#Solar desalination (Nanowerk News) When graduate student Natasha Wright began her Phd program in mechanical engineering, she had no idea how to remove salt from groundwater to make it more palatable,
Now, three years and six trips to India later, this is the sole focus of her work.
Bryce Vickmar) Wright joined the lab of Amos Winter, an assistant professor of mechanical engineering, in 2012.
with a possible focus on filtering biological contaminants from groundwater to make it safe to drink. There are already a number of filters on the market that can do this,
Wright began designing an electrodialysis desalination system, which uses a difference in electric potential to pull salt out of water.
This type of desalination system has been around since the 1950s, but is used typically only municipally, to justify its costs.
While other companies are already installing desalination systems across India, their designs are intended to be powered grid.
When operating off the grid, these systems are not cost-effective, essentially blocking disconnected, rural villages from using them.
Wrights solution offers an alternative to grid power: Shes designed a village-scale desalination system that runs on solar power.
Since her system is powered by the sun, operational and maintenance costs are fairly minimal: The system requires an occasional cartridge filter change,
and thats it. The system is equipped also to treat the biological contaminants that Wright initially thought shed be treating,
using ultraviolet light. The end result is safe drinking water that also tastes good. Earlier this year, Wrights team won a grant from the United states Agency for International Development (USAID),
Local farmers will use the system and provide feedback at a conference organized by Jain Irrigation,
Inc.,a company based in Jalgaon, India. Wrights team is now looking to find out how easy it is for users.
The USAID competition was intended actually for systems built for individual farms, but Wright calculated that the amount of water used by a single farm is similar to the amount of water that a small village needs for its daily drinking water 6 to 12 cubic meters.
such as the ranches in New mexico where she tested her system at full scale, poor access to water pipelines often leads to a heavy reliance on well water.
But some ranchers find that even their livestock wont tolerate the saltiness of this water.
Its useful to install a small-scale desalination system where people are so spread out that its more costly to pump in water from a municipal plant,
#Pimp up my nacre (Nanowerk News) Nacre, or mother of pearl, has highly attractive mechanical properties but cannot be processed into larger-scale structures.
Synthetic nanocomposites can mimic the characteristic brick -and-mortar-like structure of nacre, but combinations of stiffness, strength, toughness and desirable optical properties have remained difficult to achieve.
Scientists based in Aachen, Germany, report in the journal Angewandte Chemie("Hierarchical Nacre Mimetics with Synergistic Mechanical Properties by Control of Molecular Interactions in Self-Healing Polymers")that the introduction of tailored hydrogen bonds in the polymer
mortar by macromolecular engineering leads to an unprecedented combination of the relevant properties, which are perfectly tunable.
In nature, nacre is made a nanocomposite of layers of inorganic microtablets laminated by different biopolymers that stabilize the architecture.
Mankind has used always nacre for decorative purposes, but could not exploit it industrially, despite its generally favorable mechanical properties.
Andreas Walther and his team at the DWI-Leibniz Institute for Interactive Materials, Germany, in collaboration with KIT in Karlsruhe, Germany, use a macromolecular engineering approach to mimic
and tweak the nacre nanocomposite structure for possible mechanical and functional applications. Focusing on the laminating polymer phase,
they designed a low-molecular-weight polymer with low glass-transition temperature, which was equipped with varying degrees of a supramolecular binding motif.
Combined with advanced synthetic nanoclay platelets, the nanocomposite material self-assembled to form a film that possesses all relevant features like excellent transparency, structural periodicity, orientation, stiffness,
and a favorable fracture behavior including self-healing ability. Key to the success are the supramolecular bonds within the soft polymer matrix.
The scientists chose a ureidopyrimidinone (Upy) entity as the bonding motif that, like the nucleobases in DNA, forms dimers through hydrogen bonds."
"The type and amount of hydrogen bonds allow us to tune the manner how the transition of elastic to plastic deformation occurs,
"Walther explains.""In contrast to covalent bonds, supramolecular bonds can first provide resistance against deformation (stiffness boost),
but at substantial stress levels, the bonds can open up and provide fracture energy dissipation by stick/slip interactions and frictional sliding of the platelets against each other."
"These so-called sacrificial bonds allow full control over the material on different levels, because, depending on their amount,
the material can transform from high stiffness and strength to desired combinations of high stiffness and toughness,
as the authors write. So, upon stress the material with 13%Upy motif displayed toughening and failure phenomena"very reminiscent of the behavior of highly reinforced biological materials."
"The scientists further showed that the films are excellent gas barriers. This opens up further possibilities,
not only appealing as mechanically robust nanocomposites, but also for their multifunctional properties relevant to other applications:
as fully transparent oxygen barrier films to encapsulate organic electronics, or to protect against fire with halogen-and heavy-metal-free compositions
Jaeyoun (Jay) Kim, an Iowa State university associate professor of electrical and computer engineering and an associate of the U s. Department of energy's Ames Laboratory."
Co-authors are In-Ho Cho, an Iowa State assistant professor of civil, construction and environmental engineering; and Jungwook Paek, who recently earned his Iowa State doctorate in electrical
and computer engineering and is moving to postdoctoral work at the University of Pennsylvania in Philadelphia. The paper describes how the engineers fabricated microtubes just 8 millimeters long and less than a hundredth of an inch wide.
a transparent elastomer that can be a liquid or a soft, rubbery solid. Kim, whose research focus is micro-electromechanical systems,
The air pressure and the microtube's asymmetrical wall thickness created a circular bend. They further describe how they added a small lump of PDMS to the base of the tube to amplify the bend
And they had to use computer modeling to find a way to create more coiling.
"He said that makes it ideal for medical applications because the microrobotic tentacles can't damage tissues or even blood vessels.
The current study was supported by Kim's six-year, $400, 000 Faculty Early Career development Award from the National Science Foundation.
where people don't want to make robots out of iron and steel. This project is an overlap of both of those fields.
I want to pioneer new work in the field with both microscale and soft robotics
#With 300 kilometres per second to new electronics It may become significantly easier to design electronic components in future.
Scientists at the Max Planck Institute for Chemical Physics of Solids have discovered that the electrical resistance of a compound of niobium
when the material is exposed to a magnetic field. This giant magnetoresistance, which is responsible for the large storage capacity of modern hard discs,
together with colleagues from the High Magnetic field Laboratories at the Helmholtz-Zentrum Dresden-Rossendorf and at the Radboud University in The netherlands, published the new findings on niobium phosphide in the journal Nature Physics.
Electronic systems are expected to process and store a steadily increasing amount of data, faster and faster,
and in less space. Luckily, physicists discover effects that help engineers to develop better electronic components with surprising regularity, for instance a phenomenon known as giant magnetoresistance.
Modern hard discs utilize this phenomenon to significantly alter the resistance of a material by exposing it to a magnetic field.
Until now the computer industry has used various materials stacked on top of each other in a filigree structure to achieve this effect.
Now, Max Planck scientists in Dresden have observed a rapid increase in resistance by a factor of 10,000 in a non-complex material, namely niobium phosphide (Nbp.
The resistance of niobium phosphide changes so dramatically in a magnetic field, because the charge carriers are deflected by a phenomenon known as the Lorentz force.
This force causes an increasing percentage of electrons to start flowing in the rongdirection as the magnetic field is ramped up,
the greater the Lorentz force and thus the effect of a magnetic field, explains Binghai Yan, a researcher at the Max Planck Institute for Chemical Physics of Solids in Dresden.
He and his colleagues therefore came up with the idea of investigating a compound consisting of the transition metal niobium (Nb)
For their investigations, the scientists used the Dresden High Magnetic field Laboratory, as well as the High Field magnet Laboratory at Radboud University in Nijmegen, Netherlands,
and the Diamond Light source in Oxfordshire, England. In the process, they discovered why the electrons are so fast and mobile.
The material owes its exotic properties to unusual electronic states in niobium phosphide. Some electrons in this material, known as a Weyl metal
This material class therefore has enormous potential for future applications in information technology. n
#Sweeping lasers snap together nanoscale geometric grids Down at the nanoscale, where objects span just billionths of a meter,
the size and shape of a material can often have surprising and powerful electronic and optical effects.
Building larger materials that retain subtle nanoscale features is an ongoing challenge that shapes countless emerging technologies.
Now, scientists at the U s. Department of energy's Brookhaven National Laboratory have developed a new technique to rapidly create nano-structured grids for functional materials with unprecedented versatility."
"We can fabricate multi-layer grids composed of different materials in virtually any geometric configuration,
"By quickly and independently controlling the nanoscale structure and the composition, we can tailor the performance of these materials.
"The results published online June 23 in the journal Nature Communications could transform the manufacture of high-tech coatings for anti-reflective surfaces, improved solar cells,
and touchscreen electronics. The scientists synthesized the materials at Brookhaven Lab's Center for Functional Nanomaterials (CFN)
and characterized the nanoscale architectures using electron microscopy at CFN and x-ray scattering at the National Synchrotron Light Sourceoth DOE Office of Science User Facilities.
The new technique relies on polymer self-assembly, where molecules are designed to spontaneously assemble into desired structures.
Self-assembly requires a burst of heat to make the molecules snap into the proper configurations.
Here an intensely hot laser swept across the sample to transform disordered polymer blocks into precise arrangements in just seconds."
"Self-assembled structures tend to automatically follow molecular preferences, making custom architectures challenging,"said lead author Pawel Majewski, a postdoctoral researcher at Brookhaven."
"Laser-assembled nanowires For the first step in grid construction, the team took advantage of their recent invention of laser zone annealing (LZA) to produce the extremely localized thermal spikes needed to drive ultra-fast self-assembly.
To further exploit the power and precision of LZA, the researchers applied a heat-sensitive elastic coating on top of the unassembled polymer film.
and aligns the rapidly forming nanoscale cylinders.""The end result is that in less than one second,
who leads the Electronic nanomaterials group at CFN.""This order persists over macroscopic areas and would be difficult to achieve with any other method."
"To make these two-dimensional grids functional, the scientists converted the polymer base into other materials.
One method involved taking the nano-cylinder layer and dipping it into a solution containing metal salts.
These molecules then glom onto the self-assembled polymer, converting it into a metallic mesh.
A wide range of reactive or conductive metals can be used, including platinum, gold, and palladium.
where a vaporized material infiltrates the polymer nano-cylinders and transforms them into functional nanowires.
Layer-by-layer lattice The first completed nanowire array acts as the foundation of the full lattice.
Additional layers each one following variations on that same process, are stacked then to produce customized, crisscrossing configurationsike chain-link fences 10,000 times thinner than a human hair."
"The direction of the laser sweeping across each unassembled layer determines the orientation of the nanowire rows,
and overlap shapes the grid. We then apply the functional materials after each layer forms.
"We can stack metals on insulators, too, embedding different functional properties and interactions within one lattice structure."
"For example, a single layer of platinum nanowires conducts electricity in only one direction, but a two-layer mesh conducts uniformly in all directions."
allowing it to drive polymer self-assembly even on top of complex underlying layers. This versatility enables the use of a wide variety of materials in different nanoscale configurations."
"We can generate nearly any two-dimensional lattice shape, and thus have a lot of freedom in fabricating multi-component nanostructures,
"Yager said.""It's hard to anticipate all the technologies this rapid and versatile technique will allow. e
#Toward tiny, solar-powered sensors The latest buzz in the information technology industry regards he Internet of thingsthe idea that vehicles, appliances, civil-engineering structures, manufacturing equipment,
and even livestock would have embedded their own sensors that report information directly to networked servers,
however, will require extremely low-power sensors that can run for months without battery changes or, even better,
that can extract energy from the environment to recharge. Last week, at the Symposia on VLSI Technology And circuits, MIT researchers presented a new power converter chip that can harvest more than 80 percent of the energy trickling into it
even at the extremely low power levels characteristic of tiny solar cells. Previous experimental ultralow-power converters had efficiencies of only 40 or 50 percent.
Moreover, the researcherschip achieves those efficiency improvements while assuming additional responsibilities. Where its predecessors could use a solar cell to either charge a battery
or directly power a device, this new chip can do both, and it can power the device directly from the battery.
All of those operations also share a single inductor the chip main electrical component which saves on circuit board space
but increases the circuit complexity even further. Nonetheless the chip power consumption remains low. e still want to have battery-charging capability,
and we still want to provide a regulated output voltage, says Dina Reda El-Damak, an MIT graduate student in electrical engineering and computer science and first author on the new paper. e need to regulate the input to extract the maximum power,
and we really want to do all these tasks with inductor sharing and see which operational mode is the best.
And we want to do it without compromising the performance, at very limited input power levels 10 nanowatts to 1 microwatt for the Internet of things.
The prototype chip was manufactured through the Taiwan Semiconductor Manufacturing Company's University Shuttle Program. Ups and downs The circuit chief function is to regulate the voltages between the solar cell, the battery,
and the device the cell is powering. If the battery operates for too long at a voltage that either too high or too low, for instance, its chemical reactants break down,
and it loses the ability to hold a charge. To control the current flow across their chip, El-Damak and her advisor, Anantha Chandrakasan,
the Joseph F. and Nancy P. Keithley Professor in Electrical engineering, use an inductor, which is a wire wound into a coil.
When a current passes through an inductor, it generates a magnetic field which in turn resists any change in the current.
Throwing switches in the inductor path causes it to alternately charge and discharge, so that the current flowing through it continuously ramps up
and then drops back down to zero. Keeping a lid on the current improves the circuit efficiency,
since the rate at which it dissipates energy as heat is proportional to the square of the current.
Once the current drops to zero, however, the switches in the inductor path need to be thrown immediately;
otherwise, current could begin to flow through the circuit in the wrong direction, which would drastically diminish its efficiency.
and falls depends on the voltage generated by the solar cell, which is highly variable. So the timing of the switch throws has to vary, too.
El-Damak and Chandrakasan use an electrical component called a capacitor, which can store electrical charge.
The higher the current, the more rapidly the capacitor fills. When it full, the circuit stops charging the inductor.
The rate at which the current drops off however, depends on the output voltage, whose regulation is the very purpose of the chip.
Since that voltage is fixed, the variation in timing has to come from variation in capacitance.
El-Damak and Chandrakasan thus equip their chip with a bank of capacitors of different sizes.
As the current drops, it charges a subset of those capacitors, whose selection is determined by the solar cell voltage.
Once again, when the capacitor fills, the switches in the inductor path are flipped. n this technology space,
there usually a trend to lower efficiency as the power gets lower, because there a fixed amount of energy that consumed by doing the work,
says Brett Miwa, who leads a power conversion development project as a fellow at the chip manufacturer Maxim Integrated. f youe only coming in with a small amount,
it hard to get most of it out, because you lose more as a percentage.
El-Damak design is unusually efficient for how low a power level she at. ne of the things that most notable about it is that it really a fairly complete system,
he adds. t really kind of a full system-on-a chip for power management. And that makes it a little more complicated
#Scientists present III-V epitaxy and integration to go below 14nm IBM scientists in Zurich and Yorktown Heights,
Both papers offer the microelectronics industry a possible answer to the long term challenge of creating a new powerful and energy efficient,
yet smaller transistor to pave path for technology scaling for advanced CMOS nodes. Researchers from the IBM Materials Integration and Nanoscale Devices group demonstrated a novel, robust and yet versatile approach for integrating III-V compound semiconductor crystals on silicon wafers a novel and an important step
toward making chips smaller and more powerful at lower power density. The technique developed can be used to combine III-V materials,
including indium, gallium and arsenide (Ingaas), with silicon germanium technology to create CMOS chips. It is fully compatible with current high volume chip fabrication technology,
making it economically viable for chip manufacturers. The first paper was published last week in the journal Applied Physics Letters("Template-assisted selective epitaxy of III nanoscale devices for coplanar heterogeneous integration with Si")by lead
author Heinz Schmid who describes the crystal growth starting from a small area and evolving into a much larger,
defect-free crystal. In this so-called template-assisted selective epitaxy the oxide templates are defined and selectively filled via epitaxy to create arbitrary shaped III-V semiconductors such as nanowires,
cross junctions, nanostructures containing constrictions and 3d stacked nanowires. Using this small seed area epitaxy, today at the VLSI Symposium in Kyoto,
IBM scientist Lukas Czornomaz is presenting a solution for large scale and controlled integration of high quality Ingaas on bulk Silcon (Si)
which is based on standard CMOS process modules. Gate-first CMOS-compatible Ingaas Finfets on Si with excellent performance have been demonstrated and integrated seamlessly in a CMOS manufacturing flow.
Integrating high quality III-V materials on silicon is critical for getting the benefit of higher electron mobility to build transistors with improved power and performance for technology scaling at 7 nm and beyond.
Unfortunately growing III-V materials on 300 mm silicon substrates isn easy and often produces wafers with so many defects that they are rendered useless.
The described novel epitaxy and integration process allows the materials to be grown precisely with a low number of defects on the wafer position where they are needed
and therefore represent a significant, economical and manufacturable breakthrough towards the introduction of high-mobility channels into advanced CMOS nodes.
The new technique may also impact photonics on silicon, with active photonic components integrated seamlessly with electronics for greater functionality.
Both papers are part of IBM $3 billion five year investment to push the limits of silicon technology to 7 nanometers and below.
More specifically, IBM scientists are motivated to integrate III-V materials on silicon for faster and more powerful devices.
IBM is betting that future chips made of these materials will create more energy efficient and powerful cloud data centers and consumer devices d
#Mirrorlike display creates rich color pixels by harnessing ambient light (Nanowerk News) Using a simple structure comprising a mirror
and an absorbing layer to take advantage of the wave properties of light, researchers have developed a display technology that harnesses natural ambient light to produce an unprecedented range of colors
and superior viewing experience. An article describing their innovative approach appears today in The Optical Society's new high-impact journal Optica("Continuous Color Reflective Displays Using Interferometric Absorption".
"This display technology, which could greatly reduce the amount of power used in multiple consumer electronics products,
is the latest version of an established commercial product known as Qualcomm Mirasol. Based on a new color rendering format that the researchers call Continuous Color,
the new design helps solve many key problems affecting mobile displays such as how to provide an always-on display function without requiring more frequent battery charging
and a high quality viewing experience anywhere, especially in bright outdoor environments. The innovation was made possible by using a combination of a mirror with a thin absorbing layer separated by a precise and controllable gap.
While the mirror by itself would simply reflect all of the incident light energy the absorbing layer selectively filters out a narrow slice of the spectrum,
thus coloring the reflected light. The gap is controlled to produce nearly every conceivable color, not just the red, green,
and blue (RGB) of earlier display technologies.""We have developed an entirely new way of creating a color display,
"said John Hong, a researcher with Qualcomm MEMS Technologies, Inc. and lead author on the Optica paper."
"The incredibly efficient display is able to create a rich palette of colors using only ambient light for viewing,
much like the way we would read and view printed material.""Harnessing Ambient light Typical color displays are essential yet power-hungry components of virtually every digital product with a human-machine interface, from cell phones and computers to home televisions and massive displays
at sporting events. Since even the most energy-efficient models require some form of backlighting, they can quickly draw-down a power supply.
engineers have been exploring ways to replace emissive technologies with displays that can reflect ambient light. Earlier attempts to create reflective light color displays,
however, presented a number of vexing problems. The designs required using three separate pixels to produce the red
green and blue of a traditional display. Though adequate for certain applications, the fact that only one-third of the incoming light can be reflected back toward the viewer in a typical reflective RGB format limits the gamut of colors and brightness of the display.
The new display reported in Optica is able to overcome these hurdles by reflecting more of the incoming light
and enabling the full spectrum of visible light to be displayed, including bright white and deep black.
Hong and his colleagues were able achieve these results by using a property of light they call interferometric absorption to create a broad spectrum of colors.
Each pixel therefore behaves as a colored mirror, with the color tunable across the entire visible spectrum.
Extending Power and Saving Energy Depending on how the display is used, the power savings can exceed current backlit technologies tenfold.
when a particular image is retained on the display, which then operates like a form of analog memory in a virtually power-free display mode.
The design presented in the paper consists of a panel that is about 1. 5 inches across
and contains approximately 149, 000 pixels. Both the resolution and area of the display, however, can be scaled to match those of various mobile devices such as Internet-of-Things (Iot) enabled wearables and smartphones.
Fabrication can be achieved in one piece, with the MEMS, upper layer, and lower layer created using the same deposition,
lithography and etching processes that are used to create liquid crystal displays.""Our goal is to improve the technology
and design so it can be integrated easily into manufacturing processes at existing factories.""said Hong.
The researchers believe that this technology has the potential to change the smartphone experience and that of other personal devices."
"No more squinting at a hard to read display outdoors where we spend much of our time,"noted Hong."
"We ultimately hope to create a paperlike viewing experience, which is probably the best display experience that one can expect,
with only the light behind you shining on the page
#Single-nanocatalyst water splitter produces clean-burning hydrogen 24/7 (Nanowerk News) Stanford university scientists have invented a low-cost water splitter that uses a single catalyst to produce both hydrogen
and oxygen gas 24 hours a day, seven days a week. The device, described in a study published June 23 in Nature Communications("Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting"),could provide a renewable source of clean
-burning hydrogen fuel for transportation and industry. Stanford scientists have invented a device that produces clean-burning hydrogen from water 24 hours a day
seven days a week. Unlike conventional water splitters, the Stanford device uses a single low-cost catalyst to generate hydrogen bubbles on one electrode
and oxygen bubbles on the other. Image: L a. Cicero/Stanford university)' We have developed a low-voltage, single-catalyst water splitter that continuously generates hydrogen and oxygen for more than 200 hours,
an exciting world-record performance,'said study co-author Yi Cui, an associate professor of materials science and engineering at Stanford and of photon science at the SLAC National Accelerator Laboratory.
In an engineering first, Cui and his colleagues used lithium-ion battery technology to create one low-cost catalyst that is capable of driving the entire water-splitting reaction.'
'Our group has pioneered the idea of using lithium-ion batteries to search for catalysts, 'Cui said.'
'Our hope is that this technique will lead to the discovery of new catalysts for other reactions beyond water splitting.'
a fossil fuel that contributes to global warming. As an alternative, scientists have been trying to develop a cheap and efficient way to extract pure hydrogen from water.
A conventional water-splitting device consists of two electrodes submerged in a water-based electrolyte.
A low-voltage current applied to the electrodes drives a catalytic reaction that separates molecules of H2o, releasing bubbles of hydrogen on one electrode and oxygen on the other.
Each electrode is embedded with a different catalyst typically platinum and iridium, two rare and costly metals.
But in 2014, Stanford chemist Hongjie Dai developed a water splitter made of inexpensive nickel and iron that runs on an ordinary 1. 5-volt battery.
Single catalyst In the new study, Cui and his colleagues advanced that technology further.''Our water splitter is unique,
for both electrodes,'said graduate student Haotian Wang, lead author of the study.''This bifunctional catalyst can split water continuously for more than a week with a steady input of just 1. 5 volts of electricity.
That's an unprecedented water-splitting efficiency of 82 percent at room temperature.''In conventional water splitters, the hydrogen and oxygen catalysts often require different electrolytes with different phone acidic,
one alkaline--to remain stable and active.''For practical water splitting, an expensive barrier is needed to separate the two electrolytes,
adding to the cost of the device, 'Wang said.''But our single-catalyst water splitter operates efficiently in one electrolyte with a uniform ph.'Wang
and his colleagues discovered that nickel-iron oxide, which is cheap and easy to produce,
is actually more stable than some commercial catalysts made of precious metals.''We built a conventional water splitter with two benchmark catalysts, one platinum and one iridium,
'Wang said.''At first the device only needed 1. 56 volts of electricity to split water,
but within 30 hours we had to increase the voltage nearly 40 percent. That's a significant loss of efficiency.'
'Marriage of batteries and catalysis To find catalytic material suitable for both electrodes, the Stanford team borrowed a technique used in battery research called lithium-induced electrochemical tuning.
The idea is to use lithium ions to chemically break the metal oxide catalyst into smaller and smaller pieces.'
interconnected grain boundaries that become active sites for the water-splitting catalytic reaction, 'Cui said.'
so the catalyst has very good electrical conductivity and stability.''Wang used electrochemical tuning--putting lithium in, taking lithium out to test the catalytic potential of several metal oxides.'
but having a single catalyst also reduces two sets of capital investment to one, 'Cui said.'
'We believe that electrochemical tuning can be used to find new catalysts for other chemical fuels beyond hydrogen.
The technique has been used in battery research for many years, but it's a new approach for catalysis. The marriage of these two fields is very powerful
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