Inverse method was used in single crystal superalloy DD6 processing simulation during solidification. Numerical modeling coupled with experiments has been used to estimate the interface heat transfer coefficient （IHT...Inverse method was used in single crystal superalloy DD6 processing simulation during solidification. Numerical modeling coupled with experiments has been used to estimate the interface heat transfer coefficient （IHTC） between the surface of slab casting and inner mold. Calculated temperature dependent values of IHTC were obtained from a numerical solution. The calculated temperatures agreed well with the measurement of cooling profile.展开更多
The directional solidification process of turbine blade sample castings was investigated in the work. Variable withdrawal rates were used in one withdrawal process and compared with the other using uniform rate. A mat...The directional solidification process of turbine blade sample castings was investigated in the work. Variable withdrawal rates were used in one withdrawal process and compared with the other using uniform rate. A mathematical model for heat radiation transfer and microstructure simulation of directional solidification process was developed based on CA-FD method. The temperature distribution and microstructure w.ere simulated and compared with the experimental results. The stray grains were predicted and compared with the experimental results. The uneven temperature distribution of platform was the main reason of the formation of stray grains.展开更多
Eucommiae Folium(EF),a traditional Chinese medicine,has been used to treat secondary hypertension,including renal hypertension and salt-sensitive hypertension,as well as hypertension caused by thoracic aortic endothel...Eucommiae Folium(EF),a traditional Chinese medicine,has been used to treat secondary hypertension,including renal hypertension and salt-sensitive hypertension,as well as hypertension caused by thoracic aortic endothelial dysfunction,a high-fat diet,and oxidized low-density lipoprotein.The antihypertensive components of EF are divided into four categories:flavonoids,iridoids,lignans,and phenylpropanoids,such as chlorogenic acid,geniposide acid and pinoresinol diglucoside.EF regulates the occurrence and development of hypertension by regulating biological processes,such as inhibiting inflammation,regulating the nitric oxide synthase pathway,reducing oxidative stress levels,regulating endothelial vasoactive factors,and lowering blood pressure.However,its molecular antihypertensive mechanisms are still unclear and require further investigation.In this review,by consulting the relevant literature on the antihypertensive effects of EF and using network pharmacology,we summarized the active ingredients and pharmacological mechanisms of EF in the treatment of hypertension to clarify how EF is associated with secondary hypertension,the related components,and underlying mechanisms.The results of the network pharmacology analysis indicated that EF treats hypertension through a multicomponent,multi-target and multi-pathway mechanism.In particular,we discussed the role of EF targets in the treatment of hypertension,including epithelial sodium channel,heat shock protein70,rhoassociated protein kinase 1,catalase,and superoxide dismutase.The relevant signal transduction pathways,the ras homolog family member A(RhoA)/Rho-associated protein kinase(ROCK)and nicotinamide adenine dinucleotide phosphate(NADPH)oxidase/eNOS/NO/Ca^(2+)pathways,are also discussed.展开更多
Osteochondral defects are caused by injury to both the articular cartilage and subchondral bone within skeletal joints. They can lead to irreversible joint damage and increase the risk of progression to osteoarthritis...Osteochondral defects are caused by injury to both the articular cartilage and subchondral bone within skeletal joints. They can lead to irreversible joint damage and increase the risk of progression to osteoarthritis. Current treatments for osteochondral injuries are not curative and only target symptoms, highlighting the need for a tissue engineering solution. Scaffold-based approaches can be used to assist osteochondral tissue regeneration, where biomaterials tailored to the properties of cartilage and bone are used to restore the defect and minimise the risk of further joint degeneration. This review captures original research studies published since 2015, on multiphasic scaffolds used to treat osteochondral defects in animal models. These studies used an extensive range of biomaterials for scaffold fabrication, consisting mainly of natural and synthetic polymers. Different methods were used to create multiphasic scaffold designs, including by integrating or fabricating multiple layers, creating gradients, or through the addition of factors such as minerals, growth factors, and cells. The studies used a variety of animals to model osteochondral defects, where rabbits were the most commonly chosen and the vast majority of studies reported small rather than large animal models. The few available clinical studies reporting cell-free scaffolds have shown promising early-stage results in osteochondral repair, but long-term follow-up is necessary to demonstrate consistency in defect restoration. Overall, preclinical studies of multiphasic scaffolds show favourable results in simultaneously regenerating cartilage and bone in animal models of osteochondral defects, suggesting that biomaterials-based tissue engineering strategies may be a promising solution.展开更多
The methanation of CO_(2) using green hydrogen not only consumes CO_(2) as a carbon resource but also stores H_(2) with high density.However,the activation of CO_(2) molecules under mild conditions is challenging due ...The methanation of CO_(2) using green hydrogen not only consumes CO_(2) as a carbon resource but also stores H_(2) with high density.However,the activation of CO_(2) molecules under mild conditions is challenging due to their inert nature.Herein,we report an efficient photothermal catalytic system using light irradiation which realizes the complete conversion of CO_(2) to methane without external heating.Over optimum bimetallic Ni Fe nanoparticles(NPs)with a Ni/Fe atomic ratio of 7,the CO_(2) conversion can reach up to 98%with a CH_(4) selectivity of 99%,and no catalyst deactivation was observed for more than 100 h,outperforming the reported catalysts.The catalytic performance is strongly dependent on the structure promoters,light absorption efficiency,Ni Fe particle sizes,and Ni/Fe ratio.The Ni Fe alloy NPs with an average size of~21 nm dispersed on alumina nanosheets are evidenced to enhance the localized surface plasmon resonance(LSPR)effect,thus efficiently triggering the CO_(2) methanation.This work emphasizes and clarifies the important role of LSPR in CO_(2) hydrogenation,which may benefit the rational utilization of CO_(2) using solar power.展开更多
The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence era desirable real saturable absorber （SA） with high power toleran...The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence era desirable real saturable absorber （SA） with high power tolerance and large modulation depth. Here, we report a type of microfiber-based MoTe2 SA fabricated by the magnetron-sputtering deposition （MSD） method. High-energy wave-breaking free soliton pulses were generated with pulse duration/pulse energy/average output power of 229 fs/2.14 nJ/57 mW in the 1.5 μm regime and 1.3 ps/13.8 nJ/ 212 mW in the 2 μm regime, respectively. To our knowledge, the generated soliton pulses at 1.5μm had the shortest pulse duration and the highest output power among the reported erbium-doped fiber lasers mode locked by transition metal dichalcogenides. Moreover, this was the first demonstration of a MoTe2-based SA in fiber lasers in the 2 ltm regime, and the pulse energy/output power are the highest in the reported thulium-doped fiber lasers mode locked by two-dlmensional materials. Our results suggest that a microfiber-based MoTe2 SA could be used as an excellent photonic device for ultrafast pulse generation, and the MSD technique opens a promising route to produce a high-performance SA with high power tolerance and large modulation depth, which are beneficial for high-energy wave-breaking free pulse generation.展开更多
A green,efficient and convenient N-heterocyclic carbene-catalyzed procedure for the synthesis of novel 2,3-dihydroquinazolin-4(1H)-one derivates via condensation of o-aminonitriles and various carbonyl compounds was d...A green,efficient and convenient N-heterocyclic carbene-catalyzed procedure for the synthesis of novel 2,3-dihydroquinazolin-4(1H)-one derivates via condensation of o-aminonitriles and various carbonyl compounds was described.展开更多
As pioneering information technology,the Internet of Things(IoT)targets at building an infrastructure of embedded devices and networks of connected objects,to offer omnipresent ecosystem and interaction across billion...As pioneering information technology,the Internet of Things(IoT)targets at building an infrastructure of embedded devices and networks of connected objects,to offer omnipresent ecosystem and interaction across billions of smart devices,sensors,and actuators.The deployment of IoT calls for decentralized power supplies,selfpowered sensors,and wireless transmission technologies,which have brought both opportunities and challenges to the existing solutions,especially when the network scales up.The Triboelectric Nanogenerators(TENGs),recently developed for mechanical energy harvesting and mechanical-to-electrical signal conversion,have the natural properties of energy and information,which have demonstrated high potentials in various applications of IoT.This context provides a comprehensive review of TENG enabled IoT and discusses the most popular and significant divisions.Firstly,the basic principle of TENG is re-examined in this article.Subsequently,a comprehensive and detailed review is given to the concept of IoT,followed by the scientific development of the TENG enabled IoT.Finally,the future of this evolving area is addressed.展开更多
Lockdown measures are essential to containing the spread of coronavirus disease 2019(COVID-19),but they will slow down economic growth by reducing industrial and commercial activities.However,the benefits of activity ...Lockdown measures are essential to containing the spread of coronavirus disease 2019(COVID-19),but they will slow down economic growth by reducing industrial and commercial activities.However,the benefits of activity control from containing the pandemic have not been examined and assessed.Here we use daily carbon dioxide(CO_(2))emission reduction in China estimated from statistical data for energy consumption and satellite data for nitrogen dioxide(NO_(2))measured by the Ozone Monitoring Instrument(OMI)as an indicator for reduced activities consecutive to a lockdown.We perform a correlation analysis to show that a 1%day-1 decrease in the rate of COVID-19 cases is associated with a reduction in daily CO_(2) emissions of 0.22%±0.02%using statistical data for energy consumption relative to emissions without COVID-19,or 0.20%±0.02%using satellite data for atmospheric column NO_(2).We estimate that swift action in China is effective in limiting the number of COVID-19 cases<100,000 with a reduction in CO_(2) emissions of up to 23%by the end of February 2020,whereas a 1-week delay would have required greater containment and a doubling of the emission reduction to meet the same goal.By analyzing the costs of health care and fatalities,we find that the benefits on public health due to reduced activities in China are 10-fold larger than the loss of gross domestic product.Our findings suggest an unprecedentedly high cost of maintaining activities and CO_(2) emissions during the COVID-19 pandemic and stress substantial benefits of containment in public health by taking early actions to reduce activities during the outbreak of COVID-19.展开更多
To investigate the fog chemistry along the Yangtze River basin, a field observation experiment was performed from Shanghai to Vv＇uhan during November 2015. Fifteen fog water samples were collected by using a three-st...To investigate the fog chemistry along the Yangtze River basin, a field observation experiment was performed from Shanghai to Vv＇uhan during November 2015. Fifteen fog water samples were collected by using a three-stage Caltech Active Strand Cloud water Collector （CASCC）. The three-stage CASCC was mounted on the board of a ship. PH, electrical conductivity （EC）, H202, HCHO, S（ll0, ten inorganic ions, seven organicacids and sixteen trace metal elements were measured in this study. The pH of fog water samples ranged from weakly acidic （pH 4.3） to weakly alkaline （pH 7.05） and the EC ranged from 32.4 to 436.3 μS/cm. The main cations in fog water were NH^4＋ and Ca2＋, accounting for 12.35% and 29.07% of those inorganic ions, respectively. In addition, SO24- and NO^-3 contributed to 25.52% and 12.93% to total anion concentrations respectively. Moreover, the dominant kinds of organicacids were formate and oxalate, occupying 45.28% and 28.03% of the total organicacids, respectively. For trace metal elements in fog samples, Al, Fe, Zn, and Ba revealed 34.6%, 16.4%, 19.3%, and 20.9% contributions to these sixteen trace element concentrations, respectively. The results indicated that pollutants were mainly from human activities, including fossil fuel combustion, biomass burning, steel-making, stone quarrying and sand digging. Besides, natural sources including natural background levels and long-range transport of sea salt particles also aggravated the pollution levels in the fog events along the Yangtze River.展开更多
基金supported by National Basic Research Program of China(No.2005CB724105)National Natural Science Foundation of China (No.10477010)National High Technical Research and Development Program of China(No.2007AA04Z141)
文摘Inverse method was used in single crystal superalloy DD6 processing simulation during solidification. Numerical modeling coupled with experiments has been used to estimate the interface heat transfer coefficient （IHTC） between the surface of slab casting and inner mold. Calculated temperature dependent values of IHTC were obtained from a numerical solution. The calculated temperatures agreed well with the measurement of cooling profile.
文摘The directional solidification process of turbine blade sample castings was investigated in the work. Variable withdrawal rates were used in one withdrawal process and compared with the other using uniform rate. A mathematical model for heat radiation transfer and microstructure simulation of directional solidification process was developed based on CA-FD method. The temperature distribution and microstructure w.ere simulated and compared with the experimental results. The stray grains were predicted and compared with the experimental results. The uneven temperature distribution of platform was the main reason of the formation of stray grains.
基金supported by the Scientific Research Project of the Tianjin Educational Committee(Project No.:2019KJ081).
文摘Eucommiae Folium(EF),a traditional Chinese medicine,has been used to treat secondary hypertension,including renal hypertension and salt-sensitive hypertension,as well as hypertension caused by thoracic aortic endothelial dysfunction,a high-fat diet,and oxidized low-density lipoprotein.The antihypertensive components of EF are divided into four categories:flavonoids,iridoids,lignans,and phenylpropanoids,such as chlorogenic acid,geniposide acid and pinoresinol diglucoside.EF regulates the occurrence and development of hypertension by regulating biological processes,such as inhibiting inflammation,regulating the nitric oxide synthase pathway,reducing oxidative stress levels,regulating endothelial vasoactive factors,and lowering blood pressure.However,its molecular antihypertensive mechanisms are still unclear and require further investigation.In this review,by consulting the relevant literature on the antihypertensive effects of EF and using network pharmacology,we summarized the active ingredients and pharmacological mechanisms of EF in the treatment of hypertension to clarify how EF is associated with secondary hypertension,the related components,and underlying mechanisms.The results of the network pharmacology analysis indicated that EF treats hypertension through a multicomponent,multi-target and multi-pathway mechanism.In particular,we discussed the role of EF targets in the treatment of hypertension,including epithelial sodium channel,heat shock protein70,rhoassociated protein kinase 1,catalase,and superoxide dismutase.The relevant signal transduction pathways,the ras homolog family member A(RhoA)/Rho-associated protein kinase(ROCK)and nicotinamide adenine dinucleotide phosphate(NADPH)oxidase/eNOS/NO/Ca^(2+)pathways,are also discussed.
基金support from the National Health and Medical Research Council(NHMRC)of Australia(GNT1120249).
文摘Osteochondral defects are caused by injury to both the articular cartilage and subchondral bone within skeletal joints. They can lead to irreversible joint damage and increase the risk of progression to osteoarthritis. Current treatments for osteochondral injuries are not curative and only target symptoms, highlighting the need for a tissue engineering solution. Scaffold-based approaches can be used to assist osteochondral tissue regeneration, where biomaterials tailored to the properties of cartilage and bone are used to restore the defect and minimise the risk of further joint degeneration. This review captures original research studies published since 2015, on multiphasic scaffolds used to treat osteochondral defects in animal models. These studies used an extensive range of biomaterials for scaffold fabrication, consisting mainly of natural and synthetic polymers. Different methods were used to create multiphasic scaffold designs, including by integrating or fabricating multiple layers, creating gradients, or through the addition of factors such as minerals, growth factors, and cells. The studies used a variety of animals to model osteochondral defects, where rabbits were the most commonly chosen and the vast majority of studies reported small rather than large animal models. The few available clinical studies reporting cell-free scaffolds have shown promising early-stage results in osteochondral repair, but long-term follow-up is necessary to demonstrate consistency in defect restoration. Overall, preclinical studies of multiphasic scaffolds show favourable results in simultaneously regenerating cartilage and bone in animal models of osteochondral defects, suggesting that biomaterials-based tissue engineering strategies may be a promising solution.
基金supported by the National Natural Science Foundation of China (92145301,22121001,22222206,and U22A20392)the Fundamental Research Funds for the Central Universities (20720220008 and 20720220021)。
文摘The methanation of CO_(2) using green hydrogen not only consumes CO_(2) as a carbon resource but also stores H_(2) with high density.However,the activation of CO_(2) molecules under mild conditions is challenging due to their inert nature.Herein,we report an efficient photothermal catalytic system using light irradiation which realizes the complete conversion of CO_(2) to methane without external heating.Over optimum bimetallic Ni Fe nanoparticles(NPs)with a Ni/Fe atomic ratio of 7,the CO_(2) conversion can reach up to 98%with a CH_(4) selectivity of 99%,and no catalyst deactivation was observed for more than 100 h,outperforming the reported catalysts.The catalytic performance is strongly dependent on the structure promoters,light absorption efficiency,Ni Fe particle sizes,and Ni/Fe ratio.The Ni Fe alloy NPs with an average size of~21 nm dispersed on alumina nanosheets are evidenced to enhance the localized surface plasmon resonance(LSPR)effect,thus efficiently triggering the CO_(2) methanation.This work emphasizes and clarifies the important role of LSPR in CO_(2) hydrogenation,which may benefit the rational utilization of CO_(2) using solar power.
基金National Natural Science Foundation of China(NSFC)(11704260,61405126,61605122,61775146)Shenzhen Science and Technology Project(JCY20150324141711695,JCYJ20160427105041864,JSGG20160429114438287,KQJSCX20160226194031,JCYJ20160422103744090)+1 种基金Beijing University of Posts and Telecommunications(BUPT)(IPOC2015B003)Natural Science Foundation of Guangdong Province(2016A030310049,2016A030310059)
文摘The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence era desirable real saturable absorber （SA） with high power tolerance and large modulation depth. Here, we report a type of microfiber-based MoTe2 SA fabricated by the magnetron-sputtering deposition （MSD） method. High-energy wave-breaking free soliton pulses were generated with pulse duration/pulse energy/average output power of 229 fs/2.14 nJ/57 mW in the 1.5 μm regime and 1.3 ps/13.8 nJ/ 212 mW in the 2 μm regime, respectively. To our knowledge, the generated soliton pulses at 1.5μm had the shortest pulse duration and the highest output power among the reported erbium-doped fiber lasers mode locked by transition metal dichalcogenides. Moreover, this was the first demonstration of a MoTe2-based SA in fiber lasers in the 2 ltm regime, and the pulse energy/output power are the highest in the reported thulium-doped fiber lasers mode locked by two-dlmensional materials. Our results suggest that a microfiber-based MoTe2 SA could be used as an excellent photonic device for ultrafast pulse generation, and the MSD technique opens a promising route to produce a high-performance SA with high power tolerance and large modulation depth, which are beneficial for high-energy wave-breaking free pulse generation.
基金Financial support from the International S&T Cooperation Program of China(No.2012DFR40240)is gratefully acknowledged.
文摘A green,efficient and convenient N-heterocyclic carbene-catalyzed procedure for the synthesis of novel 2,3-dihydroquinazolin-4(1H)-one derivates via condensation of o-aminonitriles and various carbonyl compounds was described.
文摘As pioneering information technology,the Internet of Things(IoT)targets at building an infrastructure of embedded devices and networks of connected objects,to offer omnipresent ecosystem and interaction across billions of smart devices,sensors,and actuators.The deployment of IoT calls for decentralized power supplies,selfpowered sensors,and wireless transmission technologies,which have brought both opportunities and challenges to the existing solutions,especially when the network scales up.The Triboelectric Nanogenerators(TENGs),recently developed for mechanical energy harvesting and mechanical-to-electrical signal conversion,have the natural properties of energy and information,which have demonstrated high potentials in various applications of IoT.This context provides a comprehensive review of TENG enabled IoT and discusses the most popular and significant divisions.Firstly,the basic principle of TENG is re-examined in this article.Subsequently,a comprehensive and detailed review is given to the concept of IoT,followed by the scientific development of the TENG enabled IoT.Finally,the future of this evolving area is addressed.
基金the provision of funds fromthe National Natural Science Foundation of China(41877506)the Fudan’s Wangdao Undergraduate Research Opportunities Program(18107)+1 种基金the Chinese Thousand Youth Talents Programthe Australia-China Centre for Air Quality Science and Management.
文摘Lockdown measures are essential to containing the spread of coronavirus disease 2019(COVID-19),but they will slow down economic growth by reducing industrial and commercial activities.However,the benefits of activity control from containing the pandemic have not been examined and assessed.Here we use daily carbon dioxide(CO_(2))emission reduction in China estimated from statistical data for energy consumption and satellite data for nitrogen dioxide(NO_(2))measured by the Ozone Monitoring Instrument(OMI)as an indicator for reduced activities consecutive to a lockdown.We perform a correlation analysis to show that a 1%day-1 decrease in the rate of COVID-19 cases is associated with a reduction in daily CO_(2) emissions of 0.22%±0.02%using statistical data for energy consumption relative to emissions without COVID-19,or 0.20%±0.02%using satellite data for atmospheric column NO_(2).We estimate that swift action in China is effective in limiting the number of COVID-19 cases<100,000 with a reduction in CO_(2) emissions of up to 23%by the end of February 2020,whereas a 1-week delay would have required greater containment and a doubling of the emission reduction to meet the same goal.By analyzing the costs of health care and fatalities,we find that the benefits on public health due to reduced activities in China are 10-fold larger than the loss of gross domestic product.Our findings suggest an unprecedentedly high cost of maintaining activities and CO_(2) emissions during the COVID-19 pandemic and stress substantial benefits of containment in public health by taking early actions to reduce activities during the outbreak of COVID-19.
基金supported by the National Natural Science Foundation of China (Nos. 41605113, 41375126)the Taishan Scholar Grand (No. ts20120552)
文摘To investigate the fog chemistry along the Yangtze River basin, a field observation experiment was performed from Shanghai to Vv＇uhan during November 2015. Fifteen fog water samples were collected by using a three-stage Caltech Active Strand Cloud water Collector （CASCC）. The three-stage CASCC was mounted on the board of a ship. PH, electrical conductivity （EC）, H202, HCHO, S（ll0, ten inorganic ions, seven organicacids and sixteen trace metal elements were measured in this study. The pH of fog water samples ranged from weakly acidic （pH 4.3） to weakly alkaline （pH 7.05） and the EC ranged from 32.4 to 436.3 μS/cm. The main cations in fog water were NH^4＋ and Ca2＋, accounting for 12.35% and 29.07% of those inorganic ions, respectively. In addition, SO24- and NO^-3 contributed to 25.52% and 12.93% to total anion concentrations respectively. Moreover, the dominant kinds of organicacids were formate and oxalate, occupying 45.28% and 28.03% of the total organicacids, respectively. For trace metal elements in fog samples, Al, Fe, Zn, and Ba revealed 34.6%, 16.4%, 19.3%, and 20.9% contributions to these sixteen trace element concentrations, respectively. The results indicated that pollutants were mainly from human activities, including fossil fuel combustion, biomass burning, steel-making, stone quarrying and sand digging. Besides, natural sources including natural background levels and long-range transport of sea salt particles also aggravated the pollution levels in the fog events along the Yangtze River.
