Synthesis of Crosslinked Sulfonated Poly(phenylene sulfide sulfone nitrile) for Direct Methanol Fuel Cell Applications

With a view towards direct methanol fuel cell applications, novel sulfonated poly(phenylene sulfide sulfone nitrile) (sPPSSfN) has been prepared and subsequently crosslinked by a Friedel‐Craft reaction using 4,4′‐oxybis(benzoic acid) as a crosslinker to achieve lower water swelling and lower methanol permeability. The dimensional change of SPPSSfN40 is 43.7% in 90 °C liquid water but that of the crosslinked membrane, XsPPSSfN40, is 23.3% while maintaining proton conductivity at 0.22 S · cm⁻¹. These results show that the Friedel‐Craft crosslinking of the novel sPPSSfN membrane effectively reduces water uptake and the degree of swelling while improving the dimensional stability and maintaining high proton conductivity.

     

Fe-MCM-41 with highly ordered mesoporous structure and high Fe content: synthesis and application in heterogeneous catalytic wet oxidation of phenol

Raman spectroscopy has been successfully employed in order to investigate the formation of β-cyclodextrin host–guest inclusion molecular complexes with several different azo-dye structures. The Raman pattern of the carbohydrate framework results negligible when neared to the magnificent intensity of the highly polarisable guest systems and a complete and feasible comparison of the spectral features between the free and the complexed situation of the guest molecule is allowed. In general, with respect to the free guest state, it was found within the complex that a hampering of Raman intensity displays, accompanied by a levelling directed variation of the relative peak intensities, and peculiar Raman peak broadening with shifts occur, relatable to the host–guest settling of inclusive intermolecular interactions. Supportively to the other commonly established characterising methods, or in valid alternative, Raman technique has proved astoundingly useful under the perspective of the diagnostic evaluation of cyclodextrin host–guest molecular inclusion for azo-dyes and, more generally, for a highly polarisable guest structure. It features sample non-destructivity, handiness, fastness and sensitive reproducibility, occasionally providing useful suggestions about the complexation topology.     

The lattice of integer partitions and its infinite extension

In this paper, we use a simple discrete dynamical model to study integer partitions and their lattice. The set of reachable configurations of the model, with the order induced by the transition rule defined on it, is the lattice of all partitions of a positive integer, equipped with a dominance ordering. We first explain how this lattice can be constructed by an algorithm in linear time with respect to its size by showing that it has a self-similar structure. Then, we define a natural extension of the model to infinity, which we compare with the Young lattice. Using a self-similar tree, we obtain an encoding of the obtained lattice which makes it possible to enumerate easily and efficiently all the partitions of a given integer. This approach also gives a recursive formula for the number of partitions of an integer, and some informations on special sets of partitions, such as length bounded partitions.     

On the multiplicity and the Cohen-Macaulayness of fiber cones of graded algebras

Let A be a Noetherian local ring with the maximal ideal m and an m-primary ideal J. Let S=?_n≥0S_n be a finitely generated standard graded algebra over A. Set S⁺=?_n>0S_n. Denote by F_J(S)=?_n≥0→(S_n/JS_n) the fiber cone of S with respect to J. The paper characterizes the multiplicity and the Cohen-Macaulayness of F_J(S) in terms of minimal reductions of S⁺.     

Structural and compositional heterogeneities in liquid aluminosilicate: insight from a grain structure model

Network structure as well as structural and compositional heterogeneities in aluminosilicate (Al₂O₃-2SiO₂) under compression is investigated by analysis and visualization of simulation data. Structural and compositional heterogeneities are clarified through analysis of topology structure and size distribution of TO _x -clusters (T = Si, Al; x = 3, 4, 5, 6) as well as OT _y -clusters (y = 2, 3, 4). The TO _x -cluster can be considered as TO _x -grains. It appears that the structure of aluminosilicate is the mixture of TO _x -grains with a different short-range order structure and this is the origin of structural heterogeneity. Regarding their composition, the OSi _y - and OAl _y -clusters can be considered as silica- and alumina-grains respectively, and the structure of aluminosilicate can thus be considered to be formed from silica- and alumina-grains. This results in compositional heterogeneity. Moreover, the degree of polymerization and polyamorphism as well as dynamic heterogeneity is also discussed in detail.     

Infrared spectroscopy of goethite dehydroxylation: III. FT-IR microscopy of in situ study of the thermal transformation of goethite to hematite

Fourier transform infrared microscopy has been used to investigate in situ dehydroxylation of goethite to form hematite. The characterisation was based on the behaviour of hydroxyl units, which were observed in the hydroxyl stretching and hydroxyl deformation and water bending regions, and the Fe-O vibrations of the newly formed hematite during the thermal dehydroxylation process. Two hydroxyl stretching modes (v1 and v2), and three bending (V(bending-1, 2, 3)) and two deformation (V(deformation-1, 2)) modes were observed for goethite. The characteristic vibration at 916 cm(-1) was observed together with the residuals of the v1 and v2 bands in hematite spectrum. The structural transformation between goethite and hematite through thermal dehydroxylation was interpreted in order to provide criteria that can be used for the characterisation of thermally activated bauxite and their conversion to activated alumina phases.     

A polar corundum oxide displaying weak ferromagnetism at room temperature

Combining long-range magnetic order with polarity in the same structure is a prerequisite for the design of (magnetoelectric) multiferroic materials. There are now several demonstrated strategies to achieve this goal, but retaining magnetic order above room temperature remains a difficult target. Iron oxides in the +3 oxidation state have high magnetic ordering temperatures due to the size of the coupled moments. Here we prepare and characterize ScFeO(3) (SFO), which under pressure and in strain-stabilized thin films adopts a polar variant of the corundum structure, one of the archetypal binary oxide structures. Polar corundum ScFeO(3) has a weak ferromagnetic ground state below 356 K-this is in contrast to the purely antiferromagnetic ground state adopted by the well-studied ferroelectric BiFeO(3).     

A New Invariant of Quadratic Lie Algebras

We define a new invariant of quadratic Lie algebras and give a complete study and classification of singular quadratic Lie algebras, i.e. those for which the invariant does not vanish. The classification is related to O(n)-adjoint orbits in $\mathfrak{o}(n)$ .