  In a model in which leptons, quarks, and the recently introduced hyperquarks
are built up from two fundamental spin 1/2 preons, the standard model weak
gauge bosons emerge as preon bound states. In addition, the model predicts a
host of new composite gauge bosons, in particular those responsible for
hyperquark and proton decay. Their presence entails a left-right symmetric
extension of the standard model weak interactions and a scheme for a partial
and grand unification of nongravitational interactions based on respectively
the effective gauge groups SU(6)_P and SU(9)_G. This leads to a prediction of
the Weinberg angle at low energies in good agreement with experiment.
Furthermore, using evolution equations for the effective coupling strengths, we
calculate the partial and grand unification scales, the hyperquark mass scale,
as well as the mass and decay rate of the lightest hyperhadron.
