Why Do Your Ears Pop On An Airplane?

The human ear consists of the outer ear, your middle ear, and your inner ear which is fairly deep inside of your head. The middle ear is separated from the outer ear by the eardrum (or "tympanic membrane" in medical terms). So, the air trapped inside the middle ear doesn't come in contact with the air outside of your head. When you experience a change in air pressure by getting closer to or further from the ground, your ears will occasionally "pop" to adjust the pressure of the air that is caught in your middle ear so that it matches the air pressure outside of your head. This is done by quickly opening the Eustachian tubes (which connect the middle ear to the back of the nose) in order to let air rush in or out of the middle ear as needed.

The most common place for someone's ears to "pop" is on an airplane, but it can also happen with smaller changes in altitude (the height above the Earth's surface), like when you are driving up or down a mountain. The air closer to sea level is at a higher pressure since it is being compressed by the weight of all of the air above it. As you climb to higher and higher altitudes, the air pressure decreases.

Some people may find the popping of their ears to be annoying, but if your body didn't do this, then the pressure on one side of the eardrum would be higher than on the other side which could bend your eardrum slightly and compromise your hearing.

If your plane is taking off, then you are going to an area with lower pressure so the high-pressure air in your middle ear will push outwards on the eardrum. When your ears pop, air rushes out. If you are coming in for a landing, then you have low-pressure air in your head (from when you were at a high altitude) and high-pressure air outside pushing inwards on your eardrum. When your ears pop, air rushes in.

One way to make this pressure equalization more comfortable is to do it yourself by swallowing or yawning frequently rather than waiting for your ears to pop by themselves. These methods work because swallowing and yawning cause the Eustachian tubes to open briefly. This is why many people choose to chew gum when their plane is taking off or landing (chewing gum or sucking on a hard candy makes you swallow more than if your mouth were empty).

If someone has a blocked or oddly-shaped Eustachian tube, then their ear will fail to pop as their plane is landing. This creates a small vacuum in the middle ear. Fluid then rushes into the middle ear to increase the outward pressure until it equals the inward pressure from the surrounding high-pressure air.

Little Lion Experiment:

To see the effects of having a blocked Eustachian tube, obtain a small plastic cup and a bowl with a flat bottom. If possible, use a clear cup so the water will be easier to see. If you don't have a clear cup, then try adding food dye to the water in this experiment to it will be easier to see once it is inside of the cup. Fill the bowl with about an inch of water. Turn the empty plastic cup upside-down and squeeze it until it bends inwards. Place the bent cup in the water.

Being careful not to let the lip of the cup rise above the water level, slowly squeeze the creases in the cup outwards so that the cup returns to its original shape. By doing this, you are creating a small vacuum. So, the pressure inside the cup (which pushes outwards) is lower than the pressure outside of the cup (which pushes inwards), and this pressure difference is what pushes the water from the bowl into the cup until the two pressures are equalized.

As a side note, the same principles of air pressure explain how straws, turkey basters and a variety of other objects are able to move liquids against gravity.

How Can I Avoid Getting A Sunburn?

Have you ever forgotten to put on sunscreen, then regretted it the next day? Many of us know what sunburns look like, but do you know why we get them? Let's start with some background information on how our skin responds to light. Cells called melanocytes in the inner part of your skin produce the pigment melanin, which is what gives color to our skin. Believe it or not, we have about 1000 to over 2000 of these cells per square millimeter of skin! If you have dark skin, that means that your melanocytes are programmed to make a lot of melanin all the time. If you have lighter skin, then you have the same number of melanocytes, but they don't produce as much melanin. If you are albino, then your melanocytes cannot do their job because they are lacking an enzyme (a piece of cellular machinery) which is needed to make melanin.

On most days, we do not get exposed to enough sunlight to cause us to develop a suntan. However, a nice day spent at the beach is much different. The darker your skin is, the more light you can withstand without having to boost your melanin production. When your body senses that you need more melanin to protect you against harmful UV rays, your melanocytes kick into high gear and you get a suntan. However, if you stay outside for too long, especially without sunscreen, then your body can't make melanin fast enough to keep up with the amount of UV exposure. This is what causes a sunburn. A sunburn can be thought of as a "clean-up crew" of various blood cells being sent to repair the damaged area. This increased blood flow is what causes sunburns to appear red and feel warm to the touch. Starting to sound a bit like a sunburn? There's one thing missing: why does sunburned skin tend to peel? Your body does its best to repair the UV damage, but if the damage is too great, then the unrepaired cells will simply flake off to make room for new healthy cells to replace them, which allows the sunburn to heal.

You may have heard about the relationship between sunburns and skin cancer. Even though the "clean-up crew" and the skin cells themselves usually undo the harmful effects of UV, they may not always do a perfect job. This would allow damaged cells to stay in the skin. Most sunburns will not lead to cancer, but a tiny fraction of them can if they damage a cell's ability to stop dividing. This is why it is so important to wear sunscreen in order to avoid over-exposure to UV light.

There are two types of sunscreens: those that reflect UV light (like tiny mirrors) and those that absorb it like melanin does. Everyone gains extra protection from wearing sunscreen, but if you are fair-skinned or albino, it is especially important that you wear it. Remember to put it on around 30 minutes before you go outside so that it has time to stick to your skin. Otherwise, it will rub off on the grass or wash off in the water. [Safety note: some people (especially those with sensitive skin) have allergies to PABA, a chemical in some sunscreens. So if you have sensitive skin, you may want to consider buying a PABA-free sunscreen].

For more information, visit http://travel.howstuffworks.com/sunscreen.htm

Little Lion Experiment:

While UV light is harmful in some respects; we need it to stay healthy! This is because our bodies need about 10 to 15 minutes of daily UV exposure to make vitamin D. In fact, many reactions are activated by light (various kinds of light, not just UV). To see how important light is for living things to survive, obtain two small planter pots. Plant about 5 evenly-spaced seeds in each pot. If you cannot purchase seeds at your local hardware or gardening store, you could use seeds from a fresh tomato. Place one pot in front of a sunny window and place the other pot in a dark area (a cabinet would do, with your parents' permission). Remember to water the plants every few days (specific instructions can be found on the seed packet). Check on the plants over the next couple of weeks to compare the seedlings in the light versus those in the dark.

What Are Allergies

A-choo! Here comes another day of living with allergies. We are all familiar with the coughing and sneezing, but what exactly are allergies and what causes them?

Every day, our bodies are in constant contact with potential threats. These include pathogens (harmful microorganisms), pollution, and a host of other dangers. However, most of the time, we aren't even aware that anything nasty has entered our bodies. How are we able to combat these invaders so effectively? We have our immune system to thank. Immune cells called lymphocytes (pronounced lim-fo-sites) patrol all parts of the body looking for foreign molecules and microorganisms (tiny living things, like bacteria). Each lymphocyte is programmed to recognize a specific pathogen. Anything which is not part of our body is classified as "non-self" while every one of our own cells is termed "self." In short, the role of the immune system is to attack and destroy any cells it finds which are "non-self."

We also have sensors in our bodies which can detect the presence of harmful chemicals. Have you ever walked by a car and coughed or sneezed as you smelled the exhaust? This is because you have sensors in your nose, throat, and lungs that tell your brain that you have inhaled dangerous fumes, which you need to get rid of right away. So, your body sends the signal to cough and sneeze until you push out all of the fumes. This signal is sent by a chemical messenger called histamine.

If you have allergies, or know someone who does, then you might agree that the symptoms of allergies are kind of like a huge overreaction to the car fumes, except without the car! People with allergies react as if they have inhaled something toxic when in fact they have just inhaled normal everyday things like pollen and dust that are not harmful (these everyday substances are called allergens). This occurs because some of their lymphocytes are programmed to recognize the allergen as a harmful substance even though it is not. So, when the lymphocytes find an allergen floating around in your body, they trigger histamine to be released which causes the common allergic symptoms such as watery eyes, runny nose, sneezing and coughing (these are all ways to flush out the allergen). Histamine also triggers local swelling near the pathogen or allergen, and so it can cause narrowing of the airways (nose and throat) when you inhale pollen or dust in order to prevent more of the allergen from entering the lungs. Unfortunately, that makes it harder for the person to breathe (fun fact: histamine is also responsible for asthma - can you see the connection?).

So how can we treat allergies? The primary method to prevent allergic symptoms is to treat the person with antihistamines, which have been used since the 1930s to control allergies. The medicine does not affect the lymphocytes, but rather it just prevents histamine from triggering its bothersome symptoms.

Little Lion Experiment:

Obtain an empty toilet paper roll. Run water from your sink over the inner surface of the roll until it is wet but not soggy. Then, make 4 small piles (one of each) of the following: black pepper, confectioner's sugar, salt, and jimmies (sprinkles). Hold the tube sideways in one hand over the sink (so as not to make a mess). One at a time, put a pile in your hand, then carefully place it on the inside of the tube, then rotate the tube until it is coated with the substance. If the substance does not stick, then that is a pretty good indication that it is large enough that it would not stick to the lining of your nose or throat. If it sticks, then it is probably something that would get trapped in your airways if you were to inhale it. Slowly turn the tube until it is vertical. To simulate coughing, quickly shake the tube or bang it against the inside of your sink. See which kinds of substances come out the most easily. To simulate sneezing, blow air through the tube and see what comes out in your sink. The body also uses mucus in your airways to help carry foreign molecules out (like the sea carries shells to the shore). Pour a small amount of oil into the tube and see if it takes out some of the remaining particles

How Does Shampoo Work?

Have you ever wondered while rubbing shampoo into your hair how this colorful, sometimes clear soapy substance can clean hair?

Shampoo is made up of molecules such as ammonium lauryl sulfate that bond with the dirt and sweat on your hair. This bonding action helps shampoo clean your hair of dirt. Water helps by adding pressure to the shampoo-dirt components and rinsing these components out of your hair and down the drain.

Okay, so these shampoo molecules bond with dirt. How? Well, in the case of ammonium lauryl sulfate, the chemical detergent is similar to the dishwashing or laundry detergent used to wash dishes or clothes. Ammonium lauryl sulfate is a harsh chemical as it needs to bond aggressively with the dirt on your hair to clean it. Sodium laureth sulfate is also a detergent found in shampoos, but it is a little gentler to hair. Guar hydroxypropyltrimonium chloride is another type of chemical found in shampoos that adds volume and smoothes hair. This chemical helps make your hair easy to comb. Diethicone helps soften hair by coating the outer hair surface.

Shampoo is not just chemicals. It is actually 80 to 90% water. But, just using water won't really leave your hair clean, soft or comb-able. Rather, it is the 2 to 8% of detergents such as the chemicals listed above that really do the critical work of shampoo. The remaining 1% of shampoo is added fragrances or scents. The type of fragrance or scent your shampoo has really doesn't affect how clean your hair is, but it does affect the scent you smell when you are washing and brushing your hair.

So, shampoo helps clean hair; does it matter how much is used? The amount of shampoo should be about the size of a quarter. Anything less will not be enough to bond to all the dirt and sweat in your hair. Anything more is just wasting shampoo, water and your time. Too much shampoo can also leave your hair feeling dull as you wash away vital nutrients from your hair if you overwash it. Using a little more than a quarter may be necessary, though, if you were outside playing in a muddy creek.

One good way to tell if you are using too much shampoo is the amount of lather produced. Lather forms when the shampoo gathers around air instead of the oil from your hair. Dirt and oil actually destroy lather. If you have too much lather, you used too much shampoo. Remember, shampoo is to clean your hair, not the air.

Little Lion Experiment:

Materials:

• A piece of polystyrene clear plastic
• A soda straw to use as a dropper
• A little shampoo
• A centimeter ruler
• A toothpick, wire or some other small diameter "stick-like tool" that you can coat with shampoo

Steps:

1. Place your polystyrene sheet on a flat level surface where you can observe easily from the side and from the top.
2. Place some drops of water on the sheet using your straw. You can do this by sticking your straw into a glass of water, placing your index finger over the hole and pulling out the straw. When you loosen your index finger slightly, you can control the amount of water that you drop out. Make some big drops and some small ones.
3. Measure the diameters of the drops and looking from the side, sighting with your ruler, estimate their height. Finally, and again looking from the side, estimate the angle at which the water contacts the polystyrene. Why are these drops all circular? Make a plot of the height versus the diameter? What do you conclude? Make a plot of the contact angle versus the diameter. Again, what do you conclude?
4. Take your "tool" (no shampoo yet), and push it across and through a water drop (i.e. move it parallel to the polystyrene). Describe what happens. You may want to try it several times to check what things happen every time.
5. Dip your "tool" in your shampoo and shake off the excess (we do not want any big drops). Now push your "tool" into the edge of one of the water drops. What happens? Now push it across and through a drop. What happens? How is this different from what happened before you dipped it into the shampoo?

This experiment was described by the Science and Technology Center, University of Texas at Austin.

What Makes a Rainbow?

We have all seen beautiful rainbows across the sky after rain. But how does a rainbow form? Rainbows are usually formed when sky is full of clouds and it is about to rain. In order for a rainbow to form, we need two things, rain and sun.

When we look at sunlight most of us think of it as just one color: white, clear or blue. Sunlight is actually made up of all colors of light. All colors, which we see in rainbow, are originally there in sunlight. However, we do not see them in sunlight because they are mixed together. In the same way, if you take blue and yellow paint and mix them on paper you will see green paint. This green paint, as you know, contains both blue and yellow color; however, you only see green. Sunlight is the same way: when you mix all the colors of light together you get white light or sunlight.

Now that we know so much about light, let's look at what else make rainbows: rain. Rain comes from clouds. Clouds in the sky contain millions and millions of tiny raindrops. Rainbows are caused by the bending of sunlight as it passes through the raindrops. The raindrops act like miniature prisms. As white light enters the prism, it is separated into the individual colors of light. Both prisms and raindrops separate light based on the wavelength of the light. Light moves in waves, just like the waves in the ocean, and each color has a different length of wave. The longer the wavelength the slower the light color moves, purple is the fastest light and red is the slowest. The spectrum, or band of colors which make up the "white light" leaves the prism as separate bands of color. The more slowly a wavelength of light travels, the more it is bent by the prism. That is why the colors seen in the rainbow are always in the order red, orange, yellow, green, blue, indigo, and violet. The red light travels more slowly than violet light so it is bent more.

What Makes Soda Pop?

Pop, soda or soda-pop bubbles and fizzes because of the gas called carbon dioxide (di-ox-ide). Carbon dioxide is same gas that we breathe out (We breathe oxygen in). When soda-pop is made a whole lot of carbon dioxide is pushed into a pop can. The can is then sealed and pressure inside the can is created. The pressure inside the can is higher than the pressure outside the can. This is why the can will "pop" when you open it. The amount of carbon dioxide that the liquid soda-pop can hold depends on the temperature and pressure of the liquid. The amount of a gas that a liquid can hold is called the solubility (sol-u-bil-ity) of the gas. The "pop" at the opening is caused by carbon dioxide being released from the liquid soda-pop since the amount of gas the liquid soda-pop can hold is changed when the pressure is changed.

If you take a soda-pop right out of the refrigerator and open it up, less carbon dioxide will be given off than if you opened it after it was sitting in the sun for hours. If you lower the temperature of the soda-pop the solubility of the carbon dioxide is increased, so more gas will stay in the liquid soda-pop.

Little Lions Experiment:

1. See if the laws of solubility hold true. Take a can of soda-pop that has been in the freezer for an hour or two, until it is cold, but not frozen. Wash out a styrofoam cup and lid from a gas-station or a fast food place, take a straw and put it in the cup. Tape around the opening in the lid where the straw goes. Take a second straw and insert in the straw from the cup and tape any joints between the straws. Insert the far end of the straw in a clear glass with water in it. You want to try to prevent any gas from leaving the cup, other than what goes through the straw to the water. Take the styrofam cup and fill it with your soda-pop. Close the lid quickly to prevent any escaping of gas. Place the cup in warm to hot water. Do not boil water with the cup in the pan or the cup will melt. Notice the carbon dioxide bubbling in the water. Does the amount of carbon dioxide given off change when you put the cup in the warm water?
2. Find hidden gases! Look around the house for other gas hiding in liquids. Some of these imposters are hydrogen peroxide, bleach, ammonia, perfume, and cologne. Notice how some of these hidden gases smell, and some smell bad! This is because gas molecules move around a whole lot more then liquid molecules, so our nose picks them up better.

How Was Ice Cream Developed?

You know your favorite flavor and that you have to eat it fast before it melts, but do you know the science of ice cream? Believe it or not, ice cream as we know it has had a pretty rocky road in order to be as yummy and available as it is today. In "The History of Ice Cream," written by the International Association of Ice Cream Manufacturers (IAICM), Washington DC, 1978, a very detailed history of the cold and creamy treat is described. The funny part about the book, though is that most of the early history of ice cream remains unproven folklore.

And so the story goes...once upon a time, hundreds of years ago, Charles I of England hosted a banquet for many of his friends and family. The meal featured the greatest foods of the day and ended with a cold treat that resembled fresh-fallen snow. The guests as well as Charles loved the cold treat and Charles paid the cook 500 pounds a year to only serve it at his Royal table. The cook kept the secret until Charles was beheaded in 1649.

This tale along with others provides some insight into the evolution of our country's most popular dessert. Most likely, ice cream was not invented, but rather came to be over years of similar efforts. Even the Roman Emperor Caesar is said to have sent slaves to the mountains to bring snow and ice to cool and freeze the fruit drinks he was so fond of. Centuries later, the Italian Marco Polo returned from his famous journey to the Far East with a recipe for making water ices resembling modern day sherbets.

These tales are interesting and help to connect history with food science as well as cultural traditions. Unfortunately, no real historical evidence supports any of these stories. The tales might just have been a marketing plan of the nineteenth-century ice-cream makers and vendors. When it comes to actual facts, it seems that ice cream may have had its first appearance in China.

Although the actual history of ice cream is rocky, some of the inventions that were made to improve ice cream are a little more know. The first improvement in the manufacture of ice cream (from the handmade way in a large bowl) was given to us by a New Jersey woman, Nancy Johnson. In 1846, she invented the hand-cranked freezer. This device is still familiar to many. By turning the freezer handle, they agitated a container of ice cream mix in a bed of salt and ice until the mix was frozen. Because Nancy Johnson lacked the foresight to have her invention patented, her name does not appear on the patent records. A similar type of freezer was, however, patented on May 30, 1848, by a Mr. Young who at least had the courtesy to call it the "Johnson Patent Ice Cream Freezer." Commercial production was begun in North America in Baltimore, Maryland, 1851, by Mr. Jacob Fussell, now known as the father of the American ice cream industry. Right in our backyard at Penn State, tremendous research on how to make ice cream from making the best flavors to extending its shelf-life have been occurring for decades. Besides several tasty flavors, the Penn State Creamery offers a course (Ben and Jerry even took it) and a little museum. Maybe one day this summer when you are hot and in the mood for a sweet taste and a food science lesson you should ask your parents to take you down 322 E to Happy Valley. In the meantime, share your secrets on ice cream to your friends and family.

Little Lions Experiment:

Fill up a paper Dixie cup with water and another one with fruit juice. Only fill up the cups to about 3/4 full as liquid expands as it freezes (molecules in ice are bigger than they are in a liquid state). Then, place them carefully in the freezer and time how long they take to freeze. Monitor the process and see where ice forms first. Try to think why ice forms on the top before in the middle. Then, time to see which freezes first water or fruit juice. You can freeze other liquids such as milk or solids just as pudding or yogurt, if you want. Try to determine if a substance's state (liquid or solid) affects its freezing time as well as the material's density, i.e. has more sugar, food ingredients in it. Then, enjoy your frozen treats. Be careful, not to give yourself a "brain-freeze" as cold foods can cause mild nerve triggers that can hurt your head.