28,670 research outputs found

    Annealing-induced Fe oxide nanostructures on GaAs

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    We report the evolution of Fe oxide nanostructures on GaAs(100) upon pre- and post-growth annealing conditions. GaAs nanoscale pyramids were formed on the GaAs surface due to wet etching and thermal annealing. An 8.0-nm epitaxial Fe film was grown, oxidized, and annealed using a gradient temperature method. During the process the nanostripes were formed, and the evolution has been demonstrated using transmission and reflection high energy electron diffraction, and scanning electron microscopy. These nanostripes; exhibited uniaxial magnetic anisotropy. The formation of these nanostructures is attributed to surface anisotropy, which in addition could explain the observed uniaxial magnetic anisotropy

    Performances of Tiger Shrimp Culture in Environmentally Friendly Ponds

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    Mangrove ecosystem plays an obvious role in maintaining the biological balance in the coastal environment where shrimp ponds are usually constructed. The removal of mangroves around shrimp ponds has frequently brought about harvest failure. The study evaluated the performance of tiger shrimp culture in ponds provided with water from a water body where there was mangrove vegetation (hereafter mangrove reservoir). Twelve ponds, each measuring 2,500 m2, were filled with seawater from the mangrove reservoir until the water depth of 100 cm and then stocked with 20-40 PL/m2. In the first six ponds, the bottom water was released into the reservoir when the water depth reached 140 cm and then the water depth was maintained at 100 cm. In the second six ponds, the water was released from the ponds until the water depth reached 60 cm and then refilled with reservoir water until a depth of 100 cm. Both treatment ponds received water from the reservoir which also received the wastewater. The feeds for the shrimps were broadcast into the ponds twice a day to meet the 3% shrimp biomass requirement, which adjusted every other week through sampling. The result showed that mangrove vegetation is capable of removing excessive nutrients, up to 70% for NO3- N and NH4 +-N, reducing PO4 =-P fluctuation, and producing bioactive compounds. In the second treatment ponds, shrimp mortality started to occur in day 28 and most died by day 54 after stocking due to white spot disease outbreak. Mass mortality took place 54 days after stocking in two out of six of the first treatment ponds

    Writing Electronic Devices on Paper with Carbon Nanotube Ink

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    The normal paper used in any printer is among the cheapest flexible organic materials that exist. We demonstrate that we can print on paper high-frequency circuits tunable with an applied dc voltage. This is possible with the help of an ink containing functionalized carbon nanotubes and water. After the water is evaporated from the paper, the nanotubes remain steadily imprinted on paper, showing a semiconducting behaviour and tunable electrical properties

    New "Square Root" Model of Lepton Family Cyclic Symmetry

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    Following the newly formulated notion of form invariance of the neutrino mass matrix, a complete model of leptons is constructed. It is based on a specific unitary 3 X 3 matrix U in family space, such that U^2 is the simple discrete symmetry nu_e to -nu_e, nu_mu to nu_tau. Thus U also generates the cyclic group Z_4. The charged-lepton mass matrix is nearly diagonal while the neutrino mass matrix is of the form suitable for explaining maximal (large) mixing in atmospheric (solar) neutrino oscillations in the context of three nearly degenerate neutrino masses. Observable lepton flavor violation is predicted. Quarks may be treated in the same way as the charged leptons.Comment: 10 pages, no figur

    Brane-Bulk energy exchange and agegraphic dark energy

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    We consider the agegraphic models of dark energy in a braneworld scenario with brane-bulk energy exchange. We assume that the adiabatic equation for the dark matter is satisfied while it is violated for the agegraphic dark energy due to the energy exchange between the brane and the bulk. Our study shows that with the brane-bulk interaction, the equation of state parameter of agegraphic dark energy on the brane, wDw_D, can have a transition from normal state where wD>1w_D >-1 to the phantom regime where wD<1w_D <-1 , while the effective equation of state for dark energy always satisfies wDeff1w^{\mathrm{eff}}_D\geq-1.Comment: 13 pages, to appear in IJMP
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