Sharif Digital Repository

A highly chemoselective methodology is described for the N-methylation of functionalized anilines with dimethyl carbonate (MeOCO2Me, DMC) in the presence of ZrOCl2·8H2O. Dimethyl carbonate, which usually promotes methylation at T > 120 C and eventually under inert atmosphere, was activated in the presence of zirconium oxychloride for the desired transformation at 90 C under aerobic conditions. Aminophenols showed good reactivity in this transformation and produced the corresponding N-methylanilines, as the major products, with high selectivity. Catalyst reusability study confirmed that ZrOCl2·8H2O is a recyclable catalyst and its catalytic activity was remained unchanged at least after eight... 

Efficient synthesis of protected and unprotected chlorohydrins has been achieved by ring opening of epoxides with acetyl/benzoyl chloride and TMSCl using a catalytic amount of ZnO as a reusable catalyst. The applicability of ZnO is further extended by performing the cleavage of the natural product 5,6-epoxysitosterol with acetyl chloride. © 2009 Wiley Periodicals, Inc  

Due to the extreme use of method engineering and increasing attention to construct methods customized for a specific project, domain, organization or a generic method compatible with the team characteristics and needs, existence of suitable and formalized frameworks and guidelines is one of the challenges method engineers are encountered. In this area, considering method construction as the goal of method engineering brings to the mind the software development process in which the product is a method adapting the method users' needs. This paper, with a new approach of applying software architecture in method engineering and making use of architecture styles, tries to take advantage of... 

An efficient method is reported for selective oxidation of various types of sulfides to sulfoxides and sulfones in good to high yields using 30% H 2O2 in the presence of catalytic amounts of molybdate-based catalyst in acetonitrile as solvent at room temperature. The catalyst can be easily recovered and reused for seven reaction cycles without considerable loss of activity  

In this study nickel ferrite magnetic nanoparticles were applied as an efficient and reusable catalyst in the four-component synthesis of substituted pyrroles under neat conditions. The reaction was conducted using various amounts of catalyst at different temperatures and finally, application of 5 mol% of catalyst at 100 °C was determined as the optimum reaction condition. Results showed that nickel ferrite nanoparticles could catalyze the reaction at relatively short times (3-4 h) with high to excellent yields (70-96%). The catalyst could be recovered easily using an external magnetic field and reused nine times without any significant activity lost  

An efficient synthesis of tetrahydrobenzofurans is carried out in one pot through the reaction of 1,3-diketone and phenacyl bromides compound using a heterogeneous basic nano particles copper oxide catalyst. The protocol offers advantages in terms of higher yields, short reaction times, and mild reaction conditions, with reusability of the catalyst. © 2009 Elsevier B.V. All rights reserved  

Multi-agent systems (MAS) is a solution to the nowadays encountered problems, which have the characteristics such as distributiveness, dynamism and the need to adaptation, robustness, efficiency, and reusability. This paper proposed a solution to multi-agent credit assignment problem. The contribution is to equip the critic agent (who is responsible for distributing reinforcements among agents) with learning capability. Some criteria are used to propose an inner feedback to the critic. Results of simulation show the applicability of the method to a task, which has the characteristic that the agent has to decide from a large set of actions. The research is a preliminary step to more in-depth... 

The preparation, characterization and catalytic application of a novel copper-loaded ionic liquid-based periodic mesoporous organosilica (Cu@PMO-IL) are described. The mesoporous structure of the Cu@PMO-IL material is characterized by transmission electron microscopy (TEM) and nitrogen adsorption-desorption analysis. The thermal stability of the material is also determined by thermal gravimetric analysis (TGA). The presence of copper species in the material framework is confirmed by X-ray photoelectron spectroscopy (XPS) and elemental analysis (EA). The catalytic application of Cu@PMO-IL nanocatalyst is then investigated in the Biginelli condensation of different aldehydes with urea and... 

The current work deals with modification of the surface of a silica-polyamine with amine-based ionic liquid (IL) and its application for removal of Cu2+ from an aqueous media. The absorbent is simply prepared from commercially available reagents. The material is characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), N2 adsorption-desorption, and transmission electronic microscopy (TEM). Effects of several parameters on absorption efficiency, as well as activity of the absorbent to other metals, are also investigated. Moreover, the reusability of the absorbent is studied at the optimized condition. © The Royal Society of Chemistry 2016  

Entangled states can be used as secure carriers of information much in the same way as carriers are used in classical communications. In such protocols, quantum states are uploaded to the carrier at one end and are downloaded from it in safe form at the other end, leaving the carrier intact and ready for reuse. Furthermore, protocols have been designed for performing quantum state sharing in this way. In this work, we study the robustness of these protocols against two of the most common sources of noise, namely de-phasing and depolarization and show that multiple uses of these carriers do not lead to accumulative errors, rather the error remains constant and under control. © 2020, Springer... 

Reconfigurability for a component of a distributed component-based system means ability to replace the component with a new one, in presence of the other components. In this context, substitutability and compatibility of components should be analyzed. In this paper, we use I/O-Constraint Automata to model behavior of components and propose enough formalism for substitutability and compatibility analysis. We show that in the context of distributed non-blocking components, there is a relation weaker than usual simulation relation in automata theory for notion of substitutability. We illustrate the relation between substitutability and compatibility to reason about the reconfigurability of a... 

An efficient method for the synthesis of 4-amino-5-pyrimidinecarbonitriles by three-component reaction of malononitrile, aldehydes and N-unsubstituted amidines, under aqueous conditions, using CuO nanoparticles as catalyst is reported. The protocol offers advantages in terms of higher yields, short reaction times, and mild reaction conditions, with reusability of the catalyst  

Component-Based Development (CBD) has been broadly used in software development, as it enhances reusability and flexibility, and reduces the costs and risks involved in systems development. It has therefore spawned many widely-used approaches, such as Commercial Off-The-Shelf (COTS) and software product lines. On the other hand, in order to gain a competitive edge, organizations need to define custom processes tailored to fit their specific development requirements. This has led to the emergence of process patterns and Method Engineering approaches. We propose a set of process patterns commonly encountered in component-based development methodologies. Seven prominent component-based... 

An environmentally benign, aqueous synthesis of 1,2-azidoalcohols via regioselective ring opening of their epoxides using magnetic imidazolium based dicationic room temperature ionic liquid, [pbmim](FeCl4)2, as an efficient magnetic phase transfer catalyst in water has been described. The present approach offers the advantages of clean reaction, simple methodology, short reaction time, high yield, easy purification and reusable catalyst  

Object-oriented frameworks are widely used to develop new applications. They provide reusable concepts that are instantiated in application code through potentially complex implementation steps such as subclassing, implementing interfaces, and calling framework operations. Unfortunately, many modern frameworks are difficult to use because of their large and complex APIs and frequently incomplete user documentation. To cope with these problems, developers often use existing framework applications as a guide. However, locating concept implementations in those sample applications is typically challenging due to code tangling and scattering. To address this challenge, we introduce the notion of... 

An eco-friendly, simple, and effective protocol is developed for the synthesis of various multisubstituted 2-aminothiophenes. In the presence of a catalytic amount of ZnO (5 mol), ketones or aldehydes, malononitrile and elemental sulfur were converted to the corresponding 2-aminothiophene derivatives in moderate to high yields (27%-70%) under solvent-free conditions at 100 °C. Zinc oxide as an efficient, readily available, and reusable catalyst, showed very good catalytic activity for the synthesis of 2-aminothiophene derivatives. Thus far, little research has been reported on the Gewald reaction under solvent-free conditions; to the best of our knowledge, this is the first time that it has... 

1-Butyl-3-methylimidazolium tungstate ([BMIm] 2WO 4) ionic liquid supported onto silica sulphamic acid demonstrated desirable performance for oxidation of cyclohexene to adipic acid. Simple experimental procedure, easy product isolation, catalyst recovery and reusability are some attractive features of this protocol  

Uniformly sized superparamagnetic single-shell nonporous (S1) and double-shell mesoporous silica nanocomposite particles with ∼130 nm magnetite cluster cores are synthesised in this study. Mesoporous particles are prepared with two BJH pore sizes (2.44 and 3.76 nm, designated as S2 and S3 particles, respectively). Once the lipase was immobilised on particles, our results showed that the enzyme loading capacities of mesoporous structures, i.e. S2 and S3, are higher than that for nonporous particles (S1). Hydrolytic activity tests reveal that immobilised lipases retain about 90% of the free enzyme's activity. Furthermore, comparing to the free enzyme, the thermal stability of immobilised...