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A computerized method is given for the evaluation of Arrhenius parameters which describe the chemiluminescent decomposition of tetramethyl-1,2-dioxetane. The parameters were determined in several solvents by linear regression methods and the equation ln ln \documentclass{article}\pagestyle{empty}\begin{document}$ [(\sum\nolimits_0^\infty I - \sum\nolimits_0^t I)/(\sum\nolimits_0^\infty I - \sum\nolimits_0^t I - \sum\nolimits_0^{t + \Delta t} I)] = \ln\, (A_1 \Delta t) - E_1 /RT$\end{document}, where I refers to photons counted by increments of Δt, and E1 and A are the first-order Arrhenius parameters. The average of E1 and log A1 (s?1) from this method from six runs in CCl4 with initial concentrations of 4.9 × 10?5-8.45 × 10?4M were 27.21 ± 0.88 kcal/mol (113.7 ± 3.7 kJ/mol) and 13.88 ± 0.50, respectively. Simulated curves of chemiluminescence versus time were obtained with the use of a computer program and an auxiliary plotter. 相似文献
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Holographic interferometry has often been used to determine the natural frequencies and the associated mode patterns of vibrating objects with rigidly fixed or stationary boundaries. This paper describes a new pulse-laser holographic technique whereby the vibration-mode patterns of a rotating propeller blade were determined. This technique consists of rotating the holographic plate on the same axis as the rotating object and using spherically symmetric wavefronts for object and reference beams. 相似文献
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1,2-dideuterio-cyclohexene, 1,2-dideuterio-cyclooctene, and trans-3,4-dideuterio-hex-3-ene were reacted with three >NO* radicals: 4-hydroxyTempo, di-tert-butyliminoxyl, both used as the actual radicals, and phthalimide-N-oxyl (PINO) generated from N-hydroxyphthalimide (NHPI) by its reaction with tert-alkoxyl radicals (t-RO*) and with lead tetraacetate. In all cases, except the NHPI/Pb(OAc)4 system, only mono >NO-substituted alkenes were produced. The 2H NMR spectra imply that 88-92% of monoadducts were formed by the initial abstraction of an allylic H-atom, followed by capture of the allylic radical by a second >NO*, while the remaining 12-8% appear to be formed by an initial addition of >NO* to the double bond followed by H-atom abstraction by a second >NO*. A substantial and sometimes the major product formed with the NHPI/Pb(OAc)4 system has two PINO moieties added across the double bond. Since such diadducts are not formed with the NHPI/t-RO* system, a heterolytic mechanism is proposed, analogous to that known for the Pb(OAc)4-induced acetoxylation of alkenes. A detailed analysis of the NHPI/Pb(OAc)4/alkene products indicates that monosubstitution occurs by both homolytic and heterolytic processes. 相似文献
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Liu J Mendenhall MP Holley AT Back HO Bowles TJ Broussard LJ Carr R Clayton S Currie S Filippone BW García A Geltenbort P Hickerson KP Hoagland J Hogan GE Hona B Ito TM Liu CY Makela M Mammei RR Martin JW Melconian D Morris CL Pattie RW Pérez Galván A Pitt ML Plaster B Ramsey JC Rios R Russell R Saunders A Seestrom SJ Sondheim WE Tatar E Vogelaar RB VornDick B Wrede C Yan H Young AR;UCNA Collaboration 《Physical review letters》2010,105(18):181803
A precise measurement of the neutron decay β asymmetry A? has been carried out using polarized ultracold neutrons from the pulsed spallation ultracold neutron source at the Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report A? = -0.119?66±0.000?89{-0.001?40}{+0.001?23}, from which we determine the ratio of the axial-vector to vector weak coupling of the nucleon g{A}/g{V}=-1.275?90{-0.004?45}{+0.004?09}. 相似文献
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David D. Morgan Charles L. Mendenhall Albert M. Bobst Susan D. Rouster 《Photochemistry and photobiology》1985,42(1):93-94
Abstract— The incorporation of four different spin traps into cultured fetal mouse liver cells was investigated using electron spin resonance spectroscopy. The cells were incubated in saline solutions of the traps, washed, and then irradiated in a saline solution containing hydrogen peroxide. The presence of a reproducible ESR signal was taken as evidence of spin trap incorporation. The spin trap DMPO was found to be incorporated, while PBN and 4-POBN were not. MNP was toxic to the cells. 相似文献
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Decomposition of (R1R2CXON=)2 (R1 = R2 = Ph; R1 = R2 = p? ClC6H4; R1 = Ph, R2 = CH3; X = H or D) in hydrocarbon solvents at 31–75°C afforded R1R2CO in 6–8% lower yield when X = D than when X = H. This result is ascribed to cage escape of secondary alkoxyl radicals in competition with dismutation. Deuterium isotope effects for alkoxyl cage dismutation of 1.35–2.4 are estimated from the data. It is suggested that this same competition may account for the experimentally slower termination rate constants in solution of primary and secondary alkylperoxyl radicals on α-deuteration. 相似文献