Eine neue Schnellmethode zur makro- und mikrochemischen Bestimmung des Wismuts

Ohne Zusammenfassung     

Structural characterization of the ligstroside aglycone isoforms in virgin olive oils by liquid chromatography–high‐resolution Fourier‐transform mass spectrometry and H/Dexchange

A systematic structural characterization of the isomeric forms related to ligstroside aglycone (LA), one of the most relevant secoiridoids contained in virgin olive oils, was performed using reverse phase liquid chromatography with electrospray ionization Fourier‐transform single and tandem mass spectrometry, operated in negative ion mode (RPLC‐ESI(?)‐FTMS and FTMS/MS). The high mass resolution and accuracy provided by the adopted orbital trap mass analyzer enabled the recognition of more than 10 different isomeric forms of LA in virgin olive oil extracts. They were related to four different types of molecular structure, two of which including a dihydropyranic ring bearing one or two aldehydic groups, whereas the others corresponded to dialdehydic open‐structure forms, differing just for the position of a C═C bond. The contemporary presence of enolic or dienolic tautomers associated to most of these compounds, stable at room temperature (23°C), was also assessed through RPLC‐ESI‐FTMS analyses operated under H/D exchange conditions, ie, by using D₂O instead of H₂O as co‐solvent of acetonitrile in the RPLC mobile phase. As discussed in the paper, the results obtained for LA indicated a remarkable structural similarity with oleuropein aglycone (OA), the most abundant secoiridoid of olive oil, whose isoforms had been previously characterized using the same analytical approach.     

Combinatorial covers and vanishing of cohomology

We use a Mayer–Vietoris-like spectral sequence to establish vanishing results for the cohomology of complements of linear and elliptic hyperplane arrangements, as part of a more general framework involving duality and abelian duality properties of spaces and groups. In the process, we consider cohomology of local systems with a general, Cohen–Macaulay-type condition. As a result, we recover known vanishing theorems for rank-1 local systems as well as group ring coefficients and obtain new generalizations.     

Analysis of Charge-Transfer Complex Absorption Spectra and the Applicability of the Mulliken two-State Model

Complete absorption spectra, free from interference due to an unbound acceptor and donor, of several charge-transfer complexes have been examined. These spectra serve as a significant test to the applicability of the Mulliken two-state model for this series of complexes. the appearance of multiple new absorption bands and the trend in the observed oscillator strength of the CT transitions and the localized excitation within the complex spectrum require significant expansions of Mulliken's simple two-state model. Multiple new CT absorption bands are frequently encountered and their appearance has been explained in terms of multiple ion-pair states participating in CT interactions. the relative positions of these bands are predicted based on the gas-phase ionization potentials of the donors and the electron affinity of the acceptor in excellent agreement with the observed spectra achieved. the integrated absorption intensities of the localized bands within each CT complex spectrum have been measured and used as an indicator of the extent on intensity borrowing by the CT transition. These measurements show that for the better donors used in this study, i.e. hexamethylbenzene and pentamethylbenzene, intensity borrowing is not significant. However, for the poorer donors used, an increasing contribution of the LE within the CT absorption bands is observed. a multi-state model, which includes the localized excited state of the acceptors well as additional ion-pair states, is the minimum required to describe these complexes.     

Fast Biosynthesis of GFP Molecules: A Single‐Molecule Fluorescence Study

It's not easy being green : Real‐time visualization of labeled ribosomes and de novo synthesized green fluorescent protein molecules using single‐molecule‐sensitive fluorescence microscopy demonstrates that the mutant GFPem is produced with a characteristic time of five minutes. Fluorescence of the fastest GFP molecules appears within one minute (see picture).

     

Rapid chemiluminescence biosensing of microcystin-LR

A rapid immunoassay for sensitive detection of microcystin-LR using a portable chemiluminescence multichannel immunosensor (CL-MADAG) was developed. The sensor device is based on a capillary ELISA technique in combination with a miniaturized fluidics system and uses chemiluminescence as the detection principle. Minimum concentrations of at least 0.2 μg L⁻¹ microcystin-LR could be unambiguously measured in a spiked buffer system as well as in spiked real water samples. A single sample analysis for detection of microcystin-LR could be accomplished in just 13 min on the CL-MADAG. Besides providing a highly reproducible, fast and easy to perform test format, one major advantage of the newly established capillary immunoassay is represented by the feasibility of an internal retrospective quality control mechanism. Finally, simultaneous CL-MADAG measurements employing our inhibition immunoassay and a sandwich ELISA could be successfully demonstrated.     

Maximum A-isometric part of an A-contraction and applications

For two bounded linear operators A and T on a complex Hilbert space H (A being positive) which satisfy the inequality T*AT ≤ A, we study the maximum subspace ℳ₀ which reduces A and T, on which the equality T*AT = A holds. We show that in some cases involving the condition AT = A ^1/2 TA ^1/2, ℳ₀ can be expressed in terms of the minimal isometric dilation of the contraction $ \hat T $ \hat T on $ \overline {R(A)} $ \overline {R(A)} associated to T by the condition $ \hat T $ \hat T A ^1/2 = A ^1/2 T. As application we find a concrete representation for ℳ₀ when T is a contraction with S _T = S _T ², where S _T is the strong limit of the sequence [T ^*n T ⁿ : n ≥ 1]. Also, we derive some applications for hyponormal contractions and quasi-isometries.     

Toric complexes and Artin kernels

A simplicial complex L on n vertices determines a subcomplex TL of the n-torus, with fundamental group the right-angled Artin group GL. Given an epimorphism χ:GL→Z, let be the corresponding cover, with fundamental group the Artin kernel Nχ. We compute the cohomology jumping loci of the toric complex TL, as well as the homology groups of with coefficients in a field k, viewed as modules over the group algebra kZ. We give combinatorial conditions for to have trivial Z-action, allowing us to compute the truncated cohomology ring, . We also determine several Lie algebras associated to Artin kernels, under certain triviality assumptions on the monodromy Z-action, and establish the 1-formality of these (not necessarily finitely presentable) groups.     

Structure preserving simulation of muscle actuated movements

Biomechanical simulation of human locomotion is commonly done via dynamical simulations of multibody systems. The actuation of the system is thereby often represented via muscle models that create a force depending on muscle length and activation level. We show a comparison of such a simulation using a structure preserving integration framework to MATLAB/Simulink results. The conclusion is that structure preservation is important to represent such systems correctly, in particular concerning energy and angular momentum evolutions. We introduce a method for structure preserving simulation of muscle actuated movements. Additionally we show examples of a simple arm movement including only one muscle as well as a finger movement including up to six muscles as an example for more complex biomechanical systems. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)