in this paper, we introduce a class of rings which is a generalization of reversible rings. let r be a ring with identity. a ring r is called central reversible if for any a,b ∈ r, ab=0 implies ba belongs to the center of r. since every reversible ring is central reversible, we study sufficient conditions for central reversible rings to be reversible. we prove that some results of reversible ri...

a hydroponic experiment was carried out to compare root anatomy and hydraulic conductivity of four barley cultivars including valfajr, karoon, afzal and zarjo under salt stress conditions. the results showed that under salt stress, the minimum diameter of vessels was observed in the peripheral metaxylem of seminal roots of valfajr cultivar and in adventitious roots; karoon with 19±3 µm had maxi...

bentonite deposits of economic interest are widespread in tashtab mountains (khur), east of isfahan province, iran. several bentonite deposits have been developed in this area as a result of eocene volcanic alteration. these deposits are classified as khur bentonite horizon. xrd analyses reveal that alteration products consist of na-montmorillonite, kaolinite, quartz, calcite, and crystobalite....

nigella sativa (ns) (ranunculaceae family) is generally utilized as a therapeutic plant all over the world. the seeds of the plant have a long history of use in different frameworks of medicines and food. in islamic literature, it is considered as one of the greatest forms of therapeutics. it has been widely used to treat nervous system diseases such as memory impairment, epilepsy, neurotoxicit...

some lie algebra analogues of schur's theorem and its converses are presented. as a result, it is shown that for a capable lie algebra l we always have dim l=z(l)  2(dim(l2))2. we also give give some examples sup- porting our results.

let $gamma$ be a normal subgroup of the full automorphism group $aut(g)$ of a group $g$‎, ‎and assume that $inn(g)leq gamma$‎. ‎an endomorphism $sigma$ of $g$ is said to be {it $gamma$-central} if $sigma$ induces the the identity on the factor group $g/c_g(gamma)$‎. ‎clearly‎, ‎if $gamma=inn(g)$‎, ‎then a $gamma$-central endomorphism is a {it central} endomorphism‎. ‎in this article the conditi...

based on the importance and role of species diversity and richness as ameasurement of the health of an ecosystem; studying of their components can lead toevaluate the health condition of rangeland. this research was carried out in a part ofhighland mountainous rangeland of mount alborz range in iran. diversity and richnesswere assessed as an ecosystem health indicator. the study area was locate...

drought is a natural hazard that have in arid and semiarid areas more frequency. so the study and identify synoptic patterns affecting this phenomenon seems to be necessary. by using peripheral circulation approach, drought periods during the 30-year (2011-1982) in the six synoptic stations provinces of kerman, yazd and isfahan, which have a long-term cooperative period were calculated with usi...

purpose : the aim of this study is to measure the endogenous cortisol levels in the patients with central serous chorioretinopathy (cscr) and also, evaluate the short-term effect of oral ketoconazole in the treatment of both acute and chronic cscr. methods : in this prospective interventional case series 12 patients with acute cscr and 7 patients with chronic cscr (including one patient with bi...