A synthetic combinatorial library containing 52,128,400 D-amino acid hexapeptides was used to identify a ligand for the mu opioid receptor. The peptide, Ac-rfwink-NH2, bears no resemblance to any known opioid peptide. Simulations using molecular dynamics, however, showed that three amino acid moieties have the same spatial orientation as the corresponding pharmacophoric groups of the opioid peptide PLO17. Ac-rfwink-NH2 was shown to be a potent agonist at the mu receptor and induced long-lasting analgesia in mice. Analgesia produced by intraperitoneally administered Ac-rfwink-NH2 was blocked by intracerebroventricular administration of naloxone, demonstrating that this peptide may cross the blood-brain barrier.

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Using Derjaguin's approximation, we have evaluated the interaction energy associated with van der Waals, electrostatic, depletion, and capillary forces between colloidal spheroids. If the interaction range between spheroids is distinctly smaller than the lengths of their principal axes, then simple pair potentials that depend on particle distance and orientation can be derived. Attractive interactions between adjacent spheroids favor their parallel alignment. Parallel spheroids can be arranged into a variety of densely packed configurations. All of these configurations turn out to have the same lattice energy. We discuss the implications of this degeneracy with respect to the stability of photonic crystals consisting of spheroids.

The acoustic emission during tensile tests is investigated for several types of aluminium alloys. It. is found that the mean square amplitude of the continuous emission is proportional to strain rate and sample length. It is assumed that the continuous emission is generated by dislocation loops, which are created continuously a t Frank-Read sources. According to this model the mean square amplitude of the continuous emission U8 is proportional to the total length of the mobile dislocations L and the size of the loops I : vz -LZ. Information about I was taken from Kuhlmann and Wilsdorf's observations of slip lines a t the surface of deformed aluminium single crystals.An mehreren Aluminiumlegierungen wird die Schallemission wiihrend plastischer Verformung untersucht. Es wird gefunden, daB das mittlere Amplitudenquadrat der kontinuierlichen Emission der Verformungsgeschwindigkeit und der Probenliinge proportional ist.Es wird angenommen, daD die kontinuierliche Emission von Versetzungen herriihrt, die gleichmiiBig von Frank-Read-Quellen ausgestoBen werden. In diesem Modell ist das mittlere Amplitudenquadrat der Emission der gesamten beweglichen Versetzungsliinge L und der LLnge I der Versetzungsschleifen proportional : 6 -LZ. Die Ergebnisse werden mit Werten der Gleitlinienlangen auf Einkristallen von Kuhlmann und Wilsdorf verglichen.