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self-assembly
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Synthesis and Study of Electron Transport through a Self-Assembled Monolayer of Thiol-End-Functionalized Tetraphenylporphyrines and Metalo-Tetraphenylporphyrines and Electrochemical Analysis of Dopamine and Ascorbic Acid with this SAMs
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Boghaei, Davar (Supervisor)
Abstract
Self-Assembled Monolayer (SAM) is the first step in all surface engineering and assembly processes. It is used in sensor fabrication, memories and molecular recognition and optoelectronic devises as an active surface for patterning and chemical architecting of solid substrates. Tetraphenyl porphyrins because of their high stability and uniqe electronic and optic properties, that comes from their conjugate π electrons, easily can be used in these monolayers. Moreover they have a wide application because of their ability for coordination with metals and accepting substituents with electron donating and withdrawing properties. Electron transport through these layars which attach to the surface...
Synthesis and Characterization of Nano-Composite Based on Supramolecuylar Poly Caprolactone/ Hydroxyapatite for Tissue Engineering Application
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Shokrollahi, Parvin (Supervisor) ; Ataei, Mohammad (Co-Advisor)
Abstract
Synthetic polymers have a high capacity to provide and manufacture the pieces used in tissue engineering. However, optimizing the biocompatibility, bioresorbableility and mechanical properties simultaneous with processability of material is complicated and requires a lot of effort at designing different parts of the system. On the other hand, due to existence of secondary bonds (such as metal-ligand coordination or hydrogen bond) supramolecular polymers are able to respond to some stimuli such as temperature, pH, or pressure, which is important in terms of dynamic nature of interaction between the living cells and the external matrix of cell. Recently there have been extensive studies on...
Design and Construction of Two-Wheeled Mobile Robot Platform with the Ability to Connect to other Robots with Two Rotational Degrees of Freedom
, M.Sc. Thesis Sharif University of Technology ; Sayyaadi, Hassan (Supervisor)
Abstract
Due to the advantages of multi-agent systems, research in this area and the use of these systems in industry are increasingly growing. Applying these robots, various complex tasks can be done faster, safer and with better results. In our country, many different algorithms have been proposed and simulated, but due to the lack of a real environment for implementation, their actual performance has not been assessed. This project aims to create a platform for research and development of this field. This goal is achieved by performing the first phase of implementation, namely the design and construction of the robot platform. In the first step, qualitative and quantitative characteristics of the...
Self-Assembly of Colloidal Particles in Liquid Crystal
, Ph.D. Dissertation Sharif University of Technology ; Ejtehadi, Mohammad Reza (Supervisor) ; Telo da Gama, Margarida (Co-Advisor)
Abstract
A nematic colloid is a mixture of microscopic particles dispersed in a nematic liquid crystal (NLC), which is an anisotropic fluid with long-range orientational order. This long-range order might be perturbed due to different reasons, such as confinement between flat or curved surfaces which leads to frustration of the nematic director in some singular points or lines called ”topological defects”. The nucleation and the structure of these defects emerge from the elastic properties of NLC and leads to unique behavior of nematic colloids. The interaction between colloidal particles in simple fluids are mainly excluded volume interactions, electrostatic interactions, van der Waals interactions,...
Theoretical Prediction of Free-Energy for Complex Macromolecules Self-Assembly
, M.Sc. Thesis Sharif University of Technology ; Tafazzoli, Mohsen (Supervisor) ; Ejtehadi, Mohammad Reza (Supervisor)
Abstract
These days, self-assembly is one of the most significant phenomena in chemistry and biology. Although There are some Experiments and Simulations which help us to understand self-assembly much more than before, their mechanism is poorly understood. As a result, Calculating Free-energy landscape could be a great development in this area.We use the Flat-histogram monte Carlo algorithm to calculate the density of states of a complex system. In this way, there is a comparison between the exact density of states of Ising Model and the same quantities that are obtained from Flat histogram Method. After that, there would be a combination of statistical thermodynamics and Graph theory toward drawing...
Study of the Affecting Factors on the Stability of G-Quadruplex Structures
, Ph.D. Dissertation Sharif University of Technology ; Tafazzoli, Mohsen (Supervisor)
Abstract
We used spectroscopic techniques to study self-assembled structures based on nucleobases like G-quadruplexes and macrocycles. Also we used DOSY NMR technique to study hydrogen bonding network in alcohol solutions. First part of our results indicate thermodynamic stability and slow kinetic of G-quadruplexes in apolar aromatic solvents like toluene. Also our results show easy monitoring of formation of each K+ or Na+ complex by NMR, due to the low solubility of alkaline metal salts in apolar media and possibility to stop at any given time in order to control G-quadruplex yield. When combined with suitable functional units, these valuable attributes may be used for the noncovalent synthesis of...
Preparation of Mesoporous Titania Film Using Block Copolymer Template in Application of Dye-sensitized Solar Cell
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
The Mesoporous Titanium Dioxide film using Sol-Gel method and Evaporation-Induced Self-Assembly technique (EISA) was prepared. In this study, in order to employ the best coatings in anode electrode of dye-sensitized solar cell, different conditions of making this film, the effective parameters in final structure, and various methods of coating were analyzed. After optimizing the conditions of film creating, images of field emission scanning electron microscope (FESEM) proved the formation of a layer of mesoporous structure which thickness after three times of coating is about 1.5 micrometers. In order to increase the energy conversion efficiency of solar cells, a new formulation for...
, M.Sc. Thesis Sharif University of Technology ; Shahrokhian, Saeed (Supervisor)
Abstract
This experimental work is of two parts. First, self-assembled monolayers of cysteamine was formed on the gold electrode surface which leaded to the formation of amine groups on the surface; then amine bond was formed between these amine groups and the carboxylic acid groups of acid treated multi-walled carbon nanotubes (MWCNTs). The modified electrode was used for voltammetric determination of dopamine in the presence of uric acid. In the second part, acid treated MWCNTs were decorated with ruthenium nanoparticles; then the resulting composite was used for surface modification with the exact same procedure as the first part. Ruthenium nanoparticles on the electrode surface were...
This experimental work is of two parts. First, self-assembled monolayers of cysteamine was formed on the gold electrode surface which leaded to the formation of amine groups on the surface; then amine bond was formed between these amine groups and the carboxylic acid groups of acid treated multi-walled carbon nanotubes (MWCNTs). The modified electrode was used for voltammetric determination of dopamine in the presence of uric acid. In the second part, acid treated MWCNTs were decorated with ruthenium nanoparticles; then the resulting composite was used for surface modification with the exact same procedure as the first part. Ruthenium nanoparticles on the electrode surface were...
Growth of Polymer/TiO2 Nanostructures by Layer-by-Layer Self Assembly Method as Electrodes of Photoelectrochemical Cells
, Ph.D. Dissertation Sharif University of Technology ; Taghavinia, Nima (Supervisor) ; Shahrokhian, Saeed (Co-Advisor)
Abstract
Dye sensitized solar cells (DSCs) are among the 3rd generation solar cells which their mechanism of light absorption is similar to chlorophyll in green leafs and is based on photo-excitation of dyes. The electron-hole pairs of photo-excited dye separate at the interface of mesoporous semiconductor-dye-electrolyte. One of the approaches to increase the light path length and therefore the light harvesting efficiency in DSC is the addition of light scatterers inside the mesoporous semiconductor (photoanode).In this research, nanoparticulated hollow TiO2 fibers are introduced as novel light scatterers in DSCs with simultaneous light scattering, light trapping and high surface area. Light...
Reinforcement Learning Approach in Self-Assembly Systems to Acquire Desired Structures
, M.Sc. Thesis Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor)
Abstract
Self-Assembly (SA) plays a critical role in the formation of different phenomena in nature. This phenomenon can be defined as an arrangement of meaningful patterns with the aggregate behavior of simpler structures. One of the examples of Self-Assembly can be considered of the formation of ice crystals from ice molecules. Previous works mainly focus on graph grammar and self-assembly in fully observable environments. These algorithms mainly consist of two main stages: first, constructing simpler structures and then joining these simpler structures to form a complex structure. The challenges of the previous work can be considered as the necessity of a central controller in the formation of...
Design, Expression, and Evaluation of Nanoparticle Structure Containing Malaria Vaccine Candidate Antigen by Self-assembled Peptide Nanoparticles (SAPNs) and Confirmation of its Antigenicity Using Serum of Malaria Patients
, M.Sc. Thesis Sharif University of Technology ; Alemzadeh, Iran (Supervisor) ; Abouei Mehrizi, Akram (Supervisor) ; Sardari, Soroush (Co-Supervisor) ; Zakeri, Sedigheh (Co-Supervisor)
Abstract
Malaria is one of the most important infectious diseases in the tropical and subtropical regions of the world and is caused in humans by the bite of the female Anopheles mosquito of five species of Plasmodium. According to the World Health Organization, about 229 million people worldwide were infected in 2019 by the disease, and 409,000 people died from the disease. Resistance of the parasite against drugs and resistance of vectors to insecticides and larvicides, which prevents the elimination and eradication of malaria, shows the need for new strategies, such as having an effective vaccine against this disease. In the second generation of vaccines, to develop malaria vaccines, recombinant...
Investigation the Effect of Formamidinium Lead Halide on the Stability and Performance of Graphene Phototransistors Based on Lead Sulfide
, Ph.D. Dissertation Sharif University of Technology ; Simchi, Abdolreza (Supervisor)
Abstract
Enhancing the detection range, sensitivity and stability of phototdetectors due to their vast applications are in great importance. In recent years, Lead sulfide quantum dots, in order to their absorption over a wide range of wavelengths including Near-infrared (NIR), multiple exciton generation effect and solution processability are promising materials.However, long organic surface ligands which are necessary in synthesis process can suppress the carrie transport and the common method to overcome this weakness, is ligand exchange process. In this way, using short organic ligands because of their low electron mobility and methylammonium lead iodide ligands in order to their instability,...
Autonomy and Control of Swarm USVs with Self-assembly and Picking Objects Capabilities
, M.Sc. Thesis Sharif University of Technology ; Sayyaadi, Hassan (Supervisor)
Abstract
Today, robots have been widely used in various tasks. Swarm robots are the focus of many researchers because of their low cost and their flexibility. However, due to the nature of dynamics in water and locomotion systems in it, very few of them have been developed. Applications of Swarm Robotics at sea include: the formation of temporary sea bridges, the collection of marine litter, assistance to large ships for maneuvering in ports, and carrying of oceanographic sensors. Therefore, the purpose of this study is to design a system for self-control and autonomy of unmanned surface robots with the ability to connect and carry objects. First, the robot was modeled according to its hydrodynamic...
Collective Motion and Molecular Assembly of Nanocars on the Surface
, Ph.D. Dissertation Sharif University of Technology ; Nejat Pishkenari, Hossein (Supervisor) ; Ejtehadi, Mohammad Reza (Supervisor)
Abstract
In the present thesis, the movement of the clusters of fullerenes and nanocars are separately investigated on graphene surface, using molecular dynamics simulations. Investigating the fullerene clusters with different populations, it is concluded that, as the number of molecules inside the cluster increases, the displacement range of the motion decreases. In fact, some parts of the energy of the fullerene cluster are wasted through the intermolecular interactions, and as a result, the mobility of the cluster diminishes. During the investigation of the three-dimensional structures of fullerene, the wetting property of the clusters is revealed relative to the graphene surface. The decrease of...
Self‐assembled, nanowire network electrodes for depleted bulk heterojunction solar cells (Adv. Mater. 12/2013) [electronic resource]
, Article Journal of Advanced Materials ; March 2013, Vol. 25, Issue 12, PP. 1768 ; Bai, Jing ; Masala, Silvia ; Thon, Susanna M ; Ren, Yuan ; Kramer, Illan J ; Hoogland, Sjoerd ; Simchi, A. (Abdolreza) ; Koleilat, Ghada I ; Paz‐Soldan, Daniel ; Ning, Zhijun ; Labelle, André J ; Kim, Jin Young ; Jabbour, Ghassan ; Sargent, Edward H ; Sharif University of Technology
Abstract
A solution-processed, bottom-up nanowire network electrode is developed and employed in a bulk heterojunction colloidal quantum dot solar cell. The electrode features a ZnO template which is converted into locally connected, infi ltratable TiO2 nanowires. The new electrode allows the application of a thicker light absorbing fi lm without compromising the charge extraction, as reported by Edward H. Sargent, Ghassan Jabbour, and co-workers on page 1769. The frontispiece shows schematically the electrode shape and the resultant device architecture
Flower-like boehmite nanostructure formation in two-steps
, Article Journal of Coordination Chemistry ; Volume 67, Issue 3 , 1 February , 2014 , Pages 555-562 ; ISSN: 00958972 ; Zanganeh, S ; Rajabi, A ; Allahkarami, M ; Rahbari Ghahnavyeh, R ; Moghaddas, A ; Aieneravaie, M ; Asadizanjani, N ; Sadrnezhaad, S. K ; Sharif University of Technology
Abstract
Reaction between AlCl3 and TEA (triethanolamine) gave Al(OH)3 colloidal nanocrystals that were precursors to nucleation and growth of boehmite under hydrothermal conditions. Transition electron microscopic (TEM) observations revealed that flower-like nanostructures were produced through a binary self-assembly system. In the first stage, nanostrips organize themselves to form a bundle, because of NH4 + and TEA. In the second stage, the bundles form flower-like nanostructures due to the interaction of nitrate with TEA. The size of the nanopetals (length 100-200 nm; width 100-150 nm; and thickness 20-70 nm) was measured through TEM. X-ray diffraction and Brunauer-Emmett-Teller (BET-N2) results...
Rapid and simultaneous determination of tetracycline and cefixime antibiotics by mean of gold nanoparticles-screen printed gold electrode and chemometrics tools
, Article Measurement: Journal of the International Measurement Confederation ; Vol. 47, Issue. 1 , 2014 , pp. 145-149 ; ISSN: 02632241 ; Mani-Varnosfaderani, A ; Sharif University of Technology
Abstract
The screen-printed gold electrode (SPGE) modified with the formation of self-assembly monolayer (SAM) of cysteine (Cys) on gold-nanoparticles (Au nano) was utilized for rapid and simultaneous determination of tetracycline and cefixime antibiotics by square wave voltammetry (SWV). Electrochemical investigation and characterization of the modified electrode was achieved using cyclic voltammetry (CV) and scanning electron microscopy (SEM). A principal component artificial neural network (PCANN) with three layer back-propagation network was utilized for the analysis of the voltammogram data. It is possible to simultaneously determine the tetracycline and cefixime concentrations in the ranges of...
Application of sol-gel based molecularly imprinted xerogel for on-line capillary microextraction of fentanyl from urine and plasma samples
, Article Analytical Methods ; Volume 5, Issue 24 , 2013 , Pages 7096-7101 ; 17599660 (ISSN) ; Piri-Moghadam, H ; Bayat, P ; Balalaie, S ; Sharif University of Technology
2013
Abstract
A molecularly imprinted xerogel (MIX) for fentanyl was successfully prepared on the inner surface of a copper tube by sol-gel technology. Primarily, the tube was treated by self-assembly monolayers of 3-(mercaptopropyl) trimethoxysilane and then [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane was employed as a precursor for imprinting the template molecule in acidic conditions. During the sol-gel process influential parameters including volume and concentration of fentanyl were carefully investigated to obtain the most efficient and appropriate xerogel. In parallel, a non-imprinted xerogel (NIX) was synthesized in the absence of fentanyl. The extraction efficiencies achieved from MIX and NIX,...
Self-assembled, nanowire network electrodes for depleted bulk heterojunction solar cells
, Article Advanced Materials ; Volume 25, Issue 12 , January , 2013 , Pages 1769-1773 ; 09359648 (ISSN) ; Bai, J ; Masala, S ; Thon, S. M ; Ren, Y ; Kramer, I. J ; Hoogland, S ; Simchi, A ; Koleilat, G. I ; Paz-Soldan, D ; Ning, Z ; Labelle, A. J ; Kim, J. Y ; Jabbour, G ; Sargent, E. H ; Sharif University of Technology
2013
Abstract
Herein, a solution-processed, bottom-up-fabricated, nanowire network electrode is developed. This electrode features a ZnO template which is converted into locally connected, infiltratable, TiO2 nanowires. This new electrode is used to build a depleted bulk heterojunction solar cell employing hybrid-passivated colloidal quantum dots. The new electrode allows the application of a thicker, and thus more light-absorbing, colloidal quantum dot active layer, from which charge extraction of an efficiency comparable to that obtained from a thinner, planar device could be obtained
Role of precursors and coating polymers in sol-gel chemistry toward enhanced selectivity and efficiency in solid phase microextraction
, Article Analytica Chimica Acta ; Volume 742 , 2012 , Pages 45-53 ; 00032670 (ISSN) ; Piri Moghadam, H ; Ahdi, T ; Sharif University of Technology
Elsevier
2012
Abstract
To evaluate the selectivity and efficiency of solid phase microextraction (SPME) fiber coatings, synthesized by sol-gel technology, roles of precursors and coating polymers were extensively investigated. An on-line combination of capillary microextraction (CME) technique and high performance liquid chromatography (HPLC) was set up to perform the investigation. Ten different fiber coatings were synthesized in which five of them contained only the precursor and the rests were prepared using both the precursor and coating polymer. All the coatings were chemically bonded to the inner surface of copper tubes, intended to be used as the CME device and already functionalized by self-assembly...