Diet sodas must be bad: They have a warning label!

My wife and I joined some friends for dinner tonight. It wasn't anything fancy - just pizza and some soda - but it was enjoyable nonetheless. During dinner our host started talking about the "dangers" of diet soda. I kept my mouth shut, not wanting to go on a Tim Minchin-esque Storm rant (warning: NSFW language), but eventually knowing I was a chemist I was asked to give an opinion on the nasty chemicals.

I quickly explained that aspartame was perfectly safe. I have wanted to write an article on it several times but frankly it's not interesting enough to hold my own attention. It's been studied for a long time and has been found to be safe for consumption. End of story.

"But what about the warning label?" the host replied

"What warning label? I don't know about a warning label." 

"Ya, every diet soda has to have a warning label because of how bad they are for you."

Luckily I have spent more time reading about aspartame than I care to, so after a few moments I realized what label she was talking about. I quickly explained the warning to her as I will to you:

 

No, this is not the label I'm talking about!



That's not it either.

No, the warning I'm talking about is much more simple. Here it is:

That's it. The only warning is: "Phenylketonurics: Contains Phenylalanine". What does this warning mean? Well, to tell you the truth if I have to explain what this warning means then it doesn't apply to you. 

You see, there is a specific genetic defect, called phenylketonuria, which (in short) messes with your liver and makes it impossible to correctly digest phenylalanine, a common amino acid. Phenylalaine is an essential amino acid that is used by your body to synthesize dopamine, a necessary neurotransmitter. An excess of phenylalanine, like you would see in phenylketonuria, can lead to serious problems including mental retardation and death. Phenylketonurics (those that suffer from phenylketonuria) must live on a diet that restricts intake of phenylalanine. Therefore, the warning is placed on diet sodas. 

But some would argue that if it's really bad for some people we should all avoid it. If the warning that diet soda contains phenylalanine prompts you to avoid phenylalanine, here's a list of other foods you should also avoid, as they also contain phenylalanine (and some in much higher doses):

• Fish
• Bacon (Nooo!!!!)
• Beef
• Chicken
• Milk
• Cheese
• Walnuts
• Almonds
• Peanuts
• Beans
• Lentils
• Crab
• Oysters
• Soy products

And this is by no means a comprehensive list. My point is this: Yes, there is a warning on diet sodas, but it's not because they will give you cancer, and the warning probably doesn't even apply to you. So go on, drink up. You know you want that Diet Coke.

Mr. Clean's Magic Eraser and the chemical that's not a chemical

Today on Reddit I saw a post in Today I Learned that claimed that:

"Magic eraser cleaning products do not use any chemicals to clean hard-to-remove marks, but instead act as extremely fine sandpaper."

Okay...

There's the argument that every chemist wants to make right now, and many of you are screaming it at your screen already - Everything is a chemcial - but as I said during our recent discussion on chemophobia, that argument is weak and makes chemists sound like they're being dismissive of the actual concern. But this isn't a case of chemophobia. The claims states that magic eraser "does not use any chemicals", but in reality the chemical it does contain is the entire reason it's so cool.

The Mr. Clean Magic Eraser is actually a  formaldehyde-melamine-sodium bisulfite copolymer, also called melamine foam. It's a very hard polymer, which is what makes it so good at it's cleaning job. Here's how melamine foam looks under a microscope:

Image from this blog post. Unknown original source.

The claim that it works like sandpaper is entirely true. Since melamine is such a hard polymer it easily scratches off most stains. This is also why you don't want to use it on any glossy surfaces - you'll scrape off the gloss coating. If you've ever used melamine foam you've probably been amazed at how well it removes tough stains. Melamine foam is a chemical, and it's just one more way that chemistry makes your life better.

BONUS INTERESTING FACTS:

• Proctor and Gamble filed a patent on marketing melamine foam. That's right - a patent on marketing the foam. Basically, the patent is take melamine foam (which was already a well known cleaning product), put Mr. Clean's face on the front, and sell it to Americans. It's a very odd patent to read through, especially knowing that there's not a novel idea in the whole patent.
• If you love Magic Erasers, don't bother paying the high price to see Mr. Clean's face. Just buy formaldehyde-melamine-sodium bisulfite copolymer foam in bulk. Instead of paying $1.50 per scrubbing pad you can get them for about 29 cents each. You're welcome.

TCW Discussion series: How is science funded?

Tonight, May 15th, at 6:30 MDT I'll be hosting another episode of The Collapsed Wavefunction discussion series. We'll be answering the question "How is science funded?"

Update, this discussion will now be held on May 29th.  We were moments from starting when the fire alarm went off in the chemistry building. I'm currently waiting outside as the fire department investigates. Thanks for showing up, and sorry to my guests for the technical difficulties!

Joining me is Andrew from Behind NMR Lines, Chemjobber, Sam (resident devil's advocate), David Dearden (my research advisor), and Matt Asplund (a member of my PhD committee).

You can watch the streaming video right here, starting just after 6:30 MDT.

If you have any thoughts please add them in the comment section or Tweet #TCWDiscuss.

Links related to the discussion:

• My original post about Lamar Smith's bill: http://www.thecollapsedwavefunction.com/2013/04/what-lamar-smith-doesnt-understand.html
• A post by Phil Plait about Canada's new approach to research: http://www.slate.com/blogs/bad_astronomy/2013/05/13/canada_and_science_nrc_will_now_only_do_science_that_promotes_economic_gain.html?utm_source=tw&utm_medium=sm&utm_campaign=button_toolbar

Malaria infection changes mosquito behavior

Published today in PLOS one is an interesting article about how malaria changes the behavior of infected mosquitoes. The researchers showed that mosquitoes infected with malaria were more attracted to human odor than those that were not infected.

The experimenters wore nylon socks to collect their foot odor (a clean nylon sock was used for a control). Then for a period of three minutes they counted how many mosquitoes preferred to land below the (stinky) nylon sock instead of the clean one. It wouldn't seem surprising to me that the mosquitoes preferred to land by the smelly nylon sock - after all that sock smelled like food. What is interesting is that mosquitoes landed by the smelly nylon sock much more often after they were infected with malaria. The implications are obvious - malaria infected mosquitoes are more attracted to us than mosquitoes that aren't infected.

Figure 1 in the mentioned article. Notice that infected mosquitoes land significantly more often than uninfected mosquitoes

Specifically, these researchers were looking at the Anopheles gambiae. Past research (which is cited incorrectly in the article) has already shown that An. gambiae infected with malaria eat more frequently and for a longer time than those not infected. This study is another evidence that the malaria parasite is able to control the actions of it's host. The researchers point out the advantages of this mechanism - if an infected mosquito is attracted to a host the parasite can be transmitted more effectively.

This isn't the first example of so-called "mind controlling" parasites. Dicrocoelium dendriticum is a parasite that affects the behavior of ants. Ants infected with Dicrocoelium dendriticum will climb to the top of a blade of grass and wait in the hot sun to be eaten by grazing cattle - the next step in the parasite's life cycle. This current study does not prove that malaria has this extent of mind control over the mosquitoes, but it is interesting that infection with malaria changes a mosquito's behavior in the favor of the parasite. The authors mention that more research is required, specifically they are now investigating the behavior as a function of the parasite's life cycle (will a mosquito be more attracted to human odor after the parasite reaches it's transmissible stage?) Current studies of malaria transmission often use uninfected mosquitoes or computer models based on behavior of uninfected mosquitoes, which may be inadequate, given this new research.



  Renate C. Smallegange, Geert-Jan van Gemert, Marga van de Vegte-Bolmer, Salvador Gezan, Willem Takken, Robert W. Sauerwein, & James G. Logan (2013). Malaria Infected Mosquitoes Express Enhanced Attraction to Human Odor PLOS ONE DOI: http://dx.plos.org/10.1371/journal.pone.0063602

How to draw atomic orbitals

I've been teaching general chemistry concepts for several years now. For some reason the idea of atomic orbitals is hard for students to grasp. Tonight I'm holding an exam review for my students and I thought I'd prepare by writing about the quantum numbers and how they affect the shape of atomic orbitals.

The Quantum Numbers

n: The principal quantum number. n can be any positive integer (1,2,3,4...)

l: The angular momentum quantum number. l can equal: 0,1,2,3,4...(n-1)

When we write the angular quantum number we will often use the notation:

0 = s
1 = p
2 = d
3 = f

There are two other quantum numbers, but we aren't concerned with those for this exercise.

Nodes
In quantum mechanics a node is a point where an electron cannot exist. The shape of any orbital is defined by the nodes. There are two types of nodes: angular and radial.

Angular: An atomic orbital will have l angular nodes. So, an s-orbital has 0 a p-orbital has 1, and so on.
Radial: Each atomic orbital will have n-l-1 radial nodes. So a 3p orbital has 3-1-1 = 1 radial node.

Drawing orbitals
Ok, so what you've read above is explained in just about every general chemistry textbook. But, when asked to draw orbitals most chemists just pull from memory. You don't need to do that, though. You don't have to memorize the shape of a single atomic orbital. You just need to know understand the quantum numbers. Let's start with 1s.

1s
Angular nodes: 0
Radial nodes: 0

This is the easiest. We'll always start with a circle. There are zero nodes and so we're already done. We'll say that 1s looks like this:

And sure enough, the 1s orbital looks like we predicted. Here's the 1s orbital:

But now let's move on.

2s

Angular nodes: 0

Radial nodes: 1

We start again with a circle, but we draw one smaller circle within the larger circle.

We erase everything in that node and this is now our prediction for what a 2s orbital will look like.

And sure enough, our prediction is pretty close. Here's the real 2s orbital:

Moving on...

2p
Angular nodes: 1
Radial nodes: 0

We start with the same circle, but this time we need to add an angular node.

When we erase that section we are left with our prediction for a 2p orbital...

 Which, once you smooth the edges looks just like the actual 2p orbital:

 Let's do the 3d orbital now

3d
Angular nodes: 2
Radial nodes: 0

Following the same process we have marked two angles through the center of the circle. When we erase that area we're left with our prediction for a 3d orbital:

Which, after we smooth out the edges, is a pretty good prediction:

Let's do one more (because I'm not quite sick of this yet)

3p

Angular nodes: 1

Radial nodes: 1

We start with an angular node...

But, once we erase that are we're left we still have to include the radial node...

So now let's just erase that area, and we'll be left with our prediction:

Which again, once we smooth out the edges, looks pretty close to the actual 3p orbital:

 The great thing about drawing the atomic orbitals this way is you never have to memorize any of these shapes - they come directly from understanding what the quantum numbers mean.

Now, if you're one of my students, get back to studying.

Notes

All of the "real" atomic orbitals from above were created using Orbital Viewer, a very cool (and free) program.

Commander Hadfield returns home a hero

At approximately 10:30 ET tonight, Commander Hadfield will set foot on the earth for the first time in 146 days. In those 146 days Hadfield has grown an extensive Twitter following, answered questions on Reddit, shared some amazing videos, posted thousands of pictures, and now he's released this awesome cover of David Bowie's "Space Oddity":

For someone like me, that has been following Hadfield very closely, the video is pretty emotional. Hadfield's effort in science outreach is commendable and, perhaps, irreplaceable. I'm a chemist, but I can be honest with myself: Space is cool. Space increases the public's interest in science. It sparks discussion among lawmakers. Children and adults can appreciate how awesome space is, and it's great that Commander Hadfield saw his opportunity to make a difference and took it. His tweets, pictures, and videos have brought science to the public in a unique way. 

In one of his final tweets from the ISS, Hadfield shared this picture:

Along with the words

"Spaceflight finale: To some this may look like a sunset. But it's a new dawn."

Which has powerful implications. Commander Hadfield is coming home, and we could look at that as the sunset on the pictures we've come to expect from the space station. A sunset on videos showing us what it looks like when cry or wring out a washcloth in space. Or, we could look at it as a new dawn. Commander Hadfield has injected new excitement into science outreach, a bolus of interest we can now build on.

So, Commander Hadfield, thank you!!

Living with Chemicals: Sodium lauryl sulfate

The Chemical (IUPAC): Sodium lauryl sulfate (SLS)
You probably know it as: Soap
The structure:

Ok, so it's actually an oversimplification to call this one compound "soap", but this long chain molecule is an ingredient you'll probably find in just about every cleaning product you own. Soap, from a chemical perspective, is the product of a saponification reaction - a reaction between fat and a strong base (usually sodium hydroxide). The soap making scenes in Fight Club, including the chemical burn, are surprisingly accurate for movie science (though I wouldn't exactly recommend working with their starting materials).

SLS is used as an engine degreaser, shampoo, floor cleaner, a moderately effective shark repellent, and car wash soap. Believe it or not, it's also found in your toothpaste. You may not realize it, but your toothpaste is basically just a tastier, thicker version of your shampoo (I'll bet you didn't realize you were brushing your teeth with shampoo, did you). SLS is also the reason that orange juice tastes so horrible after you've brushed your teeth (probably because of it's surfactant properties).

So the same chemical that is used as an engine degreaser can be used as a shark repellent and is also found in your toothpaste. You'll often hear the argument that chemical X is bad for you because it is also used in product Y, but a chemical isn't bad because it's also found in a different product, even if that product would be bad for you. As another example, polysorbate 60 is used in many processed foods as well as in sexual lubricants. It's an easy argument to say you shouldn't eat foods that contain polysorbate 60 because you're basically eating KY Jelly, but it's not a good argument. Chemicals can have a wide variety of applications - your toothpaste is proof of that.