we call a module  essentially retractable if homr for all essential submodules n of m. for a right fbn ring r, it is shown that: (i)  a non-zero module  is retractable (in the sense that homr for all non-zero ) if and only if certain factor modules of m are essentially retractable nonsingular modules over r modulo their annihilators. (ii)  a non-zero module  is essentially retractable if and on...

the density functional theory (dft) and the natural bond orbital (nbo) calculations basedmethod b3lyp/6-31g were carried out to study the interaction of dopamine with carbon nanotube.the nanotube used in this study, includes 60 c atoms (6, 6) type. relative and formation energies ofcompounds, muliken charges, occupancy, the highest occupied molecular orbital (homo) and thelowest unoccupied mole...