Some Isoperimetric Inequalities in Electrochemistry and Hele Shaw Flows

Isoperimetric inequalities are applied to a moving-boundaryproblem for doubly-connected domains. This problem occurs forexample in electrochemistry, in which case the domains in questionare the electrolyte of an electrolytic cell. The two electrodessurrounding the electrolyte are assumed to grow or dissolve,at different rates in general, by electrochemical reaction.We obtain optimal estimates showing, for example, that the leastchange in volume of each electrode always occurs in sphericalsymmetry.     

ELECTRON TRANSPORT IN RHODOPSEUDOMONAS VIRIDIS* AT LOW TEMPERATURES

Abstract— When chromatophores of Rhodopseudomonas viridis are briefly illuminated with very bright light at temperatures between —20°C and —196°C, reaction center chlorophyll (P985) is oxidized rapidly and becomes reduced in less than 0.1 sec upon cessation of illumination. In moderate exciting light one molecule of cytochrome 558 per molecule of P985 is oxidized rapidly and irreversibly while P985 oxidation is much slower and its oxidation rate is highly temperature-dependent. After a long illumination ends, P985 reduction occurs in two temperature-dependent phases, in 1 to 1 ratio. The data are interpreted as follows.

• 1 P985 and one mole of cytochrome 588 per mole of P985 can be photooxidized at low temperatures.
• 2 Electron transfer from the primary electron acceptor to the secondary acceptor or back to P985⁺ occurs in less than 0.1 sec at low temperatures.
• 3 There is one mole of secondary acceptor (a one-electron acceptor) per mole of P985. and electron transfer from the secondary acceptor to tertiary acceptors is highly temperature-dependent.

     

Phase equilibria of confined liquid crystals

The differences between the phase diagram of the Gay-Berne potential confined by two identical walls versus the corresponding bulk phase diagram have been investigated. A wall-fluid interaction 9-3 Lennard-Jones potential was used. The study was performed in most cases by using the hybrid Monte Carlo method for the μVT ensemble. Several isotherms were analysed where vapour, liquid and smectic phases were observed. The smectic-isotropic coexistence region becomes wider, i.e. the isotropic coexistence line is shifted to lower densities but the smectic coexistence line remains nearly the same. The triple point temperature of the confined system is estimated to be in the vicinity of 0.45 versus 0.40 of the bulk system. For the isotherm at T? = 0.65 an orientational dependence was added to the 9-3 Lennard-Jones potential to model the wall-fluid interaction. For both kinds of walls, 9-3 LJ with and without orientational dependence, confinement was not found to stabilize a nematic phase as found by previous authors.