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181.
Complex and elegant protein patterns in rosette, scallop, Chinese arrow and dendrite shapes at macroscopic length scales were
prepared using salt-induced molecular self-assembly and droplet evaporation methods. The direct visual observation method
using fluorescence microscopy was adopted to characterize the formation of these protein patterns in situ. Further studies from an optical interferometric profiler have shown that both rosette and scalloped protein patterns are
hierarchical structures of concentric rings consisting of many prism-like columnar stacks, with each of the stack having thousands
of protein molecules. Systematic experimental studies were performed to investigate the influence of salt concentration, protein
concentration and evaporation rate on the morphologies of protein patterns. Upon the analysis of the representative fluorescent
microscope images some theoretical explanations, based on Deegan’s theory on the “coffee ring” effect and the dynamic self-assembly
mechanism, were proposed to illustrate the dynamics for the formation of different protein patterns. Two different evaporation
modes have been found: edge-enhanced evaporation for low salt concentration solutions, i.e., the higher evaporation rate exists at the edge of the droplet; center-enhanced evaporation for high salt concentration solutions,
in which faster evaporation occurs at the droplet center consisting of a lot of crystallized salts. 相似文献
182.
In the present work molecularly imprinted sol-gel tablet (MIP-Tablet) was prepared. The MIP-sol-gel was prepared as a thin layer on polyethylene material in a tablet form. Methadone-d9 was selected as the template and 3-(propylmethacrylate)-trimethoxysilane was used as precursor. MIP-Tablet was applied for micro-solid phase extraction (μ-SPE). The MIP-Tablet was used for the determination of methadone in human plasma samples utilizing liquid chromatography-tandem mass spectrometry; and each tablet could be used twenty times. The extraction time was 10 min while desorption time was 6 min. Factors affecting the extraction efficiency such as desorption solvents, sample pH, salt addition, extraction time, desorption time and adsorption capacity were investigated. The calibration curves were obtained within the range of 5–5000 ng/mL using methadone in human plasma samples. The coefficients of determination (r2) values were ≥0.999 for all runs and the extraction recovery was >80%. The accuracy values for quality control samples varied from +3.6 to +9.7% and the inter-day precision (RSD %) values were ranged from 5.0 to 8.0%. The limit of detection was 1.0 ng/mL and the lower limit of quantification was 5 ng/mL utilizing methadone in human plasma samples. 相似文献
183.
Mohamed Laabd Lahoucine Atourki Hafsa Chafai Mohammed Bazzaoui Maria Elamine 《Journal of Dispersion Science and Technology》2017,38(9):1227-1233
This study sheds light on the removal of humic acid by-products (trimellitic and pyromellitic acids; TMA and PMA, respectively) from aqueous solution using conducting polypyrrole (PPy) as an effective adsorbent. The effects of experimental factors including contact time, solution pH, initial concentration, adsorbent dose, and temperature were systematically investigated. The pseudo-second-order kinetic model provides the best correlation with adsorption experimental data. The equilibrium adsorption was well described by the Langmuir model with maximum mono-layer adsorption capacities of 47.62 and 71.43?mg?g?1 for TMA and PMA, respectively. The analysis of thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic in nature. In addition, we investigated the adsorption mechanism using the density functional theory (DFT) calculations. The TMA and PMA were physisorbed on the PPy surface through the formation of hydrogen bonds between carboxylic groups of adsorbate molecules and the amino group of the adsorbent. The calculated theoretical data were in good agreement with experiments. 相似文献
184.
185.
Tarak Saied Nourchaine Jelaiel Mohamed Lotfi Efrit Yves Fort Corinne Comoy 《Tetrahedron》2017,73(11):1489-1494
We report herein a short and efficient synthesis of benz[e][1,2,4]- or [d][1,2,6]oxadiazepines and benzo[f][1,3,5]triazocines from easily prepared N-aryl iminoesters. The strategy involves a bis-nucleophile reagent (hydroxylamine or guanidine) that promotes a one-step ring closure from the starting functionalized iminoesters. 相似文献
186.
187.
Noureddine Raouafi Khaled Boujlel Mohamed Lamine BenKhoud 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1387-1395
The condensation of N1-benzimidazolyl amidines 1 with tris(dimethy- lamino)phosphine leads to the corresponding [1,2a]Benzimidazolo-1,3,5,2-triazaphosphorines 3 . The N2-phosphoroamidine intermediates 2′ are isolated and yielded the corresponding cyclic compounds 4 upon heating. The oxidation by sulfur of the compounds 3 gives the thiooxide derivatives 4 . The structure of these compounds is unambiguously confirmed by IR, 1H, 31P, and 13C NMR spectroscopy and by MS for some products. 相似文献
188.
Marie-Christine Brochier Salon Mohamed Naceur Belgacem 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):240-254
Abstract The hydrolysis kinetics of 14 alkoxy silane coupling agents were carried out in an ethanol:water 80:20 (w/w) solution under acidic conditions and were monitored by 1H, 13C, and 29Si NMR spectroscopy. Acidic conditions were selected in order to enhance the silanol formation and to slow down the self-condensation between the resulting hydrolysed silanol groups. In situ 29Si NMR spectroscopy allowed the determination of the intermediate species as a function of the reaction time. Thus, the following silane coupling agents were studied: 3-methacryloxypropyl trimethoxy silane (MPMS), 3-mercaptopropyl trimethoxy silane (MRPMS), 3-cyanopropyl triethoxy silane (CPES), triethoxy vinyl silane (VES), trimethoxy (2-phenylethyl) silane (PEMS), octyl triethoxy silane (OES), trimethoxy (7-octen-1-yl) silane (OEMS), 3-aminopropyl triethoxy silane (APES), 3-aminopropyl trimethoxy silane (APMS), 3-(2-aminoethylamino)propyl trimethoxy silane, (DAMS), 3-[2-(2-aminoethylamino)-ethylamino]propyl trimethoxy silane (TAMS), 4-amino-3,3-dibutyl trimethoxy silane (ADBMS), trimethoxy [3-(phenylamino)propyl] silane (PAPMS), and triethoxy-3-(2-imidazolin-1-yl) propyl silane (IZPES). A parameter quantifying the grafting potentiality of each silane coupling agent towards OH-rich solid substrates (such as cellulose) was established as a function of the nature of the alkoxy groups (methoxy or ethoxy), as well as that of the fourth substituent (vinyl, aminopropyl, etc.) of the silane studied. GRAPHICAL ABSTRACT 相似文献
189.
Nadia R. Mohamed 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):683-691
N-(chloro-furan-2-yl)methylene-N′-(4-nitrophenyl)hydrazone (I) reacted with triethylphosphite to produce the phosphonate derivative III. The tetrazine derivative VI was produced by the interaction of I with diethyl-phosphite. Hydrazonoyl azide derivatives VIIIa–c reacted with triphenyl phosphine to form the iminophosphorane derivatives Xa–c. On the other hand, the azide derivative VIIIc reacted with the phosphonium ylide XI to form the 1,2,3-triazole adduct XIII. The reaction of triethyl phosphite with Shiff's bases XIVa–c yielded the corresponding phosphonates XVa–c. The structures of the newly prepared compounds were confirmed with the analytical and spectroscopic evidences. 相似文献
190.
Adel Mahroug Mohamed Belhouchet Annie Hémon-Ribaud Tahar Mhiri 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2332-2340
Abstract A new adduct 3-ammoniumphenyl sulfone dihydrogenphosphate phosphoric acid, [C12H14N2O2S](H2PO4)2H3PO4, has been synthesized by slow evaporation at room temperature using 3-aminophenyl sulfone as the structure-directing agent. The structure, determined by single-crystal X-ray diffraction at 293 K, can be described as inorganic layers built by H2PO4 ? groups and H3PO4 molecules, parallel to the (a, c) planes at y = 0.5, between which molecules of the organic group [C12H14N2O2S]2+ are inserted. In this atomic arrangement, hydrogen bonds and van der Waals interactions between the different species play an important role in the tri-dimensional network cohesion. Solid-state 13C and 31P MAS NMR spectroscopies are in agreement with the X-ray structure. [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Tables S1 and S2. Figures S1 and S2.] GRAPHICAL ABSTRACT 相似文献