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Differentiating Signals Recorded from Rat Brain in Response to Different Olfactory Stimuli
, M.Sc. Thesis Sharif University of Technology ; Karbalaei Aghajan, Hamid (Supervisor)
Abstract
The olfactory sense in rats provides crucial information for identifying food sources, detecting threats, and facilitating social interactions. The olfactory bulb is one of the key brain regions involved in the initial processing of olfactory information and its transmission to higher brain areas for more complex processing. However, more advanced cognitive processes such as evaluation and decision-making rely on interactions between other brain regions. Among these, the striatum, as a part of the basal ganglia, plays a role in reward evaluation, reward-based learning, and shaping behaviors associated with sensory stimuli. This region contributes to learning, decision-making, and action...
Comparing half-metallic, MOKE, and thermoelectric behavior of the CrTiZ (Z = As, P) half-Heuslers: A DFT study
, Article Materials Research Express ; Volume 8, Issue 4 , 2021 ; 20531591 (ISSN) ; Zelati, A ; Boochani, A ; Arman, A ; Mirzaei, S ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
Structural, half-metallic, magneto-optic, and thermoelectric properties of CrTiZ (Z = As, P) half-Heusleres compounds are investigated based on density functional theory. These compounds have mechanical stability in the ferromagnetic state with a high bulk modulus. They are often half-metallic with a large and integer magnetic moment and are very attractive in spintronics, magneto-optics applications. The magnetic moments of CrTiAs and CrTiP were 2.9865 μB and 3.00 μB, respectively, which were attributed to their ferromagnetic phase. Additionally, the positive sign of the phonon branches indicates the dynamic stability of these compounds. Applying both GGA and mBJ approximations, CrTiAs and...
The Effect of Rudder Angle on Ship’s Fuel Consumption
, M.Sc. Thesis Sharif University of Technology ; Khorasanchi, Mahdi (Supervisor) ; Zare, Arman (Co-Supervisor)
Abstract
The aim of this research is to investigate the effect of speed and direction of current on ship fuel consumption. A KCS benchmark model has been numerically studied in calm water and fourteen current and wind conditions with the same speed and different directions to determine how the ship performance is dependent on flow conditions. The model has been simulated in an artificial basin propelled by a single right-handed propeller via a CFD commercial code. Numerical results revealed a linear relationship between the deviation of current and wind from head-sea or following-sea conditions and the rudder angle. The head-sea and following-sea currents and winds increased and decreased the lateral...
Evaluation of the topographical surface changes of silicon wafers after annealing and plasma cleaning
, Article Silicon ; Volume 12, Issue 11 , 2020 , Pages 2563-2570 ; Ţălu, Ş ; Dallaev, R ; Arman, A ; Sobola, D ; Salerno, M ; Sharif University of Technology
Springer Science+Business Media B.V
2020
Abstract
Purpose: The morphological stability of silicon single crystal wafers was investigated, after performing cleaning surface treatments based on moderate temperature annealing and plasma sputtering. Methods: The wafer surfaces were measured by Tapping mode atomic force microscopy in air, before and after the different treatments. The 3D images were segmented by watershed algorithm identifying the local peaks, and the stereometric parameters were extracted thereof. The analysis of variance allowed to better assess the statistically significant differences. Results: All the resulting quantities were critically discussed. It appeared that the different cleaning treatments affected differently the...
The effect of thickness and film homogeneity on the optical and microstructures of the ZrO2 thin films prepared by electron beam evaporation method
, Article Optical and Quantum Electronics ; Volume 53, Issue 8 , 2021 ; 03068919 (ISSN) ; Talebani, N ; Zelati, A ; Ţălu, Ş ; Arman, A ; Mirzaei, S ; Jafari, A ; Sharif University of Technology
Springer
2021
Abstract
In this study, ZrO2 coatings with different thicknesses were grown by the electron beam evaporation technique. The crystalline structure was studied by XRD analysis which suggested the tetragonal and monoclinic phases for ZrO2 coatings. Additionally, the film thickness slightly enhanced the crystallinity. The surface morphology and fractal features were analyzed using Scanning Electron Microscopy (SEM). The surface statistical parameters and the fractal geometry were employed to analyze the impact of the coating thickness and homogeneity on the morphology of the films. The statistical processing and fractal dimension revealed variations in the morphology parameters due to the electron beam...
Electrokinetic Flow in pH-Regulated Solid-State/Soft Micro-Nanochannels
,
Ph.D. Dissertation
Sharif University of Technology
;
Saeedi, Mohammad Hassan
(Supervisor)
;
Mousavi, Ali
(Co-Supervisor)
;
Sadeghi, Arman
(Co-Supervisor)
Abstract
In recent years, advances have been made in the field of miniaturization of the devices (in order to increase their efficiency, lessen the materials needed for the constructions and experiments, reduce costs and energy usage) resulting in the dramatic increase of surface to volume ratio in these devices. This progress has led to the dominance of surface forces which can be used to control very important interface phenomena having a special application such as electrokinetic. Using today’s manufacturing technology; it is possible to construct micro-nanochannels made from different materials such as silicon, glass, quartz, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA) whose...
Plasma surface functionalization of boron nitride nano-sheets
, Article Diamond and Related Materials ; Volume 77 , 2017 , Pages 110-115 ; 09259635 (ISSN) ; Achour, A ; Solaymani, S ; Islam, M ; Vizireanu, S ; Arman, A ; Ahmadpourian, A ; Dinescu, G ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
On silicon substrates, boron nitride nanosheets (BNNS) consisting of interconnected hexagonal boron nitride nano-layers were produced via chemical vapor deposition process at 1200 °C whose roughness's are at the micrometer- and nanometer-scale. The BNNS were functionalized in argon plasma admixed with ammonia or nitrogen or oxygen. The samples were characterized to investigate the surface chemistry and structural changes after plasma treatment using X-ray photoelectron spectroscope and Micro-Raman spectroscope techniques, respectively. While no significant changes in the surface features, upon plasma treatments of the BNNS, were noticed during SEM and TEM examination, the oxygen functional...
Multiferroic behavior of the functionalized surface of a flexible substrate by deposition of Bi2O3 and Fe2O3
, Article Microscopy Research and Technique ; 2021 ; 1059910X (ISSN) ; Sobola, D ; Ţălu, Ş ; Orudzev, F ; Arman, A ; Kaspar, P ; Dallaev, R ; Ramazanov, G ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
Thin films of bismuth and iron oxides were obtained by atomic layer deposition (ALD) on the surface of a flexible substrate poly(4,4′-oxydiphenylene-pyromellitimide) (Kapton) at a temperature of 250°C. The layer thickness was 50 nm. The samples were examined by secondary-ion mass spectrometry, and uniform distribution of elements in the film layer was observed. Surface morphology, electrical polarization, and mechanical properties were investigated by atomic force microscope, piezoelectric force microscopy, and force modulation microscopy. The values of current in the near-surface layer varied in the range of ±80 pA when a potential of 5 V was applied. Chemical analysis was performed by...
3D distributed modeling of trolling-mode AFM during 2D manipulation of a spherical cell
, Article Journal of Nanoparticle Research ; Volume 23, Issue 4 , 2021 ; 13880764 (ISSN) ; Nejat Pishkenari, H ; Mohammadi Moghaddam, M ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
In this study, a general 3D distributed modeling of Trolling-Mode AFM (TR-AFM) as a nanorobot is presented to analyze the 2D manipulation process of a spherical cell. To this aim, the analysis is categorized into 3 sections. In the first section, 6 deformations of TR-AFM are taken into account, and the standard model of the system is obtained. Moreover, the system is simulated in ANSYS Workbench. The results of modal and transient analyses of the system from both analytical and software methods reveal high agreement, which confirms the accuracy of the presented analytical model. In the second section, by utilizing the 3D derived model, displacement of a spherical yeast single cell (W303)...
Sol-gel nanostructured titanium dioxide: Controlling the crystal structure, crystallite size, phase transformation, packing and ordering
, Article Microporous and Mesoporous Materials ; Volume 112, Issue 1-3 , 2008 , Pages 392-402 ; 13871811 (ISSN) ; Fray, D. J ; Mohammadi, A ; Sharif University of Technology
2008
Abstract
The anatase phase of titania was stabilised with physically modifying particulate sol-gel process. Two major parameters, peptisation temperature and drying temperature, were identified which were responsible for retarding the anatase to rutile phase transformation, crystal growth and packing of primary particles. The critical nucleus size of transformation was controlled by natural (at 25 °C) and artificial (at 50 and 70 °C) peptisation techniques. Moreover, sintering of primary particles was controlled by cool (at 0 and 5 °C) and normal (at 25 °C) drying techniques. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that a full conversion of titanium isopropoxide is obtained...
Electrokinetic mixing and displacement of charged droplets in hydrogels
, Article Transport in Porous Media ; Vol. 104, Issue. 3 , Jun , 2014 , pp. 469-499 ; ISSN: 01693913 ; Sharif University of Technology
2014
Abstract
Mixing in droplets is an essential task in a variety of microfluidic systems. Inspired by electrokinetic mixing, electric field-induced hydrodynamic flow inside a charged droplet embedded in an unbounded polyelectrolyte hydrogel is investigated theoretically. In this study, the polyelectrolyte hydrogel is modeled as a soft, and electrically charged porous solid saturated with a salted Newtonian fluid, and the droplet is considered an incompressible Newtonian fluid. The droplet-hydrogel interface is modeled as a surface, which is located at the plane of shear, with the electrostatic potential ζ. The fluid inside the droplet attains a finite velocity owing to hydrodynamic coupling with the...
Electric-field-induced response of a droplet embedded in a polyelectrolyte gel
, Article Physics of Fluids ; Volume 25, Issue 8 , 2013 ; 10706631 (ISSN) ; Sharif University of Technology
2013
Abstract
The electric-field induced response of a droplet embedded in a quenched polyelectrolyte gel is calculated theoretically. The response comprises the droplet translation and the electric-field induced flow fields within the droplet. The gel is modeled as a soft, and electrically charged porous solid saturated with a salted Newtonian fluid. The droplet is considered an incompressible Newtonian fluid with no free charge. An analytical solution, using the perturbation methodology and linear superposition, is obtained for the leading-order steady response to a DC electric-field. The fluid within the droplet is driven due to hydrodynamic coupling with the electroosmotic flow. The fluid velocity...
Oscillatory response of charged droplets in hydrogels
, Article Journal of Non-Newtonian Fluid Mechanics ; Volume 234 , 2016 , Pages 215-235 ; 03770257 (ISSN) ; Sharif University of Technology
Elsevier
2016
Abstract
Characterization of droplet-hydrogel interfaces is of crucial importance to engineer droplet-hydrogel composites for a variety of applications. In order to develop electrokinetic diagnostic tools for probing droplet-hydrogel interfaces, the displacement of a charged droplet embedded in a polyelectrolyte hydrogel exposed to an oscillating electric field is determined theoretically. The polyelectrolyte hydrogel is modeled as an incompressible, charged, porous, and elastic solid saturated with a salted Newtonian fluid. The droplet is considered an incompressible Newtonian fluid with no charges within the droplet. The droplet-hydrogel interface is modeled as a surface with the thickness of zero...
Transport in droplet-hydrogel composites: response to external stimuli
, Article Colloid and Polymer Science ; Volume 293, Issue 3 , March , 2015 , Pages 941-962 ; 0303402X (ISSN) ; Sharif University of Technology
Springer Verlag
2015
Abstract
Determination of effective transport properties of droplet-hydrogel composites is essential for various applications. The transport of ions through a droplet-hydrogel composite subjected to an electric field is theoretically studied as an initial step toward quantifying the effective transport properties of droplet-hydrogel composites. A three-phase electrokinetic model is used to derive the microscale characteristics of the polyelectrolyte hydrogel, and the droplet is considered an incompressible Newtonian fluid. The droplet-hydrogel interface is modeled as a surface, which encloses the interior fluid. The surface has the thickness of zero and the electrostatic potential ζ. Standard...
A simple particulate sol-gel route to synthesize nanostructural TiO2-Ta2O5 binary oxides and their characteristics
, Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 142, Issue 1 , 2007 , Pages 16-27 ; 09215107 (ISSN) ; Fray, D. J ; Sadrnezhaad, S. K ; Mohammadi, A ; Sharif University of Technology
2007
Abstract
Nanostructured and mesoporous TiO2-Ta2O5 films and powders with various TiO2:Ta2O5 molar ratios and high specific surface area (SSA) have been prepared by a straightforward particulate sol-gel route. Titanium isopropoxide and tantalum ethoxide were used as precursors and hydroxypropyl cellulose (HPC) was used as a polymeric fugitive agent (PFA) in order to increase the SSA. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that powders contained both hexagonal δ-Ta2O5 and monoclinic β-Ta2O5 phases, as well as anatase and rutile. It was observed that Ta2O5 retarded anatase-to-rutile transformation. Furthermore, δ → β phase transformation temperature increased...
Correction to: Controlled manipulation of a bio-particle using trolling mode atomic force microscope: a simulation study (Journal of Nanoparticle Research, (2021), 23, 10, (221), 10.1007/s11051-021-05301-6)
, Article Journal of Nanoparticle Research ; Volume 24, Issue 8 , 2022 ; 13880764 (ISSN) ; Nejat Pishkenari, H ; Mohammadi Moghaddam, M ; Sajjadi, M ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
The original article contained a mistake in Equation 1. The corrected Equation 1 is shown below: MX+Cx+Kx=f.The original article has been updated © Springer Nature B.V. 2022
Multifractal and optical bandgap characterization of Ta2O5 thin films deposited by electron gun method
, Article Optical and Quantum Electronics ; Volume 52, Issue 2 , 2020 ; Rezaee, S ; Mwema, F ; Luna, C ; Ghosh, K ; Jurečka, S ; Ţălu, Ş ; Arman, A ; Grayeli Korpi, A ; Sharif University of Technology
Springer
2020
Abstract
The micromorphology of tantalum pentoxide (Ta2O5) thin films, deposited on glass substrates by electron gun method, has been analyzed using atomic force microscopy (AFM), UV–Vis–NIR spectrophotometry and multifractal analyses. Two samples were grown at basic pressure of 7 × 10−6 mbar, work pressures of 1.3 × 10−4 and 2.0 × 10−4 mbar, and thicknesses of 0.38 μm and 0.39 μm, respectively. Subsequently, these samples were annealed at 300 °C for 2 h. The physical, structural and optical analyses were investigated by spectroscopic ellipsometry, spectrophotometry and AFM. The measured transmittance spectra were studied based on the Swanepoel method, whose results also yielded to the estimation of...
Experimental investigation of thermal resistance of a ferrofluidic closed-loop pulsating heat pipe
, Article Heat Transfer Engineering ; Vol. 35, issue. 1 , 2014 , pp. 25-33 ; ISSN: 01457632 ; Mohammadi, M ; Ghahremani, A. R ; Shafii, M. B ; Mohammadi, N ; Sharif University of Technology
2014
Abstract
For the present article, a pulsating heat pipe (PHP) is fabricated and tested experimentally by bending a copper tube. The effects of working fluid, heat input, charging ratio, inclination angle, magnets location, and ferrofluid (magnetic nanofluid) volumetric concentration have been investigated on the thermal performance of this PHP. Experimental results show that using ferrofluid as a working fluid improves the thermal performance of the PHP significantly. Moreover, applying a magnetic field on a ferrofluidic PHP reduces its thermal resistance. By changing the inclination angle of the PHP from vertical mode to angles close to the horizontal mode, the present PHP has a constant and...
Hybrid control of electrohydrodynamic 3D printer cone jet
, Article Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering ; Volume 237, Issue 4 , 2023 , Pages 1262-1272 ; 09544089 (ISSN) ; Abdullahi, M. A ; Salarieh, H ; Movahhedy, M. R ; Mohammadi, S ; Sharif University of Technology
SAGE Publications Ltd
2023
Abstract
In this article, the control of an electrohydrodynamic 3D printer is studied. The proposed controller has a hybrid piecewise linear feedback form which is designed based on a hybrid model of the printer. The hybrid model is obtained via a gray box identification process whose structure is proposed utilizing the results of the finite element simulation of the printer within the COMSOL Multiphysics software. The asymptotic stability of the hybrid control combined with a hybrid observer is proven using the Lyapunov theory. In addition, the obtained control is applied to the finite element model of the printer to check its performance which shows the success of the controlled system in tracking...
Bromo-lithium Exchange Reaction in Organic Synthesis and Continuous Separation of Organic and Aqueous phase Reactions by Microfloid Technique
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor) ; Bastani, Dariush (Supervisor)
Abstract
Today, with the development of micro-technology in chemical reactions, the use of appropriate systems for the separation and purification of synthesized chemicals seems to be necessary. In this study, the continuous synthesis of bromide-lithium exchange reaction and the separation of organic and aqueous phase products in micro systems was investigated.The method used to construct micro-separator and micro reactor, a laser engraving technique, and thermal bonding of glass to glass.In the first step, the factors affecting the separation of organic and aqueous phase in the capillary micro-separator, such as the width of the capillary, the length of the capillary, the number of capillaries and...