we introduce center-like subsets z*(r,f), z**(r,f) and z1(r,f), where r is a ring and f is a map from r to r. for f a derivation or a non-identity epimorphism and r a suitably-chosen prime or semiprime ring, we prove that these sets coincide with the center of r.

for an arbitrary ring $r$, the zero-divisor graph of $r$, denoted by $gamma (r)$, is an undirected simple graph that its vertices are all nonzero zero-divisors of $r$ in which any two vertices $x$ and $y$ are adjacent if and only if either $xy=0$ or $yx=0$. it is well-known that for any commutative ring $r$, $gamma (r) cong gamma (t(r))$ where $t(r)$ is the (total) quotient ring of $r$. in this...

let r be a prime ring with extended centroid c, h a generalized derivation of r and n ⩾ 1 a xed integer. in this paper we study the situations: (1) if (h(xy))n = (h(x))n(h(y))n for all x; y 2 r; (2) obtain some related result in case r is a noncommutative banach algebra and h is continuous or spectrally bounded.

a ring $r$ is a strongly clean ring if every element in $r$ is the sum of an idempotent and a unit that commutate. we construct some classes of strongly clean rings which have stable range one. it is shown that such cleanness of $2 imes 2$ matrices over commutative local rings is completely determined in terms of solvability of quadratic equations.

six new complexes of the type trans-[lco((do)(doh)pn)l'] where (do)(doh)pn= n2, n2'-propanediolbis (2,3-butanedione 2-imine 3-oxime), l-cl¯ and l'=mono-anaion of phenylcyanamide (pcyd), 2,5-dichlorophenylcyanamide (2,5-cl2 pcyd), 2,4-dimethyl pehylcyanamide (2,4-me2 pcyd) and l=l'=pcyd, 2,5-cl2 pcyd, 2,4-me2 pcyd, have been synthesized and characterized by elemental analysis, spectroscopy and c...

a moment equations method was performed to study the reversible chain transfer catalyzed polymerization (rtcp) of styrene in 80°c. to do this, a kinetic scheme containing conventional free radical polymerization reactions and equilibrium reactions of rtcp was assumed. after obtaining mass balance equations, three moment equations were defined for free and dormant radicals and dead chains. monom...

introduction: the role of midbrain reticular formation, which includes the nucleus cuneiformis (ncf), as a crucial antinociceptive region in descending pain modulation has long been investigated. in this study, we tried to highlight the role of ncf in morphine-induced antinociception in formalin-induced pain model in rats. methods: a total of 201 male wistar rats weighing 260-310 g were used in...

Recently testing of Quantum-dot Cellular Automata (QCA) Circuits has attracted a lot of attention. In this paper, QCA is investigated for testable implementations of reversible logic. To amplify testability in Reversible QCA circuits, a test method regarding to Built In Self Test technique is developed for detecting all simulated defects. A new Reversible QCA MUX 2×1 desig...

in this paper we define a new type of rings ”almost powerhermitian rings” (a generalization of almost hermitian rings) and establish several sufficient conditions over a ring r such that, every regular matrix admits a diagonal power-reduction.