The puzzle of contrast inversion in DNA STM imaging.

DNA has been at the center of an imaging effort since the invention of the scanning tunneling microscope (STM). In some of the STM imaging reports the molecules appeared with negative contrast, i.e.

Contact dependence of carrier injection in carbon nanotubes: an ab initio study.

We combine ab initio density functional theory with transport calculations to provide a microscopic basis for distinguishing between good and poor metal contacts to nanotubes. Comparing Ti and Pd as examples of different contact metals, we trace back the observed superiority of Pd to the nature of the metal-nanotube hybridization. Based on large scale Landauer transport calculations, we suggest that the optimum metal-nanotube contact combines a weak hybridization with a large contact length between the metal and the nanotube.

Quantum transport through a DNA wire in a dissipative environment.

Electronic transport through DNA wires in the presence of a strong dissipative environment is investigated. We show that new bath-induced electronic states are formed within the band gap. These states show up in the linear conductance spectrum as a temperature dependent background and lead to a crossover from tunneling to thermal activated behavior with increasing temperature.

Filament depolymerization by motor molecules.

Motor proteins that specifically interact with the ends of cytoskeletal filaments can induce filament depolymerization. A phenomenological description of this process is presented. We show that under certain conditions motors dynamically accumulate at the filament ends.

Model evaluation for glycolytic oscillations in yeast biotransformations of xenobiotics.

Anaerobic glycolysis in yeast perturbed by the reduction of xenobiotic ketones is studied numerically in two models which possess the same topology but different levels of complexity. By comparing both models' predictions for concentrations and fluxes as well as steady or oscillatory temporal behavior we answer the question what phenomena require what kind of minimum model abstraction. While mean concentrations and fluxes are predicted in agreement by both models we observe different domains of oscillatory behavior in parameter space.

A three terminal ring interferometer logic gate.

We propose a carbon-based logic gate where and, or, and xor logic operations are available. It consists of a carbon nanotube (CNT) ring coupled to three external CNT-leads, two of them used as input channels, and the third as the output channel. The total transmission for two inputs displays characteristic interference effects.

Correlated tunneling in intramolecular carbon nanotube quantum dots.

We investigate correlated electronic transport in single-walled carbon nanotubes with two intramolecular tunneling barriers. We suggest that below a characteristic temperature the long-range nature of the Coulomb interaction becomes crucial to determine the temperature dependence of the maximum G(max) of the conductance peak. Correlated sequential tunneling dominates transport yielding the power law G(max) proportional, variant T(alpha(end-end)-1), typical for tunneling between the ends of two Luttinger liquids.

Molecular wire-nanotube interfacial effects on electron transport.

We discuss the conductance of a molecular bridge between mesoscopic electrodes supporting low-dimensional transport and bearing an internal structure. As an example for such nanoelectrodes we assume semi-infinite (carbon) nanotubes. In the Landauer scattering matrix approach, we show that the conductance of this hybrid is very sensitive to the geometry of the contact, unlike the usual behavior in the presence of bulk electrodes.