Ostrich Eggshell

Ostriches were hunted in Egypt from the earliest times. From their eggshells beads, pendants, and vessels were manufactured. Decorated eggshells were used from the Predynastic Period onward and seem to have a religious meaning

Ostrich Eggshell

Ostriches were hunted in Egypt from the earliest times. From their eggshells beads, pendants, and vessels were manufactured. Decorated eggshells were used from the Predynastic Period onward and seem to have a religious meaning

Annealing effects on the microstructure of sputtered gold layers on oxidized silicon investigated by scanning electron microscopy and scanning probe microscopy

The structure of Au layers deposited by sputtering on oxidized p-type Si(100) substrates is investigated by a combination of scanning electron microscopy and scanning probe microscopy. The effect of the temperature on the grain structure of the layers has been determined, revealing that an annealing temperature of 300degreesC results in a larger grain size and smoother surfaces but generates some cracks in the film surface. At an annealing temperature of 500degreesC, further grain growth is observed, but a high density of cracks and voids also results while there is little enhancement regarding the smoothness of the grain surfaces

Bis(trimethylsilyl)ethyne as a Two-Electron Alkyne Ligand in Group 6 Carbonylmetal(0) Complexes: Photochemical Syntheses and Comprehensive Characterization of M(CO)₅(η²-Me₃SiC⋮CSiMe₃) (M = W, Mo, Cr) and trans-Mo(CO)₄(η²-Me₃SiC⋮CSiMe₃)₂

Continued irradiation of W(CO)6 in the presence of excess bis(trimethylsilyl)ethyne (btmse) in n-hexane solution yields W(CO)5(η2-btmse) as the sole product, with quantum yields of 0.66 and 0.69 at λexc = 365 and 313 nm, respectively. Cr(CO)6 behaves analogously, while with Mo(CO)6 the initially generated Mo(CO)5(η2-btmse) undergoes further CO substitution to form trans-Mo(CO)4(η2-btmse)2 as the second product. All four compounds were isolated in crystalline form and fully characterized by elemental analysis, MS, IR, and NMR spectroscopies as well as by single-crystal X-ray crystallography. They assume a quasi-octahedral coordination geometry with the alkyne triple bond being eclipsed to one OC−M−CO axis and, in the case of trans-Mo(CO)4(η2-btmse)2, in trans-orthogonal orientation to the second alkyne. Both Mo(CO)5(η2-btmse) and Cr(CO)5(η2-btmse) are labile toward alkyne displacement by CO, whereas W(CO)5(η2-btmse) and trans-Mo(CO)4(η2-btmse)2 undergo spontaneous 12CO/13CO exchange in the dark under mild conditions. Partially 13CO labeled samples generated in this way provide complementary CO stretching vibrational data needed for thorough analyses at the level of the energy-factored CO force field approximation. From all the structural features and spectroscopic data it is evident that bis(trimethylsilyl)ethyne acts as a two-electron donor ligand in this series of d6 carbonylmetal(0) complexes

Bericht zu den Entwicklungsarbeiten am Schlepperanbaugeraet ''Astfraese'' im Institut fuer Waldarbeit und Forstmaschinenkunde der Universitaet Goettingen

TIB: AC 8752 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman