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351.
We are proposing for the first time the successful immobilization of DNA at glassy carbon electrodes (GCE) modified with carbon nanotubes (CNT) dispersed in glucose oxidase (GOx) (GCE/CNT‐GOx) either by direct adsorption or by layer‐by‐layer self‐assembling using polydiallyldimethylamine (PDDA). The presence of GOx allows an efficient dispersion of CNT and gives a most favorable environment that promotes the adsorption and makes possible a more sensitive electrooxidation of DNA. The PDDA incorporated in the self‐assembled architecture largely facilitates the adsorption and electrooxidation of dsDNA and the adsorbed layer can be successfully used for evaluating the interaction of DNA with methylene blue. 相似文献
352.
Bernabé L. Rivas María del Carmen Aguirre Eduardo Pereira Christophe Bucher Jean‐Claude Moutet Eric Saint Aman Guy Royal 《先进技术聚合物》2011,22(4):414-419
Electrochemistry and ultrafiltration membrane methods (electro‐oxidation and liquid phase polymer based retention technique LPR, respectively) were coupled to remove As(III) inorganic species from aqueous solutions. Our main objective was to achieve an efficient extraction of arsenic species by associating a polymer‐assisted liquid phase retention procedure, based on the As(V) adsorption properties of cationic water‐soluble polymers, with the electrocatalytic oxidation process of As(III) into its more easily removable analog As(V). The exhaustive oxidation of As(III)–As(V) was readily performed in high yield at iridium oxide film modified carbon felt electrodes in the presence of different water‐soluble poly(quaternary ammonium) salts acting also as supporting electrolyte. The progress of the macro‐scale oxidation of As(III)–As(V) was followed using iridium oxide film modified glassy carbon electrodes. Finally, a study on arsenic retention by LPR‐technique performed on fully oxidized solutions of arsenic, showing that complete (100%) retention of the arsenic could be achieved using a 20:1 polyammonium:As(III) mole ratio. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
353.
C. Vázquez-Vázquez M. A. López-Quintela M. C. Buján-Núñez J. Rivas 《Journal of nanoparticle research》2011,13(4):1663-1676
Cobalt ferrite, CoFe2O4, nanoparticles in the size range 2–15 nm have been prepared using a non-aqueous solvothermal method. The magnetic studies indicate a superparamagnetic behavior, showing an increase in the blocking temperatures (ranging from 215 to more than 340 K) with the particle size, D TEM. Fitting M versus H isotherms to the saturation approach law, the anisotropy constant, K, and the saturation magnetization, M S, are obtained. For all the samples, it is observed that decreasing the temperature gives rise to an increase in both magnetic properties. These increases are enhanced at low temperatures (below ~160 K) and they are related to surface effects (disordered magnetic moments at the surface). The fit of the saturation magnetization to the T 2 law gives larger values of the Bloch constant than expected for the bulk, increasing with decreasing the particle size (larger specific surface area). The saturation magnetization shows a linear dependence with the reciprocal particle size, 1/D TEM, and a thickness of 3.7 to 5.1 Å was obtained for the non-magnetic or disordered layer at the surface using the dead layer theory. The hysteresis loops show a complex behavior at low temperatures (T ≤ 160 K), observing a large hysteresis at magnetic fields H > ~1000 Oe compared to smaller ones (H ≤ ~1000 Oe). From the temperature dependence of the ac magnetic susceptibility, it can be concluded that the nanoparticles are in magnetic interaction with large values of the interaction parameter T 0, as deduced by assuming a Vogel–Fulcher dependence of the superparamagnetic relaxation time. Another evidence of the presence of magnetic interactions is the almost nearly constant value below certain temperatures, lower than the blocking temperature T b, observed in the FC magnetization curves. 相似文献
354.
Water-soluble polymers containing amine, carboxylic acid, and sulfonic acid groups were investigated as polychelatogens through the liquid phase polymer-based retention, LPR technique, under different experimental conditions. The metal ions investigated are: Ag(I), Cu(II), Co(II), Ni(II), Ca(II), Hg(II), and Cr(III). An important effect of the pH and the ligand type was observed on the metal ion retention. As the pH increases the metal ion retention increases. Two types of metal ion interactions are involved: coordination and electrostatic. 相似文献
355.
介绍了以铽(Tb)激活的高密度发光玻璃和光导纤维发光玻璃的特性。它应用在X射线实时成像系统中,可大大改善空间分辨能力。用它做的转换屏比一般晶粒状荧光物质做的厚得多,特别适合用于高能X射线实时成像系统 相似文献
356.
Ignacio Moreno‐Villoslada Carla Muoz BernabL. Rivas 《Macromolecular rapid communications》2001,22(14):1191-1193
The multicomponent system consisting of poly(sodium 4‐styrenesulfonate) (PSS), iminodiacetic acid (IDAA), and Cu(NO3)2 in water at pH 4 was studied by means of ultrafiltration at low and relatively high ionic strengths. Under the experimental conditions, IDAA is negatively charged, and is slightly retained in ultrafiltration experiments in the presence of the water‐soluble polyelectrolyte PSS. The positively charged copper ions are strongly retained by PSS. Due to the capability of IDAA to form stable complexes with Cu2+ ions, the resulting blue 1:1 complex between IDAA and Cu2+ is not retained by PSS, but is eluted from the ultrafiltration cell at pH 4. 相似文献
357.
Bernab L. Rivas S. Amalia Pooley Maribel Luna 《Macromolecular rapid communications》2001,22(6):418-421
The synthesis and characterization of the water‐soluble poly(N‐acetyl‐α‐acrylic acid) by radical polymerization were carried out. The polymer was characterized by Fourier Transform Infrared (FT‐IR), 1H NMR and 13C NMR spectroscopies, and thermogravimetric analysis (TGA). The metal ion binding properties for the metals Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Pb(II), Hg(II), Cr(III) in the aqueous phase were studied using the liquid‐phase polymer‐based retention technique. The metal ion interactions with the hydrophilic polymer were determined as a function of pH and of the filtration factor. The polychelatogen showed a high affinity for metal ions and higher selectivity for Cr(III) at pH = 3. 相似文献
358.
Bernab L. Rivas S. Amalia Pooley Maribel Luna 《Macromolecular rapid communications》2000,21(13):905-908
The synthesis of poly(N‐acryloylpiperazine) was carried out by radical polymerization giving a yield of 90%. The polymer was soluble in water and was characterized by FTIR, 1H NMR, 13C NMR spectroscopy, and TGA. The metal ability binding properties for the Ag(I), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II), and Cr(III) metal ions in the aqueous phase were investigated using the liquid‐phase polymer‐based retention (LPR) method. The metal ion interactions with the hydrophilic polymers were determined as a function of pH and filtration factor. 相似文献
359.
Kurt E. Geckeler Nasser Arsalani Bernab L. Rivas 《Macromolecular rapid communications》1997,18(6):503-508
A novel method for the preparation of water-soluble polypyrrole graft copolymers with polyamines or polyimines is described. The polyreaction is performed in acidic solution by using chemical oxidants, e.g. iron(III) chloride or ammonium peroxodisulfate. The graft copolymers showed electrical semiconductivity in the undoped state which can be placed between the high conductivity of polypyrrole and the nonconductivity of the polyimine. Their thermal stability at 250°C is improved compared to polypyrrole. The novel graft copolymers are soluble in water over a wide pH range and have a good processability. 相似文献
360.
Elgueta Elizabeth Becerra Yerko Martínez Ana Pereira Miguel Carrillo-Varela Isabel Sanhueza Felipe Nuñez Dariela Rivas Bernabé L. 《高分子科学》2023,41(6):874-886
Chinese Journal of Polymer Science - The adsorption capacity of hydrogels derived from modified xylan hemicellulose has been tested in order to develop new bio-based adsorbent materials useful for... 相似文献