Articles from November 2015



Perovskite Could Convert Two-Third of Solar Energy To Electricity

Scientists at the Energy Department’s National Renewable Energy Laboratory (NREL) have demonstrated a way to significantly increase the efficiency of perovskite solar cells by reducing the amount of energy lost to heat.

peroskite solar cell

Present-day photovoltaic cells can only effectively utilize about a third of the available energy, with another third lost to heat and the rest lost to other processes instead of being converted to electricity. The NREL research determined that charge carriers created by absorbing sunlight by the perovskite cells encounter a bottleneck where phonons (heat carrying particles) that are emitted while the charge carriers cool cannot decay quickly enough. Instead, the phonons re-heat the charge carriers, thereby drastically slowing the cooling process and allowing the carriers to retain much more of their initial energy for much longer periods of time. This potentially allows this extra energy to be tapped off in a hot-carrier solar cell.

The theoretical limit of how much solar energy perovskite cells can convert to electricity if the hot-carriers are utilized could climb from about 33% to 66%. Additional research is needed, including tests on perovskites made from other materials.

Ye Yang is lead author of the paper. NREL colleagues David Ostrowski, Ryan France, Kai Zhu, Jao van de Lagemaat, Joey Luther and Matthew Beard also contributed to the research. A paper on the discovery, “Observation of a hot-phonon bottleneck in lead-iodide perovskites,” was published online this week in the journal Nature Photonics. The research also will appear in the January print edition of the journal.

Source: http://www.nrel.gov

Give Deaf People A New Voice

A smart device that translates sign language while being worn on the wrist could bridge the communications gap between the deaf and those who don’t know sign language, says a Texas A&M University biomedical engineering researcher who is developing the technology. The wearable technology combines motion sensors and the measurement of electrical activity generated by muscles to interpret hand gestures, explains Roozbeh Jafari, associate professor in the university’s Department of Biomedical Engineering and researcher at the Center for Remote Health Technologies and Systems. Although the device is still in its prototype stage, it can already recognize 40 American Sign Language words with nearly 96 percent accuracy, notes Jafari who presented his research at the Institute of Electrical and Electronics Engineers (IEEE) 12th Annual Body Sensor Networks Conference this past June. The technology was among the top award winners in the Texas Instruments Innovation Challenge this past summer.

sign language

We decode the muscle activities we are capturing from the wrist. Some of it is coming from the fingers indirectly because if I happen to keep my fist like this versus this the muscle activation is going to be a little different“, said Jafari.  It’s those differences that present the researchers with their biggest challenge. Fine tuning the device to process and translate the different signals accurately, in real time, requires sophisticated algorithms. The other problem is that no two people sign exactly alike, which is why they designed the system to learn from its user.  “When you wear the system for the first time the system operates with some level of accuracy. But as you start using the system more often, the system learns from your behavior and it will adapt its own learning models to fit you“,  he added.

Going forward the team hope to miniaturize the device so it can be worn on a users’ wrist like a watch and program it to decipher complete sentences rather than just individual words. The researchers also want to incorporate a synthetic voice speaker, an upgrade that could potentially give the 70 million deaf people around the world…a new voice.

Source: http://engineering.tamu.edu/

‘Self-Healing’ Gel Repairs Electronic Circuit

Researchers in the Cockrell School of Engineering at The University of Texas at Austin have developed a first-of-its-kind self-healing gel that repairs and connects electronic circuits, creating opportunities to advance the development of flexible electronics, biosensors and batteries as energy storage devices. Although technology is moving toward lighter, flexible, foldable and rollable electronics, the existing circuits that power them are not built to flex freely and repeatedly self-repair cracks or breaks that can happen from normal wear and tear.

Until now, self-healing materials have relied on application of external stimuli such as light or heat to activate repair. The UT Austinsupergel” material has high conductivity (the degree to which a material conducts electricity) and strong mechanical and electrical self-healing properties.

self-healed gelSelf-repaired supergel supports its own weight after being sliced in half

In the last decade, the self-healing concept has been popularized by people working on different applications, but this is the first time it has been done without external stimuli,” said mechanical engineering assistant professor Guihua Yu, who developed the gel. “There’s no need for heat or light to fix the crack or break in a circuit or battery, which is often required by previously developed self-healing materials.

Source: http://news.utexas.edu/

Green: How To Clean Oil Sands Water Waste

Researchers have developed a process to remove contaminants from oil sands wastewater using only sunlight and nanoparticles that is more effective and inexpensive than conventional treatment methods.

Frank Gu, a professor in the Faculty of Engineering at the University of Waterloo and Canada Research Chair in Nanotechnology Engineering, is the senior researcher on the team that was the first to find that photocatalysis — a chemical reaction that involves the absorption of light by nanoparticles — can completely eliminate naphthenic acids in oil sands wastewater, and within hours. Naphthenic acids pose a threat to ecology and human health. Water in tailing ponds left to biodegrade naturally in the environment still contains these contaminants decades later.

oil sands pond

With about a billion tonnes of water stored in ponds in Alberta, removing naphthenic acids is one of the largest environmental challenges in Canada,” said Tim Leshuk, a PhD candidate in chemical engineering at Waterloo and the leader of the study . “Conventional treatments people have tried either haven’t worked, or if they have worked, they’ve been far too impractical or expensive to solve the size of the problem.  Waterloo’s technology is the first step of what looks like a very practical and green treatment method.

Source: https://uwaterloo.ca/

How To Remove Nanoparticles From Blood

Engineers at the University of California, San Diego developed a new technology that uses an oscillating electric field to easily and quickly isolate drug-delivery nanoparticles from blood. The technology could serve as a general tool to separate and recover nanoparticles from other complex fluids for medical, environmental, and industrial applications.

Nanoparticles, which are generally one thousand times smaller than the width of a human hair, are difficult to separate from plasma, the liquid component of blood, due to their small size and low density. Traditional methods to remove nanoparticles from plasma samples typically involve diluting the plasma, adding a high concentration sugar solution to the plasma and spinning it in a centrifuge, or attaching a targeting agent to the surface of the nanoparticles. These methods either alter the normal behavior of the nanoparticles or cannot be applied to some of the most common nanoparticle types.

nanoparticles in blood

Nanoparticle removal chip developed by researchers in Professor Michael Heller’s lab at the UC San Diego Jacobs School of Engineering. An oscillating electric field (purple arcs) separates drug-delivery nanoparticles (yellow spheres) from blood (red spheres) and pulls them towards rings surrounding the chip’s electrodes.

This is the first example of isolating a wide range of nanoparticles out of plasma with a minimum amount of manipulation,” said Stuart Ibsen, a postdoctoral fellow in the Department of NanoEngineering at UC San Diego and first author of the study published October in the journal Small.
We’ve designed a very versatile technique that can be used to recover nanoparticles in a lot of different processes.”

Source: http://ucsdnews.ucsd.edu/

Google Glass Used For Arteries Surgery

Doctors in Poland used a virtual reality system combining a custom mobile application and Google Glass to clear a blocked coronary artery, one of the first uses of the technology to assist with surgery. The imaging system was used with a patient who had chronic total occlusion, a complete blockage of the artery, which doctors said is difficult to clear using standard catheter-based percutaneous coronary intervention, or PCI.

The system provides three-dimensional reconstructions of the artery and includes a hands-free voice recognition system allowing for zoom and changes of the images. The head-mounted display system allows doctors to capture images and video while also interacting with the environment around them. In patients with chronic total occlusion, the standard procedure is not always successful, at least partially because of difficulty visualizing the blockage with conventional coronary tomography angiography, or CTA, imaging.

Doctors-use-virtual-reality-imaging-to-treat-blocked-coronary-artery

This case demonstrates the novel application of wearable devices for display of CTA data sets in the catheterization laboratory that can be used for better planning and guidance of interventional procedures, and provides proof of concept that wearable devices can improve operator comfort and procedure efficiency in interventional cardiology,” Dr. Maksymilian Opolski, of the Department of Interventional Cardiology and Angiology at the Institute of Cardiology in Warsaw (Poland), said in a press release.

Source: http://www.onlinecjc.ca/
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http://www.upi.com/

Cheaper, High Performing LED

A team of Florida State University materials researchers has developed a new type of light-emitting diode, or LED, using an organic-inorganic hybrid that could lead to cheaper, brighter and mass produced lights and displays in the future. Assistant Professor of Physics Hanwei Gao and Associate Professor of Chemical Engineering Biwu Ma are using a class of materials called organometal halide perovskites to build a highly functioning LED.

LED Florida

Early work suggested perovskites could be a promising material to build LEDs,” Gao said. “But, the performance was not up to their potential. We believed there was significant room for improvement.”

Perovskites are any materials with the same type of crystal structure as calcium titanium oxide. Other researchers experimented with perovskites to build LEDs in the past but could not build particularly effective ones. Gao and Ma believed this organic-inorganic hybrid could perform better, if the formula could be appropriately tweaked. “When we thought about this class of material, we knew it should perform better than this,” Ma said. “We came up with our novel approach to solve some critical problems and get a high-performance LED.”

After months of experiments using synthetic chemistry to fine-tune the material properties and device engineering to control the device architectures, they ultimately created an LED that performed even better than expected. The material glowed exceptionally bright. It is measured at about 10,000 candelas per square meter at a driving voltage of 12Vcandelas are the unit of measurement for luminescence. As a benchmark, LEDs glowing at about 400 candelas per square meter are sufficiently bright for computer screens. “Such exceptional brightness is, to a large extent, owing to the inherent high luminescent efficiency of this surface-treated, highly crystalline nanomaterial,” Gao said. It was also quick and easy to produce.

They lay out their findings in the journal Advanced Materials.

Source: http://news.fsu.edu/

Nanodentistry Regenerates Your Teeth

Salvatore Sauro, professor of Dentistry at the Universidad CEU Cardenal Herrera in Valencia (Spain), has collaborated with experts from the College of Dental Medicine at Georgia Regents University in Augusta, US, and the Brazilian Universidade Federal do Ceará and Universidade Estadual de Campinas, on an exhaustive study of  nanomaterials and their clinical applications within “nanodentistry.” A detailed overview was published in Trends in Biotechnology, analyzing the cutting-edge properties of polymeric, metallic and inorganic nano-based materials and their potential use in therapeutic and restorative dental care.

smiling-girl

One of the most promising features of these nanomaterials is their capacity to imitate the natural physicochemical, mechanic and aesthetic properties of dentine and dental enamel, underlines Sauro. “This is what is meant by biomimetic: human-made materials that imitate nature and natural processes. “For instance, nanoceramic materials have yielded good results in dental restoration, imitating the aesthetic properties of dental enamel.”

Some dental resins and composites used today to treat tooth loss have already been given the “nano treatment,” incorporating ceramic or silica-rich nanoparticles which, aside from imitating the natural aesthetics of teeth, they are stronger, harder and more resistant to decay. Stronger still are new nanomaterials based on sapphires and diamonds, which have proven twenty times as strong as their ceramic-based counterparts. “The field of dental materials is one that will feel the benefit of advances in nanotechnology on the short-term,” adds Sauro, meaning the door is wide open to restorative dental materials that are even more natural-looking, long-lasting and easier to work with in the clinic setting.

Another area of development is that of remineralising and regenerating dental tissue, whose natural capacity for regeneration in adults is very limited. Nanomaterials are being used in conjunction with stem cells to regenerate dentin, dental cement and even enamel, the tissue least able to regenerate naturally. Incorporated into composites and injectable biomaterials, this is a promising approach to dental tissue repair which harnesses biological responses. However, Sauro warns that further testing is required to ascertain the toxicity of these materials, which may also affect the healthy cells in the treated tissue.

Source: http://ruvid.org/wordpress
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http://www.cell.com/

Blood Test Can Diagnose Pancreatic Cancer

Indiana University cancer researchers have found that a simple blood test might help diagnose pancreatic cancer, one of the most deadly forms of the disease.

In research published today in the American Journal of Gastroenterology, Murray Korc, M.D., Professor of Cancer Research at the Indiana University School of Medicine and a researcher at the Indiana University Melvin and Bren Simon Cancer Center, and colleagues found that several microRNAs – small RNA molecules — circulate at high levels in the blood of pancreatic cancer patients.

blood cells

This is a new finding that extends previous knowledge in this field,” Dr. Korc said. “The key new feature here is that there is a panel of microRNAs that can be measured accurately in the plasma component of blood to determine if a patient has pancreatic cancer.”

Specifically, the IU research team found that an increased expression of miRNA-10b, -155, and -106b in plasma appears highly accurate in diagnosing pancreatic ductal adenocarcinoma. Pancreatic ductal adenocarcinoma is by far the most common type of pancreatic malignancy.

Source: http://news.medicine.iu.edu/

Nanoscale Submarines Will Carry Cargoes Through The Blood

Though they’re not quite ready for boarding a lá “Fantastic Voyage,” nanoscale submarines created at Rice University are proving themselves seaworthy. Each of the single-molecule, 244-atom submersibles built in the Rice lab of chemist James Tour has a motor powered by ultraviolet light. With each full revolution, the motor’s tail-like propeller moves the sub forward 18 nanometers.

And with the motors running at more than a million RPM, that translates into speed. Though the sub’s top speed amounts to less than 1 inch per second, Tour said that’s a breakneck pace on the molecular scale.

submarine at nanoscale

These are the fastest-moving molecules ever seen in solution,” he said.

Expressed in a different way, the researchers reported this month in the American Chemical Society journal Nano Letters that their light-driven nanosubmersibles show an “enhancement in diffusion” of 26 percent. That means the subs diffuse, or spread out, much faster than they already do due to Brownian motion, the random way particles spread in a solution. While they can’t be steered yet, the study proves molecular motors are powerful enough to drive the sub-10-nanometer subs through solutions of moving molecules of about the same size.

This is akin to a person walking across a basketball court with 1,000 people throwing basketballs at him,” Tour said. Rice’s researchers hope future nanosubs will be able to carry cargoes for medical and other purposes. “There’s a path forward,” García-López said. “This is the first step, and we’ve proven the concept. Now we need to explore opportunities and potential applications.”

Source: http://news.rice.edu/

NanoComputers That Imitate Human Brain

Making a nanocomputer that learns and remembers like a human brain is a daunting challenge. The complex organ has 86 billion neurons and trillions of connections — or synapses — that can grow stronger or weaker over time. But now scientists from the Tsinghua University (China) report in ACS’ journal Nano Letters the development of a first-of-its-kind synthetic synapse that mimics the plasticity of the real thing, bringing us one step closer to human-like artificial intelligence.

brain_synapse_hero

While the brain still holds many secrets, one thing we do know is that the flexibility, or plasticity, of neuronal synapses is a critical feature. In the synapse, many factors, including how many signaling molecules get released and the timing of release, can change. This mutability allows neurons to encode memories, learn and heal themselves. In recent years, researchers have been building artificial neurons and synapses with some success but without the flexibility needed for learning. Tian-Ling Ren and colleagues set out to address that challenge.

The researchers created an artificial synapse out of aluminum oxide and twisted bilayer graphene. By applying different electric voltages to the system, they found they could control the reaction intensity of the receiving “neuron.” The team says their novel dynamic system could aid in the development of biology-inspired electronics capable of learning and self-healing.

Source: http://pubs.acs.org/

How To Charge A Phone Battery In 30 Seconds

If you add quantum dotsnanocrystals 10,000 times smaller than the width of a human hair – to a smartphone battery it will charge in 30 seconds, but the effect only lasts for a few recharge cycles.

However, a group of researchers at Vanderbilt University report in  of the journal ACS Nano that they have found a way to overcome this problem: Making the quantum dots out of iron pyrite, commonly known as fool’s gold, can produce batteries that charge quickly and work for dozens of cycles.

The research team headed by Assistant Professor of Mechanical Engineering Cary Pint and led by graduate student Anna Douglas became interested in iron pyrite because it is one of the most abundant materials in the earth’s surface. It is produced in raw form as a byproduct of coal production and is so cheap that it is used in lithium batteries that are bought in the store and thrown away after a single use.

Despite all their promise, researchers have had trouble getting nanoparticles to improve battery performance.

nanocrystals

Researchers have demonstrated that nanoscale materials can significantly improve batteries, but there is a limit,” Pint said. “When the particles get very small, generally meaning below 10 nanometers (40 to 50 atoms wide), the nanoparticles begin to chemically react with the electrolytes and so can only charge and discharge a few times. So this size regime is forbidden In commercial lithium-ion batteries.”

Source: http://news.vanderbilt.edu/