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[en] In this note, the problem of control for a class of chaotic systems is studied. Only partial information of the systems states is known. First, an adaptive observer is designed to ensure the corresponding error system asymptotically stable. Then, based on the states obtained by the above observer, a nonlinear state feedback controller is constructed for the chaotic system, which, according to the input to state stable (ISS) principal, guarantees the closed-loop chaotic system is asymptotically stable. A numerical example is included to show the effectiveness of the proposed techniques
[en] Selenium is both a nutrient and a toxin. Selenium—especially organic selenium—is a core component of human nutrition. Thus, it is very important to measure selenium in biological samples. The limited sensitivity of conventional XRF hampers its widespread use in biological samples. Here, we describe the use of high-energy (100 kV, 600 W) linearly polarized beam energy-dispersive X-Ray fluorescence spectroscopy (EDXRF) in tandem with a three-dimensional optics design to determine 0.1–5.1 μg g"−"1 levels of selenium in biological samples. The effects of various experimental parameters such as applied voltage, acquisition time, secondary target and various filters were thoroughly investigated. The detection limit of selenium in biological samples via high-energy (100 kV, 600 W) linearly polarized beam energy-dispersive X-ray fluorescence spectroscopy was decreased by one order of magnitude versus conventional XRF (Paltridge et al., 2012) and found to be 0.1 μg/g. To the best of our knowledge, this is the first report to describe EDXRF measurements of Se in biological samples with important implications for the nutrition and analytical chemistry communities. - Highlights: • The high-energy (100 kV, 600 W) linearly polarized beam energy-dispersive X-Ray fluorescence spectroscopy (EDXRF) was used to determine 0.1−5.1 μg g"−"1 levels of selenium in biological samples. • High-pressure pressed powder pellet technique (1500 kN) is used for sample preparation. • The detection limit of selenium in biological samples found to be 0.1 μg/g.
[en] Magnetic polyelectrolyte complex (PEC) based on chitosan and sodium ligninsulfonate as the support to stabilize Fe/Pd bimetallic particles (mPEC-Fe/Pd) were synthesized for the degradation and decolorization of organic pollutants in aqueous solution. The morphologies and structures of the as-obtained composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). Various factors potentially influencing the decolorization performance of methyl blue (MB) and malachite green (MG) from aqueous solution (i.e., mPEC-Fe/Pd dosage, solution pH, initial dye concentration and reaction temperature) were investigated. mPEC-Fe/Pd exhibited higher catalytic activity towards the removal of MB and MG, which involved both adsorption of dye molecules on mPEC surface and reduction reaction by Fe/Pd particles. Nearly 99% and 91% of MB and MG were removed at initial dye concentration of 100 mg l−1 with 1.0 g l−1 of mPEC-Fe/Pd, respectively. The decolorization efficiency of MB and MG increased with the increase of solution pH and mPEC-Fe/Pd dosage but decreased with the increase of initial dye concentrations. mPEC-Fe/Pd could be recycled effectively, and the removal percentage of MB reached as high as 83.5% even at the eighth reuse. Furthermore, the catalytic performances were further investigated to remove other organic pollutants, in which 92.4% of oxytetracycline, 85.1% of Tetrabromobisphenol A, and 34.7% of norfloxacin were removed at 50 mg l−1 of aqueous solution using 1.0 g l−1 of mPEC-Fe/Pd. Due to high removal efficiency, rapid reaction rate, easy separation and good reusability, mPEC-Fe/Pd had the potential to become an environmental remediation material for the treatment of wastewater containing organic compounds. (paper)
[en] [Co(0.6 nm)/ZnO(x nm)]60 (x= 0.4nm, 3nm) films were deposited on glass substrates then annealed in a vacuum. The magnetisation of the films increased with annealing but not the magnitude of the magneto-optical signals. The dielectric functions Im εxy for the films were calculated using the MCD spectra. A Maxwell Garnett theory of a metallic Co/ZnO mixture is presented. The extent to which this explains the MCD spectra taken on the films is discussed.
[en] (Ternary liquid + liquid) equilibria (tie-lines) of (water + acetone + α-pinene) at T = (288.15, 298.15, and 308.15) K and (water + acetone + β-pinene, or limonene) at T = 298.15 K have been measured. The experimental (ternary liquid + liquid) equilibrium data have been correlated successfully by the original UNIQUAC and modified UNIQUAC models. The modified UNIQUAC model reproduced accurately the experimental results for the (water + acetone + α-pinene) system at all the temperatures but fairly agreed with the experimental data for the (water + acetone + β-pinene, or limonene) systems.
[en] Mutual solubility data of imidazolium-based ionic liquid, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([bmmim][BF4]) with the alcohols, 1-propanol, 2-propanol, 1-butanol, 1-pentanol, and 1-hexanol were obtained by a cloud point method. The upper critical solution temperatures of the ionic liquid and alcohol mixtures were determined from the mutual solubility data. The upper critical solution temperature of the binary mixtures gradually increased as the chain length of the alcohol increased. The mutual solubility data of binary systems ([bmmim][BF4] + alcohols) have been correlated by the original UNIQUAC model as well as the extended and modified form of the UNIQUAC model. The temperature dependence of the mutual solubility data could be represented in terms of the temperature dependence of the binary energy parameters obtained from the correlation. Additionally the influence of water contamination on the ionic liquid mixture was shown experimentally by adding pure water into the binary mixture ([bmmim][BF4] + 1-butanol).
[en] Mutual solubility data of the binary (methanol + limonene) mixture at the temperatures ranging from 288.15 K close to upper critical solution temperature, and ternary (liquid + liquid) equilibrium (tie-lines) of the (methanol + ethanol + limonene) mixture at the temperatures (288.15, 298.15, and 308.15) K have been obtained. The experimental results have been represented accurately in terms of the extended and modified UNIQUAC models with binary parameters, compared with the UNIQUAC model. The temperature dependence of binary and ternary (liquid + liquid) equilibrium for the binary (methanol + limonene) and ternary (methanol + ethanol + limonene) mixtures could be calculated successfully using the extended and modified UNIQUAC model
[en] Nanostructured ZnO–Co and ZnO films with Pt, Cu, and Co as top electrodes, and Pt as bottom electrodes were grown by magnetron sputtering. Both ZnO–Co and ZnO films show bipolar resistive switching characteristics. The resistive switching properties of ZnO films are strongly dependent on the top electrode materials. The effect of top electrodes on resistive switching of ZnO–Co films is weakened due to the dominant roles of Co particles in the films. It is different with ZnO films that the ZnO–Co film shows a forming-free process. The calculation from the classical electromagnetism theory indicates that the existence of Co nanoparticles in the ZnO switching matrix can enhance the local electrical field to some extent, and decrease the operating voltages. So the device with a ZnO–Co film as a switching matrix can significantly reduce power consumption, weaken the dependence of the electrode materials, and optimize the resistive switching performance. (paper)
[en] Highlights: ► Mutual solubilities of imidazolium tetrafluoroborates with 1-alkanol were measured using light-scattering apparatus. ► UCSTs increased as increasing chain length of alcohol and decreasing alkyl chain length of cation ring. ► Experimental results were correlated accurately by extended UNIQUAC model. - Abstract: The mutual solubility of ionic liquids (ILs), 1-butyl-3-ethylimidazolium tetrafluoroborate, 1-butyl-3-propylimidazolium tetrafluoroborate, and 1,3-dibutylimidazolium tetrafluoroborate with alcohols, 1-propanol, 1-butanol, 1-pentanol, and 1-hexanol were measured at atmospheric pressure. Upper critical solution temperatures (UCSTs) were estimated from experimental results using a polynomial equation. The UCSTs increased as increasing the chain length of alcohol. On other hand, the decreasing UCSTs occurred when the alkyl chain length on the cation of ionic liquids increased. The (liquid + liquid) equilibrium data were correlated by the original UNIQUAC, extended UNIQUAC, and modified UNIQUAC models. The temperature dependence of the solubility of ILs in alcohols and alcohols in ILs is represented successfully using the UNIQUAC, extended UNIQUAC, and modified UNIQUAC models with a quadratic function of temperature for binary energy parameters.
[en] The Si2Sb2Te5 phase change material has been studied by applying a nano-tip (30 nm in diameter) on an atomic force microscopy system. Memory switching from a high resistance state to a low resistance state has been achieved, with a resistance change of about 1000 times. In a typical I-V curve, the current increases significantly after the voltage exceeds ∼4.3 V. The phase transformation of a Si2Sb2Te5 film was studied in situ by means of in situ X-ray diffraction and temperature dependent resistance measurements. The thermal stability of Si2Sb2Te5 and Ge2Sb2Te5 was characterized and compared as well.