ISSN:
1432-1017
Schlagwort(e):
Pinus sylvestris L. (Scots pine)
;
Electrical impedance
;
Membrane capacitance
;
Transmission line
;
Cole-Cole α
;
Air space
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Physik
Notizen:
Abstract Electrical impedance spectra (80 Hz–1 MHz) in Scots pine needles were found to be characterized by spectrum skewness in the Cole-Cole plot. These spectra were subjected to analysis with two distributed models: (i) the Cole-Cole function and (ii) an equivalent circuit which takes account of the presence of air spaces within the needles (Model-A). In analysis with untreated needles (without artificial infiltration with water), Model-A fitted better than the Cole-Cole function to the experimental data. After infiltration of water into the needles, the extent of spectrum skewness was substantially decreased compared with the pre-infiltration condition and the Cole-Cole function fitted better than Model-A to the measured impedance data. The Cole-Cole α decreased from 0.47 in non-infiltrated needles to 0.42 in the infiltrated needles. The exceptionally large value of α in non-infiltrated needles can be explained by the presence of air spaces, which produce transmission line properties in the mesophyll. In support of the validity of Model-A, this new model provided specific membrane resistances of 1190 ± 83 Ω cm2 in cold hardened and non-hardened needles respectively. These specific membrane resistance are comparable with previous reports of membrane resistances in other biological systems. It is concluded that in this exceptionally spongy tissue, Cole-Cole α is likely to be due to the effects of the transmission line properties of cells which are surrounded by air spaces and only thin cell walls outside the insulating cell membranes.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00211405
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