Sharif Digital Repository

Electrochemical deposition, as a well-controlled synthesis procedure, has been used for subsequently layer-by-layer preparation of nickel hydroxide nanoparticle-reduced graphene oxide nanosheets (Ni(OH)2-RGO) on a graphene oxide (GO) film pre-cast on a glassy carbon electrode surface. The surface morphology and nature of the nano-hybrid film (Ni(OH)2-RGO) was thoroughly characterized by scanning electron and atomic force microscopy, spectroscopy and electrochemical techniques. The modified electrode appeared as an effective electro-catalytic model for analysis of rifampicin (RIF) by using linear sweep voltammetry (LSV). The prepared modified electrode exhibited a distinctly higher activity... 

In this paper, a methodology for transporting objects with a group of wheeled nonholonomic mobile manipulators is presented. A full dynamic model of a mobile manipulator with a three wheeled mobile base and a three DOF manipulator is derived using the Gibbs-Appell method. Since the dynamical equations of a mobile robot are highly nonlinear, an input-output linearization technique is used to control individual robots. Transporting the object is divided into two steps. First, the robots use a decentralized behavior-based method to approach and surround the object. Then, a virtual structure method is used to control the robots to transport the object cooperatively. A numerical simulation study... 

A glassy carbon electrode (GCE) is modified with platinum nanoparticle (PtNPs) decorated multiwalled carbon nanotube (MWCNT). The modified electrode is applied for the determination of ceftriaxone (CFX) in the presence of lidocaine. Different methods were used to characterize the surface morphology of the modified electrode. The electrochemical behavior of CFX was investigated at GCE, MWCNT/GCE and PtNPs/MWCNT/GCE. A factorial-based response-surface methodology was used to find out the optimum conditions with minimum number of experiments. Under the optimized conditions, oxidation peak currents increased linearly with CFX concentration in the range of 0.01-10.00 μM with a detection limit of... 

Background: Biodegradation of free cyanide from industrial wastewaters has been proven as a viable and robust method for treatment of wastewaters containing cyanide. Results: Cyanide degrading bacteria were isolated from a wastewater treatment plant for coke-oven-gas condensate by enrichment culture technique. Five strains were able to use cyanide as the sole nitrogen source under alkaline conditions and among them; one strain (C2) was selected for further studies on the basis of the higher efficiency of cyanide degradation. The bacterium was able to tolerate free cyanide at concentrations of up to 500 ppm which makes it a good potentially candidate for the biological treatment of cyanide... 

This paper reviews the applications of experimental design to optimize some analytical chemistry techniques such as extraction, chromatography separation, capillary electrophoresis, spectroscopy, and electroanalytical methods  

In this work, the process of free gravity drainage under the influence of ultrasonic waves was investigated. A glass bead pack porous medium was used to perform free fall gravity drainage experiments. The tests were performed in the presence and absence of ultrasonic waves, and the data of recovery were recorded versus time under both conditions. The wetting phase relative permeability curves were obtained using the data of recovery versus time, based on the Hagoort backward methodology. Subsequently, using the wetting phase relative permeability curve, the relative permeability of non-wetting phases were calculated by performing history matching to the experimental production data. The... 

Background: In the recent study, optimum operational conditions of cathode compartment of microbial fuel cell were determined by using Response Surface Methodology (RSM) with a central composite design to maximize power density and COD removal. Methods: The interactive effects of parameters such as, pH, buffer concentration and ionic strength on power density and COD removal were evaluated in two-chamber microbial batch-mode fuel cell. Results: Power density and COD removal for optimal conditions (pH of 6.75, buffer concentration of 0.177 M and ionic strength of cathode chamber of 4.69 mM) improve by 17 and 5%, respectively, in comparison with normal conditions (pH of 7, buffer concentration... 

Traditionally, the model of a resource-constrained project-scheduling problem (RCPSP) contains a single objective function of either minimizing project makespan or maximizing project net present value (NPV). In order to be more realistic, in this paper, two multi-objective meta-heuristic algorithms of multi-population and two-phase sub-population genetic algorithms are proposed to find Pareto front solutions that minimize the project makespan and maximize the project NPV of a RCPSP, simultaneously. Based on standard test problems constructed by the RanGen project generator, a comprehensive computational experiment is performed, where response surface methodology is employed to tune the... 

A series of V2O5 catalysts supported on multiwall carbon nanotube (MWCNT), single wall carbon nanotube (SWCNT), and graphene were synthesized by hydrothermal and reflux methods for oxidative dehydrogenation of propane (ODHP) to propylene. The catalysts were characterized by techniques including the BET surface area measurements, XRD, FTIR, H2-TPR, NH3-TPD, FESEM, and UV-vis diffuse reflectance spectroscopy. The performance of the catalysts and the supports were subsequently examined in a fixed bed reactor. The main products were propylene, ethylene and CO x. The vanadium catalyst supported on graphene with C/V molar ratio of 1:1 synthesized through the hydrothermal method had the best... 

Reduced graphene oxide nanomesh (rGONM), as one of the recent structures of graphene with a surprisingly strong near-infrared (NIR) absorption, is used for achieving ultraefficient photothermal therapy. First, by using TiO2 nanoparticles, graphene oxide nanoplatelets (GONPs) are transformed into GONMs through photocatalytic degradation. Then rGONMs functionalized by polyethylene glycol (PEG), arginine-glycine-aspartic acid (RGD)-based peptide, and cyanine 7 (Cy7) are utilized for in vivo tumor targeting and fluorescence imaging of human glioblastoma U87MG tumors having ανβ3 integrin receptors, in mouse models. The rGONM-PEG suspension (1 μg mL -1) exhibits about 4.2- and 22.4-fold higher NIR... 

The aim of this paper is to develop the technical knowledge, especially the optimum geometries, for the design and manufacturing of a supersonic gas-gas ejector for a wasteheat driven vehicle cooling system. Although several studies have been performed to investigate the effects of geometrical configurations of gas-gas ejectors, a progressive design methodology of an ejector compressor for application to a vehicle cooling system has not yet been described. First, an analytical model for calculation of the ejector optimum geometry for a wide range of operating conditions is developed, using R134a as the working fluid with a rated cooling capacity of 2.5 kW. The maximum values of entrainment... 

This study presents applying recurrence quantification analysis (RQA) on EEG recordings and their subbands: delta, theta, alpha, beta, and gamma for epileptic seizure detection. RQA is adopted since it does not require assumptions about stationarity, length of signal, and noise. The decomposition of the original EEG into its five constituent subbands helps better identification of the dynamical system of EEG signal. This leads to better classification of the database into three groups: Healthy subjects, epileptic subjects during a seizure-free interval (Interictal) and epileptic subjects during a seizure course (Ictal). The proposed algorithm is applied to an epileptic EEG dataset provided... 

Background: The abundance of gene expression microarray data has led to the development of machine learning algorithms applicable for tackling disease diagnosis, disease prognosis, and treatment selection problems. However, these algorithms often produce classifiers with weaknesses in terms of accuracy, robustness, and interpretability. This paper introduces fuzzy support vector machine which is a learning algorithm based on combination of fuzzy classifiers and kernel machines for microarray classification.Results: Experimental results on public leukemia, prostate, and colon cancer datasets show that fuzzy support vector machine applied in combination with filter or wrapper feature selection... 

In this study, application of the Response Surface Methodology and the Central Composite Design (CCD) technique for modeling and optimization of the influence of several operating variables on titanium recovery in a leaching process were investigated. The four main leaching parameters, namely temperature, acid concentration, leaching time and solid to liquid ratio, were changed during-the leaching experiments based on the CCD. A total of 30 leaching experiments were designed and carried out in the CCD method according to software-based designed matrix. According to the results, i.e., titanium recoveries with these four parameters as well as empirical model equations were developed. The model... 

Response surface methodology (RSM) was applied to optimize the process of biodiesel production from Iranian bitter almond oil. Design of experiments was performed by application of a 5-level-3-factor central composite design in order to study the effect of different factors on the product yield, biodiesel yield and biodiesel purity. These factors were reaction temperature (30-70°C), catalyst concentration (0.3-1.7% w/w) and methanol to oil molar ratio (4.4-13.6 mol/mol). A quadratic model was suggested for the prediction of the biodiesel yield. Analysis of variance revealed that the factors were significant on the production process of biodiesel. For each factor, the optimum value was... 

Purpose - The purpose of this paper is to investigate the effect of power on pulsed plasma thruster (PPT) discharge current with respect to its peak, duration, and behavior while the power elevates in a low power range. Design/methodology/approach - A rectangular parallel-plate breech-fed PPT has been developed with a self-inductor coupling element connecting the PPT cathode to the ignitor plug cathode. The PPT has been operated in vacuum chamber at 10-6mbar and its discharge current has been recorded using a Rogowski coil while input power has been changed by means of varying the capacitor voltage at given capacitance and frequency. Findings - The analysis leads to elucidate the effects of... 

In the present study, the dissimilar aluminum alloys of 5083-H12 and 6061-T6 were joined by friction stir welding (FSW). Then, the design of experiments (DOE), the Box-Benken method, and the response surface methodology (RSM) were used to optimize the effective parameters of the FSW process. The optimized parameters that led to the maximum tensile strength in dissimilar friction stir welded sheets were determined. The predicted results were then compared with those measured experimentally. The results show that there is good agreement between the predicted and measured amounts. By applying the limit dome height (LDH) test, the formability of friction stir welded sheets was studied. During... 

Purpose - The purpose of this paper is to propose a mathematical model to estimate required energy and temperature distribution during cold extrusion process. Design/methodology/approach - An admissible velocity field is generated based on stream function technique. Then, the required energy and the temperature distributions in the metal and the extrusion die are determined by a coupled upper bound-finite element analysis. Findings - To examine the proposed model, cold extrusion of AA6061-10%SiCp is considered and the predicted extrusion force-displacement diagrams in different reductions are compared with the experimental ones and reasonable agreement is observed. Furthermore, it... 

Motivation: The interactions among proteins and the resulting networks of such interactions have a central role in cell biology. Aligning these networks gives us important information, such as conserved complexes and evolutionary relationships. Although there have been several publications on the global alignment of protein networks; however, none of proposed methods are able to produce a highly conserved and meaningful alignment. Moreover, time complexity of current algorithms makes them impossible to use for multiple alignment of several large networks together.Results: We present a novel algorithm for the global alignment of protein-protein interaction networks. It uses a greedy method,... 

Recent progress in developing artificial neural network (ANN) metamodels has paved the way for reliable use of these models in the prediction of air pollutant concentrations in urban atmosphere. However, improvement of prediction performance, proper selection of input parameters and model architecture, and quantification of model uncertainties remain key challenges to their practical use. This study has three main objectives: to select an ensemble of input parameters for ANN metamodels consisting of meteorological variables that are predictable by conventional weather forecast models and variables that properly describe the complex nature of pollutant source conditions in a major city, to...