Rice University: Designing Materials with ‘Stiffness and Flexibility’


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Materials scientists at Rice University are looking to nature — at the discs in human spines and the skin in ocean-diving fish, for example — for clues about designing materials with seemingly contradictory properties — flexibility and stiffness.

In research graduate student Peter Owuor, research scientist Chandra Sekhar Tiwary and colleagues from the laboratories of Rice Professor Pulickel Ajayan and Jun Lou found they could increase the stiffness, or “elastic modulus,” of a soft silicon-based polymer by infusing it with tiny pockets of liquid gallium.

Such composites could find use in high-energy absorption materials and shock absorbers and in biomimetic structures like artificial intervertebral discs, they said.

Owuor said conventional wisdom in composite design for the past 60 years has been that adding a harder substance increases modulus and adding a softer one decreases modulus. In most instances, that’s correct.

“People had not really looked at it from the other way around,” he said. “Is it possible to add something soft inside something else that is also soft and get something that has a higher modulus? If you look at the natural world, there are plenty of examples where you find exactly that. As materials scientists, we wanted to study this, not from a biological perspective but rather from a mechanical one.”

For example, the discs between the vertebrae in human spines, which act like both shock absorbers and ligaments, are made of a tough outer layer of cartilage and a soft, jelly-like interior. And the outer skin of deep-diving ocean fish and mammals contain myriad tiny oil-filled chambers — some no larger than a virus and others larger than entire cells — that allow the animals to withstand the intense pressures that exist thousands of feet below the ocean’s surface.Rice Flex Materials2 38906-53.jpg

Choosing the basic materials to model these living systems was relatively easy, but finding a way to bring them together to mimic nature proved difficult, said Tiwary, a postdoctoral research associate in Rice’s Department of Materials Science and NanoEngineering.

Polydimethylsiloxane, or PDMS, was chosen as the soft encapsulating layer for a number of reasons: It’s cheap, inert, nontoxic and widely used in everything from caulk and aquarium sealants to cosmetics and food additives. It also dries clear, which made it easy to see the bubbles of liquid the team wanted to encapsulate. For that, the researchers chose gallium, which like mercury is liquid at room temperature, but unlike mercury is nontoxic and relatively easy to work with.

Owuor said it took nearly four months to find a recipe for encapsulating bubbles of gallium inside PDMS. His test samples are about the diameter of a small coin and as much as a quarter-inch thick. By curing the PDMS slowly, Owuor developed a process by which he could add gallium droplets of various sizes. Some samples contained one large inner chamber, and others contained up to a dozen discrete droplets.

Each sample was subjected to dozens of tests. A dynamic mechanical analysis instrument was used to measure how much the material deformed under load, and various measures like stiffness, toughness and elasticity were measured under a variety of conditions. For example, with a relatively small amount of cooling, gallium can be turned into a solid. So the team was able to compare some measurements taken when the gallium spheres were liquid with measures taken when the spheres were solid.

Collaborators Roy Mahapatra and Shashishekarayya Hiremath of the Indian Institute of Science at Bangalore used finite element modeling and hydrodynamic simulations to help the team analyze how the materials behaved under mechanical stress. Based on this, the researchers determined that pockets of liquid gallium gave the composite higher energy absorption and dissipation characteristics than plain PDMS or PDMS with air-filled pockets.

“What we’ve shown is that putting liquid inside a solid is not always going to make it softer, and thanks to our collaborators we are able to explain why this is the case,” Tiwary said. “Next we hope to use this understanding to try to engineer materials to take advantage of these properties.”

Owuor and Tiwary said just using nanoengineering alone may not provide a maximum effect. Instead, nature employs hierarchical structures with features of varying sizes that repeat at larger scales, like those found in the oil-filled chambers in fish skin.

“If you look at (the fish’s) membrane and you section it, there is a layer where you have spheres with big diameters, and as you move, the diameters keep decreasing,” Owuor said. “The chambers are seen across the whole scale, from the nano- all the way out to the microscale.

Tiwary said, “There are important nanoscale features in nature, but it’s not all nano. We may find that engineering at the nanoscale alone isn’t enough. We want to see if we can start designing in a hierarchical way.”

Ajayan is chair of Rice’s Department of Materials Science and NanoEngineering, the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of chemistry.

The research was supported by the Air Force Office of Scientific Research. Additional Rice co-authors include Lou, Alin Chipara and Robert Vajtai.

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MIT: Powering up graphene implants without frying cells ~ For the Next Generation of Implants


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This computational illustration shows a graphene network structure below a layer of water.

Image: Zhao Qin

New analysis finds way to safely conduct heat from graphene to biological tissues.

In the future, our health may be monitored and maintained by tiny sensors and drug dispensers, deployed within the body and made from graphene — one of the strongest, lightest materials in the world. Graphene is composed of a single sheet of carbon atoms, linked together like razor-thin chicken wire, and its properties may be tuned in countless ways, making it a versatile material for tiny, next-generation implants.

But graphene is incredibly stiff, whereas biological tissue is soft. Because of this, any power applied to operate a graphene implant could precipitously heat up and fry surrounding cells.

Now, engineers from MIT and Tsinghua University in Beijing have precisely simulated how electrical power may generate heat between a single layer of graphene and a simple cell membrane. While direct contact between the two layers inevitably overheats and kills the cell, the researchers found they could prevent this effect with a very thin, in-between layer of water.

By tuning the thickness of this intermediate water layer, the researchers could carefully control the amount of heat transferred between graphene and biological tissue. They also identified the critical power to apply to the graphene layer, without frying the cell membrane. The results are published today in the journal Nature Communications.

Co-author Zhao Qin, a research scientist in MIT’s Department of Civil and Environmental Engineering (CEE), says the team’s simulations may help guide the development of graphene implants and their optimal power requirements.

“We’ve provided a lot of insight, like what’s the critical power we can accept that will not fry the cell,” Qin says. “But sometimes we might want to intentionally increase the temperature, because for some biomedical applications, we want to kill cells like cancer cells. This work can also be used as guidance [for those efforts.]”

Qin’s co-authors include Markus Buehler, head of CEE and the McAfee Professor of Engineering, along with Yanlei Wang and Zhiping Xu of Tsinghua University.

Sandwich model

Typically, heat travels between two materials via vibrations in each material’s atoms. These atoms are always vibrating, at frequencies that depend on the properties of their materials. As a surface heats up, its atoms vibrate even more, causing collisions with other atoms and transferring heat in the process.

The researchers sought to accurately characterize the way heat travels, at the level of individual atoms, between graphene and biological tissue. To do this, they considered the simplest interface, comprising a small, 500-nanometer-square sheet of graphene and a simple cell membrane, separated by a thin layer of water.

mit-graphene-ii-shutterstock_62457640-610x406“In the body, water is everywhere, and the outer surface of membranes will always like to interact with water, so you cannot totally remove it,” Qin says. “So we came up with a sandwich model for graphene, water, and membrane, that is a crystal clear system for seeing the thermal conductance between these two materials.”

Qin’s colleagues at Tsinghua University had previously developed a model to precisely simulate the interactions between atoms in graphene and water, using density functional theory — a computational modeling technique that considers the structure of an atom’s electrons in determining how that atom will interact with other atoms.

However, to apply this modeling technique to the group’s sandwich model, which comprised about half a million atoms, would have required an incredible amount of computational power. Instead, Qin and his colleagues used classical molecular dynamics — a mathematical technique based on a “force field” potential function, or a simplified version of the interactions between atoms — that enabled them to efficiently calculate interactions within larger atomic systems.

The researchers then built an atom-level sandwich model of graphene, water, and a cell membrane, based on the group’s simplified force field. They carried out molecular dynamics simulations in which they changed the amount of power applied to the graphene, as well as the thickness of the intermediate water layer, and observed the amount of heat that carried over from the graphene to the cell membrane.

Watery crystals

Because the stiffness of graphene and biological tissue is so different, Qin and his colleagues expected that heat would conduct rather poorly between the two materials, building up steeply in the graphene before flooding and overheating the cell membrane. However, the intermediate water layer helped dissipate this heat, easing its conduction and preventing a temperature spike in the cell membrane.

Looking more closely at the interactions within this interface, the researchers made a surprising discovery: Within the sandwich model, the water, pressed against graphene’s chicken-wire pattern, morphed into a similar crystal-like structure.

“Graphene’s lattice acts like a template to guide the water to form network structures,” Qin explains. “The water acts more like a solid material and makes the stiffness transition from graphene and membrane less abrupt. We think this helps heat to conduct from graphene to the membrane side.”

The group varied the thickness of the intermediate water layer in simulations, and found that a 1-nanometer-wide layer of water helped to dissipate heat very effectively. In terms of the power applied to the system, they calculated that about a megawatt of power per meter squared, applied in tiny, microsecond bursts, was the most power that could be applied to the interface without overheating the cell membrane.

Qin says going forward, implant designers can use the group’s model and simulations to determine the critical power requirements for graphene devices of different dimensions. As for how they might practically control the thickness of the intermediate water layer, he says graphene’s surface may be modified to attract a particular number of water molecules. mit_logo

“I think graphene provides a very promising candidate for implantable devices,” Qin says. “Our calculations can provide knowledge for designing these devices in the future, for specific applications, like sensors, monitors, and other biomedical applications.”

This research was supported in part by the MIT International Science and Technology Initiative (MISTI): MIT-China Seed Fund, the National Natural Science Foundation of China, DARPA, the Department of Defense (DoD) Office of Naval Research, the DoD Multidisciplinary Research Initiatives program, the MIT Energy Initiative, and the National Science Foundation.

“Beam Me Up Scotty” ~ Teleportation of light particles across cities in China and Canada a ‘technological breakthrough’!


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Scientists have shown they can teleport matter across a city, a development that has been hailed as “a technological breakthrough”.

However, do not expect to see something akin to the Star Trek crew beaming from the planet’s surface to the Starship Enterprise. star-trek-transporter-1280jpg-883390_1280w

Instead, in the two studies, published today in Nature Photonics, separate research groups have used quantum teleportation to send photons to new locations using fibre-optic communications networks in the cities of Hefei in China and Calgary in Canada.

Quantum teleportation is the ability to transfer information such as the properties or the quantum state of an atom — its energy, spin, motion, magnetic field and other physical properties — to another location without travelling in the space between.

Key points

  • Two experiments demonstrate teleportation of particles across real optical fibre networks for first time
  • Chinese experiment transports two photons per hour across seven kilometres
  • Canadian experiment transports 17 photons per minute across 6.2 kilometres

 

While it was first demonstrated in 1997, today’s studies are the first to show the process is technologically possible via a mainstream communications network.

The development could lead to future city-scale quantum technologies and communications networks, such as a quantum internet and improved security of internet-based information.

Dr. Ben Buchler, Associate Professor with the Centre for Quantum Computation and Communication Technology at the Australian National University, said the technical achievement of completing the experiments in a “non-ideal environment” was “pretty profound”.

“People have known how to do this experiment since the early 2000s, but until these papers it hasn’t been performed in fibre communication networks, in situ, in cities,” said Dr. Buchler, who was not involved in the research.

“It’s seriously difficult to do what they have done.”

Watch the YouTube Video: “The Metaphysics of Teleportation” – Dr. Michio Kaku

 

A cornerstone of quantum teleportation is quantum entanglement, where two particles are intimately linked to each other in such a way that a change in one will affect the other.

Dr. Buchler said quantum teleportation involved mixing a photon with one branch of the entanglement and this joint element was then measured. The other branch of the entanglement was sent to the receiving party or new location.

This original ‘joint’ measurement is sent to the receiver, who can then use that information to manipulate the other branch of the entanglement.

“The thing that pops out is the original photon, in a sense it has indistinguishable characteristics from the one you put in,” Dr Buchler said.

Overcoming technical barriers

He said both teams had successfully overcome technical barriers to ensure the precise timing of photon arrival and accurate polarisation within the fibres.

The Chinese team teleported single protons using the standard telecommunications wavelength across a distance of seven kilometres, whiled the Canadian team teleported single photons up to 6.2 kilometres.

But work remained to increase the speed of the system with the Chinese group teleporting just two photons per hour and the Canadians a faster rate of 17 photons per minute.

Dr. Buchler said the speeds meant the development had little immediate practical value, but “this kind of teleportation is part of the protocol people imagine will be able to extend the range of quantum key distribution” — a technique used to send secure encrypted messages.

In the future scientists envision the evolution of a quantum internet that would allow the communication of quantum information between quantum computers.

Quantum computers on their own would allow fast computation, but networked quantum computers would be more powerful still.

Dr. Buchler said today’s studies were a foundation stone toward that vision as it showed it was possible to move quantum information from one location to another within mainstream networks without destroying it.

Yes … a LOT more work has to be done however before we “Warp” and “Beam” … but to put it into the words of ‘The Good Doctor’ …

“Damit Jim, I’m ONLY a doctor!” (Highly Logical) “Live long and Prosper!”

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MIT: Seeking sustainable solutions through Nanotechnology – Engineer’s designs may help purify water, diagnose disease in remote regions of world.


mit-karnik-rohit-1“I try to guide my research by … asking myself the question, ‘What can we do today that will have a lasting impact and be conducive to a sustainable human civilization?’” says Rohit Karnik, an associate professor in MIT’s Department of Mechanical Engineering. Photo: Ken Richardson

In Rohit Karnik’s lab, researchers are searching for tiny solutions to some of the world’s biggest challenges.

In one of his many projects, Karnik, an associate professor in MIT’s Department of Mechanical Engineering, is developing a new microfluidic technology that can quickly and simply sorts cells from small samples of blood. The surface of a microfluidic channel is patterned to direct certain cells to roll toward a reservoir for further analysis, while allowing the rest of the blood sample to pass through. With this design, Karnik envisions developing portable, disposable devices that doctors may use, even in remote regions of the world, to quickly diagnose conditions ranging from malaria to sepsis.

Karnik’s group is also tackling issues of water purification. The researchers are designing filters from single layers of graphene, which are atom-thin sheets of carbon known for their exceptional strength. Karnik has devised a way to control the size and concentration of pores in graphene, and is tailoring single layers to filter out miniscule and otherwise evasive contaminants. The group has also successfully filtered salts using the technique and hopes to develop efficient graphene filters for water purification and other applications. Silver Nano P clean-drinking-water-india

In looking for water-purifying solutions, Karnik’s group also identified a surprisingly low-tech option: the simple tree branch. Karnik found that the pores within a pine branch that normally help to transport water up the plant are ideal for filtering bacteria from water. The group has shown that a peeled pine branch can filter out up to 99.00 percent of E. coli from contaminated water. Karnik’s group is building up on this work to explore the potential for simple and affordable wood-based water purification systems.

“I try to guide my research by long-term sustainability, in a specific sense, by asking myself the question, ‘What can we do today that will have a lasting impact and be conducive to a sustainable human civilization?’ Karnik says. “I try to align myself with that goal.”

From stargazer to tinkerer

Karnik was born and raised in Pune, India, which was then a relatively quiet city 100 miles east of Mumbai. Karnik describes himself while growing up as shy, yet curious about the way the world worked. He would often set up simple experiments in his backyard, seeing, for instance, how transplanting ants from one colony to another would change the ants’ behavior. (The short answer: They fought, sometimes to the death.) He developed an interest in astronomy early on and often explored the night sky with a small telescope, from the roof of his family’s home.

“I used to take my telescope up to the terrace in the middle of the night, which required three different trips up six or seven flights of stairs,” Karnik says. “I’d set the alarm for 3 a.m., go up, and do quite a bit of stargazing.”

That telescope would soon serve another use, as Karnik eventually found that, by inverting it and adding another lens, he could repurpose the telescope as a microscope.

“I built a little setup so I could look at different things, and I used to collect stuff from around the house, like onion peels or fungus growing on trees, to look at their cells,” Karnik says.

When it came time to decide on a path of study, Karnik was inspired by his uncle, a mechanical engineer who built custom machines “that did all kinds of things, from making concrete bricks, to winding up springs,” Karnik says. “What I saw in mechanical engineering was the ability to building something that integrates across different disciplines.”

Seeking balance and insight

As an entering student at the Indian Institute of Technology Bombay, Karnik chose to study mechanical engineering over electrical engineering, which was the more popular choice among students at the time. For his thesis, he looked for new ways to model three-dimensional cracks in materials such as steel beams.

Casting around for a direction after graduating, Karnik landed on the fast-growing field of nanotechnology. Arun Majumdar, an IIT alum and professor at the University of California at Berkeley, was studying energy conversion and biosensing in nanoscale systems. Karnik joined the professor’s lab as a graduate student, moving to California in 2002. For his graduate work, Karnik helped to develop a microfluidic platform to rapidly mix the contents of and test reactions occurring within droplets. He followed this work up with a PhD thesis in which he explored how fluid, flowing through tiny, nanometer-sized channels, can be controlled  to sense and direct ions and molecules.

Toward the end of his graduate work, Karnik interviewed for and ultimately accepted a faculty position at MIT. However, he was still completing his PhD thesis at Berkeley and had less than 4 years of experience beyond his bachelor’s degree. To help ease the transition, MIT offered Karnik an interim postdoc position in the lab of Robert Langer, the David H. Koch Institute Professor and a member of the Koch Institute for Integrative Cancer Research.

“It was an insightful experience,” Karnik remembers. “For a mechanical engineer who’s never been outside mechanical engineering, I basically had little experience how to do things in biology. It opened up possibilities for working with the biomedical community.”

When Karnik finally assumed his position as assistant professor of mechanical engineering in 2007, he experienced a tidal wave of deadlines, demands, and responsibilities — a common initiation for first-time faculty.

“By its nature the job is overwhelming,” Karnik says. “The trick is how to maintain balance and sanity and do the things you like, without being distracted by the busyness around you, in some sense.”

He says several things have helped him to handle and even do away with stress: walks, which he takes each day to work and around campus, as well as yoga and meditation.

“If you can see things the way they are, by clearing away the filters your mind puts in place, you can get a clear perspective, and there are a lot of insights that come through,” Karnik says.

Argonne National Laboratory-led projects among $39.8 million in first-round “Exascale” Computing Project awards -Enabled Precision Medicine for Cancer


doe-iii-doeThe U.S. Department of Energy’s (DOE’s) Exascale Computing Project (ECP) today announced its first round of funding with the selection of 15 application development proposals for full funding and seven proposals for seed funding, representing teams from 45 research and academic organizations.

Exascale refers to high-performance computing systems capable of at least a billion billion calculations per second, or a factor of 50 to 100 times faster than the nation’s most powerful supercomputers in use today.

The 15 awards being announced total $39.8 million, targeting advanced modeling and simulation solutions to specific challenges supporting key DOE missions in science, clean energy and national security, as well as collaborations such as the Precision Medicine Initiative with the National Institutes of Health’s National Cancer Institute.

Of the proposals announced that are receiving full funding, two are being led by principal investigators at the DOE’s Argonne National Laboratory:

  1. Computing the Sky at Extreme Scales equips cosmologists with the ability to design foundational simulations to create “virtual universes” on demand at the extreme fidelities demanded by future multi-wavelength sky surveys. The new discoveries that will emerge from the combination of sky surveys and advanced simulation provided by the ECP will shed more light on three key ingredients of our universe: dark energy, dark matter and inflation. All three of these concepts reach beyond the known boundaries of the Standard Model of particle physics.Salman Habib, Principal Investigator, Argonne National Laboratory, with Los Alamos National Laboratory and Lawrence Berkeley National Laboratory.argone-ii-nl-mira_-_blue_gene_q_at_argonne_national_laboratory
  1. Exascale Deep Learning and Simulation Enabled Precision Medicine for Cancer focuses on building a scalable deep neural network code called the CANcer Distributed Learning Environment (CANDLE) that addresses three top challenges of the National Cancer Institute: understanding the molecular basis of key protein interactions, developing predictive models for drug response and automating the analysis and extraction of information from millions of cancer patient records to determine optimal cancer treatment strategies.Rick Stevens, Principal Investigator, Argonne National Laboratory, with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Oak Ridge National Laboratory and the National Cancer Institute.

Additionally, a third project led by Argonne will be receiving seed funding:

  1. Multiscale Coupled Urban Systems will create an integrated modeling framework comprising data curation, analytics, modeling and simulation components that will equip city designers, planners and managers to scientifically develop and evaluate solutions to issues that affect cities now and in the future. The framework will focus first on integrating urban atmosphere and infrastructure heat exchange and air flow; building energy demand at district or city-scale, generation and use; urban dynamics and socioeconomic models; population mobility and transportation; and hooks to expand to include energy systems (biofuels, electricity and natural gas) and water resources.Charlie Catlett, Principal Investigator, Argonne National Laboratory, with Lawrence Berkeley National Laboratory, National Renewable Energy Laboratory, Oak Ridge National Laboratory and Pacific Northwest National Laboratory.

The application efforts will help guide DOE’s development of a U.S. exascale ecosystem as part of President Obama’s National Strategic Computing Initiative. DOE, the U.S. Department of Defense and the National Science Foundation have been designated as lead agencies, and ECP is the primary DOE contribution to the initiative.

The ECP’s multiyear mission is to maximize the benefits of high-performance computing for U.S. economic competitiveness, national security and scientific discovery. In addition to applications, the DOE project addresses hardware, software, platforms and workforce development needs critical to the effective development and deployment of future exascale systems.

argone-nl-090115-114727Leadership of the ECP comes from six DOE national laboratories: the Office of Science’s Oak Ridge, Argonne and Lawrence Berkeley national labs and the National Nuclear Security Administration’s (NNSA’s) Lawrence Livermore, Los Alamos and Sandia national labs.

The Exascale Computing Project is a collaborative effort of two DOE organizations — the Office of Science and the NNSA. As part of President Obama’s National Strategic Computing initiative, ECP was established to develop a capable exascale ecosystem, encompassing applications, system software, hardware technologies and architectures, and workforce development to meet the scientific and national security mission needs of DOE in the mid-2020s timeframe.

Established by Congress in 2000, NNSA is a semi-autonomous agency within DOE responsible for enhancing national security through the military application of nuclear science. NNSA maintains and enhances the safety, security, and effectiveness of the U.S. nuclear weapons stockpile without nuclear explosive testing; works to reduce the global danger from weapons of mass destruction; provides the U.S. Navy with safe and effective nuclear propulsion; and responds to nuclear and radiological emergencies in the United States and abroad.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit the Office of Science website.

U of California: Nano submarines could change healthcare, says nanoengineer professor


Nano Subs 082316 1471860105809A 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.Nano Subs 061416 untitled

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.

 

Nanoparticles that Speed Blood Clotting ~ Great Things from Small Things ~ May One Day Save Lives


Blood Clot NPs 082216 10-nanoparticle.jpgNanoparticles (green) help form clots in an injured liver. The researchers added color to the scanning electron microscopy image after it was taken. Credit: Erin Lavik, Ph.D.

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 .”

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.

Nano Body II 43a262816377a448922f9811e069be13Initial studies suggested that the nanoparticles, delivered intravenously, helped keep rodents from bleeding out due to brain and spinal , 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 .

In future studies, the 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 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.

Explore further: Researchers take the inside route to halt bleeding

More information: Engineering nanoparticles to stop internal bleeding, 252nd National Meeting & Exposition of the American Chemical Society (ACS), 2016.

Abstract
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 atom’ Created in Graphene ~ What will this Mean? For Quantum Computers? For Quantum Dots?


Artificial Atom QDs 082216 artificialatThe charged tip of a scanning tunneling microscope and an additional magnetic field lead to localized stable electron states in graphene. Credit: Nils Freitag, RWTH Aachen

“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 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 are forced into discrete quantum states.” QBits 2 050616 Researchers-Break-Room-Temperature-Quantum-Bit-Storage-Record

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 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 are forced into discrete quantum states.

Even more interesting possibilities are opened up by using graphene, a material consisting of a single layer of , 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.

'Artificial atom' created in graphene
(Left) Florian Libisch, explaining the structure of graphene. Credit: TU Wien

 

 

 

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 on a small chip in order to use them for quantum information applications.

Explore further: Physicists create artificial ‘graphene’

More information: Nils M. Freitag et al, Electrostatically Confined Monolayer Graphene Quantum Dots with Orbital and Valley Splittings, Nano Letters (2016). DOI: 10.1021/acs.nanolett.6b02548

 

 

Quantum dots with impermeable shell used as a powerful tool for “nano-engineering”


QDs Shell 081116 160811101152_1_540x360Images of ZnO quantum dots prepared by the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw, taken by transmission electron microscopy. False colors.
Credit: IPC PAS

Unique optical features of quantum dots make them an attractive tool for many applications, from cutting-edge displays to medical imaging. Physical, chemical or biological properties of quantum dots must, however, be adapted to the desired needs.

Unfortunately, up to now quantum dots prepared by chemical methods could only be functionalized using copper-based click reactions with retention of their luminescence. This obstacle can be ascribed to the fact that copper ions destroy the ability of quantum dots to emit light. Scientists from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw and the Faculty of Chemistry of the Warsaw University of Technology (FC WUT) have shown, however, that zinc oxide (ZnO) quantum dots prepared by an original method developed by them, after modification by the click reaction with the participation of copper ions, fully retain their ability to emit light.

“Click reactions catalyzed by copper cations have long attracted the attention of chemists dealing with quantum dots. The experimental results, however, were disappointing: after modification, the luminescence was so poor that they were just not fit for use. We were the first to demonstrate that it is possible to produce quantum dots from organometallic precursors in a way they do not lose their valuable optical properties after being subjected to copper-catalysed click reactions,” says Prof. Janusz Lewinski (IPC PAS, FC WUT).

Quantum dots are crystalline structures with size of a few nanometers (billionth parts of a meter). As semiconductor materials, they exhibit a variety of interesting features typical of quantum objects, including absorbing and emitting radiation of only a strictly defined energy. Since atoms interact with light in a similar way, quantum dots are often called artificial atoms. In some respects, however, quantum dots offer more possibilities than atoms. Optical properties of each dot actually depend on its size and the type of material from which it is formed. This means that quantum dots may be precisely designed for specific applications.

To meet the need of specific applications, quantum dots have to be tailored in terms of physico-chemical properties. For this purpose, chemical molecules with suitable characteristics are attached to their surface. Due to the simplicity, efficacy, and speed of the process, an exceptionally convenient method is the click reaction. Unfortunately, one of the most widely used click reactions takes place with the participation of copper ions, which was reported to result in the almost complete quenching of the luminescence of the quantum dots.

“Failure is usually a result of the inadequate quality of quantum dots, which is determined by the synthesis method. Currently, ZnO dots are mainly produced by the sol-gel method from inorganic precursors. Quantum dots generated in this manner are coated with a heterogeneous and probably leaky protective shell, made of various sorts of chemical molecules. During a click reaction, the copper ions are in direct contact with the surface of quantum dots and quench the luminescence of the dot, which becomes completely useless,” explains Dr. Agnieszka Grala (IPC PAS), the first author of the article in the Chemical Communications journal.

For several years, Prof. Lewinski’s team has been developing alternative methods for the preparation of high quality ZnO quantum dots. The method presented in this paper affords the quantum dots derived from organozinc precursors. Composition of the nanoparticles can be programmed at the stage of precursors preparation, which makes it possible to precisely control the character of their organic-inorganic interface.

“Nanoparticles produced by our method are crystalline and all have almost the same size. They are spherical and have characteristics of typical quantum dots. Every nanoparticle is stabilized by an impermeable protective jacket, built of organic compounds, strongly anchored on the surface of the semiconductor core. As a result, our quantum dots remain stable for a long time and do not aggregate, that is clump together, in solutions,” describes Malgorzata Wolska-Pietkiewicz, a PhD student at FC WUT.

“The key to success is producing a uniform stabilizing shell. Such coatings are characteristic of the ZnO quantum dots obtained by our method. The organic layer behaves as a tight protective umbrella protecting dots from direct influence of the copper ions,” says Dr. Grala and clarifies: “We carried out click reaction known as alkyne-azide cycloaddition, in which we used a copper(l) compound as catalysts. After functionalization, our quantum dots shone as brightly as at the beginning.”

Quantum dots keep finding more and more applications in various industrial processes and as nanomarkers in, among others, biology and medicine, where they are combined with biologically active molecules. Nanoobjects functionalized in this manner are used to label both individual cells as well as whole tissues. The unique properties of quantum dots also enable long-term monitoring of the labelled item. Commonly used quantum dots, however, contain toxic heavy metals, including cadmium. In addition, they clump together in solutions, which supports the thesis of the lack of tightness of their shells. Meanwhile, the ZnO dots produced by Prof. Lewinski’s group are non-toxic, they do not aggregate, and can be bound to many chemical compounds — so they are much more suitable for medical diagnosis and for imaging cells and tissues.

Research on the methods of production of functionalized ZnO quantum dots was carried out under an OPUS grant from the Poland’s National Science Centre.


Story Source:

The above post is reprinted from materials provided by Institute of Physical Chemistry of the Polish Academy of Sciences.Note: Content may be edited for style and length.


Journal Reference:

  1. Agnieszka Grala, Małgorzata Wolska-Pietkiewicz, Wojciech Danowski, Zbigniew Wróbel, Justyna Grzonka, Janusz Lewiński. ‘Clickable’ ZnO nanocrystals: the superiority of a novel organometallic approach over the inorganic sol–gel procedure. Chem. Commun., 2016; 52 (46): 7340 DOI:10.1039/C6CC01430E

University of Cambridge and IBM Collaborate on “Something Deep Within” ~ Nanocrystals grown in nanowires for new classes of high-performance, energy-efficient computing, communications, and environmental and medical sensing systems.


Deep Nanowires 081116 160729143208_1_540x360Top: High-resolution electron microscopy images of a nickel silicide rhombic nanocrystal embedded in a silicon nanowire prepared with gold silicide used as a catalyst. The images demonstrate the intimate interactions that arise at the interfaces of these nanomaterials. Bottom: The physical properties that arise from such complex nano-systems could be used in next-generation photodetectors, lasers, and transistors.
Credit: Image courtesy of Department of Energy, Office of Science
 

As any good carpenter knows, it’s often easier to get what you want if you build it yourself. An international team using resources at the Center for Functional Nanomaterials took that idea to heart. They wanted to tailor extremely small wires that carry light and electrons. They devised an approach that lets them tailor the wires through exquisite control over the structures at the nanoscale. New structures could open up a potential path to a wide range of smaller, lighter, or more efficient devices.

This development could lead to highly tailored nanowires for new classes of high-performance, energy-efficient computing, communications, and environmental and medical sensing systems. The resulting devices could lead to smaller electronics as well as improving solar panels, photodetectors, and semiconductor lasers.

Semiconducting nanowires have a wide range of existing and potential applications in optoelectronic materials, from single-electron transistors and tunnel diodes, to light-emitting semiconducting nanowires to energy-harvesting devices. An international collaboration led by the University of Cambridge and IBM has demonstrated a new method to create novel nanowires that contain nanocrystals embedded within them. They accomplished this by modifying the classic “vapor-liquid-solid” crystal growth method, wherein a liquid-phase catalyst decomposes an incoming gas-phase source and mediates the deposition of the solid, growing nanowire.

In this work, a bimetallic catalyst is used. The team showed that by appropriate thermal treatment, it is possible to crystallize a solid silicide structure within the liquid catalyst, and then attach the nanowire to the solid silicon in a controlled epitaxial fashion. The Center for Functional Nanomaterials’ Electron Microscopy Facility was employed to image the nanomaterials by high spatial-resolution, aberration-corrected transmission electron microscopy. As well, scientists used a first-of-its-kind direct electron detector to obtain high temporal-resolution images of the fabrication process. Incorporating these instruments with the expertise and insight of the scientific team led to fantastic, nanoscale control over these structures and presents notable potential for a broad range of potential devices, like photodetectors and single electron transistors.


Story Source:

The above post is reprinted from materials provided byDepartment of Energy, Office of Science. Note: Content may be edited for style and length.


Journal Reference:

  1. F. Panciera, Y.-C. Chou, M. C. Reuter, D. Zakharov, E. A. Stach, S. Hofmann, F. M. Ross. Synthesis of nanostructures in nanowires using sequential catalyst reactions. Nature Materials, 2015; 14 (8): 820 DOI:10.1038/nmat4352