Sharif Digital Repository

Demand for more efficient energy storage devices stimulates efforts to search and develop new materials and composites with promising properties. In this regard, composite materials, including carbonaceous materials and metal oxides have attracted a great attention due to better electrochemical performance as compared to their single material analogues. For the first time, herein, we report a new and simple procedure for preparing porous highly oriented pyrolytic graphite/nickel hydroxide composite (P-HOPG/Ni(OH)2) via a fast and simple two-step electrochemical method including potentiostatic routes. In the first step, a low anodic potential (2 V) was applied to pristine HOPG in 0.5 M H2SO4... 

A novel voltammetric sensor based on glassy carbon electrode (GCE) modified with a thin film of multi-walled carbon nanotubes (MWCNTs) coated with an electropolymerized layer of tiron-doped polypyrrole was developed and the resulting electrode was applied for the determination of acyclovir (ACV). The surface morphology and property of the modified electrode were characterized by field emission scanning electron microscopy and electrochemical impedance spectroscopy techniques. The electrochemical performance of the modified electrode was investigated by means of linear sweep voltammetry (LSV). The effect of several experimental variables, such as pH of the supporting electrolyte, drop size of... 

A carbon-paste electrode (CPE) modified with iron(II) phthalocyanine was used for the sensitive voltammetric determination of epinephrine (EN). The electrochemical response characteristics of the modified electrode toward EN, ascorbic acid (AA) and uric acid (UA) were investigated by cyclic and differential pulse voltammetry (CV and DPV). The results show an efficient catalytic activity of the electrode for the electro-oxidation of EN, which leads to improvement of reversibility of the electrode response and lowering its overpotential by more than 100 mV. The effect of pH and potential sweep rate on the mechanism of the electrode process was investigated. The modified electrode exhibits an... 

In this work, a nanocomposite containing manganese dioxide (MnO2) modified reduced graphene oxide (rGO) supported bimetallic palladium-nickel (Pd-Ni) catalyst is prepared by electrodeposition method. The nanocomposite modifier film is prepared by forming a thin layer of graphene oxide (GO) via drop-casting of GO nanosheet dispersion on glassy carbon electrode (GCE), followed by electrochemical reduction of the film to provide rGO/GCE. Then, a two-step potential procedure is applied to deposit MnO2 nanoparticles on rGO/GCE. At the optimum deposition conditions, MnO2 nanoparticles with a thickness of 30-50 nm homogeneously covered the rGO surface (MnO2/rGO/GCE). Finally, the bimetallic Pd-Ni... 

Increasing energy demands for pollution-free and renewable energy technologies have stimulated intense research on the development of inexpensive, highly efficient, and stable non-noble metal electrocatalysts for oxygen evolution reaction (OER). In this study, a superior OER performance was achieved using a tri-metallic (Zn, Co, Ni) high-performance electrocatalyst. We successfully fabricated a peony-flower-like hierarchical ZnCo2O4 through an additive-free hydrothermal reaction followed by heat treatment. Then NiCo-LDH (layered double hydroxides) nano-flakes was electrodeposited on the ZnCo2O4/GCE surface to prepare NiCo-LDH/ZnCo2O4/GCE which was used as electrode for OER. The structure and... 

This paper presents an optimal control strategy for optimal trajectory planning of mobile robots by considering nonlinear dynamic model and nonholonomic constraints of the system. The nonholonomic constraints of the system are introduced by a nonintegrable set of differential equations which represent kinematic restriction on the motion. The Lagrange's principle is employed to derive the nonlinear equations of the system. Then, the optimal path planning of the mobile robot is formulated as an optimal control problem. To set up the problem, the nonlinear equations of the system are assumed as constraints, and a minimum energy objective function is defined. To solve the problem, an indirect... 

Multi-walled carbon nanotubes decorated with Fe 3O 4 nanoparticles (Fe 3O 4NPs/MWCNT) were prepared and used to construct a novel biosensor for the simultaneous detection of adenine and guanine. The direct electro-oxidation of adenine and guanine on the modified electrode were investigated by linear sweep voltammetry. The results indicate a remarkable increase in the oxidation peak currents together with negative shift in the oxidation peak potentials for both adenine and guanine, in comparison to the bare glassy carbon electrode (GCE). The surface morphology and nature of the composite film deposited on GCE were characterized by transmission electron microscopy, atomic force microscopy,... 

This work describes the development of a novel electrochemical sensor based on electrodeposition of copper oxide nanoparticles onto carbon nanoparticle (CNP) film modified electrode for the analysis of the anti-HIV drug, nevirapine (NEV). The electrochemical experiments were performed using linear sweep and cyclic voltammetry. Atomic force microscopy was applied for surface characterization of the deposited modifier film (CuO-CNP) on glassy carbon electrode (GCE). No oxidation peak was observed for NEV on the bare GCE, but both CNP-GCE and CuO-CNP-GCE showed a distinctive anodic response towards NEV with considerable enhancement (276-fold and 350-fold, respectively) compared to CuO-GCE. The... 

Multi-walled carbon nanotubes (MWCNTs) were immobilised with cobalt nanoparticles and analyzed by transmission electron microscopy. This modification procedure substantially improved colloidal dispersion of the immobilised MWCNTs in water and organic solvents, yielding uniform and stable thin films for modification of the glassy carbon electrode surface. The modified electrode showed an efficient catalytic role for the electrochemical oxidation of thioridazine (TR), leading to remarkable decrease in its oxidation overpotential of approximately 100 mV and enhancement of the kinetics of the electrode reaction, which can be confirmed by increasing in the peak current and sharpness of the peak.... 

An efficient and commercially available method is introduced for preparation of a binder-free electrode for capacitive deionization (CDI) application. An interconnected porous composite consisting of polyphosphate (PPO), graphene (Gr) and multi-walled carbon nanotube (CNT) is fabricated and assembled on a Ni foam substrate to prepare a binder-free electrode (Ni/PPOGrCNT). The resulting electrodes were characterized using various instrumental techniques such as TEM, SEM, EDS, XRD, FT-IR, Raman, XPS and XRF. Characterization results indicated that a mesoporous PPO structure is formed on a 3D assembly of carbon backbone. Accordingly, the 3-D porous structure facilitates the ion diffusion into... 

The authors regret We have found, there is a problem with the image orders in the last version of the article that is being published online. In the accessible version, the caption of the images are exactly in the true orders, but the images are shifted up and they are not shown in their exact positions. This Corrigendumm is being released for revision of the image orders, like what they were in the accepted version of the manuscript. The materials are shown in the following pages. The authors would like to apologise for any inconvenience caused. [Formula presented] Scheme 1. Binder-free fabrications of the PPOGrCNT on nickel foam (Ni/PPOGrCNT electrode). [Formula presented] Fig. 1. (a)... 

Readily prepared copper nanoparticles supported on CeO2 have been found to effectively catalyse the 1,3-dipolar cycloaddition (CuAAC) of a variety terminal alkynes and organic azides generated in situ from sodium azide and different organic halides furnishing the corresponding 1,2,3-triazoles in excellent yields. Cu nanoparticles supported on CeO2 have been characterized by X-ray diffraction analysis, energy dispersive X-ray analysis, scanning electron microscope and transmission electron microscope. The salient features of the present protocol are shorter reaction time, mild reaction conditions, reusability of the catalyst, and applicability to a wide range of substrates. © 2016 Elsevier... 

The reaction of the functionalized mesoporous SBA-15 in absolute ethanol with copper (II) acetate afforded a novel CuII-Schiff base/SBA-15 catalyst. The compound CuII-Schiff base/SBA-15 was characterized by IR spectroscopy, small-angle X-ray diffraction (SAX), Energy Dispersive X-ray Spectroscopy (EDXS), X-ray Absorption Near Edge Structure (XANES), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and N2 adsorption/desorption studies. Further, the catalytic activity of this well-defined material was tested in three-component Copper-catalyzed Azide-Alkyne Cycloaddition (CuAAC) reactions to obtain 1,4-disubstituted-1,2,3-triazoles in good to excellent yields from an... 

Fabrication of scaffolds with enhanced mechanical properties and desirable cellular compatibility is critical for numerous tissue engineering applications. This study was aimed at fabrication and characterization of a nanofiber skin substitute composed of collagen (Col)/sodium alginate (SA)/ polyethylene oxide (PEO)/Rhodotorula mucilaginosa sp. GUMS16 produced exopolysaccharides (EPS) were prepared using the biaxial electrospinning technique. This study used collagen extracted from the bovine tendon as a natural scaffold, sodium alginate as an absorber of excess wound fluids, and GUMS16 produced exopolysaccharides as an antioxidant. Collagen was characterized using FTIR and EDS analyses. The... 

Purpose: The accuracy of pedicle screw placement during image-guided spine surgery (IGSS) can be characterized by estimating the target registration error (TRE). The major factors that influence TRE were identified, minimized, and verified with in vitro experiments. Materials and methods: Computed-tomography- compatible markers are placed over anatomical landmarks of lumbar vertebral segments in locations that are feasible and routinely used in surgical procedures. TRE was determined directly for markers placed on the pedicles of vertebra segments. First, optimum selections of landmarks are proposed for different landmarks according to the minimum achievable TRE values in different... 

An oxido-peroxido tungsten(VI) complex [WO(O2)L(CH 30H)] using salicylidene benzoyl hydrazine as a tridentate ONO donor Schiff base (H2L) has been synthesized and characterized by elemental analysis, IR, 1H NMR, molar conductance data, and single-crystal X-ray analysis. The complex was used as a catalyst for epoxidation of olefins and oxidation of sulfides. The results show that epoxides and sulfoxides were produced in high yield, turnover number, and selectivity  

The reactions of FeCl3·3H2O and 2-(2′-hydroxyphenyl)-5,6-dihydro-1,3-oxazine (N-O) as a bidentate O, N donor ligand afforded a five-coordinated iron(III) complex, [Fe(N-O) 2Cl], with a distorted trigonal bipyramidal configuration. The complex [Fe(N-O)2Cl] was isolated as an air-stable crystalline solid and was fully characterized, including by single-crystal X-ray structure analysis. The complex [Fe(N-O)2Cl] shows very efficient reactivity in the oxidation of sulfides to their corresponding sulfoxides using urea hydrogen peroxide (UHP) as the oxidant at room temperature under air. To get an insight into the electronic structure of the complex, the experimental studies have been accompanied... 

Fabrication of scaffolds with enhanced mechanical properties and desirable cellular compatibility is critical for numerous tissue engineering applications. This study was aimed at fabrication and characterization of a nanofiber skin substitute composed of collagen (Col)/sodium alginate (SA)/ polyethylene oxide (PEO)/Rhodotorula mucilaginosa sp. GUMS16 produced exopolysaccharides (EPS) were prepared using the biaxial electrospinning technique. This study used collagen extracted from the bovine tendon as a natural scaffold, sodium alginate as an absorber of excess wound fluids, and GUMS16 produced exopolysaccharides as an antioxidant. Collagen was characterized using FTIR and EDS analyses. The... 

A novel binuclear iron(III)-salicylaldazine complex has been synthesized and characterized by various techniques such as IR and UV–Vis spectroscopy and X-ray crystallography. The catalytic oxidation of sulfides in the presence of the aforementioned complex was explored at room temperature using urea hydrogen peroxide (UHP) as an oxidant. Effects of different reaction conditions consisting catalyst and oxidant amount, solvent effect and reaction time on the catalytic activity and selectivity in the reaction of methylphenylsulfide oxidation has been surveyed. Perfect selectivity toward sulfoxide was achieved after 15 min in CH3CN by choice of a properly optimized reaction condition. © 2020... 

The reaction of a solution of MoO2(acac)2 in CH3OH and salicylidene 2-picoloyl hydrazone as a tridentate ONO donor Schiff base (ONO) afford a six-coordinated Mo(VI) complex [MoO2(ONO)(CH3OH)], with a distorted octahedral configuration. [MoO2(ONO)(CH3OH)] was isolated as an air-stable crystalline solid and fully characterized by single-crystal X-ray structure analysis. [MoO2(ONO)(CH3OH)] shows reactivity in the oxidation of sulfides to their corresponding sulfoxides using urea hydrogen peroxide as the oxidant at room temperature under air