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February 13 2012
MeinSueppchen via
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02mydafsoup-01February 09 2012
Augmented-reality device promises astronauts instant medical expertise
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wonderfulnature via science
The Cliff of the Two-Dimensional World
Babak Anasori, Michael Naguib, Yury Gogotsi, Michel W. Barsoum
Drexel University
This landscape, which looks like a red-rock bluff straight out of Utah, isn't a geologic feature. Instead, it's a nanostructured material made from ultrathin layers of titanium-based compounds and seen under an electron microscope.
To construct the small outcropping, Babak Anasori and colleagues at Drexel University in Philadelphia used a technique called exfoliation. They placed Ti3AlC2 powders in a solution of hydrofluoric acid and stripped away the aluminum atoms. What remained were stacked layers of Ti3C2, seen here in false color, resembling stratigraphic mineral layers. These exfoliated layers, which the team dubbed MXenes, are so thin they are two-dimensional. In other words, each strip is only five atomic layers thick. The team is the first to render such materials in 2D. The MXenes could be used in energy storage devices, sensors, solar cells, and other applications, the team writes. And they could give the majesty of Arches National Park in Utah some nanoscale competition.This landscape, which looks like a red-rock bluff straight out of Utah, isn't a geologic feature. Instead, it's a nanostructured material made from ultrathin layers of titanium-based compounds and seen under an electron microscope.
science via
Species5618Rapid Visual Inventory & Comparison of Complex 3D Structures
Graham Johnson, TSRI & grahamj.com; Andrew Noske, NCMIR; Bradley Marsh, IMB
In this video, Ph.D. animator Graham Johnson of the Scripps Research Institute in San Diego, California, and colleagues take the normally jumbled pieces of a mouse pancreatic cell and stack them into neat piles. It's an organizational feat sure to please cleanliness-loving scientists. But the visualization also gives researchers and students a new look at the abundances and relative sizes of organelles, from mitochondria to insulin granules. “The cell is a lot more complicated-looking than most people think of it,” Johnson says. “We wanted to clarify it.”
The video opens with a 3D model of a chaotic cell taken from the pancreas as seen in its natural state. Thousands of irregularly shaped organelles huddle around a central and bean-shaped nucleus. Then, Johnson and colleagues start to spring-clean. Drawing on data from the lab of team member Bradley Marsh, a cell biologist at the University of Queensland in Brisbane, Australia, the researchers simplify the cell's components and then sort them by organelle. They first group together the mitochondria (green) and insulin granules (blue), then clump these and other organelles together to form uniform columns and rows for easy comparison.
The resulting image looks less like a cell and more like a 3D abacus. But it also displays the relative volumes of these cellular factories and compartments. Surprisingly, for instance, mitochondria occupy only 7% of the cell volume, which is hard to see from the raw cell alone.
This visualization, Johnson says, represents the middle ground between the two standard depictions of the cell: the natural, or chaotic, cell and the cartoonish, or textbook, cell. That became clear when the team showed the video to school kids in Australia: “When they could see the random, video-game-looking cell morph into the type of cell that their teacher had been presenting to them from textbooks and the Internet,” he says, “they really got excited.”
The team “manages to weave into one short video an unbelievable amount of information,” says challenge judge Tierney Thys. “From morphology to volumetrics and beyond, it presents completely different data sets in a seamless, accessible, and aesthetic manner.”
scienceHigh-Density Energy Storage Using Self-Assembled Materials
Christopher E. Wilmer, Omar K. Farha, Patrick E. Fuller
Northwestern University
In one of the most famous scenes in 2001: A Space Odyssey, futuristic spaceships spin and twirl to The Blue Danube by Johann Strauss. Christopher Wilmer and colleagues at Northwestern University in Evanston, Illinois, kick off their video with that same whimsical waltz. Instead of spinning spaceships, however, their visualization shows hundreds of molecules floating around and joining to each other to form solid crystals. Wilmer, a big fan of Stanley Kubrick's 1968 film, had for years looked for an “excuse” to dramatize his research using Strauss's music: Kubrick “wanted to convey the majesty of space engineering,” Wilmer says. “I also wanted to convey the majesty of self-assembly on the molecular scale.”
Wilmer's work focuses on how gaseous fuel molecules such as methane cling to solids. Unlike liquid gasoline, gaseous methane—a much cleaner energy source—is tough to squeeze into automobile gas tanks. But when scientists add special porous crystals to those tanks, methane begins to cluster inside the pores, greatly increasing the gas's density. His team employs computer algorithms to screen thousands of possible crystal structures to identify the ones best suited to concentrating methane and other gases. The topic isn't simple, but, with the help of this playfully animated video, Wilmer says he and his labmates have finally been able to explain their research to relatives. The homage to a sci-fi classic doesn't hurt.
scienceFebruary 04 2012
Forscher haben einen Herzschrittmacher gebaut, der ...
fefeJanuary 29 2012
science via
mondkroeteJanuary 28 2012
Es galt mal als technisch schwierig bis unmöglich den Flügelschlag eines Vogels funktionabel nachzubauen.
January 26 2012
If you roll a circle inside one 3 times its size, it will actually trace out a 4 pointed star shape called an Astroid (this shape is traced out in the animation in orange). But what if inside the smaller circle, there is an even smaller one tracing out a smaller Astroid? This animation shows the intricate shape that is generated by adding the effects of all the Astroids. [code]
January 17 2012
towo via
EineFragevonStilHow I became we, which became I again
Most life on Earth exists as single cells. But the ones comprised of many cells, from the tiniest ant to the tallest tree, have had an undeniable impact on our planet. These ‘multicellular’ creatures evolved from single-celled ancestors at least 25 times throughout Earth’s history. These transitions are arguably some of the most significant in evolution, but we only have a vague understanding of how they happened.
It probably went a bit like this. A single cell split into two and rather than going their separate ways, they stayed together. This happened again and again. Eventually, the groups of individual cells became individuals of grouped cells, evolving as a unit. It’s the story of how I became we, and how we became I again.
In an elegant new experiment, William Ratcliff from the University of Minnesota has shown that this story could have been a surprisingly quick one. In his laboratory, he successfully nudged single-celled brewer’s yeast into multicellular clusters, within just a few months. The clumps of cells evolved as one. They even developed a primitive division of labour, with some of them deliberately dying so that the others could grow and reproduce.
I’ve written about this discovery for Nature News, so head over there to read the full take.
Over here, I want to emphasise that Ratcliff’s work isn’t meant to directly recap how multicellularity evolved in any particular group. It’s meant to look at the general principles that govern this transition. Richard Lenski, another evolutionary biologist famous for his work on bacteria, adds, “They’re not saying that it happened in nature the way it happened in their experiments. The point of experimental evolution is to test hypotheses and watch evolution in action, not to replicate a specific event from some point in the distant past.”
Ratcliff’s work shows that this transition, from one cell to many, could have happened much more quickly than anyone expected. To set his yeast along that path, all he had to do was to let them sink. In a tube of liquid, clumps of yeast will settle faster than single cells. By picking and growing the cells that sunk quickest, Ratcliff selected for those that tend to stick together.
Many single-celled microbes clump together to create multicellular entities, from predatory bacteria like Mxyococcus to slime moulds like Dictyostelium. Yeast cells sometimes do this too – they form clumps called ‘flocs’. Ratcliff says, “My original guess was that we flocculation would evolve, but that’s not what we saw.”
Within 60 days, the yeast had evolved clusters of many cells, radiating out into microscopic ‘snowflakes’. Unlike flocs, these flakes weren’t clumps of unrelated cells. They were formed by genetically identical cells that grew and divided, but never separated. That’s similar to what happens in our own bodies. A single cell – a fertilised egg – grows and divides into trillions of cells that all stay together.
Many other studies have shown that sticking together would have provided benefits for single cells. “We can be fairly confident that, early on, large size was beneficial”, says Ratcliff. In a cluster, single cells are better at ahttp://dx.doi.org/10.1073/pnas.1115323109
Images and video by Will Ratcliff
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