Showing papers by "Nanjing Tech University published in 2008"

Electrochemical impedance immunosensor based on three-dimensionally ordered macroporous gold film.

Abstract: A novel label-free immunosensor for the detection of C-reactive protein (CRP) was developed based on a three-dimensional ordered macroporous (3DOM) gold film modified electrode by using the electrochemical impedance spectroscopy (EIS) technique The electrode was electrochemically fabricated with an inverted opal template, making the surface area of the 3DOM gold film up to 144 times higher than that of a classical bare flat one, characterized by the cyclic voltammetric (CV) technique The 3DOM gold film which was composed of interconnected gold nanoparticles not only has a good biocompatible microenvironment but also promotes the increase of conductivity and stability The CRP immunosensor was developed by covalently conjugating CRP antibodies with 3-mercaptopropionic acid (MPA) on the 3DOM gold film electrode The CRP concentration was measured through the increase of impedance values in the corresponding specific binding of CRP antigen and CRP antibody The increased electron-transfer resistance (Ret)

Microspheric Organization of Multilayered ZnO Nanosheets with Hierarchically Porous Structures

Abstract: Novel superstructures of multilayered ZnO nanosheets with hierarchically porous structures are successfully synthesized from a hydrothermal preparation and thermal decomposition of a layered precursor of zinc hydroxide carbonate (denoted as ZnHC). Nanosheet-based ZnHC microspheres are self-assembled by the hydrothermal process by using zinc nitrate hexahydrate and urea as the starting materials. The corresponding microspheric organizations of multilayered ZnO nanosheets with hierarchically porous structures are obtained by the thermal decomposition ZnHC precursor at 573 K. SEM images show that the average diameter of ZnO assembled microspheres is about 15 μm, and the length of a ZnO nanosheet building block which is made up of thin mutilayered sheets is around ∼7 μm. Studies also show well-crystallized pores with hierarchically distributed pore sizes are embedded in the multilayered ZnO nanosheets building blocks. A plausible dissociation-deposition mechanism using in situ formed Zn(OH)2 nuclei as the “sa...

Synthesis of Biodiesel in Capillary Microreactors

Abstract: KOH-catalyzed synthesis of biodiesel was carried out in capillary microreactors with inner diameters of 0.25 or 0.53 mm, with unrefined rapeseed oil and cottonseed oil as raw materials. The influences of the methanol to oil molar ratio, the residence time, the catalyst concentration, the reaction temperature, and the dimension of the capillary on the production of biodiesel were examined. The results indicated that the residence time was greatly reduced by using microchannel reactors, compared with a conventional batch reactor. The reaction temperature was the minimal factor in the yield of methyl ester. Meanwhile, the methyl ester yield first increased with the methanol/oil ratio and then decreased due to emulsion and saponification. The inner diameter of the microchannel reactor had a strong influence on the transesterification reaction. Higher methyl ester yield could be obtained at shorter residence times for the microchannel reactor with the smaller inner diameter.

CNx nanotubes as catalyst support to immobilize platinum nanoparticles for methanol oxidation

Abstract: Pt nanoparticles with sizes of 3–9 nm were well dispersed on carbon nitride (CNx) nanotubes without needing pre-surface modification on the CNx nanotubes due to the inherent chemical activity The products were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy All the experimental results revealed that Pt nanoparticles were immobilized on the CNx nanotubes due to the N-participation in the connection of Pt species with the support The electrocatalytic property of the as-prepared Pt/CNx catalyst in methanol oxidation was examined by cyclic voltammetry The results reveal that the so-constructed Pt/CNx catalyst has obvious catalytic activity, suggesting potential applications in fuel cells

Great Influence of Anions for Controllable Synthesis of CeO2 Nanostructures: From Nanorods to Nanocubes

Abstract: Controllable synthesis of well-shaped nanocrystals is of significant importance for understanding the surface-related properties as well as for the exploration of potential applications Herein, CeO2 nanorods and nanocubes were selectively synthesized using cerium(III) chloride and cerium(III) nitrate as precursor, respectively Counter anions of the cerium source were crucial to the shapes of the resulting products Intriguingly, the as-synthesized nanorods could be converted into nanocubes by the addition of an appropriate amount of NO3− ions into the hydrothermal reaction The NO3− ions are considered as both a capping agent and an oxidizer during the formation of CeO2 nanocubes Moreover, the influences of several others anions are investigated Br−, I−, and SO42− ions have similar roles to Cl− ions, which lead to the formation of nanorods The introduction of BrO3− ions can bring on the generation of irregular nanoparticles because they can function as an oxidizer but not a capping agent The anion-i

Effects of carbon blacks with various structures on vulcanization and reinforcement of filled ethylene-propylene-diene rubber

Abstract: The effects of carbon blacks on vulcanization and mechanical properties of filled ethylene-propylene-diene rub- ber (EPDM) are investigated, by comparing with five types of rubber-grade carbon blacks. Curing kinetics is studied by rheometer and the results indicate that the curing characteristics are influenced by combination of surface area of carbon black and sulphur content on the filler surface, because the former one enhances the physical cross-linking and the latter one introduces the additional chemical cross-linking. Both the degree of cross-linking and cure rate increase with increas- ing surface area and sulphur content, whereas the optimum cure time and scorch time decrease. The reinforcing nature of the carbon black is assessed from mechanical measurements. It is suggested that the surface area of carbon blacks strongly affects the physical properties of EPDM/carbon black composites. Conductive carbon black (N472) can be used as desir- able reinforcing filler due to the higher degree of cross-linking of EPDM with N472 than other EPDM/carbon black com- posites. The morphology and distribution of particles are studied by using scanning electron microscope. The sound reinforcing ability of N472 is also supported by scanning electron microscope due to the notable dispersibility of N472 within EPDM matrix. N472 ensures the EPDM/N472 composite the most conductive sample among the five composites.

Efficient production of hydrogen from natural gas steam reforming in palladium membrane reactor

Abstract: Ultra-thin, high performance composite palladium membrane, developed via a novel electroless plating method, was applied to construct a membrane reactor for methane steam reforming reaction, which was investigated under the following working conditions: temperature 723–823 K, pressure 300–900 kPa, gas hourly space velocity (GHSV) 4000–8000 mL g cat − 1 h − 1 , steam-to-carbon feed ratio (S/C, mol/mol) 2.5–3.5 and sweep ratio (defined as the ratio between flux of sweep gas to that of methane at the inlet of catalyst bed) 0–4.3. In contrast with previous investigations using commercial catalysts activated at lower temperatures, the catalyst applied in this work was a nickel-based one pre-reduced at 1023 K. The results indicated that selective removal of H2 from reaction zone obtained methane conversion much higher than thermodynamic control ones and CO selectivity significantly lower than thermodynamic control values. For instance, 98.8% methane conversion, over 97.0% selectivity to CO2 and over 95.0% H2 recovery rate could be obtained under mild working conditions. The much higher performance of membrane reactor was attributed to the combination of hydrogen ultra-permeable Pd-based membrane, highly active catalyst for methane steam reforming with countercurrent sweep gas flux design. Further work on stability investigation may develop an efficient onsite route of hydrogen production for application to proton exchange membrane fuel cells.

Strategies of pH control and glucose‐fed batch fermentation for production of succinic acid by Actinobacillus succinogenes CGMCC1593

Abstract: BACKGROUND: Succinic acid is an important precursor of numerous products, including pharmaceuticals, feed additives, green solvents, and biodegradable polymers. In this work, strategies of pH control and glucose-fed batch fermentation for producing succinic acid using Actinobacillus succinogenes CGMCC1593 were carefully optimized. RESULTS: The production of succinic acid was stable within the pH range 6.0–7.2. Both cell growth and succinic acid production were inhibited by high concentrations of sodium and calcium ions, while there was no significant inhibition by magnesium ions. With an initial glucose concentration of 25 g L−1, and glucose concentration was maintained between 10 and 15 g L−1 during the course of fed batch fermentation, succinic acid concentration, productivity and yield were 60.2 g L−1, 1.3 g L−1 h−1 and 75.1%, respectively. CONCLUSION: Of all the neutralization reagents used for pH control of A. succinogenes CGMCC1593, solid MgCO3 was the most satisfactory. With increase of initial glucose concentration, the time course showed a longer growth lag period and the maximum biomass declined, while more carbon was diverted to succinate synthesis. The results obtained in this study should be helpful for the design of a highly efficient succinic acid production process. Copyright © 2008 Society of Chemical Industry

Perovskite-type Oxide LaMnO3: An Efficient and Recyclable Heterogeneous Catalyst for the Wet Aerobic Oxidation of Lignin to Aromatic Aldehydes

Abstract: The perovskite-type oxide catalyst LaMnO3 prepared by the sol–gel method was found to be an efficient heterogeneous and recyclable catalyst for the wet aerobic oxidation of lignin to aromatic aldehydes. The lignin conversion rate and the yield of each aromatic aldehyde were enhanced significantly by the catalytic process as compared with the non-catalyzed process. Moreover, the activity, specific surface area and perovskite-type structure of the LaMnO3 catalyst remained nearly unchanged after five successive recycles of catalytic reactions.