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71.
Bergeron Denis E. Mumm H. P. Tyra M. A. 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(2):767-771
Journal of Radioanalytical and Nuclear Chemistry - Liquid scintillation cocktails loaded with neutron capture agents such as 6Li are used in both neutron and neutrino detectors. For detectors... 相似文献
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We prove that the pre-Lie operad is a free non-symmetric operad. 相似文献
76.
Marcelo Aguiar Carlos André Carolina Benedetti Nantel Bergeron Zhi Chen Persi Diaconis Anders Hendrickson Samuel Hsiao I. Martin Isaacs Andrea Jedwab Kenneth Johnson Gizem Karaali Aaron Lauve Tung Le Stephen Lewis Huilan Li Kay Magaard Eric Marberg Mike Zabrocki 《Advances in Mathematics》2012,229(4):2310-2337
We identify two seemingly disparate structures: supercharacters, a useful way of doing Fourier analysis on the group of unipotent uppertriangular matrices with coefficients in a finite field, and the ring of symmetric functions in noncommuting variables. Each is a Hopf algebra and the two are isomorphic as such. This allows developments in each to be transferred. The identification suggests a rich class of examples for the emerging field of combinatorial Hopf algebras. 相似文献
77.
Bélanger G Larouche-Gauthier R Ménard F Nantel M Barabé F 《The Journal of organic chemistry》2006,71(2):704-712
[reaction: see text] Vilsmeier-Haack type cyclizations proved to be particularly efficient for generating parts of the polycyclic cores of many alkaloids, although only monocyclizations have so far been reported. With the goal of rapidly and efficiently constructing polycyclic alkaloids, we decided to exploit the Vilsmeier-Haack reaction by utilizing iminium ions successively generated and trapped with tethered nucleophiles. To develop such a strategy, we had to set the first cyclization. This constitutes a great challenge in itself because amide activation conditions are usually not compatible with tethered nucleophiles, except for indoles and aromatic rings which have already been reported. This paper describes the comprehensive study of intramolecular addition of silyl enol ethers, allylsilanes, and enamines to chemoselectively activated formamides, aliphatic amides, and lactams. Good to excellent yields were obtained for the 5-exo, 6-exo, and 6-endo modes of cyclization. Moreover, we demonstrated that the species in solution after the cyclization are iminium ions. This is highly encouraging for the development of bis-cyclization strategies. An expeditious total synthesis of (+/-)-tashiromine is also reported. 相似文献
78.
Higgins GT Bergeron BV Hasselmann GM Farzad F Meyer GJ 《The journal of physical chemistry. B》2006,110(6):2598-2605
The yields and dynamics for energy transfer from the metal-to-ligand charge-transfer excited states of Ru(deeb)(bpy)(2)(PF(6))(2), Ru(2+), and Os(deeb)(bpy)(2)(PF(6))(2), Os(2+), where deeb is 4,4'-(CH(3)CH(2)CO(2))(2)-2,2'-bipyridine, anchored to mesoporous nanocrystalline (anatase) TiO(2) thin films were quantified. Lateral energy transfer from Ru(2+)* to Os(2+) was observed, and the yields were measured as a function of the relative surface coverage and the external solvent environment (CH(3)CN, THF, CCl(4), and hexanes). Excited-state decay of Ru(2+)*/TiO(2) was well described by a parallel first- and second-order kinetic model, whereas Os(2+)*/TiO(2) decayed with first-order kinetics within experimental error. The first-order component was assigned to the radiative and nonradiative decay pathways (tau = 1 micros for Ru(2+)*/TiO(2) and tau = 50 ns for Os(2+)*/TiO(2)). The second-order component was attributed to intermolecular energy transfer followed by triplet-triplet annihilation. An analytical model was derived that allowed determination of the fraction of excited-states that follow the two pathways. The fraction of Ru(2+)*/TiO(2) that decayed through the second-order pathway increased with surface coverage and excitation intensity. Monte Carlo simulations were performed to estimate the Ru(2+)* --> Ru(2+) intermolecular energy transfer rate constant of (30 ns)(-1). 相似文献
79.
In the first part of this Note, we show that the first non-zero eigenvalue of the Laplace operator on 1-forms of a standard congruence arithmetic complex hyperbolic n-manifold is always . The following parts of this Note concern homological applications of this result. We prove, in particular, that if Sh0H?Sh0G are two Shimura varieties of type U(n?1,1) and U(n,1), the natural map H2n?3(Sh0H)→H2n?3(Sh0G) is injective, first step of a “Lefschetz theorem” for Shimura varieties. To cite this article: N. Bergeron, L. Clozel, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 995–998. 相似文献
80.
Shivani Garapaty-Rao Christopher Nasveschuk Alexandre Gagnon Eric Y. Chan Peter Sandy Jennifer Busby Srividya Balasubramanian Robert Campbell Feng Zhao Louise Bergeron James E. Audia Brian K. Albrecht Jean-Christophe Harmange Richard Cummings Patrick Trojer 《Chemistry & biology》2013,20(11):1329-1339
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