A TEXT POST

Monitoring diabetes with contact lenses

Researchers have developed a glucose sensor that fits like a contact lens onto the surface of the eye. It offers a convenient, less invasive alternative to traditional glucose monitoring, with a system that includes a glucose sensor, antenna, communication interface and readout circuitry.

Learn more …

A TEXT POST

Shaving nanoseconds from racing processors

The computer is one of the most complex machines ever devised and most of us only ever interact with its simplest features. For each keystroke and web-click, thousands of instructions must be communicated in diverse machine languages and millions of calculations computed.

Mark Hill knows more about the inner workings of computer hardware than most. As Amdahl Professor of Computer Science at the University of Wisconsin, he studies the way computers transform 0s and 1s into social networks or eBay purchases, following the chain reaction from personal computer to processor to network hub to cloud and back again.

"Our computers are very complicated and it’s our job to hide most of this complexity most of the time, because if you had to face it all of the time, then you couldn’t get done what you want to get done, whether it was solving a problem or providing entertainment," Hill said.

During the last four decades of the 20th century, as computers grew faster and faster, it was advantageous to keep this complexity hidden. However, in the past decade, the linear speed-up in processing power that we’d grown used to (often referred to as “Moore’s law”) has started to level off. 

In response, researchers like Hill and his peers in industry are reexamining the hidden layers of computing architecture and the interfaces between them in order to wring out more processing power for the same cost.

Learn more about Hill’s computer detective work and find out how he got started in computer science

A TEXT POST

Crystal of the Week: Tyrian purple!

Ah, springtime and the beautiful colors that return to our temporarily anemic post-winter world. Whether it’s in the tulips, daffodils and crocus or the delightful blue robin eggs, springtime represents color. In fact, for those who celebrate Easter, we can take the idea of “color” to great extremes as we find ways to turn modest chicken eggs into incredible creations. Some of the most ornate Easter egg designs, known as pysanka, actually come from Ukraine, where various layers of dye are applied using intricate patterns of wax-resist.

As we continue celebrating the International Year of Crystallography, it seemed only natural to think about tint as we chose our Crystal of the Week. That’s how we arrived at an ancient dye, Tyrian purple, which has been used to color garments, beads and many other textiles since the time of the Phoenicians. This shade of purple is also known as “royal purple” because at one point the dye was so expensive to produce that only royals could afford it. Just a few grams of powdered Tyrian purple requires tens of thousands of snails (yes, snails!), which explains why the dye was so expensive in antiquity, at one point costing its own weight in silver!

Beautiful as it may be, the most interesting aspect of Tyrian purple is its preparation. Like all mollusks, predatory sea snails secrete mucus aka “snail slime” to protect their tissues. Unlike other mollusks, the mucus of predatory sea snails (family name: Muricidae) can be distilled to a vivid purple dye. Although Tyrian purple preparations initially yield a liquid product, the water content can be evaporated to produce a purple powder, like that shown in the image. Of course, the granules in the powder are tiny crystals of the molecule that gives snail slime its purple hue. Many other common dyes are prepared similarly, where the crystalline powder is easily solubilized in water to dye clothing or other textiles or mixed directly into paints and plastics.

Unlike many dyes, which fade in sunlight, Tyrian purple actually becomes brighter and more vivid. In the early 1900s, the dye molecule was shown to be a type of organobromine compound. Other common organobromine compounds include some fire retardants, biocides and pharmaceuticals. And if you’ve ever taken analytical chemistry, you’re probably familiar with bromothymol blue, a common pH indicator.

But all of this talk of dyes and dye preparation actually brings us back to Easter eggs! Did you know that a variety of common kitchen items can be used to prepare different dyes in beautiful hues? Diluted grape juice delivers lavender, while red wine and the blossoms of violets yield a purple-blue. Boiled red cabbage, canned blueberries, or concentrated purple grape juice all create shades of blue. Boiled spinach can be used for green, while many spices (e.g., celery seed, ground cumin, ground turmeric) produce yellow when boiled. Coffee and tea can deliver brown hues. Orange can be obtained from paprika or cooked carrot. Beets and raspberries yield beautiful shades of pink. Otherwise, using more concentrated raspberry juice or pomegranate juice gives red.

Okay, so perhaps our obsession with dyes this week goes beyond crystallography, but the extended winter finds us craving color a bit more than usual this spring. Whether your favorite hues come from crystals, spices, vegetables or snails, may they brighten your springtime days.

 

A TEXT POST

Cosmic Slurp

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Somewhere out in the Universe, an ordinary galaxy spins. Then all of a sudden, a flash of light explodes from the galaxy’s center. A star orbiting too close to a black hole at the center of the galaxy has been torn apart by the force of gravity, heating up its gas and sending out a beacon of light to the far reaches of the Universe.

These beacons aren’t visible to the naked eye but in recent decades, with improved telescopes and observational techniques, scientists noticed that some galaxies that previously looked inactive would suddenly light up. 

Astronomers identified those as galaxies where a central black hole just ‘ate’ a star – an event called a “tidal disruption”.

“It’s like a black hole putting up a sign that says ‘Here I am,’” according to Tamara Bogdanovic, an astronomy professor at Georgia Tech.

Tidal disruptions are relatively rare cosmic occurrences. So far, only a few dozen of these characteristic flare signatures have been observed and deemed “candidates” for tidal disruptions. But as data from upcoming astronomical surveys becomes available to scientists, Bogdanovic believes this scarcity will change dramatically.

“As opposed to a few dozen that have been found over the past 10 years, now imagine hundreds per year - that’s a huge difference!” she said.

To someone analyzing data from a ground-based or a space-based observatory, a black hole swallowing a star would have a distinct signature. Applying a mix of theoretical and computer-based approaches, Bogdanovic has been trying to nail down what that signature would look like. Using National Science Foundation-funded supercomputers, Bodganovic and her collaborators recently simulated the dynamics of a tidal disruption with more precision than ever before, helping to explain what’s really going on near the gravitational edges of black holes.

Because scientists have control over these virtual experiments, they can repeat them, fast forward, or rewind to examine the tidal disruption process from many perspectives – all without getting sucked into a black hole. This in turn allows the researchers to figure out the physical processes at play.

“There are many situations in astrophysics where we cannot get insight into a sequence of events that played out without simulations,” Bogdanovic said. “We cannot stand next to the black hole and look at how it accretes gas. So we use simulations to learn about these distant and extreme environments.”

A VIDEO

Crystal of the Week: Silicon!

It’s the fifth annual National Robotics Week celebration, so those of us celebrating International Year of Crystallography realized we could not miss out!  After all, at the National Science Foundation, robots are a big deal! In conjunction with the U.S. Navy and Woods Hole Oceanographic Institution, our Division of Ocean Sciences helped fund recent upgrades and certifications for the retrofitted and rebooted Alvin underwater remotely operated vehicle. Research funded through NSF’s Directorate for Engineering embraces robots big and small: Bin He at University of Minnesota has developed a flying, mind-controlled craft, while Sarah Bergbreiter at the University of Maryland College Park designs insect-like robots smaller than a penny! And through the Advanced Technological Education program, NSF funds continuous improvements to associate degree-granting tech programs throughout the country where thousands of students at these schools learn how to build their own robots!

So how do crystals add up to robots?  It’s all in the chips — the microchips, that is.  For this week’s Crystal of the Week, we focused on the one material that almost all robots have in common – silicon-based microchips (a.k.a., the integrated circuit). Microchip fabrication technology has a long history of NSF support, and many major advances in microchip engineering were developed in American laboratories.

Pure silicon is an electronically neutral insulator (electrically non-conducting). Silicon has a similar electronic structure to carbon, which means the crystal structure of silicon takes on the same form as diamond, called “diamond cubic.” Large, cylindrical, high-purity single crystals of silicon are grown from molten vats of silicon (1500oC!) in a method called “pulling,” also known as the Czochralski process. Various improvements in this process have increased the diameter of the cylindrical silicon crystals that can be pulled from the melt from a once-standard 6 inches to a behemoth 12 inches! Once the large cylindrical crystals have been formed, they are sectioned into very thin slices (less than 1 mm), called silicon wafers. The resulting silicon wafers must be as much as 99.9999999% pure for many applications, including solar technology. However, microchip technology requires silicon wafers to have electrically conducting regions, in addition to the insulating pure silicon.

Those conducting regions are incorporated into silicon chips during subsequent processing steps. Two types of conducting silicon can be fabricated: “n-type” and “p-type,” where electrons and holes are the respective charge carriers. Doping with phosphorus creates “n-type” silicon, whereas doping with boron creates “p-type.” Other dopants can also be used. When silicon is doped, each dopant atom replaces a silicon atom in the lattice. Because dopants can be used to induce conductivity in silicon, the material is known as an extrinsic semi-conductor, i.e., silicon conducts under certain conditions.

Looking at robots from this crystallographic perspective is a bit different. But then again, like so many of our greatest technologies, robotics rely on the most minute details to work successfully and find new ways to move technology forward in trailblazing fashion—clearly a case where the whole robot is far greater than the sum of its very smallest parts.

A PHOTO

Jellyfish populations are expanding worldwide. Their growth, reproduction, respiration and prey catch rates are similar to plankton-eating fish. Combined, their increasing numbers and food web impact make it important to better understand their biology and behavior.

Long-time collaborators Sean Colin of Roger Williams University and Jack Costello of Providence College study the comb jellyfishMnemiopsis leidyi. A suspension feeding predator and an invasive species, M. leidyi can impact the entire marine food web.

Since jellyfish feed in the water column, they eat on the move. Colin and Costello’s research reveals M. leidyi has two main ways of swimming: jetting or rowing.

Caption: A body diagram of a comb jellyfish. Credit: Sean Colin, Roger Williams University

A TEXT POST

Crystal of the Week: Serotonin!

“What,” you say?  Serotonin doesn’t sound like a crystal?  Sure, you are not going to find serotonin amongst your gemstones, crystal rock collections or those stereotypical crystals with extended structures. However, serotonin is, in fact, a molecular crystal.  And a very important one for folks who like to be happy!

Yes, so to celebrate the first anniversary of the Obama Administration’s announcement of the BRAIN Initiative, a brain-y crystal seemed like the right way to celebrate the International Year of Crystallography.

To borrow from the American Chemical Society (ACS), “Serotonin is a monoamine neurotransmitter found in blood, the gastrointestinal tract, and the central nervous system in humans. It also occurs in other animals and many plants. M. M. Rapport and co-workers isolated it from beef serum in 1948.”

Serotonin regulates myriad functions in humans (and other animals), as well as plants.  The most commonly prescribed antidepressants, SSRIs or Selective Serotonin Reuptake Inhibitors, prevent reabsorption (known as reuptake) of neurotransmitter serotonin in the brain. Scientists have found that if we change the balance of serotonin in a person, it in turn helps brain cells better send and receive chemical messages, and that is what can relieve depression.

Serotonin is also associated with regulating aging, reproduction, appetite, growth and sleep in humans. Consequently, you can find derivatives of serotonin in drugs beyond antidepressants, for treating nausea (e.g., after chemotherapy), migraines, psychosis and anxiety.  It is also infamously linked to psychotropic drugs as well, such as LSD and mescaline.

Unfortunately, according to ACS, “serotonin can be a double-edged sword: Earlier this year, W. H. Kaye at the University of California, San Diego, and others implicated elevated levels of serotonin in the brain in eating disorders, such as anorexia and bulimia.

Note:The structure shown here is a space-filling model of the serotonin molecule, C10H12N2O from the Wikimedia Commons. “It is based on that found in the salt serotonin hydrogen oxalate, determined by X-ray crystallography in Acta Chem. Scand. (1978) 32a, 267-270”

A TEXT POST

Crystal of the Week: Pyrite!

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In 1848, the first reports of gold (Au) came out of the Sierra Nevada mountains in California. As the news spread to neighboring Oregon and Latin America, eager prospectors flocked to California by the thousands, staking new claims throughout the region. Nearby cities, such as San Francisco, swelled from hundreds of residents to tens of thousands within a handful of years. In total, 300,000 people immigrated to California to find their gold and get rich. Although the gold extracted from California’s mountains totaled to nearly the equivalent of $2 billion today before the rush began to subside, many miners never profited—and some even lost money.

One complicating factor was the abundance of pyrite (FeS2), also known as “fool’s gold,” which leads us to our Crystal of the Week in celebration of 2014 International Year of Crystallography! There is certainly no better week to celebrate a “foolish” element than one that includes April Fools Day, afterall. 

Because of pyrite’s resemblance to gold, miners often encountered difficulty distinguishing between the two. Besides a comparison of density, solutions of strong nitric acid and hydrochloric acid were routinely used to identify the imposter; as a noble metal, gold is not susceptible to corrosion by strong acids, whereas almost all other metals and minerals are. Years later, we still strongly associate pyrite with the legacy that it earned in the Sierra Nevadas. However, today, fool’s gold has found a fantastic, new application, to the surprise of many.

Materials engineers are now experimenting with solar cells composed of fool’s gold. Unlike the highly toxic cadmium and rare, expensive elements (e.g., tellurium and indium) used in more conventional solar cells, or the inherently brittle silicon wafer, pyrite is both an efficient absorber of visible light and more robust to mechanical handling. Additionally, iron and sulfur are some of the most abundant and cost-effective materials on Earth. The fool’s gold is often alloyed with silicon (also abundant and cheap!) to achieve better thermal stability, which increases the survivability of the iron silicon sulfide thin film solar cells during processing.

In addition to a Center for Chemical Innovation that exclusively studies solar fuels, the National Science Foundation has supported many researchers who look at new ways to build upon basic science to find smarter, better ways to harness solar energy. Several of these researchers, in fact, include pyrite in their research, such as Matt Law at the University of California Irvine. (See Los Angeles Times story.) According to an abstract of his NSF-funded research, his team combines material scientists, chemists and mathematicians who hope to overcome two hurdles to this technology: “the difficulty in synthesizing high-quality, phase-pure pyrite and the low photovoltage of pyrite devices.”

While much work remains before bringing such devices to market, this material could rapidly move forward America’s renewable energy industry. With this kind of effort, pyrite is no joke when it comes to potential sustainable energy solutions…not even on April Fools Day.

Photo credit: Didier Descouens, Wikimedia Commons

A PHOTO

Researchers discovered that when building citizen science participation, not all social networks are equally effective. Google Hangout outperformed Twitter, Facebook and CosmoQuest in engaging a larger audience for Zooniverse, a framework for a diverse set of citizen science tasks. Read more… 

Caption: The Cartwheel galaxy provides a rainbow of mult-wavelength observations. Credit: NASA/JPL-Caltech

A TEXT POST

Crystal of the Week: Widmanstätten iron!

In continued celebration of the 2014 International Year of Crystallography, this week we highlight the recently announced potential discovery of “primordial gravitational waves,” based on data collected with the National Science Foundation’s South Pole Telescope. This exciting discovery seems to verify the final prediction of Albert Einstein’s general theory of relativity, documenting the earliest shock waves of the big bang.

Of course, any expert (or amateur!) particle physicist knows that immediately after the big bang, the degree of atomic order necessary for crystalline structures was non-existent in the universe. In fact, research has shown that the universe had to cool for thousands of years before the first electrically neutral atoms could form. Instead, our connection to crystallography this week comes from the location of the South Pole Telescope on Antarctica.

Did you know that Antarctica is the best place on Earth to find meteorites? The National Science Foundation also funds the Antarctic Search for Meteorites (ANSMET) through its Office of Polar Programs. The glaciers and terrain of the Transantarctic Mountains are perfect for capturing and sifting meteorites. Combined with local weather patterns, meteorites caught in the glaciers are concentrated and then exposed by high winds, allowing the ANSMET scientists to recover them.

Meteorites come in a variety of classes—indeed, meteorite taxonomy is its own field of science! Most meteorites that fall to Earth are chondrites (86%), formed by the accretion of dust and mineral grains into asteroids. Achondrite meteorites (8%) are similar to igneous rocks found on Earth, having suffered extensive degrees of internal heating and melting while hurtling through space.

In contrast, iron-based meteorites (only 6%), which are composed of an iron-nickel alloy known as meteoric iron, often yield some of the most beautiful internal crystallinity. Typically, the alloy separates into two phases, kamacite and taenite. Cut, polished, and acid-etched iron meteorites are known for their striking geometric Widmanstätten patterns, which reflect the internal crystal symmetry of the alloy. The lamellar grains in these striking specimens can grow to several centimeters in length, as a result of the excessively long cooling times (thousands of years!) allowed for crystal growth in the parent asteroid body.

Finally, while modern scientists collect iron meteorites to study their composition and origin, ancient civilizations used these forms for something quite different—forging and smelting to manufacture swords! (Photo credit: Liz Boatman, NSF)

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An anatomically correct robotic hand, developed by a group of researchers funded through NSF’s Emerging Frontiers in Research and Innovation program, will enhance studies of the human hand’s biomechanics and movement control. The device is expected to contribute to more dexterous robotic devices. Read more… 

Caption: Researchers are studying how the brain controls hand movements with the Anatomically Correct Testbed hand. 

Credit: Ellen Garvens, University of Washington

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Want to know how old a fish is? Check its ear bones. The bones, called otoliths, have growth rings just like growth rings in a tree, and many fish add one growth ring to their ear bones every year. During an NSF-sponsored Research Experiences for Undergraduates summer internship, James White wondered if eel ear bones add one growth ring every year. He spent the summer studying eel otoliths at the Department of Natural Resources in Charleston, S.C.

After looking at many eel otoliths, White determined that American eels in South Carolina add one growth ring to their ear bones each year. This is important because researchers can use the ear bones to figure out how long eels are living as well as the location of old and young eels. Read further… 
Here, you see a slice of an eel ear bone.
Credit: James White and Stephen Arnott, Marine Resources Research Institute