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The quenching of silver rod in boiling carbon nano tube-water nanofluid
, Article International Journal of Thermal Sciences ; Volume 75 , 2014 , Pages 95-104 ; ISSN: 12900729 ; Saboonchi, A ; Shafii, M. B ; Sharif University of Technology
Abstract
It is well established that nanofluids increase or decrease heat transfer in boiling phenomenon. The study acquired Quenching curve and boiling curve in two different surface roughnesses in two fluids: deionized water and the nanofluid MWCNT-water with four different concentrations. The cylinder was made of silver and two surface roughnesses of 129 and 690 nm. It was heated up and soaked in the fluid mentioned above. Temperature was recorded by a drilled to install thermocouple. The experiment was replicated in five times. To calculate the heat transfer quotient, assuming the cylinder to be thermally homogeneous, the Lumped capacity method was applied. The obtained results during quenching...
Selective and sensitive fluorescent chemosensor based on N2O2-donor naphthodiaza-crown macrocyclic ligands for detection of Cu(II), and Zn(II)
, Article Journal of Photochemistry and Photobiology A: Chemistry ; April , 2016 ; 10106030 (ISSN) ; Zarepour jevinani, M ; Kubicki, M ; Sharif University of Technology
Elsevier
2016
Abstract
Fluorescence spectroscopy of a series of N2O2-donor naphthodiaza-crown macrocyclic ligands, L1-L4 , in ethanol revealed that Cu(II) cation had remarkable fluorescence quenching effect during complex formation with L2 and L3 , while Zn(II) displayed noticeable enhancement on the fluorescence emission of L1 and L4 , respectively. Fluorescence quantum yields of Ln (L1-L4 ) as well as their complexes Ln /M (II) (M=Cu, and Zn) were found as 0.11-0.34, respectively. The complementary experiments on determination of the limit of detection indicated (LOD) that L2 and L3 were highly selective for detection of Cu(II) while L1 and L4 were selective towards Zn(II), respectively. Using Benesi-Hildebrand...
Photoluminescence and electrochemical investigation of curcumin-reduced graphene oxide sheets
, Article Journal of the Iranian Chemical Society ; Volume 15, Issue 2 , February , 2018 , Pages 351-357 ; 1735207X (ISSN) ; Ahadian, M. M ; Iraji zad, A ; Akhavan, O ; Jokar, E ; Sharif University of Technology
Springer Verlag
2018
Abstract
This paper reports on a novel low-temperature method for preparing curcumin-reduced graphene oxide (Cur-rGO) from graphene oxide (GO) and investigates their cyclic voltammetry (CV) and photoluminescence (PL) properties. GO sheets were synthesized using modified Hummers’ method and then were chemically reduced using polyphenol curcumin into graphene sheets. Atomic force microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy were used to confirm the formation of Cur-rGO and revealed their functionalization with polyphenol curcumin. The electrochemical and optical properties of the Cur-rGO sheets were investigated using CV and PL spectroscopy. According to the PL and...
Selective and sensitive fluorescent chemosensor based on N2O2-donor naphthodiaza-crown macrocyclic ligands for detection of Cu(II), and Zn(II)
, Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 356 , 2018 , Pages 689-699 ; 10106030 (ISSN) ; Zarepour Jevinani, M ; Kubicki, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Fluorescence spectroscopy of a series of N2O2-donor naphthodiaza-crown macrocyclic ligands, L1-L4, in ethanol revealed that Cu(II) cation had remarkable fluorescence quenching effect during complex formation with L2 and L3, while Zn(II) displayed noticeable enhancement on the fluorescence emission of L1 and L4, respectively. Fluorescence quantum yields of Ln (L1-L4) as well as their complexes Ln/M (II) (M = Cu, and Zn) were found as 0.11–0.34, respectively. The complementary experiments on determination of the limit of detection indicated (LOD) that L2 and L3 were highly selective for detection of Cu(II) while L1 and L4 were selective towards Zn(II), respectively. Using Benesi–Hildebrand...
Robust fluorogenic non-porphyrin interaction of Zn(II) and Hg(II) naphthadiaza-crown macrocyclic complexes with C60: Spectroscopic and dispersion-corrected DFT study
, Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 418 , 2021 ; 10106030 (ISSN) ; Zarepour jevinani, M ; Mohammadzadeh, A. H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
A family of Zn(II) complexes with naphthadiaza-crown macrocyclic host molecules (Ln = L1-L4) were prepared and characterized employing mass spectrometry, elemental microanalysis, 1H, 13C NMR, IR, UV–vis, fluorescence spectroscopy. The fluorescence study on [M(II)Ln]2+(M = Zn with n = 1–4, Hg with n = 5) complexes denoted on the presence of a notable selective supramolecular interaction with C60 in two different solvents, namely N-Methyl-2-pyrrolidone (NMP) and chloroform for both [Zn(II)L4]2+ and [Hg(II)L5]2+. Employing both UV–vis and fluorescence spectroscopy, 1:1 mol ratio were determined for [M(II)Ln]2+/C60 by applying the Job's plots. Comparing with their free ligands Ln interactions,...
Study of Quantum Quench in Some Simple Quantum Mechanical Systems
, M.Sc. Thesis Sharif University of Technology ; Rouhani, Shahin (Supervisor)
Abstract
Classical quench is the act of sudden change in the temperature of a system. This process is not new and has been used in some branches of science, like the smithing industry to produce a hard and stiff metal objects. Quantum Quench is the deformation of system's Hamiltonian in short time interval. This quantum version of quench is around for a few years and has attracted a lot of attention after its experimental realization in Ultracold Atoms setup. Suppose we have hamiltonian which depends on the constant g_0 which is the dynamical parameter of the system. It could be interaction strength between elements in the system or the external electric field amplitude on the system. At an arbitrary...
Stochastic ensemble pruning method via simulated quenching walking
, Article International Journal of Machine Learning and Cybernetics ; Volume 10, Issue 7 , 2019 , Pages 1875-1892 ; 18688071 (ISSN) ; Akhavan Niaki, S. T ; Niknamfar, A. H ; Sharif University of Technology
Springer Verlag
2019
Abstract
Inspired by an upward stochastic walking idea, a new ensemble pruning method called simulated quenching walking (SQWALKING) is developed in this paper. The rationale behind this method is to give values to stochastic movements as well as to accept unvalued solutions during the investigation of search spaces. SQWALKING incorporates simulated quenching and forward selection methods to choose the models through the ensemble using probabilistic steps. Two versions of SQWALKING are introduced based on two different evaluation measures; SQWALKINGA that is based on an accuracy measure and SQWALKINGH that is based on a human-like foresight measure. The main objective is to construct a proper...
Spectroscopic Study and Characterizing of Selenium Dioxide Complex with Pyridoxine(PN-Se):Interaction Between (PN-Se)and Bovine Serum Albumin
, M.Sc. Thesis Sharif University of Technology ; Mohamadi Boghaei, Davar (Supervisor)
Abstract
Temporary existence of some molecules like medicines in body and also existence of diagnostic agents in biological systems and study of the interactions of biomolecules with these agents is a matter of interest. It also may have an important role in design and synthesis of new drugs. Serum Albumin is the most abundant protein in circulation system in the body. So far, many studies about the interaction of this protein with different compounds have been undertaken. The aim of this paper was to synthesize selenium complex and analyze its potential biochemical activity in vitro. The concrete work falls into two parts:(1) to synthesize the selenium-pyridoxine compound (PNSe) (2) to probe into...
Quick speciation of iron(II) and iron(III) in natural samples using a selective fluorescent carbon dot-based probe
, Article Analytical Methods ; Volume 8, Issue 20 , 2016 , Pages 4064-4068 ; 17599660 (ISSN) ; Taghipour, M ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
A new, simple and rapid carbon dot (CD) based fluorescent probe for speciation of Fe2+ and Fe3+ ions was developed. The as-prepared CDs contain phenol groups on their surfaces and due to the special coordination interaction of phenol groups with Fe3+ ions, this sensing system exhibits excellent sensitivity and selectivity toward Fe3+. In order to detect Fe2+ ions as well, a specific amount of H2O2 was introduced to the detection system to transform Fe2+ to Fe3+ of which the latter is the determinable form of iron. Under the optimum experimental conditions, the fluorescence intensity of the sensor decreased as the Fe3+ ion concentration increased. The relationship plot between the...
Modeling of Micro Combustion Applying Electrohydrodynamics Effects
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor) ; Mozafari, Ali Asghar (Supervisor)
Abstract
In this project, one-dimensional and two-dimensional numerical approaches are used to study the effect of applying electrohydrodynamics on the temperature and species mass fraction profiles along the micro-combustor. A premixed mixture of H2-Air with a multi-step chemistry (9 species and 19 reactions) is used and thermal conductivity of the mixture is considered as a function of species thermal conductivity and temperature by using a set of new relations. Both thermal and radical quenching mechanisms are important in the micro-scale combustion due to increasing of area-to-volume ratio and significant heat loss from the combustor walls. By inserting a number of electrodes into the...
Annealed and quenched disorder in sand-pile models with local violation of conservation
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 92, Issue 2 , August , 2015 ; 15393755 (ISSN) ; Sebtosheikh, M ; Sharif University of Technology
American Physical Society
2015
Abstract
In this paper we consider the Bak, Tang, and Wiesenfeld (BTW) sand-pile model with local violation of conservation through annealed and quenched disorder. We have observed that the probability distribution functions of avalanches have two distinct exponents, one of which is associated with the usual BTW model and another one which we propose to belong to a new fixed point; that is, a crossover from the original BTW fixed point to a new fixed point is observed. Through field theoretic calculations, we show that such a perturbation is relevant and takes the system to a new fixed point
Supramolecular dyad derived from a buckybowl series of O2N2-donor naphthodiaza-crowns coordinated to C60: photophysical, NMR and theoretical studies
, Article Supramolecular Chemistry ; Volume 29, Issue 4 , 2017 , Pages 248-258 ; 10610278 (ISSN) ; Zarepour jevinani, M ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
Supramolecular complexation of C60 with L1-L5 were studied in toluene, chloroform and 1,2-dichlorobenzene solvents using UV–vis, fluorescence, 1H, 13C NMR spectroscopy as well as density functional theory (DFT) calculations. The Job’s plot of continuous variation method established 1:1 stoichiometry for L1-L5/C60. Binding constants (K) calculated for L1-L5/C60 were also determined employing UV–vis and fluorescence spectroscopy. Both steady-state and time-resolved fluorescence spectroscopic surveys showed remarkable fluorescence quenching phenomenon for L1-L5 in the presence of C60 which was primarily attributed to involvement of a static process. The observed fluorescence quenching in L1–L5...
The study of magnetic field implementation on cylinder quenched in boiling ferro-fluid
, Article Applied Thermal Engineering ; Volume 64, Issue 1-2 , March , 2014 , Pages 331-338 ; ISSN: 13594311 ; Saboonchi, A ; Shafii, M. B ; Jahani, N ; Sharif University of Technology
Abstract
It has been shown that nanofluids in different investigations increase or decrease heat transfer rate in boiling phenomenon. The present study examined the effects of ferro-fluid concentrations and magnetic field implementation on the fluid throughout the boiling process. Obtained are the quenching curve and boiling curve on specified surface roughness in both water and ferro-fluid with two different concentrations. A silver cylinder with Aspect ratio of 10, and surface roughness of 689 nm was heated up to 350 C and then was overwhelmed in the fluid under study. Temperatures were measured by a thermocouple which installed in the center of the cylinder. The test was carried out 5 times. The...
MoS2 quantum-dots as a label-free fluorescent nanoprobe for the highly selective detection of methyl parathion pesticide
, Article Analytical Methods ; Volume 9, Issue 4 , 2017 , Pages 716-723 ; 17599660 (ISSN) ; Rashti, A ; Hormozi Nezhad, M. R ; Mahdavi, V ; Sharif University of Technology
Royal Society of Chemistry
2017
Abstract
A reliable, simple, and sensitive fluorescence method was developed for the determination of methyl parathion (MP) in rice using MoS2 quantum dots (QDs). Rapid hydrolysis of MP under alkaline conditions, and thus the formation of p-nitrophenol (p-NP) can be used for MP detection. The functional mechanism of the nanoprobe relies on p-nitrophenol-induced photoluminescence quenching of MoS2 QDs. The high probability of resonance energy transfer (RET) stems from the spectral overlap of MoS2 QD emission spectra and the absorption spectra of p-NP. The high value of the Stern-Volmer constant (KSV = 3.73 × 104 M-1) suggests the efficient quenching of MoS2 QDs by MP in the course of the ET process....
Air quenching as a reliable technique to obtain colossal dielectric constant with low loss in (In, Nb)-co doped TiO2
, Article Materials Letters ; Volume 267 , May , 2020 ; Mahmoudi, P ; Karimi, A ; Sharif University of Technology
Elsevier B. V
2020
Abstract
In this research, for the first time, the effect of air quenching on the microstructural and electrical properties of (In, Nb) co-doped TiO2 was investigated. The FE-SEM images showed that the air quenching has no effect on microstructure of co-doped TiO2. However, air quenching affected the electrical properties so that the dielectric constant in the frequency of 1 kHz at room temperature sharply enhanced from 21*103 to 26*104 and the dielectric loss surprisingly decreased from 0.6 to 0.1. This incredible improvement in the dielectric properties is attributed to the electron-pined defect dipoles which has been activated through air quenching. © 2020 Elsevier B.V
An Investigation into the Kinetics of Quench Aging in an Mg-Zn Alloy
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
Special features of magnesium such as low density, perfect bio-compatibility in the human body, and close elastic modulus to the human bone have increased the use of Mg alloys in the bio-medical applications. Nevertheless, low mechanical properties and poor corrosion resistance of Mg alloys have limited their bio-medical applications. The addition of alloying elements together with the use of precipitation hardening and plastic deformation are the most effective methods to improve the mechanical properties and increase the corrosion resistance of Mg alloys. Thus, the present research with the aim of improving the mechanical properties of an Mg-Zn alloy by Ca and Gd additions together with...
Patterned and disordered continuous abelian sandpile model
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 80, Issue 4 , 2009 ; 15393755 (ISSN) ; Moghimi Araghi, S ; Sharif University of Technology
2009
Abstract
We study critical properties of the continuous Abelian sandpile model with anisotropies in toppling rules that produce ordered patterns on it. Also, we consider the continuous directed sandpile model perturbed by a weak quenched randomness, study critical behavior of the model using perturbative conformal field theory, and show that the model has a random fixed point. © 2009 The American Physical Society
High temperature mechanical properties of triple phase steels
, Article Materials Letters ; Volume 61, Issue 4-5 , 2007 , Pages 1023-1026 ; 0167577X (ISSN) ; Sharif University of Technology
2007
Abstract
A 0.15% C-1.2% Si-1.7% Mn steel was intercritically annealed at 780 °C for 5 min and then isothermally held at 400 °C for 4 min followed by oil quenching to room temperature and the annealed microstructure consist of 75% ferrite, 15% bainite and 10% retained austenite was produced. Samples of this steel with triple phase structure were tensile tested at temperature range of 25-450 °C. Stress-strain curves showed serration flow at temperature range of 120-400 °C and smooth flow at the other temperatures. All of the stress-strain curves showed discontinuous yielding at all testing temperatures. Both yield and ultimate tensile strength decreased with increasing temperature, but there exists a...
Itinerant electron transport in microscopically inhomogeneous magnetic fields
, Article Journal of Magnetism and Magnetic Materials ; Volume 299, Issue 2 , 2006 , Pages 356-361 ; 03048853 (ISSN) ; Nogaret, A ; Atkinson, D ; Ghorbani, M ; Iraji Zad, A ; Sharif University of Technology
2006
Abstract
We report on magnetoresistance measurements in thin nickel films modulated by a periodic magnetic field emanating from micromagnetic arrays fabricated at the film surface. By increasing the strength of the magnetic potential using nickel and dysprosium micromagnets, we are able to quench the anisotropic magnetoresistance (AMR) in the film. © 2005 Elsevier B.V. All rights reserved
An Investigation Into the Aging Kinetics of a Heat Resistant Stainless Steel
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
The austenitic heat resistant stainless steels have been widely used in petrochemical industry as furnace tubes which are exposed to extremely high temperatures. In this study, the quench aging process of a HP modified heat resistant stainless steel is assessed and the kinetics of aging is evaluated by the JMAK model. The microstructure of steel in as cast and aged conditions was characterized by optical microscope and scanning electron microscope equipped with EDS. The effects of aging time and temperature on the microstructure, tensile propertices, shear strength, hardness, and ductility of the aged steel were determinded. The results of tensile and shear punch tests show a linear...