Tong K.,Southwest University of Science and Technology
Nanotechnology, Science and Applications | Year: 2017
The aim of this study was to assess the effect of alginate-chitosan microcapsule on viability characteristics of Bacillus subtilis and the ability of B. subtilis/alginate-chitosan microcapsule to remove uranium ion from aqueous solution. The effects of particle size, chitosan molecular weight and inoculum density on viability characteristics were studied using alginate-chitosan microcapsule-immobilized B. subtilis experiments. In addition, the effects of pH, immobilized spherule dosage, temperature, initial uranium ion concentration and contact time on removal of uranium ion were studied using batch adsorption experiments. The results showed that alginate-chitosan microcapsule significantly improved the viability characteristics of B. subtilis and that B. subtilis/alginate-chitosan microcapsule strongly promoted uranium ion absorption. Moreover, the optimum values of pH was 6; immobilized spherule dosage was 3.5; temperature was 20°C; initial uranium ion concentration was 150 mg/L; contact time was 3 h of uranium ion absorption and the maximum adsorption capacity of uranium ion was 376.64 mg/g. © 2017 Tong.
Zhen W.,Southwest University of Science and Technology
Applied Surface Science | Year: 2017
Flotation and adsorption performance of sodium oleate(NaOl)on powellite and fluorapatite were investigated in this work through micro-flotation tests, work of adhesion calculations, molecular dynamics simulation, micro-topography studies and FTIR measurements. The micro-flotation results show a similar flotation behaviors of powellite and fluorapatite under alkaline conditions, but a considerable difference in mineral recoveries in the pH range 2–7, which demonstrates the possibilities for separating powillite from fluorapatite under acidic conditions. The great difference in mineral recovery displays a good accordance with the obvious difference in the work of adhesion of powellite and fluorapatite at NaOl dosage range of 40–80 mg/L, obtained from flotation and contact angle measurements, respectively. The more negative interaction energy (ΔE) between NaOl and powellite/water interface from molecular dynamics simulation reveals a more easily adsorption of NaOl onto powellite than onto fluorapatite, which excellently matches with the results of flotation and work of adhesion. The results of micro-topography study shows that the adsorption of NaOl on powellite is mainly ascribed to the chemisorption of oleate ions with Ca2+ on powellite lattice or the precipitation of calcium dioleate agglomerates on powellite surface when it was in the solution without or with Ca2+, respectively. The FTIR measurements further confirm the chemisorption of oleate ions with Ca2+ active sites on powellite surface. © 2017 Elsevier B.V.
Liu M.,Southwest University of Science and Technology
Laser Physics Letters | Year: 2017
A flexible thermal lens microscope (TLM), which combines the advantages of both conventional thermal lens spectrometry and TLM, is reported in this paper. The flexibility lies in the fact that the TLM can be configured in diffraction-limited (DL) or non-DL excitation mode: in small micro spaces (<50 μm), the setup can work in DL mode (as in previous TLMs) and shows a limit of detection (LOD) of 2 × 105 cm1; in large micro spaces (50-1000 μm),the setup working in non-DL mode was demonstrated to be much more advantageous. Compared with the case in DL mode, the TLM in non-DL mode shows up to an eight times lower LOD under 100-1000-fold less intense excitation, and better resistivity to flow-induced signal reduction and fluctuation to beam misalignment and background scattering, making it particularly suitable for detecting photolabile samples in highly flowing scattering mediums. For photostable samples, excitation laser powers of watt scale (in contrast to 100 mW in DL mode) could be employed to further decrease the LOD. This flexible TLM can therefore be applied for highly sensitive on-chip analysis of a broad range of analytes in different mediums. © 2017 Astro Ltd.
Jia L.-B.,Southwest University of Science and Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016
In this article, we focus on new scalar φ mediated scalar/vectorial weakly interacting massive particles (WIMPs) with φ's mass slightly below the WIMP mass. To explain the Galactic center 1-3 GeV gamma-ray excess, here we consider the case that a WIMP pair predominantly annihilates into an on-shell φφ pair with φ mainly decaying to ττ. The masses of WIMPs are in a range about 14-22 GeV, and the annihilations of WIMPs are phase space suppressed today. In this annihilation scheme, the couplings of the φ-standard model (SM) particles are almost arbitrarily small, and the WIMP-nucleus spin-independent scattering can be tolerant by the present dark matter (DM) direct detections. A scalar mediator-Higgs field mixing is introduced, which is small and available. The lower limit on the couplings of the φ-SM particles set by the thermal equilibrium in the early Universe is derived, and this constraint is above the neutrino background for scalar DM in direct detections. The WIMPs may be detectable at the upgraded DM direct detection experiment in the next few years, and the exotic decay h→φφ, the production of φ may be observable at the future high-luminosity e+e- collider. © 2016 American Physical Society.
Xiang W.,Southwest Jiaotong University |
Xiao J.,Southwest University of Science and Technology
International Journal of Robust and Nonlinear Control | Year: 2012
In this paper, we investigate the stability analysis problem of switched impulsive nonlinear systems and several stabilization problems of switched discrete-time linear systems are studied. First, sufficient conditions ensuring globally uniformly asymptotically stability of switched nonlinear impulsive system under arbitrary and DDT (dynamical dwell time which defines the length of the time interval between two successive switchings) switching are derived, respectively. In the DDT switching case, we first consider the switched system composed by stable subsystems, then we extend the results to the case where not all subsystems are stable. The stabilizations of switched discrete-time linear system under arbitrary switching, DDT switching and asynchronous switching are investigated respectively. Based on the stability analysis results, the control synthesis consists of controller design for each subsystem and state impulsive jumping generators design at switching instant. With the aid of the state impulsive jumping generators at switching instant, the 'energy' produced by switching can be minimized, which leads to less conservative results. Several numerical examples are given to illustrate the proposed results within this paper. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.
Fan X.-Y.,Southwest University of Science and Technology
Yantu Lixue/Rock and Soil Mechanics | Year: 2011
Based on systematic analysis of the landslide displacements and its evolvement characteristics, a detailed research is performed on the features of the complexity, catastrophe and nonlinearity in terms of the basic principle of multifractal. The single fractals are deficiencies in prediction of evolvement trend of landslide displacement. The evolvement of landslide displacement is determined by the multifractal dimensions. Firstly, taking the typical landslides-The Xintan landslide, Danba landslide and Huanglashi landslide as the practical examples, the evolvement of multifractal dimensions of the displacement-time are calculated. Secondly, the correlation between the displacement evolvement and multifractal dimensions is studied. It is found that the landslides are stable when the multifractal dimensions are D1 > D2 > ⋯ > D∞ and the landslides are unstable when the multifractal dimensions are D1 < D2 < ⋯ < D∞. Moreover, if there were inflexions in the multifractal dimensions of landslide displacements-time the landslide stability would change. For example, they are from D1 > D2 > ⋯ > D∞, through D1 > ⋯ > Dn < Dn+1 < ⋯ < D∞ to D1 < D2 < ⋯ < D∞, the landslides are unstable gradually. On the contrary, when they were from D1 < D2 < ⋯ < D∞, through D1 > ⋯ > Dn < Dn+1 < ⋯ < D∞ to D1 > D2 > ⋯ > D∞, the landslides are stable gradually. The study results show that the multifractal dimensions of displacement are an effective method to evaluate and predict landslide displacement evolvement.
Jia L.-B.,Southwest University of Science and Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
The recent astronomical observation of GeV gamma-ray excess from the Galactic center was suggested due to a bb¯ mode in the tens GeV of weakly interacting massive particle (WIMP) pair annihilations, and this mode was also explored by the new dwarf galaxy observation. Considering the case where the WIMP pair mass is below the top quark mass, a pseudoscalar φ is studied in this article, which mediates the interactions between the standard model fermions and fermionic WIMPs and the neutral flavor-changing interactions in standard model fermion sectors. The bb¯ mode is favored in WIMP pair annihilations, while the WIMP-nucleus scattering is highly suppressed in direct detection. Alternative schemes of t→c decay and single top production are employed to search the WIMPs. Assuming the mass of the WIMPs is around 5-60 GeV and with reasonable inputs by the constraints, the branching ratio Bt→cχ¯χ of a top quark decaying into a charm quark and a WIMP pair is derived of order 10-8-10-5; thus, careful studies in the future on top physics may help to gain a better understanding of WIMPs. © 2015 American Physical Society.
Zhou L.,Southwest University of Science and Technology
IEEE Transactions on Fuzzy Systems | Year: 2016
In this paper, we propose a method to construct homeomorphisms from the interior of intuitionistic fuzzy interpretation triangle to the complex plane. Based on such homeomorphisms, we define concepts of pure intuitionistic fuzzy sets and pure intuitionistic fuzzy numbers, and obtain some properties of these new concepts. In addition, we prove that all the pure intuitionistic fuzzy numbers form a field, whose arithmetic operations are given. Finally, we use two numerical examples to show computational skills in such field. © 1993-2012 IEEE.
Jiang Y.Q.,Southwest University of Science and Technology
Applied Mechanics and Materials | Year: 2014
This paper aims to mimic the herd behavior of pedestrian flow, i.e., the tendency towards majority when a congestion occurs, by macroscopic modeling approach. The macroscopic pedestrian simulation model is composed of a mass-conservation equation and a simple model to reflect behavioral characteristics of pedestrians based on a specific traffic situation. Numerical experiments are designed to show some preliminary results, e.g. the beneficial effect of herding on evacuation time in some situations. © (2014) Trans Tech Publications, Switzerland.
Zeng M.,Southwest University of Science and Technology
Applied Surface Science | Year: 2011
Well-crystallized cubic phase BaTiO3 particles were prepared by heating the mixture of barium hydroxide aqueous solution and titania derived from the hydrolysis of titanium isopropoxide (TTIP) at 328 K, 348 K or 368 K for 24 h. The morphology and size of obtained particles depended on the reaction temperature and the Ba(OH)2/TTIP molar ratio. By the direct hydrolytic reaction of titanium tetraisopropoxide, the high surface area titania (TiO2) was obtained. The surface adsorption characteristics of the titania particles had been studied with different electric charges OH - ions or H+ ions. The formation mechanism and kinetics of BaTiO3 were examined by measuring the concentration of [Ba 2+] ions in the solution during the heating process. The experimental results showed that the heterogeneous nucleation of BaTiO3 occurred on the titania surface, according to the Avrami's equation. © 2011 Elsevier B.V. All rights reserved.