Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG), and electrical impedance tomography (EIT) have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends.

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Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review.

The use of increasing debarking during the first harvest of cork oak trees (
 Quercus suber
 L.) had no effect on the secondary cork calliper (thickness) in one of the trials and had a small negative effect in a second trial. Little evidence was found that debarking coefficient is a useful index for the management of cork oak stands.
 The Portuguese national legislation defines, without the support of scientific data or knowledge, maximum values of debarking coefficients (ratio of debarking height and perimeter at breast height measured over cork). For the first debarking, this value is limited to 2.0. The aim of this study was to determine the impact of increasing cork debarking coefficient on the calliper of the secondary cork extraction. Trees were located in two sites, in distinct regions characterized by low or high productivity classes. Three debarking coefficients were considered: 1.5, 2.0 and 2.5. The debarking coefficient for the first cork extraction was randomly selected for each tree. During the second debarking, a cork sample was taken from each tree. The samples were used for assessing secondary cork calliper. Differences in cork calliper were analysed using both correlation analysis and modelling approaches. Debarking intensity increase had a small negative effect on secondary cork thickness in the most inland site, while no effect was detected in the more coastal site. In our experiment, debarking intensity had a significant but small effect in one site and no effect in other sites. Debarking coefficients not only should be defined according to legal constraints but also instead should be adapted considering tree and site characteristics.

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Does debarking intensity during the first cork extraction affect future cork thickness

https://link.springer.com/content/pdf/10.1007/s13196-021-00286-0.pdf

Radial variations of electrical properties of date palm stem

The dielectric constant (ε’) and dielectric loss factor (ε’’) were measured for sound and decayed heartwood specimens of Atlas cedar (Cedrus atlantica Manetti) wood (ACW) at its early stage of decay in longitudinal direction using frequencies between 10 Hz and 1 MHz at 12% moisture content and room temperature (22 24 °C). The changes observed in dielectric properties due to brown-rot decay of ACW showed loss in wood density (the mean densities of the sound and decayed heartwood specimens of 12% moisture content were 595 and 531 kg.cm, respectively). The results obtained indicated a direct relationship between dielectric constants decrease and density loss over the whole frequency range. The effect of thickness is also observed. The dielectric constant and the dielectric loss factor showed an important increase with the increase of the thickness, especially at low frequencies. Therefore the decrease in the values of the dielectric constants could be used as a good indicator of early wood decay. The changes in the dielectric properties were significant enough to distinguish between the samples from sound and decayed ACW.

Dielectric Properties of Atlas Cedar Wood at its Early Stage of Decay

is study examined the eect of bark stripping on the electrical impedance parameters of cork oak young leaves between 40Hz and 100 kHz. � is was a new application of the electrical impedances spectroscopy (EIS) in plant science. Various stripping coecients (CD) were applied on the trees. Bark stripping is expected to aect water metabolism of leaves and therefore changes in the EIS parameters are expected as well. Single-DCE (ZARC) model was used as equivalent circuit for leaves. Several electrophysiological parameters of this model were compared with moisture content (MC) of the leaves. Intracellular resistance (R i ), extracellular resistance (R e ) and relaxation time (�) of the leaves increased during 14 days aer stripping while the distributed coecient (�) and MC decreased. Signicant correlation between EIS parameters, MC and trees treatments were found.

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Noureddine Alami Chantoufi

Papers

Effect of bark stripping on the electrical impedance of Quercus suber leaves