Breit interaction effects on the Kα angular distribution following the dielectronic recombination of high-Z ions

The angular distribution of the Kα hypersatellite radiation has been investigated for high-Z, helium-like ions following the K − LL dielectronic recombination of initially hydrogen-like projectiles in relativistic ion-atom collisions. A particular strong effect is found for the alignment of the 2s2p_1/2J = 1 (spin-forbidden) resonance that changes sign if, in addition to the static Coulomb repulsion, the Breit interaction is taken into account for the resonant electron capture. This change in the alignment of the recombined ion also leads to a remarkable shift in the angular distribution of the subsequent 2s2p_1/2J = 1 → 1s2s J = 0 Kα₂ photons from a dominantly perpendicular emission to one that occurs in parallel with the ion beam, and vice versa for the 2s2p_1/2J = 1 → 1s2s J = 1 line.     

Conformational Heterogeneity and Cooperative Effects of Mammalian ALOX15

Arachidonic acid lipoxygenases (ALOXs) have been suggested to function as monomeric enzymes, but more recent data on rabbit ALOX15 indicated that there is a dynamic monomer-dimer equilibrium in aqueous solution. In the presence of an active site ligand (the ALOX15 inhibitor RS7) rabbit ALOX15 was crystalized as heterodimer and the X-ray coordinates of the two monomers within the dimer exhibit subtle structural differences. Using native polyacrylamide electrophoresis, we here observed that highly purified and predominantly monomeric rabbit ALOX15 and human ALOX15B are present in two conformers with distinct electrophoretic mobilities. In silico docking studies, molecular dynamics simulations, site directed mutagenesis experiments and kinetic measurements suggested that in aqueous solutions the two enzymes exhibit motional flexibility, which may impact the enzymatic properties.     

A study of 25 years of publication outputs in the German academic profession

Scientometrics - In the weak evaluation state of Germany, full professors are involved in the traditional social governance partnership between the state, and the self-governing higher education...     

A Column By‐Pass System and Its Application in High‐Temperature Size‐Exclusion Chromatography

Summary: A new by‐pass system for chromatographic columns is presented and its efficiency in detecting disturbances during the chromatographic run is demonstrated. The system, designed for HT SEC, is based on a ten‐port valve and allows by‐passing without the need of time and work consuming replacement of the column by a capillary and vice versa. In addition, the construction guarantees a continuous low flow of eluent through the column also when by‐passed, which helps substantially to prolong lifetime of the SEC column at high temperature. Combining the chromatograph with “absolute” detectors, e.g. a light‐scattering detector or viscometer, erroneous molecular parameters caused by polymer degradation due to wrong column selection or run conditions can be easily detected by comparing measurements with and without the column. Therefore, using the chromatograph in by‐pass mode, it can be regarded as an additional, independent apparatus, delivering e.g. the or [η] of a polymer sample. The by‐pass system enables a reliable calibration of concentration detectors in chromatography. With the aid of a detector calibration curve, even a small amount of polymer adsorbed in the SEC column can be detected by comparing the peak area derived from the concentration detector to the one to be expected from the calibration data. The column by‐pass could find application except for HT SEC also in other fields of HPLC.

Scheme of the by‐pass system.     

Species determination – Can we detect and quantify meat adulteration?

Proper labelling of meat products is important to help fair-trade, and to enable consumers to make informed choices. However, it has been shown that labelling of species, expressed as weight/weight (w/w), on meat product labels was incorrect in more than 20% of cases. Enforcement of labelling regulations requires reliable analytical methods. Analytical methods are often based on protein or DNA measurements, which are not directly comparable to labelled meat expressed as w/w. This review discusses a wide range of analytical methods with focus on their ability to quantify and their limits of detection (LOD). In particular, problems associated with a correlation from quantitative DNA based results to meat content (w/w) are discussed. The hope is to make researchers aware of the problems of expressing DNA results as meat content (w/w) in order to find better alternatives. One alternative is to express DNA results as genome/genome equivalents.     

Heteroatom nucleophile induced C-C fragmentations to access functionalized allenes

The rich structural and reactivity profile of allenes render them versatile synthetic intermediates. However, application of allenes in organic chemistry is often attenuated by inconvenient methods of preparation. Herein we present an operationally simple route to functionalized allenes from vinyl triflate precursors through a Grob-type fragmentation induced by heteroatom nucleophiles such as water, alcohols, thiols or amines. The fragmentation occurs under mild conditions and is well suited for one-pot or domino processes allowing access to a range of synthetically useful intermediates.     

Electrical and optical properties of InP nanowire ensemble p⁺-i-n⁺ photodetectors

We report on a comprehensive study of electrical and optical properties of efficient near-infrared p?-i-n? photodetectors based on large ensembles of self-assembled, vertically aligned i-n? InP nanowires monolithically grown on a common p? InP substrate without any buffer layer. The nanowires have a polytype modulated crystal structure of wurtzite and zinc blende. The electrical data display excellent rectifying behavior with an ideality factor of about 2.5 at 300 K. The ideality factor scales with 1/T, which possibly reflects deviations from classical transport models due to the mixed crystal phase of the nanowires. The observed dark leakage current is of the order of merely ～100 fA/nanowire at 1 V reverse bias. The detectors display a linear increase of the photocurrent with reverse bias up to about 10 pA/nanowire at 5 V. From spectrally resolved measurements, we conclude that the photocurrent is primarily generated by funneling photogenerated carriers from the substrate into the NWs. Contributions from direct excitation of the NWs become increasingly important at low temperatures. The photocurrent decreases with temperature with an activation energy of about 50 meV, which we discuss in terms of a temperature-dependent diffusion length in the substrate and perturbed transport through the mixed-phase nanowires.     

Adaptive pseudo dilation for gestalt edge grouping and contour detection

We consider the problem of detecting object contours in natural images. In many cases, local luminance changes turn out to be stronger in textured areas than on object contours. Therefore, local edge features, which only look at a small neighborhood of each pixel, cannot be reliable indicators of the presence of a contour, and some global analysis is needed. We introduce a new morphological operator, called adaptive pseudo-dilation (APD), which uses context dependent structuring elements in order to identify long curvilinear structure in the edge map. We show that grouping edge pixels as the connected components of the output of APD results in a good agreement with the gestalt law of good continuation. The novelty of this operator is that dilation is limited to the Voronoi cell of each edge pixel. An efficient implementation of APD is presented. The grouping algorithm is then embedded in a multithreshold contour detector. At each threshold level, small groups of edges are removed, and contours are completed by means of a generalized reconstruction from markers. The use of different thresholds makes the algorithm much less sensitive to the values of the input parameters. Both qualitative and quantitative comparison with existing approaches prove the superiority of the proposed contour detector in terms of larger amount of suppressed texture and more effective detection of low-contrast contours.     

Planungsansatz für modulare Anlagen in der chemischen Industrie

Modularly built production plants are considered for planning new chemical plants, in case they shall be designed quickly and transformable, flexible plants are required. To date, these plants are planned mostly by the conventional planning process, so that time saving is not achieved. This paper presents a module based planning approach, which allows a structured planning of new modular plants in a time‐efficient way. All required documents for building modules are stored in the Process Equipment Design documentation, which is available for re‐use in future projects.