Illuminated rhodium nanoparticles catalyze key chemical reaction
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.”
The paper appears online Feb. 23 in Nature Communications.
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.”
Rhodium nanocubes observed under a transmission electron microscope. Credit: Xiao Zhang
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.”
Researchers have developed a completely new type of display that creates 3D images by using a laser to form tiny bubbles inside a liquid “screen.” Instead of rendering a 3D scene on a flat surface, the display itself is three-dimensional, a property known as volumetric. This allows viewers to see a 3D image in the columnar display from all angles without any 3D glasses or headsets.
In The Optical Society’s journal for high impact research, Optica, researchers led by Yoshio Hayasaki of Utsunomiya University, Japan, demonstrated the ability of their volumetric bubble display to create changeable color graphics.
“Creating a full-color updatable volumetric display is challenging because many three-dimensional pixels, or voxels, with different colors have to be formed to make volumetric graphics,” said Kota Kumagai, first author of the paper. “In our display, the microbubble voxels are three-dimensionally generated in a liquid using focused femtosecond laser pulses. The bubble graphics can be colored by changing the color of the illumination light.”
Although the new work is a proof of concept, the technology might one day allow full-color updatable volumetric displays. These types of displays could be used for art or museum exhibits, where viewers can walk all the way around the display. They are also being explored for helping doctors visualize a patient’s anatomy prior to surgery or to let the military study terrain and buildings prior to a mission.
“The volumetric bubble display is most suited for public facilities such as a museum or an aquarium because, currently, the system setup is big and expensive,” said Kumagai. “However, in the future, we hope to improve the size and cost of the laser source and optical devices to create a smaller system that might be affordable for personal use.”
Using lasers to make bubbles
The bubbles for the new display are created by a phenomenon known as multiphoton absorption, which occurs when multiple photons from a femtosecond laser are absorbed at the point where the light is focused. Multiphoton absorption allowed the researchers to create microbubbles at very precise locations by moving the focus of the laser light to various parts of a liquid-filled cuvette that acted as a “screen.” Using a high-viscosity, or thick, liquid prevents the bubbles, once formed, from immediately rising to the top of the liquid.
The bubble graphics are viewable when they scatter light from an external light source such as a halogen lamp or high-power LED. The researchers produced monochromatic images in white, red, blue and green by switching the color of the illuminating LED. They say that illuminating the graphics with a projector could create different colors in different regions of the image.
Rather than creating each bubble one by one, the researchers used a computer-generated hologram to form 3D patterns of laser light that let them control the number and shapes of the microbubble voxels. This approach also increased the amount of light scattered from the microbubbles, making the images brighter.
In the paper, the researchers demonstrate their technique by creating a sequence of 2D bubble images of a mermaid, a 3D rendered bunny, and 2D dolphin graphics in four different colors. They also showed that microbubble formation depends on the irradiation energy of the laser and that the contrast could be modified by changing the number of laser pulses used to irradiate the liquid.
“Our bubble graphics have a wide viewing angle and can be refreshed and colored,” said Kumagai. “Although our first volumetric graphics are on the scale of millimeters, we achieved the first step toward an updatable full-color volumetric display.”
The researchers are now developing a system that would use a stream inside the liquid to burst the bubbles, allowing the image to be changed or cleared. They are also working on methods that could allow the formation of larger graphics, which requires overcoming spherical aberrations caused by the refractive index mismatch between the liquid screen, the glass holding the liquid, and air.
Long-distance couples can share a walk, watch movies together, and even give each other a massage, using new technologies being developed in Carman Neustaedter’s Simon Fraser University lab.
It’s all about feeling connected, says Neustaedter, an associate professor in SFU’s School of Interactive Arts and Technology (SIAT). Student researchers in his Surrey campus-based Connections Lab are working on myriad solutions.
Among them, researchers have designed a pair of interconnected gloves called Flex-N-Feel. When fingers ‘flex’ in one glove, the actions are transmitted to a remote partner wearing the other. The glove’s tactile sensors allow the wearer to ‘feel’ the movements.
To capture the flex actions, the sensors are attached to a microcontroller. The sensors provide a value for each bend, and are transmitted to the ‘feel’ glove using a WiFi module.
The sensors are also placed strategically on the palm side of the fingers in order to better feel the touch. A soft-switch on both gloves also allows either partner to initiate the touch.
“Users can make intimate gestures such as touching the face, holding hands, and giving a hug,” says Neustaedter. “The act of bending or flexing one’s finger is a gentle and subtle way to mimic touch.”
The gloves are currently a prototype and testing continues. While one set of gloves enables one-way remote touch between partners, Neustaedter says a second set could allow both to share touches at the same time.
Other projects also focus on shared experiences, including a virtual reality video conferencing system that lets one “see through the eyes” of a remote partner, and another that enables users to video-stream a remote partner’s activities to a long-distance partner at home (called Be With Me).
Meanwhile the researchers are also studying how next-generation telepresence robots can help unite couples and participate in activities together.
They’ve embedded a robot, designed by Suitable Technologies, into several Vancouver homes. There, it connects to countries around the world, including India and Singapore. Researchers continue to monitor how the robot is used. One long-distance couple plans a Valentine’s Day ‘date’ while one partner is in Vancouver, and the other, on Vancouver Island.
“The focus here is providing that connection, and in this case, a kind of physical body,” says Neustaedter, who has designed and built eight next-generation telepresence systems for families, and is author of Connecting Families: The Impact of New Communication Technologies on Domestic Life (2012). He has also spent more than a decade studying workplace collaborations over distance, including telepresence attendance at international conferences.
“Long-distance relationships are more common today, but distance don’t have to mean missing out on having a physical presence and sharing space,” says Neustaedter. “If people can’t physically be together, we’re hoping to create the next best technological solutions.”
A U of T Engineering innovation could make printing cells as easy and inexpensive as printing a newspaper. Dr. Hairen Tan and his team have cleared a critical manufacturing hurdle in the development of a relatively new class of solar devices called perovskite solar cells. This alternative solar technology could lead to low-cost, printable solar panels capable of turning nearly any surface into a power generator.
“Economies of scale have greatly reduced the cost of silicon manufacturing,” says University Professor Ted Sargent (ECE), an expert in emerging solar technologies and the Canada Research Chair in Nanotechnology and senior author on the paper. “Perovskite solar cells can enable us to use techniques already established in the printing industry to produce solar cells at very low cost. Potentially, perovskites and silicon cells can be married to improve efficiency further, but only with advances in low-temperature processes.”
Today, virtually all commercial solar cells are made from thin slices of crystalline silicon which must be processed to a very high purity. It’s an energy-intensive process, requiring temperatures higher than 1,000 degrees Celsius and large amounts of hazardous solvents.
In contrast, perovskite solar cells depend on a layer of tiny crystals — each about 1,000 times smaller than the width of a human hair — made of low-cost, light-sensitive materials. Because the perovskite raw materials can be mixed into a liquid to form a kind of ‘solar ink’, they could be printed onto glass, plastic or other materials using a simple inkjet process.
But, until now, there’s been a catch: in order to generate electricity, electrons excited by solar energy must be extracted from the crystals so they can flow through a circuit. That extraction happens in a special layer called the electron-selective layer, or ESL. The difficulty of manufacturing a good ESL has been one of the key challenges holding back the development of perovskite solar cell devices.
“The most effective materials for making ESLs start as a powder and have to be baked at high temperatures, above 500 degrees Celsius,” says Tan. “You can’t put that on top of a sheet of flexible plastic or on a fully fabricated silicon cell — it will just melt.”
Tan and his colleagues developed a new chemical reaction than enables them to grow an ESL made of nanoparticles in solution, directly on top of the electrode. While heat is still required, the process always stays below 150 degrees C, much lower than the melting point of many plastics.
The new nanoparticles are coated with a layer of chlorine atoms, which helps them bind to the perovskite layer on top — this strong binding allows for efficient extraction of electrons. In a paper recently published in Science, Tan and his colleagues report the efficiency of solar cells made using the new method at 20.1 per cent.
“This is the best ever reported for low-temperature processing techniques,” says Tan. He adds that perovskite solar cells using the older, high-temperature method are only marginally better at 22.1 per cent, and even the best silicon solar cells can only reach 26.3 per cent.
Another advantage is stability. Many perovskite solar cells experience a severe drop in performance after only a few hours, but Tan’s cells retained more than 90 per cent of their efficiency even after 500 hours of use. “I think our new technique paves the way toward solving this problem,” says Tan, who undertook this work as part of a Rubicon Fellowship.
“The Toronto team’s computational studies beautifully explain the role of the newly developed electron-selective layer. The work illustrates the rapidly-advancing contribution that computational materials science is making towards rational, next-generation energy devices,” said Professor Alán Aspuru-Guzik, an expert on computational materials science in the Department of Chemistry and Chemical Biology at Harvard University, who was not involved in the work.
“To augment the best silicon solar cells, next-generation thin-film technologies need to be process-compatible with a finished cell. This entails modest processing temperatures such as those in the Toronto group’s advance reported in Science,” said Professor Luping Yu of the University of Chicago’s Department of Chemistry. Yu is an expert on solution-processed solar cells and was not involved in the work.
Keeping cool during the manufacturing process opens up a world of possibilities for applications of perovskite solar cells, from smartphone covers that provide charging capabilities to solar-active tinted windows that offset building energy use. In the nearer term, Tan says his technology could be used in tandem with conventional solar cells.
“With our low-temperature process, we could coat our perovskite cells directly on top of silicon without damaging the underlying material,” says Tan. “If a hybrid perovskite-silicon cell can push the efficiency up to 30 per cent or higher, it makes solar power a much better economic proposition.”
Learn more: Printable solar cells just got a little closer
Carmel Majidi and Jonathan Malen of Carnegie Mellon University have developed a thermally conductive rubber material that represents a breakthrough for creating soft, stretchable machines and electronics.
The findings were published in Proceedings of the National Academy of Sciences this week.
The new material, nicknamed “thubber,” is an electrically insulating composite that exhibits an unprecedented combination of metal-like thermal conductivity and elasticity similar to soft, biological tissue that can stretch over six times its initial length.
“Our combination of high thermal conductivity and elasticity is especially critical for rapid heat dissipation in applications such as wearable computing and soft robotics, which require mechanical compliance and stretchable functionality,” said Majidi, an associate professor of mechanical engineering.
Applications could extend to industries like athletic wear and sports medicine—think of lighted clothing for runners and heated garments for injury therapy. Advanced manufacturing, energy, and transportation are other areas where stretchable electronic material could have an impact.
“Until now, high power devices have had to be affixed to rigid, inflexible mounts that were the only technology able to dissipate heat efficiently,” said Malen, an associate professor of mechanical engineering. “Now, we can create stretchable mounts for LED lights or computer processors that enable high performance without overheating in applications that demand flexibility, such as light-up fabrics and iPads that fold into your wallet.”
The key ingredient in “thubber” is a suspension of non-toxic, liquid metal microdroplets. The liquid state allows the metal to deform with the surrounding rubber at room temperature. When the rubber is pre-stretched, the droplets form elongated pathways that are efficient for heat travel. Despite the amount of metal, the material is also electrically insulating.
To demonstrate these findings, the team mounted an LED light onto a strip of the material to create a safety lamp worn around a jogger’s leg. The “thubber” dissipated the heat from the LED, which would have otherwise burned the jogger. The researchers also created a soft robotic fish that swims with a “thubber” tail, without using conventional motors or gears.
“As the field of flexible electronics grows, there will be a greater need for materials like ours,” said Majidi. “We can also see it used for artificial muscles that power bio-inspired robots.”
Majidi and Malen acknowledge the efforts of lead authors Michael Bartlett, Navid Kazem, and Matthew Powell-Palm in performing this multidisciplinary work. They also acknowledge funding from the Air Force, NASA, and the Army Research Office.
More information: More information: M. Bartlett, N. Kazem, M. Powell-Palm, X.Huang, W. Sun, J. Malen, C. Majidi, “High thermal conductivity in soft elastomers with elongated liquid metal inclusions,” Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1616377114.
Photo credit: Proceedings of the National Academy of Science of the United States of America (PNAS)
Taking one-fourth the standard dose of a widely used drug for prostate cancer with a low-fat breakfast can be as effective – and four times less expensive – as taking the standard dose as recommended: on an empty stomach.
The study, a multi-center, randomized, phase-II clinical trial to be presented at ASCO’s 2017 Genitourinary Cancers Symposium in Orlando, FL, found that the 36 patients who took 250 milligrams of the drug with a low-fat breakfast had outcomes that were virtually identical to the 36 patients who took the standard dose, 1,000 milligrams of the drug on an empty stomach.
The finding has significant financial implications. The drug, abiraterone acetate – marketed as ZYTIGA® – now retails for more than $9,000 per month. Even patients with blue-ribbon health insurance can have co-pays ranging from $1,000 to $3,000 per month.
Patients taking abiraterone acetate typically stay on the medication for 12 to 18 months. Since 2011, according to the manufacturer’s website, more than 100,000 patients in the United States alone have filled prescriptions for abiraterone.
If each of those 100,000 patients had taken the drug for 12 months and, theoretically, paid the list price out of pocket but took the lower dose with food, the 75-percent cost reduction could have saved them more than $6 billion.
Seventy-two patients from multiple centers in the United States and Singapore participated in the study. Patients aged 52 to 89 years (median 74) with advanced prostate cancer whose disease had progressed despite standard initial hormonal therapy, were randomly assigned to take the standard dose on an empty stomach or the low dose with breakfast.
The primary objective of the study was to compare the change in blood levels of prostate specific antigen (PSA), a measure of disease burden and progression. Despite a 75-percent difference in dose, there was no difference in abiraterone activity as measured by variation in PSA levels between the two groups of patients. The time to disease progression also was nearly identical for both arms of the study, about 14 months.
Patients who took the drug with food appeared to have an additional benefit. They were less likely to complain about stomach discomfort than those who took the drug as recommended. The drug’s label recommends fasting for 2 hours before and 1 hour after swallowing the medication. Taking the medication with breakfast is therefore logistically easier for patients.
“We know this drug is absorbed much more efficiently when taken with food,” said study director Russell Szmulewitz, MD, assistant professor of medicine at the University of Chicago and a specialist in medical treatment of patients with advanced prostate cancer. “It’s inefficient, even wasteful, to take this medicine while fasting, which is how the drug’s label says to take it.”
“Given the pharmaco-economic implications,” he added, “our results warrant consideration by doctors who care for prostate cancer patients as well as payers.”
Many drugs taken by mouth have a “food effect,” which can alter how the drug is absorbed. Abiraterone has one of the most dramatic food effects. Blood levels of the drug can be up to 17 times higher when taken with a high-fat meal. Taking the drug with a low-fat meal is more predictable. It increases blood levels four to seven fold.
“This is a widely prescribed drug, a mainstay for patients with prostate cancer,” Szmulewitz said. “It is a great medication that has shifted the standard of care.”
Patients with early stage prostate cancer patients are usually treated initially with hormone therapy, drugs that disrupt the production of male hormones such as testosterone, which promotes tumor growth. This can slow or halt progression of the disease.
Over time, however, cancer cells adapt. They develop the ability to grow and spread without relying on hormones, a stage known as castration-resistant prostate cancer. Historically, those patients were treated with chemotherapy, which can have significant side effects.
Abiraterone, approved for treatment of metastatic prostate cancer in April, 2011, added a new layer to the sequence. It “sits between hormone therapy and chemotherapy,” Szmulewitz explained. “It delays disease progression, improves survival and delays deterioration of quality of life.” When its effects diminish, they shift to a similar, competing drug or move on to chemotherapy.
Patients who take abiraterone for prostate cancer should not “conduct such experiments on their own,” Szmulewitz warned. “This was a relatively small study, too small to show with confidence that the lower dose is as effective. It gives us preliminary but far from definitive evidence. Physicians should use their discretion, based on patient needs.”
The study shows that patients with genuine concerns about costs could, with careful guidance and regular follow-up from their doctors, consider the smaller dose taken with a low-fat breakfast. This would enable them to spread the cost of one month’s of pills over four months, a per-patient savings of up to $7,500 each month.
The American Cancer Society estimates that 161,360 men will be diagnosed with prostate cancer in 2017 and 26,730 men will die from the disease. “If we could reduce the cost of medication for this stage of the disease by a few thousand dollars each month simply by having patients take it with food,” Szmulewitz said, “that would be significant.”
Rutgers’ Richard Riman invented energy-efficient technology that could help limit climate change
In the future, wide-ranging composite materials are expected to be stronger, lighter, cheaper and greener for our planet, thanks to an invention by Rutgers’ Richard E. Riman.
Nine years ago, Riman, a distinguished professor in the Department of Materials Science and Engineering in the School of Engineering, invented an energy-efficient technology that harnesses largely low-temperature, water-based reactions. As a result, he and his team can make things in water that previously were made at temperatures well above those required to thermally decompose plastics.
So far, the revolutionary technology has been used to make more than 30 different materials, including concrete that stores carbon dioxide, the prime greenhouse gas linked to climate change. Other materials include multiple families of composites that incorporate a wide range of metals, polymers and ceramics whose behavior can be processed to resemble wood, bone, seashells and even steel.
A promising option is creating materials for lightweight automobiles, said Riman, who holds dozens of patents and was recently named a fellow of the National Academy of Inventors. The materials could be used for engine, interior and exterior applications. Other materials could perform advanced electronic, optical and magnetic functions that replace mechanical ones.
“Ultimately, what we’d like to be able to do is create a ‘Materials Valley’ here, where this technology can start one company after another, small, medium and large businesses,” Riman said. “It’s a foundational or platform technology for solidifying materials that contain ceramics, among other things. They can be pure ceramics, ceramics and metals, ceramics and polymers – a really wide range of composites.”
Riman, who has taught for 30 years in the Department of Materials Science and Engineering, focuses on making ceramic materials under sustainable conditions. That means low energy with a low carbon dioxide footprint.
His patented technology creates bonds between materials at low temperatures. It’s called reactive hydrothermal liquid-phase densification (rHLPD), also known as low-temperature solidification. And it’s been used to make a wide range of ceramic composite materials at Rutgers, according to an article published last summer in the Journal of the American Ceramic Society.
“Typically, we don’t go any higher than 240 degrees centigrade (464 degrees Fahrenheit) to make the composite materials,” Riman said. “A lot of these processes are done even at room temperature.”
“I looked at how shellfish make ceramics at low-temperature, like carbonate crystals, and then looked at what people can do with water to make landing strips in Alaska and I said we should be able to do this with ceramics, but use a low-temperature chemical process that involves water,” he said.
Riman came up with the idea decades ago but didn’t launch the technology until climate change became a bigger issue. “When it became important to investors to see green technology developed to address carbon emissions in the world, I decided it was time to take this technology commercial,” he said.
So he founded Solidia Technologies® in Piscataway, New Jersey, in 2008. It’s a startup company marketing improved, eco-friendly cement and concrete for construction and infrastructure. Concrete is a $1 trillion market, Riman noted.
“The first thing we did was show that we could make a material that costs the same as conventional Portland cement,” he said. “We developed processing technology that allows you to drop the technology right into the conventional world of concrete and cement without having to make major capital expenditures typically encountered when a technology is disruptive to the marketplace. We plan to do the same thing in the advanced materials business.”
Solidia Concrete™ products have superior strength and durability. They, combined with Solidia Cement™ can reduce the carbon footprint of cement and concrete by up to 70 percent and can save as much as 528.3 billion gallons a year, according to Solidia Technologies.
The company’s concrete-based products include roofing tiles, cinder blocks and hollow core building slabs. The company approaches concrete product manufacturers to see if they’re interested in licensing its products.
“When you can develop technologies that are safe and easy to use, it’s a game changer – and that’s just one of the many areas that we’re interested in pursuing,” Riman said.
His second investor-funded start-up company is RRTC Inc., which is developing advanced composite materials for myriad uses. They include electronic, optical, magnetic, biomedical, biotechnology, pharmaceutical, agricultural, electrochemical, energy storage, energy generation, aerospace, automotive, body and vehicle armor, textile, and abrasive and cutting applications.
Learn more: Rutgers Develops Eco-Friendly Concrete
The bacterial world is rife with unusual talents, among them a knack for producing electricity. In the wild, “electrogenic” bacteria generate current as part of their metabolism, and now researchers at the University of California, Santa Barbara (UCSB), have found a way to confer that ability upon non-electrogenic bacteria. This technique could have applications for sustainable electricity generation and wastewater treatment, the researchers report February 9 in the journal Chem.
“The concept here is that if we just close the lid of the wastewater treatment tank and then give the bacteria an electrode, they can produce electricity while cleaning the water,” says co-first author Zach Rengert, a chemistry graduate student at UCSB. “And the amount of electricity they produce will never power anything very big, but it can offset the cost of cleaning water.”
The bacteria that inspired this study, Shewanella oneidensis MR-1, live in oxygen-free environments and can breathe in metal minerals and electrodes—instead of air—via current-conducting proteins in their cell membranes. Most bacterial species, however, do not have such proteins and therefore naturally do not produce current. Taking inspiration from S. oneidensis‘ membrane-spanning conductive proteins, the team hypothesized that with the right kind of bio-compatible molecular additive, this electrogenesis might be conferred to bacteria that have not evolved to do so.
The researchers, under the guidance of senior author Guillermo Bazan at UCSB, built a molecule called DFSO+, which contains an iron atom at its core. To add the DFSO+ to bacteria, the researchers dissolved a small amount of the rust-colored powder into water and added that solution to bacteria. Within a few minutes, the synthetic molecule found its way into the bacteria’s cell membranes and began conducting current through its iron core, providing a new pathway for the bacteria to shuttle electrons from inside to outside the cell.
Because the DFSO+ molecule’s shape mirrors the structure of cell membranes, it can quickly slip into the membranes and remain there comfortably for weeks. The approach might need some tweaking before being applied to long-term power generation, the researchers say, but it’s an encouraging initial finding.
Microbes in the gut can “disarm” antibiotics, leading to antibiotic resistance and incurable infections. A new method makes it possible to quickly detect resistance genes and, hence, choose the most efficient type of antibiotic treatment.
Taking antibiotics to fight an infection won’t necessarily solve your problems. Often, natural occurring bacteria in the gut harbor several resistance genes. This means that the gut bacteria may exchange genes with the infectious bacteria, resulting in antibiotic resistance. Therefore, knowing the resistome – i.e. the pool of resistance genes present in the gut microbiota – can improve treatment immensely.
Now researchers from The Novo Nordisk Foundation Center for Biosustainability – DTU Biosustain – at Technical University of Denmark have developed a super-fast cheap method called poreFUME that can shed light on the pool of resistance genes in the gut.
“With this method, you will get an overview of the resistome in 1-2 days, and, hence, be able to start the treatment of the infection sooner and with better results than before,” says Eric van der Helm, Postdoc at The Novo Nordisk Foundation Center for Biosustainability – DTU Biosustain – at Technical University of Denmark.
The research has recently been published in the journal Nucleic Acid Research.
Antibiotics resistance is causing 700,000 annual deaths
The poreFUME method using nanopore sequencing is very rapid compared to current methods, because it doesn’t require growth of the faecal bacteria, which takes time and can be difficult. Also, the data from the device is streamed in real time, so the user doesn’t need to wait until the end of a ‘run’ to access information about the experiment.
“We are quite convinced, that rapid resistome profiling could lead to personalized antibiotic treatment in high risk patients”
Today, getting resistome-data from a patient takes weeks. In the meantime, the resistome profile might change dramatically, and the patient will suffer from failing health.
Every year 700,000 people die of resistant infections, in particular hospitalized patients; and the problem seems to be growing. For many patients, a quick assessment of their personal pool of resistance genes in their feces can be lifesaving.
“Our research shows, that this method provides a promising alternative to other sequencing methods and that it can be used to rapidly profile the resistome of microbial communities in for instance the gut. We are quite convinced, that rapid resistome profiling could lead to personalized antibiotic treatment in high risk patients,” says Professor and co-author Morten Sommer from DTU Biosustain.
Cheap runs make the difference
The study was carried out as a collaboration between DTU and co-author Dr. Willem van Schaik from the University Medical Center Utrecht, who provided access to an intensive care unit patient (ICU). In this study, five feces samples from the ICU patient were assessed. After lung transplantation surgery, due to Chronic obstructive pulmonary disease (COPD), the patient was treated with four different kinds of antibiotics to prevent and fight infections. Samples were collected both upon admission to intensive care unit, during stay and several months after hospitalisation.
The results showed that the poreFUME method was 97% accurate, when compared to standardized resistome profiling methods. This percentage is sufficient when measuring the resistome.
Furthermore, the poreFUME method is much cheaper than current methods, primarily due to the low cost of the so-called MinION; a small handheld DNA-sequencing device, which scientists can start to use for 1,000 Dollars. In comparison, conventional so-called next generation sequencing devices are priced at between 50,000 Dollars and 10 million Dollars.
“If hospitals can purchase equipment for resistome profiling cheaper than today, it opens up for better profiling of more patients and hopefully fewer cases of bacterial resistance,” says co-author and Researcher Lejla Imamovic from DTU Biosustain.
Battery stores energy in nontoxic, noncorrosive aqueous solutions
Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new flow battery that stores energy in organic molecules dissolved in neutral pH water. This new chemistry allows for a non-toxic, non-corrosive battery with an exceptionally long lifetime and offers the potential to significantly decrease the costs of production.
The research, published in ACS Energy Letters, was led by Michael Aziz, the Gene and Tracy Sykes Professor of Materials and Energy Technologies and Roy Gordon, the Thomas Dudley Cabot Professor of Chemistry and Professor of Materials Science.
Flow batteries store energy in liquid solutions in external tanks — the bigger the tanks, the more energy they store. Flow batteries are a promising storage solution for renewable, intermittent energy like wind and solar but today’s flow batteries often suffer degraded energy storage capacity after many charge-discharge cycles, requiring periodic maintenance of the electrolyte to restore the capacity.
By modifying the structures of molecules used in the positive and negative electrolyte solutions, and making them water soluble, the Harvard team was able to engineer a battery that loses only one percent of its capacity per 1000 cycles.
“Lithium ion batteries don’t even survive 1000 complete charge/discharge cycles,” said Aziz.
“Because we were able to dissolve the electrolytes in neutral water, this is a long-lasting battery that you could put in your basement,” said Gordon. “If it spilled on the floor, it wouldn’t eat the concrete and since the medium is noncorrosive, you can use cheaper materials to build the components of the batteries, like the tanks and pumps.”
This reduction of cost is important. The Department of Energy (DOE) has set a goal of building a battery that can store energy for less than $100 per kilowatt-hour, which would make stored wind and solar energy competitive with energy produced from traditional power plants.
“If you can get anywhere near this cost target then you change the world,” said Aziz. “It becomes cost effective to put batteries in so many places. This research puts us one step closer to reaching that target.”
“If you can get anywhere near this cost target then you change the world,” said Aziz. “It becomes cost effective to put batteries in so many places. This research puts us one step closer to reaching that target.”
“This work on aqueous soluble organic electrolytes is of high significance in pointing the way towards future batteries with vastly improved cycle life and considerably lower cost,” said Imre Gyuk, Director of Energy Storage Research at the Office of Electricity of the DOE. “I expect that efficient, long duration flow batteries will become standard as part of the infrastructure of the electric grid.”
The key to designing the battery was to first figure out why previous molecules were degrading so quickly in neutral solutions, said Eugene Beh, a postdoctoral fellow and first author of the paper. By first identifying how the molecule viologen in the negative electrolyte was decomposing, Beh was able to modify its molecular structure to make it more resilient.
Next, the team turned to ferrocene, a molecule well known for its electrochemical properties, for the positive electrolyte.
“Ferrocene is great for storing charge but is completely insoluble in water,” said Beh. “It has been used in other batteries with organic solvents, which are flammable and expensive.”
But by functionalizing ferrocene molecules the same way as the viologen, the team was able to turn an insoluble molecule into a highly soluble one that could be cycled stably.
“Aqueous soluble ferrocenes represent a whole new class of molecules for flow batteries,” said Aziz.
The neutral pH should be especially helpful in lowering the cost of the ion-selective membrane that separates the two sides of the battery. Most flow batteries today use expensive polymers that can withstand the aggressive chemistry inside the battery. They can account for up to one-third of the total cost of the device. With essentially salt water on both sides of the membrane, expensive polymers can be replaced by cheap hydrocarbons.
We’ve tried a new approach, moving the focus from muscles to the nervous system. This means that our technology can detect and decode signals more clearly, opening up the possibility of robotic prosthetics that could be far more intuitive and useful for patients
– Professor Dario Farina
Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London
To control the prosthetic, the patient has to think like they are controlling a phantom arm and imagine some simple manoeuvres, such as pinching two fingers together. The sensor technology interprets the electrical signals sent from spinal motor neurons and uses them as commands.
A motor neuron is a nerve cell that is located in the spinal cord. Its fibres, called axons, project outside the spinal cord to directly control muscles in the body.
Robotic arm prosthetics currently on the market are controlled by the user twitching the remnant muscles in their shoulder or arm, which are often damaged. This technology is fairly basic in its functionality, only performing one or two grasping commands. This drawback means that globally around 40-50 per cent of users discard this type of robotic prosthetic.
The team in today’s study, published in the journal Nature Biomedical Engineering, say detecting signals from spinal motor neurons in parts of the body undamaged by amputation, instead of remnant muscle fibre, means that more signals can be detected by the sensors connected to the prosthetic. This means that ultimately more commands could be programmed into the robotic prosthetic, making it more functional.
More useful for patients
Professor Dario Farina, who is now based at Imperial College London, carried out much of the research while at the University Medical Centre Gottingen. The research was conducted in conjunction with Dr Farina’s co-authors in Europe, Canada and the USA.
Professor Farina, from the Department of Bioengineering and Institute of Biomedical Engineering at Imperial, said: “When an arm is amputated the nerve fibres and muscles are also severed, which means that it is very difficult to get meaningful signals from them to operate a prosthetic. We’ve tried a new approach, moving the focus from muscles to the nervous system. This means that our technology can detect and decode signals more clearly, opening up the possibility of robotic prosthetics that could be far more intuitive and useful for patients. It is a very exciting time to be in this field of research.”
The researchers carried out lab-based experiments with six volunteers who were either amputees from the shoulder down or just above the elbow. After some physiotherapy training, the amputees were able to make a more extensive range of movements than would be possible using a classic muscle-controlled robotic prosthetic. They came to this conclusion by comparing their research to previous studies on muscle-controlled robotic prosthetics.
The volunteers were able to move the elbow joint and do radial movements moving the wrist from side to side – as well as opening and closing the hand. This means that the user has all basic hand and arm functions of a real arm.
Further refinements are needed to make the technology more robust, but the researchers suggest the current model could be on the market in the next three years.
To take part in the study, volunteers underwent a surgical procedure at the Medical University of Vienna that involved re-routing parts of their Peripheral Nervous System (PNS), connected with hand and arm movements, to healthy muscles in their body. Depending on the type of amputation, this re-routing was either directed to the pectoral muscle in the chest or the bicep in the arm. This enabled the team to clearly detect the electrical signals sent from the spinal motor neurons – a process the team liken to amplification of the signals.
To create the technology, the researchers decoded and mapped some of the information in electrical signals sent from the re-routed nerve cells and then interpreted them in computer models. These models were then compared to models of healthy patients, which helped them to corroborate the results. Ultimately, the scientists want to decode the meaning behind all signals sent from these motor neurons, so that they can program a full range of arm and hand functions in the prosthetic. This would mean that the user could use the prosthetic almost as seamlessly as if it was their own arm.
The team then encoded specific motor neuron signals as commands into the design of the prosthetic. They then connected a sensor patch on the muscle that had been operated on as part the re-routing procedure, which was connected to the prosthetic. The amputees worked with physiotherapists so they could learn how to control the device by thinking about specific phantom arm and hand commands.
This research has taken the team to the end of the proof of concept stage with laboratory tests. The next step will involve extensive clinical trials with a much wider cross section of volunteers so that the technology can be made more robust.