Transient liquid phase(TLP)bonding was investigated in Hastelloy-X samples with different filler metal thicknesses(20,35,50,65,and 100μm)and holding time(5,20,80,320,and 640 min)to obtain optimum bonding parameters.M...Transient liquid phase(TLP)bonding was investigated in Hastelloy-X samples with different filler metal thicknesses(20,35,50,65,and 100μm)and holding time(5,20,80,320,and 640 min)to obtain optimum bonding parameters.Microstructural evaluations using electron probe microanalysis(EPMA)and electron backscattered diffraction(EBSD)show that the central eutectic phases present in the athermally solidified zone(ASZ)are Ni_(3)B,Ni_(2)Si,and CrB,and the precipitates formed in the diffusion-affected zone(DAZ)are MoB,CrB_(2),and Mo_(2)B_(5).According to the results,decreasing the filler thickness as well as increasing the holding time helps realize the completion of isothermal solidification and reduction in the density of precipitates in the DAZ,leading to a joint with more uniform properties.Diffusion of boron and silicon to longer distances with increasing holding time causes the removal of Cr-rich borides in the DAZ and the formation of Mo-rich silicide at the joint interface.Decrease in hardness of ASZ and DAZ due to the elimination of brittle phases in these zones during long holding time causes more uniform hardness distribution in the joint area.The best results are obtained for the sample joined with the 35μm-thick filler metal for 640 min holding time.展开更多
The depositional environment of the Upper Permian quartzose sandstone （Kuishan sandstone in Shihezi Formation of Upper Permian） in the North China epicontinental basin is controversial. In order to test the previous...The depositional environment of the Upper Permian quartzose sandstone （Kuishan sandstone in Shihezi Formation of Upper Permian） in the North China epicontinental basin is controversial. In order to test the previous hypotheses, we analyzed sedimentological characteristics of the Kuishan sandstones in outcrops and boreholes, and carried out trace element geochemical analysis by electron probe microanalyzer. Three lithofacies were recognized, including normal-graded conglomerate （Cng）, trough and planar cross-bedded coarse sandstone （CStpc）, and planar cross-bedded medium sandstone （MSpc）. Normal-graded conglomerate （Cng） formed in the meandering river or deltaic distributary channels. Trough and planar cross-bedded coarse sandstone （CStpc） formed in meandering river or distributary channels of near-source deltaic plain. Planar cross-bedded medium sandstone （MSpc） formed in the siliciclastic beach with highto moderate-energy conditions. By the petrology and trace elements analysis, three relatively large-scale transgressions were revealed. Each transgression was reflected by the lower content of Ba and ratios of Fe/Mn, and the high content of B and ratios of B/Ga. The ratios of Ni/Co of all samples are all lower than 2, suggesting oxygen-enriched shallower water en- vironment during deposition of the Kuishan sandstones.展开更多
While delayed structural alterations of muscles(DSAM) induced by strenuous exercises have always been one of the commoest findings in sports-related muscle injuries, its pathogenesis remains unidentified. And although...While delayed structural alterations of muscles(DSAM) induced by strenuous exercises have always been one of the commoest findings in sports-related muscle injuries, its pathogenesis remains unidentified. And although acupuncture at Ashi points has proved its efficacy in halting the progress of DASM and speeding up its recovery, we know very little about the underlying mechanism. This paper presents our work on these problems by using amphibian DSAM models created by electrostimulation, and such research tools as electromicroscopy, enzymology, the fluores cence indicator, Fura 2, and electron probe microanalysis (EPMA). Our results indicate:1) As revealed by EPMA, cytoplasmic Ca continued to rbe,reaching 3.07 and 5. 33 mmol/kg dry wt. 3 and 6hrs afterelectrostimlation respectively. Analysis of regions with variousstructural alterations showed rise of Ca concentration inparallel with severity of myofibrillar injury. Testing with Fura 2also demonstrated obvious increase of free Ca++ in cytoplasm 3 hrs after electrostimulation. All these showed a positive correlation between DSAM and the increase of intracellular Ca++.2) Further study to explore the possible mechanisms underlying the increase of cytoplasmic Ca++ revealed two sources. During the initial rise of cytoplasmic Ca, a decline of sarcoplasmic reticulum Ca content was found, suggesting the contribution of sarcoplasmic reticulum Ca. However, no further decline was noted despite continued rise of cytoplasmic Ca, which, then, could only be accounted for by extracellular contribution.3) In skeletal muscles after long-term exhaustive stimulation and in those with delayed structural alterations,the inereased cytoplasmic Ca was quickly lowered by acupuncture, down to lpretest level 10 minutes after acupuncture. Meanwhile,no marked change in sarcoplasmic reticulum Ca content and in enzymic activity of Ca, Mg-ATPase was found, indicating no contribution on their part to the quick lowering of cytoplasmic Ca. But a rapid rise of cytoplasmic Na was found. And addition o展开更多
文摘Transient liquid phase(TLP)bonding was investigated in Hastelloy-X samples with different filler metal thicknesses(20,35,50,65,and 100μm)and holding time(5,20,80,320,and 640 min)to obtain optimum bonding parameters.Microstructural evaluations using electron probe microanalysis(EPMA)and electron backscattered diffraction(EBSD)show that the central eutectic phases present in the athermally solidified zone(ASZ)are Ni_(3)B,Ni_(2)Si,and CrB,and the precipitates formed in the diffusion-affected zone(DAZ)are MoB,CrB_(2),and Mo_(2)B_(5).According to the results,decreasing the filler thickness as well as increasing the holding time helps realize the completion of isothermal solidification and reduction in the density of precipitates in the DAZ,leading to a joint with more uniform properties.Diffusion of boron and silicon to longer distances with increasing holding time causes the removal of Cr-rich borides in the DAZ and the formation of Mo-rich silicide at the joint interface.Decrease in hardness of ASZ and DAZ due to the elimination of brittle phases in these zones during long holding time causes more uniform hardness distribution in the joint area.The best results are obtained for the sample joined with the 35μm-thick filler metal for 640 min holding time.
基金financially supported by the National Natural Science Foundation of China (No. 41202070)Shandong Outstanding Young and Middle-Aged Scientists’ Research Award Fund (No. 2011BSB01335)SDUST Research Fund (No. 2012KYTD101)
文摘The depositional environment of the Upper Permian quartzose sandstone （Kuishan sandstone in Shihezi Formation of Upper Permian） in the North China epicontinental basin is controversial. In order to test the previous hypotheses, we analyzed sedimentological characteristics of the Kuishan sandstones in outcrops and boreholes, and carried out trace element geochemical analysis by electron probe microanalyzer. Three lithofacies were recognized, including normal-graded conglomerate （Cng）, trough and planar cross-bedded coarse sandstone （CStpc）, and planar cross-bedded medium sandstone （MSpc）. Normal-graded conglomerate （Cng） formed in the meandering river or deltaic distributary channels. Trough and planar cross-bedded coarse sandstone （CStpc） formed in meandering river or distributary channels of near-source deltaic plain. Planar cross-bedded medium sandstone （MSpc） formed in the siliciclastic beach with highto moderate-energy conditions. By the petrology and trace elements analysis, three relatively large-scale transgressions were revealed. Each transgression was reflected by the lower content of Ba and ratios of Fe/Mn, and the high content of B and ratios of B/Ga. The ratios of Ni/Co of all samples are all lower than 2, suggesting oxygen-enriched shallower water en- vironment during deposition of the Kuishan sandstones.
文摘While delayed structural alterations of muscles(DSAM) induced by strenuous exercises have always been one of the commoest findings in sports-related muscle injuries, its pathogenesis remains unidentified. And although acupuncture at Ashi points has proved its efficacy in halting the progress of DASM and speeding up its recovery, we know very little about the underlying mechanism. This paper presents our work on these problems by using amphibian DSAM models created by electrostimulation, and such research tools as electromicroscopy, enzymology, the fluores cence indicator, Fura 2, and electron probe microanalysis (EPMA). Our results indicate:1) As revealed by EPMA, cytoplasmic Ca continued to rbe,reaching 3.07 and 5. 33 mmol/kg dry wt. 3 and 6hrs afterelectrostimlation respectively. Analysis of regions with variousstructural alterations showed rise of Ca concentration inparallel with severity of myofibrillar injury. Testing with Fura 2also demonstrated obvious increase of free Ca++ in cytoplasm 3 hrs after electrostimulation. All these showed a positive correlation between DSAM and the increase of intracellular Ca++.2) Further study to explore the possible mechanisms underlying the increase of cytoplasmic Ca++ revealed two sources. During the initial rise of cytoplasmic Ca, a decline of sarcoplasmic reticulum Ca content was found, suggesting the contribution of sarcoplasmic reticulum Ca. However, no further decline was noted despite continued rise of cytoplasmic Ca, which, then, could only be accounted for by extracellular contribution.3) In skeletal muscles after long-term exhaustive stimulation and in those with delayed structural alterations,the inereased cytoplasmic Ca was quickly lowered by acupuncture, down to lpretest level 10 minutes after acupuncture. Meanwhile,no marked change in sarcoplasmic reticulum Ca content and in enzymic activity of Ca, Mg-ATPase was found, indicating no contribution on their part to the quick lowering of cytoplasmic Ca. But a rapid rise of cytoplasmic Na was found. And addition o
