Distinct high-T transitions in underdoped Ba1−x_{1-x}Kx_{x}Fe2_{2}As2_{2}

In contrast to the simultaneous structural and magnetic first order phase transition $T_{0}$ previously reported, our detailed investigation on an underdoped Ba$_{0.84}$K$_{0.16}$Fe$_{2}$As$_{2}$ single crystal unambiguously revealed that the transitions are not concomitant. The tetragonal ($\tau$: I4/mmm) - orthorhombic ($\vartheta$: Fmmm) structural transition occurs at $T_{S}\simeq$ 110 K, followed by an adjacent antiferromagnetic (AFM) transition at $T_{N}\simeq$ 102 K. Hysteresis and coexistence of the $\tau$ and $\vartheta$ phases over a finite temperature range observed in our NMR experiments confirm the first order character of the structural transition and provide evidence that both $T_{S}$ and $T_{N}$ are strongly correlated. Our data also show that superconductivity (SC) develops in the $\vartheta$ phase below $T_{c}$ = 20 K and coexists with long range AFM. This new observation, $T_{S}\neq T_{N}$, firmly establishes another similarity between the hole-doped BaFe$_{2}$As$_{2}$ via K substitution and the electron-doped iron-arsenide superconductors.Comment: 4 pages, 3 figure

Carrier-Concentration Dependence of the Pseudogap Ground State of Superconducting Bi2Sr2-xLaxCuO6+delta Revealed by 63,65Cu-Nuclear Magnetic Resonance in Very High Magnetic Fields

We report the results of the Knight shift by 63,65Cu-nuclear-magnetic resonance (NMR) measurements on single-layered copper-oxide Bi2Sr2-xLaxCuO6+delta conducted under very high magnetic fields up to 44 T. The magnetic field suppresses superconductivity completely and the pseudogap ground state is revealed. The 63Cu-NMR Knight shift shows that there remains a finite density of states (DOS) at the Fermi level in the zero-temperature limit, which indicates that the pseudogap ground state is a metallic state with a finite volume of Fermi surface. The residual DOS in the pseudogap ground state decreases with decreasing doping (increasing x) but remains quite large even at the vicinity of the magnetically ordered phase of x > 0.8, which suggests that the DOS plunges to zero upon approaching the Mott insulating phase.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let

velocidades mínimas de fluidización para semillas

En un trabajo anterior se observó que las velocidades mínimas de fluidización calculadas con la correlación de Wen y Yu2 están por debajo de los valores experimentales, aumentando esta desviación con el tamaño de las partículas; los autores concluyeron que esta desviación podría deberse a una caracterización inadecuada del tamaño de las partículas. En este trabajo se determinó la velocidad mínima de fluidización de partículas de origen agricola. Se comparó estos resultados con los obtenidos por Wen y Yu, empleando como diámetros representativos de particulas: diámetro medio geométrico de las aberturas de los tamices, diámetro basado en las dimensiones reales de las particulas y finalmente un diámetro equivalente basado en el volumen de las particulas. Los resultados mostraron que la desviación entre los valores experimentales y aquellos obtenidos con la ecuación de Wen y Y u son menores cuando se utiliza el diámetro equivalente basado en el volumen de las particulas

Luntiang Basura (Green Wastes): A Case Study of Three Filipino Ecopreneurs in Upcycling

Currently, the Philippines is facing the challenges of devastating disasters brought about by accelerated global warming that continuously fuel the unthinkable climate change problems. Pollution has been identified as one of the major contributors to global warming. In the light of this gargantuan problem, alternative business processes must be resorted to for humankind to continue our existence in this planet. This paper aims to show, by way of a case study, that engaging in upcycling business, a more creative and upscale recycling, can be financially rewarding, socially responsible and at the same time help protect the environment by impacting the zero-waste campaign in a major manner – i.e., helping solve the solid waste problem. The case study features three well-known, passionate ecopreneur/upcyclist subjects who concretize and attest to the sustainability of the environment by using wastes as primary raw material inputs in their production process, producing beautiful artisan goods that command high price in the market; thus, providing desired profitability forthe company. Keywords: ecopreneurs, green wastes, upcycling