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Ma L.,Tsinghua University | Ma L.,Institute of Chemical Defence | He D.,Tsinghua University
Catalysis Today | Year: 2010

Bimetallic Ru-Re/SiO2 and monometallic Ru/SiO2 catalysts were prepared by impregnation method and their catalytic performances were evaluated in the hydrogenolysis of glycerol to propanediols (1,2-propanediol and 1,3-propanediol) with a batch type reactor (autoclave) under the reaction conditions of 160 °C, 8.0 MPa and 8 h. Ru-Re/SiO2 showed much higher activity in the hydrogenolysis of glycerol than Ru/SiO2, and the pretreatment conditions of the catalyst precursors had great influence on the catalytic performance of both Ru-Re/SiO2 and Ru/SiO2 catalysts. The physicochemical properties of Ru-Re/SiO2 and Ru/SiO2, such as specific surface areas, crystal phases, morphologies/microstructures, surface element states, reduction behaviors and dispersion of Ru metal, were characterized by N2 adsorption/desorption, XRD, Raman, TEM-EDX, XPS, H2-TPR and CO chemisorption. The results of XRD, TEM-EDX and CO chemisorption characterizations showed that Re component had an effect on promoting the dispersion of Ru species on the surface of SiO2, and the measurements of H2-TPR revealed that the co-existence of Re and Ru components on SiO2 changed the respective reduction behavior of Re or Ru alone. High pre-reduction temperatures would decrease the activities of Ru-Re/SiO2 and Ru/SiO2 catalysts, compared with the corresponding calcined catalysts (without pre-reduction), which actually went through an in-situ reduction during the reaction. XPS analysis indicated that Ru species was in Ru0 metal state, while Re species was mostly in Re oxide state in the spent Ru-Re/SiO2 sample. Re component was probably in rhenium oxide state rather than Re0 metal state to take part in the reaction via interaction with Ru0 metal. © 2009 Elsevier B.V. All rights reserved.

Gao X.,Beijing University of Chemical Technology | Dong J.,Institute of Chemical Defence | Zhang X.,Beijing University of Chemical Technology
Molecular Simulation | Year: 2015

Molecular simulation studies on the interaction between nanoparticles (NPs) and cell membranes have been limited by small NP size of several nanometres. In this work, by using a simplified lipid model, we study the endocytosis of large NPs with a size being enlarged to 37.5 nm. It is found that the effect of NP size on endocytosis dynamics depends on the membrane-NP interaction. As the interaction strength between NP and lipid changes, different wrapping modes are observed. For the system with weak membrane-NP attraction, the wrapping process is controlled by the membrane bending, and thus large size of NPs (within the range of NP size we studied) would promote the wrapping dynamics. While for the case with strong membrane-NP adhesion, the wrapping process is dominated by lipid diffusion and small NPs show a larger wrapping rate. In this wrapping mode, the membrane-NP adhesion drives small NPs to move towards the membrane as the wrapping process proceeds. For relatively larger NPs, however, the membrane moves towards the NPs instead. We also find that for the second wrapping mode, the rapid wrapping rate, especially with the hydrophobic ligands on the hydrophilic NP would impose significant perturbations on membrane stability, and consequently, membrane pores may be induced during the process of NP endocytosis. © 2014 Taylor & Francis.

Yang S.,CAS Hefei Institutes of Physical Science | Yang S.,University of Munster | Cai W.,CAS Hefei Institutes of Physical Science | Kong L.,Institute of Chemical Defence | And 2 more authors.
Advanced Functional Materials | Year: 2010

Surface patterns of nanoshell arrays play an important role in diverse applications including surface-enhanced Raman scattering (SERS) sensors, lithium-ion batteries, solar cells, and optical devices. This paper describes an innovative surface nanopatterning technique for realizing large-scale ordered arrays of metallic spherical nanoshells with well-defined structures. Ag nanoshell arrays are prepared using polystyrene sphere templates by an electrophoretic process in Ag colloidal solutions. The fabricated Ag nanoshell arrays have a high controllability of the structural parameters, including the diameter, the surface roughness, and the intershell spacing, giving rise to the tunable properties of nanoshell arrays. As an example, tunable SERS and localized surface plasmon resonance of the nanoshell arrays are demonstrated by controlling the structural parameters. The surface nanopatterning tech nique shown in this paper is a general fabrication process in achieving not only metallic nanoshell arrays, but also nanoshell arrays of semiconductors and metallic oxides. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu D.,Tsinghua University | Liu M.,Tsinghua University | Liu M.,Technical Center | Liu G.,Institute of Chemical Defence | And 3 more authors.
Analytical Chemistry | Year: 2010

Extracting multidimensional information from an individual transducer simultaneously is a promising alternative sensing strategy to traditional sensors. Here, we proposed a novel dual channel sensing method with simultaneously recording conductivity change of sensing material and chemiluminescence emission during catalytic oxidation of volatile organic compounds on tin oxide nanoparticles. The orthogonal and complementary electrical and optical signals have been obtained for each compound, which have been applied to discriminate 20 volatile organic compounds using hierarchical cluster analysis (HCA). Unknown samples from three groups at concentrations of 0.2%, 0.6%, and 1.0% have been successfully classified using linear discriminant analysis (LDA) with accuracies of 98.3%, 96.7%, and 98.3%, respectively. This dual channel sensing mode is a complement of semiconducting type gas sensors and quite promising for the development of chemical sensor arrays with multimode transducing principles. © 2010 American Chemical Society.

Jin L.,Tsinghua University | Wu W.-H.,Tsinghua University | Wu W.-H.,Institute of Chemical Defence | Li Q.-Y.,Tsinghua University | And 2 more authors.
Nanoscale | Year: 2011

Copper is known to be a critical factor in Alzheimer's disease (AD) pathogenesis, as it is involved in amyloid-β (Aβ) peptide related toxicity. However, the relationship between neurotoxicity and Aβ peptide in the presence of copper remains unclear. The effect of copper has not been clearly differentiated between Aβ42 and Aβ40, and it is still debated whether copper-mediated neurotoxicity is due to reactive oxygen species (ROS) accumulation or other molecular mechanisms. Here, we describe that copper dramatically affects Aβ42 aggregation and enhances Aβ42 cytotoxicity while it shows no significant effects on Aβ40. These phenomena are mainly because that the strong interactions between copper and Aβ42 lead to great conformation changes, and stabilize Aβ42 aggregates at highly toxic nanoscale oligomer stage, whereas copper shows no similar impact on Aβ40. We also propose a possible molecular mechanism that copper enhances Aβ42 cytotoxicity via perturbing membrane structure. Moreover, we test the effect of an analogue of copper, nickel, on Aβ aggregation and cytotoxicity, finding that nickel also enhances cytotoxicity via Aβ42 nanoscale oligomer formation. These results clarify that the copper-induced Aβ42 nanoscale oligomer formation is the key process for Aβ neurotoxicity, and suggest that disrupting the interactions between copper and Aβ42 peptide to inhibit nanoscale oligomerization process, deserves more attention in AD drug development. © 2011 The Royal Society of Chemistry.

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