We give an example of a spacetime having an infinite thin rotating cylindrical shell constituted by a charged perfect fluid as a source. As the interior of the shell the Bonnor–Melvin universe is considered, while its exterior is represented by Datta– Raychaudhuri spacetime. We discuss the energy conditions and we show that our spacetime contains closed timelike curves. Trajectories of charged ...

Using numerical and asymptotic methods, the lowest natural frequencies vibration modes of a structure consisting closed circular cylindrical shell with an end cap attached to it, having shape shallow spherical segment, are studied in paper. Three types vibrations described. Eigenfrequencies first type, close shell, were previous works. In this paper, we study forms second type (cylindrical shel...

‎in this paper, a new class of fuzzy sets called fuzzy strongly ${{g}^{*}}$-closed sets is introduced and its properties are investigated. moreover, we study some more properties of this type of closed spaces.

Graphene is considered as one of the most promising materials for post silicon electronics, as it combines high electron mobility with atomic thickness [Novoselov et al. Science 2004, 306, 666-669. Novoselov et al. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 10451-10453]. The possibility of chemical doping and related excellent chemical sensor properties of graphene have been demonstrated experime...

background: persian gulf is a semi-closed environment which is affected by pollution ‎from heavy metals. entrance of heavy metals to the water column and binding to ‎sediment particles can affect the benthic organisms that can accumulate these ‎materials in their body. noticing this ability, mussels are considered as bio-monitoring ‎agents.‎ methods: the pearl oyster, pinctada radiate, and sedi...

States in Zr have been observed with the (n ,n8g) reaction using both spallation and monoenergetic accelerator-produced neutrons. A scheme comprised of 81 levels and 157 transitions was constructed concentrating on levels below 5.6 MeV in excitation energy. Spins have been determined by considering data from all experimental studies performed for Zr. Lifetimes have been deduced using the Dopple...

A family of small graphene patches, i.e., rectangular polyaromatic hydrocarbons (PAHs), that have both zigzag and armchair edges is investigated to establish their ground state electronic structure. Broken symmetry density functional theory (DFT) and plane wave DFT were used to characterize the onset of diradical character via relative energies of open-shell and closed-shell singlet states. The...

Brine systems in Europa’s ice shell have been hypothesized as potential habitats that could be more accessible than the sub-ice ocean. We model distribution of sub-millimeter-scale brine pockets shell. Through examination three habitability metrics (water activity, ionic strength, salinity), we determine are likely not geochemically prohibitive to life know it for chloride and sulfate-dominated...

Evolution of quadrupole deformations in sd and pf shell nuclei with mass A= 18∼56 is studied by using deformed Skyrme Hartree-Fock (HF) model with pairing correlations. We point out that the quadrupole deformations of the nuclei with the isospin T=0 and T=1 show strong mass number dependence as a clear manifestation of dynamical evolution of deformation in nuclear many-body systems. The competi...

We discuss the role of quantum chaos in atomic nuclei. After reviewing the basic assumptions of the nuclear shell model, we analyze the spectral statistics of the energy levels obtained with realistic shell–model calculations in the f p shell. In particular, for Ca isotopes we observe a transition from order to chaos by increasing the excitation energy and a clear quantum signature of the break...