during the removal process. The treated charcoal with hydrochloric and nitric acids had attained a higher adsorption rate for organic matters than that of the non-treated one. Removal percentages of 70% and 60% were, respectively, attained by acid-modified chars. The kinetics of the adsorption process was fitted via pseudo-first/second-order and Morris–Weber models. The thermodynamic parameters of the presented sorption process indicate that organic matter removal has been endothermic, physical and spontaneous. 相似文献
232.
Amir Waseem Mohammad Yaqoob Masood Ahmed Siddiqui 《International journal of environmental analytical chemistry》2013,93(12):825-832
A flow-injection procedure is described for the determination of carbaryl based on its inhibition effect on luminol-cobalt(II) chemiluminescence reaction in alkaline medium in the presence of hydrogen peroxide. The calibration data over the range 5.0?×?10?7 to 20?×?10?6?M give a correlation coefficient (r 2) of 0.9972 with relative standard deviations (RSD; n?=?4) in the range of 1.0–2.1% with a limit of detection (3?×?blank noise) of 2.37?×?10?7?M for carbaryl. The sample throughput was 120?h?1. The effects of some carbamates, anions, and cations were studied on luminol CL system for carbaryl determination. The proposed method has been applied to determine carbaryl in natural waters. 相似文献
233.
Treatment of the 1,6‐anhydrosugar epoxide 5 with a cyano‐Gilman cuprate [(CuCN (6 eq.), MeLi (12 eq.)] surprisingly led to the open chain rearranged (2S,3R)‐1,2‐dihydroxy‐3,6‐dimethylheptan‐4‐one (7), structurally confirmed by conversion to the corresponding diacetate 8. Another unusual reaction was found by hydrogenation of the 2‐tosyl‐1‐bromosugar 11, leading in one operation to the twofold deoxygenated chiral pyran derivative 14. This procedure might prove to be useful in the rapid deoxygenation of sugar derivatives. 相似文献
234.
A. S. Fouda T. F. Alsawy E. S. Ahmed B. S. Abou-elmagd 《Research on Chemical Intermediates》2013,39(6):2641-2661
The inhibitive effect of 2-cyano-3-hydroxy-4(Ar)-5-anilino thiophene derivatives on the corrosion of 304 stainless steel (SS) in 3 M HCl solution has been investigated by weight loss, galvanostatic polarization techniques, and potentiodynamic anodic polarization in 3.5 % NaCl. The results indicate that these compounds act as inhibitors retarding the anodic and cathodic corrosion reactions. The presence of inhibitors does not change the mechanism of either hydrogen evolution reaction or SS dissolution. The activation energy and some thermodynamic parameters are calculated and discussed. These compounds are mixed-type inhibitors in the acid solution, and their adsorption on the SS surface is found to obey the Temkin adsorption isotherm. The results suggest that the percentage inhibition of these thiophene derivatives increases with increasing inhibitor concentration and decreases with increasing temperature. The synergistic parameter (S) was calculated and found to have a value greater than unity, indicating that the enhanced inhibition efficiency caused by the addition of I?, SCN?, and Br? is only due to a synergistic effect. The relationship between molecular structure and inhibition efficiency was elucidated by quantum-chemical calculations using semi-empirical self-consistent field (SCF) methods. 相似文献
235.
Dr. Matthieu Fonvielle Dénia Mellal Delphine Patin Maxime Lecerf Dr. Didier Blanot Dr. Ahmed Bouhss Dr. Marco Santarem Dr. Dominique Mengin‐Lecreulx Dr. Matthieu Sollogoub Dr. Michel Arthur Dr. Mélanie Ethève‐Quelquejeu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(4):1357-1363
Peptidyl–RNA conjugates have various applications in studying the ribosome and enzymes participating in tRNA‐dependent pathways such as Fem transferases in peptidoglycan synthesis. Herein a convergent synthesis of peptidyl–RNAs based on Huisgen–Sharpless cycloaddition for the final ligation step is developed. Azides and alkynes are introduced into tRNA and UDP‐MurNAc‐pentapeptide, respectively. Synthesis of 2′‐azido RNA helix starts from 2′‐azido‐2′‐deoxyadenosine that is coupled to deoxycytidine by phosphoramidite chemistry. The resulting dinucleotide is deprotected and ligated to a 22‐nt RNA helix mimicking the acceptor arm of Ala‐tRNAAla by T4 RNA ligase. For alkyne UDP‐MurNAc‐pentapeptide, meso‐cystine is enzymatically incorporated into the peptidoglycan precursor and reduced, and L ‐Cys is converted to dehydroalanine with O‐(mesitylenesulfonyl)hydroxylamine. Reaction of but‐3‐yne‐1‐thiol with dehydroalanine affords the alkyne‐containing UDP‐MurNAc‐pentapeptide. The CuI‐catalyzed azide alkyne cycloaddition reaction in the presence of tris[(1‐hydroxypropyl‐1H‐1,2,3‐triazol‐4‐yl)methyl]amine provided the peptidyl‐RNA conjugate, which was tested as an inhibitor of non‐ribosomal FemXWv aminoacyl transferase. The bi‐substrate analogue was found to inhibit FemXWv with an IC50 of (89±9) pM , as both moieties of the peptidyl–RNA conjugate contribute to high‐affinity binding. 相似文献
236.
Ahmed Hanan A. Moussa Bahia A. El-Bagary Ramzia I. Darwish Mahmoud N. 《平面色谱法杂志一现代薄层色谱法》2013,26(1):56-61
JPC – Journal of Planar Chromatography – Modern TLC - Three selective, precise, and accurate methods were developed and validated for the simultaneous determination of ofloxacin and... 相似文献
237.
Raymond J. Huntley Mahender GurramJoel R. Walker David M. JenkinsEmmanuel J. Robé Feryan Ahmed 《Tetrahedron letters》2014
A new synthetic method has been developed for the synthesis of 2,4,5-substituted isoindolinones by means of intramolecular inverse-electron demand Diels–Alder cycloaddition reactions of substituted pyridazines. By taking advantage of the inherent reactivity of an intermediate chloropyridazine, a diverse set of analogues were prepared from common reagents and intermediates. 相似文献
238.
Ahmed M. Metwaly Frank R. Fronczek Guoyi Ma Hazem A. Kadry Atef A. El-Hela Abd-Elsalam I. Mohammad Stephen J. Cutler Samir A. Ross 《Tetrahedron letters》2014
Four new (1–4) and two known (5 and 6) α-pyrone derivatives have been isolated from Alternaria phragmospora, an endophytic fungus from Vinca rosea, leaves. The isolated compounds were chemically identified to be 5-butyl-4-methoxy-6-methyl-2H-pyran-2-one (1), 5-butyl-6-(hydroxymethyl)-4-methoxy-2H-pyran-2-one (2), 5-(1-hydroxybutyl)-4-methoxy-6-methyl-2H-pyran-2-one (3), 4-methoxy-6-methyl-5-(3-oxobutyl)-2H-pyran-2-one (4), 5-(2-hydroxyethyl)-4-methoxy-6-methyl-2H-pyran-2-one (5), and 5-[(2E)-but-2-en-1-yl]-4-methoxy-6-methyl-2H-pyran-2-one (6). Compounds 2 and 4 showed moderate antileukemic activities against HL60 cells with IC50 values of 2.2 and 0.9 μM and against K562 cells with IC50 values of 4.5 and 1.5 μM, respectively. 相似文献
239.
Sn(IV)Cl4 catalyst provided a rapid and efficient deprotection method for the phenolic THP and MOM ethers and sequel intramolecular Friedel–Crafts alkylation reaction of THP and MOM protected chalcone epoxides under mild conditions. The reaction took 2–3 min to give the products in excellent yield (90–98%) at 0 °C without affecting the other functional groups. 相似文献
240.
Ahmed M. Donia Asem A. Atia Hassnaa M. Abd El-Latif 《Journal of Dispersion Science and Technology》2014,35(3):380-389
Cellulose was modified via chlorination using phosphorous oxychloride followed by functionalization with amine and thiol moieties. The obtained modified cellulose samples were investigated by means of FTIR, TGA, TEM, and nitrogen-adsorption surface area (BET). The BET measurements showed a remarkable increase in the surface area of Cell-N-S (477.7 m2/g) and Cell-N (706 m2/g). The resins gave an uptake capacities of 38 and 7.2mmol/g for Cell-N-S and Cell-N, respectively toward Hg(II) from its solutions. These values are considered much better compared with other reported resins. Regeneration of the resins was achieved effectively using acidified thiourea. 相似文献