Table Of ContentForeword
This Book contains a collection of papers presented at the 1st International Meeting on Applied Physics (APHYS-
2003), held in Badajoz (Spain), from 15th to 18th October 2003
(URL: .)mth.3OO2syhpa/3OO2syhpa/gro.xetamrof.www!/:ptth
APHYS-2003 was born as an attempt to create a new international forum on Applied Physics in Europe. Since
Applied Physics is not really a branch of Physics, but the application of all the branches of Physics to the broad
realms of practical problems in Science, Engineering and Industry, this conference was a truly inter-disciplinary
event. The organizers called for papers relating Physics with other sciences such as Biology, Chemistry, Information
Science, Medicine, etc, or relating different Physics areas, and aimed at solving practical problems, from an
transnational perspective. In other words, the Conference was specifically interested in reports applying the
methods, the training, and the culture of Physics to research areas usually associated with other scientific and
engineering disciplines.
It was extremely rewarding that over 800 researchers, from over 65 countries, attended the conference, where more
than 1000 research papers were presented. We feel really proud of this excellent response obtained (in number and
quality), for this first edition of the conference.
We are very grateful to all the members of the Organizing Committee, for the hard work done for the preparation of
the Conference (which began one year before the conference start), and to the members of the International
Advisory Committee, for the valuable contribution to the evaluation of submitted works. Also we would like to
thank Prof. F. Guiberteau from the University of Extremadura (Spain), Prof. R. Tannenbaum from the Georgia
Institute of Technology (USA), Dr. M.L.Gonzfilez-Martfn, from University of Extremadura (Spain), Dr. R. Chac6n,
from University of Extremadura (Spain), Prof. A. Martfn-S~inchez, from University of Extremaudra (Spain), for
their help as sessions Chairpersons, and to the referees for the excellent work done in the revision of submitted
papers (more than 600 research papers).
We were honoured to count on the following Plenary Speakers. We are extremely grateful to all of them, which
delivered excellent enthusiastic Lectures on some cutting-edge areas of Applied Physics.
Prof. Adam Curtis, Director of the Centre of Cell Engineering at the University of Glasgow, UK
"Nanobiotechnology - Interactions of Cells with Nanofeatured Surfaces and with Nanoparticles"
Prof. Allan S. Hoffman, Department of Bioengineering, University of Washington, USA
Prof. Lars Persson, Retired Scientist of the Swedish Radiation Protection Authority, Sweden
"Radiation Protection of Nuclear Workers - Ethical Issues"
K Alan Shore, University of Wales ,Bangor, UK. Head of the School of Informatics, Director of the ICON
Prof.
Centre of Excellence and Chair of the Institute of Physics (Wales)
"Chaotic Data Encryption for Optical Communications"
Finally, we would like to thank the Department of Physics of the University of Extremadura, and the Foundation for
the Development of Science and Technology in Extremadura (FUNDECYT), for their support, and the Regional
Government (Junta de Extremadura / Consejerfa de Educaci6n, Ciencia y Tecnologfa), as well as INNOVA
Instrumentaci6n, for sponsoring the Conference.
Thanks are also due to the following companies, which chose APHYS-2003 for presenting some of their most
interesting products for the conference audience:
Innova Instrumentacion
-
Attocube Systems - Positioning for the nanoworld
-
- Owis GmBH
- Shaefer Techniques
Nanotec Electronica
-
vi
Caburn, the Vacuum Components Company
- Alfa Aesar - Johnson Matthey
- - ATOS
- Kurt J. Lesker Company
- Advanced Design Consulting USA, INC
- EDP Sciences
World Scientific Publishers
-
American Scientific Publishers - Encyclopedia of Nanoscience and Nanotechnology
-
Without the efforts of everyone, the Conference could not have been such a success and this Book could not have
been published. We hope to see you in APHYS-2006!
A. M~ndez- Vilas
Editor
FORMATEX Research Centre, Badajoz, Spain
Phone/Fax: +34 924 258 615
e-mail: amvilas @formatex.org
vii
Local Organising Committee
.A Mendez-Vilas, Formatex, Badajoz, Spain lareneG( )rotanidrooC
J.A. Mesa Gonzalez, Formatex, Badajoz, Spain )yraterceS(
M.L. Gonzalez-Martin, Physics Department, University of Extremadura, Badajoz, niapS
M.J. Nuevo, Physics Department, University of Extremadura, Badajoz, Spain
.J Dfaz Alvarez, Organic Chemistry Department, University of Extremadura, ,zojadaB
niapS
.I Solo ed Zaldivar Maldonado, Innovatex S.L., Badajoz, niapS
A.M. ,oneroM-odrallaG Physics Department, University of Extremadura, ,zojadaB
niapS
.I Corbacho Cuello, Department of ,ygoloiborciM University of Extremadura, ,zojadaB
niapS
.L Labajos Broncano, Physics Department, University of Extremadura, Badajoz, niapS
.J Mesa Gonzalez, Innovatex S.L, Badajoz, niapS
.A Agudo Rodrfguez, Formatex, Badajoz, niapS
ix
International Scientific Advisory Committee
Surfaces. Interfaces. Nanosciences. Nanotechnology. Imaging Techniques
Prof. Klaus Kern, Max-Planck-Institute for Solid State Research, Nanoscale Science
Department, Germany
Prof. Raul .A Baragiola, Director of the Laboratory for Atomic and Surface Physics,
Engineering Physics, University of Virginia, USA
Prof. Federico Rosei. INRS-EMT Universit6 ud Qu6bec, Varennes (QC), Canada
Prof. Sven Tougaard, Physics Department, University of Southern Denmark, Denmark
Dr. M.L. Gonzalez-Martin, Biosurfaces Group, Physics Department, University of
Extremadura, Spain
Dr. M.J. Nuevo, Physics Department, University of Extremadura, Spain
Prof. Bronislaw Janczuk, Dept. of Interfacial Phenomena, Faculty of Chemistry, Maria
Curie-Sklodowska Universit, Poland
Dr. Randy Headrick, Department of Physics, University of Vermount, USA
Dr. .A Patrick Gunning, Institute of Food Research, Norwich Research Park, UK
Dr. Alberto Diaspro, LAMBS (Laboratory for Advanced Microscopy, Bioimaging and
Spectroscopy), Department of Physics, University of Genova, Italy
Prof. Buddy .D Ratner, Director, University of Washington Engineered Biomaterials,
Washington Research Foundation, Endowed Professor of Bioengineering and Professor
of Chemical Engineering, University of Washington, USA.
Prof. Igor Yaminsky, Head of the Scanning Probe Microscopy Group, Moscow State
University & Advanced Technologies Center, Moscow, Russia
Dr. Jos6 Angel Martfn Gago, Department of Surface Physics and Engineering, Madrid
Institute of Materials Science, CSIC, Spain
Dr. Terry McMaster, H.H. Wills Physics Laboratory, University of Bristol, UK
Materials Science. Applied Solid State Physics/Chemistry
Prof. Isaac Hernfindez-Calder6n, Physics Department, CINVESTAV, Mexico
Dr. Vasco Teixeira, Head of the Research Group GRF-Functional Coatings Group,
University of Minho, Portugal
Prof. Marfa Teresa Mora, Group of Materials Physics I (GFMI), Autonomous
University of Barcelona, Spain
Dr. Jos6 Manuel Saniger Blesa, Center of Applied Sciences and Technological
Development (Applied Research and Sensors), National Autonomus University of
Mexico, Mexico
Prof. Fernando Guiberteau, Materials Science and Metallurgical Engineering Area,
University of Extremadura, Spain
Dr A. Pajares Vicente, Condensed Matter Physics Area, University of Extremadura,
Spain
Prof. Miguel Avalos Borja, Department of Nanostructures of the Centre of Condensed
Matter Sciences, National Autonomous University of Mexico, Mexico
Prof. Giovanni Giacometti, Universit~ id Padova, Dipartmento id Chimica Fisica, Italy
Prof. Marcelo Knobel, Laborat6rio de Materiais e Baixas Temperaturas, Departamento
de Ffsica da Mat6ria Condensada, Instituto de Ffsica "Gleb Wataghin", Universidade
Estadual de Campinas, Brazil
Prof. Norman K.Y. Cheng, Electrical and Computer Engineering Department,
University of Illinois at Urbana-Champaign, USA
Computational Physics. Non-linear Physics
Prof. Francisco Jimdnez-Morales, Condensed Matter Physics Department, Faculty of
Physics, University of Sevilla, Spain.
Dr. Ricardo Chac6n, Assoc. Prof. of Applied Physics, School of Industrial Engineering,
University of Extremadura, Spain
Prof. M.A. Jaramillo, School of Industrial Engineering, University of Extremadura,
Spain.
M.J. Nuevo, Assoc. Prof. of Theoretical Physics, Physics Department, University of
Extremadura, Spain
Prof. Victor M. P6rez Garcfa, School of Industrial Engineering, University of Castilla-
La Mancha, Spain
Dr. Alberto P6rez Mufiuzuri, Faculty of Physics, University of Santiago de Compostela,
Spain
Prof. Jason A.C. Gallas, Institute of Physics, University of Rio Grande do Sul, Brazil
Dr. Francisco Balibrea Gallego, Faculty of Mathematics, University of Murcia, Spain
Dr. Pedro J. Martfnez, Technical School of Industrial Engineering, University of
Zaragoza (Group of Theory and Simulation of Complex Systems)
xi
Dr. Juan Jos6 Mazo, Faculty of Sciences, University of Zaragoza and CSIC, Spain
(Group of Theory and Simulation of Complex Systems).
Applied Optics. Optoelectronics. Photonics
Prof. Michael Gal, School of Physics, The University of NSW, Sydney, Australia
Dr. Manuel Martinez-Corral, 3D Diffraction & Imaging Group, Department of Optics.
University of Valencia, Spain
Prof. Augusto Bel6ndez Vfizquez, Departamento de Ffsica, Ingenierfa de Sistemas y
Teorfa de la Serial, Universidad de Alicante, Spain
Dr David Binks, Laser Photonics Group, Dept. of Physics and Astronomy, University of
Manchester, U.K
Dr. M. Isabel Suero Lopez, ORION Optics and Physics Education Research Group,
Physics Department, University of Extremadura, Spain
Dr. .A Luis Perez Rodriguez, ORION Optics and Physics Education Research Group,
Physics Department, University of Extremadura, Spain
Prof. Sergei Turitsyn, Photonics Research Group, Aston University,
Birmingham, UK
Prof. Ivan Chambouleyron, Institute of Physics "Gleb Wataghin", UNICAMP, Brazil
Biophysics. Biomedical Engineering
Prof. Oswaldo Baffa, Departamento de Ffsica e Matemfitica, FFCLRP-Universidade de
Sgo Paulo, Brasil
Dr Steven James Swithenby, Department of Physics and Astronomy, Group of
Bio-magnetism, The Open University, UK
Dr. Manuel Monleon Pradas, Director of the Center of Biomaterials, Dept. de
Termodinamica Aplicada, ETSII, Universidad Politecnica de Valencia, Spain
Dr. Jose Luis Gonz~lez Carrasco, Departamento de Metalurgia Ffsica Centro, Nacional
de Investigaciones Metahirgicas, Madrid, Spain
Dr. J.C. Knowlesm, Reader in Biomaterials and Head of Department, Department of
Biomaterials, Eastman Dental Institute, University College London, UK
Prof. Yu-Li Wang, Biomedical Engineering and Medical Physics, University of
Massachusetts Medical School, USA
xii
Radiation Physics/Chemistry and Processing. Radioactivity. Radiation Protection.
Medical Physics
Prof. Farid E1-Daoushy, Department of Physics, Uppsala University, Sweden
Prof. A. Martfn-Sfinchez, Department of Physics, University of Extremadura, Spain.
Prof. Lars Persson, Swedish Radiation Protection Society, Sweden
Dr. Abdus Sattar Mollah, Director, Nuclear Safety and Radiation protection Division
of Bangladesh Atomic Energy Commission, Bangladesh
Prof. Antonio M. Lallena, Department of Modem Physics, Specialized Group of
Nuclear Physics, University of Granada, Spain
Dr. Habib Zaidi, Head of PET Instrumentation & Neuroscience Laboratory (PINLab)
Geneva University, Division of Nuclear Medicine, Geneva, Switzerland
Dr. J6rg Peter, German Cancer Research Center, Head of the Functional & Molecular
Emission Computed Tomography Group, Germany
Dr A. Omri, Professor and Director of Drug delivery systems Laboratory, Department
of Chemistry and Biochemistry, Laurentian University, Canada
Dr. Ir. G.J.L. Wuite, Physics of Complex Systems, Division of Physics and Astronomy,
Free Universiteit of Amsterdam, The Netherlands
Dr. Yu-Chung Norman Cheng, Department of Physics, Case Western Reserve
University, USA
Dr. Akhtar A. Naqvi, Center for Applied Physical Sciences, King Fahd University of
Petroleum and Mineral, Dhahran, Saudi Arabia
Applied Physics (APHYS 2003)
A. M6ndez-Vilas (Ed.)
(cid:14)9 2005 Elsevier Ltd. All rights reserved
Absorption of RF Radiation in Confocal and
Uniformly Shelled Ellipsoidal Biological Cell
Models
J.L. Sebastig.n, S. Mufioz San Martin, M. Sancho and J.M. Miranda
Departamento de Ffsica Aplicada ,IH Facultad de Fisica.
Universidad Complutense de Madrid, Ciudad Universitaria 28040 Madrid. Spain.
Abstract. This paper presents a detailed calculation of the electric field distribution induced in
biological cell models exposed to a RF radiation. The study shows the importance of using
realistic cell shapes with the proper geometry dna electrical properties to study the mechanisms of
direct cellular effects from RF exposure. For this purpose, the electric field distribution within
confocal and shelled ellipsoidal cell models si calculated by using a finite element technique with
adaptive meshing. The cell models are exposed to linearly polarized electromagnetic plane waves
of frequencies 900 and 2450 MHz. The results show that the amplification of the electric field
within the membrane of the confocal shape cell si more significant than that observed in shelled
cell geometries. The results show the dependence of the induced electric field distribution on
frequency, electrical properties of membrane dna cytoplasm dna the orientation of the cell with
respect to the applied field.
INTRODUCTION
Exposure of a biological cell to RF fields can produce a variety of profound
biochemical and biophysical responses. However, any possible cell response is directly
related to the internal field distribution, and in particular to the modification of the field
strength across the cell membrane induced by the external RF radiation. Weak electric
field effects have generally been attributed, at least as a primary event, to field
interaction with either membrane or glycocalix constituents. The magnitude of
transmembrane voltage and the deposited energy are basic issues )2,1( for understanding
the relation between the exposition to fields and the subsequent physiological reactions
at the cell level. Considering that the membrane is a site of high field amplification, it is
uncertain how the detailed geometry and electrical properties of the cell can affect the
exactness of the predictions in the electric behaviour. Therefore, in order to determine
the mechanism of the basic interaction of RF fields with a biological structure, the
knowledge of the electric field distribution within the cell membrane is of primary
importance.
The analytical approach used by many researchers to find the cell internal field
strength has severe limitations since an explicit solution of Laplace equation requires a
geometry consisting in one or several uniform media separated by interfaces which
coincide with a surface of a constant coordinate, within a certain set of coordinate types.
Therefore, it turns out that only numerical methods can give a sufficiently precise
estimation of field values in realistic cell anatomies. However, conventional
computational methods have difficulties in dealing with a very thin membrane in a
shelled structure. It is for this reason that up to now, geometric configurations
representing more realistic cell shapes, such as ellipsoids (3), erythrocytes or rods with a
uniform membrane thickness have not been studied.
Detailed numerical calculations of the electric field within a mammalian cell with
basic spherical and cylindrical geometries have been already carried out by the authors
)5,4~ in previous works. The results indicated the important role played by the geometry
of the cell model in the electric field determination. These studies made also clear that
in order to have a good insight into the possible mechanisms of the action of
electromagnetic fields, including athermal effects, more realistic models than cylindrical
and confocal ellipsoidal geometries should be used.
This paper analyzes the influence on the internal electric field distribution of the
geometry and electrical properties of confocal and shelled ellipsoidal shape cells
exposed to a RF plane wave. The frequencies of the RF radiation used in this work are
900 MHz and 2450 MHz and both orientations of the E field (electric and magnetic
polarizations) with respect to the cell model have been considered. The numerical
technique used to calculate the field distribution is based on the well known finite
elements (FE) theory. However, the efficiency and precision of this technique have been
improved by using perfectly matched layers (PML) in the boundary conditions of the
radiation region and an adaptive mesh in the mesh sizes for the different cell layers. In
order to analyze the influence of the cell electrical properties, different values of
permittivity and conductivity for both membrane and cytoplasmh ave been considered.
CELL MODELS
Figure 1 shows the geometrical dimensions for the confocal and shelled ellipsoidal
cell geometries considered in this work to model a mammalian cell. The values of the
major and minor semi-axis for both geometries were kept constant to 3.5p and l~tm
respectively. For the confocal ellipsoid, the membrane is described within the same
coordinate system, which is determined by the foci of the ellipsoidal surfaces. For this
geometry, the maximum values of the non uniform thickness of the membrane along the
major and minor semi-axis are 01 nm and 5.8 nm respectively. For the shelled
ellipsoidal model, the membrane has a uniform thickness of 01 nm. The cell structure is
formed by two layers, cytoplasm and membrane, and the cell is considered immersed in
an external continuous medium formed by electrolytes in free water with the dielectric
properties of physiological saline.
ERUGIF .1 ladiospillE llec ,sledom )1 ,dellehs htiw mrofinu ssenkciht enarbmem dna )2 .lacofnoc
Table 1 shows the electrical parameters for the non conductive membrane and the
highly polarizable cytoplasm considered for the cell as well as those for the external
medium. At the higher frequency of 2450 MHz, the values used for the permittivity and
conductivity of the cell layers have been taken to be the same as those used originally
by Liu and Cleary ,)6( whereas for the lower frequency of 900 MHz the values of the
complex permittivity of the cytoplasm and external medium have been found using the
variations that correspond to the dielectric dispersion of bound and free water .)7( The
cytoplasm is a physiological saline solution with a protein volume fraction of 0.26,
whereas the membrane is made of a phospholipids bilayer that has no conductivity and
a frequency-independent relative permittivity of 11.3.
TABLE 1. Electrical Parameters for the Different Layers of the Cell Model at the two frequencies
used in this study.
Layer Parameter f = 900 MHz f = 2450 MHz
Cytoplasm e 2.05 996.84
a - mt~5.3 b = 1 mtk c = m.p5.0 rc )m/S( 299.0 714.1
5gt 593.0 412.0
Membrane e 3.11 3.11
mrofinU llehS d = mn01 rc )m/S( 0 0
rojaM sixaimes 01 mn Minor sixaimes 8.5 mn 5gt 0 0
External Medium e 87.17 78.07
rc )m/S( 749.1 187.2
5gt 245.0 882.0
In order to know the influence of the cell electric properties on its internal field
strength, the permittivity and conductivity of the membrane and cytoplasm have been
varied within reasonable ranges found in the literature .)8~ For the membrane, the
relative permittivity has been varied from 2 to 22 for both geometries, whereas the
conductance has been kept constant to a negligible value at both frequencies. For the
cytoplasm, the relative permittivity and conductivity have been varied from 30 to 70
and from 0.8 to 1.2 S/m respectively.
The radiation region in which the cell is immersed is filled with a continuous
medium formed by electrolytes in free water with the dielectric properties of
physiological saline.
ELECTRIC FIELD CALCULATION
In order to have a sufficiently precise estimation of the electric field distribution in
realistic cell geometries it is necessary to apply numerical methods. But up to date very
few studies of this type have been reported ,)4~ the main reason being the difficulty they
have to face in handling regions of very different size scales for the cell diameter and
for the membrane thickness. As the numerical solution of Laplace equation in the form
of finite differences involves a kind of polynomial approximation in nodes of a
convenient grid, the existence of very small domains makes it necessary to use a very
dense grid or alternatively sophisticated non-uniform meshing methods. As the cell
