Why Do Onions Make Us Cry?

Shanna from Altoona, PA, was helping her big sister prepare dinner one night, and she noticed that her eyes became really irritated when her big sister cut up an onion. She wrote in asking: why do onions make us cry? We will explore the answer to that question but we will also explore some methods that might minimize the eye irritation. Many people enjoy the taste of onions in their meals. In fact, the average American eats about 20 pounds of onions each year. Onions are healthy components of the human diet because they contain vitamins B and C, protein, calcium, and iron. They also contain quercetin (pronounced KWAIR-SUH-TEN), which is an antioxidant that works to neutralize harmful substances in our bodies that cause tissue damage and aging. In addition to being full of nutrients, onions are low in fat and sodium. However, if you have ever cut into an onion, it is likely that your eyes filled with tears because they became irritated just like Shanna described. But why does this happen? How can we enjoy the taste and benefits of onions without the tears? When you cut into an onion, an enzyme (a biomolecule that speeds up chemical reactions) is released into the air from the ruptured onion cells. This enzyme converts some of the proteins from the onion into sulfenic acids that then become a gas. These can then come in contact with your eyes. These acids contain sulfur compounds that are common eye irritants. The gas reaches your eyes and reacts with the water that keeps them moist. The eyes become irritated, and your brain reacts by telling your tear ducts to produce more water that helps keep the eyes protected. You may want to rub your eyes to help soothe the irritation, but this will only make the irritation worse since your hands may have onion juices all over them. Some people wear goggles to minimize any irritation produced when cutting onions, but some also try the different methods discussed in the Little Lion Experiment. Give each method a try to figure out which one works best for you so you can enjoy onions without any eye irritation!

Little Lion Experiment:

How can we enjoy the benefits and the great taste of onions without the tears? For this experiment, you will explore some methods that are thought to reduce the unpleasant eye irritation that occurs when cutting into an onion. You will need an adult present to help you with this, especially when cutting the onion. It is preferable to try these methods over 5 different days, but you can try each of these home remedies during the same time. Throughout each of these methods, keep track of whether your eyes were irritated when the onion was cut and try to determine which method works best for you.

Items Needed

• 5 small onions with the outer layers peeled away
• 1 lemon slice
• Slice of bread
• Sugar
• Bowl of water
• Access to a refrigerator
• Knife

Procedures

1. Method 1: Put one onion into the refrigerator. After 30 minutes, take it out and cut the onion.
2. Method 2: Put one onion into a bowl of water so that it is covered in water. Cut the onion while it is submerged in the water.
3. Method 3: Put a lemon slice in your mouth. Then cut the onion (keeping your mouth open)
4. Method 4: Put a bread slice in your mouth. Then cut the onion (keeping your mouth open).
5. Method 5: Put some sugar in your mouth. Then cut the onion (keeping your mouth open with the sugar on your tongue)

Questions:

Did any of these methods work to keep your eyes from being irritated? If so, which ones worked the best? Having the onion chilling in the refrigerator before cutting it, like in Method 1, is supposed to slow the release of the irritating gases. Keeping the onion under water while cutting it, like in Method 2, is supposed to keep the gases from even reaching your eyes. Keeping the sugar, bread, or lemon slice in your mouth while cutting the onion, like in Methods 3-5, is supposed to keep the gases from ever reaching your eyes since the food will absorb the gases. Try to remember these different methods each time you help out with the cooking at home. And remember to wash your hands after handling an onion since they will be coated in the onion's eye irritating compounds.

How Does Temperature Affect the Cleaning Ability of Soap?

James from Altoona, PA, was helping his older brother wash some dishes in their kitchen sink recently, and he noticed that the dish detergent seemed to rinse off the dishes better with cold water than with hot water. He also observed that the hot water helped make the dish detergent foam more (i.e., produce more soap suds). He wrote in asking: how does the temperature of water affect the cleaning ability of soap? The use of soaps and detergents is part of everyday life (at least it should be!) so let's first discuss what soap is and how it works. You have probably heard the terms soap and detergent used to describe the various products that are used to clean clothes, dishes, hands, cars, or pretty much anything that needs cleaning. While they are very similar, they are slightly different. A detergent is a substance that cleans dirty or soiled surfaces. It is usually made from synthetic ingredients, which means the ingredients are not naturally occurring and are maufactured from different chemicals. Soap is a type of detergent and is usually produced from natural ingredients. Just from looking around your home, you probably have noticed that soaps and detergents are produced in many different physical forms - for example, there are bars, flakes, pellets, liquids and even tablets! Detergents and soaps contain a basic cleaning agent called a surfactant, which stands for surface active agent. Surfactants consist of molecules that attach themselves to the dirt particles of the dirty material that is being cleaned. The dirt particles are pulled out of the dirty material and are then held in the wash water until they are rinsed away. Most detergents contain a synthetic surfactant in addition to other chemicals that are added to improve the detergent's cleaning ability. Other ingredients that are added to detergents include perfumes, coloring agents and germ-killing or antibacterial agents. When it comes to temperature, hot or cold water is acceptable when cleaning with soap. The most important part of cleaning is using the soap or detergent! You need something that will pull the dirt particles from the dirty areas. Water alone will work OK, but water with soap will work even better.

Little Lion Experiment:

Like James above, you may notice that more soap suds are produced when using hot water. The reasoning for this begins with the fact that warmer water evaporates faster than cold water (the warmer water changes from a liquid to a gas faster than cold water). Soap suds or bubbles are formed more easily when the warmer water is evaporating. Colder water evaporates slower so it is harder to make soap suds. With this information, do you think bubbles will last longer in hot or cold water? This experiment will help you determine the answer!

Items Needed

• Two large bowls (or tubs)
• Rubber gloves
• Tablespoon measuring spoon
• Access to cold and hot water (from your faucet is OK)
• Stop watch
• Some type of soap (you can use dish detergent, laundry detergent, hand soap, etc.)

Procedures

1. Fill one bowl with warm water and the other bowl with cold water.
2. With the gloves on, add one tablespoon of your soap to each bowl.
3. Use the tablespoon to mix the soap into each bowl for 30 seconds.
4. After mixing, start the stop watch and observe how long the bubbles remain in each bowl. Did the bubbles last longer in the warmer water or the cold water? Why do you think this is so? With the faster evaporation of the warm water, the bubbles may form more quickly than the cold water but that also means that they will disappear sooner too. The slower evaporation of water means that the bubbles may take longer to form but they will also last longer once formed.

What is in the Air We Breathe?

Laura from Hollidaysburg, PA, was recently helping her parents clean her home, and she noticed how much dust there was on the tables, in the air, and coming from the couches! She wrote in asking: Where does dust come from and what happens to it when we breathe it in? About 21% of the air we breathe is actually oxygen, while the remaining air consists of other gases (e.g., nitrogen, argon, carbon dioxide). However, the air also consists of dust, tiny animals, and other stuff! Dust is defined as dry, solid particles that are less than 0.0625 millimeter in diameter, which is smaller than all grains of sand! Most dust is composed of mineral matter that originated from bare soil, plowed fields, river flood plains, and floors of desert basins. Dust also comes from ocean spray, smoke and ash produced by fires, decaying organic materials, and volcanic eruptions. The wind actually lifts up the dust particles and easily carries them long distances around the earth! The dust in your home can also be made up of dust, pollen, mold, sand, skin flakes, and pet dandruff. These air particles are actually the most common causes of allergies or asthma. Humans and animals can also act as carriers of dust and air particles because the air particles can cling to their skin or clothes. When you breathe in, you are also breathing in dust or air particles. Some of these air particles will get caught in your nose hairs, some will get caught in mucus in your airways, and some will make it into your lungs. However, don't worry too much about this, because most of what you breathe in will cling to the hairs on the inside of your nose. These hairs act as a filter, which works to trap the inhaled air particles inside your nose to keep them from traveling into your respiratory system. The hairs usually trap particles that are less than 5 nanometers in size (that is approximately 0.000005 mm!). Aside from the many nuisances of dust around your home, dust actually contributes to some beautiful sunsets and sunrises. That's right, dust is what makes sunsets and sunrises so pretty! The intense red and orange colors of the sky at sunset and sunrise are mainly caused by the scattering, or reflection, of sunlight off air and dust particles. So the next time you are cleaning your house or enjoying a beautiful sunset or sunrise, think of the dust that is contributing to these everyday events.

Little Lion Experiment:

This experiment will allow you to observe the types of air particles you breathe regularly.

Items Needed

• 6 index cards
• Scissors
• A pen
• 6 pieces of string
• tape (scotch, masking, duct, or packing tape is good)
• A magnifying glass
• A ruler

Procedures

1. Cut squares into the center of each index card. Try to make all the squares the same size (e.g., about 2'' by 3'').
2. Choose 6 locations within your home that you want to hang the air particle collectors. Some places to hang your air particle collector include: above your bed, on the inside or outside of a window, near a heating vent or air conditioner, above the cooking stove, on a wall near the floor or ceiling, on your main entry door, and under a tree.
3. Write down the locations on the index cards so that each index card has a different location on it
4. Write the starting date on each index card
5. Cover the window on the index card with the tape so that the stick side up or out.
6. Attach string to each index card, and then hang the cards at the appropriate locations.
7. Wait a few days and then take the index cards down without touching the tape. Make sure to note the date. Which location had the most air particles collected? Were these locations inside or outside? Why do you think this is so? Think about where air is moving, and where the air particles could be coming from. Use your magnifying glass to examine the air particles up close. Can you recognize any common air particles?

Why Do We Get Sunburns?

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 (UV stands for ultraviolet), 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 shed or 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.

How Does a Pencil Eraser Work?

The pencil eraser works based on the friction developed between the eraser and the paper. Friction is what causes your hands to heat up when you rub them together. When you rub two objects the roughness of their surfaces contact each other and rub against each other causing friction. A simple pencil is made of a combination of wood and finely ground graphite and clay, mixed with water and pressed together at high temperatures into thin sticks or rods. Graphite is a mineral composed of an element called carbon, and it is black in color. There are also mechanical pencils that need rods of graphite to function like a pencil. You may have heard that pencils are made of lead, but that is actually a misunderstanding that is based on the initial thoughts of those that first discovered graphite - they believed it to be lead, which was not the case at all. However, many still refer to graphite in pencils as lead. Graphite particles are arranged in layers or sheets. A pencil mark consists of graphite particles that have peeled off from the pencil point onto the paper. These particles have an angular, gritty look to them when viewed under a microscope. When the pencil is used on a sheet of paper, the graphite particles lie slightly below the surface of the paper, interlocked between its fibers. A single rub using an eraser sufficiently soft to reach between the fibers will pick up most of the graphite particles. Looking at the eraser you can see undamaged graphite pieces sticking to the surface. An effective erasing material scratches the paper surface, producing the familiar small spindles of rubber or eraser material, which wrap up the graphite particles. When you look at these under an optical microscope at 200 times magnification (200x), these look like roly-poly puddings studded with graphite raisins.

Little Lion Experiment:

Erasers come in a variety of colors: white, pink and gray are some of them. Sometimes the color difference is because of a dye or because the eraser is made of a different type of rubber. Go around your house and see how many types of different erasers and pencils you have. For example, compare number 2 pencils with a number 3 pencil. Also, if someone in your home has a mechanical pencil, you can purchase different types of pencil leads (like hard black or soft) or they might have different leads you can use. The bright-colored erasers (like purple and yellow) are usually white erasers in disguise! You can also use erasable pen as a pencil type. See which one of these works best with different types of pencils and ink. Can you erase the ink with a pink or white eraser? Is there one eraser that works for all lead types? Knowing what you know about how erasers work, why do you think certain erasers do not work with other types of pencil lead and ink?

Why Does Ice Float?

It is almost officially summer! And that means plenty of sunshine and hot temperatures. With all the sun and heat, you will likely be drinking more water to keep hydrated. Most people prefer their water to be "ice cold", which just means there is ice in the glass to keep it cold. But, you may have noticed that ice doesn't just sink to the bottom of the glass - have you ever wondered why? This month we will explore that very question! The meaning behind this mystery lies in the different properties of solid and liquid water. Nearly every solid, if placed in its liquid form, will sink to the bottom. Luckily for us, the properties of water are different. Unlike most other substances on Earth, the solid form of water floats on the liquid form. This is caused by the change in density, which is defined as the amount of mass in a volume. With the exception of water, most substances on Earth become denser as they become colder. The solid ice will float because its density is lower than that of water. It is about 9% less dense than water. The denser water sinks to the bottom forcing the less dense ice to the surface. What makes water molecules different from other molecules is that they attract each other in an organized fashion. As the water cools, the molecules begin to bind to each other, forming a hexagonal pattern (shape that has six sides). Water is at its densest point at 4 degrees C. After that point, the water molecules move very slowly and attract to each other. In most substances, the molecules are more tightly packed together in solid form. But in ice, the hexagonal pattern of the attracting water molecules leaves empty spaces. This is why water expands when making ice cubes. The empty space between the hexagonal shapes makes the solid form less dense than the liquid form so that it floats to the top. Thanks to this oddity of physics, the water in our oceans and seas remain in liquid state. If the solid form of ice happened to be denser than water, the ice would sink to the bottom. If this happened, the ice on the bottom would begin to freeze up toward the surface. Eventually, nearly all the water on Earth would become solid ice and never melt. Luckily, ice floats and remains on the surface so that the water underneath remains in liquid form.

Little Lion Experiment:

This experiment will demonstrate that ice does float in most liquids, but you will also test other solid materials to see if they float, too.

Items Needed

• 4 ice cubes
• 4 small rocks
• 4 small magnets
• 4 quarters
• 4 glasses
• 4 different liquids (e.g., water, soda pop, salt water, and milk)

Procedures

1. Put each liquid in its own glass.
2. Drop one of each solid material (i.e., ice cube, small rock, small magnet, quarter) into each glass.
3. Observe what happens. Did any of the materials sink to the bottom or float to the top of all the glasses? Did some sink to the bottom of one glass but float to the top of another glass? What can you conclude about the solid materials? What can you conclude about different liquids used? Keep trying different solid materials and different liquids to see how they compare!

What Are Allergies?

A-choo! With all the flowers blooming, it is no wonder that hay fever is upon us - that is, it is allergy season! Kaylee from Altoona, PA, who suffers from seasonal allergies writes in to ask about 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 that 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. Here's an interesting 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:

This experiment will demonstrate how allergens or pathogens may stick to the lining of your nose or throat to cause sneezing and coughing.

Items Needed

• An empty toilet paper roll
• Running water from your sink
• Black Pepper
• Salt
• Confectioner's Sugar
• Jimmies or sprinkles

Procedures

1. Run water over the inner surface of the roll until it is wet but not soggy.
2. Hold the tube sideways in one hand over a sink (so as not to make a mess) and carefully place the pepper on the inside of the tube
3. Rotate the tube until it is coated with the pepper.
4. Repeat steps 2 and 3 with the salt, sugar, and jimmies

Did all of the substance stick? 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. Now, 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.