what is the SPF of hair?

September 23, 2008 at 5:28 pm | | crazy figure contest, literature, science@home

Hair provides about SPF 10 UV protection to the head. At least according to this recent paper: Parisi, et alSolar Ultraviolet Protection Provided by Human Head Hair. Photochem. Photobiol. 2008. The intersting thing is that long hair provide about the same or even less UV protection than short hair. The authors posit that this could be because long hair is more likely to part and expose the scalp.

Oh, that’s how they did it.

more HHO

August 8, 2008 at 10:46 am | | pseudoscience, science and the public, science@home, stupid technology, wild web

We just love writing about water hoaxes at EDS (here and here). And what about running your car on water?

On the big truck that is the internets, there are several kits for splitting water from electricity from the car’s battery and burning the H2 and O2 gases with gasoline (e.g. Water4Gas). The idea is as follows:

  1. harness any wasted electricity from the alternator (or use a solar panel)
  2. use that electricity to splitting water into H2 and O2
  3. pipe the gases into the air inlet of the internal-combustion engine
  4. by burning the H2 and O2, you produce water and some energy
  5. allegedly, the hydrogen and oxygen gases also make the gasoline combustion more efficient by somehow optimizing the air/fuel mixture
  6. the combination of (4) and (5) increase your car’s MPG 

So does it work?

Well, the thermodynamics of the scheme is simple: it is impossible to generate more energy by creating water (by burning hydrogen and oxygen) than it took to split the water in the first place. So it is ridiculous to take energy from the engine to split water and burn water. But it is possible to harness external energy (i.e. via solar cells or by taking “extra” electricity from the alternator, if there is any) and convert it to chemical—then mechanical—energy. So, conceivably, you could increase your MPG by converting solar or “excess” electrical energy to hydrogen and oxygen gases, then burning them.

And then the kinetics. Fluid dynamics is very complex, and there’s no way I can guess how different gasses will affect the way the air/fuel mixture flows and explodes. I am very skeptical of the idea that the air/fuel mixture in modern internal-combustion engines is dramatically inefficient, and that throwing in a little hydrogen and oxygen gases to the mixture fixes the problem. That said, the densities of H2 and O2 gases are different than that of air, so it is conceivable that adding these molecules to the combustion mixture changes the efficiency with which the engine burns gasoline. But I would guess that those changes would be for the worse (based on Murphy’s law).

So, although I am very very doubtful that Water4Gas could work in principle, the only way to really be sure would be to test this. (That is, before Big Oil and Detroit kill all the inventors and bury their breakthrough!) But I can’t find a site that gives any real evidence of one of these “HHO” devices working. The closest to an honest test I have found is this—and these guys never saw an increase in MPG, even after a lot of tweaking!

HHO for fuel has all the warning signs of bogus science. Seriously. All of them. For instance, there is tons of marketing; such as the fake debunking sites that actually tell you to buy the product in the end: “water4gas scam revealed.” Googling will give you many more hits like this. Smart marketing!

I think Water4Gas and other HHO fuels are bunk with a lot of misleading marketing. What they’re really selling is a huge confusing book, a glass Ball jar, and a lot of tubing.


I would love to see a comparison between a well-tuned car and a well-tuned car with an “HHO” thingie. I bet there’d be no change in MPG. Anyone want to test on their car?


July 3, 2008 at 12:52 pm | | everyday science, great finds, science@home, tutorial

I’m on vacation with my financier fiancée for a week in South Carolina: a few days at our friends’ wedding, a few days at Hilton Head, and a few days with my soon-to-be in-laws. The weather has been beautiful: heat and humidity reminding of my UNC days. The shark that swam past me gave me the creeps, but otherwise Hilton Head was perfect.

One strange event: a friend got a sunburn and a strange rash. The dermatologist asked if she had been making Mojitos or drinking Coronas. Huh? Diagnosis: Phytophotodermatitis. This is really cool: limes (and various other plants) contain furocoumarins (particularly psoralen, structure below), coumarin-type chromophores that absorb strongly in the UV.

Psoralens act as photosensitizers: absorbing UV light and releasing reactive triplets or radicals. With fluorescence quantum yields only around 1-2%, psoralens transition to the triplet state (via El-Sayed’s rule, I expect, from the Jablonski diagram below) and phosphoresce strongly. Chromophores stuck in their triplet state can return to the singlet ground state by coupling with triplet O2, producing a highly reactive singlet O2 species. This may be one mechanism of the photosensitizing properties of psoralens. Alternatively, a psoralen molecule in its triplet state can react directly with DNA or other biomolecules with electron-donating capability. Various other photosensitizing reactions are discussed in an interesting review (Kitamura, N.; Kohtani, S.; Nakagaki, R. J. Photochem. Photobiol. C 2005, 6, 168-185).

So, basically, my friend was spraying tan accelerator on her skin, then sitting in the sun for hours! That equals strangely shaped splotches of sunburn. In fact, psoralens have been used in photochemotherapy (also called PUVA) for certain skin ailments, such as eczema and psoriasis. So be careful squeezing limes on the beach, or picking parsnips or playing with celery in the sun.

Check out some doctory stories in this article: Weber, I. C.; Davis, C. P.; Greeson, D. M. J. Emer. Med. 1999, 17, 235-237.

Gaming for Science: Fold.it goes public!

May 9, 2008 at 11:47 am | | science and the public, science@home, software, wild web

I just saw a remarkable take on an age-old problem: Protein Folding. David Baker at the University of Washington converted the problem of protein folding into an interactive game that we can play. Check it out at Fold.it (currently beeing /. to death)

Details about the science are sparse, but my undestanding is that they’re trying to train us like a neural network of sorts- first we learn to fold known protein structures, and then the group will release new “puzzles” of unknown or unreleased structures and see how the the borg collective does against other folding projects .

Oh yea, I made an “Everyday Scientists”mebeli group! Can’t wait to play when I get home

youtube: coupled pendulums

April 25, 2008 at 9:20 am | | science@home, wild web

Man, it’s so easy to get hooked watching YouTube sciencey videos. I liked this coupled-pentulums (or is it pendula?) video:

But then I found coupled magnetic pendulums! Even cooler:

Now you can go get trapped in YouTube.

more burning water

April 2, 2008 at 10:58 am | | literature, pseudoscience, science and the public, science@home, stupid technology

We here at EDS always love a good ol’ combustible-water story. I don’t know if you remember a while back, but there was a great YouTube video about running boats and cars on salt water. All you need is salt water (oh, and a huge RF energy source).

Now they’ve published a paper about the burning salt water: Roy, R.; Rao, M. L.; Kanzius, J. Mat. Res. Innov. 2008, 12, 3. There are some “real” scientists who wrote this: Rustum Roy is an emeritus professor at Penn State! But why Roy chose to publish in MRI, his own journal that uses “super peer review” (if you’ve been published in a peer-review journal, you can publish in MRI), is the big mystery: if he wanted people to take this seriously, why didn’t they publish in a peer-reviewed journal?


Go Figure. I’m not really sure what we’re supposed to see here. There’s no discussion in the paper, just a claim that the figure demonstrates a change in the water structure. But it’s just an intensity change!

And there’s this great footnote on the first page of the paper:

It was perhaps this distortion [by the media] that may have misled Philip Ball … in his rather unwarranted critique in Nature (published online Sept. 14, 2007.) No claims have ever been made by Kanzius of getting out more energy than was put in, etc. He only reported a unexpected observation, a forgotten art in modern laboratory practice, which could be pursued for a variety of possible applications. His observations, fortunately for science, unfortunately for his ‘unscientific’critics who did not delve into the facts first, as in normal science, appear to be correct.

Man, go watch the YouTube video and then try to take this guy seriously. A reasonable scientist would have denounced the media analysis, not the skepicism of the scientific community.

And, unfortunately for Kanzius and Roy, this “unexpected” result has been published before: Roychowdhury et al. Plasma Chem. Plasma Process. 1982, 2, 157. In 1982, this paper reports using the same frequency to split water, producing H2O2 + H2. Of course, Roy et al. fail to cite this in their “scienfitific” paper on the Kanzius effect.

Here are links to Phillip Ball’s excellent original analysis of the claim and his response to the recent paper. And here’s a C&EN article about it.

great science fairs

February 27, 2008 at 8:31 am | | science and the public, science@home, teaching

Some great science fair projects here:


Runner-up would be electroworms.

the physics of sailing

February 21, 2008 at 7:39 pm | | journal club, science@home

physics-today.jpgThe cover story of February’s issue of Physics Today, the publication of the American Institute of Physics, is the physics of sailing. I like sailing: grew up on the coast of Maine sailing Lasers—and eventually and Ensign—every summer. Obviously, I can’t afford to sail out here in San Francisco, but I get to go home every summer and sail in Casco Bay.

I thought the cover of Physics Today was a little cruel: “Hey you, in that dark laser lab, check out what these smart people are doing: Sailing!” But the article was actually pretty cool. The basic stuff was in there, and it even had equations (like Reynolds number). But really, I just looked at the figures.


This is a helpful one: you can go faster on a beam reach than when running downwind. If you don’t realize that a (modern) sailboat is wings on the water, going directly downwind is what you would intuitively want to do. And going upwind is mind-boggling.

But my favorite figure was this image of sailboats racing in the fog:


The beauty of vortices trailing off in the fog for thousands of feet was stunning. I also like that you can see that the third boat from the top is tacking and temporarily interrupting the trail. Cool.

Well, here’s a PDF of the article if you’re interested.

hot gum!

October 17, 2007 at 4:36 pm | | help me, open thread, science and the public, science@home

Who wants to help me?

Here’s an email my PI received. First of all, it’s pretty cute that some high-school student is emailing professors at Stanford for some help. Secondly, it’s even cuter that the profs actually read the email!


My name is [redacted] and I’m a highschool student who is currently doing an Honors Chemistry project. My idea that I’m experimenting with is that I’m going to try to determine if there is a temperature change or a chemical change that affects the feeling of the mouth when gum is chewed. I was actually doing quite well with my ideas, but now I’m kind of stuck, so I was wondering if somebody in the chemistry department could e-mail me back or possibly help me.

My idea that I was going with is that I wanted to first start out and (using a mouth thermometer) get a starting temperature of a person’s mouth before chewing gum. Then, I wanted to pick a brand of gum in both mint and cinnamon flavors and seperately measure if there is an increasing or decreasing temperature change. My hypothesis is that there will not be a significant change at all, so that’s where the chemistry part comes in. I wanted to then somehow test saliva samples or something with the different chemicals of gum to determine which ingredient creates the “feeling” that the mouth is hot or cold. Except I really have no idea how to go about doing that.

Do you think someone could give me some ideas within the next day or so and let me know/point me in the right direction on how I should go about doing this experiment? That would be amazing, thank you!

My first thought was to look at two flavors of the same brand of gum, find the ingredients that are different, buy those (food-grade) chemicals, and taste them! But most gums just list “natural and artificial flavoring” in the ingredients, so that wouldn’t work. Separating the different ingredients in the gum is a possibility, but probably too difficult.

Another option is to guess the flavors the manufacturers used for cinnamon and mint (an educated guess, but doing some research about flavorings). I bet they use menthol for the mint. I don’t know what they use for the spicy cinnamon, but I know that capsaicin is the chemical that makes chili peppers taste “hot” (by interfering with the pain receptors in your mouth). You could use capsaicin and menthol on saliva samples and measure changes in the temperature or whatever. These would be good estimates of the chemicals they use as flavoring in gum.

Other thoughts? Would there be a very simple way of separating the flavor ingredient without a column or TLC plates? Maybe a paper towel? Or maybe the student could just dissolve the gum in warm water and use the solution of all the ingredients.

But I don’t know what they would measure in the saliva sample (gross!) that could relate to taste.

fluorescein is green in rivers

June 20, 2007 at 9:23 am | | science@home

I was perusing Wikipedia the other day, when I read the article on fluorescein. The article claims that the molecule is often used as a dye for rivers. I had heard this, too. It makes sense, because fluorescein is generally considered nontoxic and it’s very fluorescent, so it would be a good marker.


But something puzzled me: why is the Chicago river green in the image? When I think fluorescein, I think “Absorbs at 487 nm and emits in the green (510 nm).” Fluorescein in water should look yellow. In fact, there is an image in the Wikipedia article of an eyedropper with a yellow fluorescein solution. And here’s a pic of my vial of fluorescein in water:


Sure looks yellow to me.

I mentioned my confusion to a friend. We concluded that they must dump a shit-load of fluorescein into the river to make it look green. He decided to test this by putting some fluorescein in water (I’m sure he’s not pouring that stuff down the drain!):


As you can clearly see, water looks green. And he didn’t even use very much dye (probably ~1 mg).

Here’s the point: when you look through the solution in a vial, it looks yellow because you’re seeing the transmission. When you look at the solution in a river (or a ice bucket) from above, you only see the fluorescence excited by sunlight. You can even see that it looks more yellow as he pours it out of the ice bucket (because then you can see some transmission as well as fluorescence).

Well, duh! Now, I feel silly for being confused: that was so obvious. I forgot that the quantum yield of fluorescein is nearly unity. Thanks, Wikipedia.

Science Fair

June 17, 2007 at 3:06 pm | | crazy figure contest, science and the public, science@home

Last weekend I had the pleasure of judging middle school science fair projects. It’s always refreshing to see the kids interested (or at least pretending to be interested) in science. There were a lot of great projects. It was also nice to have a coordinator that wanted us to find a winner, instead of the “everyone’s a winner” approach I’ve encountered judging at some other schools. In honour of their efforts, I’ve put together my own science fair project.

How do glasses relax? This is important because glasses are important for people with bad site to see good.

I think glasses will relax. I think this because if glasses didn’t relax, then we wouldn’t be able to see through them. But I’ve seen through a glass before, so it must have relaxed.

1) Paper
2) Pencil
3) Regeneratively amplified femtosecond Ti:Sapphire oscillator
4) Stopwatch
5) Notebook
6) Something to make things cold

1) I ask 5 friends, David, Melissa, Lindsay, Billy, and Rainbow if they thought glasses relax.
2) I wrote down what they said, and averaged the results.
3) Make a liquid supercold.
4) Shine a lazer through it, and see what comes out.
5) Analyze your results.

My independent variable was the number of people I asked. My dependent variable was if the glass relaxed.

These were my results.

As your can see, David, Melissa, and Rainbow all said that glasses relax, while Billy and Lindsay said glasses cannot relax. This confirms my hypothesis that glasses can relax, because more people think glasses can relax than glasses cannot relax.

My hypothesis was correct. If I could do this experiment again, I would see if playing different types of music would make the glasses relax faster. This experiment was important because it shows science works.

100 Great Science Fair Thesis Projects

offset your entropy footprint

January 2, 2007 at 10:31 am | | news, science and the public, science@home, stupid technology, wild web

You’ve probably heard of websites like CarbonCounter.com, where you can offset your personal carbon footprint to help prevent global warming. Well, I’ve created a site that will let you calculate and offset your entropy footprint in order to help prevent a more dangerous inevitability: the heat death of the universe!

Please help before it’s too late.

no internet and no wireless make sam something something

December 22, 2006 at 8:16 pm | | science@home, stupid technology, wild web

Go crazy? Don’t mind if I do!

I’m home in Maine visiting family (and friends) for the holidays. My parents, unfortunately, have … prepare yourself … DIAL-UP internet. In other words, there is no internet at my house. Which is partially why I haven’t written anything lately. (Another reason is that I’m lazy.)

So, in order to use (fast) internet, I go to local coffee shops and the town library. But after hours, I’ve found myself sitting in a cold car in the library parking lot—leeching off the wireless and desperately checking my email (all spam).

OK, I just wanted to make fun of myself. And perpetuate stereotypes about Maine.

geometry-conscious pigeons

November 27, 2006 at 1:16 am | | cool results, science@home

What is going on here? I woke up the last two mornings to look out the window only to see pigeons in queues in the field across the street:


This is strange. Upon closer inspection, it was revealed that they were eating along an old faded white line on the soccer field. I tried finding some mention of this phenomenon in The Google, but to no avail. The closest we found were blue jays eating house paint (here and here) and sparrows eating grit. Maybe this is the same thing: pigeons eating field chalk for grit or minerals. But they were only on one older faded line. Maybe the new lines are a different paint (to avoid this problem). Or maybe the field paint made some yummy type of grass grow there. Still unclear to me. Anyone else know what’s going on here?

< Previous PageNext Page >

Powered by WordPress, Theme Based on "Pool" by Borja Fernandez
Entries and comments feeds. Valid XHTML and CSS.