Effects Of Low Frequency Electric Fields Research Articles

Effect of low-frequency electric field assisted freezing on ice crystals of tilapia fish protein

The mechanism by which low-frequency alternating electric fields affect ice crystals and quality of aquatic products remain unclear. To study the effect of low-frequency electric field freezing (LF-EFAF) on product ice crystals, differences between LF-EFAF treated samples and air freezing (AF) were compared. The results showed that LF-EFAF increased the subcooling of fish protein by 0.3 °C and doubled the freezing time compared to AF. The equivalent diameter and cross-sectional area of LF-EFAF samples were reduced by up to 20% and 35% respectively, compared to AF samples. Moisture distribution of results showed that LF-EFAF restrained the increase in free water content of fish proteins. The LF-EFAF had a positive effect on the size and morphology. This resulted in less mechanical damage to the muscle fibres, which led to better water retention and inhibited moisture migration. Therefore, LF-EFAF can be an effective means of fish proteins preservation.

Boundary-element calculations for amplification of effects of low-frequency electric fields in a doublet-shaped biological cell

To examine the amplification of the effects of low-frequency electric fields due to the junction between the cells, the amplitude of transmembrane potential P(TMP0), the time-averaged normal stress sigma(n) and the outward force density sigma(out) on the shell-phase, and the squared intensity I(ee) of electric fields in the inner and the outer phases induced by uniform external ac fields were calculated with the boundary-element method for doublet-shaped cell models consisting of two spheres of the same size connected by the junction; the results were compared with those in a spherical model. When the external fields were parallel to the long axis of the doublet-shaped models, P(TMP0), sigma(n) and sigma(out) at the pole were greater than those in the spherical model, and sigma(out) and I(ee) at the junction increased with the decrease in the junction-radius. The external fields perpendicular to the long axis caused I(ee) greater than that at the center of the spherical model and negative sigma(out), at the junction. The amplification of P(TMP0), sigma(n), sigma(out) and I(ee) took place within restricted frequency-regions that could be specified by the characteristic frequencies for the frequency-dependence of the polarization factor of the models.

3P316 局所的変形をもった細胞に対する低周波交流電場の作用に関する境界要素法計算(その他)

3P316 局所的変形をもった細胞に対する低周波交流電場の作用に関する境界要素法計算(その他)

Microelectrode measurements of low frequency electric field effects in cells and tissues.

The average intensities of electric fields induced into tissue can be calculated if the morphology and conductivities of the tissue are known, and such values provide one estimate of dosage for a given field exposure level. However, the microanatomical structures of living tissue, which include gap junctions, tight junctions, highly charged cell coats, and extracellular matrices, as well as complex cell shapes, precludes a detailed characterization of the field and current distribution near the cells which are actually responding to the electric fields. This suggests that a more useful electric field dose metric may be one based on an induced physical effect on the cells. Electric fields have at least three distinct physical effects on cells: the normal plasma membrane potential will be altered; the ionic currents and ion distributions at the extracellular surface will be modified; and mechanical forces will be imposed at the cell surface. Each of these effects can, in principle, be measured through the application of specific microelectrode techniques. Here, the feasibility of using various intracellular and extracellular recording methods to obtain dosimetric values, as well as the contribution these measurements could make to our understanding of electric field interactions with biological tissue, are discussed.

Effect of Low-Frequency Electric Fields on Enzyme Reaction

Effect of Low-Frequency Electric Fields on Enzyme Reaction