  We connect the observed under-abundances of Li and Be in dwarfs, with recent
results on nuclear cross sections at low energies: for collisions of protons
with atomic or molecular targets, the measured cross sections seem too high
with respect to extrapolations for bare nuclei. Phenomenologically, these
anomalous nuclear interactions can be described in terms of an effective
screening potential $U_{lab}$ in the range of few hundred eV: in the presence
of the electron cloud, nuclei become more transparent to each other as if the
effective collision energy is aumented by $U_{lab}$. This implies that fusion
cross sections are enlarged and at the same time elastic cross sections are
lowered. If something similar occurs in stellar plasma, the nuclear burning
temperatures are lowered, whereas diffusion processes are enhanced. We find
that the observed Li and Be abundances in the Hyades and in the Sun can be
reproduced for effective screening potentials of the plasma in the range of
600-700 eV, close to that found by experiments in the lab.
