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CHEMOMECHANICAL TRANSDUCTION AND THE SECOND LAW OF THERMODYNAMICS
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Pentcho Valev
May 19, 2012, 2:16:16 AM5/19/12
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1367611/pdf/biophysj00645-0017.pdf
POLYELECTROLYTES AND THEIR BIOLOGICAL INTERACTIONS, A. KATCHALSKY, pp. 13-15: "Let the polymolecule be a negatively charged polyacid in a stretched state and have a length L. Now let us add to the molecule a mineral acid to provide hydrogen ions to combine with the ionized carboxylate groups and transform them into undissociated carboxylic groups according to the reaction RCOO- + H+ = RCOOH. By means of this reaction, the electrostatic repulsion which kept the macromolecule in a highly stretched state vanishes and instead the Brownian motion and intramolecular attraction cause a coiling up of the polymeric chains. Upon coiling, the polymolecule contracts and lifts the attached weight through a distance deltaL. On lifting the weight, mechanical work f*deltaL was performed... (...) FIGURE 4: Polyacid gel in sodium hydroxide solution: expanded. Polyacid gel in acid solution: contracted; weight is lifted."
https://data.epo.org/publication-server/pdf-document?PN=EP0830509%20EP%200830509&iDocId=5127209&iepatch=.pdf
Dan Urry, p. 14: "When the pH is lowered (that is, on raising the chemical potential, mu, of the protons present) at the isothermal condition of 37°C, these matrices can exert forces, f, sufficient to lift weights that are a thousand times their dry weight. This is chemomechanical transduction..."
It can rigorously be proved that the chemomechanical transduction described by Katchalsky and Urry does violate the second law of thermodynamics but even a cursory glance would suggest that anti-second-law behaviour is very likely. The work-producing force of contraction increases as hydrogen ions chemically react with the contractile macromolecule but the chemical reaction is spontaneous and, per se, does not consume work. (In a rigorous treatment, the work involved in adding and removing the mineral acid has to be evaluated).
Pentcho Valev
pva...@yahoo.com
POLYELECTROLYTES AND THEIR BIOLOGICAL INTERACTIONS, A. KATCHALSKY, pp. 13-15: "Let the polymolecule be a negatively charged polyacid in a stretched state and have a length L. Now let us add to the molecule a mineral acid to provide hydrogen ions to combine with the ionized carboxylate groups and transform them into undissociated carboxylic groups according to the reaction RCOO- + H+ = RCOOH. By means of this reaction, the electrostatic repulsion which kept the macromolecule in a highly stretched state vanishes and instead the Brownian motion and intramolecular attraction cause a coiling up of the polymeric chains. Upon coiling, the polymolecule contracts and lifts the attached weight through a distance deltaL. On lifting the weight, mechanical work f*deltaL was performed... (...) FIGURE 4: Polyacid gel in sodium hydroxide solution: expanded. Polyacid gel in acid solution: contracted; weight is lifted."
https://data.epo.org/publication-server/pdf-document?PN=EP0830509%20EP%200830509&iDocId=5127209&iepatch=.pdf
Dan Urry, p. 14: "When the pH is lowered (that is, on raising the chemical potential, mu, of the protons present) at the isothermal condition of 37°C, these matrices can exert forces, f, sufficient to lift weights that are a thousand times their dry weight. This is chemomechanical transduction..."
It can rigorously be proved that the chemomechanical transduction described by Katchalsky and Urry does violate the second law of thermodynamics but even a cursory glance would suggest that anti-second-law behaviour is very likely. The work-producing force of contraction increases as hydrogen ions chemically react with the contractile macromolecule but the chemical reaction is spontaneous and, per se, does not consume work. (In a rigorous treatment, the work involved in adding and removing the mineral acid has to be evaluated).
Pentcho Valev
pva...@yahoo.com
Pentcho Valev
May 19, 2012, 7:06:49 AM5/19/12
to
Chemical reactions are not true donors of energy when mechanical work is produced. A close inspection shows that they only channel the ambient heat into other forms of energy. Zihan Xu et al. seem to have found a way to get rid of the chemical-reaction camouflage accompanying the conversion of ambient heat into work:
http://arxiv.org/abs/1203.0161
Self-Charged Graphene Battery Harvests Electricity from Thermal Energy of the Environment, Zihan Xu et al: "Moreover, the thermal velocity of ions can be maintained by the external environment, which means it is unlimited. However, little study has been reported on converting the ionic thermal energy into electricity. Here we present a graphene device with asymmetric electrodes configuration to capture such ionic thermal energy and convert it into electricity. (...) To exclude the possibility of chemical reaction, we performed control experiments... (...) In conclusion, we could not find any evidences that support the opinion that the induced voltage came from chemical reaction. The mechanism for electricity generation by graphene in solution is a pure physical process..."
http://arxiv.org/abs/1204.6688
"Graphene can collect energy from the ambient heat and convert it to electricity, which makes it an ideal candidate for the fabrication of self-powered devices. However, this technology is suffering the high cost, which limits the practical use of it. In this work, we demonstrated that the cost can be reduced by using low cost reduced graphene oxide (RGO), graphite electrodes and low cost glass substrates. The results showed that this technology can be of practical value for the "battery" industry."
Pentcho Valev
pva...@yahoo.com
http://arxiv.org/abs/1203.0161
Self-Charged Graphene Battery Harvests Electricity from Thermal Energy of the Environment, Zihan Xu et al: "Moreover, the thermal velocity of ions can be maintained by the external environment, which means it is unlimited. However, little study has been reported on converting the ionic thermal energy into electricity. Here we present a graphene device with asymmetric electrodes configuration to capture such ionic thermal energy and convert it into electricity. (...) To exclude the possibility of chemical reaction, we performed control experiments... (...) In conclusion, we could not find any evidences that support the opinion that the induced voltage came from chemical reaction. The mechanism for electricity generation by graphene in solution is a pure physical process..."
http://arxiv.org/abs/1204.6688
"Graphene can collect energy from the ambient heat and convert it to electricity, which makes it an ideal candidate for the fabrication of self-powered devices. However, this technology is suffering the high cost, which limits the practical use of it. In this work, we demonstrated that the cost can be reduced by using low cost reduced graphene oxide (RGO), graphite electrodes and low cost glass substrates. The results showed that this technology can be of practical value for the "battery" industry."
Pentcho Valev
pva...@yahoo.com
Pentcho Valev
May 19, 2012, 5:37:59 PM5/19/12
to
Various devices (not only chemical reactions) can channel thermal motion into a macroscopic force able to perform useful work. For instance, the electric field between the plates of a capacitor orders water dipoles so that any thermal stroke coming from ambient heat contributes to the emergence of an additional hydrostatic pressure pushing the plates apart:
http://www.amazon.com/Introduction-Electromagnetic-Theory-Modern-Perspective/dp/0763738271
Introduction to Electromagnetic Theory: A Modern Perspective, Tai Chow, p. 267: "Calculations of the forces between charged conductors immersed in a liquid dielectric always show that the force is reduced by the factor K. There is a tendency to think of this as representing a reduction in the electrical forces between the charges on the conductors, as though Coulomb's law for the interaction of two charges should have the dielectric constant included in its denominator. This is incorrect, however. The strictly electric forces between charges on the conductors are not influenced by the presence of the dielectric medium. The medium is polarized, however, and the interaction of the electric field with the polarized medium results in an INCREASED FLUID PRESSURE ON THE CONDUCTORS that reduces the net forces acting on them."
http://farside.ph.utexas.edu/teaching/jk1/lectures/node44.html
"However, in experiments in which a capacitor is submerged in a dielectric liquid the force per unit area exerted by one plate on another is observed to decrease... (...) This apparent paradox can be explained by taking into account the difference in liquid pressure in the field filled space between the plates and the field free region outside the capacitor."
An explanation of the effect. Consider an oversimplified picture of the arrangement of water dipoles between the plates of the capacitor:
P+ (- +) (- +) (- +)..........(- +) -P
where P+ and -P are the positive and negative plate respectively. This arrangement has the lowest potential energy so any disturbance caused by thermal motion can only increase the potential energy, at the expense of heat absorbed from the surroundings. For instance, if the second dipole on the left receives a thermal stroke and undergoes rotation, the picture changes:
P+ (- +) (+ -) (- +)..........(- +) -P
As a result, the electrostatic repulsion increases and the string tends to stretch. Macroscopically, this is expressed as an additional hydrostatic pressure emerging between the plates and pushing them apart. This pressure is non-conservative and can do work at the expense of heat absorbed from the surroundings, in violation of the second law of thermodynamics. The waterfall presented in fig. 2 below is an illustration of a possible anti-second-law mechanism:
http://energythic.com/view.php?node=208
"However we may try to go around this difficulty by not expecting the liquid to flow out at the edges, where the retarding forces are strong (sealing the edges), but through a hole drilled into the middle of the grounded plate, as shown in fig. 2."
Pentcho Valev
pva...@yahoo.com
http://www.amazon.com/Introduction-Electromagnetic-Theory-Modern-Perspective/dp/0763738271
Introduction to Electromagnetic Theory: A Modern Perspective, Tai Chow, p. 267: "Calculations of the forces between charged conductors immersed in a liquid dielectric always show that the force is reduced by the factor K. There is a tendency to think of this as representing a reduction in the electrical forces between the charges on the conductors, as though Coulomb's law for the interaction of two charges should have the dielectric constant included in its denominator. This is incorrect, however. The strictly electric forces between charges on the conductors are not influenced by the presence of the dielectric medium. The medium is polarized, however, and the interaction of the electric field with the polarized medium results in an INCREASED FLUID PRESSURE ON THE CONDUCTORS that reduces the net forces acting on them."
http://farside.ph.utexas.edu/teaching/jk1/lectures/node44.html
"However, in experiments in which a capacitor is submerged in a dielectric liquid the force per unit area exerted by one plate on another is observed to decrease... (...) This apparent paradox can be explained by taking into account the difference in liquid pressure in the field filled space between the plates and the field free region outside the capacitor."
An explanation of the effect. Consider an oversimplified picture of the arrangement of water dipoles between the plates of the capacitor:
P+ (- +) (- +) (- +)..........(- +) -P
where P+ and -P are the positive and negative plate respectively. This arrangement has the lowest potential energy so any disturbance caused by thermal motion can only increase the potential energy, at the expense of heat absorbed from the surroundings. For instance, if the second dipole on the left receives a thermal stroke and undergoes rotation, the picture changes:
P+ (- +) (+ -) (- +)..........(- +) -P
As a result, the electrostatic repulsion increases and the string tends to stretch. Macroscopically, this is expressed as an additional hydrostatic pressure emerging between the plates and pushing them apart. This pressure is non-conservative and can do work at the expense of heat absorbed from the surroundings, in violation of the second law of thermodynamics. The waterfall presented in fig. 2 below is an illustration of a possible anti-second-law mechanism:
http://energythic.com/view.php?node=208
"However we may try to go around this difficulty by not expecting the liquid to flow out at the edges, where the retarding forces are strong (sealing the edges), but through a hole drilled into the middle of the grounded plate, as shown in fig. 2."
Pentcho Valev
pva...@yahoo.com
Pentcho Valev
May 20, 2012, 1:16:22 AM5/20/12
to
Another device that channels ambient heat into other forms of energy:
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.108.097403
"Physicists have known for decades that, in principle, a semiconductor device can emit more light power than it consumes electrically. Experiments published in Physical Review Letters finally demonstrate this in practice, though at a small scale. (...) Decreasing the input power to 30 picowatts, the team detected nearly 70 picowatts of emitted light. The extra energy comes from lattice vibrations, so the device should be cooled slightly, as occurs in thermoelectric coolers. These initial results provide too little light for most applications. However, heating the light emitters increases their output power and efficiency, meaning they are like thermodynamic heat engines..."
http://physicsworld.com/cws/article/news/48882
"At first glance this conversion of waste heat to useful photons could appear to violate fundamental laws of thermodynamics, but lead researcher Parthiban Santhanam of the Massachusetts Institute of Technology explains that the process is perfectly consistent with the second law of thermodynamics. "The most counterintuitive aspect of this result is that we don't typically think of light as being a form of heat. Usually we ignore the entropy and think of light as work," he explains. "If the photons didn't have entropy (i.e. if they were a form of work, rather than heat), this would break the second law. Instead, the entropy shows up in the outgoing photons, so the second law is satisfied."
The light-is-not-work argument formally saves the second law of thermodynamics in this particular case but still the faith is undermined.
Pentcho Valev
pva...@yahoo.com
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.108.097403
"Physicists have known for decades that, in principle, a semiconductor device can emit more light power than it consumes electrically. Experiments published in Physical Review Letters finally demonstrate this in practice, though at a small scale. (...) Decreasing the input power to 30 picowatts, the team detected nearly 70 picowatts of emitted light. The extra energy comes from lattice vibrations, so the device should be cooled slightly, as occurs in thermoelectric coolers. These initial results provide too little light for most applications. However, heating the light emitters increases their output power and efficiency, meaning they are like thermodynamic heat engines..."
http://physicsworld.com/cws/article/news/48882
"At first glance this conversion of waste heat to useful photons could appear to violate fundamental laws of thermodynamics, but lead researcher Parthiban Santhanam of the Massachusetts Institute of Technology explains that the process is perfectly consistent with the second law of thermodynamics. "The most counterintuitive aspect of this result is that we don't typically think of light as being a form of heat. Usually we ignore the entropy and think of light as work," he explains. "If the photons didn't have entropy (i.e. if they were a form of work, rather than heat), this would break the second law. Instead, the entropy shows up in the outgoing photons, so the second law is satisfied."
The light-is-not-work argument formally saves the second law of thermodynamics in this particular case but still the faith is undermined.
Pentcho Valev
pva...@yahoo.com
Pentcho Valev
May 29, 2012, 7:31:48 AM5/29/12
to
Graphene self-cools and converts ambient heat into electricity:
http://www.dailytech.com/An+Incredible+Discovery+Graphene+Transistors+SelfCool/article21285.htm
"Overcoming technical challenges, the University of Illinois team used an atomic force microscope tip as a temperature probe to make the first nanometer-scale temperature measurements of a working graphene transistor. What they found was that the resistive heating ("waste heat") effect in graphene was weaker than its thermo-electric cooling effect at times. (...) Further, as the heat is converted back into electricity by the device, graphene transistors may have a two-fold power efficiency gain, both in ditching energetically expensive fans and by recycling heat losses into usable electricity. Professor King describes, "In silicon and most materials, the electronic heating is much larger than the self-cooling. However, we found that in these graphene transistors, there are regions where the thermoelectric cooling can be larger than the resistive heating, which allows these devices to cool themselves."
Thermodynamicists:
http://skipper810.files.wordpress.com/2010/06/062310_1437_couldsharia1.png?w=640
Pentcho Valev
pva...@yahoo.com
http://www.dailytech.com/An+Incredible+Discovery+Graphene+Transistors+SelfCool/article21285.htm
"Overcoming technical challenges, the University of Illinois team used an atomic force microscope tip as a temperature probe to make the first nanometer-scale temperature measurements of a working graphene transistor. What they found was that the resistive heating ("waste heat") effect in graphene was weaker than its thermo-electric cooling effect at times. (...) Further, as the heat is converted back into electricity by the device, graphene transistors may have a two-fold power efficiency gain, both in ditching energetically expensive fans and by recycling heat losses into usable electricity. Professor King describes, "In silicon and most materials, the electronic heating is much larger than the self-cooling. However, we found that in these graphene transistors, there are regions where the thermoelectric cooling can be larger than the resistive heating, which allows these devices to cool themselves."
Thermodynamicists:
http://skipper810.files.wordpress.com/2010/06/062310_1437_couldsharia1.png?w=640
Pentcho Valev
pva...@yahoo.com
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