Lanthanide-doped luminescent ionogels

Ionogels are solid oxide host networks con. ning at a meso-scale ionic liquids, and retaining their liquid nature. Ionogels were obtained by dissolving lanthanide(III) complexes in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [C(6)mim][Tf2N], followed by confinement of the lanthanide-doped ionic liquid mixtures in the pores of a nano-porous silica network. [C(6)mim][Ln(tta)(4)], where tta is 2-thenoyltrifluoroacetonate and Ln = Nd, Sm, Eu, Ho, Er, Yb, and [choline](3)[Tb(dpa)(3)], where dpa = pyridine-2,6-dicarboxylate (dipicolinate), were chosen as the lanthanide complexes. The ionogels are luminescent, ion-conductive inorganic-organic hybrid materials. Depending on the lanthanide(III) ion, emission in the visible or the near-infrared regions of the electromagnetic spectrum was observed. The work presented herein highlights that the confinement did not disturb the first coordination sphere of the lanthanide ions and also showed the excellent luminescence performance of the lanthanide tetrakis beta-diketonate complexes. The crystal structures of the complexes [C(6)mim][Yb(tta)(4)] and [choline](3)[Tb(dpa)(3)] are reported.

The unit ball of the complex P(3H)

Let H be a two-dimensional complex Hilbert space and P(3H) the space of 3-homogeneous polynomials on H. We give a characterization of the extreme points of its unit ball, P(3H), from which we deduce that the unit sphere of P(3H) is the disjoint union of the sets of its extreme and smooth points. We also show that an extreme point of P(3H) remains extreme as considered as an element of L(3H). Finally we make a few remarks about the geometry of the unit ball of the predual of P(3H) and give a characterization of its smooth points.

The Postmodern Non-city in Miquel de Palol’s "El Jardí del Set Crepuscles"

El Jardí del Set Crepuscles –primera novela del escritor y arquitecto catalán Miquel de Palol– nos brinda la oportunidad de reflexionar acerca de la metamorfosis experimentada por la ciudad occidental a principios de los años setenta del siglo pasado. De acuerdo con autores como Henri Lefebvre, David Harvey, Giandomenico Amendola o Edward Soja, el surgimiento de la ciudad posmoderna en el marco de la transición hacia el modo de acumulación postfordista se presenta acompañado por un debilitamiento del tejido social y de la esfera pública y cívica. El objetivo del presente artículo es ilustrar las estrategias narrativas y retóricas con las que el texto de Miquel de Palol representa, y analiza, dicho fenómeno.

‘Doing it with men’: feminist research practice and patriarchal inheritance practices in Welsh family farming

Internationally, the gender relations of the family farming ‘way of life’ have beenshown to be stubbornly persistent in their adherence to patriarchal inheritancepractices. This article demonstrates how such ‘agri-cultural’ practices are situated bothwithin the subjective sphere of farming individuals’ and within global agri-economics,bringing new challenges to patrilineal farm survival. It is suggested here that the recenttendency for post-structuralist theorisation in rural studies has underestimated theexistence and impact of patrilineal patterns in family farming. Such patterns mean thatwomen are shown to largely occupy relational gender identities as the ‘helper’, whilstmen are strongly identified as the ‘farmer’. Drawing on repeated life-history interviewsconducted with farming men and women from Powys, Mid Wales, the aim of thisarticle is to generate debate as to the extent to which men can be brought into feministresearch practice in order to reveal patriarchy to a greater degree. The article begins bysituating the near-exclusion of men from feminist research practice within theoreticaldevelopments in feminist geography. This discussion also assists in deriving issues ofresearch methods, positionality and interpretive power which focus the integration ofempirical material in the methodological reflections provided in section three. In sectiontwo, the rationale for the epistemological stance taken in the research is provided. Thearticle provides an example of the successful integration of men into a feminist researchframe, suggests avenues for theoretical development and identifies future researchdirections which can be informed by ‘doing it with men’.

Keywords: epistemology; family farming; feminist res

El diagnóstico de la crisis de la cultura en España: del recorte público a la crisis sistémica

Desde su invención en los años cincuenta, la política cultural ha sido objeto de análisis y reflexión por parte de las ciencias sociales. No obstante, en España presenta una serie de características diferenciadoras frente a las democracias occidentales europeas como consecuencia del periodo franquista. Con la recuperación de la democracia España adquiere el paradigma dominante de una política cultural democrática basada en la libertad, el pluralismo y el derecho a la cultura. Sin embargo, tras décadas de gobiernos democráticos el diagnóstico de la política cultural en España presenta rasgos de crisis sistémica, además de los efectos de la crisis global financiera de inicios del siglo XXI. En este contexto, los autores diagnostican, aplicando la metodología Delphi y recurriendo a fuentes secundarias, un conjunto de discursos sociales y narrativas que parecen funcionar como recursos cognitivos solucionistas en la esfera artística y cultural y que no están exentos de contradicciones y aporías, fruto de su contraste empírico.

Near-infrared photoluminescence of lanthanide complexes containing the hemicyanine chromophore

The near-infrared luminescence properties of three (E)-N-hexadecyl-N',N'-dimethylamino-stilbazolium tetrakis(1-phenyl-3-methyl-4-benzoyl-5-pyrazolonato) lanthanide(III) complexes are described. These three complexes, containing trivalent neodymium, erbium and ytterbium, respectively, show near-infrared luminescence in acetonitrile solution upon UV irradiation. Luminescence decay times have been measured. The complexes consist of a positively charged hemicyanine chromophore with a long alkyl chain and a tetrakis(pyrazolonato) lanthanide(III) anion. Because of the absence of an alpha-hydrogen atom in the pyrazolonato ligands, and because of the saturation of the coordination sphere by four bidentate ligands, the luminescence properties are enhanced when compared to, e.g. quinolinate complexes. (C) 2007 Elsevier Ltd. All rights reserved.

Rare-earth complexes of ferrocene-containing ligands: Visible-light excitable luminescent materials

The ferrocene-derivatives bis(ferrocenyl-ethynyl)-1,10-phenanthroline (Fc(2)phen) and ferrocenoyltrifluoroacetone (Hfta) have been used to synthesize ferrocene-containing rare-earth beta-diketonate complexes. The complexes [Ln(tta)(3)(Fc(2)phen)] and [Ln(fta)(3)(phen)] (where Ln = La, Nd, Eu, Yb) show structural similarities to the tris(2-thenoyltrifluoroacetonate)(1,10-phenanthroline)lanthanide(III) complexes, [Ln(tta)(3)(phen)]. The coordination number of the lanthanide ion is 8, and the coordination sphere can be described as a distorted dodecahedron. However, the presence of the ferrocene moieties shifts the ligand absorption bands of the rare-earth complexes to longer wavelengths so that the complexes can be excited not only by ultraviolet radiation but also by visible light of wavelengths up to 420 nm. Red photoluminescence is observed for the europium(III) complexes and near-infrared photoluminescence for the neodymium(III) and ytterbium(III) complexes. The presence of the ferrocene groups makes the rare-earth complexes hydrophobic and well-soluble in apolar organic solvents.

The persistence of the HgCl2 molecule in five new compounds in the system (NH4)(w)HgxCly(H2O)(z) with w : x : y : z=1 : 5 : 11 : 0, 2 : 3 : 8 : 1, 4 : 3 : 10 : 2, 2 : 1 : 4 : 1, and 10 : 3 : 16 : 0

Five new compounds in the system (NH4)Cl/HgCl2/H2O have been obtained as colourless single crystals, (NH4)Hg5Cl11, (NH4)(2)Hg3Cl8(H2O), (NH4)(4)Hg3Cl10(H2O)(2), (NH4)(2)HgCl4(H2O), and (NH4)(10)Hg3Cl16. In all of these, as in HgCl2 itself, (almost) linear HgCl2 molecules persist with Hg-Cl distances varying from 229 to 236 pm. In (NH4)(10)Hg3Cl16 there are also tetrahedra [HgCl4] with d(Hg-Cl) = 247 pm present. If larger Hg-Cl distances (of up to 340 pm) are considered as belonging to the coordination sphere of Hg-II, the structures may be described as consisting of isolated octahedra and tetrahedra as in (NH4)(10)Hg3Cl16, edge-connected chains as in (NH4)(2)HgCl4(H2O), edge-connected chains and layers of octahedra as in (NH4)(4)Hg3Cl10(H2O)(2), corrugated layers of edge-connected octahedra as in (NH4)(2)Hg3Cl8(H2O), and, finally, a three-dimensional network of connected six- and seven-coordinate Hg-Cl polyhedra as in (NH4)Hg5Cl11. The water molecules are never attached to Hg-II. The (NH4)(+) cations, and sometimes Cl- anions, play a role for electroneutrality only.

Lanthanide(III) nitrobenzenesulfonates as new nitration catalysts: The role of the metal and of the counterion in the catalytic efficiency

Lanthanide(III) complexes of p-nitrobenzenesulfonic acid, Ln(p-NBSA)(3), m-nitrobenzenesulfonic acid, Ln(m-NBSA)(3), and 2,4-nitrobenzenesulfonic acid, Ln(2,4-NBSA)(3), were prepared, characterized and examined as catalyst for the nitration of benzene, toluene, xylenes, naphthalene, bromobenzene and chlorobenzene. The initial screening of the catalysts showed that lanthanum(III) complexes were more effective than the corresponding ytterbium(III) complexes, and that catalysts containing the bulky 2,4-NBSA ligand were less effective than the catalyst containing p-NBSA (nosylate) or m-NBSA ligands. Examination of a series of Ln(p-NBSA)(3) and Ln(m-NBSA)(3) catalysts revealed that there is a clear correlation between the ionic radii of the lanthanide(III) ions and the yields of nitration, with the lighter lanthanides being more effective. The X-ray single crystal structure of Yb(m-NBSA)(3).6H(2)O shows that two m-NBSA ligands are directly bound to the metal centre while the third ligand is not located in the first coordination sphere, but it is hydrogen bonded to one of the water molecules which is coordinated to ytterbium(III). NMR studies suggest that this structure is preserved under the conditions used in the nitration reaction. The structure of Yb(m-NBSA)(3) is markedly different from the structure of the well-known ytterbium(III) triflate catalyst. The coordination of the nitrobenzenesulfonate counterion to the lanthanide(III) ion suggests that steric effects might play an important role in determining the efficiency of these novel nitration catalysts. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).

Strong erbium luminescence in the near-infrared telecommunication window

A new type of near-infrared emitting rare-earth complex has been synthesised, consisting of three bis(perfluoroalkylsulfonyl)imide ligands and one 1,10-phenanthroline molecule. The chelate rings formed by the rare-earth ion and the bidentate ligands do not contain any carbon atoms and can hence be considered as 'inorganic' chelate rings. The absence of C-H stretching vibration modes in the first coordination sphere of the rare-earth ion and the presence of a light-harvesting moiety (1,10-phenanthroline) bound to the rare-earth ion result in a complex that can be efficiently excited and exhibits intense near-infrared luminescence. (C) 2004 Elsevier B.V. All rights reserved.

Two mercuric ammoniates: [Hg(NH3)(2)][HgCl3](2) and [Hg(NH3)(4)](ClO4)(2)

[Hg(NH3)(2)][HgCl3](2) (1) is obtained by saturating an equimolar solution of HgCl2 and NH4Cl with Hg(NH2)Cl at 75 degreesC. 1 crystallizes in the orthorhombic space group Pmna with a = 591.9(1) pm, b = 800.3(1) pm, c = 1243.3(4) pm, Z = 2. The structure consists of linear cations [Hg(NH3)(2)](2+) and T-shaped anions [HgCl3](-). The coordination sphere of mercury is

On the Uncoded BER Performance Bound of the IEEE 802.16d Channel

In this letter, the performance bound of the IEEE 802.16d channel is examined analytically in order to gain an insight into its theoretical potential. Different design strategies, such as orthogonal frequency division multiplexing (OFDM) and single-carrier frequency-domain equalization (SC-FDE), time-domain decision feedback equalization (DFE), and sphere decoder (SD) techniques are discussed and compared to the theoretical bound.

Laïcité is what Laïcité does: Rethinking the French cult controversy

France’s distinctive reaction towards “cults” is generally described as a result of laïcité’s consubstantial problems with religious diversity. The aim of this article is to present an alternative way of thinking about the French cult controversy and, ultimately, about the concept of “laïcité” as an explanatory framework for France’s response to religious diversity. It draws on empirical data to look at how notions such as “laïcité” and “cults” are used in official discourses and translated into administrative practice. This approach will underline that laïcité is not a driving force that predetermines a unilateral response to “cults”, but that laïcité is as laïcité does, in other words a highly claimed and contested value, reflecting divergent political and administrative approaches of the cult phenomenon. The framework “laïcité versus religious diversity” is also undermined by another crucial observation. While it sees the cult controversy as primarily a religious issue, it seems that the recent revitalisation of the combat against “cults” was made possible by its partial dissociation from the religious sphere and its extension to a wide range of practices and new areas.

Women in Ulster, 1600-1800

Some have entertained the belief that early modern Gaelic society conferred substantial rights on women. This could hardly be farther from the truth. In aristocratic Gaelic circles women were used ruthlessly as pawns in political alliances and other manoeuvres. The status of women at the lower levels of society also seems to have been low relative to men. While patriarchal relationships persisted after the Plantation of Ulster, they took new forms. Some women actually benefited in terms of property rights relative to men. Economic change in the eighteenth century, in particular the development of proto-industry, opened up opportunities for poorer women but it is notable that women did not feature at all in the public political sphere before 1800

Stability of dust lattice modes in the presence of charged dust grain polarization in plasmas

We discuss the effect of the attractive force associated with overlapping Debye spheres on the dispersion properties of the longitudinal and transverse dust lattice waves in strongly coupled dust crystals. The dust grain attraction is shown to contribute to a destabilization of the longitudinal dust lattice oscillations. The (optic-like) transverse mode dispersion law is shown to change. due to the Debye sphere dressing effect, from the known inverse-dispersive ("backward wave") form into a normal dispersive law (i.e. the group velocity changes sign). The stability of one-dimensionless bi-layers, consisting of (alternating) negatively and positively charged dust particles, is also discussed. The range of parameter values (mainly in terms of the lattice parameter kappa) where the above predictions are valid, are presented. (c) 2005 Elsevier B.V. All rights reserved.