Background:Gallic acid(GA),a plant-derived polyphenol,possesses diverse biological functions such as reducing inflammation and against tumors.Currently,the influence of GA on the resistance of esophageal squamous cell...Background:Gallic acid(GA),a plant-derived polyphenol,possesses diverse biological functions such as reducing inflammation and against tumors.Currently,the influence of GA on the resistance of esophageal squamous cell carcinoma(ESCC)cells to cisplatin(DDP)is not well understood.Methods:Cell counting kit-8 assay examined how GA affected KYSE30 and TE-1 cell viability.5-Ethynyl-2′-deoxyuridine and TdT-mediated dUTP Nick-End labeling staining detected cell proliferation and apoptosis.Clone formation assay,flow cytometry,Carboxyfluorescein diacetate succinimidyl ester fluorescent probes,and Transwell assay determined cell biological properties,and 2′,7′-Dichlorofluorescin diacetate(DCFH-DA)fluorescent probes detected oxidative stress levels.Signal transducer and activator of transcription 3(STAT3)/Notch pathway protein levels after GA and/or Interleukin-6(IL-6)intervention were examined through Western blot.Furthermore,a model for subcutaneous graft tumors was established in nude mice.Results:GA exerted suppressive effects on cell proliferation,and caused apoptosis of KYSE30 and TE-1 cells.IL-6 intervention activated the STAT3/Notch pathway and promoted the malignant biological properties of ESCC cells.In contrast,GA attenuated the effects of IL-6,while STAT3 or Notch inhibitor further enhanced the effects of GA,suggesting that GA inhibited the IL-6/STAT3/Notch pathway.Not only that,GA promoted oxidative stress and enhanced cell sensitivity to DDP both in vitro and in vivo.Conclusion:GA suppresses the malignant progression of ESCC and enhances cell sensitivity to DDP by hindering the IL-6/STAT3/Notch pathway.展开更多
Organohydrogel-based strain sensors are gaining attention for real-time health services and human-machine interactions due to their flexibility,stretchability,and skin-like compliance.However,these sensors often have ...Organohydrogel-based strain sensors are gaining attention for real-time health services and human-machine interactions due to their flexibility,stretchability,and skin-like compliance.However,these sensors often have limited sensitivity and poor stability due to their bulk structure and strain concentration during stretching.In this study,we designed and fabricated diamond-,grid-,and peanut-shaped organohydrogel based on positive,near-zero,and negative Poisson’s ratios using digital light processing(DLP)-based 3D printing technology.Through structural design and optimization,the grid-shaped organohydrogel exhibited record sensitivity with gauge factors of 4.5(0–200%strain,ionic mode)and 13.5/1.5×10^(6)(0-2%/2%-100%strain,electronic mode),alongside full resistance recovery for enhanced stability.The 3D-printed grid structure enabled direct wearability and breathability,overcoming traditional sensor limitations.Integrated with a robotic hand system,this sensor demonstrated clinical potential through precise monitoring of paralyzed patients’grasping movements(with a minimum monitoring angle of 5°).This structural design paradigm advanced flexible electronics by synergizing high sensitivity,stability,wearability,and breathability for healthcare,and human-machine interfaces.展开更多
In recent years,incidents of simultaneous exceedance of PM_(2.5)and O_(3) concentrations,termed PM_(2.5)and O_(3) co-pollution events,have frequently occurred in China.This study conducted atmospheric circulation anal...In recent years,incidents of simultaneous exceedance of PM_(2.5)and O_(3) concentrations,termed PM_(2.5)and O_(3) co-pollution events,have frequently occurred in China.This study conducted atmospheric circulation analysis on two typical co-pollution events in Beijing,occurring from July 22 to July 28,2019,and from April 25 to May 2,2020.These events were categorized into pre-trough southerly airflow type(Type 1)and post-trough northwest flow type(Type 2).Subsequently,sensitivity analyses using the GRAPES-CUACE adjoint model were performed to quantify the contributions of precursor emissions from Beijing and surrounding areas to PM_(2.5)and O_(3) concentrations in Beijing for two types of co-pollution.The results indicated that the spatiotemporal distribution of sensitive source region varied among different circulation types.Primary PM_(2.5)(PPM_(2.5))emissions from Hebei contributed the most to the 24-hour average PM_(2.5)(24-h PM_(2.5))peak concentration(41.6%-45.4%),followed by Beijing emissions(31%-35.7%).The maximum daily 8-hour average ozone peak concentration was primarily influenced by the emissions from Hebei and Beijing,with contribution ratios respectively of 32.8%-44.8% and 29%-42.1%.Additionally,NO_(x)emissions were the main contributors in Type 1,while both NO_(x)and VOCs emissions contributed similarly in Type 2.The iterative emission reduction experiments for two types of co-pollution indicated that Type 1 required emission reductions in NO_(x)(52.4%-71.8%)and VOCs(14.1%-33.8%)only.In contrast,Type 2 required combined emission reductions in NO_(x)(37.0%-65.1%),VOCs(30.7%-56.2%),and PPM_(2.5)(31%-46.9%).This study provided a reference for controlling co-pollution events and improving air quality in Beijing.展开更多
To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) po...To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) pollution control strategies.However,currently widely-used methods,such as statistical models and numerical models,exhibit inherent limitations in identifying OPS in a timely and accurate manner.In this study,we developed a novel approach to identify OPS based on eXtreme Gradient Boosting model,Shapley additive explanation(SHAP)al-gorithm,and volatile organic compound(VOC)photochemical decay adjustment,using the meteorology and speciated pollutant monitoring data as the input.By comparing the difference in SHAP values between base sce-nario and precursor reduction scenario for nitrogen oxides(NO_(x))and VOCs,OPS was divided into NO_(x)-limited,VOCs-limited and transition regime.Using the long-lasting O_(3) pollution episode in the autumn of 2022 at the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)as an example,we demonstrated large spatiotemporal heterogeneities of OPS over the GBA,which were generally shifted from NO_(x)-limited to VOCs-limited from September to October and more inclined to be VOCs-limited at the central and NO_(x)-limited in the peripheral areas.This study developed an innovative OPS identification method by comparing the difference in SHAP value before and after precursor emission reduction.Our method enables the accurate identification of OPS in the time scale of seconds,thereby providing a state-of-the-art tool for the rapid guidance of spatial-specific O_(3) control strategies.展开更多
This study uses the WRF-Chem model combined with the empirical kinetic modeling method(EKMA curve)to study the compound pollution event in Beijing that happened in 13−23 May 2017.Sensitivity tests are conducted to ana...This study uses the WRF-Chem model combined with the empirical kinetic modeling method(EKMA curve)to study the compound pollution event in Beijing that happened in 13−23 May 2017.Sensitivity tests are conducted to analyze ozone sensitivity to its precursors,and to develop emission reduction measures.The results suggest that the model can accurately simulate the compound pollution process of photochemistry and haze.When VOCs and NOx were reduced by the same proportion,the effect of O_(3)reduction at peak time was more obvious,and the effect during daytime was more significant than at night.The degree of change in ozone was peak time>daytime average.When reducing or increasing the ratio of precursors by 25%at the same time,the effect of reducing 25%VOCs on the average ozone concentration reduction was most significant.The degree of change in ozone decreased with increasing altitude,the location of the ozone maximum change shifted westward,and its range narrowed.As the altitude increases,the VOCs-limited zone decreases,VOCs sensitivity decreases,NOx sensitivity increases.The controlled area changed from near-surface VOCs-limited to high-altitude NOx-limited.Upon examining the EKMA curve,we have found that suburban and urban are sensitive to VOCs.The sensitivity tests indicate that when VOCs in suburban are reduced about 60%,the O_(3)-1h concentration could reach the standard,and when VOCs of the urban decreased by about 50%,the O_(3)-1h concentration could reach the standard.Thus,these findings could provide references for the control of compound air pollution in Beijing.展开更多
In this study,we report the fabrication of a sensitive deep ultraviolet(DUV)photodetector by using CsPbBr_(3) nanosheets synthesized through confined-space growth at room temperature.The peak pho-toresponse of the dev...In this study,we report the fabrication of a sensitive deep ultraviolet(DUV)photodetector by using CsPbBr_(3) nanosheets synthesized through confined-space growth at room temperature.The peak pho-toresponse of the device upon illumination blueshifts with decreasing thickness and a 68 nm CsPbBr_(3) nanosheet based device displays a peak response to 265 nm illumination,showing responsivity and spe-cific detectivity of 85 mA/W and 4.05×1011 Jones at 3 V bias,respectively.Theoretical simulation re-veals that the blueshift is associated with the wavelength-dependent absorption coefficient of CsPbBr_(3) nanosheet:incident light with shorter wavelengths can be absorbed on the superficial surface,while long-wavelength light has a larger penetration depth,leading to dominant DUV absorption in thinner CsPbBr_(3) nanosheet.This work will shed light on the facile and cost-effective fabrication of DUV photode-tectors from non-ultrawide bandgap(UWBG)all-inorganic perovskite materials.展开更多
Broadband sensitization is an effective strategy to enhance the upconversion luminescence(UCL) of lanthanide ions.Herein,novel UC materials LiScSi_(2)O_(6):Cr^(3+)/Er^(3+)(LSS:Cr^(3+)/Er^(3+)) were synthesized by high...Broadband sensitization is an effective strategy to enhance the upconversion luminescence(UCL) of lanthanide ions.Herein,novel UC materials LiScSi_(2)O_(6):Cr^(3+)/Er^(3+)(LSS:Cr^(3+)/Er^(3+)) were synthesized by high-temperature solid state reaction and their luminescent properties were investigated.LSS:Cr^(3+)/Er^(3+)has the broadband absorption in the spectral range of 600-800 nm,and meanwhile shows green UC emissions of Er^(3+)upon pumping Cr^(3+) by the 690 nm laser.The UCL of LSS:Cr^(3+)/Er^(3+)belongs to the twophoton process and is attributed to the energy transfer upconversion mechanism.The effects of the Cr^(3+)and Er^(3+)concentration as well as the Yb^(3+)introduction were also studied.LSS:Cr^(3+)/Yb^(3+)/Er^(3+) exhibits the interesting dual-mode UCL,capable of generating the UCL of Cr^(3+) upon pumping Yb^(3+)ions and the UCL of upon pumping Cr^(3+) ions.This research might promote the development of novel broadband Cr^(3+)-sensitized UC materials.展开更多
The past few years witnessed extensive emergence of short-wavelength upconversion(UC)emission stimulated photoactivation studies.However,low efficiency of multi-photon process greatly limits further applications.Here,...The past few years witnessed extensive emergence of short-wavelength upconversion(UC)emission stimulated photoactivation studies.However,low efficiency of multi-photon process greatly limits further applications.Here,ultraviolet(UV)upconversion emissions originated from multi-photon process of Tm^3+were studied with Nd^3+-sensitized NaGdF4:Yb,Tm@NaYF4:Nd,Yb core/shell nanoparticles.Crucial factors,including the contents of sensitizers Nd^3+,Yb^3+and activator Tm^3+,as well as the excitation power density were investigated based on the UV emission.Spectral results showed that high contents of Nd^3+in shell region up to 50%(molar fraction hereafter)and Yb^3+of 10%were essential to mediate the energy transfer via the core/shell interface and facilitate multi-photon UV emissions.Compared with segregated activator and sensitizer,a core/shell strategy with isolated Nd^3+in the shell was important for higher UV emission.Although the upconverting process was initiated with Nd^3+→Yb^3+,the short-wavelength emissions were intrinsically coming from four-and five-photon process.The optimized nanoparticles were found to be able to manipulate the configuration transition of azobenzene molecules,and it could be promising for near infrared(NIR)triggered optical switches applications.展开更多
Carbon dioxide gas sensors based on BaTiO3-CuO composite with different concentrations of Ag addition（1,1.5 and 2 wt%） have been prepared by stander ceramic method and sintered at 500 and 700℃ for 5 h.Electrical co...Carbon dioxide gas sensors based on BaTiO3-CuO composite with different concentrations of Ag addition（1,1.5 and 2 wt%） have been prepared by stander ceramic method and sintered at 500 and 700℃ for 5 h.Electrical conductivity and gas sensing properties of the prepared samples were investigated.Electrical conductivity measurement was used to characterize the obtained sintered sensor pellets.It was found that electrical conductivity and the sensitivity to CO2 were improved with Ag addition and sintering.The correlation between Ag content at different sintering temperature and sensing characteristics towards CO2 is discussed.展开更多
This work presents the results of the exact computation of (180)<sup>3</sup> = 5,832,000 third-order mixed sensitivities of the leakage response of a polyethylene-reflected plutonium (PERP) experimental be...This work presents the results of the exact computation of (180)<sup>3</sup> = 5,832,000 third-order mixed sensitivities of the leakage response of a polyethylene-reflected plutonium (PERP) experimental benchmark with respect to the benchmark’s 180 microscopic total cross sections. This computation was made possible by applying the Third-Order Adjoint Sensitivity Analysis Methodology developed by Cacuci. The numerical results obtained in this work revealed that many of the 3<sup>rd</sup>-order sensitivities are significantly larger than their corresponding 1<sup>st</sup>- and 2<sup>nd</sup>-order ones, which is contrary to the widely held belief that higher-order sensitivities are all much smaller and hence less important than the first-order ones, for reactor physics systems. In particular, the largest 3<sup>rd</sup>-order relative sensitivity is the mixed sensitivity <img src="Edit_754b8437-dfdf-487d-af68-c78c637e6d4e.png" width="180" height="24" alt="" />of the PERP leakage response with respect to the lowest energy-group (30) total cross sections of <sup>1</sup>H (“isotope 6”) and <sup>239</sup>Pu (“isotope 1”). These two isotopes are shown in this work to be the two most important parameters affecting the PERP benchmark’s leakage response. By comparison, the largest 1<sup>st</sup>-order sensitivity is that of the PERP leakage response with respect to the lowest energy-group total cross section of isotope <sup>1</sup>H, having the value <img src="Edit_a5cfcc11-6a99-41ee-b844-a5ee84b454b3.png" width="100" height="24" alt="" />, while the largest 2<sup>nd</sup>-order sensitivity is <img src="Edit_05166a2b-97f7-43f1-98ff-b21368c00228.png" width="120" height="22" alt="" />. The 3<sup>rd</sup>-order sensitivity analysis presented in this work is the first ever such analysis in the field of reactor physics. The consequences of the results presented in this work on the uncertainty analysis of the PERP benchmark’s leakage response will be presented in a subsequent work.展开更多
Nowadays,water pollution has become more serious,greatly affecting human life and healthy.Electrochemical biosensor,a novel and rapid detection technique,plays an important role in the realtime and trace detection of ...Nowadays,water pollution has become more serious,greatly affecting human life and healthy.Electrochemical biosensor,a novel and rapid detection technique,plays an important role in the realtime and trace detection of water pollutants.However,the stability and sensitivity of electrochemical biosensors remain a great challenge for practical detections in real samples to the strong interferences derived from complex components and coagulation effects.In this work,we reported a novel threedimensional architecture of Prussian blue nanoparticles(PBNPs)/Pt nanoparticles(PtNPs)composite film,using 3 D interweaved carbon nanofibers as a supporting matrix,for the construction of screenprinted microchips-based biosensor.PtNPs with diameters of-2.5 nm was highly dispersed on the carbon nanofibers(CNFs)to build a 3 D skeleton nanostructure through a solvothermal reduction.Subsequently,uniform PBNPs were in-situ self-assembled on this skeleton to construct a 3 D architecture of PB/Pt-CNF composite film.Due to the synergistic effects derived from this special feature,the as-prepared hydroquinone(HQ)biosensor chips can synchronously promote both surface area and conductivity to greatly enhance the electrocatalysis from enzymatic reaction.This biosensor has exhibited a high sensitivity of 220.28μA·L·mmol^(-1)·cm^(-2) with an ultrawide linear range from 2.5μmol·L^(-1) to 1.45 mmol·L^(-1) at a low potential of 0.15 V,as well as the satisfactory reproducibility and usage stability.Besides,its accuracy was also verified in the assays of real water samples.It is highly expected that the 3 D PB/Pt-CNF based screen-printed microchips will have wide applications in dynamic monitoring and early warning of analytes in the various practical fields.展开更多
The authors evaluated and compared the behavior of PM2.5 with respect to NOx and NH3 emission changes in high(the year 2013)and low(the year 2018)SO2 emission cases.Two groups of simulations were conducted based on an...The authors evaluated and compared the behavior of PM2.5 with respect to NOx and NH3 emission changes in high(the year 2013)and low(the year 2018)SO2 emission cases.Two groups of simulations were conducted based on anthropogenic emissions from China in 2013 and 2018,respectively.In each group of simulations,a respective 25%reduction in NOx and NH3 emissions were assumed.A sensitivity factor(β)was defined as the relative change in PM2.5 concentration due to 1%change in NOx or NH3 emissions.In the high SO2 emissions case,PM2.5 was more sensitive to NH3(0.31)emissions change than NOx(0.21).Due to the significant decrease in SO2 emissions from the high to low SO2 emissions case,the sensitivity of PM2.5 to NOx increased to 0.33,while its sensitivity to NH3 decreased to 0.22.The result implies that now and in the future,PM2.5 is/will be less sensitive to NH3 emissions change,while NOx emissions control is more effective in reducing the surface PM2.5 concentration.Seasonally,in the low SO2 emissions case,the sensitivities of PM2.5 to NOx and NH3 in winter were higher than those in summer,indicating that to dealwith severewinter hazemore attention should be paid to the emissions control of inorganic PM2.5 precursors,especially NOx.展开更多
基金Mechanistic Investigation into the Extraction,Purification,and Anti-Esophageal Cancer Effects of Gallic Acid Derived from Rhodiola crenulata(YLUKLM2023001).
文摘Background:Gallic acid(GA),a plant-derived polyphenol,possesses diverse biological functions such as reducing inflammation and against tumors.Currently,the influence of GA on the resistance of esophageal squamous cell carcinoma(ESCC)cells to cisplatin(DDP)is not well understood.Methods:Cell counting kit-8 assay examined how GA affected KYSE30 and TE-1 cell viability.5-Ethynyl-2′-deoxyuridine and TdT-mediated dUTP Nick-End labeling staining detected cell proliferation and apoptosis.Clone formation assay,flow cytometry,Carboxyfluorescein diacetate succinimidyl ester fluorescent probes,and Transwell assay determined cell biological properties,and 2′,7′-Dichlorofluorescin diacetate(DCFH-DA)fluorescent probes detected oxidative stress levels.Signal transducer and activator of transcription 3(STAT3)/Notch pathway protein levels after GA and/or Interleukin-6(IL-6)intervention were examined through Western blot.Furthermore,a model for subcutaneous graft tumors was established in nude mice.Results:GA exerted suppressive effects on cell proliferation,and caused apoptosis of KYSE30 and TE-1 cells.IL-6 intervention activated the STAT3/Notch pathway and promoted the malignant biological properties of ESCC cells.In contrast,GA attenuated the effects of IL-6,while STAT3 or Notch inhibitor further enhanced the effects of GA,suggesting that GA inhibited the IL-6/STAT3/Notch pathway.Not only that,GA promoted oxidative stress and enhanced cell sensitivity to DDP both in vitro and in vivo.Conclusion:GA suppresses the malignant progression of ESCC and enhances cell sensitivity to DDP by hindering the IL-6/STAT3/Notch pathway.
基金financially supported by the National Key R&D Program of China (2022YFE0197100, 2023YFB4603500)Shenzhen Science and Technology Innovation Commission (KQTD20190929172505711)+1 种基金supported by MOE SUTD Kickstarter initiative (SKI2021_02_16)Singapore Ministry of Education academic research grant Tier 2 (MOE-T2EP50121-0007).
文摘Organohydrogel-based strain sensors are gaining attention for real-time health services and human-machine interactions due to their flexibility,stretchability,and skin-like compliance.However,these sensors often have limited sensitivity and poor stability due to their bulk structure and strain concentration during stretching.In this study,we designed and fabricated diamond-,grid-,and peanut-shaped organohydrogel based on positive,near-zero,and negative Poisson’s ratios using digital light processing(DLP)-based 3D printing technology.Through structural design and optimization,the grid-shaped organohydrogel exhibited record sensitivity with gauge factors of 4.5(0–200%strain,ionic mode)and 13.5/1.5×10^(6)(0-2%/2%-100%strain,electronic mode),alongside full resistance recovery for enhanced stability.The 3D-printed grid structure enabled direct wearability and breathability,overcoming traditional sensor limitations.Integrated with a robotic hand system,this sensor demonstrated clinical potential through precise monitoring of paralyzed patients’grasping movements(with a minimum monitoring angle of 5°).This structural design paradigm advanced flexible electronics by synergizing high sensitivity,stability,wearability,and breathability for healthcare,and human-machine interfaces.
基金supported by the National Key Research and Development Program of China(No.2022YFC3701205)the National Natural Science Foundation of China(No.41975173)the Science and Technology Development Fund of the Chinese Academy of Meteorological Sciences(No.2021KJ011)。
文摘In recent years,incidents of simultaneous exceedance of PM_(2.5)and O_(3) concentrations,termed PM_(2.5)and O_(3) co-pollution events,have frequently occurred in China.This study conducted atmospheric circulation analysis on two typical co-pollution events in Beijing,occurring from July 22 to July 28,2019,and from April 25 to May 2,2020.These events were categorized into pre-trough southerly airflow type(Type 1)and post-trough northwest flow type(Type 2).Subsequently,sensitivity analyses using the GRAPES-CUACE adjoint model were performed to quantify the contributions of precursor emissions from Beijing and surrounding areas to PM_(2.5)and O_(3) concentrations in Beijing for two types of co-pollution.The results indicated that the spatiotemporal distribution of sensitive source region varied among different circulation types.Primary PM_(2.5)(PPM_(2.5))emissions from Hebei contributed the most to the 24-hour average PM_(2.5)(24-h PM_(2.5))peak concentration(41.6%-45.4%),followed by Beijing emissions(31%-35.7%).The maximum daily 8-hour average ozone peak concentration was primarily influenced by the emissions from Hebei and Beijing,with contribution ratios respectively of 32.8%-44.8% and 29%-42.1%.Additionally,NO_(x)emissions were the main contributors in Type 1,while both NO_(x)and VOCs emissions contributed similarly in Type 2.The iterative emission reduction experiments for two types of co-pollution indicated that Type 1 required emission reductions in NO_(x)(52.4%-71.8%)and VOCs(14.1%-33.8%)only.In contrast,Type 2 required combined emission reductions in NO_(x)(37.0%-65.1%),VOCs(30.7%-56.2%),and PPM_(2.5)(31%-46.9%).This study provided a reference for controlling co-pollution events and improving air quality in Beijing.
基金supported by the Key-Area Research and Development Program of Guangdong Province(No.2020B1111360003)the National Natural Science Foundation of China(Nos.42465008 and 42105164)+2 种基金Yunnan Science and Technology Department Project(No.202501AT070239)Yunnan Science and Technology Department Youth Project(No.202401AU070202)Xianyang Rapid Response Decision Support Project for Ozone(No.YZ2024-ZB019).
文摘To curb the worsening tropospheric ozone(O_(3))pollution problem in China,a rapid and accurate identification of O_(3)-precursor sensitivity(OPS)is a crucial prerequisite for formulating effective contingency O_(3) pollution control strategies.However,currently widely-used methods,such as statistical models and numerical models,exhibit inherent limitations in identifying OPS in a timely and accurate manner.In this study,we developed a novel approach to identify OPS based on eXtreme Gradient Boosting model,Shapley additive explanation(SHAP)al-gorithm,and volatile organic compound(VOC)photochemical decay adjustment,using the meteorology and speciated pollutant monitoring data as the input.By comparing the difference in SHAP values between base sce-nario and precursor reduction scenario for nitrogen oxides(NO_(x))and VOCs,OPS was divided into NO_(x)-limited,VOCs-limited and transition regime.Using the long-lasting O_(3) pollution episode in the autumn of 2022 at the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)as an example,we demonstrated large spatiotemporal heterogeneities of OPS over the GBA,which were generally shifted from NO_(x)-limited to VOCs-limited from September to October and more inclined to be VOCs-limited at the central and NO_(x)-limited in the peripheral areas.This study developed an innovative OPS identification method by comparing the difference in SHAP value before and after precursor emission reduction.Our method enables the accurate identification of OPS in the time scale of seconds,thereby providing a state-of-the-art tool for the rapid guidance of spatial-specific O_(3) control strategies.
基金This study is funded by Air Pollution Special Project of the Ministry of Science and Technology(Grant No.2017YFCOZ10006)the National Natural Science Foundation of China(Grant No.41975173)。
文摘This study uses the WRF-Chem model combined with the empirical kinetic modeling method(EKMA curve)to study the compound pollution event in Beijing that happened in 13−23 May 2017.Sensitivity tests are conducted to analyze ozone sensitivity to its precursors,and to develop emission reduction measures.The results suggest that the model can accurately simulate the compound pollution process of photochemistry and haze.When VOCs and NOx were reduced by the same proportion,the effect of O_(3)reduction at peak time was more obvious,and the effect during daytime was more significant than at night.The degree of change in ozone was peak time>daytime average.When reducing or increasing the ratio of precursors by 25%at the same time,the effect of reducing 25%VOCs on the average ozone concentration reduction was most significant.The degree of change in ozone decreased with increasing altitude,the location of the ozone maximum change shifted westward,and its range narrowed.As the altitude increases,the VOCs-limited zone decreases,VOCs sensitivity decreases,NOx sensitivity increases.The controlled area changed from near-surface VOCs-limited to high-altitude NOx-limited.Upon examining the EKMA curve,we have found that suburban and urban are sensitive to VOCs.The sensitivity tests indicate that when VOCs in suburban are reduced about 60%,the O_(3)-1h concentration could reach the standard,and when VOCs of the urban decreased by about 50%,the O_(3)-1h concentration could reach the standard.Thus,these findings could provide references for the control of compound air pollution in Beijing.
基金the National Natural Science Foundation of China(No.62074048)the Key Research and Development Plan of Anhui Province(No.2022f04020007)+1 种基金the Natural Science Foundation of Anhui Province(No.2208085MF177)the Fundamental Research Funds for the Central Universities(No.PA2020GDKC0014).
文摘In this study,we report the fabrication of a sensitive deep ultraviolet(DUV)photodetector by using CsPbBr_(3) nanosheets synthesized through confined-space growth at room temperature.The peak pho-toresponse of the device upon illumination blueshifts with decreasing thickness and a 68 nm CsPbBr_(3) nanosheet based device displays a peak response to 265 nm illumination,showing responsivity and spe-cific detectivity of 85 mA/W and 4.05×1011 Jones at 3 V bias,respectively.Theoretical simulation re-veals that the blueshift is associated with the wavelength-dependent absorption coefficient of CsPbBr_(3) nanosheet:incident light with shorter wavelengths can be absorbed on the superficial surface,while long-wavelength light has a larger penetration depth,leading to dominant DUV absorption in thinner CsPbBr_(3) nanosheet.This work will shed light on the facile and cost-effective fabrication of DUV photode-tectors from non-ultrawide bandgap(UWBG)all-inorganic perovskite materials.
基金supported by the Natural Science Foundation of Jiangsu Province of China (BK20160073)the Fundamental Research Funds for the Central Universities (2242019K40061)。
文摘Broadband sensitization is an effective strategy to enhance the upconversion luminescence(UCL) of lanthanide ions.Herein,novel UC materials LiScSi_(2)O_(6):Cr^(3+)/Er^(3+)(LSS:Cr^(3+)/Er^(3+)) were synthesized by high-temperature solid state reaction and their luminescent properties were investigated.LSS:Cr^(3+)/Er^(3+)has the broadband absorption in the spectral range of 600-800 nm,and meanwhile shows green UC emissions of Er^(3+)upon pumping Cr^(3+) by the 690 nm laser.The UCL of LSS:Cr^(3+)/Er^(3+)belongs to the twophoton process and is attributed to the energy transfer upconversion mechanism.The effects of the Cr^(3+)and Er^(3+)concentration as well as the Yb^(3+)introduction were also studied.LSS:Cr^(3+)/Yb^(3+)/Er^(3+) exhibits the interesting dual-mode UCL,capable of generating the UCL of Cr^(3+) upon pumping Yb^(3+)ions and the UCL of upon pumping Cr^(3+) ions.This research might promote the development of novel broadband Cr^(3+)-sensitized UC materials.
基金Project supported by National Natural Science Foundation of China(21425101,21331001,21371011)Ministry of Science and Technology of China(2014CB643800)
文摘The past few years witnessed extensive emergence of short-wavelength upconversion(UC)emission stimulated photoactivation studies.However,low efficiency of multi-photon process greatly limits further applications.Here,ultraviolet(UV)upconversion emissions originated from multi-photon process of Tm^3+were studied with Nd^3+-sensitized NaGdF4:Yb,Tm@NaYF4:Nd,Yb core/shell nanoparticles.Crucial factors,including the contents of sensitizers Nd^3+,Yb^3+and activator Tm^3+,as well as the excitation power density were investigated based on the UV emission.Spectral results showed that high contents of Nd^3+in shell region up to 50%(molar fraction hereafter)and Yb^3+of 10%were essential to mediate the energy transfer via the core/shell interface and facilitate multi-photon UV emissions.Compared with segregated activator and sensitizer,a core/shell strategy with isolated Nd^3+in the shell was important for higher UV emission.Although the upconverting process was initiated with Nd^3+→Yb^3+,the short-wavelength emissions were intrinsically coming from four-and five-photon process.The optimized nanoparticles were found to be able to manipulate the configuration transition of azobenzene molecules,and it could be promising for near infrared(NIR)triggered optical switches applications.
文摘Carbon dioxide gas sensors based on BaTiO3-CuO composite with different concentrations of Ag addition（1,1.5 and 2 wt%） have been prepared by stander ceramic method and sintered at 500 and 700℃ for 5 h.Electrical conductivity and gas sensing properties of the prepared samples were investigated.Electrical conductivity measurement was used to characterize the obtained sintered sensor pellets.It was found that electrical conductivity and the sensitivity to CO2 were improved with Ag addition and sintering.The correlation between Ag content at different sintering temperature and sensing characteristics towards CO2 is discussed.
文摘This work presents the results of the exact computation of (180)<sup>3</sup> = 5,832,000 third-order mixed sensitivities of the leakage response of a polyethylene-reflected plutonium (PERP) experimental benchmark with respect to the benchmark’s 180 microscopic total cross sections. This computation was made possible by applying the Third-Order Adjoint Sensitivity Analysis Methodology developed by Cacuci. The numerical results obtained in this work revealed that many of the 3<sup>rd</sup>-order sensitivities are significantly larger than their corresponding 1<sup>st</sup>- and 2<sup>nd</sup>-order ones, which is contrary to the widely held belief that higher-order sensitivities are all much smaller and hence less important than the first-order ones, for reactor physics systems. In particular, the largest 3<sup>rd</sup>-order relative sensitivity is the mixed sensitivity <img src="Edit_754b8437-dfdf-487d-af68-c78c637e6d4e.png" width="180" height="24" alt="" />of the PERP leakage response with respect to the lowest energy-group (30) total cross sections of <sup>1</sup>H (“isotope 6”) and <sup>239</sup>Pu (“isotope 1”). These two isotopes are shown in this work to be the two most important parameters affecting the PERP benchmark’s leakage response. By comparison, the largest 1<sup>st</sup>-order sensitivity is that of the PERP leakage response with respect to the lowest energy-group total cross section of isotope <sup>1</sup>H, having the value <img src="Edit_a5cfcc11-6a99-41ee-b844-a5ee84b454b3.png" width="100" height="24" alt="" />, while the largest 2<sup>nd</sup>-order sensitivity is <img src="Edit_05166a2b-97f7-43f1-98ff-b21368c00228.png" width="120" height="22" alt="" />. The 3<sup>rd</sup>-order sensitivity analysis presented in this work is the first ever such analysis in the field of reactor physics. The consequences of the results presented in this work on the uncertainty analysis of the PERP benchmark’s leakage response will be presented in a subsequent work.
基金financially supported by the National Natural Science Foundation of China(22078148 and 21727818)the Innovative Research Team Program by the Ministry of Education of China(IRT_17R54)+3 种基金the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Key Project by Medical Science and Technology Development Foundation of Nanjing Department of Health(ZKX17014)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX20_1021)。
文摘Nowadays,water pollution has become more serious,greatly affecting human life and healthy.Electrochemical biosensor,a novel and rapid detection technique,plays an important role in the realtime and trace detection of water pollutants.However,the stability and sensitivity of electrochemical biosensors remain a great challenge for practical detections in real samples to the strong interferences derived from complex components and coagulation effects.In this work,we reported a novel threedimensional architecture of Prussian blue nanoparticles(PBNPs)/Pt nanoparticles(PtNPs)composite film,using 3 D interweaved carbon nanofibers as a supporting matrix,for the construction of screenprinted microchips-based biosensor.PtNPs with diameters of-2.5 nm was highly dispersed on the carbon nanofibers(CNFs)to build a 3 D skeleton nanostructure through a solvothermal reduction.Subsequently,uniform PBNPs were in-situ self-assembled on this skeleton to construct a 3 D architecture of PB/Pt-CNF composite film.Due to the synergistic effects derived from this special feature,the as-prepared hydroquinone(HQ)biosensor chips can synchronously promote both surface area and conductivity to greatly enhance the electrocatalysis from enzymatic reaction.This biosensor has exhibited a high sensitivity of 220.28μA·L·mmol^(-1)·cm^(-2) with an ultrawide linear range from 2.5μmol·L^(-1) to 1.45 mmol·L^(-1) at a low potential of 0.15 V,as well as the satisfactory reproducibility and usage stability.Besides,its accuracy was also verified in the assays of real water samples.It is highly expected that the 3 D PB/Pt-CNF based screen-printed microchips will have wide applications in dynamic monitoring and early warning of analytes in the various practical fields.
基金This work was supported by the National Natural Science Foundation of China[grant number 41805098].
文摘The authors evaluated and compared the behavior of PM2.5 with respect to NOx and NH3 emission changes in high(the year 2013)and low(the year 2018)SO2 emission cases.Two groups of simulations were conducted based on anthropogenic emissions from China in 2013 and 2018,respectively.In each group of simulations,a respective 25%reduction in NOx and NH3 emissions were assumed.A sensitivity factor(β)was defined as the relative change in PM2.5 concentration due to 1%change in NOx or NH3 emissions.In the high SO2 emissions case,PM2.5 was more sensitive to NH3(0.31)emissions change than NOx(0.21).Due to the significant decrease in SO2 emissions from the high to low SO2 emissions case,the sensitivity of PM2.5 to NOx increased to 0.33,while its sensitivity to NH3 decreased to 0.22.The result implies that now and in the future,PM2.5 is/will be less sensitive to NH3 emissions change,while NOx emissions control is more effective in reducing the surface PM2.5 concentration.Seasonally,in the low SO2 emissions case,the sensitivities of PM2.5 to NOx and NH3 in winter were higher than those in summer,indicating that to dealwith severewinter hazemore attention should be paid to the emissions control of inorganic PM2.5 precursors,especially NOx.
