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Study of 2-butyne-1,4-diol as acid corrosion inhibitor for mild steel with electrochemical, infrared and AFM techniques
, Article International Journal of Electrochemical Science ; Volume 4, Issue 9 , 2009 , Pages 1339-1350 ; 14523981 (ISSN) ; Arshadi, M. R ; Sharif University of Technology
2009
Abstract
The inhibition of mild steel corrosion in 0.5 M sulphuric acid by the symmetrical acetylenic alcohol 2- butyne-1,4-diol is investigated. Weight loss and electrochemical impedance data consistently indicate inhibition efficiencies up to 98%. Short-term impedance measurements reveal that the interfacial inhibition is a function of the exposure time, and that full performance is achieved faster as inhibitor concentration and temperature are higher. An infrared study of the surface film provides evidence that the film does not achieve its final state but after several hours. Atomic force Microscopy has been used for investigation the surface topography of metallic electrode. © 2009 by ESG
Dynamic modeling and sensitivity analysis of atomic force microscope pushing force in nanoparticle manipulation on a rough substrate [electronic resource]
, Article Journal of Advanced Science, Engineering and Medicine ; 2013, Vol. 5, pp. 1-10 ; Mahboobi, Seyed Hanif ; Meghdari, Ali ; Sharif University of Technology
Abstract
An Atomic Force Microscope (AFM) is a capable tool to manipulate nanoparticles by exerting pushing force on the nanoparticles located on the substrate. In reality, the substrate cannot be considered as a smooth surface particularly at the nanoscale. Hence, the particle may encounter a step on the substrate during a manipulation. In this study, dynamics of the nanoparticle on a stepped substrate and critical pushing force in the manipulation are investigated. There are two possible dynamic modes that may happen in the manipulation on the stepped substrate. In one mode, the nanoparticle may slide on the step edge and then climb up to the step which is a desired mode. Another possible mode is...
Temperature dependence study of nonocontact AFM images using molecular dynamics simulations [electronic resource]
, Article Int. Journal of Modern Physics ; 2012, Vol. 5, pp. 418-432 ; Meghdar, Ali ; Sharif University of Technology
Abstract
The effect of temperature on the noncontact atomic force microscopy (NC-AFM) surface imaging is investigated with the aid of molecular dynamics (MD) analysis based on the Sutton-Chen (SC) interatomic potential. Particular attention is devoted to the tip and sample flexibility at different temperatures. When a gold coated probe is brought close to the Au (001) surface at high temperatures, the tip and surface atoms are pulled together and their distance becomes smaller. The tip and sample atoms displacement varies in the different environment temperatures and this leads to the different interaction forces. Along this line, to study the effect of temperature on the resulting images, we have...
Albumin-graphene oxide conjugates; Carriers for anticancer drugs
, Article RSC Advances ; Vol. 4, issue. 62 , July , 2014 , pp. 33001-33006 ; ISSN: 20462069 ; Pourjavadi, A ; Adeli, M ; Sharif University of Technology
Abstract
In order to improve its biological properties, graphene oxide can be modified with hydrophilic polymers. Therefore, in this study, the surface of graphene oxide was modified with polyethylene glycol and albumin by covalent methods. In the subsequent step, paclitaxel which is a hydrophobic anticancer drug was loaded onto the surface of the functionalized graphene by π-π interactions. The synthesis of the nanocarrier and its interaction with paclitaxel were evaluated by FT-IR, CD, TEM, UV, AFM, DLS and fluorescence experiments. Release of the loaded drug from albumin-graphene conjugate was investigated at pH 5.4, 6.8 and 7.4
Modeling of eccentric nanoneedle in trolling-mode atomic force microscope
, Article Microscopy Research and Technique ; 2020 ; Sajjadi, M ; Sharif University of Technology
Wiley-Liss Inc
2020
Abstract
Limitations on installation of a standard TR-AFM nanoneedle can have unpredictable effects on dynamics of system. Therefore, it is crucial to pay close attention to the position and geometry of mounted nanoneedle when deriving the mathematical model. During TR-AFM fabrication process, the nanoneedle may not always deposit precisely at the middle of AFM tip, which would result in coupled bending-torsion modes in the dynamical operation of system. In this paper, we investigate the effect of eccentric nanoneedle in dynamic response of TR-AFM. To address this issue, a continuous mathematical model is developed. This model accounts for eccentric nanoneedle which can address the couplings in...
Modeling of eccentric nanoneedle in trolling-mode atomic force microscope
, Article Microscopy Research and Technique ; Volume 84, Issue 4 , 2021 , Pages 639-655 ; 1059910X (ISSN) ; Sajjadi, M ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
Limitations on installation of a standard TR-AFM nanoneedle can have unpredictable effects on dynamics of system. Therefore, it is crucial to pay close attention to the position and geometry of mounted nanoneedle when deriving the mathematical model. During TR-AFM fabrication process, the nanoneedle may not always deposit precisely at the middle of AFM tip, which would result in coupled bending-torsion modes in the dynamical operation of system. In this paper, we investigate the effect of eccentric nanoneedle in dynamic response of TR-AFM. To address this issue, a continuous mathematical model is developed. This model accounts for eccentric nanoneedle which can address the couplings in...
Simulation of Imaging in Trolling Mode Atomic Force Microscopy by Molecular Dynamics Method
, M.Sc. Thesis Sharif University of Technology ; Nejat Pishkenari, Hossein (Supervisor)
Abstract
Atomic force microscopy (AFM), as an indispensable tool for nanoscale characterization, has major drawback for operation in a liquid environment arising from the large hydrodynamic drag on the vibrating cantilever. The newly introduced “Trolling Mode” (TR-Mode) AFM resolves this complication utilizing a specialized nanoneedle cantilever that keeps the cantilever outside of the liquid. Herein, a mechanical model with a lumped mass was developed to capture the dynamics of such cantilever with a nanoneedle tip. This new developed model was applied to investigate the effects of the needle – liquid interface on the performance of the AFM, including the imaging capability in liquid. Also...
Dynamic Modeling and Control of Atomic Force Microscope in Trolling Mode
, Ph.D. Dissertation Sharif University of Technology ; Vosoughi, Gholamreza (Supervisor) ; Nejat Pishkenari, Hossein (Supervisor)
Abstract
Trolling mode atomic force microscope (TR-AFM) significantly reduces the hydrodynamic drag generated during operation in liquid environments. This is achieved by utilizing a long nanoneedle and keeping the cantilever out of liquid. In this research, a continuous mathematical model is developed to study TR-AFM dynamics near a sample submerged in the liquid. Effects of cantilever torsion, nanoneedle flexibility, and liquid-nanoneedle interactions are considered in the model. The finite element model of the TR-AFM resonator considering the effects of fluid and nanoneedle flexibility is presented in this research, for the first time. The model is verified by ABAQUS software. The effect of...
Determination of the Surface Properties and Topography in AFM Using System Dynamics
,
M.Sc. Thesis
Sharif University of Technology
;
Nejat, Hossein
(Supervisor)
Abstract
Nowadays, the atomic force microscopy (AFM) has become a useful laboratory tool with variety of applications. In the traditional imaging technique, usually the amplitude or frequency of AFM tip oscillations is set at a desired value using a feedback control system which is a relatively slow process. In the current research, we propose an estimation approach which uses an adaptive fading extended Kalman filter (augmented with forgetting factor) as a system observer and couples with the system dynamics to determine the sample topography. As a result, in addition to state variables of system dynamic, the sample height as an unknown parameter is estimated with high accuracy in a relatively short...
Modeling of Force Interactions between Tip of Atomic Force Microscopy in Trolling Mode and Environment
, M.Sc. Thesis Sharif University of Technology ; Nejat Pishkenari, Hossein (Supervisor)
Abstract
Submerging of the Micro-beam of the AFM is indispensible in case of imaging bio-samples. (Bio-samples are unstable in non-aquos environment.), so hydrodynamical interaction of liquid and beam (viscous and meniscus forces) will result into quality factor decrease. This will cause image resolution decrement as well as damage to the sample because of large tip-sample forces during imaging of the bio-samples. The proposed method “Trolling mode AFM” keeps the micro-beam of the AFM out of the liquid, by adding a nano-needle to the end of the AFM tip. This would lead to resolve the aforementioned problems. Modeling of a part of the operation of this mechanism was done in this thesis, in order to...
Linear optimal control of continuous time chaotic systems
, Article ISA Transactions ; Vol. 53, Issue. 4 , 2014 , pp. 1209-1215 ; ISSN: 00190578 ; Abbaszadeh Chekan, J ; Salarieh, H ; Alasty, A ; Sharif University of Technology
Abstract
In this research study, chaos control of continuous time systems has been performed by using dynamic programming technique. In the first step by crossing the response orbits with a selected Poincare section and subsequently applying linear regression method, the continuous time system is converted to a discrete type. Then, by solving the Riccati equation a sub-optimal algorithm has been devised for the obtained discrete chaotic systems. In the next step, by implementing the acquired algorithm on the quantized continuous time system, the chaos has been suppressed in the Rossler and AFM systems as some case studies
Surface roughness analysis of hydrophilic SiO2/TiO 2/glass nano bilayers by the level crossing approach
, Article Physica A: Statistical Mechanics and its Applications ; Volume 392, Issue 9 , 2013 , Pages 2175-2181 ; 03784371 (ISSN) ; Reza Rahimi Tabar, M ; Moshfegh, A. Z ; Sharif University of Technology
2013
Abstract
The effect of etching time on the statistical properties of hydrophilic surfaces of SiO2/TiO2/glass nano bilayers has been studied using atomic force microscopy (AFM) and a stochastic approach based on a level crossing analysis. We have created rough surfaces of the hydrophilic SiO 2/TiO2 nano bilayer system by using 26% potassium hydroxide (KOH) solution. Measuring the average apparent contact angle allowed us to assess the degree of hydrophilicity, and the optimum condition was determined to be 10 min etching time. A level crossing analysis based on AFM images provided deeper insight into the microscopic details of the surface topography. With different etching times, it has been shown...
Atomic interactions between metallic tips and surfaces in NC-AFM
, Article Journal of Physics D: Applied Physics ; Volume 48, Issue 12 , February , 2015 ; 00223727 (ISSN) ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
In this paper, the atomic-scale interactions between metallic tips and samples in noncontact atomic force microscopy (NC-AFM) are studied using molecular dynamics simulations. The effects of the tip and sample materials, the surface plane direction and the lateral position of the tip with respect to the sample, on the interaction force and the dissipated energy, are investigated. The simulations conducted demonstrate that, generally, we can classify the possible outcomes for the dynamics due to the tip-surface interactions into four major categories. The first category includes all cases in which there are no considerable instabilities in tip-surface interactions, leading to negligible...
Dynamics of the nanoneedle probe in trolling mode AFM
, Article Nanotechnology ; Volume 26, Issue 20 , April , 2015 ; 09574484 (ISSN) ; Pishkenari, H. N ; Keramati, R ; Minary Jolandan, M ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
Atomic force microscopy (AFM), as an indispensable tool for nanoscale characterization, presents major drawbacks for operation in a liquid environment arising from the large hydrodynamic drag on the vibrating cantilever. The newly introduced 'Trolling mode' (TR-mode) AFM resolves this complication by using a specialized nanoneedle cantilever that keeps the cantilever outside of the liquid. Herein, a mechanical model with a lumped mass was developed to capture the dynamics of such a cantilever with a nanoneedle tip. This new developed model was applied to investigate the effects of the needle-liquid interface on the performance of the AFM, including the imaging capability in liquid
Optimization of first mode sensitivity of V-shaped AFM cantilever using genetic algorithm method
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings, 13 November 2009 through 19 November 2009 ; Volume 12, Issue PART A , 2010 , Pages 495-501 ; 9780791843857 (ISBN) ; Kahrobaiyan, M. H ; Rahaeifard, M ; Ahmadian, M. T ; Sharif University of Technology
Abstract
Atomic force microscopes (AFM) are widely used for feature detection and scanning surface topography of different materials. Contrast of topography images is significantly influenced by the sensitivity of AFM micro cantilever which means enhancement of sensitivity leads to increase of topography images resolution So, in the last years numerous scientists interested in studying the effects of different parameters such as geometric one on the sensitivity of AFM micro cantilevers. V-shape micro cantilever types of AFMs probe are widely used to scan various types of surfaces. In V-shape micro cantilevers, there are many geometric and design parameters which influence the flexural sensitivity of...
Flexural sensitivity of a V-shaped AFM cantilever made of functionally graded materials
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 1 , 2010 , Pages 495-501 ; 9780791849156 (ISBN) ; Kahrobaiyan, M. H ; Moeini, S. A ; Ahmadian, M. T ; Hoviattalab, M ; Sharif University of Technology
Abstract
In this paper, two lowest resonant frequencies and sensitivities of an AFM V-Shaped microcantilever made of functionally graded materials are studied. The beam is modeled by Euler-Bernoulli beam theory in which rotary inertia and shear deformation is neglected. It is assumed that the beam is made of a mixture of metal and ceramic with properties varying through the thickness of the beam. This variation is function of volume fraction of beam material constituents. The interaction between AFM tip and surface is modeled by two linear springs which expresses the normal and lateral contact stiffness. A relationship is developed to evaluate the sensitivity of FGM micro cantilever beam. Effect of...
Surface defects characterization with frequency and force modulation atomic force microscopy using molecular dynamics simulations
, Article Current Applied Physics ; Volume 10, Issue 2 , 2010 , Pages 583-591 ; 15671739 (ISSN) ; Meghdari, A ; Sharif University of Technology
2010
Abstract
This paper is devoted to the characterization of the surface defects using a recently developed AFM technique called frequency and force modulation AFM (FFM-AFM). The simulated system includes a recently developed gold coated AFM probe which interacts with a sample including single-atom vacancy and impurities. In order to examine the behavior of the above system on different transition metals, the molecular dynamics (MD) simulation with Sutton-Chen (SC) inter-atomic potential is used. In this study, an online imaging simulation of the probe and sample is performed, and the effects of the horizontal scan speed, the effective frequency set-point, the cantilever stiffness, the tip-sample rest...
Tip geometry effects in surface characterization with amplitude modulation AFM
, Article Scientia Iranica ; Volume 17, Issue 1 F , 2010 , Pages 27-34 ; 10263098 (ISSN) ; Meghdari, A ; Sharif University of Technology
Abstract
In the present work, characterization of the surface trenches and vacancies with Amplitude Modulation AFM (AM-AFM) using Molecular Dynamics (MD) is simulated and the effects of the tip shape on the resulting images are investigated. The simulated system includes a recently developed gold coated AFM probe which interacts with a sample including a surface trench or a single-atom vacancy. In order to examine the behavior of the above system, including different transition metals, a Molecular Dynamics (MD) simulation with Sutton-Chen (SC) interatomic potential is used. Special attention is dedicated to the study of tip geometry effects such as the tip apex radius, the tip cone angle, the probe...
Mechano-chemical AFM nanolithography of metallic thin films: A statistical analysis
, Article Current Applied Physics ; Volume 10, Issue 4 , 2010 , Pages 1203-1210 ; 15671739 (ISSN) ; Abdolahad, M ; Sharif University of Technology
2010
Abstract
A mechano-chemical atomic force microscope (AFM) nanolithography on a metallic thin film (50 nm in thickness) covered by a spin-coated soft polymeric mask layer (50-60 nm in thickness) has been introduced. The surface stochastic properties of initial grooves mechanically patterned on the mask layer (grooves before chemical wet-etching) and the lithographed patterns on the metallic thin film (the grooves after chemical wet-etching) have been investigated and compared by using the structure factor, power spectral density, and AFM tip deconvolution analyses. The effective shape of cross section of the before and after etching grooves have been determined by using the tip deconvolution surface...
Dynamic and Vibration Analysis of Non-Rotating and Rotating FGM Cantilever Beams Under Moving Mass
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Hoviattalab, Maryam (Supervisor)
Abstract
The purpose of this work, is to design a cantilever arm made of functionally graded materials so that the arm has maximum natural frequency and minimum mass. In this work the arm is modeled by Euler-Bernoulli beam theory and properties are assumed to be varying through the thickness. The beam is considered to be made of Aluminum and Alumina as metal and ceramic respectively and Genetic Algorithm method is used for optimization step. Finally using FGMs in atomic force microscopes is proposed as a new application of these materials