Two independent, three-dimensional structures of yeast tRNAAsp, mainly differing by the conformation of the D loop, have been obtained from a multiple isomorphous replacement (MIR) X-ray analysis at 3.5-A resolution. The folding of the ribose-phosphate backbone is similar to that found for tRNAPhe; major differences concern the relative positioning of the acceptor and anticodon stems, and the conformation of the loops in the two molecules. Crystal packing involves self-complementary GUC anticodon interactions.

By a simple washing of vaterite with ultrapure water, it transforms rapidly into cubic calcite. When the solid is washed with Cu 2+ solutions, the transformation depends on the concentrations of the copper solutions applied in the process. For concentrations of 10 -4 mol dm -3 , a certain delay in the transformation process is detected, and the obtained cubic calcite seems to be in the form of Cu x Ca 1-x CO 3 . For concentrations of 10 -3 mol dm -3 , the vaterite structure remains stable with time, and this stability seems to be correlated with the saturation of the surface by Cu 2+ in place of Ca 2+ . For concentrations of 10 -2 mol dm -3 , a mixture of vaterite, aragonite, cubic calcite, and malachite is obtained during the transformation process.

The chemical effects of high-intensity ultrasound have long been known to arise from cavitation: the creation, expansion, and adiabatic compression of gas vacuoles in solution during sonication.1 The intense, but transient, local heating and compression produced during cavitation have been calculated2,3 to reach as high as 10000 °C and 10000 atm, thus producing a variety of highenergy species in solution. The effects of high-intensity ultrasound on transition-metal and organometallic complexes have not been previously studied. We report herein the observed sonochemistry