3,043 research outputs found

    An \u3cem\u3eIn Vitro\u3c/em\u3e Spectroscopic Analysis to Determine the Chemical Composition of the Precipitate Formed by Mixing Sodium Hypochlorite and Chlorhexidine

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    Introduction—The purpose of this in vitro study was to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite (NaOCl) and Chlorhexidine (CHX), and relative molecular weight of the components. Methods—Using commercially available chlorhexidine gluconate (CHXg), a 2% solution was formed and mixed in a 1:1 ratio with commercially available NaOCl producing a brown precipitate. The precipitate as well as a mixture of precipitate and pure chlorhexidine diacetate (CHXa) was then analyzed using 1D and 2D NMR spectroscopy. Results—The 1D and 2D NMR spectra were fully assigned, in terms of chemical shifts of all proton and carbon atoms in intact CHX. This permitted identification of CHX breakdown products with and without the aliphatic linker present, including lower molecular weight components of CHX that contained a para-substituted benzene that was not para-chloroaniline (PCA). Conclusions—Based on this in vitro study, the precipitate formed by NaOCl and CHX is composed of at least two separate molecules, all of which are smaller in size than CHX. Along with native CHX, the precipitate contains two chemical fragments derived from CHX, neither of which are PCA

    European farming and post-2013 CAP measures. A quantitative impact assessment

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    Following the paradigm for reforming the current CAP, the first objective of this study is to give insights into the economic impact of post-2013 CAP measures at different levels of aggregation (e.g. EU, Member State and region). The post-2013 CAP measures included are directed towards income for the farmers, competitiveness, valuable areas and ecosystem services. The second objective is to analyse the impact of a scenario that combines the above mentioned post-2013 CAP measures. This study can be seen as a first attempt to quantify the transition to a CAP with more targeted measures at the European level and reveals considerable methodological and data challenges. A key finding is that the impact of the various measures is very different with regard to various economic indicators.Agricultural and Food Policy,

    Comparison of measured and EF5-r derived N₂O fluxes from a spring-fed river

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    There is considerable uncertainty in the estimates of indirect N₂O emissions as defined by the Intergovernmental Panel on Climate Change's (IPCC) methodology. Direct measurements of N₂O yields and fluxes in aquatic river environments are sparse and more data are required to determine the role that rivers play in the global N₂O budget. The objectives of this research were to measure the N₂O fluxes from a spring-fed river, relate these fluxes to the dissolved N₂O concentrations and NO₃–N loading of the river, and to try and define the indirect emission factor (EF5-r) for the river. Gas bubble ebullition was observed at the river source with bubbles containing 7.9 µL N₂O L⁻¹. River NO₃–N and dissolved N₂O concentrations ranged from 2.5 to 5.3 mg L⁻¹ and 0.4 to 1.9 µg N₂O-N L⁻¹ respectively with N₂O saturation reaching 404%. Floating headspace chambers were used to sample N₂O fluxes. N₂O–N fluxes were significantly related to dissolved N₂O–N concentrations (r² = 30.6) but not to NO₃–N concentrations. The N₂O–N fluxes ranged from 38-501 µg m⁻² h⁻¹, averaging 171 µg m⁻² h⁻¹ (± Std. Dev. 85) overall. The measured N₂O–N fluxes equated to an EF5-r of only 6.6% of that calculated using the IPCC methodology, and this itself was considered to be an over-estimate due to the degassing of antecedent dissolved N₂O present in the groundwater that fed the river

    Study on the Implications of Asynchronous GMO Approvals for EU Imports of Animal Feed Products

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    The aim of this study is to understand the implications of asynchronous approvals for genetically modified organisms (GMOs) that are imported to the European Union for use within animal feed products, specifically with regard to the EU livestock sector, as well as upon the upstream and downstream economic industries related to it. Asynchronous approval refers to the situation in which there is a delay in the moment when a genetically modified (GM) event – modifying a specific trait of a plant or animal – is allowed to be used in one country in comparison to another country. In the perspective of this study, the asynchronous GMO approvals concern the use of GM varieties of plants that are approved in the countries which supply them to the EU, in one form or another of feed material, before these are approved by the EU

    Twisted Classical Poincar\'{e} Algebras

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    We consider the twisting of Hopf structure for classical enveloping algebra U(g^)U(\hat{g}), where g^\hat{g} is the inhomogenous rotations algebra, with explicite formulae given for D=4D=4 Poincar\'{e} algebra (g^=P4).(\hat{g}={\cal P}_4). The comultiplications of twisted UF(P4)U^F({\cal P}_4) are obtained by conjugating primitive classical coproducts by FU(c^)U(c^),F\in U(\hat{c})\otimes U(\hat{c}), where c^\hat{c} denotes any Abelian subalgebra of P4{\cal P}_4, and the universal RR-matrices for UF(P4)U^F({\cal P}_4) are triangular. As an example we show that the quantum deformation of Poincar\'{e} algebra recently proposed by Chaichian and Demiczev is a twisted classical Poincar\'{e} algebra. The interpretation of twisted Poincar\'{e} algebra as describing relativistic symmetries with clustered 2-particle states is proposed.Comment: \Large \bf 19 pages, Bonn University preprint, November 199

    The compound Poisson limit ruling periodic extreme behaviour of non-uniformly hyperbolic dynamics

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    We prove that the distributional limit of the normalised number of returns to small neighbourhoods of periodic points of non-uniformly hyperbolic dynamical systems is compound Poisson. The returns to small balls around a fixed point in the phase space correspond to the occurrence of rare events, or exceedances of high thresholds, so that there is a connection between the laws of Return Times Statistics and Extreme Value Laws. The fact that the fixed point in the phase space is a repelling periodic point implies that there is a tendency for the exceedances to appear in clusters whose average sizes is given by the Extremal Index, which depends on the expansion of the system at the periodic point. We recall that for generic points, the exceedances, in the limit, are singular and occur at Poisson times. However, around periodic points, the picture is different: the respective point processes of exceedances converge to a compound Poisson process, so instead of single exceedances, we have entire clusters of exceedances occurring at Poisson times with a geometric distribution ruling its multiplicity. The systems to which our results apply include: general piecewise expanding maps of the interval (Rychlik maps), maps with indifferent fixed points (Manneville-Pomeau maps) and Benedicks-Carleson quadratic maps.Comment: To appear in Communications in Mathematical Physic

    Water Abundance of Dunes in Gale Crater, Mars From Active Neutron Experiments and Implications for Amorphous Phases

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    We report the water abundance of Bagnold Dune sand in Gale crater, Mars by analyzing active neutron experiments using the Dynamic Albedo of Neutrons instrument. We report a bulk water‐equivalent‐hydrogen abundance of 0.68 ± 0.15 wt%, which is similar to measurements several kilometers away and from those taken of the dune surface. Thus, the dune is likely dehydrated throughout. Furthermore, we use geochemical constraints, including bulk water content, to develop compositional models of the amorphous fraction for which little information is known. We find the amorphous fraction contains ∼26‐ to 64‐wt% basaltic glass and up to ∼24‐wt% rhyolitic glass, suggesting at least one volcanic source for the dune material. We also find a range of hydrated phases may be present in appreciable abundances, either from the incorporation of eroded aqueously altered sediments or the direct alteration of the dune sand

    Development of a Multilayer MODIS IST-Albedo Product of Greenland

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    A new multilayer IST-albedo Moderate Resolution Imaging Spectroradiometer (MODIS) product of Greenland was developed to meet the needs of the ice sheet modeling community. The multiple layers of the product enable the relationship between IST and albedo to be evaluated easily. Surface temperature is a fundamental input for dynamical ice sheet models because it is a component of the ice sheet radiation budget and mass balance. Albedo influences absorption of incoming solar radiation. The daily product will combine the existing standard MODIS Collection-6 ice-surface temperature, derived melt maps, snow albedo and water vapor products. The new product is available in a polar stereographic projection in NetCDF format. The product will ultimately extend from March 2000 through the end of 2017
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