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Artificial Molecular Machines.

Erbas-Cakmak S, Leigh DA, McTernan CT, Nussbaumer AL - Chem. Rev. (2015)

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom.

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bonded molecules and on catenanes and rotaxanes in which switching of other protic solvents... This effect (listed in descending binding ability) stations on the thread, macrocycle In these systems, fast-responding reporters are preferred... practical applications by utilizing molecular scale changes to create macroscopic effects... The thread of these rotaxanes included an anthracene fluorophore similar application in synthetic polymers often furnishes a useful result... of Brownian motion can be exploited to great effect in the synthesis every aspect of functional molecule and materials design... An improved robotics” in which ratcheted motions of molecular components

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Maxwell’sdemons. (a) A “temperature demon”sorts particles according to velocity, generating a temperature gradient.(b) A “pressure demon” sorts particles according totheir direction of movement, generating a pressure gradient.37
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fig1: Maxwell’sdemons. (a) A “temperature demon”sorts particles according to velocity, generating a temperature gradient.(b) A “pressure demon” sorts particles according totheir direction of movement, generating a pressure gradient.37

Mentions: The Second Law of Thermodynamics states that the entropy ofan isolated system tends to increase, leading to an equilibrium distributionwith maximum entropy. To achieve any distribution other than the thermodynamicequilibrium, work must be done on the system. Various thought experimentshave been proposed that attempt to violate this premise and drivea system away from equilibrium without expending work. In the Maxwell’sDemon thought experiment, particles in a container are sorted by an“intelligent gatekeeper”, the “demon”(Figure 1).32 Gas particles are distributed in a containerpartitioned into two sections in an isolated system. The spontaneousformation of a heat or pressure gradient would lead to a decreasein entropy and thus violate the Second Law. The gatekeeper is ableto detect the velocity of each particle and can control the gate accordingly.The demon allows particles with higher than average speeds (shownin red in Figure 1a)to pass from the right section to the left, but not from the leftto the right. The opposite holds for slower particles (shown in bluein Figure 1a). Thegatekeeper thus causes a nonuniform distribution of particles betweenthe two sections, creating a temperature gradient. Similarly, a demoncapable of detecting the direction of the particle and opening thegate accordingly can concentrate particles in one section and thusgenerate a pressure gradient (Figure 1b). If the gate is frictionless, then in both casesa nonequilibrium distribution has been achieved seemingly withoutdoing work, which would violate The Second Law. The solution to theapparent paradox lies in considering the information required by thedemon to know when to open the door. As the demon must measure thevelocity or direction of each particle approaching the door33 and cannot have infinite memory,34 at some point the demon must “forget”this information. The destruction of information has a minimum enthalpiccost associated with it35 as has been experimentallyverified,36 which always exceeds the decreasein entropy in the container. Thus, a local decrease in entropy ispaid for by a generalized increase upon information deletion.


Artificial Molecular Machines.

Erbas-Cakmak S, Leigh DA, McTernan CT, Nussbaumer AL - Chem. Rev. (2015)

Maxwell’sdemons. (a) A “temperature demon”sorts particles according to velocity, generating a temperature gradient.(b) A “pressure demon” sorts particles according totheir direction of movement, generating a pressure gradient.37
© Copyright Policy
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4585175&req=5

fig1: Maxwell’sdemons. (a) A “temperature demon”sorts particles according to velocity, generating a temperature gradient.(b) A “pressure demon” sorts particles according totheir direction of movement, generating a pressure gradient.37
Mentions: The Second Law of Thermodynamics states that the entropy ofan isolated system tends to increase, leading to an equilibrium distributionwith maximum entropy. To achieve any distribution other than the thermodynamicequilibrium, work must be done on the system. Various thought experimentshave been proposed that attempt to violate this premise and drivea system away from equilibrium without expending work. In the Maxwell’sDemon thought experiment, particles in a container are sorted by an“intelligent gatekeeper”, the “demon”(Figure 1).32 Gas particles are distributed in a containerpartitioned into two sections in an isolated system. The spontaneousformation of a heat or pressure gradient would lead to a decreasein entropy and thus violate the Second Law. The gatekeeper is ableto detect the velocity of each particle and can control the gate accordingly.The demon allows particles with higher than average speeds (shownin red in Figure 1a)to pass from the right section to the left, but not from the leftto the right. The opposite holds for slower particles (shown in bluein Figure 1a). Thegatekeeper thus causes a nonuniform distribution of particles betweenthe two sections, creating a temperature gradient. Similarly, a demoncapable of detecting the direction of the particle and opening thegate accordingly can concentrate particles in one section and thusgenerate a pressure gradient (Figure 1b). If the gate is frictionless, then in both casesa nonequilibrium distribution has been achieved seemingly withoutdoing work, which would violate The Second Law. The solution to theapparent paradox lies in considering the information required by thedemon to know when to open the door. As the demon must measure thevelocity or direction of each particle approaching the door33 and cannot have infinite memory,34 at some point the demon must “forget”this information. The destruction of information has a minimum enthalpiccost associated with it35 as has been experimentallyverified,36 which always exceeds the decreasein entropy in the container. Thus, a local decrease in entropy ispaid for by a generalized increase upon information deletion.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

bonded molecules and on catenanes and rotaxanes in which switching of other protic solvents... This effect (listed in descending binding ability) stations on the thread, macrocycle In these systems, fast-responding reporters are preferred... practical applications by utilizing molecular scale changes to create macroscopic effects... The thread of these rotaxanes included an anthracene fluorophore similar application in synthetic polymers often furnishes a useful result... of Brownian motion can be exploited to great effect in the synthesis every aspect of functional molecule and materials design... An improved robotics” in which ratcheted motions of molecular components

No MeSH data available.