background and objective: evaluation of the results, safety, and stability of ferrara intracorneal ring segment (ficrs) implantation for keratoconus correction (age range was 24.39±8.32 years).   materials and methods: in this clinical trial study, 64 eyes of 57 patients with keratoconus and clear cornea that had ficrs implantation were studied. uncorrected visual acuity (ucva), best-spectacle ...

Introduction: Hydrogen sulfide (H2S) plays a key role in the regulation of vascular tone and protection of blood vessels against endothelial dysfunction. Since the mechanism of salt impairing H2S-induced vascular relaxation is not fully clear, therefore this study was designed to investigate the role of potassium (K+) channels in the vasodilatory effects of exogenous H2S in rat aortic rings.&nb...

In the present work, an extensive theoretical calculation study on Histidine-Histidine dipeptide in gas phase is done by using DFT method with Gaussian 98 program. Through investigations on the molecular geometries of this molecule it is found that there is six rings in the molecules not two rings. The presence of four intramolecular hydrogen bonds is responsible for the formation of additional...

Let $alpha$ be an automorphism of a ring $R$. The authors [On skewinverse Laurent-serieswise Armendariz rings, Comm. Algebra 40(1)(2012) 138-156] applied the concept of Armendariz rings to inverseskew Laurent series rings and introduced skew inverseLaurent-serieswise Armendariz rings. In this article, we study on aspecial type of these rings and introduce strongly Armendariz ringsof inverse ske...

Elastic stability of ring and stringer-stiffened cylindrical shells under axial, internal and external pressures is studied using Ritz method. The stiffeners are rings, stringers and their different arrangements at the inner and outer surfaces of the shell. Critical buckling loads are obtained using Ritz method. It has been found that the cylindrical shells with outside rings are more stable th...

In this paper, we introduce a class of $J$-quasipolar rings. Let $R$ be a ring with identity. An element $a$ of a ring $R$ is called {it weakly $J$-quasipolar} if there exists $p^2 = pin comm^2(a)$ such that $a + p$ or $a-p$ are contained in $J(R)$ and the ring $R$ is called {it weakly $J$-quasipolar} if every element of $R$ is weakly $J$-quasipolar. We give many characterizations and investiga...

in this work, using eigenvalues and eigenvectors of unitary cayley graphs over finite local rings and elementary linear algebra, we characterize which local rings allowing pst occurring in its unitary cayley graph. moreover, we have some developments when $r$ is a product of local rings.

in this paper, we introduce the new notion of n-f-clean rings as a generalization of f-clean rings. next, we investigate some properties of such rings. we prove that mn(r) is n-f-clean for any n-f-clean ring r. we also, get a condition under which the denitions of n-cleanness and n-f-cleanness are equivalent.