Optically active oligomer units in aggregates of a highly unsaturated, optically inactive carotenoid phospholipid

Enantiomers of glycerophospholipids show low or no optical activity. Accordingly, optical activity was not observed with the R enantiomer of a highly unsaturated carotenoyl lysophospholipid in solution. In spite of this, strong Cotton effects are detected in water. The amphiphilic carotenoid-phospholipid monomers associate to form aggregates, whose optical activity is attributed to oligomeric entities. These small helical assemblies cannot exist independently. Yet, the calculated octamer represents the simplest repeating primary unit that sufficiently expresses the absorption properties and supramolecular optical activity.     

Distant collaboration in drug discovery: the LINK3D project

The work describes the development of novel software supporting synchronous distant collaboration between scientists involved in drug discovery and development projects. The program allows to visualize and share data as well as to interact in real time using standard intranets and Internet resources. Direct visualization of 2D and 3D molecular structures is supported and original tools for facilitating remote discussion have been integrated. The software is multiplatform (MS-Windows, SGI-IRIX, Linux), allowing for a seamless integration of heterogeneous working environments. The project aims to support collaboration both within and between academic and industrial institutions. Since confidentiality is very important in some scenarios, special attention has been paid to security aspects. The article presents the research carried out to gather the requirements of collaborative software in the field of drug discovery and development and describes the features of the first fully functional prototype obtained. Real-world testing activities carried out on this prototype in order to guarantee its adequacy in diverse environments are also described and discussed.In addition to the mentioned institutions the LINK3D Consortium is constituted by     

STS investigations to describe corrosion procedures on thin CrN layers

To represent the corrosion characteristics of thin hard material layers, CrN layers, which were magnetron sputtered, have been exposed to solutions with chloride or sulfate ions. The alterations of the layer surfaces were examined. Static immersion tests were carried out ex-situ in 1 mol L(-1) NaCl or 1 mol L(-1) Na(2)SO(4) solution over a period of 14 months. For in-situ measurements, the layers were inserted into the electrochemical cell of an EC STM as the working electrode. The sample potential was altered cyclically. At the same time, voltammograms were taken and the topography alteration was observed.Alterations in the surface structure were documented as hybrid information resulting from changes in topography and the chemical consistency or the thickness of the oxide layers. These modifications were demonstrated with scanning tunnelling spectroscopy before and after the treatment with solutions. Several chemical phases (initial state and oxide layers) were distinguished with raster tunnelling spectroscopy (measurements I(V) and I(z)). The evaluation of the I(z) spectroscopy showed that the tip was in mechanical contact with the sample if an oxide layer of greater thickness has existed.Exemplary XPS investigations demonstrated corrosive alterations of the CrN layers due to oxidation. Asymmetry and peak locations suggest that in addition to Cr(2)O(3) and CrN a complex mixture of different chromium oxides such as Cr(2)O(3) and Cr(OH)( x) exists.     

Cyclobutendion und methylencyclobutenon. Synthese,dienophile reaktivität und exo,endo-selektivität

A new synthesis of cyclobutenedione and methylenecyclobutenone and their reactions with 1,3-dienes are described.     

Photochemical cycloaddition of olefie to aromatic compounds -IV. on the mechanism of the photochemical meta-cycloaddition.

The meta-photoadditions of 1,3-dioxoles to benzene are shown to yield predominantly exo-configurated products. The mechanism is considered in the light of these new results.