All posts by Taehyun

Bug Repellent

mosquito
mosquito

Bzzzzz. Bzzzzz. Bzzzzz. SMACK!! Mosquitos – maybe the most annoying pest to ever fly, are the always the ones that ruins my sleep. As usual, mosquito visited me during midnight and woke me up. The sound that mosquito emits right beside my ear disturbed my sleep. So I picked up bug repellent and sprayed it to myself. Bug repellent was very effective. Within few minutes, it nullified mosquitos, and I could go back to sleep peacefully. But then, I started to wonder what is bug repellent and how it works.

In order to understand how bug repellent works, I thought that it is important to understand how mosquitoes detect us as targets. Mosquitoes contains three different sensors: chemical sensors, visual sensors and heat sensors, which allow them to target their prays. Among those three sensors, mosquitoes largely rely on their chemical sensors. “Scientists have identified several proteins found in mosquitoes’ antennae and heads that latch on to chemical markers, or odorants, emitted from our skin.” (Knight) And mosquitoes use these proteins to detect carbon dioxide and lactic acid, which are the gases that mammals and birds emit as part of their normal breathing.

The U.S. Environmental Protection Agency (EPA)
The U.S. Environmental Protection Agency (EPA)

What is bug repellent? There are two different types of bug repellents: natural and synthetic bug repellent. Basic idea of each repellent can be deduced from its own names. Literally, natural repellent is from nature and synthetic repellent is a mixture of chemical substances. Although natural repellent is much more safe than synthetic repellent, people prefer to use synthetic repellent because it is much more effective and lasts longer than natural repellent. The U.S. Environmental Protection Agency (EPA) recommends people to use repellent that contain active ingredients that the EPA approved their safety. Some examples of active ingredients are DEET, and Picaridin.

Then how does mosquito repellent actually work? When chemical substances i.e. DEET or Picaridin, from the repellent are sprayed on a surface of skin, those chemical substances prevent mosquitos’ bites by disturbing their ability to detect protected surface. So basically, mosquitos are no longer able to detect us using their chemical sensor. But bug repellent is effective for limited amount of time because repellent is not on the surface it is sprayed permanently.

What are the implications of knowing this? These days the most dangerous living organism is, with no surprise, mosquito. According to Illinois Department of Public Health, every year, “mosquitoes transmitting malaria kill 2 million to 3 million people and infect another 200 million or more.” (“Illinois Department of Department of Health”) Nearly half of world’s population is at risk for malaria. By developing the technology of getting away form mosquito bites, people can lower the risk of getting malaria. Although bug sprays or repellents are widely supplied to urban area, since the major areas, where people suffer from malaria, are not developed, people there do not have access to bug repellents. So it is important to find out natural repellents, which can be found naturally and is not harmful to children. Also, in the course of developing efficient bug repellents, just as other inventions came about accidentally, scientists may be able to invent malaria vaccination.

Word Count: 520

Bibliography

“Mosquitoes and Disease.” Illinois Department of Department of Health. Illinois Department of Department of Health, March 29, 2007 . Web. 7 Oct 2011. <http://www.idph.state.il.us/envhealth/pcmosquitoes.htm>.

“Active Ingredients Found in Insect Repellents.” The U.S. Environmental Protection Agency (EPA). The U.S. Environmental Protection Agency (EPA), September 10, 2009. Web. 7 Oct 2011. <http://www.epa.gov/pesticides/health/mosquitoes/ai_insectrp.htm>.

“Repellents are an important tool to assist people in protecting themselves from mosquito-borne diseases..” Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, October 13, 2009. Web. 7 Oct 2011. <http://www.cdc.gov/ncidod/dvbid/westnile/repellentupdates.htm>.

Freudenrich, Craig. “How Mosquitoes Work.” How Stuff Works. How Stuff Works, n.d. Web. 7 Oct 2011. <http://science.howstuffworks.com/environmental/life/zoology/insects-arachnids/mosquito.htm>.

Knight, Meredith. “Why do mosquitoes bite some people more than others?.” Scienceline. Scienceline, September 10, 2007. Web. 7 Oct 2011. <http://scienceline.org/2007/09/ask-knight-mosquitoes/>.

Reply to Juhi’s post: A Wall of Water.

After reading Juhi’s post about Japan’s earthquake, I decided to do a little research on Japan’s earthquake and how much it damaged Japan. I realized that the potential damage from the destruction of the nuclear plant is more devastating than the earthquake itself. This led me to ponder upon the science behind the nuclear plant and why it is so harmful to people.

Fukushima power plant after the quake
Fukushima power plant after the quake

The nuclear power plant, like other common power plants, creates electricity by operation a generator. We decide whether the power plant is hydraulic or anything else by the source of the power that operates the generator. Nuclear power plant gives power to the generator through a reaction called ‘nuclear fission’, during which a highly reactive radioactive element called enriched uranium 235 is situated at the heart of the nuclear generator. Nuclear fission is a process that causes the atoms to split into smaller pieces or components. When the Uranium undergoes nuclear fission, it splits into 25 neutrons and emits great amount of lights and energy. This energy that has been produced during the nuclear fission of the Uranium heats the water and water vapor generates the electricity. Ok, but why is this type of power plant so dangerous when it is destroyed?

nuclear power plant
nuclear power plant

One of the important parts of the reactor is a circuit pipes containing cold water that runs through the reactor. Due to the heat that has been produced by the nuclear fission, the water is heated and becomes vapor. This hot vapor needs to be cooled down after it is used to generate electricity. The circuit pipes full of cold water cool down the vapor and change it back to water. The power plant would be safe if the supply of the cool water is continued, but once condensed cooling water stops its supply of cool water to the generator, the temperature of the generator remains high, which is the basic reason for the disaster that might happen. If the cooling mechanisms fail, a power plant meltdown will occur because the enriched uranium core heats up and forms liquid. The process produces radioactive iodine and cesium. The extreme heat produced by the nuclear meltdown will also melt and burn surrounding structures inside the power plant; this can compromise structures intended to contain the radioactive fuel. When the surrounding structures are burnt, danger of massive nuclear radiation leak increases. Leak of nuclear radiation is harmful to our body and it may cause DNA mutations. Also, during a melt down, hydrogen gas is produced. When hydrogen gas reacts with the heat energy, it forms incredible amount of energy that can destroy everything. This is similar to the basic principle of the atomic bomb. Inducing from these scientific concepts, Japan itself is an atomic bomb right now.

It is impossible to count the actual number of nuclear power plant around the world, but it is certain that when a massive blackout worldwide occurs, (due to the explosion of the sunspot maybe) the entire earth will be exposed to nuclear radiation. This incident shows how our misconception that “we” have the power to control nature and use it for our own benefit can destroy us. Because it is not “we” who has power over nature, but the nature itself that owns us.

MLA Citation

Carter, Mia. “How Does a Nuclear Power Plant Work? – Japan’s Meltdown Crisis.” Suite101 (2011): n. pag. Web. 22 Mar 2011. <http://www.suite101.com/content/how-does-a-nuclear-power-plant-work—japans-meltdown-crisis-a358388>.

Hathaway, David. “The Sunspot Cycle.” National Aeronautics And Space Administration. National Aeronautics And Space Administration, 01 03 2011. Web. 22 Mar 2011. <http://solarscience.msfc.nasa.gov/SunspotCycle.shtml>.

Rogers, James. “How Do Nuclear Plants Work?.” Duke Energy n. pag. Web. 22 Mar 2011. <http://www.duke-energy.com/about-energy/generating-electricity/nuclear-how.asp>.

CFCs, earth’s cancer

Last week, I went to take a toefl test, and listened to a lecture that was about the depletion of ozone layer due to the synthetic chemical, chlorofluorocarbons (CFCs a.k.a. Freon gas). Since I’m taking IB HL chemistry, I was excited to listen to the lecture. Also, since my father is working at Samsung, mainly the refrigerator and AC department, he often tells me about the importance of reducing the use of CFC. When he was explaining why our family is living abroad, he reasoned this CFCs as one of the major reasons. Since Korea is now considered as a developed country, Korea should not produce CFCs anymore. So, in order for Samsung to keep manufacture the fridge and AC, it was important to move to China. After the lecture, I soon became very curious about how CFCs react with ozone layer and break apart ozone layer.

CFCs are inert, non-toxic, non-flammable, and odor-less synthetic chemicals. They were first synthesized in 1892, but the public couldn’t find their usage until the 1920s. Since they are stable and apparently harmless, CFCs are used as refrigerants in air conditioners and refrigerators, manufacture of foam packaging, and as degreasing agents. Despite CFCs’ diverse usage in industry and science, I was surprised at how CFCs are responsible for the depletion of the ozone layer.

Where ozone depleting substance can be found

How do these non-toxic, non-flammable CFCs are major reasons for the depletion of the ozone layer? After the CFCs are emitted, they are brought up to stratosphere. Let’s talk about stratosphere first. There are five different types of layers in the atmosphere, and stratosphere is between 10km and 50 km altitude This layer is important because it contains ozone layer, which shields lives on earth from the Sun’s harmful ultraviolet (UV) radiation.

Layer of atmosphere
Layer of atmosphere

When the CFCs are brought up to stratosphere by strong upward-moving air currents in the tropics with other chemical compounds such as Methane (CH4), nitrous oxide (N2O) and water, they react with the sunlight (UV), and polar stratospheric clouds (PSCs), and emit chlorine atom, which is highly reactive because it is unstable with seven valence electrons. As soon as atomic chlorine is formed, it reacts with O3, which is ozone, and breaks up the ozone, forming oxygen gas (O2) and ClO.

The reaction with chlorine, nitrogen, oxygen, hydrogen, and bromine gases destroys ozone, and this process is called catalytic processes. A catalytic reaction cycle is a set of chemical reactions, which results in the destructions of many ozone molecules while the molecule that started the reaction is reformed to continue the process. Because of this process, each chlorine atom can on average ruin nearly a thousand ozone molecules before it is converted into a form harmless to ozone. For better understanding, watch the animation (3rd graphic) in the following link. CLICK

CFC

So, what effort did the nations around the world had done to reduce the production of substances that destroy the ozone layer?

In order to reduce the amount of CFCs being emitted, the Montreal Protocol, an international treaty, was designed to protect ozone layer by phasing out the production of substances that was believed to be responsible for ozone destruction. Since September 16, 1987, when the agreement was signed, it has undergone seven revisions. As a result, the amount of CFCs and other substances that break up the ozone has been reduced significantly.

World reduction of CFC
World reduction of CFC

The reduction of CFCs has brought significant change in my life. Because Korea cannot emit any CFCs anymore, our family had to move to China. Also, it has affected my father’s industry greatly. First of all, economically, Samsung now has to spend more money to get substitutes for CFCs and getting efficient substitute is its one of the major problems they need to solve. Also, the world regulation of CFCs changes the current of what the big companies around the world focus on when they manufacture goods. For example, Samsung, since it is not allowed to emit any CFCs or other substances that might harm the ozone layer, will now try to transfer its technologies to the developing countries, and develop new fields, such as medical machineries.

Bibliography

“where ozone depleting substances can be found.” the ozone hole. Web. 15 Jan 2011. <http://www.theozonehole.com/ozonedestruction.htm>.

“The CFC Problem.” CFCs. Web. 15 Jan 2011. <http://www.theozonehole.com/cfc.htm>.

“World production of CFCs.” CFCs. Web. 15 Jan 2011.

Welch, Charles. “Ozone destruction.” The ozone hole. The Ozone Hole Inc., n.d. Web. 15 Jan 2011. <http://www.theozonehole.com/ozonedestruction.htm>.

Welch, Charles. “Ozone destruction.” The ozone hole. The Ozone Hole Inc., n.d. Web. 15 Jan 2011. <http://www.theozonehole.com/cfc.htm>.

Fatalism doesn’t exist; Big Bang didn’t exist.

Do you believe in Fatalism and Big Bang Theory? You might say ‘Fatalism and Big Bang Theory is not related.’ But, yes, they are related. How are they related? For a long time, scientists have done lots of investigations to figure out their questions and one of the questions they had was how did the universe was formed. Finally they could come up with reasonable theory, which is Big Bang Theory and its physical property connects Fatalism and Big Bang Theory.

What’s Big Bang Theory then?  The basic concept of Big Band Theory is that the universe, which is keep expanding formed present state by the huge expansion at a single point trillion years ago.

Alexander Friedmann first suggested the expansion of the universe. He derived the Friedmann equation that shows the universe might be expanding. Later, Lemaître, Belgian physicist suggested that the evident expansion in forward time required the universe contracted backwards in time, and would continue to do so until it could contract no further bringing all the mass of the universe into a single point. He concluded that massive expansion from this point resulted the expansion of the universe today. Look at Figure 1 and Big Bang Theory Video for better understanding.

Figure 1
Figure 1

the ancient universe was a single point and huge expansion formed present size of universe.

This is what Big Bang Theory is. Then you might say ‘Still, I can’t find any relationship between Big Bang Theory and Fatalism.’ Here, we have to jump into Physics to understand the relationship between fatalism and Big Bang Theory. There is a basic physical property that every material follows, which is Newton’s third law. It is also known as the properties of action and reaction. It states that every action, there is a reaction that has equal but opposite direction force. For example, if a pen is dropped (action), the pen will hit the ground (reaction). The action force is downward with its force, weight, while the reaction force is upward with equal magnitude of force to the action force. Also, when the rocket propulsion exerts force downward (action), the rocket goes straight up (reaction). (Figure 2) The reaction is what is caused as a result of the action and it applies for all areas of the known universe. Also, all the reaction is fixed and never changes, which means that every time I apply 10N (10 units) of force on certain object, the reaction will be same.

Figure 2
Figure 2

Let’s assume that the Big Bang itself as an action. Then, there should be a reaction that was caused by the action of the Big Bang. The reaction that happened after the Big Bang was the expansion of the universe, and the formation of the planets. Even the evolution of human beings and all living things can be considered as a reaction to the Big Bang that had happened trillions of years ago. Since the reaction to an action is always defined, the Big Bang (action) has its defined reaction. This can be interpreted as a means to fatalism. This means that when we assume a reaction to the Big Bang, our decisions as human beings have already been fixed since the universe was born.

Strange, huh? So, do you still believe in the Big Bang Theory?

Bibliography

1. “All About Science.” Big Bang Theory. N.p., n.d. Web. 18 Oct 2010. <http://www.big-bang-theory.com/>.

2. “Physics Classroom.” The Law of Action-Reaction. N.p., 2010. Web. 18 Oct 2010. <http://www.physicsclassroom.com/class/momentum/u4l2a.cfm>.