April 30, 2008, 5:42 PM CT

Did dust storms make the Dust Bowl drought worse?

The Dust Bowl drought of the 1930s was one of the worst environmental disasters of the Twentieth Century anywhere in the world. Three million people left their farms on the Great Plains during the drought and half a million migrated to other states, almost all to the West. But the Dust Bowl drought was not meteorologically extreme by the standards of the Nineteenth and Twentieth Centuries. Indeed the 1856-65 drought may have involved a more severe drop in precipitation. It was the combination of drought and poor land use practice that created the environmental disaster.

Much of the Plains had been plowed up in the decades before the 1930s as wheat cropping expanded west. Alas, while natural prairie grasses can survive a drought the wheat that was planted could not and, when the precipitation fell, it shriveled and died exposing bare earth to the winds. This was the ultimate cause of the wind erosion and terrible dust storms that hit the Plains in the 1930s. There had never been dust storms like these in previous droughts. In the worst years of the 1930s on as a number of as a quarter of the days dust reduced visibility to less than a mile. More soil was lost by wind erosion than the Mississippi carried to the sea. Eventhough the numbers are not known, hundreds if not thousands of Plains residents died from 'dust pneumonia', a euphemism for clogging of the lungs with dirt. For wonderful books on the topic see Worster (1979, Dust Bowl: The Southern Plains in the 1930s) and Egan (2006, The Worst Hard Time)......... Posted by: Tyler      Read more         Source

April 30, 2008, 5:20 PM CT

Heat transfer between materials

Managing heat is a major challenge for engineers who work on devices from jet engines to personal electronics to nano-scale transistors.

A team led by a University of Michigan mechanical engineer has received a five-year, $6.8-million grant from the Air Force to examine this problem, which is a barrier to more powerful, efficient devices.

Led by Kevin Pipe, an assistant professor in the Department of Mechanical Engineering, the team has received a Multidisciplinary University Research Initiative (MURI) award from the Air Force Office of Scientific Research. The research group includes nine researchers and engineers from three universities, including Brown University and the University of California at Santa Cruz.

"The processes by which heat is transferred at interfaces between different materials are poorly understood," Pipe said. "But in a number of systems, the ability to either efficiently transfer or block heat flow from one material to another is critically important to performance and reliability".

Inefficient heat flow is a main roadblock in the development of lasers and transistors that can attain higher powers. Conversely, blocking heat exchange can dramatically improve the efficiency of thermoelectric energy conversion for compact power sources......... Posted by: Kevin      Read more         Source

April 29, 2008, 8:37 PM CT

Mini-Origami: ISI Folds Up Tiny Packages for Drug Delivery

Scientists at the USC Information Sciences Institute have demonstrated a way to manufacture miniscule containers that might be used to deliver precise micro- or even nano- quantities of drugs.

As per ISI project leader Peter Will, who is a research professor in the Viterbi School of Engineering, the new technique, described in a paper in the Journal of Micromechanics and Microengineering, is a two-step process.

Part one is the creation of flat patterns, origami, of exactly the fold up shapes familiar to kindergarten children making paper pyramids, cubes or other solids, except that these are as small as 30 micrometers on a side. (1 inch = 25,400 micrometers)(see illustration).

Instead of paper, the USC scientists created the patterns in polysilicon sitting on top of a thin film of gold, using a well- established commercial silicon wafer process called PolyMUMPs. The next step was clearing the polysilicon off the hinge areas by etching.

When the blanks were later electrocoated with permalloy to make them magnetic, the photomask used left hinge areas uncoated, to make sure they were the places that folded.

Then the folding had to be accomplished. First the scientists bent the hinges by application of magnetic force. Then water pressure and capillary forces generated by submerging the tiny blanks in water, and drying them off did the final folding into shape......... Posted by: Kevin      Read more         Source

April 29, 2008, 8:17 PM CT

New 3-D test method for biomaterials 'flat out' faster

A novel, three-dimensional (3-D) screening method for analyzing interactions between cells and new biomaterials could cut initial search times by more than half, scientists from the National Institute of Standards and Technology (NIST) and Rutgers University report in the new issue of Advanced Materials.* The technique, an advance over flat, two-dimensional screening methods, enables rapid assessment of the biocompatibility and other properties of materials designed for repairingor even rebuildingdamaged tissues and organs.

In what may be a first, the team demonstrated how to screen cellmaterial interactions in a biologically representative, but systematically altered, 3-D environment. The pivotal step in the experiment was the collaborators success in making so-called libraries of miniature porous scaffolds that are bone-like in structure but vary incrementally in chemical composition. Knowing how changes in scaffold ingredients influence cell responses, scientists can devise strategies for developing biomaterials optimized for particular therapies and therapys.

Until now, attempts to accelerate screening of candidate biomaterials have used flat films and surfaces. (See, for example, Designer Gradients Speed Surface Science Experiments, Tech Beat June 8, 2006. http://www.nist.gov/public_affairs/techbeat/tb2006_0608.htm#designer ) Along with other shortcomings, these two-dimensional substrates are neither consistent with cells normal 3-D environment inside the body nor with the most common intended use of biomaterials: creating scaffolds to encourage the growth of cells into functional 3-D tissues and organs......... Posted by: Kevin      Read more         Source

April 28, 2008, 8:31 PM CT

First nanoscale image of soil

A handful of soil is a lot like a banana, strawberry and apple smoothie: Blended all together, it is hard to tell what's in there, particularly if you have never tasted the fruits before.

But when you look at soil's organic carbon closely, it has an incredible variety of known compounds. And looking closely is exactly what Cornell scientists have done for the first time -- at a scale of 50 nanometers (1 nanometer equals the width of three silicon atoms). Until now, handfuls of soil humus (or the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms) looked remarkably similar.

As per a research studyreported in the recent issue of Nature Geoscience, knowing the structure and detailed composition of soil carbon could provide a better understanding of the chemical processes that cycle organic matter in soil. For example, the research may help researchers understand what happens when materials in the soil get wet, warm or cool and how soils sequester carbon, which has implications for climate change.

"There is this incredible nanoscale heterogeneity of organic matter in terms of soil," said Johannes Lehmann, a Cornell associate professor of crop and soil sciences and lead author of the study. "None of these compounds that you can see on a nanoscale level looks anything close to the sum of the entire organic matter."........ Posted by: Kevin      Read more         Source

April 28, 2008, 8:27 PM CT

Satellite Mission To Map Earth's Water Cycle

MIT Professor Dara Entekhabi will lead the science team designing a NASA satellite mission to make global soil moisture and freeze/thaw measurements, data essential to the accuracy of weather forecasts and predictions of global carbon cycle and climate. NASA announced recently that the Soil Moisture Active-Passive mission (SMAP) is scheduled to launch December 2012.

At present, researchers have no network for gathering soil moisture data as they do for rainfall, winds, humidity and temperature. Instead, that data is gathered only at a few scattered points around the world.

"Soil moisture is the lynchpin of the water, energy and carbon cycles over land. It is the variable that links these three cycles through its control on evaporation and plant transpiration. Global monitoring of this variable will allow a new perspective on how these three cycles work and vary together in the Earth system," said Entekhabi, director of the Parsons Laboratory for Environmental Science and Engineering in MIT's Department of Civil and Environmental Engineering.

"Additionally because soil moisture is a state variable that controls both water and energy fluxes at the land surface, we anticipate that assimilation of the global observations will improve the skill in numerical weather prediction, particularly for events that are influenced by these fluxes at the base of the atmosphere," he said......... Posted by: Brooke      Read more         Source

April 28, 2008, 5:20 PM CT

Copper nanowires grown by new process

A new low-temperature, catalyst-free technique for growing copper nanowires has been developed by scientists at the University of Illinois. The copper nanowires could serve as interconnects in electronic device fabrication and as electron emitters in a television-like, very thin flat-panel display known as a field-emission display.

We can grow forests of freestanding copper nanowires of controlled diameter and length, suitable for integration into electronic devices, said Kyekyoon (Kevin) Kim, a professor of electrical and computer engineering.

The copper nanowires are grown on a variety of surfaces, including glass, metal and plastic by chemical vapor deposition from a precursor, said Hyungsoo Choi, a research professor in the Micro and Nanotechnology Laboratory and in the department of electrical and computer engineering. The patented growth process is compatible with contemporary silicon-processing protocols.

The scientists describe the nanowires, the growth process, and.

a proof-of-principle field-emission display in a paper accepted for publication in the journal Advanced Materials, and posted on its Web site.

Typically, the nanowires of 70 to 250 nanometers in diameter are grown on a silicon substrate at temperatures of 200 to 300 degrees Celsius and require no seed or catalyst. The size of the nanowires is controlled by the processing conditions, such as substrate, substrate temperature, deposition time and precursor feeding rate. The columnar, five-sided nanowires terminate in sharp, pentagonal tips that facilitate electron emission......... Posted by: Kevin      Read more         Source

April 28, 2008, 4:54 PM CT

'New' ancient Antarctic sediment reveals climate change history

Recent additions to the premier collection of Southern Ocean sediment cores at Florida State Universitys Antarctic Marine Geology Research Facility will give international researchers a close-up look at fluctuations that occurred in Antarcticas ice sheet and marine and terrestrial life as the climate cooled considerably between 20 and 14 million years ago.

FSUs latest Antarctic sediment core acquisition was extracted from deep beneath the sea floor of Antarcticas western Ross Sea, the Earths largest floating ice body. The new samples -- segments of a drill core that measures more than 1,100 meters in length -- offer an extraordinary stratigraphic record of sedimentary rock from the Antarctic continental margin that documents key developments in the areas Cenozoic climatic and glacial history.

By correlating that stratigraphic record with existing data and climate and ice sheet models, researchers from FSU and around the world expect to learn how local changes in the Southern Ocean region relate to regional and global climate events.

Such knowledge will significantly increase our understanding of Antarcticas potential responses to future global-scale climate changes, said Sherwood W. Wise, Jr., an FSU geological science professor and co-principal investigator at the Antarctic Marine Geology Research Facility. This is critical for low-lying regions such as Florida that could be directly affected by the future behavior of the Antarctic Ice Sheets and any resulting sea-level changes. By studying these glacial records of the past, geologists and climatologists seek to better predict the future......... Posted by: Tyler      Read more         Source

April 24, 2008, 10:28 PM CT

Biodiversity Is Crucial to Ecosystem Productivity

In the first experiment involving a natural environment, researchers at Brown University have shown that richer plant diversity significantly enhances an ecosystem's productivity. The finding underscores the benefits of biodiversity, such as capturing carbon dioxide, a main contributor to global warming.

Osvaldo Sala, director of the Environmental Change Initiative and the Sloan Lindeman Professor of Biology at Brown, and Pedro Flombaum, a postdoctoral research associate in the Department of Ecology and Evolutionary Biology at Brown, said the results confirmed tests charting how biodiversity affects aboveground plant productivity in artificial ecosystems. Aboveground plant productivity (ANPP) is the amount of biomass, or organic material, produced by plant growth.

But the Brown team also learned that the connection between plant species richness - the number of plant species in a unit of area - and ANPP in a natural ecosystem was greater than had been expected. What that means, the scientists wrote in a paper published online this week in the Proceedings of the National Academy of Sciences, is that the greater the number of plant species, the more productive the ecosystem.

On the other hand, species loss has a decidedly negative impact on ecosystems. This is particularly true in light of the role ecosystems play in capturing the global warming gas carbon dioxide: The fewer the plant species in a given natural environment, the less carbon dioxide they capture......... Posted by: Tyler      Read more         Source

April 24, 2008, 9:37 PM CT

Geological faults threaten Houston

HOUSTON, April 24, 2008 After finding more than 300 surface faults in Harris County, a University of Houston geologist now has information that could be vitally useful to the regions builders and city planners.

This information the most accurate and comprehensive of its kind was discovered by Shuhab Khan, assistant professor of geology, and Richard Engelkemeir, a geology Ph.D. student, using advanced radar-like laser technology. Eventhough geologists have long known of the existence of faults in Southeast Texas, only recently have UH scientists produced a comprehensive map pinpointing the locations of the faults. A Houston-area map showing active surface faults is available at http://www.uh.edu/news-events/archive/nr/2008/04april/geological-faultsph.html.

While the ground moving beneath Houstonians feet is not felt at the magnitude of recent earthquakes in San Antonio and Illinois, this shaky ground could mean trouble for buildings, roads and pipelines located on one of these hundreds of faults traversing the regions surface.

These shifting fault lines originated millions of years ago during the formation of the Gulf of Mexico, Khan said. While they are not the kinds that wreak havoc in earthquake-prone California and now the Midwest, they can move up to 1 inch a year, causing serious damage over the course of several years to buildings and streets that straddle a fault line. Additionally, structures on the subsiding side of the fault line could be more susceptible to flooding due to the lower elevation over time......... Posted by: Tyler      Read more         Source