S. S. Xie

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (95)395.31 Total impact

  • X X Zhang · D Zhao · M Gao · H B Dong · W Y Zhou · S S Xie
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    ABSTRACT: Multi-stage growth of ZnO nanorod arrays has been carried out by Au-assisted chemical vapor deposition (CVD) in order to better understand and more precisely control the growth behaviors. It is evidenced that Au-catalyzed vapor-liquid-solid (VLS) growth only dominates the initial site-specific nucleation of the nanorods, while the subsequent growth is governed by a vapor-solid (VS) epitaxy mechanism. The sequential VLS and VS behaviors permit the fabrication of large-scale highly ordered arrays of ZnO nanorods with precisely tunable diameters and embedded junctions by controlling reactant concentration and nanorod top morphology. Based on the above results, two routes to fabricate ultrafine ZnO nanorod arrays are proposed and stepwise nanorod arrays with ultrafine top segment (~10 nm in diameter) have been achieved. Temperature-dependent photoluminescence (PL) and spatial resolved PL were carried out on the nanorod arrays and on individual nanorods, indicating high quality optical properties and tunable light emission along the length of the stepwise nanorods.
    Nanotechnology 04/2011; 22(13):135603. DOI:10.1088/0957-4484/22/13/135603 · 3.67 Impact Factor
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    L D Yao · S D Luo · X Shen · S J You · L X Yang · S J Zhang · S Jiang · Y C Li · J Liu · K Zhu · Y L Liu · W Y Zhou · L C Chen · C Q Jin · R C Yu · S S Xie
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    ABSTRACT: High-pressure in situ angular dispersive x-ray diffraction study on the wurtzite-type InN nanowires has been carried out by means of the image-plate technique and diamond-anvil cell (DAC) up to about 31.8 GPa. The pressure-induced structural transition from the wurtzite to a rocksalt-type phase occurs at about 14.6 GPa, which is slightly higher than the transition pressure of InN bulk materials ($12.1 GPa). The relative volume reduction at the transition point is close to 17.88%, and the bulk modulus B 0 is determined through fitting the relative volume-pressure experimental data related to the wurtzite and rocksalt phases to the Birch–Murnaghan equation of states. Moreover, high-pressure Raman scattering for InN nanowires were also investigated in DAC at room temperature. The corresponding structural transition was confirmed by assignment of phonon modes. We calculated the mode Grüneisen parameters for the wurtzite and rocksalt phases of InN nanowires.
    Journal of Materials Research 01/2010; 25(12). DOI:10.1557/jmr.2010.0290 · 1.82 Impact Factor
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    ABSTRACT: In situ high-pressure angle dispersive x-ray diffraction experiments using synchrotron radiation on inverse spinel structure Zn <sub>2</sub> SnO <sub>4</sub> nanowires were carried out with a diamond anvil cell at room temperature. The crystal symmetry becomes lower at around 12.9 GPa and an intermediate phase with an orthorhombic structure occurs. At about 32.7 GPa, a phase transition occurs accompanying a high-pressure phase. In situ Raman scattering investigation was also performed to explore the phase transition. In the pressure range 15.5–32.8 GPa, the intermediate phase is also detected and a high-pressure phase is observed above 32.8 GPa. The high-pressure phase is considered to possess the ambient pressure structure of CaFe <sub>2</sub> O <sub>4</sub> .
    Journal of Applied Physics 01/2010; 106(11-106):113523 - 113523-5. DOI:10.1063/1.3268460 · 2.19 Impact Factor
  • S. S. Xie · W. J. Ma · W. Y. Zhou
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    ABSTRACT: Macroscale carbon nanotube (CNT) architectures such as films and fibers have superior properties and promising application prospects. We synthesize large-area transparent, highly conductive and strong single-walled carbon nanotube(SWNT) films through floating catalyst CVD method, and perform series researches to their physical properties. The correlation between the properties of films and fibers with that of individual carbon nanotubes is also explored. Based on the synthesized SWNT films, macroscale SWNT fibers are fabricated through a twisting process. We record the Raman spectra when the films and fibers are strained, and analyze the micromechanical process based on the change of G' Raman mode, propose the concept of strain transfer factor and its influence on the mechanical performance of macroscale SWNT architectures. By infiltrating polymer molecules into the interspace of the continuous carbon nanotube network, we fabricate novel high-strength composite fibers. Their mechanical properties are tested and correlated with the micromechanical process. We compare the microscale load-transfer manner of such continuous CNT network based composite with that of discrete CNT reinforced composites, and point out the invalidity of rule of mixture coming from traditional composite theory when it is used to predict the mechanical properties of CNT reinforced composites.
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    J Meng · M Yang · L Song · H Kong · C Y Wang · R Wang · S S Xie · H Y Xu
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    ABSTRACT: This work investigated the biological influence of water-soluble multiwalled carbon nanotubes (wsMWCNTs) on fibroblast cell growth as a function of concentration control in an aqueous solution. The wsMWCNTs were prepared by an optimal procedure of ultrasonication/concentrated acids oxidation. The concentration of wsMWCNT in the solution was quantified by an established calibration line. A stable concentration of 0.3mg/ml was obtained in the surfactant-free water. The physicochemical properties of wsMWCNTs were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV/VIS/NIR spectroscopy, and dynamic light scattering (DLS). Cell proliferation and the cell cycle were examined by MTS assay, flow cytometry and TEM respectively. Experimental results showed that the oxidation degree was a key factor that determined the concentration and stability of wsMWCNTs in the aqueous solution. The wsMWCNTs were able to enter into the cells and mainly accumulated in the cytoplasm. The wsMWCNTs-induced variations in cell proliferation and the cell cycle were concentration dependent. Cells cultivated with wsMWCNTs of 0.3mg/ml underwent a dramatic apoptosis. The proliferation was clearly suppressed when the cells were cultivated with wsMWCNTs of 0.03 mg/ml. There were no obvious influences on cell proliferation and the cell cycle when the concentration of wsMWNTs decreased to 0.01 mg/ml.
    Colloids and surfaces B: Biointerfaces 03/2009; 71(1):148-53. DOI:10.1016/j.colsurfb.2009.01.020 · 4.15 Impact Factor
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    ABSTRACT: We demonstrate a promising route to fabricate large scale hexagonally patterned, vertically aligned ZnOnanorod arrays with small diameter. By adding 3-mercaptopropyltriethoxysilane (MPTES) molecules as a connection between catalyst and substrate the large size dispersion resulting from the removal of catalyst pattern is avoided, thus the catalyst particle pattern with tiny size dispersion and regular shape is obtained; the size can be tuned in a large range from 50 nm to 300 nm. Using this technique, ZnOnanorod arrays with tunable spacings and diameters are achieved, which also have uniform shape and length, good crystal quality, and vertical alignment on the substrate. Moreover, a pronounced blue-shift of ultraviolet (UV) luminescence spectra of ZnOnanorods with their diameters decreasing is observed. Combining the temperature-dependent photoluminescence (PL), we suggest that a materially decreased exciton-phonon interaction with the reduced diameter of ZnOnanorods is the main reason for the blue-shift of UV luminescence.
    Journal of Materials Chemistry 01/2009; 19(7-7):962-969. DOI:10.1039/b815518f · 7.44 Impact Factor
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    ABSTRACT: In this letter, individual ZnO tetrapod was designed as a multiterminal sensor. The gas-sensing properties of water and oxygen of the device have been investigated. We found that if water was preadsorbed on the device, the sensitivity of oxygen can be effectively enhanced; meanwhile, the response time can also be remarkably shortened. The mechanism of these phenomena, we propose, is the adsorption competition of the two kinds of molecules. Our results show that the preadsorption of appropriate gas can enhance the performance of the sensors, which is helpful for sensor designing.
    Applied Physics Letters 05/2008; 92(21). DOI:10.1063/1.2938047 · 3.52 Impact Factor
  • X. Wu · P. Jiang · W. Cai · X.-D. Bai · P. Gao · S.-S. Xie
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    ABSTRACT: A kind of novel urchin-like hierarchical ZnO micro-/nano-structure film has been constructed on the Zn foil substrate by a simple one-step vacuum thermal evaporation process using a mixture of ZnS and graphite powder as a source. Individual ZnO micro-/nano-structures and bamboo-like branches have been characterized using field emission scanning electron microscope (FE-SEM) and high resolution transmission electron microscope (HRTEM). The results showed that different urchin-like ZnO structures probably originates from various microsphere precursors. Reasonable formation mechanism of the hierarchical ZnO micro- or nano-structures have been proposed on the base of the obtained information. The study also explored the properties of the ZnO micro-/nano-structure film performing wettability and Raman and room-temperature photoluminescence. The realization of the hierarchical structures can encourage potential opportunities for high technological applications.
    Advanced Engineering Materials 04/2008; 10(5):476 - 481. DOI:10.1002/adem.200700320 · 1.51 Impact Factor
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    Li Song · W J Ma · Yan Ren · W Y Zhou · S S Xie · P H Tan · L F Sun
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    ABSTRACT: The temperature-dependent Raman frequency shift in single-walled carbon nanotube (SWCNT) rings in the range of 80-550 K is investigated. We observe that the frequency decreases with increasing temperature for all Raman peaks of the nanotube rings. Furthermore, compared to the nanotubes with linear structure, the temperature coefficients of the radial breathing mode and G-mode frequencies of the nanotube rings are much smaller, which means the nanotube rings have more stable thermal ability. We attribute the better thermal stability to the high bending strain energy along the nanotube rings induced by the sidewall curvature.
    Applied Physics Letters 03/2008; 92(12-12):121905. DOI:10.1063/1.2891870 · 3.52 Impact Factor
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    ABSTRACT: PbTiO3 nanotube arrays have been synthesized via sol–gel template method, and their morphology and structures have been determined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The diameter and length of these nanotubes are about 300nm and 50μm, respectively, and their wall thickness is typically several tens of nanometers. XRD data shows that as-prepared PTO nanotubes possess perovskite structure, and electron diffraction demonstrates that they are polycrystalline. Photoluminescence spectrum of PTO nanotubes reveals an intense and wide emission band centered at 505nm. Polarization–electric field (P–E) response curves of PTO nanotube array were measured, and the hysteresis loops illustrate a room temperature ferroelectric characteristic of as-prepared PTO nanotubes.
    Materials Science and Engineering B 03/2008; 149(1-1):41-46. DOI:10.1016/j.mseb.2007.12.003 · 2.12 Impact Factor
  • D F Liu · Y J Xiang · Q Liao · J P Zhang · X C Wu · Z X Zhang · L F Liu · W J Ma · J Shen · W Y Zhou · S S Xie
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    ABSTRACT: ZnO nanorod arrays with perfect order and uniformity were prepared using a simple, low-cost, commonly available and scalable nanosphere lithography for patterning gold catalyst particles and a successive bottom-up growth technique in a tube furnace chemical vapor deposition system. Each rod in the arrays had perfect surface facets, sharp edges and uniform size. For all of the rods, their sides were oriented the same. This bottom-up assembly method may accelerate the use of ZnO nanorods in real device applications.
    Nanotechnology 09/2007; 18(40):405303. DOI:10.1088/0957-4484/18/40/405303 · 3.67 Impact Factor
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    ABSTRACT: Small zinc oxide tripodlike arms were assembled at the end of nanowires through thermal evaporation of zinc powder in a horizontal tube furnace. These arms are hundreds of nanometers in length, and they are tens of nanometers in diameter, similar to that of the based nanowires. High-resolution transmission electron microscopy investigation exhibits that they are wurtzite structure and have clear twin planes at the junction of the arms and the based nanowires. The growth mechanism, Raman, and photoluminescence properties were discussed.
    Applied Physics Letters 07/2007; 91(1-1):013106. DOI:10.1063/1.2752605 · 3.52 Impact Factor
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    ABSTRACT: ZnO−SnO2 binary nanostructure was synthesized by a simple vapor-phase transport method. Pyramid-like single-crystalline SnO2 nanoparticles were found grown on the surface of the ZnO nanobelts with definite orientations, aligning into a line along two preferential directions [011̄0] and [011̄1]. The ZnO−SnO2 binary nanostructures were studied and their growth mechanism was discussed. The ZnO−SnO2 binary nanostructures were used to fabricate CO gas sensor with sensitive response. The photoluminescence of the binary oxide nanostructure was also measured.
    The Journal of Physical Chemistry C 05/2007; 111(21). DOI:10.1021/jp070963l · 4.77 Impact Factor
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    ABSTRACT: The size- and morphology-controlled growth of ZnO nanowire (NW) arrays is potentially of interest for the design of advanced catalysts and nanodevices. By adjusting the reaction temperature, shelled structures of ZnO made of bunched ZnO NW arrays are prepared, grown out of metallic Zn microspheres through a wet-chemical route in a closed Teflon reactor. In this process, ZnO NWs are nucleated and subsequently grown into NWs on the surfaces of the microspheres as well as in strong alkali solution under the condition of the pre-existence of zincate (ZnO22-) ions. At a higher temperature (200 degrees C), three different types of bunched ZnO NW or sub-micrometer rodlike (SMR) aggregates are observed. At room temperature, however, the bunched ZnO NW arrays are found only to occur on the Zn microsphere surface, while double-pyramid-shaped or rhombus-shaped ZnO particles are formed in solution. The ZnO NWs exhibit an ultrathin structure with a length of ca. 500 nm and a diameter of ca. 10 nm. The phenomenon may be well understood by the temperature-dependent growth process involved in different nucleation sources. A growth mechanism has been proposed in which the degree of ZnO(2)(2-)saturation in the reaction solution plays a key role in controlling the nucleation and growth of the ZnO NWs or SMRs as well as in oxidizing the metallic Zn microspheres. Based on this consideration, ultrathin ZnO NW cluster arrays on the Zn microspheres are successfully obtained. Raman spectroscopy and photoluminescence measurements of the ultrathin ZnO NW cluster arrays have also been performed.
    Advanced Functional Materials 04/2007; 17(8):1303 - 1310. DOI:10.1002/adfm.200600390 · 11.81 Impact Factor
  • G M Wang · J B Ma · Y Z Jin · Y G Feng · J Hao · X Gao · S S Xie
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    ABSTRACT: There is a need to achieve donor-specific tolerance in clinical organ transplantation, where potential benefits remain overshadowed by chronic rejection and the side-effects of long-term immunosuppressive therapy. It is known that the mature immune system in mice can be reprogrammed to accept a foreign graft as if it was "self". The AdCTLA4Ig-mediated gene transfer (SC) + cyclophosphamide (CP) treatment alone prolongs allograft survival but does not induce tolerance. However, in our study, the AdCTLA4Ig-mediated gene transfer combined with SC + CP treatment yielded significantly prolonged mean survival times (149.7 +/- 18.0 days), while those in the untreated or AdLacZ treated mice were rejected in normal fashion (5.3 +/- 0.5 and 5.2 +/- 0.4 days, respectively), and survival in the AdCTLA4Ig or SC + CP treated groups were 45.7 +/- 9.6 or 50.2 +/- 5.3 days, respectively. In conclusion, a protocol of AdCTLA4Ig + SC + CP improved the survival of DA-->LEW cardiac allografts.
    Transplantation Proceedings 11/2006; 38(9):3043-5. DOI:10.1016/j.transproceed.2006.08.176 · 0.95 Impact Factor
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    ABSTRACT: We report that the conductance of macroscopic multiwall nanotube (MWNT) bundles under pressure shows power laws in temperature and voltage, as corresponding to a network of bulk-bulk connected Tomonaga-Luttinger liquids (LLs). Contrary to individual MWNTs, where the observed power laws are attributed to Coulomb blockade, the measured ratio for the end and bulk obtained exponents, approximately 2.4, can be accounted for only by LL theory. At temperatures characteristic of interband separation, it increases due to thermal population of the conducting sheets unoccupied bands.
    Physical Review Letters 11/2006; 97(17):176401. DOI:10.1103/PhysRevLett.97.176401 · 7.51 Impact Factor
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    ABSTRACT: We demonstrate a low-cost and effective method to fabricate hexagonally patterned, vertically aligned ZnO nanorod arrays. Selective wet-etching is used to develop the catalyzing gold particle hexagonal pattern with the aid of a polystyrene microsphere self-assembled monolayer. The gold particles have tunable sizes independent of the polystyrene microsphere's diameter and are inherently round in shape. Each ZnO rod is grown individually from a catalyzing site via catalyst-initiated epitaxy, and the original hexagonal periodicity is well-preserved. The rods have flat ends, and the diameters of the rods can be controlled well by the amount of source materials. This method provides a promising way to create ZnO one-dimensional nanostructures for applications as two-dimensional photonic crystal, sensor arrays, nanolaser arrays, and optoelectronic devices.
    Nano Letters 11/2006; 6(10):2375-8. DOI:10.1021/nl061399d · 13.59 Impact Factor
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    ABSTRACT: Silver (Ag) nanodecahedrons have been synthesized for the first time by liquid-phase reduction of AgNO3 with assistance of polyvinylpyrrolidone (PVP) in a large scale. The edge size of Ag decahedrons is estimated to be ca. 80 nm. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) have been employed to elucidate the five-twinned structure of Ag decahedrons. The results show that the Ag decahedrons capped by PVP molecules hold five-twinning structure with distinct twinning boundaries. The growth process of Ag decahedrons has been investigated and their growth mechanism has been proposed. Combined with our previous reports on Ag nanowires with pentagonal cross section, it is revealed that the Ag nanodecahedrons might be assembled from five tetrahedrons step by step. Further studies on the role of PVP conformation in different solution reduction systems are required.
    Journal of Crystal Growth 03/2006; 289(1-289):376-380. DOI:10.1016/j.jcrysgro.2005.11.123 · 1.69 Impact Factor
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    ABSTRACT: X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron spectroscopy (PES) have been used to investigate single-walled carbon nanotubes (SWNTs) modified by immersion in a HBr solution at room temperature. After treatment XANES spectra of SWNTs show a new pronounced feature, which has been assigned to new bonds between the sidewall of the SWNTs and Br atoms. This investigation demonstrates the unique capabilities of the XANES spectroscopy as a tool to achieve structural and bonding information of carbon nanotubes induced by chemical processes.
    Carbon 02/2006; 44:866-872. DOI:10.1016/j.carbon.2005.10.029 · 6.16 Impact Factor
  • G M Wang · Y Yang · YZ Jin · AL Li · J Hao · X Gao · S S Xie
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    ABSTRACT: CTLA4Ig, a recombinant fusion protein composed of the extracellular domain of human CTLA4 and the constant region of human IgG1, inhibits the interaction of CD28/B7 pathway by binding the B7 molecule. OX40Ig, a recombinant fusion protein composed of the extracellular domain of human OX40 and the constant region of human IgG1, abrogates the interaction of OX40/OX40L pathway by binding the OX40L on APCs. So blockade of CD28/B7 or OX40/OX40L co-stimulatory pathways alone in mice with CTLA4Ig or OX40Ig can result in finitely prolonging the survival of islet grafts (43.2 +/- 4.81 and 67.7 +/- 7.74 days, respectively). In this study, a novel replication-defective adenovirus containing both of the CTLA4Ig and OX40Ig genes, AdCTLA4Ig-IRES-OX40Ig, was constructed by homologous recombination and injected into the streptozocin-rendered diabetic BalB/c mouse recipients (H-2d) through the tail vein, at the same day, the freshly isolated islets from Lewis rats (RT-1) were transplanted under the left kidney capsule of the recipients. The results showed that the mean survival time of the islet xenografts in the AdCTLA4Ig-IRES-OX40Ig-treated diabetic mice was significantly prolonged (100.3 +/- 14.94 days), while those in the untreated or AdEGFP-treated mice were rejected in normal fashion (6.7 +/- 0.94 and 7.0 +/- 1.0 days, respectively). In conclusion, utilizing AdCTLA4Ig-IRES-OX40Ig in vivo which can simultaneously express CTLA4Ig and OX40Ig proteins can improve the survival of Lewis-->BalB/c islet xenografts.
    Transplantation Proceedings 12/2005; 37(10):4449-51. DOI:10.1016/j.transproceed.2005.10.117 · 0.95 Impact Factor

Publication Stats

4k Citations
395.31 Total Impact Points

Institutions

  • 1997–2011
    • Chinese Academy of Sciences
      • • Institute of Physics
      • • Graduate School
      • • Key Laboratory of Extreme Conditions Physics
      • • Condensed Matter Physics
      Peping, Beijing, China
  • 2005–2009
    • Peking University
      • Laboratory for the Physics & Chemistry of Nanodevices
      Peping, Beijing, China
    • National Center for Nanoscience and Technology
      Peping, Beijing, China
  • 1994–2009
    • Technical Institute of Physics and Chemistry
      Peping, Beijing, China
    • Academia Sinica
      • Institute of Physics
      T’ai-pei, Taipei, Taiwan
  • 2006
    • Peking University Health Science Center
      Peping, Beijing, China