99 research outputs found

    Pyrazole or tris(pyrazolyl)ethanol oxo-vanadium(IV) complexes as homogeneous or supported catalysts for oxidation of cyclohexane under mild conditions

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    The oxovanadium(IV) complexes [VO(acac)(2)(Hpz)].HC(pz)(3) 1.HC(pz)(3) (acac= acetylacetonate, Hpz = pyrazole, pz = pyrazoly1) and [VOCl2{HOCH2C(pz)(3)}] 2 were obtained from reaction of [VO(acac)(2)] with hydrotris(1-pyrazolyl)methane or of VCl(3)with 2,2,2-tris(1-pyrazolyl)ethanol. The compounds were characterized by elemental analysis, IR, Far-IR and EPR spectroscopies, FAB or ESI mass-spectrometry and, for 1, by single crystal X-ray diffraction analysis. 1 and 2 exhibit catalytic activity for the oxidation of cyclohexane to the cyclohexanol and cyclohexanone mixture in homogeneous system (TONS up to 1100) under mild conditions (NCMe, 24h, room temperature) using benzoyl peroxide (BPO), tert-butyl hydroperoxide (TBHP), m-chloroperoxybenzoic acid (mCPBA), hydrogen peroxide or the urea-hydrogen peroxide adduct (UHP) as oxidants. 1 and 2 were also immobilized on a polydimethylsiloxane membrane (1-PDMS or 2-PDMS) and the systems acted as supported catalysts for the cyclohexane oxidation using the above oxidants (TONs up to 620). The best results were obtained with mCPBA or BP0 as oxidant. The effects of various parameters, such as the amount of catalyst, nitric acid, reaction time, type of oxidant and oxidant-to-catalyst molar ratio, were investigated, for both homogeneous and supported systems. (C) 2012 Elsevier B.V. All rights reserved

    Evaluation of Different Aerification Methods for Ultradwarf Hybrid Bermudagrass Putting Greens

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    Aerification and topdressing are important cultural management practices that help prevent organic matter accumulation and soil compaction in golf greens. However, these practices result in surface disruption and decreased putting quality during recovery. A 2-year study was conducted on a ‘TifEagle’ hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) putting green to determine the effect of different aerification methods and topdressing materials on soil properties and turfgrass recovery. Plots were aerified four times per year (May to Aug.) using 1/2-inch hollow tines, 1/4-inch hollow needle tines, hollow tines 2X + hollow needle tines 2X, or sand injection, and topdressed with either 90:10 (sand:peat) or green-dyed sand. Visual quality, normalized difference vegetation index, percent green cover, dark green color index (DGCI), surface firmness and volumetric water content were measured before initial aerification and at 7 and 21 days after aerification. Saturated hydraulic conductivity (Ksat) and organic matter (OM) content were measured monthly. Aerification with hollow tines and hollow tines 2X + hollow needle tines 2X resulted in lower firmness and OM and higher Ksat compared with hollow needle tines and sand injection. Sand injection showed the highest percent green cover and similar OM content compared with hollow tines and hollow tines 2X + hollow needle tines 2X. Green-dyed sand showed a higher percent green cover and DGCI compared with 90:10 sand:peat. Using hollow tines only or alternating them with hollow needle tines is the best option to decrease OM content while increasing Ksat in hybrid bermudagrass greens; however, their use could result in slower turfgrass recovery compared with other aerification methods

    THE SPACE TELESCOPE NINA: RESULTS OF A BEAM TEST CALIBRATION

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    Abstract In June 1998 the telescope NINA will be launched in space on board of the Russian satellite Resource-01 n.4. The main scientific objective of the mission is the study of the anomalous, galactic and solar components of the cosmic rays in the energy interval 10–200 MeV/n. The core of the instrument is a silicon detector whose performances have been tested with a particle beam at the GSI Laboratory in Germany in 1997; we report here on the results obtained during the beam calibration

    A silicon imaging calorimeter prototype for antimatter search in space: experimental results

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    Abstract This report presents the results obtained with a prototype silicon-tungsten (Si-W) electromagnetic calorimeter, conceived as a fine-grained imaging device to carry out studies of the antimatter component in primary cosmic radiation. The calorimeter prototype contains 20 x , y sampling layers interleaved with 19 showering material planes. One sensitive layer is obtained with two silicon strip detectors (Si-D) (60 × 60) mm 2 , each divided into 16 strips, 3.6 mm wide; the two detectors are assembled back to back with perpendicular strips. This allows the transverse distributions of the shower in both coordinates at each sampling (0.5 X 0 ) to be pictured. The basic characteristics of the design and the experimental results obtained on a test beam at the CERN proton synchrotron (PS) for electrons and pions are reported. The main results presented are the response of the calorimeter to the electron at various energies (1–7 GeV), and the transverse shower profiles at different calorimeter depths as well as the patterns of the electromagnetic shower and those of the interacting and non-interacting pions. The capability of the calorimeter in measuring the direction of the incoming electromagnetic particle from the pattern of the shower has been evaluated at different energies. These results are encouraging in view of the possible use of this detector to search for high-energy γ sources in space

    Silicon calorimeter for cosmic antimatter search

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    Abstract The silicon sampling calorimeter presented is conceived as a fine grained imaging device to carry out studies of the anti-matter component in the primary cosmic radiation; it will be used in balloon payload program starting in 1993. The first sampling layer (48×48 cm2) of this silicon calorimeter has been completed and successfully tested. We report the first results form studies performed at the CERN PS t7 beam. The complete calorimeter contains 20 xy sampling layers (strip pitch 3.6 mm) interleaved with 19 showering material planes (tungsten 0.5 X0). This allows to picture the transverse distributions of the shower in both coordinates at each sampling. The outstanding imaging capabilities reflects in high particle identification power. Preliminary results from beam tests performed with antiprotons at 3.5 GeV on a tower prototype of the calorimeter are reported

    The Polarised Valence Quark Distribution from semi-inclusive DIS

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    The semi-inclusive difference asymmetry A^{h^{+}-h^{-}} for hadrons of opposite charge has been measured by the COMPASS experiment at CERN. The data were collected in the years 2002-2004 using a 160 GeV polarised muon beam scattered off a large polarised ^6LiD target and cover the range 0.006 < x < 0.7 and 1 < Q^2 < 100 (GeV/c)^2. In leading order QCD (LO) the asymmetry A_d^{h^{+}-h^{-}} measures the valence quark polarisation and provides an evaluation of the first moment of Delta u_v + Delta d_v which is found to be equal to 0.40 +- 0.07 (stat.) +- 0.05 (syst.) over the measured range of x at Q^2 = 10 (GeV/c)^2. When combined with the first moment of g_1^d previously measured on the same data, this result favours a non-symmetric polarisation of light quarks Delta u-bar = - Delta d-bar at a confidence level of two standard deviations, in contrast to the often assumed symmetric scenario Delta u-bar = Delta d-bar = Delta s-bar = Delta s.Comment: 7 pages, 3 figures, COMPASS, revised: details added, author list update

    The ocean sampling day consortium

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    Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits

    The Ocean Sampling Day Consortium

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    Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits

    The wide-field, multiplexed, spectroscopic facility WEAVE : survey design, overview, and simulated implementation

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    Funding for the WEAVE facility has been provided by UKRI STFC, the University of Oxford, NOVA, NWO, Instituto de Astrofísica de Canarias (IAC), the Isaac Newton Group partners (STFC, NWO, and Spain, led by the IAC), INAF, CNRS-INSU, the Observatoire de Paris, Région Île-de-France, CONCYT through INAOE, Konkoly Observatory (CSFK), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Lund University, the Leibniz Institute for Astrophysics Potsdam (AIP), the Swedish Research Council, the European Commission, and the University of Pennsylvania.WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366-959 nm at R ∼ 5000, or two shorter ranges at R ∼ 20,000. After summarising the design and implementation of WEAVE and its data systems, we present the organisation, science drivers and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for ∼ 3 million stars and detailed abundances for ∼ 1.5 million brighter field and open-cluster stars; (ii) survey ∼ 0.4 million Galactic-plane OBA stars, young stellar objects and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey  ∼ 400 neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionised gas in z 1 million spectra of LOFAR-selected radio sources; (viii) trace structures using intergalactic/circumgalactic gas at z > 2. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator.PostprintPeer reviewe
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