Publications (11)17.23 Total impact
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Article: Titanate-silica mesostructured nanocables: synthesis, structural analysis and biomedical applications.
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ABSTRACT: 1D hierarchical composite mesostructures of titanate and silica were synthesized via an interfacial surfactant templating approach. Such mesostructures have complex core-shell architectures consisting of single-crystalline H(2)Ti(3)O(7) nanobelts inside the ordered mesoporous SiO(2) shell, which are nontoxic and highly biocompatible. The overall diameter of as-prepared 1D hierarchical composite mesostructures is only approx. 34.2 nm with a length over 500 nm on average. A model to explain the formation mechanism of these mesostructures has been proposed; the negatively charged surface of H(2)Ti(3)O(7) nanobelts controls the formation of the octadecyltrimethylammonium bromide (C(18)TAB) bilayer, which in turn regulates the cooperative self-assembly of silica and C(18)TAB complex micelles on the interface to produce a mesoporous silica shell. More importantly, the application of synthesized mesostructured nanocables as anticancer drug reservoirs has also been explored, which indicates that the membranes containing these mesoporous nanocables have a great potential to be used as transdermal drug delivery systems.Nanotechnology 02/2010; 21(6):065604. · 3.98 Impact Factor -
Article: Surface charging of layered double hydroxides during dynamic interactions of anions at the interfaces.
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ABSTRACT: In this research, we investigated the effect of dynamic anion adsorption/exchange on the surface charging property of Mg(2)AlClLDH and Mg(2)AlCO(3)LDH particles that show the average zeta potential of 41 and 34 mV in the as-prepared suspension, respectively. The addition of NaCl up to 3x10(-3) M in the suspension does not obviously affect the zeta potential of both LDHs, which can be attributed to the less affinity of Cl(-) to LDH. The introduction of Na(2)CO(3) severely reduces the zeta potential at the CO(3)(2-) concentration higher than 1x10(-4) M, and to the negative value in both LDH systems at ca. 2x10(-3) M, which is presumably resulted from the exchange and the re-orientation of CO(3)(2-) in a tilt/vertical style on the surface. All four organic anions (dodecyl sulfate, folate, citrate and polyacrylate) also significantly affect the zeta potential of the LDH particles. At the lower concentrations of organic anionic groups (<1x10(-4) M), the zeta potential was slightly affected, i.e. limited exchange/adsorption. However, the concentration increasing to some point suddenly decreases and reverses the zeta potential of the LDH particles, which is presumably caused by the hydrophobic interactions that bind the hydrophobic hydrocarbon chains (especially in dodecyl sulfate) into the micelle-like bilayer bunches on the LDH surface. In addition, the effect of pH in 5.5-11.0 on the LDH particle surface charging is mainly reflected through the conversion of CO(3)(2-) to HCO(3)(-)/H(2)CO(3) when pH decreases from ca. 11 to 6, with limited contribution from protonation/deprotonation and exchange/adsorption.Journal of Colloid and Interface Science 10/2008; 326(2):522-9. · 3.07 Impact Factor -
Article: Fabrication and Size‐Selective Bioseparation of Magnetic Silica Nanospheres with Highly Ordered Periodic Mesostructure
Advanced Functional Materials 09/2008; 18(20):3203 - 3212. · 10.18 Impact Factor -
Article: Specific anion and cation capacitance in porous carbon blacks
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ABSTRACT: Porous carbon black was modified to introduce oxygen and nitrogen surface functionality and characterized using wet titration methods, elemental analysis, XPS, TEM, thermal analysis, adsorption of nitrogen and carbon dioxide. Then the electrochemical capacitance was measured for cations and anions in 1 M H2SO4. The results were compared to those obtained on activated carbons. The modified carbon black samples have four times higher adsorption of anions than cations. It is hypothesized that the graphitic microstructure of carbon blacks with structural defects is responsible for intercalation of anions in-between the graphene layers which take place at potentials higher than 0.75 V vs. Ag/AgCl and at moderately low current loads. This process is reversible and the deintercalation occurs at approximately 0.4 V vs. Ag/AgCl during the cathodic reduction. Introduction of nitrogen have generally a detrimental effect on the anion adsorption capacitance due to a structural defects blockage. At high current loads this phenomenon of enhanced anion adsorption capacitance becomes less pronounced due to the kinetic limitations. For amorphous activated carbons enhanced anion electrosorption at low current loads is governed by proton assistance while at high current loads larger cation capacitance is due to the pseudocapacitive interactions of protons with nitrogen and oxygen functional groups.Carbon. 48(6):1767-1778. -
Article: Microstructure refinement of cast TiAl alloys by β solidification
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ABSTRACT: Microstructure refinement of TiAl alloys is realized by introducing β solidification in this paper. The obtained fine-grained cast microstructures can be optimized to be fine-grained fully lamellar structures merely by a one-step heat treatment. The present study may provide an alternative and cost-effective approach for microstructure refinement of TiAl alloys.Scripta Materialia. -
Article: Novel Nafion composite membranes with mesoporous silica nanospheres as inorganic fillers
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Article: Hydrolytically stable phosphorylated hybrid silicas for proton conduction
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ABSTRACT: A new approach to the synthesis of fully immobilized phosphorus functionalized hybrid proton conductive gels based on phosphonic acid grafting is presented in this paper. The hybrid silicas with different amounts of phosphonic acid have been prepared and characterized using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area analysis, thermogravimetric analysis, and electrochemical techniques. The proton conductivity of the materials depend strongly on hydration, which increases by four orders of magnitude over the relative humidity (RH) range of 20 to 100 %, up to a maximum of 0.027 S cm(-1) at 100 degrees C and 100 % RE For the reported samples, proton conduction is believed to occur within a dynamic hydrogen-bond network formed by functionalized P-OH groups and water molecules by the Grotthuss mechanism. However, the proton conductive sites (P-OH) are likely to be partially immobilized by strong protonic receptors (N atoms in amines), which reduces the free P-OH groups and restricts proton transfer. Hydration may cause a bonding structural rearrangement, which results in more free P-OH groups as active proton conductive sites and, therefore, greatly increased proton conductivity is observed. -
Article: Zr(HPO4)(2) based organic/inorganic nanohybrids as new proton conductors
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ABSTRACT: In this study, sulfanilic acid was intercalated into an alpha-Zr(HPO4)(2) with the aim to enhance the proton conductivity via the acidic -SO3H groups. TGA results suggest that intercalation really takes place and a four-day reaction leads to the intercalation of 0.72 guest molecules (sulfanilic acids) per alpha-Zr(HPO4)(2). We find that the hybrid material undergoes three-step decomposition pathways: dehydration (40-150 degrees C), decomposition of benzene ring (150-470 degrees C), and finally de-SOx (470-1000 degrees C). The sulfanilic acid/alpha-Zr(HPO4)(2) hybrid shows a proton conductivity of 2.80 x 10(-3) S/cm, one order higher than the original alpha-Zr(HPO4)(2) (2.04 x 10(-4) S cm(-1)) measured at a relative humidity of 100% and 22 degrees C. The conductivity is strongly dependent on the relative humidity, and sharply increases at over 80% relative humidity. The activation energy for the proton transport in the hybrid is 0.33 and 0.15 eV at 60% and 100% relative humidity, respectively, in the temperature range of 22-100 degrees C, further reflecting the influence of humidity on the proton conduction. -
Article: Effects of niobium doping site and concentration on the phase structure and oxygen permeability of Nb-substituted SrCoOx oxides
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Article: Hydrophobic functional group initiated helical mesostructured silica for controlled drug release
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Article: Proton conductive composite membrane of phosphosilicate and polyvinyl alcohol
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ABSTRACT: Proton conductive composite membranes were prepared by dispersing phosphosilicate colloidal particles into a polyvinyl alcohol (PVA) matrix. The synthesized membranes were flexible with film thickness between 80 and 200 gm. SEM micrographs show that the phosphosilicate particles are homogenously dispersed, whilst the PVA crosslinks with the inorganic phase and fills in the gaps between the particles. Proton conductivity increases by several orders of magnitude with increasing humidity, reaching a maximum of 0.02 S/cm at ambient temperature and 100% relativity humidity (RE). The activation energy is reduced to 7.3 kJ/mol with RH increasing to 90% in the tested temperature range 2070 degrees C. From structural characterization and conductivity measurements, it is deduced that proton transport occurs by both the Grotthuss and diffusion mechanisms. The methanol permeability was found 5-10 times lower than Nation 117. The composite membrane was tested in the direct methanol fuel cell (DMFC). The preliminary results show the membrane is a promising candidate for PEM for use in DMFC systems. (C) 2007 Elsevier B.V. All rights reserved.
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Institutions
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2010
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The Second Military Medical University
Shanghai, Shanghai Shi, China -
University of Queensland
- School of Chemical Engineering
Brisbane, Queensland, Australia
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