Chou model was used to investigate the dehydriding reaction kinetic mechanism of MgH_2-Nb_2O_5 hydrogen storage materials at 573 K.A new conception,'characteristic absorption/desorption time(t_c)'was introduce...Chou model was used to investigate the dehydriding reaction kinetic mechanism of MgH_2-Nb_2O_5 hydrogen storage materials at 573 K.A new conception,'characteristic absorption/desorption time(t_c)'was introduced to characterize the reaction rate The fitting results show that for the hydrogen desorbing mechanism,the surface penetration is the rate-controlling step.The mechanism remains the same even when the original panicle size of Nb_2O_5 is before ball milling(BM) or when the BM time changes And t_c indicates that the desorption rate of MgH_2-Nb_2O_5 will be faster than that of MgH_2-Nb_2O_5 by BM.The dehydriding reaction rate of MgH_2-Nb_2O_5(micro particle) BMed for 50 h is 4.76 times faster than that of the MgH_2-Nb_2O_5(micro panicle) BMed for 0.25 h,while the dehydriding reaction rate of MgH_2-Nb_2O_5(nano particle) BMed for 50 h is only 1.18 times as that of the MgH2-Nb_2O_5 (nano particle) BMed for 0.25 h.The dehydriding reaction rate of the BMed MgH_2-Nb_2O_5(nano particle) is 1-9 times faster than that of the BMed MgH_2-Nb_2O_5(micro particle).展开更多
Change in valency of Nb-oxide in MnO-SiO_2-Nb_2O_5 system was studied with the electrochemical method using ZrO_2 as the solid electrolyte.Thermodynamic analysis has shown that the only possible reaction that could ta...Change in valency of Nb-oxide in MnO-SiO_2-Nb_2O_5 system was studied with the electrochemical method using ZrO_2 as the solid electrolyte.Thermodynamic analysis has shown that the only possible reaction that could take place at the working elec- trode is:2(Nb_2O_5)=2(Nb_2O_4)+O_2 with the a_0 values experimentally evaluated,values of a Nb_2O:/a Nb_2O:were calculated and isoactivity-ratio curves drawn in MnO-SiO_2-Nb_2O_5 triangles at 1418 and 1585K.The simultaneous existence of tetra-and penta-valent Nb mineral constituents in industrial Nb-bearing slags was thus verified experimentally.展开更多
The prostate secretory protein of 94 amino acids （PSP94） has been shown to interact with cysteine-rich secretory protein 3 （CRISP-3） in human seminal plasma. Interestingly, PSP94 expression is redaced or lost in t...The prostate secretory protein of 94 amino acids （PSP94） has been shown to interact with cysteine-rich secretory protein 3 （CRISP-3） in human seminal plasma. Interestingly, PSP94 expression is redaced or lost in the majority of the prostate tumours, whereas CRISP-3 expression is upregulated in prostate cancer compared with normal prostate tissue. To obtain a better understanding of the individual roles these proteins have in prostate tumourigenesis and the functional relevance of their interaction, we ectopically expressed either PSP94 or CRISP-3 alone or PSP94 along with CRISP-3 in three prostate cell lines （PC3, WPE1-NB26 and LNCaP） and performed growth inhibition assays. Reverse transcription-polymerase chain reaction and Western blot analysis were used to screen prostate cell lines for PSP94 and CRISP-3 expression. Mammalian expression constructs for human PSP94 and CRISP-3 were also generated and the expression, localization and secretion of recombinant protein were assayed by transfection followed by Western blot analysis and immunofluorescence assay. The effect that ectopic expression of PSP94 or CRISP-3 had on cell growth was studied by clonogenic survival assay follokving transfection. To evaluate the effects of coexpression of the two proteins, stable clones of PC3 that expressed PSP94 were generated. They were subsequently transfected with a CRISP-3 expression construct and subjected to clonogenic survival assay. Our results showed that PSP94 and CRISP-3 could each induce growth inhibition in a cell line specific manner. Although the growth of CRISP-3-positive cell lines was inhibited by PSP94, growth inhibition mediated by CRISP-3 was not affected by the presence or absence of PSP94. This suggests that CRISP-3 may participate in PSP94-independent activities during prostate tumourigenesis.展开更多
The microstructure, compressive properties at different temperatures and hardness of NiAl-Cr（Mo）-Nb alloy prepared by injection casting were investigated. Compared with the conventionally-cast alloy, the injection-c...The microstructure, compressive properties at different temperatures and hardness of NiAl-Cr（Mo）-Nb alloy prepared by injection casting were investigated. Compared with the conventionally-cast alloy, the injection-cast alloy exhibits a fine microstructure, i.e. the fine eutectic cell and interlamellar spacing as well as fine primary NiAl phase and NbCr2-type Laves phase due to the high cooling rate. In addition, the area fraction of eutectic cell increases due to the narrow intercellular zone. The Vickers hardness of injection-cast alloy is markedly enhanced. The ductility and strength at room temperature are increased by 88% and 30% compared with those of conventionally-cast alloy respectively. However, the high-temperature strength of injection-cast alloy is not improved markedly. The elevated temperature compression deformation behavior can be properly described by power-law equations.展开更多
A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics we...A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction, scanning electron microscope, and microwave dielectric properties measurements. These samples were identified as single phase and adopted A4B3O12-type cation-deficient hexagonal perovskite structure, which can be described as consisting of identical perovskite-like blocks, three corner-sharing BO6 octahedra thick, separated by layers of vacant octahedral. These ceramics have high dielectric constants in the range of 48-42, high quality factors (Q×f) up to 38 000 GHz, and low temperature coefficient of resonant frequencies (τf) in the range of (-40-+6)×10-6℃-1. With increasing content of La and Ti, the dielectric constants slightly decrease butτf gradually increases.展开更多
The corrosion resistance of Zr-1Nb alloy was compared with that of Zr-Sn-Nb-Fe and Zr-4 alloys, and the effect of hydrochemistry on the corrosion resistance of Zr-1Nb alloy was discussed. Experimental results show tha...The corrosion resistance of Zr-1Nb alloy was compared with that of Zr-Sn-Nb-Fe and Zr-4 alloys, and the effect of hydrochemistry on the corrosion resistance of Zr-1Nb alloy was discussed. Experimental results show that niobium oxide is partly soluble in LiOH aqueous solution. Therefore, when Zr-1Nb alloy is corroded in LiOH aqueous solution, a soluble niobate produced by the reaction between the corrosion products of beta -Nb particles and LiOH results in the formation of pores in the zirconium oxide films and causes the degradation of the corrosion resistance of Zr-1Nb alloy tested in LiOH aqueous solution.展开更多
A new niabate Sr6Ti7Nb9O42 was synthesized for the first time by solid state reaction in SrO-TiO2-Nb2O5 ternary system. The new compound was characterized by EPMA, XRD, SEM and DTA. The X-ray powder diffraction data o...A new niabate Sr6Ti7Nb9O42 was synthesized for the first time by solid state reaction in SrO-TiO2-Nb2O5 ternary system. The new compound was characterized by EPMA, XRD, SEM and DTA. The X-ray powder diffraction data of Sr6Ti7Nb9O42 were firstly reported in the paper. Sr6Ti7Nb9O42 crystallizes the hexagonal system with unit cell parameters a=8.9991(4) A,c= 11.5118(9)A. and space group P6/mcm (193), z=1. The calculated and measured densities are 4. 783 g/cm3 and 4. 764 g/cm3, respectively.展开更多
基金Project(2006AZ001)supported by the Shanghai Municipal Education Commission,ChinaProject(06JC14031)supported by the Scienceand Technology Commission of Shanghai Municipality,China+2 种基金Project(06QA14021)supported by the Shanghai Rising-Star Program(Atype),ChinaProject(200746)supported by the Foundation for the Author of National Excellent Doctoral Dissertation of ChinaProjectsupported by the Innovation Fund for Graduate Student of Shanghai University,China
文摘Chou model was used to investigate the dehydriding reaction kinetic mechanism of MgH_2-Nb_2O_5 hydrogen storage materials at 573 K.A new conception,'characteristic absorption/desorption time(t_c)'was introduced to characterize the reaction rate The fitting results show that for the hydrogen desorbing mechanism,the surface penetration is the rate-controlling step.The mechanism remains the same even when the original panicle size of Nb_2O_5 is before ball milling(BM) or when the BM time changes And t_c indicates that the desorption rate of MgH_2-Nb_2O_5 will be faster than that of MgH_2-Nb_2O_5 by BM.The dehydriding reaction rate of MgH_2-Nb_2O_5(micro particle) BMed for 50 h is 4.76 times faster than that of the MgH_2-Nb_2O_5(micro panicle) BMed for 0.25 h,while the dehydriding reaction rate of MgH_2-Nb_2O_5(nano particle) BMed for 50 h is only 1.18 times as that of the MgH2-Nb_2O_5 (nano particle) BMed for 0.25 h.The dehydriding reaction rate of the BMed MgH_2-Nb_2O_5(nano particle) is 1-9 times faster than that of the BMed MgH_2-Nb_2O_5(micro particle).
文摘Change in valency of Nb-oxide in MnO-SiO_2-Nb_2O_5 system was studied with the electrochemical method using ZrO_2 as the solid electrolyte.Thermodynamic analysis has shown that the only possible reaction that could take place at the working elec- trode is:2(Nb_2O_5)=2(Nb_2O_4)+O_2 with the a_0 values experimentally evaluated,values of a Nb_2O:/a Nb_2O:were calculated and isoactivity-ratio curves drawn in MnO-SiO_2-Nb_2O_5 triangles at 1418 and 1585K.The simultaneous existence of tetra-and penta-valent Nb mineral constituents in industrial Nb-bearing slags was thus verified experimentally.
文摘The prostate secretory protein of 94 amino acids （PSP94） has been shown to interact with cysteine-rich secretory protein 3 （CRISP-3） in human seminal plasma. Interestingly, PSP94 expression is redaced or lost in the majority of the prostate tumours, whereas CRISP-3 expression is upregulated in prostate cancer compared with normal prostate tissue. To obtain a better understanding of the individual roles these proteins have in prostate tumourigenesis and the functional relevance of their interaction, we ectopically expressed either PSP94 or CRISP-3 alone or PSP94 along with CRISP-3 in three prostate cell lines （PC3, WPE1-NB26 and LNCaP） and performed growth inhibition assays. Reverse transcription-polymerase chain reaction and Western blot analysis were used to screen prostate cell lines for PSP94 and CRISP-3 expression. Mammalian expression constructs for human PSP94 and CRISP-3 were also generated and the expression, localization and secretion of recombinant protein were assayed by transfection followed by Western blot analysis and immunofluorescence assay. The effect that ectopic expression of PSP94 or CRISP-3 had on cell growth was studied by clonogenic survival assay follokving transfection. To evaluate the effects of coexpression of the two proteins, stable clones of PC3 that expressed PSP94 were generated. They were subsequently transfected with a CRISP-3 expression construct and subjected to clonogenic survival assay. Our results showed that PSP94 and CRISP-3 could each induce growth inhibition in a cell line specific manner. Although the growth of CRISP-3-positive cell lines was inhibited by PSP94, growth inhibition mediated by CRISP-3 was not affected by the presence or absence of PSP94. This suggests that CRISP-3 may participate in PSP94-independent activities during prostate tumourigenesis.
文摘The microstructure, compressive properties at different temperatures and hardness of NiAl-Cr（Mo）-Nb alloy prepared by injection casting were investigated. Compared with the conventionally-cast alloy, the injection-cast alloy exhibits a fine microstructure, i.e. the fine eutectic cell and interlamellar spacing as well as fine primary NiAl phase and NbCr2-type Laves phase due to the high cooling rate. In addition, the area fraction of eutectic cell increases due to the narrow intercellular zone. The Vickers hardness of injection-cast alloy is markedly enhanced. The ductility and strength at room temperature are increased by 88% and 30% compared with those of conventionally-cast alloy respectively. However, the high-temperature strength of injection-cast alloy is not improved markedly. The elevated temperature compression deformation behavior can be properly described by power-law equations.
基金Projects(50572078, 20571059) supported by the National Natural Science Foundation of China
文摘A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction, scanning electron microscope, and microwave dielectric properties measurements. These samples were identified as single phase and adopted A4B3O12-type cation-deficient hexagonal perovskite structure, which can be described as consisting of identical perovskite-like blocks, three corner-sharing BO6 octahedra thick, separated by layers of vacant octahedral. These ceramics have high dielectric constants in the range of 48-42, high quality factors (Q×f) up to 38 000 GHz, and low temperature coefficient of resonant frequencies (τf) in the range of (-40-+6)×10-6℃-1. With increasing content of La and Ti, the dielectric constants slightly decrease butτf gradually increases.
文摘The corrosion resistance of Zr-1Nb alloy was compared with that of Zr-Sn-Nb-Fe and Zr-4 alloys, and the effect of hydrochemistry on the corrosion resistance of Zr-1Nb alloy was discussed. Experimental results show that niobium oxide is partly soluble in LiOH aqueous solution. Therefore, when Zr-1Nb alloy is corroded in LiOH aqueous solution, a soluble niobate produced by the reaction between the corrosion products of beta -Nb particles and LiOH results in the formation of pores in the zirconium oxide films and causes the degradation of the corrosion resistance of Zr-1Nb alloy tested in LiOH aqueous solution.
基金Funded by Grant-in-Aid Project (No. 95-04) of International Centre for Diffraction Data.
文摘A new niabate Sr6Ti7Nb9O42 was synthesized for the first time by solid state reaction in SrO-TiO2-Nb2O5 ternary system. The new compound was characterized by EPMA, XRD, SEM and DTA. The X-ray powder diffraction data of Sr6Ti7Nb9O42 were firstly reported in the paper. Sr6Ti7Nb9O42 crystallizes the hexagonal system with unit cell parameters a=8.9991(4) A,c= 11.5118(9)A. and space group P6/mcm (193), z=1. The calculated and measured densities are 4. 783 g/cm3 and 4. 764 g/cm3, respectively.
