Sharif Digital Repository

Molecularly imprinted polymer (MIP) was synthesized through the coprecipitation method on the graphene oxide anchored pencil lead as a substrate for the first time and applied as an efficient sorbent for pseudo stir bar sorptive extraction of nabumetone. The extracted analyte was determined by a novel spectrophotometric method based on the aggregation of silicate sol-gel stabilized silver nanoparticles in the presence of the analyte. The synthesized polymer was characterized using Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Optimization of important parameters affecting the extraction efficiency was done using central composite design whereas the... 

A sensitive fluorometric assay is described for the direct determination of the antibiotic sulfadiazine. Silver nanoparticles placed on graphene quantum dots (Ag NP-GQDs) were synthesized by reduction of AgNO3 with sodium borohydride in the presence of GQDs. The growth of Ag NPs on the surface of the GQDs causes quenching of the blue fluorescence of the GQDs with an emission maximum at 470 nm by surface-enhanced energy transfer. If sulfadiazine is added, it interacts with Ag NPs and fluorescence is restored. Under optimal conditions, the fluorescence increases linearly in the sulfadiazine concentration range of 0.04–22.0 μM. The detection limit is 10 nM with relative standard deviations of... 

A novel colorimetric nanosensor is reported for the selective and sensitive determination of cysteine using magnetic-sulfur, nitrogen graphene quantum dots (Fe3O4/S, N-GQDs), and gold nanoparticles (Au NPs). Thus, S, N-GQDs was firstly immobilized on Fe3O4 nanoparticles through its magnetization in the presence of Fe3+ in the alkali solution. The prepared Fe3O4/S, N-GQDs were dispersed in cysteine solution resulting in its quick adsorption on the surface of the Fe3O4/S, N-GQDs through hydrogen bonding interaction. Then, Au NPs solution was added to this mixture that after a short time, the color of Au NPs changed from red to blue, the intensity of surface plasmon resonance peak of Au NPs at... 

A novel colorimetric nanosensor is reported for the selective and sensitive determination of cysteine using magnetic-sulfur, nitrogen graphene quantum dots (Fe3O4/S, N-GQDs), and gold nanoparticles (Au NPs). Thus, S, N-GQDs was firstly immobilized on Fe3O4 nanoparticles through its magnetization in the presence of Fe3+ in the alkali solution. The prepared Fe3O4/S, N-GQDs were dispersed in cysteine solution resulting in its quick adsorption on the surface of the Fe3O4/S, N-GQDs through hydrogen bonding interaction. Then, Au NPs solution was added to this mixture that after a short time, the color of Au NPs changed from red to blue, the intensity of surface plasmon resonance peak of Au NPs at... 

Semantic web search engines are evolving and many prototype systems and some implementation have been developed. However, there are some different views on what a semantic search engine should do. In this paper, a categorization scheme for semantic web search engines are introduced and elaborated. For each category, its components are described according to a proposed general architecture and various approaches employed in these components are discussed. We also propose some factors to evaluate systems in each category. © 2006 IEEE  

One of the important elements of the new generation of the Web is the emergence of blogs. Currently a considerable number of users are creating content using blogs. Although Persian blogs have a short history, they have improved significantly during this short period. Because of fundamental differences between Persian and other languages, limited work has been done to analyze Persian blogs. In this work, a system named BlogDisc for automatic discovery and accumulation of Persian blogs is developed. This system uses content as well as link structure of the blogs. As an important part of this research, we propose an algorithm to recognize blogs that are not hosted on special blog hosts. © 2007... 

We study diffusive heterogeneous predator-prey system with Holling type-II functional response in the presence of harvesting in prey equation i.e.{-δu=λu-a(x)u2-buv1+mu-ch(x)in Ω,-δv=μv-v2+duv1+muin Ω,∂νu=∂νv=0on ∂Ω, where Ω is a smooth bounded region in RN and a(x) is a nonnegative continuous function on Ω, with Ω0 a region such that Ω⊂Ω and a(x)>0 on Ω\u03a90. We show that in the case of weak prey growth rate, i.e. λ less than the first eigenvalue of -δ in Ω0, the system has a positive solution for the values of μ in a bounded interval and c>0 sufficiently small. We also investigate the multiplicity of positive solutions in this case. When the prey growth rate is strong, we will show that... 

From a thermal point of view, zeotropic mixtures are likely to be more efficient than azeotropic fluids in low-temperature power cycles for reduction in exergy destruction occurring during heat absorption/rejection processes due to their suitable boiling characteristics. In this study, comprehensive energetic and exergetic analyses are mathematically performed for an organic Rankine cycle (ORC) system employing a potential binary zeotropic working fluid, namely R717/water. For this purpose, initially mass, energy, and exergy balance equations are derived. With regard to the similarity in molar mass of R717 (17.03 g mol−1) and water (18.01 g mol−1), there is no need to alter the size of the... 

From a thermal point of view, zeotropic mixtures are likely to be more efficient than azeotropic fluids in low-temperature power cycles for reduction in exergy destruction occurring during heat absorption/rejection processes due to their suitable boiling characteristics. In this study, comprehensive energetic and exergetic analyses are mathematically performed for an organic Rankine cycle (ORC) system employing a potential binary zeotropic working fluid, namely R717/water. For this purpose, initially mass, energy, and exergy balance equations are derived. With regard to the similarity in molar mass of R717 (17.03 g mol −1 ) and water (18.01 g mol −1 ), there is no need to alter the size of... 

Microstructure and mechanical properties development of X80 weld metal by addition of different amounts of alloying elements such as Nickel and Manganese to the covering of electrodes were investigated. For this reason samples were welded with electrodes that Ni value changed between 0.8%- 3.5% in tow critical amounts of Mn: 0.7 and 1.6. Tensile test and microhardness results indicated the suitable ranges of Ni and Mn for acceptable mechanical properties. In addition, optical microscopy and scanning electron microscopy were applied to link the microstructure with mechanical properties. The hardness of weld metals were found to increase linearly with Mn and Ni, which was attributed mainly to... 

Currently there is no standard test collection for evaluation of Farsi information retrieval systems. In this paper we introduce Mahak, the first complete test collection generally available for evaluating Farsi information retrieval systems. In addition, we have used different methods for constructing Mahak qrels and we have compared performance of these methods  

Machine learning algorithms often suffer from good generalization in testing domains especially when the training (source) and test (target) domains do not have similar distributions. To address this problem, several domain adaptation techniques have been proposed to improve the performance of the learning algorithms when they face accuracy degradation caused by the domain shift problem. In this paper, we focus on the non-homogeneous distributed target domains and propose a new latent subdomain discovery model to divide the target domain into subdomains while adapting them. It is expected that applying adaptation on subdomains increase the rate of detection in comparing with the situation... 

Question Answering systems are one of the hot topics in context of information retrieval. In this paper, we develop an open-domain Question Answering system for spatial queries. We use Google for gathering raw data from the Web and then in a few iterations density of potential answers will be increased, finally based on a couple of evaluators the best answers are selected to be returned to user. Our proposed algorithm uses fuzzy methods to be more precise. Some experiments have been designed in order to evaluate the performance of our algorithm and results are totally promising. We will describe that how this algorithm can be applied to other type of questions as well  

Several metrics have been proposed for recognition of relationships between elements of two Ontologies. Many of these methods select a number of such metrics and combine them to extract existing mappings. In this article, we present a method for selection of more effective metrics - based on data mining techniques. Furthermore, by having a set of metrics, we suggest a data-mining-like means for combining them into a better ontology alignment