4,017 research outputs found

    Alfalfa Production and Trends in Kentucky

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    Alfalfa is often referred to as the Queen of U.S. Forage Production . Looking at all hay production alfalfa should be called The King . In 1991, 83.8 million tons were harvested in the United States -- 55 percent of all the hay harvested in the United States. This total does not include the many tons harvested as green chop, which is an especially common practice among dairy farmers. But, why shouldn\u27t alfalfa be popular? This deep rooted leguminous plant is generally the forage leader in yield, protein, and TDN

    Geology and Stratigraphy of the Western Kentucky Coal Field

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    The Pennsylvanian rocks of the Western Kentucky Coal Field produce between 40 and 55 million tons of coal a year from as many as 45 coal seams; however, three seams produce more than 75 percent of the total. In addition, Pennsylvanian strata contain numerous oil and natural gas reservoirs, tar-sand reservoirs, and industrial minerals. Pennsylvanian sandstones are also some of the most important bedrock aquifers in the coal field. Because of the economic importance of the Pennsylvanian strata to the region and the Commonwealth as a whole, a better understanding of these rocks is needed. This description of the nomenclature of Pennsylvanian strata in the Western Kentucky Coal Field also provides information on their mineral resources and geology. New stratigraphic names, based on regional agreements among the state geological surveys of Kentucky, Illinois, and Indiana, are also presented

    Optimization of inhomogeneous electron correlation factors in periodic solids

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    A method is presented for the optimization of one-body and inhomogeneous two-body terms in correlated electronic wave functions of Jastrow-Slater type. The most general form of inhomogeneous correlation term which is compatible with crystal symmetry is used and the energy is minimized with respect to all parameters using a rapidly convergent iterative approach, based on Monte Carlo sampling of the energy and fitting energy fluctuations. The energy minimization is performed exactly within statistical sampling error for the energy derivatives and the resulting one- and two-body terms of the wave function are found to be well-determined. The largest calculations performed require the optimization of over 3000 parameters. The inhomogeneous two-electron correlation terms are calculated for diamond and rhombohedral graphite. The optimal terms in diamond are found to be approximately homogeneous and isotropic over all ranges of electron separation, but exhibit some inhomogeneity at short- and intermediate-range, whereas those in graphite are found to be homogeneous at short-range, but inhomogeneous and anisotropic at intermediate- and long-range electron separation.Comment: 23 pages, 15 figures, 1 table, REVTeX4, submitted to PR

    N-Doped Fe@CNT for Combined RWGS/FT CO <sub>2</sub> Hydrogenation

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    The conversion of CO<sub>2</sub> into chemical fuels represents an attractive route for greenhouse gas emission reductions and renewable energy storage. Iron nanoparticles supported on graphitic carbon materials (e.g., carbon nanotubes (CNTs)) have proven themselves to be effective catalysts for this process. This is due to their stability and ability to support simultaneous reverse water-gas shift (RWGS) and Fischer–Tropsch (FT) catalysis. Typically, these catalytic iron particles are postdoped onto an existing carbon support via wet impregnation. Nitrogen doping of the catalyst support enhances particle–support interactions by providing electron-rich anchoring sites for nanoparticles during wet impregnation. This is typically credited for improving CO<sub>2</sub> conversion and product selectivity in subsequent catalysis. However, the mechanism for RWGS/FT catalysis remains underexplored. Current research places significant emphasis on the importance of enhanced particle–support interactions due to N doping, which may mask further mechanistic effects arising from the presence or absence of nitrogen during CO<sub>2</sub> hydrogenation. Here we report a clear relationship between the presence of nitrogen in the CNT support of an RWGS/FT iron catalyst and significant shifts in the activity and product distribution of the reaction. Particle–support interactions are maximized (and discrepancies between N-doped and pristine support materials are minimized) by incorporating iron and nitrogen directly into the support during synthesis. Reactivity is thus rationalized in terms of the influence of C–N dipoles in the support upon the adsorption properties of CO<sub>2</sub> and CO on the surface rather than improved particle–support interactions. These results show that the direct hydrogenation of CO<sub>2</sub> to hydrocarbons is a potentially viable route to reduce carbon emissions from human activities

    Multifrequency Observations of Radio Pulse Broadening and Constraints on Interstellar Electron Density Microstructure

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    We have made observations of 98 low-Galactic-latitude pulsars to measure pulse broadening caused by multipath propagation through the interstellar medium. Data were collected with the 305-m Arecibo telescope at four radio frequencies between 430 and 2380 MHz. We used a CLEAN-based algorithm to deconvolve interstellar pulse broadening from the measured pulse shapes. We employed two distinct pulse broadening functions (PBFs): PBF1_1 is appropriate for a thin screen of scattering material between the Earth and a pulsar, while PBF2_2 is appropriate for scattering material uniformly distributed along the line of sight from the Earth to a pulsar. We found that some observations were better fit by PBF1_1 and some by PBF2_2. Pulse broadening times (τd\tau_d) are derived from fits of PBFs to the data, and are compared with the predictions of a smoothed model of the Galactic electron distribution. Several lines of sight show excess broadening, which we model as clumps of high density scattering material. A global analysis of all available data finds that the pulse broadening scales with frequency, ν\nu, as \taud \propto\nu^{-\alpha} where α∼3.9±0.2\alpha\sim 3.9\pm 0.2. This is somewhat shallower than the value α=4.4\alpha=4.4 expected from a Kolmogorov medium, but could arise if the spectrum of turbulence has an inner cutoff at ∼\sim 300--800 km. A few objects follow particularly shallow scaling laws (the mean scaling index \meanalpha \sim 3.1 \pm 0.1 and ∼3.8±0.2 \sim 3.8 \pm 0.2 respectively for the case of PBF1_1 and PBF2_2), which may arise from large scale refraction or from the truncation of scattering screens transverse to the Earth--pulsar line of sight.Comment: Accepted for publication in the Astrophysical Journal; 32 pages, 11 figure

    Non-Newtonian effects in the peristaltic flow of a Maxwell fluid

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    We analyzed the effect of viscoelasticity on the dynamics of fluids in porous media by studying the flow of a Maxwell fluid in a circular tube, in which the flow is induced by a wave traveling on the tube wall. The present study investigates novelties brought about into the classic peristaltic mechanism by inclusion of non-Newtonian effects that are important, for example, for hydrocarbons. This problem has numerous applications in various branches of science, including stimulation of fluid flow in porous media under the effect of elastic waves. We have found that in the extreme non-Newtonian regime there is a possibility of a fluid flow in the direction {\it opposite} to the propagation of the wave traveling on the tube wall.Comment: to Appear in Phys. Rev. E., 01 September 2001 issu
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