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The FDA recently chose not to impose new regulations on bisphenol-A, which has sometimes been used in food packaging. Let’s look at what bisphenol-A is, how it’s used to make materials, and why it can be harmful if people ingest it. Bisphenol-A is shown above. Like many chemicals, its name can tell you how it looks: 

• Bis (two)
• phenol (the red circle on the left: a benzene ring attached to an OH)
• A (acetone, where the 3 carbons in the middle come from)

So bisphenol-A is made by reacting 2 parts phenol with one part acetone. These are all common chemicals that don’t cost a lot, so bisphenol-A isn’t too expensive to make.

What makes it useful is the OH on each side. This makes it like a building block that can attach to something on each side. In other words, it can do something in two places or is bi-functional. 

Building blocks that can attach on both sides can be used to make long chains. And polycarbonate (sometimes called Lexan) is a long molecular chain mostly made of bisphenol-A. Many things, like jet canopies, are made of polycarbonate. Unfortunately it’s also been used in food containers. We’ll talk about that next.

alchymista:

A diffraction image of a protein crystal, which is created by using a particle accelerator to irradiate the protein with X-rays. This technique enables scientists to see internal structures of complex protein molecules such as enzymes. (via)

Here’s a fine example of science using X-ray diffraction. This pattern is created by interference at certain angles of X-rays bouncing off the atoms in the protein. And from this, you can figure out the arrangement of the atoms.

The “particle accelerator” here is probably a synchrotron light source, where the scientists travelled to do the experiment.

(via fyeahchemistry)

A synchrotron light source is a giant scientific facility made to generate X-rays. We wondered what X-rays could be useful for. It turns out they have just the right wavelength to figure out the location of atoms in a solid material.

X-rays with their wavelengths lined up strike the sample material at some angle, and they get bounced off elastically by the electrons in the atoms. Then you detect the bounced off X-rays at the same angle.

At some special angles, X-rays bouncing off different atoms will overlap, but their wavelengths might not line up anymore. You Clear Scientists know that overlapping light waves interfere with each other. And from this interference, you can use geometry to figure out the atomic spacing (5 nm in this example).

mdt:

Handmade particle accelerator unveiled at Milan Design Week, Higgs-Boson a no-show http://engt.co/I523GW

It shouldn’t surprise any of you Clear Scientists if it’s possible to make a small, handmade particle accelerator. In fact the first cyclotron, built by Lawrence and Livingston in 1931, was just 4.5 inches in diameter. It applied a voltage of 1800 volts to accelerate particles to 80,000 electron-volts. (This was the trick: How do you keep from needing 80,000 volts?)

This first, small cyclotron was the predecessor to the big synchrotrons we’ve been talking about lately.

Any idea how this handmade particle accelerator would work? We’re not sure yet, just taking a glance.

What we mean by “synchrotron” is actually a synchrotron light source, but you hear people use both words for it. It’s a particle accelerator used to produce electromagnetic radiation (“light”) such as X-rays. This light is very bright, and is useful to do experiments.

The National Synchrotron Light Source (NSLS) is pictured, where electrons are accelerated to 2.8 GeV (giga electron volts, which is a high energy). The electrons lose energy and give off photons, and these photons are pulled off in beamlines, which go off at tangents from the ring.

The larger ring at NSLS has a circumference of 170 meters. The largest synchrotron light source in the USA is 1104 meters: the Advanced Photon Source (APS) at Argonne National Lab, near Chicago. 

The Clear Science staff has been busy with science lately. We just returned from Brookhaven National Lab in Upton, New York. There we were doing X-Ray experiments at the NSLS or National Synchrotron Light Source (marked as 10 above). Around Brookhaven you just call that the light source. So if you get on a shuttle bus, you tell the driver “light source, please.”

Photo from the Brookhaven National Laboratory Flickr page:

1. Relativistic Heavy Ion Collider (RHIC)
2. Alternating Gradient Synchrotron (AGS)
3. AGS Booster
4. Linear Accelerator (LINAC)
5. Tandem to Booster Line 
6. Radiation Therapy Facility
7. Medical Research Reactor (closed)
8. Scanning Transmission Electron Microscope (STEM)
9. Center for Functional Nanomaterials (CFN)
10. National Synchrotron Light Source (NSLS)
11. High Flux Beam Reactor (closed)
12. Tandem Van de Graaff and Cyclotron
13. Graphite Research Reactor (closed)

We mentioned storing electricity in a battery. A battery stores energy electrochemically, meaning that electrons are “stored” in a chemical with high energy. Any chemistry that involves electrons as reactants and products is electrochemistry. A fuel cell is similar to a battery: both have two electrodes (anode and cathode) and an electrolyte.

There is more than one way to distinguish a battery and a fuel cell:

1. Batteries store their chemicals inside the battery, while fuel cells are fed from outside. 
2. Fuel cells often involve catalysis, while batteries may not.
3. Fuel cells operate continuously. Batteries operate in a batch manner, i.e. charge/discharge.

There’s a dinner party tonight so the Clear Science staff is testing the kitchen equipment. Have a good weekend, Clear Scientists!

A current (simplified) view of the electrical grid shows that the demand for electricity and the amount of electricity generated must essentially match. This is done by ramping power plants up and down as people change how much electricity they want.

Solar power and wind power are not easy to regulate. But we want to be able to make them a large part of the grid, since they’re green. One way to do this is add electrical storage to the grid, which is like being able to put electricity in a box and save it for later. During periods of low demand you fill up the storage and then use it during high demand. A charged battery is an example of “stored” electricity.