Papers by Author: Wen Jian Weng

Abstract: Calcium sulfate/type I collagen composite pellets were prepared by a feasible route of casting method. The as-prepared composite pellets were characterized and the results showed that the collagen fibrils acted as bridges to connect the adjacent calcium sulfate grains, especially when there was a high mass loading of collagen, which effectively depressed the rapid degradation of the pellets and improved compressive strength, and the optimal strength reached 17.2 MPa with 6 mg/mL collagen solution. The MC3T3-E1 cells could be well attached and spread on the surface of the composite pellets. Moreover, it is found that the collagen be released through pellets degradation further promoted the cells proliferation.

Abstract: Electrochemical biosensors are widely applied in areas related to health monitors. Protein adsorptions on the electrode and direct electron transfer between enzymes and electrode have been recognized as key factors affecting sensor performance. In this work, TiO₂ nanodots films were prepared on Ti substrate to act as electrodes of biosensors. The effect of the nanodots film microstructure on electrode performance was carried out. It was found that the performances H₂O₂ biosensor could be improved by tailoring TiO₂ nanodots film microstructure in the electrodes. The present work could provide an alternative to obtain biosensor with high performance.

Abstract: Micro-nano structured TiO₂ films were prepared by hydrothermally seed layer-induced synthesis. The results showed that the films were composed of TiO₂ platelets in size of 2μm~10μm. The maximum distance between platelets was ~4 μm. There were TiO₂ nanodots (seed layer) in size of ~100nm between TiO₂ platelets. This structured film was proven to be anatase and more anatase was detected along with hydrothermal synthesis. Water contact angle varied from 103° to 149° along with hydrothermal synthesis and all films showed super-hydrophilicity after UV illumination. These micro-nano structured films obtained in this study could potentially applied in many biomedical applications, e.g., osseointegration film and cell sheet technology, owing to its excellent biocompatibility and UV switchable super-hydrophilicity.

Abstract: Biphasic tricalcium phosphate (BTCP) powders composed of α-tricalcium phosphate (α-TCP) and β-tricalcium phosphate (β-TCP) were prepared using amorphous calcium phosphate (ACP) precursor after heat treatment at 800oC. The in vitro dissolution behavior of the powders was examined after soaked in 0.1M NaAc-HAc buffer solution for different times. It was revealed that the Ca2+ and PO4 3- concentration, and pH value of the BTCP-soaked solution are higher than those of the α-TCP- and β-TCP-soaked solutions. The dissolution behavior of BTCP powders was explained. The specific dissolution behavior of BTCP powders can widen the biodegradation range of calcium phosphate family.

Abstract: Ni0.5Zn0.5Fe2O4-BaTiO3 composites were prepared by calcining Ni0.5Zn0.5Fe2O4 with BaTiO3 at 1220°C for 3 h. Both μ′ and μ″ of the composites decrease rapidly, but the cut-off frequency shifts to higher level with increasing BaTiO3 content. The dielectric constant of the composites increases quickly with increasing BaTiO3 content below 50% and keeps a high and nearly unchangeable value with increasing BaTiO3 above 50%. The composites with BaTiO3 content between 20% and 40% are suitable to use for the magneto-electric devices under high applied frequency due to its high permeability and low dielectric loss.

Abstract: Ferroelectric/ferromagnetic multiphase powdered composites, consisting of PbTiO3 as ferroelectric phase and NiFe2O4 (PbFe12O19) as ferromagnetic phase, were successfully prepared in situ by sol-gel process. The phase structure, morphology and magnetism properties were observed. Biphase powdered ME composite consisting of PbTiO3 and NiFe2O4 is obtained at 700oC. Triphase composite consisting of PbTiO3, NiFe2O4 and PbFe12O19 is obtained above 750oC. With increasing heat-treatment temperature, the particles combine more tightly and the particle size decreases. The saturation magnetization (σs) and the initial permeability (μi) increase with the increase of NiFe2O4 content. The coercive force (Hc) increases with the increase of PbFe12O19 content.

Abstract: PST/Bi2Ti2O7 composite thin films were prepared by sol-gel method through heavily doping Bi3+ into lead strontium titanate (PST). The film with mono pyrochlore phase of Bi2Ti2O7 was also fabricated by controlling the Ti content in precursors. XRD, SEM and impedance analyzer measured the phase status, morphology and dielectric properties of the thin films, respectively. As a result, in the composite thin films, there was some Pb and Sr dissolved in Bi2Ti2O7, and the amount of dissolving ions decreased with the reduction of their composition in precursors. Bi4Ti3O12 impurity in crystalline Bi2Ti2O7 was due to the instability of Bi, and excess Ti in stoichiometry could make the film maintain to be mono pyrochlore phase. PST/Bi2Ti2O7 composite thin films had lower permittivity and lower dielectric loss than mono PST thin films.

Abstract: (PbySr1-y)ZnxTi1-xO3-x thin films were prepared on ITO/glass substrate by sol–gel process using dip-coating method. The phase structure, morphology, and dielectric properties of thin films were investigated by XRD, SEM and impedance analyzer, respectively. The perovskite phase structure was exhibited in the Zn-doped PST thin films. The formation ability of the thin films of the perovskite phase and its grain size decreased with the increase in doping Zn. The dielectric constant of the thin film was influenced by oxygen vacancies which could be controlled by Zn doping.

Abstract: The synthesis of aluminum titanate solid solution (Al2(1-x)MgxTi1+xO5, x=0, 0.1, 0.2) powders was realized by solid state reaction method using fine commercial α-Al2O3, TiO2 and MgO powders as raw materials. The effect of the introduced amount of MgO on the phase formation of aluminum titanate solid solution was investigated by XRD following the phase evolution. It was revealed that the introduction of MgO strongly affects the formation of Al2(1-x)MgxTi(1+x)O5 solid solution. The easily formed MgTi2O5 acts as the nucleus prompting the formation and lowering the synthesis temperature. The microstructure and properties of the solid solution ceramics were also studied by SEM and measuring the fracture strength and the thermal expansion coefficient.

Abstract: Aluminum phosphate is one of the best inorganic binders, and the addition of chromium oxide can improve the properties of the binder. In this work, the phase evolutions in chromium phosphate system and aluminum-chromium-phosphate system during heat-treatment were investigated. The initial binder solutions were prepared by dissolving Al(OH)3 and Cr2O3 in aqueous H3PO4 solution. The binder solutions consolidated at 100°C. The as-consolidated products were heated at different temperature. The experimental results showed the phase evolution of the consolidated products as: amorphous phase in 300~800°C, Cr(PO3)3 and Cr4(P2O7)3 in 900~1200°C for chromium phosphate system binder; amorphous phase in 300~1000°C, Cr(PO3)3 and AlPO4 in 1100°C, Cr4(P2O7)3 and AlPO4 in 1200°C for aluminumchromium- phosphate system binder. The addition of chromium oxide demonstrates to strengthen amorphous network, which further improves the thermal stability.