Advanced intensity measures(IMs)based on an inelastic deformation spectrum improved the evaluation of the median engineering demand parameters(EDPs)and reduced dispersion.In this regard,an optimized two-degreefreedom(...Advanced intensity measures(IMs)based on an inelastic deformation spectrum improved the evaluation of the median engineering demand parameters(EDPs)and reduced dispersion.In this regard,an optimized two-degreefreedom(2DOF)modal pushover-based scaling procedure(2DMPS)has been developed for a nonlinear dynamic analysis of asymmetric in-plan buildings.The 2DMPS procedure scales ground motions to approach close enough to a target value of the inelastic displacement of the first-mode inelastic 2DOF modal stick,extended for structures with significant contributions of higher modes.Further,4-,6-and 13-story RC SMRF buildings were selected for analyses using ground motion records scaled by the 2DMPS procedure,the modal pushover-based scaling method(MPS),and ASCE/SEI 7-16 scaling procedures.The median values of EDPs on scaled records closely matched the benchmark results.The bias in the EDP values due to the scaled records in every group regarding their median value was lower than the dispersion of the 21 unscaled records.These results generally demonstrate the accuracy and efficiency of the 2DMPS method.Additionally,the 2DOF modal stick’s inelastic response spectra are better suited for calculating seismic demands for one-way asymmetric-plan structures than the SDOF inelastic response spectra.展开更多
Cuprous oxide(Cu_(2)O) is one of the most promising catalysts for electrochemical conversion of CO_(2) into value-added C_(2) products.The efficiency of CO_(2)-to-C_(2) conversion is highly dependent on the Cu_(2)O cr...Cuprous oxide(Cu_(2)O) is one of the most promising catalysts for electrochemical conversion of CO_(2) into value-added C_(2) products.The efficiency of CO_(2)-to-C_(2) conversion is highly dependent on the Cu_(2)O crystal plane orientation and the corresponding adsorbed ^(*)CO species.Herein,we constructed high-index crystal planes(311) in Cu_(2)O(CO-Cu_(2)O) via a facile self-selective CO-induced strategy under a CO atmosphere,which was verified by high-resolution transmission electron microscopy(HR-TEM) and atomic force microscopy(AFM) results.By exploiting the high surface energy of the high index crystal planes,^(*)CO species are stabilized in CO-Cu_(2)O during CO_(2)RR,resulting in exceptional catalytic performance for CO_(2)-to-C_(2)products.In situ infrared spectroscopy revealed that both atop-type(^(*)CO_(atop)) and hollow-type(^(*)CO_(hollow)) adsorption of ^(*)CO species occurred on the CO-Cu_(2)O.The asymmetric C-C coupling energy barrier between ^(*)CO_(atop) and ^(*)CO_(hollow) in(311) crystal plane decreases by 47.8 % compared to the symmetric coupling of ^(*)CO_(atop) in conventional(100) crystal planes.Consequently,the Faradaic efficiency of C_(2) products generated with CO-Cu_(2)O was increased by as high as 100 % compared to that with pristine Cu_(2)O.展开更多
The flow behavior of molten steel in the thin slab mold under high casting speed conditions was investigated,with a focus on the multi-mode continuous casting and rolling mold.A steel-slag two-phase flow model was est...The flow behavior of molten steel in the thin slab mold under high casting speed conditions was investigated,with a focus on the multi-mode continuous casting and rolling mold.A steel-slag two-phase flow model was established using large eddy simulation,the volume of fluid,and magnetohydrodynamics methods through numerical simulation.The maximum flow velocity and wave height at the steel-slag interface within the mold are critical evaluation criteria for analyzing asymmetric flow under varying casting speeds and electromagnetic braking.The results indicate that the asymmetric flows within the mold do not occur synchronously.The severity of the asymmetric flow correlates with the velocity difference across the steel-slag interface.A greater biased flow prolongs the time required to revert to a steady state.When the magnetic field intensity is set to 0.24 T and the magnetic pole position is at 390 mm from the steel-slag interface,this configuration can reduce the velocity of the steel-slag interface,thereby mitigating the asymmetric flow.Additionally,it can diminish the velocity,impact depth,and impact intensity on the narrow face of the jet,thus improving the distribution of velocity and turbulent kinetic energy within the mold.This configuration prolongs the time required for the steel-slag interface to transition from a stable state to its maximum velocity and shortens the time for the interface to return to stability from an unstable state.Moreover,it ensures the positional stability of the steel-slag interface,confining its position within−3 mm.展开更多
A nonfused ring electron acceptor(NFREA),designated as TT-Ph-C6,has been synthesized with the aim of enhancing the power conversion efficiency(PCE)of organic solar cells(OSCs).By integrating asymmetric phenylalkylamin...A nonfused ring electron acceptor(NFREA),designated as TT-Ph-C6,has been synthesized with the aim of enhancing the power conversion efficiency(PCE)of organic solar cells(OSCs).By integrating asymmetric phenylalkylamino side groups,TT-Ph-C6 demonstrates excellent solubility and its crystal structure exhibits compact packing structures with a three-dimensional molecular stacking network.These structural attributes markedly promote exciton diffusion and charge carrier mobility,particularly advantageous for the fabrication of thick-film devices.TT-Ph-C6-based devices have attained a PCE of 18.01%at a film thickness of 100 nm,and even at a film thickness of 300 nm,the PCE remains at 14.64%,surpassing that of devices based on 2BTh-2F.These remarkable properties position TT-Ph-C6 as a highly promising NFREA material for boosting the efficiency of OSCs.展开更多
Catalytic asymmetric dearomatization(CADA)has emerged as a powerful strategy for transforming planar aromatic systems into three-dimensional chiral architectures[1].Notably,the Büchner reaction and arene cyclopro...Catalytic asymmetric dearomatization(CADA)has emerged as a powerful strategy for transforming planar aromatic systems into three-dimensional chiral architectures[1].Notably,the Büchner reaction and arene cyclopropanation excel in constructing complex polycyclic frameworks[2].However,current methods predominantly rely on diazo compounds as carbene precursors(Scheme1a),which pose safety risks and limit functional group compatibility.展开更多
As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding...As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.展开更多
The textures and microstructures of hot-and cold-rolled sheets of an AA 5454 aluminium alloy were studied,with special attention paid to comparing the texture development for the symmetric and asymmetric cold rolling....The textures and microstructures of hot-and cold-rolled sheets of an AA 5454 aluminium alloy were studied,with special attention paid to comparing the texture development for the symmetric and asymmetric cold rolling.Scanning electron microscopy with electron-backscatter diffraction was used to monitor the development of the microstructure in the differently deformed and additionally annealed samples.Details of the formations and transformations of individual texture components occurring during the rolling processes were observed and discussed.The average grain sizes,textures and mechanical properties were correlated and explained for the symmetric and asymmetric cold-rolled samples.The asymmetric rolling is beneficial in terms of deep drawability because it reduces the planar anisotropy of the annealed material due to the decrease of the Cube,Goss,rotated-Cube and η-fibre texture components and at the same time strengthens X1-and X2-fibre texture components which are shear texture components and improve deep drawability.During the asymmetric cold rolling,the temperature increases due to friction,triggering recrystallisation processes and leading to larger grains.It is also confirmed that asymmetric cold rolling uses less rolling force and consequently less energy to produce a final material with better formability,particularly earing.展开更多
Isosteviol,the hydrolysate of stevioside,has attracted increasing attention from scientists because of its special molecular skeleton and extensive biological activities.In recent years,due to the continuous rise of o...Isosteviol,the hydrolysate of stevioside,has attracted increasing attention from scientists because of its special molecular skeleton and extensive biological activities.In recent years,due to the continuous rise of organocatalysis,an increasing number of organocatalysts based on isosteviol have been devised and synthesized to facilitate a range of highly enantioselective asymmetric synthesis.The isosteviol-type organocatalysts reported in the literature over the past decade and their applications in asymmetric catalysis are systematically analyzed and elaborated in order to provide assistance for the further design,synthesis,and application of organocatalysis derived from isosteviol.展开更多
Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-c...Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.展开更多
The catalytic enantioselective electrophilic amination reaction has emerged as a highly efficient method for synthesizing diverse nitrogen-containing chiral molecules,with the development of various asymmetric catalys...The catalytic enantioselective electrophilic amination reaction has emerged as a highly efficient method for synthesizing diverse nitrogen-containing chiral molecules,with the development of various asymmetric catalysis systems.Chiral phosphoric acids(CPA)have been widely acknowledged as versatile chiral organocatalysts since it was first discovered in 2004,finding application in catalyzing diverse asymmetric reactions.A comprehensive overview of recent advances in CPA-catalyzed asymmetric electrophilic amination reactions using different N-electrophilic reagents,including azo reagents,aryldiazonium salts,and imine derivatives,is presented.Furthermore,insights into future developments in this field are offered.展开更多
Asymmetric allylic C—H functionalization is a valuable and challenging research area. Different from the conventional direct allylic C—H cleavage strategy, transition metal-catalyzed migratory allylic substitution o...Asymmetric allylic C—H functionalization is a valuable and challenging research area. Different from the conventional direct allylic C—H cleavage strategy, transition metal-catalyzed migratory allylic substitution of remote dienes has emerged as a new route to achieve allylic C—H functionalization enantioselectively. This review provides a detailed summary of the development and advance of this strategy, introduces the related mechanistic processes, and discusses the area based on the types of catalysts and products.展开更多
Leveraging the modularity and efficiency of click chemistry,a series of chiral diamine-triazole tetradentate nitrogen donor ligands and their corresponding nonheme iron complexes were synthesized.These iron-based cata...Leveraging the modularity and efficiency of click chemistry,a series of chiral diamine-triazole tetradentate nitrogen donor ligands and their corresponding nonheme iron complexes were synthesized.These iron-based catalysts demonstrated excellent catalytic activity and enantioselectivity in the asymmetric epoxidation of electron-deficient olefins using H_(2)O_(2) as the terminal oxidant.展开更多
Chiral quaternary phosphonium salts have recently been extensively developed as robust organic catalysts for asymmetric synthesis.Asymmetric addition reactions have been dominating in the chiral phosphonium salt-catal...Chiral quaternary phosphonium salts have recently been extensively developed as robust organic catalysts for asymmetric synthesis.Asymmetric addition reactions have been dominating in the chiral phosphonium salt-catalyzed construction of stereogenic carbon centers,heteroatom centers,axes and planes.The recent achievements in the chiral phosphonium-catalyzed asymmetric addition reactions are summarized.展开更多
Chiral pyridyl alcohols are a type of synthetically versatile building block for natural products,functional materials and bioactive molecules.Herein,a highly efficient Ir/f-amphox-catalyzed asymmetric hydrogenation o...Chiral pyridyl alcohols are a type of synthetically versatile building block for natural products,functional materials and bioactive molecules.Herein,a highly efficient Ir/f-amphox-catalyzed asymmetric hydrogenation of 1-(pyridin-2-yl)ketone derivatives to access chiral pyridyl alcohols was reported.The reaction proceeds smoothly under mild conditions,delivering excellent yields and enantioselectivities(up to>99%ee,turnover number(TON)up to 2000).A broad range of pyridyl alkyl and aryl ketones were successfully transformed,demonstrating the generality and synthetic utility of this methodology.展开更多
Presently,financial portfolio managers lack a solid basis for building a reliable risk management strategy for green debt instrument investments due to the lack of compelling growth and resilience data.Therefore,this ...Presently,financial portfolio managers lack a solid basis for building a reliable risk management strategy for green debt instrument investments due to the lack of compelling growth and resilience data.Therefore,this study assesses the role of green bonds in financial markets by assessing and correlating their complex scaling behaviors across multiple periods with those of key benchmark assets(e.g.,conventional bonds,high-yield bonds,Euro-Dollar exchange,Dow Jones Industrial Index,Bitcoin,and Gold).Specifically,we explore linear and nonlinear correlation patterns using crosscorrelation tests and the dynamic conditional correlation model,focusing on bond interactions under various degrees of freedom.Our analysis reveals that although most assets exhibit nonlinear correlations,Bitcoin uniquely aligns linearly with U.S.bonds under certain conditions.Green bonds,however,display nonlinear correlations with Bitcoin and stand out for their distinct upward financial persistence.We find also that green bonds are primary drivers in the financial domain,highlighted by their pronounced interactions and the consistent cross-correlation with the Euro-Dollar exchange rate.Moreover,green bonds have the lowest multifractality,showing persistent upward trends and antipersistent downward trends,rendering them quite resilient during periods of high volatility.These results imply that green bonds may be advantageous to portfolio risk management strategies,especially during crises when diversification and hedging tactics are needed.展开更多
A prior observational study indicated an asymmetric link between sea surface temperature(SST)in the Tasman Sea and ENSO during austral summer.Specifically,El Niño is associated with a dipolar SST anomaly pattern,...A prior observational study indicated an asymmetric link between sea surface temperature(SST)in the Tasman Sea and ENSO during austral summer.Specifically,El Niño is associated with a dipolar SST anomaly pattern,featuring warming in the northwest and cooling in the southeast,whereas La Niña corresponds to basin-scale warming.This study employs the experiments of coupled models from the sixth phase of the Coupled Model Intercomparison Project(CMIP6)to assess ENSO’s impact on Tasman Sea SST.While all 15 models capture the observed dipolar SST anomalies(SSTAs)in the Tasman Sea during El Niño years,only 7 models capture the basin-scale warmth in the Tasman Sea during La Niña years.Consequently,the models are bifurcated into two groups:group-one models yield one physically reasonable asymmetric connection as observed,including the asymmetry of oceanic heat transport,especially the Ekman meridional transport anomalies induced by zonal wind stress driven by the asymmetric atmospheric circulation over the Tasman Sea.However,due to abnormal responses to ENSO and systematic biases in model simulations,including jet and storm tracks,oceanic heat fluxes,ocean currents,and SST,the group-two models fail to reproduce the asymmetric connection between the Tasman Sea and ENSO.This study not only validates the observational asymmetric connection of SSTAs in the Tasman Sea with respect to the two opposite ENSO phases,but also provides evidence and clues to reduce the bias in group-two models.展开更多
Herein,we report the first asymmetric synthesis of illihenin A,an antiviral sesquiterpenoid bearing a cage-like tricyclo[6.2.2.01,5]dodecane skeleton.Starting from an abundant feedstock(-)-α-cedrene,this19-step synth...Herein,we report the first asymmetric synthesis of illihenin A,an antiviral sesquiterpenoid bearing a cage-like tricyclo[6.2.2.01,5]dodecane skeleton.Starting from an abundant feedstock(-)-α-cedrene,this19-step synthesis approach features a novel ring-reorganization strategy that includes early stage C7-hydroxylation of the cedrane skeleton and a later-stage ring disassembly-reassembly procedure,affording the desired product with high synthetic efficiency and minimal chiral manipulation.The key transformations include the following:(i)a hydroxy group-directed SmI2-mediated reductive coupling to construct the congested tertiary 7-OH cedrane,(ii)aβ-fragmentation triggered by an alkoxy radical to release a spiro[4.5]decane,and(iii)an intramolecular Aldol reaction,concomitant withα-epimerization,to furnish the tricyclic framework.In addition,preliminary investigation of antiviral activity against CVB3 revealed that illihenin A can significantly inhibit ROS production and apoptosis.展开更多
The chemo-,regio-,and enantio-controlled synthesis of P-chiral phosphines in a general and efficient manner remains a significant synthetic challenge.In this study,a Pd-catalyzed hydrofunctionalization is developed fo...The chemo-,regio-,and enantio-controlled synthesis of P-chiral phosphines in a general and efficient manner remains a significant synthetic challenge.In this study,a Pd-catalyzed hydrofunctionalization is developed for the highly selective synthesis of P-stereogenic alkenylphosphinates and alkenylphosphine oxides via conjugate addition of enynes.Notably,this methodology is suitable for both phosphine oxide and phosphinate nucleophiles,providing a versatile approach for the construction of diverse P-chiral organophosphosphorus compound.展开更多
The impacts of asymmetric rolling(ASR)and cold rolling(CR)on the creep-aging behavior of AA2219 alloys were revealed by creep deformation experiments,tensile tests,electron backscattered diffraction(EBSD)and transmiss...The impacts of asymmetric rolling(ASR)and cold rolling(CR)on the creep-aging behavior of AA2219 alloys were revealed by creep deformation experiments,tensile tests,electron backscattered diffraction(EBSD)and transmission electron microscopy(TEM).The ASR specimens under creep stress condition of 1.2σ0.2(σ0.2 is the yield strength)displayed a 50%higher creep strain than the CR specimens.At a creep stress of 0.5σ0.2,the ASR specimens demonstrated remarkably mechanical properties,with a tensile strength of 525 MPa,a yield strength of 338 MPa,and an elongation of 15.2%.This enhancement can be ascribed to the effective grain refinement and promotion of recrystallization after ASR.Notably,ASR resulted in the formation of higher cube textures and a denser forest dislocation structure compared with CR.Additionally,ASR specimens demonstrated a higher density of dispersive,smallerθ′precipitates and larger average Taylor factors compared with CR specimens.展开更多
The dynamic kinetic resolution(DKR)process remains a highly efficacious approach for constructing chiral amino alcohols via the catalytic asymmetric hydrogenation ofα-amino ketones.We report herein a highly efficient...The dynamic kinetic resolution(DKR)process remains a highly efficacious approach for constructing chiral amino alcohols via the catalytic asymmetric hydrogenation ofα-amino ketones.We report herein a highly efficient and enantioselective anti-selective dynamic kinetic asymmetric hydrogenation ofα-amino ketones catalyzed by Ir-(S)-f-phamidol system,providing various chiral amino alcohols and chiral oxazolidin-2-ones divergently with high diastereo-and enantioselectivity(up to 99%yield,up to 99%ee and up to 99:1 dr).In addition,the reaction could be performed on the gram-scale,and the resulting chiral amino alcohols are key intermediates of norephedrine and metaraminol.展开更多
文摘Advanced intensity measures(IMs)based on an inelastic deformation spectrum improved the evaluation of the median engineering demand parameters(EDPs)and reduced dispersion.In this regard,an optimized two-degreefreedom(2DOF)modal pushover-based scaling procedure(2DMPS)has been developed for a nonlinear dynamic analysis of asymmetric in-plan buildings.The 2DMPS procedure scales ground motions to approach close enough to a target value of the inelastic displacement of the first-mode inelastic 2DOF modal stick,extended for structures with significant contributions of higher modes.Further,4-,6-and 13-story RC SMRF buildings were selected for analyses using ground motion records scaled by the 2DMPS procedure,the modal pushover-based scaling method(MPS),and ASCE/SEI 7-16 scaling procedures.The median values of EDPs on scaled records closely matched the benchmark results.The bias in the EDP values due to the scaled records in every group regarding their median value was lower than the dispersion of the 21 unscaled records.These results generally demonstrate the accuracy and efficiency of the 2DMPS method.Additionally,the 2DOF modal stick’s inelastic response spectra are better suited for calculating seismic demands for one-way asymmetric-plan structures than the SDOF inelastic response spectra.
基金the financial support from the National Natural Science Foundation of China (Nos.U23A20677,22022610 and 52400137)"Pioneer" and "Leading Goose" R&D Program of Zhejiang (Nos.2022C03146 and 2023C03017)+2 种基金China Postdoctoral Science Foundation (No.2024T170805)Zhejiang Provincial Natural Science Foundation of China (No.LDT23E06015B06)the support of the Research Computing Center in College of Chemical and Biological Engineering at Zhejiang University for assistance with the calculations。
文摘Cuprous oxide(Cu_(2)O) is one of the most promising catalysts for electrochemical conversion of CO_(2) into value-added C_(2) products.The efficiency of CO_(2)-to-C_(2) conversion is highly dependent on the Cu_(2)O crystal plane orientation and the corresponding adsorbed ^(*)CO species.Herein,we constructed high-index crystal planes(311) in Cu_(2)O(CO-Cu_(2)O) via a facile self-selective CO-induced strategy under a CO atmosphere,which was verified by high-resolution transmission electron microscopy(HR-TEM) and atomic force microscopy(AFM) results.By exploiting the high surface energy of the high index crystal planes,^(*)CO species are stabilized in CO-Cu_(2)O during CO_(2)RR,resulting in exceptional catalytic performance for CO_(2)-to-C_(2)products.In situ infrared spectroscopy revealed that both atop-type(^(*)CO_(atop)) and hollow-type(^(*)CO_(hollow)) adsorption of ^(*)CO species occurred on the CO-Cu_(2)O.The asymmetric C-C coupling energy barrier between ^(*)CO_(atop) and ^(*)CO_(hollow) in(311) crystal plane decreases by 47.8 % compared to the symmetric coupling of ^(*)CO_(atop) in conventional(100) crystal planes.Consequently,the Faradaic efficiency of C_(2) products generated with CO-Cu_(2)O was increased by as high as 100 % compared to that with pristine Cu_(2)O.
基金support from the National Natural Science Foundation of China(Grant Nos.52174313 and 52304350)thank all members of the Hebei High Quality Steel Continuous Casting Engineering Technology Research Center at North China University of Science and Technology,Tangshan,China.
文摘The flow behavior of molten steel in the thin slab mold under high casting speed conditions was investigated,with a focus on the multi-mode continuous casting and rolling mold.A steel-slag two-phase flow model was established using large eddy simulation,the volume of fluid,and magnetohydrodynamics methods through numerical simulation.The maximum flow velocity and wave height at the steel-slag interface within the mold are critical evaluation criteria for analyzing asymmetric flow under varying casting speeds and electromagnetic braking.The results indicate that the asymmetric flows within the mold do not occur synchronously.The severity of the asymmetric flow correlates with the velocity difference across the steel-slag interface.A greater biased flow prolongs the time required to revert to a steady state.When the magnetic field intensity is set to 0.24 T and the magnetic pole position is at 390 mm from the steel-slag interface,this configuration can reduce the velocity of the steel-slag interface,thereby mitigating the asymmetric flow.Additionally,it can diminish the velocity,impact depth,and impact intensity on the narrow face of the jet,thus improving the distribution of velocity and turbulent kinetic energy within the mold.This configuration prolongs the time required for the steel-slag interface to transition from a stable state to its maximum velocity and shortens the time for the interface to return to stability from an unstable state.Moreover,it ensures the positional stability of the steel-slag interface,confining its position within−3 mm.
基金Financial support from the National Natural Science Foundation of China(22375024,21975031,21734009,51933001,22109080,and 52173174)the Natural Science Foundation of Shandong Province(No.ZR2022YQ45)+2 种基金the Taishan Scholars Program(Nos.tstp20221121 and tsqnz20221134)The Beijing Natural Science Foundation(No.2244073)supported by State Key Laboratory of Bio-Fibers and Eco-Textiles(Qingdao University)(RZ2200002821)is acknowledged.
文摘A nonfused ring electron acceptor(NFREA),designated as TT-Ph-C6,has been synthesized with the aim of enhancing the power conversion efficiency(PCE)of organic solar cells(OSCs).By integrating asymmetric phenylalkylamino side groups,TT-Ph-C6 demonstrates excellent solubility and its crystal structure exhibits compact packing structures with a three-dimensional molecular stacking network.These structural attributes markedly promote exciton diffusion and charge carrier mobility,particularly advantageous for the fabrication of thick-film devices.TT-Ph-C6-based devices have attained a PCE of 18.01%at a film thickness of 100 nm,and even at a film thickness of 300 nm,the PCE remains at 14.64%,surpassing that of devices based on 2BTh-2F.These remarkable properties position TT-Ph-C6 as a highly promising NFREA material for boosting the efficiency of OSCs.
文摘Catalytic asymmetric dearomatization(CADA)has emerged as a powerful strategy for transforming planar aromatic systems into three-dimensional chiral architectures[1].Notably,the Büchner reaction and arene cyclopropanation excel in constructing complex polycyclic frameworks[2].However,current methods predominantly rely on diazo compounds as carbene precursors(Scheme1a),which pose safety risks and limit functional group compatibility.
文摘As an advanced device for observing atmospheric winds,the spaceborne Doppler Asymmetric Spatial Heterodyne(DASH)interferometer also encounters challenges associated with phase distortion,par-ticularly in limb sounding scenarios.This paper discusses interferogram modeling and phase distortion cor-rection techniques for spaceborne DASH interferometers.The modeling of phase distortion interferograms with and without Doppler shift for limb observation was conducted,and the effectiveness of the analytical expression was verified through numerical simulation.The simulation results indicate that errors propagate layer by layer while using the onion-peeling inversion algorithm to handle phase-distorted interferograms.In contrast,the phase distortion correction algorithm can achieve effective correction.This phase correction method can be successfully applied to correct phase distortions in the interferograms of the spaceborne DASH interferometer,providing a feasible solution to enhance its measurement accuracy.
文摘The textures and microstructures of hot-and cold-rolled sheets of an AA 5454 aluminium alloy were studied,with special attention paid to comparing the texture development for the symmetric and asymmetric cold rolling.Scanning electron microscopy with electron-backscatter diffraction was used to monitor the development of the microstructure in the differently deformed and additionally annealed samples.Details of the formations and transformations of individual texture components occurring during the rolling processes were observed and discussed.The average grain sizes,textures and mechanical properties were correlated and explained for the symmetric and asymmetric cold-rolled samples.The asymmetric rolling is beneficial in terms of deep drawability because it reduces the planar anisotropy of the annealed material due to the decrease of the Cube,Goss,rotated-Cube and η-fibre texture components and at the same time strengthens X1-and X2-fibre texture components which are shear texture components and improve deep drawability.During the asymmetric cold rolling,the temperature increases due to friction,triggering recrystallisation processes and leading to larger grains.It is also confirmed that asymmetric cold rolling uses less rolling force and consequently less energy to produce a final material with better formability,particularly earing.
基金Project supported by the National Natural Science Foundation of China(No.51403053)the University Scientific Innovation Team of Henan Province(No.24IRTSTHN017)。
文摘Isosteviol,the hydrolysate of stevioside,has attracted increasing attention from scientists because of its special molecular skeleton and extensive biological activities.In recent years,due to the continuous rise of organocatalysis,an increasing number of organocatalysts based on isosteviol have been devised and synthesized to facilitate a range of highly enantioselective asymmetric synthesis.The isosteviol-type organocatalysts reported in the literature over the past decade and their applications in asymmetric catalysis are systematically analyzed and elaborated in order to provide assistance for the further design,synthesis,and application of organocatalysis derived from isosteviol.
文摘Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.
文摘The catalytic enantioselective electrophilic amination reaction has emerged as a highly efficient method for synthesizing diverse nitrogen-containing chiral molecules,with the development of various asymmetric catalysis systems.Chiral phosphoric acids(CPA)have been widely acknowledged as versatile chiral organocatalysts since it was first discovered in 2004,finding application in catalyzing diverse asymmetric reactions.A comprehensive overview of recent advances in CPA-catalyzed asymmetric electrophilic amination reactions using different N-electrophilic reagents,including azo reagents,aryldiazonium salts,and imine derivatives,is presented.Furthermore,insights into future developments in this field are offered.
文摘Asymmetric allylic C—H functionalization is a valuable and challenging research area. Different from the conventional direct allylic C—H cleavage strategy, transition metal-catalyzed migratory allylic substitution of remote dienes has emerged as a new route to achieve allylic C—H functionalization enantioselectively. This review provides a detailed summary of the development and advance of this strategy, introduces the related mechanistic processes, and discusses the area based on the types of catalysts and products.
文摘Leveraging the modularity and efficiency of click chemistry,a series of chiral diamine-triazole tetradentate nitrogen donor ligands and their corresponding nonheme iron complexes were synthesized.These iron-based catalysts demonstrated excellent catalytic activity and enantioselectivity in the asymmetric epoxidation of electron-deficient olefins using H_(2)O_(2) as the terminal oxidant.
文摘Chiral quaternary phosphonium salts have recently been extensively developed as robust organic catalysts for asymmetric synthesis.Asymmetric addition reactions have been dominating in the chiral phosphonium salt-catalyzed construction of stereogenic carbon centers,heteroatom centers,axes and planes.The recent achievements in the chiral phosphonium-catalyzed asymmetric addition reactions are summarized.
文摘Chiral pyridyl alcohols are a type of synthetically versatile building block for natural products,functional materials and bioactive molecules.Herein,a highly efficient Ir/f-amphox-catalyzed asymmetric hydrogenation of 1-(pyridin-2-yl)ketone derivatives to access chiral pyridyl alcohols was reported.The reaction proceeds smoothly under mild conditions,delivering excellent yields and enantioselectivities(up to>99%ee,turnover number(TON)up to 2000).A broad range of pyridyl alkyl and aryl ketones were successfully transformed,demonstrating the generality and synthetic utility of this methodology.
基金Benjamin M.Tabak(Grant no.305485/2022-9)gratefully acknowledges financial support from the CNPq foundation and CAPES Foundation。
文摘Presently,financial portfolio managers lack a solid basis for building a reliable risk management strategy for green debt instrument investments due to the lack of compelling growth and resilience data.Therefore,this study assesses the role of green bonds in financial markets by assessing and correlating their complex scaling behaviors across multiple periods with those of key benchmark assets(e.g.,conventional bonds,high-yield bonds,Euro-Dollar exchange,Dow Jones Industrial Index,Bitcoin,and Gold).Specifically,we explore linear and nonlinear correlation patterns using crosscorrelation tests and the dynamic conditional correlation model,focusing on bond interactions under various degrees of freedom.Our analysis reveals that although most assets exhibit nonlinear correlations,Bitcoin uniquely aligns linearly with U.S.bonds under certain conditions.Green bonds,however,display nonlinear correlations with Bitcoin and stand out for their distinct upward financial persistence.We find also that green bonds are primary drivers in the financial domain,highlighted by their pronounced interactions and the consistent cross-correlation with the Euro-Dollar exchange rate.Moreover,green bonds have the lowest multifractality,showing persistent upward trends and antipersistent downward trends,rendering them quite resilient during periods of high volatility.These results imply that green bonds may be advantageous to portfolio risk management strategies,especially during crises when diversification and hedging tactics are needed.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFF0805101)the National Natural Science Founda-tion of China(Grant Nos.42376250 and 42405068).
文摘A prior observational study indicated an asymmetric link between sea surface temperature(SST)in the Tasman Sea and ENSO during austral summer.Specifically,El Niño is associated with a dipolar SST anomaly pattern,featuring warming in the northwest and cooling in the southeast,whereas La Niña corresponds to basin-scale warming.This study employs the experiments of coupled models from the sixth phase of the Coupled Model Intercomparison Project(CMIP6)to assess ENSO’s impact on Tasman Sea SST.While all 15 models capture the observed dipolar SST anomalies(SSTAs)in the Tasman Sea during El Niño years,only 7 models capture the basin-scale warmth in the Tasman Sea during La Niña years.Consequently,the models are bifurcated into two groups:group-one models yield one physically reasonable asymmetric connection as observed,including the asymmetry of oceanic heat transport,especially the Ekman meridional transport anomalies induced by zonal wind stress driven by the asymmetric atmospheric circulation over the Tasman Sea.However,due to abnormal responses to ENSO and systematic biases in model simulations,including jet and storm tracks,oceanic heat fluxes,ocean currents,and SST,the group-two models fail to reproduce the asymmetric connection between the Tasman Sea and ENSO.This study not only validates the observational asymmetric connection of SSTAs in the Tasman Sea with respect to the two opposite ENSO phases,but also provides evidence and clues to reduce the bias in group-two models.
基金financially supported by the National Natural Science Foundation of China(No.22177135)the CAMS Innovation Fund for Medical Sciences(CIFMS)(No.2023-I2M-2-006)。
文摘Herein,we report the first asymmetric synthesis of illihenin A,an antiviral sesquiterpenoid bearing a cage-like tricyclo[6.2.2.01,5]dodecane skeleton.Starting from an abundant feedstock(-)-α-cedrene,this19-step synthesis approach features a novel ring-reorganization strategy that includes early stage C7-hydroxylation of the cedrane skeleton and a later-stage ring disassembly-reassembly procedure,affording the desired product with high synthetic efficiency and minimal chiral manipulation.The key transformations include the following:(i)a hydroxy group-directed SmI2-mediated reductive coupling to construct the congested tertiary 7-OH cedrane,(ii)aβ-fragmentation triggered by an alkoxy radical to release a spiro[4.5]decane,and(iii)an intramolecular Aldol reaction,concomitant withα-epimerization,to furnish the tricyclic framework.In addition,preliminary investigation of antiviral activity against CVB3 revealed that illihenin A can significantly inhibit ROS production and apoptosis.
基金the National Natural Science Foundation of China(NSFC,No.22271241),Yunnan Key Laboratory of Chiral Functional Substance Research and Application(No.202402AN360010)Research Grants Council of Hong Kong(GRF,No.12303422)HKBU KRPS grant for financial support.
文摘The chemo-,regio-,and enantio-controlled synthesis of P-chiral phosphines in a general and efficient manner remains a significant synthetic challenge.In this study,a Pd-catalyzed hydrofunctionalization is developed for the highly selective synthesis of P-stereogenic alkenylphosphinates and alkenylphosphine oxides via conjugate addition of enynes.Notably,this methodology is suitable for both phosphine oxide and phosphinate nucleophiles,providing a versatile approach for the construction of diverse P-chiral organophosphosphorus compound.
基金financial supports from the National Key Research and Development Program of China(No.2021YFB3400900)the National Natural Science Foundation of China(Nos.U22A20190,U2341273,52205435)+2 种基金the Natural Science Foundation of Hunan Province,China(No.2022JJ40621)the Science and Technology Innovation Program of Hunan Province,China(No.2020RC4001)the Project of State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,China(No.ZZYJKT2022-07)。
文摘The impacts of asymmetric rolling(ASR)and cold rolling(CR)on the creep-aging behavior of AA2219 alloys were revealed by creep deformation experiments,tensile tests,electron backscattered diffraction(EBSD)and transmission electron microscopy(TEM).The ASR specimens under creep stress condition of 1.2σ0.2(σ0.2 is the yield strength)displayed a 50%higher creep strain than the CR specimens.At a creep stress of 0.5σ0.2,the ASR specimens demonstrated remarkably mechanical properties,with a tensile strength of 525 MPa,a yield strength of 338 MPa,and an elongation of 15.2%.This enhancement can be ascribed to the effective grain refinement and promotion of recrystallization after ASR.Notably,ASR resulted in the formation of higher cube textures and a denser forest dislocation structure compared with CR.Additionally,ASR specimens demonstrated a higher density of dispersive,smallerθ′precipitates and larger average Taylor factors compared with CR specimens.
基金the National Key R&D Program of China(No.2021YFA1500201)Shenzhen Science and Technology Innovation Committee(No.KQTD20150717103157174)+6 种基金Stable Support Plan Program of Shenzhen Natural Science Fund(No.20200925161222002)Key-Area Research and Development Program of Guangdong Province(No.2020B010188001)Innovative Team of Universities in Guangdong Province(No.2020KCXTD016)National Natural Science Foundation of China(No.21991113)the National Natural Science Foundation of China(Nos.21901107 and 22171129)the Guangdong Basic and Applied Basic Research Foundation(2022B1515020055)Shenzhen Science and Technology Innovation Committee(No.JCYJ20210324104202007)for financial support。
文摘The dynamic kinetic resolution(DKR)process remains a highly efficacious approach for constructing chiral amino alcohols via the catalytic asymmetric hydrogenation ofα-amino ketones.We report herein a highly efficient and enantioselective anti-selective dynamic kinetic asymmetric hydrogenation ofα-amino ketones catalyzed by Ir-(S)-f-phamidol system,providing various chiral amino alcohols and chiral oxazolidin-2-ones divergently with high diastereo-and enantioselectivity(up to 99%yield,up to 99%ee and up to 99:1 dr).In addition,the reaction could be performed on the gram-scale,and the resulting chiral amino alcohols are key intermediates of norephedrine and metaraminol.
