185 research outputs found
A Lewis acid catalytic core sandwiched by inorganic polyoxoanion caps: selective H2O2-based oxidations with [AlIII4(H2O)10(β-XW9O33H)2]6− (X = AsIII, SbIII)
No full textThe Al-III-containing polyanions [Al-4(III)(H2O)(10)(beta-XW9O33H)(2)](4-) with X=As-III (1) and Sb-III (2) feature four aluminum(III) centers sandwiched by two trivacant (beta-XW9O33) Keggin units, and trigger peroxide catalysis as well as substrate coordination via multiple Lewis acid site interactions
Photocatalytic Water Oxidation by a Mixed-Valent (Mn3MnO3)-Mn-III-O-IV Manganese Oxo Core that Mimics the Natural Oxygen-Evolving Center
No full textThe functional core of oxygenic photosynthesis is in charge of catalytic water oxidation by a multi-redox MnIII/MnIV manifold that evolves through five electronic states (Si, where i=0-4). The synthetic model system of this catalytic cycle and of its S0→S4 intermediates is the expected turning point for artificial photosynthesis. The tetramanganese-substituted tungstosilicate [MnIII3MnIVO3(CH3COO)3(A-α-SiW9O34)]6- (Mn4POM) offers an unprecedented mimicry of the natural system in its reduced S0 state; it features a hybrid organic-inorganic coordination sphere and is anchored on a polyoxotungstate. Evidence for its photosynthetic properties when combined with [Ru(bpy)3]2+ and S2O82- is obtained by nanosecond laser flash photolysis; its S0→S1 transition within milliseconds and multiple-hole-accumulating properties were studied. Photocatalytic oxygen evolution is achieved in a buffered medium (pH 5) with a quantum efficiency of 1.7 %
Transition metal containing silico- and germanotungstates
No full textThis work focuses on the interaction of the versatile dilacunary silicotungstate unit with different metal cations leading to novel compounds interesting for magnetic and catalytic applications. Also this work reports two new lanthanide containing polytungstates, a sandwich type silicotungstate and a dimeric-pentameric germanotungstate. The 15-cobalt-substituted polyoxotungstate (1) has a core of nine CoII ions encapsulated by three unprecedented fragments and two Chloro ligands. The 6-cobalt-substituted silicotungstate (2) contains three cobalt ions which are encapsulated between an unprecedented fragment and a lacunary unit. The new, monometal substituted silicotungstates (3-5) are composed of two units fused on one side via two W-O-W' bridges and on the other side by an octahedrally coordinated transition metal fragment. The trimeric species (6) consists of three units linked by an unprecedented Zr6 cluster with C1 point group symmetry. The dimeric species (7) consists of two units sandwiching a Zr4 cluster and has also C1 symmetry. The unprecedented peroxo-zirconium(IV) containing silicotungstate (8) comprises a cyclic 6-peroxo-6-zirconium core stabilized by three decatungstosilicate units and represents the first structurally characterized Zr-peroxo POM with side-on, bridging peroxo units. The mono-lanthanide containing polyanions (9-16) have also been syntesized. Larger Ln3+ ions appear to favor an R,R (or S,S) configuration (point group C2) of the Keggin units, with an increasing amount of R,S (or S,R) configuration (point group C1) found in the solid state as the Ln3+ ion decreases in size. Finally, The gigantic 20-cerium(III) containing 100-tungstogermanate (17) represents the first lanthanide substituted tungstogermanate and it is one of the largest polytungstates reported to date
Latin America's experience with export subsidies
No full textTwenty years ago, it ws believed that export subsidies would produce more diversification and better export performance. This has not happened. In most cases, export subsidies were not supported by more open import policies - so subsidies reduced only marginally the anti-export bias of Latin American countries. Unstable real exchange rates have also hurt exports. Export subsidies appear to have improved exports in Brazil, which also liberalized imports, stabilized exchange rates, and promoted other policies conducive to export growth. Yet Mexico, after reducing import barriers, also enjoyed improved exports - with minimum export subsidies, and with apparently lower social costs than Brazil experienced. Export subsidies have failed in other Latin American countries - and particularly hurt development in Argentina, where fraud, corruption, and rent-seeking have been rampant. The author contends that the failure of export subsidies should remind us of the importance of distinguishing what is possible from what is likely. Finally, export subsidies compete with other government programs, and, considering their failure rate, the money might be better spent on infrastructure, health, and education projects.Tax Law,Economic Theory&Research,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Environmental Economics&Policies,Economic Stabilization
Synthesis and Characterization of 8-Yttrium(III)-Containing 81-Tungsto-8-Arsenate(III), [Y8(CH3COO)(H2O)18(As2W19O68)4(W2O6)2(WO4)]43−
No full textThe 8-yttrium(III)-containing 81-tungsto-8-arsenate(III) [Y8(CH3COO)(H2O)18(As2W19O68)4(W2O6)2(WO4)]43− (1) has been synthesized in a one-pot reaction of yttrium(III) ions with [B-α-AsW9O33]9− in 1 M NaOAc/HOAc buffer at pH 4.8. Polyanion 1 is composed of four {As2W19O68} units, two {W2O10} fragments, one {WO6} group, and eight YIII ions. The hydrated cesium-sodium salt of 1 (CsNa-1) was characterized in the solid-state by single-crystal XRD, FT-IR spectroscopy, thermogravimetric and elemental analyses
The trickster and the system identity and agency in contemporary society
No full text"For centuries, the trickster has been used in various narratives, including mythological, literary and cinematic, to convey the idea of agency, rebellion and, often turbulent, progress. In The Trickster and the System: Identity and Agency in Contemporary Society, Helena Bassil-Morozow shows how the trickster can be seen as a metaphor to describe the psycho-anthropological concept of change, an impulse that challenges the existing order of things, a progressive force that is a-structural and anti-structural in its nature. The book is about being able to see things from an unusual, even 'odd', perspective, which does not coincide with the homogenous normality of the mass, or the social system, or a political ideology, or some other kind of authority. The Trickster and the System offers an analytical paradigm which can be used to examine relationships between tricksters and systems, change and stability, in a wide range of social, political and cultural contexts. It covers a range of systems, describes different types of tricksters and discusses possible conflicts, tensions and dialogues between the two opposing sides. One of the central ideas of the book is that social systems use shame as a tool to control and manage all kinds of tricksters...individuality, agency, creativity, spontaneity, innovation and initiative, to name but a few. The author argues that any society that neglects its tricksters (agents of change), ends up suffering from decay, stagnation...or even mass hysterical outbursts. The Trickster and the System: Identity and Agency in Contemporary Society provides a fresh perspective on the trickster figure in a variety of cultural contexts. It covers a range of psychological, cultural, social and political phenomena, from personal issues to the highest level of society's functioning: self-esteem and shame, lifestyle and relationships, creativity and self-expression, media, advertising, economy, politica
Divacant polyoxotungstates: Reactivity of the gamma-decatungstates [γ-XW10O36]8−(X = Si, Ge)
No full textChemInform Abstract: Divacant Polyoxotungstates: Reactivity of the Gamma-Decatungstates [γ-XW10O36]8- (X: Si, Ge)
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