Technical University of Dortmund

About: Technical University of Dortmund is a education organization based out in Dortmund, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Large Hadron Collider & Neutrino. The organization has 13028 authors who have published 27666 publications receiving 615557 citations. The organization is also known as: Dortmund University & University of Dortmund.

Structure formation principles and reactivity of organolithium compounds.

Abstract: Organolithium chemistry! An overview of the structure formation principles and the strong structure–reactivity relationship of lithium organics is given. By means of the commonly used lithium bases the deaggregation of the oligomeric parent structures to small adducts is presented (see examples) and compared to the related chemistry of lithiosilanes. The structure–reactivity relationship is an important feature of organolithium compounds. The knowledge of the structure of reactive species is crucial for the elucidation of reaction mechanisms and the understanding of observed selectivities. This concept article gives an overview over the structural principles of lithium organics and their Lewis base coordinated complexes in the solid state. The transition from the oligomeric parent structures to smaller adducts, such as dimers and monomers, as well as special degrees of aggregation is presented. Besides the commonly used alkyllithium compounds, a short overview over the structural principles of the higher homologous silyllithium compounds is given. Moreover, the structure–reactivity relationship is depicted by means of the reactivity of the Lewis bases towards intramolecular decomposition reactions with the organolithium compound. Selected examples confirm the importance of structure elucidation for the understanding of mechanistic pathways and selectivities.

Runtime Analysis of the ( μ +1) EA on Simple Pseudo-Boolean Functions

Abstract: Although Evolutionary Algorithms (EAs) have been successfully applied to optimization in discrete search spaces, theoretical developments remain weak, in particular for population-based EAs. This paper presents a first rigorous analysis of the (μ+1) EA on pseudo-Boolean functions. Using three well-known example functions from the analysis of the (1+1) EA, we derive bounds on the expected runtime and success probability. For two of these functions, upper and lower bounds on the expected runtime are tight, and on all three functions, the (μ+1) EA is never more efficient than the (1+1) EA. Moreover, all lower bounds grow with μ. On a more complicated function, however, a small increase of μ provably decreases the expected runtime drastically.This paper develops a new proof technique that bounds the runtime of the (μ+1) EA. It investigates the stochastic process for creating family trees of individuals; the depth of these trees is bounded. Thereby, the progress of the population towards the optimum is captured. This new technique is general enough to be applied to other population-based EAs.

Dynamical next-to-next-to-leading order parton distributions

Abstract: Utilizing recent deep inelastic scattering measurements $({\ensuremath{\sigma}}_{r},{F}_{2,3,L})$ and data on hadronic dilepton production we determine at next-to-next-to-leading order (NNLO) (3-loop) of QCD the dynamical parton distributions of the nucleon generated radiatively from valencelike positive input distributions at an optimally chosen low resolution scale (${Q}_{0}^{2}l1\text{ }\text{ }{\mathrm{GeV}}^{2}$). These are compared with ``standard'' NNLO distributions generated from positive input distributions at some fixed and higher resolution scale (${Q}_{0}^{2}g1\text{ }\text{ }{\mathrm{GeV}}^{2}$). Although the NNLO corrections imply in both approaches an improved value of ${\ensuremath{\chi}}^{2}$, typically ${\ensuremath{\chi}}_{\mathrm{NNLO}}^{2}\ensuremath{\simeq}0.9{\ensuremath{\chi}}_{\mathrm{NLO}}^{2}$, present deep inelastic scattering data are still not sufficiently accurate to distinguish between NLO results and the minute NNLO effects of a few percent, despite the fact that the dynamical NNLO uncertainties are somewhat smaller than the NLO ones and both are, as expected, smaller than those of their standard counterparts. The dynamical predictions for ${F}_{L}(x,{Q}^{2})$ become perturbatively stable already at ${Q}^{2}=2--3\text{ }\text{ }{\mathrm{GeV}}^{2}$ where precision measurements could even delineate NNLO effects in the very small-$x$ region. This is in contrast to the common standard approach but NNLO/NLO differences are here less distinguishable due to the larger $1\ensuremath{\sigma}$ uncertainty bands. Within the dynamical approach we obtain ${\ensuremath{\alpha}}_{s}({M}_{Z}^{2})=0.1124\ifmmode\pm\else\textpm\fi{}0.0020$, whereas the somewhat less constrained standard fit gives ${\ensuremath{\alpha}}_{s}({M}_{Z}^{2})=0.1158\ifmmode\pm\else\textpm\fi{}0.0035$.

Nature of the Non-exponential Primary Relaxation in Structural Glass-formers Probed by Dynamically Selective Experiments

Abstract: Several experimental methods feature the potential to distinguish between slow and fast contributions to the non-exponential, ensemble averaged primary response in glass-forming materials. Some of these techniques are based on the selection of subensembles using multi-dimensional nuclear magnetic resonance, optical bleaching, and non-resonant spectral hole burning. Others, such as the time-dependent solvation spectroscopy, measure microscopic responses induced by local perturbations. Using several of these methods it could be demonstrated for various glass-forming materials that the non-exponential relaxation results from a superposition of dynamically distinguishable entities. The experimental observation that subensembles can be selected efficiently indicates a large degree of heterogeneity. The intrinsic response is compatible with single exponential relaxation.

Growth independent rhamnolipid production from glucose using the non-pathogenic Pseudomonas putida KT2440

Abstract: Rhamnolipids are potent biosurfactants with high potential for industrial applications. However, rhamnolipids are currently produced with the opportunistic pathogen Pseudomonas aeruginosa during growth on hydrophobic substrates such as plant oils. The heterologous production of rhamnolipids entails two essential advantages: Disconnecting the rhamnolipid biosynthesis from the complex quorum sensing regulation and the opportunity of avoiding pathogenic production strains, in particular P. aeruginosa. In addition, separation of rhamnolipids from fatty acids is difficult and hence costly. Here, the metabolic engineering of a rhamnolipid producing Pseudomonas putida KT2440, a strain certified as safety strain using glucose as carbon source to avoid cumbersome product purification, is reported. Notably, P. putida KT2440 features almost no changes in growth rate and lag-phase in the presence of high concentrations of rhamnolipids (> 90 g/L) in contrast to the industrially important bacteria Bacillus subtilis, Corynebacterium glutamicum, and Escherichia coli. P. putida KT2440 expressing the rhlAB-genes from P. aeruginosa PAO1 produces mono-rhamnolipids of P. aeruginosa PAO1 type (mainly C10:C10). The metabolic network was optimized in silico for rhamnolipid synthesis from glucose. In addition, a first genetic optimization, the removal of polyhydroxyalkanoate formation as competing pathway, was implemented. The final strain had production rates in the range of P. aeruginosa PAO1 at yields of about 0.15 g/gglucose corresponding to 32% of the theoretical optimum. What's more, rhamnolipid production was independent from biomass formation, a trait that can be exploited for high rhamnolipid production without high biomass formation. A functional alternative to the pathogenic rhamnolipid producer P. aeruginosa was constructed and characterized. P. putida KT24C1 pVLT31_rhlAB featured the highest yield and titer reported from heterologous rhamnolipid producers with glucose as carbon source. Notably, rhamnolipid production was uncoupled from biomass formation, which allows optimal distribution of resources towards rhamnolipid synthesis. The results are discussed in the context of rational strain engineering by using the concepts of synthetic biology like chassis cells and orthogonality, thereby avoiding the complex regulatory programs of rhamnolipid production existing in the natural producer P. aeruginosa.