Showing papers by "Xiamen University published in 2010"
TL;DR: Shell-isolated nanoparticle-enhanced Raman spectroscopy is reported, in which the Raman signal amplification is provided by gold nanoparticles with an ultrathin silica or alumina shell, which significantly expands the flexibility of SERS for useful applications in the materials and life sciences, as well as for the inspection of food safety, drugs, explosives and environment pollutants.
Abstract: Surface-enhanced Raman scattering (SERS) is a powerful spectroscopy technique that can provide non-destructive and ultra-sensitive characterization down to single molecular level, comparable to single-molecule fluorescence spectroscopy. However, generally substrates based on metals such as Ag, Au and Cu, either with roughened surfaces or in the form of nanoparticles, are required to realise a substantial SERS effect, and this has severely limited the breadth of practical applications of SERS. A number of approaches have extended the technique to non-traditional substrates, most notably tip-enhanced Raman spectroscopy (TERS) where the probed substance (molecule or material surface) can be on a generic substrate and where a nanoscale gold tip above the substrate acts as the Raman signal amplifier. The drawback is that the total Raman scattering signal from the tip area is rather weak, thus limiting TERS studies to molecules with large Raman cross-sections. Here, we report an approach, which we name shell-isolated nanoparticle-enhanced Raman spectroscopy, in which the Raman signal amplification is provided by gold nanoparticles with an ultrathin silica or alumina shell. A monolayer of such nanoparticles is spread as 'smart dust' over the surface that is to be probed. The ultrathin coating keeps the nanoparticles from agglomerating, separates them from direct contact with the probed material and allows the nanoparticles to conform to different contours of substrates. High-quality Raman spectra were obtained on various molecules adsorbed at Pt and Au single-crystal surfaces and from Si surfaces with hydrogen monolayers. These measurements and our studies on yeast cells and citrus fruits with pesticide residues illustrate that our method significantly expands the flexibility of SERS for useful applications in the materials and life sciences, as well as for the inspection of food safety, drugs, explosives and environment pollutants.
2,934 citations
Xiamen University1, University of Vienna2, University of Miami3, University of South Carolina4, Alfred Wegener Institute for Polar and Marine Research5, University of Tennessee6, University of Delaware7, Centre national de la recherche scientifique8, University of Maryland Center for Environmental Science9, University of California, San Diego10
TL;DR: The microbial carbon pump is proposed as a conceptual framework to address the important, multifaceted biogeochemical problem of fixed carbon in the upper ocean.
Abstract: The biological pump is a process whereby CO(2) in the upper ocean is fixed by primary producers and transported to the deep ocean as sinking biogenic particles or as dissolved organic matter. The fate of most of this exported material is remineralization to CO(2), which accumulates in deep waters until it is eventually ventilated again at the sea surface. However, a proportion of the fixed carbon is not mineralized but is instead stored for millennia as recalcitrant dissolved organic matter. The processes and mechanisms involved in the generation of this large carbon reservoir are poorly understood. Here, we propose the microbial carbon pump as a conceptual framework to address this important, multifaceted biogeochemical problem.
1,194 citations
TL;DR: It is demonstrated in this paper that a laser with a power level considered to be low in the traditional SERS measurement can already lead to a significant surface reaction.
Abstract: Surface-enhanced Raman spectroscopy (SERS) has long been considered as a noninvasive technique that can obtain the fingerprint vibrational information of surface species. We demonstrated in this paper that a laser with a power level considered to be low in the traditional SERS measurement can already lead to a significant surface reaction. para-Aminothiophenol, an important probe molecule in SERS, was found to be oxidized to form 4,4'-dimercaptoazobenzene (DMAB) on a roughened silver surface during the SERS measurement. The assumption was confirmed experimentally by surface mass spectroscopy and SERS as well as electrochemistry of the synthesized DMAB, which agrees well with theoretical calculations. A defocusing method was used to avoid the laser induced surface reaction and perform reliable SERS characterization and identification, which can effectively avoid erroneous interpretation of the distorted experimental result.
670 citations
TL;DR: In this article, the authors proposed a method to use the key scientific project of Fujian Province to improve the performance of the Key Scientific Project (KSP) of the National Natural Science Foundation of China (NNSF).
Abstract: National Natural Science Foundation of China [20625310, 20923004]; National Basic Research Program of China [2005CB221408, 2010CB732303]; Research Fund for the Doctoral Program of Higher Education [20090121110007]; Key Scientific Project of Fujian Province [2009HZ0002-1]
664 citations
TL;DR: HEV 239 is well tolerated and effective in the prevention of hepatitis E in the general population in China, including both men and women age 16-65 years and no vaccination-related serious adverse event was noted.
620 citations
TL;DR: This critical review highlights recent advances in the structurally modified (thio)urea-based receptors for anion complexation and sensing.
Abstract: This critical review highlights recent advances in the structurally modified (thio)urea-based receptors for anion complexation and sensing. Modifications of the (thio)urea structure are aimed at a better anion binding in terms of higher binding constant, anion selectivity and feasibility. Major (thio)urea receptors are reviewed as N-alkyl, N-aryl and N-amido/N-amino (thio)ureas. Hints for designing (thio)urea-based receptors for anions are discussed (102 references).
519 citations
TL;DR: Results clearly indicate that CTAC worked much better than CTAB as a capping agent in both the syntheses of Au seeds and Au@Ag core-shell nanocubes, which could be converted into Au-based hollow nanostructures containing the original Au seeds in the interiors through a galvanic replacement reaction.
Abstract: NSF [DMR 0804088, ECS 0335765]; NIH [1R01 CA138527]; Ministry of Education Science and Technology [R32 20031]; China Scholarship Council
490 citations
TL;DR: A compact Q-switched dual-wavelength erbium-doped fiber (EDF) laser based on graphene as a saturable absorber (SA) is demonstrated using a two-reflection peak fiber Bragg grating as the external cavity mirror.
Abstract: We demonstrate a compact Q-switched dual-wavelength erbium-doped fiber (EDF) laser based on graphene as a saturable absorber (SA). By optically driven deposition of graphene on a fiber core, the SA is constructed and inserted into a diode-pumped EDF laser cavity. Also benefiting from the strong third-order optical nonlinearity of graphene to suppress the mode competition of EDF, a stable dual-wavelength Q-switching operation has been achieved using a two-reflection peak fiber Bragg grating as the external cavity mirror. The Q-switched EDF laser has a low pump threshold of 6.5mW at 974nm and a wide range of pulse-repetition rate from 3.3 to 65.9kHz. The pulse duration and the pulse energy have been characterized. This is, to the best of our knowledge, the first demonstration of a graphene-based Q-switched laser.
449 citations
TL;DR: Tetrahexahedral Pd nanocrystals with {730} high-index facets were directly produced on a glassy carbon substrate in a dilute PdCl(2) solution by a newly developed programmed electrodeposition method.
Abstract: Tetrahexahedral Pd nanocrystals (THH Pd NCs) with {730} high-index facets were directly produced on a glassy carbon substrate in a dilute PdCl(2) solution by a newly developed programmed electrodeposition method. The THH Pd NCs, thanks to their high density of surface atomic steps, exhibit 4-6 times higher catalytic activity than commercial Pd black catalyst toward ethanol electrooxidation in alkaline solutions. This straightforward method provides a promising route to facile preparation of high-index-faceted metal nanocatalysts with high catalytic activity.
442 citations
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TL;DR: Li et al. as discussed by the authors examined the effects of audit quality on earnings management and cost of equity capital for two groups of Chinese firms: state-owned enterprises (SOEs) and non-state-owned entities (NSOEs).
Abstract: We examine the effects of audit quality on earnings management and cost of equity capital for two groups of Chinese firms: state-owned enterprises (SOEs) and non-state-owned enterprises (NSOEs). The differences in the nature of the ownership, agency relations and bankruptcy risks lead SOEs to have weaker incentives than NSOEs to engage in earnings management. As a result, the effect of audit quality in reducing earnings management will be greater for NSOEs than for SOEs. In addition, investors’ pricing of information risk as reflected in the cost of equity capital will be more pronounced for NSOEs than for SOEs with high and low audit quality. We find empirical evidence consistent with these hypotheses. Our findings indicate that (1) while high-quality auditors play a governance role in China, that role is limited to a subset of firms, and (2) even under the same legal jurisdiction, the effects of audit quality (in the form of lower earnings management and cost of equity capital) vary across firms with different ownership structures. Our study extends prior research by focusing on the economic consequences of SOEs’ and NSOEs’ auditor choices and underscores the importance of controlling for ownership type when conducting audit research.
425 citations
TL;DR: Wang et al. as discussed by the authors built upon the tourism and marketing literature, a conceptual model depicting the relationship among tourism destination image components, satisfaction, and behavioral intentions was proposed, empirically tested using survey data from 550 Chinese tourists who visited Zhang-Jia-Jie, a major Chinese tourism destination shown on the list of the World Natural Heritage.
Abstract: Built upon the tourism and marketing literature, a conceptual model depicting the relationship among tourism destination image components, satisfaction, and behavioral intentions was proposed. A conceptual model consisting of six hypotheses was empirically tested using survey data from 550 Chinese tourists who visited Zhang-Jia-Jie, a major Chinese tourism destination shown on the list of the World Natural Heritage. The empirical findings reveal that: (a) overall tourism destination is reflected by both cognitive image and affective image, and (b) overall tourism destination image has an indirect impact on behavioral intentions through satisfaction. Theoretical and managerial implications are discussed before the article concludes with limitations and directions for future research.
TL;DR: The results demonstrate that the fraction of the surface that is electrochemically active for Li(+) transportation is a key criterion for evaluating the different nanostructures of potential LIB materials.
Abstract: Major State Basic Research Development Program of China [2009CB220102]; National Science Foundation of China [20833005, 20773102, 20931160426]
TL;DR: In this article, the authors proposed a method to detect the presence of asteroids in the Earth's magnetic field by using a satellite data set from the National Natural Science Foundation of China (NNSCF).
Abstract: US NASA [NNX09AE17G, NNX09AV56G]; NOAA [NA06NES4400004]; National Natural Science Foundation of China [40871168]; Ministry of Education of China [B07034]
TL;DR: The ability of Tat to enable two different classes of elongation factors to cooperate and coordinate their actions on the same polymerase enzyme explains why Tat is such a powerful activator of HIV-1 transcription.
TL;DR: This work aims to demonstrate the efforts towards in-situ applicability of EMMARM, which aims to provide real-time information about the physical properties of EMTs through direct observation and computer simulation.
Abstract: US NIH ; China National Scientific Foundation of China [20805038, 20620130427]; National Basic Research Program of China [2007CB935603, 2010CB732402, 2009ZX10004-312]; ACS Division of Analytical Chemistry
TL;DR: In this article, polyvinyl alcohol (PVA) was used as a hydrogen bond functionalizing agent to modify multi-walled carbon nanotubes (CNTs), and nanoparticles of Fe3O4 were formed along the sidewalls of the as-modified CNTs by the chemical coprecipitation of Fe2+ and Fe3+ in the presence of CNT in an alkaline solution.
TL;DR: It is proved that functionalized nanoscale graphene oxide can protect oligon nucleotides from enzymatic cleavage and efficiently deliver oligonucleotides into cells.
TL;DR: If neuropilin-2 and the growth factor VEGF-C do not come together, lymphatic vessels don’t branch apart and the immune system shuts down.
Abstract: Vascular sprouting is a key process-driving development of the vascular system. In this study, we show that neuropilin-2 (Nrp2), a transmembrane receptor for the lymphangiogenic vascular endothelial growth factor C (VEGF-C), plays an important role in lymphatic vessel sprouting. Blocking VEGF-C binding to Nrp2 using antibodies specifically inhibits sprouting of developing lymphatic endothelial tip cells in vivo. In vitro analyses show that Nrp2 modulates lymphatic endothelial tip cell extension and prevents tip cell stalling and retraction during vascular sprout formation. Genetic deletion of Nrp2 reproduces the sprouting defects seen after antibody treatment. To investigate whether this defect depends on Nrp2 interaction with VEGF receptor 2 (VEGFR2) and/or 3, we intercrossed heterozygous mice lacking one allele of these receptors. Double-heterozygous nrp2vegfr2 mice develop normally without detectable lymphatic sprouting defects. In contrast, double-heterozygote nrp2vegfr3 mice show a reduction of lymphatic vessel sprouting and decreased lymph vessel branching in adult organs. Thus, interaction between Nrp2 and VEGFR3 mediates proper lymphatic vessel sprouting in response to VEGF-C.
TL;DR: One-pot biogenic fabrication of palladium nanoparticles by a simple procedure using broth of Cinnamomum camphora leaf without extra surfactant, capping agent, and/or template was reported in this article.
Abstract: The development of dependable, environmentally benign processes for the synthesis of nanoscale materials is an important aspect of nanotechnology. In the present study, we report one-pot biogenic fabrication of palladium nanoparticles by a simple procedure using broth of Cinnamomum camphora leaf without extra surfactant, capping agent, and/or template. The mean size of palladium nanoparticles, ranging from 3.2 to 6.0 nm, could be facilely controlled by merely varying the initial concentration of the palladium ions. The polyols components and the heterocyclic components were believed to be responsible for the reduction of palladium ions and the stabilization of palladium nanoparticles, respectively.
TL;DR: This research paper aims to demonstrate the efforts towards in-situ applicability of EMMARM, as to provide real-time information about concrete mechanical properties such as E-modulus and compressive strength.
Abstract: NSFC [20873113, 20833005, 20933004]; MOST [2007DFA40890]; Research Fund [200803841035]; Fujian Provincial Department of Science and Technology [2008F3099, 200810025]
TL;DR: In this article, the authors analyzed the embodied CO 2 emissions of China's import and export and showed that about 3357 million tons of CO2 emissions were embodied in the exports and the emissions avoided by imports were 2333 million tons in 2005.
TL;DR: A correlation coefficient (CC) and standard deviation (SD) integrated approach for determining the weights of attributes in multiple attribute decision making (MADM) and a global sensitivity analysis to the weights determined are proposed to ensure the stability of the best decision alternative or alternative ranking.
TL;DR: Wang et al. as mentioned in this paper investigated the role of the National Social Science Funds (NSF) and the Ministry of Education of the People's Republic of China (MEC).
TL;DR: The first observation of luminescence from a structurally well-defined Ag(2)S molecular nanocluster is reported, which displays intense red emission in both the solid state and solution at room temperature.
Abstract: The first observation of luminescence from a structurally well-defined Ag(2)S molecular nanocluster is reported. Reaction of AgSBu(t)/AgBF(4) with N(2)H(4) in methanol affords the tetracationic cluster [Ag(62)S(13)(SBu(t))(32)](BF(4))(4), which has a core-shell configuration. The 14 silver(I) centers of the [Ag(14)S(13)] core are in a face-centered cubic arrangement with each edge bridged by a S(2-) ligand; the core is further connected to the [Ag(48)(SBu(t))(32)] shell via both Ag-S bonds and Ag···Ag interactions. This novel cluster displays intense red emission in both the solid state and solution at room temperature.
TL;DR: The Nature Science Foundation of China [20976145] as discussed by the authors, Nature Science foundation of Fujian Province, China [2009J01040], [2005038401].
TL;DR: This review summarizes recent studies on the crosstalk between Wnt and EGFR signaling in cancers and points out several possible convergence points.
Abstract: Wnt and EGFR signaling play key roles in embryonic development and cell proliferation. It is well documented that dysregulation of these two pathways often leads to tumorigenesis with poor prognosis. However, the possible crosstalk between the two pathways in cancer development is largely unknown. Although some reports show that EGFR might antagonize Wnt signaling during development in Drosophila, an increasing body of evidence indicates that Wnt and EGFR signaling crosstalk and transactivate one another in development and cancer. This review summarizes recent studies on the crosstalk between Wnt and EGFR signaling in cancers and points out several possible convergence points. Wnt ligands can activate EGFR signaling through their 7-transmembrane domain receptor Frizzled while EGFR can activate β-catenin via receptor tyrosine kinase-PI3K/Akt pathway; EGFR has been shown to form a complex with β-catenin and increase the invasion and metastasis of cancer cells. NKD2, a Wnt antagonist by interacting with Dishevelled, also escorts TGFα-containing exocytic vesicles to the basolateral membrane of polarized epithelial cells. Down-regulation of NKD2 causes Wnt activation and TGFα misdelivery, suggesting its functions in cell homeostasis and prevention of tumorigenesis.
TL;DR: In this article, a review of the current status of this particular area of research in supramolecular chemistry and materials is assessed and personal perspectives as to toward what direction should this chemistry head are elaborated.
Abstract: Crystal engineering is the rational design and assembly of solid-state structures with desired properties via the manipulation of intermolecular interactions, hydrogen bonding and metal–ligand complexation in particular. The heart of crystal engineering is to control the ordering of the building blocks, be they molecular or ionic, toward a specific disposition in the solid state. The relatively weak strength of intermolecular forces with respect to chemical bonding renders the assembly of supramolecular constructs sensitive to external physical and chemical stimuli, with pH condition of the reaction mixture being arguably the most prominent and extensively observed. Using selected examples of constructing metal–organic architectures from recent literature, the influences of pH on the specific ligand forms, the generation and metal coordination of hydroxo ligands, ligand transformation promoted by pH condition changes, pH-dependent kinetics of crystallization of a number of metal–organic architectures are discussed. Current status of this particular areas of research in supramolecular chemistry and materials are assessed and personal perspectives as to toward what directions should this chemistry head are elaborated.
TL;DR: Evaluating effects of CO2-induced ocean acidification on the marine diatom Phaeodactylum tricornutum found the balance between these positive and negative effects on diatom productivity will be a key factor in determining the net effect of rising atmospheric CO2 on ocean primary production.
Abstract: . CO2/pH perturbation experiments were carried out under two different pCO2 levels (39.3 and 101.3 Pa) to evaluate effects of CO2-induced ocean acidification on the marine diatom Phaeodactylum tricornutum. After acclimation (>20 generations) to ambient and elevated CO2 conditions (with corresponding pH values of 8.15 and 7.80, respectively), growth and photosynthetic carbon fixation rates of high CO2 grown cells were enhanced by 5% and 12%, respectively, and dark respiration stimulated by 34% compared to cells grown at ambient CO2. The half saturation constant (Km) for carbon fixation (dissolved inorganic carbon, DIC) increased by 20% under the low pH and high CO2 condition, reflecting a decreased affinity for HCO3– or/and CO2 and down-regulated carbon concentrating mechanism (CCM). In the high CO2 grown cells, the electron transport rate from photosystem II (PSII) was photoinhibited to a greater extent at high levels of photosynthetically active radiation, while non-photochemical quenching was reduced compared to low CO2 grown cells. This was probably due to the down-regulation of CCM, which serves as a sink for excessive energy. The balance between these positive and negative effects on diatom productivity will be a key factor in determining the net effect of rising atmospheric CO2 on ocean primary production.
TL;DR: This Account surveys the great variety of fullerene-like metal-containing clusters with an emphasis on their synthetic and structural chemistry, and hopes that further study of the bonding interactions and properties of these molecules will lead to the development of new functional materials.
Abstract: The discovery of fullerenes in 1985 opened a new chapter in the chemistry of highly symmetric molecules. Fullerene-like metal clusters, characterized by (multi)shell-like structures, are one rapidly developing class of molecules that share this shape. In addition to creating aesthetically pleasing molecular structures, the ordered arrangement of metal atoms within such frameworks provides the opportunity to develop materials with properties not readily achieved in corresponding mononuclear or lower-nuclearity complexes. In this Account, we survey the great variety of fullerene-like metal-containing clusters with an emphasis on their synthetic and structural chemistry, a first step in the discussion of this fascinating field of cluster chemistry. We group the compounds of interest into three categories based on the atomic composition of the cluster core: those with formal metal−metal bonding, those characterized by ligand participation, and those supported by polyoxometalate building blocks. The number of ...
TL;DR: The N-doped TiO(2) nanotubes exhibited higher photocatalytic activity in degradating methyl orange into non-toxic inorganic products under both UV and simulated sunlight irradiation.