March 15, 2016
March 14, 2016
Fish and insects guide design for future contact lenses
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.
UT Austin Engineers Design Next-Generation Non-Reciprocal Antenna
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.
Researchers develop new lens for terahertz radiation
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.
Tunable windows for privacy, camouflage
(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.
MIT develops nontoxic way of generating portable power
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.
Robot learning companion offers custom-tailored tutoring
(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
New Fuel Cell Design Powered by Graphene-wrapped Nanocrystals
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
World's thinnest lens to revolutionise cameras
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.
Here heat is stored as electricity
(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.
Soap Bubbles for Treating Stenosed Blood Vessels
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.
Transforming materials
(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.
Edmonton study shows vibration technology an alternative to MRI
(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.
Rice scientists synthesize anti-cancer agent
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.”
INRS takes giant step forward in generating optical qubits
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
5 Ways SLAC’s X-ray Laser Can Change the Way We Live
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.
(iStockphoto.com/xijian)
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.
(iStockphoto.com/Izabela
Habur)
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.
Atomic Vibrations in Nanomaterials
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.
Stanford scientists make renewable plastic from carbon dioxide and plants
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
Collective memory in bacteria
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.
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