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hydrogen split  022616

Splitting water is a two-step process, and in a new study, researchers have performed one of these steps (reduction) with 100% efficiency. The results shatter the previous record of 60% for hydrogen production with visible light, and emphasize that future research should focus on the other step (oxidation) in order to realize practical overall water splitting. The main application of splitting water into its components of oxygen and hydrogen is that the hydrogen can then be used to deliver energy to fuel cells for powering vehicles and electronic devices.

The researchers, Philip Kalisman, Yifat Nakibli, and Lilac Amirav at the Technion-Israel Institute of Technology in Haifa, Israel, have published a paper on the perfect efficiency for the water reduction half-reaction in a recent issue of Nano Letters.

“I strongly believe that the search for clean and renewable energy sources is crucial,” Amirav toldPhys.org. “With the looming energy crisis on one hand, and environmental aspects, mainly global warming, on the other, I think this is our duty to try and amend the problem for the next generation.

“Our work shows that it is possible to obtain a perfect 100% photon-to-hydrogen production efficiency, under illumination, for the photocatalytic reduction half-reaction. These results shatter the previous benchmarks for all systems, and leave little to no room for improvement for this particular half-reaction. With a stable system and a turnover frequency of 360,000 moles of hydrogen per hour per mole of catalyst, the potential here is real.”

When an H2O molecule splits apart, the three atoms don’t simply separate from each other. The full reaction requires two H2O molecules to begin with, and then proceeds by two separate half-reactions. In the oxidation half-reaction, four individual hydrogen atoms are produced along with an O2 molecule (which is discarded). In the reduction half-reaction, the four hydrogen atoms are paired up into two H2 molecules by adding electrons, which produces the useful form of hydrogen: H2 gas.

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(Left) Transmission electron microscope images of the nanorod photocatalysts with (a) one and (b) two platinum tips. (Right) A comparison of the efficiencies shows the advantage of using a single platinum tip. Credit: Kalisman, et al. ©2016 American Chemical Society

In the new study, the researchers showed that the reduction half-reaction can be achieved with perfect efficiency on specially designed 50-nm-long nanorods placed in a water-based solution under visible light illumination. The light supplies the energy required to drive the reaction forward, with the nanorods acting as photocatalysts by absorbing the photons and in turn releasing electrons needed for the reaction.

The 100% efficiency refers to the photon-to-hydrogen conversion efficiency, and it means that virtually all of the photons that reach the photocatalyst generate an electron, and every two electrons produce one H2 molecule. At 100% yield, the half-reaction produces about 100 H2 molecules per second (or one every 10 milliseconds) on each nanorod, and a typical sample contains about 600 trillion nanorods.

One of the keys to achieving the perfect efficiency was identifying the bottleneck of the process, which was the need to quickly separate the electrons and holes (the vacant places in the semiconductor left after the electrons leave), and remove the holes from the photocatalyst. To improve the charge separation, the researchers redesigned the nanorods to have just one platinum catalyst instead of two. The researchers found that the efficiency increased from 58.5% with two platinum catalysts to 100% with only one.

Going forward, the researchers plan to further improve the system. The current demonstration requires a very high pH, but such strong basic conditions are not always ideal in practice. Another concern is that the cadmium sulfide (CdS) used in the nanorod becomes corroded under prolonged light exposure in pure water. The researchers are already addressing these challenges with the goal to realize practical solar-to-fuel technology in the future.

“We hope to implement our design rules, experience and accumulated insights for the construction of a system capable of overall water splitting and genuine solar-to-fuel energy conversion,” Amirav said.

“The photocatalytic hydrogen generation presented here is not yet genuine solar-to-fuel energy conversion, as hole scavengers are still required. CdS is unfortunately not suitable for overall water splitting since prolonged irradiation of its suspensions leads to photocorrosion. We have recently demonstrated some breakthrough on this direction as well. The addition of a second co-catalyst, such as IrO2 or Ru, which can scavenge the holes from the semiconductor and mediate their transfer to , affords CdS-based structures the desired photochemical stability. I believe this is an important milestone.”

Explore further: Core / shell photocatalyst with spatially separated cocatalysts for more efficient water splitting

More information: Philip Kalisman, et al. “Perfect Photon-to-Hydrogen Conversion Efficiency.” Nano Letters. DOI: 10.1021/acs.nanolett.5b04813

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Mass production of NMs 022616 thekeytomassNanoparticles form in a 3-D-printed microfluidic channel. Each droplet shown here is about 250 micrometers in diameter, and contains billions of platinum nanoparticles. Credit: Richard Brutchey and Noah Malmstadt/USC 

Nanoparticles – tiny particles 100,000 times smaller than the width of a strand of hair – can be found in everything from drug delivery formulations to pollution controls on cars to HD TV sets. With special properties derived from their tiny size and subsequently increased surface area, they’re critical to industry and scientific research.

They’re also expensive and tricky to make.

Now, researchers at USC have created a new way to manufacture nanoparticles that will transform the process from a painstaking, batch-by-batch drudgery into a large-scale, automated assembly line.

The method, developed by a team led by Noah Malmstadt of the USC Viterbi School of Engineering and Richard Brutchey of the USC Dornsife College of Letters, Arts and Sciences, was published in Nature Communications on Feb. 23.

Consider, for example, . They have been shown to be able to easily penetrate cell membranes without causing any damage – an unusual feat, given that most penetrations of cell membranes by foreign objects can damage or kill the cell. Their ability to slip through the cell’s membrane makes gold nanoparticles ideal delivery devices for medications to healthy cells, or fatal doses of radiation to cancer cells.

However, a single milligram of gold nanoparticles currently costs about $80 (depending on the size of the nanoparticles). That places the price of gold nanoparticles at $80,000 per gram – while a gram of pure, raw gold goes for about $50.

“It’s not the gold that’s making it expensive,” Malmstadt said. “We can make them, but it’s not like we can cheaply make a 50 gallon drum full of them.”

Right now, the process of manufacturing a nanoparticle typically involves a technician in a chemistry lab mixing up a batch of chemicals by hand in traditional lab flasks and beakers.

Brutchey and Malmstadt’s new technique instead relies on microfluidics – technology that manipulates of fluid in narrow channels.

“In order to go large scale, we have to go small,” Brutchey said. Really small.

The team 3D printed tubes about 250 micrometers in diameter – which they believe to be the smallest, fully enclosed 3D printed tubes anywhere. For reference, your average-sized speck of dust is 50 micrometers wide.

They then built a parallel network of four of these tubes, side-by-side, and ran a combination of two non-mixing fluids (like oil and water) through them. As the two fluids fought to get out through the openings, they squeezed off tiny droplets. Each of these droplets acted as a micro-scale in which materials were mixed and nanoparticles were generated. Each microfluidic tube can create millions of identical droplets that perform the same reaction.

This sort of system has been envisioned in the past, but its hasn’t been able to be scaled up because the parallel structure meant that if one tube got jammed, it would cause a ripple effect of changing pressures along its neighbors, knocking out the entire system. Think of it like losing a single Christmas light in one of the old-style strands – lose one, and you lose them all.

Brutchey and Malmstadt bypassed this problem by altering the geometry of the tubes themselves, shaping the junction between the tubes such that the particles come out a uniform size and the system is immune to pressure changes.

Malmstadt and Brutchy collaborated with Malancha Gupta of USC Viterbi and USC graduate students Carson Riche and Emily Roberts.

Explore further: Researchers develop a path to liquid solar cells that can be printed onto surfaces

More information: Carson T. Riche et al. Flow invariant droplet formation for stable parallel microreactors, Nature Communications (2016). DOI: 10.1038/ncomms10780

QDot Solids 022616 quantumdotsoJust as the single-crystal silicon wafer forever changed the nature of communication 60 years ago, a group of Cornell researchers is hoping its work with quantum dot solids – crystals made out of crystals – can help usher in a new era in electronics.

The team, led by Tobias Hanrath, associate professor in the Robert Frederick Smith School of Chemical and Biomolecular Engineering, and graduate student Kevin Whitham, has fashioned two-dimensional superstructures out of single-crystal building blocks. Through a pair of chemical processes, the lead-selenium nanocrystals are synthesized into larger crystals, then fused together to form atomically coherent square superlattices.

The difference between these and previous crystalline structures is the atomic coherence of each 5-nanometer crystal (a nanometer is one-billionth of a meter). They’re not connected by a substance between each crystal – they’re connected to each other. The electrical properties of these superstructures potentially are superior to existing semiconductor nanocrystals, with anticipated applications in energy absorption and light emission.

“As far as level of perfection, in terms of making the building blocks and connecting them into these superstructures, that is probably as far as you can push it,” Hanrath said, referring to the atomic-scale precision of the process.

Watch Video: “Assembling Quantum Dots Into Superlattices”

Associate professor Tobias Hanrath explains his group’s work on assembling quantum dots into ordered, two-dimensional superlattices, the subject of a paper published Feb. 22 in Nature Materials. The work has potential applications in optoelectronics. Credit: Cornell University

QDot Solids 022616 quantumdotso

The Hanrath group’s paper, “Charge transport and localization in atomically coherent quantum dot solids,” is published in this month’s issue of Nature Materials.

This latest work has grown out of previous published research by the Hanrath group, including a 2013 paper published in Nano Letters that reported a new approach to connecting through controlled displacement of a connector molecule, called a ligand. That paper referred to “connecting the dots” – i.e. electronically coupling each quantum dot – as being one of the most persistent hurdles to be overcome.

That barrier seems to have been cleared with this new research. The strong coupling of the nanocrystals leads to formation of energy bands that can be manipulated based on the crystals’ makeup, and could be the first step toward discovering and developing other artificial materials with controllable electronic structure.

Still, Whitham said, more work must be done to bring the group’s work from the lab to society. The structure of the Hanrath group’s superlattice, while superior to ligand-connected nanocrystal solids, still has multiple sources of disorder due to the fact that all nanocrystals are not identical. This creates defects, which limit electron wave function.

“I see this paper as sort of a challenge for other researchers to take this to another level,” Whitham said. “This is as far as we know how to push it now, but if someone were to come up with some technology, some chemistry, to provide another leap forward, this is sort of challenging other people to say, ‘How can we do this better?'”

Hanrath said the discovery can be viewed in one of two ways, depending on whether you see the glass as half empty or half full.

“It’s the equivalent of saying, ‘Now we’ve made a really large single-crystal wafer of silicon, and you can do good things with it,'” he said, referencing the game-changing communications discovery of the 1950s. “That’s the good part, but the potentially bad part of it is, we now have a better understanding that if you wanted to improve on our results, those challenges are going to be really, really difficult.”

Explore further: Nanocrystal infrared LEDs can be made cheaply

More information: Kevin Whitham et al. Charge transport and localization in atomically coherent quantum dot solids, Nature Materials (2016). DOI: 10.1038/nmat4576

Invisibility cloaks, bulletproof suits and cancer cures, we enter the minuscule world of nanotechnology with these 10 awesome facts.

 Nanotech 022316 membrane_big_cmykNanotechnology and Nanoscience

 

 

It’s hard to imagine just how small nanotechnology is. One nanometer is a billionth of a meter, or 10-9 of a meter. Here are a few illustrative examples:

  • There are 25,400,000 nanometers in an inch
  • A sheet of newspaper is about 100,000 nanometers thick
  • On a comparative scale, if a marble were a nanometer, then one meter would be the size of the Earth

Nanoscience and nanotechnology involve the ability to see and to control individual atoms and molecules. Everything on Earth is made up of atoms—the food we eat, the clothes we wear, the buildings and houses we live in, and our own bodies. (Watch the Video Below)

But something as small as an atom is impossible to see with the naked eye. In fact, it’s impossible to see with the microscopes typically used in a high school science classes. The microscopes needed to see things at the nanoscale were invented relatively recently—about 30 years ago.

Once scientists had the right tools, such as the scanning tunneling microscope (STM) and the atomic force microscope (AFM), the age of nanotechnology was born.

Although modern nanoscience and nanotechnology are quite new, nanoscale materials were used for centuries. Alternate-sized gold and silver particles created colors in the stained glass windows of medieval churches hundreds of years ago. The artists back then just didn’t know that the process they used to create these beautiful works of art actually led to changes in the composition of the materials they were working with.

Today’s scientists and engineers are finding a wide variety of ways to deliberately make materials at the nanoscale to take advantage of their enhanced properties such as higher strength, lighter weight, increased control of light spectrum, and greater chemical reactivity than their larger-scale counterparts.

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Genesis Nanotechnology, Inc. ~ “Great Things from Small Things”

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UC Santa Cruz 022316 9-researchersuYat Li (left) and Tianyu Liu worked with researchers at Lawrence Livermore National Laboratory to develop supercapacitors using 3D-printed graphene aerogel electrodes. Credit: T. Stephens
Scientists at UC Santa Cruz and Lawrence Livermore National Laboratory (LLNL) have reported the first example of ultrafast 3D-printed graphene supercapacitor electrodes that outperform comparable electrodes made via traditional methods. Their results open the door to novel, unconstrained designs of highly efficient energy storage systems for smartphones, wearables, implantable devices, electric cars and wireless sensors.

Using a 3D-printing process called direct-ink writing and a graphene-oxide composite ink, the team was able to print micro-architected electrodes and build supercapacitors with excellent performance characteristics. The results were published online January 20 in the journal Nano Letters and will be featured on the cover of the March issue of the journal.

“Supercapacitor devices using our 3D-printed graphene electrodes with thicknesses on the order of millimeters exhibit outstanding capacitance retention and power densities,” said corresponding author Yat Li, associate professor of chemistry at UC Santa Cruz. “This performance greatly exceeds the performance of conventional devices with thick electrodes, and it equals or exceeds the performance of reported devices made with electrodes 10 to 100 times thinner.”

LLNL engineer Cheng Zhu and UCSC graduate student Tianyu Liu are lead authors of the paper. “This breaks through the limitations of what 2D manufacturing can do,” Zhu said. “We can fabricate a large range of 3D architectures. In a phone, for instance, you would only need to leave a small area for energy storage. The geometry can be very complex.”

Fast charging

Supercapacitors also can charge incredibly fast, Zhu said, in theory requiring just a few minutes or seconds to reach full capacity. In the future, the researchers believe newly designed 3D-printed supercapacitors will be used to create unique electronics that are currently difficult or even impossible to make using other synthetic methods, including fully customized smartphones and paper-based or foldable devices, while at the same time achieving unprecedented levels of performance.

According to Li, several key breakthroughs made these novel devices possible, starting with the development of a printable graphene-based ink. Modification of the 3D printing scheme to be compatible with aerogel processing made it possible to maintain the important mechanical and electrical properties of single graphene sheets in the 3D-printed structures. Finally, the use of 3D printing to intelligently engineer periodic macropores into the graphene electrode significantly enhances mass transport, allowing the to support much faster charge/discharge rates without degrading its capacity.

“This work provides an example of how 3D-printed materials such as graphene aerogels can significantly expand the design space for fabricating high-performance and fully integrable devices optimized for a broad range of applications,” Li said.

The advantages of graphene-based inks include their ultrahigh surface area, lightweight properties, elasticity, and superior electrical conductivity. The graphene composite aerogel supercapacitors are also extremely stable, the researchers reported, capable of nearly fully retaining their energy capacity after 10,000 consecutive charging and discharging cycles.

“Graphene is a really incredible material because it is essentially a single atomic layer that can be created from graphite. Because of its structure and crystalline arrangement, it has really phenomenal capabilities,” said LLNL materials engineer Eric Duoss.

Over the next year, the researchers intend to expand the technology by developing new 3D designs, using different inks, and improving the performance of existing materials.

Explore further: Energy storage of the future

More information: Cheng Zhu et al. Supercapacitors Based on Three-Dimensional Hierarchical Graphene Aerogels with Periodic Macropores, Nano Letters (2016). DOI: 10.1021/acs.nanolett.5b04965

collage of green nature landscape with planet Earth above it

A ‘Green-er’ Clean Energy Earth?

In the latest edition of their annual letter published today, Bill and Melinda Gates argue that the world needs “an energy miracle,” and are willing to bet that such a breakthrough will arrive within 15 years.

 

Bill Gates cites scientists’ estimates that to avoid the worst effects of climate change the biggest carbon-emitting countries must reduce greenhouse gas emissions by 80% by 2050, and the world must more or less stop such emissions entirely by 2100. And that’s not going to happen if we continue on our current trajectory.

You can see Gates explain the equation in the Quartz video above.

Gates says he was stunned to discover how little research and development money is going toward breakthroughs in cheaper, scaleable clean-energy sources.Gates announced last year that he was committing $1 billion of his own money over five years to invest in clean-energy technology, and has been pushing governments to increase their funding.

To explain the need for a breakthrough in energy technology, he uses an equation (similar to the Kaya identity equation) that represents the factors determining how much carbon dioxide the world emits every year.

“Within the next 15 years, I expect the world will discover a clean-energy breakthrough that will save our planet and power our world.” Gates believes that cleaner options such as electric cars and LED lighting won’t bring down energy consumption enough to hit those climate-change goals. In fact, he doesn’t see any current clean-energy technology that will enable the world to eliminate carbon dioxide emissions by 2100, partly because it’s not consistent or inexpensive enough.

 

Gates has personally invested in next-generation nuclear power technology, which he describes as “a very promising path.” He is also backing efforts to improve battery technology, so that energy from intermittent clean sources such as solar and wind can be stored affordably at large scale for use over time. “I think we need to pursue many different paths,” says Gates in an interview with Quartz.

 

And he’s betting on relatively fast progress. “Within the next 15 years,” Gates predicts in his letter, “I expect the world will discover a clean-energy breakthrough that will save our planet and power our world.”

** Re-Posted from the World Economic Forum

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gold-panningInstead of a pan and a pick ax, prospectors of the future might seek gold with a hand-held biosensor that uses a component of DNA to detect traces of the element in water.

The gold sensor is the latest in a series of metal-detecting biosensors under development by Rebecca Lai, an associate professor of chemistry at the University of Nebraska-Lincoln. Other sensors at various stages of development detect mercury, silver or platinum. Similar technology could be used to find cadmium, lead, arsenic, or other metals and metalloids.

A primary purpose for the sensors would be to detect water contaminants, Lai said. She cited the August 2015 blowout of a gold mine near Silverton, Colorado, which spilled chemicals into nearby rivers, as well as the ongoing problems with lead-tainted water supplies in Flint, Michigan.

Gold NEB 021816 rd1602_gold

The photo shows the gold biosensor developed by Rebecca Lai, associate professor of chemistry at the University of Nebraska-Lincoln. The center diagram illustrates how gold ions connect two strands of adenine and hinder electron transmission. The right diagram shows the effect on current signaling the presence of gold. Source: Rebecca Lai/University of Nebraska-Lincoln

Fabricated on paper strips about the size of a litmus strip, Lai’s sensors are designed to be inexpensive, portable and reusable. Instead of sending water samples away for time-consuming tests, people might someday use the biosensors to routinely monitor household water supplies for lead, mercury, arsenic or other dangerous contaminants.

But Lai also is among scientists searching for new and better ways to find gold. Not only aesthetically appealing and financially valuable, the precious metal is in growing demand for pharmaceutical and scientific purposes, including anti-cancer agents and drugs fighting tuberculosis and rheumatoid arthritis.

“Geochemical exploration for gold is becoming increasingly important to the mining industry,” Lai said. “There is a need for developing sensitive, selective and cost-effective analytical methods capable of identifying and quantifying gold in complex biological and environmental samples.”

Scientists have employed several strategies to find gold, such as fluorescence-based sensors, nanomaterials and even a whole cell biosensor that uses transgenic E. coli. Lai was a co-author of a 2013 study that explored the use of E. coli as a gold biosensor.

DNA, the carrier of genetic information in nearly all living organisms, might seem an unlikely method to detect gold and other metals. Lai’s research, however, exploits long-observed interactions between metal ions and the four basic building blocks of DNA: adenine, cytosine, guanine and thymine.

Different metal ions have affinities with the different DNA bases. The gold sensor, for example, is based on gold ions’ interactions with adenine. A mercury sensor is based upon mercury ions’ interaction with thymine. A silver sensor would be based upon silver ions’ interaction with cytosine.

NUtech Ventures, UNL’s affiliate for technology commercialization, is pursuing patent protection and seeking licensing partners for Lai’s metal ion sensors. She applied for a patent for the sensors in 2014.

“Although these interactions have been well-studied, they have not been exploited for use in electrochemical metal ion sensing,” Lai and doctoral student Yao Wu said in a recent Analytical Chemistry article describing the gold sensor.

Lai and Wu say their article is the first report of how oligoadenines — short adenine chains — can be used in the design and fabrication of this class of electrochemical biosensors, which would be able to measure concentrations of a target metal in a water sample as well as its presence.

The DNA-based sensor detects Au(III), a gold ion that originates from the dissolution of metallic gold. The mercury and silver sensors also detect dissolved mercury and silver ions.

“The detected Au(III) has to come from metallic gold, so if gold is found in a water supply, a gold deposit is somewhere nearby,” Lai explained.

The DNA-based biosensors need more refinement before they can be made commercially available, she said.

Lai’s sensor works by measuring electric current passing from an electrode to a tracer molecule, methylene blue in this case. In the absence of Au(III), the observed current is high because the oligoadenine probes are highly flexible and the electron transfer between the electrode and the tracer molecule is efficient.

But upon binding to Au(III) in the sample, the flexibility of the oligoadenine DNA probes is hindered, resulting in a large reduction in the current from the tracer molecule. The extent of the change in current is used to determine the concentration of AU(III) in the sample.

To allow the sensor to be reused multiple times, the Au(III) is later removed from the sensor with an application of another ligand.

Lai’s research focus is on electrochemical ion sensors. Her research has been supported with grants from the National Institutes of Health and the National Science Foundation.

Source: Univ. of Nebraska – Lincoln 

Cancer shapeshiftin
Professor Warren Chan (IBBME, ChemE, MSE) has spent the last decade figuring out how to deliver chemotherapy drugs into tumours — and nowhere else. Now his lab has designed a set of nanoparticles attached to strands of DNA that can change …more

Chemotherapy isn’t supposed to make your hair fall out—it’s supposed to kill cancer cells. A new molecular delivery system created at U of T could help ensure that chemotherapy drugs get to their target while minimizing collateral damage.

Many target fast-growing cells. Injected into a patient, they swirl around in the bloodstream acting on fast-growing cells wherever they find them. That includes tumours, but unfortunately also hair follicles, the lining of your digestive system, and your skin.

Professor Warren Chan (IBBME, ChemE, MSE) has spent the last decade figuring out how to deliver into tumours—and nowhere else. Now his lab has designed a set of nanoparticles attached to strands of DNA that can change shape to gain access to diseased tissue.

“Your body is basically a series of compartments,” says Chan. “Think of it as a giant house with rooms inside. We’re trying to figure out how to get something that’s outside, into one specific room. One has to develop a map and a system that can move through the house where each path to the final room may have different restrictions such as height and width.”

One thing we know about : no two tumours are identical. Early-stage breast cancer, for example, may react differently to a given treatment than pancreatic cancer, or even breast cancer at a more advanced stage. Which particles can get inside which tumours depends on multiple factors such as the particle’s size, shape and surface chemistry.

Chan and his research group have studied how these factors dictate the delivery of small molecules and nanotechnologies to tumours, and have now designed a targeted molecular delivery system that uses modular nanoparticles whose shape, size and chemistry can be altered by the presence of specific DNA sequences.

“We’re making shape-changing nanoparticles,” says Chan. “They’re a series of building blocks, kind of like a LEGO set.” The component pieces can be built into many shapes, with binding sites exposed or hidden. They are designed to respond to biological molecules by changing shape, like a key fitting into a lock.

These shape-shifters are made of minuscule chunks of metal with strands of DNA attached to them. Chan envisions that the nanoparticles will float around harmlessly in the blood stream, until a DNA strand binds to a sequence of DNA known to be a marker for cancer. When this happens, the particle changes shape, then carries out its function: it can target the , expose a drug molecule to the cancerous cell, tag the cancerous cells with a signal molecule, or whatever task Chan’s team has designed the nanoparticle to carry out.

Their work was published this week in two key studies in the Proceedings of the National Academy of Sciences and the leading journal Science.

“We were inspired by the ability of proteins to alter their conformation—they somehow figure out how to alleviate all these delivery issues inside the body,” says Chan. “Using this idea, we thought, ‘Can we engineer a nanoparticle to function like a protein, but one that can be programmed outside the body with medical capabilities?'”

Applying nanotechnology and materials science to medicine, and particularly to targeted drug delivery, is still a relatively new concept, but one Chan sees as full of promise. The real problem is how to deliver enough of the nanoparticles directly to the cancer to produce an effective treatment.

“Here’s how we look at these problems: it’s like you’re going to Vancouver from Toronto, but no one tells you how to get there, no one gives you a map, or a plane ticket, or a car—that’s where we are in this field,” he says. “The idea of targeting drugs to tumours is like figuring out how to go to Vancouver. It’s a simple concept, but to get there isn’t simple if not enough information is provided.”

“We’ve only scratched the surface of how nanotechnology ‘delivery’ works in the body, so now we’re continuing to explore different details of why and how tumours and other organs allow or block certain things from getting in,” adds Chan.

He and his group plan to apply the they’ve designed toward personalized nanomedicine—further tailoring their particles to deliver drugs to your precise type of, and nowhere else.

Explore further: Cylindrical nanoparticles more deadly to breast cancer

More information: Edward A. Sykes et al. Tailoring nanoparticle designs to target cancer based on tumor pathophysiology, Proceedings of the National Academy of Sciences(2016). DOI: 10.1073/pnas.1521265113

Floating Solar kagoshima-nanatsujima-plant-similar-to-japans-current-solar-project

The World’s Largest Floating Solar Farm

Say “hello” to a truly sustainable future. Japan has started construction on, what will be, the largest floating solar farm on our planet.

Japan Just Started Work on The World’s Largest Floating Solar Farm

Graphene Super Conductivity 021816 160216090342_1_540x360
Crystal structure of Ca-intercalated bilayer graphene fabricated on SiC substrate. Insertion of Ca atoms between two graphene layers causes the superconductivity.
Credit: Copyright Tohoku University

Graphene is a single-atomic carbon sheet with a hexagonal honeycomb network. Electrons in graphene take a special electronic state called Dirac-cone where they behave as if they have no mass. This allows them to flow at very high speed, giving graphene a very high level of electrical conductivity.

This is significant because electrons with no mass flowing with no resistance in graphene could lead to the realization of an ultimately high-speed nano electronic device.

The collaborative team of Tohoku University and the University of Tokyo has developed a method to grow high-quality graphene on a silicon carbide (SiC) crystal by controlling the number of graphene sheets. The team fabricated bilayer graphene with this method and then inserted calcium (Ca) atoms between the two graphene layers like a sandwich.

They measured the electrical conductivity with the micro four-point probe method and found that the electrical resistivity rapidly drops at around 4 K (-269 °C), indicative of an emergence of superconductivity.

The team also found that neither genuine bilayer graphene nor lithium-intercalated bilayer graphene shows superconductivity, indicating that the superconductivity is driven by the electron transfer from Ca atoms to graphene sheets.

The success in fabricating superconducting graphene is expected to greatly impact both the basic and applied researches of graphene.

It is currently not clear what phenomenon takes place when the Dirac electrons with no mass become superconductive with no resistance. But based on the latest study results, further experimental and theoretical investigations would help to unravel the properties of superconducting graphene.

The superconducting transition temperature (Tc) observed in this study on Ca-intercalated bilayer graphene is still low (4 K). This prompts further studies into ways to increase Tc, for example, by replacing Ca with other metals and alloys, or changing the number of graphene sheets.

From the application point of view, the latest results pave the way for the further development of ultrahigh-speed superconducting nano devices such as a quantum computing device, which utilizes superconducting graphene in its integrated circuit.


Story Source:

The above post is reprinted from materials provided by Tohoku University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Satoru Ichinokura, Katsuaki Sugawara, Akari Takayama, Takashi Takahashi, Shuji Hasegawa. Superconducting Calcium-Intercalated Bilayer Graphene. ACS Nano, 2016; DOI: 10.1021/acsnano.5b07848

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