Benzologs of allopurinol: Synthesis of pyrazolo [4,3-g] and [3,4-f] quinazolinones

Convenient syntheses of pyrazolo [4,3-g]quinazolin-5 (6H) -one (3), its xanthine oxidase metabolite 4 and the [3,4-f] analog 5 have been developed, involving anellation of the pyrimidine ring onto aminoindazolcarboxylic acids 9 and 18, or attachment of the pyrazol portion onto quinazolinone 22 via intramolecular azo coupling.     

The automated assay of SH-groups in the range below 50μmole/l

Summary The manual method of Stockhausen, using 6,6'-dithiodinicotinic acid as a specific reagent for SH-groups, has been modified to give an automated kinetic assay. Readings are performed with the LKB Reaction Rate Analyzer 8600 in a volume of 1–2 ml at a rate of 60 samples per hour. For reduced glutathione (as a standard), concentrations between 3 and 60mole/l can be measured with a mean relative standard deviation of 4.2%; the limit of detection is 1.5mole/l. Interferences are discussed.

---

Die automatische Bestimmung von SH-Gruppen in der Gröenordnung unter 50Mol/l

Zusammenfassung Die manuelle Methode von Stockhausen zur Bestimmung von SH-Gruppen mit 6,6'-Dithiodinicotinsäure wurde als Grundlage für ein automatischkinetisches Bestimmungsverfahren verwendet. Die Messung in einem Volumen von 1–2 ml erfolgt im LKB Reaction Rate Analyzer 8600 und mit einer Durchsatzgeschwindigkeit von 60 Proben je Stunde. Bei Verwendung von reduziertem Glutathion als Standard liegt der Meßbereich zwischen 3 und 60Mol/l mit einer durchschnittlichen relativen Standardabweichung von 4,2%; die Erfassungsgrenze liegt bei 1,5Mol/l. Die Störung der Methode durch verschiedene Verbindungen wird diskutiert.

---

---

Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Synchronization of organ pipes

The European Physical Journal B - We suggest that the broad distribution of time scales in financial markets could be a crucial ingredient to reproduce realistic price dynamics in stylised...     

Chimera states in networks of logistic maps with hierarchical connectivities

Chimera states are complex spatiotemporal patterns consisting of coexisting domains of coherence and incoherence. We study networks of nonlocally coupled logistic maps and analyze systematically how the dilution of the network links influences the appearance of chimera patterns. The network connectivities are constructed using an iterative Cantor algorithm to generate fractal (hierarchical) connectivities. Increasing the hierarchical level of iteration, we compare the resulting spatiotemporal patterns. We demonstrate that a high clustering coefficient and symmetry of the base pattern promotes chimera states, and asymmetric connectivities result in complex nested chimera patterns.     

Solitonic axion condensates modeling dark matter halos

Instead of fluid type dark matter (DM), axion-like scalar fields with a periodic self-interaction or some truncations of it are analyzed as a model of galaxy halos. It is probed if such cold Bose–Einstein type condensates could provide a viable soliton type interpretation of the DM ‘bullets’ observed by means of gravitational lensing in merging galaxy clusters. We study solitary waves for two self-interacting potentials in the relativistic Klein–Gordon equation, mainly in lower dimensions, and visualize the approximately shape-invariant collisions of two ‘lump’ type solitons.     

Phase Transfer Catalytic Preparation of the Dipolar Aprotic Solvents DMI and DMPU

The title compounds are prepared by methylation of the respective cyclic ureas using Me₂SO₄/catalyst/powdered NaOH (for DMI) or K₂CO₃ (for DMPU). Improved procedures are communicated for the preparation of 2-imidazolidine and trimethylene urea.     

A convenient route to alkynes via phase transfer catalysis: Applications of phase transfer catalysis,part 19

High yield, rapid formations of alkynes from vicdibromides are possible using powered potassium hydroxide and catalytic amounts of lipophilic phase transfer catalysts. Reasons are given why molar amounts of expensive catalysts were necessary in earlier procedures.