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1.
Med Prog Technol ; 21(3): 165-70, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-8776713

RESUMO

The complex permittivity of dehydrated bovine femoral bone has been studied in vitro, in the three orthogonal directions from 1 kHz to 3 MHz, as part of an analysis of the various factors involved in the dielectric behavior of fluid-saturated cortical bone. In this study the bone's physical structure reveals its anisotropic nature by its dependence on both the real and imaginary parts of permittivity on the orientation of the applied electric field. The real permittivity and the total conductivity are generally higher in the longitudinal direction than in the other two transverse directions, with the tangential direction presenting values between those of the longitudinal and radial directions and closer to the former. The high frequency limit of the real part of the permittivity was found to be around 10 and its low frequency limit is of the order of 1000. The dispersion parameters of relaxation time show values of about 0.4 and the corresponding mean relaxation frequencies are below 100 Hz.


Assuntos
Anisotropia , Osso e Ossos/fisiologia , Animais , Bovinos , Dessecação , Condutividade Elétrica , Fêmur/fisiologia
2.
IEEE Trans Biomed Eng ; 39(5): 523-6, 1992 May.
Artigo em Inglês | MEDLINE | ID: mdl-1526642

RESUMO

The relationship between the low-frequency electric properties in the axial, tangential, and radial directions, along the diaphysis of a femoral bovine bone, is presented. It is shown that below 1 MHz the relative permittivity of the diaphysis exhibits a significant positive correlation with respect to the low-frequency conductivity, as measured in any direction, and therefore it could be related to the amount of fluid contained in the channels that provide low-frequency electrical connectivity in the measurement direction. It was also found an absence of significant correlation between permitivity, in either of the three measurement directions, and the total fluid volumetric fraction in the bone.


Assuntos
Fêmur/fisiologia , Animais , Bovinos , Condutividade Elétrica/fisiologia , Eletrofisiologia/métodos , Técnicas In Vitro
3.
Med Biol Eng Comput ; 29(4): 441-6, 1991 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1787762

RESUMO

A preliminary study is presented of the variability of the electric properties, in the axial, tangential and radial directions, as a function of position in the diaphysis of a femoral bovine bone. The measurements were carried out at three frequencies: 100 Hz, 10 kHz and 1 MHz. It is shown that both the conductivity and the permittivity exhibit significant variations along the diaphysis, and increase in magnitude towards the epiphyses. From this study, the variation of the electric properties cannot be clearly and directly ascribed to the longitudinal variability of the total volumetric fluid content of the bone. The results reflect the orthotropic nature of the electric properties, at any given location, and indicate a position-dependent tendency towards axis symmetry.


Assuntos
Fêmur/fisiologia , Animais , Bovinos , Condutividade Elétrica , Eletrofisiologia
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