Spectrum and Eigenfunctions of the Lattice Hyperbolic Ruijsenaars–Schneider System with Exponential Morse Term

We place the hyperbolic quantum Ruijsenaars–Schneider system with an exponential Morse term on a lattice and diagonalize the resulting n-particle model by means of multivariate continuous dual q-Hahn polynomials that arise as a parameter reduction of the Macdonald–Koornwinder polynomials. This allows to compute the n-particle scattering operator, to identify the bispectral dual system, and to confirm the quantum integrability in a Hilbert space setup.     

Are physico-chemical soil characteristics key factors to select the polycyclic aromatic hydrocarbons extraction procedure?

The aim of this work was to assess the impact of soil characteristics and constituents in the total extraction of hydrophobic organic pollutants, such as polycyclic aromatic hydrocarbons (PAH), in real polluted soil samples from different sources. Soil samples were obtained from a wood creosote treatment plant, in the vicinity of a metallurgy industry and coal thermal power stations. Soils showed a wide diversity of textures, organic matter (OM) and CaCO₃ content, pH and electrical conductivity to assure representativeness of multiple situations. Two extraction procedures with soft (solid–liquid extraction, SLE) and intense (pressurised liquid extraction, PLE) extraction power were used to determine the total concentration of PAH in soils. Results obtained showed that soil properties affect the effectiveness of the extraction procedures tested. The validation of PAH extraction procedure with a reference soil did not confirm that the procedure was adequate for all kinds of soil. Results showed that OM content and clay were the main soil characteristics that should be taken into account to select the most adequate PAH extraction procedure for any given polluted soil.     

Reactions of Sn(NMe2)2 with MPHCy: the effects of alkali metal phosphide coupling (Cy=cyclohexyl; M=Li, Na, K, Rb)

The reactions of the SnII base Sn(NMe2)2 with CyPHM (Cy=cyclohexyl) produce a range of products, depending primarily on the alkali metal (M) involved. The 1:3 stoichiometric reaction of Sn(NMe2)2 with CyPHNa in the presence of the Lewis base donor PMDETA (PMDETA=(Me2NCH2CH2)2NMe) gives [(NaPMDETA)2{Sn(mu-PCy)}3] (3), containing the electron-deficient [{Sn(mu-PCy)}3]2- dianion. Natural bond order (NBO) and electron localisation function (ELF) calculations show that this species is described most appropriately by a two-electron, three-centre Sn3 bonding model. Evidence that 3 results from phosphide coupling is provided by the 1:1 reaction of Sn(NMe2)2 with CyPHNa in the presence of PMDETA, which gives 3 and trace amounts of (NaPMDETA)2[{Sn(mu-PCy)}2(mu-PCyPCy)] (4) (containing one PCyPCy2- dianion). Greater extents of phosphide coupling are observed as the size of the Group 1 metal is increased. Thus, the 1:3 reaction of Sn(NMe2)2 with CyPHK in THF gives the co-crystalline product {(K2 THF)2[{Sn(mu-PCyPCy)}2(mu-PCy)]}0.9{(K2 THF)2[{Sn(mu-PCy)}2(mu-PCyPCy)]}0.1 (5) (containing [{Sn(mu-PCyPCy)}2(mu-PCy)]2- and [{Sn(mu-PCy)}2(mu-PCyPCy)]2- dianions), whereas the analogous reaction of Sn(NMe2)2 with RbPHCy gives [RbPMDETA{(CyP)3SnP(H)Cy}] (6) (containing a cyclic {(CyP)3Sn} unit).     

Rare earth arenedisulfonate metal-organic frameworks: an approach toward polyhedral diversity and variety of functional compounds

Eight 2D and 3D metal-organic framework (MOF) rare earth naphthalenedisulfonates have been obtained. The different geometry of the naphthalenedisulfonic acids used as connectors [(1,5-NDS) and (2,6-NDS)] gives rise to the three new structure types. In Ln(OH)(1,5-NDS)H2O, LnPF-1 (lanthanide polymeric framework; Ln=La, Nd, Pr, Sm and Eu), the lanthanide ion is octacoordinated. Its 3D structure is formed by (Ln2O14)-S-(Ln2O14) infinite chains, connected through complete NDS connectors. LnPF-2 (Ln=Nd), with the same empirical formula as the former, and the lanthanide in octa- and nonacoordination, owns an arrangement of sulfonate bridges and neodymium polyhedra that gives rise to a 2D structure. [Ln5(2,6-NDS)3(OH)9(H2O)4](H2O)2, LnPF-3 (Ln=Nd, Eu), demonstrates that it is possible to obtain a 3D structure with (2,6-NDS), when a greater Ln/connector ratio is employed. It is worth pointing out the existence, in this latter family of compounds, of a mu5-OH group, whose hydrogen atom is very close to one-sixth Ln atom (distance Ln...H=2.09 A). The materials, with high thermal stability, act as active and selective bifunctional heterogeneous catalysts in oxidation of linalool yielding cyclic hydroxy ethers. The absence of any 3D Nd-Nd magnetic interaction is explained due to the inner nature of 4f orbitals of Nd3+, which do not favor the magnetic exchange. The influence of the polymeric frame matrix results in a better photoluminescence efficiency for NdPF-1.     

Importance of catalyst–photoabsorber interface design configuration on the performance of Mo-doped BiVO4 water splitting photoanodes

Photoelectrochemical water splitting is mostly impeded by the slow kinetics of the oxygen evolution reaction. The construction of photoanodes that appreciably enhance the efficiency of this process is of vital technological importance towards solar fuel synthesis. In this work, Mo-modified BiVO₄ (Mo:BiVO₄), a promising water splitting photoanode, was modified with various oxygen evolution catalysts in two distinct configurations, with the catalysts either deposited on the surface of Mo:BiVO₄ or embedded inside a Mo:BiVO₄ film. The investigated catalysts included monometallic, bimetallic, and trimetallic oxides with spinel and layered structures, and nickel boride (Ni_xB). In order to follow the influence of the incorporated catalysts and their respective properties, as well as the photoanode architecture on photoelectrochemical water oxidation, the fabricated photoanodes were characterised for their optical, morphological, and structural properties, photoelectrocatalytic activity with respect to evolved oxygen, and recombination rates of the photogenerated charge carriers. The architecture of the catalyst-modified Mo:BiVO₄ photoanode was found to play a more decisive role than the nature of the catalyst on the performance of the photoanode in photoelectrocatalytic water oxidation. Differences in the photoelectrocatalytic activity of the various catalyst-modified Mo:BiVO₄ photoanodes are attributed to the electronic structure of the materials revealed through differences in the Fermi energy levels. This work thus expands on the current knowledge towards the design of future practical photoanodes for photoelectrocatalytic water oxidation.

     

Star-shaped molecules as functional materials based on 1,3,5-benzenetriesters with pendant 1,3,4-thiadiazole groups: liquid crystals,optical, solvatofluorochromic and electrochemical properties

New molecular structures consisting of a C₃ star-shaped 1,3,5-benzene unit as a central core, and three pendant 2-phenyl-5-(di-, and/or tri-n-alkoxyphenyl)-1,3,4-thiadiazole arms, containing ester connecting groups, variable number and positions of linear alkoxy chains (2an, 2b10 and 2c10) were synthesised. The mesomorphic properties were studied by differential scanning calorimetry, polarised optical microscopy and X-ray diffraction. Compounds bearing nine peripheral n-decyloxy chains (2a10) and nine peripheral n-dodecyloxy chains (2a12) form an enantiotropic hexagonal columnar phase, whereas their homologue 2a14, bearing nine peripheral n-tetradecyloxy chains, does not show mesomorphic behaviour. Compound bearing six peripheral n-decyloxy chains, which are in the 3,4-positions of the terminal benzene rings (2c10) does not show mesomorphic properties, whereas its analogous compound 2b10, bearing six n-decyloxy chains in the 3,5-positions of the terminal benzene rings, is liquid. The electrochemical behaviour of the liquid crystalline compounds 2a10 and 2a12 was investigated by cyclic voltammetry which revealed the hole-blocker character of these compounds. The ultraviolet–visible absorption and emission properties of the compounds 2an, 2b10 and 2c10 have been investigated. Photophysical studies were carried out in solution and in film. In addition, solvatofluorochromism studies were performed with compound 2a12 as a representative member of the compounds of series 2.     

Optimization of lignin recovery from sugarcane bagasse using ionic liquid aided pretreatment

Ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]oAc) was employed for the pretreatment of sugarcane bagasse (SCB) and extraction of lignin, a potentially valuable by-product of the biofuel industry. Response surface methodology based on central composite design was exploited and thereby an empirical model, exhibiting a coefficient of determination, R², of 0.9890, was established to optimize lignin recovery. In particular, a maximum lignin yield, equal to 90.1%, was calculated at the optimal pretreatment conditions, namely time: 120 min, temperature: 140 °C, and ionic liquid to bagasse ratio equal to 20:1 (wt/wt). The presence of guaiacyl and syringyl rings in lignin was confirmed by Fourier transform infrared spectroscopy (FTIR); whereas UV–Vis spectrophotometry showed that both p-coumaric acid and ferulic acid were contained in the lignin. Thermal analysis indicated a maximum decomposition rate of 2%/°C at 265 °C while Gel permeation chromatography analysis revealed that the molecular weight (M_w) of recovered lignin was equal to 1769 g/mol. Comparison of FTIR spectra of pretreated and untreated bagasse showed a negligible presence of lignin in the pretreated samples. Maximum delignification of bagasse after pretreatment was thus ensured. Thermal stability of the ionic liquid towards recyclability was proven by thermogravimetric analysis. The present study established adequate performance of neat and recycled ([EMIM]oAc) with regard to lignin recovery from SCB.     

Semi‐strong and strong solutions for variable density asymmetric fluids in unbounded domains

We establish the existence of local in time semi‐strong solutions and global in time strong solutions for the system of equations describing flows of viscous and incompressible asymmetric fluids with variable density in general three‐dimensional domains with boundary uniformly of class C³. Under suitable assumptions, uniqueness of local semi‐strong solutions is also proved. Copyright © 2016 John Wiley & Sons, Ltd.     

A solution for the local plane strain problems using elliptic integrals of Cauchy type

We consider a parallel fiber‐reinforced periodic elastic composite that present an imperfect contact of spring type between the fiber and the matrix. We use the elliptic integral of Cauchy type for solving the plane strain local problems that arise from the asymptotic homogenization method. Several general conditions are assumed, which include that the fibers are disposed of arbitrary manner in the local cell, that all fibers present contact perfect with different constants of imperfection, and that their cross section is a smooth closed arbitrary curve. We find that there are infinity solutions for these problems, and we find relations between these solutions and effective coefficients of the composite. Finally, we obtain analytic formulae for the circular fiber case and show some numerical examples. Copyright © 2016 John Wiley & Sons, Ltd.     

Higher cohomology of parabolic actions on certain homogeneous spaces

We show that for a parabolic R ^d -action on PSL(2,R) ^d /Γ, the cohomologies in degrees 1 through d ? 1 trivialize, and we give the obstructions to solving the degree-d coboundary equation, along with bounds on Sobolev norms of primitives. In previous papers, we have established these results for certain Anosov systems. This work extends the methods of those papers to systems that are not Anosov. The main new idea is defining special elements of representation spaces that allow us to modify the arguments from the previous papers. We discuss how to generalize this strategy to R ^d -systems coming from a product of Lie groups, as in the systems analyzed here.