University of Stuttgart

About: University of Stuttgart is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Laser & Finite element method. The organization has 27715 authors who have published 56370 publications receiving 1363382 citations. The organization is also known as: Universität Stuttgart.

Reduction of azo dyes by redox mediators originating in the naphthalenesulfonic acid degradation pathway of Sphingomonas sp. strain BN6.

Abstract: The anaerobic reduction of azo dyes by Sphingomonas sp. strain BN6 was analyzed. Aerobic conversion of 2-naphthalenesulfonate (2NS) by cells of strain BN6 stimulated the subsequent anaerobic reduction of the sulfonated azo dye amaranth at least 10-fold. In contrast, in crude extracts, the azo reductase activity was not stimulated. A mutant of strain BN6 which was not able to metabolize 2NS showed increased amaranth reduction rates only when the cells were resuspended in the culture supernatant of 2NS-grown BN6 wild-type cells. The same increase could be observed with different bacterial strains. This suggested the presence of an extracellular factor which was formed during the degradation of 2NS by strain BN6. The addition of 1,2-dihydroxynaphthalene, the first intermediate of the degradation pathway of 2NS, or its decomposition products to cell suspensions of the mutant of strain BN6 (2NS-) increased the activity of amaranth reduction. The presence of bacterial cells was needed to maintain the reduction process. Thus, the decomposition products of 1,2-dihydroxynaphthalene are suggested to act as redox mediators which are able to anaerobically shuttle reduction equivalents from the cells to the extracellular azo dye.

Local Permutations in the Glomerular Array of the Mouse Olfactory Bulb

Abstract: Olfactory sensory neurons expressing a given odorant receptor gene project their axons with great precision to a few specific glomeruli in the olfactory bulb. It is not clear to which extent the positions of these glomeruli are fixed. We sought to evaluate the constancy of the glomerular array in the mouse by determining the relative positions of glomeruli for various odorant receptors, using a method that affords single-axon resolution, and in a large number of bulbs. We used a genetic strategy to visualize neuronal populations that express one of three members of the mOR37 subfamily. We generated by gene targeting five strains of mice in which expression of a given mOR37 gene is linked to expression of an axonal maker, which is either taulacZ or tauGFP. The patterns of marker expression faithfully mimic those of the cognate receptors. Axons of neurons expressing a given mOR37 gene converge onto one or two glomeruli per bulb. Each mOR37 gene has its own glomeruli, and the mOR37 glomeruli are grouped within a restricted domain of the bulb. Serial sectioning of 214 bulbs reveals that the relative positions of the three types of glomeruli are not fixed but display local permutations. Importantly, this is also the case among the two bulbs from one individual, ruling out the genetic manipulation itself and differences in genetic background or olfactory experience as causes for the observed variability. These local permutations may reflect the developmental history of the glomeruli and are relevant for the construction of spatial odor maps.

Charge state manipulation of qubits in diamond

Abstract: The nitrogen-vacancy (NV) centre in diamond is a promising candidate for a solid-state qubit. However, its charge state is known to be unstable, discharging from the qubit state NV− into the neutral state NV0 under various circumstances. Here we demonstrate that the charge state can be controlled by an electrolytic gate electrode. This way, single centres can be switched from an unknown non-fluorescent state into the neutral charge state NV0, and the population of an ensemble of centres can be shifted from NV0 to NV−. Numerical simulations confirm the manipulation of the charge state to be induced by the gate-controlled shift of the Fermi level at the diamond surface. This result opens the way to a dynamic control of transitions between charge states and to explore hitherto inaccessible states, such as NV+. Point defects in diamond in the form of nitrogen vacancy centres are believed to be promising candidates for qubits in quantum computers. Grotzet al. present a method for manipulating the charge state of nitrogen vacancies using an electrolytic gate electrode.

Wetting Phenomena in Nanofluidics

Abstract: We focus on the dynamical aspects of wetting phenomena on the nanoscale for which bulk hydrodynamic equations become invalid. At the nanoscale, phenomena that are irrelevant on the micrometer scale and larger, or that can be summarily incorporated in terms of boundary conditions, become important. Among these features are long-ranged molecular interactions such as dispersion forces, thermal fluctuations, hydrodynamic slip, segregation of mixtures and solutions at walls, and electrical double layers.