139 research outputs found

    A Comparison of Unbleached Pulps from Cherry Heartwood and Sapwood

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    The purpose of the project was to evaluate pulps made from cherry heartwood and sapwood. The amount of heartwood a tree has is an individual trait of the tree rather than a function of geography or environment. Tree breeders can, through selection, reduce or increase the amount of heartwood if it is economically justifiable. Three cherry logs with 50-50 heartwood to sapwood ratio were barked and chipped at S.D. Warren Company in Muskegon. The chips were separated, heartwood from sapwood, by the color difference. The chips were cooked using 20% active alkali, 6 to 1 liquor ratio, for 1.5 hours at 175‚ó¶C using an oil bath digester. The oil bath digester had six cartridges of which three were charged with heartwood and three with sapwood. The average yield for heartwood was 44.8% and the average yield for sapwood was 52.7%. The difference in yield was the most significant difference between heartwood and sapwood. The brightness of the sapwood was about 5% greater than heartwood. The Kappa number of the heartwood was 20.8 compared to 22.0 for sapwood. The mullen of heartwood was greater than the sapwood in the freeness range of 100 to 500 C.S.F. by 12 to 16%. The tensile of heartwood was greater than the sapwood in the freeness range of 150 to 500 C.S.F. by 4 to 8%. The tear of sapwood was greater than heartwood in the freeness range of 100 to 500 C.S.F. by 14 to 18%. You cannot totally eliminate either heartwood or sapwood and the resulting trade-off of advantages of increasing or decreasing the percent of heartwood would likely result in only a couple percent advantages in a few parameters. Therefore, the conclusion of this paper is to leave the ratio of heartwood to sapwood to nature

    A process model of natural attenuation in drainage from a historic mining district

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    A process model was used to better understand the controls on the chemical evolution of drainage in a historic mining district. At the Pecos Mine Operable Unit, New Mexico, drainage near the waste rock pile is acidic (pH varies from 3.0--5.0) and carries high concentrations of Zn, Al, Cu and Pb. As drainage flows toward the Pecos River, pH increases to greater than 7 and heavy metal content decreases. A process model of natural attenuation in this drainage shows the main controls on pH are reaction with a local bedrock that contains limestone, and concurrent mixing with tributary streams. Models that account for both calcite dissolution and mixing reproduce the observed decrease in aqueous metal concentrations with increasing pH. Contaminant concentrations attenuate primarily via two distinct pathways: Al, Cu, Fe and Pb precipitate directly from solution, whereas Zn, Mg, Mn and SO{sub 4} concentrations decrease primarily through dilution. Additionally, Pb adsorbs to precipitating hydroxide surfaces

    Monte Carlo simulation for jet fragmentation in SUSY-QCD

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    We present results from a new Monte Carlo simulation for jet fragmentation in QCD and SUSY QCD for large primary energies s\sqrt s up to 101610^{16} GeV. In the case of SUSY QCD the simulation takes into account not only gluons and quarks as cascading particles, but also their supersymmetric partners. A new model-independent hadronization scheme is developed, in which the hadronization functions are found from LEP data. An interesting feature of SUSY QCD is the prediction of a sizeable flux of the lightest supersymmetric particles (LSPs), if R-parity is conserved. About 10% of the jet energy is transferred to LSPs which, owing to their harder spectra, constitute an important part of the spectra for large x=E/Ejetx=E/E_{jet}. Spectra of protons and of secondary particles, photons and neutrinos, are also calculated. These results have implications for the decay of superheavy particles with masses up to the GUT scale, which have been suggested as a source of ultrahigh energy cosmic rays.Comment: latex, 25 pages with 17 eps figure

    Loop Quantum Cosmology: A Status Report

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    The goal of this article is to provide an overview of the current state of the art in loop quantum cosmology for three sets of audiences: young researchers interested in entering this area; the quantum gravity community in general; and, cosmologists who wish to apply loop quantum cosmology to probe modifications in the standard paradigm of the early universe. An effort has been made to streamline the material so that, as described at the end of section I, each of these communities can read only the sections they are most interested in, without a loss of continuity.Comment: 138 pages, 15 figures. Invited Topical Review, To appear in Classical and Quantum Gravity. Typos corrected, clarifications and references adde

    Geochemical Characterization of Two Ferruginous Meromictic Lakes in the Upper Midwest, USA

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    To elucidate the role of (bio)geochemical processes that fueled iron and carbon cycling in early Earth oceans, modern environments with similar geochemical conditions are needed. As the range of chemical, physical, and biological attributes of the Precambrian oceans must have varied in time and space, lakes of different compositions are useful to ask and answer different questions. Tropical Lake Matano (Indonesia), the largest known ferruginous lake, and Lake Pavin (France), a meromictic crater lake, are the two best studied Precambrian ocean analogs. Here we present seasonal geochemical data from two glacially formed temperate ferruginous lakes: Brownie Lake (MN) and Canyon Lake (MI) in the Upper Midwest, USA. The results of seasonal monitoring over multiple years indicate that (1) each lake is meromictic with a dense, anoxic monimolimnion, which is separated from the less dense, oxic mixolimnion by a sharp chemocline; (2) below this chemocline are ferruginous waters, with maximum dissolved iron concentrations \u3e1 mM; (3) meromixis in Brownie Lake is largely anthropogenic, whereas in Canyon Lake it is natural; (4) the shallow chemocline of Brownie Lake and high phosphorus reservoir make it an ideal analog to study anoxygenic photosynthesis, elemental ratios, and mineralogy; and (5) a deep penetrating suboxic zone in Canyon Lake may support future studies of suboxic microbial activity or mineral transformation

    Search for dark matter produced in association with bottom or top quarks in ‚ąös = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb‚ąí1 of proton‚Äďproton collision data recorded by the ATLAS experiment at ‚ąös = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 20 fb‚ąí1 of ‚ąös=8 TeV proton-proton collision data with the ATLAS detector