equatorial/axial conversion in piperidine and phosphorinane with different substituents wereinvestigated with great details. three possible routes, i.e. heteroatom inversion and two ring inversiontype were considered. ring conversion can occur via two pathways one starts with ring flatteningfrom the heteroatom site (nitrogen in piperidine and phosphorous in phosphorinane) and the otherinitiates...

the effect of alkyl substituents on the c-phenyl and/or the n-phenyl ring of benzophenylhydroxamic acid on their molecular structure and hydrogen bonding has been investigated. the predominant configuration in chcl3 is determined by steric and electronic effects. substituents on the c-phenyl ring favor the cis configuration, while substituents in the n-phenyl ring favor a trans configuration. t...

In this paper, we investigate various kinds of extensions of twin-good rings. Moreover, we prove that every element of an abelian neat ring R is twin-good if and only if R has no factor ring isomorphic to‌ Z2  or Z3. The main result of [24] states some conditions that any right self-injective ring R is twin-good. We extend this result to any regular Baer ring R by proving that every elemen...

Let $R$ be a ring (not necessarily commutative) with nonzero identity. We define $Gamma(R)$ to be the graph with vertex set $R$ in which two distinct vertices $x$ and $y$ are adjacent if and only if there exist unit elements $u,v$ of $R$ such that $x+uyv$ is a unit of $R$. In this paper, basic properties of $Gamma(R)$ are studied. We investigate connectivity and the girth of $Gamma(R)$, where $...

an efficient and simple method for the preparation of si-imidazole-hso4 functionalized magnetic fe3o4 nanoparticles (si-im-hso4 mnps) and used as an efficient and reusable magnetic catalysts for the regioselective ring opening of epoxides under green conditions in water. this catalyst was used for the ring opening of epoxide corresponding to the thiocyanohydrins and azidohydrines. compared to t...

In this paper, a channel drop ring resonator filter based on two dimensional photonic crystal is proposed which is suitable for all optical communication systems. The multilayer of silicon rods in the center of resonant ring enables one to adjust resonant wavelength of the ring and enhance power coupling efficiency between ring and waveguide. Refractive index and radius of multilayer rods insid...

This research examined the types and characteristics of soil, including porosity, water content, void ratio, degree saturation to value infiltration rate in soil located western part Semarang City, Indonesia. The test was carried out at 49 measurement points, based on a 2×2 km 2 grid division area. field using turf-tech infiltrometer. data from results were calculated estimation model Kostiakov...

Abstract Infiltration is one of the watershed parameters that are essential for integrated water resources management. can be measured directly by a ground test such as using double infiltrometer. But very large watersheds, methods take lot time, require skilled manpower, and cost. Geographical information systems (GIS) remote sensing applications have been developed used in various fields reso...

purpose : to assess the results of intracorneal ring (icr) segments for treatment of patients with pellucid marginal degeneration (pmd) methods : in this prospective interventional case series study, eight eyes of 5 patients with pmd who were contact lens intolerant received one or two intacs (intacs, addition technology) segments. preoperative and postoperative evaluations included slit-lamp e...