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71.
Yang UK Adams T Alton A Arroyo CG Avvakumov S de Barbaro L de Barbaro P Bazarko AO Bernstein RH Bodek A Bolton T Brau J Buchholz D Budd H Bugel L Conrad J Drucker RB Fleming BT Formaggio JA Frey R Goldman J Goncharov M Harris DA Johnson RA Kim JH King BJ Kinnel T Koutsoliotas S Lamm MJ Marsh W Mason D McFarland KS McNulty C Mishra SR Naples D Nienaber P Romosan A Sakumoto WK Schellman H Sciulli FJ Seligman WG Shaevitz MH Smith WH Spentzouris P Stern EG Suwonjandee N Vaitaitis A Vakili M Yu J 《Physical review letters》2001,86(13):2742-2745
We report on the extraction of the structure functions F2 and DeltaxF(3) = xF(nu)(3)-xF(nu;)(3) from CCFR nu(mu)-Fe and nu;(mu)-Fe differential cross sections. The extraction is performed in a physics model-independent (PMI) way. This first measurement of DeltaxF(3), which is useful in testing models of heavy charm production, is higher than current theoretical predictions. The ratio of the F2 (PMI) values measured in nu(mu) and mu scattering is in agreement (within 5%) with the predictions of next-to-leading-order parton distribution functions using massive charm production schemes, thus resolving the long-standing discrepancy between the two sets of data. 相似文献
72.
Etiënne L. M. Vermeirssen Conrad Dietschweiler Beate I. Escher Jürgen van der Voet Juliane Hollender 《Analytical and bioanalytical chemistry》2013,405(15):5225-5236
The Chemcatcher passive sampler, which uses Empore? disks as sampling phase, is frequently used to monitor polar organic chemicals in river water and effluents. Uptake kinetics need to be quantified to calculate time-weighted average concentrations from Chemcatcher field deployments. Information on release kinetics is needed if performance reference compounds (PRCs) are used to quantify the influence of environmental conditions on the uptake. In a series of uptake and elimination experiments, we used Empore? SDB disks (poly(styrenedivinylbenzene) copolymer modified with sulfonic acid groups) as a sampling phase and 22 compounds with a logK ow (octanol–water partitioning coefficient) range from ?2.6 to 3.8. Uptake experiments were conducted in river water or tap water and lasted up to 25 days. Only 1 of 22 compounds (sulfamethoxazole) approached equilibrium in the uptake trials. Other compounds showed continuing non-linear uptake, even after 25 days. All compounds could be released from SDB disks, and desorption was proportionally higher in disks loaded for shorter periods. Desorption showed two-phase characteristics, and desorption was proportionally higher for passively sorbed compounds compared to actively loaded compounds (active loading was performed by pulling spiked river water over SDB disks using vacuum). We hypothesise that the two-phase kinetics and better retention of actively loaded compounds—and compounds loaded for a longer period—may be caused by slow diffusion of chemicals within the polymer. As sorption and desorption did not show isotropic kinetics, it is not possible to develop robust PRCs for adsorbent material like SDB disks. 相似文献
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John Conrad Merkel 《Journal of Dynamics and Differential Equations》2008,20(3):653-668
In the spirit of Palmore and Pacella, Morse Theory is used to obtain a lower bound for the number of central configurations
in the spatial N-body problem. The homology of the configuration ellipsoid with the collision and collinear manifolds removed and the SO(3) symmetry quotiented out is calculated. As intermediate steps, homology calculations are carried out for several additional
manifolds naturally arising in the N-body problem. 相似文献
75.
Dr. Jacy K. Conrad Prof. Aliaksandra Lisouskaya Prof. Stephen P. Mezyk Prof. David M. Bartels 《Chemphyschem》2023,24(24):e202300465
The reactivity of chromium(III) species with the major oxidizing and reducing radiolysis products of water was investigated in aqueous solutions at temperatures up to 150 °C. The reaction between the hydrated electron (eaq−) and Cr(III) species showed a positive temperature dependence over this temperature range. The reaction was also studied in pH 2.5 and 3.5 solutions for the first time. This work also studied the reaction between acidic Cr(III) species and the hydroxyl radical (⋅OH). It was found that Cr3+ did not react significantly with the ⋅OH radical, but the first hydrolysis species, Cr(OH)2+, did with a rate coefficient of k= (7.2±0.3)×108 M−1 s−1 at 25 °C. The oxidation of Cr(OH)2+ by the ⋅OH radical formed an absorbing product species that ultimately oxidized to give Cr(VI). These newly measured reaction rates allow for the development of improved models of aqueous chromium speciation for the effective remediation of liquid high-level nuclear waste via vitrification processes. 相似文献
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Andreas Baumeler Walter Brade Andreas Haag Conrad Hans Eugster 《Helvetica chimica acta》1990,73(3):700-715
Synthesis of Optically Pure Grasshopper Ketone and of Its Diastereoisomers and Related Compounds Starting from our previously described synthon 1 , the synthesis of four enantiomerically pure grasshopper ketons (diastereoisomeric 4-(2′,4′-dihydroxy-2′,6′,6′-trimethylcyclohexylidene)but-3-en-2-ons) and of their oxo derivatives was performed. Spectral and chiroptical data are presented. 相似文献
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