The voltammetric behaviour of uric acid at overoxidized polypyrrole (OPPY ) film-coated glassy carbon (GC ) electrodes was investigaied. The chemically modi- fied electrodes exhilbited an excellent permselectivity for...The voltammetric behaviour of uric acid at overoxidized polypyrrole (OPPY ) film-coated glassy carbon (GC ) electrodes was investigaied. The chemically modi- fied electrodes exhilbited an excellent permselectivity for uric acid of undissociated form in an acidic medium. The current response sensitivity of uric acid at the modi- fied electrodes was markedly increased by properly anodizing activation of underly- ing electrodes and overoxidizing treatment of polypyrrole film. The voltammetric response of uric acid at the chemically modified electrode was linearly related to itinvestigatedtion in the range of 4. 0 ×10-7 -8. 0 ×10-5 mol/L in pH 5 buffer solu- tions. Ascorbic acid in less than 150-fold excess did not interfere with the voltam- metric determination of uric acid. The proposed procedure was utilized to determine uric acicl in human urine and serum samples without any pretreatment.展开更多
Boron doped diamond(BDD)performs well in electrochemical oxidation for organic pollutants thanks to its wide electrochemical window and superior chemical stability.We presented a method to obtain well-adherent large-s...Boron doped diamond(BDD)performs well in electrochemical oxidation for organic pollutants thanks to its wide electrochemical window and superior chemical stability.We presented a method to obtain well-adherent large-scale BDD/Nb electrode by the modified hot filament chemical vapor deposition system(HFCVD).SiC particles were sand blasted to enhance the adhesion of BDD coating.The BDD coating was then deposited on both sides of Nb which was placed vertically and closely with filament grids on both sides.The BDD/Nb electrodes had no deformation because the thermal deformations of the BDD films on both sides of the Nb substrate conteracted each other during cooling process after deposition.The surface morphology and purity of the BDD/Nb electrode were analyzed by Raman and scanning elestron microscope(SEM)techniques.Scratch test was used to investigate the adhesion of BDD films.The electrochemical performances were measured by cyclic voltammetry test.The BDD electrode at the B/C ratio of 2 000×10^(-6) held a higher oxygen evolution potential thanks to its high sp3 carbon content.Accelerated life test illustrated that the sandblasting pretreatment obviously enhanced the adhesion of BDD coating which resulted in a longer service duration than the un-sandblasted one.展开更多
he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o...he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o') was 0. 015 V (at25℃ , vs. SCE) and the heterogeneous electron transfer rate constant k_s obtainedvaried form 1. 10×10￣(-3) cm · s￣(-1) to 1. 80k×10￣(-3) cm · s￣(-1). The thermodynamic pa-rameters of the electron transfer reaction of cvtochrome C was also estimated. Fur-thermore, the effect of the various electrode surface states on the electrochemistryof cytochrome C was discussed.展开更多
为消除场致发射电推力器(Field emission electric propulsion,FEEP)羽流发散角度过大给推进器寿命和可靠性带来的不利影响,研究了聚焦电极阵列空间位置对羽流聚焦效果的影响,并通过正交试验法给出了最优电极分布。通过数值仿真对FEEP...为消除场致发射电推力器(Field emission electric propulsion,FEEP)羽流发散角度过大给推进器寿命和可靠性带来的不利影响,研究了聚焦电极阵列空间位置对羽流聚焦效果的影响,并通过正交试验法给出了最优电极分布。通过数值仿真对FEEP的离子运动过程建模,采用正交试验方法电极阵列进行研究,关注其在不同空间位置下的聚焦效果,得到了离子出射半角分布和推力大小。结果表明,聚焦极的位置决定了羽流的聚焦效果,其次是提取极和加速极;聚焦极径向距离发射极1600μm,且提取极径向和轴向坐标为(800μm,500μm)时能得到最优的聚焦效果。本文验证了正交试验方法在聚焦电极阵列设计上的可行性,同时还为聚焦电极阵列设计提供了有效的分析方法和设计策略。展开更多
文摘The voltammetric behaviour of uric acid at overoxidized polypyrrole (OPPY ) film-coated glassy carbon (GC ) electrodes was investigaied. The chemically modi- fied electrodes exhilbited an excellent permselectivity for uric acid of undissociated form in an acidic medium. The current response sensitivity of uric acid at the modi- fied electrodes was markedly increased by properly anodizing activation of underly- ing electrodes and overoxidizing treatment of polypyrrole film. The voltammetric response of uric acid at the chemically modified electrode was linearly related to itinvestigatedtion in the range of 4. 0 ×10-7 -8. 0 ×10-5 mol/L in pH 5 buffer solu- tions. Ascorbic acid in less than 150-fold excess did not interfere with the voltam- metric determination of uric acid. The proposed procedure was utilized to determine uric acicl in human urine and serum samples without any pretreatment.
基金supported by the National Natural Science Foundation of China(Nos.51575269,51275232)the Six Talent Peaks Project in Jiangsu Province(No.ZBZZ005)the Zhejiang Provincial Key Laboratory for Cutting Tools(No.ZD201305)
文摘Boron doped diamond(BDD)performs well in electrochemical oxidation for organic pollutants thanks to its wide electrochemical window and superior chemical stability.We presented a method to obtain well-adherent large-scale BDD/Nb electrode by the modified hot filament chemical vapor deposition system(HFCVD).SiC particles were sand blasted to enhance the adhesion of BDD coating.The BDD coating was then deposited on both sides of Nb which was placed vertically and closely with filament grids on both sides.The BDD/Nb electrodes had no deformation because the thermal deformations of the BDD films on both sides of the Nb substrate conteracted each other during cooling process after deposition.The surface morphology and purity of the BDD/Nb electrode were analyzed by Raman and scanning elestron microscope(SEM)techniques.Scratch test was used to investigate the adhesion of BDD films.The electrochemical performances were measured by cyclic voltammetry test.The BDD electrode at the B/C ratio of 2 000×10^(-6) held a higher oxygen evolution potential thanks to its high sp3 carbon content.Accelerated life test illustrated that the sandblasting pretreatment obviously enhanced the adhesion of BDD coating which resulted in a longer service duration than the un-sandblasted one.
文摘he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o') was 0. 015 V (at25℃ , vs. SCE) and the heterogeneous electron transfer rate constant k_s obtainedvaried form 1. 10×10￣(-3) cm · s￣(-1) to 1. 80k×10￣(-3) cm · s￣(-1). The thermodynamic pa-rameters of the electron transfer reaction of cvtochrome C was also estimated. Fur-thermore, the effect of the various electrode surface states on the electrochemistryof cytochrome C was discussed.
文摘为消除场致发射电推力器(Field emission electric propulsion,FEEP)羽流发散角度过大给推进器寿命和可靠性带来的不利影响,研究了聚焦电极阵列空间位置对羽流聚焦效果的影响,并通过正交试验法给出了最优电极分布。通过数值仿真对FEEP的离子运动过程建模,采用正交试验方法电极阵列进行研究,关注其在不同空间位置下的聚焦效果,得到了离子出射半角分布和推力大小。结果表明,聚焦极的位置决定了羽流的聚焦效果,其次是提取极和加速极;聚焦极径向距离发射极1600μm,且提取极径向和轴向坐标为(800μm,500μm)时能得到最优的聚焦效果。本文验证了正交试验方法在聚焦电极阵列设计上的可行性,同时还为聚焦电极阵列设计提供了有效的分析方法和设计策略。
