Synthetic biology is a new interdisciplinary research area that uses engineering principles as guidelines for biological investigation.With research goals to modify existing biological systems or to create new ones,th...Synthetic biology is a new interdisciplinary research area that uses engineering principles as guidelines for biological investigation.With research goals to modify existing biological systems or to create new ones,the recent applications of synthetic biology have expanded approaches and tools for conventional biological research.In this article,we first briefly review the development and progress of synthetic biology over the past decade.Although the contributions of synthetic biology to basic life science research,human health,environmental protection,and even economic growth have been widely observed,potential biosafety,biosecurity,and ethical risks related to synthetic biology have also emerged in recent years as technology becomes less expensive,more mature,and more accessible.We provide a brief assessment of the risks associated with the possible misuse or abuse of this technology in various areas and discuss concerns from three points of view:biosafety,biosecurity risks,and ethics.Finally,to address challenges arising from the rapid progress of synthetic biology,technical,ethical,and regulatory measures were developed or discussed in recent years,including laboratory level precautionary measures for biosafety and biosecurity related to synthetic biology(such as genetic safeguards and firewalls),ethical codes of conduct for biological scientists,and regulations or oversight rules from personal,national,and international perspectives.A brief summary of these efforts is provided.展开更多
He and Ar isotopic compositions of megacrystal minerals from mantle xenoliths were measured by the technique of vacuum crushing extraction. The used samples were clinopyroxene, garnet and ilmenite in Cenozoic alkaline...He and Ar isotopic compositions of megacrystal minerals from mantle xenoliths were measured by the technique of vacuum crushing extraction. The used samples were clinopyroxene, garnet and ilmenite in Cenozoic alkaline basalts, which were from Nushan in Anhui Province and Yingfengling in Guangdong Province, respectively, and represented materials from the upper mantle in the continental margin of SE China. The results show 3He/4He ratios of 7.99 Ra to 8.58 Ra, consistent with the characteristic ratios of the MORB-type mantle. 40Ar/39Ar ratios vary from 313 to 909, suggesting a binary mixing between the MORB-type mantle and air argons. This may reflect the incorporation of the air argon absorbed in oceanic sediments into the mantle beneath the continental margin by subduction of oceanic plate. This study presents the first report that ilmenite megacrysts contain abundant fluid inclusions and noble gases in the mantle xenoliths.展开更多
The recurrent extreme El Niño events are commonly linked to reduced vegetation growth and the land carbon sink over many but discrete regions of the Northern Hemisphere(NH).However,we reported here a pervasive an...The recurrent extreme El Niño events are commonly linked to reduced vegetation growth and the land carbon sink over many but discrete regions of the Northern Hemisphere(NH).However,we reported here a pervasive and continuous vegetation greening and no weakened land carbon sink in the maturation phase of the 2015/2016 El Niño event over the NH(mainly in the extra-tropics),based on multiple evidences from remote sensing observations,global ecosystem model simulations and atmospheric CO_(2)inversions.We discovered a significant compensation effect of the enhanced vegetation growth in spring on subsequent summer/autumn vegetation growth that sustained vegetation greening and led to a slight increase in the land carbon sink over the spring and summer of 2015(average increases of 23.34%and 0.63%in net ecosystem exchange from two independent datasets relative to a 5-years average before the El Niño event,respectively)and spring of 2016(6.82%),especially in the extra-tropics of the NH,where the water supply during the pre-growing-season(November of the previous year to March of the current year)had a positive anomaly.This seasonal compensation effect was much stronger than that in 1997 and 1998 and significantly alleviated the adverse impacts of the 2015/2016 El Niño event on vegetation growth during its maturation phase.The legacy effect of water supply during the pre-growing-season on subsequent vegetation growth lasted up to approximately six months.Our findings highlight the role of seasonal compensation effects on mediating the land carbon sink in response to episodic extreme El Niño events.展开更多
The development of aqueous battery with dual mechanisms is now arousing more and more interest.The dual mechanisms of Zn^(2+)(de)intercalation and I^(-)/I_(2)redox bring unexpected effects.Herein,differing from previo...The development of aqueous battery with dual mechanisms is now arousing more and more interest.The dual mechanisms of Zn^(2+)(de)intercalation and I^(-)/I_(2)redox bring unexpected effects.Herein,differing from previous studies using Zn I_(2)additive,this work designs an aqueous Bi I_(3)-Zn battery with selfsupplied I^(-).Ex situ tests reveal the conversion of Bi I_(3)into Bi(discharge)and Bi OI(charge)at the 1st cycle and the dissolved I^(-)in electrolyte.The active I^(-)species enhances the specific capacity and discharge medium voltage of electrode as well as improves the generation of Zn dendrite and by-product.Furthermore,the porous hard carbon is introduced to enhance the electronic/ionic conductivity and adsorb iodine species,proven by experimental and theoretical studies.Accordingly,the well-designed Bi I_(3)-Zn battery delivers a high reversible capacity of 182 m A h g^(-1)at 0.2 A g^(-1),an excellent rate capability with 88 m A h g^(-1)at 10 A g^(-1),and an impressive cyclability with 63%capacity retention over 20 K cycles at 10 A g^(-1).An excellent electrochemical performance is obtained even at a high mass loading of 6 mg cm^(-2).Moreover,a flexible quasi-solid-state Bi I_(3)-Zn battery exhibits satisfactory battery performances.This work provides a new idea for designing high-performance aqueous battery with dual mechanisms.展开更多
Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the...Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the strength and toughness of a DZ2 axle steel at various tempering temperatures and the cause of the improvement in impact toughness was evaluated.The tempering process dramatically influenced carbide precipitation behavior,which resulted in different aspect ratios of carbides.Impact toughness improved along with the rise in tempering temperature mainly due to the increase in energy required in impact crack propagation.The characteristics of the impact crack propagation process were studied through a comprehensive analysis of stress distribution,oscilloscopic impact statistics,fracture morphology,and carbide morphology.The poor impact toughness of low-tempering-temperature specimens was attributed to the increased number of stress concentration points caused by carbide morphology in the small plastic zone during the propagation process,which resulted in a mixed distribution of brittle and ductile fractures on the fracture surface.展开更多
Based on China Family Panel Studies(CFPS)2018 data,the multiple linear regression model is used to analyze the effects of Internet use on women’s depression,and to test the robustness of the regression results.At the...Based on China Family Panel Studies(CFPS)2018 data,the multiple linear regression model is used to analyze the effects of Internet use on women’s depression,and to test the robustness of the regression results.At the same time,the effects of Internet use on mental health of women with different residence,age,marital status and physical health status are analyzed.Then,we can obtain that Internet use has a significant promoting effect on women’s mental health,while the degree of Internet use has a significant inhibitory effect on women’s mental health.In addition,the study found that women’s age,education,place of residence,marital status,length of sleep,working status and physical health status are the main factors affecting the mental health of Chinese women.In the heterogeneity investigation of residence,age,marital status and physical health status,Internet use has a greater negative impact on the Center for Epidemiological Studies Depression Scale(CES-D8)scores of women in rural areas,has a significant positive impact on the mental health of middle-aged and elderly women or women with spouses,and has a positive impact on the mental health of physically unhealthy women.Therefore,in view of women’s mental health needs and the problems existing in the use of the Internet,this paper puts forward some suggestions to further improve the overall mental health level of women.展开更多
Forest stand structure is not only a crucial factor for regulating forest functioning but also an important indicator for sustainable forest management and ecosystem services.Although there exists a few national/globa...Forest stand structure is not only a crucial factor for regulating forest functioning but also an important indicator for sustainable forest management and ecosystem services.Although there exists a few national/global structure databases for natural forests,a country-wide synthetic structure database for plantation forests over China,the world’s largest player in plantation forests,has not been achieved.In this study,we built a country-wide synthetic stand structure database by surveying more than 600 peer-reviewed literature.The database covers tree species,mean stand age,mean tree height,stand density,canopy coverage,diameter at breast height,as well as the associated ancillary in-situ topographical and soil properties.A total of 594 pub-lished studies concerning diverse forest stand structure parameters were compiled for 46 tree species.This first synthesis for stand structure of plantation forests over China supports studies on the evolution/health of plantation forests in response to rapid climate change and intensified disturbances,and benefits country-wide sustainable forest management,future afforestation or reforestation planning.Potential users include those studying forest community dynamics,regional tree growth,ecosystem stability,and health,as well as those working with conservation and sustainable management.This dataset is freely acces-sible at http://www.doi.org/10.11922/sciencedb.j00076.00091.展开更多
The purpose of this paper is to study the optimal performance for an irreversible quantum Stirling cooler with heat leak and other irreversible losses. The relationship between the optimal cooling load and the coeffic...The purpose of this paper is to study the optimal performance for an irreversible quantum Stirling cooler with heat leak and other irreversible losses. The relationship between the optimal cooling load and the coefficient of performance (COP) for the quantum Stirling cooler is derived. The maximum cooling load and the corresponding COP, as well as the maximum coefficient of performance and the corresponding cooling load are obtained. The experimental observation for the optimal region is provided.展开更多
The influence of austenitizing temperature and austenite grain size on the crystallographic characteristics and mechanical properties of transformation products was investigated in a low-alloy steel.Annealing at a low...The influence of austenitizing temperature and austenite grain size on the crystallographic characteristics and mechanical properties of transformation products was investigated in a low-alloy steel.Annealing at a lower temperature after austenitization at 1050℃ can reduce the vacancy concentration and enhance the stability of austenite,thereby determining the martensite-start(Ms)temperature and density of twin-related V1/V2 variant pairs.V1/V2 variant pairs are predominately generated by autocatalytic nucleation,which can promote transformation by self-accommodation.Annealing at 800℃ after austenitization at 1050℃ generated the highest content of V1/V2 variant pairs,which contributed to high values of strength,Charpy impact energy,and elongation.In addition to refining the austenite grain size,niobium(Nb)microalloying increases the packet boundaries of the transformation products,mainly because the refined austenite grains provide more nucleation sites for the martensitic transformation.However,the density of block boundaries decreases after austenite refinement by Nb microalloying,owing to insufficient autocatalytic nucleation.展开更多
Three series of forty-nine novel 4-(3-trifluoromethylphenyl)-2H-pyridazin-3-one derivatives are designed,synthesized,and evaluated through a Spirodela polyrrhiza test and a greenhouse test.Some compounds show 】 80% c...Three series of forty-nine novel 4-(3-trifluoromethylphenyl)-2H-pyridazin-3-one derivatives are designed,synthesized,and evaluated through a Spirodela polyrrhiza test and a greenhouse test.Some compounds show 】 80% chlorophyll inhibition of Spirodela polyrrhiza at 10 μg/mL and exhibit some herbicidal activities against Digitaria adscendens in the pre-emergence treatment at a rate of 150 g/ha.Moreover,the study of the structure-activity relationship(SAR) suggests that the appropriate bulky substituent at the right position is critical for the bleaching and herbicidal activities,which may be useful for the future design of new compounds.展开更多
Thermoacoustic engine has been concerned recently because of its advantages of no moving parts and no pollution. A prime mover is built and its characteristics of onset temperature difference, frequency and output aco...Thermoacoustic engine has been concerned recently because of its advantages of no moving parts and no pollution. A prime mover is built and its characteristics of onset temperature difference, frequency and output acoustic power are measured and analyzed. A thermoacoustic refrigerator driven by this prime mover had been tested. It may develop a temperature difference of 25 K across the regenerator and a lowest temperature of -8℃ was achieved with the frequency, input power and the static pressure 81.7 Hz, 800 W and 1 Mpa respectively.展开更多
基金This research was supported by grants from the Tianjin Social Science Federation(No.2017-03-15)the Tianjin Municipal Science and Technology Commission(No.18JCQNJC10000),and the Tianjin University Research Initiation Fund.
文摘Synthetic biology is a new interdisciplinary research area that uses engineering principles as guidelines for biological investigation.With research goals to modify existing biological systems or to create new ones,the recent applications of synthetic biology have expanded approaches and tools for conventional biological research.In this article,we first briefly review the development and progress of synthetic biology over the past decade.Although the contributions of synthetic biology to basic life science research,human health,environmental protection,and even economic growth have been widely observed,potential biosafety,biosecurity,and ethical risks related to synthetic biology have also emerged in recent years as technology becomes less expensive,more mature,and more accessible.We provide a brief assessment of the risks associated with the possible misuse or abuse of this technology in various areas and discuss concerns from three points of view:biosafety,biosecurity risks,and ethics.Finally,to address challenges arising from the rapid progress of synthetic biology,technical,ethical,and regulatory measures were developed or discussed in recent years,including laboratory level precautionary measures for biosafety and biosecurity related to synthetic biology(such as genetic safeguards and firewalls),ethical codes of conduct for biological scientists,and regulations or oversight rules from personal,national,and international perspectives.A brief summary of these efforts is provided.
基金supported by The National Natural Science Foundation of China(Grant Nos.49473175,49972062 and 40110104104).
文摘He and Ar isotopic compositions of megacrystal minerals from mantle xenoliths were measured by the technique of vacuum crushing extraction. The used samples were clinopyroxene, garnet and ilmenite in Cenozoic alkaline basalts, which were from Nushan in Anhui Province and Yingfengling in Guangdong Province, respectively, and represented materials from the upper mantle in the continental margin of SE China. The results show 3He/4He ratios of 7.99 Ra to 8.58 Ra, consistent with the characteristic ratios of the MORB-type mantle. 40Ar/39Ar ratios vary from 313 to 909, suggesting a binary mixing between the MORB-type mantle and air argons. This may reflect the incorporation of the air argon absorbed in oceanic sediments into the mantle beneath the continental margin by subduction of oceanic plate. This study presents the first report that ilmenite megacrysts contain abundant fluid inclusions and noble gases in the mantle xenoliths.
基金This study was financially supported by the National Key Research and Development Program of China(Grant No.2022YFF0801802)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0306)+2 种基金the National Natural Science Foundation of China(Grant No.42171050)the China Postdoctoral Science Foundation(Grant No.2023M730281)the State Key Laboratory of Earth Surface Processes and Resource Ecology of Beijing Normal University(Grant No.2023-KF-07).
文摘The recurrent extreme El Niño events are commonly linked to reduced vegetation growth and the land carbon sink over many but discrete regions of the Northern Hemisphere(NH).However,we reported here a pervasive and continuous vegetation greening and no weakened land carbon sink in the maturation phase of the 2015/2016 El Niño event over the NH(mainly in the extra-tropics),based on multiple evidences from remote sensing observations,global ecosystem model simulations and atmospheric CO_(2)inversions.We discovered a significant compensation effect of the enhanced vegetation growth in spring on subsequent summer/autumn vegetation growth that sustained vegetation greening and led to a slight increase in the land carbon sink over the spring and summer of 2015(average increases of 23.34%and 0.63%in net ecosystem exchange from two independent datasets relative to a 5-years average before the El Niño event,respectively)and spring of 2016(6.82%),especially in the extra-tropics of the NH,where the water supply during the pre-growing-season(November of the previous year to March of the current year)had a positive anomaly.This seasonal compensation effect was much stronger than that in 1997 and 1998 and significantly alleviated the adverse impacts of the 2015/2016 El Niño event on vegetation growth during its maturation phase.The legacy effect of water supply during the pre-growing-season on subsequent vegetation growth lasted up to approximately six months.Our findings highlight the role of seasonal compensation effects on mediating the land carbon sink in response to episodic extreme El Niño events.
基金funding from National Natural Science Foundation of China(52103053,52102312)Huxiang Young Talents of Hunan Province(2022RC1004)+1 种基金Macao Young Scholars Program(AM2021011)Foundation of State Key Laboratory of Utilization of Woody Oil Resource(GZKF202126)。
文摘The development of aqueous battery with dual mechanisms is now arousing more and more interest.The dual mechanisms of Zn^(2+)(de)intercalation and I^(-)/I_(2)redox bring unexpected effects.Herein,differing from previous studies using Zn I_(2)additive,this work designs an aqueous Bi I_(3)-Zn battery with selfsupplied I^(-).Ex situ tests reveal the conversion of Bi I_(3)into Bi(discharge)and Bi OI(charge)at the 1st cycle and the dissolved I^(-)in electrolyte.The active I^(-)species enhances the specific capacity and discharge medium voltage of electrode as well as improves the generation of Zn dendrite and by-product.Furthermore,the porous hard carbon is introduced to enhance the electronic/ionic conductivity and adsorb iodine species,proven by experimental and theoretical studies.Accordingly,the well-designed Bi I_(3)-Zn battery delivers a high reversible capacity of 182 m A h g^(-1)at 0.2 A g^(-1),an excellent rate capability with 88 m A h g^(-1)at 10 A g^(-1),and an impressive cyclability with 63%capacity retention over 20 K cycles at 10 A g^(-1).An excellent electrochemical performance is obtained even at a high mass loading of 6 mg cm^(-2).Moreover,a flexible quasi-solid-state Bi I_(3)-Zn battery exhibits satisfactory battery performances.This work provides a new idea for designing high-performance aqueous battery with dual mechanisms.
基金the National Natural Science Foundation of China(Nos.52001310 and 52130002)the National Science and Technology Major Project(No.J2019-VI-0019-0134)+1 种基金KC Wong Education Foundation(No.GJTD-2020-09)Institute of Metal Res earch Innovation Fund(No.2023-ZD01)。
文摘Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the strength and toughness of a DZ2 axle steel at various tempering temperatures and the cause of the improvement in impact toughness was evaluated.The tempering process dramatically influenced carbide precipitation behavior,which resulted in different aspect ratios of carbides.Impact toughness improved along with the rise in tempering temperature mainly due to the increase in energy required in impact crack propagation.The characteristics of the impact crack propagation process were studied through a comprehensive analysis of stress distribution,oscilloscopic impact statistics,fracture morphology,and carbide morphology.The poor impact toughness of low-tempering-temperature specimens was attributed to the increased number of stress concentration points caused by carbide morphology in the small plastic zone during the propagation process,which resulted in a mixed distribution of brittle and ductile fractures on the fracture surface.
基金funded by the National Social Science Fund of China(Grant No.23BTJ069).
文摘Based on China Family Panel Studies(CFPS)2018 data,the multiple linear regression model is used to analyze the effects of Internet use on women’s depression,and to test the robustness of the regression results.At the same time,the effects of Internet use on mental health of women with different residence,age,marital status and physical health status are analyzed.Then,we can obtain that Internet use has a significant promoting effect on women’s mental health,while the degree of Internet use has a significant inhibitory effect on women’s mental health.In addition,the study found that women’s age,education,place of residence,marital status,length of sleep,working status and physical health status are the main factors affecting the mental health of Chinese women.In the heterogeneity investigation of residence,age,marital status and physical health status,Internet use has a greater negative impact on the Center for Epidemiological Studies Depression Scale(CES-D8)scores of women in rural areas,has a significant positive impact on the mental health of middle-aged and elderly women or women with spouses,and has a positive impact on the mental health of physically unhealthy women.Therefore,in view of women’s mental health needs and the problems existing in the use of the Internet,this paper puts forward some suggestions to further improve the overall mental health level of women.
基金This project was financially supported by the National Natural Science Foundation of China[No.41922001,41530747]the National Key Research and Development Program of China[No.2016YFD060020603]the Swedish Formas.
文摘Forest stand structure is not only a crucial factor for regulating forest functioning but also an important indicator for sustainable forest management and ecosystem services.Although there exists a few national/global structure databases for natural forests,a country-wide synthetic structure database for plantation forests over China,the world’s largest player in plantation forests,has not been achieved.In this study,we built a country-wide synthetic stand structure database by surveying more than 600 peer-reviewed literature.The database covers tree species,mean stand age,mean tree height,stand density,canopy coverage,diameter at breast height,as well as the associated ancillary in-situ topographical and soil properties.A total of 594 pub-lished studies concerning diverse forest stand structure parameters were compiled for 46 tree species.This first synthesis for stand structure of plantation forests over China supports studies on the evolution/health of plantation forests in response to rapid climate change and intensified disturbances,and benefits country-wide sustainable forest management,future afforestation or reforestation planning.Potential users include those studying forest community dynamics,regional tree growth,ecosystem stability,and health,as well as those working with conservation and sustainable management.This dataset is freely acces-sible at http://www.doi.org/10.11922/sciencedb.j00076.00091.
基金This material is based upon work supported by the National Important Fundamental Research Development Program Project of China under the Contract No.G2000026301.
文摘The purpose of this paper is to study the optimal performance for an irreversible quantum Stirling cooler with heat leak and other irreversible losses. The relationship between the optimal cooling load and the coefficient of performance (COP) for the quantum Stirling cooler is derived. The maximum cooling load and the corresponding COP, as well as the maximum coefficient of performance and the corresponding cooling load are obtained. The experimental observation for the optimal region is provided.
基金financially supported by the National Key Research and Development Program of China(Grant No.2020YFB0311000)the Research Center for Iron based New Materials(School of Materials Science and Engineering,Tsinghua University&Masteel Co.Ltd.).
文摘The influence of austenitizing temperature and austenite grain size on the crystallographic characteristics and mechanical properties of transformation products was investigated in a low-alloy steel.Annealing at a lower temperature after austenitization at 1050℃ can reduce the vacancy concentration and enhance the stability of austenite,thereby determining the martensite-start(Ms)temperature and density of twin-related V1/V2 variant pairs.V1/V2 variant pairs are predominately generated by autocatalytic nucleation,which can promote transformation by self-accommodation.Annealing at 800℃ after austenitization at 1050℃ generated the highest content of V1/V2 variant pairs,which contributed to high values of strength,Charpy impact energy,and elongation.In addition to refining the austenite grain size,niobium(Nb)microalloying increases the packet boundaries of the transformation products,mainly because the refined austenite grains provide more nucleation sites for the martensitic transformation.However,the density of block boundaries decreases after austenite refinement by Nb microalloying,owing to insufficient autocatalytic nucleation.
基金support from the China 973 Program (Grant No.2010CB126103)the National Natural Science Foundation of China (Grant Nos.20572054 & 20972081)
文摘Three series of forty-nine novel 4-(3-trifluoromethylphenyl)-2H-pyridazin-3-one derivatives are designed,synthesized,and evaluated through a Spirodela polyrrhiza test and a greenhouse test.Some compounds show 】 80% chlorophyll inhibition of Spirodela polyrrhiza at 10 μg/mL and exhibit some herbicidal activities against Digitaria adscendens in the pre-emergence treatment at a rate of 150 g/ha.Moreover,the study of the structure-activity relationship(SAR) suggests that the appropriate bulky substituent at the right position is critical for the bleaching and herbicidal activities,which may be useful for the future design of new compounds.
基金the National Natural Science Foundation of China (No.59706003).
文摘Thermoacoustic engine has been concerned recently because of its advantages of no moving parts and no pollution. A prime mover is built and its characteristics of onset temperature difference, frequency and output acoustic power are measured and analyzed. A thermoacoustic refrigerator driven by this prime mover had been tested. It may develop a temperature difference of 25 K across the regenerator and a lowest temperature of -8℃ was achieved with the frequency, input power and the static pressure 81.7 Hz, 800 W and 1 Mpa respectively.
