Application of direct on-line coupling of HPLC and SFC with 1HNMR spectroscopy for the investigation of monomeric acrylates

The separation of monomeric acrylates was performed with High Performance Liquid Chromatography (HPLC) and Supercritical Fluid Chromatography (SFC). A direct on-line structural assignment of all compounds by continuous-flow ¹HNMR spectroscopy is possible with both separation techniques. The direct SFC-NMR coupling offers the advantage that the recorded continuous-flow ¹HNMR spectrum is not obscured by solvent signals.Dedicated to Professor Dr. H. Kriegsmann on the occasion of his 70th birthday     

Isospin breaking in $K \rightarrow \pi\pi$ decays

We perform a complete analysis of isospin breaking in amplitudes in chiral perturbation theory, including both strong isospin violation ( ) and electromagnetic corrections to next-to-leading order in the low-energy expansion. The unknown chiral couplings are estimated at leading order in the 1/N_c expansion. We study the impact of isospin breaking on CP conserving amplitudes and rescattering phases. In particular, we extract the effective couplings g₈ and g₂₇ from a fit to branching ratios, finding small deviations from the isospin-limit case. The ratio measuring the enhancement is found to decrease from in the isospin limit to in the presence of isospin breaking. We also analyze the effect of isospin violation on the CP violation parameter , finding a destructive interference between three different sources of isospin violation. Within the uncertainties of large-N_c estimates for the low-energy constants, the isospin violating correction for is below 15%.Received: 21 November 2003, Published online: 4 February 2004Work supported in part by IHP-RTN, Contract No. HPRN-CT2002-00311 (EURIDICE) and by Acciones Integradas, Project No. 19/2003 (Austria), HU2002-0044 (MCYT, Spain)     

Über Thiophosphonsäureanhydride

Zusammenfassung Durch Einleiten von Schwefelwasserstoff in Thiophosphonsäure-O-esterchloride (1) entstehen Thiophosphonsäureanhydride (2), die trimer sind und den Schwefel exocyclisch am Phosphor gebunden enthalten. Die 2 reagieren mit sek. Aminen zu Salzen der bisher unbekannten Thiophosphonsäuremonoamide, die durch Ansäuern in Freiheit gesetzt werden können.

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Thiophosphonic anhydrides

If hydrogen sulfide is passed into boiling O-alkyl-phosphonochloridothioates (1) trimer thiophosphonic anhydrides (2) are formed containing the sulfur outside the six-membered ring. The reaction of 2 with secondary amines gives salts of thiophosphonic monoamides that can be set free by acidification.

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Herrn Prof. Dr.H. Kratky freundschaftlich gewidmet.     

Single-pion production and the structure of the weak neutral current

We investigate the restrictions on the structure of the weak neutral current imposed by single pion production cross sections on single nucleons. A general vector (V), axial-vector (A) neutral current with |ΔI|?1 is assumed, where the isovector V,A neutral currents are the neutral members of the isotriplets containing the charged weak currents. From neutrino cross sections alone we derive bounds for the neutral current coupling constants. These bounds supplement the known constraints from inclusive scattering in a very useful way. More specific assumptions about the isoscalar neutral current are also considered. We discuss the resulting bounds using the existing neutrino data. Finally, it is shown that with the advent of antineutrino data for single pion production the neutral current coupling constants will be determined uniquely.     

Pion-pion phase shifts from covariant perturbation theory for a chiral invariant field theoretic model

The Lehmann model for pion -pion scattering consists of a low-energy expansion of the scattering amplitude to fourth order in the momenta on the basis of the chiral-invariant pion-nucleon Lagrangian. Because of the non-renormalizability of the pion Lagrangian two parameters remain undetermined in the pion-loop contribution. Using covariant perturbation theory and superpropagator methods, we calculate these two parameters independently of the choice of the pion field coordinates. The resulting phase shifts are shown to be in very good agreement with the data.     

Influence of nuclear deformation on the correlation of protons emitted from compound nuclei

The angular correlations of protons evaporated from the compound nucleus¹²⁴Ce exhibit strong anisotropies which are inconsistent with the emission from a spherical source. The data can be explained by an enhanced emission probability due to a lower Coulomb barrier perpendicular to the spin axis of strongly deformed nuclei.     

Intensive care unit occupancy predictions in the COVID-19 pandemic based on age-structured modelling and differential flatness

The COVID-19 pandemic confronts governments and their health systems with great challenges for disease management. In many countries, hospitalization and in particular ICU occupancy is the primary measure for policy makers to decide on possible non-pharmaceutical interventions. In this paper a combined methodology for the prediction of COVID-19 case numbers, case-specific hospitalization and ICU admission rates as well as hospital and ICU occupancies is proposed. To this end, we employ differential flatness to provide estimates of the states of an epidemiological compartmental model and estimates of the unknown exogenous inputs driving its nonlinear dynamics. A main advantage of this method is that it requires the reported infection cases as the only data source. As vaccination rates and case-specific ICU rates are both strongly age-dependent, specifically an age-structured compartmental model is proposed to estimate and predict the spread of the epidemic across different age groups. By utilizing these predictions, case-specific hospitalization and case-specific ICU rates are subsequently estimated using deconvolution techniques. In an analysis of various countries we demonstrate how the methodology is able to produce real-time state estimates and hospital/ICU occupancy predictions for several weeks thus providing a sound basis for policy makers.

     

Improved synthesis of the enantiomers of propafenone using chiral building blocks

Summary A short and efficient synthesis of the enantiomers of the antiarrhythmic drug propafenone (1) is described using both (R)-isopropylideneglycerol tosylate and (S)-glycidyl tosylate as chiral building blocks. The key step of the high yield synthesis is the acetalization of the carbonyl group in 1-(2-hydroxyphenyl)-3-phenyl-1-propanone (2) which allows application of mild reaction conditions in the subsequent alkylation of the phenolic hydroxy group.With our best wishes dedicated to Prof. Dr.H. Achenbach on the occasion of his 65^th birthday