arXiv subjects

E Alfinito

Publications and source records attributed to E Alfinito.

3 recordsLinked to original sources

arXiv2014

Investigations on the electrical current-voltage response in protein light receptors

We report a theoretical/computational approach for modeling the current-voltage characteristics of sensing proteins. The modeling is applied to a couple of transmembrane proteins, bacteriorhodopsin and proteorhodopsin, sensitive to visible light and promising biomaterials for the development of a new generation of photo-transducers. The agreement between theory and experiments sheds new light on the microscopic interpretation of charge transfer in proteins and biological materials in general.

physics.bio-ph↗

arXiv2013

Photoreceptors for a light biotransducer: a comparative study of the electrical responses of two (type-1)-opsins

The increasing interest in photoactivated proteins as natural replacement of standard inorganic materials in photocells drives to the compared analysis of bacteriorhodopsin and proteorhodopsin, two widely diffused proteins belonging to the family of \textit{type-1} opsins. These proteins share similar behaviours but exhibit relevant differences in the sequential chain of the amino acids constituting their tertiary structure. The use of an impedance network analogue to model the protein main features provides a microscopic interpretation of a set of experiments on their photoconductance properties. In particular, this model links the protein electrical responses to the tertiary structure and to the interactions among neighbouring amino acids. The same model is also used to predict the small-signal response in terms of the Nyquist plot. Interesting enough, these rhodopsins are found to behave like a wide gap semiconductor with intrinsic conductivities of the order of $10^{-7}$ S/cm.

physics.bio-ph↗

arXiv1999

Vacuum structure for expanding geometry

We consider gravitational wave modes in the FRW metrics in a de Sitter phase and show that the state space splits into many unitarily inequivalent representations of the canonical commutation relations. Non-unitary time evolution is described as a trajectory in the space of the representations. The generator of time evolution is related to the entropy operator. The thermodynamic arrow of time is shown to point in the same direction of the cosmological arrow of time. The vacuum is a two-mode SU(1,1) squeezed state of thermo field dynamics. The link between expanding geometry, squeezing and thermal properties is exhibited.

gr-qc↗