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Silver nanoparticles within vertically aligned multi-wall carbon nanotubes with open tips for antibacterial purposes
, Article Journal of Materials Chemistry ; Volume 21, Issue 2 , Oct , 2011 , Pages 387-393 ; 09599428 (ISSN) ; Abdolahad, M ; Abdi, Y ; Mohajerzadeh, S ; Sharif University of Technology
2011
Abstract
Vertically aligned multi-wall carbon nanotube (CNT) arrays were fabricated in tip-growth mode on Ni/Si substrates using plasma enhanced chemical vapor deposition. In a purification process including hydrogenation and acid washing of the Ni/CNTs, the oxygen-containing functional groups were substantially reduced and a wide hollow core at the tip of the CNTs was formed by removing the Ni seeds. Sol-gel silver nanoparticles were deposited on the surface of the unpurified Ni/CNTs, while they could also be embedded within the hollow core of the Ni-removed CNTs. The persistency of the silver ions in the Ni-removed Ag-CNTs in comparison to the release of the silver ions from the Ag-Ni/CNTs in a...
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...
Near infrared laser stimulation of human neural stem cells into neurons on graphene nanomesh semiconductors
, Article Colloids and Surfaces B: Biointerfaces ; Volume 126 , 2015 , Pages 313-321 ; 09277765 (ISSN) ; Ghaderi, E ; Shirazian, S. A ; Sharif University of Technology
Abstract
Reduced graphene oxide nanomeshes (rGONMs), as p-type semiconductors with band-gap energy of ~1. eV, were developed and applied in near infrared (NIR) laser stimulation of human neural stem cells (hNSCs) into neurons. The biocompatibility of the rGONMs in growth of hNSCs was found similar to that of the graphene oxide (GO) sheets. Proliferation of the hNSCs on the GONMs was assigned to the excess oxygen functional groups formed on edge defects of the GONMs, resulting in superhydrophilicity of the surface. Under NIR laser stimulation, the graphene layers (especially the rGONMs) exhibited significant cell differentiations, including more elongations of the cells and higher differentiation of...
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...
Simulation of Red Blood Cell mechanical behavior in optical tweezers experiment based on a particle method
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010 ; Volume 2 , 2010 , Pages 325-329 ; 9780791844267 (ISBN) ; Firoozbakhsh, K ; Hasanian, M
Abstract
Optical tweezers provide an accurate measurement technique for evaluating mechanical properties of the living cells and many experimental studies have been done to understand the behavior of cells due to external forces. Numerical studies such as finite element methods have been used in order to simulate mechanical behavior of the Red Blood Cells (RBCs). Recent studies have shown that the particle methods are useful tools to simulate the mechanical behavior of living cells. Since in microscopic scales, using discrete models are preferred than continuum methods, a particle-based method is used to simulate the deformation of RBC which is stretched by optical tweezers. The cytoplasm of RBC is...
Modeling of cell deformation under external force using artificial neural network
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010 ; Volume 2 , 2010 , Pages 659-665 ; 9780791844267 (ISBN) ; Vossoughi, G. R ; Abbasi, A. A ; Raeissi, P ; Sharif University of Technology
Abstract
Embryogenesis, regeneration and cell differentiation in microbiological entities are influenced by mechanical forces. Therefore, development of mechanical properties of these materials is important. Neural network technique is a useful method which can be used to obtain cell deformation by the means of force-geometric deformation data or vice versa. Prior to insertion in the needle injection process, deformation and geometry of cell under external point-load is a key element to understand the interaction between cell and needle. In this paper the goal is the prediction of cell membrane deformation under a certain force, and to visually estimate the force of indentation on the membrane from...
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...
Toxicity of graphene and graphene oxide nanowalls against bacteria
, Article ACS Nano ; Volume 4, Issue 10 , October , 2010 , Pages 5731-5736 ; 19360851 (ISSN) ; Ghaderi, E ; Sharif University of Technology
2010
Abstract
Bacterial toxicity of graphene nanosheets in the form of graphene nanowalls deposited on stainless steel substrates was investigated for both Gram-positive and Gram-negative models of bacteria. The graphene oxide nanowalls were obtained by electrophoretic deposition of Mg2+-graphene oxide nanosheets synthesized by a chemical exfoliation method. On the basis of measuring the efflux of cytoplasmic materials of the bacteria, it was found that the cell membrane damage of the bacteria caused by direct contact of the bacteria with the extremely sharp edges of the nanowalls was the effective mechanism in the bacterial inactivation. In this regard, the Gram-negative Escherichia coli bacteria with an...
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
A 32kb 90nm 10T-cell sub-threshold SRAM with improved read and write SNM
, Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 ; 9781467356343 (ISBN) ; Zamani, M ; Hajsadeghi, K ; Sharif University of Technology
Abstract
The constraints of power saving have compelled SRAM designers to consider sub-threshold area as a viable choice. The biggest barrier of this progress is the stability of SRAM's cells and the correct operations. In this paper a 10T cell structure has been proposed with 90% read and 50% write SNM improvement in comparison to the conventional 6T cell. The hold SNM value is about the 6T cell SRAM. Also using differential read method in the proposed structure causes high read performance and using simpler sense amplifier. The symmetric configuration of this structure helps the SRAM has simpler layout and lower transistor mismatch. Using 90nm TSMC CMOS, 32kb 10T cell SRAM in sub-threshold area is...
Investigation of readout cell configuration and parameters on functionality and stability of bi-directional RSFQ TFF
, Article IEEE Transactions on Applied Superconductivity ; Volume 26, Issue 3 , 2016 ; 10518223 (ISSN) ; Zandi, H ; Foroughi, F ; Bozbey, A ; Fardmanesh, M ; Sharif University of Technology
Abstract
Considering the two main categories of rapid single flux quantum gates with destructive and nondestructive readout process, we have investigated the effects of readout cell topology and involved critical parameters on the proper functionality and stability of the states of the newly developed bidirectional T flip-flops (TFFs). It is observed that instabilities and fluctuations in the state of the gate (memory of TFF) after each transition determine the minimum time intervals between the clock pulses set by the ac bias current, further limiting the ultimate operation frequency of the circuits. The absolute values of the current levels of the junctions at each state, which play an important...
A comparative study of collagen matrix density effect on endothelial sprout formation using experimental and computational approaches
, Article Annals of Biomedical Engineering ; Volume 44, Issue 4 , 2016 , Pages 929-941 ; 00906964 (ISSN) ; Mohammadaliha, N ; Heilshorn, S. C ; Bauer, A. L ; Sharif University of Technology
Abstract
A thorough understanding of determining factors in angiogenesis is a necessary step to control the development of new blood vessels. Extracellular matrix density is known to have a significant influence on cellular behaviors and consequently can regulate vessel formation. The utilization of experimental platforms in combination with numerical models can be a powerful method to explore the mechanisms of new capillary sprout formation. In this study, using an integrative method, the interplay between the matrix density and angiogenesis was investigated. Owing the fact that the extracellular matrix density is a global parameter that can affect other parameters such as pore size, stiffness,...
Simulation of the effects of oxygen carriers and scaffold geometry on oxygen distribution and cell growth in a channeled scaffold for engineering myocardium
, Article Mathematical Biosciences ; Volume 294 , 2017 , Pages 160-171 ; 00255564 (ISSN) ; Mashayekhan, S ; Bastani, D ; Sharif University of Technology
Abstract
This study proposes a mathematical model to evaluate the impact of oxygen carriers and scaffold geometry on oxygen distribution and cell growth in a 3D cardiac construct using computational fluid dynamics (CFD). Flow equations, oxygen balance equation and cell balance equation were solved using special initial and boundary conditions. The modeling results revealed that 55% increase in cardiac cell density occurred by using 6.4% perfluorocarbon oxygen carrier (PFC) compared to pure culture medium without PFC supplementation. Moreover, the effects of the scaffold geometry on cell density were examined by changing the channel numbers and the construct length. A 30% increase in the average cells...
A multiscale approach for determining the morphology of endothelial cells at a coronary artery
, Article International Journal for Numerical Methods in Biomedical Engineering ; Volume 33, Issue 12 , 2017 ; 20407939 (ISSN) ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
Abstract
The morphology of endothelial cells (ECs) may be an indication for determining atheroprone sites. Until now, there has been no clinical imaging technique to visualize the morphology of ECs in the arteries. The present study introduces a computational technique for determining the morphology of ECs. This technique is a multiscale simulation consisting of the artery scale and the cell scale. The artery scale is a fluid-structure interaction simulation. The input for the artery scale is the geometry of the coronary artery, that is, the dynamic curvature of the artery due to the cardiac motion, blood flow, blood pressure, heart rate, and the mechanical properties of the blood and the arterial...
A Low area overhead NBTI/PBTI sensor for SRAM memories
, Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 25, Issue 11 , 2017 , Pages 3138-3151 ; 10638210 (ISSN) ; Rohbani, N ; Miremadi, S. G ; Sharif University of Technology
Abstract
Bias temperature instability (BTI) is known as one serious reliability concern in nanoscale technologies. BTI gradually increases the absolute value of threshold voltage (Vth) of MOS transistors. The main consequence of Vth shift of the SRAM cell transistors is the static noise margin (SNM) degradation. The SNM degradation of SRAM cells results in bit-flip occurrences due to transient faults and should be monitored accurately. This paper proposes a sensor called write current-based BTI sensor (WCBS) to assess the BTI-aging state of SRAM cells. The WCBS measures BTI-induced SNM degradation of SRAM cells by monitoring the maximum write current shifts due to BTI. The observations show that the...
Development of a virtual cell model to predict cell response to substrate topography
, Article ACS Nano ; Volume 11, Issue 9 , 2017 , Pages 9084-9092 ; 19360851 (ISSN) ; Heidari, M ; Mashinchian, O ; Wojcik, M ; Xu, K ; Dalby, M. J ; Mahmoudi, M ; Ejtehadi, M. R ; Sharif University of Technology
Abstract
Cells can sense and respond to changes in the topographical, chemical, and mechanical information in their environment. Engineered substrates are increasingly being developed that exploit these physical attributes to direct cell responses (most notably mesenchymal stem cells) and therefore control cell behavior toward desired applications. However, there are very few methods available for robust and accurate modeling that can predict cell behavior prior to experimental evaluations, and this typically means that many cell test iterations are needed to identify best material features. Here, we developed a unifying computational framework to create a multicomponent cell model, called the...
In vitro biological outcome of laser application for modification or processing of titanium dental implants
, Article Lasers in Medical Science ; Volume 32, Issue 5 , 2017 , Pages 1197-1206 ; 02688921 (ISSN) ; Farahmand, F ; Tabatabaei, F. S ; Sharif University of Technology
Abstract
There are numerous functions for laser in modern implant dentistry including surface treatment, surface coating, and implant manufacturing. As laser application may potentially improve osseointegration of dental implants, we systematically reviewed the literature for in vitro biological responses to laser-modified or processed titanium dental implants. The literature was searched in PubMed, ISI Web, and Scopus, using keywords “titanium dental implants,” “laser,” “biocompatibility,” and their synonyms. After screening the 136 references obtained, 28 articles met the inclusion criteria. We found that Nd:YAG laser was the most commonly used lasers in the treatment or processing of titanium...
Modeling and optimization of gelatin-chitosan micro-carriers preparation for soft tissue engineering: using response surface methodology
, Article Materials Science and Engineering C ; Volume 75 , 2017 , Pages 545-553 ; 09284931 (ISSN) ; Mashayekhan, S ; Vakilian, S ; Sharif University of Technology
Abstract
Electrospray ionization is a wide spread technique for producing polymeric microcarriers (MCs) by applying electrostatic force and ionic cross-linker, simultaneously. In this study, fabrication process of gelatin-chitosan MCs and its optimization using the Response Surface Methodology (RSM) is reported. Gelatin/chitosan (G/C) blend ratio, applied voltage and feeding flow rate, their individual and interaction effects on the diameter and mechanical strength of the MCs were investigated. The obtained models for diameter and mechanical strength of MCs have a quadratic relationship with G/C blend ratio, applied voltage and feeding flow rate. Using the desirability curve, optimized G/C blend...
Study of epithelial differentiation and protein expression of keratinocyte-mesenchyme stem cell co-cultivation on electrospun nylon/B. vulgaris extract composite scaffold
, Article Materials Science and Engineering C ; Volume 75 , 2017 , Pages 653-662 ; 09284931 (ISSN) ; Soleimani, M ; Vossoughi, M ; Ranjbarvan, P ; Hamedi, S ; Zamanlui, S ; Mahmoudifard, M ; Sharif University of Technology
Abstract
Employing of the composite electrospun scaffold containing herbal extract in conjugation with co-culturing of cells can open up new window to the design of efficient biomaterials for skin tissue regeneration. Here, we introduce the synergistic effect of composite electrospun nanofibrous scaffold of nylon66 loaded with Beta vulgaris (B. vulgaris) (extract of beet roots, a plants whose widely used in Iranian folk medicine as wound healing medicine) and co-culture of mesenchymal stem-cells (MSCs)-human keratinocyte (H-keratino) differentiation towards epithelial lineage. In vitro biocompatibility was examined through MTT assay and epithelial differentiation checked by real-time PCR and...