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An element x ∈ R is considered (strongly) nil-clean if it can be expressed as the sum of an idempotent e ∈ R and a nilpotent b ∈ R (where eb = be). If for any x ∈ R, there exists a unit u ∈ R such that ux is (strongly) nil-clean, then R is called a (strongly) unit nil-clean ring. It is worth noting that any unit-regular ring is strongly unit nil-clean. In this note, we provide a characterization of the unit regularity of a group ring, along with an additional condition. We also fully characterize the unitregularity of the group ring Z n G for every n > 1. Additionally, we discuss strongly unit nil-cleanness in the context of Morita contexts, matrix rings, and group rings.

We examine those matrix rings whose entries lie in periodic rings equipped with some additional properties. Specifically, we prove that the famous Diesl's question whether or not R being nil-clean implies that M n (R) is nil-clean for all n ≥ 1 is paralleling to the corresponding implication for (Abelian, local) periodic rings. Besides, we study when the endomorphism ring E(G) of an Abelian group G is periodic. Concretely, we establish that E(G) is periodic exactly when G is finite as well as we find a complete necessary and sufficient condition when the endomorphism ring over an Abelian group is strongly m-nil clean for some natural number m thus refining an "old" result concerning strongly nil-clean endomorphism rings. Responding to a question when a group ring is periodic, we show that if R is a right (resp., left) perfect periodic ring and G is a locally finite group, then the group ring RG is periodic, too. We finally find some criteria under certain conditions when the tensor product of two periodic algebras over a commutative ring is again periodic. In addition, some other sorts of rings very close to periodic rings, namely the so-called weakly periodic rings, are also investigated.