By using Fura-2/AM, the effects of magnesium (Mg 2+) on the glutamate-induced increase of intracellular free calcium ([Ca 2+]i) in the cultured hippocampal neurons and the features were investigated by integrated ph...By using Fura-2/AM, the effects of magnesium (Mg 2+) on the glutamate-induced increase of intracellular free calcium ([Ca 2+]i) in the cultured hippocampal neurons and the features were investigated by integrated photoelectric detecting system. The experiments were designed to three groups (The drug was spit to the cells for 20 s): Group A receiving 1×10 —5 mol/L glutamate; Group B receiving 1×10 —5 mol/L glutamate and1×10 —5 mol/L Mg 2+ simultaneously; Group C receiving 1×10 —5 mol/L glutamate again after [Ca 2+]i in group B back to the baseline. The results showed that in group A, [Ca 2+]i was obviously increased. In group B, the changes in [Ca 2+]i and the peak value were significantly decreased. Moreover, the elevation of Phase 1 was slowed down and Phase 2 was shortened to some extent, and the plateau phase between them was relatively prolonged. In group C, calcium oscillation similar to that in group A occurred, but both the Phase 1 and Phase 2 were shortened and the △[Ca 2+]i was slightly decreased. It was suggested that Mg 2+ could quickly inhibit the rise of [Ca 2+]i induced by glutamate in the cultured hippocampal neurons in rats.展开更多
The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells： one using MgZr4（PO4）6 （MZP） as the solid electrolyte and the other using...The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells： one using MgZr4（PO4）6 （MZP） as the solid electrolyte and the other using CaF2 as the solid electrolyte. The first cell was operated in the range of 950 to 1100 K. The second cell was operated in the range of 1125 to 1200 K. The reversibility of the cell EMFs was confirmed by microcoulometric titration. The Gibbs energy changes of magnesium ferrite relative to component oxides were calculated based on EMF measurements and are given by following expressions, respectively： AG1 = -3579-15 T （J/mol） and AGⅡ =6258-24.3 T （J/mol）. The results obtained from two different cells are consistent with each other. The results also are in agreement with Rao＇ s and Tretjakov＇s data in the measured temperature range. When the Gibbs free energies of formation of MgO and Fe203 were substituted in the reaction, the Gibbs free energies of formation of MgFe204 was obtained in two temperature ranges and the for mations are shown as follows： AG 1Formation =-1427394＋360.5 T （J/mol） and AGⅡ Formition =-1417557＋351.2 T （J/mol）.展开更多
Compact anodic films with high hardness and good corrosion resistance on magnesium alloys were prepared by a new constant voltage and arc-free anodizing process. The effects of anodizing parameters such as applied vol...Compact anodic films with high hardness and good corrosion resistance on magnesium alloys were prepared by a new constant voltage and arc-free anodizing process. The effects of anodizing parameters such as applied voltage and electrolyte temperature on the peak current density and the thickness of films were investigated. In addition, the morphologies and corrosion resistance of films were investigated by scanning electron microscopy and potentiodynamic polarization, respectively. The results show that the higher the applied voltage, the higher the peak current density and the thicker the films. However, too high applied voltage may result in breakdown of films and intense sparking which may deteriorate the properties of the anodic films and bring about unsafety. The new anodizing process can be applied in a wide range of temperature. The new anodic films have numbers of pores with the diameter of 0.55.0μm which do not transverse the entire film.展开更多
Anodization of AZ91D magnesium alloy in the electrolyte solution of 0.5 mol/L of sodium silicate and 1.0 mol/L of potassium fluoride was investigated. The anodic films were characterized using optical microscopy （OM...Anodization of AZ91D magnesium alloy in the electrolyte solution of 0.5 mol/L of sodium silicate and 1.0 mol/L of potassium fluoride was investigated. The anodic films were characterized using optical microscopy （OM）, scanning electron microscopy （SEM）, and X-ray diffraction （XRD）. The corrosion resistance of the various anodized alloys was evaluated by a fast corrosion test using the solution of hydrochloric acid and potassium dichromate. The results showed that the addition of KF resulted in the presence of NaF in the anodic film. The thickness of the anodic film formed under a constant current density of 20 mA/cm^2 for 16 rain at 60℃ exceeded 100 gm. The growth of the anodic film could be divided into three stages based on the anodizing time; the growth rate was much faster during stage Ⅱ than in stages I and Ⅲ. The anodic film exhibited the highest corrosion resistance for the AZ91 alloy, which is attributed to the fact that the anodization was maintained until the end of stage Ⅱ.展开更多
An organic-magnesium complex conversion(OMCC)coating on AZ91D magnesium alloy was obtained by treating in a solution containing organic compounds.SEM,FESEM and XPS were used to examine the surface morphology,thickness...An organic-magnesium complex conversion(OMCC)coating on AZ91D magnesium alloy was obtained by treating in a solution containing organic compounds.SEM,FESEM and XPS were used to examine the surface morphology,thickness and structure of the conversion coatings.The results show that the continuous and uniform conversion coating is deposited on AZ91D alloy and the main component of the coatings is organic compound containing benzene ring,which forms a chemical bond with magnesium.The polarization measurement and salt spray test show that the corrosion resistance of the conversion coating is much higher than that of traditional chromate conversion coating.展开更多
Corrosion of magnesium alloys is an important issue for their applications in automobile and aerospace industry. pH values as a function of time in two types of simulated occluded corrosion cells(OCC) for magnesium al...Corrosion of magnesium alloys is an important issue for their applications in automobile and aerospace industry. pH values as a function of time in two types of simulated occluded corrosion cells(OCC) for magnesium alloys AZ80 and AM60 were measured. The influence of mass ratio of solution to material or liquid to solid ratio(L/S ratio),initial pH value and chemical compositions of solutions on pH value in OCC was discussed. The experimental results show that pH value for magnesium alloys increases gradually or rapidly in Occ,depending on L/S ratio,initial pH value of solution and chloride ions concentration etc,and then reaches up to 10.5-10.6 and finally stabilizes at the level. The onset in the pH value time curve corresponds to the precipitate of magnesium hydroxide according to the theoretical calculation.展开更多
The model of this test was set up according to Langendoff isolated heart reperfusion mechanics. The experimental research was designed to observe the protective effects on ischemic andreperfuslon myocardial tissue by ...The model of this test was set up according to Langendoff isolated heart reperfusion mechanics. The experimental research was designed to observe the protective effects on ischemic andreperfuslon myocardial tissue by using ST. Thomas cardioplegic solution containing selenium andmagnesium. We conclude that using cold crystallold cardioplegic solution containing Se'+, Mg' 4 canobviously reduce ischemic and reperfusion myocardlal injury and bas an advantage of recovering myocardial runctlon after operation by observing the content or lactic dehydrogenase (LDH); creatineI,kasphoklnase CK in the coronary vessel's sinus reflux solutlonl glutatblone peroxldase (GPX); suI,eroxlde dismutase (SOD); maloydladehyde (MDA ) I Se4+ .Mg'+ .Ca'+ and cia-nging or myocardialultrastructure.展开更多
为了满足生产低碳钢和超低碳钢的技术要求,以棕刚玉、板状刚玉、电熔镁铝尖晶石粉为原料,电熔镁砂粉和α-氧化铝微粉为添加剂,络合镁铝溶胶为结合剂,研制出了机压成型免烧刚玉-尖晶石无碳砖,并进行了实验。试验结果表明:当电熔镁砂粉和...为了满足生产低碳钢和超低碳钢的技术要求,以棕刚玉、板状刚玉、电熔镁铝尖晶石粉为原料,电熔镁砂粉和α-氧化铝微粉为添加剂,络合镁铝溶胶为结合剂,研制出了机压成型免烧刚玉-尖晶石无碳砖,并进行了实验。试验结果表明:当电熔镁砂粉和α-氧化铝微粉加入量分别为3%和8%时,试验砖的性能最佳。该砖在太钢90 t LF钢包熔池及包底部位使用,其寿命达到105炉。展开更多
文摘By using Fura-2/AM, the effects of magnesium (Mg 2+) on the glutamate-induced increase of intracellular free calcium ([Ca 2+]i) in the cultured hippocampal neurons and the features were investigated by integrated photoelectric detecting system. The experiments were designed to three groups (The drug was spit to the cells for 20 s): Group A receiving 1×10 —5 mol/L glutamate; Group B receiving 1×10 —5 mol/L glutamate and1×10 —5 mol/L Mg 2+ simultaneously; Group C receiving 1×10 —5 mol/L glutamate again after [Ca 2+]i in group B back to the baseline. The results showed that in group A, [Ca 2+]i was obviously increased. In group B, the changes in [Ca 2+]i and the peak value were significantly decreased. Moreover, the elevation of Phase 1 was slowed down and Phase 2 was shortened to some extent, and the plateau phase between them was relatively prolonged. In group C, calcium oscillation similar to that in group A occurred, but both the Phase 1 and Phase 2 were shortened and the △[Ca 2+]i was slightly decreased. It was suggested that Mg 2+ could quickly inhibit the rise of [Ca 2+]i induced by glutamate in the cultured hippocampal neurons in rats.
基金the National Natural Science Foundation of China (No.50572024) the Education Ministry Foundation for Returning Overseas Scholar of China.
文摘The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells： one using MgZr4（PO4）6 （MZP） as the solid electrolyte and the other using CaF2 as the solid electrolyte. The first cell was operated in the range of 950 to 1100 K. The second cell was operated in the range of 1125 to 1200 K. The reversibility of the cell EMFs was confirmed by microcoulometric titration. The Gibbs energy changes of magnesium ferrite relative to component oxides were calculated based on EMF measurements and are given by following expressions, respectively： AG1 = -3579-15 T （J/mol） and AGⅡ =6258-24.3 T （J/mol）. The results obtained from two different cells are consistent with each other. The results also are in agreement with Rao＇ s and Tretjakov＇s data in the measured temperature range. When the Gibbs free energies of formation of MgO and Fe203 were substituted in the reaction, the Gibbs free energies of formation of MgFe204 was obtained in two temperature ranges and the for mations are shown as follows： AG 1Formation =-1427394＋360.5 T （J/mol） and AGⅡ Formition =-1417557＋351.2 T （J/mol）.
基金Project (2002107) supported by the Natural Science Foundation of Hunan Province project(2005-241) supported by theScience Project of Changsha
文摘Compact anodic films with high hardness and good corrosion resistance on magnesium alloys were prepared by a new constant voltage and arc-free anodizing process. The effects of anodizing parameters such as applied voltage and electrolyte temperature on the peak current density and the thickness of films were investigated. In addition, the morphologies and corrosion resistance of films were investigated by scanning electron microscopy and potentiodynamic polarization, respectively. The results show that the higher the applied voltage, the higher the peak current density and the thicker the films. However, too high applied voltage may result in breakdown of films and intense sparking which may deteriorate the properties of the anodic films and bring about unsafety. The new anodizing process can be applied in a wide range of temperature. The new anodic films have numbers of pores with the diameter of 0.55.0μm which do not transverse the entire film.
基金The work was financially supported by the National Natural Science Foundation of China (No.50541003) and the Aeronautic ScienceFoundation of China (No.04H51002).
文摘Anodization of AZ91D magnesium alloy in the electrolyte solution of 0.5 mol/L of sodium silicate and 1.0 mol/L of potassium fluoride was investigated. The anodic films were characterized using optical microscopy （OM）, scanning electron microscopy （SEM）, and X-ray diffraction （XRD）. The corrosion resistance of the various anodized alloys was evaluated by a fast corrosion test using the solution of hydrochloric acid and potassium dichromate. The results showed that the addition of KF resulted in the presence of NaF in the anodic film. The thickness of the anodic film formed under a constant current density of 20 mA/cm^2 for 16 rain at 60℃ exceeded 100 gm. The growth of the anodic film could be divided into three stages based on the anodizing time; the growth rate was much faster during stage Ⅱ than in stages I and Ⅲ. The anodic film exhibited the highest corrosion resistance for the AZ91 alloy, which is attributed to the fact that the anodization was maintained until the end of stage Ⅱ.
基金Project(50871046)supported by the National Natural Science Foundation of ChinaProject(2007KZ09)supported by the 2007 Scienceand Technology Support Plan of Changchun City,China
文摘An organic-magnesium complex conversion(OMCC)coating on AZ91D magnesium alloy was obtained by treating in a solution containing organic compounds.SEM,FESEM and XPS were used to examine the surface morphology,thickness and structure of the conversion coatings.The results show that the continuous and uniform conversion coating is deposited on AZ91D alloy and the main component of the coatings is organic compound containing benzene ring,which forms a chemical bond with magnesium.The polarization measurement and salt spray test show that the corrosion resistance of the conversion coating is much higher than that of traditional chromate conversion coating.
基金Projects (200413BA4002, 8655) supported by the Natural Science Foundation of Chongqing Municipal Science Commission, ChinaProject (KJ050604) supported by the Technology Commission and the Science and Technology foundation of Chongqing Municipal Education Commission, China
文摘Corrosion of magnesium alloys is an important issue for their applications in automobile and aerospace industry. pH values as a function of time in two types of simulated occluded corrosion cells(OCC) for magnesium alloys AZ80 and AM60 were measured. The influence of mass ratio of solution to material or liquid to solid ratio(L/S ratio),initial pH value and chemical compositions of solutions on pH value in OCC was discussed. The experimental results show that pH value for magnesium alloys increases gradually or rapidly in Occ,depending on L/S ratio,initial pH value of solution and chloride ions concentration etc,and then reaches up to 10.5-10.6 and finally stabilizes at the level. The onset in the pH value time curve corresponds to the precipitate of magnesium hydroxide according to the theoretical calculation.
文摘The model of this test was set up according to Langendoff isolated heart reperfusion mechanics. The experimental research was designed to observe the protective effects on ischemic andreperfuslon myocardial tissue by using ST. Thomas cardioplegic solution containing selenium andmagnesium. We conclude that using cold crystallold cardioplegic solution containing Se'+, Mg' 4 canobviously reduce ischemic and reperfusion myocardlal injury and bas an advantage of recovering myocardial runctlon after operation by observing the content or lactic dehydrogenase (LDH); creatineI,kasphoklnase CK in the coronary vessel's sinus reflux solutlonl glutatblone peroxldase (GPX); suI,eroxlde dismutase (SOD); maloydladehyde (MDA ) I Se4+ .Mg'+ .Ca'+ and cia-nging or myocardialultrastructure.
文摘为了满足生产低碳钢和超低碳钢的技术要求,以棕刚玉、板状刚玉、电熔镁铝尖晶石粉为原料,电熔镁砂粉和α-氧化铝微粉为添加剂,络合镁铝溶胶为结合剂,研制出了机压成型免烧刚玉-尖晶石无碳砖,并进行了实验。试验结果表明:当电熔镁砂粉和α-氧化铝微粉加入量分别为3%和8%时,试验砖的性能最佳。该砖在太钢90 t LF钢包熔池及包底部位使用,其寿命达到105炉。
