Archive for June 2011

Ocean Currents–The Big Unknowns

June 30th, 2011 by Sarah Pryputniewicz

Scientists have known for a long time that ocean currents affect climate.  The big unanswered question is how ocean currents change during the periods of greatest change–from ice ages to periods of global warming.

During the Eocene period, 38 million years ago, the Antarctic had a temperate climate.  What is now the midwest United States was covered in tropical jungles.  The temperature differential during that last warm period was much smaller than it is today, when Antarctica is a frozen tundra.

New research suggests that the Antarctic Circumpolar Current (ACC), an ocean current that surrounds Antarctica, played a major role in the Eocene climate shift and that ACC formation played a vital role in the formation of modern ocean structure.  During the Eocene, when temperature differences were not as large between the poles and the midlatitudes, ocean currents were weaker than they are today.  Today, the ACC is considered the most significant ocean current, thermally isolating Antarctica from the rest of the planet, keeping warm surface waters away from the frozen ice sheets.

“What we have found is that the evolution of the Antarctic Circumpolar Current influenced global ocean circulation much earlier than previous studies have shown,” said Katz, who is assistant professor of earth and environmental science at Rensselaer.  “This finding is particularly significant because it places the impact of initial shallow ACC circulation in the same interval when the climate began its long-term shift to cooler temperatures.”

Just how did this shift in ocean currents happen?  That’s not yet understood.

Scientist Miriam Katz points out, “By reconstructing climates of the past, we can provide a science-based means to explore or predict possible system responses to the current climate change.”  As always, science requires more study to start filling in the blanks of the big unknowns!

http://www.sciencedaily.com/releases/2011/05/110526141406.htm

Wanted: Cause of the End of “Snowball Earth”

June 27th, 2011 by Sarah Pryputniewicz

A new study has been published disproving the previous explanation for the end of the Marinoan ice age, also known as “Snowball Earth.”  That ice age ended abruptly about 600 million years ago.

The debunked explanation stated that methane bubbled up from the oceans and was consumed by microbes, which released carbon dioxide into the atmosphere, warming the Earth.  Earlier scientists had interpreted “bubbles” in the rocks as evidence of the ancient microbial activity.

A new study on those rocks showed that they were formed under very high temperatures–temperatures at which no microbes are known to survive.  In addition, better dating of the rocks showed that the “bubbles” were formed millions or tens of millions of years after the end of the ice age.

So scientists still don’t have an explanation for the end of “Snowball Earth.”  But they do know a couple of things that didn’t cause the end of the ice age.

As scientists come up with new explanations for the end of the ice age, those explanations will be tested by other scientists.  When explanations can be disproved with evidence, science moves forward.  We may never discover the true cause of the end of “Snowball Earth,” but one thing’s for sure–we’ll know a lot more about how the Earth works by trying to craft a good explanation.  That’s the way science works!

http://www.sciencedaily.com/releases/2011/05/110525141540.htm

The Molecular Workbench wins a SPORE Award from the Science Magazine

June 23rd, 2011 by Charles Xie
The Science Magazine announced that the Molecular Workbench software has won a SPORE Award. The Science Prize for Online Resources in Education (SPORE) has been established by the American Association for the Advancement of Science to "encourage innovation and excellence in education, as well as to encourage the use of high-quality on-line resources by students, teachers, and the public."

Read our essay published in the Science Magazine.

Here is the AAAS announcement.

Trees to the (partial) rescue!

June 23rd, 2011 by Sarah Pryputniewicz

The Earth is getting warmer.  In warmer climes, decomposition occurs more quickly.  This releases more carbon dioxide into the atmosphere, leading to further warming.  But it needn’t get completely out of control–trees (and other plants) can come to the rescue!

A recent study in a central Massachusetts forest has shown that increased temperatures do indeed lead to increased decomposition.  But they also led to increased tree growth, partially offsetting the carbon dioxide release from decomposition.  Why?  The researchers found that nitrogen was also being liberated by the decomposition.

Because tree growth is limited by the availability of nitrogen, an increased supply of nitrogen results in increased growth.  The trees’ growth spurts result in some of the carbon dioxide being stored in the wood rather than being released into the atmosphere.  Unfortunately, the trees don’t take in ALL of the released carbon dioxide… trees to the (partial) rescue!

http://www.sciencedaily.com/releases/2011/05/110525120050.htm

Journal of Chemical Education features IR work

June 14th, 2011 by Charles Xie
The Journal of Chemical Education, published by the American Chemical Society, selects my paper "Visualizing Chemistry with Infrared Imaging" as the cover article on the July 2011 issue. The IR experiments presented in the paper were described as "captivating, intriguing, and thought-provoking."

Scientists have long relied on powerful imaging techniques to
see things invisible to the naked eye and thus advance
science. IR imaging is one of the few scientific imaging tools that can be easily used by anyone without complicated setup and calibration. And the price for an affordable IR camera has recently fallen below $900. This is a truly transformative tool that will empower students to learn and discover deep science from everyday life. I have shown many examples in this blog.

Every time I did some experiments with this wonderful tool, there was always something that surprised me. Even a humble leaf from a plant in my office shows a lot of things I don't really have a clue (I will blog more about biological applications later). Being a scientist, I intuitively feel that some of the surprises are not simple at all. Behind them there is very deep science that might have never been discovered before. It is a lot of fun to "crack" the scientific secrets in these surprises.

I hope every student would have the same opportunity to have fun with science as I have. Discovery should be an important part of science in schools.

Molecular simulation of self-assembly

June 4th, 2011 by Charles Xie
Molecular self-assembly is the process by which molecules adopt a defined arrangement without guidance or management from an outside source. This is one of the ways Mother Nature makes biomolecules that support life. For example, the amino acids of a protein self-assembles themselves and fold into a conformation determined primarily by its primary structure (the sequence of amino acids). It has inspired scientists to invent nanotechnology that is based on self-assembly.

Ab initio simulations of self-assembly involve many atoms and take a long time to run. For intermolecular self-assembly, most of the time the molecules' internal chemical structures do not change much. The Molecular Workbench has a coarse-grained model that simulates the soft, sticky character of the molecular surfaces, which is the most important factor during self-assembly. With this model, we have created a sequence of simulations for teaching the concept of self-assembly (see the images for an example). These simulations have been well-received and used in many classrooms as an introduction to nanotechnology.

You can explore these simulations with this applet.

Several of these simulations were used by a research scientist, Dr. Frank Balzer at NanoSYD of the University of Southern Denmark, in his presentation to illustrate the principles for nanofabrication laboratory experiments.