The radiofrequency dielectric behaviour of packed human erythrocytes has been investigated in normal haemoglobins F and AA and also abnormal haemoglobins homozygous S S and heterozygous AS. Dielectric measurements were made in tightly packed blood cells at an average room temperature of 26.5 i 0.5 "C in the frequency range from 0.1 to 100 MHz. In agreement with previous findings in many biological molecules, all the packed erythrocytes of the different haemoglobins exhibited a decrease in dielectric constant and an increase in conductivity with frequency. However, each type has been found to show distinct dielectric dispersion with respect to the others and this has been associated with their molecular structure in addition to the polarization of cell membrane. The possible application of this technique in identifying different haemoglobins of the blood has been suggested.

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A new supercell approach is presented to the calculations for quantum conductance of single-wall carbon nanotubes as a function of tube length L, diameter d, and chirality. It is shown that there is a conductance gap (dip) in infinite (finite) metallic non-armchair nanotubes due to the curvature-induced energy gap, while it is absent in armchair tubes. This mediates a dispute in experiments. A scaling of G = 2G0 exp[−βL/d 2 ] is obtained for the zerobias conductance where G0 = 2e 2 /h and β depends only on the chiral angle. This behavior can be well understood by a proposed tunneling model. c EDP Sciences