Showing papers by "Xiamen University published in 2007"
TL;DR: Platinum NCs of unusual tetrahexahedral (THH) shape were prepared at high yield by an electrochemical treatment of Pt nanospheres supported on glassy carbon by a square-wave potential to exhibit much enhanced catalytic activity for equivalent Pt surface areas for electro-oxidation of small organic fuels such as formic acid and ethanol.
Abstract: The shapes of noble metal nanocrystals (NCs) are usually defined by polyhedra that are enclosed by {111} and {100} facets, such as cubes, tetrahedra, and octahedra. Platinum NCs of unusual tetrahexahedral (THH) shape were prepared at high yield by an electrochemical treatment of Pt nanospheres supported on glassy carbon by a square-wave potential. The single-crystal THH NC is enclosed by 24 high-index facets such as {730}, {210}, and/or {520} surfaces that have a large density of atomic steps and dangling bonds. These high-energy surfaces are stable thermally (to 800°C) and chemically and exhibit much enhanced (up to 400%) catalytic activity for equivalent Pt surface areas for electro-oxidation of small organic fuels such as formic acid and ethanol.
2,782 citations
TL;DR: In this article, a sundried biomass of Cinnamomum camphora leaf with aqueous silver or gold precursors at ambient temperature was used for simple synthesis of nanoparticles.
Abstract: The synthesis of nanocrystals is in the limelight in modern nanotechnology. Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Not only could silver nanoparticles ranging from 55 to 80 nm in size be fabricated, but also triangular or spherical shaped gold nanoparticles could be easily modulated by reacting the novel sundried biomass of Cinnamomum camphora leaf with aqueous silver or gold precursors at ambient temperature. The marked difference of shape control between gold and silver nanoparticles was attributed to the comparative advantage of protective biomolecules and reductive biomolecules. The polyol components and the water-soluble heterocyclic components were mainly responsible for the reduction of silver ions or chloroaurate ions and the stabilization of the nanoparticles, respectively. The sundried leaf in this work was very suitable for simple synthesis of nanoparticles.
1,614 citations
TL;DR: It is proved that the full discretization is unconditionally stable, and the numerical solution converges to the exact one with order O(@Dt^2^-^@a+N^- ^m), where @Dt,N and m are the time step size, polynomial degree, and regularity of the exact solution respectively.
1,420 citations
TL;DR: In this paper, simultaneous measurements of atmospheric organic and elemental carbon (OC and EC) were taken during winter and summer seasons at 2003 in 14 cities in China, and PM2.5 samples were analyzed for OC and EC by the Interagency Monitoring of Protected Visual Environments (IMPROVE) thermal/optical reflectance protocol.
Abstract: [1] Simultaneous measurements of atmospheric organic and elemental carbon (OC and EC) were taken during winter and summer seasons at 2003 in 14 cities in China. Daily PM2.5 samples were analyzed for OC and EC by the Interagency Monitoring of Protected Visual Environments (IMPROVE) thermal/optical reflectance protocol. Average PM2.5 OC concentrations in the 14 cities were 38.1 μg m−3 and 13.8 μg m−3 for winter and summer periods, and the corresponding EC were 9.9 μg m−3 and 3.6 μg m−3, respectively. OC and EC concentrations had summer minima and winter maxima in all the cities. Carbonaceous matter (CM), the sum of organic matter (OM = 1.6 × OC) and EC, contributed 44.2% to PM2.5 in winter and 38.8% in summer. OC was correlated with EC (R2: 0.56–0.99) in winter, but correlation coefficients were lower in summer (R2: 0.003–0.90). Using OC/EC enrichment factors, the primary OC, secondary OC and EC accounted for 47.5%, 31.7% and 20.8%, respectively, of total carbon in Chinese urban environments. More than two thirds of China's urban carbon is derived from directly emitted particles. Average OC/EC ratios ranged from 2.0 to 4.7 among 14 cities during winter and from 2.1 to 5.9 during summer. OC/EC ratios in this study were consistent with a possible cooling effect of carbonaceous aerosols over China.
992 citations
TL;DR: Most of the Review is devoted to the properties of valence-tautomeric compounds, molecular magnets, and spin-crossover complexes, which could find future application in memory devices or optical switches.
Abstract: The magnetic properties of many magnetic materials can be controlled by external stimuli. The principal focus here is on the thermal, photochemical, electrochemical, and chemical control of phase transitions that involve changes in magnetization. The molecular compounds described herein range from metal complexes, through pure organic compounds to composite materials. Most of the Review is devoted to the properties of valence-tautomeric compounds, molecular magnets, and spin-crossover complexes, which could find future application in memory devices or optical switches.
942 citations
TL;DR: In this paper, the authors reviewed over 150 articles on the subject of the effect of contamination on PEM fuel cell and found that even trace amounts of impurities present in either fuel or air streams or fuel cell system components could severely poison the anode, membrane, and cathode, particularly at low-temperature operation.
932 citations
TL;DR: In this article, a humidity sensor based on a single SnO2 nanowire was fabricated, which has fast and sensitive response to relative humidity (RH) in air from a wide range of atmospheres at 30 °C.
Abstract: A humidity sensor based on a single SnO2 nanowire was fabricated. This sensor has fast and sensitive response to relative humidity (RH) in air from a wide range of atmospheres at 30 °C. The response sensitivity of the sensor to RH is linear to 90%.
793 citations
TL;DR: The proliferation of panel data studies is explained in terms of data availability, the more heightened capacity for modeling the complexity of human behavior than a single cross-section or time series data can possibly allow, and challenging methodology.
Abstract: We explain the proliferation of panel data studies in terms of (i) data availability, (ii) the more heightened capacity for modeling the complexity of human behavior than a single cross-section or time series data can possibly allow, and (iii) challenging methodology. Advantages and issues of panel data modeling are also discussed.
691 citations
TL;DR: This paper studied the dispersion in rates of provincial economic and TFP growth in China and found that human capital positively affects output per worker and productivity growth, in particular, in terms of its direct contribution to production.
Abstract: We study the dispersion in rates of provincial economic- and TFP growth in China. Our results show that regional growth patterns can be understood as a function of several interrelated factors, which include investment in physical capital, human capital, and infrastructure capital; the infusion of new technology and its regional spread; and market reforms, with a major step forward occurring following Deng Xiaoping's "South Trip" in 1992. We find that FDI had much larger effect on TFP growth before 1994 than after, and we attribute this to emergence of other channels of technology transfer when marketization accelerated. We find that human capital positively affects output per worker and productivity growth. In particular, in terms of its direct contribution to production, educated labor has a much higher marginal product. Moreover, we estimate a positive, direct effect of human capital on TFP growth. This direct effect is hypothesized to come from domestic innovation activities. The estimated spillover effect of human capital on TFP growth is positive and statistically significant, which is very robust to model specifications and estimation methods. The spillover effect appears to be much stronger before 1994. We conduct cost-benefit analysis and a policy "experiment," in which we project the impact of increases in human capital and infrastructure capital on regional inequality. We conclude that investing in human capital will be an effective policy to reduce regional gaps in China as well as an efficient means to promote economic growth.
560 citations
TL;DR: Using mathematical induction, it is proved that the IDM is unconditionally stable and convergent, but the EDM is conditionally stable and Convergent.
514 citations
TL;DR: Although all metal concentrations in sediments meets Chinese National Standard Criteria for Marine Sediment Quality, both metal enrichment factors (EF) and geoaccumulation index (I) show that Pb contamination exists in the entire study area and contamination of other metals are also present in some locations depending on the sources.
TL;DR: Recent approaches of utilizing the borrowing SERS activity strategy mainly through constructing two types of nanostructures are presented and the Raman spectra of surface water, having small Raman cross-section, on several transition metals for the first time are obtained.
TL;DR: An important role for hypoxia/HIF-1α in modulating the amyloidogenic processing of APP is demonstrated and a molecular mechanism for increased incidence of AD following cerebral ischemic and stroke injuries is provided.
TL;DR: A Fourier method is proposed for analyzing the stability and convergence of the implicit difference approximation scheme (IDAS), derive the global accuracy of the IDAS, and discuss the solvability.
TL;DR: The identification of PTPN11 as the first proto-oncogene that encodes a cytoplasmic tyrosine phosphatase with 2 Src-homology 2 (SH2) domains (Shp2)domain represents another milestone in the leukemia/cancer research field and provides a fresh view on the molecular mechanisms underlying cell transformation.
TL;DR: It is demonstrated that PRAK mediates senescence upon activation by p38 in response to oncogenic ras, and it is proposed that phosphorylation of p53 by P RAK following activation of p38 MAPK by ras plays an important role in ras-inducedsenescence and tumor suppression.
TL;DR: Not only is it shown the resistance distance can be naturally expressed in terms of the normalized Laplacian eigenvalues and eigenvectors of G, but also a new index which is closely related to the spectrum of the Normalized LaPLacian is introduced.
TL;DR: The experimental results indicated that the film thickness markedly influenced the photocatalytic activity of nanotubes array film, and the 2.5 microm-thick TiO2 nanotube array film appeared a maximum photodegradation efficiency to methyl orange.
Abstract: A highly ordered TiO2 nanotube array on Ti substrate was fabricated by using an electrochemical anodic oxidation method. The morphology, crystalline phase, and photoelectrochemical property of the nanotube array were characterized. The photocatalytic activity of the nanotube array was evaluated by the decolorization of methyl orange in aqueous solution using the different light sources. The effects of structure and morphology of the nanotube array on its photocatalytic activity were investigated. It was found that the photoabsorption behavior of the TiO2 nanotube film depended on the structures of the nanotube array. The nanotube array films exhibited a drastically enhanced photocurrent, and a higher photocatalytic activity compared with the TiO2 nanoparticle film prepared by the regular sol−gel method. The experimental results indicated that the film thickness markedly influenced the photocatalytic activity of nanotube array film, and the 2.5 μm-thick TiO2 nanotube array film appeared a maximum photodegr...
TL;DR: Findings reveal a tumor-suppressing function of the p38 pathway, and indicate that components of thep38 pathway are potential targets for novel cancer therapies.
TL;DR: In this article, a high capacity Li 2 MnSiO 4 /C nanocomposite cathode material with good rate performance for lithium ion batteries through a solution route has been successfully prepared.
12 Aug 2007
TL;DR: Promising experimental results demonstrate that the accuracy and efficiency of the IMDS system out perform popular anti-virus software such as Norton AntiVirus and McAfee VirusScan, as well as previous data mining based detection systems which employed Naive Bayes, Support Vector Machine and Decision Tree techniques.
Abstract: The proliferation of malware has presented a serious threat to the security of computer systems. Traditional signature-based anti-virus systems fail to detect polymorphic and new, previously unseen malicious executables. In this paper, resting on the analysis of Windows API execution sequences called by PE files, we develop the Intelligent Malware Detection System (IMDS) using Objective-Oriented Association (OOA) mining based classification. IMDS is an integrated system consisting of three major modules: PE parser, OOA rule generator, and rule based classifier. An OOA_Fast_FP-Growth algorithm is adapted to efficiently generate OOA rules for classification. A comprehensive experimental study on a large collection of PE files obtained from the anti-virus laboratory of King-Soft Corporation is performed to compare various malware detection approaches. Promising experimental results demonstrate that the accuracy and efficiency of our IMDS system out perform popular anti-virus software such as Norton AntiVirus and McAfee VirusScan, as well as previous data mining based detection systems which employed Naive Bayes, Support Vector Machine (SVM) and Decision Tree techniques.
TL;DR: It is suggested that RNAi is capable of silencing sequence-specific genes of WSSV and might constitute a new therapeutic strategy for W SSV infection in shrimp.
TL;DR: In this paper, the authors describe a Vielzahl magnetischer materialien, deren magnetische Eigenschaften durch externe Stimuli geschaltet werden konnen.
Abstract: Man kennt eine Vielzahl magnetischer Materialien, deren magnetische Eigenschaften durch externe Stimuli geschaltet werden konnen. Das Hauptaugenmerk liegt auf der thermischen, photochemischen, elektrochemischen und chemischen Steuerung von Phasenubergangen, die mit einem Wechsel der Magnetisierung einhergehen. Die Bandbreite der beschriebenen Spezies reicht von Metallkomplexen uber rein organische Verbindungen bis zu Kompositmaterialien, wobei der Schwerpunkt dieses Aufsatzes auf den Eigenschaften von valenztautomeren Verbindungen, molekularen Magneten und Spin-Crossover-Komplexen liegt, fur die Anwendungen als Speichermedien oder optische Schalter in Aussicht stehen.
TL;DR: A general protocol for the making of surface-imprinted core-shell nanoparticles via surface reversible addition-fragmentation chain- transfer (RAFT) polymerization using RAFT agent functionalized model silica nanoparticles as the chain-transfer agent was presented.
Abstract: In this paper, we present a general protocol for the making of surface-imprinted core−shell nanoparticles via surface reversible addition−fragmentation chain-transfer (RAFT) polymerization using RAFT agent functionalized model silica nanoparticles as the chain-transfer agent. In this protocol, trichloro(4-chloromethylphenyl)silane was immobilized on the surface of SiO2 nanoparticles, forming chloromethylphenyl functionalized silica (silica-Cl). RAFT agent functionalized silica was subsequently produced by substitute reaction of silica-Cl with PhC(S)SMgBr. The grafting copolymerization of 4-vinylpyridine and ethylene glycol dimethacrylate using surface RAFT polymerization and in the presence of 2,4-dichlorophenoxyacetic acid as the template led to the formation of surface-imprinted core−shell nanoparticles. The resulting surface-imprinted core−shell nanoparticles bind the original template 2,4-D with an appreciable selectivity over structurally related compounds. The potential use of the surface-imprinted ...
TL;DR: The results of magnetic characterization showed that the magnetic properties of the hexagonal close-packed (hcp) and face-centered cubic (fcc) nickel nanoparticles are quite different from those of the fcc and hcp, respectively.
Abstract: Nickel nanoparticles were prepared from the thermal decomposition of nickel(II) acetylacetonate in alkylamines and characterized by powder x-ray diffraction, transmission electron microscopy and magnetic measurement. The reaction temperature, heating rate and solvent type play an important role in the control over the crystalline phase. Depending on the reaction conditions, face-centered cubic (fcc) or hexagonal close-packed (hcp) nickel nanoparticles can be obtained. Monodisperse nickel nanoparticles were also obtained by introducing surfactants. The results of magnetic characterization showed that the magnetic properties of the hcp nickel nanoparticles are quite different from those of the fcc nickel nanoparticles.
TL;DR: In this paper, the authors use numerical simulation methods to analyze the Hukou system of permanent registration in China which many believe has supported growing relative inequality over the last 20 years by restraining labour migration both between the countryside and urban areas and between regions and cities.
TL;DR: In this paper, a nonparametric kernel-based model specification test is proposed for regression models with both discrete and continuous regressors, and the test statistic is shown to have an asymptotic normal null distribution.
TL;DR: In this paper, the root exudates of Kandelia candel (L.) Druce seedlings were examined for 6 months under growth in an air-conditioned greenhouse with natural illumination and the relative humidity of 85%, the temperature ranging from 26 to 32°C, in increasing Cd concentration stress conditions (0, 5, 10, 20, 30, 40 and 50 ǫppm).
TL;DR: Nice ferromagnetic interactions between the Ni(II) ions upon lowering the temperature from 300 to 2 K were revealed and the cage-like arrangement of the two distinct sets of metal ions manifests the beauty of symmetry.
Abstract: A structurally fascinating Keplerate magnetic cluster featuring an icosidodecahedron of Ni(II) ions encapsulating a dodecahedron of La(III) ions was assembled under hydrothermal conditions starting with La(NO3)3, Ni(NO3)2, and iminodiacetic acid. The cage-like arrangement of the two distinct sets of metal ions manifests the beauty of symmetry as both ideally possess icosahedral (Ih) symmetry, the highest possible symmetry for molecules. The cluster constitutes a framework of Ni(II) centers with an unusual spin topology. Interesting ferromagnetic interactions between the Ni(II) ions upon lowering the temperature from 300 to 2 K were revealed.
TL;DR: The photoresponsive behaviors of these valence tautomeric compounds are similar to those of spin-crossover complexes (light-induced excited spin-state trapping effects) and can be regarded as novel photomagnetic materials.
Abstract: A number of photofunctional molecular compounds have been developed recently. Typical examples of these are phototunable valence tautomeric compounds, which are now attracting great attention. When the charge-transfer bands of some Co valence tautomeric compounds are excited at low temperature, metastable redox isomers can be created after irradiation. The lifetimes of the metastable states can be more than several hours. These transformations can involve changes in the magnetic properties of the compounds, as well as their color. Hence, these compounds can be regarded as novel photomagnetic materials. The photoresponsive behaviors of these valence tautomeric compounds are similar to those of spin-crossover complexes (light-induced excited spin-state trapping effects).