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Magnetic Nanoparticles Promise to Prevent Strokes and Heart Attacks

Magnetic nanoparticles have served as the foundation for a number of medical technologies, including drug delivery, medical imaging contrast agents and cancer diagnosis and treatment

Now researchers at Houston Methodist are loading up magnetic nanoparticles with drugs and camouflaging them from the immune systems so that they can  destroy blood clots at a rate about 100 to 1000 times faster than a commonly used clot-busting technique.

The researchers believe that if the technique proves successful in human trials that it could help prevent strokes, heart attacks and pulmonary embolisms.

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Silicon Nanofibers Boost Li-ion Batteries for EVs

Last summer, Mihri and Cengiz Ozkan, both professors at the University of California Riverside, put a small twist on all the attempts to use nanostructured silicon on the anodes of lithium-ion (Li-ion) batteries. They dispersed silicon particles onto nanostructures rather than making nanostructures on silicon.

Now the Ozkans are at it again. This time they and their colleagues at UC Riverside have created a paper-like nanofiber material that can be applied to the anodes of Li-ion batteries, boosting by several times a battery’s specific energy—the amount of energy that can be delivered per unit weight.

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Crumpling Graphene Could Expand Its Applications

Last October, researchers at MIT showed that graphene could be crumpled and then flattened again and still remain effective for use in the electrodes of supercapacitors that could be used to power flexible electronics.

Now a team at the University of Illinois at Urbana-Champaign are showing that if you keep the graphene crumpled, you increase its surface area. This 3D surfaced graphene could open new application areas for the material in electronics and biomaterials. 

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Nanowire Brushes Usher in New Generation of Smoke Detectors

Zinc oxide's' ability to absorb and emit ultraviolet light has long been the operational foundation of photoelectric smoke detectors.

While this technology has proved effective in detecting larger smoke particles found in dense smoke, it’s not quite as sensitive in detecting the small smoke particles produced by fast burning fires.

Now researchers at the University of Surrey’s Advanced Technology Institute have dramatically increased the effective surface area of zinc oxide by fashioning the material into what amounts to nanowire "brushes," making the smoke detectors they’re used in 10,000 times more sensitive to UV light than a traditional zinc-oxide detector.

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DNA Data Storage Just Got a Bit More Practical

For two years now, researchers have been storing digital information in the form of DNA, but there has remained some question as to whether it’s a practical solution for digital storage.

Now researchers at the Swiss Federal Institute of Technology in Zurich (ETHZ) have addressed a number of the problems associated with using DNA as data storage—enough so that they believe it can be used for error-free storage of information.  If their solution proves successful, it could open the door for data storage that lasts for a million years.

Researchers around the world have been investigating a variety of new methods for storing digital information because we’ll be lucky if the solutions we have now, like hard drives and servers, can keep faithful records for fifty years. DNA has been among those potential alternatives. But errors during data retrieval have been the method’s bugaboo. Gaps and false information in the encoded data result from chemical degradation and mistakes in DNA sequencing.

In research published in the journal Angewandte Chemie, the Swiss team was able to overcome the problem of chemical degradation of the DNA by encapsulating the genetic material in silica (glass) spheres with diameters of around 150 nanometers.

In order to test the quality of their encapsulation, the researchers simulated a long period of time by storing the information-encoded DNA at temperatures between 60 and 70 degrees Celsius for up to a month. This simulated, within a few weeks, the degradation that would occur over hundreds of years under normal conditions.

After finding that the silica capsules outperformed several other materieals they tested, the researchers then moved on to ensuring that the DNA remained error free.

While advances in DNA sequencing make it possible to read stored data on DNA affordably, affordability and exactitude don’t always go hand in hand. To overcome this problem, the researchers have developed a way to correct any errors based on the Reed-Solomon Codes, error-correcting codes normally used to ensure accurate data recovery after long-distance data transmission.

The scheme adds just a bit more data to ensure that what’s encoded is error free. “In order to define a parabola, you basically need only three points,” said Reinhard Heckel from ETH Zurich’s Communication Technology Laboratory in a press release. “We added a further two in case one gets lost or is shifted.”

Mollusks Show the Way to Better Li-ion Batteries

Biomimicry has served as the foundation for a significant portion of nanotech research. Nature has had a few billion years to work out the most effective way to get things done on the nanoscale so it makes sense to do a fair amount of cribbing from it solutions.

Now researchers at the University of Maryland, Baltimore County (UMBC) have borrowed a process from mollusks to develop a method for improving the properties of lithium-ion (Li-ion) batteries.

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New Manufacturing Method Promises Scalable Graphene Electronics Production

When you hear people sing the praises of graphene, they are usually referring to the single-crystal graphene that has many attractive properties like high electron mobility. Unfortunately, producing that pure single-crystal graphene requires a decidedly unscalable method known as the “Scotch Tape” method; graphene is pulled off in single-layer flakes directly from bulk graphite.

Chemical Vapor Deposition (CVD) has been seen as a bridge between scalability and purity in graphene production. With that technique, graphene is grown on a metal substrate like copper or nickel. But because the graphene eventually has to be peeled off of the metal substrate, the graphene can either be completely ruined or contaminated.

Now researchers at the University of Groningen in the Netherlands have devised a production method based on CVD that eliminates the potential for ruin or contamination while still remaining scalable. It is based on something they discovered when analyzing CVD-grown graphene three years ago.

“When we analyzed a sample of graphene on copper, we made some strange observations,” said Meike Stöhr, one of the researchers, in a press release.

What the researchers observed was that some copper oxide was present next to the copper. In fact, the graphene formed a kind of film on top of the copper oxide. Because oxidized metals are often used in passivation of electronics—a process in which a light coat of a protective oxide is used to create a shell against corrosion—the researchers suspected that the copper oxide layer could leave the graphene’s properties untouched.

In research published in the journal Nano Letters, the Groningen researchers took their initial observations and demonstrated the ability to grow graphene on copper oxide. Most importantly, the process of decoupling the graphene and copper oxide preserves the graphene’s attractive electronic properties.

While Stöhr concedes that their work will need to be duplicated by other research groups, their findings could have a long-reaching impact on the future of graphene devices. If this process enables the growth of large single-domain crystals of graphene, it would be possible to then use common lithographic techniques to etch a host of electronic devices in a way analogous to silicon.

Thermoelectric Nanowires Promise Energy Harvesting From Car Exhaust

Researchers at Sandia National Labs have developed a manufacturing process capable of controlling the crystal orientation, crystal size, and alloy uniformity of nanowires so that they could be used in a range of thermoelectric applications. 

Because thermoelectric materials are capable of generating an electrical current as a result of a difference in temperature between one side of the material and the other, the Sandia team believes the new nanowires could make it possible for carmakers to harvest power from the heat wasted by exhaust systems or lead to more efficient devices for cooling computer chips.

Nanowires have been suggested for a range of applications, but in thermoelectric applications, the quality of the nanowires has heretofore been inadequate. The trick for any thermoelectric material is to combine high electrical conductivity and relatively low thermal conductivity—a property known as thermoelectric efficiency.

Researchers have been investigating a number of nanomaterials for thermoelectric applications; traditional materials possess a relatively poor thermoelectric conversion efficiency or they are prohibitively expensive for commercial uses.

The Sandia researchers turned to nanowires despite their previous poor performance, believing that if they could better control the manufacturing process, they could improve the nanowires’ quality enough to make them a useful thermoelectric material.

In research published in the Cambridge Journal of Materials Research, the Sandia team employed a method known as room-temperature electroforming, which is widely used in commercial electroplating. In electroforming, material is deposited at a constant rate, which results in the nanowires growing uniformly.

This uniformity of composition held for the entire length of each nanowire and even across an array of them. The crystals that made up the nanowires were all oriented in one direction, making it easier for electrons to travel along the conduits.

“There are little nuances in the technique that I do to allow the orientation, the crystal growth, and the composition to be maintained within a fairly tight range,” said Graham Yelton of Sandia in a press release. “It’s turning the knobs of the process to get these things to behave.”

The next step in the research will be to make an electrical contact with the nanowire-based material and to measure the resulting thermoelectric behavior.

One hurdle the team has to overcome: “Thermoelectric materials readily form oxides or intermetallics, leading to poor contact connections or higher electrical contact resistance. That reduces the gains achieved in developing the materials,” Yelton said.

So far the team has had some success in getting good contact at the bottom of an array, but making a connection at the top has proved difficult.

At the moment, the researchers are seeking additional funding to solve the problem of making contacts, and then they plan to characterize the thermal electric properties of the arrays.

Is "Valleytronics" the Next Big Thing in Quantum Computing?

Researchers at the Lawrence Berkeley National Laboratory (LBL) have developed a new pathway to achieving “valleytronics” using two-dimensional (2D) semiconductors.  The LBL researchers believe that this new approach could make valleytronics a more stable alternative to “spintronics” as a replacement for traditional electronics.

The term valleytronics is starting to filter into in the lexicon of cutting-edge electronics research. What it actually means is complicated, but it represents a movement away from exploiting the electrical charge of electrons as a means for storing information and instead using the wave quantum number of an electron in a crystalline material to encode data.

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Transistor Made From Silicene for First Time

Ever since silicene—a one-atom-thick layer of silicon—was first predicted in computer models a decade before graphene was first synthesized in 2004, it’s been on a roller coaster ride. It’s gone from being considered the next big thing to being thought of as an impossibility outside of computer models.

Drawing on an increasing amount of recent research demonstrating that silicene can survive—for at least a little while—outside the virtual world of computer models, researchers at the University of Texas at Austin have taken it all a step further by demonstrating a method for fabricating a field-effect transistor out of silicene. The device reportedly lives up to the switching speeds that had been promised in the computer models. Most importantly, this research marks the first time that anyone has been able to fabricate a transistor out of silicene.

In research published in the journal Nature Nanotechnology, the Texas researchers grew their silicene on a thin film of silver and capped it with aluminum oxide. Adding this light coat of protective oxide to create a protective shell—what’s known in the business as passivation—has recently proven effective in protecting graphene devices.

The researchers took the encapsulated silicene and placed it on a silicon dioxide wafer with the silver side up. They then put patterns into the silver side that would allow for contacts to be made so it could operate as a transistor.

The device was not tested in the open air, but it at least remained stable in vacuum conditions. Of course, this situation is not practical for real-world applications, but the researchers feel that this marks an important step towards realizing commercially viable silicene-based transistors.

The experimental research does confirm some of the theories that had been based solely on computer models. It demonstrated that silicene has electrical properties similar to those of graphene, including allowing electrons to travel through the material without any barriers.

While this research provides some confirmation of silicene’s attractive electronic properties, the research falls somewhat short of supporting the notion that because silicene is made from silicon it will be easier for the electronics industry to adopt. Silicene may be a one-atom-thick relative of silicon, which the electronics industry has characterized for the last half-century, but this research doesn’t seem to indicate that it has become any more friendly to large-scale manufacturing than its more mature cousin.

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Nanoclast

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

 
Editor
Dexter Johnson
Madrid, Spain
 
Contributor
Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY
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