Colorectal cancer is one of the most common malignant tumors worldwide. A model of cancer development involving cancer stem cells has been put forward because it provides a possible explanation of tumor hierarchy. Can...Colorectal cancer is one of the most common malignant tumors worldwide. A model of cancer development involving cancer stem cells has been put forward because it provides a possible explanation of tumor hierarchy. Cancer stem cells are characterized by their proliferation, tumorigenesis, differentiation, and selfrenewal capacities, and chemoradiotherapy resistance. Due to the role of cancer stem cells in tumor initiation and treatment failure, studies of cancer stem cell markers, such as CD133, have been of great interest. CD133, a five-transmembrane glycoprotein, is widely used as a marker to identify and isolate colorectal cancer stem cells. This marker has been investigated to better understand the characteristics and functions of cancer stem cells. Moreover, it can also be used to predict tumor progression, patient survival, chemoradiotherapy resistance and other clinical parameters. In this review, we discuss the use of CD133 in the identification of colorectal cancer stem cell, which is currently controversial. Although the function of CD133 is as yet unclear, we have discussed several possible functions and associated mechanisms that may partially explain the role of CD133 in colorectal cancers. In addition, we focus on the prognostic value of CD133 in colorectal cancers. Finally, we predict that CD133 may be used as a possible target for colorectal cancer treatment.展开更多
Paired immunoglobulin-like receptor B(Pir B) is a functional receptor of myelin-associated inhibitors for axonal regeneration and synaptic plasticity in the central nervous system, and thus suppresses nerve regenera...Paired immunoglobulin-like receptor B(Pir B) is a functional receptor of myelin-associated inhibitors for axonal regeneration and synaptic plasticity in the central nervous system, and thus suppresses nerve regeneration. The regulatory effect of Pir B on injured nerves has received a lot of attention. To better understand nerve regeneration inability after spinal cord injury, this study aimed to investigate the distribution of Pir B(via immunofluorescence) in the central nervous system and peripheral nervous system 10 days after injury. Immunoreactivity for Pir B increased in the dorsal root ganglia, sciatic nerves, and spinal cord segments. In the dorsal root ganglia and sciatic nerves, Pir B was mainly distributed along neuronal and axonal membranes. Pir B was found to exhibit a diffuse, intricate distribution in the dorsal and ventral regions. Immunoreactivity for Pir B was enhanced in some cortical neurons located in the bilateral precentral gyri. Overall, the findings suggest a pattern of Pir B immunoreactivity in the nervous system after unilateral spinal transection injury, and also indicate that Pir B may suppress repair after injury.展开更多
The transient receptor potential cation channel subfamily V member 1(TRPV1) provides the sensation of pain(nociception). However, it remains unknown whether TRPV1 is activated after peripheral nerve injury, or whe...The transient receptor potential cation channel subfamily V member 1(TRPV1) provides the sensation of pain(nociception). However, it remains unknown whether TRPV1 is activated after peripheral nerve injury, or whether activation of TRPV1 affects neural regeneration. In the present study, we established rat models of unilateral sciatic nerve crush injury, with or without pretreatment with AMG517(300 mg/kg), a TRPV1 antagonist, injected subcutaneously into the ipsilateral paw 60 minutes before injury. At 1 and 2 weeks after injury, we performed immunofluorescence staining of the sciatic nerve at the center of injury, at 0.3 cm proximal and distal to the injury site, and in the dorsal root ganglia. Our results showed that Wallerian degeneration occurred distal to the injury site, and neurite outgrowth and Schwann cell regeneration occurred proximal to the injury. The number of regenerating myelinated and unmyelinated nerve clusters was greater in the AMG517-pretreated rats than in the vehicle-treated group, most notably 2 weeks after injury. TRPV1 expression in the injured sciatic nerve and ipsilateral dorsal root ganglia was markedly greater than on the contralateral side. Pretreatment with AMG517 blocked this effect. These data indicate that TRPV1 is activated or overexpressed after sciatic nerve crush injury, and that blockade of TRPV1 may accelerate regeneration of the injured sciatic nerve.展开更多
Aims Nitrogen(N)-fixing legumes,despite being highly phosphorus(P)-demanding,constitute an important plant functional group and play key roles in N-poor ecosystems such as alpine grasslands.However,legume performance,...Aims Nitrogen(N)-fixing legumes,despite being highly phosphorus(P)-demanding,constitute an important plant functional group and play key roles in N-poor ecosystems such as alpine grasslands.However,legume performance,including biomass,abundance and species richness,is expected to change,because anthropogenic activities have drastically increased soil N and P availability world-wide.We conducted a field experiment to assess the effects of N and P addition,alone and in combination,on legume performance in an alpine grassland,and identified and clarified the mechanisms underlying these changes.Methods A three year field experiment of N addition(10 g N m−2 year−1),P addition(5 g P m−2 year−1),and N+P combined addition(both N and P,same amounts as solo treatments)was conducted in an alpine grassland on the tibetan Plateau in china from 2011 to 2013.Effects of nutrient addition were assessed at the community level(above-ground net primary production(ANPP),height and light intensity),functional group level(biomass,species richness,relative height,relative coverage and relative density of legumes)and species level(foliar N,P concentration of two legumes).Important findings Overall,adding N alone significantly increased ANPP by 20.82%,but adding P alone did not;whereas,addition of N and P together resulted in a large increase in ANPP(+37.03%)than addition of either alone,indicating potential co-limitation of alpine grasslands.In contrast,adding P alone significantly promoted legume perfor-mance as measured by 65.22%increase in biomass and 58.45%increase in relative abundance,while adding N alone reduced leg-ume performance as measured by 39.54%decrease in biomass and 50.36%in relative abundance.combining P and N addition did not mitigate the negative effect of N addition on legume performance and,surprisingly,suppressed legume biomass by 53.14%and relative abundance by 63.51%.N and P addition altered the balance of light competition between grasses and legumes as indicated by the changes in light levels,plant heights and litter accumulation.However,there were no obvious changes in legume species richness in response to N and P within our experimental timeframe.this study provides further evidence of the importance of P as a co-limiting nutrient in alpine grasslands,contrary to the traditional view that N limitation predominates in such regions.the contrasting effects of N and P addition on legume performance provide important insights into potential changes in legume performance in nutrient-limited grasslands following N and P enrichment under climate change,with implications for nutrient management in alpine grasslands.展开更多
Age structure and seasonality influence the population fluctuations of small rodents.Age determines body weight and social experience,while seasonality regulates the duration of the breeding season and onset of sex...Age structure and seasonality influence the population fluctuations of small rodents.Age determines body weight and social experience,while seasonality regulates the duration of the breeding season and onset of sexual maturity in newborn offspring.Therefore,reproductive success and skew usually occur in different age groups.Brandt’s vole(Lasiopodomys brandtii)is a social,short-lived and seasonal breeding small rodent with a dramatic seasonal population fluctuation,but reproductive skew is not fully understood in this species.In the present study,we determined kinship in semi-natural enclosure populations using microsatellite markers based on genotyping,analyzed the reproductive skew between sexes and between overwintered and newborn voles,and monitored variation in male reproductive activity by testing fecal testosterone levels throughout the year.Overwintered voles had the most reproductive success along with a striking increase in the population size in the enclosures,with all biological fathers and 77.8%of biological mothers,which had 100%and 87%of the total offspring,respectively.Compared to overwintered voles,reproductive skews were significantly higher in potential overwintered and newborn parents,implying the possible reproductive suppression of newborn voles by dominant overwintered voles.Moreover,both heavier body weight and higher testosterone levels in overwintered males supported their potential social status in the population.Our study provided new evidence for reproductive skew and differentiation of postnatal gonadal development patterns of different age groups in Brandt’s vole.展开更多
To identify the unknown proteins that would contaminate the α- and β-subunits of nitrogenase MoFe protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the partially purified MoFe prote...To identify the unknown proteins that would contaminate the α- and β-subunits of nitrogenase MoFe protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the partially purified MoFe protein (Avl) preparation was obtained from Azotobacter vinelandii Lipmann OP by chroma- tography on DEAE-cellulose (DE52) and Sephacryl S-200 columns and analyzed by PAGE and matrix- assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The Av 1 preparation was shown to have two main bands at the position of the α- and β-subunits of crystalline Avl on the SDS gel. However, on the anoxic native PAGE, in addition to the Avl band, the preparation was shown to have three other main bands that migrated slower than Av 1. Of these three main bands, the protein with the fastest migration was identified as bacterioferritin elsewhere. The proteins on the other two bands, termed Upper and Middle, were suggested to be two different homopolymers with the same apparent subunit electrophoretic mobilities as the α- and β-subunits of Avl, respectively. By analysis of MALDI-TOF mass spectrometry, the Upper was identified as GroEL, which belongs to the heat shock protein 60 family, and the Middle was identified as glucose-6-phosphate isomerase (PGI). In our preparation, anoxic native electrophoresis indicated that GroEL was composed of 14 identical subunits and that PGI was composed of 10 identical subunits. This is the first report of PGI, with so many subunits. The contaminating proteins in the Av 1 preparation, mainly GroEL and PGI, could be totally or partially removed from Av 1 if the shoulders and center of the elution peak were collected separately from the Sephacryl S-200 column and the center fraction was purified further by Q-Sepharose developed with an NaC1 concentration gradient. Thus, Avl with more than 90% purity was obtained. Obviously, this modified method is useful for the purification of mutant MoFe proteins with a high purity.展开更多
Photothermal therapy(PTT)is emerging as an effective treatment for superficial carcinoma.A key challenge to the effectiveness of PTT is to develop photosensitizers with high photothermal conversion efficiency.Aiming t...Photothermal therapy(PTT)is emerging as an effective treatment for superficial carcinoma.A key challenge to the effectiveness of PTT is to develop photosensitizers with high photothermal conversion efficiency.Aiming to address this challenge,we develop a series of multi-arylpyrrole derivatives with different donors that contain different multi-rotor structures to explore highly efficient PTT photosensitizers.Among these multi-arylpyrrole derivatives,MAP4-FE nanoparticles with a small size of their donor groups and better-donating ability exhibit a high photothermal conversion efficiency(up to 72%)when they are encapsulated by an amphiphilic polymer.As a result,the MAP4-FE nanoparticles have shown satisfactory PTTeffects on in vivo tumor eradication under the guidance of photoacoustic signals.The findings of this study provide significant insights for the development of high-efficiency PTT photosensitizers for cancer treatment by making full use of the nonradiative decay of small size donors as rotors.展开更多
Using minute data of eligible A+H stocks under the Shanghai-Hong Kong Stock Connect(SHHKSC),we investigate the volatility spillover between the Shanghai and Hong Kong stock markets based on a generalized autoregressiv...Using minute data of eligible A+H stocks under the Shanghai-Hong Kong Stock Connect(SHHKSC),we investigate the volatility spillover between the Shanghai and Hong Kong stock markets based on a generalized autoregressive conditional heteroskedasticity-X(GARCH-X)model with four exogenous variables,namely,volatilities of the corresponding stocks on the other market,volatilities of the indexes of both stock markets,and volatilities of the correlated stocks,which are selected using the dynamic conditional correlation model and bootstrap approach.Results show that after the launch of the SHHKSC,volatility spillovers are significant in both directions almost all the time,and the volatility spillover between the two stock markets tends to be larger when bidirectional capital flows under the SHHKSC increase or when important financial events occur.We also analyze the influences of the volatilities of correlated stocks and industries on the volatility spillover and volatilities of A+H stocks.The bidirectional volatility spillovers between Shanghai and Hong Kong stock markets do not change qualitatively after incorporating the volatilities of correlated stocks and industries in the GARCH-X model.Moreover,the average volatilities of the correlated stocks are shown to have significant influences on the volatilities of individual A+H stocks,and the influences increase when the local stock market shows a sharp rise or fall.Compared with the market indexes,the correlated stocks could be regarded as a more important and indispensable factor for individual A+H stocks’volatilities modeling,which may carry more information than the industry.展开更多
We report on a quantum dot quantum cascade detector(QD-QCD), whose structure is derived from a QD cascade laser. In this structure, more ordered In As QD layers formed in the Stranski-Krastanow growth mode on a thin...We report on a quantum dot quantum cascade detector(QD-QCD), whose structure is derived from a QD cascade laser. In this structure, more ordered In As QD layers formed in the Stranski-Krastanow growth mode on a thin Ga As buffer layer are incorporated into the active region. This QD-QCD can operate up to room temperature with a peak detection wavelength of 5.8 μm. A responsivity of 3.1 mA/W at 160 K and a detectivity of 3.6 × 10~8 Jones at 77 K are obtained. The initial performance of the detector is promising, and, by further optimizing the growth of InA s QDs, integrated QD-quantum cascade laser/QCD applications are expected.展开更多
An integrated and systematic database of sooting tendency with more than 190 kinds of fuels was obtained through a series of experimental investigations. The laser-induced incandescence (LII) method was used to acquir...An integrated and systematic database of sooting tendency with more than 190 kinds of fuels was obtained through a series of experimental investigations. The laser-induced incandescence (LII) method was used to acquire the 2D distribution of soot volume fraction, and an apparatus-independent yield sooting index (YSI) was experimentally obtained. Based on the database, a novel predicting model of YSI values for surrogate fuels was proposed with the application of a machine learning method, named the Bayesian multiple kernel learning (BMKL) model. A high correlation coefficient (0.986) between measured YSIs and predicted values with the BMKL model was obtained, indicating that the BMKL model had a reliable and accurate predictive capacity for YSI values of surrogate fuels. The BMKL model provides an accurate and low-cost approach to assess surrogate performances of diesel, jet fuel, and biodiesel in terms of sooting tendency. Particularly, this model is one of the first attempts to predict the sooting tendencies of surrogate fuels that concurrently contain hydrocarbon and oxygenated components and shows a satisfying matching level. During surrogate formulation, the BMKL model can be used to shrink the surrogate candidate list in terms of sooting tendency and ensure the optimal surrogate has a satisfying matching level of soot behaviors. Due to the high accuracy and resolution of YSI prediction, the BMKL model is also capable of providing distinguishing information of sooting tendency for surrogate design.展开更多
基金Supported by Clinical Key Discipline Fund by Ministry of Health(2010-2012)Chinese National Clinical Key Discipline(2011-2012)the Shanghai Science and Technology Commission of Shanghai Municipality,No.10DJ1400500
文摘Colorectal cancer is one of the most common malignant tumors worldwide. A model of cancer development involving cancer stem cells has been put forward because it provides a possible explanation of tumor hierarchy. Cancer stem cells are characterized by their proliferation, tumorigenesis, differentiation, and selfrenewal capacities, and chemoradiotherapy resistance. Due to the role of cancer stem cells in tumor initiation and treatment failure, studies of cancer stem cell markers, such as CD133, have been of great interest. CD133, a five-transmembrane glycoprotein, is widely used as a marker to identify and isolate colorectal cancer stem cells. This marker has been investigated to better understand the characteristics and functions of cancer stem cells. Moreover, it can also be used to predict tumor progression, patient survival, chemoradiotherapy resistance and other clinical parameters. In this review, we discuss the use of CD133 in the identification of colorectal cancer stem cell, which is currently controversial. Although the function of CD133 is as yet unclear, we have discussed several possible functions and associated mechanisms that may partially explain the role of CD133 in colorectal cancers. In addition, we focus on the prognostic value of CD133 in colorectal cancers. Finally, we predict that CD133 may be used as a possible target for colorectal cancer treatment.
基金supported by the National Natural Science Foundation of China,No.81171178the Natural Science Foundation of Shanxi Province in China,No.2012011036-3the Research Project of Shanxi Scholarship Council of China,No.2012-047
文摘Paired immunoglobulin-like receptor B(Pir B) is a functional receptor of myelin-associated inhibitors for axonal regeneration and synaptic plasticity in the central nervous system, and thus suppresses nerve regeneration. The regulatory effect of Pir B on injured nerves has received a lot of attention. To better understand nerve regeneration inability after spinal cord injury, this study aimed to investigate the distribution of Pir B(via immunofluorescence) in the central nervous system and peripheral nervous system 10 days after injury. Immunoreactivity for Pir B increased in the dorsal root ganglia, sciatic nerves, and spinal cord segments. In the dorsal root ganglia and sciatic nerves, Pir B was mainly distributed along neuronal and axonal membranes. Pir B was found to exhibit a diffuse, intricate distribution in the dorsal and ventral regions. Immunoreactivity for Pir B was enhanced in some cortical neurons located in the bilateral precentral gyri. Overall, the findings suggest a pattern of Pir B immunoreactivity in the nervous system after unilateral spinal transection injury, and also indicate that Pir B may suppress repair after injury.
基金supported by the National Natural Science Foundation of China,No.81171178the Natural Science Foundation of Shanxi Province in China,No.2012011036-3Scientific Research Foundation of Shanxi Province of China for the Returned Overseas Chinese Scholars,No.2013011054-2
文摘The transient receptor potential cation channel subfamily V member 1(TRPV1) provides the sensation of pain(nociception). However, it remains unknown whether TRPV1 is activated after peripheral nerve injury, or whether activation of TRPV1 affects neural regeneration. In the present study, we established rat models of unilateral sciatic nerve crush injury, with or without pretreatment with AMG517(300 mg/kg), a TRPV1 antagonist, injected subcutaneously into the ipsilateral paw 60 minutes before injury. At 1 and 2 weeks after injury, we performed immunofluorescence staining of the sciatic nerve at the center of injury, at 0.3 cm proximal and distal to the injury site, and in the dorsal root ganglia. Our results showed that Wallerian degeneration occurred distal to the injury site, and neurite outgrowth and Schwann cell regeneration occurred proximal to the injury. The number of regenerating myelinated and unmyelinated nerve clusters was greater in the AMG517-pretreated rats than in the vehicle-treated group, most notably 2 weeks after injury. TRPV1 expression in the injured sciatic nerve and ipsilateral dorsal root ganglia was markedly greater than on the contralateral side. Pretreatment with AMG517 blocked this effect. These data indicate that TRPV1 is activated or overexpressed after sciatic nerve crush injury, and that blockade of TRPV1 may accelerate regeneration of the injured sciatic nerve.
文摘Aims Nitrogen(N)-fixing legumes,despite being highly phosphorus(P)-demanding,constitute an important plant functional group and play key roles in N-poor ecosystems such as alpine grasslands.However,legume performance,including biomass,abundance and species richness,is expected to change,because anthropogenic activities have drastically increased soil N and P availability world-wide.We conducted a field experiment to assess the effects of N and P addition,alone and in combination,on legume performance in an alpine grassland,and identified and clarified the mechanisms underlying these changes.Methods A three year field experiment of N addition(10 g N m−2 year−1),P addition(5 g P m−2 year−1),and N+P combined addition(both N and P,same amounts as solo treatments)was conducted in an alpine grassland on the tibetan Plateau in china from 2011 to 2013.Effects of nutrient addition were assessed at the community level(above-ground net primary production(ANPP),height and light intensity),functional group level(biomass,species richness,relative height,relative coverage and relative density of legumes)and species level(foliar N,P concentration of two legumes).Important findings Overall,adding N alone significantly increased ANPP by 20.82%,but adding P alone did not;whereas,addition of N and P together resulted in a large increase in ANPP(+37.03%)than addition of either alone,indicating potential co-limitation of alpine grasslands.In contrast,adding P alone significantly promoted legume perfor-mance as measured by 65.22%increase in biomass and 58.45%increase in relative abundance,while adding N alone reduced leg-ume performance as measured by 39.54%decrease in biomass and 50.36%in relative abundance.combining P and N addition did not mitigate the negative effect of N addition on legume performance and,surprisingly,suppressed legume biomass by 53.14%and relative abundance by 63.51%.N and P addition altered the balance of light competition between grasses and legumes as indicated by the changes in light levels,plant heights and litter accumulation.However,there were no obvious changes in legume species richness in response to N and P within our experimental timeframe.this study provides further evidence of the importance of P as a co-limiting nutrient in alpine grasslands,contrary to the traditional view that N limitation predominates in such regions.the contrasting effects of N and P addition on legume performance provide important insights into potential changes in legume performance in nutrient-limited grasslands following N and P enrichment under climate change,with implications for nutrient management in alpine grasslands.
基金the National Nature Science Foundation of China(31471790)the Agricultural Agricultural Science and Technology Innovation Program(National Key Technology R&D Program,2012BAD19B02)the National Basic Research Program of China(973 Program,2007CB109104)。
文摘Age structure and seasonality influence the population fluctuations of small rodents.Age determines body weight and social experience,while seasonality regulates the duration of the breeding season and onset of sexual maturity in newborn offspring.Therefore,reproductive success and skew usually occur in different age groups.Brandt’s vole(Lasiopodomys brandtii)is a social,short-lived and seasonal breeding small rodent with a dramatic seasonal population fluctuation,but reproductive skew is not fully understood in this species.In the present study,we determined kinship in semi-natural enclosure populations using microsatellite markers based on genotyping,analyzed the reproductive skew between sexes and between overwintered and newborn voles,and monitored variation in male reproductive activity by testing fecal testosterone levels throughout the year.Overwintered voles had the most reproductive success along with a striking increase in the population size in the enclosures,with all biological fathers and 77.8%of biological mothers,which had 100%and 87%of the total offspring,respectively.Compared to overwintered voles,reproductive skews were significantly higher in potential overwintered and newborn parents,implying the possible reproductive suppression of newborn voles by dominant overwintered voles.Moreover,both heavier body weight and higher testosterone levels in overwintered males supported their potential social status in the population.Our study provided new evidence for reproductive skew and differentiation of postnatal gonadal development patterns of different age groups in Brandt’s vole.
文摘To identify the unknown proteins that would contaminate the α- and β-subunits of nitrogenase MoFe protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the partially purified MoFe protein (Avl) preparation was obtained from Azotobacter vinelandii Lipmann OP by chroma- tography on DEAE-cellulose (DE52) and Sephacryl S-200 columns and analyzed by PAGE and matrix- assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The Av 1 preparation was shown to have two main bands at the position of the α- and β-subunits of crystalline Avl on the SDS gel. However, on the anoxic native PAGE, in addition to the Avl band, the preparation was shown to have three other main bands that migrated slower than Av 1. Of these three main bands, the protein with the fastest migration was identified as bacterioferritin elsewhere. The proteins on the other two bands, termed Upper and Middle, were suggested to be two different homopolymers with the same apparent subunit electrophoretic mobilities as the α- and β-subunits of Avl, respectively. By analysis of MALDI-TOF mass spectrometry, the Upper was identified as GroEL, which belongs to the heat shock protein 60 family, and the Middle was identified as glucose-6-phosphate isomerase (PGI). In our preparation, anoxic native electrophoresis indicated that GroEL was composed of 14 identical subunits and that PGI was composed of 10 identical subunits. This is the first report of PGI, with so many subunits. The contaminating proteins in the Av 1 preparation, mainly GroEL and PGI, could be totally or partially removed from Av 1 if the shoulders and center of the elution peak were collected separately from the Sephacryl S-200 column and the center fraction was purified further by Q-Sepharose developed with an NaC1 concentration gradient. Thus, Avl with more than 90% purity was obtained. Obviously, this modified method is useful for the purification of mutant MoFe proteins with a high purity.
基金financially supported by the National Natural Science Foundation of China(21875019,21803007,21975020,51803009)the National Key Research and Development Program of China(2018YFA0901800)+1 种基金the Department of Science and Technology of Guangdong Province(2019ZT08Y191)the Shenzhen Science and Technology Program(JSGG20200225151916021)。
文摘Photothermal therapy(PTT)is emerging as an effective treatment for superficial carcinoma.A key challenge to the effectiveness of PTT is to develop photosensitizers with high photothermal conversion efficiency.Aiming to address this challenge,we develop a series of multi-arylpyrrole derivatives with different donors that contain different multi-rotor structures to explore highly efficient PTT photosensitizers.Among these multi-arylpyrrole derivatives,MAP4-FE nanoparticles with a small size of their donor groups and better-donating ability exhibit a high photothermal conversion efficiency(up to 72%)when they are encapsulated by an amphiphilic polymer.As a result,the MAP4-FE nanoparticles have shown satisfactory PTTeffects on in vivo tumor eradication under the guidance of photoacoustic signals.The findings of this study provide significant insights for the development of high-efficiency PTT photosensitizers for cancer treatment by making full use of the nonradiative decay of small size donors as rotors.
基金supported by the National Natural Science Foundation(Nos.10905023,71131007,71532009 and 71790594)Humanities and Social Sciences Fund sponsored by Ministry of Education of the People’s Republic of China(No.17YJAZH067)the Fundamental Research Funds for the Central Universities(2015).
文摘Using minute data of eligible A+H stocks under the Shanghai-Hong Kong Stock Connect(SHHKSC),we investigate the volatility spillover between the Shanghai and Hong Kong stock markets based on a generalized autoregressive conditional heteroskedasticity-X(GARCH-X)model with four exogenous variables,namely,volatilities of the corresponding stocks on the other market,volatilities of the indexes of both stock markets,and volatilities of the correlated stocks,which are selected using the dynamic conditional correlation model and bootstrap approach.Results show that after the launch of the SHHKSC,volatility spillovers are significant in both directions almost all the time,and the volatility spillover between the two stock markets tends to be larger when bidirectional capital flows under the SHHKSC increase or when important financial events occur.We also analyze the influences of the volatilities of correlated stocks and industries on the volatility spillover and volatilities of A+H stocks.The bidirectional volatility spillovers between Shanghai and Hong Kong stock markets do not change qualitatively after incorporating the volatilities of correlated stocks and industries in the GARCH-X model.Moreover,the average volatilities of the correlated stocks are shown to have significant influences on the volatilities of individual A+H stocks,and the influences increase when the local stock market shows a sharp rise or fall.Compared with the market indexes,the correlated stocks could be regarded as a more important and indispensable factor for individual A+H stocks’volatilities modeling,which may carry more information than the industry.
基金supported by the National Basic Research Program of China(No.2013CB632804/02)the National Natural Science Foundation of China(Nos.61376501,61404131,and 11274301)
文摘We report on a quantum dot quantum cascade detector(QD-QCD), whose structure is derived from a QD cascade laser. In this structure, more ordered In As QD layers formed in the Stranski-Krastanow growth mode on a thin Ga As buffer layer are incorporated into the active region. This QD-QCD can operate up to room temperature with a peak detection wavelength of 5.8 μm. A responsivity of 3.1 mA/W at 160 K and a detectivity of 3.6 × 10~8 Jones at 77 K are obtained. The initial performance of the detector is promising, and, by further optimizing the growth of InA s QDs, integrated QD-quantum cascade laser/QCD applications are expected.
基金supported by the National Natural Science Foundation of China(Grant No.52071216)the Shanghai Rising-Star Program.
文摘An integrated and systematic database of sooting tendency with more than 190 kinds of fuels was obtained through a series of experimental investigations. The laser-induced incandescence (LII) method was used to acquire the 2D distribution of soot volume fraction, and an apparatus-independent yield sooting index (YSI) was experimentally obtained. Based on the database, a novel predicting model of YSI values for surrogate fuels was proposed with the application of a machine learning method, named the Bayesian multiple kernel learning (BMKL) model. A high correlation coefficient (0.986) between measured YSIs and predicted values with the BMKL model was obtained, indicating that the BMKL model had a reliable and accurate predictive capacity for YSI values of surrogate fuels. The BMKL model provides an accurate and low-cost approach to assess surrogate performances of diesel, jet fuel, and biodiesel in terms of sooting tendency. Particularly, this model is one of the first attempts to predict the sooting tendencies of surrogate fuels that concurrently contain hydrocarbon and oxygenated components and shows a satisfying matching level. During surrogate formulation, the BMKL model can be used to shrink the surrogate candidate list in terms of sooting tendency and ensure the optimal surrogate has a satisfying matching level of soot behaviors. Due to the high accuracy and resolution of YSI prediction, the BMKL model is also capable of providing distinguishing information of sooting tendency for surrogate design.