For a ring endomorphism $alpha$ and an $alpha$-derivation $delta$, we introduce a concept, so called skew $pi$-Armendariz ring, that is a generalization of both $pi$-Armendariz rings, and $(alpha,delta)$-compatible skew Armendariz rings. We first observe the basic properties of skew $pi$-Armendariz rings, and extend the class of skew $pi$-Armendariz rings through various ring extensions. We nex...

statement of the problem: implant-retained overdenture can improve the stability of dentures and prevent bone loss. overdenture-wearing patients need special hygiene care. purpose: the aim of this study was to evaluate the effects of various denture cleansers on the retention of dio orange o-rings. method and materials : in this experimental study, 40 dio orange o-rings were divided into 4 grou...

A commutative ring A is said to be clean if every element of A can be written as a sum of a unit and an idempotent. This definition dates back to 1977 where it was introduced by W. K. Nicholson [7]. In 2002, V. P. Camillo and D. D. Anderson [1] investigated commutative clean rings and obtained several important results. In [4] Han and Nicholson show that if A is a semiperfect ring, then A[Z2] i...

We study the cancellation property of projective modules rank $2$ with a trivial determinant over Noetherian rings dimension $\leq 4$. If $R$ is smooth affine algebra $4$ an algebraically closed field $k$ such that $6 \in k^{\times}$, then we prove stably free $R$-modules are if and only Hermitian $K$-theory group $\tilde{V}_{SL} (R)$ trivial.

Thirty-one isomers of polychlorinated biphenyl (PCB) were examined for biodegradability by two species of Alcaligenes and Acinetobacter. The following relationships between chlorine substitution and biodegradability of PCBs were observed. (i) Degradation decreased as chlorine substitution increased. PCB isomers containing more than four chlorines were less susceptible to degradation. (ii) PCBs ...

We develop a representation theoretic technique for detecting closed orbits that is applicable in all characteristics. Our based on Kempf’s theory of optimal subgroups and we make some improvements simplify the from computational perspective. exhibit our many examples particular, give an algorithm to decide if symmetric polynomial $n$-variables has $\operatorname{SL}\_n$-orbit. As important app...

The aim of this paper is to generalize the‎‎notion of pseudo-almost valuation domains to arbitrary‎ ‎commutative rings‎. ‎It is shown that the classes of chained rings‎ ‎and pseudo-valuation rings are properly contained in the class of‎ ‎pseudo-almost valuation rings; also the class of pseudo-almost‎ ‎valuation rings is properly contained in the class of quasi-local‎ ‎rings with linearly ordere...

0045-7930/$ see front matter 2009 Elsevier Ltd. A doi:10.1016/j.compfluid.2009.10.006 * Corresponding author. Tel./fax: +1 949 824 1750. E-mail address: [email protected] (F. Liu). The vortex dominated flows in the near field of jets from notched circular nozzles are investigated using direct numerical simulation. The nozzles studied include a normal circular nozzle, a V-shaped notched nozzle, and a...

BACKGROUND This study was undertaken to compare the in vitro effects of 17beta-estradiol on human epicardial coronary arteries, resistance coronary arteries and on arterial vessels usually employed as grafts in surgical myocardial revascularization. METHODS Coronary artery rings (descending coronary artery, right coronary artery, circumflex coronary artery, first septal branch) and arterial g...

In a theoretical study, combining molecular dynamics simulations, quantum-chemical calculations, and charge migration simulations based on Marcus theory, we investigate the electronic structure, its fluctuations, and the charge transport of a promising organic near-infrared absorber material: 7,7-difluoro-7H-5,9diphenyldiisoindolo[2,1-c:1′,2′-f ][1,3,5,2]triazaborinine-6-ium-7-uide (Ph2-benz-BO...