Ti_(2)AlC,a MAX phase ceramic,has an attractive self-healing ability to restore performance via the oxidation-induced crack healing mechanism upon healing at high temperatures in air(high oxygen partial pressures).How...Ti_(2)AlC,a MAX phase ceramic,has an attractive self-healing ability to restore performance via the oxidation-induced crack healing mechanism upon healing at high temperatures in air(high oxygen partial pressures).However,such healing ability to repair damages in vacuum or low oxygen partial pressure conditions remains unknown.Here,we report on the self-healing behavior of Ti_(2)AlC at a low oxygen partial pressure of about 1 Pa.The experimental results showed that the strength recovery depends on both healing temperature and time.After healing at 1400℃for 1–4 h,the healed samples exhibited the recovered strengths even exceeding the original strength of 375 MPa.The maximum recovered strength of~422 MPa was achieved in the healed Ti_(2)AlC sample after healing at 1400 for 4 h,about 13%higher than the original strength.Damages were healed by the formed℃TiCx from the decomposition of Ti_(2)AlC.The decomposition-induced crack healing as a new mechanism in the low oxygen partial pressure condition was disclosed for the MAX ceramics.The present study illustrates that key components made of Ti_(2)AlC can prolong their service life and keep their reliability during use at high temperatures in low oxygen partial pressures.展开更多
A high temperature equilibration experiment was carried out to investigate the effect of oxygen partial pres- sure on the phase equilibria and liquidus in CaO-Al2O3- FeOx system with the intermediate oxygen partial pr...A high temperature equilibration experiment was carried out to investigate the effect of oxygen partial pres- sure on the phase equilibria and liquidus in CaO-Al2O3- FeOx system with the intermediate oxygen partial pressures of 10.13 Pa and 1.01 × 10^-3 Pa. The equilibrated phases and their compositions of the quenched samples were analyzed by using SEM/EPMA （Scanning Electron Microscope/Electron Probe Micro Analysis） and XRD （X Ray Diffraction）. The phase equilibrium results include two cases, the two phase coexistence and the three-phase coexistence in the high Al2O3 region with oxygen partial pressure of either 10.13 Pa or 1.01 × 10^-3 Pa. Effects of oxygen partial pressure and temperature on the liquidus along the primary phase fields of CaO · Al2O3 and CaO · 2Al2O3 were nota hle. With the decrease of oxygen partial pressure, the liquid area expands and the liquidus of CaO · Al2O3 and CaO · 2Al2O3 primary fields moves to the Al2O3-FeOx region. On the other hand, the liquid area of CaO Al2O3-FeOx sys tem extends extremely to the high Al2O3 region with the temperature increasing from 1 400 to 1 500℃, especially at lower oxygen partial pressure. The present experiment results are in good agreement with the calculated ones by FactSage.展开更多
A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock r...A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures （OPP） and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 ° C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths （RCS） of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 ° C in high OPP to boiling water for 30 times was merely 1.61%.展开更多
目的探讨2型糖尿病绝经后女性经皮氧分压水平与骨密度(bone mineral density,BMD)的关系,进一步了解微循环对糖尿病骨密度的影响。方法本横断面研究共纳入162例绝经后2型糖尿病患者。通过双能X射线吸收测定法评估其腰椎、髋部、右侧股...目的探讨2型糖尿病绝经后女性经皮氧分压水平与骨密度(bone mineral density,BMD)的关系,进一步了解微循环对糖尿病骨密度的影响。方法本横断面研究共纳入162例绝经后2型糖尿病患者。通过双能X射线吸收测定法评估其腰椎、髋部、右侧股骨颈、Ward’s三角区、股骨大转子及转子内骨密度。根据T-Score值分为3组:骨质疏松组(T≤-2.5)、骨量减低组(-2.5<T<-1.0)和骨量正常组(T≥-1.0)。Perimed PeriFlux System 5000检测双侧膝下及足背经皮氧分压水平,经皮氧分压是微血管病变的主要检测手段。比较3组间的一般特征,应用Pearson分析骨密度与经皮氧分压之间的关联,多元逐步回归分析骨密度的影响因素。结果骨质疏松组TcPO_(2)、ABI水平低于骨量正常组(40.09 vs.47.89,1.06 vs.1.17,P<0.05)。TcPO_(2)与腰1至腰4、股骨颈、股骨大转子、转子内、总髋及Ward’s三角区BMD呈正相关,r分别为0.259、0.215、0.226、0.217、0.213、0.226。校正年龄、病程、BMI、绝经年限后,TcPO_(2)与腰椎骨密度仍呈正相关。多元逐步回归分析,TcPO_(2)、BMI和年龄是腰椎骨密度的独立影响因素,TcPO_(2)、BMI、Ca和绝经年限是股骨颈的独立影响因素。结论2型糖尿病绝经后女性骨质疏松患者TcPO_(2)、ABI降低,TcPO_(2)下降可能是糖尿病骨密度降低的独立影响因素。展开更多
Thermodynamic assessment in the ternary systems ZrO2 -CeO2 -Y2 O3, ZrO2 -CeO2 -Ce2 03 and the limiting binaries ZrO2 -Y2 O3, ZrO2 -CeO2, CeO2 -Y2 03, ZrO2 -Ce2O3, CeO2 -Ce2O3 as well as the modeling for oxides are rev...Thermodynamic assessment in the ternary systems ZrO2 -CeO2 -Y2 O3, ZrO2 -CeO2 -Ce2 03 and the limiting binaries ZrO2 -Y2 O3, ZrO2 -CeO2, CeO2 -Y2 03, ZrO2 -Ce2O3, CeO2 -Ce2O3 as well as the modeling for oxides are reviewed comprehensively. Based on the recent estimations on the YO1.5-CeO2, ZrO2-CeO2 and ZrO2 -YO1.6 systems, isothermal sections at 1273 and 1 973 K of the ternary CeO2- ZrO2-YO1.5system are calculated. In the system of ZrO2-CeO2-Ce2O3, the complex relation between the nonstoichiometry （y） in CeO2-x, the composition of the ZrO2 -CeO2 solid solution and the oxygen partial pressure （Po2 ） for different ZrO2 containing solid solutions CexZr1-xO2-x. are evaluated from 1 473 to 1 773 K. The relation between the degree of Ce^＋4 reduction to Ce.3 under different Po2 in the fluorite CeO2-xy and CexZr1-xOz-x solid solutions at different temperatures can be used as a guide in the development of functional ceramics.展开更多
For an analysis of the oxidation behavior of UO2 nuclear fuel pellet under a loss of water coolant accident in a spent nuclear fuel pool of an LWR, thermodynamic assessments of UO2 oxidation were carried out under var...For an analysis of the oxidation behavior of UO2 nuclear fuel pellet under a loss of water coolant accident in a spent nuclear fuel pool of an LWR, thermodynamic assessments of UO2 oxidation were carried out under various atmospheric conditions. In a steam atmosphere, it was assessed that UO2 would not be fully oxidized into U3O8 due to the relatively lower oxygen partial pressure, while UO2 will be fully oxidized into U3O8 in an air atmosphere. In an air and steam mixture atmosphere, the UO2 oxidation was dominantly affected by the air volumetric fraction, because of the relatively higher oxygen partial pressure of air. In addition, the effect of H2 volumetric fraction on the oxygen partial pressure under a mixture atmosphere was calculated, and it was revealed that UO2 pellet oxidation could be reduced above the critical value of H2 volumetric fraction.展开更多
Objective To explore the effects of sliding-cup with different parameters on energy metabolism in the body by observing the effect of sliding-cup along the governor vessel on transcutaneous partial pressures of oxygen...Objective To explore the effects of sliding-cup with different parameters on energy metabolism in the body by observing the effect of sliding-cup along the governor vessel on transcutaneous partial pressures of oxygen and carbon dioxide in Mìngmén（命门 GV 4） in sub-healthy people. Methods A total of 10 sub-healthy adults at rest were observed and sliding-cup along the governor vessel were conducted with three different parameters, jar-pressure of –0.01~ –0.02 MPa with sliding-cup for 5 min, jar-pressure of –0.02~ –0.03 MPa with sliding-cup for 5 min and jar-pressure of –0.02~ –0.03 MPa with slidingcup for 3 min. Peri Flux System5000 PF5040 module was employed to monitor the changes of transcutaneous partial pressures of oxygen（tcp O2） and carbon dioxide（tcp CO2） in GV 4 at 0 min, 5 min, 10 min, 15 min, 20 min, 25 min and 30 min after sliding-cup with above different interventions in sub-healthy subjects. Results After sliding-cup, tcp O2 increased at first and then decreased over time; there was no difference in tcp O2 after sliding-cupping with different parameters（all P0.05）. After sliding-cup, tcp CO2 decreased; there was no difference in tcp CO2 after sliding-cup with different parameters（all P0.05）. Conclusion Sliding-cup has a sustained effect on the body and can speed up the energy metabolism in the body.展开更多
Background:Hypoxia is a significant risk factor of hypertension.However,no studies have used transcutaneous tissue partial pressure of oxygen(TcPO_(2))and partial pressure of carbon dioxide(TcPCO_(2))monitors to measu...Background:Hypoxia is a significant risk factor of hypertension.However,no studies have used transcutaneous tissue partial pressure of oxygen(TcPO_(2))and partial pressure of carbon dioxide(TcPCO_(2))monitors to measure the respective partial pressures in healthy individuals.Oxygen saturation(SpO_(2))is often used for traditional monitoring of vital signs.This study investigated the changes in TcPO_(2)and SpO_(2)values during rapid changes in altitude.The trial was registered at ClinicalTrials.gov(registration no.NCT06076057).Methods:Healthy adult volunteers were instructed to sit vertically in a hypobaric oxygen chamber,which ascended from 0 m to 2500 m at a uniform speed within 10 min.The Danish Radiometer TCM4 was used to measure TcPO_(2)and TcPCO_(2)with the ventral side of the upper arm as the measurement site.The Shenzhen Kerokan P0D-1 W pulse oximeter was used to measure heart rate and SpO_(2),with values recorded once every 500 m.Results:Altogether,49 healthy volunteers were recruited between March 2023 and August 2023.With increasing altitude,TcPO_(2)and SpO_(2)decreased significantly(P<0.01).During the ascent from 0 m,TcPO_(2)began to change statistically at 500 m(P<0.05),whereas SpO_(2)began to change statistically at 1000 m(P<0.05).At the same altitude,the difference in TcPO_(2)was greater than the difference in SpO_(2).At 1000 m,there were statistically significant changes in TcPO_(2)and SpO_(2)(P<0.001).At altitudes>500 m,statistical significance was identified between TcPO_(2)in both sexes(P<0.05).Statistical significance in TcPCO_(2)and heart rate was observed at the different elevations(P<0.05).Conclusion:In acutely changing low-pressure hypoxic environments,TcPO_(2)changed more dramatically than SpO_(2).展开更多
基金supported by the National Natural Science Foundation of China(No.52275171)the PreResearch Program in National 14th Five-Year Plan(No.80923010304).
文摘Ti_(2)AlC,a MAX phase ceramic,has an attractive self-healing ability to restore performance via the oxidation-induced crack healing mechanism upon healing at high temperatures in air(high oxygen partial pressures).However,such healing ability to repair damages in vacuum or low oxygen partial pressure conditions remains unknown.Here,we report on the self-healing behavior of Ti_(2)AlC at a low oxygen partial pressure of about 1 Pa.The experimental results showed that the strength recovery depends on both healing temperature and time.After healing at 1400℃for 1–4 h,the healed samples exhibited the recovered strengths even exceeding the original strength of 375 MPa.The maximum recovered strength of~422 MPa was achieved in the healed Ti_(2)AlC sample after healing at 1400 for 4 h,about 13%higher than the original strength.Damages were healed by the formed℃TiCx from the decomposition of Ti_(2)AlC.The decomposition-induced crack healing as a new mechanism in the low oxygen partial pressure condition was disclosed for the MAX ceramics.The present study illustrates that key components made of Ti_(2)AlC can prolong their service life and keep their reliability during use at high temperatures in low oxygen partial pressures.
基金Item Sponsored by National Natural Science Foundation of China(50974034,51074039)
文摘A high temperature equilibration experiment was carried out to investigate the effect of oxygen partial pres- sure on the phase equilibria and liquidus in CaO-Al2O3- FeOx system with the intermediate oxygen partial pressures of 10.13 Pa and 1.01 × 10^-3 Pa. The equilibrated phases and their compositions of the quenched samples were analyzed by using SEM/EPMA （Scanning Electron Microscope/Electron Probe Micro Analysis） and XRD （X Ray Diffraction）. The phase equilibrium results include two cases, the two phase coexistence and the three-phase coexistence in the high Al2O3 region with oxygen partial pressure of either 10.13 Pa or 1.01 × 10^-3 Pa. Effects of oxygen partial pressure and temperature on the liquidus along the primary phase fields of CaO · Al2O3 and CaO · 2Al2O3 were nota hle. With the decrease of oxygen partial pressure, the liquid area expands and the liquidus of CaO · Al2O3 and CaO · 2Al2O3 primary fields moves to the Al2O3-FeOx region. On the other hand, the liquid area of CaO Al2O3-FeOx sys tem extends extremely to the high Al2O3 region with the temperature increasing from 1 400 to 1 500℃, especially at lower oxygen partial pressure. The present experiment results are in good agreement with the calculated ones by FactSage.
基金Project supported by the Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,ChinaProject(51205417)supported by the National Natural Science Foundation of China
文摘A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures （OPP） and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 ° C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths （RCS） of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 ° C in high OPP to boiling water for 30 times was merely 1.61%.
文摘目的探讨2型糖尿病绝经后女性经皮氧分压水平与骨密度(bone mineral density,BMD)的关系,进一步了解微循环对糖尿病骨密度的影响。方法本横断面研究共纳入162例绝经后2型糖尿病患者。通过双能X射线吸收测定法评估其腰椎、髋部、右侧股骨颈、Ward’s三角区、股骨大转子及转子内骨密度。根据T-Score值分为3组:骨质疏松组(T≤-2.5)、骨量减低组(-2.5<T<-1.0)和骨量正常组(T≥-1.0)。Perimed PeriFlux System 5000检测双侧膝下及足背经皮氧分压水平,经皮氧分压是微血管病变的主要检测手段。比较3组间的一般特征,应用Pearson分析骨密度与经皮氧分压之间的关联,多元逐步回归分析骨密度的影响因素。结果骨质疏松组TcPO_(2)、ABI水平低于骨量正常组(40.09 vs.47.89,1.06 vs.1.17,P<0.05)。TcPO_(2)与腰1至腰4、股骨颈、股骨大转子、转子内、总髋及Ward’s三角区BMD呈正相关,r分别为0.259、0.215、0.226、0.217、0.213、0.226。校正年龄、病程、BMI、绝经年限后,TcPO_(2)与腰椎骨密度仍呈正相关。多元逐步回归分析,TcPO_(2)、BMI和年龄是腰椎骨密度的独立影响因素,TcPO_(2)、BMI、Ca和绝经年限是股骨颈的独立影响因素。结论2型糖尿病绝经后女性骨质疏松患者TcPO_(2)、ABI降低,TcPO_(2)下降可能是糖尿病骨密度降低的独立影响因素。
文摘Thermodynamic assessment in the ternary systems ZrO2 -CeO2 -Y2 O3, ZrO2 -CeO2 -Ce2 03 and the limiting binaries ZrO2 -Y2 O3, ZrO2 -CeO2, CeO2 -Y2 03, ZrO2 -Ce2O3, CeO2 -Ce2O3 as well as the modeling for oxides are reviewed comprehensively. Based on the recent estimations on the YO1.5-CeO2, ZrO2-CeO2 and ZrO2 -YO1.6 systems, isothermal sections at 1273 and 1 973 K of the ternary CeO2- ZrO2-YO1.5system are calculated. In the system of ZrO2-CeO2-Ce2O3, the complex relation between the nonstoichiometry （y） in CeO2-x, the composition of the ZrO2 -CeO2 solid solution and the oxygen partial pressure （Po2 ） for different ZrO2 containing solid solutions CexZr1-xO2-x. are evaluated from 1 473 to 1 773 K. The relation between the degree of Ce^＋4 reduction to Ce.3 under different Po2 in the fluorite CeO2-xy and CexZr1-xOz-x solid solutions at different temperatures can be used as a guide in the development of functional ceramics.
文摘For an analysis of the oxidation behavior of UO2 nuclear fuel pellet under a loss of water coolant accident in a spent nuclear fuel pool of an LWR, thermodynamic assessments of UO2 oxidation were carried out under various atmospheric conditions. In a steam atmosphere, it was assessed that UO2 would not be fully oxidized into U3O8 due to the relatively lower oxygen partial pressure, while UO2 will be fully oxidized into U3O8 in an air atmosphere. In an air and steam mixture atmosphere, the UO2 oxidation was dominantly affected by the air volumetric fraction, because of the relatively higher oxygen partial pressure of air. In addition, the effect of H2 volumetric fraction on the oxygen partial pressure under a mixture atmosphere was calculated, and it was revealed that UO2 pellet oxidation could be reduced above the critical value of H2 volumetric fraction.
基金Suported by Tianjin Municipal Administration of Traditional Chinese Medicine:11028
文摘Objective To explore the effects of sliding-cup with different parameters on energy metabolism in the body by observing the effect of sliding-cup along the governor vessel on transcutaneous partial pressures of oxygen and carbon dioxide in Mìngmén（命门 GV 4） in sub-healthy people. Methods A total of 10 sub-healthy adults at rest were observed and sliding-cup along the governor vessel were conducted with three different parameters, jar-pressure of –0.01~ –0.02 MPa with sliding-cup for 5 min, jar-pressure of –0.02~ –0.03 MPa with sliding-cup for 5 min and jar-pressure of –0.02~ –0.03 MPa with slidingcup for 3 min. Peri Flux System5000 PF5040 module was employed to monitor the changes of transcutaneous partial pressures of oxygen（tcp O2） and carbon dioxide（tcp CO2） in GV 4 at 0 min, 5 min, 10 min, 15 min, 20 min, 25 min and 30 min after sliding-cup with above different interventions in sub-healthy subjects. Results After sliding-cup, tcp O2 increased at first and then decreased over time; there was no difference in tcp O2 after sliding-cupping with different parameters（all P0.05）. After sliding-cup, tcp CO2 decreased; there was no difference in tcp CO2 after sliding-cup with different parameters（all P0.05）. Conclusion Sliding-cup has a sustained effect on the body and can speed up the energy metabolism in the body.
基金supported by grants from Shandong Province Key R&D Program(2021CXGC011301).
文摘Background:Hypoxia is a significant risk factor of hypertension.However,no studies have used transcutaneous tissue partial pressure of oxygen(TcPO_(2))and partial pressure of carbon dioxide(TcPCO_(2))monitors to measure the respective partial pressures in healthy individuals.Oxygen saturation(SpO_(2))is often used for traditional monitoring of vital signs.This study investigated the changes in TcPO_(2)and SpO_(2)values during rapid changes in altitude.The trial was registered at ClinicalTrials.gov(registration no.NCT06076057).Methods:Healthy adult volunteers were instructed to sit vertically in a hypobaric oxygen chamber,which ascended from 0 m to 2500 m at a uniform speed within 10 min.The Danish Radiometer TCM4 was used to measure TcPO_(2)and TcPCO_(2)with the ventral side of the upper arm as the measurement site.The Shenzhen Kerokan P0D-1 W pulse oximeter was used to measure heart rate and SpO_(2),with values recorded once every 500 m.Results:Altogether,49 healthy volunteers were recruited between March 2023 and August 2023.With increasing altitude,TcPO_(2)and SpO_(2)decreased significantly(P<0.01).During the ascent from 0 m,TcPO_(2)began to change statistically at 500 m(P<0.05),whereas SpO_(2)began to change statistically at 1000 m(P<0.05).At the same altitude,the difference in TcPO_(2)was greater than the difference in SpO_(2).At 1000 m,there were statistically significant changes in TcPO_(2)and SpO_(2)(P<0.001).At altitudes>500 m,statistical significance was identified between TcPO_(2)in both sexes(P<0.05).Statistical significance in TcPCO_(2)and heart rate was observed at the different elevations(P<0.05).Conclusion:In acutely changing low-pressure hypoxic environments,TcPO_(2)changed more dramatically than SpO_(2).
