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41.
Sergio A. Guerrero Carlos M. Sanabría Alirio Palma Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(4):408-415
(2R*,4S*)‐Methyl 2,3,4,5‐tetrahydro‐1,4‐epoxy‐1H‐benz[b]azepine‐2‐carboxylate, C12H13NO3, (I), and its reduction product (2R*,4S*)‐methyl 4‐hydroxy‐2,3,4,5‐tetrahydro‐1H‐benz[b]azepine‐2‐carboxylate, C12H15NO3, (II), both crystallize as single enantiomers in the space group P212121, while the hydrolysis product (2RS,4SR)‐4‐hydroxy‐2,3,4,5‐tetrahydro‐1H‐benz[b]azepine‐2‐carboxylic acid, C11H13NO3, (III), and the lactone (2RS,5SR)‐8‐(trifluoromethoxy)‐5,6‐dihydro‐1H‐2,5‐methanobenz[e][1,4]oxazocin‐3(2H)‐one, C12H10F3NO3, (IV), both crystallize as racemic mixtures in the space group P21/c. The molecules of compound (IV) are linked into centrosymmetric R22(10) dimers by N—H...O hydrogen bonds, and those of compound (I) are linked into chains by C—H...π(arene) hydrogen bonds. A combination of O—H...O and O—H...N hydrogen bonds links the molecules of compound (III) into sheets containing equal numbers of R44(14) and R44(26) rings, and a combination of C—H...π(arene) hydrogen bonds and three‐centre O—H...(N,O) hydrogen bonds links the molecules of compound (II) into a three‐dimensional framework structure. Comparisons are made with some related compounds. 相似文献
42.
Rafael Caballero Mercedes González Flor M Guerrero Julián Molina Concepción Paralera 《European Journal of Operational Research》2007
In this work we present a multiobjective location routing problem and solve it with a multiobjective metaheuristic procedure. In this type of problem, we have to locate some plants within a set of possible locations to meet the demands of a number of clients with multiple objectives. This type of model is used to solve a problem with real data in the region of Andalusia (Spain). Thus, we study the location of two incineration plants for the disposal of solid animal waste from some preestablished locations in Andalusia, and design the routes to serve the different slaughterhouses in this region. This must be done while taking into account certain economic objectives (start-up, maintenance, and transport costs) and social objectives (social rejection by towns on the truck routes, maximum risk as an equity criterion, and the negative implications for towns close to the plant). 相似文献
43.
Jorge Antonio Guerrero‐Álvarez Wendy Paloma Mas‐Ku Cesar Garcías‐Morales Armando Ariza‐Castolo 《Magnetic resonance in chemistry : MRC》2010,48(5):356-361
The relative acidities of the cis and trans isomers of a series of 1,5‐oxazaspiro[5.5]undecane derivatives were determined by measuring ΔpK in acid‐base titrations followed by 1 H NMR. Relative structural stabilities were determined by measuring substituent chemical shift and γ‐gauche effects in 13C, 15N, and 17O NMR. Crystallographic characterization of a model spiro[5.5]undecane is presented to support the basicity in solid state. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
44.
M. Calixto J. Guerrero J. C. Sánchez-Monreal 《Journal of Fourier Analysis and Applications》2008,14(4):538-567
Using coherent-state techniques, we prove a sampling theorem for Majorana’s (holomorphic) functions on the Riemann sphere
and we provide an exact reconstruction formula as a convolution product of N samples and a given reconstruction kernel (a sinc-type function). We also discuss the effect of over- and under-sampling.
Sample points are roots of unity, a fact which allows explicit inversion formulas for resolution and overlapping kernel operators
through the theory of Circulant Matrices and Rectangular Fourier Matrices. The case of band-limited functions on the Riemann
sphere, with spins up to J, is also considered. The connection with the standard Euler angle picture, in terms of spherical harmonics, is established
through a discrete Bargmann transform.
相似文献
45.
Jesús S. Pérez Guerrero Todd H. Skaggs M. Th. van Genuchten 《Transport in Porous Media》2009,80(2):373-387
Transport equations governing the movement of multiple solutes undergoing sequential first-order decay reactions have relevance
in analyzing a variety of subsurface contaminant transport problems. In this study, a one-dimensional analytical solution
for multi-species transport is obtained for finite porous media and constant boundary conditions. The solution permits different
retardation factors for the various species. The solution procedure involves a classic algebraic substitution that transforms
the advection-dispersion partial differential equation for each species into an equation that is purely diffusive. The new
system of partial differential equations is solved analytically using the Classic Integral Transform Technique (CITT). Results
for a classic test case involving a three-species nitrification chain are shown to agree with previously reported literature
values. Because the new solution was obtained for a finite domain, it should be especially useful for testing numerical solution
procedures. 相似文献
46.
Spectra of the N‐phenyl‐5,6‐dihydro‐2,4‐diphenylbenzo[h]quinolinium tetrafluoroborate (1) and of the N‐phenyl‐5,6,8,9‐tetrahydro‐7‐phenyldibenzo[c,h]acridinium tetrafluoroborate (2) were recorded in various solvents and temperatures. The analysis of the 1H‐NMR spectra of the tetrafluoroborate salt 1, recorded in acetone, acetonitrile, 1,1,2,2‐tetrachloroethane and chloroform, revealed the existence of an equilibrium between two conformers in solution. Tight ion‐pairing in chloroform led to a smaller barrier for interconversion between the two conformers. In more polar solvents, where the dihydrobenzoquinolinium exists as a free cation, theoretical calculations predicted larger barriers. The spectra of 1 in 1,1,2,2‐tetrachloroethane also varied with temperature, resembling at higher temperatures the spectrum in CDCl3 and at 300K spectra in more polar media. Spectra of 2 did not vary with the solvent or the temperature, in an indication of a much higher barrier to conformational interconversion, because of a greater steric hindrance between the N‐phenyl substituent and the dihydrobenzo rings. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
47.
Vaz W. F. Custodio J. M. F. D’Oliveira G. D. C. Neves B. J. Junior P. S. C. Filho J. T. M. Andrade C. H. Perez C. N. Silveira-Lacerda E. P. Napolitano H. B. 《Molecular diversity》2021,25(1):55-66
Molecular Diversity - Cancer is one of the leading causes of death worldwide and requires intense and growing research investments from the public and private sectors. This is expected to lead to... 相似文献
48.
María U. Alzueta Marta Guerrero Ángela Millera Paul Marshall Peter Glarborg 《Proceedings of the Combustion Institute》2021,38(1):575-583
Oxidation of acetonitrile has been studied in a flow reactor in the absence and presence of nitric oxide. The experiments were conducted at atmospheric pressure in the temperature range 1150–1450 K, varying the excess air ratio from slightly fuel-lean to very lean. Oxidation of CH3CN was slow below 1300 K. Nitric oxide, hydrogen cyanide and nitrous oxide were detected as important products. A detailed chemical kinetic model for oxidation of acetonitrile was developed, based on a critical evaluation of data from literature. The rate coefficients for the reactions of CH3CN and CH2CN with O2 were calculated from ab initio theory. Modeling predictions were in satisfactory agreement with experiments. Calculations were sensitive to thermal dissociation of CH3CN and to the branching fraction for CH3CN + OH to CH2CN + H2O and HOCN + CH3, respectively. More work is desirable for these steps, as well as for reactions of CH2CN and HCCN. 相似文献
49.
Sandra Barriga Ana Méndez Joaquín Cámara Francisca Guerrero Gabriel Gascó 《Journal of Thermal Analysis and Calorimetry》2010,99(3):981-986
The objective of this study is to study the influence of de-inking paper sludge (DPS) and sewage sludge (SL) mixtures addition
at different rates (2, 4 and 8%) in two soils. Incubation experiments were performed during 60 days and the influence of treatments
in physical soil properties was determined by soil porosity and stability of aggregates. Differential thermal analysis (DTA)
of amended soils after incubation was performed. Experimental results show that amendment increased biological soil activity,
soil porosity and stability of aggregates. DTA analysis shows that the first exothermic peak generally increases with the
dosage of DPS:SL due to the addition of immature organic matter. Moreover, the second peak enlarges probably due to the humification
process during incubation. 相似文献
50.
The present work offers new equations for phase evaluation in measurements. Several phase shifting equations with an arbitrary but constant phase shift between captured intensity signs are proposed. The equations are similarly derived as the so-called Carré equation. The idea is to develop a generalization of Carré equation that is not restricted to four images. Errors and random noise in the images cannot be eliminated, but the uncertainty due to their effects can be reduced by increasing the number of observations. An experimental analysis of the mistakes of the technique was made, as well as a detailed analysis of mistakes of the measurement. The advantages of the proposed equation are its precision in the measures taken, speed of processing and the immunity to noise in signs and images. 相似文献