[by:www.51voa.com] [00:00.00]¸ü¶àÌýÁ¦Çë·ÃÎÊ51VOA.COM [00:05.28]Blowdrying. Curling. Straightening. [00:09.64]Heat has been used to control hair for hundreds of years. [00:15.84]But how much is too much? [00:19.08]If you've ever opened a very hot oven, [00:23.44]you know that heat can burn your eyebrows off your face very quickly. [00:29.72]A scientist from Purdue University in Indiana [00:35.32]is trying to find a scientific answer [00:39.56]on how hot is too hot when it comes to your hair. [00:46.08]Many women and some men are very particular about their hair. [00:52.40]Some people who have naturally curly hair prefer to have it straightened. [00:59.08]Others with straight hair want to have curls. [01:04.32]Tahira Reid is one of those people. [01:08.44]As an African-American woman, [01:11.24]she is familiar with the challenges of maintaining curly, coil or tightly curled hair. [01:20.32]Putting her mechanical engineering training to work, [01:24.88]Tahira Reid and other researchers at Purdue University [01:30.84]are studying how heat treatment interacts [01:35.08]with different types of hair and how to prevent damage. [01:40.00]"It is kind of like the way I see the world, [01:42.96]like the lens through which I see the world and I always was wondering about [01:47.64]how we can think about this from a mechanical engineering perspective." [01:51.80]Hair irons can take many shapes [01:55.20]but are essentially clips or rods with heated surfaces. [02:00.56]Amy Marconnet is assistant professor of mechanical engineering. [02:07.60]She says the team is seeing how heat and temperature relates to their research. [02:15.28]"If you go to the mall right now you [02:17.44]see a whole aisle full of straightening irons, and they have terms like [02:21.80]ion technology and tourmaline." [02:25.84]In a Purdue University lab, [02:28.84]team members designed a hair straightener tool -- [02:33.44]a flat iron with ceramic plates and temperature control. [02:39.32]They attached it to a robotic arm that moved over pieces of hair. [02:46.08]They monitored the temperature while the device straightened hair. [02:52.64]What did they find? [02:54.72]Their study found that the heat weakens or breaks a protein called keratin, [03:02.36]responsible for the hair's shape, and temporarily changes it. [03:08.42]But nobody knows exactly at what level the heat [03:13.40]can actually cause permanent damage. [03:16.80]Again, Tahira Reid. "If we understand the onset at which [03:22.24]that happens then we might [03:24.24]be able to intervene before or give some [03:27.24]suggestions before you get to that point." [03:31.04]Researchers say early results are a bit inconclusive. [03:37.68]It turns out that everyone's hair is different [03:42.44]and that there's no exact temperature [03:45.64]where hair straightening becomes hair damage. [03:49.80]For example, people with naturally curly hair [03:54.16]can suffer more damage from heat irons than those with straight hair. [04:00.36]Ms. Reid says they will continue their research [04:05.08]in the hopes of finding what works best without damaging the hair. [04:11.00]I'm Marsha James.