Temperature-dependence measurements of the luminescence spectra, the decay times and the luminescence intensities of some Cu' complexes are reported. The results are interpreted in terms of a three-level scheme. The lifetimes of these complexes vary considerably due to the differences in quantum efficiencies of the complexes. The charge-transfer character of the transitions involved is confirmed. E X P E R I M E N T A LCur complexes were prepared and characterized by the methods described previ~usly.'.'~ We found no significant variation of the luminescence properties of the complexes due to 595

Measurements are reported on the propagation velocity of ultrasound in muscle tissue. This appears to be dependent on fiber direction for various muscle types (in vitro). Typical results are 1550 m/s perpendicular and 1557 m/s parallel to fiber direction (20 degrees C). A model is drawn up to relate such data to the elastic properties of muscle. It is shown that the assumptions: linear elastic behavior, homogeneity, and anisotropy with cylindrical symmetry, do not harmonize with the experimental results. A more elaborate model is suggested. Contraction dependence of the ultrasound velocity was investigated on human biceps muscle (in vivo) and frog gastrognemius muscle (in vitro). The measured velocity increase in biceps muscle during contraction--up to 3 m/s--is attributed to a varying blood content of the muscle. In (in vitro) frog muscle contraction is not accompanied by a change in ultrasound velocity. This suggests that increased muscle stiffness is not appreciably reflected in ultrasound velocity.

Ttle 1uaGncsccnce of t11c tittc c~rnplcs ICu(dppf2 ] + in rhc solid state is reported. The results are compared with tflose crf r&rcd Cut con~plcscs ami with those for /Cu(dpp)2 1' in solution.

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