  Single top-quark t-channel production is exploited for studies of top quark
properties. The analyses include the measurement of the CKM matrix element,
$|V_{tb}|$, search for anomalous couplings of the top quark using a Bayesian
neural network analysis, measurement of single top-quark polarization which
directly confirms the V-A nature of the $tWb$ production vertex, and the
measurement of W-helicity fractions in the phase space sampled by a selection
optimized for t-channel single top-quark production, orthogonal to the
$t\overline{t}$ final states used in traditional measurements of these
properties. All measurements are found to be consistent with the standard model
predictions.
