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281.
Angel Romo-Uribe Maraolina Domínguez-Díaz Maria Eugenia Romero-Guzmán Leonardo Rejón Rubén Saldivar-Guerrero 《Rheologica Acta》2009,48(2):201-215
This research investigates the influence of monomer composition on the thermal transitions, mi crostructure, and viscoelastic
properties of thermotro pic liquid crystalline polymers (LCPs) based on 1, 4-hydroxy-benzoic acid (B) and 2,6-hydroxy-naphthoic
acid (N). Compositions B–N of 1:1, 1:3, 3:1, and 2:1 mol% were studied. The solid-to-nematic transition T
s→n was greatly influenced by the monomer composition, ranging from 230 to 280 °C. However, the decomposition temperature T
dec was independent of composition, all the materials degrading at T
dec = 509 °C. Polarized optical microscopy showed a threaded texture in the nematic phase. Fiber X-ray diffraction showed aperiodic
meridional maxima for all LCPs, the number of maxima depended on composition. B–N 3:1 and 1:3 mol% favor the orthorhombic
crystallographic phase whereas the 1:1 and 2:1 mol% crystallized in a pseudohexagonal phase. Dynamic time sweeps showed that
the nematic phases are stable at the temperatures studied. Strain sweeps showed the existence of a linear viscoelastic (LVE)
regime. The LVE properties ranged from predominantly viscous (G′ < G″) for the 1:1 mol% composition to predominantly elastic (G′ > G″) and with a well-defined rubber-like regime for the 1:3 mol% composition, resembling the rheology of flexible polymer melts.
The persistence length q appears to be the parameter driving the rheological behavior.
相似文献
Angel Romo-UribeEmail: |
282.
M. Duocastella J. M. Fernández-Pradas J. Domínguez P. Serra J. L. Morenza 《Applied Physics A: Materials Science & Processing》2008,93(4):941-945
Laser-induced forward transfer (LIFT) is a direct-writing technique adequate for the high-resolution printing of a wide range
of materials, including biological molecules. In this article, the preparation through LIFT of microarrays of droplets from
a solution containing rabbit antibody immunoglobulin G (IgG) is presented. The microarrays were prepared at different laser
pulse energy conditions, obtaining microdroplets with a circular and well-defined contour. The transfer process has a double
threshold: a minimum energy density required to generate an impulsion on the liquid film, and a minimum pulse energy, which
corresponds to the onset for material ejection. In addition, it was demonstrated that the transfer process can be correctly
described through a simple model which relates the energy density threshold with the amount of released material. Finally,
a fluorescence assay was carried out in which the preservation of the activity of the transferred biomolecules was demonstrated. 相似文献
283.
Irene Domínguez Antonio Doménech-Carbó Josep P. Cerisuelo Gracia López-Carballo Pilar Hernández-Muñoz Rafael Gavara 《Journal of Solid State Electrochemistry》2014,18(8):2099-2110
A contact probe methodology, based on the voltammetry of immobilized microparticle approach, is used for characterizing silver species present in linear low density polyethylene (LLDPE) films with different Ag(I)/Ag(0) ratios and silver nanoparticle features usable as food contact polymers. The films displayed characteristic voltammetric features in contact with aqueous acetate buffer, in particular signals for the stripping oxidation of nanoparticulate Ag systems. Significant differences between the studied films were also observed by means of electrochemical impedance spectroscopy and detected at the nanoscopic scale using electrochemical scanning microscopy. Differences in optical and thermal properties of the studied films are associated with the presence of silver nanoparticles. The silver oxidation state as well as nanoparticle size also had influence on the oxidative resistance of the LLDPE films; indeed, films containing cationic silver showed the lowest oxidation induction time value. 相似文献
284.
Ferragud Xavier Piquero-Cilla Joan Doménech-Carbó María Teresa Blay Vicent Guerola Company Ximo Doménech-Carbó Antonio 《Journal of Solid State Electrochemistry》2017,21(5):1477-1487
Journal of Solid State Electrochemistry - The application of the voltammetry of microparticles methodology to the study of gildings in paintings and architectural ornaments is described.... 相似文献
285.
Summary Program temperature retention indices for fifteen nonalkane solutes have been determined by cubic splines, by other procedures
found in the literature and by interpolation of the n-alkanes retention time logarithm for eleven temperature programs. A
comparison in terms of variance of the differences between PTRI calculated by CS and each of the remaining methods is made
for each of the eleven program runs, for each of the three stationary phases used and for many of the programs. The smallest
variances obtained result when the Zenkevich, van den Dool & Kratz and Chen et al. methods are tested. The stationary phase
polarity is of no relevance since it has no effect on the specific PTRI found by the different methods employed in this work. 相似文献
286.
A complete formulation of kinetic theory in the scale-covariant gravitation is presented in this paper. Following the usual scheme we find the Boltzmann equation for a colliding gas. From this equation we obtain the H-Theorem and the equilibrium distribution functions for homogeneous and isotropic spaces in the quantum case and in the high dilution limit. 相似文献
287.
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289.
290.
Summary Enzyme based detection systems in column liquid chromatography are described using systems based on both enzyme reactors in conjunction with a flow through detection device and enzyme electrodes. Optimizations for making detection principles compatible with chromatographic systems and applications made in our laboratories are presented for the analysis of e.g. carbohydrates, amino acids, ethanol and catecholamines. Gel-permeation chromatography and mass spectrometry are used as complementary techniques for qualitative and quantitative analysis of complex samples. 相似文献