A numerical simulation was performed to investigate the interaction of two bubbles rising side by side in shear-thinning fluid using volume of fluid (VOF) method coupled with continuous surface force (CSF) method....A numerical simulation was performed to investigate the interaction of two bubbles rising side by side in shear-thinning fluid using volume of fluid (VOF) method coupled with continuous surface force (CSF) method. By considering rheological characteristics of fluid, this approach was able to accurately capture the deformation of bubble interface, and validated by comparing with the experimental results. The rising of bubble pairs with different configurations, including horizontal alignment and oblique alignment, was simulated by the method. The influences of the bubble initial distance and the bubble alignment were studied by analyzing the bubble deformation, rising paths and flow fields surrounding bubbles. The results indicate that within certam mltlal bubble spacing of S = 3.3 (S* = SI/D, SI initial distance between bubbles, and D bubble diameter), the dynamic interaction between two bub- bles aligned horizontally shows repulsive effect that decreases with the increase of initial bubble spacing, but weakens to certain degree by the shear-thinning properties of fluid. However, the interaction between two bubbles aligned obliquely presents a repulsive effect for the small angle involved but an attractive impact for the large one, which is vet strengthened by the rheological characteristics of fluid.展开更多
Based on research results on the impacts of solar light,seawater temperature,and nutrient available to phytoplankton growth and changes in phytoplankton physiology and assemblage,we discussed the order of influence of...Based on research results on the impacts of solar light,seawater temperature,and nutrient available to phytoplankton growth and changes in phytoplankton physiology and assemblage,we discussed the order of influence of these factors.By clarifying the mechanisms and processes of the impacts by these factors,we have determined the rising order of the importance as solar light,seawater temperature,and nutrient silicon (Si).Therefore,for human interests in sustaining economic development,the first thing to be considered is the input of nutrient Si into the ocean,followed by seawater temperature change.展开更多
Systematic experimental work was conducted to investigate the solid acceleration length in a 16m long circulating fluidized bed riser with fluid cracking catalyst particles over a wide range of operating conditions. A...Systematic experimental work was conducted to investigate the solid acceleration length in a 16m long circulating fluidized bed riser with fluid cracking catalyst particles over a wide range of operating conditions. A more feasible method is proposed to determine the acceleration length from the measured axial profiles of pressure gradient (or apparent solid holdup). With this new method and large amount of experimental data, a clear picture on the variation of the acceleration length with both solid circulating rate and superficial gas velocity is obtained.It is found that the acceleration length increases generally with increasing solid flow rate and/or decreasing gas velocity. However, the trend in variation of the acceleration length with operating conditions are quite different in different operation ranges. Reasonable explanations are suggested for the observed variation patterns of acceleration length.展开更多
China's relationship with Central Asia has grown manifold since the foundation of Shanghai Five in 1996, which in June 2001 became the Shanghai Cooperation Organisation. The impetus to the relationship has further be...China's relationship with Central Asia has grown manifold since the foundation of Shanghai Five in 1996, which in June 2001 became the Shanghai Cooperation Organisation. The impetus to the relationship has further been accen- tuated when China-Russia friendship treaty was signed in July 2001. The US-led war in Afghanistan against Taliban and A1-Qaeda has yet again cemented Chinese position in Central Asia, and the recently concluded Belt and Road Initiative (BRI) has undeniably dramatically underscored the strategic value of Central Asia to the west and has opened up possibilities for Chinese security, political and economic interests. Geostrategically enmeshed with Central Asia, China will remain an integral and increasingly influential player in Central Asia. This research paper contextualises China's emergence and interests in Central Asia discarding the much talked about great game thesis and asserts by analysing the rise of China in the region as an unmatched and unchallenged power which has been testified once again with the recent BRI of Beijing.展开更多
The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world's major dust emission centres. Deciphering the source region of Asian dust is cr...The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world's major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environrnental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.展开更多
Background:Autoimmune hepatitis may flare up after treatment withdrawal,especially in those who had not achieved histological remission but had normal liver enzymes.The European Association for the Study of the Liver(...Background:Autoimmune hepatitis may flare up after treatment withdrawal,especially in those who had not achieved histological remission but had normal liver enzymes.The European Association for the Study of the Liver(EASL)and the American Association for the Study of Liver Disease(AASLD)Guidelines recommend performing liver biopsy before treatment withdrawal.The aim of the study is to define the outcome of treatment withdrawal in adults with wellcontrolled disease for 2 years with and without liver-biopsy guidance.Methods:A retrospective observational study was conducted on biopsy-proven autoimmune hepatitis patients who were treated for 2 years and with persistently normal aspartate aminotransferase(AST)and alanine aminotransferase(ALT)or nearly so for 6 months prior to treatment withdrawal.Exclusions were:juvenile onset autoimmune hepatitis and prior treatment or use of agents other than corticosteroids and azathioprine.The primary endpoint was to define freedomfrom flare-ups for 1 year after treatment withdrawal.Results:Thirty-four consecutive subjectsmeeting study criteria were identified.Treatment withdrawal was accomplished in 24 subjects without liver-biopsy guidance and 10 had pre-treatment withdrawal liver biopsy.Demographics,immunosuppressive usage,pre-treatment cirrhosis and pre-treatment liver enzymes were similar between the two groups,and 25%had an enzyme flare-up within 12months after treatment withdrawal,which was similar in the two groups(20.8 vs 30.0%,P=0.57).Conclusions:Adults with autoimmune hepatitis and excellent response to therapy for 2 years are candidates for treatment withdrawal without the need for liver biopsy.展开更多
基金Supported by the National Natural Science Foundation of China (21076139, 21106106), Tianjin Natural Science Foundation of China (12JcQNJC3700), and Foundation of Tianjin Educational Committee of China (20100508).
文摘A numerical simulation was performed to investigate the interaction of two bubbles rising side by side in shear-thinning fluid using volume of fluid (VOF) method coupled with continuous surface force (CSF) method. By considering rheological characteristics of fluid, this approach was able to accurately capture the deformation of bubble interface, and validated by comparing with the experimental results. The rising of bubble pairs with different configurations, including horizontal alignment and oblique alignment, was simulated by the method. The influences of the bubble initial distance and the bubble alignment were studied by analyzing the bubble deformation, rising paths and flow fields surrounding bubbles. The results indicate that within certam mltlal bubble spacing of S = 3.3 (S* = SI/D, SI initial distance between bubbles, and D bubble diameter), the dynamic interaction between two bub- bles aligned horizontally shows repulsive effect that decreases with the increase of initial bubble spacing, but weakens to certain degree by the shear-thinning properties of fluid. However, the interaction between two bubbles aligned obliquely presents a repulsive effect for the small angle involved but an attractive impact for the large one, which is vet strengthened by the rheological characteristics of fluid.
基金Supported by the Knowledge Innovation Project of Chinese Academy of Sciences (No.KZCX 2-207)Zhejiang Bureau of Science and Technology (No.2007C23075)
文摘Based on research results on the impacts of solar light,seawater temperature,and nutrient available to phytoplankton growth and changes in phytoplankton physiology and assemblage,we discussed the order of influence of these factors.By clarifying the mechanisms and processes of the impacts by these factors,we have determined the rising order of the importance as solar light,seawater temperature,and nutrient silicon (Si).Therefore,for human interests in sustaining economic development,the first thing to be considered is the input of nutrient Si into the ocean,followed by seawater temperature change.
基金the National Natural Science foundation of China (No. 29928005).
文摘Systematic experimental work was conducted to investigate the solid acceleration length in a 16m long circulating fluidized bed riser with fluid cracking catalyst particles over a wide range of operating conditions. A more feasible method is proposed to determine the acceleration length from the measured axial profiles of pressure gradient (or apparent solid holdup). With this new method and large amount of experimental data, a clear picture on the variation of the acceleration length with both solid circulating rate and superficial gas velocity is obtained.It is found that the acceleration length increases generally with increasing solid flow rate and/or decreasing gas velocity. However, the trend in variation of the acceleration length with operating conditions are quite different in different operation ranges. Reasonable explanations are suggested for the observed variation patterns of acceleration length.
文摘China's relationship with Central Asia has grown manifold since the foundation of Shanghai Five in 1996, which in June 2001 became the Shanghai Cooperation Organisation. The impetus to the relationship has further been accen- tuated when China-Russia friendship treaty was signed in July 2001. The US-led war in Afghanistan against Taliban and A1-Qaeda has yet again cemented Chinese position in Central Asia, and the recently concluded Belt and Road Initiative (BRI) has undeniably dramatically underscored the strategic value of Central Asia to the west and has opened up possibilities for Chinese security, political and economic interests. Geostrategically enmeshed with Central Asia, China will remain an integral and increasingly influential player in Central Asia. This research paper contextualises China's emergence and interests in Central Asia discarding the much talked about great game thesis and asserts by analysing the rise of China in the region as an unmatched and unchallenged power which has been testified once again with the recent BRI of Beijing.
基金supported by National Natural Science Foundation of China (Grant No. 41021002)
文摘The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world's major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environrnental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.
文摘Background:Autoimmune hepatitis may flare up after treatment withdrawal,especially in those who had not achieved histological remission but had normal liver enzymes.The European Association for the Study of the Liver(EASL)and the American Association for the Study of Liver Disease(AASLD)Guidelines recommend performing liver biopsy before treatment withdrawal.The aim of the study is to define the outcome of treatment withdrawal in adults with wellcontrolled disease for 2 years with and without liver-biopsy guidance.Methods:A retrospective observational study was conducted on biopsy-proven autoimmune hepatitis patients who were treated for 2 years and with persistently normal aspartate aminotransferase(AST)and alanine aminotransferase(ALT)or nearly so for 6 months prior to treatment withdrawal.Exclusions were:juvenile onset autoimmune hepatitis and prior treatment or use of agents other than corticosteroids and azathioprine.The primary endpoint was to define freedomfrom flare-ups for 1 year after treatment withdrawal.Results:Thirty-four consecutive subjectsmeeting study criteria were identified.Treatment withdrawal was accomplished in 24 subjects without liver-biopsy guidance and 10 had pre-treatment withdrawal liver biopsy.Demographics,immunosuppressive usage,pre-treatment cirrhosis and pre-treatment liver enzymes were similar between the two groups,and 25%had an enzyme flare-up within 12months after treatment withdrawal,which was similar in the two groups(20.8 vs 30.0%,P=0.57).Conclusions:Adults with autoimmune hepatitis and excellent response to therapy for 2 years are candidates for treatment withdrawal without the need for liver biopsy.