299 research outputs found

    Main-chain metallopolymers at the static–dynamic boundary based on nickelocene

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    Interactions between metal ions and ligands in metal-containing polymers involve two bonding extremes: persistent covalent bonding, in which the polymers are essentially static in nature, or labile coordination bonding, which leads to dynamic supramolecular materials. Main-chain polymetallocenes based on ferrocene and cobaltocene fall into the former category because of the presence of strong metal–cyclopentadienyl bonds. Herein, we describe a main-chain polynickelocene—formed by ring-opening polymerization of a moderately strained [3]nickelocenophane monomer—that can be switched between static and dynamic states because of the relatively weak nickel–cyclopentadienyl ligand interactions. This is illustrated by the observation that, at a low concentration or at an elevated temperature in a coordinating or polar solvent, depolymerization of the polynickelocene occurs. A study of this dynamic polymer–monomer equilibrium by 1H NMR spectroscopy allowed the determination of the associated thermodynamic parameters. Microrheology data, however, indicated that under similar conditions the polynickelocene is considered to be static on the shorter rheological timescale

    Untangling knowledge creation and knowledge integration in enterprise wikis

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    A central challenge organizations face is how to build, store, and maintain knowledge over time. Enterprise wikis are community-based knowledge systems situated in an organizational context. These systems have the potential to play an important role in managing knowledge within organizations, but the motivating factors that drive individuals to contribute their knowledge to these systems is not very well understood. We theorize that enterprise wiki initiatives require two separate and distinct types of knowledge-sharing behaviors to succeed: knowledge creation (KC) and knowledge integration (KI). We examine a Wiki initiative at a major German bank to untangle the motivating factors behind KC and KI. Our results suggest KC and KI are indeed two distinct behaviors, reconcile inconsistent findings from past studies on the role of motivational factors for knowledge sharing to establish shared electronic knowledge resources in organizations, and identify factors that can be leveraged to tilt behaviors in favor of KC or KI

    Common Goods for Health : Economic Rationale and Tools for Prioritization

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    This paper presents the economic rationale for treating Common Goods for Health (CGH) as priorities for public intervention. We use the concept of market failure as a central argument for identifying CGH and apply cost-effectiveness analysis (CEA) as a normative tool to prioritize CGH interventions in public finance decisions. We show that CGH are consistent with traditional lists of public health core functions but cannot be identified separately from non-CGH activities in such lists. We propose a public finance decision tree, adapted from existing health economics tools, to identify CGH activities within the set of cost-effective interventions for the health sector. We test the framework by applying it to the 2018 Disease Control Priority (DCP) list of interventions recommended for public funding and find that less than 10% of cost-effective interventions unconditionally qualify as CGH, while another two-thirds may or may not qualify depending on context and form. We conclude that while CEA can be used as a tool to prioritize CGH, the scarcity of such analyses for CGH interventions may be partly responsible for the lack of priority given to them. We encourage further research to address methodological and resource challenges to assessing the cost-effectiveness of CGH intervention packages, in particular those involving large investments and long-term benefits

    Spectroscopic evidence for an all-ferrous [4Fe–4S]0 cluster in the superreduced activator of 2-hydroxyglutaryl-CoA dehydratase from Acidaminococcus fermentans

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    The key enzyme of the fermentation of glutamate by Acidaminococcus fermentans, 2-hydroxyglutarylcoenzyme A dehydratase, catalyzes the reversible syn-elimination of water from (R)-2-hydroxyglutaryl-coenzyme A, resulting in (E)-glutaconylcoenzyme A. The dehydratase system consists of two oxygen-sensitive protein components, the activator (HgdC) and the actual dehydratase (HgdAB). Previous biochemical and spectroscopic studies revealed that the reduced [4Fe–4S]+ cluster containing activator transfers one electron to the dehydratase driven by ATP hydrolysis, which activates the enzyme. With a tenfold excess of titanium(III) citrate at pH 8.0 the activator can be further reduced, yielding about 50% of a superreduced [4Fe–4S]0 cluster in the all-ferrous state. This is inferred from the appearance of a new Mössbauer spectrum with parameters δ = 0.65 mm/s and ΔEQ = 1.51–2.19 mm/s at 140 K, which are typical of Fe(II)S4 sites. Parallel-mode electron paramagnetic resonance (EPR) spectroscopy performed at temperatures between 3 and 20 K showed two sharp signals at g = 16 and 12, indicating an integer-spin system. The X-band EPR spectra and magnetic Mössbauer spectra could be consistently simulated by adopting a total spin St = 4 for the all-ferrous cluster with weak zero-field splitting parameters D = −0.66 cm−1 and E/D = 0.17. The superreduced cluster has apparent spectroscopic similarities with the corresponding [4Fe–4S]0 cluster described for the nitrogenase Fe-protein, but in detail their properties differ. While the all-ferrous Fe-protein is capable of transferring electrons to the MoFe-protein for dinitrogen reduction, a similar physiological role is elusive for the superreduced activator. This finding supports our model that only one-electron transfer steps are involved in dehydratase catalysis. Nevertheless we discuss a common basic mechanism of the two diverse systems, which are so far the only described examples of the all-ferrous [4Fe–4S]0 cluster found in biology

    Importance of the Public Service in Achieving the UN SDGs

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    Public service is the engine of effective governance delivery in the world economy; governments across the world cannot function well without the enabling structures of public administration to deliver on their mandate as set out mostly in (political) manifestos, while also making sure the core mandate for meeting citizens’ basic welfare needs are made available through an efficient market system. The operation of such a market system must enable entities or agents to act in the best interest of delivering high services, which would have already been set as dictated through regulation of the legal system – this should also facilitate the presence of information symmetry for agents to operate (Jackson and Jabbie, 2019; Winston, 2006; Weiner and Vining, 2004)

    Corporation taxes in the European Union: Slowly moving toward comprehensive business income taxation?

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    This paper is a substantial revision of a paper presented at the 71st Annual Congress of the International Institute of Public Finance (Dublin, 20–23 August, 2015), which was issued under the title Tackling Spillovers by Taxing Corporate Income in the European Union at Source, as CPB Discussion Paper 324 (February 2016) and as CESifo Working Paper No. 5790 (March 2016).This paper surveys and evaluates the corporation tax systems of the Member States of the European Union on the basis of a comprehensive taxonomy of actual and potential regimes, which have as their base either profits; profits, interest and royalties; or economic rents. The current regimes give rise to various instate and interstate spillovers, which violate the basic tenets—neutrality and subsidiarity—of the single market. The trade-offs between the implications of these tenets—harmonization and diversity, respectively—can be reconciled by a bottom-up strategy of strengthening source-based taxation and narrowing differences in tax rates. The strategy starts with dual income taxation, proceeds with final source withholding taxes and rate coordination, and is made complete by comprehensive business income taxation. Common base and cash flow taxation are not favored.http://link.springer.com/journal/10797am2017Economic
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