Hi everybody,I need a information, Why the crab chitosan has reflects(blue,pink).
thank's
Hi everybody,I need a information, Why the crab chitosan has reflects(blue,pink).
thank's
It's similar in concept to how butterfly wings get their colors - not pigments, but multiple layers of slightly varying dielectric constants at spacings on the order of half the wavelengths of the colors desired.
Every time light runs into an interface between two media with slightly different dielectric coefficients, part of the light reflects at that interface (proportional to the differences in the two dielectrics). When the interfaces are at half-wavelength spacings of one color of light, the reflections all constructively reinforce each other at that one color of light.
Chitosan in crabs is grown in layers, so you get colors from their reflections.
Every time light runs into an interface between two media with slightly different dielectric coefficients, part of the light reflects at that interface (proportional to the differences in the two dielectrics). When the interfaces are at half-wavelength spacings of one color of light, the reflections all constructively reinforce each other at that one color of light.
Chitosan in crabs is grown in layers, so you get colors from their reflections.
I think you mean the refractive indices of the layers are slightly different because they have different alignments, not dielectric constants...
QUOTE (Granouille+Sep 7 2009, 06:48 PM)
I think you mean the refractive indices of the layers are slightly different because they have different alignments, not dielectric constants...
What he said.
http://www.livescience.com/animals/051117_wings_led.html
All the goodies that we have and marvel at have already been created by time, happenstance and the interacting forces of our most wonderful Universe.
Wow, that's heavy.
What he said.
http://www.livescience.com/animals/051117_wings_led.html
All the goodies that we have and marvel at have already been created by time, happenstance and the interacting forces of our most wonderful Universe.
Wow, that's heavy.
Anybody here remember the relationship between dielectric constants and indices of refraction? There's a magnetic term equivalent to the dielectric constant, and I don't think there's a significant magnetic aspect to chitosan, so what's true about dielectric constants is true about indices of refraction.
And it's the alternating layers' half-wavelength periodicity that make them reflect at a specific color.
Aside from miracles of nature, we make these multilayer reflective/antireflective coatings for optics, especially useful with high power lasers.
Sorry about the confusion, I usually speak in terms of index of refraction when I discuss this topic.
And it's the alternating layers' half-wavelength periodicity that make them reflect at a specific color.
Aside from miracles of nature, we make these multilayer reflective/antireflective coatings for optics, especially useful with high power lasers.
Sorry about the confusion, I usually speak in terms of index of refraction when I discuss this topic.
You've misunderstood the practice of coating particles of magnetic materials with chitosan to make them less biologically active.
QUOTE
You've misunderstood the practice of coating particles of magnetic materials with chitosan to make them less biologically active.
Not exactly. To be precise, I've never *heard* of the practice of coating magnetic materials with chitosan for any reason.
Would you have a link for this? I'd be very interested.
Sorry -- I may have misread your post.
Chitosan is interesting and by attaching magnetic particles to it, chitosan particles may be recovered from suspensions.
http://www.iop.org/EJ/article/0957-4484/18...7_40_405102.pdf
Chitosan is interesting and by attaching magnetic particles to it, chitosan particles may be recovered from suspensions.
http://www.iop.org/EJ/article/0957-4484/18...7_40_405102.pdf
No problem. Some of my best ideas come from mistaking something somebody said. Magnetic chitosan particles might end up being a cure for cancer, who knows?
Except I routinely kick people off for claiming to cure cancer as cancer is not a single disease.
First, you should consider switching to decaf.
Second, how many diseases has penicillin cured? (Cancer could well be multiple diseases, yet have a single cure.)
Second, how many diseases has penicillin cured? (Cancer could well be multiple diseases, yet have a single cure.)
QUOTE (wcelliott+Sep 12 2009, 11:39 AM)
First, you should consider switching to decaf.
Second, how many diseases has penicillin cured? (Cancer could well be multiple diseases, yet have a single cure.)
If you knew the first thing about cancer, you would know that it's not.
Second, how many diseases has penicillin cured? (Cancer could well be multiple diseases, yet have a single cure.)
If you knew the first thing about cancer, you would know that it's not.
I would say that penicillin cures no diseases per se -- it kills off a large class of disease causing agents. That it does so is result of an arms race between Eukaryotes and Prokaryotes which has been going on for perhaps 500 million years. Once the disease agent is removed, the body's pre-existing self-repair mechanisms are often able to fix things.
This also explains why penicillin solves less medical problems than it did -- the peculiar vulnerabilities of certain Prokaryotes to penicillin can be fixed in more than one way by mutation, and the wide-scale use of penicillin causes inadvertent selection for those mutant strains.
Cancer and prion disease are not in the same class. Cancer cells are host cells which no longer respond to the all the signals for cooperation which all multi-cellular life has. They have become less specialized. And as the human body has perhaps hundreds of cell types, the ways that cancers can become less specialized also numbers in the hundreds. Then, as effectively freely reproducing cells within a host, they multiply and mutate. Some cancers have diverged so far from their original state that they are now infectious agents or amoeboid. Prions, being rearrangements of the body's own proteins cannot be so easily removed from the host.
So when people advocate cancer cure-alls, such is my state of knowledge than I ban them as harmful.
This also explains why penicillin solves less medical problems than it did -- the peculiar vulnerabilities of certain Prokaryotes to penicillin can be fixed in more than one way by mutation, and the wide-scale use of penicillin causes inadvertent selection for those mutant strains.
Cancer and prion disease are not in the same class. Cancer cells are host cells which no longer respond to the all the signals for cooperation which all multi-cellular life has. They have become less specialized. And as the human body has perhaps hundreds of cell types, the ways that cancers can become less specialized also numbers in the hundreds. Then, as effectively freely reproducing cells within a host, they multiply and mutate. Some cancers have diverged so far from their original state that they are now infectious agents or amoeboid. Prions, being rearrangements of the body's own proteins cannot be so easily removed from the host.
So when people advocate cancer cure-alls, such is my state of knowledge than I ban them as harmful.
QUOTE (rpenner+Sep 11 2009, 02:56 AM)
Except I routinely kick people off for claiming to cure cancer as cancer is not a single disease.
You KNOW that cancer is not a single disease !
What is meant by "not a single disease" -
is it meant that there are more than one fundamental cause of cancer ?
I do not think that there is evidence for coming up with such a statement.
Whether people should be routinely kicked off is Your decision - it is a fairly safe procedure - in the light of the unlikeliness that a person in this Forum should come up with a general cure for cancer - personally I favor the principle of benefit of doubt.
You KNOW that cancer is not a single disease !
What is meant by "not a single disease" -
is it meant that there are more than one fundamental cause of cancer ?
I do not think that there is evidence for coming up with such a statement.
Whether people should be routinely kicked off is Your decision - it is a fairly safe procedure - in the light of the unlikeliness that a person in this Forum should come up with a general cure for cancer - personally I favor the principle of benefit of doubt.
QUOTE (bukh+Sep 12 2009, 06:50 PM)
is it meant that there are more than one fundamental cause of cancer ?
There is more than one cause and more than one type. A cure for pancreatic cancer probably won't work for brain cancer. Cancer's strength is its ability to be virtually indistinguishable from normal cells at the cellular level. Since cancer is the result of a whole range of random cellular mutation, every cancer is different. Most infection treatments hinge on the fact that germs have to reproduce, and do so in a way different than human cells.
Modern cancer treatments rely on the shotgun approach; target the general location of the cancer cells and target them with destructive chemicals/radiation. The side effect is that many if not more healthy cells are damaged in the process.
Anyone claiming to have a cure for cancer that isn't actively doing research is an idiot. It is like trying to dig a hole by running around and flapping your arms. Retarded AND pointless.
There is more than one cause and more than one type. A cure for pancreatic cancer probably won't work for brain cancer. Cancer's strength is its ability to be virtually indistinguishable from normal cells at the cellular level. Since cancer is the result of a whole range of random cellular mutation, every cancer is different. Most infection treatments hinge on the fact that germs have to reproduce, and do so in a way different than human cells.
Modern cancer treatments rely on the shotgun approach; target the general location of the cancer cells and target them with destructive chemicals/radiation. The side effect is that many if not more healthy cells are damaged in the process.
Anyone claiming to have a cure for cancer that isn't actively doing research is an idiot. It is like trying to dig a hole by running around and flapping your arms. Retarded AND pointless.
Has it occurred to anyone else besides me that this topic's original question was answered several posts back, and that all this BS about cancer cures is pointless and retarded?
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