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81.
R. D. Simoes M. A. Rodriguez-Perez J. A. de Saja C. J. L. Constantino 《Journal of Thermal Analysis and Calorimetry》2010,99(2):621-629
Films of poly(vinylidene fluoride), PVDF, and poly(vinylidene fluoride – trifluoroethylene), P(VDF-TrFE), containing corn
starch and latex of natural rubber as additives were produced by compressing/annealing forming blends visioning applications
as biomaterials. Therefore, considering the possible applications of these blends, a basic characterization has been carried
out targeting to infer on their thermomechanical properties. The polymer films (PVDF and P(VDF-TrFE)) with different percentage
of additives were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR),
thermogravimetry (TG), differential scanning calorimetry (DSC), and dynamical-mechanical analysis (DMA). The compressing/annealing
process allowed discarding the necessity of using the solvents to dissolve either PVDF or P(VDF-TrFE), which are usually toxic
to human. The results showed that the polymers do not interact chemically with the additives with the blends showing high
thermal stability and elasticity modulus at the same order of magnitude of the bone, for instance. The SEM imaged revealed
that the blends present morphological structures of typical physical mixtures where each material can be identified within
the blends. 相似文献
82.
83.
Pedro Henrique Benites Aoki Priscila Alessio Jose Antonio De Saja Carlos Jos Leopoldo Constantino 《Journal of Raman spectroscopy : JRS》2010,41(1):40-48
The synergistic effect produced by nanoparticles when incorporated into different systems used as analytical tools represents a growing research field nowadays. On the other hand, the study of interactions involving pharmacological drugs and biological membranes using phospholipids as mimetic systems is a research field already well established. Here, we combine both the anionic phospholipid dipalmitoyl phosphatidyl glycerol (DPPG) and negative Ag nanoparticles (AgNP) to form layer‐by‐layer (LbL) multilayered films using the cationic polymer poly(allylamine hydrochloride) (PAH) as the supporting polyelectrolyte, which were further investigated in the presence of a phenothiazine compound (methylene blue—MB). The molecular architecture of the LbL films in terms of controlled growth, morphology with micro and nanometer spatial resolutions, and dispersion of both AgNP and MB within the DPPG matrix was determined combining spectroscopy [ultraviolet–visible (UV–Vis) absorption and micro‐Raman spectroscopy] and microscopy [scanning electron microscopy (SEM) and atomic force microscopy (AFM)]. The results showed that the LbL films can be grown in a controlled way at nanometer thickness scale with the surface morphology susceptible to the presence of both AgNP and MB. The surface‐enhanced phenomenon was applied to investigate the LbL films taking the advantage of the strong surface‐enhanced resonance Raman scattering (SERRS) signal presented by the MB molecules. Besides, as MB is a pharmacological drug of interest, its molecular arrangements when dispersed in LbL films containing DPPG, which is the biological membrane mimetic system here, were investigated. In this case, the AgNP played a key role in achieving the MB SERRS signal. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
84.
Rafael J. G. Rubira Sabrina A. Camacho Pedro H. B. Aoki Mateus D. Maximino Priscila Alessio Cibely S. Martin Osvaldo N. Oliveira Jr. Francisco M. Fatore Fernando V. Paulovich Carlos J. L. Constantino 《Colloid and polymer science》2014,292(11):2811-2820
The detection of trace amounts of pesticides is essential for the quality control of waters, particularly with their inevitable increasing use with the growing demand for food. In this study, we report on the detection of atrazine, a highly toxic herbicide, down to 5?×?10?12 M, which is sufficient to monitor the quality of drinking water even according to the most stringent international regulations. Such detection was performed with surface-enhanced Raman scattering (SERS) in atrazine incorporated into silver nanoparticles (AgNPs) colloids, with the SERS spectra being treated with Sammon’s mapping, an information visualization technique. In addition to providing a fingerprint of the atrazine molecules, SERS is advantageous in comparison with impedance spectroscopy and cyclic voltammetry applied to a sensor array of units made with layer-by-layer (LbL) films containing AgNPs and AuNPs. The combined use of SERS and information visualization methods is promising for monitoring water quality with regard to other pesticides, which may even approach single molecule detection. 相似文献
85.
Mauricio Gomes Constantino Milton Beltrame Jr. Gil Valdo José da Silva Julio Zukerman-Schpector 《合成通讯》2013,43(2):321-329
A 12-step synthesis of the natural product (+)-Artemisinin, very active against malaria, is described. (-)-Isopulegol, which already contains two of the asymmetric centers of (+)-Artemisinin in the correct absolute configuration, was used as starting material. 相似文献
86.
Gustavo F. Perotti Rafael Auras Vera R. L. Constantino 《Journal of carbohydrate chemistry》2013,32(8-9):483-501
Starch-based biofilms containing synthetic Laponite clay and glycerol were prepared using a solvent casting technique. Electron microscopy images showed predominance of the exfoliated type of nanocomposite. Dynamic mechanical analysis revealed a larger influence of glycerol content on the polymer β relaxation and T g than the clay content. Gas barrier properties were influenced by clay particles and plasticizer content. An increase of clay content led to lower gas permeability values. Although both glycerol and Laponite are hydrophilic, no significant changes were observed on the water sorption by starch films at different relative humidity values. Mechanical properties are kept similar after the inorganic filler incorporation. 相似文献
87.
Poisson-Boltzmann description of the electrical double layer including ion size effects 总被引:1,自引:0,他引:1
López-García JJ Horno J Grosse C 《Langmuir : the ACS journal of surfaces and colloids》2011,27(23):13970-13974
The electrical double layer is examined using a generalized Poisson-Boltzmann equation that takes into account the finite ion size by modeling the aqueous electrolyte solution as a suspension of polarizable insulating spheres in water. We find that this model greatly amplifies the steric effects predicted by the usual modified Poisson-Boltzmann equation, which imposes only a restriction on the ability of ions to approach one another. This amplification should allow for an interpretation of the experimental results using reasonable effective ionic radii (close to their well-known hydrated values). 相似文献
88.
Miguel Constantino Xenia Klimentova Ana Viana Abdur Rais 《European Journal of Operational Research》2013
In recent years several countries have set up policies that allow exchange of kidneys between two or more incompatible patient–donor pairs. These policies lead to what is commonly known as kidney exchange programs. 相似文献
89.
Constantino Tsallis 《Brazilian Journal of Physics》2014,44(2-3):283-285
What is nowadays ubiquitously referred to as complexity emerges in a wide variety of natural, artificial, and social systems. This very rich concept is nontrivial to understand and is therefore hard to operationally define. Consequently, along the years, many intertwined characterizations have been proposed in the literature. Among those, a powerful and practical one consists in focusing on the entropic and statistical mechanical aspects of the system. We attempt here to put this active line of research into a contemporary perspective. 相似文献
90.