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| Registros recuperados: 601 | |
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| Oh-Hoon Kwon; Omar F. Mohammed. |
| In continuation of comments by Catalán, the latest here questions the steady-state emission spectra of 7-azaindole, and hence the validity of non-concerted proton transfer. In this comment, we show that his results are at fault and not supportive of his claims. We provide possible causes of the misleading claims, including the contamination of the solvent with water moisture. We conclude by calling for an end to such practice, which is counter productive, as it does not follow the scholarly approach of science. |
| Tipo: Manuscript |
Palavras-chave: Chemistry. |
| Ano: 2008 |
URL: http://precedings.nature.com/documents/2522/version/1 |
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| Sierra Rayne; Kaya Forest. |
| Gas phase standard state (298.15 K, 1 atmosphere) relative enthalpies and free energies of formation were calculated for all mono- through hepta-halogenated (X=F, Cl, Br) anthraquinone congeners using the B3LYP, BHandHLYP, M062X, PBE0, and B97D density functionals with the 6-311++G(d,p) basis set. All levels of theory yielded similar results with strong intra- and inter-method correlations for both the relative enthalpy and free energy values and the corresponding thermodynamic stability rank. Within each homolog group, the most thermodynamically stable isomers are those which maximize substitution at the lateral positions (2, 3, 7, and 8) versus the less stabilizing peri positions (1, 4, 6, and 9), while also minimizing destabilizing adjacent substitution... |
| Tipo: Manuscript |
Palavras-chave: Chemistry. |
| Ano: 2010 |
URL: http://precedings.nature.com/documents/5153/version/1 |
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| Sierra Rayne; Kaya Forest. |
| A systematic and comprehensive semiempirical, Hartree-Fock (HF) ab initio, and B3LYP density functional theory (DFT) study was conducted on the relative thermodynamic properties of various linear and branched perfluorinated and perhydrogenated alkyl compounds. The semiempirical AM1, PM3, and PM6 methods all consistently and accurately predict that branched alkyl compounds will generally be more thermodynamically stable than their linear counterparts. In contrast, HF and B3LYP calculations with the 6-31G(d,p), 6-31++G(d,p), and 6-311++G(d,p) basis sets predict that linear isomers will be more stable than branched analogs. These different linear versus branched perfluoroalkyl/perhydroalkyl thermodynamic property trends between semiempirical and ab initio/DFT... |
| Tipo: Manuscript |
Palavras-chave: Chemistry; Earth & Environment. |
| Ano: 2009 |
URL: http://precedings.nature.com/documents/3928/version/1 |
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| Sierra Rayne; Kaya Forest. |
| Gas to solution phase Gibbs free energies of solvation at 298.15 K for transfer of six representative combustion flue gas compounds (N~2~, O~2~, CO~2~, H~2~O, SO~2~, and CO) were calculated at the Gaussian-4 (G4) level of theory using the IEFPCM-UFF, CPCM, and SMD implicit solvent models for 178 organic solvents. The IEFPCM-UFF and CPCM models yield similar free energies of solvation for all six compounds in each of the solvents considered, having maximum absolute intra-solvent deviations <1.6 kJ mol^-1^. Substantial free energy of solvation differences were observed between the IEFPCM-UFF/CPCM and SMD models, with maximum absolute intra-solvent deviations up to 45.5 kJ mol^-1^. The IEFPCM-UFF and CPCM models displayed strong free energy of... |
| Tipo: Manuscript |
Palavras-chave: Chemistry. |
| Ano: 2010 |
URL: http://precedings.nature.com/documents/5227/version/1 |
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| Sierra Rayne; Kaya Forest. |
| The gas and solution phase relative thermodynamic stabilities of the 89 perfluorooctane sulfonic acid (PFOS) congeners play an important role in assessing whether synthetic conditions for commercial mixtures are under thermodynamic or kinetic control, and in calculating various physico-chemical properties for these important industrial compounds and environmental contaminants. In the present study, 4,272 gas and solvent phase (water and n-octanol) calculations were conducted at various levels of semiempirical (PM6), density functional (B3LYP, B97D, PBE1PBE [PBE0], and M062X functionals with the 6-311++G(d,p) basis set), and second order Moller-Plesset perturbation (MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p)) theory and the SMD, IEFPCM-UFF, and CPCM implicit... |
| Tipo: Manuscript |
Palavras-chave: Chemistry. |
| Ano: 2010 |
URL: http://precedings.nature.com/documents/5353/version/1 |
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| Sierra Rayne; Kaya Forest. |
| The gas and solution phase relative thermodynamic stabilities of the 39 linear and branched perfluorooctanoic acid (PFOA) congeners in both their acid and anionic forms were calculated at various levels of density functional (B3LYP, wB97XD, and M062X functionals with the 6-311++G(d,p) basis set) and second order Moller-Plesset perturbation (MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p)) theory using the SMD implicit solvation model. The B3LYP functional does not accurately model the expected trends in thermodynamic stability of PFOA isomers with linear versus branched perfluoroalkyl chains. Calculations obtained with the M062X and MP2 model chemistries suggest these theoretical methods may be more appropriate for relative thermodynamic stability studies on... |
| Tipo: Manuscript |
Palavras-chave: Chemistry. |
| Ano: 2011 |
URL: http://precedings.nature.com/documents/5528/version/1 |
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| Lehrsch, G.A.; Kincaid, D.C.. |
| Dairy manure increases the yields of dry bean (Phaseolus vulgaris L.) and spring wheat (Triticum aestivum L.) from eroded, furrow-irrigated soils and may increase corn (Zea mays L.) silage yield from steeper eroded areas under sprinkler irrigation. In a 2-year field study in southern Idaho on Portneuf silt loam (coarse silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid), the effects of a one-time, fall application of 29 or 72 Mg ha-1 of dry manure or 22 or 47 Mg ha21 of dry compost on subsequent silage yield and nitrogen (N) uptake from previously eroded, sprinkler-irrigated hill slopes were evaluated. In October 1999, stockpiled or composted dairy manure was disked to a depth of 0.15 m into plots with slopes from 0.8 to 4.4%. After... |
| Tipo: Article |
Palavras-chave: Corn / maize; Corn; Composted manure; Chemistry; Fertilizer; Mass Import - autoclassified (may be erroneous). |
| Ano: 2007 |
URL: http://eprints.nwisrl.ars.usda.gov/66/1/1230.pdf |
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| Michael J. Bucknum. |
| [alpha]-Ca3N2 as an opaque, red-brown crystalline powder lying in the cubic Ia-3 space group, was placed into a specially designed glove box under nitrogen atmosphere, along with powdered f.c.c. Au, and carefully loaded within the [beta]-brass gasket of a conventional high pressure diamond anvil cell (DAC). The powdered samples were then sealed under nitrogen atmosphere to a pressure of 8.40 Kb and taken to Cornell High Energy Synchrotron Source where conventional
Debeye-Scherrer diffraction photographs were recorded at 8.40, 91.0 and 137 Kb. The pressure of the sample was monitored by using the equation of state of Au, and no phase change from the Ia-3 structure was observed in the sample of powdered [alpha]-Ca3N2 up to a pressure of 137... |
| Tipo: Manuscript |
Palavras-chave: Chemistry. |
| Ano: 2008 |
URL: http://precedings.nature.com/documents/1771/version/4 |
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| Sierra Rayne. |
| Melatonin and serotonin are important phytochemicals with hormonal, antioxidant, immunoactive, and neuroactive biological properties, and have been identified and quantitated in a broad range of fruits, vegetables, and derivative products. Relatively little is known about the temporal profiles of these compounds during fruit and vegetable development. Improved knowledge in this area would help guide our understanding of fundamental plant physiology, as well as potentially facilitate better control of melatonin and serotonin concentrations and relative abundances in functional foods. The current work synthesizes the current state-of-the-art regarding the presence and trends of these compounds during fruit and vegetable development. The literature reflects... |
| Tipo: Manuscript |
Palavras-chave: Chemistry. |
| Ano: 2010 |
URL: http://precedings.nature.com/documents/4722/version/1 |
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| Registros recuperados: 601 | |
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