TechBlog

Brent Christner, LSU professor of biological sciences, in partnership with colleagues in Montana and France, recently found evidence that rain-making bacteria are widely distributed in the atmosphere. These biological particles could factor heavily into the precipitation cycle, affecting climate, agricultural productivity and even global warming. Christner and his colleagues published their results on Feb 29 in the journal Science.

Brent Christner, LSU assistant professor of biolo-

gical sciences, collecting precipitation samples in Antarctica. (Credit: Brent Christner Continue reading ‘Evidence Of ‘Rain-making’ Bacteria Discovered In Atmosphere And Snow’ »

A national team of scientists led by experts at Durham University are embarking on one of the UK’s largest ever research projects into photovoltaic (PV) solar energy.

The £6.3million PV-21 programme will focus on making thin-film light absorbing cells for solar panels from sustainable and affordable materials.

The four-year project, which begins in April (2008), is being funded by the Engineering and Physical Sciences Research Council (EPSRC) under the SUPERGEN initiative.

Eight UK universities, led by Durham and including Bangor, Bath, Cranfield, Edinburgh, Imperial College London, Northumbria and Southampton, are involved in the project.

Continue reading ‘Durham University Leads UK Research Project Into Cheaper Solar Energy’ »

Berkeley, CA — As structures made of metal get smaller — as their dimensions approach the micrometer scale (millionths of a meter) or less — they get stronger. Scientists discovered this phenomenon 50 years ago while measuring the strength of tin “whiskers” a few micrometers in diameter and a few millimeters in length. Many theories have been proposed to explain why smaller is stronger, but only recently has it become possible to see and record what’s actually happening in tiny structures under stress.Andrew Minor, of the Materials Sciences Division in the Department of Energy’s Lawrence Berkeley National Laboratory, with colleagues from Hysitron Incorporated and the General Motors Research and Development Center, used the In Situ Microscope at the National Center for Electron Microscopy (NCEM) to record what happens when pillars of nickel with diameters between 150 and 400 nanometers (billionths of a meter) are compressed under a flat punch made of diamond. The transmission electron microscope is equipped so that samples can be stressed, measured, and videotaped while being observed under the electron beam.

“What controls the deformation of a metal object is the way that defects, called dislocations, move along planes in its crystal structure,” Minor says. “The result of dislocation slip is plastic deformation. For example, bending a paper clip causes its trillions of dislocations per square centimeter to tangle up and multiply as they run into one another and slide along numerous slip planes.”

In general, mechanical deformation tends to increase the number of dislocations in a material. But for small-scale structures, with a much greater proportion of surface area to volume, the process can be very different. The videotaped images from the electron microscope helped the researchers understand why nanoscale nickel pillars are so strong by allowing them to observe changes in the microstructure of the pillars during deformation — including a never-before-seen process the researchers dubbed “mechanical annealing.” (In bulk materials, annealing, a treatment that reduces the density of defects, is usually accomplished by heating.)

Continue reading ‘Smaller Is Stronger — Now Scientists Know Why’ »