452 research outputs found
THE SECONDARY ECONOMIC IMPACTS OF IRRIGATION DEVELOPMENT IN WASHINGTON
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
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
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) Ă
) is significantly shorter than that in 1 (2.6578(6) Ă
), consistent with an enhanced Lewis acidity of the [AlPhos] +ligand. This is corroborated by a blue shift in both the observed and computed Μ 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 < AlMePhos < [AlPhos] +. copy; 2022 American Chemical Society.</p
Multi-point Assessment of the Kinematics of Shocks (MAKOS): A Heliophysics Mission Concept Study
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
Relativistic density functional theory calculations, both with and without the effects of spinâorbit 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, Hâ, Fâ and Clâ), as well as selected phosphine analogues [Ru(R2PCH2CH2PR2)2(L)H]+ (R = iPr, Cy; L = vacant, O2). Inclusion of spinâorbit 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, Clâ, Fâ) being reinforced by the contribution from spinâorbit 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 dÏ orbitals and the unoccupied Ï*RuâH orbital. In [Ru(NHC)4(η2-O2)H]+ a ÎŽ-interaction with the O2 ligand results in a low-lying LUMO of dÏ 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) dÏ 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 = â6.2 ppm) and [Ru(R2PCH2CH2PR2)2H]+ (ca. â32 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 â41 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 BArF4â 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
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Solar Energetic Particles Produced by a Slow Coronal Mass Ejection at âŒ0.25 au
We present an analysis of Parker Solar Probe (PSP) ISâIS observations of ~30â300 keV nâ»Âč ions on 2018 November 11 when PSP was about 0.25 au from the Sun. Five hours before the onset of a solar energetic particle (SEP) event, a coronal mass ejection (CME) was observed by STEREO-A/COR2, which crossed PSP about a day later. No shock was observed locally at PSP, but the CME may have driven a weak shock earlier. The SEP event was dispersive, with higher energy ions arriving before the lower energy ones. Timing suggests the particles originated at the CME when it was at ~7.4R_â. SEP intensities increased gradually from their onset over a few hours, reaching a peak, and then decreased gradually before the CME arrived at PSP. The event was weak, having a very soft energy spectrum (â4 to â5 spectral index). The earliest arriving particles were anisotropic, moving outward from the Sun, but later, the distribution was observed to be more isotropic. We present numerical solutions of the Parker transport equation for the transport of 30â300 keV nâ»Âč ions assuming a source comoving with the CME. Our model agrees well with the observations. The SEP event is consistent with ion acceleration at a weak shock driven briefly by the CME close to the Sun, which later dissipated before arriving at PSP, followed by the transport of ions in the interplanetary magnetic field
Micropallet arrays for the capture, isolation and culture of circulating tumor cells from whole blood of mice engrafted with primary human pancreatic adenocarcinoma
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 â€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 (â„97%), could be isolated from the array by a laser-based approach and were demonstrated to yield a high rate of colony formation (â„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
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
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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