THE LOTUS’ MAGIC

By Fernando Luna Vera

Ph.D. Candidate, Chemistry Department, VCU

Science Museum of Virginia Volunteer

On August 16^th 2008 millions of people witnessed one of the greatest achievements in the history of the Olympics games, Michael Phelps winning his eighth gold medal in Beijing. Beyond the incontestable talent of Phelps, this amazing feat was in part possible by the technology he wore. The fabric utilized in his swimsuit emulates a shark’s skin, which minimizes the drag of one’s body in the water. Using this technology, Phelps was able to swim like a shark as if he were hunting his prey.

Bio-inspiration applied to technology development is called Biomimetics. This discipline has shown us that by learning and unraveling nature’s tricks human life can be transformed in many ways, one ruse at a time. One example is the phenomenon of high water repellency (super-hydrophobicity) born by some plant leaves and especially distinguishable in the species Nelumbo lutea better known as the “Lotus,” from where the effect takes its name: The Lotus effect.

When water does not stick to a surface, like on Lotus leaves, the droplets adopt a spherical shape, so it looks like a marble sitting on top of a table. In contrast, when on a surface that is water-friendly (hydrophilic), droplets can spread out and appear flat like a Frisbee. A collateral effect of this is that the sphere-like droplets can roll along the surface instead of slide down on it. This fact creates one of the most appealing features of the Lotus: it can self-clean its own leaves.

This effect is due to water’s high surface tension. Molecules on the droplet’s surface eagerly want to adhere to anything that deter them from being exposed to the water/air interface. Because the Lotus offers a waxy, hydrophobic substrate, the water does not spread out on the leaf. Water has to adopt the shape that allows the smallest air-exposed area: a sphere. Now, since the surface molecules still want to get rid of the overwhelming job of being at edge of the droplet, when the drop rolls down the surface all the tiny particles like soot or pollen found on its path get picked up by it. The water surface then becomes covered with a layer of dirt. This is the way self-cleaning occurs and in the end the leaf and water droplet are happy.

So therefore, self-cleaning is possible when water does not stick to the substrate and retains a spherical configuration. But how does the Lotus achieve this? Using highly sophisticated microscopes, a technique called Scanning Electron Microscopy (SEM), researchers have shown that the Lotus’ surface is not smooth at all and in addition to its waxy layer it possesses a well organized structure. It is widely recognized now by scientists that nearly all super-hydrophobic and self-cleaning leaves consist of an intrinsic hierarchical structure where pillars of micrometric size (just millionths of a meter) arrange to form a forest of columns made of water repellent wax. If Lotus’ surface were waxy, but not smooth, it would repel water; water would not acquire a well-defined sphere-like shape and therefore would not pick up the dirt particles.

This knowledge from the Lotus plant has provided the secret to developing many products available today which produce well structured surfaces (Lotus-like). Some self-cleaning paints, which are used in exterior wall coatings (i.e. Lotusan ®) will self-clean a surface when it rains. Can you image your house having a fresh look just after a summer storm? There are water-repellent fabrics that never get dirty (i.e. Nanotex ®) and are used to manufacture outdoors furniture and clothes that very seldom need to get laundered. General Motors is currently working on developing a Lotus-like metal surface to be incorporated within aircraft-technology that avoids the formation of ice, simply because water won’t stick to this kind of surface. These technologies are not just providing comfort; they help in reducing water consumption too, which in the end turns into environmental gain. The human imagination is unlimited and hopefully new technological applications for the lotus effect are still to come. By the way….have you seen a gecko climbing a wall lately?

References and links:

Bhushan, B., Jung C. Y., Koch K., Phil. Trans. R. Soc. A 2009 367, 1631-1672

http://www.youtube.com/watch?v=MFHcSrNRU5E

Could the oil spill reach Virginia?

As officials make another attempt to cap the well spilling oil into the Gulf of Mexico, Virginians might be asking, “Could oil show up here?” As of now, it appears a large oil slick on Virginia waterways is unlikely, but oil residue in the form of tar balls could wash up on local beaches. How could oil that’s currently in the Gulf of Mexico end up in Virginia?
The Earth’s oceans are always on the move, their motion influenced by atmospheric circulation patterns, water temperature and salinity, ocean floor topography, and the Earth’s rotation. These ocean currents can occur both at the surface and deep in the ocean; they often travel great distances and have an enormous effect on regional climates.
As far as the oil spill goes, the Loop Current is the first culprit that could carry oil toward the East Coast. This current flows north between the Yucatan Peninsula and Cuba into the Gulf of Mexico, loops east and then south along the west coast of Florida. The Florida Current would take up where the Loop Current left off, carrying the oil around Florida. Then the Gulf Stream would take over and carry it up the southeast coast.
The Gulf Stream is an enormous river of warm water averaging 60 miles in width and 3000 feet in depth. At Cape Hatteras, the current’s flow rate is an incredible 85 million cubic meters per second, equivalent to over 1 billion fire hoses! (By comparison, the Mississippi River moves water at roughly 0.6 million cubic meters per second.) A major influence on East Coast weather, the Gulf Stream sometimes breeds Nor’easters in the winter and intensifies hurricanes in the summer, as happened with Hurricane Hugo off the coast of South Carolina in 1989.
At present, disruptions in the Loop Current appear to be keeping oil away from Florida and the Gulf Stream. Eddies often form and then break off from the main body of the current; the majority of the oil that had drifted into the Loop Current in recent weeks appears to be caught in an eddy and cut off from the main body of the current. Satellite pictures even suggest that the current itself may soon sever entirely, lessening the imminent threat of oil coming ashore in Florida and beyond.
This afternoon BP began an attempt to plug the leak with a method called top kill, an ambitious procedure intended to clog the well with thousands of pounds of heavy fluids pumped through extremely long pipes. This procedure has never been attempted so far beneath the surface; it could take several days to determine if it was successful. For everyone’s sake, let’s hope they succeed.

Satellite image courtesy of NASA. Colors indicate water temperature: darker colors = cooler temperatures, lighter colors = warmer temperatures.

Why Hot Sauce is Hot…..

By Fernando Luna Vera

Ph.D. Candidate, Chemistry Department, VCU

Science Museum of Virginia Volunteer

“Can you please pass me the hot sauce?” a friend of mine asked. “This one?” I replied, holding up and showing him a warm spinach dip cup. “No! The spicy one,” he said. As I passed it to him, I mentally wondered an almost childish question, “Why do we call it hot sauce if it is not really hot…nor is it even served warm!” Appreciating and feeling the taste of food involves a complex mechanism that uses the sense of taste, smell and touch. This rise of sensations and perceptions sparked by food requires hundreds of chemical signals and our brain acting as traffic officer to control them.

After you bite a spicy taco your body can recognize that familiar, pungency sensation thanks to a well equipped network of sensors called neurons. Neurons, as do all animal cells, contain a boundary layer called a membrane, where specific receptors are allocated. These receptors are like the geometric figures on the surface of a shape sorter toy which recognizes specific shapes. Certain neurons, called nociceptors, have the specialized job of sensing pain. These kinds of neurons contain a specific receptor for capsaicin, the molecule found in high concentration within chili peppers. One can image then, capsaicin molecules traveling to the tongue and getting caught later by the nociceptors, which immediately after recognizing them, trigger an electrical signal that travels to the brain and makes us aware of the irritating sensation of the hot sauce. That specific capsaicin receptor is called TRPV-1.

But why does our brain read the signal produced by capsaicin as an increment in temperature? An experiment performed in 2000 by scientist of UCLA helped us to better understand this outcome. By using genetic techniques, they “knocked out” the gene that produces the capsaicin receptor (TRPV-1) from a group of mice and compared it with other group that still had the TRPV-1. After exposing the two groups to capsaicin, the one lacking TRPV-1 showed to be insensitive to the irritant substance, as expected. However, surprisingly the same group showed a high insensibility to temperatures above 43ºC, which is when pain is normally sensed. This result implied that the same receptor for the chili peppers irritant molecule is the same receptor for sensing high temperature. So when neurons bind capsaicin, the brain interprets the signal produced as an increase in temperature, like something “hot” is touching your tongue.

Additionally, neurons possess certain receptors called TRM8, which are activated by low temperatures (> 12 ºC). These receptors also happen to be sensitive to menthol, the compound found in high concentration within peppermint and used in products like mouthwashes and toothpaste. By then using the same mechanism for associating capsaicin and hot temperatures, the menthol bond to a TRM8 receptor sends a signal that tricks the brain; therefore, by just the taste of mint, makes you feel cool!

References:

http://student.biology.arizona.edu/honors2007/group12/home12.html

Sven-Eric Jordt, David D McKemy and David Julius, Current Opinion in Neurobiology, 2003, 13:487–492.

M. J. Caterina, A. Lefßer, A. B. Malmberg, W. J. Martin, J. Trafton, K. R. Petersen-Zeitz, M. Koltzenburg, A. I. Basbaum, D. Julius, Science, 2000, 288, 306-313

Eyjafjallajökull: “the little volcano that could”

Eyjafjallajökull? Can you pronounce it? Apparently, it’s: “AY-uh-fyat-luh-YOE-kuutl(-uh).” If that helps, good for you! Even after hearing an Iceland native pronounce it, I still can’t manage to wrap my tongue around that many syllables.
First, a little geography – Iceland, sometimes called the land of fire and ice, is an island in the North Atlantic Ocean between Greenland and northern Europe. It’s about the size of Virginia with a population slightly less than that of Virginia Beach. At 65°N latitude, the subpolar climate would be brutally cold if the Gulf Stream ocean current did not moderate temperatures somewhat; Iceland's average July high is around 57°F and its average January high is around 34°F.
So why does Iceland have so many active volcanoes? Two factors. First, the island is bisected by the Mid-Atlantic Ridge, the boundary between the North American plate and the Eurasian plate. The two plates diverge along this boundary, forming new crust along the ridge; therefore, Iceland is continually getting bigger. In addition, geologists believe Iceland is over a hot spot, an area of rising lava below the earth’s crust. Hot spots often breed volcanoes and sometimes new islands; the islands of Hawaii were formed over a hot spot in the Pacific. However, the Hawaiian Islands are in the middle of a drifting tectonic plate, rather than between plates, so an island in the Hawaiian chain will eventually drift away from the hot spot and a new island will begin to form over the hot spot. As long as Iceland straddles the mid-ocean ridge and the hot spot remains under the ridge, Iceland will remain one of the most active volcanic regions on earth.
Eyjafjallajökull may have cooled slightly, but today’s strong tremors indicate that the eruption is not over yet. Also scientists are concerned that Katla, a much bigger and more active volcano, may erupt next. Past evidence indicates that when Eyjafjallajökull erupts, Katla follows. Katla’s eruption could be much more explosive, and Katla is overdue. Explosive eruptions often send ash and other matter into the upper atmosphere where they stay for long periods often causing dramatic global climate change.
Now that Eyjafjallajökull has calmed somewhat, we can take a look at the impact and subsequent ripple effect this eruption caused around the globe. The most obvious: Eyjafjallajökull’s ash cloud grounded planes all over Europe, inconveniencing travelers who were stranded in airports for days and costing the airline industry over $1 billion in lost revenue. In addition, the eruption affected the economy and citizens of countries near and not-so-near the island of Iceland.
Kenya - thousands of laborers are out of work; flowers and produce cannot be shipped to Europe. 10 million flowers, mostly roses, have been thrown away.
Ghana – pineapple and pawpaw farmers’ incomes are suffering due to lack of refrigeration at Ghana’s capital airport.
Japan – Nissan stopped production at two of its plants on Wednesday because they ran out of tire pressure sensors due in from Ireland.
Australia – a family from Britain saved for two years to make a trip to Australia, then the hotel more than doubled the rates (because they could). The frustrated family moved to a hostel.
Iraq and Afghanistan – medical evacuation flights are taking up to 8 hours longer than usual because they cannot fly back to the US out of Germany but instead must fly out of Spain.
United States – the airline slowdown cost the US economy $650 million and affected about 6000 American jobs. BMW reduced production at its Spartanburg, SC plant due to lack of supplies from Germany. Brides in New York had no Dutch flowers (tulips, peonies, or daffodils) for their weddings. Marathoner David Gray missed his second consecutive Boston marathon while stuck in a hotel in Brussels (the first was due to injury).
If Katla erupts, the impacts could be even greater…

Thanks to CBS News for the international anecdotes and to the Associated Press for the photo.
For more info, go to http://www.guardian.co.uk/environment/blog/2010/apr/20/iceland-volcano-your-questions-answered
And for great volcano pix, go to - http://www.boston.com/bigpicture/2010/04/icelands_disruptive_volcano.html

Flying Squirrels Play Baseball?

Play ball! It’s Opening Day at the Diamond! Today Richmond welcomes its new baseball team, the Richmond Flying Squirrels, with a sold-out Diamond! So why Flying Squirrels???
Well, flying squirrels are rather cute! And Virginia boasts 2 species: the Northern Flying Squirrel, whose range includes a few isolated high altitude locations (it is more common in states farther north) and the Southern Flying Squirrel, whose range includes the entire state except its westernmost tip.
Flying squirrels are nocturnal so they are rarely seen by humans. Their eyes are quite large to help them see in the dark. They spend most of their time high up in trees but come to the ground occasionally to hunt for food. Their predators are creatures of the night, including owls, raccoons, weasels, coyotes and domestic cats.
Flying squirrels do not actually fly but glide. Gliding is facilitated by the patagium, a flap of skin between the front and hind legs, which acts as a sort of parachute when the squirrel jumps from a tree. The patagium contains muscles that hold it taut while gliding and keep it close to the body while at rest. The fur on the patagium is short to reduce air flow resistance or drag.
A flying squirrel’s diet includes mast crops (acorns, hickory nuts, pecans, walnuts), seeds, insects, snails, plant buds and flowers, fruit, fungi, tree bark and sap. Flying squirrels are “scatter hoarders,” often stashing small quantities of nuts in tree notches and in shallow digs under leaf litter and logs. Southern Flying Squirrels are also known to store larger quantities of nuts and other “goodies” in "larder cavities."
For shelter, flying squirrels use several types of nests. The most common nest type is the cavity nest, often a natural tree cavity or a tree cavity made and then abandoned by another animal. In summer, flying squirrels often use outside nests called “dreys,” which are usually made of plant material. Aggregate nests are often used in winter. Flying squirrels are the most social of all squirrel species and they do not hibernate; therefore, to keep warm in winter, they will gather in a communal or aggregate nest for warmth. Other nesting sites may include birdhouses, stacked firewood and attics. We had flying squirrels living in our attic for a couple of winters until we figured out how to humanely “evict” them, but that is a story for another day…

Most of this material came from http://www.flyingsquirrels.com/ , an excellent source for almost anything you’d like to know about flying squirrels. Information more specific to Virginia can be found at http://www.dgif.virginia.gov/wildlife/information/?s=050068 and http://www.dgif.virginia.gov/wildlife/information/?s=050065.

Pizza Garden

I've just returned from visiting our first two of five Richmond Public Schools participating in the Science Museum of Virginia's pizza garden. Today, John B. Cary Elementary and Maymont Elementary planted basil in their classrooms. When they've finished their SOL testing in early June, they'll visit the museum to transplant their seedlings into our on-site pizza garden. Bellevue Elementary, William Fox Elementary and Linwood Holton Elementary will also participate in this endeavor. Third grade students from these schools will be planting hot peppers, tomatoes and green peppers respectively.

It is the museum's hope that this project will inspire a new generation of gardeners. This project will hopefully allow kids to see where everday food items (such as pizza) come from. Perhaps it will even inspire some of them to pay more attention to their diet as well! I had several students tell me today that they had never grown anything from seed, so it's very exciting to be a part of that "first" in their lives.

Why are we having so many earthquakes?

Another earthquake – this time in Turkey. Earthquakes are certainly in the news. Fortunately, earthquakes are not a frequent occurrence in Virginia, but they do happen. Do you remember the one on December 9, 2003? It measured 4.5 on the Richter scale; its epicenter was just south of the James River in Powhatan County. I remember it well; it was quite an experience!
With all the recent reported earthquakes, you might wonder if they are related; that is, could the earthquake in Haiti cause the one in Chile, which might then cause the one in Turkey and so on? Here are some frequently-asked earthquake questions and their “myth-busting” answers:
1. Why are we having so many earthquakes?
Although it may seem like it, we are not having more earthquakes than usual. Earthquakes do occur in clusters, though, but clusters are predicted by statistics and do not mean the quakes are related. (Also, there are long periods when earthquakes are not in the news, but that is not considered unusual.) Several factors make it appear earthquake frequency has increased:
(a) Better reporting – in 1931 there were 350 stations reporting earthquakes; now there are 4000. Current stations locate an average of 50 quakes per day. In general, there are about 18 major quakes per year (7.0-7.9) and one great one (8.0+).
(b) Increasing global population makes for more casualties and thus more reporting.
(c) Better communication around the globe allows us to know about earthquakes quickly so it’s timely and newsworthy.
2. Can scientists predict earthquakes?
Unfortunately, they do not know how. However, using scientific data, they can calculate the probability one will strike in the future.
3. Can animals predict earthquakes?
From the days of ancient Greece, there have been reports of animals behaving strangely just before an earthquake. Scientists have investigated and cannot find consistent and reliable animal behavior prior to an earthquake.
4. Is there a particular time of day that earthquakes tend to occur? Do they occur more often at certain time of the month or year?
Earthquakes are equally probable at all times of the day, month or year.
5. Can the ground open up during an earthquake?
In an earthquake, the earth moves along a fault not perpendicular to it, so the ground would not open up. If it did, there would be no friction, thus no quake. Landslides and other ground failures caused by earthquakes can cause crevasses and depressions to form, however.
6. Will California eventually fall into the ocean?
No. The Pacific Plate runs into the North American Plate at the San Andreas Fault. The Pacific Plate is moving northwest relative to the North American Plate at a rate of 46 mm/year (about the rate your fingernails grow). California will not fall into the ocean, but LA may one day have a very cold climate – it is heading toward Alaska.
The above information came from the US Geological Survey. Want to know more? Go to http://earthquake.usgs.gov/earthquakes.