Analysis of the fluid-bed stability of FCC catalysts at high temperature in terms of bed elasticity

The effect of temperature on the fluid-bed stability of three FCC catalysts has been analyzed through considerations on fluid-bed elasticity. Experimental findings on the effect of temperature on the elasticity modulus at minimum bubbling conditions, （E）mb, were analyzed using the hydrodynamic fluid-bed stability model developed by Foscolo and Gibilaro （1984） and adopting the interparticle-forces-based stability criterion developed by Mutsers and Rietema （1977）. For both models, the parameters which control changes in （E）mb with temperature are discussed, in order to establish the origin of the fluid-bed elasticity and analyze the ability of these models to discriminate between the relative importance of the hydrodynamic and interoarticle forces on the stability of the fluidized catalysts.     

Priestley duality and quotient lattices of many-valued algebras

Si mostra che la costruzione e le proprietà del funtore β (vedi [2]) della categoria delleMV-algebre alla categoria di reticoli distributivi limitati trova una naturale interpretazione nel contesto della dualità di Priestley [17], [18] e [19].     

Representations of MV‐algebras by sheaves

In this paper, inspired by methods of Bigard, Keimel, and Wolfenstein ([2]), we develop an approach to sheaf representations of MV‐algebras which combines two techniques for the representation of MV‐algebras devised by Filipoiu and Georgescu ([18]) and by Dubuc and Poveda ([16]). Following Davey approach ([12]), we use a subdirect representation of MV‐algebras that is based on local MV‐algebras. This allowed us to obtain: (a) a representation of any MV‐algebras as MV‐algebra of all global sections of a sheaf of local MV‐algebras on the spectruum of its prime ideals; (b) a representation of MV‐algebras, having the space of minimal prime ideals compact, as MV‐algebra of all global sections of a Hausdorff sheaf of MV‐chains on the space of minimal prime ideals, which is a Stone space; (c) an adjunction between the category of all MV‐algebras and the category of MV‐algebraic spaces, where an MV‐algebraic space is a pair (X, F), where X is a compact topological space and F is a sheaf of MV‐algebras with stalks that are local (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photocatalytic TiO2 coatings on limestone

The application of photocatalytic coatings on stone has been investigated for providing surface protection and self-cleaning properties. Sol–Gel and hydrothermal processes were used to synthesise TiO₂ colloidal suspensions and coatings with enhanced photocatalytic activity without any thermal curing of the coated stone. The stone was a porous limestone (apulian sedimentary carbonatic, calcite stone). Films and powders prepared from TiO₂ sols were studied using X-ray diffraction to evaluate the microstructure and identify rutile and anatase phases. A morphological and physical characterisation was carried out on coated and uncoated stone to establish the changes of appearance, colour, water absorption by capillarity and water vapour permeability. The photocatalytic activity of the coated surface was evaluated under UV irradiation through NO _x and organics degradation tests. The performances of the synthesised TiO₂ sols were compared with commercial TiO₂ suspension. Since the coating doesn’t need temperature treatments for activating the photocatalytic properties, the nano-crystalline hydrothermal TiO₂ sols seem good candidate for coating applications on stone that cannot be annealed after the coating application.     

Importance of unpaired electrons in organic electronics

The first observation that PBBTPD, a low bandgap, ambipolar conjugated donor-acceptor (DA) polymer based on benzobisthiadiazole (BBT), possesses an open-shell singlet ground state as well as a thermally accessible triplet state is described. Similarly, interesting electronic behavior in semiconducting organic DA oligomers based on BBT is also observed. Theoretical predictions have suggested that such behavior is due to the biradicaloid character of BBT and we provide experimental evidence indicating that these predictions are correct. Furthermore, the open shell character strengthens as the conjugation length increases, as observed in the BBT-based polymer, PBBTPD. We show that this biradicaloid structure is observed in each BBT moiety along the chain and that therefore PBBTPD is in fact a polyradicaloid. This observation will most likely aid in the development of better n-type polymeric acceptors for organic semiconductor applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 287–293