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11.
Miguelina Vasquez‐Ortega Mauricio Ortega Juan Morales M Guadalupe Olayo Guillermo J Cruz Roberto Olayo 《Polymer International》2014,63(12):2023-2029
Polypyrrole hollow nanoparticles were prepared by atmospheric pressure plasma polymerization. The structure of the nanoparticles was studied using Fourier transform infrared and X‐ray photoelectron spectroscopies, thermogravimetric analysis, scanning and transmission electron microscopies and atomic force microscopy. In contrast to low‐pressure plasma polymerization of pyrrole, which can produce films and solid nanoparticles, we obtained two types of hollow nanoparticles: a fraction with single spherical core and another with a core composed of small bubbles. Thermal characterization allowed us to determine that the nanoparticles are composed of highly crosslinked polymer. A mechanism that explains the formation of both types of hollow nanoparticles as well as solid nanoparticles is proposed. Chemical characterization shows that, in addition to the expected chemical structures due to pyrrole polymerization, the high energy of the plasma at atmospheric pressure produces intense dehydrogenation and oxidation processes. The fluorescence spectrum of the nanoparticles, however, shows a peak at 482 nm indicating that some degree of π‐conjugation is present in the material. © 2014 Society of Chemical Industry 相似文献
12.
Guadalupe Aparicio Gallego Vanessa Medina Villaamil Enrique Grande Isabel Santamarina Ca��nzos Lu��s M. Ant��n Aparicio 《International journal of molecular sciences》2012,13(10):12710-12733
Historically, cell-signaling pathways have been studied as the compilation of isolated elements into a unique cascade that transmits extracellular stimuli to the tumor cell nucleus. Today, growing evidence supports the fact that intracellular drivers of tumor progression do not flow in a single linear pathway, but disseminate into multiple intracellular pathways. An improved understanding of the complexity of cancer depends on the elucidation of the underlying regulatory networks at the cellular and intercellular levels and in their temporal dimension. The high complexity of the intracellular cascades causes the complete inhibition of the growth of one tumor cell to be very unlikely, except in cases in which the so-called “oncogene addiction” is known to be a clear trigger for tumor catastrophe, such as in the case of gastrointestinal stromal tumors or chronic myeloid leukemia. In other words, the separation and isolation of the driver from the passengers is required to improve accuracy in cancer treatment. This review will summarize the signaling pathway crossroads that govern renal cell carcinoma proliferation and the emerging understanding of how these pathways facilitate tumor escape. We outline the available evidence supporting the putative links between different signaling pathways and how they may influence tumor proliferation, differentiation, apoptosis, angiogenesis, metabolism and invasiveness. The conclusion is that tumor cells may generate their own crossroads/crosstalk among signaling pathways, thereby reducing their dependence on stimulation of their physiologic pathways. 相似文献
13.
Beatriz Gutiérrez‐Rivera Krzysztof Waliszewski‐Kubiak Octavio Carvajal‐Zarrabal Maria Guadalupe Aguilar‐Uscanga 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(2):263-270
BACKGROUND: Efficient conversion of glucose/xylose mixtures from lignocellulose is necessary for commercially viable ethanol production. Oxygen and carbon sources are of paramount importance for ethanol yield. The aim of this work was to evaluate different glucose/xylose mixtures for ethanol production using S. cerevisiae ITV‐01 (wild type yeast) and P. stipitis NRRL Y‐7124 and the effect of supplying oxygen in separate and co‐culture processes. RESULTS: The complete conversion of a glucose/xylose mixture (75/30 g L?1) was obtained using P. stipitis NRRL Y‐7124 under aerobic conditions (0.6 vvm), the highest yield production being Yp/s = 0.46 g g?1, volumetric ethanol productivity Qpmax = 0.24 g L?1 h?1 and maximum ethanol concentration Pmax = 34.5 g L?1. In the co‐culture process and under aerobic conditions, incomplete conversion of glucose/xylose mixture was observed (20.4% residual xylose), with a maximum ethanol production of 30.3 g L?1, ethanol yield of 0.4 g g?1 and Qpmax = 1.26 g L?1 h?1. CONCLUSIONS: The oxygen present in the glucose/xylose mixture promotes complete sugar consumption by P. stipitis NRRL Y‐7124 resulting in ethanol production. However, in co‐culture with S. cerevisiae ITV‐01 under aerobic conditions, incomplete fermentation occurs that could be caused by oxygen limitation and ethanol inhibition by P. stipitis NRRL Y‐7124; nevertheless the volumetric ethanol productivity increases fivefold compared with separate culture. Copyright © 2011 Society of Chemical Industry 相似文献
14.
Jesus Guardiola Jose M. Aragón Guadalupe Ramos Rosario Elvira Daniel Martín 《American Institute of Chemical Engineers》2012,58(12):3645-3652
The fine tuning of a sensor designed to locate interfaces using a two‐dimensional gas–solid fluidized bed (FB) as reference is described. The sensor works through computer vision and consists of a charge coupled device camera that is placed alongside the bed and, as the human eye would do, first establishes a straight segment of the bed's top surface to define the phase boundary and then through pattern recognition continuously scans the interface in search of a similar pattern. The field of view is 582 × 752 pixels2. The experimentally measured Pixel size is 216 × 208 μm2. The device allows for experimentally obtaining the position of the probe with a resolution of ± 0.01 pixels at 25 Hz. We also describe its use to measure the height of the FB and observe a linear relationship with fluidization velocity. © 2012 American Institute of Chemical Engineers AIChE J, 2012 相似文献
15.
Muoz-Lpez Cesar Nadem Daz-Silvestre Sergio Telles-Padilla J. Guadalupe Rivera-Vallejo Claudia St Thomas Claude Jimnez-Regalado Enrique 《Polymer Bulletin》2020,77(5):2539-2555
Polymer Bulletin - Preparation of associating multiblock copolymer electrolytes mediated by radical addition–fragmentation chain transfer (RAFT) technique has been evaluated and reported in... 相似文献
16.
Arcila-Lozano CC Loarca-Piña G Lecona-Uribe S González de Mejía E 《Archivos latinoamericanos de nutrición》2004,54(1):100-111
The oregano spice includes various plant species. The most common are the genus Origanum, native of Europe, and the Lippia, native of Mexico. Among the species of Origanum. their most important components are the limonene, gamma-cariofilene, rho-cymenene, canfor, linalol, alpha-pinene, carvacrol and thymol. In the genus Lippia, the same compounds can be found. The oregano composition depends on the specie, climate, altitude, time of recollection and the stage of growth. Some of the properties of this plant's extracts are being currently studied due to the growing interest for substituting synthetic additives commonly found in foods. Oregano has a good antioxidant capacity and also presents antimicrobial activity against pathogenic microorganisms like Salmonella typhimurium, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, among others. These are all characteristics of interest for the food industry because they may enhance the safety and stability of foods. There are also some reports regarding the antimutagenic and anticarcinogenic effect of oregano; representing an alternative for the potential treatment and/or prevention of certain chronic ailments, like cancer. 相似文献
17.
18.
M. Guadalupe Rodríguez‐Delgado Isaura G. Yáñez‐Flores Saul Sánchez‐Valdes Oliverio S. Rodriguez‐Fernandez Rebecca Betancourt‐Galindo Tomas Lozano‐Ramirez Eduardo Ramirez‐Vargas Hortencia Ortega‐Ortiz 《应用聚合物科学杂志》2013,130(4):2713-2721
Hydrogel silver nanocomposites have been used in applications with excellent antibacterial performance. Acrylic acid (AA)/itaconic acid (IA) hydrogels silver nanocomposites were prepared and applied as a coating on a textile substrate. Hydrogel matrices were synthesized first by the polymerization of an AA/IA aqueous (80/20 v/v) solution and mixed with 2‐2‐azobis(2‐methylpropionamide) diclorohydrate and N,N′‐methylene bisacrylamide until the hydrogel was formed. Silver nanoparticles were generated throughout the hydrogel networks with an in situ method via the incorporation of the silver ions and subsequent reduction with sodium borohydride. Cotton (C) and cotton/polyester (CP) textile fibers were then coated with these hydrogel silver nanocomposites. The influence of these nanocomposite hydrogels on the properties of the textile fiber were investigated by infrared spectroscopy (attenuated total reflectance), scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and antibacterial tests against Pseudomona aeruginosa and Staphylococcus aureus. The better conditions, in which no serious aggregation of the silver nanoparticles occurred, were determined. It was proven that the textiles coated with hydrogels containing nanosilver had an excellent antibacterial abilities. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2713–2721, 2013 相似文献
19.
Effect of functional monomer on the stability and film properties of thermosetting core-shell latexes 总被引:1,自引:0,他引:1
E.P. Pedraza 《Polymer》2005,46(24):11174-11185
Functionalized core-shell latexes were prepared by copolymerization of butyl acrylate and methyl methacrylate with 2-hydroxyethyl methacrylate (HEMA) or methacrylic acid (MAA), which were added during the first or second stages of polymerization, respectively. The HEMA and MAA concentrations were increased while the equivalent ratio of functional groups remained constant. Colloidal stability, particle size, particle size distribution, film properties and morphology were studied as functions of functional monomer content. The upper limit functionality content was limited by the stability of the system during synthesis. A bimodal particle size distribution was observed for high concentrations of functional monomers. Increase in carboxyl and hydroxyl functionalities improved tensile strength and modulus for un-crosslinked films, and generally higher tensile strength, tensile modulus and storage modulus at high temperature were obtained after the functional latexes were crosslinked with a cycloaliphatic diepoxide. 相似文献
20.