452 research outputs found

    THE SECONDARY ECONOMIC IMPACTS OF IRRIGATION DEVELOPMENT IN WASHINGTON

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    Two potential projects in Washington are examined for their secondary impacts on the economy of the state. A major impact of these projects is to increase the energy costs to regional power consumers. After accounting for the negative impacts of rising energy costs, the long run state level residual income increases by $209 million after irrigating an additional 700,000acres. The distribution of potential benefits is uneven among sectors of the economy and some sectors will possibly experience substantial decreases in returns to stockholder equity as a result of irrigation expansion.Community/Rural/Urban Development, Resource /Energy Economics and Policy,

    AN IRRIGATION MODEL FOR MANAGEMENT OF LIMITED WATER SUPPLIES

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    A two-stage simulation/mathematical programming model is presented for determining the optimal intraseasonal allocation of irrigation water under conditions of limited water supply. The model is applied to a series of water shortage scenarios under both surface and center pivot irrigation. Economically efficient irrigation management is shown to involve the coordination of a number of managerial decisions, including irrigation scheduling, crop substitution, the adoption of improved irrigation labor practices, and idling land. The results indicate that significant opportunities exist for conserving water in the study area under both surface and center pivot irrigation.Crop Production/Industries, Resource /Energy Economics and Policy,

    Experimental and Computational Studies of Ruthenium Complexes Bearing Z-Acceptor Aluminum-Based Phosphine Pincer Ligands

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    Reaction of [Ru(C 6H 4PPh 2) 2(Ph 2PC 6H 4AlMe(THF))H] with CO results in clean conversion to the Ru-Al heterobimetallic complex [Ru(AlMePhos)(CO) 3] (1), where AlMePhos is the novel P-Al(Me)-P pincer ligand (o-Ph 2PC 6H 4) 2AlMe. Under photolytic conditions, 1 reacts with H 2to give [Ru(AlMePhos)(CO) 2(ÎŒ-H)H] (2) that is characterized by multinuclear NMR and IR spectroscopies. DFT calculations indicate that 2 features one terminal and one bridging hydride that are respectively anti and syn to the AlMe group. Calculations also define a mechanism for H 2addition to 1 and predict facile hydride exchange in 2 that is also observed experimentally. Reaction of 1 with B(C 6F 5) 3results in Me abstraction to form the ion pair [Ru(AlPhos)(CO) 3][MeB(C 6F 5) 3] (4) featuring a cationic [(o-Ph 2PC 6H 4) 2Al] +ligand, [AlPhos] +. The Ru-Al distance in 4 (2.5334(16) Å) is significantly shorter than that in 1 (2.6578(6) Å), consistent with an enhanced Lewis acidity of the [AlPhos] +ligand. This is corroborated by a blue shift in both the observed and computed Îœ COstretching frequencies upon Me abstraction. Electronic structure analyses (QTAIM and EDA-ETS) comparing 1, 4, and the previously reported [Ru(ZnPhos)(CO) 3] analogue (ZnPhos = (o-Ph 2PC 6H 4) 2Zn) indicate that the Lewis acidity of these pincer ligands increases along the series ZnPhos &lt; AlMePhos &lt; [AlPhos] +. copy; 2022 American Chemical Society.</p

    Multi-point Assessment of the Kinematics of Shocks (MAKOS): A Heliophysics Mission Concept Study

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    Collisionless shocks are fundamental processes that are ubiquitous in space plasma physics throughout the Heliosphere and most astrophysical environments. Earth's bow shock and interplanetary shocks at 1 AU offer the most readily accessible opportunities to advance our understanding of the nature of collisionless shocks via fully-instrumented, in situ observations. One major outstanding question pertains to the energy budget of collisionless shocks, particularly how exactly collisionless shocks convert incident kinetic bulk flow energy into thermalization (heating), suprathermal particle acceleration, and a variety of plasma waves, including nonlinear structures. Furthermore, it remains unknown how those energy conversion processes change for different shock orientations (e.g., quasi-parallel vs. quasi-perpendicular) and driving conditions (upstream Alfv\'enic and fast Mach numbers, plasma beta, etc.). Required to address these questions are multipoint observations enabling direct measurement of the necessary plasmas, energetic particles, and electric and magnetic fields and waves, all simultaneously from upstream, downstream, and at the shock transition layer with observatory separations at ion to magnetohydrodynamic (MHD) scales. Such a configuration of spacecraft with specifically-designed instruments has never been available, and this white paper describes a conceptual mission design -- MAKOS -- to address these outstanding questions and advance our knowledge of the nature of collisionless shocks.Comment: White paper submitted to the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033; 9 pages, 3 figures, 5 table

    Computation Provides Chemical Insight into the Diverse Hydride NMR Chemical Shifts of [Ru(NHC)<sub>4</sub>(L)H]<sup>0/+</sup> Species (NHC = N-heterocyclic carbene; L = vacant, H<sub>2</sub>, N<sub>2</sub>, CO, MeCN, O<sub>2</sub>, P<sub>4</sub>, SO<sub>2</sub>, H<sup>-</sup>, F<sup>-</sup> and Cl<sup>-</sup>) and their [Ru(R<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>PR<sub>2</sub>)<sub>2</sub>(L)H]<sup>+</sup> Congeners

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    Relativistic density functional theory calculations, both with and without the effects of spin–orbit coupling, have been employed to model hydride NMR chemical shifts for a series of [Ru(NHC)4(L)H]0/+ species (NHC = N-heterocyclic carbene; L = vacant, H2, N2, CO, MeCN, O2, P4, SO2, H−, F− and Cl−), as well as selected phosphine analogues [Ru(R2PCH2CH2PR2)2(L)H]+ (R = iPr, Cy; L = vacant, O2). Inclusion of spin–orbit coupling provides good agreement with the experimental data. For the NHC systems large variations in hydride chemical shift are shown to arise from the paramagnetic term, with high net shielding (L = vacant, Cl−, F−) being reinforced by the contribution from spin–orbit coupling. Natural chemical shift analysis highlights the major orbital contributions to the paramagnetic term and rationalizes trends via changes in the energies of the occupied Ru dπ orbitals and the unoccupied σ*Ru–H orbital. In [Ru(NHC)4(η2-O2)H]+ a ÎŽ-interaction with the O2 ligand results in a low-lying LUMO of dπ character. As a result this orbital can no longer contribute to the paramagnetic shielding, but instead provides additional deshielding via overlap with the remaining (occupied) dπ orbital under the Lz angular momentum operator. These two effects account for the unusual hydride chemical shift of +4.8 ppm observed experimentally for this species. Calculations reproduce hydride chemical shift data observed for [Ru(iPr2PCH2CH2PiPr2)2(η2-O2)H]+ (ÎŽ = −6.2 ppm) and [Ru(R2PCH2CH2PR2)2H]+ (ca. −32 ppm, R = iPr, Cy). For the latter, the presence of a weak agostic interaction trans to the hydride ligand is significant, as in its absence (R = Me) calculations predict a chemical shift of −41 ppm, similar to the [Ru(NHC)4H]+ analogues. Depending on the strength of the agostic interaction a variation of up to 18 ppm in hydride chemical shift is possible and this factor (that is not necessarily readily detected experimentally) can aid in the interpretation of hydride chemical shift data for nominally unsaturated hydride-containing species. The synthesis and crystallographic characterization of the BArF4− salts of [Ru(IMe4)4(L)H]+ (IMe4 = 1,3,4,5-tetramethylimidazol-2-ylidene; L = P4, SO2; ArF = 3,5-(CF3)2C6H3) and [Ru(IMe4)4(Cl)H] are also reported

    Micropallet arrays for the capture, isolation and culture of circulating tumor cells from whole blood of mice engrafted with primary human pancreatic adenocarcinoma

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    Circulating tumor cells (CTCs) are important biomarkers of cancer progression and metastatic potential. The rarity of CTCs in peripheral blood has driven the development of technologies to isolate these tumor cells with high specificity; however, there are limited techniques available for isolating target CTCs following enumeration. A strategy is described to capture and isolate viable tumor cells from whole blood using an array of releasable microstructures termed micropallets. Specific capture of nucleated cells or cells expressing epithelial cell adhesion molecules (EpCAM) was achieved by functionalizing micropallet surfaces with either fibronectin, Matrigel or anti-EpCAM antibody. Surface grafting of poly(acrylic acid) followed by covalent binding of protein A/G enabled efficient capture of EpCAM antibody on the micropallet surface. MCF-7 cells, a human breast adenocarcinoma, were retained on the array surface with 90 ± 8% efficiency when using an anti-EpCAM-coated array. To demonstrate the efficiency of tumor cell retention on micropallet arrays in the presence of blood, MCF-7 cells were mixed into whole blood and added to small arrays (71 mm2) coated with fibronectin, Matrigel or anti-EpCAM. These approaches achieved MCF-7 cell capture from ≀10 ÎŒL of whole blood with efficiencies greater than 85%. Furthermore, MCF-7 cells intermixed with 1 mL blood and loaded onto large arrays (7171 mm2) were captured with high efficiencies (≄97%), could be isolated from the array by a laser-based approach and were demonstrated to yield a high rate of colony formation (≄85%) after removal from the array. Clinical utility of this technology was shown through the capture, isolation and successful culture of CTCs from the blood of mice engrafted with primary human pancreatic tumors. Direct capture and isolation of living tumor cells from blood followed by analysis or culture will be a valuable tool for cancer cell characterization

    Radial Evolution of Thermal and Suprathermal Electron Populations in the Slow Solar Wind from 0.13 to 0.5 au: Parker Solar Probe Observations

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    We develop and apply a bespoke fitting routine to a large volume of solar wind electron distribution data measured by Parker Solar Probe (PSP) over its first five orbits, covering radial distances from 0.13 to 0.5 au. We characterise the radial evolution of the electron core, halo and strahl populations in the slow solar wind during these orbits. The fractional densities of these three electron populations provide evidence for the growth of the combined suprathermal halo and strahl populations from 0.13 to 0.17 au. Moreover, the growth in the halo population is not matched by a decrease of the strahl population at these distances, as has been reported for previous observations at distances greater than 0.3 au. We also find that the halo is negligible at small heliocentric distances. The fractional strahl density remains relatively constant ~1% below 0.2 au, suggesting that the rise in the relative halo density is not solely due to the transfer of strahl electrons into the halo

    Testing the Solar Probe Cup, an Instrument Designed to Touch the Sun

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    Solar Probe Plus will be the first, fastest, and closest mission to the sun, providing the first direct sampling of the sub-Alfvenic corona. The Solar Probe Cup (SPC) is a unique re-imagining of the traditional Faraday Cup design and materials for immersion in this high temperature environment. Sending an instrument of this type into a never-seen particle environment requires extensive characterization prior to launch to establish sufficient measurement accuracy and instrument response. To reach this end, a slew of tests for allowing SPC to see ranges of appropriate ions and electrons, as well as a facility that reproduces solar photon spectra and fluxes for this mission. Having already tested the SPC at flight like temperatures with no significant modification of the noise floor, we recently completed a round of particle testing to see if the deviations in Faraday Cup design fundamentally change the operation of the instrument. Results and implications from these tests will be presented, as well as performance comparisons to cousin instruments such as those on the WIND spacecraft
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