53 research outputs found

    On the Heisenberg invariance and the Elliptic Poisson tensors

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    We study different algebraic and geometric properties of Heisenberg invariant Poisson polynomial quadratic algebras. We show that these algebras are unimodular. The elliptic Sklyanin-Odesskii-Feigin Poisson algebras qn,k(E)q_{n,k}(\mathcal E) are the main important example. We classify all quadratic HH-invariant Poisson tensors on Cn{\mathbb C}^n with n6n\leq 6 and show that for n5n\leq 5 they coincide with the elliptic Sklyanin-Odesskii-Feigin Poisson algebras or with their certain degenerations.Comment: 14 pages, no figures, minor revision, typos correcte

    Global maps of soil temperature.

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    Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km <sup>2</sup> resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km <sup>2</sup> pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

    Oxidative Dehomologation of Aldehydes with Oxygen as a Terminal Oxidant

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    A mild, efficient protocol for oxidative cleavage of C-C bonds in aldehydes has been developed that employs alkali metal hydrides as reagents and oxygen from air as a terminal oxidant. The method is applicable to a broad substrate range. © 2017 American Chemical Society

    Oxidative Dehomologation of Aldehydes with Oxygen as a Terminal Oxidant

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    A mild, efficient protocol for oxidative cleavage of C-C bonds in aldehydes has been developed that employs alkali metal hydrides as reagents and oxygen from air as a terminal oxidant. The method is applicable to a broad substrate range. © 2017 American Chemical Society

    Oxidative azo-ene cyclization

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    An expedient procedure for catalytic oxidative azo-ene cyclization of allylic and homoallylic 1,2-hydrazinedicarboxylates is reported. The reaction produced a wide range of cyclic carbamate derivatives featuring an appended alkene fragment ready for further functionalization. © 2016 American Chemical Society

    Oxidative azo-ene cyclization

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    An expedient procedure for catalytic oxidative azo-ene cyclization of allylic and homoallylic 1,2-hydrazinedicarboxylates is reported. The reaction produced a wide range of cyclic carbamate derivatives featuring an appended alkene fragment ready for further functionalization. © 2016 American Chemical Society

    Dehydration of Amides to Nitriles under Conditions of a Catalytic Appel Reaction

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    A highly expedient protocol for a catalytic Appel-type dehydration of amides to nitriles has been developed that employs oxalyl chloride and triethylamine along with triphenylphosphine oxide as a catalyst. The reactions are usually complete in less than 10 min with only a 1 mol % catalyst loading. The reaction scope includes aromatic, heteroaromatic, and aliphatic amides, including derivatives of α-hydroxy and α-amino acids. © 2018 American Chemical Society
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