Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observe...Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions. Furthermore, the formation and change of the nonmetallic inclusion characteristics of finished steel sheets after the RE treatment were discussed. The results have shown that in the present work,the suitable RE metal additions are 0.6 -0.9 kg/t steel. After the suitable RE treatment,the formation of AIN and MnS inclusions were restrained, and the aggregation, flotation and removal of nonmetallic inclusions were efficiently promoted and the cleanliness of liquid steel was significantly increased. Meanwhile, the total oxygen concentration reached the minimum value and thle desulfurization efficiency was optimal ,and the type of main inclusions was approximately spherical or elliptical spherical RE radicle inclusions whose size was relatively large.展开更多
The mechanical properties and stress corrosion cracking (SCC) resistance of an Al-Zn-Cu-Mg-Sc-Zr alloy under different aging conditions were investigated. The dependence of microstructure and mechanical properties on ...The mechanical properties and stress corrosion cracking (SCC) resistance of an Al-Zn-Cu-Mg-Sc-Zr alloy under different aging conditions were investigated. The dependence of microstructure and mechanical properties on aging parameters was evaluated by tensile test, hardness test and conductivity measurement. The results show that for the alloys with retrogression and re-aging treatment (RRA), the conductivity increases with the retrogression time and temperature, while the tensile strength decreases. The transmission electron microscopy (TEM) results show that the precipitates η(MgZn2) at grain boundary aggregate apparently with retrogression time and the precipitates inside the matrix exhibit the similar distribution to T6 temper, which comprises fine GP zones, large η′(MgZn2) and η(MgZn2) phases. According to the mechanical properties and microstructure observations, the optimal RRA regime is recommended to be 120 °C, 24 h + 180 °C, 30 min + 120 °C, 24 h. The strength level of the alloy after the optimum RRA treatment is similar to that in T6 condition and the SCC resistance is improved obviously in contrast to T6 condition.展开更多
Mg-9Al-xRE magnesium alloys were studied, where, x is 0, 0.4. 0.8. 1.2 and 1.6% (in weight percent, wt%), respectively. Influence of rare earths (RE) on micro structure. and strength in both T4 (solute heat treatment)...Mg-9Al-xRE magnesium alloys were studied, where, x is 0, 0.4. 0.8. 1.2 and 1.6% (in weight percent, wt%), respectively. Influence of rare earths (RE) on micro structure. and strength in both T4 (solute heat treatment) and T6 (solute heat treatment and artificial ageing treatment) were investigated. Strength of specimen was tested at ambient temperature. The micro structure was analyzed by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction analysis. RE additions improved T4 tensile strength of the treated alloys. Small addition (0.4wt%) of RE greatly improved the strength of ageing treated (T6) Mg-9Al alloy, but further additions caused decreasing.展开更多
AIM:To evaluate the safety and efficacy of vitamin E in children with chronic hepatitis B.METHODS:We randomly assigned patients with chronic hepatitis B,positive for hepatitis B e antigen(HBeAg),to receive either vita...AIM:To evaluate the safety and efficacy of vitamin E in children with chronic hepatitis B.METHODS:We randomly assigned patients with chronic hepatitis B,positive for hepatitis B e antigen(HBeAg),to receive either vitamin E or placebo once daily for 6 mo in a 3:1 ratio and double-blind manner.The primary end point was HBeAg seroconversion,defined as the loss of HBeAg,undetectable levels of serum hepatitis B virus DNA,and the appearance of antibodies against HBeAg 12 mo after therapy.RESULTS:At baseline visit,49 patients had normal and 43 had increased serum aminotransferase levels.Twenty-nine patients did not respond to previous treatment with interferon-α or lamivudine.Seventy-six children completed the study;16 were non-compliant(n = 7),lost to follow-up(n = 7),or started another antiviral treatment(n = 3).Intention-to-treat analysis showed HBeAg seroconversion in 16 children(23.2%) treated with vitamin E and two(8.7%) in the placebo group(P = 0.13).Vitamin E was well tolerated.CONCLUSION:There is only a tendency that vitamin E may promote HBeAg seroconversion.Therefore larger studies are needed to clarify the role of antioxidants in the therapy of chronic hepatitis B.展开更多
Drug susceptibility testing (DST) plays a pivotal role in TB patients’ management leading to the selection of most effective drugs. This study aimed to determine resistance patterns to first line anti-TB drugs in Myc...Drug susceptibility testing (DST) plays a pivotal role in TB patients’ management leading to the selection of most effective drugs. This study aimed to determine resistance patterns to first line anti-TB drugs in Mycobacterium tuberculosis isolates from re-treated patients from Sudan. A total of 239 sputum specimens were collected from smear positive re-treatment TB patients during the period from July 2009 to July 2010. Specimens were pre-treated according to Petroff method. The recovered isolates were tested for sensitivity to first line anti-TB drugs by the 1% proportion method. One hundred and forty three (143/239, 59.8%) mycobacterial isolates were successfully recovered. The majority (98.6%, 141/143) of the isolates were Mycobacterium tuberculosis complex strains. Two strains (2/143, 1.4%) were identified as RIF/INH-resistant MOTT, while fifty four isolates (38.3%, 54/141) were MDR. Multi- drug resistant Mycobacterium tuberculosis complex (MDR-TB) among re-treatment patients from national referral centers for tuberculosis diagnosis and management was considerably high in the study isolates.展开更多
The effects of heat treatment on the Cu-Zn-Al shape memory alloys with mixed REwere researched with the help of X-ray diffraction and transmission electron micro-scope (TEM).The results show that the shape memory allo...The effects of heat treatment on the Cu-Zn-Al shape memory alloys with mixed REwere researched with the help of X-ray diffraction and transmission electron micro-scope (TEM).The results show that the shape memory alloys with martensite can beproduced by adding mixed RE and heat treatment processes holding at 820C -880Cfor 15min,quenching into oil,aging at 150C for 15min,and then holding in waterat 50C for 10min.The alloys have the lowest transformation thermal hysteresis.Among the four experimental heat treatment processes the gradationally quenchingmakes the alloy have the highest transformation temperature and quenching into oilor water at room temperature makes the alloy have the largest thermal hysteresis.Mi-crostructure examination shows that aging at 2000C could destroy the substructuresin lathy martensites in the alloy and form a lot of dislocations,and aging at 250℃could cause the bainite transformation in the alloy.展开更多
After different heat treatment processes, the metal compound, the microstructure and the hardness of the C-Cr-W- Mo-V-RE Fe-based hardfacing layers are investigated by means of metallographic microscope, X-ray diffrac...After different heat treatment processes, the metal compound, the microstructure and the hardness of the C-Cr-W- Mo-V-RE Fe-based hardfacing layers are investigated by means of metallographic microscope, X-ray diffraction （ XRD ）, energy dispersive spectrum（ EDS ）, transmission electron microscope（TEM） and hardness tester. The results show that the hardfacing layers have higher tempering stability and secondary hardening property. After quenching at 820 ℃ ,the hardness value（ HRC37 ） and the microstructure of the layers are similar to that normalized at 820 - 1 000 ℃. The tempering stability and the hardness increases with increasing quench temperature, which is attributed to the amount of the alloy element in the matrix. These results are very helpful for improving the mechanical properties of the hardfacing layers.展开更多
文摘Based on the industrial production of non-oriented silicon steel, the rare earth （RE） treatment during the Ruhrstahl Heraeus （RH） refining process was studied. The morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions. Furthermore, the formation and change of the nonmetallic inclusion characteristics of finished steel sheets after the RE treatment were discussed. The results have shown that in the present work,the suitable RE metal additions are 0.6 -0.9 kg/t steel. After the suitable RE treatment,the formation of AIN and MnS inclusions were restrained, and the aggregation, flotation and removal of nonmetallic inclusions were efficiently promoted and the cleanliness of liquid steel was significantly increased. Meanwhile, the total oxygen concentration reached the minimum value and thle desulfurization efficiency was optimal ,and the type of main inclusions was approximately spherical or elliptical spherical RE radicle inclusions whose size was relatively large.
基金Project(2006AA03Z523) supported by the National High-tech Research and Development Program of China
文摘The mechanical properties and stress corrosion cracking (SCC) resistance of an Al-Zn-Cu-Mg-Sc-Zr alloy under different aging conditions were investigated. The dependence of microstructure and mechanical properties on aging parameters was evaluated by tensile test, hardness test and conductivity measurement. The results show that for the alloys with retrogression and re-aging treatment (RRA), the conductivity increases with the retrogression time and temperature, while the tensile strength decreases. The transmission electron microscopy (TEM) results show that the precipitates η(MgZn2) at grain boundary aggregate apparently with retrogression time and the precipitates inside the matrix exhibit the similar distribution to T6 temper, which comprises fine GP zones, large η′(MgZn2) and η(MgZn2) phases. According to the mechanical properties and microstructure observations, the optimal RRA regime is recommended to be 120 °C, 24 h + 180 °C, 30 min + 120 °C, 24 h. The strength level of the alloy after the optimum RRA treatment is similar to that in T6 condition and the SCC resistance is improved obviously in contrast to T6 condition.
文摘Mg-9Al-xRE magnesium alloys were studied, where, x is 0, 0.4. 0.8. 1.2 and 1.6% (in weight percent, wt%), respectively. Influence of rare earths (RE) on micro structure. and strength in both T4 (solute heat treatment) and T6 (solute heat treatment and artificial ageing treatment) were investigated. Strength of specimen was tested at ambient temperature. The micro structure was analyzed by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction analysis. RE additions improved T4 tensile strength of the treated alloys. Small addition (0.4wt%) of RE greatly improved the strength of ageing treated (T6) Mg-9Al alloy, but further additions caused decreasing.
文摘AIM:To evaluate the safety and efficacy of vitamin E in children with chronic hepatitis B.METHODS:We randomly assigned patients with chronic hepatitis B,positive for hepatitis B e antigen(HBeAg),to receive either vitamin E or placebo once daily for 6 mo in a 3:1 ratio and double-blind manner.The primary end point was HBeAg seroconversion,defined as the loss of HBeAg,undetectable levels of serum hepatitis B virus DNA,and the appearance of antibodies against HBeAg 12 mo after therapy.RESULTS:At baseline visit,49 patients had normal and 43 had increased serum aminotransferase levels.Twenty-nine patients did not respond to previous treatment with interferon-α or lamivudine.Seventy-six children completed the study;16 were non-compliant(n = 7),lost to follow-up(n = 7),or started another antiviral treatment(n = 3).Intention-to-treat analysis showed HBeAg seroconversion in 16 children(23.2%) treated with vitamin E and two(8.7%) in the placebo group(P = 0.13).Vitamin E was well tolerated.CONCLUSION:There is only a tendency that vitamin E may promote HBeAg seroconversion.Therefore larger studies are needed to clarify the role of antioxidants in the therapy of chronic hepatitis B.
文摘Drug susceptibility testing (DST) plays a pivotal role in TB patients’ management leading to the selection of most effective drugs. This study aimed to determine resistance patterns to first line anti-TB drugs in Mycobacterium tuberculosis isolates from re-treated patients from Sudan. A total of 239 sputum specimens were collected from smear positive re-treatment TB patients during the period from July 2009 to July 2010. Specimens were pre-treated according to Petroff method. The recovered isolates were tested for sensitivity to first line anti-TB drugs by the 1% proportion method. One hundred and forty three (143/239, 59.8%) mycobacterial isolates were successfully recovered. The majority (98.6%, 141/143) of the isolates were Mycobacterium tuberculosis complex strains. Two strains (2/143, 1.4%) were identified as RIF/INH-resistant MOTT, while fifty four isolates (38.3%, 54/141) were MDR. Multi- drug resistant Mycobacterium tuberculosis complex (MDR-TB) among re-treatment patients from national referral centers for tuberculosis diagnosis and management was considerably high in the study isolates.
文摘The effects of heat treatment on the Cu-Zn-Al shape memory alloys with mixed REwere researched with the help of X-ray diffraction and transmission electron micro-scope (TEM).The results show that the shape memory alloys with martensite can beproduced by adding mixed RE and heat treatment processes holding at 820C -880Cfor 15min,quenching into oil,aging at 150C for 15min,and then holding in waterat 50C for 10min.The alloys have the lowest transformation thermal hysteresis.Among the four experimental heat treatment processes the gradationally quenchingmakes the alloy have the highest transformation temperature and quenching into oilor water at room temperature makes the alloy have the largest thermal hysteresis.Mi-crostructure examination shows that aging at 2000C could destroy the substructuresin lathy martensites in the alloy and form a lot of dislocations,and aging at 250℃could cause the bainite transformation in the alloy.
文摘After different heat treatment processes, the metal compound, the microstructure and the hardness of the C-Cr-W- Mo-V-RE Fe-based hardfacing layers are investigated by means of metallographic microscope, X-ray diffraction （ XRD ）, energy dispersive spectrum（ EDS ）, transmission electron microscope（TEM） and hardness tester. The results show that the hardfacing layers have higher tempering stability and secondary hardening property. After quenching at 820 ℃ ,the hardness value（ HRC37 ） and the microstructure of the layers are similar to that normalized at 820 - 1 000 ℃. The tempering stability and the hardness increases with increasing quench temperature, which is attributed to the amount of the alloy element in the matrix. These results are very helpful for improving the mechanical properties of the hardfacing layers.
