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Liquid 3-D Printing

Giant leaps have been made in recent years with 3-D printing. Though most 3-D printed items are made of plastic, more exotic ingredients have included sugar, mashed potatoes, and living cells. A 3-D printer commonly works by depositing a layer of material much like an ordinary printer and then printing out another layer once the material below has solidified. This procedure has a built-in problem: Even small objects take way too long to produce.

An object just several centimeters high can take hours to print. But now scientists at Carbon3D in Redwood City, Calif., and the University of North Carolina at Chapel Hill (UNC) say they can slash printing times by two orders of magnitude. Instead of printing an item step by step and layer by layer, the new technique prints objects in a continuous manner.

A 3-D printer often uses ultraviolet light to harden resins, but oxygen in the air often slows this hardening down. Instead of treating oxygen as an obstacle they had to overcome, the researchers used it to their advantage.

The new 3-D printer starts with a basin filled with a pool of liquid resin. Ultraviolet rays can emerge from beneath through a hole at the bottom of this basin. (Imagine a sink filled with resin where ultraviolet light can shine up from the drain.)

In the hole between the basin and ultraviolet rays, where a stopper might fill the hole at the bottom of a sink, is a layer of oxygen-rich liquid tens of micrometers thick. This layer serves as a transparent window for the ultraviolet rays. Solidification cannot occur in this "dead zone."

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To print an object, a metal plate is lowered down onto the surface of the resin pool. Ultraviolet rays are then fired upward at the metal plate. The ultraviolet rays make the resin harden only in specific zones within this pool above the dead zone. The resulting solid object is attached to the metal plate. When enough of the object has solidified, the 3-D printer slowly pulls the metal plate upward. As the hardening item rises from the liquid resin, it creates suction forces that pull liquid resin into the basin to replace what was lost to the solidified object.

Using this new method, the scientists printed objects at speeds of up to more than 1 meter per hour, generating complex solid objects such as a 10-centimeter-tall version of the Eiffel Tower. By slowing down print speeds, they could also print features less than 100 µm wide, or thinner the average human hair.

One of the senior researchers on this work, UNC’s Joseph DeSimone, gave a TEDTalk on this project on 16 March. The scientists will detail their findings in the 20 March issue of the journal Science.

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Why International Engineering and Science Students Stay or Go

Foreign-born talent has fueled many Silicon Valley startups and contributed heavily to U.S. leadership in in science and engineering for decades. But national data shows that just half of science and engineering doctoral recipients who were born overseas end up staying in the U.S. to pursue their post-graduation careers. A new study has teased out several reasons why students choose to stay in the U.S. or go back to their home countries.

The limitations of U.S. immigration policy and H-1B work visas are one of the biggest challenges for foreign students interested in pursuing U.S. careers. That’s according to a survey of 166 international graduate students conducted by the Center for Nanotechnology in Society at the University of California, Santa Barbara. Many students who participated in the survey pointed to uncertainty about obtaining permanent resident status after graduation as a major deterrent to both studying in the U.S. and trying to work in the U.S. after graduation. For the study, which appeared in the 11 March 2015 issue of the journal PLOS One, one mechanical engineering student summed up the frustrations of many peers thusly:

The fact that you don’t have a green card at the end of your PhD—it’s a nightmare. For international students, not having a green card, it impacts the job search, everything. The U.S. is welcoming to graduate students to come and study but there doesn’t seem to be a plan for after students graduate. Students settle for jobs that are below them because they work for companies that will provide them with a green card.

But the study also examined how several professional, social and personal factors influenced the decisions of foreign students. The study authors focused on three key decisions: whether to pursue higher education in the home country, whether to stay in the U.S. or return home after graduation, and whether to pursue a career in academia or industry.

One of the strongest predictors of whether a student will stay or leave is whether he or she wants to pursue a career in academia or industry. Students who wanted industry careers had a 90 percent probability of pursuing U.S.-based careers after graduation. By comparison, students who planned to pursue academic careers believed they would receive better treatment from colleagues in their home country. As a result, this group had an 86 percent probability of leaving the U.S. after graduation.

The quality of U.S. mentors and professional networks factored heavily into the decisions of students who wanted to go into academia but decided to leave the United States after earning their degrees. But not in the way one might predict. Many students who believed the U.S. offered higher quality mentors or professional networks were more likely to return to their home countries.

“We were most surprised by the role mentorship and networking played in whether a student decided to stay or leave,” said Xueying (Shirley) Han, lead author on the study and a postdoctoral scholar in marine biology at the University of California, Santa Barbara, in a press release. “Individuals who felt they had strong mentorships and networking actually felt more comfortable leaving the U.S.”

It’s possible that foreign students who had forged strong relationships with U.S. mentors or professional networks were more confident about returning home to work, according to Han and her colleagues. Students who had weaker U.S. relationships might be more interested in staying longer in order to strengthen professional ties.

One important thing to note is the study’s relatively small sample size. Of the 166 students surveyed, about 73 percent were engineers and the rest studied life and physical sciences. But the demographics of the survey respondents did generally match the national distribution of international students studying in the U.S.; the largest groups hailed from China and India.

Such foreign talent continues to drive much of U.S. innovation. About 44 percent of Silicon Valley startups currently include a foreign founder. Foreign born scientists and engineers also contributed more than half of the international patents filed by multinational corporations based in the United States. But the United States can’t assume it will continue to attract the world’s best talent without addressing these students’ concerns. Many international students pointed to Europe as an increasingly competitive choice for studying science and engineeringin large part because of more relaxed immigration policies.

In order for policymakers to craft smart policy, they need to consider the complex interaction of factors that go into foreign students’ career decisions,” Han said. “And if the U.S. wants to maintain its competitive economic edge, it needs to provide an alternative for highly skilled scientists and researchers to stay.”

Laser Bug Zapper Inches To Market

If it’s over-the-top crazy to swat a fly with a sledgehammer, what are we to say of vaporizing one with a laser?

How about: good riddance. We need new weapons for the war on bugs, particularly disease-bearing mosquitoes, which are quick to evolve resistance to poisons and are hardly fazed by traps that lure them to their deaths. That’s because there are just too many of the little bloodsuckers out there, particularly in the malarial regions of Africa. 

After years in the blue-sky area of speculative inquiry, the laser bug zapper took its first solid step toward commercialization last week, when Intellectual Ventures, the patent-holding giant, announced that it had licensed the manufacturing of the system to Lighting Science Group of Melbourne, Florida, a maker of LEDs.

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A Brain-Computer Interface That Lasts for Weeks

Brain signals can be read using soft, flexible, wearable electrodes that stick onto and near the ear like a temporary tattoo and can stay on for more than two weeks even during highly demanding activities such as exercise and swimming, researchers say.

The invention could be used for a persistent brain-computer interface (BCI) to help people operate prosthetics, computers, and other machines using only their minds, scientists add.

For more than 80 years, scientists have analyzed human brain activity non-invasively by recording electroencephalograms (EEGs). Conventionally, this involves electrodes stuck onto the head with conductive gel. The electrodes typically cannot stay mounted to the skin for more than a few days, which limits widespread use of EEGs for applications such as BCIs.

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Now materials scientist John Rogers at the University of Illinois at Urbana-Champaign and his colleagues have developed a wearable device that can help record EEGs uninterrupted for more than 14 days. Moreover, their invention survived despite showering, bathing, and sleeping. And it did so without irritating the skin. The two weeks might be "a rough upper limit, defined by the timescale for natural exfoliation of skin cells," Rogers says. 

The device consists of a soft, foldable collection of gold electrodes only 300 nanometers thick and 30 micrometers wide mounted on a soft plastic film. This assemblage stays stuck to the body using electric forces known as van der Waals interactions—the same forces that help geckoes cling cling to walls.

The electrodes are flexible enough to mold onto the ear and the mastoid process behind the ear. The researchers mounted the device onto three volunteers using tweezers. Spray-on bandage was used once twice a day to help the electrodes survive normal daily activities.

The electrodes on the mastoid process recorded brain activity while those on the ear were used as a ground wire. The electrodes were connected to a stretchable wire that could plug into monitoring devices. "Most of the experiments used devices mounted on just one side, but dual sides is certainly possible," Rogers says.

The device helped record brain signals well enough for the volunteers to operate a text-speller by thought, albeit at a slow rate of 2.3 to 2.5 letters per minute.

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According to Rogers, this research: 

...could enable a persistent BCI that one could imagine might help disabled people, for whom mind control is an attractive option for operating prosthetics… It could also be useful for monitoring cognitive states—for instance, to see if people are paying attention while they're driving a truck, flying an airplane, or operating complex machinery. It could also help monitor patterns of sleep to better understand sleep disorders such as sleep apnea, or for monitoring brain function during learning.

The scientists hope to improve the speed at which people can use this device to communicate mentally, which could expand its use into commercial wearable electronics. They also plan to explore devices that can operate wirelessly, Rogers says. The researchers detailed their findings online March 16 in the journal Proceedings of the National Academy of Sciences.

ESA Rescues Errant Galileo Navigation Satellites

After long journeys two satellites that were parked in wrong orbits have reached a "corrected" orbit, allowing them to become part of Europe’s GPS system. When launched in August of last year, a design flaw in the fourth stage of the Soyuz launcher caused the injection of both satellites into orbits that brought them through the Van Allen Belts but also made them unusable as navigation satellites.

At first, things looked grim. The two satellites, the fifth and sixth of a series of 30 satellites, had hydrazine fuel for their thrusters, but the amount was only sufficient for small orbit corrections, not for mayor orbit changes. However, in November ESA engineers used the fifth satellite’s thrusters, to nudge its orbit’s lowest point 3500 km farther from Earth—making the orbit more circular. Testing showed that its electronics were not damaged by Van Allen Belt radiation, and in December it performed, in combination with the other Galileo satellites, its first navigation fix.

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Instead of Dropping Bombs, Can Drones Locate Unexploded Ones?

In much of the world, an American drone flying overhead means danger: Predator drones and the like can unleash fury out of the deep blue sky. But drones can also help war-torn countries recover, argued Ryan Baker, CEO of drone maker Arch Aerial, at a SXSW Interactive talk yesterday. His company hopes to use its drones to identify locations that are likely to be riddled with unexploded bombs from past wars. 

Baker wants to start with Laos, which bears the terrible distinction of being the most heavily bombed nation ever: During the height of the Vietnam War, the country was pounded with about 2 million tons of ordnance. And Laotians today are still suffering the effects of that bombardment, as unexploded shells and landmines still litter the landscape. The biggest threat comes from the cluster bombs dropped during the Vietnam War, which scattered small explosives about the size of tennis balls. 

In Laos, “there have been some 12,000 accidents related to UXO [unexploded ordnance] since 1973,” said Baker. Most deaths and injuries occur when people try to remove unexploded bombs, he said, or when local farmers till their fields.

Baker said his company’s octocopter will carry a laser imaging system known as LIDAR (often used in self-driving cars) to survey terrain and identify locations where unexploded ordance will likely be found. LIDAR is useful because it can see through vegetation and create precision maps of the ground. By flying drones above Laos’s forests and fields, surveyors can look for topographical features signifying places that might have been targeted by bombing campaigns—such as bunkers and trenches, Baker explained. Arch Aerial plans to do some test runs this year in cooperation with one of the humanitarian groups working on unexploded ordance in Laos. 

This initiative is only possible because of rapid advances in LIDAR technology, Baker said. “A few years ago, a LIDAR system was the size of this table,” he said, “and had to be fitted into a gutted airplane.” And conducting a survey by plane requires plenty of money and compliance with flight regulations. Now, with a small and cheap LIDAR system aboard a drone, a surveyor could create an aerial map with “risk profiles” of the landscape before setting foot on the ground. 

Surveyors will still have to deal with public perception and the stigma surrounding drones, Baker noted, since Americans operating strange equipment are sometimes viewed with suspicion. But there’s an easy way to solve that problem, he said: Just hand the controls to a local. 

Your Body Is a Race Car. McLaren Wants to Optimize Its Performance

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It’s probably not good for the soul to think of life as a race to be won. But if you do accept that metaphor, you’d likely be happy to have McLaren managing your pit stops as you make your way along the course.

The engineering company is famous for building Formula One race cars featuring computerized engine control systems and dozens of sensors that transmit data to remote analytics teams. Over the last few years, McLaren first began applying lessons learned from managing race cars to managing elite athletes, and now it’s bringing its tools to health and medicine. 

Today at SXSW Interactive, Geoff McGrath described the origin and evolution of McLaren Applied Technologies, the business unit he founded within the company. McGrath also articulated three conditions that must be met in order to turn our bodies into high performance machines, with instruments and analytics helping us operate at our peak capacity. 

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Disney Research System Predicts Soccer Goals

Last weeked, Brazilian superstar, Kaká, scored in the final minute of his Major League Soccer debut for Orlando City Soccer Club. It was his fifth shot at goal, the second on target. Carlos Rivas, Orlando’s Colombian striker, also had five shots, but didn’t score. The match, against New York City FC, ended 1-1.

Soccer coaches often complain that their teams don’t take all the chances to score that they get. But, according to a group of Disney Research scientists, more chances don’t necessarily mean more goals. Germany beat Brazil 7-1 in the World Cup semi-final, last July, but Brazil had more shots on goal.

The Disney Research team released their paper, “Quality vs Quantity: Improved Shot Prediction in Soccer using Strategic Features from Spatiotemporal Data” at the 9th Annual MIT Sloan Sports Analytics Conference in Boston, on February 27th

They used player tracking data from sports analytics company Prozone looking at a season’s worth of shots on goal from an anonymous professional league. The data ccovered a ten-second window of play before each of the 9732 shots were taken.

During a soccer match, players are moving all the time. The role they play at any given moment will depend on the context of the match as it unfolds as much as their preassigned duties.  “We needed to align the tracking data so it told us which role a player is taking up, in each frame, rather than just their starting position,” says Patrick Lucey, who led the research team.

To work out the probability of different types of chances turning into goals, Lucey’s team used role representation software to analyse what players were doing, where and with who. “This enabled us to capture the nuances in general play, counter-attack, work out what role a player is performing during the 10 second segment being analyzed,” Lucey adds.

They also clustered each play into a specific match-contexts. This revealed that not all chances are created equal. The highest percentage of goals, they discovered, resulted from counter attacks—14.87 percent. Next came set pieces from a cross from a free-kick (10.05 percent), corners (8.97 percent) open play (8.26 percent) and finally free-kicks themselves (4.82 percent)

Nonetheless, two of Germany’s goals against Brazil in the World Cup came on the counter attack, one from a corner, and four from open play. Kaka’s debut goal was a deflected free kick. Analytics still can’t account for everything in the beautiful game.

Carbon Buckyballs Have a New Silicon Rival

Three years ago researchers created a 2-D silicon analogue to graphene, whereby silicon atoms form a similar honeycomb monolayer of atoms, a material that could combine the extraordinary properties of graphene with silicon’s semiconducting abilities. Researchers quickly moved to try to replace the carbon atoms of buckyballs with silicon atoms as well, but ran into difficulties because silicon’s chemical behavior is very different from that of carbon.

Now researchers have reported in Angewandte Chemie, International Editionthe discovery of a 3-D silicon analogue to carbon buckyballs. It contains a core of 20 silicon atoms stabilized by chlorine atoms (the researchers are therefore suggesting the term “fullerane” instead of “fullerene” for their compound.) The discovery was serendipitous, says Matthias Wagner, who with Max Holthausen, led the research at the Goethe University in Frankfurt, Germany. “One of my Ph.D. students, Jan Tillmann, discovered a small amount of crystals produced in a reaction involving hexachlorodisilane (Si2Cl6). He X-rayed them and found that they contained cages made up of 20 silicon atoms. It took him a year to optimize the reaction and now he gets a yield of about 30 percent,” says Wagner.

While carbon atoms happily link to one, two, three, or four other atoms, silicon atoms prefer to form bonds with four other atoms, which precludes a buckyball consisting of only silicon.  Consequently, the compound Tillmann discovered had a more complex structure. It contains a buckyball structure in the shape of a dodecahedron formed by 20 silicon atoms, with a chloride ion sitting at its center. Forming an exoskeleton of sorts around the silicon dodecahedron, are 12 silyl groups of atoms consisting of one silicon atom linked to three chlorine atoms (SiCl3). Another eight individual chlorine atoms are bound to the remaining vertices.

The 12 silyl groups make the silicon fullarene vulnerable to moisture. On the other hand, their chlorine atoms can easily be substituted by hydrogen atoms, explains Wagner: “This tells us that we can use the SiCl3 groups as functionalization sites” he adds. And this is where the silicon buckyballs could have a clear advantage over their carbon relatives, which are not very amenable to linking up with each other.

“What we are dreaming about is that we can use these SiCl3 substituents as anchor groups to interlink these fullerenes to form two or three dimensional networks—this is our long-term goal,” says Wagner.

Will this allow the introduction of new strategies for the further miniaturization of nanoscale silicon circuits? Finding out will be the focus of much of their future work. One project will be to determine the electrical and optical properties of these fullerenes. “We have just prepared the building blocks, and we hope for something like semiconductive properties. Compounds like this did not exist up to now, and now we have to see what we can do with them,” says Wagner.

Magnetosphere Satellites Launch

Update, 13 March: NASA’s Magnetospheric Multiscale mission had a picture-perfect launch from Cape Canaveral Air Force Base in Florida at 10:44 p.m. ET following a smooth countdown. All four spacecraft that are part of the mission "appear healthy following separation," the agency says.

To solve a mystery concerning powerful geomagnetic storms that can threaten Earth's satellites and power grids, NASA is launching a quartet of spacecraft into orbit on 12 Marchfor a two-year mission to analyze magnetic fields around the Earth.

A geomagnetic storm in March 1989 blacked out the entire Canadian province of Quebec, leaving millions of customers in the dark and damaging transformers as far as New Jersey, and ones 10 times worse are possible, such as the 1859 solar superstorm.

Every step leading to such intense bursts of space weather are ultimately driven by a mysterious phenomenon known as magnetic reconnection, which occurs in clouds of electrically charged gas known as plasmas. Magnetic fields are entrapped inside plasmas, and magnetic field lines can break and reconnect with each other within these clouds, explosively converting magnetic energy to heat and kinetic energy.

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