Einfacher Beweis einer charakteristischen EigenschaftRiemann-integrierbarer Funktionen

Ohne Zusammenfassung     

Totally unimodular stochastic programs

We consider totally unimodular (TU) stochastic programs, that is, two-stage stochastic programs whose extensive-form constraint matrix is TU. We generalize the notion of total unimodularity to apply to sets of matrices and provide properties of such sets. We provide several sufficient conditions on stochastic programs to be TU. When solving TU stochastic problems using the L-shaped method, it is not clear whether the integrality restrictions should be imposed on the master problem. Such restrictions will make each master problem more difficult to solve. On the other hand, solving the linear relaxation of the master typically means sending fractional (and unlikely optimal) solutions to the subproblems, perhaps leading to more iterations. Our computational results investigate this trade-off and provide insight into which strategy is preferable.     

Renormalization group approach towards the QCD phase diagram

The idea of the functional renormalization group and one-loop improved renormalization group flows are reviewed. The associated flow equations and nonperturbative approximations schemes for its solutions are discussed. These techniques are then applied to the strong interaction in the framework of an effective quark meson model, which is introduced in great detail. The renormalization group analysis of the two flavor quark meson model is extended to finite temperature and quark chemical potential which allows for an analysis of the chiral phase diagram beyond the mean field approximation. The text was submitted by the authors in English.     

Late‐Stage Functionalization of Peptides and Cyclopeptides Using Organozinc Reagents

We report a new late‐stage functionalization of small peptides and cyclopeptides relying on the Negishi cross‐coupling of readily prepared iodotyrosine‐ or iodophenylalanine‐containing peptides with aryl‐, heteroaryl‐, and alkylzinc pivalates or halides. In silico and in vitro determinations of membrane permeability parameters of the modified cyclopeptides showed that in most cases, the solubility was improved by the introduction of polar pyridyl units while the cell‐membrane permeability was maintained.     

Melting and freezing of argon in a granular packing of linear mesopore arrays

Freezing and melting of Ar condensed in a granular packing of template-grown arrays of linear mesopores (SBA-15, mean pore diameter 8 nm) has been studied by specific heat measurements C as a function of fractional filling of the pores. While interfacial melting leads to a single melting peak in C, homogeneous and heterogeneous freezing along with a delayering transition for partial fillings of the pores result in a complex freezing mechanism explainable only by a consideration of regular adsorption sites (in the cylindrical mesopores) and irregular adsorption sites (in niches of the rough external surfaces of the grains and at points of mutual contact of the powder grains). The tensile pressure release upon reaching bulk-liquid-vapor coexistence quantitatively accounts for an upward shift of the melting and freezing temperature observed while overfilling the mesopores.     

Is PdII‐Promoted σ‐Bond Metathesis Mechanism Operative for the PdPEPPSI Complex‐Catalyzed Amination of Chlorobenzene with Aniline? Experiment and Theory

Reduction of the Pd?PEPPSI precatalyst to a Pd⁰ species is generally thought to be essential to drive Buchwald–Hartwig amination reactions through the well‐ documented Pd⁰/Pd^II catalytic cycle and little attention has been paid to other possible mechanisms. Considered here is the Pd?PEPPSI‐catalyzed aryl amination of chlorobenzene with aniline. A neat reaction system was used in new experiments, from which the potentially reductive roles of the solvent and labile ligand of the PEPPSI complex in leading to Pd⁰ species are ruled out. Computational results demonstrate that anilido‐containing Pd^II intermediates involving σ‐bond metathesis in pathways leading to the diphenylamine product have relatively low barriers. Such pathways are more favorable energetically than the corresponding reductive elimination reactions resulting in Pd⁰ species and other putative routes, such as the Pd^II/Pd^IV mechanism, single electron transfer mechanism, and halide atom transfer mechanism. In some special cases, if reactants/additives are inadequate to reduce a Pd^II precatalyst, a Pd^II‐involved σ‐bond metathesis mechanism might be feasible to drive the Buchwald–Hartwig amination reactions.