March 15, 2016
March 14, 2016
Contact lens design for presbyopia
(March 14, 2016) Making the most of the low light in the muddy rivers where it swims, the elephant nose fish survives by being able to spot predators amongst the muck with a uniquely shaped retina, the part of the eye that captures light. In a new study, researchers looked to the fish’s retinal structure to inform the design of a contact lens that can adjust its focus.
Imagine a contact lens that autofocuses within milliseconds. That could be life-changing for people with presbyopia, a stiffening of the eye’s lens that makes it difficult to focus on close objects. Presbyopia affects more than 1 billion people worldwide, half of whom do not have adequate correction, said the project’s leader, Hongrui Jiang, Ph.D., of the University of Wisconsin, Madison. And while glasses, conventional contact lenses and surgery provide some improvement, these options all involve the loss of contrast and sensitivity, as well as difficulty with night vision. Jiang’s idea is to design contacts that continuously adjust in concert with one’s own cornea and lens to recapture a person’s youthful vision.
The project, for which Jiang received a 2011 NIH Director’s New Innovator Award (an initiative of the NIH Common Fund) funded by the National Eye Institute, requires overcoming several engineering challenges. They include designing the lens, algorithm-driven sensors, and miniature electronic circuits that adjust the shape of the lens, plus creating a power source – all embedded within a soft, flexible material that fits over the eye.
In their latest study, published in Proceedings of the National Academy of Sciences, Jiang and his team focused on a design for the image sensors. “The sensors must be extremely small and capable of acquiring images under low-light conditions, so they need to be exquisitely sensitive to light,” Jiang said.
The team took their inspiration from the elephant nose fish’s retina, which has a series of deep cup-like structures with reflective sidewalls. That design helps gather light and intensify the particular wavelengths needed for the fish to see. Borrowing from nature, the researchers created a device that contains thousands of very small light collectors. These light collectors are finger-like glass protrusions, the inside of which are deep cups coated with reflective aluminum. The incoming light hits the fingers and then is focused by the reflective sidewalls. Jiang and his team tested this device’s ability to enhance images captured by a mechanical eye model designed in a lab.
Associate professor Andrea Alù and his team have designed a non-reciprocal antenna
that can independently control incoming and outgoing radio-wave signals with greater
efficiency. Cockrell School of Engineering
(March 14, 2016) Researchers in the Cockrell School of Engineering at The University of Texas at Austin have designed an antenna that is able to process incoming and outgoing radio-wave signals more efficiently and without the need for separate bulky and expensive electrical components commonly used in antenna systems. This new technology could lead to significantly faster, cheaper and clearer telecommunications in the future.
Andrea Alù, associate professor in the Department of Electrical and Computer Engineering, along with postdoctoral fellows Yakir Hadad and Jason Soric, discuss their non-reciprocal antenna’s design and capabilities in the Proceedings of the National Academy of Sciences. Their article will be published online this month.
The research team’s breakthrough design is an antenna that can break reciprocity, or the natural symmetry in radiation that characterizes conventional antennas. In textbooks, the angular patterns for antenna transmission and reception have been assumed to be the same — if the antenna opens a door to let signals out, signals can come back through that same door and leak toward the source. By breaking reciprocity, the UT Austin researchers’ new antenna can independently control incoming and outgoing signals with large efficiency.
The main advantage of this technological advancement is the possibility of sending out a signal while keeping out noise and echoes that come back toward the antenna, enabling faster data rates and improved connections while requiring less bulky antenna systems. Beyond telecommunications, the new antenna technology may be applied to sensors used in applications as diverse as health care and weather tracking, allowing the sensors to pick up stronger signals for more accurate data collection.
A terahertz lens
Researchers have used an array of stacked plates to make a lens for terahertz radiation.
The technique could set stage for new types of components for manipulating terahertz waves.
Mittleman lab / Brown University
(March 14, 2016) Brown University engineers have devised a way to focus terahertz radiation using an array of stacked metal plates, which may prove useful for terahertz imaging or in next-generation data networks.
Terahertz radiation is a relatively unexplored slice of the electromagnetic spectrum, but it holds the promise of countless new imaging applications as well as wireless communication networks with extremely high bandwidth. The problem is that there are few off-the-shelf components available for manipulating terahertz waves.
Now, researchers from Brown University’s School of Engineering have developed a new type of lens for focusing terahertz radiation (which spans from about 100 to 10,000 GHz). The lens, made from an array of stacked metal plates with spaces between them, performs as well or better than existing terahertz lenses, and the architecture used to build the device could set the stage for a range of other terahertz components that don’t currently exist.
The work was led by Rajind Mendis, assistant professor of engineering (research) at Brown, who worked with Dan Mittleman, professor of engineering at Brown. The work is described in the journal Nature Scientific Reports.
The image shows a a two-centimeter beam focused to four millimeters.
Mittleman lab / Brown University
“Any photonic system that uses terahertz – whether it’s in imaging, wireless communications or something else – will require lenses,” said Dan Mittleman, professor of engineering at Brown and the senior author on the new paper. “We wanted to look for new ways to focus terahertz radiation.”
Most lenses use the refractive properties of a material to focus light energy. Eyeglasses, for example, use convex glass to bend visible light and focus it on a certain spot. But for this new terahertz lens, the properties of the materials used don’t matter as much as the way in which the materials are arranged.
(March 14, 2016) METHOD TURNS GLASS FROM CLEAR TO OPAQUE WITH THE FLICK OF A SWITCH
Say goodbye to blinds.
Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a technique that can quickly change the opacity of a window, turning it cloudy, clear or somewhere in between with the flick of a switch.
Tunable windows aren’t new but most previous technologies have relied on electrochemical reactions achieved through expensive manufacturing. This technology, developed by David Clarke, the Extended Tarr Family Professor of Materials, and postdoctoral fellow Samuel Shian, uses geometry adjust the transparency of a window.
The research is described in journal Optics Letters.
The tunable window is comprised of a sheet of glass or plastic, sandwiched between transparent, soft elastomers sprayed with a coating of silver nanowires, too small to scatter light on their own.
But apply an electric voltage and things change quickly.
With an applied voltage, the nanowires on either side of the glass are energized to move toward each other, squeezing and deforming the soft elastomer. Because the nanowires are distributed unevenly across the surface, the elastomer deforms unevenly. The resulting uneven roughness causes light to scatter, turning the glass opaque.
The change happens in less than a second.
It’s like a frozen pond, said Shian.
“If the frozen pond is smooth, you can see through the ice. But if the ice is heavily scratched, you can’t see through,” said Shian.
Clarke and Shian found that the roughness of the elastomer surface depended on the voltage, so if you wanted a window that is only light clouded, you would apply less voltage than if you wanted a totally opaque window.
In this time-lapse series of photos, progressing from top to bottom, a coating of sucrose
(ordinary sugar) over a wire made of carbon nanotubes is lit at the left end, and burns from
one end to the other. As it heats the wire, it drives a wave of electrons along with it,
thus converting the heat into electricity. Courtesy of the researchers
(March 14, 2016) Battery substitutes produce current by burning fuel-coated carbon nanotubes like a fuse.
The batteries that power the ubiquitous devices of modern life, from smartphones and computers to electric cars, are mostly made of toxic materials such as lithium that can be difficult to dispose of and have limited global supplies. Now, researchers at MIT have come up with an alternative system for generating electricity, which harnesses heat and uses no metals or toxic materials.
The new approach is based on a discovery announced in 2010 by Michael Strano, the Carbon P. Dubbs Professor in Chemical Engineering at MIT, and his co-workers: A wire made from tiny cylinders of carbon known as carbon nanotubes can produce an electrical current when it is progressively heated from one end to the other, for example by coating it with a combustible material and then lighting one end to let it burn like a fuse.
That discovery represented a previously unknown phenomenon, but experiments at the time produced only a minuscule amount of current in a simple laboratory setup. Now, Strano and his team have increased the efficiency of the process more than a thousandfold and have produced devices that can put out power that is, pound for pound, in the same ballpark as what can be produced by today’s best batteries. The researchers caution, however, that it could take several years to develop the concept into a commercializable product.
The new results were published in the journal Energy & Environmental Science, in a paper by Strano, doctoral students Sayalee Mahajan PhD ’15 and Albert Liu, and five others.
(March 14, 2016) New social robot from MIT helps students learn through personalized interactions
Parents want the best for their children's education and often complain about large class sizes and the lack of individual attention.
Goren Gordon, an artificial intelligence researcher from Tel Aviv University who runs the Curiosity Lab there, is no different.
He and his wife spend as much time as they can with their children, but there are still times when their kids are alone or unsupervised. At those times, they'd like their children to have a companion to learn and play with, Gordon says.
That's the case, even if that companion is a robot.
Working in the Personal Robots Group at MIT, led by Cynthia Breazeal, Gordon was part of a team that developed a socially assistive robot called Tega that is designed to serve as a one-on-one peer learner in or outside of the classroom.
Socially assistive robots for education aren't new, but what makes Tega unique is the fact that it can interpret the emotional response of the student it is working with and, based on those cues, create a personalized motivational strategy.
Testing the setup in a preschool classroom, the researchers showed that the system can learn and improve itself in response to the unique characteristics of the students it worked with. It proved to be more effective at increasing students' positive attitude towards the robot and activity than a non-personalized robot assistant.
March 12, 2016
A powdery mixture of graphene-wrapped magnesium nanocrystals, produced at
Berkeley Lab, is stable in air. The mixture’s energy properties show promise for use
in hydrogen fuel cells. (Eun Seon Cho/Berkeley Lab)
(March 12, 2016) Berkeley Lab innovation could lead to faster fueling, improved performance for hydrogen-powered vehicles
Hydrogen is the lightest and most plentiful element on Earth and in our universe. So it shouldn’t be a big surprise that scientists are pursuing hydrogen as a clean, carbon-free, virtually limitless energy source for cars and for a range of other uses, from portable generators to telecommunications towers—with water as the only byproduct of combustion.
While there remain scientific challenges to making hydrogen-based energy sources more competitive with current automotive propulsion systems and other energy technologies, researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a new materials recipe for a battery-like hydrogen fuel cell—which surrounds hydrogen-absorbing magnesium nanocrystals with atomically thin graphene sheets—to push its performance forward in key areas.
Thin sheets of graphene oxide (red sheets) have natural, atomic-scale defects that
allow hydrogen gas molecules to pass through while blocking larger molecules
such as oxygen (O2) and water (H2O). Berkeley Lab researchers encapsulated
nanoscale magnesium crystals (yellow) with graphene oxide sheets to produce
a new formula for metal hydride fuel cells. (Jeong Yun Kim)
The graphene shields the nanocrystals from oxygen and moisture and contaminants, while tiny, natural holes allow the smaller hydrogen molecules to pass through. This filtering process overcomes common problems degrading the performance of metal hydrides for hydrogen storage.
These graphene-encapsulated magnesium crystals act as “sponges” for hydrogen, offering a very compact and safe way to take in and store hydrogen. The nanocrystals also permit faster fueling, and reduce the overall “tank” size.
“Among metal hydride-based materials for hydrogen storage for fuel-cell vehicle applications, our materials have good performance in terms of capacity, reversibility, kinetics and stability,” said Eun Seon Cho, a postdoctoral researcher at Berkeley Lab and lead author of a study related to the new fuel cell formula, published recently in Nature Communications.
In a hydrogen fuel cell-powered vehicle using these materials, known as a “metal hydride” (hydrogen bound with a metal) fuel cell, hydrogen gas pumped into a vehicle would be chemically absorbed by the magnesium nanocrystaline powder and rendered safe at low pressures.
March 11, 2016
Dr Lu (left) with student Jiong Yang, with the lens on screen. Image Stuard Hay, ANU
(March 11, 2016) Scientists have created the world's thinnest lens, one two-thousandth the thickness of a human hair, opening the door to flexible computer displays and a revolution in miniature cameras.
Lead researcher Dr Yuerui (Larry) Lu from ANU Research School of Engineering said the discovery hinged on the remarkable potential of the molybdenum disulphide crystal.
"This type of material is the perfect candidate for future flexible displays," said Dr Lu, leader of Nano-Electro-Mechanical System (NEMS) Laboratory in the ANU Research School of Engineering.
"We will also be able to use arrays of micro lenses to mimic the compound eyes of insects."
The 6.3-nanometre lens outshines previous ultra-thin flat lenses, made from 50-nanometre thick gold nano-bar arrays, known as a metamaterial.
"Molybdenum disulphide is an amazing crystal," said Dr Lu
"It survives at high temperatures, is a lubricant, a good semiconductor and can emit photons too.
"The capability of manipulating the flow of light in atomic scale opens an exciting avenue towards unprecedented miniaturisation of optical components and the integration of advanced optical functionalities."
image: Stuard Hay, ANU
Molybdenum disulphide is in a class of materials known as chalcogenide glasses that have flexible electronic characteristics that have made them popular for high-technology components.
Dr Lu's team created their lens from a crystal 6.3-nanometres thick - 9 atomic layers - which they had peeled off a larger piece of molybdenum disulphide with sticky tape.
They then created a 10-micron radius lens, using a focussed ion beam to shave off the layers atom by atom, until they had the dome shape of the lens.
(March 11, 2016) Researchers at the Laboratory for Organic Electronics at LiU, with Professor Xavier Crispin in the lead, have created a supercondenser that can be charged by the sun. It contains no expensive or hazardous materials, has patents pending, and it should be fully possible to manufacture it on an industrial scale.
In the future we could have a completely new type of energy storage, charged by heat energy – for example during the day when the sun shines, or by waste heat from an industrial process. The heat is converted to electricity, which can be stored until it is needed. The results have recently been published in the esteemed journal Energy Environmental Science.
Simply put, a supercondenser is energy storage: a type of battery that consists of an electrolyte of charged particles – ions – between two electrodes. The charge is stored next to the electrodes, most often in carbon nanotubes. One of the physical phenomena that the researchers make use of here is that if a supercapacitor is exposed to a temperature gradient – that is, one end is warm and the other cold – the ions rush towards the cold side and an electric current arises.
The thermoelectric effect is used to make electricity of heat; how much heat is converted to electricity depends both on which electrolyte is used and how great the temperature difference is.
For many years, researchers at the Laboratory for Organic Electronics have experimented with fluid electrolytes consisting of ions and conductive polymers. The positively-charged ions are small and quick, while the negatively-charged polymer molecules are large and heavy. When one end is heated and the other one cooled down, the small, quick ions rush towards the cold side while the heavy polymer chains stay where they are. Since they are ions, and not electrons, they stick to the metal electrodes. The charge that then arises is stored in carbon nanotubes next to the metal electrodes, and can be discharged whenever the electricity is needed.
The drug molecules (red) are embedded in a water-filled cavity
inside of the phopholipid vesicle.
(March 11, 2016) Liposomes are currently used as drug delivery vehicles but recognized by the immune system. Scientists from the universities of Basel and Fribourg have shown that special artificial liposomes do not elicit any reaction in human and porcine sera as well as pigs. The study was published in the Journal Nanomedicine: Nanotechnology, Biology, and Medicine.
Liposomes are soap-bubble-like nanocontainers made of a double phospholipid membrane that shields off an inner aqueous compartment. In a lenticular form, as developed by Professor Andreas Zumbühl’s team at the Department of Chemistry at the University of Fribourg, they are promising candidates for drug delivery to constricted coronary arteries. Here, the blood flows through the stenosed artery segments with high velocity and is subjected to enhanced shear forces. Under these conditions, the liposomes open and release their content.
Unfortunately, the immune system does recognize these liposomes as foreign bodies. The activation of the immune system may lead to a pseudo-allergy. Earlier studies have shown that negative effects are found in up to 30 percent of the cases. Even using clinically approved liposomal dugs it is possible to find anaphylactic shocks, which can be highly toxic for the treated patient.
(March 11, 2016) HARVARD RESEARCHERS DESIGN 3D MATERIAL WITH CONTROLLABLE SHAPE AND SIZE
Imagine a house that could fit in a backpack or a wall that could become a window with the flick of a switch.
Harvard researchers have designed a new type of foldable material that is versatile, tunable and self actuated. It can change size, volume and shape; it can fold flat to withstand the weight of an elephant without breaking, and pop right back up to prepare for the next task.
The research was lead by Katia Bertoldi, the John L. Loeb Associate Professor of the Natural Sciences at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), James Weaver, Senior Research Scientist at the Wyss Institute for Biologically Inspired Engineering at Harvard University and Chuck Hoberman, of the Graduate School of Design. It is described in Nature Communications.
“We’ve designed a three-dimensional, thin-walled structure that can be used to make foldable and reprogrammable objects of arbitrary architecture, whose shape, volume and stiffness can be dramatically altered and continuously tuned and controlled,” said Johannes T. B. Overvelde, graduate student in Bertoldi’s lab and first author of the paper.
The structure is inspired by an origami technique called snapology, and is made from extruded cubes with 24 faces and 36 edges. Like origami, the cube can be folded along its edges to change shape. The team demonstrated, both theoretically and experimentally, that the cube can be deformed into many different shapes by folding certain edges, which act like hinges. The team embedded pneumatic actuators into the structure, which can be programmed to deform specific hinges, changing the cube’s shapes and size, and removing the need for external input.
The team connected 64 of these individual cells to create a 4x4x4 cube that can grow, and shrink, change its shape globally, change the orientation of its microstructure and fold completely flat. As the structure changes shape, it also changes stiffness — meaning one could make a material that’s very pliable or very stiff using the same design. These actuated changes in material properties adds a fourth dimension to the material.
“We not only understand how the material deforms, but also have an actuation approach that harnesses this understanding,” said Bertoldi. “We know exactly what we need to actuate in order to get the shape we want.”
The material can be embedded with any kind of actuator, including thermal, dielectric or even water.
(March 11, 2016) A new study out of the University of Alberta shows vibration technology could help doctors find out what’s shaking with back pain sufferers.
Teaming up with the University of South Denmark, Greg Kawchuk, professor of physical therapy in the faculty of rehabilitative medicine, studied the lumbar spines of identical twins.
They discovered structural changes in the spine significantly affect the way the spine responds to vibration.
“We used gentle vibrations to find out where problems exist in the back,” Kawchuk said. “By studying and testing vibration responses in identical twins, we were able to demonstrate that structural changes within the spine alter its vibration response.”
The study relied on Denmark’s identical twin registry — the largest and most comprehensive of its kind — and researchers found that while twins who had similar spines had similar responses to vibration, in twins where one had sustained a back injury the vibration response between the two was significantly different.
Researchers believe that this research could help doctors diagnose back problems that may not be visible using magnetic resonance imaging, or MRI, scans, and may uncover new diagnoses for those plagued with back pain.
“While an MRI shows us a picture of the spine, it doesn’t show how the spine is working. It’s like taking a picture of a car to see if the car is capable of starting. Vibration diagnostics shows us more than how the spine looks, it shows us how the spine is functioning,” Kawchuk said.
Brienne McKenzie (left), PhD student, and Manmeet Mamik, post-doctoral student, work in the Brain Power Lab at the University of Alberta in Edmonton on Thursday, March 10, 2016. Ian Kucerak
They also believe it could help prevent wasteful, unnecessary MRI scans.
“One of the biggest problems in back pain today is over-utilization of MRI scans in patients that do not need them. This is a waste of health-care resources that leads to over-treatment and even increased disability,” said Jan Hartvigsen, professor of clinical biomechanics and musculoskeletal research with the University of Southern Denmark.
“By using a simple, safe and inexpensive technology like this, we can potentially decrease the use of these scans significantly,” Hartvigsen added.
A schematic shows a trioxacarcin C molecule, whose structure was revealed for
the first time through a new process developed by the Rice lab of synthetic organic
chemist K.C. Nicolaou. Trioxacarcins are found in bacteria but synthetic versions are
needed to study them for their potential as medications. Trioxacarcins have anti-cancer
properties. (Credit: Nicolaou Group/Rice University)
(March 11, 2016) Trioxacarcin molecules bind to the DNA of targeted cells and prevent them from replicating
A team led by Rice University synthetic organic chemist K.C. Nicolaou has developed a new process for the synthesis of a series of potent anti-cancer agents originally found in bacteria.
The Nicolaou lab finds ways to replicate rare, naturally occurring compounds in larger amounts so they can be studied by biologists and clinicians as potential new medications. It also seeks to fine-tune the molecular structures of these compounds through analog design and synthesis to improve their disease-fighting properties and lessen their side effects.
Such is the case with their synthesis of trioxacarcins, reported this month in the Journal of the American Chemical Society.
“Not only does this synthesis render these valuable molecules readily available for biological investigation, but it also allows the previously unknown full structural elucidation of one of them,” Nicolaou said. “The newly developed synthetic technologies will allow us to construct variations for biological evaluation as part of a program to optimize their pharmacological profiles.”
At present, there are no drugs based on trioxacarcins, which damage DNA through a novel mechanism, Nicolaou said.
Trioxacarcins were discovered in the fermentation broth of the bacterial strain Streptomyces bottropensis. They disrupt the replication of cancer cells by binding and chemically modifying their genetic material.
“These molecules are endowed with powerful anti-tumor properties,” Nicolaou said. “They are not as potent as shishijimicin, which we also synthesized recently, but they are more powerful than taxol, the widely used anti-cancer drug. Our objective is to make it more powerful through fine-tuning its structure.”
In a recently published article in Science, Prof. Roberto Morandotti and his team demonstrate
the generation of complex entangled quantum states on an optical chip, bringing us one step
closer to practical applications in quantum information processing. Left: On-chip frequency combs
for scalable, complex quantum state generation. Top right: Quantum frequency comb of entangled photons.
Bottom right: Photonic chip – compatible with common semiconductor fabrication technologies.
Credits : Ultrafast Optical Processing Group, 2016.
(March 11, 2016) Quantum communications and computing
The optical chip developed at INRS by Prof. Roberto Morandotti’s team overcomes a number of obstacles in the development of quantum computers, which are expected to revolutionize information processing. The international research team has demonstrated that on-chip quantum frequency combs can be used to simultaneously generate multiphoton entangled quantum bit (qubit) states.
Quantum computing differs fundamentally from classical computing, in that it is based on the generation and processing of qubits.Unlike classical bits, which can have a state of either 1 or 0, qubits allow a superposition of the 1 and 0 states (both simultaneously).Strikingly, multiple qubits can be linked in so-called ‘entangled’ states, where the manipulation of a single qubit changes the entire system, even if individual qubits are physically distant.This property is the basis for quantum information processing, aiming towards building superfast quantum computers and transferring information in a completely secure way.
Professor Morandotti has focused his research efforts on the realization of quantum components compatible with established technologies.The chip developed by his team was designed to meet numerous criteria for its direct use:it is compact, inexpensive to make, compatible with electronic circuits, and uses standard telecommunication frequencies.It is also scalable, an essential characteristic if it is to serve as a basis for practical systems.But the biggest technological challenge is the generation of multiple, stable, and controllable entangled qubit states.
The generation of qubits can rely on several different approaches, includingelectron spins, atomic energy levels, and photon quantum states. Photons have the advantage of preserving entanglement over long distances and time periods.But generating entangled photon states in a compact and scalable way is difficult.“What is most important, several such states have to be generated simultaneously if we are to arrive at practical applications,” added INRS research associate Dr. Michael Kues.
Roberto Morandotti’s team tackled this challenge by using on-chip optical frequency combs for the first time to generate multiple entangled qubit states of light.As Michael Kues explains, optical frequency combs are light sources comprised of many equally-spaced frequency modes.“Frequency combs are extraordinarily precise sources and have already revolutionized metrology and sensing, as well as earning their discoverers the 2005 Nobel Prize in Physics.”
Thanks to these integrated quantum frequency combs, the chip developed by INRS is able to generate entangled multi-photon qubit states over several hundred frequency modes.It is the first time anyone has demonstrated the simultaneous generation of qubit multi-photon and two-photon entangled states:Until now, integrated systems developed by other research teams had only succeeded in generating individual two-photon entangled states on a chip.
March 10, 2016
Six years ago, the Department of Energy’s SLAC National Accelerator Laboratory answered
a bold call by the scientific community: Build a transformative tool for discovery, an X-ray laser
so bright and fast it can unravel the hidden dynamics of our physical world. (iStockphoto.com/nadla)
(March 10, 2016) 'The First Five Years' Points to a Bright Future of High-impact Discovery at LCLS
If you’ve ever stood in a dark room wishing you had a flashlight, then you understand how scientists feel when faced with the mysteries of physical processes that happen at scales that are mind-bogglingly small and fast.
The future of life-changing science – science that will spawn the electronic devices, medications and energy solutions of the future – depends on being able to see atoms and molecules at work.
To do that you need special light – such as X-ray light with a wavelength as small as an atom – that pulses at the rate of femtoseconds. A femtosecond is to a second what a second is to 32 million years. It is the timescale for the basic building blocks of chemistry, biology and materials science.
That’s why, six years ago, the Department of Energy’s SLAC National Accelerator Laboratory answered a bold call by the scientific community: Build a transformative tool for discovery, an X-ray laser so bright and fast it can unravel the hidden dynamics of our physical world.
Since it began operation in 2009, this singularly powerful “microscope” has generated molecular movies, gotten a glimpse of the birth of a chemical bond, traced electrons moving through materials and made 3-D pictures of proteins that are key to drug discovery. Known to scientists as an X-ray free-electron laser (XFEL), SLAC's Linac Coherent Light Source, or LCLS, is a DOE Office of Science User Facility that draws many hundreds of scientists from around the world each year to perform innovative experiments.
The success of LCLS has inspired the spread of such machines all over the world.
The latest issue of Reviews of Modern Physics contains the most comprehensive scientific overview of its accomplishments in a paper entitled, "Linac Coherent Light Source: The First Five Years."
LCLS staff scientists devoted about a year to compiling the collection of reports, says LCLS Director Mike Dunne.
Smart clothing of the future will automatically adjust itself according to the wearer's actual needs
(March 10, 2016) VTT Technical Research Centre of Finland Ltd has developed new technology that takes care of the thermal, moisture and flow-technical behaviour of smart clothing. The temperature of smart clothing, for example, is automatically adjusted according to the wearer's individual needs. The technology is also suited to demanding conditions such as hospitals and sports.
In its Smart Clothing project, VTT developed a technology that can be utilised in smart fabrics and clothing, able to calculate whether the wearer needs to be cooled or warmed based on initial data measured from the person and the environment. Furthermore, this technology is able to determine the needed warming or cooling power so that the thermal sensation of the person wearing the smart clothing remains optimal in varying conditions. The smart fabrics and clothing currently on the market faces the challenge of adjusting the individual temperature of a human body rapidly and automatically according to the wearer's actual need.
The technology is based on the Human Thermal Model calculation tool developed by VTT, enabling the calculation of a person's individual thermal sensation from the prevailing conditions. Individual thermal sensations are ultimately caused by differences in body composition. There are statistically significant differences between men and women, for example, because men have on average 5 to 15 kg more muscle mass than women.
The wearable smart technology developed by VTT can be applied extensively even in demanding conditions, such as hospitals, nursing homes, and different consumer groups such as police officers, firemen, soldiers, outdoor workers, athletes and small babies.
Vibrations of atoms in materials, the "phonons", are responsible for how
electric charge and heat is transported in materials. (Graphics: Deniz Bozyigit / ETH Zurich)
(March 10, 2016) Researchers at ETH have shown for the first time what happens to atomic vibrations when materials are nanosized and how this knowledge can be used to systematically engineer nanomaterials for different applications.
All materials are made up of atoms, which vibrate. These vibrations, or "phonons", are responsible, for example, for how electric charge and heat is transported in materials. Vibrations of metals, semiconductors, and insulators in are well studied; however, now materials are being nanosized to bring better performance to applications such as displays, sensors, batteries, and catalytic membranes. What happens to vibrations when a material is nanosized has until now not been understood.
Soft Surfaces Vibrate Strongly
In a recent publication in Nature, ETH Professor Vanessa Wood and her colleagues explain what happens to atomic vibrations when materials are nanosized and how this knowledge can be used to systematically engineer nanomaterials for different applications.
The paper shows that when materials are made smaller than about 10 to 20 nanometers - that is, 5,000 times thinner than a human air – the vibrations of the outermost atomic layers on surface of the nanoparticle are large and play an important role in how this material behaves.
“For some applications, like catalysis, thermoelectrics, or superconductivity, these large vibrations may be good, but for other applications like LEDs or solar cells, these vibrations are undesirable,” explains Wood.
Indeed, the paper explains why nanoparticle-based solar cells have until now not met their full promise. The researchers showed using both experiment and theory that surface vibrations interact with electrons to reduce the photocurrent in solar cells.
“Now that we have proven that surface vibrations are important, we can systematically design materials to suppress or enhance these vibrations,” say Wood.
Chemistry graduate student Aanindeeta Banerjee and Assistant Professor Matthew Kanan
have developed a novel way to make renewable plastic from carbon dioxide and ordinary plants
(March 10, 2016) The new technology could provide a green alternative to petroleum-based plastic bottles and other polyester products.
Stanford scientists have discovered a novel way to make plastic from carbon dioxide (CO2) and inedible plant material, such as agricultural waste and grasses. Researchers say the new technology could provide a low-carbon alternative to plastic bottles and other items currently made from petroleum.
"Our goal is to replace petroleum-derived products with plastic made from CO2," said Matthew Kanan, an assistant professor of chemistry at Stanford. "If you could do that without using a lot of non-renewable energy, you could dramatically lower the carbon footprint of the plastics industry."
Kanan and his Stanford colleagues described their results in the March 9 online edition of the journal Nature.
Changing the plastic formula
Many plastic products today are made from a polymer called polyethylene terephthalate (PET), also known as polyester. Worldwide, about 50 million tons of PET are produced each year for items such as fabrics, electronics, recyclable beverage containers and personal-care products.
PET is made from two components, terephthalic acid and ethylene glycol, which are derived from refined petroleum and natural gas. Manufacturing PET produces significant amounts of CO2, a greenhouse gas that contributes to global warming.
"The use of fossil-fuel feedstocks, combined with the energy required to manufacture PET, generates more than four tons of CO2 for every ton of PET that's produced," Kanan said.
For the Nature study, he and his collaborators focused on a promising alternative to PET called polyethylene furandicarboxylate (PEF). PEF is made from ethylene glycol and a compound called 2-5-Furandicarboxylic acid (FDCA).
March 9, 2016
Seeing the Light: Army Ants Evolve to Regain Sight and More in Return to Surface’s Complex Environment
Eciton burchellii ants, among the above-ground species that appeared
to regrow the parts of the brain used for sight.
(March 9, 2016) A change to a more challenging environment could, over time, re-ignite and grow old parts of the brain that have gone inactive, according to a study of army ants led by a Drexel biology professor.
Sean O’Donnell, PhD, professor in the College of Arts and Sciences, studied several genera (groups of related species) of tropical army ants whose ancestors moved to living mostly underground almost 80 million years ago. The army ant species that continued to live underground appeared to have lost most, if not all, of their vision, but the genus Eciton appeared to gain back sight after returning to live on the surface about 18 million years ago.
A diagram depicting the different sections of an ant's brain.
“Most of the known examples of changes in brain investment involve shifts to simpler or ‘reduced’ environments,” O’Donnell said. “Classic examples are cases of light-living surface species giving rise to dark-living cave-dwellers. These are frequently — almost always — associated with reduced vision-processing brain regions.”
But some of the ants that O’Donnell and his research partners studied appeared to grow back parts of the brain used in seeing. It appeared to be a rare example of a species’ brain tissue increasing over time following a move to a more complex environment.
Eciton rapax, another variety of the ants who seemed to evolve to regrow the sight
centers of their brains after returning to the surface millions of years ago.
“Our data on visual investment suggest there is at least some room to regain or increase lost sensory and cognitive function,” O’Donnell said. “We don’t yet know how well Eciton can see and how their eyes work. We found anatomical suggestions that their eye structure is distinct from most other above-ground insects. Have Eciton reinvented the eye to some extent?”
O’Donnell, along with four co-authors, recently published their findings in “Into the black, and back: The ecology of brain investment in Neotropical army ants” in The Science of Nature.
March 8, 2016
Researchers investigated the memory of the model bacteria
Caulobacter crescentus. (Photograph: Wikipedia)
(March 8, 2016) Individual bacterial cells have short memories. But groups of bacteria can develop a collective memory that can increase their tolerance to stress. This has been demonstrated experimentally for the first time in a study by Eawag and ETH Zurich scientists published in PNAS.
Bacteria exposed to a moderate concentration of salt survive subsequent exposure to a higher concentration better than if there is no warning event. But in individual cells this effect is short-lived: after just 30 minutes, the survival rate no longer depends on the exposure history. Now two Eawag/ETH Zurich microbiologists, Roland Mathis and Martin Ackermann, have reported a new discovery made under the microscope with Caulobacter crescentus, a bacterium ubiquitous in freshwater and seawater.
The bacteria are attached to the glass surface by an adhesive stalk. When the bacterial
cells divide, one of the two daughter cells remains in the channel, while the other
is washed out. (Graphics: Stephanie Stutz)
When an entire population is observed, rather than individual cells, the bacteria appear to develop a kind of collective memory. In populations exposed to a warning event, survival rates upon a second exposure two hours after the warning are higher than in populations not previously exposed. Using computational modelling, the scientists explained this phenomenon in terms of a combination of two factors. Firstly, salt stress causes a delay in cell division, leading to synchronization of cell cycles; secondly, survival probability depends on the individual bacterial cell’s position in the cell cycle at the time of the second exposure.
Experimental set-up with the bacterium Caulobacter crescentus in microfluidic chips:
each chip comprises eight channels, with a bacterial population growing in each
channel (Graphic: Stephanie Stutz)
As a result of the cell cycle synchronization, the sensitivity of the population changes over time. Previously exposed populations may be more tolerant to future stress events, but they may sometimes even be more sensitive than populations with no previous exposure.
Martin Ackermann comments: “If we understand this collective effect, it may improve our ability to control bacterial populations.” The findings are relevant, for example, to our understanding of how pathogens can resist antibiotics, or how the performance of bacterial cultures in industrial processes or wastewater treatment plants can be maintained under dynamic conditions. After all, bacteria play a crucial role in almost all bio- and geochemical processes.
(March 8, 2016) An amputee feels rough or smooth textures in real-time — in his phantom hand — using an artificial fingertip connected to nerves in the arm. The advancement will accelerate the development of touch enabled prosthetics.
An amputee was able to feel smoothness and roughness in real-time with an artificial fingertip that was surgically connected to nerves in his upper arm. Moreover, the nerves of non-amputees can also be stimulated to feel roughness, without the need of surgery, meaning that prosthetic touch for amputees can now be developed and safely tested on intact individuals.
The technology to deliver this sophisticated tactile information was developed by Silvestro Micera and his team at EPFL (Ecole polytechnique fédérale de Lausanne) and SSSA (Scuola Superiore Sant'Anna) together with Calogero Oddo and his team at SSSA. The results, published today in eLife, provide new and accelerated avenues for developing bionic prostheses, enhanced with sensory feedback.
"The stimulation felt almost like what I would feel with my hand," says amputee Dennis Aabo Sørensen about the artificial fingertip connected to his stump. He continues, "I still feel my missing hand, it is always clenched in a fist. I felt the texture sensations at the tip of the index finger of my phantom hand."
Sørensen is the first person in the world to recognize texture using a bionic fingertip connected to electrodes that were surgically implanted above his stump.
Nerves in Sørensen's arm were wired to an artificial fingertip equipped with sensors. A machine controlled the movement of the fingertip over different pieces of plastic engraved with different patterns, smooth or rough. As the fingertip moved across the textured plastic, the sensors generated an electrical signal. This signal was translated into a series of electrical spikes, imitating the language of the nervous system, then delivered to the nerves.
Sørensen could distinguish between rough and smooth surfaces 96% of the time.
In a previous study, Sorensen's implants were connected to a sensory-enhanced prosthetic hand that allowed him to recognize shape and softness. In this new publication about texture in the journal eLife, the bionic fingertip attains a superior level of touch resolution.
Simulating touch in non-amputees
This same experiment testing coarseness was performed on non-amputees, without the need of surgery. The tactile information was delivered through fine needles that were temporarily attached to the arm's median nerve through the skin. The non-amputees were able to distinguish roughness in textures 77% of the time.
But does this information about touch from the bionic fingertip really resemble the feeling of touch from a real finger? The scientists tested this by comparing brain-wave activity of the non-amputees, once with the artificial fingertip and then with their own finger. The brain scans collected by an EEG cap on the subject's head revealed that activated regions in the brain were analogous.
The research demonstrates that the needles relay the information about texture in much the same way as the implanted electrodes, giving scientists new protocols to accelerate for improving touch resolution in prosthetics.
March 7, 2016
(March 7, 2016) A web-based machine language system solves crossword puzzles far better than commercially-available products, and may help machines better understand language.
Researchers have designed a web-based platform which uses artificial neural networks to answer standard crossword clues better than existing commercial products specifically designed for the task. The system, which is freely available online, could help machines understand language more effectively.
In tests against commercial crossword-solving software, the system, designed by researchers from the UK, US and Canada, was more accurate at answering clues that were single words (e.g. ‘culpability’ – guilt), a short combination of words (e.g. ‘devil devotee’ – Satanist), or a longer sentence or phrase (e.g. ‘French poet and key figure in the development of Symbolism’ – Baudelaire). The system can also be used a ‘reverse dictionary’ in which the user describes a concept and the system returns possible words to describe that concept.
The researchers used the definitions contained in six dictionaries, plus Wikipedia, to ‘train’ the system so that it could understand words, phrases and sentences – using the definitions as a bridge between words and sentences. Their results, published in the journal Transactions of the Association for Computational Linguistics, suggest that a similar approach may lead to improved output from more general language understanding and dialogue systems and information retrieval engines in general. All of the code and data behind the application has been made freely available for future research.