Cover Picture: Angew. Chem. Int. Ed. 15/2002

The cover picture shows the interior of a red‐figure kylix (440–430 BC, British Museum London) which shows the brilliant exploits of Theseus, the Greek mythology hero. In the center, Theseus is shown defeating the infamous Minataur within the labyrinth. On the right, the hero raises his hand against Sciron, below whom the turtle is visible. Next clockwise, are shown the bull of Marathon, the punishment of Sinis, the slaying of the sow Phaea, the battle of Cercyon, and finally the punishment of Procrustes. The labors of Theseus are no different from the accomplishments of today's synthetic chemists working in total synthesis. One such endeavor, the total synthesis of the CP molecules with its challenges, twists and turns, and dead‐ends, but also its rewards, is compared to the conquest of the Minotaur by Theseus in the Review by K. C. Nicolaou and P. S. Baran on p. 2678 ff.     

The Explicit Density Functional and Its Connection with Entropy Maximization

The intrinsic Helmholtz free energy, commonly used as a basis for density functional theories, is here given explicitly as a cluster diagram expansion with density field points. Also given are explicit variational procedures for determining the chemical potential for a given density, the pair potential for a given pair correlation function, and the pair correlation function for a given pair potential. The physical meaning of the density functional is established within the context of a new derivation of statistical mechanics based on entropy that supplies a variational principle for equilibrium by generalizing the thermodynamic potential to nonequlibrium states. This shows that the conventional density functional determines not only the equilibrium density, but also the probability of fluctuations about that density.     

Substrate specificity of the human proteasome

BACKGROUND: Regulated proteolysis by the proteasome is crucial for a broad array of cellular processes, from control of the cell cycle to production of antigens. RESULTS: The rules governing the N-terminal primary and extended substrate specificity of the human 20S proteasome in the presence or absence of 11S proteasome activators (REGalpha/beta and REGgamma) have been elaborated using activity-based proteomic library tools. CONCLUSIONS: The 11S proteasome activators are shown to be important for both increasing the activity of the 20S proteasome and for altering its cleavage pattern and substrate specificity. These data also establish that the extended substrate specificity is an important factor for proteasomal cleavage. The specificities observed have features in common with major histocompatibility complex (MHC) class I ligands and can be used to improve the prediction of MHC class I restricted cytotoxic T-cell responses.     

An assessment of the safety of rapidly changing magnetic fields in the rabbit: Implications for NMR imaging

The effects of rapidly changing magnetic fields on the cardiac and respiratory functions of anaesthetised rabbits have been investigated. No changes were observed using pulsed fields with peak rates of change of 60 T/sec. The implications of these experiments for the safety of NMR imaging are discussed.     

A model for the ∼ 1.10eV emission band in InP

A study of the emission band present in InP has been made at temperatures between 4.2 and 280 K. The emission spectrum has phonon-structure at lower temperatures. The observed band shape and band-peak position are well explained by the configuration coordinate model. The coupling strength S, a measure of the lattice-localized center interaction, ranges from 1.7 to 3.5. A nearest-neighbor molecular-like defect center (Fe)_In—(V)_p appears to be responsible for the 1.10eV emission band.     

Rapid droplet mixers for digital microfluidic systems

The mixing of analytes and reagents for a biological or chemical lab-on-a-chip is an important, yet difficult, microfluidic operation. As volumes approach the sub-nanoliter regime, the mixing of liquids is hindered by laminar flow conditions. An electrowetting-based linear-array droplet mixer has previously been reported. However, fixed geometric parameters and the presence of flow reversibility have prevented even faster droplet mixing times. In this paper, we study the effects of varying droplet aspect ratios (height:diameter) on linear-array droplet mixers, and propose mixing strategies applicable for both high and low aspect ratio systems. An optimal aspect ratio for four electrode linear-array mixing was found to be 0.4, with a mixing time of 4.6 seconds. Mixing times were further reduced at this ratio to less than three seconds using a two-dimensional array mixer, which eliminates the effects of flow reversibility. For lower aspect ratio (相似文献