Thursday, October 30, 2008
Wired's "What's Inside"
I love the Wired "What's Inside" series. Very informative. Today they covered Ultra-Strength Bengay.
Friday, October 24, 2008
X-ray sticky tape
A new way to make sticky tape see-through
When you peel sticky tape in the dark, you can see tiny sparks. This is a process called Triboluminescence. The same thing happens when you smash sugar crystals (for instance, by chewing). Materials scientists lack a consensus but the current theory is that after the bonds are broken, electrons hurry back to their atom of interest. Once they get back, the energy they had while zooming is released as a photon, which can be in the X-ray region of the spectrum!
When you peel sticky tape in the dark, you can see tiny sparks. This is a process called Triboluminescence. The same thing happens when you smash sugar crystals (for instance, by chewing). Materials scientists lack a consensus but the current theory is that after the bonds are broken, electrons hurry back to their atom of interest. Once they get back, the energy they had while zooming is released as a photon, which can be in the X-ray region of the spectrum!
AP: a machine peeled ordinary Scotch tape off a roll in a vacuum chamber at about 1.2 inches per second. Rapid pulses of X-rays, each about a billionth of a second long, emerged from very close to where the tape was coming off the roll.
That's where electrons jumped from the roll to the sticky underside of the tape that was being pulled away, a journey of about two-thousandths of an inch, Escobar said. When those electrons struck the sticky side they slowed down, and that slowing made them emit X-rays.
Reuters: Carlos Camara of University of California, Los Angeles and colleagues used a motorized peeling machine to unwind a roll of tape in a vacuum.
They generated enough X-rays to show the bones inside their fingers.
"The tape has to be in the vacuum. Your hand can be outside," Camara said in a telephone interview on Thursday.
"If you unroll the tape on your office desk in ambient conditions you only get visible light. You don't get X-rays," he added. This is because gases in the air slow down the electrons that produce the X-rays.
Wednesday, October 22, 2008
isopropyl alcohol
Wiki says that rubbing alcohol can refer to ethyl alcohol (ethanol - booze) or isopropyl alcohol.
Isopropyl alcohol is represented by the chemical formula C3H8O. It's good for dissolving oils (fingerprints, smudges on connectors, sticky stuff, I imagine poison ivy as well)
The vapor pressure is higher than water (at 24° C = 75.2° F it is 40 mmHg compared to 22 mmHg). An interesting note is that in general, a lower boiling point corresponds to a higher vapor pressure; this is consistent with the of 82.3° C, lower than water at 100° C
The vapor is heavier than air. It's also quite flammable; the flash point is a mere 12° C. Since the vapor is what burns, you can light something on fire and the flame doesn't actually touch the object. If you soak a cotton ball in it, it will catch on fire but the cotton ball will be fine. Many videos on youtube show people lighting their hand on fire, since their hand isn't actually burning, though I must warn you that you should never play with fire.
It is less dense than water at 0.786 g/cm³, so it settles on top of the water.
70% is better than higher concentrations at killing things, because the increased amount of water aids in the transport across the cell membrane, where the alcohol denatures the proteins necessary for bacterial metabolism. The water must be permitted to evaporate. Other things make better disinfectants.
Isopropyl alcohol is represented by the chemical formula C3H8O. It's good for dissolving oils (fingerprints, smudges on connectors, sticky stuff, I imagine poison ivy as well)
The vapor pressure is higher than water (at 24° C = 75.2° F it is 40 mmHg compared to 22 mmHg). An interesting note is that in general, a lower boiling point corresponds to a higher vapor pressure; this is consistent with the of 82.3° C, lower than water at 100° C
The vapor is heavier than air. It's also quite flammable; the flash point is a mere 12° C. Since the vapor is what burns, you can light something on fire and the flame doesn't actually touch the object. If you soak a cotton ball in it, it will catch on fire but the cotton ball will be fine. Many videos on youtube show people lighting their hand on fire, since their hand isn't actually burning, though I must warn you that you should never play with fire.
It is less dense than water at 0.786 g/cm³, so it settles on top of the water.
70% is better than higher concentrations at killing things, because the increased amount of water aids in the transport across the cell membrane, where the alcohol denatures the proteins necessary for bacterial metabolism. The water must be permitted to evaporate. Other things make better disinfectants.
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