Derivatives of thiazolidinone ring systems are known to act as anti-HIV infections , analgesic, anti-bacterial, anti-convulsant, anti parasitic, potential anti-inflammatory and herbicidal agents. Due biological activities of thiazolidinones ring, several methods for their synthesis have been illustrated in literature. Imidazolidine-2-thiones were synthesized by the oxidative cyclization of 1-be...

let $r$ be a ring‎, ‎and let $n‎, ‎d$ be non-negative integers‎. ‎a right $r$-module $m$ is called $(n‎, ‎d)$-projective if $ext^{d+1}_r(m‎, ‎a)=0$ for every $n$-copresented right $r$-module $a$‎. ‎$r$ is called right $n$-cocoherent if every $n$-copresented right $r$-module is $(n+1)$-coprese-nted‎, ‎it is called a right co-$(n,d)$-ring if every right $r$-module is $(n‎, ‎d)$-projective‎. ‎$r$ ...

the zero-divisor graph of a commutative ring r with respect to nilpotent elements is a simple undirected graph $gamma_n^*(r)$ with vertex set z_n(r)*, and two vertices x and y are adjacent if and only if xy is nilpotent and xy is nonzero, where z_n(r)={x in r: xy is nilpotent, for some y in r^*}. in this paper, we investigate the basic properties of $gamma_n^*(r)$. we discuss when it will be eu...

An enantioselective alkoxylation/Claisen rearrangement reaction was achieved by a strategic desymmetrization of 1,4-dienes under the catalysis of (S)-DTBM-Segphos(AuCl)2/AgBF4. This reaction system was highly selective for the formation of 3,3-rearrangement products, providing cycloheptenes with various substitutions in good yield and good to excellent enantioselectivity. This transformation wa...

Congenital anomalies of the great thoracic vessels have been reported in 20% of dogs and cats. In some cases, the vascular ring anomalies remain unrecognized throughout the lifetime of an animal. This report describes a case with an unusual vascular ring anomaly (VRA) that was detected during dissection on a cadaver of an approximately two-year-old male native mixed breed dog. No history of the...

The sealing performance will directly affect the operation of downhole robot under HTHP condition. Traditional analysis methods are that temperature and pressure is loaded respectively. This can not really evaluate performance. Besides, simulation process is: Step 1: pre-compress O-ring to produce contact force. According pressure, select compression ratio calculate displacement slip ring. 2: l...

A new method (thermal spokes) is proposed to simulate the guide rolls in FE analysis of the ring rolling process. So far this method is the only one, capable of calculating guide rolls reaction contact forces related to the stiffness of their adjustment mechanism. The method is simple to use, does not introduce further nonlinearities and could be used in any kind of FE formulations. The method ...

A new method (thermal spokes) is proposed to simulate the guide rolls in FE analysis of the ring rolling process. So far this method is the only one, capable of calculating guide rolls reaction contact forces related to the stiffness of their adjustment mechanism. The method is simple to use, does not introduce further nonlinearities and could be used in any kind of FE formulations. The method ...

We construct effective Hamiltonians which despite their apparently nonrelativistic form incorporate relativistic effects by involving parameters which depend on the relevant momentum. For some potentials the corresponding energy eigenvalues may be determined analytically. Applied to two-particle bound states, it turns out that in this way a nonrelativistic treatment may indeed be able to simula...