Sharif Digital Repository

Study on pool boiling heat transfer characteristics of water-based magnetic fluid and distilled water containing micro size particles has performed. Different concentration in each experiment has been studied to investigate the effect of magnetic fluid and micro size particles on boiling heat transfer on horizontal plate heater. The nickel particles was used as micro size particles which is expected to increase thermal performance of water due to high thermal conductivity of nickel. Experimental results showed adding nickel micro size particles to water can deteriorate the boiling heat transfer coefficient. However the amount of deterioration was the same for all concentrations of nickel... 

Various application of polyethylene material in different industries caused to modern techniques for controlling and measuring specifications of micro-particle suspension. Many industries try to increase stability of suspensions in front of their phase separation.
Because of the consequences of suspension homogeneity, at first, we measured this property. Then, the stability was tested by three different methods. In the first method, the transmitted laser light was measured to assay the suspensions stability. In the second, number of sediments of particles was counted. Sedimentation velocity of particles was measured directly by using a horizontal microscope as the third method. The... 

Immobilization of β-D-galactosidase represents an important approach for development of lactose hydrolysis technology.Chitosan proved to be an excellent carrier for β-Dgalactosidase immobilization, by both covalent binding and sol-gel entrapment combined with adsorption. Among different preparation methods of chitosan support particles for covalent binding, emulsion cross-linking was the most efficient, producing narrow-sized microspheres, without aggregation.The best process parameters of β-D-galactosidase immobilization by covalent coupling on chitosan microspheres were found as 3% glutaraldehyde cross-linker concentration, enzyme loading of 27 mg protein/g dry support, 6 h reaction time,... 

In many microfluidic devices, focusing particles into a narrow stream is usually an essential step prior to counting, detecting, and sorting them. By installation of microfluidic laboratory functions on a rotating disk, new devices called Lab-on-a-disks, which have plenty of advantages in comparison to ordinary Lab-on-a-chips, shape. In this study, to the best of our knowledge for the first time, a Lab-on-a-disk device is designed and fabricated in order to focus particles prior to detecting them by a conventional CD-ROM as a strong optical system. Hydrophoresis method, using slanted obstacles to induce transverse pressure gradients, is utilized to focus particles. In this regard, the... 

In the presence of spatially non-uniform electric field, a dielectric object can experience a translational force which is known as Dielectrophoresis (DEP) force. DEP is one of the most applicable methods in sorting mechanism of different biological cells. Moreover accurately measuring the DEP force in single cell level can lead to a valuable knwoledge about the electrical properties of various cells.In this thesis, first, the other electrokinetic forces in which the Electro-Osmosis (EO) force is the important one, have to be eliminated. Regarding that this effect is strongly dependent on the frequency of external E field, we have applied the external electric field at appropriate frequency...