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(Haaretz)   Epidemics are looming because we pop antibiotics like they were farking candy   (haaretz.com) divider line 3
    More: Scary, towers, epidemics  
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616 clicks; posted to Geek » on 02 May 2014 at 10:41 AM (20 weeks ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2014-05-02 11:34:03 AM
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Please note: I do not have a PhD *yet* (8 months out! .. I hope. And fear.), and it is a large field. Anyways!

Currently there are two methods of mass-producing nanoscale structures (that is, combinations of nanoparticles/things more complex than a simple shape):
One method is called "Top down", which is lithographically making them. This is sort-of like whittling with a laser or acids (not exactly). It's akin to how we make semiconductor chips. This has limits on both the size scale, and the types of structures you can make.
The other method is called "Bottom up", or "Self assembly". This is reacting nanoparticles together chemically, to make more complex structures-but this, too, has its issues. Currently, there tends to be a high degree of disorder. Say we just want to make a simple barbell shape: Two spheres sticking to the ends of a nanorod, like this:  o-o. We try to mass produce that chemically, and in the solution we might get oo, ------, o-o-o, ||, |o, and, yes, a few o-o-'s: But there's no good way to *FILTER* on that scale.
The problem is that nanoscale objects are *inherently unstable* in solution: Bulk matter has a lower energy state. To keep things from just aggregating and crashing out of solution, you need to either A) Coat them with something charged, so they stay away from each other, or B) Coat them with the nanoscale equivalent of Teflon.
But now you've made it so it's hard to *react* them! So you have to do fancy chemistry dances.

We are currently in the.. the best way I can describe it I "Stone-age" level of nanotech. "Sharp rock, AXE! Smooth rock, SHOVEL! Round rock, HAMMER."  We are very, *very* good at making specific nanoparticles, like spheres, Rods, CUBES,(Which still seems like farking witchraft), etc, and putting them to various uses.  And we are still finding new uses for these shapes! I just saw a talk where someone at our school was doing preliminary research into making surfaces (like, say, on a medical device) less hospitable to bacteria. Not by using antibiotics, or even nanoscale silver: Just by changing the surface topology. If you cover the surface with simply polystyrene (plastic) spheres of a certain size, it becomes much, much harder for (a specific) bacteria to stick and thrive. Some can still adhere here and there, but there's not *enough* of them to form a 'colony', which is what tends to make people ill and spread bacteria further through the body. Just by coating a surface in nanoscale spheres. He is currently expanding to other bacteria.

Another use is gold nanospheres, with their fantastic optical properties, but I will get to that in another post.

And we're making progress on the bottom-up front, too: I'm working with my advisor on a way of optically-directing chemical self-assembly.

I'll try to post more later!
2014-05-02 10:53:54 AM
1 votes:
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2014-05-02 09:42:19 AM
1 votes:
Obvious tag is on vacation in Madagascar and plans to remain there until the crisis passes.
 
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