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11.
Jorge J. Betancor Juan C. Fariña Eleonor Harboure Lourdes Rodríguez-Mesa 《Potential Analysis》2013,38(3):711-739
In this paper we prove that the variation operators of the heat semigroup and the truncations of Riesz transforms associated to the Schrödinger operator are bounded on a suitable BMO type space. 相似文献
12.
Automorphic loops, or A-loops, are loops in which all inner mappings are automorphisms. We investigated A-loops arising from a Lie algebra and describe their automorphism group. Also, we identify and describe their inner mapping group. 相似文献
13.
María Consuelo Díaz-Maroto Manuel Lpez Vias Lourdes Marchante María Elena Alan Ignacio Javier Díaz-Maroto María Soledad Prez-Coello 《Molecules (Basel, Switzerland)》2021,26(1)
The effects of different storage conditions, light exposure, temperature and different commercially available cork stoppers on the phenolic, volatile and sensorial profile of Verdejo wines were studied. Two natural corks of different visual quality and a microgranulated cork stopper were investigated over one year at two different storage conditions. One simulating light exposure and temperature in retail outlets and the other simulating optimal cellar conditions (darkness and 12 °C). The wines stored under commercial conditions showed greater losses of total and free SO2 and higher levels of brown-yellowish tones, related to the oxidation of flavan-3-ols. Although these wines underwent a decrease in the total content of stilbenes, a significant increase in trans-piceid was observed. In addition, these wines suffered important changes in their volatile and sensory profile. Volatile compounds with fruity and floral aromas decreased significantly, while volatile compounds related to aged-type characters, as linalool oxides, vitispirane, TDN or furan derivatives increased. Wines stored in darkness at 12 °C underwent minor changes and their sensory profiles were similar to wine before bottling. The high-quality natural corks and microgranulated corks better preserved the quality of the white wines from a sensory point of view. These results showed that temperature and light exposure conditions (diffuse white LEDs and 24 ± 2 °C) in retail outlets considerably decrease the quality of bottled white wines and, consequently, their shelf life, due to the premature development of aged-type characters. 相似文献
14.
Reguera Edilso Yee-Madeira Hernani Fernández-bertran José Nuñez Lourdes 《Transition Metal Chemistry》1999,24(2):163-167
Ferrous salts of ten hexacyanometallates and three tetracyanometallates were obtained and their Mössbauer spectra interpreted according to recent structural models for these families of compounds. Ferrous ferrocyanide (Williamson White) and its ruthenium and osmium analogs prepared mechanochemically are stable for hours, allowing their study by Mössbauer spectroscopy and other related techniques. For ferrous salts of trivalent hexacyanometallate anions, the random distribution of anion vacancies is discarded and a model of two well defined relative positions of CN and H2O ligands around the Fe2+ is suggested. Iron was found octahedrally coordinated in tetracyanometallates. 相似文献
15.
16.
Arturo F. Méndez-Sánchez M. Rosario López-González V. Hugo Rolón-Garrido José Pérez-González Lourdes de Vargas 《Rheologica Acta》2003,42(1-2):56-63
The rheological behavior of a cetylpyridinium chloride 100 mmol l–1/sodium salicylate 60 mmol l–1 aqueous solution was studied in this work under homogeneous (cone and plate) and non-homogeneous flow conditions (vane-bob
and capillary rheometers), respectively. Instabilities consistent with non-monotonic flow curves were observed in all cases
and the solution exhibited similar behavior under the different flow conditions. Hysteresis and the sigmoidal flow curve suggested
as characteristic of systems that show constitutive instabilities were observed when running cycles of increasing and decreasing
stress or shear rate, respectively. This information, together with a detailed determination of steady states at shear stresses
close to the onset of the instabilities, allowed one to show unequivocally that "top and bottom jumping" are the mechanisms
to trigger the instabilities in this micellar system. It is shown in addition that there is not a true plateau region in between
the "top and bottom jumping". Finally, the flow behavior beyond the upturn seemed to be unstable and was found accompanied
by an apparent violation of the no-slip boundary condition. 相似文献
17.
18.
Temporal cleaning of a high-energy fiber-based ultrafast laser using cross-polarized wave generation
Zaouter Y Ramirez LP Papadopoulos DN Hönninger C Hanna M Druon F Mottay E Georges P 《Optics letters》2011,36(10):1830-1832
We report the use of cross-polarized wave generation to perform both pulse shortening and temporal cleaning of a high-energy ytterbium-doped fiber-based femtosecond laser system. The nonlinear processes allow both a highly efficient nonlinear conversion of 20% and a large compression ratio of 3.5, with inherently improved coherent and incoherent contrasts. This results in the generation of 37 μJ, 115 fs pulses at a repetition rate of 100 kHz with high temporal quality. 相似文献
19.
During the last three decades, the impact of visualization processes on the teaching and learning of mathematics has been extensively researched. However, considerably less work has been devoted to haptic processes. In this paper, we describe and analyze the role of haptic processes from data collected in mathematics lessons taught in a school for blind students. The analysis builds upon studies from perception and also from teaching experiences in order to examine the teacher’s and the students’ hand movements and metaphors when handling solids of revolution and communicating verbally with each other about their insights. We highlight the powerful combination of the visual and the haptic components of their interactions for the conceptualization of mathematical experiences, and we also note the critical role mathematical language plays in supporting the teaching–learning processes in this context. Finally, we consider important educational implications not only for blind people, but for all students and teachers of mathematics. 相似文献
20.
Julien Férec Marie-Claude Heuzey José Pérez-González Lourdes de Vargas Gilles Ausias Pierre J. Carreau 《Rheologica Acta》2009,48(1):59-72
The behavior of short glass fiber–polypropylene suspensions in extensional flow was investigated using three different commercial
instruments: the SER wind-up drums geometry (Extensional Rheology System) with a strain-controlled rotational rheometer, a
Meissner-type rheometer (RME), and the Rheotens. Results from uniaxial tensile testing have been compared with data previously
obtained using a planar slit die with a hyperbolic entrance. The effect of three initial fiber orientations was investigated:
planar random, fully aligned in the stretching flow direction and perpendicular to it. The elongational viscosity increased
with fiber content and was larger for fibers initially oriented in the stretching direction. The behavior at low elongational
rates showed differences among the various experimental setups, which are partly explained by preshearing history and nonhomogenous
strain rates. However, at moderate and high rates, the results are comparable, and the behavior is strain thinning. Finally,
a new constitutive equation for fibers suspended into a fluid obeying the Carreau model is used to predict the elongational
viscosity, and the predictions are in good agreement with the experimental data. 相似文献