1.Introduction Biodegradable polymeric biomaterials have been fabricated into various biomedical implants such as drug delivery nanoparticles,tissue engineering scaffolds and orthopedic devices.Using biodegradable pol...1.Introduction Biodegradable polymeric biomaterials have been fabricated into various biomedical implants such as drug delivery nanoparticles,tissue engineering scaffolds and orthopedic devices.Using biodegradable polymers as implant materials is beneficial as the implants are degraded and cleared by the body once their missions are complete,leaving no foreign materials in the body.Driven by the versatile needs in biomedical engineering,searching for ideal functional biodegradable polymers has been an endless effort in the past decades.Among biodegradable polymers,citrate-based biodegradable elastomeric(CABE)polymers have recently received increasing attention because their compliance under force can closely resemble the elastic展开更多
Dispersion behavior of ultra fine BaTiO3 particles in the aqueous solution of ammonium citrate （NH4-CA） or citric acid lanthanum chelate （NH4-La-CA） was investigated. The dispersion property was characterized with...Dispersion behavior of ultra fine BaTiO3 particles in the aqueous solution of ammonium citrate （NH4-CA） or citric acid lanthanum chelate （NH4-La-CA） was investigated. The dispersion property was characterized with sedimentation value. It is easier to obtain well dispersed slurry with NH4La-CA than NH4-CA. In an attempt to better understand the role of citric acid radical, simulation of the dispersant adsorption on BaTiO3 particle was performed with universal force field （UFF）. It is demonstrated that the interaction between citric acid radical and BaTiO3 particle surface is a weak chemical adsorption. Trivalent citric acid radical is adsorbed on BaTiO3 particle surface with maximal adsorption energy. And, larger molecules of NH4-La-CA formed by adding La^3＋ lead to better dispersion property than NHn-CA.展开更多
A novel technology for lead removal with nonliving Rhizopus oligosporus immobilized in calcium alginate was studied. The results show that the main influencing factors include pH value and interfering cations. pH valu...A novel technology for lead removal with nonliving Rhizopus oligosporus immobilized in calcium alginate was studied. The results show that the main influencing factors include pH value and interfering cations. pH value has different effects on biosorption of various heavy metals and lead adsorption can be proceeded by controlling pH value in a range of 2–5; interfering cations especially Cu(II) can make the adsorption amount of Pb(II) decrease by immobilized Rhizopus oligosporus. Desorption efficiency of different eluants and kinetics were investigated. Citrate acid with concentration of 0.3 mol ? L?1 is the best for the elution of Pb(II) and desorption rate is over 98%when the reaction equilibrium reaches 3 h. Immobilized biomass keeps high lead biosorption capacity after five cycles of regeneration.展开更多
The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric a...The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.展开更多
The citrate gel of (Bi, Pb), Sr, Ca and Cu and the (Bi, Pb)SrCaCu(O, F) superconductor were prepared using citrate as the organic complex agent and 2ethyl hexanol as the dehydrating agent. The starting material was a ...The citrate gel of (Bi, Pb), Sr, Ca and Cu and the (Bi, Pb)SrCaCu(O, F) superconductor were prepared using citrate as the organic complex agent and 2ethyl hexanol as the dehydrating agent. The starting material was a highpurity nitrate solution containing the desired ions in the appropriate atomic ratio. The optimum temperature and pH to obtain the homogeneous gel precursor were estimated. IR and DSC were employed to study the thermal decomposition and the calcination of the precursor material. After the calcined powder was sintered, a nearly singlephase (Bi, Pb)2Sr2Ca2Cu3Ox superconductor with the transition temperature 105 K was synthesized. The effect of the doping of Pb and F was also studied in the paper.展开更多
基金supported in part by a NSF CAREER award(1313553)a NIH R01 award (EB012575)+2 种基金a NSF collaborative research award(1266116)a CPRIT High Impact/High Risk Research Award(RP110412)a research award from National Natural Sciences Foundation of China(31228007)
文摘1.Introduction Biodegradable polymeric biomaterials have been fabricated into various biomedical implants such as drug delivery nanoparticles,tissue engineering scaffolds and orthopedic devices.Using biodegradable polymers as implant materials is beneficial as the implants are degraded and cleared by the body once their missions are complete,leaving no foreign materials in the body.Driven by the versatile needs in biomedical engineering,searching for ideal functional biodegradable polymers has been an endless effort in the past decades.Among biodegradable polymers,citrate-based biodegradable elastomeric(CABE)polymers have recently received increasing attention because their compliance under force can closely resemble the elastic
基金Project(020951) supported by Natural Science Fundation of Guangdong Province, China
文摘Dispersion behavior of ultra fine BaTiO3 particles in the aqueous solution of ammonium citrate （NH4-CA） or citric acid lanthanum chelate （NH4-La-CA） was investigated. The dispersion property was characterized with sedimentation value. It is easier to obtain well dispersed slurry with NH4La-CA than NH4-CA. In an attempt to better understand the role of citric acid radical, simulation of the dispersant adsorption on BaTiO3 particle was performed with universal force field （UFF）. It is demonstrated that the interaction between citric acid radical and BaTiO3 particle surface is a weak chemical adsorption. Trivalent citric acid radical is adsorbed on BaTiO3 particle surface with maximal adsorption energy. And, larger molecules of NH4-La-CA formed by adding La^3＋ lead to better dispersion property than NHn-CA.
文摘A novel technology for lead removal with nonliving Rhizopus oligosporus immobilized in calcium alginate was studied. The results show that the main influencing factors include pH value and interfering cations. pH value has different effects on biosorption of various heavy metals and lead adsorption can be proceeded by controlling pH value in a range of 2–5; interfering cations especially Cu(II) can make the adsorption amount of Pb(II) decrease by immobilized Rhizopus oligosporus. Desorption efficiency of different eluants and kinetics were investigated. Citrate acid with concentration of 0.3 mol ? L?1 is the best for the elution of Pb(II) and desorption rate is over 98%when the reaction equilibrium reaches 3 h. Immobilized biomass keeps high lead biosorption capacity after five cycles of regeneration.
基金Project(50975058)supported by the National Science Foundation of China
文摘The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.
文摘The citrate gel of (Bi, Pb), Sr, Ca and Cu and the (Bi, Pb)SrCaCu(O, F) superconductor were prepared using citrate as the organic complex agent and 2ethyl hexanol as the dehydrating agent. The starting material was a highpurity nitrate solution containing the desired ions in the appropriate atomic ratio. The optimum temperature and pH to obtain the homogeneous gel precursor were estimated. IR and DSC were employed to study the thermal decomposition and the calcination of the precursor material. After the calcined powder was sintered, a nearly singlephase (Bi, Pb)2Sr2Ca2Cu3Ox superconductor with the transition temperature 105 K was synthesized. The effect of the doping of Pb and F was also studied in the paper.
