A reader tried to comment on Paper Chase: Thibault Heimburger’s Paper on the Maillard Reaction Hypothesis. It wouldn’t take any he suspects a bug. I tried to post it for him and it wouldn’t take; I have no idea why.
“I was quoting Rogers conclusions and asking Thibault for more details concerning Rogers hypothesis (presumably given in a long SSG message) as he suggested,” he writes.
So here it is:
Some years ago, Rogers wrote a very long SSG message to explain step by step his hypothesis and the many parameters. I will try to summarize this message later.
Online, we have only access to part of his book : A Chemist’s Perspective On The Shroud of Turin. Based on preliminary experiments he concluded :
1/When temperature is too high, convection cells are too active, and resolution is low. A body that had cooled would give better resolution than a hot body. I think Rogers first thought high body temperature was needed for two main reasons : vertical convection cells, and a temperature gradient on the shroud, making temperature the main parameter to explain high resolution since he thought reactive amines came from the lungs (and don’t forget he was a thermal analyst). Then he tested his hypothesis, came back on this idea, and admitted a lower body temperature would better suit high resolution. Anisotropic heat flow, may be a second order parameter.
2/The amine must be released slowly. Two much amines badly reduced resolution. Porosity – Adsorption properties of the shroud : a low flow of amines can diffuse through the cloth, a high flow of amines is blocked and flows along the cloth. This is consistent with a slow production of ammonia through hydrolysis of urea on the skin for hours (your article on the origin of the reactive amines).
3/The atmosphere must be cool and still. No external convection flows. Convection blurs the image.
4/An increase in the concentration of reducing saccharides improves resolution. It improves contrast. Indirectly, it allows a lower amount of reactive amines, thus a lower flow.
5/Modern linen that does not contain suitable impurities will not produce an image. According to his Maillard reaction hypothesis, that is an argument against the pcw as the chromophore. The question is, which other parameters are given in his SSG message ? Thank you,
The first point is very difficult to explain according to the laws of fluid mechanics and would also be in contradiction with point #3, which impliciltly involves a laminar flow of amines. The main difficulty with point #1 is that anisotropy of the flow must neccesarily be a first order effect if the mechanism is based upon vertical convection cells (again in laminar flow). The very reasonable model of vertical cells is also in contradiction with amines coming from the lungs and in the first place, following a path towards the face, hair and body and eventually adopting a vertical laminar flow regime to impact the cloth and react. It is a trajectory that according to what we know on the motion of fluids and gases is impossible.
If the compounds responsible for the maillard reaction were sweat the vertical convection cell model would sound more reasonable.
Ok, actually points 1 and 3 are in contradiction. Rogers drew conclusions out of his preliminary experiments even if it was in contradiction with his own hypothesis.
So far, I think any convection flow blurs the image. “High resolution” requires a cool and still atmosphere (and cooled body), there was no convection cells.
The origin of the amines should be on the skin (ammonia coming from slow hydrolysis of urea), the origin of the amines in the lung simply doesn’t fit the data. The cloth was laid on the body.
The suited model is not fluid mechanics (“low flow” is misleading, i meant no macroscopic flow) but models of diffusion (random migration of molecules) giving a probability
Even if I think it’s more realistic to estimate that the amines were coming from the skin (from maybe urea and other substances left there by the drying sweat or already present in the skin at the time of death), I don’t think it’s fair, in the present state of our knowledge to discard completely the possibility that amines could have come out also from the lungs and maybe from the other natural orifices of the corpse to take part in the image formation process…
I disagree. The image shows a connection between each point of the body and the image. A random migration of molecules in the frame of a isotropic flow based on Fick’s law would have never reacted with the resolution we see. One would expect a blurred image. In my view, a laminar flow of amines with a very low Reynolds number in small confined cells could be the only option because this would mean a quasi-vertical motion and could -perhaps- explain why each point of the body is connected to each point of the cloth and not to a probability distribution function on the cloth.
I don’t think we should take a vertical motion for granted. The intensity of the coloration on the shroud may be correlated to the shortest path between body and cloth.
Concerning convection cells : why would they be confined ? why would they be in a steady-state ? how could they fit high resolution (at then be totally asymetrical : long and narrow) ? why would confined convection cells between body and shroud create any contrast on the shroud ? do you think the temperature gradient between body and shroud could create any convection at all (if significant) ?
Any convection mouvement would alter a gradient of concentration depending on body distance, and result in a loss of information.
Rogers set the cornerstone of the image theory : Maillard reaction.
Reading parts of his books, you can see the origin of the reactive amines is just of component of the hypothesis, and Rogers had to found a candidate because Maillard reaction requires amines.
Rogers set the method.
And reading his conclusions and experiments you can see it can be translated to an origin of the amines on the skin. Actually chapter XI is on kinetics theory of gases, which applies once the amines “reached its target” on the skin, and then diffuse “in a cool and still atmosphere”.
All this would need much more experimental testing in order to really see clearly what’s good and what’s not… That’s all I say.
And that’s precisely why i’m asking for details to test step by step his hypothesis.
The (very long) “paper” (The many details and parameters of the Maillard reaction hypothesis- and related topics- by Rogers himself) is coming very soon.
Sorry for the delay.
Merci Thibault !
Thank you Thibault for this comprehensive description of Rogers hypothesis.
Actually this hypothesis requires many parameters, the value of each being important to get a final image. Part I, MAILLARD REACTION IN DETAIL :
The nature and thickness of the layer depends on the amount of wetting agent (S. officinalis) and the type of ground grains used to make crude starch.
The reactive amines should come from the skin. They could have concentrated from sweat or direct plasma exudation from the wounds. Reactive amines would slowly appear at the surface of the skin.
Rogers used DETA (diethylenetriamine) mw 103.2 in his experiments, and used it directly (no slow production or release), there was no convection, but you can see the borders of image are not straight, certainly due to a quick release of amines responsible for a flooding.
In your article, you suggested ammonia through hydrolysis of urea. But is hydrolysis of urea significant at ambient temperature ? Have you thought about glutamine ? glutamine is available in plasma and sweat, and in large amounts in muscle cells (~20 mmol/L). Under a stress and/or trauma there is an accelerated outward transport from muscle cells. Hydrolysis of glutamine is much faster than hydrolysis of urea at lower temperature.
There may be other amines, main ones should be determined before any experiment.
There may be reactive reacting through contact (glutamine), while other could diffuse (ammonia). And there may be different products, through different pathways, giving different coloration.
This is an “autocatalytic” type reaction, which increases contrast (the closer the darker) and resolution (lesser spread of gaseous amines).
How long is the “induction time” depending on the concentration of gaseous amines ? During this time, the rate will closely follow a zero-order rate law and contrast will be “diffusion controlled”.
This may explain partly why resolution seems higher on the face (more autocatalytic) than on other parts (more diffusion controlled).
“Extinction coefficient” is important but hardly evaluable.
5/Path-length dependent attenuation of the concentration
It is not simply due to a concentration gradient based on Kinetic Theory of Gases, we should take into account a complex absorbing boundary.
Absorbing boundary (cloth), whose strength depends on time, adsorption, absorption, depletion of reactant(s), thus the type of linen and weaving, thickness of the sugars layer, local level of completion.
The more the parameters, the lower the odds to get an image. But here it is.
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