Can this sugar-based material replace single-use plastics? | All Science. No Fiction.

Sugar glass itself isn't the solution to single use plastics.

It's too brittle and too water soluble.

But it sounds like the composite of sugar glass (isomalt) and sawdust - particularly with a waterproof coating - might be a promising possibility.

St Louis Arch Final Construction and Thermal Expansion

I absolutely adore the St Louis arch - technically The Gateway Arch - and have been to the top at least a half dozen times. If I had my druthers, I would get to the top every time I'm in St Louis, but my wife and mother-in-law are less interested, so I merely admire it crossing the bridge each time we're in town.

One of our campers in Boise this summer explained that she had a lesson in her science class about the final topping-out ceremony of the arch, it being interesting because one side was in more direct sun. This lead to that sun side expanding more than the other, causing the two legs not to initially line up and the gap for the keystone to be too narrow if not for the hydraulic jacks installed to spread the legs apart.

Check out the details in the above video at 0:50 and in from the Arch's wikipedia article...

It was slated to be inserted at 10:00 a.m. local time but was done 30 minutes early because thermal expansion had constricted the 8.5-foot (2.6 m) gap at the top by 5 inches (13 cm). To mitigate this, workers used fire hoses to spray water on the surface of the south leg to cool it down and make it contract. The keystone was inserted in 13 minutes with only 6 inches (15 cm) remaining. For the next section, a hydraulic jack had to pry apart the legs six feet (1.8 m). The last section was left only 2.5 feet (0.76 m). By noon, the keystone was secured.

Brilliant, man. hose down the hot side with cold water. 

How cool is that?

I'm sorry...I know...it's a corny joke...but it was right there...I couldn't help myself...

Indestructible books

A month or so ago, my wife brought home an Indestructibles book. She'd picked it up from our local Target store as a baby shower gift for a coworker and said it was made of a neat material that didn't rip.

I asked if it was Tyvek, knowing that Tyvek is a rip-stop fabric. She, a successful Appalachian Trail thru-hiker knows Tyvek as a lightweight ground cloth, and she said she wasn't sure whether the books were Tyvek or not.

So off I went on an internet hunt...

On the Indesctructibles FAQ page, I found the following... 

What are Indestructibles made of that is so durable yet paperlike and delightful for my baby?  

Indestructibles are printed on a synthetic material made from flashspun high-density polyethylene fibers (getting technical here, we know). It feels like paper, but liquid water cannot pass through it and it is very difficult to tear.

Which then sent me to the wikipedia article on flashspun fabrics...

Flashspun fabric is a nonwoven fabric formed from fine fibrillation of a film by the rapid evaporation of solvent and subsequent bonding during extrusion. 

...and wikipedia links onward to 'see also' Tyvek...

Tyvek (/ˈtaɪ.vɛk/) is a brand of synthetic flashspun high-density polyethylene fibers. The name Tyvek is a registered trademark of the American multinational chemical company DuPont, which discovered and commercialized Tyvek in the late 1950s and early 1960s. 

 

Tyvek's properties—such as being difficult to tear but easily cut, and waterproof against liquids while allowing water vapor to penetrate—have led to it being used in a variety of applications.

See the parallels between the Tyvek entry on wikipedia and the Indestructibles description?

waterproof...liquid water cannot pass through it...

difficult to tear but easily cut...very difficult to tear...

flashspun high-density polyethylene fibers...flashspun high-density polyethylene fibers

The books might not be made from the branded Tyvek, but it sounds to me like they're made of a generic Tyvek.

I'm going to take that as a win.

The Story of Stuff

This video is from 2009, so some of the details are admittedly a little dated, but the overall concepts - that we need to reduce our usage of materials in spite of the business community's desire for us to increase our usage and many governments' business-friendly leanings - are as relevant today as they were fifteen years ago (as I type this, anyway).

The channel has continued to make videos, posting their most recent (as of me typing this on July 4th, 2024) one in June of 2024, and they have a website with information on how to get involved in their campaign to decrease materials usage - particularly plastics and materials that end up in landfills.

Facets of Glass Physics

From online pdf

I'm going to have to give this article a couple more read-throughs to get all the content in it.

The article - from Physics Today's January, 2016 issue - goes into peer-reviewed detail of the thermodynamics of glass's formation, methods of forming glasses, a defining glass as a specific state of matter. I know the science would blow the heads off of our Princeton matsci students and would likely push my AP chemistry students to their very edges of understanding, but I learned a lot in reading the article and will go back through it a few more times to get a little more out of it.

The full article is available as a pdf as published or without the fancy title page.

Why on Earth is Depleted Uranium Used for Military Ammunition?

Depleted uranium just sounds terrifying. Sure, you can pick up some uranium ore and yellowcake from United Nuclear, but trying to buy depleted uranium is going to likely be a little dodgier.

With that being said, the US military has used depleted uranium (DU) as a source of armor penetrating ammunition over the years. I thought - wrongly from the video above - that the DU was simply used because of its high density and nature otherwise as nuclear waste. Today's video posits that there are quite a few other advantages of DU in high-caliber munitions applications.

There are also some seemingly obvious health risks involved in living in an area where spent DU shells are peppering the ground or having been in a tank where DU rounds entered and as least slightly vaporized. The video also goes through those health risks and says that they have largely been disproven, though I would be skeptical and appreciate that many military branches are "not considering depleted uranium anymore because of the environmental problems associated with it, be [they] real or perceived."

I think I'll stick to good ol' tungsten for my armor piercing needs.

A glass that builds and heals itself

That looks a whole lot like solgels to me, but I'll admit that my knowledge of solgel chemistry is about twenty five years out of date and based on a single summer of research at Miami University (no, not University of Miami).

The video summarizes researchers' findings that amino acids can form glasses with an index of refraction close to that of silica glass, adhesive properties, and a natural inclination to form convex lens shapes...and that self heal themselves as they rehydrate themselves.