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Energetic particle methods have been used to synthesize two metastable layers with superior mechanical properties: amorphous Ni implanted with overlapping Ti and C, and amorphous diamond-like carbon (DLC) formed by vacuum-arc deposition or pulsed laser deposition. Elastic modulus, yield stress and hardness were reliably determined for both materials by fitting finiteelement simulations to the observed layer/substrate responses during nanoindentation. Both materials show exceptional properties, i.e., the yield stress of amorphous Ni(Ti,C) exceeds that of hardened steels and other metallic glasses, and the hardness of DLC (up to 88 GPa) approaches that of crystalline diamond (∼100 GPa). Tribological performance of the layers during unlubricated sliding contact appears favorable for treating Ni-based micro-electromechanical systems: stick-slip adhesion to Ni is eliminated, giving a low coefficient of friction (∼0.3–0.2) and greatly reduced wear. We discuss how energetic particle synthesis is critical to forming these phases and manipulating their properties for optimum performance.
A major astrophysical problem is related to the fact that rotation curves (RCs)) of galaxies are flat. The presence of a dark halo is most often invoked to explain that. Some controversies exist concerning the existence of a dark halo for galaxies in very hostile environments like in center of clusters. Using a scanning Fabry-Perot interferometer, we have observed Hα velocity fields of a sample of 38 galaxies located in 7 different clusters of galaxies. From this sample, our conclusion is that spirals located in the central part of clusters do not have decreasing RCs within the optical radius.
Studies are now in progress on the nature of various possible systematic and random errors which may be influencing the values of the Hubble parameter Ho derived from application of the Tully-Fisher method to samples of cluster spirals outside of the Local Supercluster. Three effects seem to be of most importance. (1) Clusters yield slopes in the infrared Tully-Fisher diagram varying from 8 to 12, making it problematic as to how to derive a relative distance modulus from comparison with the local calibrators, (2) errors in measured 21-cm line widths (often measured at low signal-to-noise ratios) are the dominant source of error in derived relative distances, (3) errors in measured optical major and minor axes of a galaxy influence both its derived inclination and the H-magnitude as corrected to a standard isophote. Monte Carlo simulations of cluster samples, however, have shown that the tendency not to detect H I from edge-on and/or low-luminosity galaxies introduces no important biases. Overall, the relative distance of any of these clusters to the local calibrators appears to be good to ±20%.
Hyperkinetic movement disorders may occur as side effects of antipsychotic drugs; and a hyperdopaminergic state induced by the neuroleptic compounds is thought to be a cause of extrapyramidal disorders such as tardive dyskinesia. We have observed two cases of the dyskinetic syndrome in patients receiving tricyclic antidepressants (TCA). Because the TCA are known to have little effect on striatal dopamine but do share with the neuroleptics potent anticholinergic activity, these cases appear to support the hypothesis that the drug-induced hyperkinetic disorders are related to a diminution of CNS acetylcholine activity as well as to an increase in dopamine activity.
Maps with 0′.5 resolution are presented of the distribution of neutral hydrogen in two galaxies. The barred spiral NGC 5383 contains much hydrogen, in strong differential rotation, in its outer parts; some H I concentrations with possibly anomalous velocities are observed in the regions of bar and nucleus. In the giant Scd spiral M101, the H I distribution corresponds closely with the optical spiral pattern, except for a lack of hydrogen in the central region.
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