Because of their effect on climate,carbon dioxide(CO_(2)),methane(CH_(4)),nitrous oxide(N_(2)O),and dimethylsulfide(DMS)are collectively designated as climate-relevant gases(CRGs).CO_(2),CH_(4),and N_(2)O are greenhou...Because of their effect on climate,carbon dioxide(CO_(2)),methane(CH_(4)),nitrous oxide(N_(2)O),and dimethylsulfide(DMS)are collectively designated as climate-relevant gases(CRGs).CO_(2),CH_(4),and N_(2)O are greenhouse gases contributing to global warming(positive climate feedback).Conversely,DMS is involved in the generation of cloud condensation nuclei,thus in the formation of clouds that cool the boundary layer by reflecting incoming solar radiation(negative climate feedback).Despite their scarcity,field observations and model results have demonstrated the essential role of polar oceans in the budget of CRGs.For example,the Southern Ocean represents a substantial CO_(2)sink but a source of N_(2)O and DMS,thereby exerting variable feedback on climate change.Unfortunately,because of the severe environmental conditions at polar latitudes,substantial knowledge gaps remain,for example on the mechanisms underlying CRGs formation or on the strength and distribution of their sources and sinks in the Southern and Arctic Oceans.Here,we review the most recent research results on the distribution,production-loss processes,and abundance variations of CRGs in the polar oceans.We list the remaining knowledge gaps and propose future directions of research on CRGs in the polar oceans,as a useful reference for future studies.展开更多
Electro-Optic Sampling(EOS)detection technique has been widely used in terahertz science and tech⁃nology,and it also can measure the field time waveform of the few-cycle laser pulse.Its frequency response and band lim...Electro-Optic Sampling(EOS)detection technique has been widely used in terahertz science and tech⁃nology,and it also can measure the field time waveform of the few-cycle laser pulse.Its frequency response and band limitation are determined directly by the electro-optic crystal and duration of the probe laser pulse.Here,we investigate the performance of the EOS with thin GaSe crystal in the measurement of the mid-infrared few-cycle la⁃ser pulse.The shift of the central frequency and change of the bandwidth induced by the EOS detection are calcu⁃lated,and then the pulse distortions induced in this detection process are discussed.It is found that this technique produces a red-shift of the central frequency and narrowing of the bandwidth.These changings decrease when the laser wavelength increases from 2μm to 10μm.This work can help to estimate the performance of the EOS de⁃tection technique in the mid-infrared band and offer a reference for the related experiment as well.展开更多
Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moder...Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moderate band gaps,which offer a good platform to explore their thermoelectric properties.Here,we demonstrate by first-principles calculations that the two systems have very similar band structures and phonon dispersions,despite different stacking sequences between adjacent layers.Interestingly,the lattice thermal conductivity of ε-GaSe is obviously lower than that of β-GaSe,which is inherently tied to stronger lattice anharmonicity caused by bonding heterogeneity.Besides,both systems exhibit higher p-type power factors due to doubly degenerate bands with weaker dispersions around the valence band maximum.As a consequence,a significantly enhanced p-type figure-of-merit of 2.1 can be realized at 700 K along the out-of-plane direction of theε-phase.展开更多
We study the shock structure and the sub-shock formation in a binary mixture of rarefied polyatomic gases,considering the dissipation only due to the dynamic pressure.We classify the regions depending on the concentra...We study the shock structure and the sub-shock formation in a binary mixture of rarefied polyatomic gases,considering the dissipation only due to the dynamic pressure.We classify the regions depending on the concentration and the Mach number for which there may exist the sub-shock in the profile of shock structure in one or both constituents or not for prescribed values of the mass ratio of the constituents and the ratios of the specific heats.We compare the regions with the ones of the corresponding mixture of Eulerian gases and perform the numerical calculations of the shock structure for typical cases previously classified and confirm whether sub-shocks emerge.展开更多
The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity funct...The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious.展开更多
This study presents a comprehensive overview of the atmospheric pollutants including Sulfur dioxide(SO_(2)),Nitrogen dioxide(NO_(2)),Formaldehyde(HCHO),Particulate Matter PM;PM_(10):diameter≤10μm,and PM_(2.5):diame...This study presents a comprehensive overview of the atmospheric pollutants including Sulfur dioxide(SO_(2)),Nitrogen dioxide(NO_(2)),Formaldehyde(HCHO),Particulate Matter PM;PM_(10):diameter≤10μm,and PM_(2.5):diameter≤2.5μm,and Ozone(O_(3)),over Dongying(Shandong Province)from March-April 2018 and September-October 2019 by employing ground-based Multiple Axis Differential Optical Absorption Spectroscopy(MAX-DOAS)observations along with the in-situ measurements attained by the national air quality monitoring platform.The concentrations of SO_(2)and NO_(2)were under the acceptable level,while both PM_(2.5),and PM_(10)were higher than the safe levels as prescribed by national and international air quality standards.The results depict that 21%of the total observation days were found to be complex polluted days(PM_(2.5)>35μg/m^(3) and O_(3)>160μg/m^(3)).The secondary HCHO was used for accurate analysis of O_(3)sensitivity.A difference of 11.40%and 10%during March-April 2018 and September-October 2019 respectively in O_(3)sensitivity was found between HCHO_(total)/NO_(2)and HCHO_(sec)/NO_(2).The results indicate that primary HCHO have significant contribution in HCHO.O_(3)formation predominantly remained to be in VOC-limited and transitional regime during March-April 2018 and September-October 2019 in Dongying.These results imply that concurrent control of both NO_(x) and VOCs would benefit in ozone reductions.Additionally,the criteria pollutants(PM,SO_(2),and NO_(2))depicted strong correlations with each other except for O_(3)for which weak correlation coefficient was obtained with all the species.This study will prove to be baseline for designing of air pollution control strategies.展开更多
Motivated by experiments with interacting quantum gases across high partial wave resonance,we investigate the thermodynamic properties and single-particle spectra of Bose gases in normal phase for different interactio...Motivated by experiments with interacting quantum gases across high partial wave resonance,we investigate the thermodynamic properties and single-particle spectra of Bose gases in normal phase for different interaction strengths for both p-and d-wave interactions.The equation of state,contact density,momentum distributions and self-energies of single-particle Green’s functions are obtained in the spirit of ladder diagram approximations.The radio-frequency(RF)spectrum,as an important experimental approach for detecting Feshbach molecules or the interaction effect,is calculated at different temperatures.A reversed temperature dependence on the Bose–Einstein condensation side and Bardeen–Cooper–Schrieffer side is identified for both p-and d-wave interactions.An estimate for the signal of RF spectra under typical experimental conditions is also provided.展开更多
Two-dimensional(2D)materials have gained considerable attention in chemical sensing owing to their naturally high surface-to-volume ratio.However,the poor response time and incomplete recovery re-strict their applicat...Two-dimensional(2D)materials have gained considerable attention in chemical sensing owing to their naturally high surface-to-volume ratio.However,the poor response time and incomplete recovery re-strict their application in practical,high performance gas sensors.In this work,we fabricated air-stable ReS_(2)/GaSe heterostructure-based NO_(2)gas sensors with excellent gas sensing response,recovery,selectiv-ity and a low limit of detection(LOD)toward nitrogen dioxide(NO_(2)).The ReS_(2)/GaSe heterostructure was prepared via mechanical exfoliation and an all-dry transfer method.Before the sensing measurements,temperature-dependant transport measurements were carried out.The Schottky Barrier Height(SBH)of the ReS_(2)/GaSe heterostructure was calculated and the corresponding transport mechanisms were dis-cussed.The fabricated gas sensors showed a significant response enhancement with full reversibility to-ward ppm-level NO_(2)(response of∼17%at 3 ppm,a LOD of∼556 ppb)at an operating temperature of(33°C).In particular,the total response and recovery time of the ReS_(2)/GaSe was revealed to be less than 4 min(∼38 s and∼174 s,respectively)for the 250 ppm concentration,which is one of the best response and recovery time toward ppm-level NO_(2).The excellent sensing performances and recovery characteris-tics of the ReS_(2)/GaSe structure are attributed to its efficient charge separation,unique interlayer coupling and desirable band alignments.This atomically thin,ultrasensitive gas sensor that operates at room tem-perature is a strong technological contender to conventional metal oxide gas sensors,which often require elevated temperatures.展开更多
The catalytic combustion technology for treating waste gases exiting from wastewater treatment system and oil separators in petrochemical enterprises was introduced in this article. Commercial application of this tech...The catalytic combustion technology for treating waste gases exiting from wastewater treatment system and oil separators in petrochemical enterprises was introduced in this article. Commercial application of this technology showed that the process ＂desulfurization and total hydrocarbon concentration homogenizationcatalytic combustion＂ and the associated WSH-1 combustion catalyst were suitable for treating volatile organic gases emitted from the oil separators, floatation tanks, inlet water-collecting well, waste oil tanks, etc. The commercial unit was equipped with an advanced auto-control system, featuring a simple operation and low energy consumption with good treatment effect. The purified gases could meet the national emission standard.展开更多
基金supported the National Natural Science Foundation of China(Grant nos.4227624,42376239 and 42476253)。
文摘Because of their effect on climate,carbon dioxide(CO_(2)),methane(CH_(4)),nitrous oxide(N_(2)O),and dimethylsulfide(DMS)are collectively designated as climate-relevant gases(CRGs).CO_(2),CH_(4),and N_(2)O are greenhouse gases contributing to global warming(positive climate feedback).Conversely,DMS is involved in the generation of cloud condensation nuclei,thus in the formation of clouds that cool the boundary layer by reflecting incoming solar radiation(negative climate feedback).Despite their scarcity,field observations and model results have demonstrated the essential role of polar oceans in the budget of CRGs.For example,the Southern Ocean represents a substantial CO_(2)sink but a source of N_(2)O and DMS,thereby exerting variable feedback on climate change.Unfortunately,because of the severe environmental conditions at polar latitudes,substantial knowledge gaps remain,for example on the mechanisms underlying CRGs formation or on the strength and distribution of their sources and sinks in the Southern and Arctic Oceans.Here,we review the most recent research results on the distribution,production-loss processes,and abundance variations of CRGs in the polar oceans.We list the remaining knowledge gaps and propose future directions of research on CRGs in the polar oceans,as a useful reference for future studies.
基金Supported by the National Natural Science Foundation of China(12064028)Jiangxi Provincial Natural Science Foundation(20232BAB201045).
文摘Electro-Optic Sampling(EOS)detection technique has been widely used in terahertz science and tech⁃nology,and it also can measure the field time waveform of the few-cycle laser pulse.Its frequency response and band limitation are determined directly by the electro-optic crystal and duration of the probe laser pulse.Here,we investigate the performance of the EOS with thin GaSe crystal in the measurement of the mid-infrared few-cycle la⁃ser pulse.The shift of the central frequency and change of the bandwidth induced by the EOS detection are calcu⁃lated,and then the pulse distortions induced in this detection process are discussed.It is found that this technique produces a red-shift of the central frequency and narrowing of the bandwidth.These changings decrease when the laser wavelength increases from 2μm to 10μm.This work can help to estimate the performance of the EOS de⁃tection technique in the mid-infrared band and offer a reference for the related experiment as well.
基金supported by the National Natural Science Foundation of China(Grant Nos.62074114 and 12474019)。
文摘Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moderate band gaps,which offer a good platform to explore their thermoelectric properties.Here,we demonstrate by first-principles calculations that the two systems have very similar band structures and phonon dispersions,despite different stacking sequences between adjacent layers.Interestingly,the lattice thermal conductivity of ε-GaSe is obviously lower than that of β-GaSe,which is inherently tied to stronger lattice anharmonicity caused by bonding heterogeneity.Besides,both systems exhibit higher p-type power factors due to doubly degenerate bands with weaker dispersions around the valence band maximum.As a consequence,a significantly enhanced p-type figure-of-merit of 2.1 can be realized at 700 K along the out-of-plane direction of theε-phase.
基金supported by the JSPS KAKENHI Grant No.JP19K04204(S.T.).
文摘We study the shock structure and the sub-shock formation in a binary mixture of rarefied polyatomic gases,considering the dissipation only due to the dynamic pressure.We classify the regions depending on the concentration and the Mach number for which there may exist the sub-shock in the profile of shock structure in one or both constituents or not for prescribed values of the mass ratio of the constituents and the ratios of the specific heats.We compare the regions with the ones of the corresponding mixture of Eulerian gases and perform the numerical calculations of the shock structure for typical cases previously classified and confirm whether sub-shocks emerge.
文摘The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious.
基金supported by the Jiangsu Funding Program for Excellent Postdoctoral Talent (No.2022ZB651)the National Natural Science Foundation of China (No.32071521)+1 种基金the Scientific Research Foundation for Senior Talent of Jiangsu University,China (No.20JDG067)the Jiangsu Province“Double Innovation Ph D”Grant。
文摘This study presents a comprehensive overview of the atmospheric pollutants including Sulfur dioxide(SO_(2)),Nitrogen dioxide(NO_(2)),Formaldehyde(HCHO),Particulate Matter PM;PM_(10):diameter≤10μm,and PM_(2.5):diameter≤2.5μm,and Ozone(O_(3)),over Dongying(Shandong Province)from March-April 2018 and September-October 2019 by employing ground-based Multiple Axis Differential Optical Absorption Spectroscopy(MAX-DOAS)observations along with the in-situ measurements attained by the national air quality monitoring platform.The concentrations of SO_(2)and NO_(2)were under the acceptable level,while both PM_(2.5),and PM_(10)were higher than the safe levels as prescribed by national and international air quality standards.The results depict that 21%of the total observation days were found to be complex polluted days(PM_(2.5)>35μg/m^(3) and O_(3)>160μg/m^(3)).The secondary HCHO was used for accurate analysis of O_(3)sensitivity.A difference of 11.40%and 10%during March-April 2018 and September-October 2019 respectively in O_(3)sensitivity was found between HCHO_(total)/NO_(2)and HCHO_(sec)/NO_(2).The results indicate that primary HCHO have significant contribution in HCHO.O_(3)formation predominantly remained to be in VOC-limited and transitional regime during March-April 2018 and September-October 2019 in Dongying.These results imply that concurrent control of both NO_(x) and VOCs would benefit in ozone reductions.Additionally,the criteria pollutants(PM,SO_(2),and NO_(2))depicted strong correlations with each other except for O_(3)for which weak correlation coefficient was obtained with all the species.This study will prove to be baseline for designing of air pollution control strategies.
基金supported by the National Key Research and Development Program of China (Grant Nos. 2022YFA1405301 and 2018YFA0306502)the National Natural Science Foundation of China (Grant Nos. 12 022 405 and 11 774 426)the Beijing Natural Science Foundation (Grant No. Z180013)
文摘Motivated by experiments with interacting quantum gases across high partial wave resonance,we investigate the thermodynamic properties and single-particle spectra of Bose gases in normal phase for different interaction strengths for both p-and d-wave interactions.The equation of state,contact density,momentum distributions and self-energies of single-particle Green’s functions are obtained in the spirit of ladder diagram approximations.The radio-frequency(RF)spectrum,as an important experimental approach for detecting Feshbach molecules or the interaction effect,is calculated at different temperatures.A reversed temperature dependence on the Bose–Einstein condensation side and Bardeen–Cooper–Schrieffer side is identified for both p-and d-wave interactions.An estimate for the signal of RF spectra under typical experimental conditions is also provided.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)(No.2018R1A6A1A03025708)supported by the Nano-Material Technology Development Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Science,ICT and Future Planning(No.2009-0082580).
文摘Two-dimensional(2D)materials have gained considerable attention in chemical sensing owing to their naturally high surface-to-volume ratio.However,the poor response time and incomplete recovery re-strict their application in practical,high performance gas sensors.In this work,we fabricated air-stable ReS_(2)/GaSe heterostructure-based NO_(2)gas sensors with excellent gas sensing response,recovery,selectiv-ity and a low limit of detection(LOD)toward nitrogen dioxide(NO_(2)).The ReS_(2)/GaSe heterostructure was prepared via mechanical exfoliation and an all-dry transfer method.Before the sensing measurements,temperature-dependant transport measurements were carried out.The Schottky Barrier Height(SBH)of the ReS_(2)/GaSe heterostructure was calculated and the corresponding transport mechanisms were dis-cussed.The fabricated gas sensors showed a significant response enhancement with full reversibility to-ward ppm-level NO_(2)(response of∼17%at 3 ppm,a LOD of∼556 ppb)at an operating temperature of(33°C).In particular,the total response and recovery time of the ReS_(2)/GaSe was revealed to be less than 4 min(∼38 s and∼174 s,respectively)for the 250 ppm concentration,which is one of the best response and recovery time toward ppm-level NO_(2).The excellent sensing performances and recovery characteris-tics of the ReS_(2)/GaSe structure are attributed to its efficient charge separation,unique interlayer coupling and desirable band alignments.This atomically thin,ultrasensitive gas sensor that operates at room tem-perature is a strong technological contender to conventional metal oxide gas sensors,which often require elevated temperatures.
基金supported by the Federal Target Program“The scientific and Scientific-pedagogical Personnel of Innovative Russia”(No.02.740.11.04444)Russian President Grant(SS4297.2010.2)
基金Supported by RFBR Project(No.10-02-01452-a)Presidium SB RAS under the Project Ⅶ.63.3.1 of Ⅶ.63.3 Prog.Integrated Projec of 2012－2014 and Join Proj. between Presidium SB RAS and Presidium NAS,Belarus No.10 of 2010
文摘The catalytic combustion technology for treating waste gases exiting from wastewater treatment system and oil separators in petrochemical enterprises was introduced in this article. Commercial application of this technology showed that the process ＂desulfurization and total hydrocarbon concentration homogenizationcatalytic combustion＂ and the associated WSH-1 combustion catalyst were suitable for treating volatile organic gases emitted from the oil separators, floatation tanks, inlet water-collecting well, waste oil tanks, etc. The commercial unit was equipped with an advanced auto-control system, featuring a simple operation and low energy consumption with good treatment effect. The purified gases could meet the national emission standard.
