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103.
Poly(3‐hydroxybutyrate)–thermoplastic starch–organoclay bionanocomposites: Surface properties 下载免费PDF全文
Bionanocomposites based on poly(3‐hydroxybutyrate) (PHB) and starch plasticized with glycerol and water [thermoplastic starch (TPS)] with organically modified montmorillonite clay as a nanofiller were obtained by melt‐blending. The influence of the clay and TPS on the thermal and mechanical properties of the resultant bionanocomposite was investigated by various techniques, such as X‐ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), thermogravimetric analysis, differential scanning calorimetry, and nanoindentation. The results obtained by AFM showed that bionanocomposites have a surface roughness of 30.88 nm, compared to 14.53 nm for processed PHB. This result is obtained due to the migration of clay layers to the surface. From XRD and TEM it was determined that the clay layers of the bionanocomposites are completely separated. The hardness and elastic moduli of bionanocomposites have values similar to those of PHB, improving the drawbacks of the PHB–TPS blends (65:35 weight ratio). The thermal properties do not present significant changes, and only the degree of crystallinity decreased with increasing clay content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45217. 相似文献
104.
Patricia Ruiz Bernabé Dorronsoro Giorgio Valentini Frédéric Pinel Pascal Bouvry 《The Journal of supercomputing》2012,62(3):1213-1240
Mobile ad hoc networks (or MANETs) are wireless networks that are spontaneously created by the neighbouring devices, without the use of any kind of infrastructure. These devices usually rely on batteries, so the lifetime of this type of network highly depends on the energy consumption of the devices composing it. Therefore, the optimisation of the energy consumption is a must in a realistic MANET. We deal in this paper with the optimisation of enhanced distance based (or EDB) broadcasting protocol for MANETs. EDB is an improved version of DB (distance based protocol), a state-of-the-art broadcasting protocol for MANETs, that is focussed on saving the energy used by the devices in the dissemination process (an essential component in MANETs), without degrading the network connectivity or the performance in the coverage of the broadcasting process. A set of parameters were identified in EDB and optimised using CellDE, a hybrid multi-objective optimisation algorithm, to maximise the coverage of the broadcast while minimising at the same time both the energy consumption and the broadcast time. The ns3 simulator was used to evaluate the different configurations of EDB. As a result, 100 different solutions are provided for every studied network, covering a wide range of design options; all of them have quality better than or similar to that provided by EDB with previously recommended values for its parameters. 相似文献
105.
Immobilization of Trametes versicolor laccase on different PGMA‐based polymeric microspheres using response surface methodology: Optimization of conditions 下载免费PDF全文
Enzymatic immobilization is a versatile alternative to improve enzyme stability and enable its reuse. In this study, the change in the immobilized enzyme properties due to the type of functional group on the carrier was evaluated. For that, monodisperse polymeric microspheres with two functional groups widely used in laccase immobilization—oxirane [poly(glycidyl methacrylate) (PGMA)] and hydrazide—were synthesized by dispersion polymerization to covalently immobilize the laccase Trametes versicolor. Using a response surface methodology, laccase immobilization was optimized for each microsphere type. As a result, laccase immobilization on PGMA carriers appears to broaden the pH and temperature ranges, storage stability, and reusability compared to free and hydrazide enzymes. These aforementioned characteristics indicate that PGMA microspheres could act as an ideal support for enzyme immobilization in biotechnological applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45249. 相似文献
106.
Preparation and characterization of water‐soluble polymers and their utilization in chromium sorption 下载免费PDF全文
Julio Sánchez Nicole Mendoza Bernabé L. Rivas Luis Basáez J. L. Santiago‐García 《应用聚合物科学杂志》2017,134(39)
In this article, we study the sorption of chromium from aqueous solutions using water‐soluble polymers (WSPs): poly[2‐(acryloyloxy) ethyl] trimethylammonium chloride, P(ClAETA); poly[2‐(methacryloyloxy) ethyl] trimethylammonium methyl sulfate, P(SAETA); and poly(sodium 4‐styrenesulfonate), P(NaSS). These WSPs were obtained by radical polymerization and purified by fractionation through ultrafiltration membranes with different molar mass cut‐offs (30 and 100 kDa). The characterization was carried out by thermogravimetric analysis (TGA), FTIR, and 1H‐NMR spectroscopies and scanning electron microscopy/energy dispersive X‐ray spectroscopy. The chromium retention properties of the polymers were determined in terms of pH, optimal polymer concentration, and the effect of interfering ions. The results show yields above 80% for all of the synthesized WSPs. Characterization by spectroscopy confirmed the chemical structure of the polymers. TGA shows thermal decomposition temperatures of 264 and 324 °C for P(ClAETA) and P(SAETA), respectively. In the case of P(NaSS), the first thermal decomposition begins at approximately 450 °C. Maximum retention of Cr(VI) (100%) by the polymers P(ClAETA) and P(SAETA) was achieved at pH 9, and the maximum retention of Cr(III) (100%) was achieved by P(NaSS) at pH 3. The optimal polymer:Cr molar ratio obtained was 20:1. The retention of chromium(VI) was decreased by the presence of interfering ions, and the hydrodynamic flux was almost constant during ultrafiltration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45355. 相似文献
107.
Bernabé Gregorio Casanova José D. Cuenca Javier González-Carrillo Josefa 《The Journal of supercomputing》2019,75(3):1625-1640
The Journal of Supercomputing - Left ventricular non-compaction is characterized by the presence of multiple trabecules in the left ventricle myocardium, associated with multiple inter-trabecular... 相似文献
108.
Guadalupe del C. Pizarro Oscar G. Marambio Manuel Jeria-Orell Margarita R. Huerta Bernabé L. Rivas Wolf D. Habicher 《应用聚合物科学杂志》2008,108(6):3982-3989
Radical copolymerization of 1-vinyl-2-pyrrolidone with itaconic acid at different feed monomer ratios (75–25 mol %) were investigated. The copolymers were characterized by elemental analysis, Fourier transform infrared (FTIR), 1H and 13C NMR spectroscopy. The copolymer composition was determined from elemental analysis and found to be statistical copolymers. Additionally, viscosimetric measurements, molecular weight, and polydispersity have been determined. The metal complexation of poly(1-vinyl-2-pyrrolidone-co-itaconic acid) for the metal ions such as Cr(III), Co (II), Zn(II), Ni(II), Cu(II), Cd(II), and Fe(III) were investigated at pH 3, 5, and 7 in aqueous solution. The metal ion interaction with hydrophilic polymers was determined as a function of the pH and filtration factor. Poly(1-vinyl-2-pyrrolidone-co-itaconic acid) showed a high affinity for the metal ions at pH 5 and 7. The poly(NVP-co-IA), with a copolymer composition of 29 : 71 mol % (PVA-3), presented the highest metal ion retention values, particularly at higher pHs, at which the carboxylic acid groups are nonprotonated and could easily coordinate with the metal ions. According to the interaction pattern obtained, Cr(II), Zn(II), Pb(II), and Ni(II) formed the most stable complexes at pH 7. The thermal behaviors of the copolymer and polymer metal complex were characterized using differential scanning calorimetry (DSC) and thermogravimetry techniques under nitrogen atmosphere. The copolymers present high thermal stability and do not present glass transition in DSC curves between 25 and 500°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
109.
Bernabé Linares-Barranco Teresa Serrano-Gotarredona Rafael Serrano-Gotarredona Clara Serrano-Gotarredona 《Analog Integrated Circuits and Signal Processing》2004,38(2-3):103-119
In this paper we explore the low current limit that standard CMOS technologies offer for current mode based VLSI designs. We show and validate a reliable circuit design technique for current mode signal processing down to fempto-amperes. We will take advantage of specific-current extractors and logarithmic current splitters to obtain on-chip sub-pA currents. Then we will use a special on-chip saw-tooth oscillator to monitor and measure currents down to a few fempto-amps. This way, sub-pA currents are characterized without driving them off-chip, nor requiring expensive instrumentation with complicated low leakage setups. A special current mirror is also introduced for reliably replicating such low currents. As an example, a simple log-domain first-order low-pass filter is implemented that uses a 100 fF capacitor and a 3.5 fA bias current to achieve a cut-off frequency of 0.5 Hz and using an area of 12 × 24.35 μm2 in a standard 0.35 μm CMOS process. A technique for characterizing noise at these currents is described and verified. Also, temperature dependence of leakage currents is measured as well. 相似文献
110.
Saúl E. Bustamante Fonseca Bernabé L. Rivas José M. García Pérez Saúl Vallejos Calzada Félix García 《应用聚合物科学杂志》2018,135(19)
A dense membrane (MS) based on vinyl polymers and containing a pyrylium salt [2,6‐diphenyl‐4(p‐methacryloyloxy)phenylpyryliumtetrafluoroborate] was prepared. The MS has hydrophilic and sensory properties that make it a good material for the selective colorimetric detection of trimethylamine (TMA) vapors, a biogenic amine of great importance in food safety. The polymeric sensor changes from yellow to an intense pink color with increasing concentrations of TMA. The material could be reused in the presence of HCl vapors for at least 10 times. The detection and quantification limits were determined by ultraviolet–visible absorption spectroscopy (4.42 and 13.40 ppm, respectively) and by the RGB parameters of digital color (3.37 and10.22 ppm, respectively). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46185. 相似文献