Sharif Digital Repository

Sulfur containing compounds are known as the most applicable group of organic compounds. Due to their medicinal and biological applications, dithiocarbamates are the most considerable among the many sulfur containing compounds. There are many procedures reported to synthesize these compounds as synthetic intermediates instead of thiophosgen and isothiocyanates. The reaction of amine and carbon disulfide is reported as the best and least hazardous way to synthesize this functional group. In this project heterocyclic compounds such as thiazoles, thiazolidine-2-thione, and 2-(alkylthio)thiazol-4(5H)-one derivatives were synthesized from the reaction of prepared dithiocarbamates with in situ... 

Considering the advantages of heterogeneous catalysts for the easy work up procedure, being eco-friendly, and the reusability, herein, two projects are carried out by metal-supported SBA-15 catalysts. The first one is the oxidative deprotection of trimethylsilyl ethers catalyzed Cr (VI) in the presence of TBHP as oxidant. In this project, trimethylsylil ethers are oxidized in good to high yields. The second project is the oxidative coupling of thiols to disulfides catalyzed by Fe (III) in the presence of hydrogenperoxide. This catalyst/oxidant system convets different aromatic thiols to corresponding disulfides efficiently  

The potential of phase change process in liquids at microscale has been a favorite for the scientists to fabricate this type of micropumps. To hold unidirectional flow in microchannels usually nozzle-diffuser arrangement is used. Due to the existence of difference in pressure drop in the nozzle and diffuser sections, one can see unidirectional flow through diffuser direction. The objective of this article is to analyze analytically the thermo-hydrodynamic behavior of the Isopropyl Alcohol (IPA) bubble of a phase change micropump. Considering the simultaneous effects of hydrodynamic and thermal characteristics of the bubble in the bubble generation chamber, and temperature-saturation... 

This research project contains two parts that investigating new approaches for becoming closer to green chemistry principals is clear in it. In the first part we tried to synthesis dithiocarbamate salts using aromatic amins and than Michael addition of them to prepare bifunctional dithiocarbamats. But we found ?-thiols as final product. In the second part of this project, we investigated the regioselective epoxide ring opening with aromatic amines by using boric acid and glycerol in water as a green media. Corresponding ?-amino alcohols were obtained with excellent yields and considerable regioselectivity. High yields of the products, mild reaction conditions, using green catalyst and water... 

The reaction of α-haloketones with a variety of dithiocarbamate derivatives for the synthesis of various 2-alkylthiothiazole heterocyclic compounds was investigated in this thesis. To this end, different dithiocarbamates were initially synthesized through the reaction of amines, carbon disulfide and various alkyl halides; then, these dithiocarbamates were reacted with α-bromoketones (bromoacetophenone and chloroacetone) resulting in the formation of range of 2-alkyl thiothiazoles. To optimize the reaction conditions, ethanol and water were tested as solvents in the presence of ZrCl4 as catalyst. According to the data obtained, ethanol was selected as the optimum solvent using ZrCl4 as... 

Porous burner technology has many advantages in comparison with conventional burners such as higher burner thermal performance, lower pollutants emission, high power ranges, fuel flexibility, compact geometry and higher turn down ratios. These kinds of burners are made of preheated porous combustion zone and combustion porous zone that have different thermophysical and geometrical properties. In this work, the transient one-dimensional multi-step premixed laminar reacting flows in a two-stage porous media burner have been investigated. The combustible mixture is considered H2-Air (9 species and 19 reactions) and CH4-Air (22 species and 49 reactions). In porous media, without lateral wall... 

Dithiocabamates are valuable compounds due to their wide application as herbicides, fungicides, antitumor and etc. Another aspect of dithiocarbamates is their application in coordination chemistry. In this project, 3-((pyridin-2-yl) methyl amino) propane nitrile was prepared via Michael addition reaction of 1-methyl¬amino¬pyridine and acrylonitrile in water. Then this compound was converted to its potassium dithiocarbamate salt via treatment with carbon disulfide in the presence of potassium hydroxide in tetrahydrofuran. The prepared ligand was used in complexation with metal salts of Zn, Hg, Ni and Sn to prepare their dithiocarbamate complexes. The structure of complexes was elucidated by... 

Thermopneumatic micropump is one type of positive displacement micropumps, which has many applications due to its relatively large stroke volume, low working voltage, and simple fabrication in microscale. In this paper, a numerical study of heat transfer and fluid flow in a valveless thermopneumatically driven micropump is presented. For rectifying the bidirectional flow, a nozzle and a diffuser are used as the inlet and outlet of the chamber. Since the fluid flow is induced by the motion of a diaphragm, the numerical simulation includes fluid structure interaction, which requires applying a dynamic mesh. The domain of solution is divided into two sections; the actuator unit, which contains... 

Contactless and nonintrusive methods in particulate manipulation have been considered by many investigations. Particularly the use of these methods in characterization of micro and nano flows is in the focus of interests. Laser usage in the particulate systems has been dramatically increased during the last two decades. Laser can be used either as an illustration or excitation source in these systems. So-called optical tweezers use the laser beam for particle manipulation and characterization based on the hydrodynamic interaction of the laser beam with particles. There are numerous works being conducted in the field of particulate manipulation and characterization using laser beam.Present... 

Pipe freezing has become well established in industry as a method of short-termisolation in order to carry out maintenance or repairs. It is often necessary to repair system components without plant shutdown or drainage of system having many piping structures which may have hazardous or expensive fluid. Therefore, a series of tests has been arranged to investigate the ice plug formation in two standard pipes with different diameter size. The freeze zone on the pipe has been created by means of an aluminum jacket which liquid nitrogen flows in it. In the tests the freezing time, amount of liquid nitrogen usage andthe pressure tolerance of ice plug have been determined. Moreover, the numerical... 

Nowadays environmental issues are of great importance and one of the most paramount issues is the quality of water, because clean water is vital to our existence. Besides different methods for water purification, water quality testing is a useful and needful tool. Traditional methods for determination of water quality parameters are mainly expensive, time consuming and require highly trained staff. In this study, we have described a centrifugal microfluidic platform (Lab- on – a- CD) for simultaneous determination of different physical and chemical parameters including Nitrite, Free Chlorine and pH. All of the processes from sample injection to detection are integrated on this low-cost and... 

Nowadays, cancer, which has been mentioned as the disease of the century, is the second leading cause of death throughout the world, and its incidence is constantly increasing. Isolation of circulating tumor cells is one of the most critical steps in diagnosing and controlling cancer progression. Due to the rarity of cancer cells compared to other cells in the blood sample, the isolation process requires optimal and high-precision devices. With the advent of inertial microfluidics, the ability to control the particles movement, the processing of blood samples as quickly and accurately as possible, and the viability of cells with a high percentage, introduced microfluidic systems as a... 

The prediction of deposition efficiency of submicron particles in the pulmonary alveoli has received special attention due to its importance for drug delivery systems, and for assessing air pollutants health risks. In this work, the pulmonary alveoli of a healthy human are idealized by a three dimensional honeycomb like configuration and a fluid-structure interaction analysis is performed to study the normal cyclic breathing hydrodynamics. A viscoelastic model is used for the mechanical behavior of alveolar wall tissue. In contrast to previous works in which the inlet flow rate is predefined, in this model a negative pressure is imposed on the outside surface of the alveolus which causes air... 

An acinus is defined as the complex of airways supplied by one first order respiratory or transitional bronchiole. In this part, the replenishment of oxygen at the alveolar surface occurs by a combination of convective air flow with diffusion of oxygen in the air. So for studying gas exchange in the lung, modeling gas species transport and exchange in an acinus is important. Due to lacking direct measurements of the distribution of oxygen (or carbon dioxide) concentration in the acinus, several mathematical models have been developed and studied by numerical simulations. But in none of them the influence of breathing pattern and the role of blood flow in restricting the gas exchange rate have... 

This projct includes the following sections: In the first section, Michael addition reaction of anthrone to nitroolefins is described in water without using any catalyst to prepare 9-(2-nitro-1-arylethyl)anthracene-10(9H)-ones. This method is green, efficient and gives high yields of products. The solvent effect is also investigated. In the second section, Considerable efforts have been directed in recent years towards the transition metal complex catalyzed oxidation of organic compounds such as olefins, sulfides, benzylics alcohols and phenolics. And due to the various advantages of supported heterogeneous catalysts and in our aim to develop a simple, more efficient and eco-friendly... 

These days, according to increasing requirement to the applications of clean rooms in industries in and within the developing industry of computer, positive indicators that show a real need to a compere comprehensive study and research about the Clean rooms, in oder to predict the distribution and dispersal of the particles. Correct determination of indoor airflow and particle concentration distribution results in new standard development for Clean rooms. As computational fluid dynamics has become a powerful tool for indoor airflow studies, in this research, influence of effective parameters on the flow and concentration distribution in clean rooms has been... 

In order to safe design and optimize performance of industrial systems which work under two phase flow conditions, it’s often needed to categorize flow into different regimes. In present work the experiments of two phase flow were done in a large scale test facility with length of 6m and 5cm diameter. Four main flow regimes were observed in vertical air-water two phase flows at moderate superficial velocities of gas and water: Bubbly, Slug, Churn and Annular. Some image processing techniques were used to extract information from each picture. This information includes number of bubbles or objects, area, perimeter, height and width of objects (second phase). Also a texture feature extraction... 

The present study examines both Direct Current (DC) and Alternating Current (AC) electroosmotic flows in a parallel plate microchannel. The method consists of a central finite difference scheme for spatial terms and a forward difference scheme for the temporal term. Asymmetric boundary conditions are assumed for Poison-Boltzmann equation used to determine the electric double layer (EDL) potential distribution. The potential distribution is then used to evaluate the velocity distribution for both DC and AC electroosmotic flows. The velocity distributions are obtained by applying slip boundary conditions on the walls to account for probable hydrophobicity of the surfaces. After determining the... 

Atherosclerosis is one of the most important and common causes of death in the world. Atherosclerosis typically affects medium and large arteries in the body and it leads to plaque formation in arterial wall. The first stage of plaque formation has been related to accumulation of low density lipoproteins in arterial wall.
The purpose of this research is presenting a four-layer model to describe the LDL transport in the arterial wall. The endothelium, intima, internal elastic lamina (IEL) and media are all treated as macroscopically homogeneous porous media and the volume-averaged porous media equations are employed to model various layers. The physiological parameters within the various...