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Colorimetric Sensing of Nitrite and Glutathione Based on Morphological Changes of High Aspect Ratio of Gold Nanorods
, M.Sc. Thesis Sharif University of Technology ; Hormozi Nezhad, Mohammad Reza (Supervisor)
Abstract
The fascinating size-dependent properties of noble metal nanop articles have created a great promise for their use in a different applications specially chemical sensing. Gold nanorods (GNRs), specifically, have received a great deal of attention due to their unusual optical properties. The nanoscale confinement of electrons on the surface of gold nanorods grants them aspect ratio-dependent properties not seen in larger particles. Due to the intriguing properties of GNRs, significant work has gone into the application of nanorods for sensing and detection of various an alytes in biological and other systems. The major modalities which have been developed for...
A Mechanobiological model for damage-induced growth in arterial tissue with application to in-stent restenosis
, Article Journal of the Mechanics and Physics of Solids ; Volume 101 , 2017 , Pages 311-327 ; 00225096 (ISSN) ; Naghdabadi, R ; Sohrabpour, S ; Holzapfel, G. A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In-stent restenosis (ISR) is one of the main drawbacks of stent implementation which limits the long-term success of the procedure. Morphological changes occurring within the arterial wall due to stent-induced mechanical injury are a major cause for activation of vascular smooth muscle cells (VSMCs), and the subsequent development of ISR. Considering the theory of volumetric mass growth and adopting a multiplicative decomposition of the deformation gradient into an elastic part and a growth part, we present a mechanobiological model for ISR. An evolution equation is developed for mass growth of the neointima, in which the activation of VSMCs due to stent-induced damage (injury) and the...
How does a microfluidic platform tune the morphological properties of polybenzimidazole nanoparticles?
, Article Journal of Physical Chemistry B ; Volume 126, Issue 1 , 2022 , Pages 308-326 ; 15206106 (ISSN) ; Sayyad Amin, J ; Zendehboudi, S ; Sharif University of Technology
American Chemical Society
2022
Abstract
Microfluidic synthesis methods are among the most promising approaches for controlling the size and morphology of polymeric nanoparticles (NPs). In this work, for the first time, atomistic mechanisms involved in morphological changes of polybenzimidazole (PBI) NPs in microfluidic media are investigated. The multiscale molecular dynamic (MD) simulations are validated with the literature modeling and experimental data. A good agreement is obtained between the molecular modeling results and experimental data. The effects of mixing time, solvent type, dopant, and simulation box size at the molecular level are investigated. Mixing time has a positive impact on the morphology of the PBI NPs....
Alteration of corrosion and nanomechanical properties of pulse electrodeposited Ni/SiC nanocomposite coatings
, Article Journal of Alloys and Compounds ; Vol. 598 , 2014 , Pages 236-242 ; ISSN: 09258388 ; Ghorbani, M ; Sharif University of Technology
Abstract
Nickel/silicon carbide composite electrodeposits were prepared on a rotating disk electrode (RDE), under pulse current condition. The effect of pulse parameters, current density, SiC content in the electrolyte on the codeposition of SiC were studied. Afterwards, the effect of codeposited SiC amount was investigated on electrochemical behavior and nanomechanical properties of coatings. The coatings were analyzed with Scanning Electron Microscopy (SEM), linear polarization, nanoindentation and Atomic Force Microscopy (AFM). The Ni-SiC electrocomposites, prepared at optimum conditions, exhibited improved nanomechanical properties in comparison to pure nickel electrodeposits. With increasing...
Effect of high energy ball milling on compressibility of nanostructured composite powder
, Article Powder Metallurgy ; Volume 54, Issue 1 , Nov , 2011 , Pages 24-29 ; 00325899 (ISSN) ; Farnoush, H. R ; Asgharzadeh, H ; Sadrnezhaad, S. K ; Sharif University of Technology
2011
Abstract
Compressibility of a nanostructured Al-5AlN composite powder synthesised via high energy ball milling for various times was studied by means of a modified Heckel equation. Since workhardening and morphological changes take place by milling evolution, the compressibility was consequently affected. Strengthening of composite compacts was influenced by milling and compaction processes, i.e. strength of compacts increased at longer milling times and higher compaction pressures. It was found that, at the initial stages of milling and higher compaction pressures, the strengthening was mostly affected from compaction process, whereas the milling strengthening fraction was near to unity at lower...
A combined dynamical sequential network for generating coupled cardiovascular signals with different beat types
, Article ; 2010 3rd International Symposium on Applied Sciences in Biomedical and Communication Technologies, ISABEL 2010, 7 November 2010 through 10 November 2010 , 2010 ; 9781424481323 (ISBN) ; Shamsollahi, M. B ; Sharif University of Technology
Abstract
We present generalizations of the previously published artificial models for generating abnormal cardiac rhythms to provide simulations of coupled cardiovascular (CV) signals with different beat morphologies. Using a joint dynamical formulation, we generate the normal morphologies of the cardiac cycle using a sum of Gaussian kernels, fitted to real CV recordings. The joint inter-dependencies of CV signals are introduced by assuming the same angular frequency and a phase coupling. Abnormal beats are then specified as new dynamical trajectories. An ergadic first-order Markov chain is also used for switching between normal and abnormal beat types. Probability transitions can be learned from...
Performance of a nickel-alumina catalytic layer for simultaneous production and purification of hydrogen in a tubular membrane reactor
, Article RSC Advances ; Volume 6, Issue 79 , 2016 , Pages 75686-75692 ; 20462069 (ISSN) ; Towfighi, J ; Zamaniyan, A ; Ganji Babakhani, E ; Heidari, M ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
A catalytic membrane reactor was synthesized by coating a 4-5 micron thick Ni/γ-Al2O3 layer on top of a hydrogen selective SiO2/Al2O3 composite membrane using a sol-gel method. Mercury intrusion and BET analysis indicated a uniform size distribution with an average pore size of 285 nm and average surface area of 279 m2 g-1. Single-component permeation tests were carried out for H2, CH4 and CO2 in the temperature range of 650-800 °C and the results showed the same permeance and selectivity values for hydrogen as the composite membrane without a catalytic layer. Performance of the catalytic membrane was evaluated by using as a membrane reactor for the methane steam reforming reaction with a...
Microstructural evolution, mechanical properties, and corrosion resistance of a heat-treated Mg alloy for the bio-medical application
, Article Journal of Magnesium and Alloys ; Volume 7, Issue 1 , 2019 , Pages 80-89 ; 22139567 (ISSN) ; Karimi Taheri, K ; Karimi Taheri, A ; Sharif University of Technology
National Engg. Reaserch Center for Magnesium Alloys
2019
Abstract
During the recent years, some Mg based alloys have extensively been considered as a new generation of degradable and absorbable bio-medical materials. In this work, the Mg–2Zn–1Gd–1Ca (wt%) alloy as a new metallic bio-material was produced by the casting process followed by the heat treatment. The samples of the alloy were solution treated at temperatures of 500, 550, and 600 °C and then quench aged at temperatures of 125, 150, and 175 °C. The results of SEM-EDS examinations indicated that the alloy microstructure consists of α-Mg matrix and the Ca2Mg6Zn3 and Mg3Gd2Zn3 secondary phases. With regard to the results of Vickers hardness test, the temperatures of 500 °C and 150 °C were selected...
An artificial multi-channel model for generating abnormal electrocardiographic rhythms
, Article Computers in Cardiology 2008, CAR, Bologna, 14 September 2008 through 17 September 2008 ; Volume 35 , 2008 , Pages 773-776 ; 02766574 (ISSN); 1424437067 (ISBN); 9781424437061 (ISBN) ; Nemati, S ; Sameni, R ; Sharif University of Technology
2008
Abstract
We present generalizations of our previously published artificial models for generating multi-channel ECG so that the simulation of abnormal rhythms is possible. Using a three-dimensional vectorcardiogram (VCG) formulation, we generate the normal cardiac dipole for a patient using a sum of Gaussian kernels, fitted to real VCG recordings. Abnormal beats are then specified either as new dipoles, or as perturbations of the existing dipole. Switching between normal and abnormal beat types is achieved using a hidden Markov model (HMM). Probability transitions can be learned from real data or modeled by coupling to heart rate and sympathovagal balance. Natural morphology changes form beat-to-beat...
Effects of hydrogen and oxides on tensile properties of Al-Si-Mg cast alloys
, Article Materials Science and Engineering A ; Volume 552 , 2012 , Pages 36-47 ; 09215093 (ISSN) ; Davami, P ; Kim, S. K ; Varahram, N ; Sharif University of Technology
Abstract
Gas porosities and entrapped double oxide film (hereafter: oxides) are known to be the most detrimental defects in cast Al-Si-Mg alloys. This study investigated the effects of dissolved hydrogen (hereafter: H) and oxides on reproducibility of tensile properties in Al-7Si-0.35 Mg alloys. Also the effects of H and oxides content on the morphology of defects were studied. Four different casting conditions (low oxide-low H, low oxide-high H, high oxide-low H, high oxide-high H) were tested using tensile test bars that were cast in a metallic mold. Results of tensile test that were obtained for each casting condition were analyzed using Weibull two-parameter analysis. Microstructure and fracture...
Effect of deep cryogenic treatment on microstructure, creep and wear behaviors of AZ91 magnesium alloy
, Article Materials Science and Engineering A ; Volume 523, Issue 1-2 , 2009 , Pages 27-31 ; 09215093 (ISSN) ; Tari, A ; Khomamizadeh, F ; Sharif University of Technology
2009
Abstract
This paper focuses on the effect of deep cryogenic treatment (-196 °C) on microstructure and mechanical properties of AZ91 magnesium alloy. The execution of deep cryogenic treatment on samples changed the distribution of β precipitates. The tiny laminar β particles almost dissolved in the microstructure and the coarse divorced eutectic β phase penetrated into the matrix. This microstructural modification resulted in a significant improvement on mechanical properties of the alloy. The steady state creep rates were measured and it was found that the creep behavior of the alloy, which is dependent on the stability of the near grain boundary microstructure, was improved by the deep cryogenic...