Articles from August 2013

Miniature Rockets For NanoSatellites

For the last few years, researchers around the world have been trying to build mini rockets using microscopic hollow needles to electrically spray thin jets of fluid, which push the spacecraft in the opposite direction. The fluid propellant is a special chemical known as an ionic liquid. A single thruster needle is finer than a human hair, less than one millimeter long and produces a thrust force equivalent to the weight of a few grains of sand. A few hundred of these needles fit in a postage-stamp-size package and produce enough thrust to maneuver a nanosatellite.
Miniature rockets aren’t needed to launch a nanosatellite from Earth. The small vehicles can hitchhike with a regular rocket that is going that way anyway. But because they are hitchhikers, these nanosats don’t always get dropped off in their preferred location. Once in space, a nanosatellite might need some type of propulsion to move it from its drop-off point into its desired orbit. This is where the micro rocket engine comes in. These new electrospray thrusters face some design challenges, however. “Because they are so small and intricate, they are expensive to make, and the needles are fragile,” says King, the Ron and Elaine Starr Professor of Mechanical Engineering-Engineering Mechanics at Michigan Technical University. “They are easily destroyed either by a careless bump or an electrical arc when they’re running.

Nanosatellites are smartphone-sized spacecraft that can perform simple, yet valuable, space missions. Dozens of these little vehicles are now tirelessly orbiting the earth performing valuable functions for NASA, the Department of Defense and even private companies.
nanosat Nanosatellites borrow many of their components from terrestrial gadgets: miniaturized cameras, wireless radios and GPS receivers that have been perfected for hand-held devices.
However, according to Michigan Tech’s L. Brad King, there is at least one technology need that is unique to space: “Even the best smartphones don’t have miniaturized rocket engines, so we need to develop them from scratch.”


From Butterfly Wings To Wearable Electronics, Better Solar Cells

Leveraging the amazing natural properties of the Morpho butterfly’s wings, scientists have developed a nanobiocomposite material that shows promise for wearable electronic devices, highly sensitive light sensors and sustainable batteries. Eijiro Miyako and colleagues from the Japanese national institute of Advanced Industrial Science and Technology (AIST) explain that Morpho butterfly wings have natural properties that are beyond the capabilities of any current technology to reproduce artificially. In addition to being lightweight, thin and flexible, the butterfly’s wings absorb solar energy, shed water quickly and are self-cleaning.
butterfly wings
 “Our present study highlights the important progress that has been made toward the development of smart nanobiomaterials for various applications such as digital diagnosis, soft wearable electronic devices, photosensors, and photovoltaic cells,” the scientists state.

A report on the new hybrid material appears in the journal ACS Nano.


Telepathy Via Internet Is Now Real

University of Washington researchers Rajesh Rao and Andrea Stocco have performed what they believe is the first noninvasive human-to-human brain interface, with one researcher able to send a brain signal via the Internet to control the hand motions of a fellow researcher. Using electrical brain recordings and a form of magnetic stimulation, Rajesh Rao sent a brain signal to Andrea Stocco on the other side of the UW campus, causing Stocco’s finger to move on a keyboard.

brain to brain

Rajesh Rao, left, plays a computer game with his mind. Across campus, Andrea Stocco, right, wears a magnetic stimulation coil over the left motor cortex region of his brain. Stocco’s right index finger moved involuntarily to hit the “fire” button as part of the first human brain-to-brain interface demonstration.

While researchers at Duke University have demonstrated brain-to-brain communication between two rats, and Harvard researchers have demonstrated it between a human and a rat, Rao and Stocco believe this is the first demonstration of human-to-human brain interfacing.

The Internet was a way to connect computers, and now it can be a way to connect brains,” Stocco said. “We want to take the knowledge of a brain and transmit it directly from brain to brain.”

The researchers captured the full demonstration on video recorded in both labs. A video and high-resolution photos also are available on the research website.


How To Control Atomic Structures of Carbon Nanotubes

Researchers at the University of South CaliforniaUSC – have succeed to create carbon nanotubes building them with specific, predictable atomic structures. This breakthrough is a major step towards the next generation of computers and materials. Until now, scientists were unable to “growcarbon nanotubes with specific attributes — say metallic rather than semiconducting — instead getting mixed, random batches and then sorting them. The sorting process also shortened the nanotubes significantly, making the material less practical for many applications. For more than three years, the USC team, led by Chongwu Zhou, professor at the USC Viterbi School of Engineering and author of the study published in the journal Nano Letters has been working on the idea of using these short sorted nanotubes as “seeds” to grow longer nanotubes, extending them at high temperatures to get the desired atomic structure.

grow carbon-nanotubeRolled up tubes of graphene could someday rival silicon for applications in solar cells, batteries, electronics and more
We are solving a fundamental problem of the carbon nanotube,” Zhou said. “To be able to control the atomic structure, or chirality, of nanotubes has basically been our dream, a dream in the nanotube field. We are now working on scale up the process. Our method can revoutionize the field and significantly push forward the real applications of nanotube in many fields“, he added.


How Drones Tag and Track Target

Voxtel, an US firm located in Beaverton, Oregon, is developing for the US Air Force a drone-based tagging system, based on quantum dots technology. Voxtel makes tagging materials, called taggants, that can be used to discreetly label vehicles carrying terrorists, or people who are involved in civil disobedience or attempting to cross international borders illegally. Suspects or cars, could be tagged by a tiny drone with a spray that gives a distinct spectral signature, easy to track.

Quantum dots are semiconductor nanocrystals less than 50 atoms across. Because of quantum effects, they absorb and emit light at specific wavelengths.

The company has demonstrated a taggant powder that, when illuminated with an invisible ultraviolet laser, can be detected by infrared cameras 2 kilometres away. The powder is delivered as an aerosol that clings to metal, glass and cloth, and batches can be engineered to have distinct spectral signatures.
Voxtel will deliver the drones very soon to the US Air Force, according to John Kerry, current United States Secretary of State.


Why Gold Nanoparticles Penetrate Cells

Cells are very good at protecting their precious contents — and as a result, it’s very difficult to penetrate their membrane walls to deliver drugs, nutrients or biosensors without damaging or destroying the cell. One effective way of doing so, discovered in 2008, is to use nanoparticles of pure gold, coated with a thin layer of a special polymer. But nobody knew exactly why this combination worked so well, or how it made it through the cell wall. Researchers at MIT and the Ecole Polytechnique de Lausanne in Switzerland have figured out how the process works, and the limits on the sizes of particles that can be used. Their analysis appears in the journal Nano Letters.
gold nanoparticles Passage of a gold nanoparticle (in orange) covered with a monolayer of hydrophobic /hydrophilic material (shown in blue-green, yellow and red), passing through a cell membrane composed of lipids (white and blue)

Until now, says Van Lehn, the paper’s lead author, “the mechanism was unknown. … In this work, we wanted to simplify the process and understand the forces” that allow gold nanoparticles to penetrate cell walls without permanently damaging the membranes or rupturing the cells. The researchers did so through a combination of lab experiments and computer simulations.
Cells tend to engulf things on the surface,” says Alexander-Katz, an associate professor of materials science and engineering at MIT, but it’s “very unusual” for materials to cross that membrane into the cell’s interior without causing major damage. Irvine and Stellacci demonstrated in 2008 that monolayer-coated gold nanoparticles could do so; they have since been working to better understand why and how that works.

Is Safe Drinking Water A Resolved Problem?

An international team of researchers – led by Associate Professor Hui Ying Yang from Singapore University of Technology and Design – showed that water purification membranes enhanced by plasma-treated carbon nanotubes are ideal for removing contaminants and brine from water.

The team included Dr Zhaojun Han and Professor Kostya (Ken) Ostrikov from CSIRO‘s world-leading Plasma Nanoscience Laboratories, located in Australia.

According to Dr Han, these membranes could be integrated into portable water purification devices the size of a tea pot that would be rechargeable, inexpensive and more effective than many existing filtration methods. Contaminated water would go in one end, and clean drinkable water would come out the other.
Carbon naotubeCross-sectional image of the carbon nanotubes

Small portable purification devices are increasingly recognised as the best way to meet the needs of clean water and sanitation in developing countries and in remote locations, minimising the risk of many serious diseases,” Dr Han says. “The large industrialised purification plants we see in other parts of the world are just not practical – they consume a large amount of energy and have high labour costs, making them very expensive to run“, he added.

Dr Han acknowledges that some smaller portable devices do already exist. However, because they rely on reverse osmosis and thermal processes, they are able to remove salt ions but are unable to filter out organic contaminants from the briny water found in some river and lake systems.
For people in remote locations, briny water can sometimes be the only available water source,” he says. “That’s why it’s important to not only be able to remove salts from water, but to also be able to put it through a process of purification“. “Our study showed that carbon nanotube membranes were able to filter out ions of vastly different sizes – meaning they were able to remove salt, along with other impurities,” he says.

According to Professor Ostrikov, the other downside of existing portable devices is that they require a continuous power supply to operate their thermal processes. “On the other hand, the new membranes could be operated as a rechargeable device.”


How To Put Up Your Signature In Tiny Lights

Researchers at the Georgia Institute of Technology want to put your signature up in lightstiny lights, that is. Using thousands of nanometer-scale wires, the researchers have developed a sensor device that converts mechanical pressure – from a signature or a fingerprintdirectly into light signals that can be captured and processed optically.The sensor device could provide an artificial sense of touch, offering sensitivity comparable to that of the human skin. Beyond collecting signatures and fingerprints, the technique could also be used in biological imaging and micro-electromechanical (MEMS) systems. Ultimately, it could provide a new approach for human-machine interfaces.
device to capture your signature
You can write with your pen and the sensor will optically detect what you write at high resolution and with a very fast response rate,” said Zhong Lin Wang, Regents’ professor and Hightower Chair in the School of Materials Science and Engineering at Georgia Tech. “This is a new principle for imaging force that uses parallel detection and avoids many of the complications of existing pressure sensors.”


DNA Robots Mark Cells So Drugs Can Kill Them

Researchers at Columbia University Medical Center, working with their collaborators at the Hospital for Special Surgery, have created a fleet of molecularrobots” that can home in on specific human cells and mark them for drug therapy or destruction. The nanorobots — a collection of DNA molecules, some attached to antibodies— were designed to seek a specific set of human blood cells and attach a fluorescent tag to the cell surfaces. Details of the system were published in the online edition of Nature Nanotechnology.
dnarobotsThis opens up the possibility of using such molecules to target, treat, or kill specific cells without affecting similar healthy cells,” said the study’s senior investigator, Milan Stojanovic, PhD, associate professor of medicine and of biomedical engineering at Columbia University Medical Center.
In our experiment, we tagged the cells with a fluorescent marker; but we could replace that with a drug or with a toxin to kill the cell.”

How To Scan Molecules

Molecules could soon be “scanned” in a fashion similar to imaging screenings at airports, thanks to a detector developed by University of Pittsburgh physicists. The detector, featured in a recent issue of Nano Letters, may have the ability to chemically identify single molecules using terahertz radiation—a range of light far below what the eye can detect.

Etch A sketchOur invention allows lines to be ‘written’ and ‘erased’ much in the manner that an Etch A Sketch® toy operates,” said study coauthor Jeremy Levy, professor in the Department of Physics and Astronomy within the Kenneth P. Dietrich School of Arts and Sciences. “The only difference is that the smallest feature is a trillion times smaller than the children’s toy, able to create conductive lines as narrow as two nanometers.

Nanoparticles Reprogram Immune Cells To Attack Cancer

Researchers at the University of Georgia are developing a new treatment technique that uses nanoparticles to reprogram immune cells so they are able to recognize and attack cancer.
The human body operates under a constant state of martial law. Chief among the enforcers charged with maintaining order is the immune system, a complex network that seeks out and destroys the hordes of invading bacteria and viruses that threaten the organic society as it goes about its work. The immune system is good at its job, but it’s not perfect. Most cancerous cells, for example, are able to avoid detection by the immune system because they so closely resemble normal cells, leaving the cancerous cells free to multiply and grow into life-threatening tumors while the body’s only protectors remain unaware. Shanta Dhar and her colleagues are giving the immune system a boost through their research.

immunity and cancer

What we are working on is specifically geared toward breast cancer,” said Dhar, the study’s co-author and an assistant professor of chemistry in the UGA Franklin College of Arts and Sciences. “Our paper reports for the first time that we can stimulate the immune system against breast cancer cells using mitochondria-targeted nanoparticles and light using a novel pathway.

The findings were published recently in the early online edition of ACS Nano.

APOE4 Gene Increases Up To Ten-Fold Risk To Develop Alzheimer’s

A research team from Columbia University Medical Center (CUMC) identified key molecular pathways that link genetic risk factors to Alzheimer’s disease. More specifically, the researchers first focused on the single most significant genetic factor that puts people at high risk for Alzheimer’s, called APOE4 (found in about a third of all individuals). People with one copy of this genetic variant have a three-fold increased risk of developing late-onset Alzheimer’s, while those with two copies have a ten-fold increased risk. “In this study,” said Dr. Abeliovich, “we initially asked: If we look at autopsy brain tissue from individuals at high risk for Alzheimer’s, is there a consistent pattern?” Surprisingly, even in the absence of Alzheimer’s disease, brain tissue from individuals at high risk (who carried APOE4 in their genes) harbored certain changes reminiscent of those seen in full-blown Alzheimer’s disease,” said Dr. Abeliovich. “We therefore focused on trying to understand these changes, which seem to put people at risk. The brain changes we considered were based on ‘transcriptomics’—a broad molecular survey of the expression levels of the thousands of genes expressed in brain.”
Human-neuronsThe researchers evaluated the role of SV2A, using human-induced neurons that carry the APOE4 genetic variant. (The neurons were generated by directed conversion of skin fibroblasts from individuals at high risk for Alzheimer’s, using a technology developed in the Abeliovich laboratory.) Treating neurons that harbor the APOE4 at-risk genetic variant with levetiracetam (which inhibits SV2A) led to reduced production of amyloid beta. The study also showed that RFN219 appears to play a role in APP-processing in cells with the APOE4 variant.