Pseudo differential operators with variable order of differentiation generating feller semigroups

supported by DFG-contract Ja 522/3-1     

Accentuated selective population transfer difference spectroscopy: a new method for revealing hidden NMR resonances.

Block difference FID accumulation with an initial selective decoupler pulse alternately placed at the high and low frequency lines of a multiples provides, upon transform, a difference spectrum that shows only those other multiplets that are scalar coupled to the probed resonance with full retention of all splittings for the multiplets so revealed.     

Determination of antigen—antibody affinity by immuno-capillary electrophoresis

The use of affinity capillary electrophoresis for the characterization of antigen—antibody interactions (immuno-capillary electrophoresis) is shown using monoclonal antibodies against phosphotyrosine as a model system. The influence of the interaction kinetics on the peak profiles was demonstrated in experiments with addition of phosphotyrosine to the electrophoresis buffer. One of the two antibodies that were tested exhibited peak broadening while the other showed no change in peak shape but had a decreased mobility proportional to the amount of phosphotyrosine present. The migration shifts which were of the order 0.05 to 0.15 min at 439 V/cm were a consequence of the antibody—antigen complexes having a slower mobility than the non-complexed antibody. On the basis of measurement of migration shifts at different antigen concentrations, dissociation constants were estimated and shown to be independent on the applied field strength. Thus, when certain requirements are fulfilled, immuno-capillary electrophoresis is a fast and simple method for establishing binding characteristics of unlabelled antigen and antibody molecules under non-denaturing conditions and consumes minute amounts of sample.     

On image pre-processing for PIV of single- and two-phase flows over reflecting objects

A novel image pre-processing scheme for PIV of single- and two-phase flows over reflecting objects which does not require the use of additional hardware is discussed. The approach for single-phase flow consists of image normalization and intensity stretching followed by background subtraction. For two-phase flow, an additional masking step is added after the background subtraction. The effectiveness of the pre-processing scheme is shown for two examples: PIV of single-phase flow in spacer-filled channels and two-phase flow in these channels. The pre-processing scheme increased the displacement peak detectability significantly and produced high quality vector fields, without the use of additional hardware.     

Solvated positron chemistry competitive positron reactions with halide ions in water

It is shown by means of the angular correlation technique that the binding of positrons to halides is strongly influenced by solvation effects. For aqueous solutions we find increasing values for the binding energies between the halide and the positron with increasing mass of the halide. This is contrary to the calculations of Cade and Farazdel for the vacuum case.     

Oligodeoxynucleotides containing alpha-L-ribo configured LNA-type C-aryl nucleotides

Synthesis of 2[prime or minute]-O,4[prime or minute]-C-methylene-[small alpha]-l-ribofuranosyl derivatives containing phenyl and 1-pyrenyl aglycons, i.e., novel [small alpha]-l-ribo configured LNA-type C-aryl nucleosides, has been accomplished. Key synthetic steps included stereoselective Grignard reactions on tetrahydrofuran aldehyde, configurational inversion of the resulting alcohol into alcohol, and concomitant Mitsonobu cyclization furnishing the desired bicyclic furanosyl skeleton with a locked conformation. The phosphoramidite derivatives and were used for automated synthesis of 9-mer DNA and [small alpha]-L-LNA oligonucleotides containing the [small alpha]-L-LNA-type C-aryl monomers ([small alpha]L)Ph(L) and ([small alpha]L)Py(L) containing a phenyl and pyrenyl aglycon, respectively. Thermal denaturation studies showed universal base pairing behavior for the pyrenyl monomer ([small alpha]L)Py(L) when incorporated into a DNA or an [small alpha]-L-LNA oligonucleotide.