The dynamics of the myosin molecular motor as it binds to actin filaments during muscle contraction are still not clearly understood.In this paper,we focus on the coupling mechanism of multi-force interactions in the ...The dynamics of the myosin molecular motor as it binds to actin filaments during muscle contraction are still not clearly understood.In this paper,we focus on the coupling mechanism of multi-force interactions in the myosin molecule during its interaction with actin.These forces include the electrostatic force,the van der Waals force and the Casimir force in molecular dynamic simulations of the molecules in solvent with thermal fluctuations.Based on the Hamaker approach,van der Waals and Casimir potentials and forces are calculated between myosin and actin.We have developed a Monte Carlo method to simulate the dynamic activity of the molecular motor.We have shown that because of the retardation effect,the van der Waals force falls into the Casimir force when the distance between the surfaces is larger than 3 nm.When the distance is smaller than 3 nm,the electrostatic force and the van der Waals force increase until the myosin becomes attached to the actin.Over the distances studied in the present work,the electrostatic force dominates the attractive interactions.Our calculations are in good agreement with recently reported experimental results.展开更多
We modeled a one-dimensional actuator including the Casimir and electrostatic forces perturbed by an external force with fractional damping. The movable electrode was assumed to oscillate by an anharmonic elastic forc...We modeled a one-dimensional actuator including the Casimir and electrostatic forces perturbed by an external force with fractional damping. The movable electrode was assumed to oscillate by an anharmonic elastic force originated from Murrell- Mottram or Lippincott potential. The nonlinear equations have been solved via the Adomian decomposition method. The behavior of the displacement of the electrode from equilibrium position, its velocity and acceleration were described versus time. Also, the changes of the displacement have been investigated according to the frequency of the external force and the voltage of the electrostatic force. The convergence of the Adomian method and the effect of the orders of expansion on the displacement versus time, frequency, and voltage were discussed. The pull-in parameter was obtained and compared with the other models in the literature. This parameter was described versus the equilibrium position and anharmonicity constant.展开更多
The calculations of quantum mechanical descriptors of 79 heterogeneous phenol compounds were presented at the HF/6-31G＊ and B3LYP/6-31G＊ levels of theory.Quantitative structure-activity relationship（QSAR） models o...The calculations of quantum mechanical descriptors of 79 heterogeneous phenol compounds were presented at the HF/6-31G＊ and B3LYP/6-31G＊ levels of theory.Quantitative structure-activity relationship（QSAR） models of the growth inhibition activity（pIGC50） of 79 heterogeneous phenols were established using some of the following calculated quantum mechanical descriptors：the zero point energy（ZPE）,the front-line orbital energy（EHOMO,ELUMO）,the differences between HOMO and LUMO energies（ΔE）,and the molecular dipole moment（μ）.The QSAR models obtained by employing multiple linear regression techniques are aimed at correlating the structures to their experimental pIGC50.The most significant is a one-parameter linear equation with the correlation coefficient R2 values to be 0.855（HF） and 0.844（B3LYP）.The results display that the zero point energy as a special quantum-chemical descriptor in the QSAR equations indicates the existence of Casimir force in the interaction between the molecules of compounds and biological receptor（cells）.The physical mechanism of structure-activity of the molecules at a deeper level would have a new understanding.展开更多
Mechanical stability and sticking are the troublesome problems in microfabrication andoperation processes when separations of components in MEMS are in the sub-micrometer regime.Some mechanical effects including quant...Mechanical stability and sticking are the troublesome problems in microfabrication andoperation processes when separations of components in MEMS are in the sub-micrometer regime.Some mechanical effects including quantum mechanical effect should be taken into account forsolving the problems. The influence of capillary forces on sticking of a surface micromachined mi-crocantilever in ambient environment or the rinse liquid and the influence of quantum mechanicaleffect such as the Casimir effect on sticking and stability of a micro membrane strip cavity structurein vacuum were investigated. A factual rough model theory about sticking problem under theCasimir effect was suggested for the first time. The study on the design of anti-sticking structuresunder different forces shows that sticking and stability of microcantilevers and micro membranestrip cavities has something to do with Young’s modulus of materials, surface properties, length ofstructures, thickness of structures and separation between the fixed surface and the deflectingcomponent. But, it is independent of width of structures. The map of the size design of anti-stickingstructures was put forward for the first time. This also provides a way to design a MEMS structurewith high resistance to collapse.展开更多
The frequency spectrum of the cosmical Zero Point Energy (ZPE) and its total density are so far unknown in their details. In the present complementary investigation, a revised theory forms the basis for studies of thi...The frequency spectrum of the cosmical Zero Point Energy (ZPE) and its total density are so far unknown in their details. In the present complementary investigation, a revised theory forms the basis for studies of this concept in two respects. It first applies to the observable universe considered as an entity, as well as to included subregions such as the galaxies with supermassive black holes. Second, experiments are proposed on the maximum Casimir force arising between two metal plates of different materials and with a vanishing air gap in their spacing. This serves the purpose of making an indirect determination of the ZPE energy density in the laboratory, i.e. at the Earth’s orbit. The ZPE energy density is interpreted as dark matter density and its pressure gradient as dark energy force density.展开更多
The pull-in instability of a cantilever nano-actuator model incorporating the effects of the surface, the fringing field, and the Casimir attraction force is investigated. A new quartic polynomial is proposed as the s...The pull-in instability of a cantilever nano-actuator model incorporating the effects of the surface, the fringing field, and the Casimir attraction force is investigated. A new quartic polynomial is proposed as the shape function of the beam during the deflection, satisfying all of the four boundary values. The Gaussian quadrature rule is used to treat the involved integrations, and the design parameters are preserved in the evaluated formulas. The analytic expressions are derived for the tip deflection and pull-in parameters of the cantilever beam. The micro-electromechanical system （MEMS） cantilever actuators and freestanding nano-actuators are considered as two special cases. It is proved that the proposed method is convenient for the analyses of the effects of the surface, the Casimir force, and the fringing field on the pull-in parameters.展开更多
Both the size of the components and the separation between them in some microelectromechanical systems (MEMS) are already in the sub-micrometer regime, where quantum mechanical effects such as the Casimir effect will...Both the size of the components and the separation between them in some microelectromechanical systems (MEMS) are already in the sub-micrometer regime, where quantum mechanical effects such as the Casimir effect will need to be considered. This paper theoretically analyzes the roughness, electrical conductivity, and temperature corrections due to the Casimir force between two parallel polysilicon plates. The theoretical results show that the combined effects of roughness, conductivity and temperature cause a maximum relative error of the Casimir force per unit area of 26.2% between parallel polysilicon plates separated by 1 μm. Therefore, the surface roughness and finite conductivity corrections should be taken into account when calculating precise Casimir forces with separations on the order of 1 μm.展开更多
基金supported by the National Natural Science Foundation of China (60643002,61075101)the Research Fund of State Key Laboratory of MSV, China (MSV-2010-01)+2 种基金the National High-Tech Research and Development Program of China (2006AA04Z240)the Shanghai Dawn Program (07SG14)the Medical and Technology Intercrossing Research Foundation of Shanghai Jiao Tong University (YG2010ZD101)
文摘The dynamics of the myosin molecular motor as it binds to actin filaments during muscle contraction are still not clearly understood.In this paper,we focus on the coupling mechanism of multi-force interactions in the myosin molecule during its interaction with actin.These forces include the electrostatic force,the van der Waals force and the Casimir force in molecular dynamic simulations of the molecules in solvent with thermal fluctuations.Based on the Hamaker approach,van der Waals and Casimir potentials and forces are calculated between myosin and actin.We have developed a Monte Carlo method to simulate the dynamic activity of the molecular motor.We have shown that because of the retardation effect,the van der Waals force falls into the Casimir force when the distance between the surfaces is larger than 3 nm.When the distance is smaller than 3 nm,the electrostatic force and the van der Waals force increase until the myosin becomes attached to the actin.Over the distances studied in the present work,the electrostatic force dominates the attractive interactions.Our calculations are in good agreement with recently reported experimental results.
文摘We modeled a one-dimensional actuator including the Casimir and electrostatic forces perturbed by an external force with fractional damping. The movable electrode was assumed to oscillate by an anharmonic elastic force originated from Murrell- Mottram or Lippincott potential. The nonlinear equations have been solved via the Adomian decomposition method. The behavior of the displacement of the electrode from equilibrium position, its velocity and acceleration were described versus time. Also, the changes of the displacement have been investigated according to the frequency of the external force and the voltage of the electrostatic force. The convergence of the Adomian method and the effect of the orders of expansion on the displacement versus time, frequency, and voltage were discussed. The pull-in parameter was obtained and compared with the other models in the literature. This parameter was described versus the equilibrium position and anharmonicity constant.
文摘The calculations of quantum mechanical descriptors of 79 heterogeneous phenol compounds were presented at the HF/6-31G＊ and B3LYP/6-31G＊ levels of theory.Quantitative structure-activity relationship（QSAR） models of the growth inhibition activity（pIGC50） of 79 heterogeneous phenols were established using some of the following calculated quantum mechanical descriptors：the zero point energy（ZPE）,the front-line orbital energy（EHOMO,ELUMO）,the differences between HOMO and LUMO energies（ΔE）,and the molecular dipole moment（μ）.The QSAR models obtained by employing multiple linear regression techniques are aimed at correlating the structures to their experimental pIGC50.The most significant is a one-parameter linear equation with the correlation coefficient R2 values to be 0.855（HF） and 0.844（B3LYP）.The results display that the zero point energy as a special quantum-chemical descriptor in the QSAR equations indicates the existence of Casimir force in the interaction between the molecules of compounds and biological receptor（cells）.The physical mechanism of structure-activity of the molecules at a deeper level would have a new understanding.
文摘Mechanical stability and sticking are the troublesome problems in microfabrication andoperation processes when separations of components in MEMS are in the sub-micrometer regime.Some mechanical effects including quantum mechanical effect should be taken into account forsolving the problems. The influence of capillary forces on sticking of a surface micromachined mi-crocantilever in ambient environment or the rinse liquid and the influence of quantum mechanicaleffect such as the Casimir effect on sticking and stability of a micro membrane strip cavity structurein vacuum were investigated. A factual rough model theory about sticking problem under theCasimir effect was suggested for the first time. The study on the design of anti-sticking structuresunder different forces shows that sticking and stability of microcantilevers and micro membranestrip cavities has something to do with Young’s modulus of materials, surface properties, length ofstructures, thickness of structures and separation between the fixed surface and the deflectingcomponent. But, it is independent of width of structures. The map of the size design of anti-stickingstructures was put forward for the first time. This also provides a way to design a MEMS structurewith high resistance to collapse.
文摘The frequency spectrum of the cosmical Zero Point Energy (ZPE) and its total density are so far unknown in their details. In the present complementary investigation, a revised theory forms the basis for studies of this concept in two respects. It first applies to the observable universe considered as an entity, as well as to included subregions such as the galaxies with supermassive black holes. Second, experiments are proposed on the maximum Casimir force arising between two metal plates of different materials and with a vanishing air gap in their spacing. This serves the purpose of making an indirect determination of the ZPE energy density in the laboratory, i.e. at the Earth’s orbit. The ZPE energy density is interpreted as dark matter density and its pressure gradient as dark energy force density.
基金supported by the National Natural Science Foundation of China(No.11201308)the Natural Science Foundation of Shanghai(No.14ZR1440800)the Innovation Program of the Shanghai Municipal Education Commission(No.14ZZ161)
文摘The pull-in instability of a cantilever nano-actuator model incorporating the effects of the surface, the fringing field, and the Casimir attraction force is investigated. A new quartic polynomial is proposed as the shape function of the beam during the deflection, satisfying all of the four boundary values. The Gaussian quadrature rule is used to treat the involved integrations, and the design parameters are preserved in the evaluated formulas. The analytic expressions are derived for the tip deflection and pull-in parameters of the cantilever beam. The micro-electromechanical system （MEMS） cantilever actuators and freestanding nano-actuators are considered as two special cases. It is proved that the proposed method is convenient for the analyses of the effects of the surface, the Casimir force, and the fringing field on the pull-in parameters.
基金Supported by the Doctoral Science Foundation of China(No. 2 0 0 0 0 0 0 338)
文摘Both the size of the components and the separation between them in some microelectromechanical systems (MEMS) are already in the sub-micrometer regime, where quantum mechanical effects such as the Casimir effect will need to be considered. This paper theoretically analyzes the roughness, electrical conductivity, and temperature corrections due to the Casimir force between two parallel polysilicon plates. The theoretical results show that the combined effects of roughness, conductivity and temperature cause a maximum relative error of the Casimir force per unit area of 26.2% between parallel polysilicon plates separated by 1 μm. Therefore, the surface roughness and finite conductivity corrections should be taken into account when calculating precise Casimir forces with separations on the order of 1 μm.
