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.

Mechanism and kinetics of the diffusion of gold in silicon

Abstract: The diffusion of Au in Si is known to take place via the interchange of Au atoms between substitutional (Au s ) and interstitial (Au i ) sites. So far it has generally been believed that this interchange involves lattice vacancies (V) and that it occurs via the Frank-Turnbull mechanism V+Au i ⇆Au s . It is stated in the literature that this model explains the observation that the Au s concentrationC s m in the centre of Au-diffused Si wafers increases with timet according to $$C_s^m \propto \sqrt t $$ . We show that this statement is incorrect, i.e., the Frank-Turnbull model cannot account for the $$C_s^m \propto \sqrt t $$ law. Such a dependence is expected in the case of Si wafers with a sufficiently low density of internal sinks for self-interstitials if the Au i −Au s interchange is controlled by the so-called kick-out mechanism Au i ⇆Au s +1. Since this mechanism involves self-interstitials (I) the present result is in accordance with the fact that under high-temperature equilibrium conditions the dominating intrinsic point defects in Si are self-interstitials and not vacancies as in Ge or metals.

Actions of imidacloprid and a related nitromethylene on cholinergic receptors of an identified insect motor neurone

Abstract: Nitromethylenes and their analogues are a novel class of insecticidally active molecules of commercial importance. Here we describe the actions of a novel nitroguanidine analogue, l-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine (imidacloprid; NTN 33893) and a nitromethylene, l-(3-pyridylmethyl)-2-nitromethylene-imidazolidine (PMNI) on the cockroach fast coxal depressor motor neurone Df and their effectiveness in displacing [125I]α-bungarotoxin binding to cockroach nerve cord preparations. When tested on the cell body of this identified neurone both imidacloprid and PMNI induce slow depolarizations, which are sensitive to nicotinic receptor antagonists, such as dihydro-β-erythroidine (1.0 × 10−5 M) and mecamylamine (1.0 × 10−4 M). Lower concentrations of imidacloprid (1.0 × 10−8 −1.0 × 10−6 M) and PMNI (1.0 × 10−8 M) show no antagonist action on nicotine-induced depolarization. At concentrations in the range 1.0 × 10−7 −5.0 × 10−7 M, PMNI partially and reversibly blocks nicotine-induced depolarization. Both compounds are more effective displacers of specific [125I]α-bungarotoxin binding than nicotine, with imidacloprid (IC50 = 2.0 × 10−7 M) about tenfold more potent than PMNI (IC50 = 1.3 × 10−6 M).

Thermodynamics of a colloidal particle in a time-dependent nonharmonic potential.

Abstract: We study the motion of an overdamped colloidal particle in a time-dependent nonharmonic potential. We demonstrate the first lawlike balance between applied work, exchanged heat, and internal energy on the level of a single trajectory. The observed distribution of applied work is distinctly non-Gaussian in good agreement with numerical calculations. Both the Jarzynski relation and a detailed fluctuation theorem are verified with good accuracy.

RNA interference: from basic research to therapeutic applications.

Abstract: An efficient mechanism for the sequence-specific inhibition of gene expression is RNA interference. In this process, double-stranded RNA molecules induce cleavage of a selected target RNA (see picture). This technique has in recent years developed into a standard method of molecular biology. Successful applications in animal models have already led to the initiation of RNAi-based clinical trials as a new therapeutic option.Only ten years ago Andrew Fire and Craig Mello were able to show that double-stranded RNA molecules could inhibit the expression of homologous genes in eukaryotes. This process, termed RNA interference, has developed into a standard method of molecular biology. This Review provides an overview of the molecular processes involved, with a particular focus on the posttranscriptional inhibition of gene expression in mammalian cells, the possible applications in research, and the results of the first clinical studies.