Double glow plasma surface metallurgy technique was used to fabricate a Fe?Al?Cr?Nb alloyed layer onto the surface of the 45 steel. The microstructures and composition of th?eA Fl?eCr?Nb alloyed layer were analyzed by...Double glow plasma surface metallurgy technique was used to fabricate a Fe?Al?Cr?Nb alloyed layer onto the surface of the 45 steel. The microstructures and composition of th?eA Fl?eCr?Nb alloyed layer were analyzed by scanning electronic microscopy, X-ray diffraction and energy dispersive spectroscopy. The results indicate thatthe 20 μm alloyed layer is homogeneous and compact. The alloyed elements exhibit a gradient distribution along the cross section. Microhardness and nanoindentation tests imply that the surface hardness of the alloyed layer reaches HV 580, which is almost 2.8 times that of the substrate. Compared with the substrate, the alloyed layer has a much smaller displacement and a larger elastic modulus. According to the friction and wear tests at room temperature, the? FeAl?Cr?Nb alloyed layer has lower friction coefficient and less wear mass, implying that the Fe?Al?Cr?Nb alloyed layer can effectively improve the surface hardness and wear resistance of the substrate.展开更多
目的观察莫沙必利对高原缺氧大鼠小肠动力及黏膜屏障的保护作用,初步探讨其对肠道急性缺氧损害的预防作用。方法将90只SD雄性大鼠按随机数字表法分为正常对照组、高原缺氧组、高原莫沙必利组;低压氧舱模拟海拔6 000 m,氧分压(9.31±...目的观察莫沙必利对高原缺氧大鼠小肠动力及黏膜屏障的保护作用,初步探讨其对肠道急性缺氧损害的预防作用。方法将90只SD雄性大鼠按随机数字表法分为正常对照组、高原缺氧组、高原莫沙必利组;低压氧舱模拟海拔6 000 m,氧分压(9.31±0.05)kPa,氧含量(19.6±0.2)%,建立大鼠急性缺氧模型,高原莫沙必利组采用莫沙必利灌胃,3次/d,每天剂量0.27 mg/kg。分别于10、24、48、72、168 h取小肠组织。检测急性高原缺氧应激后小肠组织一氧化氮(NO)、一氧化氮合酶(NOS)的含量变化;墨汁灌胃实验计算推进距离,检测小肠动力;RT-PCR检测小肠黏膜闭锁连接蛋白1(ZO-1)mRNA的表达情况。结果与同时间段正常对照组比,高原缺氧组NO、NOS含量增高,24、48、72、168 h NO含量差异明显(P<0.05,P<0.01),48、72、168 h NOS含量差异明显(P<0.05,P<0.01);ZO-1 mRNA表达量降低,48、72、168 h差异明显(P<0.05,P<0.01);高原莫沙必利组NO、NOS含量较正常对照组增高,仅48 h NO含量增高明显(P<0.05);高原缺氧组与高原莫沙必利组(168 h除外)各时间点小肠推进距离均较正常对照组明显降低(P<0.05,P<0.01)。各时间点高原莫沙必利组NO、NOS含量较高原缺氧组降低,72 h NO,72、168 h NOS含量差异明显(P<0.05);各时间点高原莫沙必利组小肠推进距离及ZO-1 mRNA的表达量较高原缺氧组增高,48、72、168 h的小肠推进距离及72、168 hZO-1 mRNA的表达量差异明显(P<0.05)。结论莫沙必利可有效促进小肠动力,减轻高原缺氧应激引起的小肠动力障碍及肠道黏膜屏障的损伤,可用于高原缺氧肠道损害的预防。展开更多
To obtain the stable temperature field required for growing sapphire crystals, the influence of relative positions between RF coil and crucible on the performances of sapphires produced by edge-defined film-fed growth...To obtain the stable temperature field required for growing sapphire crystals, the influence of relative positions between RF coil and crucible on the performances of sapphires produced by edge-defined film-fed growth（EFG） technique was investigated. For comparison, the crucible was located at the top（case A） and the middle（case B） of the RF coil, respectively. Furthermore, the lattice integrities were studied by the double-crystal X-ray diffraction, and the dislocations were observed under the optical microscope and atomic force microscope after corroding in molten KOH at 390 ℃. The crystals in case B exhibit better lattice integrity with smaller full width at half maximum of 29.13 rad·s, while the value in case A is 45.17 rad·s. The morphologies of dislocation etch pits in both cases show typical triangular symmetry with smooth surfaces. However, the dislocation density of 2.8×104 cm-2 in case B is only half of that in case A, and the distribution is more uniform, compared to the U-shaper in case A.展开更多
基金Project(51371097)supported by the National Natural Science Foundation of ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘Double glow plasma surface metallurgy technique was used to fabricate a Fe?Al?Cr?Nb alloyed layer onto the surface of the 45 steel. The microstructures and composition of th?eA Fl?eCr?Nb alloyed layer were analyzed by scanning electronic microscopy, X-ray diffraction and energy dispersive spectroscopy. The results indicate thatthe 20 μm alloyed layer is homogeneous and compact. The alloyed elements exhibit a gradient distribution along the cross section. Microhardness and nanoindentation tests imply that the surface hardness of the alloyed layer reaches HV 580, which is almost 2.8 times that of the substrate. Compared with the substrate, the alloyed layer has a much smaller displacement and a larger elastic modulus. According to the friction and wear tests at room temperature, the? FeAl?Cr?Nb alloyed layer has lower friction coefficient and less wear mass, implying that the Fe?Al?Cr?Nb alloyed layer can effectively improve the surface hardness and wear resistance of the substrate.
文摘目的观察莫沙必利对高原缺氧大鼠小肠动力及黏膜屏障的保护作用,初步探讨其对肠道急性缺氧损害的预防作用。方法将90只SD雄性大鼠按随机数字表法分为正常对照组、高原缺氧组、高原莫沙必利组;低压氧舱模拟海拔6 000 m,氧分压(9.31±0.05)kPa,氧含量(19.6±0.2)%,建立大鼠急性缺氧模型,高原莫沙必利组采用莫沙必利灌胃,3次/d,每天剂量0.27 mg/kg。分别于10、24、48、72、168 h取小肠组织。检测急性高原缺氧应激后小肠组织一氧化氮(NO)、一氧化氮合酶(NOS)的含量变化;墨汁灌胃实验计算推进距离,检测小肠动力;RT-PCR检测小肠黏膜闭锁连接蛋白1(ZO-1)mRNA的表达情况。结果与同时间段正常对照组比,高原缺氧组NO、NOS含量增高,24、48、72、168 h NO含量差异明显(P<0.05,P<0.01),48、72、168 h NOS含量差异明显(P<0.05,P<0.01);ZO-1 mRNA表达量降低,48、72、168 h差异明显(P<0.05,P<0.01);高原莫沙必利组NO、NOS含量较正常对照组增高,仅48 h NO含量增高明显(P<0.05);高原缺氧组与高原莫沙必利组(168 h除外)各时间点小肠推进距离均较正常对照组明显降低(P<0.05,P<0.01)。各时间点高原莫沙必利组NO、NOS含量较高原缺氧组降低,72 h NO,72、168 h NOS含量差异明显(P<0.05);各时间点高原莫沙必利组小肠推进距离及ZO-1 mRNA的表达量较高原缺氧组增高,48、72、168 h的小肠推进距离及72、168 hZO-1 mRNA的表达量差异明显(P<0.05)。结论莫沙必利可有效促进小肠动力,减轻高原缺氧应激引起的小肠动力障碍及肠道黏膜屏障的损伤,可用于高原缺氧肠道损害的预防。
基金Project(BA2012049)supported by the Special Fund of Jiangsu Province for the Transformation of Scientific and Technological Achievements,China
文摘To obtain the stable temperature field required for growing sapphire crystals, the influence of relative positions between RF coil and crucible on the performances of sapphires produced by edge-defined film-fed growth（EFG） technique was investigated. For comparison, the crucible was located at the top（case A） and the middle（case B） of the RF coil, respectively. Furthermore, the lattice integrities were studied by the double-crystal X-ray diffraction, and the dislocations were observed under the optical microscope and atomic force microscope after corroding in molten KOH at 390 ℃. The crystals in case B exhibit better lattice integrity with smaller full width at half maximum of 29.13 rad·s, while the value in case A is 45.17 rad·s. The morphologies of dislocation etch pits in both cases show typical triangular symmetry with smooth surfaces. However, the dislocation density of 2.8×104 cm-2 in case B is only half of that in case A, and the distribution is more uniform, compared to the U-shaper in case A.
