Bob’s Beautiful Blue Glacier

Recently I had the fortune to visit the state of Alaska. While there, I took a boat trip around the Kenai Peninsula, where there are glaciers moving from the Harding Icefield toward the ocean. As our tour boat approached Holgate Glacier, I was awed by the immense size of this giant wall of ice, but I was even more surprised by the fact that the glacier is a mottled mat of white and absolutely gorgeous blue. Not a bright color, but a very distinct bluish-green, probably more accurately referred to as “cyan.”


CSN Director Bob Hamers in front of Holgate Glacier.  (photo by Bob Hamers)

Living in Wisconsin I’m used to snow and ice being white… sometimes dirty brown, and sometimes yellow(!). But never blue. I pondered this for some time as the boat drove around. What was causing this beautiful color? And why were some areas white and some areas blue?
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What’s in a Unit Anyway? Part 2: When is a Kilogram Not a Kilogram?

In my last post, I told you about how scientists measure amazingly cool things that can be vastly different in size, like elementary particles or very distant dwarf planets and their moons. Thinking about all the units to describe length got me thinking again (uh oh)… How do scientists know that the nanometer they measure at the Large Hadron Collider is the same as a nanometer on a spacecraft zipping past Pluto? Even though it seemed like it should be obvious, it turns out that defining a unit so that it’s the same for everyone isn’t all that straightforward.

Weights & Measures Office

The old Weights & Measures Office in London, England  (photo by Nico Hogg)

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What’s in a Unit Anyway? Part 1: From Protons to Galaxies

If you’re like me, you often find yourself thinking about random things. For example, just the other day I was thinking to myself, “what’s the diameter of a gold nanoparticle* in light years**?” Unit conversions have been a thorn in my side for as long as I can remember, so I was pleased to discover one of the coolest Google features ever: unit conversions! (Just when I thought Google had maximized my laziness…)


How big is a gold nanoparticle… in LIGHTYEARS?!? (image adapted from Pixabay)

So, with Google’s help, we can figure out the diameter of a gold nanoparticle in light years. We’ll assume our gold nanoparticle is 10 nanometers in diameter (similar in size to many of the nanoparticles we use in the Center for Sustainable Nanotechnology – check out some previous Sustainable Nano posts to learn more). All you have to do is type the following into your Google search bar: “10 nanometers in light years” – go ahead, I’ll wait.

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Thus Spake Paracelsus*

The Swiss Renaissance physician, alchemist and founder of toxicology Philippus Aureolus Theophrastus Bombastus (!) von Hohenheim, better known as Paracelsus (Figure 1), said it well: “All substances are poisons; there is none that is not a poison. The right dose differentiates a poison and a remedy.” Or more compactly, “the dose makes the poison.”


Figure 1. Portrait of Paracelsus (contemplating poisons?)   (image from Wikimedia)

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How can you calculate how many atoms are in a nanoparticle?

Two years ago, I wrote a blog post called Two Ways to Make Nanoparticles, describing the difference between top-down and bottom-up methods for making nanoparticles. In the post I commented, “we can estimate, knowing how gold atoms pack into crystals, that there are about 2000 gold atoms in one 4 nm diameter gold nanoparticle.” Recently, a Sustainable Nano reader wrote in to ask about how this calculation is done. It’s a great question!

In order to estimate how many atoms are in a gold nanoparticle, we have to talk a little about crystal structure. Crystals form when atoms (or molecules) arrange themselves in an ordered way in three dimensions. The smallest unit of that structure is called a unit cell. The example below shows a simple cubic structure where there is one atom at each corner of a cube, and the cubes stack together to make the crystal structure.

cubic crystal

A simple cubic crystal built from 27 unit cells. (image by Miriam Krause)

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Fluorescence is Awesome: New CSN Videos!

Fluorescence is a favorite topic here at Sustainable Nano – we’ve written about quantum dotsfluorescein in the Chicago River, glowing bacteria, and many other topics, but one of our most popular blog posts of all time is about how highlighters and blacklights work.

Well, now our colleagues at ACS Reactions have made two amazing new videos inspired by that post! The first one is all about highlighters and fluorescence, including some cool nanotechnology applications; the second is a how-to guide for making flowers glow under blacklight.



Update July 27: Our video was featured on Gizmodo! Regarding their headline, though, it’s important to note that highlighters glow under UV light, not in the dark🙂