Islamic Azad University

About: Islamic Azad University is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Population & Catalysis. The organization has 83635 authors who have published 113437 publications receiving 1275049 citations. The organization is also known as: Azad University.

Fuzzy fractional differential equations under generalized fuzzy Caputo derivative

Abstract: In this paper the fuzzy Caputo fractional differential equation FCFDE under the Generalized Hukuhara differentiability is introduced. Also the existence and uniqueness of the solution for a class of fuzzy Caputo fractional differential equation with initial value is studied, and an analytical solution of FCFDE is obtained. The related theorems and properties are proved in detail and the method is illustrated by solving some examples.

Phase-change heat transfer in a cavity heated from below: The effect of utilizing single or hybrid nanoparticles as additives

Abstract: The present study deals with the effects of hybrid nanoparticles on the melting process of a nano-enhanced phase-change material (NEPCM) inside an enclosure. The bottom side of the cavity is isothermal at a hot temperature while the top wall is isothermal at a cold temperature and the left and right walls are insulated. The governing partial differential equations are first non-dimensional form and then solved using the Galerkin finite element method. Some of the dimensionless parameters are kept constant such as the Prandtl number, the Rayleigh number, the Stefan number and the ratio between the thermal diffusivity of the solid and liquid phases while the volume fraction of nanoparticles, the conductivity and viscosity parameters, and the Fourier number are altered. It is found out that increasing the values of the nanoparticles volume fraction, viscosity and conductivity parameters leads to significant variations in the solid-liquid interface for large values of Fourier number. Moreover, increasing the conductivity parameter and decreasing the viscosity parameter at the same time can cause an augmentation in the liquid fraction.

A novel nanosensor based on Pt:Co nanoalloy ionic liquid carbon paste electrode for voltammetric determination of vitamin B9 in food samples

Abstract: In this work we describe a novel nanoalloy (Pt:Co) room temperature ionic liquid (RTIL) modified carbon paste electrode as a high sensitive sensor for voltammetric determination of vitamin B 9 in food samples. The sensor exhibits an enhanced effectiveness for the electro-oxidation of vitamin B 9 in aqueous solution. The oxidation peak potential for this matter at a surface of the ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) Pt:Co carbon paste electrode (Pt:Co/IL/CPE) appeared at 685 mV that was about 110 mV lower than the oxidation peak potential at the surface of the traditional carbon paste electrode (CPE) under similar condition. The mechanism of the electro-oxidation process on the surface of the modified electrode was analyzed. Square wave voltammetry (SWV) was applied as a very sensitive electrochemical method for the determination of sub-micro-molar amounts of vitamin B 9 . The linear response range and detection limit were found to be 1.0 × 10 −7 to 5.0 × 10 −4 M and 4.0 × 10 −8 M, respectively. The prepared modified electrode shows several advantages such as simple preparation method, high stability, high sensitivity, and excellent catalytic activity, long-term stability and remarkable voltammetric reproducibility for eletrooxidation of vitamin B 9 . The proposed sensor was successfully applied for the determination of vitamin B 9 in food samples.

Electrochemical preparation of α-Ni(OH) 2 ultrafine nanoparticles for high-performance supercapacitors

Abstract: Well-dispersed nanoparticles of nickel hydroxide were prepared via a simple electrochemical method Electrodeposition experiments were performed from 0005 M Ni(NO3)2 bath at a constant current density of 01 mA cm−2 on the steel cathode for 1 h Recording the potential values during the deposition process revealed that the reduction of water has major role in the base electrogeneration at the applied conditions The obtained deposit was characterized by the X-ray diffraction (XRD), infrared (IR), differential scanning calorimeter–thermogravimetric analysis, carbon–nitrogen–hydrogen (CHN), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques The CHN, XRD, and IR analyses showed that the obtained deposit has α phase of Ni(OH)2 with intercalated nitrate ions in its structure Morphological characterization by SEM and TEM revealed that the prepared α-Ni(OH)2 is composed of well-dispersed ultrafine particles with the size of about 5 nm The supercapacitive performance of the prepared nanoparticles was analyzed by means of cyclic voltammetry and galvanostatic charge–discharge tests The electrochemical measurements showed an excellent supercapacitive behavior of the prepared α-Ni(OH)2 nanoparticles It was also observed that the α-Ni(OH)2 ultrafine particles have better electrochemical characteristic and supercapacitive behavior than β-Ni(OH)2 ultrafine nanoparticles, including less positive charging potential, lower E a − E c value, better reversibility, higher E OER − E a, higher utilization of active material, higher proton diffusion coefficient, greater discharge capacity, and better cyclability These results make the α-Ni(OH)2 nanoparticles as an excellent candidate for the supercapacitor materials