Sharif Digital Repository

A global concern has arisen owing to rapid industrial development and population growth, resulting in energy scarcity and earth pollution. In this regard, developing green and sustainable methods for producing clean energy and solving environmental pollution problems have absorbed enormous attention. Among various auspicious strategies, semiconductor photocatalysis has been widely studied in recent years owing to its capabilities to obtain hydrogen as an energy carrier, to remove organic pollutants, and to reduce CO2 emission by converting solar energy into chemical energy. Recently, a metal-free semiconductor photocatalyst based on graphitic carbon nitride, g-C3N4, has received much... 

Titanium nitride-carbon nanocomposites are synthesized by the reaction of TiCl4 and NaN3 in supercritical benzene medium that also serves as a carbon source. In order to improve the crystallinity of the as-prepared precursor (SI), it is further heat-treated at 1000 ˚C for 3-10 h using anhydrous ammonia and UHP nitrogen atmospheres at 1000 ˚C (SIII-SV). Moreover, to improve electrochemical behavior, the synthesized nanocomposite (SIV) is modified with Pt nanoparticles using a polyol process. For better understanding of synthesized catalyst nature and justifying their variant ORR activity several analyses are done. X-ray diffraction (XRD), Raman spectrum, field emission scanning electron... 

WO3 have good electrochromic, gas sensor, photocatalyst, phoelectrochemical (PEC) properties. due its properties, tungsten oxide have many application in technology and industry. In this thesis, pure WO3 thin film and MWCNT-WO3 nanocomposite thin films with different weight percent of MWCNT/WO3 utilize for energy domain, particular hydrogen production with phoelectrochemical reactions spiliting water. For this purpose, initially WO3 thin films were deposited on glass and ITO substrates using sol-gel dip-coating method. Optical and surface properties of the films dried at 100ºC and annealed at 400 ºC had been investigated. UV-Visible spectrophotometer, atomic force microscopy (AFM), X-ray... 

In recent years, bimetallic metal-organic frameworks have attracted the great attention of researchers due to their dual properties and synergistic effects. In this research and inspired by green chemistry, the synthesis of a magnetic nanocomposite of the defective green metal-organic framework was implemented, which carries metallic silver nanoparticles (Ag NPs@Cu-MOF). Then, the sulfonated compounds were synthesized with the prepared nanocomposite because of the importance and widespread medicinal use of sulfur-containing compounds especially sulfonated compounds, and the difficulty of their preparation methods. It is noteworthy to mention that the sulfonation reaction was done by... 

Due to the presence of carbon dioxide and hydrogen sulfide in natural gas outlet of wells, it cannot be sent directly to the municipal pipelines. This study was trying to be select and made membranes for separation of CO2 and H2S from methane. Permeability of methane and carbon dioxide gases through the polyurethane membranes were studied. For this purpose, two commercial polyurethane and synthesized polyurethane with different formulations of the compounds that have been studied so far in the literature were used. Synthesized polyurethane and nano-composite membranes were characterized by using Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and Fourier Transfer... 

Because of mistakes in the design and calculation, incoherence between construction and design, structural changes, changes in loads and also damages caused by the passage of the time, concrete structures need to be improved and strengthened. Polymeric sheets reinforced by fibers (FRP), according to their appropriate characteristic, are more efficient for strengthening concrete structures. Most studies on confined columns refers to confined RC columns with FRP and less mentioned about prestressed columns. In this study, the behavior of prestressed columns is analyzed by modeling a case of prestressed column in a nonlinear analysis software. Samples of confined concrete columns with CFRP and... 

For application as a biosensor electrode, Aligned Carbon Nanotubes (CNTs) were produced on Stainless Steel 304 substrate by optimizing the CVD method. For better performance, Zinc Oxide (ZnO) nanoparticles were coated on CNTs, using electrochemical deposition method at room temperature and process variables were optimized to acquire discrete particles with a narrow distribution. After that, Polyaniline, which is a conductive polymer, was electropolymerized on CNT/ZnO composite to further improve the electrocatalytic abilities of the electrode. The produced electrode was then used to detect glucose by Cyclic Voltammetry and Amperometry methods. This electrode shows a linear relationship... 

Proteins carry out most important roles in the organisms and they have a number of functions including structural, catalytically, regulatory and transportal, However for protein to have functional role they must be able to possess tridimensional structure. Several proteins due to various genetic and physico-chemical conditions have shown to alter their tridimensional structure leading to insoluble fibrilar structure. One of the properties of these insoluble fibrils is conformational change, converting to β-sheet rich structures; the entire process of converting soluble to proteins insoluble fibrils known as amyloid formation. The proteins amyloidosis have been seen as causative role in a... 

Most of the investigations during the two past decades focused on the effect of moisture and temperature on the bond at the interface of carbon or glass-fabrics and concrete, masonry or timber. Few investigations have studied the effect of chemical solutions, dry heat exposure and ultravilolent (UV) radiation on the bond at the interface of other types of fiber reinforced-polymers (FRPs) and masonry, timber and concrete in the short and long terms. Therefore, this research aims to investigate the effect of five chemical solutions with pH of 2.5±0.1, 7±0.1, 7.25±0.1, 10±0.1 and 12.5±0.1 on the interfacial bond strength between seven types of FRPs (unidirectional, bidirectional and hybrids)... 

Injection of acid into the carbonate rock dissolves the rock, and the porous medium is constantly changing. As a result, the boundaries between the acid and the porous medium, which are in fact the interface between the solid phase and the liquid phase, are constantly changing. Therefore, on the issue of acid injection into carbonate rock, we are facing dynamic boundary conditions. Also, due to the simultaneous solution of transfer and reaction phenomena, modeling acid injection into carbonate rock faces many challenges.In such problems, the ALE method, which is a combination of the best features of the Lagrangian method and the Eulerian method, offers a very precise solution and is used as... 

In this study the kinetics of extraction of various hydrocarbons from crude oil using supercritical CO2 has been studied experimentally. The effect of parameters such as temperature (35, 45, 55, 65 °C), pressure (90, 110, 130, 150 bar), initial volume of crude oil (16, 19, 22, 25 mL) were investigated. Flow rate of gas has been recorded dynamically. QUALITECH 4 and MATLAB neural network softwares have been used for designing the experiments and modeling the final results, respectively. Pressure has a direct effect on extraction yield and by increasing it, heavier fractions could be obtained. On the other hand, the effect of temperature is more complicated, by increasing the temperature, the... 

Pharmaceutical active compounds existence in the water would cause serious ecological risks and human health-related adverse effects which turn to environmental concern, therefore several studies have done to remove pharmaceutical active compounds efficiently. Carbamazepine (CBZ), a widely used psychiatric drug, is one of the most frequently detected compounds in the surface water and groundwater which is studies in the current study. Recently, biocatalytic degradation using ligninolytic enzymes such as laccase provides a promising approach for their removal from water and wastewater. In this work, carbamazepine removal by immobilized laccase on modified membrane by multi wall carbon nanotube... 

In this work, a model was presented for an MCFC fuel cell with internal reforming and combustion chamber. The model consists of mass and heat transfer equations beside the chemical and electrochemical reaction rate equations. Velocity distribution due to reactions and temperature distribution along the cell is considered. The model has been simulated in steady state form using finite difference method in MATLAB package environment accompanied by the analysis of the dynamic behavior of cell using method of lines in Simulink environment. Simulation results have been validated with experimental data extracted from literature. The last part of the work concerns with sensitivity analysis of some... 

Sustainable development is the basic aim of energy researchers. But common conversion technologies with respect to efficiency, fuel type and pollution of them, need basic operating improvement to reach sustainable development. Aim of this project is investigation of high temperature fuel cells as basic energy convertor. To improve performance of fuel cell system, four integration systemsare modeled and proposed. Using integrated systems in combined cooling, heat and power is another way of improving performance of systems, that is done in this project.
To improve system performance, the optimum operating values of these parameters is determined. In order to use four proposed system in... 

In this project dynamic effect of changes in gas turbine load on power plant, reforming and Co2 capture section is investigate. The reason for study of effects change of gas turbine load is that gas turbine determines the performance of the other parts in combined cycle including gas cycle and change of gas turbine load can alter the load and the performance of other parts in the power plant and in other process such as production of synthesis gas and carbon dioxide separation unit. One Autothermal reactor and eight sewgs reactor are utilized to produce gas turbine fuel which is mainly consist of Hydrogen. this part of thesis is to be implemented in the gPROMS from process system enterprise... 

Given the growth of the world's population along with the increase in the percentage of urban population by 2050, the way of responding to food consumption will change in the future. Controlled Environment Agriculture will largely account for future food supply. Vertical Farming is one of these systems. But despite the efficiency of these systems in terms of land and water and also not being affected by weather conditions, the main challenge in these systems is the consumption of energy use per unit of crop production. The cost of energy is about 25 to 40 percent of the total costs. The purpose of this study is to develop an integrated dynamic model for the determination of vertical farm... 

Although a lot of research has been done on Carbon-based interconnect, there are many important questions unanswered. For example, there is no compact model for the resistance of bundle of CNTs at high frequencies, at which interconnects will be operating due to the scaling. Also there are many studies comparing CNT, GNR, and Cu wires but there is no study to show how much this will impact the design of a chip at today’s Giga Scale Integration. This comprehensive study should include chip performance, power dissipation and total number of metal levels. These two big questions are investigated in this dissertation. In the first part, high frequency behavior of CNT bundles is studied. A... 

Rammed earth (RE) is an eco-friendly building material and has been capturing special attention among researchers. Many of the recently studied RE additives are extremely resource- and energy-consuming. On the other hand, the usage of fly ash (FA), which is a sustainable replacement for cement, has been scarcely investigated in RE construction. In this paper, an experimental investigation was performed on the physical and mechanical properties of RE materials stabilized with the combination of cement and alkali-activated FA. This scrutiny consists of density measurements, pulse velocity tests, unconfined compression tests, and direct shear tests. Additionally, the carbon dioxide emission and... 

In the first work, a novel voltammetric biosensor basedon TiO2-nafion-carbon nanoparticles modified glassy carbon electrode (TiO2/N/CNP/GCE) was developed for the determination of DBA. The electrochemical performance of the modified electrode was investigated by means of cyclic voltammetry (CV), different pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Characterization of the surface morphology and properties of TiO2/N/CNP was carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Effective experimental variables, such as scan rate, pH of the supporting electrolyte, drop size of the cast modifier suspension and accumulation... 

In this work, a novel type electrode based on RuO2 nanoparticles-modified vertically aligned carbon nanotubes (RuO2/MWCNTs) was investigated. ThisRuO2/MWCNTs electrode not only shows a high capacity nature,but also possesses a good response to the pH value. In order to develope this sensor, aligned carbon nanotubes were synthesized by the chemical vapor deposition at first and then modified with RuO2 nanopartcles by sol-gel method. Various parameters affecting the growth of nanotubes, such as substrate type, surface finishing, surface roughness, the growth temperature and carbon feed rate was studiedand and optimal conditions for growth were obtained. At last, aligned nanotubes with a...