Matter wave diffraction from an inclined transmission grating: searching for the elusive 4He trimer Efimov state

The size of the helium trimer is determined by diffracting a beam of 4He clusters from a 100 nm period grating inclined by 21 degrees. Because of the bar thickness the projected slit width is roughly halved to 27 nm, increasing the sensitivity to the trimer size. The peak intensities measured out to the eighth order are evaluated via a few-body scattering theory. The trimer pair distance is found to be (r) = 1.1(+0.4)(-0.5) nm in agreement with predictions for the ground state. No evidence for a significant amount of Efimov trimers is found. Their concentration is estimated to be under 6%, less than expected.

Diffraction of neutral helium clusters: evidence for "magic numbers"

The size distributions of neutral 4He clusters in cryogenic jet beams, analyzed by diffraction from a 100 nm period transmission grating, reveal magic numbers at N=10-11, 14, 22, 26-27, and 44 atoms. Whereas magic numbers in nuclei and clusters are attributed to enhanced stabilities, this is not expected for quantum fluid He clusters on the basis of numerous calculations. These magic numbers occur at threshold sizes for which the quantized excitations calculated with the diffusion Monte Carlo method are stabilized, thereby providing the first experimental confirmation for the energy levels of 4He clusters.

[Histochemical and ultrastructural study of cytochrome-oxydase in basal cell epithelioma]

The activity of cytochrome-oxydase is less pronounced in the basal cell epithelioma than in the basal cells of the surrounding normal epidermis. The electron microscopic study of the localisation of the enzyme reveals that the cells of the basal cell epithelioma contain two types of mitochondria, the first of which having the same size as the epidermal mitochondria, and the other being giant mitochondria. The latter seem to be less active. The weak reactivity of the basal cell epithelioma for cytochrome-oxydase is probably due to the reduction of the cristae in mitochondria and to the functional deficiency of the giant mitochondria.