Sharif Digital Repository

Three-dimensional cell culture and forming multicellular aggregates is superior over traditional monolayer approaches due to better mimicking in vivo conditions and hence functions of a tissue. A considerable amount of attention has been devoted to devising efficient methods for the rapid formation of uniform sized multicellular aggregates. Restoring cartilage to healthy state is difficult due to low cell density and hence low regenerative capacity. Currently used platforms are not compatible with clinical translation and require dedicated handling of trained personnel. However, when engineering and implanting cell microaggregates in a higher concentration, new cartilage is efficiently... 

Significant advances in biotechnology have led to the emergence of a cost-effective way with less ethical issues to study disease, organ functions, tumors, and their response to drugs besides studying on animals. Microfluidic devices and organ on a chip (tumor on a chip) were introduced to remove those obstacles. Organ on a chip is a powerful tool for studying different types of tissues and simulating diseases, especially cancers, for biological and medical applications. Organ (tumor) on a chip is considered as a smaller scale of the real organ or tumor and it causes to the real-time study of tissues and their functions more accurately. In this study, to fabricate a droplet-based... 

Currently, one of the most important problems in the field of drilling is the issue of drilling fluid loss in different formations. The problem of mud loss has been evident since the beginning of oil and gas well drilling operations, so that oil companies spend millions of dollars annually to solve the problem of mud loss. Problems such as pipe jamming, loss of rig production time, well blowout, loss of a large volume of drilling mud and damage to reservoir formations due to loss of drilling fluid are caused. Regarding the drilling variables, many factors cause the decrease or increase of the loss, the most important of which are the weight on the drill bit, drilling speed, the rate of... 

Cancer spheroids are complex three-dimensional models of cancer cells that closely resemble in vivo tumors. Studying these models is essential for better understanding tumor biology, developing new drugs, and testing anti-cancer therapies. In this paper, we present a novel method for generating cancer spheroids using droplet-based microfluidics. This method is based on the formation of small droplets containing cancer cells in a microfluidic channel, which leads to the self-assembly of spheroids. We employ metal-organic framework (MOF) nanoparticles as drug carriers to enhance drug delivery to spheroids. ZIF-8, a porous MOF with the ability to load and release drugs in a controlled manner,... 

Despite the extensive research conducted so far to treat cancer, this disease is still one of the main causes of death worldwide. The results of recent studies reveal the importance of the tumor microenvironment in the growth, proliferation, and invasion of the primary tumor. Most common models in cancer research, such as 2-dimensional in vitro models and xenografts, do not have sufficient ability to mimic the interaction of tumors with human stromal tissue. Therefore, the implementation of 3-dimensional in vitro models with the ability to replicate tumor microenvironments is essential. In this study, a microfluidic platform has been introduced to create parallel models of the tumor... 

Access to potable water with standard quality is an inevitable component of human’s lives. Seawater desalination is the precedure of removing the impurities and contaminants in water to achieve the suitable quality for human consumption. Freeze desalination, by consuming relatively much lower energy compared to other techniques has shown to be a promising method for desalination. This technique requires the exertion of a cold source to the system which is then accompanied by simultaneous rejection of the impurities from the water. Regarding this, a numerical study on freeze desalination a hollow cylinder is carried out to determine the effects of the design variables such as heat flux,... 

Analytical biological research has gained significant attention due to the critical importance of processes such as cell separation, cell lysis, DNA purification, and amplification for disease diagnosis and genetic studies. These processes are essential in biological assays for molecular pathogen detection, immunological assessments, and studies on the effects of drugs on diseases. The objective of this research is to design and develop microfluidic systems in three main areas: cell separation, DNA extraction, and amplification for the identification of BRCA1 mutations. The cell separation platform is solely designed for simulation on a microfluidic chip, while the extraction and... 

Vascular tissue has a highly complex structure whose main function is to transport blood and supply oxygen and nutrients to body tissues. Because it is continuously exposed to blood flow and hemodynamic pressures, this tissue is always subject to special mechanical and biochemical conditions. Damage or obstruction in blood vessels can lead to serious cardiovascular diseases, the treatment of which requires advanced methods of reconstruction and replacement. Tissue engineering, as a novel approach for vascular tissue regeneration, has attracted significant attention. Scaffolds designed for vascular tissue engineering should not only possess mechanical properties similar to those of natural... 

Due to significant reduction in fossil fuel sources; several researches have been conducted recently to explore modern sources of renewable energy. One of the major fields in the category of renewable energy harnessing devices is parabolic trough solar collectors (PTC). Several parameters have effect on the overall efficiency of the PTC’s.As the effect of these parameters is coupled to each other, a comprehensive investigation is necessary.In the present study a numerical analysis is performed to examine the efficiency of PTCs via variation of several governing parameters (e.g. wind velocity magnitude, nanoparticles volume fraction, inlet temperature and reflector’s orientation). A detailed... 

Multi stage Pulse Tube Cryocoolers (PTCs) have found the interest of researchers due to its reliability, long life and absence of moving part. This thesis represents a comprehensive numerical simulation method to investigate one and two stage PTC. All components of the PTC are modeled employing the nodal analysis technique to discretize the mass, momentum and energy conservation equations. SUTPTC code has been developed in cryocooler laboratory of Sharif University of Technology (SUT) to analyze and optimize one and two stage cryocooler performance. The SUTPTC code has been validated with the existing experimental data. Employing the proposed code, the effect of precooling temperature, the... 

Physics of the present work is 2D two-phase immiscible flow under gravitational effect through fractured porous media and the most practical formulas for transfer function in dual porosity-dual permeability models have been implemented for numerical simulation of naturally fractured reservoir. The models are: Kazemi et al. (1976), Gilman (1986), Sonier et al. (1988), Quandalle and Sabathier (1989), Lim and Aziz (1995), and Rangel-German and Kovscek (2006), which are compared using a benchmark problem and the effects of gravity, capillary, number of matrix block subdomains and dual continuum media model are studied. The benchmark problem was adopted from Gilman (1986) and involves water... 

In this thesis, engine performance parameters such as power, torque, fuel consumption and in-cylinder pressure are investigated with considering ignition timing in order to achieve the minimum value of knock index. The implemented methods include engine dynamometer tests and simulating vehicle powertrain in GT- POWER software. Based on the acceptable precision of the GT-POWER model, it can be used to predict the engine performance in other ignition timings. Final results prove that for wide open throttle status altering the ignition timing to reach the minimum possible value impact differently on the engine performance so that in low engine speeds for basic and new ignition timings, a...