Light olefins is the incredibly important materials in chemical industry.Methanol to olefins(MTO),which provides a non-oil route for light olefins production,received considerable attention in the past decades.However...Light olefins is the incredibly important materials in chemical industry.Methanol to olefins(MTO),which provides a non-oil route for light olefins production,received considerable attention in the past decades.However,the catalyst deactivation is an inevitable feature in MTO processes,and regeneration,therefore,is one of the key steps in industrial MTO processes.Traditionally the MTO catalyst is regenerated by removing the deposited coke via air combustion,which unavoidably transforms coke into carbon dioxide and reduces the carbon utilization efficiency.Recent study shows that the coke species over MTO catalyst can be regenerated via steam,which can promote the light olefins yield as the deactivated coke species can be essentially transferred to industrially useful synthesis gas,is a promising pathway for further MTO processes development.In this work,we modelled and analyzed these two MTO regeneration methods in terms of carbon utilization efficiency and technology economics.As shown,the steam regeneration could achieve a carbon utilization efficiency of 84.31%,compared to 74.74%for air combustion regeneration.The MTO processes using steam regeneration can essentially achieve the near-zero carbon emission.In addition,light olefins production of the MTO processes using steam regeneration is 12.81%higher than that using air combustion regeneration.In this regard,steam regeneration could be considered as a potential yet promising regeneration method for further MTO processes,showing not only great environmental benefits but also competitive economic performance.展开更多
目的评价桑丹通络颗粒治疗阴虚血瘀证缺血性脑卒中恢复期的临床有效性与安全性。方法采用回顾性队列研究方法,通过湖南省中医药研究院附属医院门诊与住院病历系统收集2021年7月至2022年6月收治的缺血性脑卒中恢复期患者临床资料,选择应...目的评价桑丹通络颗粒治疗阴虚血瘀证缺血性脑卒中恢复期的临床有效性与安全性。方法采用回顾性队列研究方法,通过湖南省中医药研究院附属医院门诊与住院病历系统收集2021年7月至2022年6月收治的缺血性脑卒中恢复期患者临床资料,选择应用桑丹通络颗粒联合西医常规治疗的51例患者为暴露组,匹配仅应用西医常规治疗的102例患者为对照组,两组均治疗2周。比较治疗前后总有效率、美国国立卫生研究院卒中量表(National Institute of Health Stroke Scale,NIHSS)评分、日常生活活动能力(activity of daily living,ADL)评分、血脂水平、血液流变学指标和症状总积分等,并对所有患者治疗期间不良反应事件进行记录。结果暴露组临床总有效率84.31%,高于对照组的67.65%(P<0.05)。与治疗前比较,两组治疗后NIHSS、TC、LDL降低(P<0.01或P<0.05),且暴露组低于对照组(P<0.05);两组ADL升高(P<0.01),且暴露组高于对照组(P<0.01)。与治疗前比较,暴露组治疗后症状总积分、血液流变学各项指标降低(P<0.01或P<0.05),且暴露组低于对照组(P<0.01或P<0.05);HDL-C升高(P<0.01),且暴露组高于对照组(P<0.01)。结论桑丹通络颗粒联合西医常规治疗可明显改善阴虚血瘀证缺血性脑卒中恢复期患者症状,降低其神经缺损程度,改善血脂水平和血液流变学指标,有效提高其生存质量,疗效确切且安全稳定。因此,推测桑丹通络颗粒具有一定的临床应用与推广价值。展开更多
An in-depth understanding of the structure-activity relationship between the surface structure,chemical composition,adsorption and desorption of molecules,and their reaction activity and selectivity is necessary for t...An in-depth understanding of the structure-activity relationship between the surface structure,chemical composition,adsorption and desorption of molecules,and their reaction activity and selectivity is necessary for the rational design of high-performance catalysts.Herein,we present a method for studying catalytic mechanisms using a combination of in situ reaction cells and surface science techniques.The proposed system consists of four parts:preparation chamber,temperatureprogrammed desorption(TPD)chamber,quick load-lock chamber,and in situ reaction cell.The preparation chamber was equipped with setups based on the surface science techniques used for standard sample preparation and characterization,including an Ar+sputter gun,Auger electron spectrometer,and a low-energy electron diffractometer.After a well-defined model catalyst was prepared,the sample was transferred to a TPD chamber to investigate the adsorption and desorption of the probe molecule,or to the reaction cell,to measure the catalytic activity.A thermal desorption experiment for methanol on a clean Cu(111)surface was conducted to demonstrate the functionality of the preparation and TPD chambers.Moreover,the repeatability of the in situ reaction cell experiment was verified by CO_(2) hydrogenation on the Ni(110)surface.At a reaction pressure of 800 Torr at 673 K,turnover frequencies for the methanation reaction and reverse water-gas shift reaction were 0.15 and 7.55 Ni atom^(-1) s^(-1),respectively.展开更多
Magnetic topological states of matter provide a fertile playground for emerging topological physics and phenomena.The current main focus is on materials whose magnetism stems from 3d magnetic transition elements,e.g.,...Magnetic topological states of matter provide a fertile playground for emerging topological physics and phenomena.The current main focus is on materials whose magnetism stems from 3d magnetic transition elements,e.g.,MnBi_(2)Te_(4),Fe_(3)Sn_(2),and Co_(3)Sn_(2)S_(2).In contrast,topological materials with the magnetism from rare earth elements remain largely unexplored.Here we report rare earth antiferromagnet GdAuAl_(4)Ge_(2)as a candidate magnetic topological metal.Angle resolved photoemission spectroscopy(ARPES)and first-principles calculations have revealed multiple bulk bands crossing the Fermi level and pairs of low energy surface states.According to the parity and Wannier charge center analyses,these bulk bands possess nontrivial Z2 topology,establishing a strong topological insulator state in the nonmagnetic phase.Furthermore,the surface band pairs exhibit strong termination dependence which provides insight into their origin.Our results suggest GdAuAl_(4)Ge_(2)as a rare earth platform to explore the interplay between band topology,magnetism and f electron correlation,calling for further study targeting on its magnetic structure,magnetic topology state,transport behavior,and microscopic properties.展开更多
One-dimensional(1D)topological insulators are superior for low-dissipation applications owing to the 1D character of surface states where scatterings other than prohibited backscattering are further restricted.Among t...One-dimensional(1D)topological insulators are superior for low-dissipation applications owing to the 1D character of surface states where scatterings other than prohibited backscattering are further restricted.Among the proposed candidates for 1D topological materials,TaNiTe_(5)has attracted intensive attention for its quasi-one-dimensional(quasi-1D)crystalline structure.In this study,we identify the chain-like construction and anisotropic electronic states on TaNiTe_5 surface with scanning tunneling microscopy.The electron scatterings are largely suppressed even with chromium impurities deposited on the surface and magnetic field applied normal to the surface,which endows TaNiTe_5 great potential for low-dissipation spintronic applications.展开更多
Most asteroids and comets are formed in the early stages of the solar system and therefore contain a wealth of information about their birth.The asteroid exploration mission planned in the coming years by China will l...Most asteroids and comets are formed in the early stages of the solar system and therefore contain a wealth of information about their birth.The asteroid exploration mission planned in the coming years by China will likely target the celestial body named 133P/Elst-Pizarro(estimated diameter of about 4 km).The orbit of this asteroid stays within the asteroid belt,but nevertheless,it displays a comet-like dust tail.In this study,we used differential tracking data between two simulated probes and the data from an Earth station to estimate 133P gravity field model.This observation mode is similar to how the gravity field was estimated for large celestial objects in the GRAIL and GRACE missions,but here the object is the very small 133P asteroid.We compared the estimated gravity fields obtained for 133P from the satellite-to-satellite combined with the Earth-based two-way range-rate observation mode,with only the Earth-based two-way range rate mode.The results show that the accuracy of the low-degree(4 degree and order)estimate of the gravity field is improved by one order of magnitude by using the satellite-to-satellite combined with the Earth-based two-way range-rate observation mode with respect to the Earthonly tracking.Furthermore,another order of magnitude improvement in the gravity field solution is gained by decreasing the orbit altitude from 12 to 8 km.展开更多
The simple kagome-lattice band structure possesses Dirac cones,flat band,and saddle point with van Hove singularities in the electronic density of states,facilitating the emergence of various electronic orders.Here we...The simple kagome-lattice band structure possesses Dirac cones,flat band,and saddle point with van Hove singularities in the electronic density of states,facilitating the emergence of various electronic orders.Here we report a titanium-based kagome metal CsTi_(3)Bi_(5)where titanium atoms form a kagome network,resembling its isostructural compound CsV_3Sb_5.Thermodynamic properties including the magnetization,resistance,and heat capacity reveal the conventional Fermi liquid behavior in the kagome metal CsTi_(3)Bi_(5)and no signature of superconducting or charge density wave(CDW)transition anomaly down to 85 m K.Systematic angle-resolved photoemission spectroscopy measurements reveal multiple bands crossing the Fermi level,consistent with the first-principles calculations.The flat band formed by the destructive interference of hopping in the kagome lattice is observed directly.Compared to Cs V_(3)Sb_(5),the van Hove singularities are pushed far away above the Fermi level in CsTi_(3)Bi_(5),in line with the absence of CDW.Furthermore,the first-principles calculations identify the nontrivial Z_(2)topological properties for those bands crossing the Fermi level,accompanied by several local band inversions.Our results suppose CsTi_(3)Bi_(5)as a complementary platform to explore the superconductivity and nontrivial band topology.展开更多
In our most recently published article,[1]an important reference[2]predicting CsTi_(3)Bi_(5) is missing and should be added,along with Ref.[3](originally Ref.[28]),to the introduction section.
Seeking new order parameters and the related broken symmetry and studying their relationship with phase transition have been important topics in condensed matter physics.Here,by using spin-and angle-resolved photoemis...Seeking new order parameters and the related broken symmetry and studying their relationship with phase transition have been important topics in condensed matter physics.Here,by using spin-and angle-resolved photoemission spectroscopy,we confirm the helical spin texture caused by spin-layer locking in the nodal region in the cuprate superconductor Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)and discover the anisotropy of spin polarizations at nodes alongΓ–X andΓ–Y directions.The breaking of C_(4)rotational symmetry in electronic spin texture may give deeper insights into understanding the ground state of cuprate superconductors.展开更多
基金the financial support from the Strategic Priority Research Program of Chinese Academy of Sciences(XDA21010100)。
文摘Light olefins is the incredibly important materials in chemical industry.Methanol to olefins(MTO),which provides a non-oil route for light olefins production,received considerable attention in the past decades.However,the catalyst deactivation is an inevitable feature in MTO processes,and regeneration,therefore,is one of the key steps in industrial MTO processes.Traditionally the MTO catalyst is regenerated by removing the deposited coke via air combustion,which unavoidably transforms coke into carbon dioxide and reduces the carbon utilization efficiency.Recent study shows that the coke species over MTO catalyst can be regenerated via steam,which can promote the light olefins yield as the deactivated coke species can be essentially transferred to industrially useful synthesis gas,is a promising pathway for further MTO processes development.In this work,we modelled and analyzed these two MTO regeneration methods in terms of carbon utilization efficiency and technology economics.As shown,the steam regeneration could achieve a carbon utilization efficiency of 84.31%,compared to 74.74%for air combustion regeneration.The MTO processes using steam regeneration can essentially achieve the near-zero carbon emission.In addition,light olefins production of the MTO processes using steam regeneration is 12.81%higher than that using air combustion regeneration.In this regard,steam regeneration could be considered as a potential yet promising regeneration method for further MTO processes,showing not only great environmental benefits but also competitive economic performance.
文摘目的评价桑丹通络颗粒治疗阴虚血瘀证缺血性脑卒中恢复期的临床有效性与安全性。方法采用回顾性队列研究方法,通过湖南省中医药研究院附属医院门诊与住院病历系统收集2021年7月至2022年6月收治的缺血性脑卒中恢复期患者临床资料,选择应用桑丹通络颗粒联合西医常规治疗的51例患者为暴露组,匹配仅应用西医常规治疗的102例患者为对照组,两组均治疗2周。比较治疗前后总有效率、美国国立卫生研究院卒中量表(National Institute of Health Stroke Scale,NIHSS)评分、日常生活活动能力(activity of daily living,ADL)评分、血脂水平、血液流变学指标和症状总积分等,并对所有患者治疗期间不良反应事件进行记录。结果暴露组临床总有效率84.31%,高于对照组的67.65%(P<0.05)。与治疗前比较,两组治疗后NIHSS、TC、LDL降低(P<0.01或P<0.05),且暴露组低于对照组(P<0.05);两组ADL升高(P<0.01),且暴露组高于对照组(P<0.01)。与治疗前比较,暴露组治疗后症状总积分、血液流变学各项指标降低(P<0.01或P<0.05),且暴露组低于对照组(P<0.01或P<0.05);HDL-C升高(P<0.01),且暴露组高于对照组(P<0.01)。结论桑丹通络颗粒联合西医常规治疗可明显改善阴虚血瘀证缺血性脑卒中恢复期患者症状,降低其神经缺损程度,改善血脂水平和血液流变学指标,有效提高其生存质量,疗效确切且安全稳定。因此,推测桑丹通络颗粒具有一定的临床应用与推广价值。
基金supported by the National Natural Science Foundation of China (Nos.21802096,21832004,21902179,21991152,and 21991150)the Shanghai XFEL Beamline Project (SBP) (31011505505885920161A2101001)the support of the Shanghai Sailing Program (19YF1455600)。
文摘An in-depth understanding of the structure-activity relationship between the surface structure,chemical composition,adsorption and desorption of molecules,and their reaction activity and selectivity is necessary for the rational design of high-performance catalysts.Herein,we present a method for studying catalytic mechanisms using a combination of in situ reaction cells and surface science techniques.The proposed system consists of four parts:preparation chamber,temperatureprogrammed desorption(TPD)chamber,quick load-lock chamber,and in situ reaction cell.The preparation chamber was equipped with setups based on the surface science techniques used for standard sample preparation and characterization,including an Ar+sputter gun,Auger electron spectrometer,and a low-energy electron diffractometer.After a well-defined model catalyst was prepared,the sample was transferred to a TPD chamber to investigate the adsorption and desorption of the probe molecule,or to the reaction cell,to measure the catalytic activity.A thermal desorption experiment for methanol on a clean Cu(111)surface was conducted to demonstrate the functionality of the preparation and TPD chambers.Moreover,the repeatability of the in situ reaction cell experiment was verified by CO_(2) hydrogenation on the Ni(110)surface.At a reaction pressure of 800 Torr at 673 K,turnover frequencies for the methanation reaction and reverse water-gas shift reaction were 0.15 and 7.55 Ni atom^(-1) s^(-1),respectively.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2022YFA1403700)the National Natural Science Foundation of China (Grant No. 12074163)+2 种基金the Basic and Applied Basic Research Foundation of Guangdong Province, China (Grants Nos. 2022B1515020046, 2022B1515130005, and 2021B1515130007)the Innovative and Entrepreneurial Research Team Program of Guangdong Province, China (Grant Nos. 2019ZT08C044)Shenzhen Science and Technology Program (Grant No. KQTD20190929173815000)
文摘Magnetic topological states of matter provide a fertile playground for emerging topological physics and phenomena.The current main focus is on materials whose magnetism stems from 3d magnetic transition elements,e.g.,MnBi_(2)Te_(4),Fe_(3)Sn_(2),and Co_(3)Sn_(2)S_(2).In contrast,topological materials with the magnetism from rare earth elements remain largely unexplored.Here we report rare earth antiferromagnet GdAuAl_(4)Ge_(2)as a candidate magnetic topological metal.Angle resolved photoemission spectroscopy(ARPES)and first-principles calculations have revealed multiple bulk bands crossing the Fermi level and pairs of low energy surface states.According to the parity and Wannier charge center analyses,these bulk bands possess nontrivial Z2 topology,establishing a strong topological insulator state in the nonmagnetic phase.Furthermore,the surface band pairs exhibit strong termination dependence which provides insight into their origin.Our results suggest GdAuAl_(4)Ge_(2)as a rare earth platform to explore the interplay between band topology,magnetism and f electron correlation,calling for further study targeting on its magnetic structure,magnetic topology state,transport behavior,and microscopic properties.
基金the National Key R&D Program of China(Grant No.2017YFA0305400)the National Natural Science Foundation of China(Grant No.11227902)。
文摘One-dimensional(1D)topological insulators are superior for low-dissipation applications owing to the 1D character of surface states where scatterings other than prohibited backscattering are further restricted.Among the proposed candidates for 1D topological materials,TaNiTe_(5)has attracted intensive attention for its quasi-one-dimensional(quasi-1D)crystalline structure.In this study,we identify the chain-like construction and anisotropic electronic states on TaNiTe_5 surface with scanning tunneling microscopy.The electron scatterings are largely suppressed even with chromium impurities deposited on the surface and magnetic field applied normal to the surface,which endows TaNiTe_5 great potential for low-dissipation spintronic applications.
基金supported by the National Natural Science Foundation of China (42241116 and U1831132)supported by the Macao Science and Technology Development Fund (No. SKL-LPS(MUST)-20212023)+2 种基金the 2022 Project of Xinjiang Uygur Autonomous Region of China for Heaven Lake Talent Programsupported by the Chinese Academy of Sciences Foundation of the young scholars of western (2020-XBQNXZ-019)supported by a DAR grant in planetology from the French Space Agency (CNES).
文摘Most asteroids and comets are formed in the early stages of the solar system and therefore contain a wealth of information about their birth.The asteroid exploration mission planned in the coming years by China will likely target the celestial body named 133P/Elst-Pizarro(estimated diameter of about 4 km).The orbit of this asteroid stays within the asteroid belt,but nevertheless,it displays a comet-like dust tail.In this study,we used differential tracking data between two simulated probes and the data from an Earth station to estimate 133P gravity field model.This observation mode is similar to how the gravity field was estimated for large celestial objects in the GRAIL and GRACE missions,but here the object is the very small 133P asteroid.We compared the estimated gravity fields obtained for 133P from the satellite-to-satellite combined with the Earth-based two-way range-rate observation mode,with only the Earth-based two-way range rate mode.The results show that the accuracy of the low-degree(4 degree and order)estimate of the gravity field is improved by one order of magnitude by using the satellite-to-satellite combined with the Earth-based two-way range-rate observation mode with respect to the Earthonly tracking.Furthermore,another order of magnitude improvement in the gravity field solution is gained by decreasing the orbit altitude from 12 to 8 km.
基金the National Key R&D Program of China(Grant No.2022YFA1403700)the National Natural Science Foundation of China(Grant Nos.12074163 and 12004030)+5 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022B1515020046,2022B1515130005,2021B1515130007,and 2020B1515120100)the Guangdong Innovative and Entrepreneurial Research Team Program(Grant Nos.2017ZT07C062 and 2019ZT08C044)the Shenzhen Science and Technology Program(Grant No.KQTD20190929173815000)Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices(Grant No.ZDSYS20190902092905285)the Shenzhen Fundamental Research Program(Grant No.JCYJ20220818100405013)China Postdoctoral Science Foundation(Grant No.2020M682780 and 2022M711495)。
文摘The simple kagome-lattice band structure possesses Dirac cones,flat band,and saddle point with van Hove singularities in the electronic density of states,facilitating the emergence of various electronic orders.Here we report a titanium-based kagome metal CsTi_(3)Bi_(5)where titanium atoms form a kagome network,resembling its isostructural compound CsV_3Sb_5.Thermodynamic properties including the magnetization,resistance,and heat capacity reveal the conventional Fermi liquid behavior in the kagome metal CsTi_(3)Bi_(5)and no signature of superconducting or charge density wave(CDW)transition anomaly down to 85 m K.Systematic angle-resolved photoemission spectroscopy measurements reveal multiple bands crossing the Fermi level,consistent with the first-principles calculations.The flat band formed by the destructive interference of hopping in the kagome lattice is observed directly.Compared to Cs V_(3)Sb_(5),the van Hove singularities are pushed far away above the Fermi level in CsTi_(3)Bi_(5),in line with the absence of CDW.Furthermore,the first-principles calculations identify the nontrivial Z_(2)topological properties for those bands crossing the Fermi level,accompanied by several local band inversions.Our results suppose CsTi_(3)Bi_(5)as a complementary platform to explore the superconductivity and nontrivial band topology.
文摘In our most recently published article,[1]an important reference[2]predicting CsTi_(3)Bi_(5) is missing and should be added,along with Ref.[3](originally Ref.[28]),to the introduction section.
基金the National Natural Science Foundation of China(Grant Nos.U1632266,11927807,and U2032207)the National Key R&D Program of China(Grant No.2017YFA 0305400)supported by the US Department of Energy,Office of Basic Energy Sciences(Grant Nos.DOE-sc0012704)。
文摘Seeking new order parameters and the related broken symmetry and studying their relationship with phase transition have been important topics in condensed matter physics.Here,by using spin-and angle-resolved photoemission spectroscopy,we confirm the helical spin texture caused by spin-layer locking in the nodal region in the cuprate superconductor Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)and discover the anisotropy of spin polarizations at nodes alongΓ–X andΓ–Y directions.The breaking of C_(4)rotational symmetry in electronic spin texture may give deeper insights into understanding the ground state of cuprate superconductors.
