This study utilizes the Dynamic Conditional Correlation-Generalized Autoregressive Conditional Heteroskedasticity (DCC-GARCH) model to investigate the dynamic relationship between Chinese and U.S. stock markets amid t...This study utilizes the Dynamic Conditional Correlation-Generalized Autoregressive Conditional Heteroskedasticity (DCC-GARCH) model to investigate the dynamic relationship between Chinese and U.S. stock markets amid the COVID-19 pandemic. Initially, a univariate GARCH model is developed to derive residual sequences, which are then used to estimate the DCC model parameters. The research reveals a significant rise in the interconnection between the Chinese and U.S. stock markets during the pandemic. The S&P 500 index displayed higher sensitivity and greater volatility in response to the pandemic, whereas the CSI 300 index showed superior resilience and stability. Analysis and model estimation suggest that the market’s dependence on historical data has intensified and its sensitivity to recent shocks has heightened. Predictions from the model indicate increased market volatility during the pandemic. While the model is proficient in capturing market trends, there remains potential for enhancing the accuracy of specific volatility predictions. The study proposes recommendations for policymakers and investors, highlighting the importance of improved cooperation in international financial market regulation and investor education.展开更多
Background:Ambient air pollution has posed negative effects on human health.Individual-level factors may modify this effect,but previous studies have controversial conclusions,and evidence is lacking especially in dev...Background:Ambient air pollution has posed negative effects on human health.Individual-level factors may modify this effect,but previous studies have controversial conclusions,and evidence is lacking especially in developing countries.This study aims to examine the modifying effects of sex,age,and education level of individuals on the associated between daily mortality and air pollutants,including particulate matter<10μm in aerodynamic diameter(PM_(10)),sulfur dioxide(SO_(2)),and nitrogen dioxide(NO_(2)).Methods:Time-series analysis was conducted to investigate the acute effects of the air pollution on daily mortality from January 2002 to December 2010 in Wuhan,China.Generalized Additive Models(GAM)were used to examine the association stratified by sex for non-accidental,cardiovascular,and respiratory mortality.For non-accidental mortality,stratified analysis was also conducted by age and educational level.Results:Outdoor air pollution was associated with daily non-accidental and cardiovascular mortality.An increase of 10μg/m3 in a 2-day average concentration of PM10,SO_(2),and NO_(2) was corresponding to the increase in non-accidental mortality of 0.29%(95%CI:0.06-0.53%),1.22%(95%CI:0.77-1.67%)and 1.60%(95%CI:1.00-2.19%),respectively.The effects of air pollution were faster in females than males.The magnitude of the estimates was higher for females with low education,aged 65-75 years for PM_(10) and<65 years for SO_(2).To be more specific,we observed that per 10μg/m^(3) increase in SO_(2) was association with increases in non-accidental mortality of 2.03%(95%CI:1.38-2.67)for all females and 3.10%(95%CI:2.05-4.16)for females with low education.Conclusion:Females and people with low-education are more susceptible to the effect of air pollution,which would provide a sound scientific basis for determination of air pollution standards.展开更多
Stimulated Raman scattering(SRS)microscopy has shown superior chemical resolution due to the much narrower vibrational spectral bandwidth than its fluorescence counterpart.However,breaking the diffraction-limited spat...Stimulated Raman scattering(SRS)microscopy has shown superior chemical resolution due to the much narrower vibrational spectral bandwidth than its fluorescence counterpart.However,breaking the diffraction-limited spatial resolution of SRS imaging is much more challenging because of the intrinsically weak scattering cross section and inert/stable nature of molecular bond vibrations.We report superresolution SRS(SR-SRS)nanoscopy based on reversible-switchable vibrational photochromic probes integrated with point spread function engineering strategy.By introducing a Gaussian-shaped ultraviolet excitation beam and a donut-shaped visible depletion beam in addition to the pump and Stokes beams,SR-SRS could reach sub-100 nm resolution on photoswitchable nanoparticles(NPs).Furthermore,NP-treated live cell imaging was demonstrated with resolution improvement by a factor of∼4.Our proof-of-principle work provides the potential for SR vibrational imaging to assist research on complex biological systems.展开更多
Despite much progress in organic solar cells(OSCs),higher efficiency is still the most desirable goal and can indeed be obtained through rational design of active layer materials and device optimization according to t...Despite much progress in organic solar cells(OSCs),higher efficiency is still the most desirable goal and can indeed be obtained through rational design of active layer materials and device optimization according to the theoretical prediction.Herein,under the guidance of a semi-empirical model,two new non-fullerene small molecule acceptors(NFSMAs)with an acceptor-donor-acceptor(A-D-A)architecture,namely,6 T-OFIC and 5 T-OFIC,have been designed and synthesized.6 T-OFIC exhibits wider absorption spectrum and a red-shifted absorption onset(λ_(onset))of 946 nm due to its extended conjugation central unit.In contrast,5 T-OFIC with five-thiophene-fused backbone has an absorption with theλ_(onset)of 927 nm,which is closer to the predicted absorption range for the best single junction cells based on the semiempirical model.Consequently,the device based on 5 T-OFIC yields a higher power conversion efficiency(PCE)of 13.43%compared with 12.35%of the 6 T-OFIC-based device.Furthermore,an impressive PCE of 15.45%was achieved for the5 T-OFIC-based device when using F-2 Cl as the third component.5 T-OFIC offers one of a few acceptor cases with efficiencies over 15%other than Y6 derivatives.展开更多
Ternary organic photovoltaic(OPV)strategy is an effective but facile approach to enhance the photovoltaic performance for single-junction devices.Herein,a series of ternary OPVs were fabricated by employing a wide ban...Ternary organic photovoltaic(OPV)strategy is an effective but facile approach to enhance the photovoltaic performance for single-junction devices.Herein,a series of ternary OPVs were fabricated by employing a wide bandgap donor(PBDB-TF)and two acceptor-donor-acceptor(A-D-A)-type nonfullerene small molecule acceptors(NF-SMAs,called F-2 Cl and 3 TT-OCIC).As the third component,the near-infrared SMA,3 TT-OCIC,has complementary absorption spectrum,narrow bandgap and wellcompatible crystallization property to the host acceptor(F-2 Cl)for efficient ternary OPVs.With these,the optimal ternary devices yield significantly enhanced power conversion efficiency of 15.23%,one of the very few examples with PCE higher than15%other than Y6 systems.This is mainly attributed to the increased short-circuit current density of 24.92 m A cm^(-2) and dramatically decreased energy loss of 0.53 e V.This work presents a successful example for simultaneously improving current,minimizing energy loss and together with modifying the morphology of active layers in OPVs,which will contribute to the further construction of high performance ternary OPVs.展开更多
文摘This study utilizes the Dynamic Conditional Correlation-Generalized Autoregressive Conditional Heteroskedasticity (DCC-GARCH) model to investigate the dynamic relationship between Chinese and U.S. stock markets amid the COVID-19 pandemic. Initially, a univariate GARCH model is developed to derive residual sequences, which are then used to estimate the DCC model parameters. The research reveals a significant rise in the interconnection between the Chinese and U.S. stock markets during the pandemic. The S&P 500 index displayed higher sensitivity and greater volatility in response to the pandemic, whereas the CSI 300 index showed superior resilience and stability. Analysis and model estimation suggest that the market’s dependence on historical data has intensified and its sensitivity to recent shocks has heightened. Predictions from the model indicate increased market volatility during the pandemic. While the model is proficient in capturing market trends, there remains potential for enhancing the accuracy of specific volatility predictions. The study proposes recommendations for policymakers and investors, highlighting the importance of improved cooperation in international financial market regulation and investor education.
文摘Background:Ambient air pollution has posed negative effects on human health.Individual-level factors may modify this effect,but previous studies have controversial conclusions,and evidence is lacking especially in developing countries.This study aims to examine the modifying effects of sex,age,and education level of individuals on the associated between daily mortality and air pollutants,including particulate matter<10μm in aerodynamic diameter(PM_(10)),sulfur dioxide(SO_(2)),and nitrogen dioxide(NO_(2)).Methods:Time-series analysis was conducted to investigate the acute effects of the air pollution on daily mortality from January 2002 to December 2010 in Wuhan,China.Generalized Additive Models(GAM)were used to examine the association stratified by sex for non-accidental,cardiovascular,and respiratory mortality.For non-accidental mortality,stratified analysis was also conducted by age and educational level.Results:Outdoor air pollution was associated with daily non-accidental and cardiovascular mortality.An increase of 10μg/m3 in a 2-day average concentration of PM10,SO_(2),and NO_(2) was corresponding to the increase in non-accidental mortality of 0.29%(95%CI:0.06-0.53%),1.22%(95%CI:0.77-1.67%)and 1.60%(95%CI:1.00-2.19%),respectively.The effects of air pollution were faster in females than males.The magnitude of the estimates was higher for females with low education,aged 65-75 years for PM_(10) and<65 years for SO_(2).To be more specific,we observed that per 10μg/m^(3) increase in SO_(2) was association with increases in non-accidental mortality of 2.03%(95%CI:1.38-2.67)for all females and 3.10%(95%CI:2.05-4.16)for females with low education.Conclusion:Females and people with low-education are more susceptible to the effect of air pollution,which would provide a sound scientific basis for determination of air pollution standards.
基金supported by the National Key R&D Program of China (2022YFA1203304)the Minstry of Science and Technology of China (2022YFB4200400 and 2019YFA0705900)the National Natural Science Foundation of China (21935007 and 52025033)。
基金the financial support from the National Key Research and Development Program of China(Grant No.2021YFF0502900)the National Natural Science Foundation of China(Grant Nos.61975033 and 81771930)+2 种基金the Shanghai Municipal Science and Technology Major Project(Grant Nos.2017SHZDZX01 and 2018SHZDZX01)the financial support from the Shenzhen Science and Technology Innovation Commission(Grant No.KQTD20170810111314625)the National Key Research and Development Program of China(Grant No.2018YFB0407200).
文摘Stimulated Raman scattering(SRS)microscopy has shown superior chemical resolution due to the much narrower vibrational spectral bandwidth than its fluorescence counterpart.However,breaking the diffraction-limited spatial resolution of SRS imaging is much more challenging because of the intrinsically weak scattering cross section and inert/stable nature of molecular bond vibrations.We report superresolution SRS(SR-SRS)nanoscopy based on reversible-switchable vibrational photochromic probes integrated with point spread function engineering strategy.By introducing a Gaussian-shaped ultraviolet excitation beam and a donut-shaped visible depletion beam in addition to the pump and Stokes beams,SR-SRS could reach sub-100 nm resolution on photoswitchable nanoparticles(NPs).Furthermore,NP-treated live cell imaging was demonstrated with resolution improvement by a factor of∼4.Our proof-of-principle work provides the potential for SR vibrational imaging to assist research on complex biological systems.
基金supported by the Ministry of Science and Technology, China (2019YFA0705900 and 2016YFA0200200)the National Natural Science Foundation of China (21935007, 52025033 and 51773095)+1 种基金Natural Science Foundation of Tianjin (20JCZDJC00740 and 17JCJQJC44500)the 111 Project (B12015)
文摘Despite much progress in organic solar cells(OSCs),higher efficiency is still the most desirable goal and can indeed be obtained through rational design of active layer materials and device optimization according to the theoretical prediction.Herein,under the guidance of a semi-empirical model,two new non-fullerene small molecule acceptors(NFSMAs)with an acceptor-donor-acceptor(A-D-A)architecture,namely,6 T-OFIC and 5 T-OFIC,have been designed and synthesized.6 T-OFIC exhibits wider absorption spectrum and a red-shifted absorption onset(λ_(onset))of 946 nm due to its extended conjugation central unit.In contrast,5 T-OFIC with five-thiophene-fused backbone has an absorption with theλ_(onset)of 927 nm,which is closer to the predicted absorption range for the best single junction cells based on the semiempirical model.Consequently,the device based on 5 T-OFIC yields a higher power conversion efficiency(PCE)of 13.43%compared with 12.35%of the 6 T-OFIC-based device.Furthermore,an impressive PCE of 15.45%was achieved for the5 T-OFIC-based device when using F-2 Cl as the third component.5 T-OFIC offers one of a few acceptor cases with efficiencies over 15%other than Y6 derivatives.
基金supported by the National Key Research and Development Program of China(2019YFA0705900,2016YFA0200200)the National Natural Science Foundation of China(21935007,51873089,51773095)+1 种基金Tianjin city(20JCZDJC00740,17JCJQJC44500)111 Project(B12015)。
文摘Ternary organic photovoltaic(OPV)strategy is an effective but facile approach to enhance the photovoltaic performance for single-junction devices.Herein,a series of ternary OPVs were fabricated by employing a wide bandgap donor(PBDB-TF)and two acceptor-donor-acceptor(A-D-A)-type nonfullerene small molecule acceptors(NF-SMAs,called F-2 Cl and 3 TT-OCIC).As the third component,the near-infrared SMA,3 TT-OCIC,has complementary absorption spectrum,narrow bandgap and wellcompatible crystallization property to the host acceptor(F-2 Cl)for efficient ternary OPVs.With these,the optimal ternary devices yield significantly enhanced power conversion efficiency of 15.23%,one of the very few examples with PCE higher than15%other than Y6 systems.This is mainly attributed to the increased short-circuit current density of 24.92 m A cm^(-2) and dramatically decreased energy loss of 0.53 e V.This work presents a successful example for simultaneously improving current,minimizing energy loss and together with modifying the morphology of active layers in OPVs,which will contribute to the further construction of high performance ternary OPVs.
