The projected changes in carbon exchange between China terrestrial ecosystem and the atmosphere and vegetation and soil carbon storage during the 21st century were investigated using an atmos-phere-vegetation interact...The projected changes in carbon exchange between China terrestrial ecosystem and the atmosphere and vegetation and soil carbon storage during the 21st century were investigated using an atmos-phere-vegetation interaction model (AVIM2). The results show that in the coming 100 a, for SRES B2 scenario and constant atmospheric CO2 concentration, the net primary productivity (NPP) of terrestrial ecosystem in China will be decreased slowly, and vegetation and soil carbon storage as well as net ecosystem productivity (NEP) will also be decreased. The carbon sink for China terrestrial ecosystem in the beginning of the 20th century will become totally a carbon source by the year of 2020, while for B2 scenario and changing atmospheric CO2 concentration, NPP for China will increase continuously from 2.94 GtC·a?1 by the end of the 20th century to 3.99 GtC·a?1 by the end of the 21st century, and vegetation and soil carbon storage will increase to 110.3 GtC. NEP in China will keep rising during the first and middle periods of the 21st century, and reach the peak around 2050s, then will decrease gradually and approach to zero by the end of the 21st century.展开更多
This paper applies the newest emission scenarios of the sulfur and greenhouse gases, namely IPCC SRES A2 and B2 scenarios, to investigate the change of the North China climate with an atmosphere-ocean coupled general ...This paper applies the newest emission scenarios of the sulfur and greenhouse gases, namely IPCC SRES A2 and B2 scenarios, to investigate the change of the North China climate with an atmosphere-ocean coupled general circulation model. In the last three decades of the 21st century, the global warming enlarges the land-sea thermal contrast, and hence, causes the East Asian summer (winter) monsoon circulation to he strengthened (weakened). The rainfall seasonality strengthens and the summer precipitation increases significantly in North China. It is suggested that the East Asian rainy area would expand northward to North China in the last three decades of the 21st century. In addition, the North China precipitation would increase significantly in September. In July, August, and September, the interannual variability of the precipitation enlarges evidently over North China, implying a risk of flooding in the future.展开更多
To improve the wear resistance of aluminum alloy frictional parts, Ti B2particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding. The microstructure and tribological...To improve the wear resistance of aluminum alloy frictional parts, Ti B2particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding. The microstructure and tribological properties of the composite coatings were investigated. The results show that the composite coating contains the phases of Ni Al, Ni3Al, Al3Ni2, TiB2, TiB, TiC, CrB, and Cr23C6.Its microhardness is HV0.5855.8, which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy. The friction coefficients of the composite coatings are reduced by 6.8 %–21.6 % and 13.2 %–32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys, while the wear losses are 27.4 %–43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %–32.7 % of those of the aluminum alloys at different loads. At the light loads ranging from 3 to 6 N, the calculated maximum contact stress is smaller than the elastic limit contact stress. The wear mechanism of the composite coatings is micro-cutting wear, but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress. As the loads increase to 12 N, the calculated flash temperature rises to 332.1 °C.The composite coating experiences multi-plastic deformation wear, micro-brittle fracture wear, and oxidative wear.展开更多
Mouth ulcer is associated with inflammation and high risk of bacterial infection, which aggravates the patient's condition.Currently, there is no effective treatment for mouth ulcer. Herein, we report that vitamin...Mouth ulcer is associated with inflammation and high risk of bacterial infection, which aggravates the patient's condition.Currently, there is no effective treatment for mouth ulcer. Herein, we report that vitamin-modified iron oxide nanoparticles improve the healing of mouth ulcer through anti-inflammation and antibacterial activities. We discovered that vitamin B2(VB2)modified iron oxide nanoparticles performed enhanced peroxidase-like, catalase-like, and superoxide dismutase(SOD)-like activities, acting as typical iron oxide nanozymes(IONzymes) with triad activities. In particular, VB2 modification significantly improved the SOD-like activity, thus providing a reactive oxygen species(ROS)-scavenging ability. Cellular antioxidant experiments showed that vitamin B2 modified IONzymes(VB2-IONzymes) protect human oral keratinocytes(HOK) and BALB/3 T3 cells from hydrogen peroxide(H2O2), and these cells have high biocompatibility to eukaryotic cells. In addition, VB2-IONzymes exerted an antibacterial activity against Streptococcus mutans, Staphylococcus aureus, and Escherichia coli. Importantly, VB2-IONzymes accelerated the recovery of mouth ulcer and reduced the local secretion of inflammatory factors in mouse ulcer model via ROS scavenging and antibacterial activity. Taken together, our work demonstrates that vitamin B2 modification endows iron oxide nanoparticles with enhanced enzyme-like activities and VB2-IONzymes may be a promising reagent in the treatment of mouth ulcer because of their intrinsic anti-inflammation and antibacterial capabilities.展开更多
AIM: To provide further insight into the characterization of mucosa-associated Escherichia coli (E. coli) isolated from the colonic mucosa of cancer patients.
The concentration of carcinogenic polycyclic aromatic hydrocarbons （c-PAHs） present in the sediment and water of Peninsular Malaysia as well as in the cockle Anadara granosa was investigated. Samples were extracted ...The concentration of carcinogenic polycyclic aromatic hydrocarbons （c-PAHs） present in the sediment and water of Peninsular Malaysia as well as in the cockle Anadara granosa was investigated. Samples were extracted and analysed with gas chromatographymass spectrometry. The concentrations of total carcinogenic polycyclic aromatic hydrocarbons （t-PAHs） were measured between 0.80±0.04 to 162.96 ±14.74 ng/g wet weight （ww） in sediment, between 21.85± 2.18 to 76.2± 10.82 ng/L in water samples and between 3.34 ±0.77 to 46.85 ± 5.50 ng/g ww in the cockle tissue. The risk assessment of probable human carcinogens in the Group B2 PAHs was calculated and assessed in accordance with the standards of the United States Environmental Protection Agency （US EPA）. Case I in the toxicity assessment analysed the cancer risk to consumers of Malaysian blood cockle. Case II assessed the risk of cancer from exposure to PAHs from multiple pathways. The average cancer risk of case I and case II were found to be classifiable as unsafe according to the US EPA standard. The cancer risk due to c-PAHs acquired by the ingestion of blood cockle was （8.82 ± 0.54） × 10^ 6 to （2.67 ± 0.06） × 10^-2, higher than the US EPA risk management criterion. The non-cancer risks associated with multiple pathways in Kuala Gula, Kuala Juru and Kuala Perlis were higher than the US EPA safe level, but the non-cancer risk for eating blood cockle was below the level of US EPA concern.展开更多
使用SAC/SAC-CI方法,利用D95(d),6-311g**以及cc-PVTZ等基组,对B2分子的基态(X3Σg-)和第一激发态(A3Σu-)的平衡结构和谐振频率进行了优化计算.通过对3个基组的计算结果的比较,得出了D95(d)基组为3个基组中的最优基组的结论;使用D95(d...使用SAC/SAC-CI方法,利用D95(d),6-311g**以及cc-PVTZ等基组,对B2分子的基态(X3Σg-)和第一激发态(A3Σu-)的平衡结构和谐振频率进行了优化计算.通过对3个基组的计算结果的比较,得出了D95(d)基组为3个基组中的最优基组的结论;使用D95(d)基组,利用SAC的GSUM(Group Sum of Operators)方法对基态(X3Σg-),SAC-CI的GSUM方法对激发态(A3Σu-)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到了相应电子态的完整势能函数;从得到的势能函数计算了与基态(X3Σg-)和第一激发态(A3Σu-)相对应的光谱常数(Be,αe,ωe和ωeχe),结果与实验数据吻合.展开更多
Objective：To investigate the expression of cyclooxygenase-2 and its pathological effect in the experimental nonalcoholic fatty liver of rats, and to explore its possible mechanism. Methods：The rat NAFLD model was es...Objective：To investigate the expression of cyclooxygenase-2 and its pathological effect in the experimental nonalcoholic fatty liver of rats, and to explore its possible mechanism. Methods：The rat NAFLD model was established by giving a fat-enriched diet. The blood samples were obtained form abdominal aorta and the levels of serum ALT, AST and IL-1, changes in the hepatic tissue 6-k-PGF1 α TXB2 were measured. The expression level of COX-2 in rats livers were assayed by immunohistochemistry, RT-PCR and Westernblot. Results： Light microscope analysis revealed that hepatocytes were injured in the model group and slightly in the treatment group. The levels of serum TXB2 and IL-1 in the fatty liver rats were increased. Compared with the model group, the IL-1 and TXB2 increased significantly（P〈 0.05）, on the contrary, compared with the normal group, the hepatic tissue 6-Keto-prostagland decreased significantly in the model group（P 〈 0.05）, the treatment group also increased but P 〉 0.05. There was no positive expression of COX-2 in hepatic tissue of normal rats. In the model group, there was positive expression of COX-2 antigen and the number of COX positive cells progressively increased at 4, 8, 12 wks. The intensity of expression of COX-2 had significantly increased（P 〈 0.05 ） and the intensity of COX-2 expression in the treated group decreased remarkably compared with the model group（P 〈 0.05）. The expression of COX-2 mRNA and the level of COX-2 protein were significantly stronger in the liver of model rats compared with normal rats, and significantly weaker in treated rats, than in 8W and 12W model rats（P 〈 0.05）. Conclusion：The increase of COX-2 expression in NAFLD is closely associated with the severity of liver inflammation and damage. COX-2 may play an important role in the progression of rat NAFLD, and the expression of COX-2 mRNA is downregulated by cyclooxygenase-2 inhibitor, which can depress the oxidative stress and control inflammatory response efficiently.展开更多
基金the Basic Research Program of China (Grant No. 2002CB412500)the National Natural Science Foundation of China (Grant No. 30590384)
文摘The projected changes in carbon exchange between China terrestrial ecosystem and the atmosphere and vegetation and soil carbon storage during the 21st century were investigated using an atmos-phere-vegetation interaction model (AVIM2). The results show that in the coming 100 a, for SRES B2 scenario and constant atmospheric CO2 concentration, the net primary productivity (NPP) of terrestrial ecosystem in China will be decreased slowly, and vegetation and soil carbon storage as well as net ecosystem productivity (NEP) will also be decreased. The carbon sink for China terrestrial ecosystem in the beginning of the 20th century will become totally a carbon source by the year of 2020, while for B2 scenario and changing atmospheric CO2 concentration, NPP for China will increase continuously from 2.94 GtC·a?1 by the end of the 20th century to 3.99 GtC·a?1 by the end of the 21st century, and vegetation and soil carbon storage will increase to 110.3 GtC. NEP in China will keep rising during the first and middle periods of the 21st century, and reach the peak around 2050s, then will decrease gradually and approach to zero by the end of the 21st century.
基金supported by the Key Project of the Chinese Academy of Sciences(KZCX2-SW-210)the Key Project of the Chinese Academy of Sciences(KZCX2-203)the National Key Programme for Developing Basic Sciences(G1998040904).
文摘This paper applies the newest emission scenarios of the sulfur and greenhouse gases, namely IPCC SRES A2 and B2 scenarios, to investigate the change of the North China climate with an atmosphere-ocean coupled general circulation model. In the last three decades of the 21st century, the global warming enlarges the land-sea thermal contrast, and hence, causes the East Asian summer (winter) monsoon circulation to he strengthened (weakened). The rainfall seasonality strengthens and the summer precipitation increases significantly in North China. It is suggested that the East Asian rainy area would expand northward to North China in the last three decades of the 21st century. In addition, the North China precipitation would increase significantly in September. In July, August, and September, the interannual variability of the precipitation enlarges evidently over North China, implying a risk of flooding in the future.
基金financially supported by the Research Program of General Armament Department of China (No. 2012500)
文摘To improve the wear resistance of aluminum alloy frictional parts, Ti B2particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding. The microstructure and tribological properties of the composite coatings were investigated. The results show that the composite coating contains the phases of Ni Al, Ni3Al, Al3Ni2, TiB2, TiB, TiC, CrB, and Cr23C6.Its microhardness is HV0.5855.8, which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy. The friction coefficients of the composite coatings are reduced by 6.8 %–21.6 % and 13.2 %–32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys, while the wear losses are 27.4 %–43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %–32.7 % of those of the aluminum alloys at different loads. At the light loads ranging from 3 to 6 N, the calculated maximum contact stress is smaller than the elastic limit contact stress. The wear mechanism of the composite coatings is micro-cutting wear, but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress. As the loads increase to 12 N, the calculated flash temperature rises to 332.1 °C.The composite coating experiences multi-plastic deformation wear, micro-brittle fracture wear, and oxidative wear.
基金supported by the National Key Research and Development Program of China(2018YFC1003500)the National Natural Science Foundation of China(81671810 and 31701236)the Jiangsu Provincial Basic Research Program for the Natural Science Foundation(BK20161333)
文摘Mouth ulcer is associated with inflammation and high risk of bacterial infection, which aggravates the patient's condition.Currently, there is no effective treatment for mouth ulcer. Herein, we report that vitamin-modified iron oxide nanoparticles improve the healing of mouth ulcer through anti-inflammation and antibacterial activities. We discovered that vitamin B2(VB2)modified iron oxide nanoparticles performed enhanced peroxidase-like, catalase-like, and superoxide dismutase(SOD)-like activities, acting as typical iron oxide nanozymes(IONzymes) with triad activities. In particular, VB2 modification significantly improved the SOD-like activity, thus providing a reactive oxygen species(ROS)-scavenging ability. Cellular antioxidant experiments showed that vitamin B2 modified IONzymes(VB2-IONzymes) protect human oral keratinocytes(HOK) and BALB/3 T3 cells from hydrogen peroxide(H2O2), and these cells have high biocompatibility to eukaryotic cells. In addition, VB2-IONzymes exerted an antibacterial activity against Streptococcus mutans, Staphylococcus aureus, and Escherichia coli. Importantly, VB2-IONzymes accelerated the recovery of mouth ulcer and reduced the local secretion of inflammatory factors in mouse ulcer model via ROS scavenging and antibacterial activity. Taken together, our work demonstrates that vitamin B2 modification endows iron oxide nanoparticles with enhanced enzyme-like activities and VB2-IONzymes may be a promising reagent in the treatment of mouth ulcer because of their intrinsic anti-inflammation and antibacterial capabilities.
基金Supported by Ministère de l’Enseignement supérieur et de la Recherche,Inserm and Universitéd’Auvergne(UMR1071),INRA(USC-2018)Grants from the Association F.Aupetit(AFA)and Ligue contre le cancer
文摘AIM: To provide further insight into the characterization of mucosa-associated Escherichia coli (E. coli) isolated from the colonic mucosa of cancer patients.
基金supported by the MOSTI Science Funding Project(No. 5450100)
文摘The concentration of carcinogenic polycyclic aromatic hydrocarbons （c-PAHs） present in the sediment and water of Peninsular Malaysia as well as in the cockle Anadara granosa was investigated. Samples were extracted and analysed with gas chromatographymass spectrometry. The concentrations of total carcinogenic polycyclic aromatic hydrocarbons （t-PAHs） were measured between 0.80±0.04 to 162.96 ±14.74 ng/g wet weight （ww） in sediment, between 21.85± 2.18 to 76.2± 10.82 ng/L in water samples and between 3.34 ±0.77 to 46.85 ± 5.50 ng/g ww in the cockle tissue. The risk assessment of probable human carcinogens in the Group B2 PAHs was calculated and assessed in accordance with the standards of the United States Environmental Protection Agency （US EPA）. Case I in the toxicity assessment analysed the cancer risk to consumers of Malaysian blood cockle. Case II assessed the risk of cancer from exposure to PAHs from multiple pathways. The average cancer risk of case I and case II were found to be classifiable as unsafe according to the US EPA standard. The cancer risk due to c-PAHs acquired by the ingestion of blood cockle was （8.82 ± 0.54） × 10^ 6 to （2.67 ± 0.06） × 10^-2, higher than the US EPA risk management criterion. The non-cancer risks associated with multiple pathways in Kuala Gula, Kuala Juru and Kuala Perlis were higher than the US EPA safe level, but the non-cancer risk for eating blood cockle was below the level of US EPA concern.
文摘使用SAC/SAC-CI方法,利用D95(d),6-311g**以及cc-PVTZ等基组,对B2分子的基态(X3Σg-)和第一激发态(A3Σu-)的平衡结构和谐振频率进行了优化计算.通过对3个基组的计算结果的比较,得出了D95(d)基组为3个基组中的最优基组的结论;使用D95(d)基组,利用SAC的GSUM(Group Sum of Operators)方法对基态(X3Σg-),SAC-CI的GSUM方法对激发态(A3Σu-)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到了相应电子态的完整势能函数;从得到的势能函数计算了与基态(X3Σg-)和第一激发态(A3Σu-)相对应的光谱常数(Be,αe,ωe和ωeχe),结果与实验数据吻合.
文摘Objective：To investigate the expression of cyclooxygenase-2 and its pathological effect in the experimental nonalcoholic fatty liver of rats, and to explore its possible mechanism. Methods：The rat NAFLD model was established by giving a fat-enriched diet. The blood samples were obtained form abdominal aorta and the levels of serum ALT, AST and IL-1, changes in the hepatic tissue 6-k-PGF1 α TXB2 were measured. The expression level of COX-2 in rats livers were assayed by immunohistochemistry, RT-PCR and Westernblot. Results： Light microscope analysis revealed that hepatocytes were injured in the model group and slightly in the treatment group. The levels of serum TXB2 and IL-1 in the fatty liver rats were increased. Compared with the model group, the IL-1 and TXB2 increased significantly（P〈 0.05）, on the contrary, compared with the normal group, the hepatic tissue 6-Keto-prostagland decreased significantly in the model group（P 〈 0.05）, the treatment group also increased but P 〉 0.05. There was no positive expression of COX-2 in hepatic tissue of normal rats. In the model group, there was positive expression of COX-2 antigen and the number of COX positive cells progressively increased at 4, 8, 12 wks. The intensity of expression of COX-2 had significantly increased（P 〈 0.05 ） and the intensity of COX-2 expression in the treated group decreased remarkably compared with the model group（P 〈 0.05）. The expression of COX-2 mRNA and the level of COX-2 protein were significantly stronger in the liver of model rats compared with normal rats, and significantly weaker in treated rats, than in 8W and 12W model rats（P 〈 0.05）. Conclusion：The increase of COX-2 expression in NAFLD is closely associated with the severity of liver inflammation and damage. COX-2 may play an important role in the progression of rat NAFLD, and the expression of COX-2 mRNA is downregulated by cyclooxygenase-2 inhibitor, which can depress the oxidative stress and control inflammatory response efficiently.
