Arctic changes influence not only temperature and precipitation in the midlatitudes but also contribute to severe convection.This study investigates an extreme gale event that occurred on 30 April 2021 in East China a...Arctic changes influence not only temperature and precipitation in the midlatitudes but also contribute to severe convection.This study investigates an extreme gale event that occurred on 30 April 2021 in East China and was forced by an Arctic potential vorticity(PV)anomaly intrusion.Temperature advection steered by storms contributed to the equatorward propagation of Arctic high PV,forming the Northeast China cold vortex(NCCV).At the upper levels,a PV southward intrusion guided the combination of the polar jet and the subtropical jet,providing strong vertical wind shear and downward momentum transportation to the event.The PV anomaly cooled the upper troposphere and the northern part of East China,whereas the lower levels over southern East China were dominated by local warm air,thus establishing strong instability and baroclinicity.In addition,the entrainment of Arctic dry air strengthened the surface pressure gradient by evaporation cooling.Capturing the above mechanism has the potential to improve convective weather forecasts under climate change.This study suggests that the more frequent NCCV-induced gale events in recent years are partly due to high-latitude waviness and storm activities,and this hypothesis needs to be investigated using more cases.展开更多
In order to improve the length of plasma in a whole tube and mechanical properties of Cr films deposited on the inner surface of the tube, a high-power impulse magnetron sputtering coating method with a planar cathode...In order to improve the length of plasma in a whole tube and mechanical properties of Cr films deposited on the inner surface of the tube, a high-power impulse magnetron sputtering coating method with a planar cathode target and auxiliary anode was proposed. The auxiliary anode was placed near the tube tail to attract plasma into the inner part of the tube. Cr films were deposited on the inner wall of a 20# carbon steel tube with a diameter of 40 mm and length of 120 mm. The influence of auxiliary anode voltage on the discharge characteristics of the Cr target, and the structure and mechanical properties of Cr films deposited on the inner surface of the tube were explored. With higher auxiliary anode voltage, an increase in substrate current was observed, especially in the tube tail. The thickness uniformity, compactness, hardness and H/E ratios of the Cr films deposited on the inner surface of the tube increased with the increase in auxiliary anode voltage. The Cr films deposited with auxiliary anode voltage of 60 V exhibited the highest hardness of 9.6 GPa and the lowest friction coefficient of 0.68.展开更多
Despite the impressive progress of stimuli-responsive fluorescent materials,little is known about the influence of confinement created by crystalline polymer over the fluorescence properties of fluorescent molecules.T...Despite the impressive progress of stimuli-responsive fluorescent materials,little is known about the influence of confinement created by crystalline polymer over the fluorescence properties of fluorescent molecules.The effects of confinement on the fluorescence of an aggregation-induced emission luminogen(AIEgen)are investigated using computational simulations,which reveal that the confined space induces the AIEgens to take a more planar conformation,resulting in a red-shifted emission spectrum.With this property,the study is extended to explore the confinement generated by various polymer crystalline forms,and it is shown that different fluorescence colors are activated.This confinement fluorescence effect is attributed to the different spatial dimensions of the polymer amorphous layer between lamellar crystals where the AIEgens are located.These results indicate the immediate association between crystalline structure and fluorescence signals,activating unprecedented photophysical properties of luminescent materials,and also providing the possibility for crystalline structure visualization,it is important for the many polymer crystallization processes occurring in the materials processing.展开更多
Carbon-free hydrogen as a promising clean energy source can be produced with electrocatalysts via water electrolysis.Oxygen evolution reaction(OER)as anodic reaction determines the overall efficiency of water electrol...Carbon-free hydrogen as a promising clean energy source can be produced with electrocatalysts via water electrolysis.Oxygen evolution reaction(OER)as anodic reaction determines the overall efficiency of water electrolysis due to sluggish OER kinetics.Thus,it’s much desirable to explore the efficient and earth-abundant transition-metal-based OER electrocatalysts with high current density and superior stability for industrial alkaline electrolyzers.Herein,we demonstrate a significant enhancement of OER kinetics with the hybrid electrocatalyst arrays in alkaline via judiciously combining earth-abundant and ultrathin NiCo-based layered double hydroxide(NiCo LDH)nanosheets with nickel cobalt sulfides(NiCoS)with a facile metal-organic framework(MOF)-template-involved surface sulfidation process.The obtained NiCo LDH/NiCoS hybrid arrays exhibits an extremely low OER overpotential of 308 mV at 100 mA·cm^(−2),378 mV at 200 mA·cm^(−2)and 472 mV at 400 mA·cm^(−2)in 1 M KOH solution,respectively.A much low Tafel slope of 48 mV·dec^(−1)can be achieved.Meanwhile,with the current density from 50 to 250 mA·cm^(−2),the NiCo-LDH/NiCoS hybrid arrays can run for 25 h without any degradation.Our results demonstrate that the construction of hybrid arrays with abundant interfaces of NiCo LDH/NiCoS can facilitate OER kinetics via possible modulation of binding energy of O-containing intermediates in alkaline media.The present work would pave the way for the development of lowcost and efficient OER catalysts and industrial application of water alkaline electrolyzers.展开更多
基金supported by the China National Science Foundation (Grant No. 41705029)Anhui Joint Foundation (Grant No.2208085UQ11)+2 种基金China Meteorological Administration special grants on innovation and development (Grant No. CXFZ2023J017)China Meteorological Administration special grants on decision-making meteorological service (Grant No. JCZX2022005)support from the innovation team at Anhui Meteorological Bureau
文摘Arctic changes influence not only temperature and precipitation in the midlatitudes but also contribute to severe convection.This study investigates an extreme gale event that occurred on 30 April 2021 in East China and was forced by an Arctic potential vorticity(PV)anomaly intrusion.Temperature advection steered by storms contributed to the equatorward propagation of Arctic high PV,forming the Northeast China cold vortex(NCCV).At the upper levels,a PV southward intrusion guided the combination of the polar jet and the subtropical jet,providing strong vertical wind shear and downward momentum transportation to the event.The PV anomaly cooled the upper troposphere and the northern part of East China,whereas the lower levels over southern East China were dominated by local warm air,thus establishing strong instability and baroclinicity.In addition,the entrainment of Arctic dry air strengthened the surface pressure gradient by evaporation cooling.Capturing the above mechanism has the potential to improve convective weather forecasts under climate change.This study suggests that the more frequent NCCV-induced gale events in recent years are partly due to high-latitude waviness and storm activities,and this hypothesis needs to be investigated using more cases.
基金financial support from National Natural Science Foundation of China(Nos.12075071 and 11875119)Heilongjiang Touyan Innovation Team Program(HITTY-20190013)。
文摘In order to improve the length of plasma in a whole tube and mechanical properties of Cr films deposited on the inner surface of the tube, a high-power impulse magnetron sputtering coating method with a planar cathode target and auxiliary anode was proposed. The auxiliary anode was placed near the tube tail to attract plasma into the inner part of the tube. Cr films were deposited on the inner wall of a 20# carbon steel tube with a diameter of 40 mm and length of 120 mm. The influence of auxiliary anode voltage on the discharge characteristics of the Cr target, and the structure and mechanical properties of Cr films deposited on the inner surface of the tube were explored. With higher auxiliary anode voltage, an increase in substrate current was observed, especially in the tube tail. The thickness uniformity, compactness, hardness and H/E ratios of the Cr films deposited on the inner surface of the tube increased with the increase in auxiliary anode voltage. The Cr films deposited with auxiliary anode voltage of 60 V exhibited the highest hardness of 9.6 GPa and the lowest friction coefficient of 0.68.
基金the National Science Foundation of China,Grant/Award Numbers:51973030,52127805,52273031,22173017the Science and Technology Commission of Shanghai Municipality,Grant/Award Numbers:20JC1414900,22511103900+3 种基金the Shanghai Rising-Star Program,Grant/Award Number:20QA1400100the China Postdoctoral Science Foundation,Grant/Award Numbers:2022M710664,2022M710663,2022T150111the Fundamental Research Funds for the Central Universities,Grant/Award Numbers:2232021A-06,22D210613“DHU”Distinguished Young Professor Program,Grant/Award Number:LZB2021001。
文摘Despite the impressive progress of stimuli-responsive fluorescent materials,little is known about the influence of confinement created by crystalline polymer over the fluorescence properties of fluorescent molecules.The effects of confinement on the fluorescence of an aggregation-induced emission luminogen(AIEgen)are investigated using computational simulations,which reveal that the confined space induces the AIEgens to take a more planar conformation,resulting in a red-shifted emission spectrum.With this property,the study is extended to explore the confinement generated by various polymer crystalline forms,and it is shown that different fluorescence colors are activated.This confinement fluorescence effect is attributed to the different spatial dimensions of the polymer amorphous layer between lamellar crystals where the AIEgens are located.These results indicate the immediate association between crystalline structure and fluorescence signals,activating unprecedented photophysical properties of luminescent materials,and also providing the possibility for crystalline structure visualization,it is important for the many polymer crystallization processes occurring in the materials processing.
基金supports from the National Natural Science Foundation of China(Nos.51908408 and 21872104)the Natural Science Foundation of Tianjin for Distinguished Young Scholar(No.20JCJQJC00150)+1 种基金Innovative Research Team of Tianjin Municipal Education Commission(No.TD13-5008)D.M.acknowledges the support from the Tencent Foundation through the XPLORER PRIZE.
文摘Carbon-free hydrogen as a promising clean energy source can be produced with electrocatalysts via water electrolysis.Oxygen evolution reaction(OER)as anodic reaction determines the overall efficiency of water electrolysis due to sluggish OER kinetics.Thus,it’s much desirable to explore the efficient and earth-abundant transition-metal-based OER electrocatalysts with high current density and superior stability for industrial alkaline electrolyzers.Herein,we demonstrate a significant enhancement of OER kinetics with the hybrid electrocatalyst arrays in alkaline via judiciously combining earth-abundant and ultrathin NiCo-based layered double hydroxide(NiCo LDH)nanosheets with nickel cobalt sulfides(NiCoS)with a facile metal-organic framework(MOF)-template-involved surface sulfidation process.The obtained NiCo LDH/NiCoS hybrid arrays exhibits an extremely low OER overpotential of 308 mV at 100 mA·cm^(−2),378 mV at 200 mA·cm^(−2)and 472 mV at 400 mA·cm^(−2)in 1 M KOH solution,respectively.A much low Tafel slope of 48 mV·dec^(−1)can be achieved.Meanwhile,with the current density from 50 to 250 mA·cm^(−2),the NiCo-LDH/NiCoS hybrid arrays can run for 25 h without any degradation.Our results demonstrate that the construction of hybrid arrays with abundant interfaces of NiCo LDH/NiCoS can facilitate OER kinetics via possible modulation of binding energy of O-containing intermediates in alkaline media.The present work would pave the way for the development of lowcost and efficient OER catalysts and industrial application of water alkaline electrolyzers.