Showing papers by "Nankai University published in 2005"
1,537 citations
TL;DR: In this paper, a porous-alumina-template method was used to obtain high discharge capacity and superior cycling reversibility of Co3O4 nanotubes, which exhibited excellent sensitivity to hydrogen and alcohol, owing to their hollow, nanostructured character.
Abstract: Co3O4 nanotubes, nanorods, and nanoparticles are used as the anode materials of lithium-ion batteries. The results show that the Co3O4 nanotubes prepared by a porous-alumina-template method display high discharge capacity and superior cycling reversibility. Furthermore, Co3O4 nanotubes exhibit excellent sensitivity to hydrogen and alcohol, owing to their hollow, nanostructured character.
1,134 citations
TL;DR: In this paper, the authors aim at the construction of dark energy models without exotic matter but with a phantomlike equation of state (an effective phantom phase) and propose a generalized holographic model, which is produced by the presence of an infrared cutoff.
Abstract: We aim at the construction of dark energy models without exotic matter but with a phantomlike equation of state (an effective phantom phase) The first model we consider is decaying vacuum cosmology where the fluctuations of the vacuum are taken into account In this case, the phantom cosmology (with an effective, observational $\ensuremath{\omega}$ being less than $\ensuremath{-}1$ ) emerges even for the case of a real dark energy with a physical equation of state parameter $\ensuremath{\omega}$ larger than $\ensuremath{-}1$ The second proposal is a generalized holographic model, which is produced by the presence of an infrared cutoff It also leads to an effective phantom phase, which is not a transient one as in the first model However, we show that quantum effects are able to prevent its evolution towards a big rip singularity
444 citations
TL;DR: Both batch experiments and column experiments indicated that BCF had higher removal efficiency for arsenite than for arsenate, whereas Arsenate elimination was favored at acidic pH, whereas the adsorption of arsenite by BCF was found to be effective in a wide pH range of 5-11.
Abstract: A new adsorbent, bead cellulose loaded with iron oxyhydroxide (BCF), was prepared and applied for the adsorption and removal of arsenate and arsenite from aqueous systems. The continuing loading process of Fe in the cellulose beads was realized through hydrolization of ferric salts when alkaline solution was added dropwise. Spherical BCF had excellent mechanical and hydraulic properties. Akaganeite (beta-FeOOH), the reactive center of BCF that was stably loaded into the cellulose, had a high sensitivity to arsenite as well as arsenate. The maximum content of Fe in BCF reached 50% (w/w). In this study we investigated the adsorption behavior of arsenite and arsenate on BCF, including adsorption isotherms, adsorption kinetics, the influence of pH and competing anions on adsorption, and column experiments. The adsorption data accorded with both Freundlich and Langmuir isotherms. The adsorption capacity for arsenite and arsenate was 99.6 and 33.2 mg/g BCF at pH 7.0 with an Fe content of 220 mg/ mL. Kinetic data fitted well to the pseudo-second-order reaction model. Arsenate elimination was favored at acidic pH, whereas the adsorption of arsenite by BCF was found to be effective in a wide pH range of 5-11. Under the experimental conditions, the addition of sulfate had no effect on arsenic adsorption, whereas phosphate greatly influenced the elimination of both arsenite and aresenate. Silicate moderately decreased the adsorption of arsenite, but not arsenate. Both batch experiments and column experiments indicated that BCF had higher removal efficiency for arsenite than for arsenate. While the influent contaminant concentration was 500 microg/L in groundwater and the empty-bed contact time (EBCT) for arsenite and arsenate was 4.2 and 5.9 min, breakthrough empty-bed volumes at the WHO provisional guideline value of 10 microg/L were 2200 and 5000, respectively. BCF can be effectively regenerated when elution is done with 2 M NaOH solution. The column experiments for four cycles showed that stable and high removal efficiency of arsenic was sustained by BCF after regeneration.
361 citations
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TL;DR: G-frames as mentioned in this paper are generalized frames which include ordinary frames, bounded invertible linear operators, as well as many recent generalizations of frames, e.g., bounded quasi-projectors and frames of subspaces.
Abstract: G-frames are generalized frames which include ordinary frames, bounded invertible linear operators, as well as many recent generalizations of frames, e.g., bounded quasi-projectors and frames of subspaces. G-frames are natural generalizations of frames and provide more choices on analyzing functions from frame expansion coefficients. We give characterizations of g-frames and prove that g-frames share many useful properties with frames. We also give generalized version of Riesz bases and orthonormal bases. As an application, we get atomic resolutions for bounded linear operators.
328 citations
TL;DR: In this article, a template-free control of the degree of crystallinity, crystal structure, and morphology of these types of nanoscale sodium titanate products is presented, and the performance of the dehydrated hydrogen titanate nanotubes and nanorods is explored in terms of their potential performance as anode materials for lithium-ion batteries.
Abstract: Various sized hollow nanotubes and solid nanorods are synthesized from rutile powder (particle size ≈ 120–280 nm) using a relatively simple chemical approach in alkaline solution. The nanotubes and nanorods occur as hydrated phases: TiO2·1.25H2O and TiO2·1.0H2O, respectively. The rutile particles react in concentrated NaOH solution under hydrothermal conditions, yielding layered sodium titanate in the form of either polycrystalline nanotubes or single-crystal nanorods. The form of the product depends on the temperature and time of hydrothermal reaction: Therefore, this is a report of the template-free control of the degree of crystallinity, crystal structure, and morphology of these types of nanoscale sodium titanate products. By treating the nanotubes and nanorods with dilute HCl, the sodium ions within them could be exchanged for protons, and the morphology of the nanotubes and nanorods is retained, resulting in hydrogen titanate nanotubes and nanorods. The electrochemical performance of dehydrated hydrogen titanate nanotubes and nanorods is explored in terms of their potential performance as anode materials for lithium-ion batteries. The discharge capacity is higher for thin anatase nanorods converted from hydrogen titanate nanotubes when compared to the calcined (at 500 °C and 700 °C) products of hydrogen titanate nanorods. The significance of these findings is the possibility of fabricating delicate, nanostructured materials directly from industrial raw materials, because the natural mineral of titanium dioxide and most of the raw industrial TiO2 products exist in the rutile phase.
310 citations
TL;DR: The prepared ion-imprinted functionalized sorbent was shown to be promising for on-line, solid-phase extraction coupled with flame atomic absorption spectrometry for the determination of trace cadmium in environmental and biological samples.
Abstract: A new ion-imprinted thiol-functionalized silica gel sorbent was synthesized by a surface imprinting technique in combination with a sol−gel process for selective on-line, solid-phase extraction of Cd(II). The Cd(II)-imprinted thiol-functionalized silica sorbent was characterized by FT-IR, the static adsorption−desorption experiment, and the dynamic adsorption−desorption method. The maximum static adsorption capacity of the ion-imprinted functionalized sorbent was 284 μmol g-1. The largest selectivity coefficient for Cd(II) in the presence of Pb(II) was over 220. The static uptake capacity and selectivity coefficient of the ion-imprinted functionalized sorbent are higher than those of the nonimprinted sorbent. The breakthrough capacity and dynamic capacity of the imprinted functionalized silica gel sorbent for 4 mg L-1 of Cd(II) at 5.2 mL min-1 of sample flow rate were 11.7 and 64.3 μmol g-1, respectively. No remarkable effect of sample flow rate on the dynamic capacity was observed as the sample flow rate...
308 citations
TL;DR: In this paper, the authors study the evolution of a supernova core from the beginning of the gravitational collapse of a 15 M☉ star up to 1 s after core bounce and compare two sets of EOS, namely, those by Lattimer and Swesty (LS-EOS) and by Shen et al. (SH-Eos).
Abstract: We study the evolution of a supernova core from the beginning of the gravitational collapse of a 15 M☉ star up to 1 s after core bounce. We present results of spherically symmetric simulations of core-collapse supernovae by solving general relativistic ν-radiation hydrodynamics in the implicit time differencing. We aim to explore the evolution of shock waves in the long term and investigate the formation of proto-neutron stars together with supernova neutrino signatures. These studies are done to examine the influence of the equation of state (EOS) on the postbounce evolution of shock waves in the late phase and the resulting thermal evolution of proto-neutron stars. We compare two sets of EOSs, namely, those by Lattimer and Swesty (LS-EOS) and by Shen et al. (SH-EOS). We found that, for both EOSs, the core does not explode and the shock wave stalls similarly in the first 100 ms after bounce. A revival of the shock wave does not occur even after a long period in either case. However, the recession of the shock wave appears different beyond 200 ms after bounce, having different thermal evolution of the central core. A more compact proto-neutron star is found for LS-EOS than SH-EOS with a difference in the central density by a factor of ~2 and a difference of ~10 MeV in the peak temperature. The resulting spectra of supernova neutrinos are different to an extent that may be detectable by terrestrial neutrino detectors.
296 citations
280 citations
TL;DR: A strain--temperature sensor that makes use of those characteristics, which is new for applications of HiBi-FLMs, has been proposed and demonstrated and the experimental results are in good agreement with the theoretical analysis.
Abstract: The reflection and transmission characteristics of a high-birefringence fiber loop mirror (HiBi-FLM), which is composed of a standard fiber coupler and one-section or multisection high-birefringence fibers (HBFs), are analyzed and discussed in detail. Theoretical reflectivity and transmissivity expressions for HiBi-FLMs with one-, two-, and three-section HBFs were obtained. The procedure for calculating reflectivity and transmissivity for HiBi-FLMs with n-section HBFs is given. Experimental results have verified the theoretical model. The basic characteristics of the one-section HiBi-FLM when strain and high temperature are applied to HBFs were analyzed and investigated theoretically and experimentally. The experimental results are in good agreement with the theoretical analysis. Furthermore, a strain– temperature sensor that makes use of those characteristics, which is new for applications of HiBi-FLMs, has been proposed and demonstrated.
278 citations
TL;DR: In this paper, different carbon support materials including single-walled carbon nanotubes (SWNTs), multilayer carbon nanotsubes (MWNTs) and XC-72 carbon black, were compared in terms of their electrochemical properties using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).
TL;DR: In this paper, the authors study the evolution of supernova core from the beginning of gravitational collapse of a 15Msolar star up to 1 second after core bounce and examine the influence of equation of state (EOS) on the postbounce evolution of shock wave in the late phase and the resulting thermal evolution of protoneutron star.
Abstract: We study the evolution of supernova core from the beginning of gravitational collapse of a 15Msolar star up to 1 second after core bounce. We present results of spherically symmetric simulations of core-collapse supernovae by solving general relativistic neutrino-radiation-hydrodynamics in the implicit time-differencing. We aim to explore the evolution of shock wave in a long term and investigate the formation of protoneutron star together with supernova neutrino signatures. These studies are done to examine the influence of equation of state (EOS) on the postbounce evolution of shock wave in the late phase and the resulting thermal evolution of protoneutron star. We make a comparison of two sets of EOS, that is, by Lattimer and Swesty (LS-EOS) and by Shen et al.(SH-EOS). We found that, for both EOSs, the core does not explode and the shock wave stalls similarly in the first 100 milliseconds after bounce. The revival of shock wave does not occur even after a long period in either cases. However, the recession of shock wave appears different beyond 200 milliseconds after bounce, having different thermal evolution of central core. A more compact protoneutron star is found for LS-EOS than SH-EOS with a difference in the central density by a factor of ~2 and a difference of ~10 MeV in the peak temperature. Resulting spectra of supernova neutrinos are different to the extent that may be detectable by terrestrial neutrino detectors.
TL;DR: In this article, a new three-dimensional continuous quadratic autonomous chaotic system, modified from the Lorenz system, was reported, in which each equation contains a single quadralatic crossproduct term, which is different from the original Lorenz, Rossler, Chen, Lu systems.
Abstract: This paper reports a new three-dimensional continuous quadratic autonomous chaotic system, modified from the Lorenz system, in which each equation contains a single quadratic cross-product term, which is different from the Lorenz, Rossler, Chen, Lu systems. Basic properties of the new system are analyzed by means of Lyapunov exponent spectrum and bifurcation diagrams. Analysis results show that this system has complex dynamics with some interesting characteristics.
TL;DR: In this paper, the potential of Chinese clinoptilolite for ammonia removal from aqueous solution was assessed and the effects of relevant parameters, such as contact time, pH and initial ammonia concentration, were examined, respectively.
TL;DR: In this paper, an Ag/TiO2 catalyst with fine size and homogeneous dispersion of coated silver clusters was synthesized by a recently developed pH-controlled photocatalytic process.
TL;DR: In this article, an efficient and reusable heterogeneous basic catalysts for the synthesis of propylene carbonate from propylene oxide and CO2 under supercritical CO2 conditions (373 K, 8 MPa) were presented.
TL;DR: In this paper, the authors examine the ownership structure of 826 listed corporations and find that government shareholding is surprisingly large and its effect on corporate value is found to be negative, but non-monotonic.
Abstract: The role of government shareholding in corporate performance is central to an understanding of China's newly privatized large firms. In this paper, we analyze shareholders as agents that can both harm and benefit companies. We examine the ownership structure of 826 listed corporations and find that government shareholding is surprisingly large. Its effect on corporate value is found to be negative, but non-monotonic. Up to a certain threshold, corporate value decreases as government shareholding stakes increase, but beyond this corporate value begins to increase. We interpret this in terms of ownership concentration and the advantages of government partiality.
TL;DR: In this article, the authors take a phenomenological approach to the study of the cosmological evolution of decaying vacuum cosmology (Λ(t)CDM) based on a simple assumption about the form of the modified matter expansion rate.
Abstract: We take a phenomenological approach to the study of the cosmological evolution of decaying vacuum cosmology (Λ(t)CDM) based on a simple assumption about the form of the modified matter expansion rate. In this framework, almost all current vacuum decaying models can be unified in a simple manner. We argue that the idea of letting vacuum decay to resolve the fine-tuning problem is inconsistent with cosmological observations. We also discuss some issues in confronting Λ(t)CDM with observation. Using the effective equation-of-state formalism, we indicate that Λ(t)CDM is a possible candidate for phantom cosmology. Moreover, confronted with a possible problem with the effective equation-of-state formalism, we construct the effective dark energy density. Finally, we discuss the evolution of linear perturbation.
TL;DR: The PCP-imprinted amino-functionalized silica gel sorbent exhibited high selectivity and offered a fast kinetics for the adsorption and desorption of PCP and offered good linearity for on-line solid-phase extraction of trace levels ofPCP.
TL;DR: In this paper, the authors studied the thermoresponsive micellization of poly(ethylene glycol)-b-poly(N-isopropylacrylamide) (PEG110-b-PNIPAM44) in water by static light scattering and dynamic light scattering.
Abstract: Thermoresponsive micellization of poly(ethylene glycol)-b-poly(N-isopropylacrylamide) (PEG110-b-PNIPAM44) in water is studied by static light scattering and dynamic light scattering. The critical aggregation temperature of PEG110-b-PNIPAM44 is a little higher than homopolymer PNIPAM, and it depends on the block copolymer concentration, which increases from 33.7 to 38.4°C when the copolymer concentration decreases from 2.0 to 0.20 mg/mL. Above the critical aggregation temperature, thermoresponsive micellization occurs, and the resultant spherical micelles consist of a PNIPAM core and a PEG shell. The block copolymer concentration exerts a strong influence on the size and structure of the resultant micelles. Micellization of PEG110-b-PNIPAM44 at higher copolymer concentration favors formation of narrowly distributed, small, and dense micelles, while large, loose micelles or micellar clusters form at lower block copolymer concentration.
TL;DR: It was found that the nanotube electrodes exhibited better reversibility and higher discharge capacities than that of their nanocrystalline counterparts and the reason for the improved electrochemical performance was interpreted.
Abstract: The first point of this work is to synthesize LiCoO2, LiNi0.8Co0.2O2, and LiMn2O4 nanotubes with the template of porous anodic aluminum oxide by thermal decomposition of sol−gel precursors. The as-synthesized materials were open-ended nanotubes with uniform shape and size based on the analysis of scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. An “in situ reaction from nanoparticle to nanotube” mechanism was discussed for the formation process of the nanotubes. The second point of this paper is to investigate the electrochemical properties of the as-synthesized nanotubes for the cathode materials of lithium ion batteries. It was found that the nanotube electrodes exhibited better reversibility and higher discharge capacities than that of their nanocrystalline counterparts. The reason for the improved electrochemical performance of the nanotube electrodes was also interpreted.
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TL;DR: In this article, it was shown that the crossing number and the nesting number are distributed symmetrically over all partitions of the minimal block elements and maximal block elements, as well as over all matchings on the set partitions.
Abstract: We present results on the enumeration of crossings and nestings for matchings and set partitions. Using a bijection between partitions and vacillating tableaux, we show that if we fix the sets of minimal block elements and maximal block elements, the crossing number and the nesting number of partitions have a symmetric joint distribution. It follows that the crossing numbers and the nesting numbers are distributed symmetrically over all partitions of $[n]$, as well as over all matchings on $[2n]$. As a corollary, the number of $k$-noncrossing partitions is equal to the number of $k$-nonnesting partitions. The same is also true for matchings. An application is given to the enumeration of matchings with no $k$-crossing (or with no $k$-nesting).
01 Oct 2005
TL;DR: Lyapunov-based techniques are exploited to craft an adaptive controller that enables mobile robot position and orientation regulation despite the lack of an object model and the Lack of depth information.
Abstract: A monocular camera-based vision system attached to a mobile robot (i.e., the camera-in-hand configuration) is considered in this paper. By comparing corresponding target points of an object from two different camera images, geometric relationships are exploited to derive a transformation that relates the actual position and orientation of the mobile robot to a reference position and orientation. This transformation is used to synthesize a rotation and translation error system from the current position and orientation to the fixed reference position and orientation. Lyapunov-based techniques are used to construct an adaptive estimate to compensate for a constant, unmeasurable depth parameter, and to prove asymptotic regulation of the mobile robot. The contribution of this paper is that Lyapunov techniques are exploited to craft an adaptive controller that enables mobile robot position and orientation regulation despite the lack of an object model and the lack of depth information. Experimental results are provided to illustrate the performance of the controller.
TL;DR: A series of novel two-dimensional and three-dimensional praseodymium coordination polymers were designed and synthesized under hydrothermal conditions and exhibited various and intriguing topological structures from a 1D chain to a 3D network.
Abstract: A series of novel two-dimensional (2D) and three-dimensional (3D) praseodymium coordination polymers, namely, {[Pr3(PDA)4(HPDA)(H2O)8]·8H2O}n (2), {[Pr2(PDA)3(H2O)3]·H2O}n (3), {[Pr(PDA)(H2O)4]·ClO4}n (4), and {[Pr2(PDA)2(H2O)5SO4]·2H2O}n (5) (PDA = pyridine-2,6-dicarboxylic anion), was designed and synthesized under hydrothermal conditions. Complexes 1−3 (chainlike polymer, {[Pr(PDA)(HPDA)(H2O)2]·4H2O}n (1) was also obtained independently by us, although it has been reported recently by Ghosh et al.) were fabricated successfully by simply tuning the Pr/PDA ratio and exhibited various and intriguing topological structures from a 1D chain to a 3D network. While the synthetic strategy of 5 was triggered and further performed only after 1 was structurally characterized. The complexes were characterized by X-ray single-crystal determination, spectroscopic, and variable-temperature magnetic susceptibility analyses. In complex 2 an unusual nanosized square motif as a building block constructed by eight Pr ions ...
TL;DR: In this article, the biomimetic chemistry of single and double oxadithiolatodiiron-containing model compounds for the active site of Fe-only hydrogenases (FeHases) has been systematically studied.
TL;DR: In this article, the structure, thermal properties and crystallization behaviors of the nanocomposite were studied by means of X-ray diffraction, differential scanning calorimetry, thermogravimetry analysis, and polarizing optical microscopy.
TL;DR: In this paper, the formation and chemical reactivities of the butterfly Fe/S cluster anions (μ-S-)2Fe2(CO)6 (I), (μS-S-)(μ-RS)Fe2[1]6]2(μ4-S)2 (II), (M S-SZS-μ)2(M SZS)
Abstract: This Account describes the formation and chemical reactivities of the novel butterfly Fe/S cluster anions (μ-S-)2Fe2(CO)6 (I), (μ-S-)(μ-RS)Fe2(CO)6 (II), (μ-S-)(μ-RS)[Fe2(CO)6]2(μ4-S) (III), (μ-S-)(μ-RS)[Fe2(CO)6]3(μ4-S)2 (IV), and {(μ-S-)(μ4-S)[Fe2(CO)6]2}2(μ-SZS-μ) (V). It also gives a description of the novel structures, unique properties, and wide applications of the corresponding butterfly Fe/S cluster complexes produced from these anions. Anions I−V along with their products are important in the development of organometallic chemistry, cluster chemistry, catalysis, and material and life sciences.
TL;DR: In this article, a right-handed helical infinite chain was constructed in triazole compounds, where the supramolecular helical chain and the coordination chain formed a unique double helical structure.
Abstract: Using similar synthesis conditions and a flexible ligand, 1,2-bis(1,2,4-triazole-1-yl)ethane (L), we isolated novel right-handed helical infinite chain [Zn(L)(Cl)2] (1), two-dimensional (2D) coordination polymers [M(L)2(H2O)2]·(NO3)2 [M = Zn (2), Cd (3)], and a one-dimensional (1D) double-bridged complex [Cd(L)2(H2O)2]·(ClO4)2(H2O)2 (4), where anions could tune the self-assemblies to form different supramolecular and coordination networks. Compound 1 is the first infinite helix in triazole compounds, where the supramolecular helical chain and the coordination chain form a unique double helical structure. Nitrate and perchlorate anions induced different supramolecular structures, which lead to the first case of the self-assembled CdN4O2 polyhedra from 2D to 1D coordination polymers for 3 and 4, respectively.
TL;DR: In this article, the structure, morphologies, composition, and properties of the as-synthesized SnS and SnS 2 products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), transmission electron microscope (TEM) and high-resolution TEM (HRTEM), and Raman Spectroscopy, which showed that SnS nanoparticles possessed a multilayer nanostructure with an average diameter of 30-100nm.
TL;DR: In this paper, the catalytic properties of the prepared catalysts for low-temperature CO oxidation were studied by using a microreactor-GC system and the results showed that the thermal decomposition temperature affected the physical properties of prepared CeO 2 particles, such as particle size and morphology.
Abstract: CeO 2 nanoparticles were prepared by thermal decomposition of cerous nitrate and then used as supports for CuO/CeO 2 catalysts prepared via the impregnation method. The samples were characterized by HRTEM, XRD, H 2 -TPR, and XPS. The catalytic properties of the prepared catalysts for low-temperature CO oxidation were studied by using a microreactor–GC system. The results showed that the thermal decomposition temperature affected the physical properties of the prepared CeO 2 particles, such as particle size and morphology. The loading of CuO in non-crystalline forms on CeO 2 supports was different in the CuO/CeO 2 catalysts. The loading of non-crystalline CuO was higher on the CeO 2 prepared via thermal decomposition at 500 °C than those on the CeO 2 prepared via thermal decomposition at 400, 600 and 700 °C. One part of the non-crystalline CuO in CuO/CeO 2 catalysts entered the CeO 2 lattice and the other part dispersed over the CeO 2 surface. Calcination temperature had little effect on the catalytic activity when it was lower than 600 °C. However, heating the catalysts to higher temperatures (i.e. 800 °C) had a significant impact on the catalytic activity because the crystallite size rapidly grows and more CuO and CeO 2 phase-separation occurs.