Sharif Digital Repository

Titanium dioxide, due to its specific semiconductive properties, has been a highly investigated material for a variety of applications including gas sensors, hydrogen generation by water photoelectrolysis, photocatalysis, dye-sensitized solar cells and purification of water and air. Several recent studies have indicated that titania nanotubes have improved properties compared to any other form of titania for mentioned application. Titania nanotubes have been produced by a variety of methods including deposition into a template and hydrothermal processes. Anodic oxidation of titanium foil in a fluoride-based solution is one of the best methods to produce of titania nanotube arrays. Highly... 

Mobile and wireless services industry has been among the most attractive businesses recently and is progressing at a fast pace. In this huge industry various organizations and entities cooperate to deliver value to the end user. The mobile operator plays the pivotal role in this chain. Hence mobile operator’s market was chosen in this study as the representative of the industry. Market segmentation and customer satisfaction are the main topics of this study.
Market segmentation for MCI was done using data mining with two-step algorithm. Input data included the consumer behavior extracted from mobile post-paid bills. The results indicated five distinctive clusters. The next part included... 

In this study, aqueous two-phase systems (ATPS) containing Tween 20 as a biocompatible nonionic surfactant and three different salts (NH4HPO4, NH4CH3COO and Mg(CH3COO)2 ) were prepared and their extractive potential for Lysozyme enzyme was evaluated. These systems have surfactant-rich top phase and salt-rich bottom phase. Phase equilibrium diagrams at 23 ° C were obtained by using the cloud point method and the results were successfully fitted to the Merchuk correlation and their trends were correlated with the effective excluded volume (EEV) parameter. Afterward, the partitioning behavior of the lysozyme and its extraction efficiency in the systems of Tween 20/diammonium hydrogen phosphate,... 

Oil refineries, petrochemical factories and oil platforms produce a large amount of oily wastewater every day. If these wastewaters are released in environment, it can damage soil and water seriously. Although, Biological treatment of oily wastewaters is a well-established method for remediation of these wastes, efficiency of conventional systems such as Activated Sludge, aren’t very high. Also these systems have many problems such as instability during hydraulics shocks and bulking phenomena. the hybrid bioreactor system are designed to increase the efficiency of treatment by allowing greater organic loads, increasing microbial concentration by using attached and suspended bacteria, and... 

In this study designing and manufacturing of high-temperature fluidized bed reactor were performed. These reactors are based on the contact of fluid with solid particles and balancing the weight of the solid materials. In the manufactured reactor, reduction of manganese de oxide to manganese oxide was done by carbon monoxide produced from incomplete combustion. The most important parameters in the reduction rate are: bed temperature and reduction gas concentration. Materials were injected into the reactor under the pressure of 1.13 mmHg and temperature of 787 ℃ in the bed depth of 4 cm for 2 hours and then the product was removed. XRD patterns showed that the dominant phase in the product... 

The experimental investigation of biodiesel production stages from microalgae especially biomass production stage was conducted in this thesis. The optimal rate of biomass productivity was determined.
A photobioreactor was designed and constructed to cultivate microalgae C. Vulgaris according to researchers’ works and obtained results in this study. The process parameters were examined and the optimal parameters were obtained according to the necessary tests which were carried out.
According to the results, the optimal condition for growing of microalgae was obtained with aeration of 6 lit/min with 3% CO2, and CO2 injection regime of 45 sec. injection and 3 min. of stoppage. A rapid... 

Dietary CLA production for medicinal purposes needs a safe and selective process. Biological production methods meet this goal. In this study, the microbial species that was suitable for CLA production was selected; then the CLA produced by bioconversion methods was utilized to produce CLA-enriched triglycerides by trans-esterification. Also the biochemical kinetics of CLA production and esterification reactions to produce CLA-enriched triglycerides was studied. In the presence of two substrates, the kinetics of enzymatic reaction was studied. Then the factors influencing on the microbial yield and CLA production including reaction conditions (reaction time, cell concentration and substrate... 

Cancer has been known as one of the main reasons for disease-related deaths in the last decades. Early diagnosis could significantly reduce the level of fatality chances. Among the known cancer types, lung cancer is one of the most malignant ones. The common diagnosticmethods are expensive and using high-technology methods; therefore, the introduction of simple and cheap methods is very urgent to detect it. In this project, surface and interfacial tension measurement of cancerous and normal lung cells have been investigated as an easy detection technique. Among the common measurement methods, Pendant Drop and Capillary height techniques have been utilized in this research work. The obtained... 

In this work, the recovery of rhenium from ferromolybdenum furnace outgoing dust in semi industrial scale was conducted. The ferromolybdenum furnace outgoing dust contains rhenium as major part and large amounts of molybdenum plus Iron and copper as impurities. An overall flow sheet, consist of leaching, solvent extraction and precipitation methods, was design to recovery and purification of rhenium. Firstly, ferromolybdenum furnace outgoing dust was subjected to leaching treatment by 10 g/L sulfuric as solvent at 85 C. Secondly, solvent extraction method was employed, using LIX984N 10 %vol, to separate copper from rhenium containing solution. The results of MacCab thiele diagram for... 

Mechanosensitive (MS) channels are ubiquitous molecular force sensors that respond to a number of different mechanical stimuli including tensile, compressive and shear stress. One of the main mechanisms to functionally study these channels is the patch clamp technique. Here we use continuum mechanics to probe the question of how curvature, in a standard patch clamp experiment, at different length scales (global and local) affects a model MS channel. Firstly, to increase the accuracy of the Laplace’s equation in tension estimation in a patch membrane and to be able to more precisely describe the transient phenomena happening during patch clamping, we propose a modified Laplace’s equation. In... 

In this work, partitioning of amino acids such as glutamic acid, phenyl anine and tryptophan in aqueous and ionic liquid phases at 298.15 K and atmospheric pressure was measured. [C4mim][Tf2N] is used due can produce two phase with water rapidly. Studying the effect of liquid solution pH on amino acids partitioning shows that increasing of pH results in decreasing of amino acid partitioning coefficient. This phenomenon pertains to electrostatic interactions between cation of amino acid and anion of ionic liquid which reduces when pH increases. Considering the effect of pH, liquid-liquid equilibrium data of amino acids was obtained in a pH that owning maximum partioning coefficient. Chemical... 

According to human needs and in line with the development of advanced technologies, different biomedical Engineering fields like hard tissue implants are growing rapidly. Despite significant biotechnology Developments in recent years, some problems to the recognition of implants related osseointegration phenomena persist. The deficient osseointegration and implant-associated infections are key issues for the long-term clinical success of titanium and titanium alloy implants, while development of multifunctional surfaces that can simultaneously overcome these problems remains highly challenging. Therefore, the ultimate goal of this paper was to improve bone cell attachment and simultaneously...