  We generalize Amitsur's construction of central simple algebras over a field
$F$ which are split by field extensions possessing a derivation with field of
constants $F$ to nonassociative algebras: for every central division algebra
$D$ over a field $F$ of characteristic zero there exists an
infinite-dimensional unital nonassociative algebra whose right nucleus is $D$
and whose left and middle nucleus are a field extension $K$ of $F$ splitting
$D$, where $F$ is algebraically closed in $K$. We then give a short direct
proof that every $p$-algebra of degree $m$, which has a purely inseparable
splitting field $K$ of degree $m$ and exponent one, is a differential extension
of $K$ and cyclic. We obtain finite-dimensional division algebras over a field
$F$ of characteristic $p>0$ whose right nucleus is a division $p$-algebra.
