Dielectrophoretic spectra of translational velocity and critical frequency for a spheroid in traveling electric field.

An analysis has been made of the dielectrophoretic (DEP) forces acting on a spheroidal particle in a traveling alternating electric field. The traveling field can be generated by application of alternating current signals to an octapair electrode array arranged in phase quadrature sequence. The frequency dependent force can be resolved into two orthogonal forces that are determined by the real and the imaginary parts of the Clausius-Mossotti factor.

Discovery of "punch-through" or membrane electrical breakdown and electroporation.

As part of a detailed study in Alex Hope's laboratory of the V-I characteristics of the membrane of the giant cells of Chara corallina, it was discovered that at a well defined potential difference of around 500 mV (depending on the temperature), the cell membrane undergoes a reversible electrical breakdown. The author coined the word "punchthrough" to describe this electrical breakdown phenomenon. Detailed studies followed on the nature of this electrical breakdown phenomenon, in various cells, aimed at elucidating the physical mechanism(s) involved.

Biographical memoir: Alexander Beaumont Hope, Australian biophysicist, 1928-2008.

This introductory article is the first of four short articles from the Tribute to Alex Hope Symposium held at the 2008 Australian Society for Biophysics meeting in Canberra, Australia, as a tribute to Professor Alex Hope, who died in July last year. As well as briefly introducing the other three articles by three former PhD students, it will also be a biographical memoir of Alex Hope.

Structural characterization of organic multilayers on silicon(111) formed by immobilization of molecular films on functionalized Si-C linked monolayers.

Silicon(111)-H surfaces were derivatized with omega-functionalized alkenes in UV-mediated and thermal hydrosilylation reactions to give Si-C linked monolayers. Additional molecular layers of organic compounds were coupled either directly or via linker molecules to the functionalized alkyl monolayers. In the first instance, amino-terminated monolayers were prepared from a tert-butoxycarbonyl-protected omega-aminoalkene followed by removal of the protecting group.

Electrical breakdown of human erythrocytes: a technique for the study of electro-haemolysis.

This paper describes a technique suitable for investigating the electromechanical breakdown properties of erythrocyte cells. The cells were exposed to square wave electric pulses of precise duration and voltage. The erythrocytes were suspended in normal isotonic saline between two opposing platinum electrodes.

Electric field effects in proteins in membranes.

Both the organization and function of protein nanostructures in membranes are related to the substructural properties of the lipid portion of the membrane. Potential differences that are established across the membrane and generate electric fields in these very thin portions are shown to modulate the organizational and functional properties of the protein modules. Many protein modules also have nonisotropic distributions of charged sites, including configurations in which there are regions containing predominantly positive fixed charges, juxtaposed with adjacent regions containing predominantly negative fixed charges.