Developing cost-effective,robust and stable non-precious metal catalysts for oxygen reduction reaction(ORR) is of paramount importance for electrochemical energy conversion devices such as fuel cells and metal-air bat...Developing cost-effective,robust and stable non-precious metal catalysts for oxygen reduction reaction(ORR) is of paramount importance for electrochemical energy conversion devices such as fuel cells and metal-air batteries.Although Fe-N-C single atom catalysts(SACs) have been hailed as the most promising candidate due to the optimal binding strength of ORR intermediates on the Fe-N_(4) sites,they suffer from serious mass transport limitations as microporous templates/substrates,i.e.,zeolitic imidazolate frameworks(ZIFs),are usually employed to host the active sites.Motivated by this challenge,we herein develop a hydrogen-bonded organic framework(HOF)-assisted pyrolysis strategy to construct hierarchical micro/mesoporous carbon nanoplates for the deposition of atomically dispersed Fe-N_(4) sites.Such a design is accomplished by employing HOF nanoplates assembled from 2-aminoterephthalic acid(NH_(2)-BDC) and p-phenylenediamine(PDA) as both soft templates and C,N precursors.Benefitting from the structural merits inherited from HOF templates,the optimized catalyst(denoted as Fe-N-C SAC-950) displays outstanding ORR activity with a high half-wave potential of 0.895 V(vs.reversible hydrogen electrode(RHE)) and a small overpotential of 356 mV at 10 mA cm^(-2) for the oxygen evolution reaction(OER).More excitingly,its application potential is further verified by delivering superb rechargeability and cycling stability with a nearly unfading charge-discharge gap of 0.72 V after 160 h.Molecular dynamics(MD) simulations reveal that micro/mesoporous structure is conducive to the rapid mass transfer of O_(2),thus enhancing the ORR performance.In situ Raman results further indicate that the conversion of O_(2) to~*O_(2)-the rate-determining step(RDS) for Fe-N-C SAC-950.This work will provide a versatile strategy to construct single atom catalysts with desirable catalytic properties.展开更多
In the first half of winter 2020/21,China has experienced an extremely cold period across both northern and southern regions,with record-breaking low temperatures set in many stations of China.Meanwhile,a moderate La ...In the first half of winter 2020/21,China has experienced an extremely cold period across both northern and southern regions,with record-breaking low temperatures set in many stations of China.Meanwhile,a moderate La Niña event which exceeded both oceanic and atmospheric thresholds began in August 2020 and in a few months developed into its mature phase,just prior to the 2020/21 winter.In this report,the mid−high-latitude large-scale atmospheric circulation anomalies in the Northern Hemisphere,which were forced by the negative phase of Arctic Oscillation,a strengthened Siberian High,an intensified Ural High and a deepened East Asian Trough,are considered to be the direct reason for the frequent cold surges in winter 2020/21.At the same time,the synergistic effect of the warm Arctic and the cold tropical Pacific(La Niña)provided an indispensable background,at a hemispheric scale,to intensify the atmospheric circulation anomalies in middle-to-high latitudes.In the end,a most recent La Niña prediction is provided and the on-coming evolution of climate is discussed for the remaining part of the 2020/21 winter for the purpose of future decision-making and early warning.展开更多
High-quality AlN/sapphire templates were fabricated by the combination of sputtering and high-temperature(HT)annealing.The influence of sputtering parameters including nitrogen flux,radio frequency power,and substrate...High-quality AlN/sapphire templates were fabricated by the combination of sputtering and high-temperature(HT)annealing.The influence of sputtering parameters including nitrogen flux,radio frequency power,and substrate temperature on the crystalline quality and surface morphology of annealed AlN films were investigated.With lower substrate temperature,lower power,and lower N2 flux,the full width at half maximum of the X-ray rocking curve for AlN(0002)and(102)were improved to 97.2 and 259.2 arcsec after high-temperature annealing.This happens because the increased vacancy concentration of sputtered AlN films can facilitate the annihilation of dislocations by increasing the recovery rate during HT annealing.Step and step-bunching morphologies were clearly observed with optimized sputtering conditions.展开更多
Objective:the N-myc downstream regulatory gene 4(NDRG4)is involved in cell growth,cell proliferation,cell survival and tumor invasion.In this paper,the role of NDRG4 in glioma was explored.Method:the expression of NDR...Objective:the N-myc downstream regulatory gene 4(NDRG4)is involved in cell growth,cell proliferation,cell survival and tumor invasion.In this paper,the role of NDRG4 in glioma was explored.Method:the expression of NDRG4 in glioma clinical specimens and its relationship with the prognosis of glioma patients were analyzed by the Cancer Genome Atlas(TCGA)and the Chinese Glioma Genome Atlas(CGGA),and the expression of NDRG4 protein and mRNA in glioma cell lines were tested and verified by Western blot and quantitative real-time fluorescence polymerase chain reaction(qRT-PCR).Result:it showed that the expression of NDRG4 in glioma tissues and cell lines is closely related to the prognosis of glioma patients.Conclusion:NDRG4 is a highly potential target gene for glioma therapy.展开更多
Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbo...Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbon(M-Nx/C)catalysts are hailed as the most promising candidates to replace Pt due to their considerable oxygen reduction reaction(ORR)activity and low cost.Despite tremendous progress in terms of active site identification and activity improvement being achieved in the past few decades,the M-Nx/C catalysts still suffer from insufficient durability,which drastically limits their practical application.In this regard,understanding degradation mechanisms and customizing stabilization strategies are of significant importance yet challengeable.In this review,we summarize the recent advances in the stability improvement of M-Nx/C catalysts.The stability test protocols of the M-Nx/C are firstly introduced.Subsequently,with the combination of advanced ex situ and in situ characterization techniques and density functional theory calculation,we present a comprehensive overview of the main degradation mechanisms during ORR process.Aiming at these deactivation issues,a variety of novel improvement strategies are developed to enhance the stability of M-Nx/C.Finally,the current challenges and prospects to design highly stable M-Nx/C catalysts are also proposed.展开更多
This paper tested the viscosity of prepreg in the automatic placement process, and conducted the probe and placement-90° peel tests through the test systems. The law of variation of prepreg viscosity during the l...This paper tested the viscosity of prepreg in the automatic placement process, and conducted the probe and placement-90° peel tests through the test systems. The law of variation of prepreg viscosity during the laying process was studied through these tests under different conditions by taking the peel force to intuitively and quantitatively characterise the viscosity of the prepreg.The results show that this viscosity is inversely proportional to the laying rate, proportional to the laying pressure, and quadratic to the laying temperature. Then, peel tests were simulated to validate both the correctness of the peel test and that of the probe test data fitting the two-line cohesion model. On this basis, a response surface test for laying and peeling was designed. Taking viscous peel force as the response target, the laying process parameters were optimised and the significance of their influence was further studied. The error between the test value and the predicted value of the maximum viscous peel force is 3.03%.展开更多
We evaluated the sea surface temperature(SST)products derived from the visible infrared radiometer on board the Fengyun-3 satellites(FY-3/VIRR)during 2016-2018 from the perspective of climate applications.The data had...We evaluated the sea surface temperature(SST)products derived from the visible infrared radiometer on board the Fengyun-3 satellites(FY-3/VIRR)during 2016-2018 from the perspective of climate applications.The data had previously been reprocessed by the National Satellite Meteorological Center of China Meteorological Administration based on an updated SST retrieval algorithm.The overall consistency between the FY-3/VIRR SST data and the optimum interpolation SST version 2.1(OIv2.1)was better for monthly means than for pentad means,and showed a clear dependence on the season and location.There was better consistency in winter than in summer,and in the tropical central-eastern Pacific than in the western Pacific warm pool,tropical North Indian Ocean,and tropical Atlantic Ocean.The monthly deviation of the global average SST anomaly was-0.03±0.07℃ and the average root-meansquare errors(RMSEs)presented clear seasonal fluctuations with a maximum of approximately 0.5℃ in summer.The poor consistency of the FY-3/VIRR SST in summer may be partially attributed to the bias of the OIv2.1 data in global oceans(especially the Indian Ocean)as a result of the spatially heterogeneous in situ measurements from ships,buoys,and Argo floats.Convective activities and clouds in the tropics may also influence the accuracy of the FY-3/VIRR SST retrievals.The Nino SST indices based on both FY-3/VIRR and OIv2.1 SST data displayed a generally similar evolution,including the start and end of El Nino and La Nina events and their amplitudes,although the deviations were slightly larger when the Pacific SST anomaly was in the neutral state of the El Nino-Southern Oscillation(ENSO).The deviations varied greatly with season in the tropical Indian and Atlantic oceans,suggesting the need to perform further analyses and validation of the FY-3/VIRR SST products in these two basins.展开更多
基金financially supported by the National Key R&D Program of China(2022YFB4004100)the National Natural Science Foundation of China(22272161)+6 种基金the Jilin Province Science and Technology Development Program(20230101367JC)financially supported by the National Natural Science Foundation of China(22073094)the Science and Technology Development Program of Jilin Province(20210402059GH)the Science and Technology Plan Projects of Yunnan Province(202101BC070001–007)the Major Science and Technology Projects for Independent Innovation of China FAW Group Co.,Ltd(20220301018GX)the essential support of the Network and Computing Center,CIAC,CASthe Computing Center of Jilin Province。
文摘Developing cost-effective,robust and stable non-precious metal catalysts for oxygen reduction reaction(ORR) is of paramount importance for electrochemical energy conversion devices such as fuel cells and metal-air batteries.Although Fe-N-C single atom catalysts(SACs) have been hailed as the most promising candidate due to the optimal binding strength of ORR intermediates on the Fe-N_(4) sites,they suffer from serious mass transport limitations as microporous templates/substrates,i.e.,zeolitic imidazolate frameworks(ZIFs),are usually employed to host the active sites.Motivated by this challenge,we herein develop a hydrogen-bonded organic framework(HOF)-assisted pyrolysis strategy to construct hierarchical micro/mesoporous carbon nanoplates for the deposition of atomically dispersed Fe-N_(4) sites.Such a design is accomplished by employing HOF nanoplates assembled from 2-aminoterephthalic acid(NH_(2)-BDC) and p-phenylenediamine(PDA) as both soft templates and C,N precursors.Benefitting from the structural merits inherited from HOF templates,the optimized catalyst(denoted as Fe-N-C SAC-950) displays outstanding ORR activity with a high half-wave potential of 0.895 V(vs.reversible hydrogen electrode(RHE)) and a small overpotential of 356 mV at 10 mA cm^(-2) for the oxygen evolution reaction(OER).More excitingly,its application potential is further verified by delivering superb rechargeability and cycling stability with a nearly unfading charge-discharge gap of 0.72 V after 160 h.Molecular dynamics(MD) simulations reveal that micro/mesoporous structure is conducive to the rapid mass transfer of O_(2),thus enhancing the ORR performance.In situ Raman results further indicate that the conversion of O_(2) to~*O_(2)-the rate-determining step(RDS) for Fe-N-C SAC-950.This work will provide a versatile strategy to construct single atom catalysts with desirable catalytic properties.
基金supported by the national key R&D Program of China(Grant No 2018YFC1505603)the Key Research Program of Frontier Sciences,CAS(Grant No.ZDBS-LY-DQC010)the National Natural Science Foundation of China(Grant Nos.41876012,41861144015).
文摘In the first half of winter 2020/21,China has experienced an extremely cold period across both northern and southern regions,with record-breaking low temperatures set in many stations of China.Meanwhile,a moderate La Niña event which exceeded both oceanic and atmospheric thresholds began in August 2020 and in a few months developed into its mature phase,just prior to the 2020/21 winter.In this report,the mid−high-latitude large-scale atmospheric circulation anomalies in the Northern Hemisphere,which were forced by the negative phase of Arctic Oscillation,a strengthened Siberian High,an intensified Ural High and a deepened East Asian Trough,are considered to be the direct reason for the frequent cold surges in winter 2020/21.At the same time,the synergistic effect of the warm Arctic and the cold tropical Pacific(La Niña)provided an indispensable background,at a hemispheric scale,to intensify the atmospheric circulation anomalies in middle-to-high latitudes.In the end,a most recent La Niña prediction is provided and the on-coming evolution of climate is discussed for the remaining part of the 2020/21 winter for the purpose of future decision-making and early warning.
基金This work was supported by the National Key R&D Program of China(Nos.2016YFB0400800 and 2017YFB0404202)the National Natural Sciences Foundation of China(Grant Nos.61527814,61674147,61904176,U1505253)+1 种基金Beijing Nova Program Z181100006218007Youth Innovation Promotion Association CAS 2017157.
文摘High-quality AlN/sapphire templates were fabricated by the combination of sputtering and high-temperature(HT)annealing.The influence of sputtering parameters including nitrogen flux,radio frequency power,and substrate temperature on the crystalline quality and surface morphology of annealed AlN films were investigated.With lower substrate temperature,lower power,and lower N2 flux,the full width at half maximum of the X-ray rocking curve for AlN(0002)and(102)were improved to 97.2 and 259.2 arcsec after high-temperature annealing.This happens because the increased vacancy concentration of sputtered AlN films can facilitate the annihilation of dislocations by increasing the recovery rate during HT annealing.Step and step-bunching morphologies were clearly observed with optimized sputtering conditions.
文摘Objective:the N-myc downstream regulatory gene 4(NDRG4)is involved in cell growth,cell proliferation,cell survival and tumor invasion.In this paper,the role of NDRG4 in glioma was explored.Method:the expression of NDRG4 in glioma clinical specimens and its relationship with the prognosis of glioma patients were analyzed by the Cancer Genome Atlas(TCGA)and the Chinese Glioma Genome Atlas(CGGA),and the expression of NDRG4 protein and mRNA in glioma cell lines were tested and verified by Western blot and quantitative real-time fluorescence polymerase chain reaction(qRT-PCR).Result:it showed that the expression of NDRG4 in glioma tissues and cell lines is closely related to the prognosis of glioma patients.Conclusion:NDRG4 is a highly potential target gene for glioma therapy.
基金supported by the National Key R&D Program of China(grant no.2022YFB4004100)National Natural Science Foundation of China(grant nos.22272161 and 22179126)Jilin Province Science and Technology Development Program(grant no.20230101367JC).
文摘Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbon(M-Nx/C)catalysts are hailed as the most promising candidates to replace Pt due to their considerable oxygen reduction reaction(ORR)activity and low cost.Despite tremendous progress in terms of active site identification and activity improvement being achieved in the past few decades,the M-Nx/C catalysts still suffer from insufficient durability,which drastically limits their practical application.In this regard,understanding degradation mechanisms and customizing stabilization strategies are of significant importance yet challengeable.In this review,we summarize the recent advances in the stability improvement of M-Nx/C catalysts.The stability test protocols of the M-Nx/C are firstly introduced.Subsequently,with the combination of advanced ex situ and in situ characterization techniques and density functional theory calculation,we present a comprehensive overview of the main degradation mechanisms during ORR process.Aiming at these deactivation issues,a variety of novel improvement strategies are developed to enhance the stability of M-Nx/C.Finally,the current challenges and prospects to design highly stable M-Nx/C catalysts are also proposed.
基金supported by the National Natural Science Foundation of China(No.51875159)the Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory,China(No.XHT 2020-002)+5 种基金Fok Ying Tung Education Foundation,China(No.171046)the Key Research and Development Program of Anhui Province,China(No.201904d07020013)the Fundamental Research Funds for the Central Universities,China(Nos.PA2020GDJQ0029 and PA2020GDSK0075)the National Key Research and Development Project,China(No.2019YFB1504800)the Beijing Natural Science Foundation,China(No.2192044)2020 and 2021 Open Project of State Key Laboratory of Organic-Inorganic Composites,China(Nos.Oic-202001008 and Oic-202101008)。
文摘This paper tested the viscosity of prepreg in the automatic placement process, and conducted the probe and placement-90° peel tests through the test systems. The law of variation of prepreg viscosity during the laying process was studied through these tests under different conditions by taking the peel force to intuitively and quantitatively characterise the viscosity of the prepreg.The results show that this viscosity is inversely proportional to the laying rate, proportional to the laying pressure, and quadratic to the laying temperature. Then, peel tests were simulated to validate both the correctness of the peel test and that of the probe test data fitting the two-line cohesion model. On this basis, a response surface test for laying and peeling was designed. Taking viscous peel force as the response target, the laying process parameters were optimised and the significance of their influence was further studied. The error between the test value and the predicted value of the maximum viscous peel force is 3.03%.
基金Supported by the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Key Reseach and Development Program of China(2018YFB0504905 and 2018YFB0504900)。
文摘We evaluated the sea surface temperature(SST)products derived from the visible infrared radiometer on board the Fengyun-3 satellites(FY-3/VIRR)during 2016-2018 from the perspective of climate applications.The data had previously been reprocessed by the National Satellite Meteorological Center of China Meteorological Administration based on an updated SST retrieval algorithm.The overall consistency between the FY-3/VIRR SST data and the optimum interpolation SST version 2.1(OIv2.1)was better for monthly means than for pentad means,and showed a clear dependence on the season and location.There was better consistency in winter than in summer,and in the tropical central-eastern Pacific than in the western Pacific warm pool,tropical North Indian Ocean,and tropical Atlantic Ocean.The monthly deviation of the global average SST anomaly was-0.03±0.07℃ and the average root-meansquare errors(RMSEs)presented clear seasonal fluctuations with a maximum of approximately 0.5℃ in summer.The poor consistency of the FY-3/VIRR SST in summer may be partially attributed to the bias of the OIv2.1 data in global oceans(especially the Indian Ocean)as a result of the spatially heterogeneous in situ measurements from ships,buoys,and Argo floats.Convective activities and clouds in the tropics may also influence the accuracy of the FY-3/VIRR SST retrievals.The Nino SST indices based on both FY-3/VIRR and OIv2.1 SST data displayed a generally similar evolution,including the start and end of El Nino and La Nina events and their amplitudes,although the deviations were slightly larger when the Pacific SST anomaly was in the neutral state of the El Nino-Southern Oscillation(ENSO).The deviations varied greatly with season in the tropical Indian and Atlantic oceans,suggesting the need to perform further analyses and validation of the FY-3/VIRR SST products in these two basins.