Winning Essays
Below are excerpts from The DuPont Challenge© 2009 first-place essays.
Sivabalan Manivasagam, Junior Division First-Place Winner
A New Look at Bees and Wasps (excerpt)
“Ahhh! Get it away from me! Oh no, it’s going to sting!” a child screams, grabbing his parent’s hands and shaking it violently. Then the parent shouts, “Oh no! A bee!” and takes his newspaper and swats the bee to the ground. The bee is paralyzed for a moment, and then lies still- dead. Yet, neither the parent nor the child realizes that in the upcoming years airports, landmines, farms, and hospitals, will be swarming with them - not to cure their phobia of bees, but to save lives.
Now, how could a small bee possibly save lives? Actually the bee (Apis Mellifera) and its family member, wasp, (Vespula vulgaris) have an extraordinary sense of smell. Their ability to smell comes from their antennas (Chemoreceptors) that have thousands of microscopic sensors to sense odors in concentration of parts per trillion. As Robertson Hugh, an entomologist, said, “…bees might encounter a bewildering number of flowers to choose from, but they can discriminate between them using subtle olfactory cues." Harnessing the bee’s acute sense of smell, scientists have made it possible to track down peculiar scents such as TNT (bombs), methamphetamine (drugs), landmines, and even cancer. The tantalizing question is: how can pollen collecting bees become security bomb officers? (ABC News 2005)
Entomologists accomplish this by teaching the bees kinesthetically - exposing the bees to the scent of the new chemical and eliciting a response from them. Scientists first give a bee an ordinary drop of sugar water; the bee sticks out its proboscis (tongue) searching for food. Then they give it the target odor it is supposed to identify such as heroin; there is no response. Next, the scientists offer the sugar water and the scent of the target chemical simultaneously. The bee once again sticks out its proboscis looking for food. For a bee to completely register the odor, scientists repeat giving the sugar water and the target odor at least three times. As a result, the bee relates the smell to food and exhibits a food searching behavior when scientists finally provide the bee with just the target odor. This very method of conditioning for a scent is called the Pavlovian conditioning. Unlike bees, wasps (trained the same way) can communicate by dancing when they sense the chemical. (Gaidos, 2008)
For a list of all the Junior Division winners and honorable mentions, click here.
Julian Whitman, Senior Division First-Place Winner
Water from the Wind: Beetle-inspired Hydrophilic/ Superhydrophobic Structured Surfaces (excerpt)
Deep in the arid Namib Desert of southern Africa, a beetle is getting thirsty. It climbs up onto a rock and tilts its wings up. The beetle stays that way for a few minutes, and as water droplets flow down its back and into its mouth, has a refreshing drink. Where did it get the water from? The answer to this question could solve a major world problem: a looming shortage of fresh water.
Even though the earth is full of water, it is not always available to humans. In the desert, water of any kind is hard to come by. In the sea, all of the water is undrinkable because of the high salt content. So while on an arid island, on a boat, or under the sea in a submarine, you are surrounded by water you can’t drink. There are also an increasing number of places around the world where the readily available water is too dirty or polluted to drink. An unusual desert beetle may hold the solution.
One potential source of water that is always available is the air. Even in the Namib Desert, one of the most arid environments in the world, moisture can be found in the air, especially in the morning fog (Henschel & Seely, 2008). The Stenocara beetle, Stenocara gracilipes, found amidst the desert rocks, can collect the water it needs to live from the wind, using a very special structure on its wings (Zhai et al., 2006). This wing structure, which uses a combination of hydrophilic and superhydrophobic surfaces, has scientists excited about many possible applications.
A hydrophilic surface is one that water is strongly attracted to. In scientific terms, it has a droplet contact angle of 30° or less (Forbes, 2008), meaning that when a water droplet forms on it, the angle from the flat surface to the adjacent drop is small, and the droplet formed is a nearly flat dome. The opposite of this is a hydrophobic surface, a surface that repels water. A superhydrophobic surface has a contact angle of 150° or more, making a nearly spherical droplet. A lotus flower is a naturally occurring hydrophobic surface that repels water along with any dirt it contacts, which is why it appears so white and clean (Forbes, 2008).
For a list of all the Senior Division winners and honorable mentions, click here.
