Sharif Digital Repository

Dye-sensitized solar cells were introduced by M. Gratzel in 1991. These solar cells have a power conversion efficiency of about 12% over the AM1.5 full sun. Traditionally, a liquid electrolyte redox system is used to regenerate the dye. Due to stability issues, a solid hole transport material has been employed to replace the liquid electrolyte as an attempt to create solid-state Dye-sensitized solar cell (ssDSC). Over past few years power conversion efficiency of ssDSCs has improved considerably and reached over 7%.
Here, ss-DSCs based on TiO2 nanoparticles as photoelctrode and P3HT as hole transport material were fabricated and characterized. We used three different methods; dip... 

In this research we focus on fabrication and characterization of Dye and Cadmium based Quantum Dot Sensitized Solar Cells (QDSCs) based on TiO2 nanostructures. TiO2 nanorods were synthesized with a simple chemical method. TiO2 nanorods, TiO2 nanorod/TiO2 and ZnO nanoparticle composite structures were integrated as photoanode in dye sensitized solar cells (DSSCs). Incorporation of TiO2 nanoparticles into the bare nanorods increased the efficiency more than 45%. Monitoring electron transport properties of the cells, pointed out the crucial role of electronic structure of composite film components on the performance of cells. Suitable morphology of TiO2 nanorods, led us to use them, to make a... 

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... 

In this research we focus on study and fabrication of ordered nanotube arrays of titanium oxide and their applications in photoelectrochemical cell. Nanotubular films of titanium oxide have been fabricated using anodization method. Short-length nanotubes, less than one micrometer, have been synthesized in aqueous electrolyte containing deionized water, hydrofluoric acid and phosphoric acid. To get Micron-length nanotubes, we have employed organic electrolyte containing ethylene glycol, deionized water and fluoride ammonium. After fabrication, the photo-catalytic activity of nanotubular structures was evaluated by measuring the rate of degradation of in methylene blue aqueous solution. The... 

In this research, initially, thin film of TiO2 nanotube arrays (TNA) was deposited on Titanium foil (Ti), using anodization technique under an optimized applied voltage of 60 V, for 200 minutes. Highly smooth and ordered TNA formed by effective two-step anodization method. The TNA synthesized by this procedure, showed a better surface smoothness and tube order as compared with the TNA prepared in one-step anodization process. The electrolyte which was utilized for the anodization process, contained 90% of Ethylene Glycol (EG) in volume, 10% de-ionized water (DI) in volume, 0.1M Ammonium Fluoride (NH4F), and 0.5 ml Phosphoric Acid (H3PO4) 1M in order to adjust the pH about 5.6. Moreover, the... 

Fretting fatigue is one of the main factors leading to failure in structures that have components temporarily connected to each other. The occurrence of fretting at the connection region of a structure under cyclic loading is inevitable, and only various methods can delay its occurrence or minimize the damage resulting from it. Fretting is dependent on various factors, and this has made previous studies unable to lead to a unified approach for predicting the fretting fatigue crack initiation life. In this thesis, after reviewing previous studies, a proving ring is designed for fretting fatigue testing. In the next step, fretting fatigue tests using the bridge-type method are performed on... 

In various industries such as aerospace, biomedicine and automobile manufacturing, they seek to manufacture light parts with complex geometry and acceptable mechanical properties. Additive manufacturing processes have gained a special place in the field of rapid prototyping, reverse engineering, mold production, etc. brought It is very important to know the mechanical properties, especially the fatigue behavior of the parts obtained by this method. In this research, the stress-fatigue life graph of parts made of Ti-6Al-4V (grade 5), which is one of the most widely used alloys in aerial structures, was extracted by selective laser melting. For this purpose, several standard fatigue test... 

In contacts, the presence of both variable loading and low-amplitude movements causes a kind of fatigue in these components called FRETTING FATIGUE. fretting fatigue has reduced the life of parts. Due to the high cost of replacing some parts in case of failure, it is necessary to take effective measures to delay this exhaustion. One of the effective solutions that can be applied is the use of coating and surface treatments in the contact areas. In this research, first, the fretting fatigue maps of Ti-6Al-4V alloy have been calculated and drawn according to the recommendations of the ASTM standard by using finite element methods. In the next step, by using experimental experiments, the damage... 

Humic compounds are considered the most portion of natural organic matter (NOM) found in many surface water sources.Humic substances have been known as precursors to disinfection by-products.because conventional treatment process can not meet disinfection by-product standards,novel method have been increasingly applied for the removal of disinfection by-products precursors.The〖UV/TiO〗_2 process is one of the advanced oxidation process using the photocatalytic technology.The most important advantages of this process are its stability and high efficiency removal.The present study aims to investigate the effect of 〖UV/TiO〗_2photo-catalytic technology on removal of humic substances.In this... 

Flexible cones are one of the latest bone loss treatment methods in the ever-increasing revision total knee arthroplasty. This study is conducted to assess the biomechanical performance of the tibial flexible cellular cones in enhancing the initial stability of the implant system through the analysis of implant micromotion, as well as minimizing stress shielding through the analysis of strain distribution in the bone. The research evaluates the impact of various geometrical variables, including the thickness of the porous wall, the presence, type, width, number, and location of the inner solid wall notches on the spring stiffness and stress distribution of these cones. The research... 

Today, titanium and its alloys are the most widely used metals in manufacturing of biomedical implants. But unfortunately, most of bulk (nonporous) titanium alloys implants are facing problems such as stress shielding. If titanium is produced in such a way that has sufficient amount of porosity on the surface and inside of the sample, it provides sufficient space for connection and proliferation of new bone tissues and transmission of body fluids. However, machining of porous titanium causes pore closing. Due to the importance of recognizing the machining mechanism of materials such as porous titanium for manufacturing of implants, in this study micromachining of porous titanium with the... 

Connecting titanium and aluminum alloys is widely used in different industries such as transportation, chemical, aircraft manufacturing, etc. Friction stir welding is one of the methods of joining these two metals. In order to obtain a sound joint, the formation of intermetallic phases in the interface must be controlled. One of the ways to control these phases is the use of an interlayer, which in this research is the interlayer applied by plasma electrolytic oxidation method with different current densities and coating times. In this regards, first the optimal parameters of friction stir welding were determined. Then, Ti6Al4V and Al6061-t6 welding was performed in the presence of... 

Titanium carbide MXene (Ti_3 C_2 T_x) has attracted significant research interest because of its extraordinary advantages as advanced electrode material for energy storage. In this study, 4-aminodiphenylamine functionalized Ti_3 C_2 T_x/polyaniline composite synthesized by in situ growth of PANI on 4-aminodiphenylamine functionalized Ti_3 C_2 T_x nanosheets. First, Ti_3 C_2 T_x MXene nanosheets was prepared according to the minimally intensive layer delamination (MILD) method followed by sonication. Ti_3 C_2 T_x nanosheets were modified with 4-aminodiphenylamine diazonium salt. The FTIR، FE-SEM and EDS analysis were used to characterize modified Ti_3 C_2 T_x. Finally, the Ti_3 C_2 T_x... 

Tissue engineering is a science that tries to create new tissues by using cells, growth factors and appropriate biological materials in order to repair damaged organs and replace parts lost due to various reasons. In this research, the effect of adding mxene sheets on the oxidized alginate-gelatin hydrogel scaffold was investigated. For this purpose, mxene nanosheets were first synthesized by Max phase chemical etching and its synthesis was confirmed by X-ray diffraction spectroscoy, field emission scanning electron microscope, X-ray energy diffraction spectroscopy, Fourier-transform infrared spectroscopy, UV-visible spectroscopy. Then, in order to prepare the scaffolds, different amounts of... 

The aim of this research is to create coatings with antibacterial and superhydrophobic properties. To evaluate this, the sourness angle test, bacterial culture and halo diameter test have been used. The results show that 316L stainless steel containing PDMS+TiO2+7%Ag3PO4 coating, which is applied by immersion method on the substrate, has a water contact angle of 152 degrees, the number of bacteria cfu.cm2 is 44000 and the halo diameter is 24 mm. which has the best performance among other examples. In order to increase the adhesion of coatings on 316L stainless steel, first heat treatment was performed and then the samples were placed in H2SO4:H2O2 solution for 1 hour to form its OH- groups... 

Capacitive deionization (CDI) is a suitable method for water desalination with low energy consumption and high efficiency, which does not have secondary pollution and is environmentally friendly. The hybrid capacitive deionization uses a faradaic electrode next to the carbonaceous electrode, taking advantage of both electrodes, and high capacities have also been reported. Titanium carbide Mxene is an important candidate in CDI due to its high electrical conductivity and tunable interlayer distance, but Mxene suffers from low oxidation resistance. Therefore, in this research, molybdenum disulfide (MoS2) that is an essential member of the 2D transition metal dichalcogenides family, was used as... 

Nowadays, in many industrial applications, protecting surfaces has become necessary. This research attempted to create a coating resistant to the wear of NiCrBSi with the help of the atmospheric plasma spray and the process of plasma Transferred Arc on the substrate of the simple carbon steel. Also, in order to study the effect of compositing on hardness and abrasive properties of the APS coatings, NiCrBSi powder was strengthened with 25 weight percent of Titanium Carbide particles so that the NiCrBSi-25TiC composite coating could also be created. According to the nature of the APS process, the substructure of this coating always has some porosity and layered structure, and the connection of... 

The bladder is one of the most important internal organs of human that improper functioning of this organ causes various diseases such as bladder exstrophy, bladder syndrome, bladder cancer and bladder infection. The main challenge in treating these diseases is the presence of a mucous layer consisting of glycosaminoglysis (GAG) in the bladder wall that prevents drugs from reaching the surface of the bladder. Hence, drug delivery through the mucosal layer is not easy, Hence, urease micro/nano carriers have recently been considered for the treatment of bladder diseases. In this study, new janus micromotors based on black titanium oxide with asymmetric urease catalytic coating were synthesized... 

Enzyme-powered motors self-propel through the catalysis of biofuels, which makes them excellent candidates for biomedical applications. However, fundamental issues such as their movement in biological fluids and understanding the mechanism of propulsion are important aspects that must be considered before application in biomedicine. Building active systems based on biocompatible materials that use non-toxic fuels to power their vehicles have always been challenging. In this study, self-propelled micromotors consist of titanium dioxide black spheres asymmetrically coated with a thin layer of gold. Cysteine was used to bind urease enzyme due to thiol binding. By biocatalytically converting...