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Solar energy used to create solar energy materials

Solar energy used to create solar energy materials | Amazing Science | Scoop.it

In a recent advance in solar energy, researchers have discovered a way to tap the sun not only as a source of power, but also to directly produce the solar energy materials that make this possible.


This breakthrough by chemical engineers at Oregon State University could soon reduce the cost of solar energy, speed production processes, use environmentally benign materials, and make the sun almost a “one-stop shop” that produces both the materials for solar devices and the eternal energy to power them.


The findings were just published in RSC Advances, a journal of the Royal Society of Chemistry, in work supported by the National Science Foundation.


“This approach should work and is very environmentally conscious,” said Chih-Hung Chang, a professor of chemical engineering at Oregon State University, and lead author on the study.


“Several aspects of this system should continue to reduce the cost of solar energy, and when widely used, our carbon footprint,” Chang said. “It could produce solar energy materials anywhere there’s an adequate solar resource, and in this chemical manufacturing process, there would be zero energy impact.”


The work is based on the use of a “continuous flow” microreactor to produce nanoparticle inks that make solar cells by printing. Existing approaches based mostly on batch operations are more time-consuming and costly.


In this process, simulated sunlight is focused on the solar microreactor to rapidly heat it, while allowing precise control of temperature to aid the quality of the finished product. The light in these experiments was produced artificially, but the process could be done with direct sunlight, and at a fraction of the cost of current approaches.

“Our system can synthesize solar energy materials in minutes compared to other processes that might take 30 minutes to two hours,” Chang said. “This gain in operation speed can lower cost.”


In these experiments, the solar materials were made with copper indium diselenide, but to lower material costs it might also be possible to use a compound such as copper zinc tin sulfide, Chang said. And to make the process something that could work 24 hours a day, sunlight might initially be used to create molten salts that could later be used as an energy source for the manufacturing. This could provide more precise control of the processing temperature needed to create the solar energy materials.


State-of-the-art chalcogenide-based, thin film solar cells have already reached a fairly high solar energy conversion efficiency of about 20 percent in the laboratory, researchers said, while costing less than silicon technology. Further improvements in efficiency should be possible, they said.


Another advantage of these thin-film approaches to solar energy is that the solar absorbing layers are, in fact, very thin - about 1-2 microns, instead of the 50-100 microns of more conventional silicon cells. This could ease the incorporation of solar energy into structures, by coating thin films onto windows, roof shingles or other possibilities.

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Nanoparticles trapped with laser light temporarily violate the second law of thermodynamics

Nanoparticles trapped with laser light temporarily violate the second law of thermodynamics | Amazing Science | Scoop.it

Watching a movie played in reverse often makes us laugh because unexpected and mysterious things seem to happen: glass shards lying on the floor slowly start to move towards each other, magically assemble and suddenly an intact glass jumps on the table where it gently gets to a halt. Or snow starts to from a water puddle in the sun, steadily growing until an entire snowman appears as if molded by an invisible hand. When we see such scenes, we immediately realize that according to our everyday experience something is out of the ordinary. Indeed, there are many processes in nature that can never be reversed. The physical law that captures this behavior is the celebrated second law of thermodynamics, which posits that the entropy of a system – a measure for the disorder of a system – never decreases spontaneously, thus favoring disorder (high entropy) over order (low entropy).


However, when we zoom into the microscopic world of atoms and molecules, this law softens up and looses its absolute strictness. Indeed, at the nanoscale the second law can be fleetingly violated. Recently, a team of physicists of the University of Vienna, the Institute of Photonic Sciences in Barcelona and the Swiss Federal Institute of Technology in Zürich succeeded in accurately predicting the likelihood of events transiently violating the second law of thermodynamics. They immediately put the mathematical fluctuation theorem they derived to the test using a tiny glass sphere with a diameter of less than 100 nm levitated in a trap of laser light. Their experimental set-up allowed the research team to capture the nano-sphere and hold it in place, and, furthermore, to measure its position in all three spatial directions with exquisite precision. In the trap, the nano-sphere rattles around due to collisions with surrounding gas molecules. By a clever manipulation of the laser trap the scientists cooled the nano-sphere below the temperature of the surrounding gas and, thereby, put it into a non-equilibrium state. They then turned off the cooling and watched the particle relaxing to the higher temperature through energy transfer from the gas molecules. The researchers observed that the tiny glass sphere sometimes, although rarely, does not behave as one would expect according to the second law: the nano-sphere effectively releases heat to the hotter surroundings rather than absorbing the heat. The theory derived by the researchers to analyze the experiment confirms the emerging picture on the limitations of the second law on the nanoscale.

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Spray-On Polymer Mats of Biodegradable Nanofibers Seal Surgical Incisions

Spray-On Polymer Mats of Biodegradable Nanofibers Seal Surgical Incisions | Amazing Science | Scoop.it

Mats of polymer nanofibers show potential not only for surgery but also as biodegradable, drug-releasing implants or as scaffolds for tissue engineering, says Peter Kofinas, a bioengineer at the University of Maryland, College Park. Current methods for making the mats—such as electrospinning, which involves electric current—would damage living cells if the mats were made in situ. To devise a way to create the mats directly on the tissue, Kofinas and colleagues adapted a commercial airbrush, a tool more commonly used to apply paint.


They tinkered with different formulations of a biodegradable polymer, poly(lactic-co-glycolic acid), or PLGA, to find one that would work in the airbrush. By choosing a particular molecular weight of PLGA and concentration of acetone as the solvent, they could control the diameter of the resulting fibers. They ended up producing mats with fiber diameters of about 370 nm.


The researchers showed that the mats could seal diaphragm hernias and cuts to the lung, intestine, and liver in a pig. The acetone appears to evaporate before the nanofibers get deposited, suggesting that the solvent won’t pose toxicity problems, according to the paper. Cells sprayed with the PLGA nanofibers show no change in health after 24 hours. In lab tests, the nanofiber mats degraded completely over a 42-day period.


“Using an airbrush to deposit biomaterials directly onto tissue is quite enticing and has potential in many areas of medicine,” saysJeffrey M. Karp, a bioengineer and codirector of the Center for Regenerative Therapeutics at Brigham & Women’s Hospital, in Boston. Kofinas’s group is currently doing safety studies and improving the materials for surgical trials in laboratory animals.

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Anti-counterfeit 'fingerprints' made from silver nanowires

Anti-counterfeit 'fingerprints' made from silver nanowires | Amazing Science | Scoop.it

Unique patterns made from tiny, randomly scattered silver nanowires have been created by a group of researchers from South Korea in an attempt to authenticate goods and tackle the growing problem of counterfeiting.


The nanoscale 'fingerprints' are made by randomly dumping 20 to 30 individual nanowires, each with an average length of 10 to 50 µm, onto a thin plastic film, and could be used to tag a variety of goods from electronics and drugs to credit cards and bank notes.

They have been presented in a paper published today, 21 March, in IOP Publishing's journal Nanotechnology.


According to the researchers, the fingerprints are almost impossible to replicate because of the natural randomness of their creation and the difficulty associated with manipulating such small materials.


Lead author of the research Professor Hyotcherl Ihee, from the Korea Advanced Institute of Science and Technology (KAIST) and Institute for Basic Science (IBS), said: "It is nearly impossible to replicate the fingerprints due to the difficulty in trying to manipulate the tiny nanowires into a desired pattern. The cost of generating such an identical counterfeit pattern would generally be much higher than the value of the typical product being protected."


The researchers estimate that the fingerprints could be produced at a cost of less than $1 per single pattern, which was demonstrated in their study by synthesizing a solution containing individual silver nanowires, coating the nanowires with silica, doping them with specific fluorescent dyes and then randomly dropping them onto a transferable film made from flexible polyethylene terephthalate (PET).


The fluorescent dyes allowed the patterns, which are invisible to the naked eye, to be visually identified and authenticated under an optical microscope and could add another layer of complexity to the 'fingerprints' if a number of different coloured dyes are used.

The researchers believe the fingerprints could also be tagged with a unique ID, or barcode, which could facilitate a quick search in a database and ease the process of authentication or counterfeit identification.


"Once a pattern is tagged and stored on a database using a unique ID, a certain substrate, whether this is a bank note or a credit card, could be authenticated almost immediately by observing the fluorescence images and comparing it with stored images," continued Professor Ihee.


"These authentication processes can be automated by employing an algorithm that recognises the positions and colours of the silver nanowires and digitizes that information in a database. Such digitized information could significantly reduce the size of the stored data and reduce the time required for the authentication process."

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Nanoscale graphene origami cages set world record for densest hydrogen storage

Nanoscale graphene origami cages set world record for densest hydrogen storage | Amazing Science | Scoop.it

The U.S. Department of Energy is searching for ways to make storing energy with hydrogen a practical possibility, and they set up some goals for onboard automotive hydrogen storage systems with a driving range of 300 miles or more: the Department had hoped that by 2017, a research team could pack in 5.5 percent hydrogen by weight, and that by 2020, it could be stretched to 7.5 percent. Li’s team has already crossed that threshold, with a hydrogen storage density of 9.5 percent hydrogen by weight.  The team has also demonstrated the potential to reach an even higher density, a future research goal.


“Just like paper origami, which can make complicated 3-D structures from 2-D paper, graphene origami allows us to design and fabricate carbon nanostructures that are not naturally existing but have desirable properties,” said Li, an Associate Professor of Mechanical Engineering, a member of the Maryland NanoCenter and the University of Maryland Energy Research Center (UMERC), and a Keystone professor in the A. James Clark School of Engineering. Forming a graphene nanocage: (a) Patterned graphene is suitably hydrogenated (by bonding hydrogen atoms to the carbon atoms of planar graphene, thus warping it) and then folded (b-f) into a nanocage via electric-field assistance. (Credit: Shuze Zhu and Teng Li/ACS Nano“In this paper, we show that graphene nanocages can be used for hydrogen storage with extraordinary capacity, holding the promise to exceed the year 2020 goal of the U.S. Department of Energy on hydrogen storage,” Li explained to KurzweilAI in an email interview.


“Paper origami has existed for more than a millennium. Such a concept has been explored to enable the formation of complicated 3D structures from 2D building blocks in recent years, such as micro-robots and actuators. In these developments, the building block materials are still bulk materials, with a final resulting 3D structure of size on the order of millimeters. “The graphene origami we demonstrate in this paper uses the thinnest yet strongest materials ever made (one atom thick), leading to a nanocage on the order of several nanometers. Another unique feature of [Hydrogenation-assisted graphene origami] HAGO that does not exist in conventional origami is that programmable opening and closing of HAGO-enabled nanostructures can be controlled via an external electric field.

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Scientists are making paint that never fades, by mimicking iridescent bird feathers

Scientists are making paint that never fades, by mimicking iridescent bird feathers | Amazing Science | Scoop.it

Among the taxidermal specimens in Harvard’s Museum of Comparative Zoology, past centuries-old fur coats, arises a flicker of brilliant blue. This is the spangled cotinga. Surprisingly, the cotinga is about as old as everything in the room, but its color is still as dazzling as the day it was brought to the museum. The cotinga—or rather its feathers—achieve this effect through structural color.


Unlike color that we usually think of, which arises from paints and dyes absorbing certain wavelengths of light and reflecting the remainder, structural color is created when an object’s very nanostructure amplifies a specific wavelength. Cells in the cotinga’s feathers have a series of tiny pores spaced just right so that blues (and not much of anything else) are reflected back to our eyes. Because of this, if the feathers were thoroughly pulverized, the formation of pores and therefore the color would be lost. It also means that the same color could be produced from an entirely different material, if one could recreate the same pattern made by the feathers' pores.


Researchers led by Vinothan N. Manoharan at the Harvard School of Engineering and Applied Sciences want to recreate this effect, giving man-made materials structural color. Producing structural color is not easy, though; it often requires a material’s molecules to be in a very specific crystalline pattern, like the natural structure of an opal, which reflects a wide array of colors. But the pores on the cotinga’s feathers lack a regular order and are therefore a prime target for imitation.


Manoharan's lab has devised a system where microcapsules are filled with a disordered solution of even smaller particles suspended in water. When the microcapsule is partly dried out, it shrinks, bringing the particles closer and closer together. Eventually the average distance between all the particles will give rise to a specific reflected color from the capsule. Shrink the capsule a bit more, and they become another color, and then another.


“Most color you get in paints, coatings or cosmetics, even, comes from the selective absorption and reflection of light. What that means is that the material is absorbing some energy, and that means that over time, the material will fade,” says Manoharan.


The sun’s energy pummels the molecules in conventional pigments. Eventually, the molecules simply deteriorate and no longer absorb the colors they used to, leading to sun bleaching. Manoharan’s group is currently testing their innovation to see if it can create an effectively ageless color.


Electronic display technology—for example, e-readers—might also benefit from this advance. The microcapsules could be used in displays that create pixels with colored particles rather than LEDs, liquid crystals, or black-and-white “electronic ink.”


“We think it could be possible to create a full-color display that won’t fade over time,” says Manoharan. “The dream is that you could have a piece of flexible plastic that you can put graphics on in full color and read in bright sunlight.”

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Nanotechnology needle arrays for drug delivery

Nanotechnology needle arrays for drug delivery | Amazing Science | Scoop.it

It is estimated that as much as 99% of medicinal molecules administered during a therapy don't reach their targets and subsequently stay in the body of the patient. Some of these molecules can be very toxic, especially cancer drugs, and the potential side effects of many therapeutic drugs can be downright frightening – just read the instruction leaflet that comes with your pills.These effects often occur when a drug is active throughout the body, not just where and when it is needed. As opposed to having patients simply swallow a pill, health care professionals have long envisioned delivering specific quantities of medicines to targeted areas of the body, thereby increasing the treatment’s effectiveness while reducing side effects. In order to achieve this, a 'vehicle' of sorts is needed to safely and accurately deliver the medicine to the desired location within the body.


The ultimate goal of nanotechnology-enabled drug delivery, especially with regard to cancer therapy, is to ferry most of the administered drug to the target, while eliminating the accumulation of the drug at any non-target tissues.


Nanomedicine applications with targeted nanoparticles are expected to revolutionize cancer therapy. The use of such nanoparticles to deliver therapeutic agents is currently being studied as a promising method by which drugs can be effectively targeted to specific cells in the body, such as tumor cells.Biological barriers – the skin, mucosal membranes, the blood-brain barrier and cell/nuclear membranes – seriously limit the delivery of drugs into the desired sites within the body, resulting in a low delivery efficacy, poor therapeutic efficacy, and high cost.Nanomedicine researchers have developed numerous biological, chemical, and physical strategies to overcome these barriers.


A new review paper in Advanced Materials highlights recent advanced physical approaches for transdermal and intracellular delivery ("Advanced Materials and Nanotechnology for Drug Delivery").


Via Szabolcs Kósa
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Smart holographic sensors can test for and monitor diseases

Smart holographic sensors can test for and monitor diseases | Amazing Science | Scoop.it

A team of interdisciplinary researchers have created "smart" holograms that can monitor health conditions or diagnose diseases, by changing color in the presence of disease indicators in a person's breath or bodily fluids. When developed into a portable medical test, these responsive holograms could make testing for medical conditions and monitoring one's health very easy, the scientists claim.


A person would just have to check the hologram's color against a chart or use a camera phone to read the results. As these holographic sensors don't require batteries, electricity or lasers to function, it's possible to create inexpensive portable tests for healthcare workers to use or people to self-administer, that could help them potentially diagnose diseases in their earliest stages.


"We often see holograms on banknotes, credit cards, as security features, or artwork," Ali Yetisen, a PhD student at the University of Cambridge, UK, who led the research, tells Gizmag. "However, these type of holograms do not response when they encounter a health condition indicator such as glucose or blood electrolytes. We have developed techniques to make these holograms 'smart,' so that they can respond to a wide range of disease markers."


The holographic sensors are made out of hydrogels (a highly absorbent material) that are doped with silver nanoparticles. These silver nanoparticles are then organized into three-dimensional holograms of predetermined shapes using a multi-megawatt laser. The final sensors resemble the iridescent hardened forewings of beetles, and normally diffract light in a green color. 


However, when the holographic sensor is exposed to a person's breath, urine, tears or a drop of their blood or saliva, the hydrogel in the sensor, which is sensitive to specific disease indicators, reacts if any of them are present. The hydrogel either swells or shrinks, causing a change in the hologram's color in the entire visible spectrum. It's the first time, the researchers claim, that they've been able to achieve such a result with a colorimetric sensor. 


"It's pretty much like a butterfly wing," says Dr. Haider Butt, a Lecturer in Micro Engineering and Nanotechnology, at the University of Birmingham and a co-author of the study. "But this is a butterfly wing that changes color depending on the solution we dip it in."


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Making nanoelectronics last longer for medical devices and ‘cyborgs’

Making nanoelectronics last longer for medical devices and ‘cyborgs’ | Amazing Science | Scoop.it

Harvard scientist Charles Lieber and colleagues have developed a coating that makes nanoelectronics much more stable in conditions mimicking those in the human body.


The advance could aid in the development of very small implanted medical devices for monitoring health and disease, and could speed up the debut of cyborgs who are part human, the researchers say.

Nanoelectronics devices with nanowire components are much smaller than most implanted medical devices used today, and have unique abilities to probe and interface with living cells. Laboratory versions made of silicon nanowires can detect disease biomarkers and even single virus cells, or record heart cells as they beat.


However, nanoelectronics devices have one obstacle to their practical, long-term use: they typically fall apart within weeks or days when implanted.


The researchers found that coating with a metal oxide shell allowed nanowire devices to last for several months. This was in conditions that mimicked the temperature and composition of the inside of the human body. In preliminary studies, one shell material, hafnium oxide-aluminum oxide nanolaminated shells, appeared to extend the lifespan of nanoelectronics to more than a year.

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Tiny single-chip device to provide real-time ultrasonic 3D images from inside the heart and blood vessels

Tiny single-chip device to provide real-time ultrasonic 3D images from inside the heart and blood vessels | Amazing Science | Scoop.it

Georgia Institute of Technology researchers have developed the technology for a catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels. With its volumetric imaging, the new device could better guide surgeons working in the heart, and potentially allow more of patients’ clogged arteries to be cleared without major surgery.


The device integrates ultrasound transducers with processing electronics on a single 1.4 millimeter  CMOS silicon chip. On-chip processing of signals allows data from more than a hundred elements on the device to be transmitted using just 13 tiny cables, permitting it to easily travel through circuitous blood vessels. The forward-looking images produced by the device would provide significantly more information than existing cross-sectional ultrasound.


“Our device will allow doctors to see the whole volume that is in front of them within a blood vessel,” said F. Levent Degertekin, a professor in the George W. Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. “This will give cardiologists the equivalent of a flashlight so they can see blockages ahead of them in occluded arteries. It has the potential for reducing the amount of surgery that must be done to clear these vessels.”


“If you’re a doctor, you want to see what is going on inside the arteries and inside the heart, but most of the devices being used for this today provide only cross-sectional images,” Degertekin explained. “If you have an artery that is totally blocked, for example, you need to see the front, back and sidewalls altogether. That kind of information is basically not available at this time.”


The single chip device combines capacitive micromachined ultrasonic transducer (CMUT) arrays with front-end CMOS electronics technology to provide three-dimensional intravascular ultrasound (IVUS) and intracardiac echography (ICE) images.


Researchers have developed and tested a prototype able to provide image data at 60 frames per second. The researchers expect to conduct animal trials to demonstrate the device’s potential applications. They ultimately expect to license the technology to an established medical diagnostic firm to conduct the clinical trials necessary to obtain FDA approval.


For the future, Degertekin hopes to develop a version of the device that could guide interventions in the heart under magnetic resonance imaging (MRI). Other plans include further reducing the size of the device to place it on a 400-micron diameter guide wire.


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A novel form of artificial graphene: Two-Dimensional Semiconductors with a Honeycomb Nanogeometry

A novel form of artificial graphene: Two-Dimensional Semiconductors with a Honeycomb Nanogeometry | Amazing Science | Scoop.it

A new breed of ultra thin super-material has the potential to cause a technological revolution. “Artificial graphene” should lead to faster, smaller and lighter electronic and optical devices of all kinds, including higher performance photovoltaic cells, lasers or LED lighting.


For the first time, scientists are able to produce and have analysed artificial graphene from traditional semiconductor materials. Such is the scientific importance of this breakthrough these findings were published recently in one of the world’s leading physics journals, Physical Review X. A researcher from the University of Luxembourg played an important role in this highly innovative work.


Graphene (derived from graphite) is a one atom thick honeycomb lattice of carbon atoms. This strong, flexible, conducting and transparent material has huge scientific and technological potential. Only discovered in 2004, there is a major global push to understand its potential uses. Artificial graphene has the same honeycomb structure, but in this case, instead of carbon atoms, nanometer-thick semiconductor crystals are used. Changing the size, shape and chemical nature of the nano-crystals, makes it possible to tailor the material to each specific task.

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Fantastic Voyage: Nanomotors are inserted and controlled, for the first time, inside living cells

Fantastic Voyage: Nanomotors are inserted and controlled, for the first time, inside living cells | Amazing Science | Scoop.it

For the first time anywhere, a team of chemists and engineers at Penn State has placed tiny synthetic motors inside live human cells, propelled them with ultrasonic waves and steered them magnetically. It's not exactly "Fantastic Voyage," but it's close. The nanomotors, which are rocket-shaped metal particles, move around inside the cells, spinning and battering against the cell membrane.


"As these nanomotors move around and bump into structures inside the cells, the live cells show internal mechanical responses that no one has seen before," said Tom Mallouk, Evan Pugh Professor of Materials Chemistry and Physics. "This research is a vivid demonstration that it may be possible to use synthetic nanomotors to study cell biology in new ways. We might be able to use nanomotors to treat cancer and other diseases by mechanically manipulating cells from the inside. Nanomotors could perform intracellular surgery and deliver drugs noninvasively to living tissues."


Up until now, Mallouk said, nanomotors have been studied only "in vitro" in a laboratory apparatus, not in living human cells. Chemically powered nanomotors were first developed 10 years ago at Penn State by a team that included chemist Ayusman Sen and physicist Vincent Crespi, in addition to Mallouk.


"Our first-generation motors required toxic fuels and they would not move in biological fluid, so we couldn't study them in human cells," Mallouk said. "That limitation was a serious problem." When Mallouk and French physicist Mauricio Hoyos discovered that nanomotors could be powered by ultrasonic waves, the door was open to studying the motors in living systems.


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Capturing ten-color ultrasharp images of synthetic DNA structures resembling numerals 0 to 9

Capturing ten-color ultrasharp images of synthetic DNA structures resembling numerals 0 to 9 | Amazing Science | Scoop.it

A new microscopy method could enable scientists to generate snapshots of dozens of different biomolecules at once in a single human cell, a team from the Wyss Institute of Biologically Inspired Engineering at Harvard University reported Sunday in Nature Methods.


Such images could shed light on complex cellular pathways and potentially lead to new ways to diagnose disease, track its prognosis, or monitor the effectiveness of therapies at a cellular level.


Cells often employ dozens or even hundreds of different proteins and RNA molecules to get a complex job done. As a result, cellular job sites can resemble a busy construction site, with many different types of these tiny cellular workers coming and going. Today's methods typically only spot at most three or four types of these tiny workers simultaneously. But to truly understand complex cellular functions, it's important to be able to visualize most or all of those workers at once, said Peng Yin, Ph.D., a Core Faculty member at the Wyss Institute and Assistant Professor of Systems Biology at Harvard Medical School.


To capture ultrasharp images of biomolecules, they had to overcome laws of physics that stymied microscopists for most of the last century. When two objects are closer than about 200 nanometers apart — about one five-hundredth the width of a human hair — they cannot be distinguished using a traditional light microscope: the viewer sees one blurry blob where in reality there are two objects.


Since the mid-1990s, scientists have developed several ways to overcome this problem using combinations of specialized optics, special fluorescent proteins or dyes that tag cellular components.


Ralf Jungmann, Ph.D., now a Postdoctoral Fellow working with Yin at the Wyss Institute and Harvard Medical School, helped develop one of those super-resolution methods, called DNA-PAINT, as a graduate student. DNA-PAINT can create ultrasharp snapshots of up to three cellular workers at once by labeling them with different colored dyes.


To visualize cellular job sites with crews of dozens of cellular workers, Yin's team, including Jungmann, Maier Avendano, M.S., a graduate student at Harvard Medical School, and Johannes Woehrstein, a postgraduate research fellow at the Wyss Institute, modified DNA-PAINT to create a new method called Exchange-PAINT.


Exchange-PAINT relies on the fact that DNA strands with the correct sequence of letters, or nucleotides, bind specifically to partner strands with complementary sequences. The researchers label a biomolecule they want to visualize with a short DNA tag, then add to the solution a partner strand carrying a fluorescent dye that lights up only when the two strands pair up. When that partner strand binds the tagged biomolecule, it lights up, then lets go, causing the biomolecule to "blink" at a precise rate the researchers can control. The researchers use this blinking to obtain ultrasharp images.


To test Exchange-PAINT, the researchers created 10 unique pieces of folded DNA, or DNA origami, that resembled the numerals 0 through 9. These numerals could be resolved with less than 10 nanometers resolution, or one-twentieth of the diffraction limit.


The team was able to use Exchange-PAINT to capture clear images of the 10 different types of miniscule DNA origami structures in one image. They also used the method to capture detailed, ultrasharp images of fixed human cells, with each color tagging an important cellular component — microtubules, mitochondria, Golgi apparatus, or peroxisomes.

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Ordered carbon-nanotube design may increase conductivity of solar cells by 100 million times

Ordered carbon-nanotube design may increase conductivity of solar cells by 100 million times | Amazing Science | Scoop.it

Controlled placement of carbon nanotubes in nanostructures could result in a huge boost in electronic performance in photovoltaic solar cells, researchers at Umeå University in Sweden have discovered.


In the new study, published in Advanced Materials, the researchers were able to engineer the nanotubes into complex network architectures with controlled nanoscale dimensions inside a polymer matrix. That structure allows for better conductivity (lower loss of power) and reduction of the number of high-cost nanotubes needed.


“We have found that the resulting nano networks possess exceptional ability to transport charges, up to 100 million times higher than previously measured carbon nanotube random networks produced by conventional methods,” says David Barbero, project leader and assistant professor at the Department of Physics at Umeå University.


“This innovation has direct implications for the next generation of carbon-based solar cells, which use carbon nanotubes and other carbon materials (graphene, semi-conducting polymers, etc.),” Barbero told KurzweilAI. “That’s because the new nano-engineered networks show much increased charge transport compared to commonly used networks today. These new nano-networks could also in principle be advantageously used in any nanocomposite material where efficient charge transport is required, and where low amounts of nanotubes are necessary.


“This new architecture enables a higher degree of interconnection between nanotubes and more robust charge transport pathways in the device,” he explained. “This is expected to increase device efficiency, but also to reduce materials costs because at least 100 times less nanotubes are necessary to form efficient charge transport networks.”


Barbero could not predict when this new technology might go into production, but hinted that “this field is moving fast and things can happen quickly, so stay tuned.”


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Novel paper nanofilter can remove viruses efficiently

Novel paper nanofilter can remove viruses efficiently | Amazing Science | Scoop.it
Researchers at the Division of Nanotechnology and Functional Materials, Uppsala University have developed a paper filter, which can remove virus particles with an efficiency matching that of the best industrial virus filters. The paper filter consists of 100 percent high purity cellulose nanofibers, directly derived from nature.


The research was carried out in collaboration with virologists from the Swedish University of Agricultural Sciences/Swedish National Veterinary Institute and is published in the Advanced Healthcare Materials journal.


Virus particles are very peculiar objects- tiny (about thousand times thinner than a human hair) yet mighty. Viruses can only replicate in living cells but once the cells become infected the viruses can turn out to be extremely pathogenic. Viruses can actively cause diseases on their own or even transform healthy cells to malignant tumors.


‘Viral contamination of biotechnological products is a serious challenge for production of therapeutic proteins and vaccines. Because of the small size, virus removal is a non-trivial task, and, therefore, inexpensive and robust virus removal filters are highly demanded’, says Albert Mihranyan, Associate Professor at the Division of Nanotechnology and Functional Materials, Uppsala University, who heads the study.


Cellulose is one of the most common materials to produce various types of filters because it is inexpensive, disposable, inert and non-toxic. It is also mechanically strong, hydrophyllic, stable in a wide range of pH, and can withstand sterilization e.g. by autoclaving. Normal filter paper, used for chemistry, has too large pores to remove viruses.


The undergraduate student Linus Wågberg, Professor Maria Strømme, and Associate Professor Albert Mihranyan at the Division of Nanotechnology and Functional Materials, Uppsala University, in collaboration with virologists Dr. Giorgi Metreveli, Eva Emmoth, and Professor Sándor Belák from the Swedish University of Agricultural Sciences (SLU)/Swedish National Veterinary Institute (SVA), report a design of a paper filter which is capable of removing virus particles with the efficiency matching that of the best industrial virus filters. The reported paper filter, which is manufactured according to the traditional paper making processes, consists of 100 percent high purity cellulose nanofibers directly derived from nature.


The discovery is a result of a decade long research on the properties of high surface area nanocellulose materials, which eventually enabled the scientists to tailor the pore size distribution of their paper precisely in the range desirable for virus filtration.

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Unavoidable disorder used to build nanolaser

Unavoidable disorder used to build nanolaser | Amazing Science | Scoop.it

Researchers the world round are working to develop optical chips, where light can be controlled with nanostructures. These could be used for future circuits based on light (photons) instead of electron - that is photonics instead of electronics. But it has proved to be impossible to achieve perfect photonic nanostructures: they are inevitably a little bit imperfect. Now researchers at the Niels Bohr Institute in collaboration with DTU have discovered that imperfect nanostructures can offer entirely new functionalities. They have shown that imperfect optical chips can be used to produce 'nanolasers', which is an ultimately compact and energy-efficient light source. The results are published in the scientific journal Nature Nanotechnology.


The researchers are working with extremely small photonic crystal membranes - the width of the membrane is 25 micrometer, and the thickness is 340 nanometers (1 nanometer is one thousandth of a micrometer). The crystals are made of the semiconducting material gallium arsenide (GaAs). A pattern of holes are etched into the material at a regular distance of 380 nanometers. The holes have the function of acting as built-in mirrors that reflect the light and can thus be used to control the spread of the light in the optical chip. The researchers have therefore tried to achieve as perfect a regular structure of holes as possible to control the light in certain optical circuit.


"It turns out that the imperfect optical chips are extremely well suited for capturing light. When the light is sent into the imperfect chip, it will hit the many small irregular holes, which reflect the light in random directions. Due to the frequent reflections, the light is spontaneously captured in the nanostructure and cannot escape. This allows the light to be amplified, resulting in surprisingly good conditions for creating highly efficient and compact lasers," explains Peter Lodahl, professor and head of the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen.

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Diagnosis by Light: How to Shrink Chemical Labs Onto Optical Fibers

Diagnosis by Light: How to Shrink Chemical Labs Onto Optical Fibers | Amazing Science | Scoop.it

Lab-on-fiber sensors could monitor the environment and hunt for disease inside your body.


Imagine an entire laboratory that fits inside a case the size of a tablet computer. The lab would include an instrument for reading out results and an array of attachable microsize probes for detecting molecules in a fluid sample, such as blood or saliva. Each probe could be used to diagnose one of many different diseases and health conditions and could be replaced for just a few cents.


This scenario is by no means a pipe dream. The key to achieving it will be optical glass fibers—more or less the same as the ones that already span the globe, ferrying voluminous streams of data and voice traffic at unmatchable speeds. Their tiny diameter, dirt-cheap cost, and huge information-carrying capacity make these fibers ideal platforms for inexpensive, high-quality chemical sensors.


We call this technology a lab on fiber. Beyond being an affordable alternative to a traditional laboratory, it could take on tasks not possible now. For instance, it could be snaked inside industrial machines to ensure product quality and test for leaks. It could monitor waterways and waste systems, survey the oceans, or warn against chemical warfare. One day, maybe as soon as a decade from now, it could be injected into humans to look for disease orstudy the metabolism of drugs inside the body.


It will probably be at least five years before lab-on-fiber instruments are ready for commercial use. For example, a remaining major challenge is figuring out how to toughen the surface coating on the probes so that they can be stored for several months without becoming unstable and thereby losing their ability to bind with target molecules.


Nevertheless, lab-on-fiber technology is tantalizingly close to being able to compete in cost and performance with today’s diagnostic tools for many applications. One of the first might very well be a blood test: Imagine turning on your home lab kit, pricking your finger, and blotting the blood on an array of fiber probes. In just a few minutes, the machine would automatically e-mail the results to your doctor, who could get back to you within hours if there was a problem. Meanwhile, you could get on with the rest of your day.

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Nanoscale optical switch breaks miniaturization barrier

Nanoscale optical switch breaks miniaturization barrier | Amazing Science | Scoop.it

A new ultra-fast, ultra-small optical switch could advance the day when photons replace electrons in consumer products ranging from cell phones to automobiles. It was developed by a team of scientists from Vanderbilt University, University of Alabama-Birmingham, and Los Alamos National Laboratory.


Described in the March 12 issue of the journal Nano Letters, the new optical device can turn on and off trillions of times per second. It consists of individual switches that are only 200 nanometers in diameter — much smaller than the current generation of optical switches. It overcomes one of the major technical barriers to the spread of electronic devices that detect and control light: miniaturizing the size of ultrafast optical switches.


The ultrafast switch is made out of a metamaterial (artificial material) engineered to have properties that are not found in nature. The metamaterial consists of nanoscale particles of vanadium dioxide (VO2) — a crystalline solid that can rapidly switch back and forth between an opaque, metallic phase and a transparent, semiconducting phase — which are deposited on a glass substrate and coated with a “nanomesh” of tiny gold nanoparticles.

The scientists report that bathing these gold nanoparticles with brief pulses from an ultrafast laser generates hot electrons in the gold particles that jump into the vanadium dioxide and cause it to undergo its phase change in a few trillionths of a second.


“We had previously triggered this transition in vanadium dioxide nanoparticles directly with lasers and we wanted to see if we could do it with electrons as well,” said Richard Haglund, Stevenson Professor of Physics at Vanderbilt, who led the study. “Not only does it work, but the injection of hot electrons from the gold nanoparticles also triggers the transformation with one fifth to one tenth as much energy input required by shining the laser directly on the bare VO2.”


Both industry and government are investing heavily in efforts to integrate optics and electronics, because it is generally considered to be the next step in the evolution of information and communications technology. Intel, Hewlett-Packard and IBM have been building chips with increasing optical functionality for the last five years that operate at gigahertz speeds, one thousandth that of the VO2 switch.

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Medical microrobots to deliver drugs on demand

Medical microrobots to deliver drugs on demand | Amazing Science | Scoop.it

Advances in micro- and nanoscale engineering in the medical field have led to the development of various robotic designs that one day will allow a new level of minimally invasive medicine. These micro- and nanorobots will be able to reach a targeted area, provide treatments and therapies for a desired duration, measure the effects and, at the conclusion of the treatment, be removed or degrade without causing adverse effects. Ideally, all these tasks would be automated but they could also be performed under the direct supervision and control of an external user.Several approaches have been explored for the wireless actuation of microrobots. Among these, magnetic fields have been the most widely employed strategy for propulsion because they do not require special environmental properties such as conductivity or transparency (for instance: "Artificial nano swimmers", with a video that shows the controlled motions of particles in a magnetic field).


This approach allows for the precise manipulation of magnetic objects toward specific locations, and magnetic fields are biocompatible even at relatively high field strengths (MRI).In a new work, a team of researchers from ETH Zurich and Harvard University (David Mooney's lab) demonstrate that additional intelligence – including sensing and actuation – can be instantiated in these microrobots by selecting appropriate materials and methods for the fabrication process.


"Our work combines the design and fabrication of near infrared light (NIR) responsive hydrogel capsules and biocompatible magnetic microgels with a magnetic manipulation system to perform targeted drug and cell delivery tasks, Dr." Mahmut Selman Sakar, a research scientist in Bradley Nelson's Institute of Robotics and Intelligent Systems at ETH Zurich, tells Nanowerk.Reporting their results in the November 4, 2013 online edition of Advanced Materials ("An Integrated Microrobotic Platform for On-Demand, Targeted Therapeutic Interventions"), first-authored by Sakar's co-researcher Stefano Fusco, the team fabricated an untethered, self-folding, soft microrobotic platform, in which different functionalities are integrated to achieve targeted, on-demand delivery of biological agents.

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Jose Mejia R's comment, March 30, 2014 11:40 AM
TRADUCCION:<br>Los avances en la ingeniería de micro-y nanoescala en el campo de la medicina han conducido al desarrollo de diversos diseños robóticos que un día permitirá un nuevo nivel de la medicina mínimamente invasiva. Estos micro-y nano-robots serán capaces de llegar a un área objetiva, proporcionar tratamientos y terapias para una duración deseada, medir los efectos y, a la conclusión del tratamiento, deberá ser eliminado o degradado sin causar efectos adversos. Lo ideal sería que todas estas tareas se pueden automatizar, pero también pueden ser realizados bajo la supervisión y el control directos de un usuario externo. Varios enfoques se han explorado para el accionamiento inalámbrico de microrobots. Entre éstos, los campos magnéticos han sido la estrategia más ampliamente empleada para la propulsión, ya que no requieren propiedades especiales del medio ambiente tales como la conductividad o la transparencia (por ejemplo: "nadadores nano artificial", con un vídeo que muestra los movimientos controlados de partículas en una magnética campo).<br> <br>Este enfoque permite la manipulación precisa de objetos magnéticos hacia lugares específicos, y los campos magnéticos son biocompatibles, incluso a intensidades de campo relativamente altas (MRI). En un nuevo trabajo, un equipo de investigadores de ETH Zurich y la Universidad de Harvard (el laboratorio de David Mooney) demuestran que con inteligencia adicional - incluyendo detección y actuación - se puede crear instancias de estos microrobots seleccionando materiales y procedimientos para el proceso de fabricación adecuadas.<br><br>"Nuestro trabajo combina el diseño y la fabricación de la luz en el infrarrojo cercano (NIR) cápsulas de hidrogel sensible y microgeles magnéticas biocompatibles con un sistema de manipulación magnética para realizar tareas de administración de drogas y de suministro de células específicas, nos diece el Dr. Mahmut Sakar Selman, un científico de investigación en el Instituto de Bradley Nelson de Robótica y Sistemas Inteligentes en la ETH Zurich. Sus resultados indicados el 04 de noviembre 2013 en la edición en línea de Materiales Avanzados ...
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Metal nanotubes make for better batteries

Metal nanotubes make for better batteries | Amazing Science | Scoop.it

Researchers in the US have taken an important step towards understanding exactly how single-walled carbon nanotubes (SWCNTs) boost the performance of lithium-ion batteries. The team found that metallic SWCNTs are able to accommodate more lithium atoms than semiconducting SWCNTs, which could lead to better performance. The research also reveals how semiconducting SWCNTs could be made to take up more lithium. The work could have a broad practical impact because lithium-ion batteries are used in a range of portable electronic devices.


SWCNTs are frequently employed as additives in lithium-ion batteries to improve the lifetime of the battery and its charge and discharge rates. However, SWCNTs come in two electronic flavours – metallic and semiconducting – and it was not clear whether both types were boosting performance or if one flavour was responsible for the bulk of the improvement.


Now, researchers at Northwestern University and the Argonne National Laboratory in the US have found that a nanotube's electronic type affects how easily it can accommodate lithium. Their research also reveals that the spacing between nanotubes in a battery also appears to influence the uptake of lithium.


The team, led by Mark Hersam of Northwestern, used a technique called density gradient ultracentrifugation (DGU) to separate metallic and semiconducting SWCNTs. SWCNTs are always produced in a mix of both electronic types – typically 33% metallic and 67% semiconducting.


The researchers dispersed unsorted tubes in water using two surfactants. Because the surfactant wraps around the tubes in a different way depending on their electronic type, the metallic and semiconducting tubes end up with different buoyant densities and can therefore be separated using DGU.


After sorting the tubes into metallic and semiconducting batches, the team processed them into freestanding films using vacuum filtration. The films were subsequently used as the cathodes in lithium-ion half-cell batteries with the lithium metal as the anode. The researchers measured properties such as cell capacity, charge-transfer (or Coulomb) efficiency, and battery cycling rates of devices made from each type of tube to determine how easily each one took up lithium. These studies were augmented with theoretical calculations.


Hersam and colleagues found that metallic SWCNTs accommodate lithium much more efficiently than their semiconducting counterparts. Another important discovery was that, if made denser, the semiconducting SWCNT films also begin to take up lithium at levels that are comparable to metallic SWCNTs. This is because lithium is more easily accommodated at the junctions between tubes, says Hersam.  

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Reusable gecko-inspired adhesive tape shrugs off the "dirt"

Reusable gecko-inspired adhesive tape shrugs off the "dirt" | Amazing Science | Scoop.it

Geckos' feet are right up there with adhesive tape, when it comes to being able to stick to things. Unlike tape, however, those feet retain their adhesive qualities even after many, many uses. Now, thanks to research being conducted at Carnegie Mellon University and Germany's Karlsruhe Institute of Technology, we may one day be using self-cleaning reusable gecko-inspired tape.


The feet get their stickiness from millions of microscopic hair-like projections known as setae. These temporarily bond with surfaces at a molecular level, thanks to the effect of Van der Waals forces. When a gecko walks forward, the friction created by its foot dragging laterally against the surface causes larger dirt particles to roll off of the setae, while smaller particles fall down between them into folds in the lizards' skin. This is what is largely responsible for the self-cleaning aspect of the feet.


The scientists copied this effect by creating mushroom-shaped elastic microhairs modeled after setae, in three sizes. Instead of dirt, the researchers spread tiny glass spheres on a plate. A piece of tape covered in the microhairs was then pressed down onto that plate, slid laterally, and then pulled off again – in the same fashion in which a gecko might step on it.


In cases where the microhairs were smaller in diameter than the spheres, the tape initially lost its adhesive force after its first contact with the plate, but then regained 80 to 100 percent of it after eight to ten subsequent applications. This was due to the self-cleaning effect kicking in, as the spheres rolled off the microhairs.


When the microhairs were larger in diameter than the spheres, however, the spheres tended to fall down between them instead rolling off. Because there were no skin folds for the spheres to disappear into, the self-cleaning effect wasn't as pronounced – only one third of the tape's original adhesive force came back after repeated applications.


Because of this, the scientists believe that smaller microhairs (in the nanometer-wide range) should work best at repelling dirt, as they would be smaller in diameter than most dirt particles. The team has already artificially reproduced the skin folds, which could be used for trapping dust particles, and plan on testing a new-and-improved version of the tape on actual dirt in the near future. It is hoped that once perfected, it could be used in applications including "reusable tapes, clothing closures and medical adhesives."


Perhaps not surprisingly, this isn't the first time that reusable gecko-foot tape has been created. Other versions have previously been developed at the University of Massachusetts Amherst and the University of Kiel.

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Magnetic medicine: nanoparticles and magnetic fields train immune cells to fight cancer in mice

Magnetic medicine: nanoparticles and magnetic fields train immune cells to fight cancer in mice | Amazing Science | Scoop.it
Applying a magnetic field caused the nano-aAPCs (iron nanoparticles with T-cell-activating proteins) --- and their receptors on T-cells --- to cluster


Johns Hopkins researchers have trained the immune systems of mice to fight melanoma, a deadly skin cancer, by using nanoparticles designed to target cancer-fighting immune cells,  The experiments, described in ACS Nano February 24, represent a significant step toward using nanoparticles and magnetism to treat a variety of conditions, the researchers say.


“By using small enough particles, we could, for the first time, see a key difference in cancer-fighting cells, and we harnessed that knowledge to enhance the immune attack on cancer,” said Jonathan Schneck, M.D., Ph.D., a professor of pathology, medicine and oncology at the Johns Hopkins University School of Medicine‘s Institute for Cell Engineering.


Schneck’s team has pioneered the development of artificial white blood cells (“artificial antigen-presenting cells” or aAPCs), which show promise in training animals’ immune systems to fight diseases such as cancer. To do that, the aAPCs must interact with immune cells known as naive T cells that are already present in the body, awaiting instructions about which specific invader they will battle.


The aAPCs bind to specialized receptors on the T cells’ surfaces, “presenting” the T cells with distinctive proteins called antigens. This process activates the T cells, programming them to battle a specific threat such as a virus, bacteria, or tumor, as well as to make more T cells.  The team had been working with microscale particles, which are about one-hundredth of a millimeter across. But, says Schneck, aAPCs of that size are still too large to get into some areas of a body and may even cause tissue damage because of their relatively large size. In addition, the microscale particles bound equally well to naive T cells and others, so the team began to explore using much smaller nanoscale aAPCs.


Since size and shape are central to how aAPCs interact with T cells, Karlo Perica, a graduate student in Schneck’s laboratory, tested the impact of these smaller particles. To see whether there indeed was a relationship between activation and receptor clustering, Perica applied a magnetic field to the cells, causing the iron-based nano-aAPCs to attract one another and cluster together, bringing the receptors with them. The clustering did indeed activate the naive T cells, and it made the activated cells even more active — effectively ramping up the normal immune response.


To examine how the increased activation would play out in living animals,  Perica tested the impact of these smaller particles.treated a sample of T cells with nano-aAPCs targeting those T cells that were programmed to battle melanoma. The researchers next put the treated cells under a magnetic field and then put them into mice with skin tumors.


The tumors in mice treated with both nano-aAPCs and magnetism stopped growing, and by the end of the experiment, they were about 10 times smaller than those of untreated mice, the researchers found. In addition, they report, six of the eight magnetism-treated mice survived for more than four weeks showing no signs of tumor growth, compared to zero of the untreated mice.


“We were able to fine-tune the strength of the immune response by varying the strength of the magnetic field and how long it was applied, much as different doses of a drug yield different effects,” says Perica. “We think this is the first time magnetic fields have acted like medicine in this way.”

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Rice’s carbon nanotube fibers outperform copper in regards to carry electrical current

Rice’s carbon nanotube fibers outperform copper in regards to carry electrical current | Amazing Science | Scoop.it

On a pound-per-pound basis, carbon nanotube-based fibers invented at Rice University have greater capacity to carry electrical current than copper cables of the same mass, according to new research.


While individual nanotubes are capable of transmitting nearly 1,000 times more current than copper, the same tubes coalesced into a fiber using other technologies fail long before reaching that capacity.

But a series of tests at Rice showed the wet-spun carbon nanotube fiber still handily beat copper, carrying up to four times as much current as a copper wire of the same mass.


That, said the researchers, makes nanotube-based cables an ideal platform for lightweight power transmission in systems where weight is a significant factor, like aerospace applications.


The analysis led by Rice professors Junichiro Kono and Matteo Pasquali appeared online this week in the journal Advanced Functional Materials. Just a year ago the journal Science reported that Pasquali’s lab, in collaboration with scientists at the Dutch firm Teijin Aramid, created a very strong conductive fiber out of carbon nanotubes.


Present-day transmission cables made of copper or aluminum are heavy because their low tensile strength requires steel-core reinforcement.


Scientists working with nanoscale materials have long thought there’s a better way to move electricity from here to there. Certain types of carbon nanotubes can carry far more electricity than copper. The ideal cable would be made of long metallic “armchair” nanotubes that would transmit current over great distances with negligible loss, but such a cable is not feasible because it’s not yet possible to manufacture pure armchairs in bulk, Pasquali said.


In the meantime, the Pasquali lab has created a method to spin fiber from a mix of nanotube types that still outperforms copper. The cable developed by Pasquali and Teijin Aramid is strong and flexible even though at 20 microns wide, it’s thinner than a human hair.

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Scientists use DNA strands to build decomposable nanostructures

Scientists use DNA strands to build decomposable nanostructures | Amazing Science | Scoop.it

A team of researchers in Canada has found a way around the problem of large nanostructures that are used to combat tumors, remaining in the body after they are no longer needed. In their paper published in the journal Nature Nanotechnology, the team describes a technique they developed where they used DNA strands to tie together small nanostructures creating larger nanostructures, that over time—after a tumor had been reduced—broke down and left the body.

Over the past several years, researchers have discovered that nanostructures, built from nanoparticles can be used to deliver drugs directly to a tumor, killing it. This is preferential to chemotherapy because it harms only tumor cells, rather than healthy cells throughout the body. The down side is that the nanostructures are made of materials that are considered toxic if they build up in the body and worse, are a little too big for the body to break down and get rid of. Thus, the nanostructures remain after they are no longer needed. To get around this problem, the researchers took a very unique approach, they used DNA strands to tie small nanostructures together, creating a large enough structure to transport tumor killing drugs. But because they are tied together with DNA, they become untied as the body breaks down the DNA strands. Once loosed, the nanostructures revert back to groups of smaller structures which the body can process and get rid of.


The concept was tested in mice, and results thus far indicate that the process worked as planned—the team was able to actually see the nanostructures as they appeared in the mouse urine, proving that the mice's systems were able to remove the smaller sized nanostructures from the tumor site and pass them through to the renal system.


The researchers report that their technique at this time shows promise, but of course, more work will have to be done to prove that the technique is safe, and that the nanostructures can hold together long enough to do their job. They believe their work will lead to new types of cancer killing agents, but they won't be ready for use in humans for at least five to ten years.

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Nanoribbons of graphene conduct electricity ten times better than theory predicted

Nanoribbons of graphene conduct electricity ten times better than theory predicted | Amazing Science | Scoop.it

Physicists have produced nanoribbons of graphene — the single-atom-thick carbon — that conduct electrons better than theory predicted even for the most idealized form of the material. The finding could help graphene realize its promise in high-end electronics, where researchers have long hoped it could outperform traditional materials such as silicon.Carbon layers grown on silicon carbide conduct electricity even better than theory predicted.


In graphene, electrons can move faster than in any other material at room temperature. But techniques that cut sheets of graphene into the narrow ribbons needed to form wires of a nano-scale circuit leave ragged edges, which disrupt the electron flow (further reading: Graphene: The quest for supercarbon').


Now a team led by physicist Walt de Heer at the Georgia Institute of Technology in Atlanta has made ribbons that conduct electric charges for more than 10 micrometres without meeting resistance — 1,000 times farther than in typical graphene nanoribbons1. The ribbons made by de Heer's team in fact conduct electrons ten times better than standard theories of electron transport they should, say the authors. This unimpeded motion means that circuits could transmit signals faster and without the overheating issues that hamper typical semiconductor chips.

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