The influence of thermomechanical aging on microstructure and mechanical properties of 2519A aluminum alloy was investigated by means of microhardness test,tensile test,optical microscopy (OM) and transmission electro...The influence of thermomechanical aging on microstructure and mechanical properties of 2519A aluminum alloy was investigated by means of microhardness test,tensile test,optical microscopy (OM) and transmission electron microscopy (TEM).The results show that 50% cold rolling deformation prior to aging is beneficial since it promotes a more homogeneous distribution of the precipitation phase and reduces the number of precipitation phase on the grain boundaries,and thus shrinks the total volume of precipitation-free zones at grain and sub-grain boundaries.As a result,the tensile properties of 2519A aluminum alloy have been significantly improved.展开更多
Background Brain natriuretic peptide （BNP） is normally present in low levels in the circulation, but it is elevated in parallel with the degree of congestion in heart failure subjects （CHF）. BNP has natriuretic ef...Background Brain natriuretic peptide （BNP） is normally present in low levels in the circulation, but it is elevated in parallel with the degree of congestion in heart failure subjects （CHF）. BNP has natriuretic effects and is a potent vasodilator. It is suggested that BNP could be a therapeutic alternative in CHF. However, we postulated that the high levels of circulating BNP in CHF may downregulate the response of microvascular natriuretic receptors. This was tested by comparing 15 CHF patients （BNP 〉 3000 ng/L） with 10 matched, healthy controls. Methods Cutaneous microvascular blood flow in the forearm was measured by laser Doppler Flowmetry. Local heating （＋44°C, 10 min） was used to evoke a maximum local dilator response. Results Non-invasive iontophoretic administration of either BNP or acetylcholine （ACh）, a known endothelium-dependent dilator, elicited an increase in local flow. The nitric oxide synthase inhibitor, l-N-Arginine- methyl-ester （L-NAME）, blocked the BNP response （in controls）. Interestingly, responses to BNP in CHF patients were reduced to about one third of those seen in healthy controls （increase in flow： 251% in CHF vs. 908% in controls; P 〈 0.001）. In contrast, the vasodilator responses to ACh and to local heating were only somewhat attenuated in CHF patients. Thus, dilator capacity and nitric oxide signalling were not af- fected to the same extent as BNP-mediated dilation, indicating a specific downregulation of the latter response. Conclusions The findings show for the first time that microvascular responses to BNP are markedly reduced in CHF patients. This is consistent with the hypothesis of BNP receptor function is downregulated in CHF.展开更多
Objective: The present study was designed to investigate the effect of microinfusion angiotensin Ⅱ(Ang Ⅱ),Ang Ⅱ type 1(AT_1)receptor antagonist losartan into the rostral ventrolateral medulla(RVLM)on the barorecept...Objective: The present study was designed to investigate the effect of microinfusion angiotensin Ⅱ(Ang Ⅱ),Ang Ⅱ type 1(AT_1)receptor antagonist losartan into the rostral ventrolateral medulla(RVLM)on the baroreceptor reflex sensitivity(BRS)in urethane-anesthetized rats. Methods: Reflex changes in heart rate(HR)were elicited by bolus intravenous injection of phenylephrine before and during RVLM microinfusion of saline(0.5 μl/h),Ang Ⅱ (1.5 nmol/h),losartan(250 nmol/h),and Ang Ⅱ(1.5 nmol/h)pretreated with microinjection of losartan (50 nmol/0.51 μl)into the RVLM.The average ratio between changes in HR in beats per minute(beats·min -1)and changes in mean arterial pressure [MAP,mmHg(1 mmHg=0.133 kPa)] was used as an index of BRS. Results: Ang Ⅱ resulted in a significant decrease in the BRS for reflex bradycardia compared with control(-2.1±0.1 vs-3.9±0.4 beats·min -1·mmHg -1).Microinfusion of losartan had no significant effect on BRS for reflex bradycardia.The effect of Ang Ⅱ was almost completely abolished by pretreatment with microinjection of losartan. Conclusion:These results showed that the exogenous Ang Ⅱ in the RVLM produces inhibitory modulation of BRS,which is mediated by AT_1 receptor.However,AT_1 receptor in the RVLM is not involved in the tonic control of BRS.展开更多
The enriched characters of methane content in the main coal seam of Yunnan＇s Laochang coal mine was analyzed through combined with the geologic conditions of the research area： structure type, hydrogeology condition...The enriched characters of methane content in the main coal seam of Yunnan＇s Laochang coal mine was analyzed through combined with the geologic conditions of the research area： structure type, hydrogeology condition, coal reservoir＇s macerals, ash, water content, and so on. The geology factors of controlling gas in Laochang coal mine were illustrated; and the different geology models of controlling gas of geologic condition coupling were posed. Research shows that, in the region, the methane contents of the main coal seams decrease gradually from middle to all around it; the northeast and southeast is higher than the west. In the local area, the methane content of anticline axis is higher, and the gas content is reduced to both wings and plunging crown. On macroscopic view, the distribution of methane content in coal-beds was controlled by structural type. On microscopic view, the methane content in coal-beds is mainly involved in coal reservoir＇s macerals, ash content, and water content. The enriched characters of CBM in the research area are mainly the result of structure-hydrogeology-petrophysics coupling controls of CBM. On the basis of above analysis, according to the distribution character of methane content in coalbeds, the research area was divided into low gas area, middle gas area, and high gas area.展开更多
Purpose： Macrophages are known to be important for healing numerous injured tissues depending on their functional phenotypes in response to different stimuli. The objective of this study was to reveal macrophage phen...Purpose： Macrophages are known to be important for healing numerous injured tissues depending on their functional phenotypes in response to different stimuli. The objective of this study was to reveal macrophage phenotypic changes involved in exercise-induced skeletal muscle injury and regeneration. Methods： Adult male Sprague-Dawley rats experienced one session of downhill running （16~ decline, 16 m/min） for 90 min. After exercise the blood and soleus muscles were collected at 0 h, 6 h, 12 h, 1 d, 2 d, 3 d, 1 w and 2 w after exercise, separately. Results： It was showed that CD6B＋ M1 macrophages mainly infiltrated into musc｜e necrotic sites at 1-3 d, while CD163＋ M2 macrophages were present in muscles from 0 h to 2 weeks after exercise. Using transmission electron microscopy, we observed activated satellite cells 1 d after exercise. Thl-associated transcripts of iNOS and Cc12 were inhibited post exercise, while COX-2 mRNA was dramatically increased 12 h after running （p 〈 0.01 ）. M2 phenotype marker Arg-1 increased 12 h and 3 d （p 〈 0.05, p 〈 0.01 ） after exercise, and Clecl0a and Mrc2 were up-regulated in muscles 12 h following exercise （p 〈 0.05, p 〈 0.05）. Conclusion： The data demonstrate the dynamic patterns of macrophage phenotype in skeletal muscle upon eccentric exercise stimuli, and M1 and M2 phenotypes perform different functions during exercise- induced skeletal muscle injury and recovery.展开更多
基金Project(2005CB623706) supported by the National Basic Research Program of China
文摘The influence of thermomechanical aging on microstructure and mechanical properties of 2519A aluminum alloy was investigated by means of microhardness test,tensile test,optical microscopy (OM) and transmission electron microscopy (TEM).The results show that 50% cold rolling deformation prior to aging is beneficial since it promotes a more homogeneous distribution of the precipitation phase and reduces the number of precipitation phase on the grain boundaries,and thus shrinks the total volume of precipitation-free zones at grain and sub-grain boundaries.As a result,the tensile properties of 2519A aluminum alloy have been significantly improved.
文摘Background Brain natriuretic peptide （BNP） is normally present in low levels in the circulation, but it is elevated in parallel with the degree of congestion in heart failure subjects （CHF）. BNP has natriuretic effects and is a potent vasodilator. It is suggested that BNP could be a therapeutic alternative in CHF. However, we postulated that the high levels of circulating BNP in CHF may downregulate the response of microvascular natriuretic receptors. This was tested by comparing 15 CHF patients （BNP 〉 3000 ng/L） with 10 matched, healthy controls. Methods Cutaneous microvascular blood flow in the forearm was measured by laser Doppler Flowmetry. Local heating （＋44°C, 10 min） was used to evoke a maximum local dilator response. Results Non-invasive iontophoretic administration of either BNP or acetylcholine （ACh）, a known endothelium-dependent dilator, elicited an increase in local flow. The nitric oxide synthase inhibitor, l-N-Arginine- methyl-ester （L-NAME）, blocked the BNP response （in controls）. Interestingly, responses to BNP in CHF patients were reduced to about one third of those seen in healthy controls （increase in flow： 251% in CHF vs. 908% in controls; P 〈 0.001）. In contrast, the vasodilator responses to ACh and to local heating were only somewhat attenuated in CHF patients. Thus, dilator capacity and nitric oxide signalling were not af- fected to the same extent as BNP-mediated dilation, indicating a specific downregulation of the latter response. Conclusions The findings show for the first time that microvascular responses to BNP are markedly reduced in CHF patients. This is consistent with the hypothesis of BNP receptor function is downregulated in CHF.
文摘Objective: The present study was designed to investigate the effect of microinfusion angiotensin Ⅱ(Ang Ⅱ),Ang Ⅱ type 1(AT_1)receptor antagonist losartan into the rostral ventrolateral medulla(RVLM)on the baroreceptor reflex sensitivity(BRS)in urethane-anesthetized rats. Methods: Reflex changes in heart rate(HR)were elicited by bolus intravenous injection of phenylephrine before and during RVLM microinfusion of saline(0.5 μl/h),Ang Ⅱ (1.5 nmol/h),losartan(250 nmol/h),and Ang Ⅱ(1.5 nmol/h)pretreated with microinjection of losartan (50 nmol/0.51 μl)into the RVLM.The average ratio between changes in HR in beats per minute(beats·min -1)and changes in mean arterial pressure [MAP,mmHg(1 mmHg=0.133 kPa)] was used as an index of BRS. Results: Ang Ⅱ resulted in a significant decrease in the BRS for reflex bradycardia compared with control(-2.1±0.1 vs-3.9±0.4 beats·min -1·mmHg -1).Microinfusion of losartan had no significant effect on BRS for reflex bradycardia.The effect of Ang Ⅱ was almost completely abolished by pretreatment with microinjection of losartan. Conclusion:These results showed that the exogenous Ang Ⅱ in the RVLM produces inhibitory modulation of BRS,which is mediated by AT_1 receptor.However,AT_1 receptor in the RVLM is not involved in the tonic control of BRS.
基金Supported by the National Major Special Projects of Science and Technology of China （2011ZX05034） the National Basic Research Program of China （2009CB219605） the National Natural Science Foundation of China （41272178）
文摘The enriched characters of methane content in the main coal seam of Yunnan＇s Laochang coal mine was analyzed through combined with the geologic conditions of the research area： structure type, hydrogeology condition, coal reservoir＇s macerals, ash, water content, and so on. The geology factors of controlling gas in Laochang coal mine were illustrated; and the different geology models of controlling gas of geologic condition coupling were posed. Research shows that, in the region, the methane contents of the main coal seams decrease gradually from middle to all around it; the northeast and southeast is higher than the west. In the local area, the methane content of anticline axis is higher, and the gas content is reduced to both wings and plunging crown. On macroscopic view, the distribution of methane content in coal-beds was controlled by structural type. On microscopic view, the methane content in coal-beds is mainly involved in coal reservoir＇s macerals, ash content, and water content. The enriched characters of CBM in the research area are mainly the result of structure-hydrogeology-petrophysics coupling controls of CBM. On the basis of above analysis, according to the distribution character of methane content in coalbeds, the research area was divided into low gas area, middle gas area, and high gas area.
文摘Purpose： Macrophages are known to be important for healing numerous injured tissues depending on their functional phenotypes in response to different stimuli. The objective of this study was to reveal macrophage phenotypic changes involved in exercise-induced skeletal muscle injury and regeneration. Methods： Adult male Sprague-Dawley rats experienced one session of downhill running （16~ decline, 16 m/min） for 90 min. After exercise the blood and soleus muscles were collected at 0 h, 6 h, 12 h, 1 d, 2 d, 3 d, 1 w and 2 w after exercise, separately. Results： It was showed that CD6B＋ M1 macrophages mainly infiltrated into musc｜e necrotic sites at 1-3 d, while CD163＋ M2 macrophages were present in muscles from 0 h to 2 weeks after exercise. Using transmission electron microscopy, we observed activated satellite cells 1 d after exercise. Thl-associated transcripts of iNOS and Cc12 were inhibited post exercise, while COX-2 mRNA was dramatically increased 12 h after running （p 〈 0.01 ）. M2 phenotype marker Arg-1 increased 12 h and 3 d （p 〈 0.05, p 〈 0.01 ） after exercise, and Clecl0a and Mrc2 were up-regulated in muscles 12 h following exercise （p 〈 0.05, p 〈 0.05）. Conclusion： The data demonstrate the dynamic patterns of macrophage phenotype in skeletal muscle upon eccentric exercise stimuli, and M1 and M2 phenotypes perform different functions during exercise- induced skeletal muscle injury and recovery.
