Localized in vivo H spectroscopy of human skeletal muscle: Normal and pathologic findings

To obtain high signal to noise ratio in small volume elements (8 cm³), in vivo ¹H NMR spectroscopy of normal and diseased human skeletal muscle was performed using a double spin-echo localization method on a 1.5-T whole body system. High resolved spectra of normal calf muscle show the well known resonances of lipids (methyl, methylene, olefinic, and other fatty acid resonances), creatine/phosphocreatine, choline/carnitine, taurine, and histidine with good intraindividual reproducibility. Pronounced intraindividual differences in the lipid range were found between different upper thigh muscle groups. On pathologic conditions like myopathia, myositis or irradiation damage the spectral lipid content was increased. Three months after local irradiation of the medial vastus muscle (50 Gy), the localized ¹H NMR spectrum showed a complete loss of the choline and creatine signals. In a case of M. Behçet with muscular involvement the relative reduction of the choline signal may provide an insight in the pathobiochemistry. The results of our investigations in nine healthy volunteers and three patients are presented in detail including relaxation times of the metabolites.     

Improved outcoupling of light in organic light emitting devices, utilizing a holographic DFB-structure

In this work organic light emitting devices (OLEDs) were fabricated implementing gratings, in order to extract waveguided electroluminescence (EL). The gratings were recorded by exposing thin films of the molecular azo glass N, N′-bis (4-phenyl)-N, N′-bis [(4-phenylazo)-phenyl] benzidine (AZOPD) to holographic light patterns. The photopatterned AZOPD serves as hole transport material for devices with aluminum-tris(8-hydroxyquinoline) doped with 1% of 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (Alq₃:DCM) as emissive/electron transport layer. The corrugated devices showed enhanced emission in the forward direction. The emitted light is polarized preferably parallel to the grating lines. In addition, we have found a doubling in the total luminance with respect to the unstructured device.     

High Performance Computing Techniques for the FEM Simulation in Structural Mechanics

For the solution of large scale simulations in structural mechanics iterative solving methods are mandatory. The efficiency of such methods can crucially depend on different factors: choice of material parameters, quality of the underlying computational mesh and number of processors in a parallel computing system. We distinguish between three aspects of ‘efficiency’: processor efficiency (degree to which the solving algorithm is able to exploit the processor's computational power), parallel efficiency (ratio between computation and communication times) and numerical efficiency (convergence behaviour). With the new FEM software package Feast we pursue the aim to develop a solver mechanism which at the same time gains high efficiencies in all three aspects, while trying to minimise the mentioned dependencies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Total synthesis of tetraacetyl clionamide

Tetraacetyl clionamide, a 6-bromotryptophan derivative from the sponge Cliona celata was synthesized from gallic acid.