It’s ALL in Our Heads ~ Studying the Consciousness to Better Understand …


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The physical brain and the conceptual mind are linked in ways that we don’t fully understand. A new collaboration is getting us closer.

How does the brain give rise to the mind? This question lies at the interface between philosophy and biology. Researchers are starting to zero in on how brain activity translates into consciousness and how we experience the world around us. The results have broad implications for cognition, brain health, human nature, and artificial intelligence.

The Azrieli Program in Brain, Mind & Consciousness is a collaboration started by the Canadian Institute for Advanced Research, bringing together a team of neuroscientists to answer these big questions.

Watch the Video

 

 

But how is it possible to probe something like consciousness? Professors Adrian Owen, Melvyn Goodale, and Lisa Saksida are all fellows of the Azrieli Program working at Western University, and they look at brain activity at the boundaries between health and dysfunction.

Owen studies patients who are losing consciousness. Communicating with patients who will soon be in a vegetative state, Owen takes functional magnetic resonance imaging (fMRI) scans to observe transitions in the brain as they lose awareness, allowing a better understanding what types of brain activity are preserved or lost.

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Along similar lines, Goodale looks at how brain damage impacts cognition, memory, sensory processing, and motor control. These insights illuminate how the brain solves problems and controls complex movement, which have implications not only in health, but also in computer science and artificial intelligence, says Goodale.

Saksida wants to understand how brain circuits are altered in Alzheimer’s Disease. Drug treatment for Alzheimer’s only treats symptoms. There is still no proven therapy that stops or reverses progression of Alzheimer’s. Saksida believes the key to effective treatments is to better understand the brain circuits involved so that they can be targeted to improve cognition.

While the mind remains a bit of a mystery, these studies are working to fill in the gaps. This understanding allows researchers to better understand how the mind emerges, how it can be damaged, and perhaps one day, how it can be imitated or repaired.

NASA & MIT Collaborate to develop space-based quantum-dot spectrometer ~ Quantum Dots in Space “simplifying instrument integration.”


A NASA technologist has teamed with the inventor of a new nanotechnology that could transform the way space scientists build spectrometers, the all-important device used by virtually all scientific disciplines to measure the properties of light emanating from astronomical objects, including Earth itself.

Mahmooda Sultana, a research engineer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, now is collaborating with Moungi Bawendi, a chemistry professor at the Cambridge-based Massachusetts Institute of Technology, or MIT, to develop a prototype imaging spectrometer based on the emerging quantum-dot technology that Bawendi’s group pioneered. NASA’s Center Innovation Fund, which supports potentially trailblazing, high-risk technologies, is funding the effort.

Introducing Quantum Dots

Quantum dots are a type of semiconductor nanocrystal discovered in the early 1980s. Invisible to the naked eye, the dots have proven in testing to absorb different wavelengths of light depending on their size, shape, and chemical composition. The technology is promising to applications that rely on the analysis of light, including smartphone cameras, medical devices, and environmental-testing equipment.

“This is as novel as it gets,” Sultana said, referring to the technology that she believes could miniaturize and potentially revolutionize space-based spectrometers, particularly those used on uninhabited aerial vehicles and small satellites. “It really could simplify instrument integration.”

Absorption spectrometers, as their name implies, measure the absorption of light as a function of frequency or wavelength due to its interaction with a sample, such as atmospheric gases.

After passing through or interacting with the sample, the light reaches the spectrometer. Traditional spectrometers use gratings, prisms, or interference filters to split the light into its component wavelengths, which their detector pixels then detect to produce spectra. The more intense the absorption in the spectra, the greater the presence of a specific chemical.

While space-based spectrometers are getting smaller due to miniaturization, they still are relatively large, Sultana said. “Higher-spectral resolution requires long optical paths for instruments that use gratings and prisms. This often results in large instruments. Whereas here, with quantum dots that act like filters that absorb different wavelengths depending on their size and shape, we can make an ultra-compact instrument. In other words, you could eliminate optical parts, like gratings, prisms, and interference filters.”

Just as important, the technology allows the instrument developer to generate nearly an unlimited number of different dots. As their size decreases, the wavelength of the light that the quantum dots will absorb decreases. “This makes it possible to produce a continuously tunable, yet distinct, set of absorptive filters where each pixel is made of a quantum dot of a specific size, shape, or composition. We would have precise control over what each dot absorbs. We could literally customize the instrument to observe many different bands with high-spectral resolution.”

Prototype Instrument Under Development

nasa-symbolWith her NASA technology-development support, Sultana is working to develop, qualify through thermal vacuum and vibration tests, and demonstrate a 20-by-20 quantum-dot array sensitive to visible wavelengths needed to image the sun and the aurora. However, the technology easily can be expanded to cover a broader range of wavelengths, from ultraviolet to mid-infrared, which may find many potential space applications in Earth science, heliophysics, and planetary science, she said.

Under the collaboration, Sultana is developing an instrument concept particularly for a CubeSat application and MIT doctoral student Jason Yoo is investigating techniques for synthesizing different precursor chemicals to create the dots and then printing them onto a suitable substrate. “Ultimately, we would want to print the dots directly onto the detector pixels,” she said.

“This is a very innovative technology,” Sultana added, conceding that it is very early in its development. “But we’re trying to raise its technology-readiness level very quickly. Several space-science opportunities that could benefit are in the pipeline.”

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UC Berkeley: Magnetic nano-particle imaging Research May Lead to Early Cancer Detection


 

Magnetic particle imaging is a new, up-and-coming, safe and highly sensitive tracer imaging technique that works by detecting super-para-magnetic iron oxide nano-particles with high image contrast (that is, no background tissue signal). The technique, which does not use any ionizing radiation, can be used to image anywhere inside the body, which means that it could be promising for detecting and monitoring tumors. Researchers in the US are now the first to have used MPI to passively detect cancer by basically exploiting the abnormal leakiness of tumor blood vessels – a finding that bodes well for the early detection of cancers like breast cancer in patients at risk for the disease.

Biomedical imaging is important at every stage of diagnosing and treating cancer, beginning with initial screening, through to diagnosis, treatment planning and monitoring. The biggest challenge here is to be able to reliably distinguish tumour tissue from healthy tissue, something that is not as easy as it sounds.

“Conventional anatomical techniques, such as X-ray, X-ray computed tomography (CT), ultrasound and magnetic resonance imaging (MRI), are very useful for detecting the tissue architecture changes that generally accompany cancer, but the native contrast of tumours may not differ sufficiently from healthy tissue for a confident diagnosis, especially for metastatic or so-called diffuse tumours” explains lead author of the study Elaine Yu, who is completing her Bioengineering PhD in Steven Conolly’s lab at the University of California at Berkeley (UCB). “This is why exogenous contrast agents, such as iodine (for X-ray and CT) and gadolinium (for MRI) are often administered to highlight crucial vascular differences between normal and cancerous tissue for more precise screening.”

Exploiting the EPR effect

Contrast agents are all injected intravenously, but the way they highlight tumours differs considerably. Nanosized agents are better than conventional low molecular weight agents in one respect because they are not immediately excreted by the kidneys if designed to be large enough. They are thus able to circulate in the blood for extended periods of time. The naturally leaky vasculature of some tumours also allows nanosized particles to preferentially end up in tumour tissue, where they can be held. This is known as the enhanced permeability and retention (EPR) effect.

“Our work is the first to exploit the EPR effect with the high sensitivity and contrast afforded by magnetic particle imaging (MPI),” says Yu. “We have succeeded in imaging tumours in rats with vivid tumour-to-background contrast. “Thanks to its high sensitivity and good signal throughout the entire body, we were able to clearly capture the nanoparticle dynamics in the tumour: so-called rim enhancement, peak particle uptake at six hours after administration and eventual clearance beyond 48 hours.”

Synthesizing the SPIOscancer-shapeshiftin

The MPI-tailored superparamagnetic iron oxide nanoparticle (SPIO) tracers were synthesized by team members at LodeSpin Labs and by Kannan Krishnan’s lab at the University of Washington (UW), and were designed for optimal imaging resolution and long blood circulation time. “The iron oxide nanoparticles were made by thermolysis of iron III oleate in 1-octadcene, with subsequent oxidation to achieve the desired magnetic behaviour and coated with the biocompatible coating MPAO-PEG,” explains Yu.

The researchers injected the nanoparticles into the tail veins of rats and then performed a series of MPI scans as the nanoparticles travelled through the circulation. Thanks to the EPR effect, the particles preferentially accumulated in tumours and were retained there for up to six days.

Imaging the SPIO electronic moment

MPI was first developed by Philips Research in 2005 and is a tracer imaging technique that directly measures the location and concentration of SPIO nanoparticles in vivo. It images the SPIO electronic moment, which is 22 million times more intense than nuclear MRI moments. When a time-varying exciting field is applied, it causes the moments of the SPIOs to instantaneously “flip”, thereby inducing a signal in a receiver coil.

“The advantages of MPI are its superb contrast and sensitivity, which could very soon rival the dose-limited sensitivity of nuclear medicine techniques,” Conolly tells nanotechweb.org. “This is very exciting, since MPI does not rely on ionizing radiation. The scanner and iron oxide tracer are also thought to be safe for humans. Indeed, some SPIO agents are already FDA or EU safety approved for human use in other clinical applications.”

MPI tracers are excreted through the liver

Importantly, the MPI tracers are excreted through the liver, rather than through the kidneys, and there is evidence that SPIOs could be safer than iodine and gadolinium for patients with chronic kidney disease. “Given all these advantages, we are very hopeful that MPI could play an important role in early-stage cancer detection. Indeed, we are particularly focusing on early-stage breast cancer detection in the subpopulation of women with radiologically dense breast tissue and who are at high risk for cancer (because of, for example, BRCA1 or BRCA2 defects, or family history of the disease).”

Conolly says that he and his colleagues are now working hard to improve MPI in terms of resolution and sensitivity. “We are also studying MPI for stem-cell tracking, detecting pulmonary embolism, brain perfusion to detect and monitor strokes or traumatic brain injuries, and T-cell immunotherapy studies in collaboration with researchers at Berkeley, the University of California at San Francisco, UW, Case Western, Harvard and Stanford. We would also like to follow up on several promising demonstrations of MPI-guided magnetic fluid hyperthermia exploiting the unique ‘focusing’ capabilities of MPI to selectively heat tumours or to release chemotherapeutic agents specifically into a tumour. We are doing this work with University of Florida collaborators.”

The new MPI cancer imaging study is described in Nano Letters DOI: 10.1021/acs.nanolett.6b04865.

“Your Heart (Organ) on-a-chip” ~ mimics heart’s biomechanical properties (w/video)


Posted: Feb 23, 2017



The human heart beats more than 2.5 billion times in an average lifetime. Now scientists at Vanderbilt University have created a three-dimensional organ-on-a-chip that can mimic the heart’s amazing biomechanical properties.

“We created the I-Wire Heart-on-a-Chip so that we can understand why cardiac cells behave the way they do by asking the cells questions, instead of just watching them,” said Gordon A. Cain University Professor John Wikswo, who heads up the project. 

“We believe it could prove invaluable in studying cardiac diseases, drug screening and drug development, and, in the future, in personalized medicine by identifying the cells taken from patients that can be used to patch damaged hearts effectively.”

The device and the results of initial experiments demonstrating that it faithfully reproduces the response of cardiac cells to two different drugs that affect heart function in humans are described in an article published last month in the journal Acta Biomaterialia ~

(“I-Wire Heart-on-a-Chip I: Three-dimensional cardiac tissue constructs for physiology and pharmacology”). 

A companion article in the same issue presents a biomechanical analysis of the I-Wire platform that can be used for characterizing biomaterials for cardiac regenerative medicine.


I-Wire device with cardiac fiber shown in magnification window. (Image: VIIBRE / Vanderbilt)

The unique aspect of the new device, which represents about two millionths of a human heart, is that it controls the mechanical force applied to cardiac cells. 

This allows the researchers to reproduce the mechanical conditions of the living heart, which is continually stretching and contracting, in addition to its electrical and biochemical environment.

“Heart tissue, along with muscle, skeletal and vascular tissue, represents a special class of mechanically active biomaterials,” said Wikswo. “Mechanical activity is an intrinsic property of these tissues so you can’t fully understand how they function and how they fail without taking this factor into account.”

“Currently, we don’t have many models for studying how the heart responds to stress. Without them, it is very difficult to develop new drugs that specifically address what goes wrong in these conditions,” commented Charles Hong, associate professor of cardiovascular medicine at Vanderbilt’s School of Medicine, who didn’t participate in the research but is familiar with it. 

“This provides us with a really amazing model for studying how hearts fail.”

The I-Wire device consists of a thin thread of human cardiac cells 0.014 inches thick (about the size of 20-pound monofilament fishing line) stretched between two perpendicular wire anchors. 

The amount of tension on the fiber can be varied by moving the anchors in and out, and the tension is measured with a flexible probe that pushes against the side of the fiber.

The fiber is supported by wires and a frame in an optically clear well that is filled with liquid medium like that which surrounds cardiac cells in the body. The apparatus is mounted on the stage of a powerful optical microscope that records the fiber’s physical changes. 
The microscope also acts as a spectroscope that can provide information about the chemical changes taking place in the fiber. 
A floating microelectrode also measures the cells’ electrical activity.

According to the researchers, the I-Wire system can be used to characterize how cardiac cells respond to electrical stimulation and mechanical loads and can be implemented at low cost, small size and low fluid volumes, which make it suitable for screening drugs and toxins. Because of its potential applications, Vanderbilt University has patented the device.

Video taken through a microscope shows I-Wire heart fiber. left, beating at different frequencies. The black circle, right, is the flexible cantilever that measures the force of the fiber’s contractions. (Veniamin Sidorov / VIIBRE /Vanderbilt)

Unlike other heart-on-a-chip designs, I-Wire allows the researchers to grow cardiac cells under controlled, time-varying tension similar to what they experience in living hearts. 

As a consequence, the heart cells in the fiber align themselves in alternating dark and light bands, called sarcomeres, which are characteristic of human muscle tissue. The cardiac cells in most other heart-on-a-chip designs do not exhibit this natural organization.

In addition, the researchers have determined that their heart-on-a-chip obeys the Frank-Starling law of the heart. The law, which was discovered by two physiologists in 1918, describes the relationship between the volume of blood filling the heart and the force with which cardiac cells contract. The I-Wire is one of the first heart-on-a-chip devices to do so.

To demonstrate the I-Wire’s value in determining the effects that different drugs have on the heart, the scientists tested its response with two drugs known to affect heart function in humans: isoproterenol and blebbistatin. Isoproterenol is a medication used to treat bradycardia (slow heart rate) and heart block (obstruction of the heart’s natural pacemaker). Blebbistatin inhibits contractions in all types of muscle tissue, including the heart.

According to Veniamin Sidorov, the research assistant professor at the Vanderbilt Institute for Integrative Biosystems Research and Education (VIIBRE) who led its development, the device faithfully reproduces the response of cardiac cells in a living heart.

“Cardiac tissue has two basic elements: an active, contractile element and a passive, elastic element,” said Sidorov. “By separating these two elements with blebbistatin, we successfully characterized the elasticity of the artificial tissue. By exposing it to isoproterenol, we tested its response to adrenergic stimulation, which is one of the main systems responsible for regulation of heart contractions. 
We found that the relationship between these two elements in the cardiac fiber is consistent with that seen in natural tissue. 

This confirms that our heart-on-a-chip model provides us with a new way to study the elastic response of cardiac muscle, which is extremely complicated and is implicated in heart failure, hypertension, cardiac hypertrophy and cardiomyopathy.”

Source: Vanderbilt University

Light-driven reaction converts carbon dioxide into fuel ~ A potential boon to Alternative Energy 



Posted: Feb 23, 2017

Duke University researchers have developed tiny nanoparticles that help convert carbon dioxide into methane using only ultraviolet light as an energy source.




Having found a catalyst that can do this important chemistry using ultraviolet light, the team now hopes to develop a version that would run on natural sunlight, a potential boon to alternative energy.

Chemists have long sought an efficient, light-driven catalyst to power this reaction, which could help reduce the growing levels of carbon dioxide in our atmosphere by converting it into methane, a key building block for many types of fuels.

Not only are the rhodium nanoparticles made more efficient when illuminated by light, they have the advantage of strongly favoring the formation of methane rather than an equal mix of methane and undesirable side-products like carbon monoxide. This strong “selectivity” of the light-driven catalysis may also extend to other important chemical reactions, the researchers say.

“The fact that you can use light to influence a specific reaction pathway is very exciting,” said Jie Liu, the George B. Geller professor of chemistry at Duke University. “This discovery will really advance the understanding of catalysis.”

Rhodium Nanocube Swarm





Duke University researchers have engineered rhodium nanoparticles (blue) that can harness the energy in ultraviolet light and use it to catalyze the conversion of carbon dioxide to methane, a key building block for many types of fuels. (Image: Chad Scales)

The paper appears online Feb. 23 in Nature Communications (“Product selectivity in plasmonic photocatalysis for carbon dioxide hydrogenation”).

Despite being one of the rarest elements on Earth, rhodium plays a surprisingly important role in our everyday lives. Small amounts of the silvery grey metal are used to speed up or “catalyze” a number of key industrial processes, including those that make drugs, detergents and nitrogen fertilizer, and they even play a major role breaking down toxic pollutants in the catalytic converters of our cars.

Rhodium accelerates these reactions with an added boost of energy, which usually comes in the form of heat because it is easily produced and absorbed. However, high temperatures also cause problems, like shortened catalyst lifetimes and the unwanted synthesis of undesired products.

In the past two decades, scientists have explored new and useful ways that light can be used to add energy to bits of metal shrunk down to the nanoscale, a field called plasmonics.

“Effectively, plasmonic metal nanoparticles act like little antennas that absorb visible or ultraviolet light very efficiently and can do a number of things like generate strong electric fields,” said Henry Everitt, an adjunct professor of physics at Duke and senior research scientist at the Army’s Aviation and Missile RD&E Center at Redstone Arsenal, AL. “For the last few years there has been a recognition that this property might be applied to catalysis.”

Xiao Zhang, a graduate student in Jie Liu’s lab, synthesized rhodium nanocubes that were the optimal size for absorbing near-ultraviolet light. He then placed small amounts of the charcoal-colored nanoparticles into a reaction chamber and passed mixtures of carbon dioxide and hydrogen through the powdery material.

When Zhang heated the nanoparticles to 300 degrees Celsius, the reaction generated an equal mix of methane and carbon monoxide, a poisonous gas. When he turned off the heat and instead illuminated them with a high-powered ultraviolet LED lamp, Zhang was not only surprised to find that carbon dioxide and hydrogen reacted at room temperature, but that the reaction almost exclusively produced methane.

“We discovered that when we shine light on rhodium nanostructures, we can force the chemical reaction to go in one direction more than another,” Everitt said. “So we get to choose how the reaction goes with light in a way that we can’t do with heat.”

This selectivity — the ability to control the chemical reaction so that it generates the desired product with little or no side-products — is an important factor in determining the cost and feasibility of industrial-scale reactions, Zhang says.

“If the reaction has only 50 percent selectivity, then the cost will be double what it would be if the selectively is nearly 100 percent,” Zhang said. “And if the selectivity is very high, you can also save time and energy by not having to purify the product.”

Now the team plans to test whether their light-powered technique might drive other reactions that are currently catalyzed with heated rhodium metal. By tweaking the size of the rhodium nanoparticles, they also hope to develop a version of the catalyst that is powered by sunlight, creating a solar-powered reaction that could be integrated into renewable energy systems.

“Our discovery of the unique way light can efficiently, selectively influence catalysis came as a result of an on-going collaboration between experimentalists and theorists,” Liu said. “Professor Weitao Yang’s group in the Duke chemistry department provided critical theoretical insights that helped us understand what was happening. This sort of analysis can be applied to many important chemical reactions, and we have only just begun to explore this exciting new approach to catalysis.”

Source: Duke University

MIT: New ‘Solar Skin’ Solar panels get a face-lift with custom Display Capabilities


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Startup aims for wider U.S. solar adoption with photovoltaic panels that can display any image.

Founded at the MIT Sloan School of Management, Sistine Solar creates custom solar panels designed to mimic home facades and other environments, as well as display custom designs, with aims of enticing more homeowners to install photovoltaic systems. Courtesy of Sistine Solar

Residential solar power is on a sharp rise in the United States as photovoltaic systems become cheaper and more powerful for homeowners. A 2012 study by the U.S. Department of Energy (DOE) predicts that solar could reach 1 million to 3.8 million homes by 2020, a big leap from just 30,000 homes in 2006.

But that adoption rate could still use a boost, according to MIT spinout Sistine Solar. “If you look at the landscape today, less than 1 percent of U.S. households have gone solar, so it’s nowhere near mass adoption,” says co-founder Senthil Balasubramanian MBA ’13.

Founded at the MIT Sloan School of Management, Sistine creates custom solar panels designed to mimic home facades and other environments, with aims of enticing more homeowners to install photovoltaic systems.

Sistine’s novel technology, SolarSkin, is a layer that can be imprinted with any image and embedded into a solar panel without interfering with the panel’s efficacy. Homeowners can match their rooftop or a grassy lawn. Panels can also be fitted with business logos, advertisements, or even a country’s flag. SolarSkin systems cost about 10 percent more than traditional panel installations. But over the life of the system, a homeowner can still expect to save more than $30,000, according to the startup.

A winner of a 2013 MIT Clean Energy Prize, Sistine has recently garnered significant media attention as a rising “aesthetic solar” startup. Last summer, one of its pilot projects was featured on the Lifetime television series “Designing Spaces,” where the panels blended in with the shingle roof of a log cabin in Hubbardston, Massachusetts.

In December, the startup installed its first residential SolarSkin panels, in a 10-kilowatt system that matches a cedar pattern on a house in Norwell, Massachusetts. Now, the Cambridge-based startup says it has 200 homes seeking installations, primarily in Massachusetts and California, where solar is in high demand.

“We think SolarSkin is going to catch on like wildfire,” Balasubramanian says. “There is a tremendous desire by homeowners to cut utility bills, and solar is finding reception with them — and homeowners care a lot about aesthetics.”

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Captivating people with solar – Who Said Solar Can’t Be Beautiful?

SolarSkin is the product of the co-founders’ unique vision, combined with MIT talent that helped make the product a reality.

Balasubramanian came to MIT Sloan in 2011, after several years in the solar-power industry, with hopes of starting his own solar-power startup — a passion shared by classmate and Sistine co-founder Ido Salama MBA ’13.

One day, the two were brainstorming at the Muddy Charles Pub, when a surprisingly overlooked issue popped up: Homeowners, they heard, don’t really like the look of solar panels. That began a nebulous business mission to “captivate people’s imaginations and connect people on an emotional level with solar,” Balasubramanian says.

Recruiting Jonathan Mailoa, then a PhD student in MIT’s Photovoltaic Research Laboratory, and Samantha Holmes, a mosaic artist trained in Italy who is still with the startup, the four designed solar panels that could be embedded on massive sculptures and other 3-D objects. They took the idea to 15.366 (Energy Ventures), where “it was drilled into our heads that you have to do a lot of market testing before you build a product,” Balasubramanian says.

That was a good thing, too, he adds, because they realized their product wasn’t scalable. “We didn’t want to make a few installations that people talk about. … We [wanted to] make solar so prevalent that within our lifetime we can see the entire world convert to 100 percent clean energy,” Balasubramanian says.

The team’s focus then shifted to manufacturing solar panels that could match building facades or street fixtures such as bus shelters and information kiosks. In 2013, the idea earned the team — then officially Sistine Solar — a modest DOE grant and a $20,000 prize from the MIT Clean Energy Prize competition, “which was a game-changer for us,” Balasubramanian says.

But, while trying to construct custom-designed panels, another idea struck: Why not just make a layer to embed into existing solar panels? Recruiting MIT mechanical engineering student Jody Fu, Sistine created the first SolarSkin prototype in 2015, leading to pilot projects for Microsoft, Starwood Hotels, and other companies in the region.

That summer, after earning another DOE grant for $1 million, Sistine recruited Anthony Occidentale, an MIT mechanical engineering student who has since helped further advance SolarSkin. “We benefited from the incredible talent at MIT,” Balasubramanian says. “Anthony is a shining example of someone who resonates with our vision and has all the tools to make this a reality.”

Imagination is the limit

SolarSkin is a layer that employs selective light filtration to display an image while still transmitting light to the underlying solar cells. The ad wraps displayed on bus windows offer a good analogy: The wraps reflect some light to display an image, while allowing the remaining light through so passengers inside the bus can see out. SolarSkin achieves a similar effect — “but the innovation lies in using a minute amount of light to reflect an image [and preserve] a high-efficiency solar module,” Balasubramanian says.

To achieve this, Occidentale and others at Sistine have developed undisclosed innovations in color science and human visual perception. “We’ve come up with a process where we color-correct the minimal information we have of the image on the panels to make that image appear, to the human eye, to be similar to the surrounding backdrop of roof shingles,” Occidentale says.

As for designs, Sistine has amassed a database of common rooftop patterns in the United States, such as asphalt shingles, clay tiles, and slate, in a wide variety of colors. “So if a homeowner says, for instance, ‘We have manufactured shingles in a barkwood pattern,’ we have a matching design for that,” he says. Custom designs aren’t as popular, but test projects include commercial prints for major companies, and even Occidentale’s face on a panel.

Currently, Sistine is testing SolarSkin for efficiency, durability, and longevity at the U.S. National Renewable Energy Laboratory under a DOE grant.

The field of aesthetic solar is still nascent, but it’s growing, with major companies such as Tesla designing entire solar-panel roofs. But, as far as Balasubramanian knows, Sistine is the only company that’s made a layer that can be integrated into any solar panel, and that can display any color as well as intricate patterns and actual images.

Companies could thus use SolarSkin solar panels to double as business signs. Municipalities could install light-powering solar panels on highways that blend in with the surrounding nature. Panels with changeable advertisements could be placed on bus shelters to charge cell phones, information kiosks, and other devices. “You can start putting solar in places you typically didn’t think of before,” Balasubramanian says. “Imagination is really the only limit with this technology.”

Switched-on DNA: Sparking nano-electronic applications


DNA, the stuff of life, may very well also pack quite the jolt for engineers trying to advance the development of tiny, low-cost electronic devices. Credit: ASU

Switched-on DNA

DNA, the stuff of life, may very well also pack quite the jolt for engineers trying to advance the development of tiny, low-cost electronic devices.

Much like flipping your light switch at home—-only on a scale 1,000 times smaller than a human hair—-an ASU-led team has now developed the first controllable DNA switch to regulate the flow of electricity within a single, atomic-sized molecule. 

The new study, led by ASU Biodesign Institute researcher Nongjian Tao, was published in the advanced online journal Nature Communications.

“It has been established that charge transport is possible in DNA, but for a useful device, one wants to be able to turn the charge transport on and off. We achieved this goal by chemically modifying DNA,” said Tao, who directs the Biodesign Center for Bioelectronics and Biosensors and is a professor in the Fulton Schools of Engineering. 

“Not only that, but we can also adapt the modified DNA as a probe to measure reactions at the single-molecule level. This provides a unique way for studying important reactions implicated in disease, or photosynthesis reactions for novel renewable energy applications.”

Engineers often think of electricity like water, and the research team’s new DNA switch acts to control the flow of electrons on and off, just like water coming out of a faucet.

Previously, Tao’s research group had made several discoveries to understand and manipulate DNA to more finely tune the flow of electricity through it. They found they could make DNA behave in different ways—and could cajole electrons to flow like waves according to quantum mechanics, or “hop” like rabbits in the way electricity in a copper wire works —creating an exciting new avenue for DNA-based, nano-electronic applications.

Tao assembled a multidisciplinary team for the project, including ASU postdoctoral student Limin Xiang and Li Yueqi performing bench experiments, Julio Palma working on the theoretical framework, with further help and oversight from collaborators Vladimiro Mujica (ASU) and Mark Ratner (Northwestern University).

Tao’s group, modified just one of DNA’s iconic double helix chemical letters, abbreviated as A, C, T or G, with another chemical group, called anthraquinone (Aq). Anthraquinone is a three-ringed carbon structure that can be inserted in …more




To accomplish their engineering feat, Tao’s group, modified just one of DNA’s iconic double helix chemical letters, abbreviated as A, C, T or G, with another chemical group, called anthraquinone (Aq). Anthraquinone is a three-ringed carbon structure that can be inserted in between DNA base pairs but contains what chemists call a redox group (short for reduction, or gaining electrons or oxidation, losing electrons).
 

These chemical groups are also the foundation for how our bodies’ convert chemical energy through switches that send all of the electrical pulses in our brains, our hearts and communicate signals within every cell that may be implicated in the most prevalent diseases.

The modified Aq-DNA helix could now help it perform the switch, slipping comfortably in between the rungs that make up the ladder of the DNA helix, and bestowing it with a new found ability to reversibly gain or lose electrons.

Through their studies, when they sandwiched the DNA between a pair of electrodes, they careful controlled their electrical field and measured the ability of the modified DNA to conduct electricity. This was performed using a staple of nano-electronics, a scanning tunneling microscope, which acts like the tip of an electrode to complete a connection, being repeatedly pulled in and out of contact with the DNA molecules in the solution like a finger touching a water droplet.

“We found the electron transport mechanism in the present anthraquinone-DNA system favors electron “hopping” via anthraquinone and stacked DNA bases,” said Tao. In addition, they found they could reversibly control the conductance states to make the DNA switch on (high-conductance) or switch-off (low conductance). 

When anthraquinone has gained the most electrons (its most-reduced state), it is far more conductive, and the team finely mapped out a 3-D picture to account for how anthraquinone controlled the electrical state of the DNA.

For their next project, they hope to extend their studies to get one step closer toward making DNA nano-devices a reality.

“We are particularly excited that the engineered DNA provides a nice tool to examine redox reaction kinetics, and thermodynamics the single molecule level,” said Tao.

 Explore further: Scientists engineer tunable DNA for electronics applications

More information: Gate-controlled conductance switching in DNA, Nature Communications, DOI: 10.1038/ncomms14471 

Journal reference: Nature Communications  

Provided by: Arizona State University  

ASU and Stanford Researchers Achieve Record Breaking Efficiency with Tandem (Perovskite + Silicon) Solar Cell


ecee-perovskite-silicon-tandem-cell-pz-0035-w-1280x640Above: A perovskite/silicon tandem solar cell, created by research teams from Arizona State University and Stanford University, capable of record-breaking sunlight-to-electricity conversion efficiency. Photographer: Pete Zrioka/ASU

Some pairs are better together than their individual counterparts — peanut butter and chocolate, warm weather and ice cream, and now, in the realm of photovoltaic technology, silicon and perovskite.

As existing solar energy technologies near their theoretical efficiency limits, researchers are exploring new methods to improve performance — such as stacking two photovoltaic materials in a tandem cell. Collaboration between researchers at Arizona State University and Stanford University has birthed such a cell with record-breaking conversion efficiency — effectively finding the peanut butter to silicon’s chocolate.

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The results of their work, published February 17 in Nature Energy, outline the use of perovskite and silicon to create a tandem solar cell capable of converting sunlight to energy with an efficiency of 23.6 percent, just shy of the all-time silicon efficiency record.

“The best silicon solar cell alone has achieved 26.3 percent efficiency,” says Zachary Holman, an assistant professor of electrical engineering at the Ira A. Fulton Schools of Engineering. “Now we’re gunning for 30 percent with these tandem cells, and I think we could be there within two years.”

Assistant Professor Zachary Holman, holds one of the many solar cells his research group has created. Photographer: Jessica Hochreiter/ASU

Silicon solar cells are the backbone of a $30 billion a year industry, and this breakthrough shows that there’s room for significant improvement within such devices by finding partner materials to boost efficiency.

The high-performance tandem cell’s layers are each specially tuned to capture different wavelengths of light. The top layer, composed of a perovskite compound, was designed to excel at absorbing visible light. The cell’s silicon base is tuned to capture infrared light.

Perovskite, a cheap, easily manufacturable photovoltaic material, has emerged as a challenger to silicon’s dominance in the solar market. Since its introduction to solar technology in 2009, the efficiency of perovskite solar cells has increased from 3.8 percent to 22.1 percent in early 2016, according to the National Renewable Energy Laboratory.

The perovskite used in the tandem cell came courtesy of Stanford researchers Professor Michael McGehee and doctoral student Kevin Bush, who fabricated the compound and tested the materials.

The research team at ASU provided the silicon base and modeling to determine other material candidates for use in the tandem cell’s supporting layers.

OVERCOMING CHALLENGES WITH PEROVSKITES

 Zhengshan (Jason) Yu, an electrical engineering doctoral student at ASU, holds up a tiny black solar cell which is flanked by two conductors. The small cell has yielded big improvements, resulting in a record-breaking 23.6 percent efficiency rate.

Though low-cost and highly efficient, perovskites have been limited by poor stability, degrading at a much faster rate than silicon in hot and humid environments. Additionally, perovskite solar cells have suffered from parasitic absorption, in which light is absorbed by supporting layers in the cell that don’t generate electricity.

“We have improved the stability of the perovskite solar cells in two ways,” says McGehee, a materials science and engineering professor at Stanford’s School of Engineering. “First, we replaced an organic cation with cesium. Second, we protected the perovskite with an impermeable indium tin oxide layer that also functions as an electrode.”

Though McGehee’s compound achieves record stability, perovskites remain delicate materials, making it difficult to employ in tandem solar technology.

“In many solar cells, we put a layer on top that is both transparent and conductive,” says Holman, a faculty member in the School of Electrical, Computer and Energy Engineering. “It’s transparent so light can go through and conductive so we can take electrical charges off it.”

This top conductive layer is applied using a process called sputtering deposition, which historically has led to damaged perovskite cells. However, McGehee was able to apply a tin oxide layer with help from chemical engineering Professor Stacey Bent and doctoral student Axel Palmstrom of Stanford. The pair developed a thin layer that protects the delicate perovskite from the deposition of the final conductive layer without contributing to parasitic absorption, further boosting the cell’s efficiency.

The deposition of the final conductive layer wasn’t the only engineering challenge posed by integrating perovskites and silicon.

“It was difficult to apply the perovskite itself without compromising the performance of the silicon cell,” says Zhengshan (Jason) Yu, an electrical engineering doctoral student at ASU.

Silicon wafers are placed in a potassium hydroxide solution during fabrication, which creates a rough, jagged surface. This texture, ideal for trapping light and generating more energy, works well for silicon, but perovskite prefers a smooth — and unfortunately reflective — surface for deposition.

Additionally, the perovskite layer of the tandem cell is less than a micron thick, opposed to the 250-micron thick silicon layer. This means when the thin perovskite layer was deposited, it was applied unevenly, pooling in the rough silicon’s low points and failing to adhere to its peaks.

Yu developed a method to create a planar surface only on the front of the silicon solar cell using a removable, protective layer. This resulted in a smooth surface on one side of the cell, ideal for applying the perovskite, while leaving the backside rough, to trap the weakly-absorbed near-infrared light in the silicon.

“With the incorporation of a silicon nanoparticle rear reflector, this infrared-tuned silicon cell becomes an excellent bottom cell for tandems,” says Yu.

BUILDING ON PREVIOUS SUCCESSES

The success of the tandem cell is built on existing achievements from both teams of researchers. In October 2016, McGehee and post-doctoral scholar Tomas Leijtens fabricated an all-perovskite cell capable of 20.3 percent efficiency. The high-performance cell was achieved in part by creating a perovskite with record stability, marking McGehee’s group as one of the first teams to devote research efforts to fabricating stable perovskite compounds.

Likewise, Holman has considerable experience working with silicon and tandem cells.

“We’ve tried to position our research group as the go-to group in the U.S. for silicon bottom cells for tandems,” says Holman, who’s been pursuing additional avenues to create high-efficiency tandem solar cells.

In fact, Holman and Yu published a comment in Nature Energy in September 2016 outlining the projected efficiencies of different cell combinations in tandems.

“People often ask, ‘given the fundamental laws of physics, what’s the best you can do?’” says Holman. “We’ve asked and answered a different, more useful question: Given two existing materials, if you could put them together, ideally, what would you get?”’

The publication is a sensible guide to designing a tandem solar cell, specifically with silicon as the bottom solar cell, according to Holman.

It calculates what the maximum efficiency would be if you could pair two existing solar cells in a tandem without any performance loss. The guide has proven useful in directing research efforts to pursue the best partner materials for silicon.

“We have eight projects with different universities and organizations, looking at different types of top cells that go on top of silicon,” says Holman. “So far out of all our projects, our perovskite/silicon tandem cell with Stanford is the leader.”

Oregon St. University: New hydronium-ion battery show promise for sustainable energy storage


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February 20, 2017

 
A new type of battery developed by scientists at Oregon State University shows promise for sustainable, high-power energy storage.

It’s the world’s first battery to use only hydronium ions as the charge carrier.
The new battery provides an additional option for researchers, particularly in the area of stationary storage.

 
Stationary storage refers to batteries in a permanent location that store grid power – including power generated from alternative energy sources such as wind turbines or solar cells – for use on a standby or emergency basis.

 
Hydronium, also known as H3O+, is a positively charged ion produced when a proton is added to a water molecule. Researchers in the OSU College of Science have demonstrated that hydronium ions can be reversibly stored in an electrode material consisting of perylenetetracarboxylic dianhydridem, or PTCDA.

 
This material is an organic, crystalline, molecular solid. The battery, created in the Department of Chemistry at Oregon State, uses dilute sulfuric acid as the electrolyte.
Graduate student Xingfeng Wang was the first author on the study, which has been published in the journal Angewandte Chemie International Edition, a publication of the German Chemical Society.

 
“This may provide a paradigm-shifting opportunity for more sustainable batteries,” said Xiulei Ji, assistant professor of chemistry at OSU and the corresponding author on the research. “It doesn’t use lithium or sodium or potassium to carry the charge, and just uses acid as the electrolyte. There’s a huge natural abundance of acid so it’s highly renewable and sustainable.” Ji points out that until now, cations – ions with a positive charge – that have been used in batteries have been alkali metal, alkaline earth metals or aluminum.
“No nonmetal cations were being considered seriously for batteries,” he said.
The study observed a big dilation of the PTCDA lattice structure during intercalation – the process of its receiving ions between the layers of its structure. That meant the electrode was being charged, and the PTCDA structure expanded, by hydronium ions, rather than extremely tiny protons, which are already used in some batteries.

 
“Organic solids are not typically contemplated as crystalline electrode materials, but many are very crystalline, arranged in a very ordered structure,” Ji said. “This PTCDA material has a lot of internal space between its molecule constituents so it provides an opportunity for storing big ions and good capacity.” The hydronium ions also migrate through the electrode structure with comparatively low “friction,” which translates to high power.
“It’s not going to power electric cars,” Ji said. “But it does provide an opportunity for battery researchers to go in a new direction as they look for new alternatives for energy storage, particularly for stationary grid storage.”

More information: Xingfeng Wang et al, Hydronium-Ion Batteries with Perylenetetracarboxylic Dianhydride Crystals as an Electrode, Angewandte Chemie International Edition (2017). DOI: 10.1002/anie.201700148
Provided by: Oregon State University

Energy-collecting Windows Dream One-Step Closer


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Silicon-based luminescent solar concentrator. While most of the light concentrated to the edge of the silicon-based luminescent solar concentrator is actually invisible, we can better see the concentration effect by the naked eye when the slab is illuminated by a “black light” which is composed of mostly ultraviolet wavelengths. (image: Uwe Kortshagen, University of Minnesota)

February 20, 2017

Researchers at the University of Minnesota and University of Milano-Bicocca are bringing the dream of windows that can efficiently collect solar energy one step closer to reality thanks to high tech silicon nanoparticles.

The researchers developed technology to embed the silicon nanoparticles into what they call efficient luminescent solar concentrators (LSCs). These LSCs are the key element of windows that can efficiently collect solar energy. When light shines through the surface, the useful frequencies of light are trapped inside and concentrated to the edges where small solar cells can be put in place to capture the energy.

The research is published today in Nature Photonics (“Highly efficient luminescent solar concentrators based on Earth-abundant indirect-bandgap silicon quantum dots”).

Windows that can collect solar energy, called photovoltaic windows, are the next frontier in renewable energy technologies, as they have the potential to largely increase the surface of buildings suitable for energy generation without impacting their aesthetics—a crucial aspect, especially in metropolitan areas. LSC-based photovoltaic windows do not require any bulky structure to be applied onto their surface and since the photovoltaic cells are hidden in the window frame, they blend invisibly into the built environment.

The idea of solar concentrators and solar cells integrated into building design has been around for decades, but this study included one key difference—silicon nanoparticles. Until recently, the best results had been achieved using relatively complex nanostructures based either on potentially toxic elements, such as cadmium or lead, or on rare substances like indium, which is already massively utilized for other technologies. Silicon is abundant in the environment and non-toxic. It also works more efficiently by absorbing light at different wavelengths than it emits. However, silicon in its conventional bulk form, does not emit light or luminesce.

“In our lab, we ‘trick’ nature by shrinking the dimension of silicon crystals to a few nanometers, that is about one ten-thousandths of the diameter of human hair,” said University of Minnesota mechanical engineering professor Uwe Kortshagen, inventor of the process for creating silicon nanoparticles and one of the senior authors of the study. “At this size, silicon’s properties change and it becomes an efficient light emitter, with the important property not to re-absorb its own luminescence. This is the key feature that makes silicon nanoparticles ideally suited for LSC applications.”

Using the silicon nanoparticles opened up many new possibilities for the research team.

“Over the last few years, the LSC technology has experienced rapid acceleration, thanks also to pioneering studies conducted in Italy, but finding suitable materials for harvesting and concentrating solar light was still an open challenge,” said Sergio Brovelli, physics professor at the University of Milano-Bicocca, co-author of the study, and co-founder of the spin-off company Glass to Power that is industrializing LSCs for photovoltaic windows “Now, it is possible to replace these elements with silicon nanoparticles.”

Researchers say the optical features of silicon nanoparticles and their nearly perfect compatibility with the industrial process for producing the polymer LSCs create a clear path to creating efficient photovoltaic windows that can capture more than 5 percent of the sun’s energy at unprecedented low costs.

“This will make LSC-based photovoltaic windows a real technology for the building-integrated photovoltaic market without the potential limitations of other classes of nanoparticles based on relatively rare materials,” said Francesco Meinardi, physics professor at the University of Milano-Bicocca and one of the first authors of the paper.

The silicon nanoparticles are produced in a high-tech process using a plasma reactor and formed into a powder.

“Each particle is made up of less than two thousand silicon atoms,” said Samantha Ehrenberg, a University of Minnesota mechanical Ph.D. student and another first author of the study. “The powder is turned into an ink-like solution and then embedded into a polymer, either forming a sheet of flexible plastic material or coating a surface with a thin film.”

The University of Minnesota invented the process for creating silicon nanoparticles about a dozen years ago and holds a number of patents on this technology. In 2015, Kortshagen met Brovelli, who is an expert in LSC fabrication and had already demonstrated various successful approaches to efficient LSCs based on other nanoparticle systems. The potential of silicon nanoparticles for this technology was immediately clear and the partnership was born. The University of Minnesota produced the particles and researchers in Italy fabricated the LSCs by embedding them in polymers through an industrial based method, and it worked.

“This was truly a partnership where we gathered the best researchers in their fields to make an old idea truly successful,” Kortshagen said. “We had the expertise in making the silicon nanoparticles and our partners in Milano had expertise in fabricating the luminescent concentrators. When it all came together, we knew we had something special.”

Source: University of Minnesota

 

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