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Alan Turing's Chemistry Hypothesis Turned Into a Desalination Filter (arstechnica.com)
An anonymous reader quotes a report from Ars Technica: Alan Turing is rightly famed for his contributions to computer science. But one of his key concepts -- an autonomous system that can generate complex behavior from a few simple rules -- also has applications in unexpected places, like animal behavior. One area where Turing himself applied the concept is in chemistry, and he published a paper describing how a single chemical reaction could create complex patterns like stripes if certain conditions are met. It took us decades to figure out how to actually implement Turing's ideas about chemistry, but we've managed to create a number of reactions that display the behaviors he described. And now, a team of Chinese researchers has figured out how to use them to make something practical: a highly efficient desalination membrane.
To make this a true Turing-style system, the researchers dissolved a large molecule in water. This had the effect of making the water more viscous, which slowed the diffusion of the activator. In addition, the molecule was chosen so that the activator would stick to it, slowing things down even further. The end result was a system similar to the ones defined over a half-century ago. Imaging of the features show that rather than simply thickening the membrane, the membrane retained the same width in these areas; instead, it bulged out to form the structures. That's critical, as the amount of surface area exposed to a salt solution should influence how much water gets through the membrane. In fact, the researchers confirmed that more water was purified when the new membranes were used (the version with the stripes outperformed the dotted one). Unfortunately, the researchers don't compare this system to commercially available membranes. The report has been published in the journal Science.
To make this a true Turing-style system, the researchers dissolved a large molecule in water. This had the effect of making the water more viscous, which slowed the diffusion of the activator. In addition, the molecule was chosen so that the activator would stick to it, slowing things down even further. The end result was a system similar to the ones defined over a half-century ago. Imaging of the features show that rather than simply thickening the membrane, the membrane retained the same width in these areas; instead, it bulged out to form the structures. That's critical, as the amount of surface area exposed to a salt solution should influence how much water gets through the membrane. In fact, the researchers confirmed that more water was purified when the new membranes were used (the version with the stripes outperformed the dotted one). Unfortunately, the researchers don't compare this system to commercially available membranes. The report has been published in the journal Science.
the researchers dissolved a large molecule in water
Just one? Was this a study of homeopathy?
Hey, I wonder if someone who actually understood what they were reading could redo this summary so humans can interpret it? Maybe somebody with a tiny bit of technical background, who knows even generally what these guys are up to. That would be nice.
I am a geek attorney, but not your geek attorney unless you've already retained me. This is not legal advice.
"...how a single chemical reaction could create complex patterns like stripes if certain conditions are met."
This describes a random number generator: a single seed, from which a long string of seed-like numbers are generated by an algorithm. With the right type of algorithm, stripes are created in the pattern of output, because certain RNG algorithms are flawed in the way they create patterns.
Think of the RNG as a chain of chemical reactions starting from a single chemical reaction.
As in the effect of brownian motion, seeds are generated by the RNG all over the pattern's n-dimensional space in a seemingly random fashion, but in fact, holes are created in the resulting pattern, from which stripes emerge.
Quite a few years ago I wrote an article about Turing's Reaction-Diffusion system on Dr.Dobbs Journal.
it is still available online for anyone interested:
http://www.drdobbs.com/cpp/algorithm-alley/184410024?queryText=Rafael%2BCollantes
http://www.drdobbs.com/windows/letters/184410223
I'm afraid if you're looking for sympathy on the costs of running your cruising yacht ... you're not going to get it.
Getting poor people access to clean water is great, but I'm afraid the yacht set and their worries I just can't muster up giving a damn about.
During the Industrial Revolution, patents were only national in scope. It was normal for everyone to "steal" patented inventions from other countries... so normal it was pretty common to copy patented inventions from your own country too. The system couldn't keep up with the sheer volume of infringement.
Of course today we have large and formidable law firms that specialize in international IP law. We have databases and search engines that make it feasible to run a patent troll firm on a shoestring.
During the Cultural Revolution (1966-1976), China attempted to industrialize with things like back yard steel mills operated by collectives of people with no actual expertise in metallurgy. It's the kind of thing only an armchair philosopher could think feasible. From there, China took the proven path from near-medieval conditions to industrial supremacy: copying ideas. And since they're a sovereign nation, there's nothing anyone outside can do to stop them. You can only persuade.
One difference between China and the US in the early 21st Century is that China is still governed with its national interests paramount across the board. China's sole aim has been to increase its national economic power and prestige, and it's been highly successful. The US, on the other hand, while remaining firmly nationalistic in military affairs, has adopted a kind of internationalism as the establishment political position in economic affairs. In simple terms, it could be stated this way: what's economically best for nations collectively is economically best for the US. And, in fact, if you don't look too closely, that's worked out pretty well too.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
They get no rejection of monovalents. This is a nanofilter.
But the fluxes are crazy high.