We examine when the nil and prime radicals of an algebra are stable under q-skew σ-derivations. We provide an example which shows that even if q is not a root of 1 or if δ and σ commute in characteristic 0, then the nil and prime radicals need not be δ-stable. However, when certain finiteness conditions are placed on δ or σ, then the nil and prime radicals are δ-stable.

Generalizing Petrogradsky’s construction, we give examples of infinite-dimensional nil Lie algebras of finite Gelfand–Kirillov dimension over any field of positive characteristic.

Let $f:A\to B$ and $g:A\to C$ be two ring homomorphisms and let $K$ and $K^{\text{'}}$ be two ideals of $B$ and $C$, respectively, such that $f^{-1}\left(K\right)=g^{-1}\left(K^{\text{'}}\right)$. We investigate unipotent, symmetric and reversible properties of the bi-amalgamation ring $A{\bowtie }^{f,g}(K,K^{\text{'}})$ of $A$ with $(B,C)$ along $(K,K^{\text{'}})$ with respect to $(f,g)$.