AIM： To evaluate the changes in hepatic platelet activating factor （PAF） and its receptors and their effect on portal pressure of cirrhotic rats induced by CCh. METHODS： A model of liver cirrhosis was replicated i...AIM： To evaluate the changes in hepatic platelet activating factor （PAF） and its receptors and their effect on portal pressure of cirrhotic rats induced by CCh. METHODS： A model of liver cirrhosis was replicated in rats by intra-peritoneal injection of CCh for 8 wk. We determined the effect of hepatic PAF and its receptor level on portal and arterial pressure by EIA, saturation binding and RT-PCR technique. RESULTS： Compared to control rats, cirrhotic rats had higher hepatic PAF levels and output as well as higher plasma PAF levels （P〈0.01, P〈0.01, P〈0.05, respectively）. Both hepatic PAF receptor mRNA levels and PAF binding were nearly 3-fold greater in cirrhotic rats （P〈0.01）. Portal injection of PAF （1 g/kg WT） increased the portal pressure by 22% and 33% in control and cirrhotic rats, respectively. In contrast, the arterial pressure was decreased in the both groups （54% in control rats and 42% in cirrhotic rats）. Injection of the PAF antagonist BN52021 （5 mg/kg WT） decreased the portal pressure by 16% in cirrhotic rats but had no effect in the control rats. CONCLUSION： The upregulation of the PAF system contributes to hepatic hemodynamic and metabolic abnormalities in drrhosis, and the increased release of PAF into the circulation has impacts on the systemic hemodynamics.展开更多
Calcium aluminate cement(CAC)—based strain hardening cementitious composites(SHCC)has been developed and used for the rehabilitation of sewerage pipelines.In addition to well-known microbiologically induced corrosion...Calcium aluminate cement(CAC)—based strain hardening cementitious composites(SHCC)has been developed and used for the rehabilitation of sewerage pipelines.In addition to well-known microbiologically induced corrosion,CO_(2)concentration in the sewerage environment is high,which may cause significant carbonation of pipelines.Thus,this paper aims to investigate the effects of carbonation on the mechanical performance of CAC-based SHCC.Two types of CAC-based SHCC with different strength grades and a referenced OPC-based SHCC were prepared.The accelerated carbonation test was conducted in a carbonation chamber with a 5%CO_(2)concentration.The compressive and tensile behaviour of SHCC was tested first,and microstructure analysis,e.g.,X-ray diffraction and scanning electron microscopy,was then performed.The results showed that CAC-based SHCC specimens exhibited robust strain-hardening performance as well as large deformation capacity in tension due to the fiber-bridging effect.Also,the compressive and tensile strength was significantly improved as well as achieving a higher tensile strain capacity after carbonation when compared with OPC-based SHCC.Microstructure analysis revealed that the metastable phases in carbonated CAC-based SHCC were converted into stable phases and calcium carbonate polymorphs,densifying the binder matrix.The obtained results of this paper may provide new insight into utilizing carbonation to avoid the unstable conversion of hydrates in calcium aluminate cement.展开更多
Nanoindentation technique was adopted to investigate the chemomechanical properties change of hardened cement paste before and after carbonation.It was found that the mean elastic modulus and mean hardness obviously i...Nanoindentation technique was adopted to investigate the chemomechanical properties change of hardened cement paste before and after carbonation.It was found that the mean elastic modulus and mean hardness obviously increase after the carbonation reaction.Specifically,the probability of the elastic modulus showed a sharp reduction for the elastic modulus at the range of 7-34 and 83-160 GPa,in comparison of a large increase for the elastic modulus between 34-83 GPa.For the same reason,the probability of the hardness showed a large decrease when the hardness fell within 0.15-1.75 and 4.15-8.20 GPa and a dramatic increase for the hardness at the range of 1.75-4.15 GPa.In addition,low density C-S-H was affected by the carbonation degradation more seriously than high density C-S-H.The carbonation reaction led to distinct decrease of the number and size of unhydrated cement paste particles.展开更多
基金Supported by the Key Scientific and Technological Research Foundation of the National 863 Program,No.2003AA208106Medical Outstandard Foundation of Army,No.04J020
文摘AIM： To evaluate the changes in hepatic platelet activating factor （PAF） and its receptors and their effect on portal pressure of cirrhotic rats induced by CCh. METHODS： A model of liver cirrhosis was replicated in rats by intra-peritoneal injection of CCh for 8 wk. We determined the effect of hepatic PAF and its receptor level on portal and arterial pressure by EIA, saturation binding and RT-PCR technique. RESULTS： Compared to control rats, cirrhotic rats had higher hepatic PAF levels and output as well as higher plasma PAF levels （P〈0.01, P〈0.01, P〈0.05, respectively）. Both hepatic PAF receptor mRNA levels and PAF binding were nearly 3-fold greater in cirrhotic rats （P〈0.01）. Portal injection of PAF （1 g/kg WT） increased the portal pressure by 22% and 33% in control and cirrhotic rats, respectively. In contrast, the arterial pressure was decreased in the both groups （54% in control rats and 42% in cirrhotic rats）. Injection of the PAF antagonist BN52021 （5 mg/kg WT） decreased the portal pressure by 16% in cirrhotic rats but had no effect in the control rats. CONCLUSION： The upregulation of the PAF system contributes to hepatic hemodynamic and metabolic abnormalities in drrhosis, and the increased release of PAF into the circulation has impacts on the systemic hemodynamics.
基金The first author would like to acknowledge the University of South Australia Postgraduate Research Award and Research Training Program scholarships for his Ph.D study.
文摘Calcium aluminate cement(CAC)—based strain hardening cementitious composites(SHCC)has been developed and used for the rehabilitation of sewerage pipelines.In addition to well-known microbiologically induced corrosion,CO_(2)concentration in the sewerage environment is high,which may cause significant carbonation of pipelines.Thus,this paper aims to investigate the effects of carbonation on the mechanical performance of CAC-based SHCC.Two types of CAC-based SHCC with different strength grades and a referenced OPC-based SHCC were prepared.The accelerated carbonation test was conducted in a carbonation chamber with a 5%CO_(2)concentration.The compressive and tensile behaviour of SHCC was tested first,and microstructure analysis,e.g.,X-ray diffraction and scanning electron microscopy,was then performed.The results showed that CAC-based SHCC specimens exhibited robust strain-hardening performance as well as large deformation capacity in tension due to the fiber-bridging effect.Also,the compressive and tensile strength was significantly improved as well as achieving a higher tensile strain capacity after carbonation when compared with OPC-based SHCC.Microstructure analysis revealed that the metastable phases in carbonated CAC-based SHCC were converted into stable phases and calcium carbonate polymorphs,densifying the binder matrix.The obtained results of this paper may provide new insight into utilizing carbonation to avoid the unstable conversion of hydrates in calcium aluminate cement.
基金supported by the National Basic Research Program of China ("973" Project) (Grant No. 2009CB623200)the Scientific Research Foundation of the Graduate School of Southeast University (Grant No. YBJJ1113)
文摘Nanoindentation technique was adopted to investigate the chemomechanical properties change of hardened cement paste before and after carbonation.It was found that the mean elastic modulus and mean hardness obviously increase after the carbonation reaction.Specifically,the probability of the elastic modulus showed a sharp reduction for the elastic modulus at the range of 7-34 and 83-160 GPa,in comparison of a large increase for the elastic modulus between 34-83 GPa.For the same reason,the probability of the hardness showed a large decrease when the hardness fell within 0.15-1.75 and 4.15-8.20 GPa and a dramatic increase for the hardness at the range of 1.75-4.15 GPa.In addition,low density C-S-H was affected by the carbonation degradation more seriously than high density C-S-H.The carbonation reaction led to distinct decrease of the number and size of unhydrated cement paste particles.
