Islamic Azad University at Yazd

www.iauyazd.ac.ir
Yazd, Iran
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Shayesteh M.R.,Islamic Azad University at Yazd
Electronic Materials Letters | Year: 2017

We propose a new structure of organic vertical-cavity surface-emitting laser to be pumped electrically. The microcavity structure consists of an organic light emitting diode with field-effect electron transport set in between multilayer dielectric mirrors. The threshold behavior and the dynamics of the proposed OVCSEL are analyzed numerically. We show that the device can reach the lasing threshold under electrical pump at a current density of 24 A/cm2. Also, the dynamic behavior of the device under pulsed excitation is investigated. The results show that pulse excitation reduces field quenching and triplet exciton losses; hence, output photon density can be increased. [Figure not available: see fulltext.] © 2017, The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.


Reza Ahadiat M.,Islamic Azad University at Yazd
Proceedings of the International Conference on Industrial Engineering and Operations Management | Year: 2017

The purpose of this study was to investigate the influence of Islamic Azad University Mehriz Branch on academic, cultural, political and economic Mehriz citizens' views in the academic years 2010-2014 Statistical population of the study consisted of all the citizens Mehrizi academic years 2010-2014 Since society has given way to random sampling of 150 people were chosen. Islamic Azad University Mehriz Branch on academic, cultural, political and economic impact is significant. © IEOM Society International.


Shayesteh M.R.,Islamic Azad University at Yazd
Journal of Electronic Materials | Year: 2017

We investigate the impact of optical excitation in a low-threshold organic semiconductor vertical-cavity surface-emitting laser (OVCSEL) to achieve lasing. We study the threshold behavior and the dynamics of the optimized OVCSEL structure when pumped by both picosecond and nanosecond pulses. The boundary between pulsed and continuous wave lasing is analyzed for the study of annihilation quenching losses in the proposed OVCSEL. Results from numerical simulation show that, for the picosecond pulses excitation case, the singlet–triplet annihilation is not effective and a lasing threshold of about 0.75 μJ cm−2 can be obtained. We show that for the nanosecond pulses pumping case, triplet excitons largely quench singlet excitons and lasing is sustained for a short time following turn-on of the pump. © 2017 The Minerals, Metals & Materials Society


Shateri-Khalilabad M.,Islamic Azad University at Yazd | Yazdanshenas M.E.,Islamic Azad University at Yazd
Carbohydrate Polymers | Year: 2013

In this work, design parameters were investigated for enhancing the conductivity of graphene-coated cotton textiles. Graphene oxide (GO) was immobilized on cotton fabric through a conventional "dip and dry" method. The GO-coated fabrics were then immersed in an aqueous solution of reducing agent, which converted the GO into graphene. The effect of various parameters such as type of reducing agent (NaBH4, N2H 4, C6H8O6, Na2S 2O4 and NaOH) and its concentration, reduction time and number of coating process on conductivity of the fabrics was studied. The mechanical performance of the fabrics was also investigated. The results showed that the best conductivity and mechanical performance were obtained using Na2S2O4 as a reducing agent. The reaction time of 30 min at 95 C was enough for complete reduction of the GO. Electrical conductivity increased by approximately three orders of magnitude with the increase in the number of coating process from 1 to 20 cycles. © 2013 Elsevier Ltd. All rights reserved.


Hashemian S.,Islamic Azad University at Yazd
Main Group Chemistry | Year: 2011

The adsorption of Acid Red 151 (AR151) from water was determined for kaolin, MnFe2O4 and MnFe2O4/kaolin magnetic nano-composite. MnFe2O4 and MnFe 2O4/kaolin were prepared using a simple chemical co-precipitation procedure. The MnFe2O4/kaolin composite was prepared with Mn: Fe: kaolin mass ratios of 1: 1: 10, 1: 1.5: 10 and 1: 2: 10. The adsorption capacity increased in 1: 2: 10 Mn: Fe: kaolin. Powder XRD and SEM were used to characterize the sorbents. The spinel magnetic phase is present in the MnFe2O4. The AR151 adsorption is strongly dependent on pH and increases with increasing acidity with a maximum at pH 2. The adsorption capacity of the composite is greater than that of natural kaolin and MnFe2O4. The adsorption was not affected by the presence of chloride, but was significantly affected by sulfate. The adsorption kinetics of AR151 on kaolin and ferrite powder are similar, but the adsorption of AR151 on the MnFe2O4/kaolin composite is much more rapid and occurs within 2-5 min of contact. The adsorption process follows pseudo-second order kinetics. The solid magnetic composite could be conveniently recovered after adsorption. © 2011 - IOS Press and the authors. All rights reserved.


Tabatabaee M.,Islamic Azad University at Yazd
Acta Crystallographica Section E: Structure Reports Online | Year: 2010

The reaction of Ni(NO3)2·6H2O with pyridine-2,6-dicarboxylic acid, NaOH and 2-amino-pyrimidine in aqueous solution leads to the formation of the title complex, [Ni(C7H 3NO4)(C4H5N3)(H 2O)2]·H2O. The NiII ion is coordinated by one N and two O atoms of the tridentate chelating pyridine-2,6-dicarboxyl-ate anion, one heterocyclic N atom of the 2-amino-pyrimidine ligand, and two water mol-ecules. The resulting geometry for the [NiN2O4] coordination environment can be described as distorted octa-hedral. One uncoord-inated water mol-ecule completes the asymmetric unit. Extensive O - H⋯O and N - H⋯O hydrogen-bonding inter-actions between the NH2 group of 2-amino-pyrimidine, carboxyl-ate groups, and coordinated and uncoordinated water mol-ecules contribute to the formation of a three-dimensional supra-molecular structure.


Yazdanshenas M.E.,Islamic Azad University at Yazd | Shateri-Khalilabad M.,Islamic Azad University at Yazd
Industrial and Engineering Chemistry Research | Year: 2013

Superhydrophobic textiles are materials that have been treated to become resistant to penetration by water and wetting. Such materials have attracted substantial interest because of their high potential for applications in various areas. They are usually made in a two-step coating process: formation of nanoscale roughness on microscale fibers and subsequent hydrophobization by low-surface-energy materials. In this study, a facile one-step ultrasound-assisted approach was developed for the synthesis of silica nanoparticles (SiNPs) functionalized with octyltriethoxysilane and their in situ incorporation into cotton fabrics. The fabrics were tested in terms of water contact angle (CA) and water shedding angle (SHA) and were characterized by SEM, EDX and FTIR spectroscopies, and reflectance spectrophotometry. SEM and AFM images revealed that the functionalized SiNPs formed a nearly close-packed assembly on the fibers and increased the roughness value of the fabric. The fabric showed stable superhydrophobicity with CA and SHA values of 152.8 ± 2.6 and 8, respectively. Reflectance spectra showed that the coating was transparent and could not affect the color of the fabric. In addition, the coating had high stability against repeated washing, and its mechanical properties were not substantially affected. © 2013 American Chemical Society.


Shateri-Khalilabad M.,Islamic Azad University at Yazd | Yazdanshenas M.E.,Islamic Azad University at Yazd
Cellulose | Year: 2013

A simple and versatile method based on cotton cellulose coated with graphene is reported for the fabrication of superhydrophobic and electroconductive textiles. Graphene oxide was deposited on cotton fibers by a dip-pad-dry method followed by reduction with ascorbic acid to yield a fabric with a layer of graphene. The fabric was then reacted with methyltrichlorosilane to form polymethylsiloxane (PMS) nanofilaments on the fibers surface. The surface chemistry and morphology were characterized by UV-visible reflectance spectrophotometry, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and scanning electron microscopy. The water contact angle (CA)/shedding angle (SHA) and resistivity measurements were used for assessing hydrophobicity and conductivity, respectively. The graphene-coated fabric showed hydrophobicity with the CA of 143. 2° ± 2.9° and SHA of 41°. The formation of PMS nanofilaments displayed superhydrophobicity with CA of 163° ± 3.4° and SHA of 7°, which indicated the self-cleaning ability. Conductivity of the graphene-coated fabric was confirmed by the electrical resistivity of 91.8 kΩ/sq which increased to 112.5 kΩ/sq after the formation of PMS nanofilaments. © 2013 Springer Science+Business Media Dordrecht.


Shateri Khalil-Abad M.,Islamic Azad University at Yazd | Yazdanshenas M.E.,Islamic Azad University at Yazd
Journal of Colloid and Interface Science | Year: 2010

We present a facile and effective method to prepare superhydrophobic cotton textiles. Silver particles were produced on cotton fibers by treatment with aqueous KOH and AgNO 3, followed by reduction treatment with ascorbic acid in the presence of a polymeric steric stabilizer to generate a dual-size surface roughness. Further modification of the particle-containing cotton textiles with octyltriethoxysilane led to hydrophobic surfaces. Surfaces prepared showed a sticky property, which exhibits a static water contact angle of 151° for a 10μL droplet that water drop did not slid off even when the sample was held upside down. The modified cotton has potent antibacterial activity toward both Gram-positive and Gram-negative bacteria. The Ag particles were uniformly and stably distributed on the substrate surface and killed bacteria. These modified cotton textiles are potentially useful; as superhydrophobic antibacterial fabrics in a wide variety of biomedical and general use applications. © 2010 Elsevier Inc.


Hashemian S.,Islamic Azad University at Yazd
African Journal of Biotechnology | Year: 2010

Magnetic MnFe2O4/bentonite nanocomposite was synthesized by chemical co-precipitation method. The product was characterized by X-ray diffraction (XRD) and Scanning electron microscope (SEM). XRD results indicated the presence of free quartz in bentonite. The magnetic ferrite MnFe2O4 has spinel structure. It is also found that the presence of bentonite in the magnetic composite has not made any changes in the spinel structure of MnFe2O4. SEM images of the sorbent shows nanocomposite with a uniform structure and nanochannels from 0.3 to 0.8 mμ in diameter having a surface area of 130 m2 g-1. The results also revealed that the composite has much higher catalytic activity than the bentonite. The process confirmed very fast kinetic and pseudo-second-order model for acid red 138 (AR138) from aqueous solutions. The adsorption of AR138 was strongly dependent on the pH of the medium, where the removal efficiency increased as the pH decreased in pH 2. © 2010 Academic Journals.

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