Tesla Semi and Roadster could be relying on a “battery breakthrough”


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Elon Musk and Tesla have made some bold claims for the new Tesla Semi and Roadster. Those who understand batteries have been scratching their heads trying to figure out how the company can deliver the specs it’s promising – and concluding that the only possible way is some as-yet-unannounced advancement in battery technology.

Musk says the Tesla Semi will be able to haul 80,000 pounds for 500 miles, and recharge to 400 miles in 30 minutes, which would revolutionize the trucking industry. As for the Roadster, its promised 0-60 acceleration of 1.9 seconds effectively shuts down every one of the world’s baddest supercars, and its touted 620-mile range would be double that of any EV produced to date.

However, industry experts are questioning Tesla CEO Elon Musk’s touted range and charging capabilities, saying the specifications defy current physics and battery economics.

According to Bloomberg, analysts at Bloomberg New Energy Finance point out that Tesla Semi’s announced specs would require a battery capacity of between 600 and 1,000 kilowatt hours (6-10 times the size of the largest Model S battery).

Using current technology, an 800 kWh battery pack would weigh over 10,000 pounds and cost more than $100,000. That’s just for the battery – Tesla has said its entire truck will start at $150,000. It seems plain that Tesla is counting on falling battery prices to square the circle. “The first Tesla Semis won’t hit the road until late 2019,” Bloomberg points out.

“Even then, production would probably start slowly. Most fleet operators will want to test the trucks before considering going all-in. By the time Tesla gets large orders, batteries should cost considerably less.”

It isn’t just the capacity of the battery that’s causing analysts to wear out their calculators – Musk’s claim that the Tesla Semi will be able to add 400 miles of charge in 30 minutes would require a charging system 10 times more powerful than Tesla’s current Supercharger – which is already by far the most powerful in the industry.

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Tesla Semi Megacharger port could support 1 MW of power.

“I don’t understand how that works,” said Bloomberg New Energy Finance EV Analyst Salim Morsy. “I really don’t.” Tesla’s current generation of Superchargers have a power output of 120 kilowatts and can add about 180 miles of range to a Model S battery in 30 minutes. To meet Tesla’s charging claim for the Semi would require the promised Megacharger to deliver an output of at least 1,200 kW.

Perhaps Tesla’s biggest bombshell is the promise that it will guarantee truckers electricity rates of 7 cents per kilowatt hour, which Bloomberg estimates could translate to fuel savings of up to $30,000 a year.

Musk says that adding solar panels and battery packs at the charging stations will account for at least part of the cost reduction. However, BNEF’s Salim Morsy insists that Tesla will have to heavily subsidize those electricity rates – he estimates that Tesla will pay a minimum of 40 cents per kWh. “There’s no way you can reconcile 7 cents a kilowatt hour with anything on the grid that puts a megawatt hour of energy into a battery,” Morsy said. “That simply does not exist.”

Of course, that’s no different from what Tesla does for its current Supercharger network, offering free electricity to many customers, while paying almost $1 per kWh to produce it, according to Morsy’s estimate.

And how about that Roadster? To deliver its promised range of 620 miles, it will need a 200 kWh battery pack, twice the size of Tesla’s largest currently available pack. Mr. Morsy predicts that Tesla will stack two battery packs, one on top of the other, beneath the Roadster’s floor.

Roadster

 

 

Even with a double-decker pack however, it’s hard to escape the conclusion that Tesla is counting on improving battery tech to make the Roadster, like the Semi, feasible. Battery density has been improving at a rate of about 7.5 percent a year, and that’s without any major breakthrough in battery chemistry.

“The trend in battery density is, I think, central to any claim Tesla made about both the Roadster and the Semi,” Morsy said. “That’s totally fair. The assumptions on a pack in 2020 shouldn’t be the same ones you use today.”

A massive battery pack not only enables greater range – it’s also a key element in the Roadster’s world-beating 0-60 acceleration. Jalopnik’s David Tracy spoke with battery expert Venkat Viswanathan, a Mechanical Engineering Assistant Professor at Carnegie Mellon, who says that the 1.9-second figure actually seems reasonable.

Viswanathan explains that the power output of a motor is limited by the power draw from each battery cell. Because the Roadster’s pack is double the size, the power draw may not be that much more than that of a Ludicrous Model S.

Viswanathan told Jalopnik that the most modern battery cells offer specific energy of about 240 watt-hours per kilogram. Using that assumption, the Roadster’s 200 kWh battery pack should weigh roughly 1,800 pounds, a huge advance over the previous-generation Roadster. With clever use of lightweight materials, the Roadster could still come out under the nearly two-ton curb weight of the Nissan GT-R, an acceleration benchmark among sports cars.

Viswanathan concludes that a 0-60 time of 1.9 seconds and a range of 620 miles are quite feasible, although there are several other factors that will come into play – much depends on the vehicle’s tires and aerodynamics.

Meanwhile, at least one analyst thinks Tesla’s latest revelations (or claims, or fantasies, depending on your point of view) have implications that go far beyond the Semi and the Roadster. Michael Kramer, a Fund Manager with Mott Capital Management, told Marketwatch that he suspects improved battery capacities and charging times could make their way into all future Tesla vehicles.

“I’d have to imagine that Tesla has figured out how to put this technology on all of their cars, which means every car could get a full charge in under 30 minutes,” Kramer wrote. Once the Model S “is equipped with the 200 kWh battery pack in the new Roadster, which I can’t imagine is too far down the road, the range issue for the Tesla is officially dead.” (Elon Musk has said that Models S and X will not get physically larger packs, but improved energy density could increase capacity while keeping the size of the pack the same.) Someday soon, Kramer says, “The Model S would likely be able to drive further on one charge than a car on a full tank of gasoline.”

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Note: Article originally published on evannex.com, by Charles Morris

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US Patent Granted to Grolltex for Advanced Graphene ‘Super’ Sensor


December 8, 2017

San Diego based Grolltex was granted a patent by the USPTO for a new multi-modal ‘super’ sensor design made of single layer graphene.

The patent, titled “Graphene-based multi-modal sensor” describes a one atom thick architecture and utilizes several of Grolltex’ 2D materials technologies to produce what the company internally calls ‘The smallest, most sensitive sensor in the world’.

The company is working on initial applications for these sensors that are targeting the bio-sensing and defense fields as leading-edge users of this technology.

“Our single atom thick sensor design, in the strain sensor configuration, is so sensitive that it captures a robust and repeatable signal on the contractility strength of individual ‘cardio myocytes’ or heart cells as they beat”, said Jeff Draa, company co-founder and CEO.

“This can be a holy grail for fields such as cardiotoxicity testing as it has the capacity to be a significant time and money saver in the new drug testing and approval process”.

Additionally, the single layer graphene sensor covered by this patent has a very high threshold for thermal coefficient of resistance, meaning it experiences little to no signal drift when exposed to extreme levels of heat. This makes it an ideal sensor for measuring micro strain in high speed aeronautical vehicles.

These sensors are so small and thin, they can be layered into the skins of airplanes, helicopters or other high stress vehicles to real-time measure and detect micro stress at architectures and levels not currently possible with today’s sensing technologies. These sensors could also be discreetly placed within critical structures such as bridges or buildings.

The full story is available below.

Source: The Daily Telescope

‘Smart’ Orthodontic Technology from KAUST – Flexible microbattery enables smart dental braces


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Flexible, non-cytotoxic battery concept. Optical images of an intra-oral implantable device that relies on millimeter-sized flexible, biocompatible lithium-ion battery as a rapid powering solution. (© Nature Publishing Group)

Researchers have demonstrated a novel approach toward smart orthodontics based on near-infrared red light from a mechanically flexible LED powered by flexible bio-safe batteries all integrated in a single 3D-printed dental brace.

As the team from King Abdullah University of Science and Technology (KAUST) demonstrates in their paper in NPJ Flexible Electronics (“Flexible and biocompatible high-performance solid-state micro-battery for implantable orthodontic system”), integration of red light therapy enhances bone regeneration, reducing overall time to wear the dental brace and unburdening users from expense. Furthermore, 3D printing allows personalized (instead of one size fits all) transparent dental brace.
“Integration of electronic devices in 3D printed dental aligners, as we have demonstrated here, is a pragmatic approach towards implementing a flexible electronic technology in personalized advanced healthcare, particularly in orthodontics,” Muhammad Mustafa Hussain, an Associate Professor of Electrical Engineering at KAUST, tells Nanowerk. ” The next stage of our work will be to demonstrate diagnostics in the smart dental brace in which sensors are able to detect the pressure exerted by aligners on teeth. This might help orthodontists estimate the force required by aligners; thus providing both diagnostic and treatment capabilities in dental braces. “
Flexible, non-cytotoxic battery concept
The scientific core of the team’s findings is to approach flexible energy storage solutions in a way that is pragmatic, fast and well integrated with other components. A major challenge to integrate any traditional lithium-based energy storage is their toxicity. The scientists circumvented this issue by introducing non-toxic micro-scale flexible batteries to be used as on-demand power supply.
Furthermore, they integrated near-infrared (NIR) capability as well as an optoelectronic system of light emitting diodes (LED) arrays in a personalized, 3D-printed semi-transparent dental brace. Of course, such a device would not have been possible without an appropriate energy storage solution.
Key to this smart brace is the use of a high-performance flexible solid-state microbattery. A standalone all thin-film lithium-ion battery already can be readily thinned down to about 30 microns thickness to achieve flexibility. The team’s flexing process for thin-film-based micro-batteries achieves two major objectives: 1) utilization of mature and reliable CMOS process with 90% yield and repeated electrochemical measurements on multiple devices, and 2) the ability to withstand high annealing temperatures of cathode material or soldering that are unachievable using direct film deposition on plastic substrates.
“Our flexile biocompatible lithium-ion battery can be transferred on polyethylene terephthalate (PET) and interconnected via aluminum engraved interconnections to create a battery module,” explains Hussain. “During testing we found that the battery module exhibits minimal strain while most of the stress is experienced by the PET film.”
Continuous intra-oral NIR light therapy for patients is becoming a growing necessity for accelerating the rate of the bone remodeling process. Near-infrared light can be absorbed by bone cells to stimulate the bone regeneration for faster orthodontic treatment.
That’s why the team integrated near-infrared LEDs with the flexible batteries and interconnected them on a soft PET substrate. The whole device is embedded in semi-transparent 3D-printed brace.
To summarize, this smart dental brace relies on two main functionalities: Firstly, a customizable, personalized, and semitransparent brace, which provides required external loading to stimulate healthy rebuilding of bone structures. Secondly, a miniaturized, soft, biocompatible optoelectronic system for an intraoral (conformable on the mouth) near-infrared light therapy, which allows rapid, temporally specific control of osteogenic cell activity via targeted exposure and light sensitive proteins present in bone cells.
“The combination of both strategies in one single platform provides affordable, multifunctionality dental braces,” concludes Hussain. “Such capability enhances the bone regeneration significantly and reduces the overall cost and discomfort. Our future work will include integration of compliant soft-substrate-based LEDs and miniaturized ICs with enhanced wireless capability for smart gadget-based remote control for cleaning and therapy.”

 

@ Michael Berger © Nanowerk

Promising New Research for High Performance Lithium Batteries – Engineering 2D Nanofluidic Channels


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Abstract: In article number 1703909, Gang Chen, Guihua Yu, and co-workers present a novel concept of 2D nanofluidic lithium-ion transport channels based on stacked Co3O4nanosheets for high-performance lithium batteries. This unique nanoarchitecture exhibits exceptional capacity and outstanding long-term cycling stability for lithium-ion storage at high-rates in both half- and full-cells.

 

Despite being a promising electrode material, bulk cobalt oxide (Co3O4) exhibits poor lithium ion storage properties. Nanostructuring, e.g. making Co3O4 into ultrathin nanosheets, shows improved performance, however, Co3O4-based nanomaterials still lack long-term stability and high rate capability due to sluggish ion transport and structure degradation.

Nanofluidic channels possess desired properties to address above issues. However, while these unique structures have been studied in hollow nanotubes and recently in restacked layered materials such as graphene, it remains challenging to construct nanofluidic channels in intrinsically non-layered materials.
Motived by the large number of non-layered materials, e.g. transition metal oxides, which hold great promise in battery applications, scientists aim to extend the concept of nanofluidic channels into these materials and improve their electrochemical properties.
Nanofluidic channels feature a unique unipolar ionic transport when properly designed and constructed. By controlling surface charge and channel spacing, enhanced and selective ion transport can be achieved in these channels by constructing them with dimensions comparable to the double Debye length and opposite surface charge with respect to the transporting ion.
In a new study published in Advanced Materials (“Engineering 2D Nanofluidic Li-Ion Transport Channels for Superior Electrochemical Energy Storage”), researchers have developed a Co3O4-based two-dimensional (2D) nano-architecture possessing nanofluidic channels with specially designed interlayer characteristics for fast lithium ion transport, leading to exceptional performance in lithium ion batteries ever reported for this material.
“Such constructed 2D nanofluidic channels in non-layered materials manifest a general structural engineering strategy for improving electrochemical properties in a vast number of different electrode materials,” Guihua Yu, a professor in Materials Science and Engineering, Mechanical Engineering, at the Texas Materials Institute, University of Texas at Austin. “The enhanced and selective ion transport demonstrated in our study is of broad interest to many applications where fast kinetics of ion transport is essential.”
Illustration of lithium ion transport in the 2D nanofluidic channels
Illustration of lithium ion transport in 2D nanofluidic channels. (Reprinted with permission by Wiley-VCH)
On the one hand, an intercalated molecule acts as interlayer pillar in the stacked oxide, constituting transport channels with proper spacing. On the other hand, negatively charged functional groups anchored on the nanosheets surface facilitate transport of positively charged lithium ions inside the channels.
“Satisfying aforementioned conditions for unipolar ionic transport, combined with other advantageous features – extra storage capacity contributed by the surface functional groups, buffered structural stress from the interlayer spacing, and shortened lithium ion diffusion distance due to the ultrathin nanosheet morphology – the resulting nanoarchitecture exhibit exceptional electrochemical performance as tested in lithium-ion batteries,” notes Yu.
In a next step, the researchers are going to extend the concept of 2D nanofluidic channels to other electrode materials with or without layering structures. With ability to further tune interlayer spacing, they expect some promising energy storage applications in beyond-lithium-ion batteries.
It might also be interesting to examine this structural engineering strategy in other applications, for example, catalysis.
Design and LIBs application of Co3O4 nanosheets with 2D nanofluidic channels
Design and LIBs application of Co3O4 nanosheets with 2D nanofluidic channels. (a) The synthetic route from Co-based layered hydroxide precursor to Co3O4 nanosheets with 2D nanofluidic channels. (b) Cycling performance of a full cell (anode: Co3O4 nanosheets /cathode: commercial LiCoO2). (Reprinted with permission by Wiley-VCH)
Constructing 2D nanofluidic channels for energy storage application is still in its infancy and the success of using non-layered materials demonstrated in this study promises a bright future in this direction with a broader material coverage.
“We are also taking this research direction even further by looking into the transport and storage properties for energy storage systems based on larger charge-carrying ions, such as Na+ and Mg2+, ” concludes Yu. “In order to realize that, an important challenge is to tune the channel spacing in a controlled manner. It is also imperative to investigate structural stability and scalability of this specially designed nanoarchitecture for its utilization in practical applications.”
@Michael Berger © Nanowerk

MIT: Device makes power conversion more efficient New design could dramatically cut energy waste in electric vehicles, data centers, and the power grid


MIT-Power-Converters-01_0MIT postdoc Yuhao Zhang, handles a wafer with hundreds of vertical gallium nitride power devices fabricated from the Microsystems Technology Laboratories production line. Courtesy of Yuhao Zhang

 

Power electronics, which do things like modify voltages or convert between direct and alternating current, are everywhere. They’re in the power bricks we use to charge our portable devices; they’re in the battery packs of electric cars; and they’re in the power grid itself, where they mediate between high-voltage transmission lines and the lower voltages of household electrical sockets.

Power conversion is intrinsically inefficient: A power converter will never output quite as much power as it takes in. But recently, power converters made from gallium nitride have begun to reach the market, boasting higher efficiencies and smaller sizes than conventional, silicon-based power converters.

Commercial gallium nitride power devices can’t handle voltages above about 600 volts, however, which limits their use to household electronics.

At the Institute of Electrical and Electronics Engineers’ International Electron Devices Meeting this week, researchers from MIT, semiconductor company IQE, Columbia University, IBM, and the Singapore-MIT Alliance for Research and Technology, presented a new design that, in tests, enabled gallium nitride power devices to handle voltages of 1,200 volts.

That’s already enough capacity for use in electric vehicles, but the researchers emphasize that their device is a first prototype manufactured in an academic lab. They believe that further work can boost its capacity to the 3,300-to-5,000-volt range, to bring the efficiencies of gallium nitride to the power electronics in the electrical grid itself.

That’s because the new device uses a fundamentally different design from existing gallium nitride power electronics.

“All the devices that are commercially available are what are called lateral devices,” says Tomás Palacios, who is an MIT professor of electrical engineering and computer science, a member of the Microsystems Technology Laboratories, and senior author on the new paper. “So the entire device is fabricated on the top surface of the gallium nitride wafer, which is good for low-power applications like the laptop charger. But for medium- and high-power applications, vertical devices are much better. These are devices where the current, instead of flowing through the surface of the semiconductor, flows through the wafer, across the semiconductor. Vertical devices are much better in terms of how much voltage they can manage and how much current they control.”

For one thing, Palacios explains, current flows into one surface of a vertical device and out the other. That means that there’s simply more space in which to attach input and output wires, which enables higher current loads.

For another, Palacios says, “when you have lateral devices, all the current flows through a very narrow slab of material close to the surface. We are talking about a slab of material that could be just 50 nanometers in thickness. So all the current goes through there, and all the heat is being generated in that very narrow region, so it gets really, really, really hot. In a vertical device, the current flows through the entire wafer, so the heat dissipation is much more uniform.”

Narrowing the field

Although their advantages are well-known, vertical devices have been difficult to fabricate in gallium nitride. Power electronics depend on transistors, devices in which a charge applied to a “gate” switches a semiconductor material — such as silicon or gallium nitride — between a conductive and a nonconductive state.

For that switching to be efficient, the current flowing through the semiconductor needs to be confined to a relatively small area, where the gate’s electric field can exert an influence on it. In the past, researchers had attempted to build vertical transistors by embedding physical barriers in the gallium nitride to direct current into a channel beneath the gate.

But the barriers are built from a temperamental material that’s costly and difficult to produce, and integrating it with the surrounding gallium nitride in a way that doesn’t disrupt the transistor’s electronic properties has also proven challenging.

Palacios and his collaborators adopt a simple but effective alternative. The team includes first authors Yuhao Zhang, a postdoc in Palacios’s lab, and Min Sun, who received his MIT PhD in the Department of Electrical Engineering and Computer Science (EECS) last spring; Daniel Piedra and Yuxuan Lin, MIT graduate students in EECS; Jie Hu, a postdoc in Palacios’s group; Zhihong Liu of the Singapore-MIT Alliance for Research and Technology; Xiang Gao of IQE; and Columbia’s Ken Shepard.

Rather than using an internal barrier to route current into a narrow region of a larger device, they simply use a narrower device. Their vertical gallium nitride transistors have bladelike protrusions on top, known as “fins.” On both sides of each fin are electrical contacts that together act as a gate. Current enters the transistor through another contact, on top of the fin, and exits through the bottom of the device. The narrowness of the fin ensures that the gate electrode will be able to switch the transistor on and off.

“Yuhao and Min’s brilliant idea, I think, was to say, ‘Instead of confining the current by having multiple materials in the same wafer, let’s confine it geometrically by removing the material from those regions where we don’t want the current to flow,’” Palacios says. “Instead of doing the complicated zigzag path for the current in conventional vertical transistors, let’s change the geometry of the transistor completely.”

‘Swiss army knife’ Nanovaccine carries multiple weapons to battle tumors – cancer


Swiss Army Knife of Nano Ps 171129163851_1_540x360
Source: National Institute of Biomedical Imaging and Bioengineering
Summary: Researchers have developed a synergistic cancer nanovaccine packing DNA and RNA sequences that modulate the immune response, along with anti-tumor antigens, into one small nanoparticle.
(Above) Large particles (left) containing the DNA and RNA components are coated with electronically charged molecules that shrink the particle. The tumor-specific neoantigen is then complexed with the surface to complete construction of the nanovaccine. Upper left: electron micrograph of large particle. Credit: Zhu, et al. Nat Comm.

 

 

Scientists are using their increasing knowledge of the complex interaction between cancer and the immune system to engineer increasingly potent anti-cancer vaccines. The nanovaccine produced an immune response that specifically killed tumor tissue, while simultaneously inhibiting tumor-induced immune suppression to block lung tumor growth in a mouse model of metastatic colon cancer.

Now researchers at the National Institute of Biomedical Imaging and Bioengineering (NIBIB) have developed a synergistic nanovaccine packing DNA and RNA sequences that modulate the immune response, along with anti-tumor antigens, into one small nanoparticle. The nanovaccine produced an immune response that specifically killed tumor tissue, while simultaneously inhibiting tumor-induced immune suppression. Together this blocked lung tumor growth in a mouse model of metastatic colon cancer.

The molecular dance between cancer and the immune system is a complex one and scientists continue to identify the specific molecular pathways that rev up or tamp down the immune system. Biomedical engineers are using this knowledge to create nanoparticles that can carry different molecular agents that target these pathways. The goal is to simultaneously stimulate the immune system to specifically attack the tumor while also inhibiting the suppression of the immune system, which often occurs in cancer patients. The aim is to press on the gas pedal of the immune system while also releasing the emergency brake.

A key hurdle is to design a system to reproducibly and efficiently create a nanoparticle loaded with multiple agents that synergize to mount an enhanced immune attack on the tumor. Engineers at the NIBIB report the development and testing of such a nanovaccine in the November issue of Nature Communications.

Making all the parts fit

Guizhi Zhu, Ph.D., a post-doctoral fellow in the NIBIB Laboratory of Molecular Imaging and Nanomedicine (LOMIN) and lead author on the study, explains the challenge. “We are very excited about putting multiple cooperating molecules that have anti-cancer activity into one nanovaccine to increase effectiveness. However, the bioengineering challenge is fitting everything in to a small particle and designing a way to maintain its structural integrity and biological activity.”

Zhu and his colleagues have created what they call a “self-assembling, intertwining DNA-RNA nanocapsule loaded with tumor neoantigens.” They describe it as a synergistic vaccine because the components work together to stimulate and enhance an immune attack against a tumor.

The DNA component of the vaccine is known to stimulate immune cells to work with partner immune cells for antitumor activation. The tumor neoantigens are pieces of proteins that are only present in the tumor; so, when the DNA attracts the immune cells, the immune cells interact with the tumor neoantigens and mount an expanded and specific immune response against the tumor. The RNA is the component that inhibits suppression of the immune system. The engineered RNA binds to and degrades the tumor’s mRNA that makes a protein called STAT3. Thus, the bound mRNA is blocked from making STAT3, which may suppress the immune system. The result is an enhanced immune response that is specific to the tumor and does not harm healthy tissues.

In addition to engineering a system where the DNA, RNA and tumor neoantigens self-assemble into a stable nanoparticle, an important final step in the process is shrinking the particle. Zhu explains: “Shrinking the particle is a critical step for activating an immune response. This is because a very small nanoparticle can more readily move through the lymphatic vessels to reach the parts of the immune system such as lymph nodes. A process that is essential for immune activation.”

The method for shrinking also had to be engineered. This was achieved by coating the particle with a positively charged polypeptide that interacts with the negatively charged DNA and RNA components to condense it to one-tenth of its original size.

Testing the nanovaccine

To create a model of metastatic colon cancer, the researchers injected human colon cancer cells into the circulation of mice. The cells infiltrate different organs and grow as metastatic colon cancer. One of the prime sites of metastasis is the lung.

The nanovaccine was injected under the skin of the mice 10, 16, and 22 days after the colon cancer cells were injected. To compare to the nanovaccine, two control groups of mice were analyzed; one group was injected with just the DNA and the neoantigen in solution but not formed into a nanovaccine particle, and the second control group was injected with an inert buffer solution.

At 40 days into the experiment, lung tumors from the nanovaccine-treated and the control groups were assessed by PET-CT imaging, and then removed and weighed. In mice treated with the nanovaccine, tumors were consistently one tenth the size of the tumors that were found in mice in both control groups.

Further testing revealed that mice receiving the nanovaccine had a significant increase in circulating cytotoxic T lymphocytes (CTLs) that specifically targeted the neoantigen on the colon cancer cells. CTLs are cells that attack and kill virus-infected cells and those damaged in other ways, such as cancerous cells.

An important aspect of the nanovaccine approach is that it mounts an anti-tumor immune response that circulates through the system, and therefore is particularly valuable for finding and inhibiting metastatic tumors growing throughout the body.

The researchers view their nanovaccine as an important part of eventual therapies combining immunotherapy with other cancer killing approaches.

Story Source:

Materials provided by National Institute of Biomedical Imaging and BioengineeringNote: Content may be edited for style and length.


Journal Reference:

  1. Guizhi Zhu, Lei Mei, Harshad D. Vishwasrao, Orit Jacobson, Zhantong Wang, Yijing Liu, Bryant C. Yung, Xiao Fu, Albert Jin, Gang Niu, Qin Wang, Fuwu Zhang, Hari Shroff, Xiaoyuan Chen. Intertwining DNA-RNA nanocapsules loaded with tumor neoantigens as synergistic nanovaccines for cancer immunotherapyNature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-01386-7

Chemists synthesize Nano-Ribbons of Graphene for the Next Generation of Semiconductors: Applications for Electronic Devices


UCLA 2-chemistssyntAn illustration of the molecular structure of graphene nanoribbons produced by UCLA scientists. Credit: Yves Rubin

Silicon—the shiny, brittle metal commonly used to make semiconductors—is an essential ingredient of modern-day electronics. But as electronic devices have become smaller and smaller, creating tiny silicon components that fit inside them has become more challenging and more expensive.

Now, UCLA chemists have developed a new method to produce nanoribbons of graphene, next-generation structures that many scientists believe will one day power .

This research is published online in the Journal of the American Chemical Society.

The nanoribbons are extremely narrow strips of graphene, the width of just a few carbon . They’re useful because they possess a bandgap, which means that electrons must be “pushed” to flow through them to create electrical current, said Yves Rubin, a professor of chemistry in the UCLA College and the lead author of the research.

“A material that has no bandgap lets electrons flow through unhindered and cannot be used to build logic circuits,” he said.

Rubin and his research team constructed graphene nanoribbons molecule by molecule using a simple reaction based on ultraviolet light and exposure to 600-degree heat.

“Nobody else has been able to do that, but it will be important if one wants to build these molecules on an industrial scale,” said Rubin, who also is a member of the California NanoSystems Institute at UCLA.

The process improves upon other existing methods for creating graphene nanoribbons, one of which involves snipping open tubes of  known as carbon nanotubes. That particular approach is imprecise and produces ribbons of inconsistent sizes—a problem because the value of a nanoribbon’s bandgap depends on its width, Rubin said.

To create the nanoribbons, the scientists started by growing crystals of four different colorless molecules. The crystals locked the molecules into the perfect orientation to react, and the team then used light to stitch the  into polymers, which are large structures made of repeating units of carbon and .

The scientists then placed the shiny, deep blue polymers in an oven containing only argon gas and heated them to 600 degrees Celsius. The heat provided the necessary boost of energy for the polymers to form the final bonds that gave the nanoribbons their final shape: hexagonal rings composed of carbon atoms, and hydrogen atoms along the edges of the ribbons.

“We’re essentially charring the polymers, but we’re doing it in a controlled way,” Rubin said.

The process, which took about an hour, yielded  just eight  wide but thousands of atoms long. The scientists verified the molecular structure of the nanoribbons, which were deep black in color and lustrous, by shining light of different wavelengths at them.

“We looked at what wavelengths of light were absorbed,” Rubin said. “This reveals signatures of the structure and composition of the ribbons.”

The researchers have filed a patent application for the process.

Rubin said the team now is studying how to better manipulate the nanoribbons—a challenge because they tend to stick together.

“Right now, they are bundles of fibers,” Rubin said. “The next step will be able to handle each nanoribbon one by one.”

 Explore further: A nanotransistor made of graphene nanoribbons

More information: Robert S. Jordan et al. Synthesis of N = 8 Armchair Graphene Nanoribbons from Four Distinct Polydiacetylenes, Journal of the American Chemical Society (2017). DOI: 10.1021/jacs.7b08800

 

Researchers use nanoparticles to target and kill endometrial cancer


Cancer Killer 57-researchersuUI researchers loaded nanoparticles with two cancer drugs and injected them into lab mice with type II endometrial cancer. The super-lethal nanoparticles reduced tumor growth and extended survival rates. In this photo, tiny green …more

Tumor-targeting nanoparticles loaded with a drug that makes cancer cells more vulnerable to chemotherapy’s toxicity could be used to treat an aggressive and often deadly form of endometrial cancer, according to new research by the University of Iowa College of Pharmacy.

For the first time, researchers combined traditional chemotherapy with a relatively new cancer  that attacks chemo-resistant  cells, loaded both into tiny nanoparticles, and created an extremely selective and lethal . Results of the three-year lab study were published today in the journal Nature Nanotechnology.

The new treatment could mean improved survival rates for the roughly 6,000 U.S. women diagnosed with type II endometrial cancer every year and also represents an important step in the development of targeted cancer therapies. In contrast to chemotherapy, the current standard in cancer treatment that exposes the entire body to anti-cancer drugs, targeted treatments deliver drugs directly to the tumor site, thereby protecting healthy tissue and organs and enhancing drug efficacy.

“In this particular study, we took on one of the biggest challenges in cancer research, which is tumor targeting,” said Kareem Ebeid, a UI pharmacy science graduate student and lead researcher on the study. “And for the first time, we were able to combine two different tumor-targeting strategies and use them to defeat deadly type II endometrial cancer. We believe this treatment could be used to fight other cancers, as well.”

In their effort to create a highly selective cancer treatment, Ebeid and his team started with tiny nanoparticles. In recent years, there has been increased interest in using nanoparticles to treat cancer, in large part because of their small size. Tumors grow quickly, and the blood vessels they create to feed their growth are defective and full of holes. Nanoparticles are small enough to slip through the holes, thereby allowing them to specifically target tumors.

Researchers then fueled the nanoparticles with two anti-cancer drugs: paclitaxel, a type of chemotherapy used to treat endometrial cancer, and nintedanib, or BIBF 1120, a relatively new drug used to restrict tumor blood vessel growth. However, in the UI study, the drug was used for a different purpose. Besides limiting , nintedanib also targets tumor cells with a specific mutation. The mutation, known as Loss of Function p53, interrupts the normal life cycle of tumor cells and makes them more resistant to the lethal effects of chemotherapy.

Chemotherapy kills cells when they are in the process of mitosis, or cell division, and tumor cells with the Loss of Function p53 mutation often are stuck in a limbo state that slows this process. Cancers that are resistant to chemotherapy are much harder to treat and have less favorable outcomes.

Nintedanib attacks tumor cells with the Loss of Function p53 mutation and compels them to enter mitosis and divide, at which point they are more easily killed by chemotherapy. Ebeid says this is the first time that researchers have used nintedanib to force tumor  into mitosis and kill them—a phenomenon scientists refer to as “synthetic lethality.”

“Basically, we are taking advantage of the ‘ Achilles heel—the Loss of Function mutation—and then sweeping in and killing them with chemotherapy,” Ebeid says. “We call this a synthetically lethal situation because we are creating the right conditions for massive cell death.”

The treatment—and cellular death that it incites—could be used to treat other cancers as well, including types of ovarian and lung cancers that also carry the Loss of Function p53 mutation.

“We believe our research could have a positive impact beyond the treatment of endometrial cancer,” says Aliasger K. Salem, professor of pharmaceutical sciences at the UI and corresponding author on the study. “We hope that since the drugs used in our study have already been approved for clinical use, we will be able to begin working with patients soon.”

Incidence and mortality rates for endometrial cancer have been on the rise in the U.S. in recent years, especially in Iowa. Type I endometrial cancer, which feeds on the hormone estrogen, accounts for about 80 percent of new cases annually. Type II endometrial cancer is less common, accounting for roughly 10 percent to 20 percent of cases, but is much more aggressive, resulting in 39 percent of total endometrial  deaths every year.

“For two decades, the standard therapy for type II  has been  and radiation,” says Kimberly K. Leslie, professor and chair of the Department of Obstetrics and Gynecology at the UI Roy J. and Lucille A. Carver College of Medicine. “The possibility of a new  that is both highly selective and highly effective is incredibly exciting.”

 Explore further: Genetic targets to chemo-resistant breast cancer identified

More information: Synthetically lethal nanoparticles for treatment of endometrial cancer, Nature Nanotechnology (2017). nature.com/articles/doi:10.1038/s41565-017-0009-7

 

Stanford University: Graphene takes the strain in all-carbon stretchable transistors: Applications for displays, functional sensors and digital circuits for electronic skin


Graphene’s unique combination of electrical and physical properties marks it out as a potential candidate for transparent, stretchable electronics, which could enable a new generation of sophisticated displays, wearable health monitors, or soft robotic devices. But, although graphene is atomically thin, highly transparent, conductive, and more stretchable than conventional indium tin oxide electrodes, it still tends to crack at small strains.

Now researchers from Stanford University believe they have found a way to overcome this shortcoming and have created the most stretchable carbon-based transistors to date [Liu et al., Science Advances 3 (2017) e1700159].

“To enable excellent strain-dependent performance of transparent graphene conductors, we created graphene nanoscrolls in between stacked graphene layers,” explains first author of the study, Nan Liu

Illustration of the stacked graphene MGG structure.

The team led by Zhenan Bao dub their combination of rolled up sheets of graphene sandwiched in between stacked graphene layers ‘multi-layer G/G scrolls’ or MGG. The scrolls, which are 1–20 microns long, 0.1–1 microns wide, and 10–100 nm high, form naturally during the wet transfer process as graphene is moved from one substrate to another.

“By using MGG graphene stretchable electrodes (source/drain and gate) and semiconducting carbon nanotubes, we were able to demonstrate highly transparent and highly stretchable all-carbon transistors,” says Liu.

The all-carbon devices fabricated by the team retain 60% of their original current output when stretched to 120% strain (parallel to the direction of charge transport). This is the most stretchable carbon-based transistor reported to date, believe the researchers.

The graphene scrolls are key to the stretchable electrode’s remarkable properties because they seem to provide a conductive path even when graphene sheets start to crack at high strain levels.

“Taking into account the electronic and optical properties as well as the cost, our MGG exhibits substantial strengths over other conductors, such as carbon nanotubes and metal nanowires,” says Liu.

Transparent, stretchable graphene electrodes could be useful as contacts in flexible electronic circuits such as backplane control units for displays, as well as functional sensors and digital circuits for electronic skin.

“This is a very important area of research with a variety of possible applications,” comments Andrea C. Ferrari of the University of Cambridge. “The approach taken by Bao et al. is an interesting one that could be quite general.”

The concept of using a mixture of graphene scrolls and platelets to enable an electrode to stretch without significant losses in transmittance or conductivity is a good and should, in principle, not be too complicated to scale up for real devices, he adds.

“We are now seeking to extend this method to other two-dimensional materials, such as MoS2, to enable stretchable two-dimensional semiconductors,” says Liu.

This article was originally published in Nano Today (2017), doi: 10.1016/j.nantod.2017.10.005.

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene – Faster Devices at a Fraction of Energy Costs


Researchers of the ICN2 Theoretical and Computational Nanoscience Group, led by ICREA Prof. Stephan Roche, have published another paper on spin, this time reporting numerical simulations for spin relaxation in graphene/TMDC heterostructures.

Published in Physical Review Letters this week, spintronics researchers of the ICN2 Theoretical and Computational Nanoscience Group led by ICREA Prof. Stephan Roche have gleaned potentially game-changing insight into the mechanisms governing spin dynamics and relaxation in graphene/TMDC heterostructures. Not only do their models give a spin lifetime anisotropy that is orders of magnitude larger than the 1:1 ratio typically observed in 2D systems, but they point to a qualitatively new regime of spin relaxation.

Spin relaxation is the process whereby the spins in a spin current lose their orientation, reverting to a natural disordered state. This causes spin signal to be lost, since spins are only useful for transporting information when they are oriented in a certain direction.

This study reveals that the rate at which spins relax in graphene/TMDC systems depends strongly on whether they are pointing in or out of the graphene plane, with out-of-plane spins lasting tens or hundreds of times longer than in-plane spins. Such a high ratio has not previously been observed in graphene or any other 2D material.

In the paper, aptly titled “Giant Spin Lifetime Anisotropy in Graphene Induced by Proximity Effects”, lead author Aron Cummings reports that this behaviour is mediated by the spin-valley locking induced in graphene by the TMDC, which ties the lifetime of in-plane spin to the intervalley scattering time. This causes in-plane spin to relax much faster than out-of-plane spin.

Furthermore, the numerical simulations suggest that this mechanism should come into play in any substrate with strong spin-valley locking, including the TMDCs themselves.

Effectively inducing a spin filter effect –the ability to sort or tweak spin orientations–, these findings give reason to believe that it might one day be possible to manipulate, and not just transport, spin in graphene.

These simulations have since been borne out experimentally by colleagues in the ICN2 Physics and Engineering of Nanodevices Group, led by ICREA Prof. Sergio Valenzuela. Paper coming soon.

Background:

Spintronics is a branch of electronics that uses the spin of subatomic particles like electrons to store and transport information. It promises devices that are faster, operate at a fraction of the energy cost and have vastly superior memories. However, establishing a spin current is not a straightforward process. First, because spin in its natural state is disordered; that is, the spin axes are pointing in any number of directions. They must first be polarised to tune their orientation.

Then, even once polarised, the spins can lose this orientation easily in a process known as spin relaxation, which limits the lifetime and therefore usefulness of spin currents in practice.

Enter graphene, very much the material of the moment and not without good reason: this 2D material boasts a series of properties that make it uniquely suited for maintaining spin orientation over long lifetimes. However, its low spin-orbit coupling (SOC) makes it ineffective for manipulating spin.

The solution adopted in spintronics is to create layered heterostructures, harnessing the spin transport properties of graphene and a second high SOC material in a single system. This works through the proximity effect, whereby graphene becomes imprinted with the properties of the second material, and has been proven experimentally with 2D magnetic insulators and transition metal dichalcogenides (TMDCs).

In this work, researchers have studied spin relaxation in such layered graphene/TMDC heterostructures in a bid to shed some light on the as yet unexplored mechanisms governing spin relaxation in these systems. Spin lifetime anisotropy is the ratio of out-of-plane to in-plane spin lifetimes, and is used as a measurement of these mechanisms. What they find is a unique mechanism enabled by the specific proximity effect of TMDCs on graphene.

Article reference:

A.W. Cummings, J.H. García, J. Fabian, and S. Roche. Giant Spin Lifetime Anisotropy in Graphene Induced by Proximity Effects. Physical Review Letters 2017, Vol. 119, p. 206601. DOI: 10.1103/PhysRevLett.119.206601

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