Researchers at Rice University in Houston, Texas, have developed a nanoporous material that has the energy density (the amount of energy stored per unit mass) of an electrochemical battery and the power density (the maximum amount of power that can be supplied per unit mass) of a supercapacitor. It’s important to note that the energy storage device enabled by the material is not claimed to be either of these types of energy storage devices.
A leading global chemist has come to the Sunshine Coast to discuss how his team is close to creating a successful nano submarine that could revolutionise the healthcare system.
When asked what exactly a “nano submarine” was, University of California San Diego chair of nanoengineering professor Joseph Wang described it as like something taken from the 1966 film Fantastic Voyage, where medical personnel board a submarine were shrunk to microscopic size to travel through the bloodstream of a wounded diplomat and save his life.
Professor Wang said his team was getting closer to the goal of using nano submarines in a variety of ways, minus the shrunken humans and sabotage of the 1966 film.
“It’s like the Fantastic Voyage movie, where you want to improve therapeutic and diagnostic abilities through proper timing and proper location to improve efficiency,” he said.
“It is like shrinking a big submarine a million times to get the nano-scale submarine.
“We use special nano fabrications to create it.
“You can call it submarine or a nano machine, there are different names for it.”
One nanometer is one-billionth of a meter. To put this into perspective, a strand of human DNA is 2.5 nanometers in diameter while a sheet of paper is about 100,000 nanometers thick.
Professor Wang said the nano submarines could be tailored to specific applications, including diagnosis, treatment and imaging and would use energy within the body’s system to generate its movement.
“It is powered by the blood, by chemical in the blood like glucose, it can autonomously move in blood,” he said.
“This is all part of what we call nano medicine, precision medicine that we use to improve medicines.
“It could improve imaging, diagnosis, treatment, it is multifunctional.”
Professor Wang said there was a fair way to go before human testing could begin, but said the pioneering work could improve drug treatments by providing a more targeted approach.
“Compared to (current) drug delivery, it could take cargo, the drug, and dispose it at the right location, right time and could improve the efficiency of drug,” he said.
Professor Wang was presenting a free public seminar on nano submarines at University of Sunshine Coast’s Innovation Centre at Sippy Downs.
Whether severe trauma occurs on the battlefield or the highway, saving lives often comes down to stopping the bleeding as quickly as possible. Many methods for controlling external bleeding exist, but at this point, only surgery can halt blood loss inside the body from injury to internal organs.
Now, researchers have developed nanoparticles that congregate wherever injury occurs in the body to help it form blood clots, and they’ve validated these particles in test tubes and in vivo.
The researchers will present their work today at the 252nd National Meeting & Exposition of the American Chemical Society (ACS).
“When you have uncontrolled internal bleeding, that’s when these particles could really make a difference,” says Erin B. Lavik, Sc.D. “Compared to injuries that aren’t treated with the nanoparticles, we can cut bleeding time in half and reduce total blood loss.”
Trauma remains a top killer of children and younger adults, and doctors have few options for treating internal bleeding. To address this great need, Lavik’s team developed a nanoparticle that acts as a bridge, binding to activated platelets and helping them join together to form clots. To do this, the nanoparticle is decorated with a molecule that sticks to a glycoprotein found only on the activated platelets.
Initial studies suggested that the nanoparticles, delivered intravenously, helped keep rodents from bleeding out due to brain and spinal injury, Lavik says. But, she acknowledges, there was still one key question: “If you are a rodent, we can save your life, but will it be safe for humans?”
As a step toward assessing whether their approach would be safe in humans, they tested the immune response toward the particles in pig’s blood. If a treatment triggers an immune response, it would indicate that the body is mounting a defense against the nanoparticle and that side effects are likely. The team added their nanoparticles to pig’s blood and watched for an uptick in complement, a key indicator of immune activation. The particles triggered complement in this experiment, so the researchers set out to engineer around the problem.
“We made a battery of particles with different charges and tested to see which ones didn’t have this immune-response effect,” Lavik explains. “The best ones had a neutral charge.” But neutral nanoparticles had their own problems. Without repulsive charge-charge interactions, the nanoparticles have a propensity to aggregate even before being injected. To fix this issue, the researchers tweaked their nanoparticle storage solution, adding a slippery polymer to keep the nanoparticles from sticking to each other.
Lavik also developed nanoparticles that are stable at higher temperatures, up to 50 degrees Celsius (122 degrees Fahrenheit). This would allow the particles to be stored in a hot ambulance or on a sweltering battlefield.
In future studies, the researchers will test whether the new particles activate complement in human blood. Lavik also plans to identify additional critical safety studies they can perform to move the research forward. For example, the team needs to be sure that the nanoparticles do not cause non-specific clotting, which could lead to a stroke. Lavik is hopeful though that they could develop a useful clinical product in the next five to 10 years.
More information: Engineering nanoparticles to stop internal bleeding, 252nd National Meeting & Exposition of the American Chemical Society (ACS), 2016.
Young people between 5 and 44 are most likely to die from a trauma, and the primary cause of death will be bleeding out. We have a range of technologies to control external bleeding, but there is a dearth of technologies for internal bleeding.
Following injury, platelets become activated at the injury site.
We have designed nanoparticles that are administered intravenously that bind with activated platelets to help form platelet plugs more rapidly. We have investigated the behavior of these particles in an number of in vitro systems to understand their behavior. We have also tested these particles in a number of models of trauma. The particles lead to a reduction in bleeding in a number of models of trauma including models of brain and spinal cord injury, and these particles lead to increased survival.
This work is not without challenges. One of the goals is to be able to use these particles in places where there are extreme temperatures and storage is challenging. We have engineering a variant of the hemostatic nanoparticles that is stable up to 50 C. A second challenge is that the intravenous administration of nanoparticles triggers complement activation as has been seen in a wide range of nanoparticle technologies from DOXIL to imaging agents.
The solution is generally to administer the particles very slowly to modulate the physiological responses to complement activation, but that is not an option when one is bleeding out, so we have had to develop variants that reduce complement activation and the accompanying complications.
Ultimately, we hope that this work provides insight and, potentially, a new approach to dealing with internal bleeding.
“Artificial atoms open up new, exciting possibilities, because we can directly tune their properties”, says Professor Joachim Burgdörfer (TU Wien, Vienna).In semiconductor materials such as gallium arsenide, trapping electrons in tiny confinements has already been shown to be possible. These structures are often referred to as “quantum dots”. Just like in an atom, where the electrons can only circle the nucleus on certain orbits, electrons in these quantum dots are forced into discrete quantum states.”
In a tiny quantum prison, electrons behave quite differently as compared to their counterparts in free space. They can only occupy discrete energy levels, much like the electrons in an atom – for this reason, such electron prisons are often called “artificial atoms”.
Artificial atoms may also feature properties beyond those of conventional ones, with the potential for many applications for example in quantum computing. Such additional properties have now been shown for artificial atoms in the carbon material graphene.
The results have been published in the journal Nano Letters, the project was a collaboration of scientists from TU Wien (Vienna, Austria), RWTH Aachen (Germany) and the University of Manchester (GB).
Building Artificial Atoms
“Artificial atoms open up new, exciting possibilities, because we can directly tune their properties”, says Professor Joachim Burgdörfer (TU Wien, Vienna).
In semiconductor materials such as gallium arsenide, trapping electrons in tiny confinements has already been shown to be possible. These structures are often referred to as “quantum dots”. Just like in an atom, where the electrons can only circle the nucleus on certain orbits, electrons in these quantum dots are forced into discrete quantum states.
Even more interesting possibilities are opened up by using graphene, a material consisting of a single layer of carbon atoms, which has attracted a lot of attention in the last few years. “In most materials, electrons may occupy two different quantum states at a given energy. The high symmetry of the graphene lattice allows for four different quantum states. This opens up new pathways for quantum information processing and storage” explains Florian Libisch from TU Wien. However, creating well-controlled artificial atoms in graphene turned out to be extremely challenging.
Cutting edge is not enough
There are different ways of creating artificial atoms: The simplest one is putting electrons into tiny flakes, cut out of a thin layer of the material. While this works for graphene, the symmetry of the material is broken by the edges of the flake which can never be perfectly smooth. Consequently, the special four-fold multiplicity of states in graphene is reduced to the conventional two-fold one.
Therefore, different ways had to be found: It is not necessary to use small graphene flakes to capture electrons. Using clever combinations of electrical and magnetic fields is a much better option. With the tip of a scanning tunnelling microscope, an electric field can be applied locally. That way, a tiny region is created within the graphene surface, in which low energy electrons can be trapped. At the same time, the electrons are forced into tiny circular orbits by applying a magnetic field. “If we would only use an electric field, quantum effects allow the electrons to quickly leave the trap” explains Libisch.
The artificial atoms were measured at the RWTH Aachen by Nils Freitag and Peter Nemes-Incze in the group of Professor Markus Morgenstern. Simulations and theoretical models were developed at TU Wien (Vienna) by Larisa Chizhova, Florian Libisch and Joachim Burgdörfer. The exceptionally clean graphene sample came from the team around Andre Geim and Kostya Novoselov from Manchester (GB) – these two researchers were awarded the Nobel Prize in 2010 for creating graphene sheets for the first time.
The new artificial atoms now open up new possibilities for many quantum technological experiments: “Four localized electron states with the same energy allow for switching between different quantum states to store information”, says Joachim Burgdörfer.
The electrons can preserve arbitrary superpositions for a long time, ideal properties for quantum computers. In addition, the new method has the big advantage of scalability: it should be possible to fit many such artificial atoms on a small chip in order to use them for quantum information applications.
The US Department of Energy will invest $16 million over the next four years to accelerate the design of new materials through use of supercomputers.
Two four-year projects—one team led by DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab), the other teamled by DOE’s Oak Ridge National Laboratory (ORNL)—will leverage the labs’ expertise in materials and take advantage of lab supercomputers to develop software for designing fundamentally new functional materials destined to revolutionize applications in alternative and renewable energy, electronics, and a wide range of other fields. The research teams include experts from universities and other national labs.
The new grants—part of DOE’s Computational Materials Sciences (CMS) program launched in 2015 as part of the US Materials Genome Initiative—reflect the enormous recent growth in computing power and the increasing capability of high-performance computers to model and simulate the behavior of matter at the atomic and molecular scales.
The teams are expected to develop sophisticated and user-friendly open-source software that captures the essential physics of relevant systems and can be used by the broader research community and by industry to accelerate the design of new functional materials.
The Berkeley Lab team will be led by Steven G. Louie, an internationally recognized expert in materials science and condensed matter physics. A longtime user of NERSC supercomputers, Louie has a dual appointment as Senior Faculty Scientist in the Materials Sciences Division at Berkeley Lab and Professor of Physics at the University of California, Berkeley. Other team members are Jack Deslippe, Jeffrey B. Neaton, Eran Rabani, Feng Wang, Lin-Wang Wang and Chao Yang, Lawrence Berkeley National Laboratory; and partners Daniel Neuhauser, University of California at Los Angeles, and James R. Chelikowsky, University of Texas, Austin.
This investment in the study of excited-state phenomena in energy materials will, in addition to pushing the frontiers of science, have wide-ranging applications in areas such as electronics, photovoltaics, light-emitting diodes, information storage and energy storage. We expect this work to spur major advances in how we produce cleaner energy, how we store it for use, and to improve the efficiency of devices that use energy.
ORNL researchers will partner with scientists from national labs and universities to develop software to accurately predict the properties of quantum materials with novel magnetism, optical properties and exotic quantum phases that make them well-suited to energy applications, said Paul Kent of ORNL, director of the Center for Predictive Simulation of Functional Materials, which includes partners from Argonne, Lawrence Livermore, Oak Ridge and Sandia National Laboratories and North Carolina State University and the University of California–Berkeley.
Our simulations will rely on current petascale and future exascale capabilities at DOE supercomputing centers. To validate the predictions about material behavior, we’ll conduct experiments and use the facilities of the Advanced Photon Source, Spallation Neutron Source and the Nanoscale Science Research Centers.
At Argonne, our expertise in combining state-of-the-art, oxide molecular beam epitaxy growth of new materials with characterization at the Advanced Photon Source and the Center for Nanoscale Materials will enable us to offer new and precise insight into the complex properties important to materials design. We are excited to bring our particular capabilities in materials, as well as expertise in software, to the center so that the labs can comprehensively tackle this challenge.
—Olle Heinonen, Argonne materials scientist
Researchers are expected to make use of the 30-petaflop/s Cori supercomputer now being installed at the National Energy Research Scientific Computing center (NERSC) at Berkeley Lab, the 27-petaflop/s Titan computer at the Oak Ridge Leadership Computing Facility (OLCF) and the 10-petaflop/s Mira computer at Argonne Leadership Computing Facility (ALCF). OLCF, ALCF, and NERSC are all DOE Office of Science User Facilities. One petaflop/s is 1015 or a million times a billion floating-point operations per second.
In addition, a new generation of machines is scheduled for deployment between 2016 and 2019 that will take peak performance as high as 200 petaflops. Ultimately the software produced by these projects is expected to evolve to run on exascale machines, capable of 1000 petaflops and projected for deployment in the mid-2020s.
Research will combine theory and software development with experimental validation, drawing on the resources of multiple DOE Office of Science User Facilities, including the Molecular Foundry and Advanced Light Source at Berkeley Lab, the Center for Nanoscale Materials and the Advanced Photon Source at Argonne National Laboratory (ANL), and the Center for Nanophase Materials Sciences and the Spallation Neutron Source at ORNL, as well as the other Nanoscience Research Centers across the DOE national laboratory complex.
The new research projects will begin in Fiscal Year 2016. Subsequent annual funding will be contingent on available appropriations and project performance.
The two new projects expand the ongoing CMS research effort, which began in FY 2015 with three initial projects, led respectively by ANL, Brookhaven National Laboratory and the University of Southern California.
Membrane structures in plant xylem from different species are being investigated for use in water filtration. Image: Karnik Lab
Four new projects and one renewal receive $150,000 in funding for 2016-2017.
The Abdul Latif Jameel World Water and Food Security Lab (J-WAFS) has announced four new grant recipients in its J-WAFS Solutions program. J-WAFS Solutions is sponsored by Abdul Latif Jameel Community Initiatives, and provides commercialization grants to help develop products and services that will have a significant impact on water and food security, with related economic and societal benefits.
The program, managed by the MIT Deshpande Center for Technological Innovation, is in its second year. Like direct Deshpande grants, the goal of the funding is to advance a technology to the point where it can attract customer interest and investments to commercialize a product and launch a spinout company, and/or to license the technology to an existing organization. Funds support work to refine and enhance an innovation, systematically explore potential markets, and assess commercial viability, whereby the technology and market risks are sufficiently reduced.
The four new grants go to faculty in the departments of Chemical Engineering, Chemistry, and Mechanical Engineering. John H. Lienhard V, director of J-WAFS and the Abdul Latif Jameel World Water and Food Security Professor, says that MIT faculty continue to devise innovative technologies that are applicable to a range of challenges in the food and water sectors:
“Commercializing effective technologies with sound business models is one of MIT’s most effective mechanisms to have a positive impact on the world,” he says. “The J-WAFS Solutions program is helping not only to stimulate creative problem solving, but also to support entrepreneurial faculty and students who are motivated by problems of global importance.”
Following on prior J-WAFS seed funding, Alan Hatton, the Ralph Landau Professor of Chemical Engineering Practice, has been awarded a commercialization grant for the development of an affordable and robust purification technology. Seeing a need for separation technologies that can be applied to water purification needs in a range of contexts — from point-of-source treatment to remote in-situ purification devices to large-scale, centralized wastewater treatment facilities — the lab has been developing electrochemically-mediated adsorptive processes for water treatment. J‑WAFS Solutions funding will support the development of a demonstration unit and exploration of commercial application opportunities.
A new project led by Rohit Karnik, associate professor in the Department of Mechanical Engineering, and co-PI Amy Smith, senior lecturer in the Department of Mechanical Engineering and co-director of D-Lab, takes avery different approach to water purification. Addressing the largely unmet need to provide safe and affordable drinking water to very low-income groups, Karnik is developing low-cost water filters that exploit the natural filtration capabilities of xylem tissue in wood. Particularly in regions lacking access to piped water supply systems, microbial contamination is a major threat to health. With J-WAFS Solutions funding, Karnik’s lab will work with Amy Smith to validate filtration performance in the lab and in the field, while also assessing the usability, desirability, and affordability of low-cost filters and devising a strategy for local manufacture and commercialization.
Gang Chen, the Carl Richard Soderberg Professor in Power Engineering and head of the Department of Mechanical Engineering, was funded for his proposal on “Floating, Heat Localizing Solar Receivers for Distributed Desalination.” The lab’s invention is a wavelength-selective, insulating, solar powered still (WISPS) tarp structure that can blanket ocean, lake, and pond surfaces to generate freshwater onsite. The project addresses the challenges associated with scalability, cost, and water safety associated with seawater desalination by capitalizing on a recent innovation by Chen that achieves high evaporation rates and high efficiency by localizing high temperatures to the water surface.
The fourth funded project addresses the need for simple and rapid detection of pathogenic bacteria in food and water samples in order to prevent widespread infection, illness, and even death. Using a carbohydrate array detection scheme based on specific binding interactions of bacteria with carbohydrates, Timothy Swager, the John D. MacArthur Professor of Chemistry, and Alexander M. Klibanov, Novartis Professor in Chemistry and Bioengineering, are developing a system that will be able to simultaneously detect multiple types of pathogenic bacterial strains. The project will focus initially on the occurrence of food poisoning from ground beef — a common problem because of the prevalence of E. coli contamination in beef and dairy cattle and because bacteria that may only be on the surface and readily killed by cooking become dispersed throughout the meat during the grinding process.
A one-year renewal grant was awarded for another project that is pursuing point-of use identification of contaminants in drinking water and food through a different technology. Jointly led by Professor Michael S. Strano of the Department of Chemical Engineering and Professor Anthony Sinskey of the Department of Biology, this interdisciplinary project is leveraging new MIT nanotechnology to develop a single integrated platform that can address all important food and water contaminants — including bacterial pathogens, heavy metals, and allergens — in a low cost, widely deployable nanosensor array.
Renee J. Robins, executive director of J-WAFS, noted that the new projects span various aspects of ensuring a safe supply of water and food:
“Whether the issue is clean water for a rural village in India or enjoying a juicy hamburger cooked on the grill without fear of food poisoning, MIT researchers are developing technologies that will greatly improve people’s ability to have clean water and safe food at their ready disposal,” she says.
The tip of an atomic force microscope on a cantilevered arm is used to pull a graphene nanoribbon the same way it would be used to pull apart a protein or a strand of DNA in a Rice University lab. The microscope can be used to measure properties like rigidity in a material as it’s manipulated by the tip. Credit: Kiang Research Group/Rice University
Graphene nanoribbons (GNRs) bend and twist easily in solution, making them adaptable for biological uses like DNA analysis, drug delivery and biomimetic applications, according to scientists at Rice University.
Knowing the details of how GNRs behave in a solution will help make them suitable for wide use in biomimetics, according to Rice physicist Ching-Hwa Kiang, whose lab employed its unique capabilities to probe nanoscale materials like cells and proteins in wet environments. Biomimetic materials are those that imitate the forms and properties of natural materials.
The research led by recent Rice graduate Sithara Wijeratne, now a postdoctoral researcher at Harvard University, appears in the Nature journal Scientific Reports.
Graphene nanoribbons can be thousands of times longer than they are wide. They can be produced in bulk by chemically “unzipping” carbon nanotubes, a process invented by Rice chemist and co-author James Tour and his lab.
Their size means they can operate on the scale of biological components like proteins and DNA, Kiang said. “We study the mechanical properties of all different kinds of materials, from proteins to cells, but a little different from the way other people do,” she said. “We like to see how materials behave in solution, because that’s where biological things are.” Kiang is a pioneer in developing methods to probe the energy states of proteins as they fold and unfold.
She said Tour suggested her lab have a look at the mechanical properties of GNRs. “It’s a little extra work to study these things in solution rather than dry, but that’s our specialty,” she said.
Nanoribbons are known for adding strength but not weight to solid-state composites, like bicycle frames and tennis rackets, and forming an electrically active matrix. A recent Rice project infused them into an efficient de-icer coating for aircraft.
But in a squishier environment, their ability to conform to surfaces, carry current and strengthen composites could also be valuable.
“It turns out that graphene behaves reasonably well, somewhat similar to other biological materials. But the interesting part is that it behaves differently in a solution than it does in air,” she said. The researchers found that like DNA and proteins, nanoribbons in solution naturally form folds and loops, but can also form helicoids, wrinkles and spirals.
Kiang, Wijeratne and Jingqiang Li, a co-author and student in the Kiang lab, used atomic force microscopy to test their properties. Atomic force microscopy can not only gather high-resolution images but also take sensitive force measurements of nanomaterials by pulling on them. The researchers probed GNRs and their precursors, graphene oxide nanoribbons.
The researchers discovered that all nanoribbons become rigid under stress, but their rigidity increases as oxide molecules are removed to turn graphene oxide nanoribbons into GNRs. They suggested this ability to tune their rigidity should help with the design and fabrication of GNR-biomimetic interfaces.
“Graphene and graphene oxide materials can be functionalized (or modified) to integrate with various biological systems, such as DNA, protein and even cells,” Kiang said. “These have been realized in biological devices, biomolecule detection and molecular medicine. The sensitivity of graphene bio-devices can be improved by using narrow graphene materials like nanoribbons.”
Wijeratne noted graphene nanoribbons are already being tested for use in DNA sequencing, in which strands of DNA are pulled through a nanopore in an electrified material. The base components of DNA affect the electric field, which can be read to identify the bases.
The researchers saw nanoribbons’ biocompatibility as potentially useful for sensors that could travel through the body and report on what they find, not unlike the Tour lab’s nanoreporters that retrieve information from oil wells.
Further studies will focus on the effect of the nanoribbons’ width, which range from 10 to 100 nanometers, on their properties.
Researchers from Polytechnique Montréal, Université de Montréal and McGill University have just achieved a spectacular breakthrough in cancer research. They have developed new nanorobotic agents capable of navigating through the bloodstream to administer a drug with precision by specifically targeting the active cancerous cells of tumours. This way of injecting medication ensures the optimal targeting of a tumour and avoids jeopardizing the integrity of organs and surrounding healthy tissues. As a result, the drug dosage that is highly toxic for the human organism could be significantly reduced.
This scientific breakthrough has just been published in the prestigious journal Nature Nanotechnology in an article titled “Magneto-aerotactic bacteria deliver drug-containing nanoliposomes to tumour hypoxic regions.” The article notes the results of the research done on mice, which were successfully administered nanorobotic agents into colorectal tumours.
“These legions of nanorobotic agents were actually composed of more than 100 million flagellated bacteria – and therefore self-propelled – and loaded with drugs that moved by taking the most direct path between the drug’s injection point and the area of the body to cure,” explains Professor Sylvain Martel, holder of the Canada Research Chair in Medical Nanorobotics and Director of the Polytechnique Montréal Nanorobotics Laboratory, who heads the research team’s work. “The drug’s propelling force was enough to travel efficiently and enter deep inside the tumours.”
When they enter a tumour, the nanorobotic agents can detect in a wholly autonomous fashion the oxygen-depleted tumour areas, known as hypoxic zones, and deliver the drug to them. This hypoxic zone is created by the substantial consumption of oxygen by rapidly proliferative tumour cells. Hypoxic zones are known to be resistant to most therapies, including radiotherapy.
But gaining access to tumours by taking paths as minute as a red blood cell and crossing complex physiological micro-environments does not come without challenges. So Professor Martel and his team used nanotechnology to do it.
Bacteria with compass
To move around, bacteria used by Professor Martel’s team rely on two natural systems. A kind of compass created by the synthesis of a chain of magnetic nanoparticles allows them to move in the direction of a magnetic field, while a sensor measuring oxygen concentration enables them to reach and remain in the tumour’s active regions. By harnessing these two transportation systems and by exposing the bacteria to a computer-controlled magnetic field, researchers showed that these bacteria could perfectly replicate artificial nanorobots of the future designed for this kind of task.
“This innovative use of nanotransporters will have an impact not only on creating more advanced engineering concepts and original intervention methods, but it also throws the door wide open to the synthesis of new vehicles for therapeutic, imaging and diagnostic agents,” Professor Martel adds. “Chemotherapy, which is so toxic for the entire human body, could make use of these natural nanorobots to move drugs directly to the targeted area, eliminating the harmful side effects while also boosting its therapeutic effectiveness.”
Imagine an electronic newspaper that you could roll up and spill your coffee on, even as it updated itself before your eyes.
It’s an example of the technological revolution that has been waiting to happen, except for one major problem that, until now, scientists have not been able to resolve.
Researchers at McMaster University have cleared that obstacle by developing a new way to purify carbon nanotubes – the smaller, nimbler semiconductors that are expected to replace silicon within computer chips and a wide array of electronics.
“Once we have a reliable source of pure nanotubes that are not very expensive, a lot can happen very quickly,” says Alex Adronov, a professor of Chemistry at McMaster whose research team has developed a new and potentially cost-efficient way to purify carbon nanotubes.
Carbon nanotubes – hair-like structures that are one billionth of a metre in diameter but thousands of times longer – are tiny, flexible conductive nano-scale materials, expected to revolutionize computers and electronics by replacing much larger silicon-based chips.
A major problem standing in the way of the new technology, however, has been untangling metallic and semiconducting carbon nanotubes, since both are created simultaneously in the process of producing the microscopic structures, which typically involves heating carbon-based gases to a point where mixed clusters of nanotubes form spontaneously as black soot.
Only pure semiconducting or metallic carbon nanotubes are effective in device applications, but efficiently isolating them has proven to be a challenging problem to overcome. Even when the nanotube soot is ground down, semiconducting and metallic nanotubes are knotted together within each grain of powder. Both components are valuable, but only when separated.
Researchers around the world have spent years trying to find effective and efficient ways to isolate carbon nanotubes and unleash their value.
While previous researchers had created polymers that could allow semiconducting carbon nanotubes to be dissolved and washed away, leaving metallic nanotubes behind, there was no such process for doing the opposite: dispersing the metallic nanotubes and leaving behind the semiconducting structures.
Now, Adronov’s research group has managed to reverse the electronic characteristics of a polymer known to disperse semiconducting nanotubes – while leaving the rest of the polymer’s structure intact. By so doing, they have reversed the process, leaving the semiconducting nanotubes behind while making it possible to disperse the metallic nanotubes.
The researchers worked closely with experts and equipment from McMaster’s Faculty of Engineering and the Canada Centre for Electron Microscopy, located on the university’s campus.
“There aren’t many places in the world where you can to this type of interdisciplinary work,” Adronov says.
The next step, he explains, is for his team or other researchers to exploit the discovery by finding a way to develop even more efficient polymers and scale up the process for commercial production.
The research is described in the cover story of Chemistry – A European Journal.
A new study says that today’s electric vehicles can handle almost 90 percent of all car travel in the U.S.
Special to MIT TECHNOLOGY REVIEW by C. Caruso
Electric vehicles promise to free us from our dependence on gasoline, but there’s a catch: most models can’t travel as far as their internal-combustion counterparts without recharging. As a result, whenever widespread adoption of electrics comes up, the conversation almost always turns to “range anxiety.”
New research suggests the concern is overblown. By analyzing people’s driving habits across the country, Jessika Trancik at MIT and colleagues found that currently available electric cars could replace 87 percent of the personal vehicles on the road and still get us where we need to go (and back again). Assuming battery technology improves in line with government estimates, by 2020 up to 98 percent of vehicles could be replaced.
You don’t have to pony up for a Tesla, either. In their analysis, the team used performance metrics for the Nissan Leaf, which starts around $29,000. According to the researchers, the Leaf’s range averages 74 miles per charge, which includes a buffer of 10 percent of charge left in the battery, though that depends on things like whether you often drive in heavy traffic and how hard you tend to lean on the accelerator.
The researchers’ model used self-reported data on how Americans travel, taken from the 2009 National Household Travel Survey. They paired that with GPS data from car trips around the country, as well as fuel economy data, and air temperature readings. The model assumed that people only recharged their cars overnight.
Replacing 87 percent of vehicles with Nissan Leafs would, predictably, have a huge impact on fuel consumption. The researchers say it would slash our national gas-guzzling habit by 61 percent and have a dramatic impact on carbon emissions. If batteries improve in line with expectations laid out by the U.S. Department of Energy’s ARPA-E agency, those numbers would increase to 98 percent replacement, which would account for 88 percent of our gasoline consumption.
Perhaps most interesting is the high potential for replacement across a wide variation in climate, urban planning, and population. Sprawling Houston, for example, has the potential for 88 percent replacement, compared with 87 percent in New York City. Even in rural settings, the model indicates that 81 percent of vehicles could be replaced.
The researchers are currently working on getting the model into the hands of consumers to help them make more informed decisions about whether an electric car can meet their needs, either overall or on a particular day of driving.
“It’s taking the approach of empowering people with information, which often today they don’t have,” Trancik says. “These changes can happen from the ground. And I think the area of personal transportation is just so exciting for that reason, because private citizens can really make a difference today.”
Getting electric cars widely adopted still presents challenges. The biggest is dealing with the remaining 13 percent of cars making trips that are too long for today’s electric vehicles. People need to have a convenient alternative on their “high-energy days,” Trancik says, or they will never purchase an electric vehicle. Sharing of gas-powered vehicles is one potential solution, and down the road, quick-charging stations or battery swapping may become more realistic options.
Installing overnight charging stations at home can also be logistically difficult. Robert Green, a computer scientist at Bowling Green State University who studies electric cars and power system reliability, points out that we must consider how the charging demands of more electric cars will affect the power grid. He considers the newer, more complex data set used by the model to be the study’s biggest contribution. “Better data gives you a more accurate picture of what life with electric vehicles looks like,” he says.
“Every time I see a paper like this, the major takeaway is Hey, you don’t actually have to be scared about these—the math works out,” he says. “But there is that issue when you are driving long-haul or vacation or whatever it happens to be.”