Tunable topographical cellulose matrices for electro-optical liquid crystal cells

In this work we have used acetoxypropylcellulose (APC) to produce free standing solid films (∼60 μm) that were used for assembling electro-optical devices. Thin films were obtained from concentrated lyotropic solutions of cellulose derivatives. Induced by the cast and shearing preparation conditions wrinkles and band textures can be observed in their free-surface plane. In order to eliminate and control these textures we used a process similar to that introducted in literature [1] which consists of storing the films in the same solvent-vapour atmosphere as the solution system. Lyotropic APC liquid crystalline solutions in dymethylacetamide (DMA) with crosslinker were prepared, thin films were obtained by using a shear/casting technique and stored in the solvent-vapour atmosphere until a planar structure was achieved. The dried crosslinked films were analyzed by optical polarised microscopy (POM) and scanning electron microscopy (SEM). The films with different topographies were used to produce optical cells composed by the cellulose derivative film covered on both free surfaces by a layer of the nematic liquid crystal E7 and placed between two transparent conducting substrates. The electro-optical properties of these cells were obtained.     

Radial solutions for a Dirichlet problem in a ball

The Ambrosetti-Prodi boundary value problem with an asymptotically linear nonlinearity is considered. Under general conditions on the nonlinearity it is shown that there exist positive and negative solutions. In the case when the domain is a ball in Rⁿ and the nonlinearity “crosses” the first n eigenvalues, corresponding to radial eigenfunctions, it is proved that there are at least n + 1 radial solution.     

Denaturation of a Recombinant Cutinase from Fusarium solani in AOT-iso-Octane Reverse Micelles: a Steady-State Fluorescence Study

Abstract— Near UV absorbance and fluorescence spectroscopy show conformational changes of a recombinant cutinase from Fusarium solani incorporated in sodium-di-2-ethylhexyl sulfosuccinate (AOT)-iso-octane reversed micelles with W₀= [H₂O]/[AOT] = 20. Excitation spectra were used to decompose cutinase absorbance in its Trp and Tyr components, showing that the latter absorb red-shifted in the native cutinase in aqueous solution as compared to free Tyr, whereas in reverse micelles and denatured cutinase no shift is detected. Emission maxima variations (λ_max 303, 311 and 335 nm, respectively in aqueous, reverse micelles and thermally denatured cutinase) reflect progressive changes in the micropolarity of the environment and exposure of Trp residues at the protein surface. The encapsulation of cutinase in AOT-iso-octane reversed micelles induces a time-dependent denaturation measured by fluorescence intensity changes at 330 nm, which match the profile of enzyme activity loss in this media.     

On codimension one submersions of euclidean spaces

Summary It is shown that when (n–1) first integrals of a dynamical systemX inR ⁿ are known (and they are independent at any point ofR ⁿ ) then one can have (n3) that certain orbits ofX are diffeomorphic to circles and others diffeomorphic to straight-lines. An analytical criterion is also given (involving only the first derivatives of the first integrals) in order thatall the orbits be diffeomorphic to straight lines. Therefore the criterion is sufficient in order to avoid the presence of geometrical chaos among the orbits of the dynamical systemX.     

The computer and the heat engine

Brillouin sees order as generated by tapping negentropy sources existing upstream, while Prigogine sees it as generated by dumping entropy downstream. Joining both ideas yields a picture of the computer closely paralleling that of Carnot's heat engine. The difference is that the one delivers information and the other, work. In either case the irretrievable (that is, by definition) loss occurs at the last step. Bennett and Landauer very rightly emphasize this, but their fixation on the condenser blinds them to the necessity of the furnace; thus they are led to believe in the possibility of perpetual duplication of the second kind, which Brillouin explicitly denies.     

Superparamagnetism in primitive meteorites

The meteorites called carbonaceous chondrites are the least altered samples we have of the material which formed our solar system. Using⁵⁷Fe Mössbauer spectroscopy we show that the carbonaceous chondrite Murchison contains a compound exhibiting superparamagnetic relaxation below 80 K.     

Universal coverings of PL-manifolds via coloured graphs

Summary By means of techniques and results concerning maps on surfaces [JS] and edge-coloured graphs representing PL-manifolds [FGG], we prove the existence of an infinite ball complexP(n), n > 1, such thatevery orientable PL-manifold of dimension n is a quotient of |P(n)| by the action of a finite index subgroup of a Fuchsian group with signature ,with h(2) = h(3) = 4 and h(n) = 2, for n > 3. The core of the proof is that all orientable PL-manifolds of dimensionn can be represented by edge-coloured graphs which are quotients of a universal graph, only depending onn.