A Brownian microscopic heat engine with a particle hopping on a one-dimensional lattice driven by adiscrete and periodic temperature field in a periodic sawtooth potential is investigated.In order to clarify the under...A Brownian microscopic heat engine with a particle hopping on a one-dimensional lattice driven by adiscrete and periodic temperature field in a periodic sawtooth potential is investigated.In order to clarify the underlyingphysical pictures of the heat engine, the heat flow via the potential energy and the kinetic energy of the particles areconsidered simultaneously.Based on describing the jumps among the three states, the expressions of the efficiency andpower output of the heat engine are derived analytically.The general performance characteristic curves are plotted bynumerical calculation.It is found that the power output-efficiency curve is a loop-shaped one, which is similar to onefor a real irreversible heat engine.The influence of the ratio of the temperature of the hot and cold reservoirs and thesawtooth potential on the maximum efficiency and power output is analyzed for some given parameters.When the heatflows via the kinetic energy is neglected, the power output-efficiency curve is an open-shaped one, which is similar to onefor an endroeversible heat engine.展开更多
F_1-ATPase, a part of ATP synthase, can synthesize and hydrolyze ATP moleculars in which the centralγ-subunit rotates inside the α_3β_3 cylinder.A stochastic four-state mechanochemical coupling model of F_1-ATPase ...F_1-ATPase, a part of ATP synthase, can synthesize and hydrolyze ATP moleculars in which the centralγ-subunit rotates inside the α_3β_3 cylinder.A stochastic four-state mechanochemical coupling model of F_1-ATPase isstudied with the aid of the master equation.In this model, the ATP hydrolysis and synthesis are dependent on ATP,ADP, and Pi concentrations.The effects of ATP concentration, ADP concentration, and the external torque on theoccupation probability of binding-state, the rotation rate and the diffusion coefficient of F_1-ATPase are investigated.Moreover, the results from this model are compared with experiments.The mechanochemical mechanism F_1-ATPase isqualitatively explained by the model.展开更多
We investigate the evolution dynamics of a two-level atom system interacting with the massless scalar field in a Cylindrical spacetime. We find that both the energy shifts of ground state and excited state can be sepa...We investigate the evolution dynamics of a two-level atom system interacting with the massless scalar field in a Cylindrical spacetime. We find that both the energy shifts of ground state and excited state can be separated into two parts due to the vacuum fluctuations. One is the corresponding energy shift for a rest atom in four-dimensional Minkowski space without spatial compactification, the other is just the modification of the spatial compactified periodic length. It will reveal that the influence of the presence of one spatial compactified dimension can not be neglected in Lamb shift as the relative energy level shift of an ~tom.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.10765004
文摘A Brownian microscopic heat engine with a particle hopping on a one-dimensional lattice driven by adiscrete and periodic temperature field in a periodic sawtooth potential is investigated.In order to clarify the underlyingphysical pictures of the heat engine, the heat flow via the potential energy and the kinetic energy of the particles areconsidered simultaneously.Based on describing the jumps among the three states, the expressions of the efficiency andpower output of the heat engine are derived analytically.The general performance characteristic curves are plotted bynumerical calculation.It is found that the power output-efficiency curve is a loop-shaped one, which is similar to onefor a real irreversible heat engine.The influence of the ratio of the temperature of the hot and cold reservoirs and thesawtooth potential on the maximum efficiency and power output is analyzed for some given parameters.When the heatflows via the kinetic energy is neglected, the power output-efficiency curve is an open-shaped one, which is similar to onefor an endroeversible heat engine.
基金Supported by the National Natural Science Foundation of China under Grant No.10847118the National Natural Science Foundation of the City of Tianjin under Grant No.08JCYBJC00900 the Science Research Program of Education office of Hebei Province under Grant No.2008427
文摘F_1-ATPase, a part of ATP synthase, can synthesize and hydrolyze ATP moleculars in which the centralγ-subunit rotates inside the α_3β_3 cylinder.A stochastic four-state mechanochemical coupling model of F_1-ATPase isstudied with the aid of the master equation.In this model, the ATP hydrolysis and synthesis are dependent on ATP,ADP, and Pi concentrations.The effects of ATP concentration, ADP concentration, and the external torque on theoccupation probability of binding-state, the rotation rate and the diffusion coefficient of F_1-ATPase are investigated.Moreover, the results from this model are compared with experiments.The mechanochemical mechanism F_1-ATPase isqualitatively explained by the model.
基金Supported by the National Natural Science Foundation of China under Grant No.11005038the Program for Changjiang Scholars and Innovative Research Team in University under Grant No.IRT0964the Hunan Provincial Natural Science Foundation of China under Grant No.11JJ7001
文摘We investigate the evolution dynamics of a two-level atom system interacting with the massless scalar field in a Cylindrical spacetime. We find that both the energy shifts of ground state and excited state can be separated into two parts due to the vacuum fluctuations. One is the corresponding energy shift for a rest atom in four-dimensional Minkowski space without spatial compactification, the other is just the modification of the spatial compactified periodic length. It will reveal that the influence of the presence of one spatial compactified dimension can not be neglected in Lamb shift as the relative energy level shift of an ~tom.
