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Particles focusing and separation by a novel inertial microfluidic device: divergent serpentine microchannel
, Article Industrial and Engineering Chemistry Research ; Volume 61, Issue 38 , 2022 , Pages 14324-14333 ; 08885885 (ISSN) ; Shamloo, A ; Vatani, P ; Ebrahimi, S ; Sharif University of Technology
American Chemical Society
2022
Abstract
Microfluidic experiments have found wide applications in medical sciences and engineering, such as cell separation and focusing. In the present study, focusing and separation of particles with different sizes and densities were investigated by designing inertial microfluidic devices. The microfluidic channel is designed by analyzing the induced forces on the particles. In the designing process, the objective was to focus and separate the particles in the shortest length of the channel with the lowest possible cycles and high efficiency. The simulation is then used for analyzing the two proposed geometries to evaluate their particle separation and focusing ability, named convergent and...
Flexible high dielectric polystyrene/ethylene-α-octene copolymer/graphene nanocomposites: Tuning the morphology and dielectric properties by graphene's surface polarity
, Article Polymers for Advanced Technologies ; Volume 33, Issue 3 , 2022 , Pages 937-951 ; 10427147 (ISSN) ; Pircheraghi, G ; Khonakdar, H. A ; Altstadt, V ; Sharif University of Technology
John Wiley and Sons Ltd
2022
Abstract
The current research focuses on suggesting a new potential application of polymeric materials for capacitor applications by focusing on polystyrene (PS)/ethylene-α-octene copolymer (EOC) blends. Polymeric materials have high dielectric strength (≈ 200 for PS), good processability, and flexibility. However, their low dielectric constants make them not suitable for capacitor applications. Therefore, suggesting a method for enhancing their dielectric constant accompanied by low tan δ proposes an excellent substitute for commonly used ceramic dielectrics. The current article investigates the control of the dielectric properties of PS/EOC blends by manipulating the graphene nanoplatelets (GNPs)...
Zero knowledge focusing in millimeter-wave imaging systems using gradient approximation
, Article IEEE Transactions on Antennas and Propagation ; Volume 70, Issue 4 , 2022 , Pages 3123-3127 ; 0018926X (ISSN) ; Fakharzadeh, M ; Amini, A ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This communication addresses the focusing problem in the millimeter-wave imaging systems. We categorize the focusing problem into the frequency focusing for wideband systems and the range focusing for narrowband systems. In an out-of-focus wideband system, a shifted shadow of the object is present in the reconstruction, whereas for a range out of the focused system, the recovered images are blurred. To overcome these issues, first, we theoretically show that the defocusing variations for both categories are bounded. Then, we present a universal formulation for focusing problem, which covers both wideband and narrowband systems. As the true focused images are sharp at the boundaries of the...
Investigating the effects of precursor concentration and gelling parameters on droplet-based generation of Ca-Alginate microgels: identifying new stable modes of droplet formation
, Article Materials Today Chemistry ; Volume 24 , 2022 ; 24685194 (ISSN) ; Rezaeian, M ; Mahmoudi, Z ; Shamloo, A ; Kazemzadeh Hannani, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Droplet-based microfluidics is an attractive approach for producing microgels due to its high potential to control the size and shape of the particles and precisely entrap the substances within the hydrogel matrix. However, the microfluidic generation of monodisperse microgels with desired structures is still challenging. Indeed, the rheological and interfacial properties of the immiscible fluids, as well as the adopted gelling strategy, play important roles in microfluidic methods. Herein, sodium alginate droplets with different concentrations are generated via a microfluidic device with a flow-focusing unit. Besides, a combined in situ and ex situ strategy is optimized to crosslink sodium...
Fast and robust LRSD-Based sar/isar imaging and decomposition
, Article IEEE Transactions on Geoscience and Remote Sensing ; Volume 60 , 2022 ; 01962892 (ISSN) ; Moradikia, M ; Bastami, H ; Abdelhadi, A ; Soltanalian, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
The earlier works in the context of low-rank-sparse-decomposition (LRSD)-driven stationary synthetic aperture radar (SAR) imaging have shown significant improvement in the reconstruction-decomposition process. Neither of the proposed frameworks, however, can achieve satisfactory performance when facing a platform residual phase error (PRPE) arising from the instability of airborne platforms. More importantly, in spite of the significance of real-time processing requirements in remote sensing applications, these prior works have only focused on enhancing the quality of the formed image, not reducing the computational burden. To address these two concerns, this article presents a fast and...
Effect of laser additive manufacturing parameters on hardness and geometry of Inconel 625 parts manufactured by direct laser metal deposition
, Article Optik ; Volume 249 , 2022 ; 00304026 (ISSN) ; Akbari, J ; Moradi, M ; Malekshahi Beiranvand, Z ; Sharif University of Technology
Elsevier GmbH
2022
Abstract
This research investigates the effect of process parameters on the geometry and properties of In625 parts, manufactured by the direct laser metal deposition (DLMD) process. For this purpose, eight parts, consisting of 5 layers on top of each other, were manufactured, and the effect of laser power, laser focal plane position, and scanning speed on the height, width, and surface smoothness of each of them was investigated using design of experiment (DOE). The experimental results showed that the height of the parts manufactured by 800 W/mm and 200 W/mm of energy density is 3.69 mm and 6.12 mm, respectively. The thickness of the parts manufactured by 80 W/mm and 200 W/mm of energy density is...
Investigation of the different parameters contributing to bubble sticking inside physiological bifurcations
, Article Medical and Biological Engineering and Computing ; Volume 60, Issue 2 , 2022 , Pages 599-618 ; 01400118 (ISSN) ; Saidi, M. S ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Gas embolotherapy (GE) is a developing medical method which can be utilized either as an autonomous therapeutic method to treat vascularized solid tumors, or it can be combined with other medical procedures—such as high-intensity focused ultrasound—to improve their efficiency. This paper is dedicated to investigating the different parameters which influence bubble lodging inside human vasculature via 2D-modeling of bubble dynamics in arteries’ and arterioles’ bifurcations which are potential sticking positions. Values used in the simulations are in accordance with the non-dimensional physiological numbers. It is found out that inlet pressure plays a decisive role in bubble lodging; the lower...
Super-resolution photoacoustic microscopy using structured-illumination
, Article IEEE Transactions on Medical Imaging ; Volume 40, Issue 9 , 2021 , Pages 2197-2207 ; 02780062 (ISSN) ; Mostafavi, M ; Chen, J ; Kavehvash, Z ; Zhu, J ; Wang, L ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
A novel super-resolution volumetric photoacoustic microscopy, based on the theory of structured-illumination, is proposed in this paper. The structured-illumination will be introduced in order to surpass the diffraction limit in a photoacoustic microscopy (PAM) structure. Through optical excitation of the targeted object with a sinusoidal spatial fringe pattern, the object's frequency spectrum is forced to shift in the spatial frequency domain. The shifting in the desired direction leads to the passage of the high-frequency contents of the object through the passband of the acoustic diffraction frequency response. Finally, combining the low-frequency image with the high-frequency parts in...
Image quality equations for focused transducer in circular photoacoustic computed tomography
, Article 29th Iranian Conference on Electrical Engineering, ICEE 2021, 18 May 2021 through 20 May 2021 ; 2021 , Pages 917-921 ; 9781665433655 (ISBN) ; Kavehvash, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In this paper, we divide the imaging geometry of a photoacoustic computed tomography (PACT) structure that have a circular geometry and have focused transducers of positive or negative focus, into different zones of varying resolution. With using the presented analysis, it is possible to find the maximum range in which the system resolution is at its best value, according to the device specifications. The following equations are used to find the blind spot angles of the system for each source point inside the chamber. These are important for two reasons: the first is that the user can calculate the range in which the imaging system has the best quality by entering the specifications of his...
Beam manipulation by hybrid plasmonic-dielectric metasurfaces
, Article Plasmonics ; Volume 15, Issue 3 , 2020 , Pages 639-645 ; Hemmatyar, O ; Kavehvash, Z ; Sharif University of Technology
Springer
2020
Abstract
A hybrid plasmonic-dielectric metasurface is proposed in order to manipulate beam propagation in desired manners. The metasurface is composed of patterned hybrid graphene-silicon nano-disks deposited on a low-index substrate, namely silica. It is shown that the proposed hybrid metasurface simultaneously benefits from the advantages of graphene-based metasurfaces and dielectric ones. Specially, we show that the proposed hybrid metasurface not only provides reconfigurability, just like previously proposed graphene-based metasurfaces, but also similar to dielectric metasurfaces, is of low loss and CMOS-compatible. Such exceptional features give the metasurface exceptional potentials to realize...
High throughput solution exchange of microparticles using magnetophoresis in curved microchannels
, Article 21st International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2017, 22 October 2017 through 26 October 2017 ; 2020 , Pages 1324-1325 ; Zareian, S ; Rezai, P ; The Chemical and Biological Microsystems Society (CBMS) ; Sharif University of Technology
Chemical and Biological Microsystems Society
2020
Abstract
A novel method involving focusing of magnetic particles at the inner wall of a curved microchannel and secondary Dean flow-based exchange of their fluid was investigated. Solution exchange occurred in a hybrid microchip at very high throughput and with unprecedented solution exchange and particle isolation efficiencies of 99.2% and 90%, respectively. © 17CBMS-0001
High intensity focused ultrasound (HIFU) ablation of porous liver: numerical analysis of heat transfer and hemodynamics
, Article Applied Thermal Engineering ; Volume 170 , April , 2020 ; Firoozabadi, B ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In the present study, the influence of the liver vascular bed on heat transfer in a tumor located close to the hepatic artery and exposed to high intensity focused ultrasound (HIFU), is studied numerically. For this purpose, an acoustics-thermal-fluid coupling model based on the porous media theory under the local thermal non-equilibrium assumption is used to calculate the temperature field in the tumor, porous liver, and the hepatic artery. Different generations of the liver vasculature including arterial branches, terminal arterial branches, terminal veins and venous branches are examined at different porosities (the volume fraction of the vasculature). It is found that the liver...
Computational inertial microfluidics: a review
, Article Lab on a Chip ; Volume 20, Issue 6 , 2020 , Pages 1023-1048 ; Mashhadian, A ; Ehsani, A ; Saha, S. C ; Krüger, T ; Ebrahimi Warkiani, M ; Sharif University of Technology
Royal Society of Chemistry
2020
Abstract
Since the discovery of inertial focusing in 1961, numerous theories have been put forward to explain the migration of particles in inertial flows, but a complete understanding is still lacking. Recently, computational approaches have been utilized to obtain better insights into the underlying physics. In particular, fundamental aspects of particle focusing inside straight and curved microchannels have been explored in detail to determine the dependence of focusing behavior on particle size, channel shape, and flow Reynolds number. In this review, we differentiate between the models developed for inertial particle motion on the basis of whether they are semi-analytical, Navier-Stokes-based,...
An interface–particle interaction approach for evaluation of the co-encapsulation efficiency of cells in a flow-focusing droplet generator
, Article Sensors (Switzerland) ; Volume 20, Issue 13 , 2020 , Pages 1-17 ; Saidi, M. S ; Ghadami, S ; Kashaninejad, N ; Sharif University of Technology
MDPI AG
2020
Abstract
Droplet-based microfluidics offers significant advantages, such as high throughput and scalability, making platforms based on this technology ideal candidates for point-of-care (POC) testing and clinical diagnosis. However, the efficiency of co-encapsulation in droplets is suboptimal, limiting the applicability of such platforms for the biosensing applications. The homogeneity of the bioanalytes in the droplets is an unsolved problem. While there is extensive literature on the experimental setups and active methods used to increase the efficiency of such platforms, passive techniques have received less attention, and their fundamentals have not been fully explored. Here, we develop a novel...
Numerical study of the effect of vascular bed on heat transfer during high intensity focused ultrasound (HIFU) ablation of the liver tumor
, Article Journal of Thermal Biology ; Volume 86 , 2019 ; 03064565 (ISSN) ; Firoozabadi, B ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this study, the influence of vascular bed comprising terminal arterial branches on heat transfer in a liver tumor exposed to high intensity focused ultrasound (HIFU) is studied numerically. Also, the effect of vascular density on temperature distribution is investigated. A coupled set of acoustics, thermal, and fluid models is used to calculate the temperature distribution in the liver. The numerical model is established based on the Westervelt and bioheat equations along with the Navier-Stokes equations. Moreover, the acoustic streaming effect is included with Newtonian and non-Newtonian flow assumptions. It is found that in a vascular bed comprising terminal arterial branches, the...
Inertial microfluidics: a method for fast prediction of focusing pattern of particles in the cross section of the channel
, Article Analytica Chimica Acta ; Volume 1083 , 2019 , Pages 137-149 ; 00032670 (ISSN) ; Shamloo, A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Inertial microfluidics is utilized as a powerful passive method for particle and cell manipulation, which uses the hydrodynamic forces of the fluid in the channel to focus particles in specific equilibrium positions in the cross section of the channel. To achieve high performance manipulation, knowledge of focusing pattern of particles in the cross section of channel is essential. In this paper, we propose a method to address this important issue. To this end, firstly inertial microfluidics is analyzed in rectangular cross section channels. The results indicate that fluid flow velocity and channel's cross-sectional profiles have great impacts on the forces exerted on particles. Next, these...
Differential effects of fonf and fonfs on learning english lax vowels in an efl context
, Article Journal of Asia TEFL ; Volume 16, Issue 2 , 2019 , Pages 499-515 ; 17383102 (ISSN) ; Moinzadeh, A ; Barati, H ; Sharif University of Technology
Asian Association of Teachers of English as a Foreign Language
2019
Abstract
This study investigated the differential effects of focus-on-form (FonF: explicit instruction followed by focused tasks) and focus-on-forms (FonFS: explicit instruction followed by controlled exercises) on learning English lax vowels (i.e., /ɪ/, /ʊ/, /ʌ/) by Persian English as a foreign language (EFL) learners. To this end, 48 learners took a voluntary 6-hour course: the experimental group (n = 17) received FonF, the comparison group (n = 16) received FonFS, and the control group (n = 15) engaged in theme-based discussions with no focus on the target vowels. Learners’ pronunciations were elicited in controlled read-aloud and spontaneous picture description tasks and acoustically measured for...
A mixture of vortex terahertz radiation generation in inhomogeneous plasma by considering pump depletion
, Article Laser Physics ; Volume 29, Issue 1 , 2019 ; 1054660X (ISSN) ; Bahrampour, A. R ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
An attempt to extend helical terahertz radiation generation based on pump depletion is presented here. By considering an upward plasma density ramp, such a reasonable extension is examined to improve the results. It is claimed that the output terahertz energy is saturated which is attributed to laser pump divergence. The saturation effect is enhanced by considering suitable laser and plasma parameters. The adjustable slope of the density ramp is an important parameter for tuning terahertz generation effciency, which is restricted to the up and down limit. For the resonant excitation of terahertz radiation, the ripple wave number is suitably chosen to satisfy the phase matching condition....
Beam manipulation by hybrid plasmonic-dielectric metasurfaces
, Article Plasmonics ; 2019 ; 15571955 (ISSN) ; Hemmatyar, O ; Kavehvash, Z ; Sharif University of Technology
Springer
2019
Abstract
A hybrid plasmonic-dielectric metasurface is proposed in order to manipulate beam propagation in desired manners. The metasurface is composed of patterned hybrid graphene-silicon nano-disks deposited on a low-index substrate, namely silica. It is shown that the proposed hybrid metasurface simultaneously benefits from the advantages of graphene-based metasurfaces and dielectric ones. Specially, we show that the proposed hybrid metasurface not only provides reconfigurability, just like previously proposed graphene-based metasurfaces, but also similar to dielectric metasurfaces, is of low loss and CMOS-compatible. Such exceptional features give the metasurface exceptional potentials to realize...
A mixture of vortex terahertz radiation generation in inhomogeneous plasma by considering pump depletion
, Article Laser Physics ; Volume 29, Issue 1 , 2019 ; 1054660X (ISSN) ; Bahrampour, A. R ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
An attempt to extend helical terahertz radiation generation based on pump depletion is presented here. By considering an upward plasma density ramp, such a reasonable extension is examined to improve the results. It is claimed that the output terahertz energy is saturated which is attributed to laser pump divergence. The saturation effect is enhanced by considering suitable laser and plasma parameters. The adjustable slope of the density ramp is an important parameter for tuning terahertz generation effciency, which is restricted to the up and down limit. For the resonant excitation of terahertz radiation, the ripple wave number is suitably chosen to satisfy the phase matching condition....