The dynamics of two-dimensional rigid circles filled with chiral active particles are investigated by employing the overdamped Langevin dynamics simulations. Unidirectional rotation of rigid circles is observed, and t...The dynamics of two-dimensional rigid circles filled with chiral active particles are investigated by employing the overdamped Langevin dynamics simulations. Unidirectional rotation of rigid circles is observed, and the rotational angular velocity（ω） relies mainly on the length（l）, the number（nB）, and tilt angle（γ） of boards, and the angular velocity（ω）and area fraction（ρ） of chiral active particles. There are optimum values for these parameters at which the average angular velocity of circle reaches its maximum. The center-of-mass mean square displacement for circles drops by about two orders of magnitude for large angular velocity ω of chiral active particles with oscillations in the short-time regime. Our work demonstrates that nanofabricated objects with suitable designs immersed in a bath of chiral active particles can extract and rectify energy in a unidirectional motion.展开更多
In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a wat...In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion.Effects of various factors on bubble disintegration and dispersion were investigated.These factors were stirring mode,eccentricity and rotation speed,nozzle structure,nozzle immersion depth,and gas flow rate.Gas injection from a nozzle at the end of the impeller shaft and from an immersed lance was studied.Under eccentric stirring,a vortex was formed away from the shaft.Small bubbles were produced in the strong turbulence or high shear stress field near the rotating impeller and moved in the direction to the vortex keeping up with the macroscopic flow induced by the mechanical stirring.Thus small bubbles could disperse widely in the bath under eccentric stirring with unidirectional rotation.展开更多
Molecular alignment and orientation by laser fields has attracted significant attention in recent years,mostly due to new capabilities to manipulate the molecular spatial arrangement.Molecules can now be efficiently p...Molecular alignment and orientation by laser fields has attracted significant attention in recent years,mostly due to new capabilities to manipulate the molecular spatial arrangement.Molecules can now be efficiently prepared for ionization,structural imaging,orbital tomography,and more,enabling,for example,shooting of dynamic molecular movies.Furthermore,molecular alignment and orientation processes give rise to fundamental quantum and classical phenomena like quantum revivals,Anderson localization,and rotational echoes,just to mention a few.We review recent progress on the visualization,coherent control,and applications of the rich dynamics of molecular rotational wave packets driven by laser pulses of various intensities,durations,and polarizations.In particular,we focus on the molecular unidirectional rotation and its visualization,the orientation of chiral molecules,and the three-dimensional orientation of asymmetric-top molecules.Rotational echoes are discussed as an example of nontrivial dynamics and detection of prepared molecular states.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21674096 and 21873082)
文摘The dynamics of two-dimensional rigid circles filled with chiral active particles are investigated by employing the overdamped Langevin dynamics simulations. Unidirectional rotation of rigid circles is observed, and the rotational angular velocity（ω） relies mainly on the length（l）, the number（nB）, and tilt angle（γ） of boards, and the angular velocity（ω）and area fraction（ρ） of chiral active particles. There are optimum values for these parameters at which the average angular velocity of circle reaches its maximum. The center-of-mass mean square displacement for circles drops by about two orders of magnitude for large angular velocity ω of chiral active particles with oscillations in the short-time regime. Our work demonstrates that nanofabricated objects with suitable designs immersed in a bath of chiral active particles can extract and rectify energy in a unidirectional motion.
基金Projects (50974035,51074047) supported by the National Natural Science Foundation of ChinaProject (20090407) supported by the Doctoral Fund of Ministry of Education,ChinaProject (200921007) supported by Liaoning Key Science and Technology,China
文摘In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion.Effects of various factors on bubble disintegration and dispersion were investigated.These factors were stirring mode,eccentricity and rotation speed,nozzle structure,nozzle immersion depth,and gas flow rate.Gas injection from a nozzle at the end of the impeller shaft and from an immersed lance was studied.Under eccentric stirring,a vortex was formed away from the shaft.Small bubbles were produced in the strong turbulence or high shear stress field near the rotating impeller and moved in the direction to the vortex keeping up with the macroscopic flow induced by the mechanical stirring.Thus small bubbles could disperse widely in the bath under eccentric stirring with unidirectional rotation.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0306303)the National Natural Science Foundation of China(Grants Nos.11834004,61690224,and 11761141004)+6 种基金the 111 Project of China(Grant No.B12024)the Projects from Shanghai Science and Technology Commission(No.19JC1412200)ISF-NSFC joint research program(Grant No.2520/17),CNRSthe ERDF Operational Program-Burgundythe EIPHI Graduate School(Contract No.ANR-17-EURE-0002)the Associate(CNRS&Weizmann)International ImagiNano LaboratoryIsrael Science Foundation(Grant No.746/15).
文摘Molecular alignment and orientation by laser fields has attracted significant attention in recent years,mostly due to new capabilities to manipulate the molecular spatial arrangement.Molecules can now be efficiently prepared for ionization,structural imaging,orbital tomography,and more,enabling,for example,shooting of dynamic molecular movies.Furthermore,molecular alignment and orientation processes give rise to fundamental quantum and classical phenomena like quantum revivals,Anderson localization,and rotational echoes,just to mention a few.We review recent progress on the visualization,coherent control,and applications of the rich dynamics of molecular rotational wave packets driven by laser pulses of various intensities,durations,and polarizations.In particular,we focus on the molecular unidirectional rotation and its visualization,the orientation of chiral molecules,and the three-dimensional orientation of asymmetric-top molecules.Rotational echoes are discussed as an example of nontrivial dynamics and detection of prepared molecular states.
