Loading...
Search for:
cytology
0.007 seconds
Total 229 records
Fabrication of a highly ordered hierarchically designed porous nanocomposite via indirect 3D printing: Mechanical properties and in vitro cell responses
, Article Materials and Design ; Volume 88 , 2015 , Pages 924-931 ; 02641275 (ISSN) ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Design and development of biodegradable scaffolds with highly uniform and controlled internal structure that stimulate tissue regeneration are the focus of many studies. The aim of this work is to apply a modified three-dimensional (3D) printing process to fabricate polymer-matrix composites with controlled internal architecture. Computationally-designed plaster molds with various pore sizes in the range of 300-800. μm were prepared by employing 3D printing of a water-based binder. The molds were converted to ε-polycaprolactone (PCL) and PCL/bioactive glass (BG) composite scaffolds by solvent casting and freeze drying methods. Optical and electron microscopy studies revealed that the pore...
A microfluidic device for 2D to 3D and 3D to 3D cell navigation
, Article Journal of Micromechanics and Microengineering ; Volume 26, Issue 1 , November , 2015 ; 09601317 (ISSN) ; Amirifar, L ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
Microfluidic devices have received wide attention and shown great potential in the field of tissue engineering and regenerative medicine. Investigating cell response to various stimulations is much more accurate and comprehensive with the aid of microfluidic devices. In this study, we introduced a microfluidic device by which the matrix density as a mechanical property and the concentration profile of a biochemical factor as a chemical property could be altered. Our microfluidic device has a cell tank and a cell culture chamber to mimic both 2D to 3D and 3D to 3D migration of three types of cells. Fluid shear stress is negligible on the cells and a stable concentration gradient can be...
Design of robust SRAM cells against single-event multiple effects for nanometer technologies
, Article IEEE Transactions on Device and Materials Reliability ; Volume 15, Issue 3 , 2015 , Pages 429-436 ; 15304388 (ISSN) ; Asgari, B ; Tabandeh, M ; Fazeli, M ; Sharif University of Technology
Abstract
As technology size scales down toward lower two-digit nanometer dimensions, sensitivity of CMOS circuits to radiation effects increases. Static random access memory cells (SRAMs) that are mostly employed as high-performance and high-density memory cells are prone to radiation-induced single-event upsets. Therefore, designing reliable SRAM cells has always been a serious challenge. In this paper, we propose two novel SRAM cells, namely, RHD11 and RHD13, that provide more attractive features than their latest proposed counterparts. Simulation results show that our proposed SRAM cells as compared with some state-of-the-art designs have considerably higher robustness against single-event...
Effect of formulation factors on the bioactivity of glucose oxidase encapsulated chitosan-alginate microspheres: In vitro investigation and mathematical model prediction
, Article Chemical Engineering Science ; Volume 125 , March , 2015 , Pages 4-12 ; 00092509 (ISSN) ; Cheng, J ; Wu, X. Y ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Higher reactive oxygen species (ROS) levels in cancer cells than normal cells have long been recognized, which makes cancer cells more susceptible to excess ROS. Thus oxidation (also called pro-oxidant) therapy has been explored as new cancer therapy regimens. To produce additional ROS, e.g. H2O2 in situ within tumor, we encapsulated glucose oxidase in chitosan-coated alginate-calcium microspheres (GOX-MS) for locoregional treatment and demonstrated its efficacy against cancer cells in vitro and in vivo. Owing to the complex biological functions of ROS, the production rate and amount of H2O2 are critical to achieve therapeutic benefits without causing normal tissue toxicity. This work was...
Fsi simulation of a healthy coronary bifurcation for studying the mechanical stimuli of endothelial cells under different physiological conditions
, Article Journal of Mechanics in Medicine and Biology ; Volume 15, Issue 5 , October , 2015 ; 02195194 (ISSN) ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2015
Abstract
Atherosclerosis is a world-spread and well-known disease. This disease strongly relates to the endothelial cells (ECs) function. Normally, the endothelial cells align in the flow direction in the atheroprotected sites; however, in the case of atheroprone sites these cells orient randomly. The mechanical stimuli such as wall shear stress and strains could determine the morphology and function of the endothelial cells. In the present study, we numerically simulated the left main coronary artery (LCA) and its branches to left anterior descending (LAD) and left circumflex coronary (LCX) artery using fluid-structure interaction (FSI) modeling. The results were presented as longitudinal and...
On the control of tumor growth via type-1 and interval type-2 fuzzy logic
, Article Journal of Mechanics in Medicine and Biology ; Volume 15, Issue 5 , 2015 ; 02195194 (ISSN) ; Alasty, A ; Salarieh, H ; Hosseinian Sarajehlou, M ; Sharif University of Technology
Abstract
This paper deals with growth control of cancer cells population using type-1 and interval type-2 fuzzy logic. A type-1 fuzzy controller is designed in order to reduce the population of cancer cells, adjust the drug dosage in a manner that allows normal cells re-grow in treatment period and maintain the maximum drug delivery rate and plasma concentration of drug in an appropriate range. Two different approaches are studied. One deals with reducing the number of cancer cells without any concern about the rate of decreasing, and the other takes the rate of malignant cells damage into consideration. Due to the fact that uncertainty is an inherent part of real systems and affects controller...
ZnFe2O4 nanoparticles as radiosensitizers in radiotherapy of human prostate cancer cells
, Article Materials Science and Engineering C ; Volume 46 , January , 2015 , Pages 394-399 ; 09284931 (ISSN) ; Akhavan, O ; Khoei, S ; Shokri, A. A ; Hajikarimi, Z ; Khansari, N ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Nanoparticles of high-Z elements exhibit stronger photoelectric effects than soft tissues under gamma irradiation. Hence, they can be used as effective radiosensitizers for increasing the efficiency of current radiotherapy. In this work, superparamagnetic zinc ferrite spinel (ZnFe2O4) nanoparticles were synthesized by a hydrothermal reaction method and used as radiosensitizers in cancer therapy. The magnetic nanoparticles showed fast separation from solutions (e.g., ~ 1 min for 2 mg mL- 1 of the nanoparticles in ethanol) by applying an external magnetic field (~ 1 T). The ZnFe2O4 nanoparticles were applied in an in vitro radiotherapy of lymph node carcinoma of prostate cells (as high...
Leukocyte's nucleus segmentation using active contour in YCbCr colour space
, Article Proceedings of 2010 IEEE EMBS Conference on Biomedical Engineering and Sciences, IECBES 2010, 30 November 2010 through 2 December 2010, Kuala Lumpur ; 2010 , Pages 257-260 ; 9781424476008 (ISBN) ; Jahed, M ; Salehian, P ; Eslami, A ; Sharif University of Technology
2010
Abstract
Blood cell segmentation is a crucial part of many medical and laboratory procedures such as cell counting and blood cell disorder diagnosis. Among different types of blood cells, white blood cells are the most important clinically, as they suffer greatest from blood disorders. In this paper we propose a method for automatic segmentation of white blood cells nucleus. A distinctive function is used in YCbCr color space to segment the white blood cells nucleus. Next, the sub-images are extracted which contain the whole body of white blood cell nucleus. Then an active contour method is applied to the sub-images extracted from the previous step to accurately segment the cell nucleus boundary. Our...
A nanoscale CMOS SRAM cell for high speed applications
, Article 5th International Conference on MEMS NANO, and Smart Systems, ICMENS 2009, 28 December 2009 through 30 December 2009, Dubai ; 2010 , Pages 33-36 ; 9780769539386 (ISBN) ; Manzuri Shalmani, M. T ; Mehrparvar, A ; Sharif University of Technology
2010
Abstract
The leakage current and process variation are drastically increased with technology scaling. In Conventional SRAM cell due to process variations, stored data can be destroyed during read operation. Therefore, leakage current of SRAM cell and stability during read operation are two important parameters in nano-scaled CMOS technology. To overcome these limitations and to increase the speed of conventional SRAMs, we have developed a read-static-noise-margin-free SRAM cell. The developed cell has six-transistors and uses two read/write-lines and two read/write-bit-lines during read/write operation. This cell retains its data with leakage current and positive feedback without refresh cycle. The...
A novel nano-scaled SRAM cell
, Article World Academy of Science, Engineering and Technology ; Volume 65 , 2010 , Pages 172-174 ; 2010376X (ISSN) ; Sahebi, M. R ; Manzuri Shalmani, M. T ; Sharif University of Technology
Abstract
To help overcome limits to the density of conventional SRAMs and leakage current of SRAM cell in nanoscaled CMOS technology, we have developed a four-transistor SRAM cell. The newly developed CMOS four-transistor SRAM cell uses one word-line and one bit-line during read/write operation. This cell retains its data with leakage current and positive feedback without refresh cycle. The new cell size is 19% smaller than a conventional six-transistor cell using same design rules. Also the leakage current of new cell is 60% smaller than a conventional sixtransistor SRAM cell. Simulation result in 65nm CMOS technology shows new cell has correct operation during read/write operation and idle mode
Performance assessment of thermophotovoltaic application in steel industry
, Article Solar Energy Materials and Solar Cells ; Volume 157 , 2016 , Pages 55-64 ; 09270248 (ISSN) ; Sharif University of Technology
Elsevier
2016
Abstract
The potential for using Thermophotovoltaic (1TPV) generators as an alternative for recovering energy losses in steel production industry is assessed. A mathematical model for the assessment of the performance of TPV application in the iron and steel industry has been developed. In order to support the mathematical model, a sample TPV apparatus in laboratory scale based on an IR emitter has been designed and assembled. The key modeling parameters of TPV generator include: the open circuit voltage, the short circuit current density and fill factor of the TPV cell. These parameters have been considered in the model as functions of several variables such as: the emitter (hot steel slab)...
Mathematical modeling and analytical solution of two-phase flow transport in an immobilized-cell photo bioreactor using the homotopy perturbation method (HPM)
, Article International Journal of Hydrogen Energy ; Volume 41, Issue 41 , 2016 , Pages 18405-18417 ; 03603199 (ISSN) ; Fattahi, M ; Sharif University of Technology
Elsevier Ltd
Abstract
In the present study, a theoretical model of a reaction–diffusion within an entrapped-cell photobioreactor packed with gel-granules containing immobilized photosynthetic bacterial cells is presented. The model is based on a system of two coupled nonlinear reaction–diffusion equations under steady-state condition for biochemical reactions occurring in the photobioreactor that describes the substrate and product concentration within the gel-granule. Simple analytical expressions for the concentration of substrate and product have been derived for all values of reaction–diffusion parameters, demonstrating competition between the diffusion and reaction in the gel-granule, using the homotopy...
Simulation of 2D fluid–structure interaction in inviscid compressible flows using a cell-vertex central difference finite volume method
, Article Journal of Fluids and Structures ; Volume 67 , 2016 , Pages 190-218 ; 08899746 (ISSN) ; Azampour, M. H ; Sharif University of Technology
Academic Press
Abstract
In the present study, the applicability and accuracy of a cell-vertex finite volume method developed are assessed in simulating 2D fluid–structure interaction in inviscid compressible flows where the nonlinear phenomena exist in both the unsteady transonic fluid flows and the large nonlinear deformation of solid structures. The unsteady Euler equations are considered as the governing equations of the fluid flow in the arbitrary Lagrangian–Eulerian form and the large nonlinear deformation of the solid structure is considered to be governed by the Cauchy equations in the total Lagrangian form. Both the domains are discretized by a second-order central-difference cell-vertex finite volume...
Integrating evolutionary game theory into an agent-based model of ductal carcinoma in situ: Role of gap junctions in cancer progression
, Article Computer Methods and Programs in Biomedicine ; Volume 136 , 2016 , Pages 107-117 ; 01692607 (ISSN) ; Habibi, J ; Zangooei, M. H ; Aghakhani, H ; Sharif University of Technology
Elsevier Ireland Ltd
Abstract
Background and objective There are many cells with various phenotypic behaviors in cancer interacting with each other. For example, an apoptotic cell may induce apoptosis in adjacent cells. A living cell can also protect cells from undergoing apoptosis and necrosis. These survival and death signals are propagated through interaction pathways between adjacent cells called gap junctions. The function of these signals depends on the cellular context of the cell receiving them. For instance, a receiver cell experiencing a low level of oxygen may interpret a received survival signal as an apoptosis signal. In this study, we examine the effect of these signals on tumor growth. Methods We make an...
Biomimetic apatite layer formation on a novel citrate starch scaffold suitable for bone tissue engineering applications
, Article Starch/Staerke ; Volume 68, Issue 11-12 , 2016 , Pages 1275-1281 ; 00389056 (ISSN) ; Shahriarpanah, S ; Asadzadehzanjani, N ; Khaleghpanah, S ; Heidari, S ; Sharif University of Technology
Wiley-VCH Verlag
2016
Abstract
The formation of biomimetic bone-like apatite layers throughout the biopolymer-based hydrogel scaffold is an attractive approach in bone tissue engineering. Here, the starch scaffold was prepared using a combination of particulate leaching and freeze-drying techniques. The fabricated structures were then modified by citric acid to investigate the formation of bone-like apatite layer on the porous citrate-based scaffold after soaking in simulated body fluid (SBF). The Fourier Transform Infrared (FTIR) spectra and X-ray diffraction (XRD) patterns revealed that the B-type carbonated apatite has successfully deposited on the scaffold after immersing in SBF for 28 days. Indeed, high chemical...
A mechanical model for morphological response of endothelial cells under combined wall shear stress and cyclic stretch loadings
, Article Biomechanics and Modeling in Mechanobiology ; Volume 15, Issue 5 , 2016 , Pages 1229-1243 ; 16177959 (ISSN) ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
Springer Verlag
Abstract
The shape and morphology of endothelial cells (ECs) lining the blood vessels are a good indicator for atheroprone and atheroprotected sites. ECs of blood vessels experience both wall shear stress (WSS) and cyclic stretch (CS). These mechanical stimuli influence the shape and morphology of ECs. A few models have been proposed for predicting the morphology of ECs under WSS or CS. In the present study, a mathematical cell population model is developed to simulate the morphology of ECs under combined WSS and CS conditions. The model considers the cytoskeletal filaments, cell–cell interactions, and cell–extracellular matrix interactions. In addition, the reorientation and polymerization of...
Biocatalysts in microbial electrolysis cells: A review
, Article International Journal of Hydrogen Energy ; Volume 41, Issue 3 , 2016 , Pages 1477-1493 ; 03603199 (ISSN) ; Mardanpour, M. M ; Yaghmaei, S ; Sharif University of Technology
Elsevier Ltd
Abstract
Microbial electrolysis cells (MECs) are bioelectrochemical reactors in which chemical energy stored in organic compounds are converted to hydrogen through biocatalytic oxidation by microorganisms. The performance of MECs is highly affected by microbial communities that are impartible parts of this technology. A better understanding of microbial interactions and competitions mechanisms, has aided the comprehension of ideas and guidelines for cost effective commercial scales design. In this study, a comprehensive review of current knowledge in the microbial characterization, enrichment, and evaluation of effective parameters of microbial community in microbial electrolysis cells for typical...
Rigidity of transmembrane proteins determines their cluster shape
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 93, Issue 1 , 2016 ; 15393755 (ISSN) ; Khoshnood, A ; Jalali, M. A ; Sharif University of Technology
American Physical Society
Abstract
Protein aggregation in cell membrane is vital for the majority of biological functions. Recent experimental results suggest that transmembrane domains of proteins such as α-helices and β-sheets have different structural rigidities. We use molecular dynamics simulation of a coarse-grained model of protein-embedded lipid membranes to investigate the mechanisms of protein clustering. For a variety of protein concentrations, our simulations under thermal equilibrium conditions reveal that the structural rigidity of transmembrane domains dramatically affects interactions and changes the shape of the cluster. We have observed stable large aggregates even in the absence of hydrophobic mismatch,...
Modeling self-assembly of the surfactants into biological bilayer membranes with special chemical structures using dissipative particle dynamics method
, Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 942-950 ; 10263098 (ISSN) ; Pishevar, A. R ; Saidi, M. S ; Shirani, E ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
The aim of this study is to simulate the self-assembly of the surfactant molecules with special chemical structure and bending stiffiness into bilayer membranes using a mesoscopic Dissipative Particle Dynamics (DPD) method. The surfactants are modeled with special chemical structure and bending stiffiness. To confirm that the novel model is physical, we determine the interaction parameters based on matching the compressibility and solubility of the DPD system with real physics of the uid. To match the mutual solubility for binary uids, we use the relation between DPD parameters and x-parameters in Flory-Huggins-type models. Unsaturated bonds can change the stiffiness of a lipid membrane,...
Nanofibrous hydrogel with stable electrical conductivity for biological applications
, Article Polymer (United Kingdom) ; Volume 97 , 2016 , Pages 205-216 ; 00323861 (ISSN) ; Rezayat, S. M ; Vashegani Farahani, E ; Mahmoudifard, M ; Zamanlui, S ; Soleimani, M ; Sharif University of Technology
Elsevier Ltd
Abstract
3D hydrogel environment with both unique properties of nanofibrous structure and electrical character can provide a promising scaffold for skeletal muscle tissue engineering approaches. Herein, the poly acrylic acid (PAA)-based hydrogel was engineered to conductive one by aniline polymerization in the form of nanofibers. The poly aniline (PANi) nanofibers were made by the optimized chemical reactions between the surface carboxylate groups of based hydrogel and protonated aniline monomers. We found that the strong bonding which was created between PANi and camphor sulphonic acid (CSA) as a doping agent supporting the stable electrical property of composite hydrogel after incubation in cell...