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491.
This study reports a convenient approach to prepare SiO2/CCPy/Cu(OAc)2 as a novel nanocatalyst, in which melamine-bearing pyridine groups have functionalized SiO2 and can act as a capping agent to stabilize Cu(II) species. The catalyst is characterized through Fourier transform infrared, transmission electron microscopy, field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller (BET), thermogravimetric analysis, inductivity coupled plasma (ICP), and energy dispersive X-ray (EDX) techniques. Furthermore, its catalytic behavior is evaluated in the N-arylation of indole, imidazole, and aniline during Ullmann-type C–N coupling reactions. Moreover, it has been proved that the heterogeneous nanocatalyst can be feasibly recovered by filtration and reused in five consecutive reaction cycles without any noticeable loss of its catalytic activity. The results clarified that the devised method is advantageous from several perspectives, that is, low catalyst loading, high product yield, experimental simplicity, broad substrate scope, and short reaction time. 相似文献
492.
Kaveh Parvanak Boroujeni Elham Rezazadeh Shirazi Mohammad Mahdi Doroodmand 《Phosphorus, sulfur, and silicon and the related elements》2016,191(5):683-688
A supported acidic catalyst was easily prepared via anchoring imidazolium salt-based ionic liquid onto multiwalled carbon nanotube by covalent bonds. This novel immobilized acidic ionic liquid effectively catalyzed the one-pot synthesis of α-aminophosphonates from the reaction of amines and aldehydes with diethyl phosphite. The catalyst can be easily recovered and reused without appreciable change in its efficiency. 相似文献
493.
In this article, we apply the concept of m-polar fuzzy sets in labeling graphs and introduce the concept of m-polar fuzzy labeling graphs. We present properties of m-polar fuzzy labeling cycle and m-polar fuzzy labeling with bridge and cut nodes. We introduce several different types of distances, including w-distance, strongest strong distance, strong geodesic distance, \(\delta \)-distance in m-polar fuzzy labeling graph and investigate some of their properties. We also present an application of m-polar fuzzy labeling graphs in image processing. 相似文献
494.
A multi agent organization model defines the structure, roles, interaction ways and coordination styles of a multi agent system. Multi agent organizations may constrain the communication between included members. Organizations’ communication is the process of sending or receiving all the messages through a group of agents in order to achieve common goals. In a dialogue, agents follow some rules that define the permissive speech acts called dialogue protocol. Aiming for common goals, the dialogue strategy is the policy of agents to choose a particular speech act among the allowed ones by the protocol. In this paper a formal model for dialogue strategy for a group of agents in an organization is proposed in order to choose the most preferable speech acts. The argumentation theory is applied to the proposed method to define the values of plausible speech acts and to rank them. The algorithm finds the best option to utter and also it decreases the volume of exchanging messages. The proposed dialogue strategy is illustrated via a deliberation dialogue example in a group of agents. 相似文献
495.
Shaabani Ahmad Afshari Ronak Hooshmand Seyyed Emad 《Research on Chemical Intermediates》2016,42(6):5607-5616
Research on Chemical Intermediates - A greener synthesis of α-acyloxyamides was achieved by one-pot three component cascade Passerini reactions in a deep eutectic solvent (DES). Reactions... 相似文献
496.
497.
Dr. Manjur O. Akram John R. Tidwell Dr. Jason L. Dutton Dr. Caleb D. Martin 《Angewandte Chemie (International ed. in English)》2023,62(34):e202307040
The Lewis superacid, bis(1-methyl-ortho-carboranyl)borane, is rapidly accessed in two steps. It is a very effective hydroboration reagent capable of B−H addition to alkenes, alkynes, and cyclopropanes. To date, this is the first identified Lewis superacidic secondary borane and most reactive neutral hydroboration reagent. 相似文献
498.
Evers F Shokuie K Paulus M Sternemann C Czeslik C Tolan M 《Langmuir : the ACS journal of surfaces and colloids》2008,24(18):10216-10221
The high energy X-ray reflectivity technique has been applied to study the interfacial structure of protein adsorbates and protein adsorption kinetics in situ. For this purpose, the adsorption of lysozyme at the hydrophilic silica-water interface has been chosen as a model system. The structure of adsorbed lysozyme layers was probed for various aqueous solution conditions. The effect of solution pH and lysozyme concentration on the interfacial structure was measured. Monolayer formation was observed for all cases except for the highest concentration. The adsorbed protein layers consist of adsorbed lysozyme molecules with side-on or end-on orientation. By means of time-dependent X-ray reflectivity scans, the time-evolution of adsorbed proteins was monitored as well. The results of this study demonstrate the capabilities of in situ X-ray reflectivity experiments on protein adsorbates. The great advantages of this method are the broad wave vector range available and the high time resolution. 相似文献
499.
Kabir-ud-Din Al-Ahmadi MD Naqvi AZ Akram M 《Colloids and surfaces. B, Biointerfaces》2008,64(1):65-69
Conductivity measurements have been carried out on aqueous solutions of two antidepressant drugs (nortriptyline hydrochloride and clomipramine hydrochloride) with four cationic surfactants (monomeric: cetyltrimethylammonium bromide, tetradecylammonium bromide; dimeric: 1,5-pentanediyl-alpha-omega-bis(hexadecyldimethylammonium bromide), 1,4-butanediyl-alpha,omega-bis(hexadecyldimethylammonium bromide) as well as with sodium chloride. Counterions from NaCl adsorb to the charged headgroup of the drug molecules and reduce the repulsion, hence cmc decreases. cmc values decreased with the addition of surfactants indicating mixed micelle formation. Experimental mole fraction of surfactants in micelle (X1) and their ideal values (X1 id) also support this explanation. Interaction parameter, beta, and excess free energy of micellization are negative suggesting synergism in mixed state. Activity coefficients are less than unity which means non-ideal mixing. 相似文献
500.
Tauqir A. Sherazi Shujaat Ahmad M. Akram Kashmiri Michael D. Guiver 《Journal of membrane science》2008
Ultra-high molecular weight polyethylene (UHMWPE) powder was irradiated by gamma rays using a 60Co source. Simultaneous and pre-irradiation grafting was performed in air and in inert atmosphere at room temperature. The monomer selected for grafting was styrene, since the styrene-grafted UHMWPE could be readily post-sulfonated to afford proton exchange membranes (PEMs). The effect of absorbed radiation dose and monomer concentration in methanol on the degree of grafting (DG) is discussed. It was found that the DG increases linearly with increase in the absorbed dose, grafting time and monomer concentration, reaching a maximum at a certain level. The order of rate dependence of grafting on monomer concentration was found to be 2.32. Furthermore, the apparent activation energy, calculated by plotting the Arrhenius curve, was 11.5 kJ/mole. Lower activation energy and high rate dependence on monomer concentration shows the facilitation of grafting onto powder substrate compared with film. The particle size of UHMWPE powder was measured before and after grafting and found to increase linearly with increase in level of grafting. FTIR-ATR analysis confirmed the styrene grafting. The grafted UHMWPE powder was then fabricated into film and post-sulfonated using chlorosulfonic acid for the purposes of evaluating the products as inexpensive PEM materials for fuel cells. The relationship of DG with degree of substitution (DS) of styrene per UHMWPE repeat unit and ion exchange capacity (IEC) is also presented. 相似文献