2,176 research outputs found

    A Phase I Cultural Resource Survey for the Proposed Six Mile Boat Ramp Expansion Project (Texas Antiquities Permit #9155)

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    Cultural Resource Analysts, Inc., personnel completed a records review and cultural resource survey for the proposed expansion of the existing Six Mile Boat Ramp in Sabine County, Texas. This work was performed to assist the Sabine River Authority of Texas in complying with Section 106 of the National Historic Preservation Act of 1966 (Public Law 89-665, 16 U.S.C. 470h-2) as an applicant for a Section 404 Clean Water Act Permit from the US Army Corps of Engineers, and the provisions of the Texas Administrative Code regarding archaeological resources on public lands. The Texas Administrative Code requires review of projects on state-owned lands by the Texas Antiquities Commission. The Sabine River Authority of Texas is considered a political subdivision of the State of Texas, and therefore it has a responsibility to provide the Texas Antiquities Commission an opportunity to review projects that may affect potential or designated archaeological sites. This project was performed under Texas Antiquities Permit (No. 9155). All work was performed pursuant to the guidelines published by the Council of Texas Archeologists and adopted by the Texas Historical Commission, and this report was prepared following the short report format in the Guidelines for Cultural Resource Management Reports published by the Council of Texas Archeologists. The current proposed project includes the expansion of the Six Mile Boat Ramp on the Toledo Bend Reservoir in Sabine County, Texas. The proposed development includes the addition of a handicap-accessible floating boat ramp, the clearing of approximately 0.4 ha (1.0 acre) of trees, the construction of a parking area, the addition of a vault toilet, the addition of two tables on concrete platforms, and the clearing of trees along the shoreline to provide an enhanced scenic view. In order to provide some flexibility in siting these facilities, the direct and visual areas of potential effect for this project were within a polygon adhering on its southern and western boundaries to the property line, and roughly buffered to the north and east by the existing shoreline of the Toledo Bend Reservoir. It is estimated that the area of potential effect for this project measures 1.2 ha (3.0 acres), of which approximately 0.9 ha (2.2 acres) could be surveyed, excluding paved surfaces. The records review for this project was conducted on October 18, 2019, prior to the commencement of the field survey, to identify cultural resources or cultural resource investigations previously documented within the area. This file search utilized online files maintained by the Texas Archaeological Research Laboratory at the University of Texas. Additionally, historic maps were examined to identify the locations of any potential historic archaeological sites. The records review indicated that one previously documented site, 41SB58, was located within approximately 50 m (164 ft) to the north of the proposed project area. Additionally, one historic structure was depicted within the project area on historic mapping. Fieldwork was conducted on November 19, 2019, and was completed in 11.5 person hours. The project area was systematically investigated by pedestrian survey and screened shovel tests spaced at a 30 m (98 ft) interval on pedestrian transects spaced at 30 m. The fieldwork for this project resulted in one newly recorded isolated find that is not eligible for designation as a Texas State Archeological Landmark or for listing in the National Register of Historic Places. Based on the findings of this work, it is recommended that the project area be considered cleared from a cultural resource perspective

    An Evaluation of Customer Relationship Management (CRM) Practices among Agribusiness Firms

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    Customer Relationship Management (CRM) has received much attention in the business press as a management process to enhance firm performance. This research highlights differences between groups of respondents who believe their firm's CRM program is performing at a high level, as compared to those not satisfied with the performance of their CRM initiative. Cluster analysis was used to develop a taxonomy of respondents based on their perceived CRM performance. The resulting clusters are then profiled on both demographic variables as well as a core set of activities/behaviors to better understand key differences in the CRM programs of agribusinesses.customer relationship management (CRM), marketing, strategy, information technology, cluster analysis., Agribusiness,

    Third-Generation W(CNAr)₆ Photoreductants (CNAr = Fused-Ring and Alkynyl-Bridged Arylisocyanides)

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    Homoleptic tungsten(0) arylisocyanides possess photophysical and photochemical properties that rival those of archetypal ruthenium(II) and iridium(III) polypyridine complexes. Previous studies established that extending the π-system of 2,6-diisopropylphenylisocyanide (CNDipp) by coupling aryl substituents para to the isocyanide functionality results in W(CNDippAr)₆ oligoarylisocyanide complexes with greatly enhanced metal-to-ligand charge transfer (MLCT) excited-state properties relative to those of W(CNDipp)₆. Extending electronic modifications to delineate additional design principles for this class of photosensitizers, herein we report a series of W(CNAr)₆ compounds with naphthalene-based fused-ring (CN-1-(2-ⁱPr)-Naph) and CNDipp-based alkynyl-bridged (CNDipp^(CC)Ar) arylisocyanide ligands. Systematic variation of the secondary aromatic system in the CNDippCCAr platform provides a straightforward method to modulate the photophysical properties of W(CNDipp^(CC)Ar)₆ complexes, allowing access to an extended range of absorption/luminescence profiles and highly reducing excited states, while maintaining the high molar absorptivity MLCT absorption bands, high photoluminescence quantum yields, and long excited-state lifetimes of previous W(CNAr)₆ complexes. Notably, W(CN-1-(2-iPr)-Naph)₆ exhibits the longest excited-state lifetime of all W(CNAr)₆ complexes explored thus far, highlighting the potential benefits of utilizing fused-ring arylisocyanide ligands in the construction of tungsten(0) photoreductants

    Third-Generation W(CNAr)₆ Photoreductants (CNAr = Fused-Ring and Alkynyl-Bridged Arylisocyanides)

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    Homoleptic tungsten(0) arylisocyanides possess photophysical and photochemical properties that rival those of archetypal ruthenium(II) and iridium(III) polypyridine complexes. Previous studies established that extending the π-system of 2,6-diisopropylphenylisocyanide (CNDipp) by coupling aryl substituents para to the isocyanide functionality results in W(CNDippAr)₆ oligoarylisocyanide complexes with greatly enhanced metal-to-ligand charge transfer (MLCT) excited-state properties relative to those of W(CNDipp)₆. Extending electronic modifications to delineate additional design principles for this class of photosensitizers, herein we report a series of W(CNAr)₆ compounds with naphthalene-based fused-ring (CN-1-(2-ⁱPr)-Naph) and CNDipp-based alkynyl-bridged (CNDipp^(CC)Ar) arylisocyanide ligands. Systematic variation of the secondary aromatic system in the CNDippCCAr platform provides a straightforward method to modulate the photophysical properties of W(CNDipp^(CC)Ar)₆ complexes, allowing access to an extended range of absorption/luminescence profiles and highly reducing excited states, while maintaining the high molar absorptivity MLCT absorption bands, high photoluminescence quantum yields, and long excited-state lifetimes of previous W(CNAr)₆ complexes. Notably, W(CN-1-(2-iPr)-Naph)₆ exhibits the longest excited-state lifetime of all W(CNAr)₆ complexes explored thus far, highlighting the potential benefits of utilizing fused-ring arylisocyanide ligands in the construction of tungsten(0) photoreductants

    Modification of Heme Peptides by Reverse Proteolysis:  Spectroscopy of Microperoxidase-10 with C-Terminal Histidine, Tyrosine, and Methionine Residues

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    Small-molecule analogs of the active sites of heme proteins are under investigation in many laboratories. Covalent attachment of ligands to the porphyrins is often desirable as it reduces complications due to axial ligand dissociation and scrambling in cases involving mixed axial ligation. The preparation of ligand-linked (tailed) porphyrin systems, however, often involves complex multistep syntheses. We have found that trypsin-catalyzed reverse proteolysis provides a simple preparative route to a novel class of water-soluble tailed porphyrins based on the well-characterized microperoxidase (MP) framework. Using reverse proteolysis reactions, we have obtained mutant microperoxidase decapeptides (MP10s) with C-terminal histidine (H23MP10), tyrosine (Y23MP10), and methionine (M23MP10) residues. In addition, we have investigated the electronic absorption and resonance Raman spectra of these MP10 mutants

    The NASA-UC Eta-Earth Program: II. A Planet Orbiting HD 156668 with a Minimum Mass of Four Earth Masses

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    We report the discovery of HD 156668b, an extrasolar planet with a minimum mass of M_P sin i = 4.15 M_Earth. This planet was discovered through Keplerian modeling of precise radial velocities from Keck-HIRES and is the second super-Earth to emerge from the NASA-UC Eta-Earth Survey. The best-fit orbit is consistent with circular and has a period of P = 4.6455 d. The Doppler semi-amplitude of this planet, K = 1.89 m/s, is among the lowest ever detected, on par with the detection of GJ 581e using HARPS. A longer period (P ~ 2.3 yr), low-amplitude signal of unknown origin was also detected in the radial velocities and was filtered out of the data while fitting the short-period planet. Additional data are required to determine if the long-period signal is due to a second planet, stellar activity, or another source. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 156668 (an old, quiet K3 dwarf) is photometrically constant over the radial velocity period to 0.1 mmag, supporting the existence of the planet. No transits were detected down to a photometric limit of ~3 mmag, ruling out transiting planets dominated by extremely bloated atmospheres, but not precluding a transiting solid/liquid planet with a modest atmosphere.Comment: This planet was announced at the 2010 AAS meeting in Wash. DC; 12 pages, 8 figures, 3 tables, submitted to Ap

    The NASA-UC Eta-Earth Program: III. A Super-Earth orbiting HD 97658 and a Neptune-mass planet orbiting Gl 785

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    We report the discovery of planets orbiting two bright, nearby early K dwarf stars, HD 97658 and Gl 785. These planets were detected by Keplerian modelling of radial velocities measured with Keck-HIRES for the NASA-UC Eta-Earth Survey. HD 97658 b is a close-in super-Earth with minimum mass Msini = 8.2 +/- 1.2 M_Earth, orbital period P = 9.494 +/- 0.005 d, and an orbit that is consistent with circular. Gl 785 b is a Neptune-mass planet with Msini = 21.6 +/- 2.0 M_Earth, P = 74.39 +/- 0.12 d, and orbital eccentricity 0.30 +/- 0.09. Photometric observations with the T12 0.8 m automatic photometric telescope at Fairborn Observatory show that HD 97658 is photometrically constant at the radial velocity period to 0.09 mmag, supporting the existence of the planet.Comment: Submitted to ApJ, 7 pages, 6 figures, 5 table

    Manganese Microperoxidase-8

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    Demetalation of Fe(III) microperoxidase-8 (MP8) by anhydrous HF gives metal-free MP8, a convenient starting material for a wide variety of metal-substituted MP8 derivatives, including Mn(III)MP8. Mn(III)MP8 was produced by treatment of metal-free MP8 with manganous acetate in aerated aqueous solution; it was characterized by mass spectrometry and UV−visible absorption spectroscopy. Resonance Raman spectra suggest that Mn(III)MP8 contains histidine and water axial ligands at neutral pH. The Mn(IV)=O derivative is readily prepared by oxidation of Mn(III)MP8 with hydrogen peroxide or Ru(bpy)_3^(3+) (bpy = 2,2‘-bipyridine)

    Photoswitchable Luminescence of Rhenium(I) Tricarbonyl Diimines

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    The synthesis, characterization, and X-ray crystal structures of [Re(diimine)(CO)_3(dpe)](PF_6) (dpe = 1,2-di(4-pyridyl)ethylene) compounds are reported. The cis-dpe complexes exhibit yellow luminescence after UV excitation, whereas the trans-dpe counterparts are nonluminescent. The luminescence quantum yields of the cis-dpe complexes are strongly dependent on the identity of the diimine ligand. Irradiation (350 nm) of the trans-dpe complexes induces trans → cis dpe-ligand isomerization with quantum yields on the order of 0.2, and this process leads to an on-switching of yellow luminescence. After long 350-nm irradiation times, a steady state composed of roughly 70% cis- and 30% trans-dpe complexes is reached. The reverse cis → trans photoisomerization reaction is induced by irradiating the cis-dpe complexes at 250 nm, switching off the yellow luminescence. For 250-nm excitation, photodecomposition of the [Re(diimine)(CO)_3(dpe)]^+ complexes competes efficiently with photoisomerization

    Generation of Powerful Tungsten Reductants by Visible Light Excitation

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    The homoleptic arylisocyanide tungsten complexes, W(CNXy)_6 and W(CNIph)_6 (Xy = 2,6-dimethylphenyl, Iph = 2,6-diisopropylphenyl), display intense metal to ligand charge transfer (MLCT) absorptions in the visible region (400–550 nm). MLCT emission (λ_max ≈ 580 nm) in tetrahydrofuran (THF) solution at rt is observed for W(CNXy)6 and W(CNIph)_6 with lifetimes of 17 and 73 ns, respectively. Diffusion-controlled energy transfer from electronically excited W(CNIph)_6 (*W) to the lowest energy triplet excited state of anthracene (anth) is the dominant quenching pathway in THF solution. Introduction of tetrabutylammonium hexafluorophosphate, [Bun4N][PF_6], to the THF solution promotes formation of electron transfer (ET) quenching products, [W(CNIph)6]+ and [anth]^•–. ET from *W to benzophenone and cobalticenium also is observed in [Bun4N][PF6]/THF solutions. The estimated reduction potential for the [W(CNIph)6]^(+)/*W couple is −2.8 V vs Cp_(2)Fe^(+/0), establishing W(CNIph)_6 as one of the most powerful photoreductants that has been generated with visible light
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