Monday, August 27, 2007

What are Maraschino Cherries?

-Brian, from Chicago

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Hi Brian!

Maraschino cherries are the bright red cherries found on top of ice cream sundaes. Its sweet taste and bright red color leads many people to believe that it is artificial or manufactured.

cola.jpg

Since I like Maraschino cherries, I decided to look more into where this sweet topping comes from.

How it is made

Maraschino cherries are real cherries that are pickled (in brine, just like pickles). When ready, the cherries are transferred into a syrup of sugar containing a natural red dye. The cherries absorb the sugar and color, giving a sweet flavor and bright red color.

Different flavors and colors can be added to make the cherries appear and taste different. Maraschino cherries typically have almond extract in the syrup. It is also not uncommon to find cherries with a mint taste, which comes from adding peppermint oil to the syrup.

The cherries are then packed in a jar filled with the syrup, sealed, and shipped out, eventually finding their way to sundaes across the nation.

maraschino-cherry.jpg

Maraschino cherries are obviously not grown on trees. It is processed with natural ingredients to give the final taste and color. While these cherries are not good for you, I am sure the soda or ice cream that it came on is worse.

Enjoy!

Dr. Dave

Sunday, August 26, 2007

Why are Antibiotics Useless Against the Cold and Flu?

In 1928, Sir Alexander Fleming’s discovery of penicillin ushered in a medical revolution. For the first time, a drug was available to combat ancient scourges like the bubonic plague, leprosy, and tuberculosis, which were caused by bacteria.

Below is an illustration of a bacteria.
generalbacteria.jpg

Although penicillin was very potent, it was limited in kinds of bacteria it could kill, and therefore, what diseases it could cure. Fortunately, scientists worked hard to develop the modern assortment of powerful antibiotics that we have today.

What are antibiotics?
antibiotics.jpg

Antibiotics are drugs that kill microorganisms. For something to be killed, it must first be alive.

Bacteria are alive because they have the basic machinery of life contained within a cell. This machinery allows microorganisms to make energy from sugar, read and copy DNA, make proteins, and reproduce.

Antibiotics work by destroying a bacteria’s machinery of life.

By destroying this machinery, bacteria will no longer be able to live.

Did you know that the machinery inside a microorganism is similar to machinery that is inside all of our cells? The antibiotics we take are chemicals that are specifically designed to destroy bacterial machinery and not our own! The next time you have to take an antibiotic, think about all the hard work put forth by biologist and chemists to make certain that you don’t get hurt when taking this medicine.

Viruses

Viruses are smaller than bacteria and come in many shapes and sizes. In general, viruses have a protein coat, called a capsid, which protects the genetic blueprint (either DNA or RNA) on the inside.

Below is a cutaway illustration of the influenza (flu) virus.
influenza-schematic.jpg

Viruses lack the machinery to make energy, read and copy DNA, make proteins, and reproduce. Therefore, viruses are not alive!

***Antibiotics cannot kill a virus because it does not have any machinery of life!***

If a virus is not alive, then how do we get sick?

Viruses are the cause of the common cold and flu (influenza). To make us sick, a virus needs to insert its genetic material inside our cells. Once the viral DNA or RNA is inside a cell, it will use our cell’s machinery to construct copies of the viruses. DNA and RNA are the universal blueprints of life so our cells are unable to distinguish the viral genetic information from our own.

The cell will keep making copies of the virus until it runs of resources while pushing out the newly made viruses. Sometimes the cell will die during this process.

The only way to destroy a virus is to take an antiviral drug or have our immune systems destroy it (a subject for later post).

Now you know why the cold and flu cannot be cure by antibiotics!

-Dr. Dave

Tuesday, August 21, 2007

Hurricanes and Latent Heat

Whether we like it or not, it is hurricane season. These giant storms generate strong winds and heavy rains that are capable of extreme destruction.

This is a picture of Hurricane Dean from www.wunderground.com.
hurricane-dean.jpg

Do you know what fuels a hurricane?

Most hurricanes begin as small storms that form in the warm waters of the Atlantic Ocean, as far away as the western coast of Africa. These small storms grow in both size and intensity at an alarming pace when they are exposed to enough heat, moisture, and unstable air.

This track of all the named Atlantic storms in 2006. Storms get named only when it reaches the size of a Tropical Depression. Some storms grow, some lose strength. Take a look!
2006atlantictrackmap.gif

A hurricane cannot form on land because it needs an open body of warm water – like the Atlantic Ocean at the end of summer – for it to grow. Instead, dangerous thunderstorms and smaller spinning storms, like tornadoes, will form on land.

Heat from the sun helps to warm the ocean’s waters to provide energy to establish the best conditions to create a hurricane. The latent heat (see what this is below!) of water helps the feed a hurricane’s strength and intensity once it forms.

What is Latent Heat?

Things in our everyday lives are almost always either solid, liquid, or gas. These are the three phases of matter. Depending on how much the temperature changes, the phase can change. Water is an excellent example of something that we have seen in three phases:

Solid – Ice in the freezer
Liquid – Water from the tap
Gas – Steam above a boiling pot of water

When matter changes phases heat is either given off or absorbed. This is called latent heat.

Check out this illustration from http://www.physicalgeography.net.
latent.gif

Let’s take a closer look at latent heat so we can understand why it is so important.

According to the illustration, heat is absorbed when a solid changes into a liquid. Even more heat is absorbed when a liquid changes into a gas.

Let us imagine that we fill a pot with ice cubes. We know that ice will melt outside of the freezer. The ice is literally absorbing heat from the air! To turn a pot of water into a gas (steam), it has to be heated on a stove and boiled.

melting-ice.jpg

What happens when liquid changes into a solid or a gas changes into liquid?

We know that heat must be absorbed to melt ice or boil water. So if we want to make ice or condense steam, then this means that heat has to be given off or removed.

Making Ice
If you fill a cup with water and place it in the freezer, after a few hours it will turn into ice. How does this happen?

Although a freezer/refrigerator is cold, it is a heat pump: it absorbs heat from the things inside it (making it cold) and pumps the heat outside! Have you ever noticed how hot it gets behind a refrigerator?

This means that heat is given off when changing from a liquid to a solid.

Condensing Water Vapor
When a gas turns in to a liquid, heat is also given off. If you take a glass of ice water outside on a hot and humid day, water vapor from the air will touch the cool surface of your glass and immediately turn into liquid water. The heat given off by this phase change causes the ice in the glass to melt faster than if was sitting in warm air alone.

condensation-glass.jpg

So what does this have to do with hurricanes?

As I mentioned before, hurricanes need heat, moisture, and unstable air to grow and become powerful.

At the end of summer, the water of the Atlantic Ocean reaches its highest temperature. This causes the ocean’s water to evaporate more than usual, putting more water vapor in the air. Eventually, the water vapor will cool and condense to form clouds. This means that heat is given off in the sky.

This occurs over huge area of the ocean, meaning that the sky is being heated more than usual. From the “How does a hot air balloon work” discussion, we know that hot air rises. To a weather scientist, too much hot air is a sign that the sky is unstable.

Did you know that an easy way to tell if the air is unstable is to look for tall puffy clouds in the sky? This is often a sign of bad weather!

When a storm system enters this heated area, it causes the storm to grow both outwards and up into the sky. The hotter the air gets, the stronger the storm becomes. If the heating continues, a small storm can grow into an extremely powerful hurricane many hundreds of miles wide!

To learn more about hurricanes, NASA has a great website on hurricanes with links to interesting videos and information.

NASA’s Hurricanes Main Page

This link has a short 8 minute video with cool animations that is very informative.

This link has an amazing video of Hurricane Katrina. Notice how the hurricane looks small at the beginning of the video before it hits Florida and then grows to a huge size over the warm waters of the Gulf of Mexico. I am amazed and scared by the power of nature!

Dr. Dave