| Topic: |
Science > Physics |
| User: |
"Doune60" |
| Date: |
10 Feb 2006 04:57:56 AM |
| Object: |
Thermodynamics |
I would like to start a discussion on the proposal to make an addition
to the Laws of Thermodynamics, viz;
"The transference of energy between any two systems requires an
available route"
This may seem a little obvious to many of you, but I feel it ties up a
loose end and brings a clearer link with QM.
Best regards
SCWilliams
.
|
|
| User: "Ken S. Tucker" |
|
| Title: Re: Thermodynamics |
10 Feb 2006 05:15:13 AM |
|
|
Doune60 wrote:
I would like to start a discussion on the proposal to make an addition
to the Laws of Thermodynamics, viz;
"The transference of energy between any two systems requires an
available route"
This may seem a little obvious to many of you, but I feel it ties up a
loose end
Maybe 2 loose ends...
and brings a clearer link with QM.
Best regards
SCWilliams
I agree, it has to do with the medium of transfer
between an event emitting energy and one in
another event receiving that energy.
I prefer the term "occurance" to connect those two
events since the coodinates x,y,z,t that conventionally
describes an event are modified by a differential of
energy, like
-DE @ x y z t => +DE' @ x' y' z' t'
where the
-DE "occurs" in frame K
and
+DE' "occurs" in frame K'.
The OP get's a 5 star post
Ken
.
|
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Thermodynamics |
10 Feb 2006 09:24:21 AM |
|
|
Doune60 wrote:
I would like to start a discussion on the proposal to make an addition
to the Laws of Thermodynamics, viz;
"The transference of energy between any two systems requires an
available route"
This may seem a little obvious to many of you, but I feel it ties up a
loose end and brings a clearer link with QM.
Look at http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heaeng.html
.
|
|
|
| User: "Doune60" |
|
| Title: Re: Thermodynamics |
10 Feb 2006 10:07:21 AM |
|
|
Thanks for this Sam.
The website gives some nice descriptions and diagrams for the First Law
(Conservation), Second Law (Direction) and Zeroth (symmetry).
I was more interested in establishing a prerequisite for an available
route, or mechanism, and its relationship with Potential Energy,
especially in particle exchange in Quantum Mechanics and Dark
Matter/Energy.
It seems to me that the First, Second and Zeroth imply the requirement
for a an available route, without an explicit statement.
Best Regards
SCW
.
|
|
|
|
|
| User: "Andy Resnick" |
|
| Title: Re: Thermodynamics |
13 Feb 2006 08:41:48 AM |
|
|
Doune60 wrote:
I would like to start a discussion on the proposal to make an addition
to the Laws of Thermodynamics, viz;
"The transference of energy between any two systems requires an
available route"
This may seem a little obvious to many of you, but I feel it ties up a
loose end and brings a clearer link with QM.
Best regards
SCWilliams
I don't understand what you mean. Are you referring to *spontaneous*
energy flux? If so, this is covered in the definition of the Gibbs free
energy. And what do you mean by "available route"- how do you square
that with tunneling?
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
13 Feb 2006 10:26:54 AM |
|
|
Dear Andrew
Many thanks for taking time to reply
After replies in other posts, I've modified this to "Energy dissipates
via the most efficient route" or "most efficient route" instead of
"available route" - although I meant it to be the same thing. It was
just I first considered the results of Yang and Lee (on weak
interaction's violation of the law of parity conservation), to be
counter-intuitive. I expanded it to cover all instances rather than
limiting it to a binary option.
Gibbs free energy concerns the energy which is available for doing
work, not the process or mechanism of exchange (e.g. it could equally
be used for convection or conduction). The idea I am putting forward is
very basic and much simpler than the derived concept of Gibbs, that is:
exchanging energy *always* exploits the most efficient (i.e. easiest)
route.
If you mean tunnelling in the quantum mechanical sense, then again I am
not concerned with what the process is, just that if there is an
exchange of energy that it exploits the most efficient route. In the
original post, I simply meant that there must be a process or route
available to exchange energy (a binary Yes or No option). Now I have
expanded this to mean that when there are multiple routes available, as
is generally the case, then the exchange is via the most efficient
route.
Best regards
SCW
.
|
|
|
| User: "Andy Resnick" |
|
| Title: Re: Thermodynamics |
13 Feb 2006 02:37:34 PM |
|
|
Doune wrote:
Dear Andrew
Many thanks for taking time to reply
After replies in other posts, I've modified this to "Energy dissipates
via the most efficient route" or "most efficient route" instead of
"available route" - although I meant it to be the same thing. It was
just I first considered the results of Yang and Lee (on weak
interaction's violation of the law of parity conservation), to be
counter-intuitive. I expanded it to cover all instances rather than
limiting it to a binary option.
Hmmm... This seems to be totally different that what you originally
wrote (which is fine, BTW). Energy dissipation can be different from
energy flux; for example the difference between the damping of an
excited state and a chemical reaction. Both involve energy flow, but
one dissipates energy from a coherent excitation to incoherent thermal
excitation and the other transports a coherent excited state into a
definite final state.
Gibbs free energy concerns the energy which is available for doing
work, not the process or mechanism of exchange (e.g. it could equally
be used for convection or conduction). The idea I am putting forward is
very basic and much simpler than the derived concept of Gibbs, that is:
exchanging energy *always* exploits the most efficient (i.e. easiest)
route.
That's sort of a tautology- simply assign *all* possible routes a
weighting factor depending on how likely it is to occur..... and you get
a Boltzman distribution. Or something similar, right?
If you mean tunnelling in the quantum mechanical sense, then again I am
not concerned with what the process is, just that if there is an
exchange of energy that it exploits the most efficient route. In the
original post, I simply meant that there must be a process or route
available to exchange energy (a binary Yes or No option). Now I have
expanded this to mean that when there are multiple routes available, as
is generally the case, then the exchange is via the most efficient
route.
Well, I meant it more generally: tunneling occurs in reaction kinetics
also (that's one way to explain how enzymes work, they lower the energy
barrier). I would think that the existence of a thermal reservior in
contact with a system would constitute the existence of a "route" by
which to exchange energy. To be sure, there was some interesting things
done with isolated microscopic resonant cavities (cavity QED) which
allowed people to tune the coupling between the system and a reservior.
The physics lab manager at UAH was doing some cool stuff using radio
equipment and slabs of housing insulation: the large wavelength allowed
a major relaxation of machining and positioning tolerances....
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
|
|
|
| User: "Ken S. Tucker" |
|
| Title: Re: Thermodynamics |
13 Feb 2006 03:16:13 PM |
|
|
Andy Resnick wrote:
Doune wrote:
Dear Andrew
Many thanks for taking time to reply
After replies in other posts, I've modified this to "Energy dissipates
via the most efficient route" or "most efficient route" instead of
"available route" - although I meant it to be the same thing. It was
just I first considered the results of Yang and Lee (on weak
interaction's violation of the law of parity conservation), to be
counter-intuitive. I expanded it to cover all instances rather than
limiting it to a binary option.
Hmmm... This seems to be totally different that what you originally
wrote (which is fine, BTW). Energy dissipation can be different from
energy flux; for example the difference between the damping of an
excited state and a chemical reaction. Both involve energy flow, but
one dissipates energy from a coherent excitation to incoherent thermal
excitation and the other transports a coherent excited state into a
definite final state.
Gibbs free energy concerns the energy which is available for doing
work, not the process or mechanism of exchange (e.g. it could equally
be used for convection or conduction). The idea I am putting forward is
very basic and much simpler than the derived concept of Gibbs, that is:
exchanging energy *always* exploits the most efficient (i.e. easiest)
route.
That's sort of a tautology- simply assign *all* possible routes a
weighting factor depending on how likely it is to occur..... and you get
a Boltzman distribution. Or something similar, right?
If you mean tunnelling in the quantum mechanical sense, then again I am
not concerned with what the process is, just that if there is an
exchange of energy that it exploits the most efficient route. In the
original post, I simply meant that there must be a process or route
available to exchange energy (a binary Yes or No option). Now I have
expanded this to mean that when there are multiple routes available, as
is generally the case, then the exchange is via the most efficient
route.
Well, I meant it more generally: tunneling occurs in reaction kinetics
also (that's one way to explain how enzymes work, they lower the energy
barrier). I would think that the existence of a thermal reservior in
contact with a system would constitute the existence of a "route" by
which to exchange energy. To be sure, there was some interesting things
done with isolated microscopic resonant cavities (cavity QED) which
allowed people to tune the coupling between the system and a reservior.
The physics lab manager at UAH was doing some cool stuff using radio
equipment and slabs of housing insulation: the large wavelength allowed
a major relaxation of machining and positioning tolerances....
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
Cool :-)
I interpret SCW's original post as being two 100% insulated
spheres A & B but at different temperatures or voltages.
If I insert a wire into them to connect the sphere's an
energy conduction is then possible, carrying heat, current
or both.
Hey, make sphere A cold and charged to some voltage V
and sphere B hot and uncharged, could the heat flow and
current balance, such that there is no energy flow?
Regards
Ken S. Tucker
.
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
13 Feb 2006 06:06:32 PM |
|
|
Cool :-)
I interpret SCW's original post as being two 100% insulated
spheres A & B but at different temperatures or voltages.
If I insert a wire into them to connect the sphere's an
energy conduction is then possible, carrying heat, current
or both.
Hey, make sphere A cold and charged to some voltage V
and sphere B hot and uncharged, could the heat flow and
current balance, such that there is no energy flow?
Regards
Ken S. Tucker
That's a *really* interesting question. I need to think about this, but
my gut reaction is that since there is energy flow, there must be an
increase in entropy in each sphere, but not in the overall system...
SCW
.
|
|
|
|
| User: "Andy Resnick" |
|
| Title: Re: Thermodynamics |
14 Feb 2006 08:02:41 AM |
|
|
Ken S. Tucker wrote:
<snip>
I interpret SCW's original post as being two 100% insulated
spheres A & B but at different temperatures or voltages.
If I insert a wire into them to connect the sphere's an
energy conduction is then possible, carrying heat, current
or both.
Hey, make sphere A cold and charged to some voltage V
and sphere B hot and uncharged, could the heat flow and
current balance, such that there is no energy flow?
Regards
Ken S. Tucker
I don't see why not: consider a semipermeable membrane separating two
regions containing differing amounts of 'stuff'. The total system is
isothermal, but as you will see, adding a thermal gradient is just
another term.
The Nernst equation for the electrochemical gradient across the membrane is:
Du = RTln[[X_i]/[X_o]] + z_X F(V_i-V_o),
Where Du is the electrochemical energy difference (if RT goes to kT, Du
goes to DG, where G is the Gibbs free energy), [X_i] is the
concentration of molecular species X on one side, [X_o] the
concentration on the other side, V_i - V_o the voltage acorss the
membrane, z_X the charge associated with molecular species X, and F the
Faraday constant.
This equation is the coolest thing I have learned while here in the
medical school, because it allows different ions, like sodium and
potassium, to feel different driving forces (not just magnitude, but
also sign) across the membrane, even theough the membrane is at a single
voltage, because of the concentration dependence.
So yes, surely it's possible to exchange current for thermal energy.
And magnetic field, also- isn't that what magnetic cooling is? To make
the system spontaneously transfer charge for temperature would simply
require writing down the thermo-electrochemical gradient formula, and
determining under what conditions Du is negative.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
|
|
|
| User: "Ken S. Tucker" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 12:52:08 PM |
|
|
Andy Resnick wrote:
Ken S. Tucker wrote:
<snip>
I interpret SCW's original post as being two 100% insulated
spheres A & B but at different temperatures or voltages.
If I insert a wire into them to connect the sphere's an
energy conduction is then possible, carrying heat, current
or both.
Hey, make sphere A cold and charged to some voltage V
and sphere B hot and uncharged, could the heat flow and
current balance, such that there is no energy flow?
Regards
Ken S. Tucker
I don't see why not: consider a semipermeable membrane separating two
regions containing differing amounts of 'stuff'. The total system is
isothermal, but as you will see, adding a thermal gradient is just
another term.
The Nernst equation for the electrochemical gradient across the membrane is:
Du = RTln[[X_i]/[X_o]] + z_X F(V_i-V_o),
Where Du is the electrochemical energy difference (if RT goes to kT, Du
goes to DG, where G is the Gibbs free energy), [X_i] is the
concentration of molecular species X on one side, [X_o] the
concentration on the other side, V_i - V_o the voltage across the
membrane, z_X the charge associated with molecular species X, and F the
Faraday constant.
Ok.
This equation is the coolest thing I have learned while here in the
medical school, because it allows different ions, like sodium and
potassium, to feel different driving forces (not just magnitude, but
also sign) across the membrane, even theough the membrane is at a single
voltage, because of the concentration dependence.
I flunked biology...
You mentioned "protein dynamics", if the membrane
is semi-porous such as the epidremis of an ameoba,
is that the sort of "osomatic" action to exchange
nutrients with the enviroment? Or is that something
entirely different?
So yes, surely it's possible to exchange current for thermal energy.
And magnetic field, also- isn't that what magnetic cooling is?
This may be a digression, however I think the "Peltier Effect"
can apply if that's what you want to discuss. As to "magnetic
cooling", I think that's more exotic.
To make
the system spontaneously transfer charge for temperature would simply
require writing down the thermo-electrochemical gradient formula, and
determining under what conditions Du is negative.
Ok, then the OP can model the thermal transfer
route based on "Kirchoff's Laws" of electrical conduction.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
Thanks
Ken S. Tucker
.
|
|
|
| User: "Andy Resnick" |
|
| Title: Re: Thermodynamics |
16 Feb 2006 07:53:05 AM |
|
|
Ken S. Tucker wrote:
<snip>
I flunked biology...
You mentioned "protein dynamics", if the membrane
is semi-porous such as the epidremis of an ameoba,
is that the sort of "osomatic" action to exchange
nutrients with the enviroment? Or is that something
entirely different?
There's two effects involved, which are different in origin. Let's
first consider a semi-premeable membrane, which is freely permeable to
water and small charged particles (like ions) but impermeable to large,
highly charged molecules (like proteins). We start with equal amounts
of small ions on one side (each of concentration [x] in the exterior),
and on the interior, one of the ion species is present at concentration
[x], and the charge is balanced by a small number of the highly charged
protein molecules. The membrane will spontaneously create a charge
across the membrane, and additionally there will be a hydraulic pressure
difference across the membrane. This is called "Gibbs-Donnan
equilibrium", and unless the small ions are actively pumped out of the
cell, the cell will swell until bursting.
Now the cell membrane is not freely permeable to all small ions, and in
fact the ion channels present can easily distinguish between sodium and
potassium ions based on the hydration radius. Consider sodium: the
concentration of sodium inside a cell is about 0.1 times the
concentration outside, and the converse is true for potassium: the cell
has 10 times as much as the extracellular space. So, even though there
is a single (negative by convention) membrane potential, the
concentration gradient is sufficient for sodium to want to enter the
cell, and potassium to leave the cell. Now, by coupling energetically
*unfavorable* transport of uncharged molecules like glucose (the cell
wants as much as possible) to the energetically favorable motion of one
of those two ion species, directed transport becomes possible. So every
cell has a small system of sodium, potassium, and chloride pumps to
maintain the concentration gradient (and membrane potential), while
moving things into and out of the cell.
Protein folding and binding is something totally different, and I don't
think the thermodynamics of either has been satisfactorally worked out.
There are partial steps and good ideas out there, but I think the
current research focus is on protein structure, determining binding
sites via NMR, etc.
This may be a digression, however I think the "Peltier Effect"
can apply if that's what you want to discuss. As to "magnetic
cooling", I think that's more exotic.
Yes- the Peltier effect, that's what I was thinking of.
<snip>
Ok, then the OP can model the thermal transfer
route based on "Kirchoff's Laws" of electrical conduction.
I agree.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
|
|
|
| User: "Ken S. Tucker" |
|
| Title: Re: Thermodynamics |
16 Feb 2006 11:51:11 AM |
|
|
Andy Resnick wrote:
Ken S. Tucker wrote:
<snip>
I flunked biology...
You mentioned "protein dynamics", if the membrane
is semi-porous such as the epidremis of an ameoba,
is that the sort of "osomatic" action to exchange
nutrients with the enviroment? Or is that something
entirely different?
Wow, that's a Wiki class essay...
There's two effects involved, which are different in origin. Let's
first consider a semi-premeable membrane, which is freely permeable to
water and small charged particles (like ions) but impermeable to large,
highly charged molecules (like proteins). We start with equal amounts
of small ions on one side (each of concentration [x] in the exterior),
and on the interior, one of the ion species is present at concentration
[x], and the charge is balanced by a small number of the highly charged
protein molecules. The membrane will spontaneously create a charge
across the membrane,
Would a "charge across the membrane" be a voltage across,
(wondering about that Nernst Eq).
and additionally there will be a hydraulic pressure
difference across the membrane. This is called "Gibbs-Donnan
equilibrium", and unless the small ions are actively pumped out of the
cell, the cell will swell until bursting.
I think your essay is better than,
http://www.people.vcu.edu/~mikuleck/courses/gdeq/
Can this "cell swell" be artificially created with a
porous membrane, like a balloon of some kind?
Now the cell membrane is not freely permeable to all small ions, and in
fact the ion channels present can easily distinguish between sodium and
potassium ions based on the hydration radius. Consider sodium: the
concentration of sodium inside a cell is about 0.1 times the
concentration outside, and the converse is true for potassium: the cell
has 10 times as much as the extracellular space. So, even though there
is a single (negative by convention) membrane potential, the
concentration gradient is sufficient for sodium to want to enter the
cell, and potassium to leave the cell. Now, by coupling energetically
*unfavorable* transport of uncharged molecules like glucose (the cell
wants as much as possible) to the energetically favorable motion of one
of those two ion species, directed transport becomes possible. So every
cell has a small system of sodium, potassium, and chloride pumps to
maintain the concentration gradient (and membrane potential), while
moving things into and out of the cell.
That's amazing. I'm guessing your use of "cell" is generic,
and applies to most animal cells? If so it explains why
animals can strongly crave salt, NaCl.
Protein folding and binding is something totally different, and I don't
think the thermodynamics of either has been satisfactorally worked out.
There are partial steps and good ideas out there, but I think the
current research focus is on protein structure, determining binding
sites via NMR, etc.
Is that NMR acronym the same as MRI ?
This may be a digression, however I think the "Peltier Effect"
can apply if that's what you want to discuss. As to "magnetic
cooling", I think that's more exotic.
Yes- the Peltier effect, that's what I was thinking of.
LOL, a friend told me about his invention of using the Peltier
effect to cool the bottom kitty litter boxes, apparently
kitty's like putting waste into a cooler spot for odor
suppression and 40F is ideal.
Ok, then the OP can model the thermal transfer
route based on "Kirchoff's Laws" of electrical conduction.
I agree.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
Thanks
Ken
.
|
|
|
| User: "Andy Resnick" |
|
| Title: Re: Thermodynamics |
16 Feb 2006 12:17:09 PM |
|
|
Ken S. Tucker wrote:
Andy Resnick wrote:
<snip>
There's two effects involved, which are different in origin. Let's
first consider a semi-premeable membrane, which is freely permeable to
water and small charged particles (like ions) but impermeable to large,
highly charged molecules (like proteins). We start with equal amounts
of small ions on one side (each of concentration [x] in the exterior),
and on the interior, one of the ion species is present at concentration
[x], and the charge is balanced by a small number of the highly charged
protein molecules. The membrane will spontaneously create a charge
across the membrane,
Would a "charge across the membrane" be a voltage across,
(wondering about that Nernst Eq).
Oops- good catch. Yes, you are correct.
and additionally there will be a hydraulic pressure
difference across the membrane. This is called "Gibbs-Donnan
equilibrium", and unless the small ions are actively pumped out of the
cell, the cell will swell until bursting.
I think your essay is better than,
http://www.people.vcu.edu/~mikuleck/courses/gdeq/
Can this "cell swell" be artificially created with a
porous membrane, like a balloon of some kind?
Thanks- I was surprised at how this stuff is considered totally
elementary, first-year stuff in medical school. Of course, they are so
math-averse that the presentation level is around 9th grade, but even so....
You probably have seen the cell swelling stuff in pictures of red blood
cells, but the same thing can be observed with Xenopus eggs- those are
large (1 mm) frog eggs. People do make empty lipid bilayer vesicles,
but I think those are pretty stable; the key is to have these ion
channels present. Then people add drugs and whatnot to plug up or
disable different ion channels and see what happens.
<snip>
That's amazing. I'm guessing your use of "cell" is generic,
and applies to most animal cells? If so it explains why
animals can strongly crave salt, NaCl.
Yeah, it's generic in the sense of 'atom' and 'molecule'. Plant cells
are different because of the rigid cell wall, and bacteria still
different because of various reasons. The whole reason we have so much
salt is because we all came from the ocean. And the extracellular fluid
composition is as tightly controlled as the intercellular fluid. I was
recently wondering why saline, which has a 'natural' salt composition
(and is the basic ingredient in all of our cell culture media), tastes
salty. Because naively, if the salt composition in saline is identical
to the "normal" salt balance in our body, it should taste neutral...
right? There is interesting work out there in the molecular basis of
taste and food preference.
Protein folding and binding is something totally different, and I don't
think the thermodynamics of either has been satisfactorally worked out.
There are partial steps and good ideas out there, but I think the
current research focus is on protein structure, determining binding
sites via NMR, etc.
Is that NMR acronym the same as MRI ?
Yeah, I insist on NMR, 'cuz I ain't afraid of nu-kyu-lar. :)
I suppose Nuclear Magnetic resonance is a spectral method, while
Magnetic Resonance Imaging is an imaging method.... but they are the
same thing, really. Fourier transforms of each other, at least.
This may be a digression, however I think the "Peltier Effect"
can apply if that's what you want to discuss. As to "magnetic
cooling", I think that's more exotic.
Yes- the Peltier effect, that's what I was thinking of.
LOL, a friend told me about his invention of using the Peltier
effect to cool the bottom kitty litter boxes, apparently
kitty's like putting waste into a cooler spot for odor
suppression and 40F is ideal.
Now *there's* an NIH grant waiting to be written!
<snip>
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
|
|
|
| User: "Ken S. Tucker" |
|
| Title: Re: Thermodynamics |
16 Feb 2006 01:17:38 PM |
|
|
Andy Resnick wrote:
Ken S. Tucker wrote:
Andy Resnick wrote:
<snip>
There's two effects involved, which are different in origin. Let's
first consider a semi-premeable membrane, which is freely permeable to
water and small charged particles (like ions) but impermeable to large,
highly charged molecules (like proteins). We start with equal amounts
of small ions on one side (each of concentration [x] in the exterior),
and on the interior, one of the ion species is present at concentration
[x], and the charge is balanced by a small number of the highly charged
protein molecules. The membrane will spontaneously create a charge
across the membrane,
Would a "charge across the membrane" be a voltage across,
(wondering about that Nernst Eq).
Oops- good catch. Yes, you are correct.
Not sure I'm correct. If I re-wrote your statement as,
"The membrane will spontaneously create a charge
*crossing* the membrane,"
as a causal effect of the potential across the membrane
at a quantum level, then you're going to the atomic
level in your thoughts.
In transistor theory, similiar explanations are provided
for charge and "hole" current transversing and NP
junction for example at the orbital level.
((To be picky, above you used [x] and [x] to be
for [xO] and [xI] if I read that correctly. Not ragging
ya, just enjoying a good essay)).
and additionally there will be a hydraulic pressure
difference across the membrane. This is called "Gibbs-Donnan
equilibrium", and unless the small ions are actively pumped out of the
cell, the cell will swell until bursting.
I think your essay is better than,
http://www.people.vcu.edu/~mikuleck/courses/gdeq/
Can this "cell swell" be artificially created with a
porous membrane, like a balloon of some kind?
Thanks- I was surprised at how this stuff is considered totally
elementary, first-year stuff in medical school. Of course, they are so
math-averse that the presentation level is around 9th grade, but even so....
You probably have seen the cell swelling stuff in pictures of red blood
cells, but the same thing can be observed with Xenopus eggs- those are
large (1 mm) frog eggs. People do make empty lipid bilayer vesicles,
but I think those are pretty stable; the key is to have these ion
channels present. Then people add drugs and whatnot to plug up or
disable different ion channels and see what happens.
Well if the theory of "cell swell" is correct, you may
have the key to "strokes", "migraines" etc. so that's
why I ask if such a thing might be reproduced with
a specific membrane, I denote a balloon on a macro-
scopic scale, such as a fluid filled balloon submersed
in an aquarium of a different fluid might actually demo
that.
That's amazing. I'm guessing your use of "cell" is generic,
and applies to most animal cells? If so it explains why
animals can strongly crave salt, NaCl.
Yeah, it's generic in the sense of 'atom' and 'molecule'. Plant cells
are different because of the rigid cell wall, and bacteria still
different because of various reasons. The whole reason we have so much
salt is because we all came from the ocean. And the extracellular fluid
composition is as tightly controlled as the intercellular fluid. I was
recently wondering why saline, which has a 'natural' salt composition
(and is the basic ingredient in all of our cell culture media), tastes
salty. Because naively, if the salt composition in saline is identical
to the "normal" salt balance in our body, it should taste neutral...
right?
There is interesting work out there in the molecular basis of
taste and food preference.
LOL, is that a relativity question. "Taste bud dynamics",
is a bit more exotic (and erotic) than I would know where
to start!
Protein folding and binding is something totally different, and I don't
think the thermodynamics of either has been satisfactorally worked out.
There are partial steps and good ideas out there, but I think the
current research focus is on protein structure, determining binding
sites via NMR, etc.
Is that NMR acronym the same as MRI ?
Yeah, I insist on NMR, 'cuz I ain't afraid of nu-kyu-lar. :)
OK, I was in the medical imaging (gamma & ultrasound)
business back in late 70's early 80's when the acronym
was **quietly** changed.
I suppose Nuclear Magnetic resonance is a spectral method, while
Magnetic Resonance Imaging is an imaging method.... but they are the
same thing, really. Fourier transforms of each other, at least.
You implied above (something I don't know) that NMR
can be as microscopic as examining protein dynamics,
do you have a name an apparatus that does that?
This may be a digression, however I think the "Peltier Effect"
can apply if that's what you want to discuss. As to "magnetic
cooling", I think that's more exotic.
Yes- the Peltier effect, that's what I was thinking of.
LOL, a friend told me about his invention of using the Peltier
effect to cool the bottom kitty litter boxes, apparently
kitty's like putting waste into a cooler spot for odor
suppression and 40F is ideal.
Now *there's* an NIH grant waiting to be written!
I'll tell him that :-).
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
Thanks again
Ken
.
|
|
|
| User: "Andy Resnick" |
|
| Title: Re: Thermodynamics |
17 Feb 2006 11:47:24 AM |
|
|
Ken S. Tucker wrote:
Andy Resnick wrote:
Ken S. Tucker wrote:
Andy Resnick wrote:
<snip>
There's two effects involved, which are different in origin. Let's
first consider a semi-premeable membrane, which is freely permeable to
water and small charged particles (like ions) but impermeable to large,
highly charged molecules (like proteins). We start with equal amounts
of small ions on one side (each of concentration [x] in the exterior),
and on the interior, one of the ion species is present at concentration
[x], and the charge is balanced by a small number of the highly charged
protein molecules. The membrane will spontaneously create a charge
across the membrane,
Would a "charge across the membrane" be a voltage across,
(wondering about that Nernst Eq).
Oops- good catch. Yes, you are correct.
Not sure I'm correct. If I re-wrote your statement as,
"The membrane will spontaneously create a charge
*crossing* the membrane,"
I should have written "a charge gradient across the membrane will arise
spontaneously, creating a potential jump across the membrane".
<snip>
((To be picky, above you used [x] and [x] to be
for [xO] and [xI] if I read that correctly. Not ragging
ya, just enjoying a good essay)).
No, that I did correctly: to ensure charge neutrality at the beginning,
there are equal concentrations of positive and negative ions *when the
ions have the same charge*. Now, adding divalent ions is done easily
enough, but my abilities to use text for formulas isn't that great.
<SNIP>
Well if the theory of "cell swell" is correct, you may
have the key to "strokes", "migraines" etc. so that's
why I ask if such a thing might be reproduced with
a specific membrane, I denote a balloon on a macro-
scopic scale, such as a fluid filled balloon submersed
in an aquarium of a different fluid might actually demo
that.
It's not a theory, it's a physical effect, and can be demonstrated very
easily. I don't know of artifical membranes that would demonstrate
this, but I don't know the field that well either. I don't see what it
has to do with migraines, strokes, etc.
<snip>
You implied above (something I don't know) that NMR
can be as microscopic as examining protein dynamics,
do you have a name an apparatus that does that?
NMR is a standard technique for determining protein structure, I confess
I don't understand it that well, but a web search for NOESY and related
terms should point the way.
<snip>
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
|
|
|
|
|
|
|
|
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
14 Feb 2006 03:32:56 AM |
|
|
Hi Andy
Thanks for this reply - this contains some really interesting stuff.
Hmmm... This seems to be totally different that what you originally
wrote (which is fine, BTW).
<snip>
Yes, I can see how it may appear that way. However, to me, the two
statements I made are the same. Due to the SR prediction there is no
such thing as a simultaneous event, the routes available to a process
will only ever be binary and so occur at nodes - there will never be
an option instantaneously available between three routes.
So, the possibilities are only ever a choice between two routes, or
three options:
(i) There are no routes available.
(ii) Route 1 is the path of least resistance.
(ii) Route 2 is the path of least resistance.
This is where the "available route" priciple comes from, and I think is
still the core of the idea.
Of course, very few process involve a single node - the process
continues along a series of nodes until the energy is dissipated, hence
the revised statement.
In terms of energy flux and Boltzman distribution, I see this as a
macroscopic description of discrete operations This is because density
variations appear in both energy flux and a Boltzman distribution. For
example, a gas can be described by the ideal gas law ( PV = nRT) or in
terms of kinetic theory. Since the kinetic theory of gases is the study
of the microscopic behaviour of molecules and the interactions which
lead to macroscopic relationships like the ideal gas law, I see the
kinetic theory as providing the more accurate, and therefore valid,
picture (at least in terms of my proposal!).
Well, I meant it more generally: tunnelling occurs in reaction kinetics
also (that's one way to explain how enzymes work, they lower the energy
barrier). I would think that the existence of a thermal reservoir in
contact with a system would constitute the existence of a "route" by
which to exchange energy.
Yes, I agree. But in any laboratory examination, there must be surely
be a multitude of routes available over the contact area - due to
slight variations in depth and thermal conductivity. We couldn't
consider the contact area to be a single route unless it was a single
atom.
To be sure, there was some interesting things
done with isolated microscopic resonant cavities (cavity QED) which
allowed people to tune the coupling between the system and a reservoir.
The physics lab manager at UAH was doing some cool stuff using radio
equipment and slabs of housing insulation: the large wavelength allowed
a major relaxation of machining and positioning tolerances....
God I feel out of touch! Things seemed to have moved a long wince I was
at college! This is really interesting and I will take a look.
Best regards
SCW
.
|
|
|
| User: "Andy Resnick" |
|
| Title: Re: Thermodynamics |
14 Feb 2006 08:11:07 AM |
|
|
Doune wrote:
Andy Resnick wrote:
Well, I meant it more generally: tunnelling occurs in reaction kinetics
also (that's one way to explain how enzymes work, they lower the energy
barrier). I would think that the existence of a thermal reservoir in
contact with a system would constitute the existence of a "route" by
which to exchange energy.
Yes, I agree. But in any laboratory examination, there must be surely
be a multitude of routes available over the contact area - due to
slight variations in depth and thermal conductivity. We couldn't
consider the contact area to be a single route unless it was a single
atom.
I think I see where you are going with this, and I have to confess a
bias towards the continuum picture rather than the "pointilist" picture.
So for me, there is no difficulty- energy is a field, and the
variation in thermal conductivity is simply a space-dependent weighing
factor, which would predict localized 'hot spots', etc.
This point of view gets me in trouble with other biophysics types-
especially when we start talking about protein dynamics.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
14 Feb 2006 08:31:11 AM |
|
|
Andy Resnick wrote:
This point of view gets me in trouble with other biophysics types-
especially when we start talking about protein dynamics.
I don't see a problem with your view if it works well. I'm just
approaching this from the Photoelectric Effect end of things.
I'm getting my head bitten off in other news groups for pointing out
discrete and "continuum" models give the same results!
Take Care
SCW
.
|
|
|
| User: "Andy Resnick" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 07:59:24 AM |
|
|
Doune wrote:
Andy Resnick wrote:
This point of view gets me in trouble with other biophysics types-
especially when we start talking about protein dynamics.
I don't see a problem with your view if it works well. I'm just
approaching this from the Photoelectric Effect end of things.
I'm getting my head bitten off in other news groups for pointing out
discrete and "continuum" models give the same results!
Well, they should give the same results. The difference is that
discrete and continuum models have different postulates, and sometimes
it's non-trivial to translate a fundamental construct from one model
into the other model.
For proteins, the key-and-lock model of ligand binding works well using
the discrete model, where one can draw what a protein "looks like", and
how ligand binding changes the "shape" of the molecule, but the
continuum picture is much better at discussing reaction energetics and
folding dynamics (IMHO).
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
|
|
|
|
|
|
|
|
| User: "PD" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 11:49:39 AM |
|
|
Doune wrote:
Dear Andrew
Many thanks for taking time to reply
After replies in other posts, I've modified this to "Energy dissipates
via the most efficient route" or "most efficient route" instead of
"available route" - although I meant it to be the same thing. It was
just I first considered the results of Yang and Lee (on weak
interaction's violation of the law of parity conservation), to be
counter-intuitive. I expanded it to cover all instances rather than
limiting it to a binary option.
I don't think this works. Consider parallel electric circuits, where
energy is deposited along both paths simultaneously. This "parallel
circuit" analysis also applies to magnetic flux, to heat flow, to fluid
flow, and a variety of other circumstances.
Even in quantum mechanics, the path integral formulation says that all
paths between initial and final states contribute to the total process
(though in this case there is entanglement between the various paths
and consequent interference phenomena that are not considered in the
classical examples).
Gibbs free energy concerns the energy which is available for doing
work, not the process or mechanism of exchange (e.g. it could equally
be used for convection or conduction). The idea I am putting forward is
very basic and much simpler than the derived concept of Gibbs, that is:
exchanging energy *always* exploits the most efficient (i.e. easiest)
route.
If you mean tunnelling in the quantum mechanical sense, then again I am
not concerned with what the process is, just that if there is an
exchange of energy that it exploits the most efficient route. In the
original post, I simply meant that there must be a process or route
available to exchange energy (a binary Yes or No option). Now I have
expanded this to mean that when there are multiple routes available, as
is generally the case, then the exchange is via the most efficient
route.
Best regards
SCW
.
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 12:58:13 PM |
|
|
PD Wrote:
Thanks ofr the reply
I don't think this works. Consider parallel electric circuits, where
energy is deposited along both paths simultaneously. This "parallel
circuit" analysis also applies to magnetic flux, to heat flow, to fluid
flow, and a variety of other circumstances.
I think we are talking at crossed purposes - you're right, in all your
examples above, it just depends on your definition of route. In your
example above you're considering multiple routes, whereas I was
considering the resistance met along a single route that would affect
the path. In each of the examples you give, there will be density
variations that will lead to variations in route. For instance, your
electrical circuit example appears to imply that current flows equally
along both circuits (I know you haven't said this, but I take
that's the gist), and therefore each path has equal resistance. In
reality, this is unlikely and there would be variation in voltage and
current between the circuits.
Even in quantum mechanics, the path integral formulation says that all
paths between initial and final states contribute to the total process
(though in this case there is entanglement between the various paths
and consequent interference phenomena that are not considered in the
classical examples).
Again this depends on what you consider to be the route. The path
integral formulation is a description of quantum theory that
generalises the action principle of classical mechanics. In this thread
I'm more interested in the invoking of, and change in, the route than
the actual mechanism of energy dissapation, however, having said that I
not a big fan of generalisations and would prefer to see a detailed
model over statistics - although I do admire Feynman!
Best regards
SCW
.
|
|
|
| User: "Ken S. Tucker" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 01:41:57 PM |
|
|
Doune wrote:
....
snip ok stuff
Again this depends on what you consider to be the route. The path
integral formulation is a description of quantum theory that
generalises the action principle of classical mechanics. In this thread
I'm more interested in the invoking of, and change in, the route than
the actual mechanism of energy dissapation,
"change in the route"
Ah, why does a river meander or
why does a light bulb increase resistance as the voltage
applied increases, and what effect does that have in
a circuit, thermal or otherwise.
however, having said that I
not a big fan of generalisations and would prefer to see a detailed
model over statistics - although I do admire Feynman!
But a detailed model is based on generalizations, like
Kirchoff's Laws. What I like about your suggestion is
somewhat along the lines of increasing the "R-value"
of insulation as the temperature differential increases.
I recall Cashmir sweaters do that.
Regards
Ken S. Tucker
.
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 02:49:08 PM |
|
|
I recall Cashmir sweaters do that.
Regards
Ken S. Tucker
Cashmir? You must be on a good package Ken!
.
|
|
|
| User: "Ken S. Tucker" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 03:46:59 PM |
|
|
Doune wrote:
I recall Cashmir sweaters do that.
Regards
Ken S. Tucker
Cashmir? You must be on a good package Ken!
Don't quite know what you mean Doune,
There are plenty of examples to show how a
non-linearity in energy flow happens, and
sometimes chaotically. a lightning bolt changing
paths is an exciting visual experience.
In the case of Cashmir, the differential of
temperature causes the insulating fibres
to expand to a greater radius, like a bi-metal
therometer, and traps more air and expands
the "R-level" insulational level, animals evolve
to do those things.
But Douane what does "be on a good package
mean" ???
Regards
Ken S. Tucker
.
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 04:38:13 PM |
|
|
But Douane what does "be on a good package
mean" ???
Regards
Ken S. Tucker
Cashmir is very expensive. On a good package is management-speak for a
good salary, car, pension, nice office on the 6th floorr etc.
It was just a joke! I
Best regards
SCW
.
|
|
|
| User: "Ken S. Tucker" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 06:01:21 PM |
|
|
Doune wrote:
Cashmir is very expensive. On a good package is management-speak for a
good salary, car, pension, nice office on the 6th floorr etc.
It was just a joke! I
Best regards
SCW
My point was to introduce 3 ways to support your
point about non-linearity in energy continuity...
1) Meandering rivers
2) light bulbs in circuits
3) Cashmir sweaters.
each of which varies the *rate of energy flux* in proportion
to the applied potential.
As you (Doune) spec'd in your OP was to
have a look at thermodynamics, that's not a joke,
it's good stuff, personally I'm learning.
Cheers
Ken
.
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
16 Feb 2006 01:58:49 AM |
|
|
Ken S. Tucker Wrote:
<snip>
As you (Doune) spec'd in your OP was to
have a look at thermodynamics, that's not a joke,
it's good stuff, personally I'm learning.
Yes, I agree, you're absolutely right. Thanks for the post.
Best regards
Sean
.
|
|
|
|
|
|
|
|
|
| User: "PD" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 01:23:25 PM |
|
|
Doune wrote:
PD Wrote:
Thanks ofr the reply
I don't think this works. Consider parallel electric circuits, where
energy is deposited along both paths simultaneously. This "parallel
circuit" analysis also applies to magnetic flux, to heat flow, to fluid
flow, and a variety of other circumstances.
I think we are talking at crossed purposes - you're right, in all your
examples above, it just depends on your definition of route. In your
example above you're considering multiple routes, whereas I was
considering the resistance met along a single route that would affect
the path. In each of the examples you give, there will be density
variations that will lead to variations in route. For instance, your
electrical circuit example appears to imply that current flows equally
along both circuits (I know you haven't said this, but I take
that's the gist), and therefore each path has equal resistance. In
reality, this is unlikely and there would be variation in voltage and
current between the circuits.
No, I didn't mean to imply that at all.
If one path has a resistance of 90 ohms and the resistance of the other
path is 2 ohms, then there will be 45 times more current in the latter
path than in the former path. But this does not mean that all the
current will choose the 2 ohm path.
Even in quantum mechanics, the path integral formulation says that all
paths between initial and final states contribute to the total process
(though in this case there is entanglement between the various paths
and consequent interference phenomena that are not considered in the
classical examples).
Again this depends on what you consider to be the route. The path
integral formulation is a description of quantum theory that
generalises the action principle of classical mechanics.
Yes, and the sum over all histories is what I'm referring to.
In this thread
I'm more interested in the invoking of, and change in, the route than
the actual mechanism of energy dissapation, however, having said that I
not a big fan of generalisations and would prefer to see a detailed
model over statistics - although I do admire Feynman!
Best regards
SCW
.
|
|
|
| User: "Doune" |
|
| Title: Re: Thermodynamics |
15 Feb 2006 02:41:46 PM |
|
|
PD Wrote:
No, I didn't mean to imply that at all.
If one path has a resistance of 90 ohms and the resistance of the other
path is 2 ohms, then there will be 45 times more current in the latter
path than in the former path. But this does not mean that all the
current will choose the 2 ohm path.
Exactly - which is why I said "...there would be variation in voltage
and current between the circuits." not "...all of current would flow
along the circuit with least resistance"
Just to clarify, it seems to me that you have implied that there are
two routes in your electrical circuit example (correct me if I am
wrong). I believe that there are a multiple nodal routes, (just like a
route between two towns is connected by roads) in just one or other of
the circuits, due to variations in density and resistivity of the
conductor. The argument comes down to the treatment - a statistical
analysis or kinetic theory.
Best regards
SCW
.
|
|
|
|
|
|
|
|
|
|
Related Articles |
|
|
