Pre-compression and heat treatment were performed on an extruded AZ31 Mg alloy,and their effects on subsequent deformation behavior were investigated.The results show that at low temperature annealing(170 ℃ for 4 h),...Pre-compression and heat treatment were performed on an extruded AZ31 Mg alloy,and their effects on subsequent deformation behavior were investigated.The results show that at low temperature annealing(170 ℃ for 4 h),the extruded samples with and without annealing exhibit a nearly equivalent yield stress(~148 MPa) because their microstructures are nearly unchanged.However,under the same annealing condition,the yield stress of sample with pre-twinning and subsequent annealing(~225 MPa) is higher than that of the pre-twinned one(~200 MPa).The former sample presents a hardening effect because the solute atoms segregated on twin boundaries lead to a strengthening effect.The pre-twinned sample annealed at 400 ℃ for 1 h shows a higher ultimate elongation(~28%) than the pre-twinned one(~15%),but its yield stress(~125 MPa) is much lower than that of the pre-twinned one(~200 MPa).展开更多
Carbonaceous gold mines are important refractory gold ores. The previous results demonstrate that the carbonaceous matter is mainly composed of elemental carbon, organic acid and hydrocarbons. The dissolved aurocyanid...Carbonaceous gold mines are important refractory gold ores. The previous results demonstrate that the carbonaceous matter is mainly composed of elemental carbon, organic acid and hydrocarbons. The dissolved aurocyanide complex is robbed by adsorption of carbonaceous matter, which is similar to activated carbon in cyanide leaching of gold. The pretreatment methods of carbonaceous gold ores were introduced, including high temperature roasting, bio-oxidation, chemical oxidation, competitive adsorption, barrier inhibition and microwave roasting. Recently, bio-oxidation was developed rapidly due to its advantages such as mild conditions, simple processes, low energy consumption and friendly environment. The known microorganisms related with bio-oxidation pretreatment mainly are chemolithotroph bacteria such as Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. The researches on decomposing and passivating carbonaceous matter were commenced by Phanerochaete chrysosporium, Pseudomonadaceae and Streptomyces setonii. Finally, the main problems were analyzed and the application prospect of this technique was looked forward.展开更多
The electrochemical treatment of COD contained in biologically pretreated coking wastewater treated by a three-dimensional electrode system with modified coke as the particle electrode was investigated. And the electr...The electrochemical treatment of COD contained in biologically pretreated coking wastewater treated by a three-dimensional electrode system with modified coke as the particle electrode was investigated. And the electrochemical perromance of the coke modified with various active components was studied. The results show that the coke modified with Fe（NO3）2 has the lowest energy consumption and higher COD removal rate under the same condition, and the modified coke has better surface characteristics for the purpose of this study. In addition, the kinetic constant was also calculated. The study shows that the three-dimensional electrode system with Fe （NO3）z-modified coke can give a satisfactory solution in biologically pretreated coking wastewater.展开更多
In this work, different flotation–preoxidation–cyanidation methods are considered for treating a lowgrade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1%of total Sb a...In this work, different flotation–preoxidation–cyanidation methods are considered for treating a lowgrade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1%of total Sb and As, respectively, remained in the final tailings and only about 28% of the total Au remained for further cyanidation processes. On the other hand, in bulk method of flotation the maximum Au recovery of 90.6% achieved after 60 min of flotation at the grind size with K80 of 146 micron. In addition, the bulk flotation method resulted in the concentrate with low concentrations of Sb and As elements. To improve the recovery of low-grade refractory gold ores, flotation should be followed by roasting, biological, or pressure oxidation processes so that the gold could be liberated prior to cyanidation processes. It is also found that the pressure oxidation pre-treatment of the concentrates prior to cyanidation may yield high gold recoveries of over than 83%. In these processes, recoveries are controlled by the temperature and the oxygen partial pressure in the solvent. However, by utilizing the bio-oxidation technique, the oxidation of sulfur to sulfate cannot be completed and, consequently, the gold recovery may be limited to only 72.2%.展开更多
Objective: To study the pretreatment effect of adenosine on NF κB nuclear activity in ischemia/reperfusion myocardium in rats. Methods: Eighteen healthy male S D rats were randomly divided into three groups. Group I ...Objective: To study the pretreatment effect of adenosine on NF κB nuclear activity in ischemia/reperfusion myocardium in rats. Methods: Eighteen healthy male S D rats were randomly divided into three groups. Group I was the control group. The other two groups were subjected to 30 minutes of ischemia, followed by 2 hours of reperfusion. In group III, adenosine was given 40 μg·kg -1 ·min -1 30 minutes before coronary artery occlusion. The NF κB in nuclear was extracted and measured with western blot analysis. TNF α levels in myocardium were measured with enzyme linked immunosorbent assay (ELISA) system. All the data were recorded with mean±SEM, differences at the 95% confidence level were considered significant. Results: NF κB activity in the nucleus significantly increased after ischemia/reperfusion and TNF α levels changed. Adenosine significantly inhibited NF κB activity in nucleus, and concomitantly decreased the level of TNF α in myocardium. Conclusions: Adenosine modulation of NF κB activation may be the cellular molecular mechanism of decreasing of TNF a. The cardioprotective action of adenosine may be involved in the differential modulation of NF κB activation during myocardial ischemia/reperfusion.展开更多
基金Project(XDJK2013C106)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(51201140)supported by the National Natural Science Foundation of China
文摘Pre-compression and heat treatment were performed on an extruded AZ31 Mg alloy,and their effects on subsequent deformation behavior were investigated.The results show that at low temperature annealing(170 ℃ for 4 h),the extruded samples with and without annealing exhibit a nearly equivalent yield stress(~148 MPa) because their microstructures are nearly unchanged.However,under the same annealing condition,the yield stress of sample with pre-twinning and subsequent annealing(~225 MPa) is higher than that of the pre-twinned one(~200 MPa).The former sample presents a hardening effect because the solute atoms segregated on twin boundaries lead to a strengthening effect.The pre-twinned sample annealed at 400 ℃ for 1 h shows a higher ultimate elongation(~28%) than the pre-twinned one(~15%),but its yield stress(~125 MPa) is much lower than that of the pre-twinned one(~200 MPa).
基金Projects(51174062,51104036)supported by the National Natural Science Foundation of ChinaProject(2012BAE06B05)supported by the National Science and Technology Support Program of China during the 12th Five-Year Plan Period+1 种基金Projects(2012AA061502,2012AA061501)supported by the National High-Tech Research and Development Program of ChinaProjects(N120602006,N110302002,N110602005)supported by Fundamental Research Funds for the Central Universities of China
文摘Carbonaceous gold mines are important refractory gold ores. The previous results demonstrate that the carbonaceous matter is mainly composed of elemental carbon, organic acid and hydrocarbons. The dissolved aurocyanide complex is robbed by adsorption of carbonaceous matter, which is similar to activated carbon in cyanide leaching of gold. The pretreatment methods of carbonaceous gold ores were introduced, including high temperature roasting, bio-oxidation, chemical oxidation, competitive adsorption, barrier inhibition and microwave roasting. Recently, bio-oxidation was developed rapidly due to its advantages such as mild conditions, simple processes, low energy consumption and friendly environment. The known microorganisms related with bio-oxidation pretreatment mainly are chemolithotroph bacteria such as Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. The researches on decomposing and passivating carbonaceous matter were commenced by Phanerochaete chrysosporium, Pseudomonadaceae and Streptomyces setonii. Finally, the main problems were analyzed and the application prospect of this technique was looked forward.
文摘The electrochemical treatment of COD contained in biologically pretreated coking wastewater treated by a three-dimensional electrode system with modified coke as the particle electrode was investigated. And the electrochemical perromance of the coke modified with various active components was studied. The results show that the coke modified with Fe（NO3）2 has the lowest energy consumption and higher COD removal rate under the same condition, and the modified coke has better surface characteristics for the purpose of this study. In addition, the kinetic constant was also calculated. The study shows that the three-dimensional electrode system with Fe （NO3）z-modified coke can give a satisfactory solution in biologically pretreated coking wastewater.
文摘In this work, different flotation–preoxidation–cyanidation methods are considered for treating a lowgrade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1%of total Sb and As, respectively, remained in the final tailings and only about 28% of the total Au remained for further cyanidation processes. On the other hand, in bulk method of flotation the maximum Au recovery of 90.6% achieved after 60 min of flotation at the grind size with K80 of 146 micron. In addition, the bulk flotation method resulted in the concentrate with low concentrations of Sb and As elements. To improve the recovery of low-grade refractory gold ores, flotation should be followed by roasting, biological, or pressure oxidation processes so that the gold could be liberated prior to cyanidation processes. It is also found that the pressure oxidation pre-treatment of the concentrates prior to cyanidation may yield high gold recoveries of over than 83%. In these processes, recoveries are controlled by the temperature and the oxygen partial pressure in the solvent. However, by utilizing the bio-oxidation technique, the oxidation of sulfur to sulfate cannot be completed and, consequently, the gold recovery may be limited to only 72.2%.
文摘Objective: To study the pretreatment effect of adenosine on NF κB nuclear activity in ischemia/reperfusion myocardium in rats. Methods: Eighteen healthy male S D rats were randomly divided into three groups. Group I was the control group. The other two groups were subjected to 30 minutes of ischemia, followed by 2 hours of reperfusion. In group III, adenosine was given 40 μg·kg -1 ·min -1 30 minutes before coronary artery occlusion. The NF κB in nuclear was extracted and measured with western blot analysis. TNF α levels in myocardium were measured with enzyme linked immunosorbent assay (ELISA) system. All the data were recorded with mean±SEM, differences at the 95% confidence level were considered significant. Results: NF κB activity in the nucleus significantly increased after ischemia/reperfusion and TNF α levels changed. Adenosine significantly inhibited NF κB activity in nucleus, and concomitantly decreased the level of TNF α in myocardium. Conclusions: Adenosine modulation of NF κB activation may be the cellular molecular mechanism of decreasing of TNF a. The cardioprotective action of adenosine may be involved in the differential modulation of NF κB activation during myocardial ischemia/reperfusion.
