Abstract

The biophysical studies of the biological system are far from being conclusive. Not only because this science is relatively recent, but also because of the lack of physical data. Also there are a lot of contradicting views among researchers as well as the poor theoretical interpretation of the reported experimental data. However, the advent of computer science with the considerable storage capability and highly vast calculations gives modeling techniques a great advantage and opens a real door to better understanding of the complicated biological phenomena. The present thesis addressed the problem of ionic penetration through biological tissue under the effect of external electric field (DC and AC). This was done by studying the diffusion coefficient D as an indicating parameter for such effects. The work was based on stochastic computer simulation of the problem such that the tissue was considered as a matrix that contains the elements under study. The size of the matrix was up to 30,000 x 30,000. Two dimensional honey comb cellular pattern was simulated such that it allowed six maximum possible element-to-element communications. The diffusants were let to diffuse under different electric field strengths in DC forward and opposite directions, and AC field with different frequencies. The effect of vacancies concentration and annealing time were tested in the absence of electric field. Two different vacancies concentrations were studied under the effect of electric field. Fist, 90% of the tissue was vacant and subjected to DC and AC fields as well as zero field. Second, 50% of the tissue was vacant and investigated under similar conditions. The results showed that for the 90% case, the penetration increased with increasing of electric field strength. While in the 50% case, the penetration increases with increasing the current until a point at which the diffusion is hindered. The DC results of forward current were compared to that of backward direct current and the results showed that the backward direction hindered diffusion. The effect of alternating current shows that penetration was inversely proportional with the frequency which agrees with literature. Comparisons of the effects of sinusoidal and square waves were illustrated. The square waves showed to have more ionic penetration and diffusion coefficient values than the sinusoidal ones. As the frequency of alternating current is decreased, its effect on diffusion became close to that of direct current. Despite the fact that the results obtained by simulation are in essence virtual and based on arbitrary units, yet the effects were clear and indicative.

Department

Physics Department

Degree Name

MS in Physics

Graduation Date

2-1-2013

Submission Date

January 2013

First Advisor

Elsheikh, Salah

Committee Member 1

El-Sheikh, Salah

Committee Member 2

El-Messiery, Medhat

Extent

118 p.

Document Type

Master's Thesis

Library of Congress Subject Heading 1

Ionic solutions.

Library of Congress Subject Heading 2

Ionic mobility.

Rights

The author retains all rights with regard to copyright. The author certifies that written permission from the owner(s) of third-party copyrighted matter included in the thesis, dissertation, paper, or record of study has been obtained. The author further certifies that IRB approval has been obtained for this thesis, or that IRB approval is not necessary for this thesis. Insofar as this thesis, dissertation, paper, or record of study is an educational record as defined in the Family Educational Rights and Privacy Act (FERPA) (20 USC 1232g), the author has granted consent to disclosure of it to anyone who requests a copy.

Institutional Review Board (IRB) Approval

Not necessary for this item

Comments

I want to express my deep appreciation to my advisors for accepting me as a MS student for this thesis, their advices were crucial for my research and learning experience. I express my deep thanks to Prof.Dr.Salah El-Sheikh who provided me with all the support to complete this thesis. In addition, he found the fund at the American University in Cairo for me to present the research work in the 7th Intertiol Workshop on Biological effects of Electromagnetic fields in Malta. I consider Dr.Salah not only my advisor, but a kind father who always supported me and helped me setting the priorities in my life. I sincerely thank Prof. Dr. Medhat El-Messiery who was a true inspiration since I entered the Masters program. He was the first who introduced me and others to the promising area of computer modeling and gave me an essence to its application in physics. He taught me how the physical phenomenon of diffusion could be alyzed and modeled. His expert experience helped me in interpreting the results of the model outcomes. The valuable discussion and continuous assistance which were so willingly given by Dr.Medhat during the course of this work will never be forgotten. I will always remember his professiol advices in the conference in Malta. His experience improved my research skills and prepared me for future challenges. Dr.Medhat is a true mentor for all his students. I also want to thank Dr.Noha Salem who encouraged me to complete the Masters degree. Her inputs in building the theoretical model were certainly helpful. I owe my deepest gratitude to Dr.Ahmed Shawky from the faculty of Computer Science at Cairo University and his students, Sara Salem and Doha Ehab. The interdiscipliry collaboration was made true with them. They gave us all the time and effort to transform our code from Matlab language to the C language. This transformation gave the chance for a broader application of the model and extremely saved time. It was a fruitful time which promises for more future team work. I sincerely express my deepest gratitude to the Chair of the physics department and colleagues at the Physics department for their faithful help and their beneficial support during the research program. It is an honor to have worked with my advisors. I learnt a lot, not only as a student, but also as a person, and I truly owe them for that. Thank you for making this thesis happens.

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