Cyclodextrin knowledgebase a web-based service managing CD-ligand complexation data

Cyclodextrins are cyclic oligosaccharides that are able to form water-soluble inclusion complexes with small molecules. Because of their complexing ability, they are widely applied in food, pharmaceutical and chemical industries. In this paper we describe the development of a free web-service, Cyclodextrin KnowledgeBase: (http://www.cyclodextrin.net). The database contains four modules: the Publication, Interaction, Chirality and Analysis Modules. In the Publication Module, almost 50,000 publication details are collected that can be retrieved by text search. In the Interaction and Chirality Modules relevant literature data on cyclodextrin complexation and chiral recognition are collected that can be retrieved by both text and structural searches. Moreover, in the Analysis Module, the geometries of small molecule-cyclodextrin complexes can be predicted using molecular docking tools in order to explore the structures and interaction energies of the inclusion complexes. Complex geometry prediction is made possible by the built-in database of 95 cyclodextrin derivatives, where the 3D structures as well as the partial charges are calculated and stored for further utilization. The use of the database is demonstrated by several examples.     

Radical-polar crossover domino reactions involving organozinc and mixed organocopper/organozinc reagents

A domino process involving Michael addition and carbocyclization has been developed starting from beta-N-allylamino enoates and various organometallic reagents (organozinc halides, diorganozinc reagents, and copper/zinc mixed species). In all cases the mechanism of this domino reaction has been evidenced to involve a radical-polar crossover mechanism.     

Continuous-wave mode-locked Ti:sapphire laser focusable to 5 x 10(13) W/cm(2)

Generation of sub-10-fs pulses with an average power of 1 W and a peak of 1.5 MW from a Kerr-lens mode-locked mirror-dispersion-controlled Ti:sapphire laser is demonstrated. A specially designed lens triplet focuses the output of this compact all-solid-state source to a peak intensity in excess of 5x10(13) W/cm (2) . Nonperturbative nonlinear optics is now becoming feasible by use of the output of a cw mode-locked laser.     

Formation and evolution of scroll waves in photosensitive excitable media

Experimental and computational studies of the formation and evolution of scroll waves in three-dimensional excitable media are presented. Scroll waves are initiated in the photosensitive Belousov-Zhabotinsky reaction by perturbing traveling waves transverse to their direction of propagation. Scroll rings are generated by perturbing circular waves, which expand or contract depending on the strength of an imposed excitability gradient and its direction relative to the rotational direction of the scroll wave. (c) 1998 American Institute of Physics.     

Passivation of SnF2 by a coating of SnO2 formed on heating in air

X-ray powder diffraction and tin-119 Mössbauer spectroscopy were used to study samples of SnF₂ heated in open teflon containers under air. The reactivity was found to be low at 100 °C and to increase dramatically with temperature. Passivation by a layer of refractory SnO₂ that coats the surface of the particles is very effective at low temperature. The reactivity increases at the transition and close to the melting point, since both result in bond breaking and therefore offers opportunities for chemical attack.     

Study of active carbons by X-ray methods

The X-ray scattering properties of carbon black and charcoals, activated chemically and by steam have been studied in a transmission arrangement. The radial distribution functions calculated from the experimental data indicate that the majority of carbon atoms in chemically activated samples have sp³ configurations, characteristic of strained ring systems. Activation by steam produces a small amount of crystalline graphite. Most of the carbon atoms in carbon black are in an sp²-hybrid state, apparently because of the presence of contaminating atoms in appreciable amount, although no crystalline graphite can be detected.