Sharif Digital Repository

The tissue characteristics are important for all kinds of medical laser applications in order to understand the interaction mechanisms between light and tissue. Knowledge about light transport in tissue is essential for cancer treatment and cancer diagnostic techniques. By having the diffused reflectance of a tissue we can determine its optical characteristics. In this thesis we have solved the inverse process. That is, we compute the diffused reflectance of a turbid media with pre-determined optical parameters. This problem can be solved using two methods: Monte Carlo simulation and diffusion method. Since Monte Carlo simulation is computationally very expensive, it is not used in medical... 

Magnetic resonance imaging is one of non-invasive methods to measure the hemodynamic and morphologic parameters of tissues, especially brain tissues. Hemodynamic parameters monitoring in brain tissue is of significant importance in many majors such as detection of tumor occurrence, brain abnormalities, and track of treatment procedures. Blood is a suspension, comprised of plasma, red blood cells, white blood cells, platelet, etc. Plasma is a Newtonian fluid which is composed of proteins and has a constant viscosity in body temperature. Rheological properties of blood are highly dependent on mechanical and rheological properties of its cells and this dependence is multiplied in narrow vessels... 

This research studies a 3D channeled myocardium scaffold with computational fluid dynamics. It proposes a mathematical model to evaluate the impact of oxygen carriers and scaffold geometry on cell growth in a 3D cardiac construct. The modeling results show that using 5.4% perfluorocarbon oxygen carrier (PFC) has increased cardiac cells density 15% of the initial seeded cells comparing to pure culture medium without PFC supplementation. Effects of the scaffold geometry on cell density in the construct were examined by increasing channel numbers and changing the construct length. The results show that increasing channel numbers (by 50% decreasing channels diameter and wall to wall spacing) the... 

In this study, at first the V2O5 spent catalysts were characterized. The aim was to identifying whether these catalyst may be regenerated. Then, for feasibility study of them, three methods were applied: washing, diffusion and milling the spent catalysts for their subsequent reproduction. A variety of techniques such as XRD, XRF, AAS, TPR and TPO were applied in order to identify factors contributing in vanadium pentoxide catalysts deactivation. The results showed that approximately all of pollutants caused their performance deterioration, while they still have some active phases. Then, the polluted catalysts were washed (their yield increased from 43% to 72.2%). In the underside of the... 

The progress in the design of nano-scale machines over the past decade has motivated researchers to study the concept of nano-communications. Inspired by biological systems,diffusion-based molecular communication (MC) systems have been proposed as a potential solution for communication in nano-networks where molecules are used as information carriers.Nano-networks are envisioned to facilitate revolutionary applications in areas such as biological engineering, healthcare, and environmental monitoring. In recent years, there has been a significant amount of work on various aspects of MC systems, including transmitter and receiver design, multiple access protocols, and network layer issues.... 

Molecular communication which is inspired by nature has emerged as a promising field in recent years for its potential applications in medicine, environment, tissue engineering, industry and so on. In molecular communication, molecules are the information carriers. One of the mechanisms of movement of molecules that does not require any infrastructure is Diffusion. Diffusion-based molecular communication in which molecules diffuse in the medium in order to reach the receiver, has two major problems: delayed and lost molecules. Due to the randomness of diffusion, molecules are usually received with varied delays, their order of reception is different from the order of transmission and even... 

Nanomachines are molecules inspired by natural molecular machines and are able to move and transport at the nanoscale. Due to the advancement of nanotechnology, the need to move materials and energy on a small scale is necessary more than ever. Nanocars are artificial molecular machines with chassis, axles, and wheels designed for nanoscale transport at materials’ surfaces. Understanding the dependence of surface dynamics of nanocars on the substrate’s physico-chemical properties is critical to the design of the transport properties of such man-made nanoscale devices. Among the multitude of potential substrates for the nanotransporters, graphene exhibits intrinsic ripples on its surface,... 

Molecular communication (MC) is a new paradigm, in which the molecules or ions are used as information carriers. MC has been proposed as a promising approach for abnormality detection and localization in a variety of micro-scale and macro-scale applications in biotechnology, medicine, and industry; such as air pollutant monitoring, agriculture, abnormality detection in pipelines, and drug delivery. The goal in some of these works is to detect the tumors, viruses, and infectious micro-organisms in the body or leakage and pressure drop in pipelines. If these abnormalities are detected, the next step would be localizing them to finding a solution or treatment, e.g., drug delivery, or targeted... 

The instability and contamination leakage through tailings dams is one of the major problems of them. These dams are usually constructed through self-consolidation with minimum compaction effort, so special attention must be given to the stability of these structures. In addition, tailings dams contain considerable amounts of metals and chemically soluble contaminants resulting from mining processes in their reservoirs, making them more likely to leak contamination from the dam's foundation and body, causing pollution downstream. The infiltration of various chemical contaminants into the soil may alter its hydraulic and resistance properties. Laboratory studies have shown that pore solution...