Saturday, March 3, 2018

Why Bridges Move... (and more thermal expansion demos)

I wouldn't want to get my hands caught between those jaws on a hot day.

I don't know that I would actually show this video in class. The demonstrations of thermal expansion aren't all that impressive. The explanation and theory is solid, but the demos could be a little more impressive.

Like these, for example...

Monday, February 5, 2018

TRANSPARENT Solar Panels?!

We can maybe back off with the question mark-exclamation point ending on the title, folks.

I'll take 'not 100% transparent' any day of the week if it means that we can turn our windows into solar panels. That would be outstanding.

I am a little curious, though, about just how 'not 100% transparent' they would be. The whole <640 nm thing would be around red/orange, and their explanation that longer wavelengths would travel right on through seems odd. Longer than red/orange doesn't leave a whole lot of colors because the rest of the colors are shorter wavelengths than red/orange.

Thursday, January 25, 2018

Turning air into plastic?

I remember the 'Anything Into Oil' claims. The article was first posted in 2006, and I thought our environmental concerns were solved.

It has, of course, been eleven years now since that first article, and we're still throwing away trash and pumping oil out of the ground - at increasingly desperate cost to our environment.

So, in the spirit of  'extraordinary claims require extraordinary evidence', I'm not going to hold my breath until the airplastic comes to a store near me and gets the full scientific exploration that it deserves.

And as much as the science of this video from Thuderf00t seems sound, I don't know his bonafides either.

All that being said, the concept of sequestering carbon from the air to make the plastics that we're already using is pretty outstanding. I'm skeptically hopeful.

Monday, January 8, 2018

Why Roman Concrete Still Stands Strong While Modern Version Decays

Concrete, strong stuff...

But apparently Roman concrete is among the strongest stuff, and it just got stronger while it was under seawater.
Previous work had revealed lime particles within the cores that surprisingly contained the mineral aluminous tobermorite – a rare substance that is hard to make.

The mineral, said Jackson, formed early in the history of the concrete, as the lime, seawater and volcanic ash of the mortar reacted together in a way that generated heat.

But now Jackson and the team have made another discovery. “I went back to the concrete and found abundant tobermorite growing through the fabric of the concrete, often in association with phillipsite [another mineral],” she said.

She said this revealed another process that was also at play. Over time, seawater that seeped through the concrete dissolved the volcanic crystals and glasses, with aluminous tobermorite and phillipsite crystallising in their place.

These minerals, say the authors, helped to reinforce the concrete, preventing cracks from growing, with structures becoming stronger over time as the minerals grew.
And it looks like the Romans knew what they were doing.
As the authors note, the Romans were aware of the virtues of their concrete, with Pliny the Elder waxing lyrical in his Natural History that it is “impregnable to the waves and every day stronger”.
If you want to read more, check out the original research article...or the Guardian article that's way more readable and that I quoted up above.

Sunday, December 31, 2017

Costa Rica's Turquoise River - A Natural Optical Illusion

That blue water doesn't look too natural to me.

I mean it's a gorgeous blue, but it's a blue that doesn't seem quite right.

Apparently - at least according to this article - there's no copper in the water, so that's not what it's blue.

Instead, the Rio Celeste produces particulates of aluimosilicate of exactly the right size to reflect light in the blue area of the spectrum. Neither tributary contains particles of the right size, but...
[t]here was only one puzzle left to solve, though. If Rio Buena Vista also had an abundance of aluminosilicate, how come its water looked completely transparent, while Rio Celeste appeared to be turquoise? It turned out to be a matter of particle size. Upon analyzing samples from both bodies of water, scientists realized that aluminosilicate particles in Rio Buena Vista measured 184 nanometers (nm), while those in Rio Celeste were much larger at 566 nm

“This increase in size is what causes the scattering of sunlight, such that it occurs principally in the blue region of the visible spectrum. So that’s why we have that spectacular light blue color of the Rio Celeste” said Dr. Max Chavarría Vargas, who lead the scientific investigation into the turquoise waters of Rio Celeste. “It’s one of those quirks of nature where one of the rivers provides mineral material with one size and the other river provides the acidic environment so that those particles grow.”
Who knew that particulate size mattered?

Monday, December 18, 2017

Brad Makes a Knife with Bob Kramer | It's Alive | Bon Appétit

I'm a fan of goofy Brad, the host of the video series, It's Alive. Mostly the show is about cooking in the realm of fermented foods (kombucha, beer, garlic honey, cultured butter, sauerkraut, etc), but this time Brad goes to a small-scale knife shop because, as he says at about 13:10, "this ain't necessarily alive, but it's got energy...watching [the knife-making process] from start to finish, if it don't make you feel alive, I can't help you.

There are a bunch of metal topics covered here...
  • 0:45 - "make some steel from scratch"...they make their steel from powdered ingredients (carbon, iron, manganese) and then melt them together
  • 1:30 - induction heat melting of the steel ingredients
  • 2:20 (and again at 3:00) - forging...the take the fresh, steel 'biscuit', reheat it 
  • 2:45 - heating the steel back up to the plastic state...they don't mention the phase transition from BCC to FCC, but they do explain that hot steel can change it shape more easily...and that they have to reheat the 'biscuit' because it's getting cold
  • 3:30 - rolling mill...a small mill but still far larger than what we show in the summer workshop
  • 4:15 - forge welding different steels together...they only refer to the steels as steel A and steel mention of high- or low-carbon steels
  • 4:40 - iron oxide...the captions explain that, "[t]hose dark flakes are iron oxide. High temperatures accelerate the oxidation process."
  • 6:20 - "quench tank there, Vinnie"...Vinnie is the camera man for all the Bon Appétit explanation yet as to why you would quench something
  • 6:58 - hardening the knife...molten salt bath for an oxygen-free atmosphere for heating..."dissolving the carbon into the iron" then capturing it during the quench...followed by a tempering bath to, "bring the knife to a working hardness, so it's not too hard...not too brittle"..."when it's hardened, it's under a lot of STRESS...we go in there (the tempering bath) and it just adds some heat, kind of massages it...makes the knife 'happy'...yeah, this is the 'martini' for the knife"...there's a decent graphic summary of this at 7:50
  • 8:40 - acid etching the knife..."the acid eats these layers at a different rate...because we mixed in different things in the steel"
  • 11:20 - nothing curricular, but watching Bob Kramer put a blade on the knife just by eye as stunning...I assume it took a few more passes than what the video shows, but he makes it look so casual and awesome...I'm amazed
  • 7:35 - mention of making the steel happy via a 'martini'
  • 10:20 - there's a bleeped, "I always f*#^ that up"
Brad's a goof, but it's loads of fun to watch him make a knife.

Tuesday, November 28, 2017

Prop: Shop - How to Make a Vacuum Forming Machine

This might be a little beyond my skill set at this point, but with the shift of material science from a semester to a full year, this might be in the future.

Gonna need myself a little suctioned viking head.