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101.
Hanessian S Margarita R Hall A Johnstone S Tremblay M Parlanti L 《Journal of the American Chemical Society》2002,124(45):13342-13343
The structure and absolute configuration of the marine antithrombotic product dysinosin A was confirmed by total synthesis. The strategy involved disconnections to three subunits, of which two were synthesized from the readily available l-glutamic acid, d-leucine, and d-mannitol. The Grubbs olefin metathesis carbocyclization reaction was utilized to prepare two intermediates. 相似文献
102.
Dickerson TJ Tremblay MR Hoffman TZ Ruiz DI Janda KD 《Journal of the American Chemical Society》2003,125(50):15395-15401
A conformationally constrained hapten is presented that is capable of catalyzing the first antibody-mediated photo-Fries rearrangement. In this reaction, absorption of light energy by a diphenyl ether substrate results in homolytic C-O bond cleavage followed by recombination to yield biphenyl-derived products. The most proficient antibody studied converts 4-phenoxyaniline 15 into 2-hydroxy-5-aminobiphenyl 16 under high-intensity irradiation at a rate of 8.6 microM/min. These results support a recent hypothesis stating that immunization with conformationally constrained haptens provides higher titers for the acquisition of simple binding antibodies; however, in this case, conformational constraint does not ensure the development of more efficient catalysts. Using the obtained antibodies, the presence of products resulting from escape of free radicals from the solvent cage can be suppressed, altering the excited state energy surface such that free radicals are funneled into the formation of the desired biphenyl product. However, studies also show the inactivation of the antibodies as a result of photodecay of the biphenyl product. Using an isocyanate scavenging resin, the photodecay product could be removed and the inactivation of the antibody drastically reduced. Furthermore, despite the observed photodecay, turnover of the antibody was present; this represents the first case in which true turnover of a photochemical reaction using a catalytic antibody could be observed. 相似文献
103.
104.
Deanna de Marcano Bernardo Mndez Henry Parada Aníbal Rojas 《Magnetic resonance in chemistry : MRC》1981,16(4):314-315
The 13C NMR spectra were determined and signals assigned to the various carbons of veratridine and cevadine. 相似文献
105.
106.
107.
A method is presented for calculating the Lie point symmetries of difference equations with one, or several, independent variables.
The equations are given on a priori specified lattices. The Lie transformations act on the lattice, as well as on the equation.
The transformations take solutions into solutions and can be used to perform symmetry reduction.
Presented by P. Winternitz at the DI-CRM Workshop held in Prague, 18–21 June 2000.
This article was written while S.T. and P.W. were visiting the Dipartimento di Fisica, Università di Roma Tre. They thank
the Dipartimento, the INFN and the Agreement Università di Roma Tre — Université de Montréal for their support. The research
of P.W. was partly supported by a research grant from NSERC of Canada. 相似文献
108.
Noah J. Tremblay Alon A. Gorodetsky Dr. Marshall P. Cox Theanne Schiros Dr. Bumjung Kim Rachel Steiner Zachary Bullard Aaron Sattler Woo‐Young So Dr. Yoshimitsu Itoh Dr. Michael F. Toney Dr. Hirohito Ogasawara Dr. Arthur P. Ramirez Prof. Ioannis Kymissis Dr. Michael L. Steigerwald Dr. Colin Nuckolls Prof. 《Chemphyschem》2010,11(4):799-803
109.
Larivière D Tremblay M Durand-Jézéquel M Tolmachev S 《Analytical and bioanalytical chemistry》2012,403(2):409-418
This article describes a robust methodology using the combination of instrumental design (high matrix interface—HMI), sample
dilution and internal standardization for the quantification of beryllium (Be) in various digested autopsy tissues using inductively
coupled plasma mass spectrometry. The applicability of rhodium as a proper internal standard for Be was demonstrated in three
types of biological matrices (i.e., femur, hair, lung tissues). Using HMI, it was possible to achieve instrumental detection
limits and sensitivity of 0.6 ng L−1 and 157 cps L ng−1, respectively. Resilience to high salt matrices of the HMI setup was also highlighted using bone mimicking solution ([Ca2+] = 26 to 1,400 mg L−1), providing a 14-fold increase in tolerance and a 2.7-fold decrease in method detection limit compared to optimized experimental
conditions obtained without the HMI configuration. Precision of the methodology to detect low levels of Be in autopsy samples
was demonstrated using hair and blood certified reference materials. Be concentration ranging from 0.015 to 255 μg kg−1 in autopsy samples obtained from the U.S. Transuranium and Uranium Registries were measured using the methodology presented. 相似文献
110.
Jean-François Lemieux Dana A. Knoll Bruno Tremblay David M. Holland Martin Losch 《Journal of computational physics》2012,231(17):5926-5944
Numerical convergence properties of a recently developed Jacobian-free Newton–Krylov (JFNK) solver are compared to the ones of the widely used EVP model when solving the sea ice momentum equation with a Viscous-Plastic (VP) formulation. To do so, very accurate reference solutions are produced with an independent Picard solver with an advective time step of 10 s and a tight nonlinear convergence criterion on 10, 20, 40, and 80-km grids. Approximate solutions with the JFNK and EVP solvers are obtained for advective time steps of 10, 20 and 30 min. Because of an artificial elastic term, the EVP model permits an explicit time-stepping scheme with a relatively large subcycling time step. The elastic waves excited during the subcycling are intended to damp out and almost entirely disappear such that the approximate solution should be close to the VP solution. Results show that residual elastic waves cause the EVP approximate solution to have notable differences with the reference solution and that these differences get more important as the grid is refined. Compared to the reference solution, additional shear lines and zones of strong convergence/divergence are seen in the EVP approximate solution. The approximate solution obtained with the JFNK solver is very close to the reference solution for all spatial resolutions tested. 相似文献