Büchwald-Hartwig reaction applied to synthesis of new luminescent liquid crystal triarylamines derived from isoxazoles

© 2015 Taylor & Francis Group, LLC. The present work describes the synthesis and characterization of novel series of triarylamines isoxazoles (TAA) addressed to the organic photovoltaic materials. Diarylisoxazoles were synthesized by sequential [3+2] 1,3-dipolar cycloaddition reaction between arylnitrile oxides and selected arylalkenes followed by MnO2-oxidation. Isoxazoles were coupled to diarylamines by Büchwald-Hartwig reaction to afford desired compounds 6a-k. Some TAA display liquid-crystalline behaviour and UV-Vis absorption and fluorescence emission were analysed for all samples of TAA 6a-k

Perspectives on Quantum Gravity Phenomenology

The idea that quantum gravity manifestations would be associated with a violation of Lorentz invariance is very strongly bounded and faces serious theoretical challenges. Other related ideas seem to be drowning in interpretational quagmires. This leads us to consider alternative lines of thought for such phenomenological search. We discuss the underlying viewpoints and briefly mention their possible connections with other current theoretical ideas.Comment: Latex, 23 page

Can aerosols be trapped in open flows?

The fate of aerosols in open flows is relevant in a variety of physical contexts. Previous results are consistent with the assumption that such finite-size particles always escape in open chaotic advection. Here we show that a different behavior is possible. We analyze the dynamics of aerosols both in the absence and presence of gravitational effects, and both when the dynamics of the fluid particles is hyperbolic and nonhyperbolic. Permanent trapping of aerosols much heavier than the advecting fluid is shown to occur in all these cases. This phenomenon is determined by the occurrence of multiple vortices in the flow and is predicted to happen for realistic particle-fluid density ratios.Comment: Animation available at http://www.pks.mpg.de/~rdvilela/leapfrogging.htm

Glued laminated timber beams reinforced with sisal fibres

The current appeal for sustainable building materials has expanded the use of timber in construction. However, due to timber be a raw material, natural defects are present, what reduce its strength capacity and cause, in particular, brittle failures in the tensile region of timber beams. In order to increase the mechanical properties of these beams, fibre reinforcement can be applied. In this context, natural fibres, such as Sisal fibres, already used in various fields of construction, are an alternative for reinforcement of timber structural elements, by taking into account their adequate mechanical properties and, in special, for low-mechanical resistance wood species, such as Pinu sp, a species used widely in timber construction. This paper deals with an experimental analysis glued laminated timber beams (Glulam) of Pinus sp species, reinforced by Sisal fibres. Bending tests were performed on six beams with the following dimensions, 53 mm-width by 180 mm-height by 3000 mm-length, which were prepared with eight lamellas by 8 mm-thickness. These beams were reinforced with Sisal strips that were glued by Epoxy adhesive on the bottom part of these beams. In addition, comparisons of result with non-reinforced Glulam were carried out. From the analyses of the experimental results, a decrease of 20 to 30% for the normal stresses, 5 to 10% for the shear stresses and 8 to 12 % for the displacements in relation to non-reinforced beams were verified8439039

Soft singularity and the fundamental length

It is shown that some regular solutions in 5D Kaluza-Klein gravity may have interesting properties if one from the parameters is in the Planck region. In this case the Kretschman metric invariant runs up to a maximal reachable value in nature, i.e. practically the metric becomes singular. This observation allows us to suppose that in this situation the problems with such soft singularity will be much easier resolved in the future quantum gravity then by the situation with the ordinary hard singularity (Reissner-Nordstr\"om singularity, for example). It is supposed that the analogous consideration can be applied for the avoiding the hard singularities connected with the gauge charges.Comment: 5 page

On the nonlinearity interpretation of q- and f-deformation and some applications

q-oscillators are associated to the simplest non-commutative example of Hopf algebra and may be considered to be the basic building blocks for the symmetry algebras of completely integrable theories. They may also be interpreted as a special type of spectral nonlinearity, which may be generalized to a wider class of f-oscillator algebras. In the framework of this nonlinear interpretation, we discuss the structure of the stochastic process associated to q-deformation, the role of the q-oscillator as a spectrum-generating algebra for fast growing point spectrum, the deformation of fermion operators in solid-state models and the charge-dependent mass of excitations in f-deformed relativistic quantum fields.Comment: 11 pages Late