A GC-MS with electron impact ionization was used for the development of a speciation method for the simultaneous determination of monobutyl-, dibutyl-, and tributyltin in environmental samples (waters, sediments, and biota). The method is based on the use of a mixed spike containing Sn-enriched monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) for isotope dilution analysis. The mixed ...

In this paper we introduce two symmetric variants of amenability, symmetric module amenability and symmetric Connes amenability. We determine symmetric module amenability and symmetric Connes amenability of some concrete Banach algebras. Indeed, it is shown that $ell^1(S)$ is  a symmetric $ell^1(E)$-module amenable if and only if $S$ is amenable, where $S$ is an inverse semigroup with subsemigr...

let $rin textbf{c}^{mtimes m}$ and $sin textbf{c}^{ntimes n}$ be nontrivial involution matrices; i.e., $r=r^{-1}neq pm~i$ and $s=s^{-1}neq pm~i$. an $mtimes n$ complex matrix $a$ is said to be an $(r, s)$-symmetric ($(r, s)$-skew symmetric) matrix if $ras =a$ ($ ras =-a$). the $(r, s)$-symmetric and $(r, s)$-skew symmetric matrices have a number of special properties and widely used in engi...

BACKGROUND Technological advances (e.g. directional drilling, hydraulic fracturing), have led to increases in unconventional natural gas development (NGD), raising questions about health impacts. OBJECTIVES We estimated health risks for exposures to air emissions from a NGD project in Garfield County, Colorado with the objective of supporting risk prevention recommendations in a health impact...

in recent decades, attention to contamination propagation into soils and underground water has increased, which has led to a rise in the studies on soil contamination problems and methods of in-situ remediation. in this research, effective parameters on oil contamination propagation in soils and underground water have been investigated using fem in order to determine propagation patterns. the m...

In this article, Finite Element Method (FEM) and Eulerian-Lagrangies Algorithm (ELA) formulation were used to numerically simulate the impact of several low-velocity projectiles with water surface. Material models which were used to express behavior of air and water included Null material model. For the projectiles, rigid material model were applied. Results were validated by analyzing the impa...