Free fermions and WZW theories on nonsimple groups

We consider conformally and Kac-Moody invariant theories based on the groupsG=G(N)×G(Ñ) whereG(N) is any of the classical groups. For the valuesk=Ñ, \(\tilde k = N\) of the Kac-Moody central charges, the monodromy problem involved in the computation of the four point function for primary fields in the defining representation ofG possesses two distinct solutions. As a consequence, the WZW theory onG (with an additionalU(1) factor ifG(N)=SU (N)) cannot be equivalent to a theory of free fermions.     

Stereoelectronic effects in negatively and positively (Protonated) charged species. Ab initio studies of the gauche effect in 1,4-dioxa systems

A computational study ab initio of the conformational dependence of proton affinities of 2-methoxyethoxide (MEO), dimethoxyethane (DME), and 1,4-dioxane has been carried out at the MP2/6-31+G level of theory. The results were discussed in comparison with reference systems, from simple alkoxides and ethers to anomeric moieties, in open, cyclic, and bicyclic molecules. The COCCOC species are stronger bases than the COCOC (anomeric) ones and approach regular ethers in their strength. The gauche forms in MEO and DME are altogether stronger bases than the anti forms, and anti (equatorial) protonation is preferred over gauche (axial), unless ditopic protonation is possible, like in aga-DME or cis-tetraoxadecalin. The gauche effect plays a significant role in the formation, relative stability, and reactivity of the charged species.     

Intramolecular electrophilic aromatic substitution reactions of 2-amidoacroleins: a new method for the preparation of tetrahydroisoquinolines, tetrahydro-3-benzazepines, and hexahydro-3-benzazocines

[reaction: see text]. A variety of heterocyclic ring systems can be prepared by subjecting N-aryl-substituted 5-amido-1,3-dioxins to Lewis acids. The reactions proceed via catalyzed retrocycloadditions to afford 2-amidoacroleins and concomitant regioselective electrophilic aromatic substitution reactions. The transformation is also successful using dioxins with amides that are within the incipient ring to afford the analogous lactams.     

6-Pyruvoyl tetrahydropterin synthase assay in extracts of cultured human cells using high-performance liquid chromatography with fluorescence detection of biopterin.

An assay for 6-pyruvoyl tetrahydropterin synthase, the second enzyme in the conversion of guanosine triphosphate into tetrahydrobiopterin, has been developed. Cell extracts were incubated with enzymatically prepared dihydroneopterin triphosphate (80 microM) in the presence of Mg2+ (12 mM), excess sepiapterin reductase (EC 1.1.1.153) (2 nmol/min) and NADPH (2 mM). 6-Pyruvoyl tetrahydropterin, the product of the reaction, was thus converted into tetrahydrobiopterin. After oxidation of the reduced biopterin derivatives in acidic iodine solution, biopterin was enriched and separated from the abundant neopterin phosphates by solid-phase extraction on a strong cation exchanger. Biopterin was then directly eluted on a reversed-phase liquid chromatographic column and detected fluorimetrically using excitation at 353 nm and emission at 438 nm. The biopterin concentrations formed by the coupled enzyme reaction increased linearly with incubation times up to 90 min. The assay allows the quantification of 6-pyruvoyl tetrahydropterin synthase in cultured human cells.     

Survey of experimental results on μCF including hyperfine effects

Complementary to the investigations of the most efficient dt cycle, also the other muon-induced fusion cycles in mixtures of hydrogen isotopes have been studied. The results of these dedicated experiments provide rich information about muon-induced few-body reactions and contribute significantly to a better overall understanding of CF. A summary of the recent progress will be presented. Special emphasis will be put on two characteristic examples, namely a new experimental approach to study the muonic cascade in H-D mixtures and the systematic study of hyperfine effects in muon-induced reactions.