The Nature of Ultra-Luminous Compact X-Ray Sources in Nearby Spiral Galaxies

Studies were made of ASCA spectra of seven ultra-luminous compact X-ray sources (ULXs) in nearby spiral galaxies; M33 X-8 (Takano et al. 1994), M81 X-6 (Fabbiano 1988b; Kohmura et al. 1994; Uno 1997), IC 342 Source 1 (Okada et al. 1998), Dwingeloo 1 X-1 (Reynolds et al. 1997), NGC 1313 Source B (Fabbiano & Trinchieri 1987; Petre et al. 1994), and two sources in NGC 4565 (Mizuno et al. 1999). With the 0.5--10 keV luminosities in the range 10^{39-40} ergs/s, they are thought to represent a class of enigmatic X-ray sources often found in spiral galaxies. For some of them, the ASCA data are newly processed, or the published spectra are reanalyzed. For others, the published results are quoted. The ASCA spectra of all these seven sources have been described successfully with so called multi-color disk blackbody (MCD) emission arising from optically-thick standard accretion disks around black holes. Except the case of M33 X-8, the spectra do not exhibit hard tails. For the source luminosities not to exceed the Eddington limits, the black holes are inferred to have rather high masses, up to ~100 solar masses. However, the observed innermost disk temperatures of these objects, Tin = 1.1--1.8 keV, are too high to be compatible with the required high black-hole masses, as long as the standard accretion disks around Schwarzschild black holes are assumed. Similarly high disk temperatures are also observed from two Galactic transients with superluminal motions, GRO 1655-40 and GRS 1915+105. The issue of unusually high disk temperature may be explained by the black hole rotation, which makes the disk get closer to the black hole, and hence hotter.Comment: submitted to ApJ, December 199

Superfast spreading rate crust 2 and 3

IODP publications, Scientific Prospectu

Selectivity Switch in the Synthesis of Vinylgold(I) Intermediates

An unexpected regioselectivity reversal was observed in the synthesis of vinylgold(I) complexes from propargyl carboxamides. The use of [Au(IPr)(OH)] affords preferentially vinylgold(I) complexes resulting from a 5-exo-dig cyclization, whereas the use [Au(IPr)](+) species, generated in situ starting from [Au(IPr)(Cl)] and AgOTf, leads to vinylgold(I) complexes which form via a 6-endo-dig cyclization, This unexpected "selectivity switch" for this cyclization led us to propose two different reaction pathways enabling the formation of the two different products. One mechanism involves the [Au(IPr)](+) species with "classical" pi activation of the alkyne framework of the carboxamides, and the second represents an "unusual" use of the basic Bronsted character of [Au(IPr)(OH)). Mechanistic and DFT studies support the mechanistic hypotheses

Superfast spreading rate crust 2: a complete in situ section of upper oceanic crust formed at a superfast spreading rate.

none43sinoneJ.C. Alt; D.A.H. Teagle; S. Umino; S. Miyashita; N.R. Banerjee; D.S. Wilson; F. Einaudi; A. Belghoul; C. Cordier; L. Crispini; L. Galli; Y. Gao; J. Geldmacher; L.A. Gilbert; E. Herreo-Bervera; S.A. Holter; C. Laverne; H.L. Lledo Vasques; S. Rodriguez Durand; T. Sakuyama; T. Sano; C.E. Smith-Duque; S. Tominaga; P. Tartarotti; E.A. Veloso Espinosa; M. Reichow; R. Anma; J. Carlut; D.M. Christie; R. Coggon; N.W. Hayman; N. Hirano; S. Ingle; J. Koepke; J. MacLennan; S. Morgan; N. Neo; S.H. Park; B. Scheibner; S.A. Swift; A.A. Tikku; T. Yamazaki; S. YamazakiJ. C., Alt; D. A. H., Teagle; S., Umino; S., Miyashita; N. R., Banerjee; D. S., Wilson; F., Einaudi; A., Belghoul; C., Cordier; Crispini, Laura; L., Galli; Y., Gao; J., Geldmacher; L. A., Gilbert; E., Herreo Bervera; S. A., Holter; C., Laverne; H. L., Lledo Vasques; S., Rodriguez Durand; T., Sakuyama; T., Sano; C. E., Smith Duque; S., Tominaga; P., Tartarotti; E. A., Veloso Espinosa; M., Reichow; R., Anma; J., Carlut; D. M., Christie; R., Coggon; N. W., Hayman; N., Hirano; S., Ingle; J., Koepke; J., Maclennan; S., Morgan; N., Neo; S. H., Park; B., Scheibner; S. A., Swift; A. A., Tikku; T., Yamazaki; S., Yamazak