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61.
Selma Mededovic Thagard Gunnar R. Stratton Mikhail Vasilev Patrick Conlon Douglas Bohl 《Plasma Chemistry and Plasma Processing》2018,38(4):719-741
In this work, particle image velocimetry has been used to visualize and quantify plasma-induced flow fields in liquid water. Experiments were performed in a rod-plane plasma reactor with a thin wire electrode suspended above the surface of the liquid in argon gas and a grounded plate immersed in the liquid. The velocity field has been quantified for two types of solutions: (1) aqueous NaCl solutions of varying solution conductivities and discharge frequencies and (2) aqueous NaCl solutions containing varying concentrations of the following four organic compounds: rhodamine B dye, caffeine, fluoxetine, and perfluorooctanoic acid. Results show that in neat water and aqueous caffeine solutions, the liquid is “pulled” along by the interaction of the gas molecules with the liquid molecules at the free surface and thus the direction of the liquid flow is in the direction of the gas phase flow (i.e., away from the discharge location). However, the flow was reversed (i.e., towards the discharge) for those solutions with strong surfactants such as perfluorooctanoic acid. The magnitude of the reversal depended on the initial concentration of the compound and for some compounds as time progressed the reversed flow pattern weakened and then reverted to a normal flow pattern. To determine the most likely cause of these flow reversals, a simple numerical model of the velocity field was developed to estimate relative contributions of various flow inducing mechanisms. The model indicates that in the presence of surfactants, Marangoni stresses are responsible for inducing the flow in the liquid. 相似文献
62.
Microwave‐assisted solvent‐free synthesis of novel benzoxazines: A faster and environmentally friendly route to the development of bio‐based thermosetting resins
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Jéssica R. Oliveira Lloyd R. V. Kotzebue Francisco W. M. Ribeiro Beatriz C. Mota Dávila Zampieri Selma E. Mazzetto Hatsuo Ishida Diego Lomonaco 《Journal of polymer science. Part A, Polymer chemistry》2017,55(21):3534-3544
Microwave‐assisted organic synthesis (MAOS) is a well‐established technique that has been used in the enhancement of chemical reactions. Here, the versatility of MAOS is explored describing an environmentally friendly one‐pot route to novel bio‐based benzoxazines under solvent‐free conditions. The lignin derivative, guaiacol, along with paraformaldehyde and different conjugated and nonconjugated amines are successfully fused into guaiacol‐derived 3,4‐dihydro‐2H‐1,3‐benzoxazines. The reactions conducted under microwave irradiation are completed much faster than those under traditional heating, reducing the reaction time from hours to only 6 min, with good yields. The chemical structures of novel benzoxazines are confirmed by 1H and 13C NMR spectroscopy, FTIR, and HR‐MS. The thermal behavior of the resins are evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), showing that these polymers have good thermal stability and wide processing‐window, with onset temperature of polymerization above 230 °C. These results indicate dramatic improvement over the traditional methodologies for the production of this class of resins, which are usually obtained by time‐consuming procedures and in the presence of toxic solvents. Therefore, MAOS can be considered a green and efficient strategy for the synthesis of eco‐friendly benzoxazines. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3534–3544 相似文献
63.
Horacio J. Salavagione Diego Cazorla-Amors Selma Tidjane Mohammed Belbachir Abdelghani Benyoucef Emilia Moralln 《European Polymer Journal》2008,44(5):1275-1284
A detailed study about the synthesis, characterization and properties of poly(o-methylaniline)(PoMea)/maghnite nanocomposites has been performed. Changes in the characteristics of the nanocomposites, depending on the intercalated cation between the clay layers before the synthesis, have been observed. Intercalated morphology has been detected by TEM in nanocomposites containing copper-treated maghnite (Magh-Cu), while when maghnite treated with strong acids was used (Magh-H); an exfoliated material has been obtained. Also, remarkable differences in the properties of the polymers have been observed by TG-MS and FTIR, suggesting that the polymer produced with Magh-H has a higher degree of branching. The electrochemical behavior of the polymers extracted from the nanocomposites has been studied by cyclic voltammetry. Good electrochemical response has been observed for PoMea grown into Magh-Cu but not for the one polymerized into Magh-H. 相似文献
64.
The aim of this paper is to analyze the effects of uncontrolled co-production on the production planning and lot scheduling of multiple products. Co-production occurs when a proportion of a certain production comes out as another product. This is typical in the process industry where quality and process specifications can lead to diversified products. We assume that there is no demand substitution and each product has its own market. Furthermore, we assume that co-production cannot be controlled due to technical and/or cost considerations. We introduce two models that extend the common cycle economic lot scheduling (ELSP) setting to include uncontrolled co-production. In the first model we do not allow for shortages and derive the optimal cycle time expression. In the second model, we allow for planned backorders and characterize the optimal solution in closed form. We provide a numerical study to gain insight about co-production. It seems that the cycle time increases with co-production rate and utilization of the system. The effect of co-production on long-term average cost does not exhibit a certain characteristic. 相似文献
65.
Diacylglycerol oil has been increasingly recognized by its good nutritional properties and therefore, different technologies have been developed for obtaining it. The present work focuses on the diacylglycerol production by hydrolysis reaction of the palm oil using the PS IM and TL IM commercial lipases as biocatalysts under ultrasound irradiation. An experimental design (central composite rotatable design - CCRD) adopting surface response was applied as a tool to evaluate the optimal reaction conditions beyond a restrict number of experiments. Reactions were performed in an ultrasound equipment and different variables were investigated, such as temperature (30-55 °C), enzyme content (1-2 wt.% of oil mass), mechanical stirring (300-700 rpm) and reaction time. Both, PS IM and TL IM enzymes showed the best results after 1 h and 30 min of reaction under 30 °C and, applying 300 rpm as stirring. On these conditions, the diacylglycerol yield was around 34% and 39%, respectively; considering that 1% PS IM was applied for the first one and, 2% TL IM for the second one. Therefore, it was obtained good yield of a diacylglycerol-rich oil in shorter reaction times under sonication and soft conditions. The mathematic model proposed suggested a satisfactorily representation of the process and good correlation among the experimental results and the theoretical values predicted by the model equation were achieved. 相似文献
66.
Gülgün Yeniehirli Nuren Altunta
zta Ertan ahin Mustafa elebier Nilgün Ancn Selma Gül
zta 《Heteroatom Chemistry》2010,21(6):373-385
A new series of diorganotin complexes of the type R2SnL (L1: N‐(2‐hydroxy‐5‐chlorophenyl)‐ 3‐ethoxysalicylideneimine, R = Me, (Me2SnL1), R = n‐Bu, (n‐Bu2SnL1), R = Ph, (Ph2SnL1), L2: N‐(2‐hydroxy‐4‐nitro‐5‐chlorophenyl)‐3‐ethoxysalicylideneimine, R = Ph, Ph2SnL2, L3: N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐methoxysalicylideneimine, R = Me, (Me2SnL3), R = n‐Bu, (n‐Bu2SnL3), L4: N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐ethoxysalicylideneimine, R = Me, (Me2SnL4), R = n‐Bu, (n‐Bu2SnL4)) were synthesized and characterized by elemental analysis, infrared (IR), 1H, and 13C NMR mass spectroscopic techniques, and electrochemical measurements. Ph2SnL1 and Ph2SnL2 were also characterized by X‐ray diffraction analysis and were found to show a fivefold C2NO2 coordination geometry nearly halfway between a trigonal bipyramidal and distorted square pyramidal arrangement. The C Sn C angles in the complexes were calculated using Lockhart's equations with the 1J(117/119Sn‐13C) and 2J(117/119Sn‐1H) values from the 1H NMR and 13C NMR spectra. Biocidal activity tests against several micro‐organisms and some fungi indicate that all the complexes are mildly active against Gram (+) bacteria and the fungi, A. niger and inactive against Gram (−) bacteria. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:373–385, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20628 相似文献
67.
There is a correspondence between functions in the maximal ideal of the local ring of a rational singularity and certain positive
divisors supported on the exceptional fiber of a resolution of the singularity. Here we give an algorithm to obtain a generating
set over ℤ of these divisors. 相似文献
68.
Alisina Bazrafshan Travis A. Meyer Hanquan Su Joshua M. Brockman Aaron T. Blanchard Selma Piranej Yuxin Duan Yonggang Ke Khalid Salaita 《Angewandte Chemie (International ed. in English)》2020,59(24):9514-9521
Inspired by biological motor proteins, that efficiently convert chemical fuel to unidirectional motion, there has been considerable interest in developing synthetic analogues. Among the synthetic motors created thus far, DNA motors that undertake discrete steps on RNA tracks have shown the greatest promise. Nonetheless, DNA nanomotors lack intrinsic directionality, are low speed and take a limited number of steps prior to stalling or dissociation. Herein, we report the first example of a highly tunable DNA origami motor that moves linearly over micron distances at an average speed of 40 nm/min. Importantly, nanomotors move unidirectionally without intervention through an external force field or a patterned track. Because DNA origami enables precise testing of nanoscale structure‐function relationships, we were able to experimentally study the role of motor shape, chassis flexibility, leg distribution, and total number of legs in tuning performance. An anisotropic rigid chassis coupled with a high density of legs maximizes nanomotor speed and endurance. 相似文献
69.
70.
Hilmi Namli Ayse Dilek Azaz Sedat Karabulut Selma Çelen Raif Kurtaran Canan Kazak 《Transition Metal Chemistry》2007,32(2):266-270
The cobalt(IV) complex of 2,6-diacetylpyridine dioxime (dapdoH2) was prepared and characterized by X-ray diffraction, elemental analysis and FT-IR. The titled complex was found to crystallize
in the orthorhombic space group and was screened for antibacterial and antifungal activities by the disc diffusion and microtitter
plate techniques using DMF as solvent. It has been found that the antimicrobial activity of the complex [Co(dapdo)2] is slightly higher than the free ligand (dapdoH2). 相似文献