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Well, since that thread was locked I have to answer here instead. I don't think the technical part we were discussing was the reason for the lock.
W∴ Balboos, GHB wrote:
Interestingly - "fine mesh" - can be obtained in more than one way. A single thing sheet of very tightly woven material or many layers of less tightly woven material. The former (fine mesh) will react poorly to pressure increases and redirect to vent said pressure; the latter (if the coarser mesh doesn't get extreme) doesn't have the problem with pressure (by comparison) but does effective trapping of droplets as the wend through the contorted path between mouth and "outside", trapping droplets on the fibers during many collisions.
I thought you might find it interesting that those N95 (Actually N,R,P 95,99,100) masks we read about all the time nowadays are having much larger "mesh" than viruses.
They work by being made made from a nonwoven material with statically charged fibers, and particles are forced to make a lot of turns when following the air stream and are getting stuck on these statically charged fibers.
They also don't lose efficiency when being used a lot, they just get heavier to breathe through.
Basically an agreement. As for a mesh small enough to trap a virus? It would, for all practical purposes, be impermeable - at least in terms of breathing through it. Virus' are extraordinarily small.
When Louis Pasteur was trying to isolate the rabies virus he found it passed through his finest filters. Virus' are basically large molecular scale entities. Now one doesn't emit virus' on their own (such as during a cough or sneeze) but as content of the droplets - and even the smallest droplet can contain an unaccountably large number of virus' (of various types, concurrently).
Taken to the next smaller level - masks against poison gasses - far smaller than a virus. They rely upon adsorption (such as activated charcoal) and decomposition/reaction, such as (imaginary scenario) trapping chlorine gas with sodium carbonate (going to Nacl (salt) and CO2.
The thing is that to prevent outgoing (masks worn by the public) it may make more sense to target the droplets with (moisture) adsorbent surfaces (threads) in a comparatively free flowing but thick-enough matrix. Easier to get. Easier to wear for longer periods. Easier to clean/reuse. And I'd suspect, more effective.
Don't know, I'd refer to Erwin Schrödinger for this one.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
As far as I know you have a cat: why does it even enter your mind to pose the question?
Cats have long memories and don't even consider allowing having bad things done to them again.
After all they do have personnel to take care of them.
After the success of my first galaxies, the next night I headed out again, new target and tried longer exposures, and pretty much used up the camera battery on the one target taking around 60 x 120s exposures. After stacking them and rejecting some fuzzies, and then tweaking I ended up with what I thought was a reasonable outcome!
It never ceases to amaze me at the shear numbers involved in these objects. Millions of lights away, thousands of light years in diameter and containing billions of stars.
One of my pals pointed out that of one of the pictures I caught the first night, when the light photon journey started travelling away from the target, dinosaurs were still on the Earth. I had never really thought about it like that!