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Development of an Optimal Technique to Construct the Energy Spectrum of the Hpge Detector Using the Output Spectrum of the Nai Detector, with the Help of Soft Computing Algorithms
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor)
Abstract
Gamma ray spectroscopy has a special place in the industrial applications of nuclear radiation. Currently, the most common device for gamma ray detection and spectroscopy is the sodium iodide scintillation detector. Long life and high efficiency and reasonable price of these detectors are the reasons for the development of the use of these detectors in industries and laboratories. But these detectors in the classification of energy sensitive detectors are considered as detectors with low resolution. The presence of broad peaks in the gamma ray spectrum of this detector increases the possibility of interference of peaks related to different energies and makes it difficult to identify the...
Characterization of Micromixing and Determination of Mass-Transfer Coefficient in a new Double-Spinning-Disk Contactor
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
High mixing efficiency and high liquid-liquid mass transfer rate are two key features of spinning disk contactors. This work presents the experimental investigation of mixing and liquid-liquid mass transfer characteristics in a new double coaxial spinning disks contactor. The micromixing efficiency was investigated using a standard system of competitive parallel reaction known as iodide/iodate test reaction. The influences of various operating conditions such as the rotational speed of the disks, the direction of rotation, the feed radial location, the feed distribution pattern, the distance between the disks, and the feed flow rate on the mixing quality were examined carefully. The obtained...
Influences of Magnetic Nanoparticles and Magnetic Field on the Performance of the Redox Flow Batteries
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor) ; Gharibi, Hossein (Supervisor)
Abstract
The novel concept of using magnetic nanofluidic electrolyte for redox flow batteries (RFBs) is demonstrated for the first time. In this regard, the stable magnetic nanofluidic electrolytes are prepared by dispersing magnetic modified multiwalled carbon nanotubes (MMWCNTs) in the positive electrolyte of a polysulfide-iodide redox flow battery at mass concentrations of less than 0.3 g L−1. The electrochemical behavior of magnetic nanofluidic electrolyte was examined using cyclic voltammetry at different mass concentrations of MMWCNTs with a carbon felt electrode. Higher and stable peak current densities were observed at larger mass concentrations of MMWCNTs. A polysulfide-iodide redox flow...
Synthesis and Stability Improvement of Perovskite QDs for Optoelectronic Devices
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdol Reza (Supervisor)
Abstract
In the last years, perovskite QDs have emerged as the novel candidate due to their unique optical properties such as high-absorption coefficient, long-range charge transport, low exciton-binding energy, and etc. Nonetheless, poor stability of perovskite in ambient conditions made researchers to consider this issue. Recently, amoung various types of organic-inorganic perovskites, Formamidinium lead iodide has attracted tremendous attention due to its near IR absorption wavelength in addition to the higher stability compared to MAPbI3. In this work, FAPbI3 perovskite stability improvement was investigated by several methods under different conditions. In the first step, FAPbI3 QDs colloidal...
Modeling and Simulation of Micromixing Phenomenon in a New Double-Spinning-Disc Reactor
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
Mixing efficiency is an important performance indicator in many chemical reactors. In the present study, using a computational fluid dynamics model, the quality of micromixing in a double-disk-spinning reactor with the ability to rotate both disks using a fast iodide-iodate competitive reaction has been investigated. The purpose of this study was to investigate the effect of operational parameters such as the speed and direction of rotation of disks, radius and number of entry points of one feed, distance between disks, volumetric flow of feed, feed inlet nozzle diameter and acid concentration (H+) on quality of micromixing. The simulation results show that by increasing the rotation speed...
Synthesis of AgI Nanoparticle in a New SDR
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
In this study, low-cost and simple method of precipitation or reactive crystallization was used to synthesize nanoparticles of silver iodide. For this purpose, the reaction of silver nitrate and potassium iodide along with several surfactants in a rotating disk reactor at ambient temperature and pressure was applied. In addition, the effects of hydrodynamic conditions such as diameter and rotating speed of the disk, feed flow rate, and feed injection location, with some of the effective kinetic parameters in the synthesis such as the concentration of the reactants, type and concentration of the surfactants and free ion ratio and aging time of solutions using dynamic light scattering analysis...
Investigation the Effect of Formamidinium Lead Halide on the Stability and Performance of Graphene Phototransistors Based on Lead Sulfide
, Ph.D. Dissertation Sharif University of Technology ; Simchi, Abdolreza (Supervisor)
Abstract
Enhancing the detection range, sensitivity and stability of phototdetectors due to their vast applications are in great importance. In recent years, Lead sulfide quantum dots, in order to their absorption over a wide range of wavelengths including Near-infrared (NIR), multiple exciton generation effect and solution processability are promising materials.However, long organic surface ligands which are necessary in synthesis process can suppress the carrie transport and the common method to overcome this weakness, is ligand exchange process. In this way, using short organic ligands because of their low electron mobility and methylammonium lead iodide ligands in order to their instability,...
All inorganic cesium lead iodide perovskite nanowires with stabilized cubic phase at room temperature and nanowire array-based photodetectors
, Article Nano Letters ; Volume 17, Issue 8 , 2017 , Pages 4951-4957 ; 15306984 (ISSN) ; Tavakoli, M. M ; Gu, L ; Hussain, S ; Zhang, D ; Poddar, S ; Wang, Z ; Zhang, R ; Fan, Z ; Sharif University of Technology
Abstract
Alluring optical and electronic properties have made organometallic halide perovskites attractive candidates for optoelectronics. Among all perovskite materials, inorganic CsPbX3 (X is halide) in black cubic phase has triggered enormous attention recently owing to its comparable photovoltaic performance and high stability as compared to organic and hybrid perovskites. However, cubic phase stabilization at room temperature for CsPbI3 still survives as a challenge. Herein we report all inorganic three-dimensional vertical CsPbI3 perovskite nanowires (NWs) synthesized inside anodic alumina membrane (AAM) by chemical vapor deposition (CVD) method. It was discovered that the as-grown NWs have...
Iodide-selective electrode based on copper phthalocyanine
, Article Electroanalysis ; Volume 14, Issue 23 , 2002 , Pages 1621-1628 ; 10400397 (ISSN) ; Taghani, A ; Moattar, F ; Sharif University of Technology
2002
Abstract
Copper phthalocyanine was used as ion carrier for preparing polymeric membrane selective sensor for detection of iodide. The electrode was prepared by incorporating the ionophore into plasticized poly(vinyl chloride) (PVC) membrane, coated on the surface of graphite electrode. This novel electrode shows high selectivity for iodide with respect to many common inorganic and organic anions. The effects of membrane composition, pH and the influence of lipophilic cationic and anionic additives and also nature of plasticizer on the response characteristics of the electrode were investigated. A calibration plot with near-Nernestian slope for iodide was observed over a wide linear range of five...
Analysis of complex gamma-ray spectra using particle swarm optimization
, Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment ; Volume 911 , 2018 , Pages 123-130 ; 01689002 (ISSN) ; Vosoughi, N ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Analysis of gamma-ray spectra is an important step for identification and quantification of radionuclides in a sample. In this paper a new gamma-ray spectra analysis algorithm based on Particle Swarm Optimization (PSO) is developed to identify different isotopes of a mixed gamma-ray source and determine their fractional abundances. PSO is an iterative algorithm that imitates the social behaviors observed in nature to solve complex optimization problems. The PSO method is used for complex fitting to the response of a 3 [Formula presented] 3 inch NaI (Tl) scintillation detector and the fitting process is controlled by a test for significance of abundance and computation of Theil coefficient....
Processing scintillation gamma-ray spectra by artificial neural network
, Article Journal of Radioanalytical and Nuclear Chemistry ; Volume 325, Issue 2 , 2020 , Pages 471-483 ; Vosoughi, N ; Saheli, F ; Sharif University of Technology
Springer Netherlands
2020
Abstract
Elemental analysis can be performed using obtained gamma-ray spectrum of the sample under study. In this work, simple Multi-Layer Perceptron (MLP) neural network models are proposed for analyzing a gamma-ray emitting sample using whole information of its obtained gamma-ray spectrum. Elemental analysis is performed in two fields of study using 3 × 3 inch NaI(Tl) detectors: Radio-Isotope Identification (RIID) and Prompt Gamma Neutron Activation Analysis (PGNAA). The gamma-ray point sources are used for an empirical study in RIID field, while a Monte Carlo simulation study is considered for determining chlorine and water content of crude oil using combination of PGNAA technique and a MLP model....
Vapor assisted deposition of alkaline doped perovskites: Pure phase formation of CsxMA1−xPbI3
, Article Electrochimica Acta ; Volume 259 , 2018 , Pages 485-491 ; 00134686 (ISSN) ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Alkaline doping (Cs, Rb) in CH3NH3PbI3 (MAPbI3) is known to enhance the stability of perovskite solar cells. The films are usually deposited using anti-solvent method, which is tricky and not applicable for large scale deposition. Besides, in case of CsxMA1−xPbI3 the amount of Cs must be carefully controlled to prevent CsI phase formation. Herein, we report an atmospheric pressure vapor assisted solution process (AP-VASP) for the growth of Cs doped MAPbI3 perovskite films that features highly uniform morphology, pin-hole free films, large grain size, as well as being scalable. The CsxMA1−xPbI3 films are formed by the reaction of Cs doped PbI2 films with MAI vapor in a simple oven. We...
Facile template-free synthesis of new α-MnO2 nanorod/silver iodide p-n junction nanocomposites with high photocatalytic performance
, Article New Journal of Chemistry ; Volume 44, Issue 18 , 2020 , Pages 7401-7411 ; Kohantorabi, M ; Sharif University of Technology
Royal Society of Chemistry
2020
Abstract
In the present study, a novel α-MnO2/AgI photocatalyst was successfully fabricated by using hydrothermal/precipitation methods, and its photocatalytic performance was evaluated from the degradation of Acid blue 92 (AB92) dye under visible light irradiation. The surface and crystalline structure, morphology, and electro-chemical properties of the as-made photocatalyst were investigated by BET, XRD, XPS, SEM-EDS, TEM, DRS, PL, PC, and Raman analysis. The optimized nanocomposite (α-MnO2/AgI) with a weight ratio of 1:15 showed the best photocatalytic activity in the decomposition of AB92 with a removal efficiency of 100% in 40 min which was better than that of pure α-MnO2 (48%) and AgI (61%),...
Synthesis of poly-substituted thiophenes in the realm of sulfonylketenimines chemistry
, Article Journal of Sulfur Chemistry ; Volume 41, Issue 2 , 2020 , Pages 146-153 ; Sedaghat, A ; Nematpour, M ; Jahani, M ; Tabatabai, S. A ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
An efficient synthesis of highly substituted thiophenes was developed by means of sulfonylketenimines in a multi-step reaction including heterocumulene system containing sulfur and nitro-alkanes with acidic α-hydrogen. The speed and ease of conducting this four-component reaction under mild conditions and using available materials makes it an ideal method to synthesize high purity substituted thiophenes with sulfonamide moiety. All structures synthesized are confirmed by the instrumental analysis (EI-MS, IR and 1H /13C-NMR). © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group
Engineering of perovskite materials based on formamidinium and cesium hybridization for high-efficiency solar cells
, Article Chemistry of Materials ; Volume 31, Issue 5 , 2019 , Pages 1620-1627 ; 08974756 (ISSN) ; Runjhun, R ; Tavakoli, M. M ; Yadav, P ; Saski, M ; Alanazi, A. Q ; Kubicki, D. J ; Kaszkur, Z ; Zakeeruddin, S. M ; Lewiński, J ; Grätzel, M ; Sharif University of Technology
American Chemical Society
2019
Abstract
Engineering the chemical composition of inorganic-organic hybrid perovskite materials is an effective strategy to boost the performance and operational stability of perovskite solar cells (PSCs). Among the diverse family of ABX3 perovskites, methylammonium-free mixed A-site cation CsxFA1-xPbI3 perovskites appear as attractive light-absorber materials because of their optimum band gap, superior optoelectronic property, and good thermal stability. Here, we develop a simple and very effective one-step solution method for the preparation of high-quality (Cs)x(FA)1-xPbI3 perovskite films upon the addition of excess CsCl to the FAPbI3 precursor solution. It is found that the addition of CsCl as a...
Cellulose-immobilized NHC-Cu(i) complex: An efficient and reusable catalyst for multicomponent synthesis of 1,2,3-triazoles
, Article RSC Advances ; Volume 5, Issue 120 , Nov , 2015 , Pages 99498-99501 ; 20462069 (ISSN) ; Habibi, Z ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
A novel cellulose supported copper NHC complex has been prepared by the reaction of cellulose supported imidazolium salt with copper(i) iodide. The catalyst is active in the synthesis of 1,2,3-triazoles via a one-pot reaction of alkyl/benzyl halides or tosylates and terminal alkynes, with sodium azide in water
Simultaneous alpha and gamma discrimination with a phoswich detector using a rise time method and an artificial neural network method
, Article Applied Radiation and Isotopes ; Volume 154 , 2019 ; 09698043 (ISSN) ; Feghhi, S. A. H ; Moghadam, S. R ; Zamzamian, S. M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
We used two digital methods—rise time discrimination (RTD) and an artificial neural network (ANN)—to simultaneously discriminate alpha particles and gamma rays detected by a phoswich detector (50 μm BC-400 coupled to 3 mm CsI(Tl)). The results for 10,000 pulses discriminated by the RTD method showed that the rise time distribution of the pulses is rather vast (between 200 and 800 ns for gamma rays and less than 40 ns for alpha particles). The same result was also observed in the dual-parameter diagram (pulse rise time versus area under the pulse) for an 241Am source. Then, as another approach, three pulse features—rise time, pulse height ratio, and charge ratio—were extracted from 2000...
Sensitivity analysis of the efficiency of Compton camera to the detector parameters using the GEANT4 computer code
, Article Applied Radiation and Isotopes ; Volume 176 , 2021 ; 09698043 (ISSN) ; Hosseini, S. A ; Loushab, M. E ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Compton imaging is an imaging technique in which Compton scattering is used to produce images from a gamma-ray source. Compton imaging systems are also known as Compton camera. The basic design of Compton imaging systems consists of two-position detectors that are sensitive to the position and energy scattered from gamma rays. Compton camera efficiency is defined as the fraction of photons entering the scatterer (disperse) detector that undergoes only one Compton scattering and is then photoelectrically absorbed in the absorber detector. In the present study, the efficiency of a Compton camera was investigated based on semiconductor detectors using the GEANT4 simulation toolkit. In this...
Ultrasound-assisted synthesis of highly functionalized benzo[1,3]thiazine via Cu-catalyzed intramolecular C–H activation reaction from isocyanides, aniline-benzoyl(acetyl) isothiocyanate adduct
, Article Ultrasonics Sonochemistry ; Volume 50 , 2019 , Pages 1-5 ; 13504177 (ISSN) ; Rezaee, E ; Jahani, M ; Tabatabai, S. A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
A facile sonochemical route for the synthesis of benzo[1,3]thiazine derivatives via a one pot, multicomponent, intramolecular C–H activation reaction from isocyanides, aniline and benzoyl (acetyl) isothiocyanate adduct catalyzed by copper (I) iodide in acetone at 30 °C have been reported. The advantages of the described method include using simple and readily available starting materials and performing under mild copper-catalytic reaction conditions and also obtaining pure product with high yield without applying column chromatography. Furthermore, using the sonochemical methodology as an efficient method led to reduce the reaction times. © 2018 Elsevier B.V
Ultrasound-assisted synthesis of highly functionalized benzo[1,3]thiazine via Cu-catalyzed intramolecular C–H activation reaction from isocyanides, aniline-benzoyl(acetyl) isothiocyanate adduct
, Article Ultrasonics Sonochemistry ; Volume 50 , 2019 , Pages 1-5 ; 13504177 (ISSN) ; Rezaee, E ; Jahani, M ; Tabatabai, S. A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
A facile sonochemical route for the synthesis of benzo[1,3]thiazine derivatives via a one pot, multicomponent, intramolecular C–H activation reaction from isocyanides, aniline and benzoyl (acetyl) isothiocyanate adduct catalyzed by copper (I) iodide in acetone at 30 °C have been reported. The advantages of the described method include using simple and readily available starting materials and performing under mild copper-catalytic reaction conditions and also obtaining pure product with high yield without applying column chromatography. Furthermore, using the sonochemical methodology as an efficient method led to reduce the reaction times. © 2018 Elsevier B.V