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entrainment mechanism of the cyanobacterial circadian clock induced by oxidized quinone

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Chinese Physics B 2020年第9期29卷 589-596页

作者：李莹张广鹍宋自根 College of Information Technology Shanghai Ocean UniversityShanghai 201306China

The circadian clock is a self-sustained biological oscillator which can be entrained by environmental signals.The cyanobacteria circadian clock is the simplest one,which is composed of the proteins KaiA,KaiB and KaiC.The phosphorylation/dephosphorylation state of KaiC exhibits a circadian oscillator.KaiA and KaiB activate KaiC phosphorylation and dephosphorylation respectively.CikA competing with KaiA for the same binding site on KaiB affects the phosphorylation state of KaiC.Quinone is a signaling molecule for entraining the cyanobacterial circadian clock which is oxidized at the onset of darkness and reduced at the onset of light,reflecting the environmental light-dark cycle.KaiA and CikA can sense external signals by detecting the oxidation state of quinone.However,the entrainment mechanism is far from clear.We develop an enhanced mathematical model including oxidized quinone sensed by KaiA and CikA,with which we present a detailed study on the entrainment of the cyanobacteria circadian clock induced by quinone signals.We find that KaiA and CikA sensing oxidized quinone pulse are related to phase advance and delay,respectively.The time of oxidized quinone pulse addition plays a key role in the phase shifts.The combination of KaiA and CikA is beneficial to the generation of entrainment,and the increase of signal intensity reduces the entrainment phase.This study provides a theoretical reference for biological research and helps us understand the dynamical mechanisms of cyanobacteria circadian clock.

关键词： mathematical model entrainment cyanobacterial circadian clock phase response curve

entrainment range affected by the heterogeneity in the amplitude relaxation rate of suprachiasmatic nucleus neurons

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Chinese Physics B 2019年第1期28卷 663-668页

作者：顾长贵王萍杨会杰 Business School University of Shanghai for Science and Technology

Adaption of circadian rhythms in behavioral and physiological activities to the external light–dark cycle is achieved through the main clock, i.e., the suprachiasmatic nucleus(SCN) of the brain in mammals. It has been found that the SCN neurons differ in the amplitude relaxation rate, which represents the rigidity of the neurons to the external amplitude disturbance. Thus far, the appearance of that difference has not been explained. In the present study, an alternative explanation based on the Poincare′ model is given which takes into account the effect of the difference in the entrainment range of the SCN. Both our simulation results and theoretical analyses show that the largest entrainment range is obtained with suitable difference in the case that only a part of SCN neurons are sensitive to the light information. Our findings may give an alternative explanation for the appearance of that difference(heterogeneity) and shed light on the effects of the heterogeneity in the neuronal properties on the collective behaviors of the SCN neurons.

关键词： amplitude relaxation rate entrainment range heterogeneity

entrainment effects and the dynamical evolution of debris avalanche/flow on substrate materials

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Journal of Mountain Science 2019年第8期16卷 1760-1773页

作者： HUO Miao YANG Xing-guo ZHOU Hong-wei LIANG yu-feng ZHOU Jia-wen State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China College of Water Resource and Hydropower Sichuan UniversityChengdu 610065China

A pair of flumes with variable inclinations were employed to investigate the entrainment mechanics and dynamical evolution of a debris avalanche/flow. A fixed quantity of solid and water mixture was released from a constant elevation and accelerated along a higher chute to impact substrate materials with different water contents and particle size distributions in the lower chute. Two high-speed cameras, pore and earth pressure detecting devices, were placed in the substrate materials where severe scouring occurs in order to collect multiple measurements of dynamical and mechanical parameters. The entrainment dynamics were verified by geometrical analysis and quasi-static simulation. The results show that wet and fine materials that are placed in the lower chute with steeper slopes are easily entrained during debris flow initiation, the pattern of which can be described by Coulomb friction and the Mohr-Coulomb law. Elaborate measurements of dynamical parameters enable the results of an elementary computational framework to predict the time-dependent scouring depth ht, which provides insight into rapidly determining debris flow propagation. Finally, the post-entrainment dynamics were studied. The results indicate that the propagation and the amplification of debris flows along erodible beds are dominated by the velocity and the solid volume fraction of the mixed substrate, and the coarse particle group of the substrate is a key feature affected by momentum changes.

关键词： Debris avalanche Debris flow initiation entrainment mechanism Flume experiment Dynamical evolution

Air entrainment and detrainment downstream a chute aerator

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Journal of Hydrodynamics 2019年第1期31卷 76-82页

作者： Rui-di Bai Fa-xing Zhang Wei Wang Shan-jun Liu State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

The chute aerators separate the flow from the chute bottom,and the air can enter into the flow through the lower surface.In this study,the air concentration and the pressure along the chute bottom are investigated systematically by a series of model tests with the upper aeration effect being eliminated.The chute downstream the aerator is partitioned into four zones:the cavity zone,the impact zone,the equilibrium zone,and the far zone.It is found that a large amount of air entrained in the cavity zone is only partially entrained into the flow finally.Furthermore,the lower air discharge is decreased sharply in the impact zone,and the detrainment disappearsonthe section of x= Lm.In the equilibrium zone,the lower air discharge is kept unchanged.With the in crease of the flow Froude number and withthe other parameters kept unchanged,it is found that the dimensionless value of K has a significant increase.Meanwhile,a formula to calculate K is proposed,with results in good agreement with the model and prototype data.

关键词： Chute aerator air concentration entrainment detrainment

EXPERIMENTAL STUDY ON THE VORTEX FORMATION AND entrainment CHARACTERISTICS FOR A ROUND TRANSVERSE JET IN SHALLOW WATER

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Journal of Hydrodynamics 2009年第3期21卷 386-393页

作者： FAN Jing-yu ZHANG Yan WANG Dao-zeng Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Key Laboratory of Advanced Display and System Applications Ministry of Education and SMIT Center School of Mechatronics Engineering and Automation Shanghai University Shanghai 200072 China

The vortex formation and entrainment characteristics for a round transverse jet in shallow water were experimentally investigated by means of a combination of LIF flow visualization and PIV measurement. A scarf vortex wrapped around the main body of the jet is formed in the near-wall region due to the interaction between the resulting wall jet and sufficiently shallow crossflow, with some more or less unsteady flow properties and with spreading ranges as functions of both the velocity ratio and the water depth within the near field. The entrainment of the ambient crossflow fluid into the jet main body is closely associated with the time-evolving features of the shear layer between the jet and surrounding fluid as well as the induced vortical structures near the wall. In the case of slight impingement upon the wall, the interaction between the jet shear layer and the weak, unstable scarf vortex gives rise to an appreciable local entrainment enhancement, confined in the near-wall region in the vicinity of the stagnation point. While in the case of intense impingement upon the wall, the well-organized and stable scarf vortex gives rise to a greatly enhanced entrainment and a greatly increased lateral spreading rate nearly throughout the overall near field as compared to the conventional wall jet. In addition, the entrainment of the ambient crossflow fluid by the scarf vortex in this case occurs largely on the surface of the unique spiral roller structure by itself due to the presence of smaller and unorganized eddies, and accordingly the scarf vortex is likely to keep its spiral roller structure steadily to a relatively great downstream distance within the near field.

关键词： transverse jet shallow water vortex formation entrainment PIV measurement

Simulation study on factors influencing the entrainment behavior of liquid steel as bubbles pass through the steel/slag interface

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International Journal of Minerals,Metallurgy and Materials 2016年第5期23卷 511-519页

作者： Xiang Li Yan-ping Bao Min Wang Lu Lin State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

In this study, a water/silicone oil interface was used to simulate the steel/slag interface in a converter. A high-speed camera was used to record the entrainment process of droplets when air bubbles were passed through the water/silicone oil interface. Motion parameters of the bubbles and droplets were obtained using particle kinematic analysis software, and the entrainment rate of the droplets was calculated. It was found that the entrainment rate decreased from 29.5% to 0 when the viscosity of the silicone oil was increased from 60 mPa.s to 820 mPa.s in the case of bubbles with a 5 mm equivalent diameter passing through the water/silicone oil interface. The results indicate that in- creasing the viscosity of the silicone oil is conducive to reducing the entrainment rate. The entrainment rate increased from 0 to 136.3% in the case of silicone oil with a viscosity of 60 mPa.s when the equivalent diameter of the bubbles was increased from 3 mm to 7 ram. We there- fore conclude that small bubbles are also conductive to reducing the entrainment rate. The force analysis results for the water colmnn indicate that the entrainment rate of droplets is affected by the velocity of the bubble passing through the water/silicone oil interface and that the en- trainment rate decreases with the bubble velocity.

关键词： steelmaking bubbles interfaces entrainment influencing factors simulation studies

WALL PRESSURE FLUCTUATIONS OF TURBULENT FLOW OVER BACKWARD-FACING STEP WITH AND WITHOUT entrainment: MICROPHONE ARRAY MEASUREMENT

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Journal of Hydrodynamics 2006年第4期18卷 393-396页

作者： KE Feng LIU Ying-zheng WANG Wei-zhe CHEN Han-ping School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China

Wall pressure fluctuations in turbulent boundary layer flow over backward-facing step with and without entrainment were investigated. Digital array pressure sensors and multi-arrayed microphones were employed to acquire the time-averaged static pressure and fluctuating pressure, respectively. The differences of two flows were scrutinized in terms of static pressure characteristics, pressure fluctuations, cross-correlation and coherence of wall pressure. Introduction of the entrainment increased scale of large-scale vortical structure and reduced its convection velocity. However, shedding frequency of large-scale vortical structures was found to be the same for both flows.

关键词： backward-facing step turbulent boundary layer entrainment wall pressure fluctuations Microphone Array

Ratio Between Sensitive Strength to Light Information and Coupling Strength Affects entrainment Range of Suprachiasmatic Nucleus

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Communications in Theoretical Physics 2018年第12期69卷 771-776页

作者：顾长贵杨会杰王曼 Business School University of Shanghai for Science and Technology School of Foreign Languages and Literature Shandong University

The suprachiasmatic nucleus(SCN), an endogenous clock in the brain of the mammals, regulates the physiological and behavioral activities according to the natural 24 h light-darkness cycle. Animals can also entrain themselves to non 24 h light-darkness cycles. The range of the periods which the animal can entrain to is called entrainment range. Previous studies have found that the entrainment range depends on the coupling strength and the sensitive strength to the light for the SCN neurons. However, the effect of the interplay between these two strengths on the entrainment range has not been examined. In the present study, we examine the effect of the ratio of the sensitive strength to the coupling strength on the entrainment range. We find that there is a parabolic-like relationship between the entrainment range and the ratio, and the largest entrainment range is obtained with a suitable ratio. Interestingly,the value of this suitable ratio is related to the comparison in the intrinsic amplitudes between the light information sensitive neurons and the light information insensitive neurons. Our finding will shed light on the interplay between the sensitive strength to the light information and the coupling strength, and the understanding for the diversity of the entrainment range among various species.

关键词： biological rhythms neuronal network nonlinear dynamics entrainment range

POTENTIAL ENERGY MODEL FOR TURBULENT entrainment ACROSS DENSITY INTERFACE IN A LINEARLY STRATIFIED FLUID

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Science China Mathematics 1992年第12期35卷 1475-1485页

作者：鄂学全王薇 Institute of Mechanics Academia Sinica Beijing 100080 PRC

A potontial energy medel is developed for turbulent entrainment in the absence of mean shear in a linearly stratified fluid. The relation between the entrainment distanee D and the time t and the relation between dimensionless entrainment rate E and the local Richardson number are obtained. An experiment is made for examination. The experimental results are in good agreement with the medel, in which the dimensionless entrainment distance D is given by where A_i is the proportional coefficient, S is the dimensionless stroke, is thc dimensionless frequency of the grid oscillation, the dimensionless time.

关键词： turbulent entrainment linearly stratified fluid.