scholarly journals Statistical mechanical analysis of the electromechanical coupling in an electrically-responsive polymer chain

Soft Matter ◽  
2020 ◽  
Vol 16 (27) ◽  
pp. 6265-6284
Author(s):  
Matthew Grasinger ◽  
Kaushik Dayal
Keyword(s):  
Statistical Mechanics ◽  
Potential Application ◽  
Electromechanical Coupling ◽  
Mechanical Analysis ◽  
Soft Sensors ◽  
Sensors And Actuators ◽  
Responsive Polymer ◽  
Biomedical Technologies ◽  
Statistical Mechanical ◽  
Couple Deformation

Polymers that couple deformation and electrostatics have potential application in soft sensors and actuators for robotics and biomedical technologies. This paper applies statistical mechanics to study their coupled electromechanical response.

Statistical mechanics of deuterium exchange reactions : relationships between equilibrium constants and enthalpies of reaction

1982 ◽  
Vol 35 (2) ◽  
pp. 237 ◽  
Author(s):  
DV Fenby ◽  
GL Bertrand
Keyword(s):  
Statistical Mechanics ◽  
Equilibrium Constant ◽  
Isotopic Exchange ◽  
Equilibrium Constants ◽  
Mechanical Analysis ◽  
Deuterium Exchange ◽  
Exchange Reactions ◽  
Statistical Mechanical

Bertrand and Burchfield proposed that the equilibrium constants K and the (standard) enthalpies ΔH of isotopic exchange reactions are related by the equation K = Kstatexp(-ΔH/RT) in which Kstat is the statistical (random) equilibrium constant. The application of this equation to deuterium exchange reactions for which experimental K and ΔH values are available suggests that it is a good approximation at 298 K. In this paper we present a statistical mechanical analysis to account for the success of the equation and to point out its limitations.

scholarly journals Combined piezoelectric and flexoelectric effects in resonant dynamics of nanocantilevers

2018 ◽  
Vol 29 (20) ◽  
pp. 3949-3959 ◽  
Author(s):  
Adriane G Moura ◽  
Alper Erturk
Keyword(s):  
Barium Titanate ◽  
Frequency Response ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Analytical Framework ◽  
Electromechanical Coupling Coefficient ◽  
Sensors And Actuators ◽  
Energy Harvesters ◽  
Size Dependent ◽  
Resonant Dynamics

We establish and analyze an analytical framework by accounting for both the piezoelectric and flexoelectric effects in bimorph cantilevers. The focus is placed on the development of governing electroelastodynamic piezoelectric–flexoelectric equations for the problems of resonant energy harvesting, sensing, and actuation. The coupled governing equations are analyzed to obtain closed-form frequency response expressions via modal analysis. The combined piezoelectric–flexoelectric coupling coefficient expression is identified and its size dependence is explored. Specifically, a typical atomistic value of the flexoelectric constant for barium titanate is employed in the model simulations along with its piezoelectric constant from the existing literature. It is shown that the effective electromechanical coupling of a piezoelectric material, such as barium titanate, is significantly enhanced for thickness levels below 100 nm. The electromechanical coupling coefficient of a barium titanate bimorph cantilever increases from the bulk piezoelectric value of 0.065 to the combined piezoelectric–flexoelectric value exceeding 0.3 toward nanometer thickness level. Electromechanical frequency response functions for resonant power generation and dynamic actuation also capture the size-dependent enhancement of the electromechanical coupling. The analytical framework given here can be used for parameter identification and design of nanoscale cantilevers that can be used as energy harvesters, sensors, and actuators.

Linear Response Theory

2006 ◽  
Author(s):  
Abraham Nitzan
Keyword(s):  
Statistical Mechanics ◽  
Linear Response ◽  
Ad Hoc ◽  
Linear Response Theory ◽  
Perturbative Expansion ◽  
General Nature ◽  
Response Theory ◽  
Equilibrium Statistical Mechanics ◽  
Standard Application ◽  
Statistical Mechanical

Equilibrium statistical mechanics is a first principle theory whose fundamental statements are general and independent of the details associated with individual systems. No such general theory exists for nonequilibrium systems and for this reason we often have to resort to ad hoc descriptions, often of phenomenological nature, as demonstrated by several examples in Chapters 7 and 8. Equilibrium statistical mechanics can however be extended to describe small deviations from equilibrium in a way that preserves its general nature. The result is Linear Response Theory, a statistical mechanical perturbative expansion about equilibrium. In a standard application we start with a system in thermal equilibrium and attempt to quantify its response to an applied (static- or time-dependent) perturbation. The latter is assumed small, allowing us to keep only linear terms in a perturbative expansion. This leads to a linear relationship between this perturbation and the resulting response. Let us make these statements more quantitative. Consider a system characterized by the Hamiltonian Ĥ0.

scholarly journals The Dam1 ring binds to the E-hook of tubulin and diffuses along the microtubule

2011 ◽  
Vol 22 (4) ◽  
pp. 457-466 ◽  
Author(s):  
Vincent H. Ramey ◽  
Hong-Wei Wang ◽  
Yuko Nakajima ◽  
Amanda Wong ◽  
Jian Liu ◽  
...  
Keyword(s):  
Energy Coupling ◽  
Mechanical Analysis ◽  
Microtubule Depolymerization ◽  
Ring Model ◽  
Complex Interactions ◽  
Functional Aspects ◽  
Significant Step ◽  
Statistical Mechanical ◽  
Biased Diffusion ◽  
Dam1 Complex

There has been much effort in recent years aimed at understanding the molecular mechanism by which the Dam1 kinetochore complex is able to couple microtubule depolymerization to poleward movement. Both a biased diffusion and a forced walk model have been proposed, and several key functional aspects of Dam1-microtubule binding are disputed. Here, we investigate the elements involved in tubulin-Dam1 complex interactions and directly visualize Dam1 rings on microtubules in order to infer their dynamic behavior on the microtubule lattice and its likely relevance at the kinetochore. We find that the Dam1 complex has a preference for native tubulin over tubulin that is lacking its acidic C-terminal tail. Statistical mechanical analysis of images of Dam1 rings on microtubules, applied to both the distance between rings and the tilt angle of the rings with respect to the microtubule axis, supports a diffusive ring model. We also present a cryo-EM reconstruction of the Dam1 ring, likely the relevant assembly form of the complex for energy coupling during microtubule depolymerization in budding yeast. The present studies constitute a significant step forward by linking structural and biochemical observations toward a comprehensive understanding of the Dam1 complex.

ON THE EXTENSIVITY OF THE ENTROPY Sq FOR N ≤ 3 SPECIALLY CORRELATED BINARY SUBSYSTEMS

2006 ◽  
Vol 16 (06) ◽  
pp. 1727-1738 ◽  
Author(s):  
YUZURU SATO ◽  
CONSTANTINO TSALLIS
Keyword(s):  
Statistical Mechanics ◽  
Stationary States ◽  
Nonextensive Statistical Mechanics ◽  
Entropy Formula ◽  
Gibbs Entropy ◽  
Statistical Mechanical

Many natural and artificial systems whose range of interaction is long enough are known to exhibit (quasi)stationary states that defy the standard, Boltzmann–Gibbs statistical mechanical prescriptions. For handling such anomalous systems (or at least some classes of them), nonextensive statistical mechanics has been proposed based on the entropy [Formula: see text], with [Formula: see text] (Boltzmann–Gibbs entropy). Special collective correlations can be mathematically constructed such that the strictly additive entropy is now Sq for an adequate value of q ≠ 1, whereas Boltzmann–Gibbs entropy is nonadditive. Since important classes of systems exist for which the strict additivity of Boltzmann–Gibbs entropy is replaced by asymptotic additivity (i.e. extensivity), a variety of classes are expected to exist for which the strict additivity of Sq (q ≠ 1) is similarly replaced by asymptotic additivity (i.e. extensivity). All probabilistically well defined systems whose adequate entropy is S1 are called extensive (or normal). They correspond to a number W eff of effectively occupied states which grows exponentially with the number N of elements (or subsystems). Those whose adequate entropy is Sq (q ≠ 1) are currently called nonextensive (or anomalous). They correspond to W eff growing like a power of N. To illustrate this scenario, recently addressed [Tsallis, 2004] we provide in this paper details about systems composed by N = 2, 3 two-state subsystems.

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