Ariana de Campos

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To present day, the maximum magnetocaloric effect (MCE) at room temperature for a magnetic field change of 5 T is 40 J/(kg K) for MnAs. In this Letter we present colossal MCE measurements on MnAs under pressure, reaching values up to 267 J/(kg K), far greater than the magnetic limit arising from the assumption of magnetic field independence of the lattice(More)
Through a mean field theory, an elastic free energy describing the nonuniform elastic textures observed in nematic elastomers, is proposed. To construct it, an order parameter that describes the nematic-isotropic phase transition through the change of the elastic properties of the strain tensor at the transition point is introduced. The resulting elastic(More)
A commercial available Schottky barrier silicon photodiode is coupled to a Gas Proportional Scintillation Counter through a quartz window and is used as an alpha particle room temperature detector. An Ar+N2(2%) gas mixture at 1470 Thrr is used. Resolutions of 3.2% are achieved. A discussion of the results obtained is presented and future improvements(More)
In this work, the effective viscosity of the cholesteryl myristate and cholesteryl nonanoate liquid crystals is studied as a function of temperature at the region of their cholesteric-to-isotropic phase transition, where blue phases are found. Using a change of scale it is shown that the viscosity peaks that characterize these phase transitions are shape(More)
The magnetocaloric effect (MCE) is the basis for magnetic refrigeration, and can replace conventional gas compression technology due to its superior efficiency and environment friendliness. MCE materials must exhibit a large temperature variation in response to an adiabatic magnetic-field variation and a large isothermal entropic effect is also expected. In(More)
In this paper, the affine connection approach [D. Baalss and S. Hess, Phys. Rev. Lett. 57, 86 (1986)] will be defined in terms of a local transformation. Accordingly, the macroscopic anisotropy of the nematic medium will be conceived as resulting from a local transformation where, at each point of the sample, the spherical molecules of an idealized(More)
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