#Researchers Developed a Frictional Interface at the Atomic Level Scientists from MIT have developed a frictional interface at the atomic level.
Friction is all around us, working against the motion of tires on pavement, the scrawl of a pen across paper,
Now physicists at MIT have developed an experimental technique to simulate friction at the nanoscale. Using their technique
Vladan Vuletic, the Lester Wolfe Professor of Physics at MIT, says the ability to tune friction would be helpful in developing nanomachines tiny robots built from components the size of single molecules.
Vuletic says that at the nanoscale, friction may exact a greater force for instance, creating wear and tear on tiny motors much faster than occurs at larger scales. here a big effort to understand friction and control it,
because it one of the limiting factors for nanomachines, but there has been relatively little progress in actually controlling friction at any scale,
along with graduate students Alexei Bylinskii and Dorian Gangloff, published their results in the journal Science. Learn about the technique MIT physicists developed to simulate friction at the nanoscale.
Video: Melanie Gonick/MIT (with computer simulations from Alexei Bylinkskii) Friction and force fieldsthe team simulated friction at the nanoscale by first engineering two surfaces to be placed in contact:
an optical lattice, and an ion crystal. The optical lattice was generated using two laser beams traveling in opposite directions,
When atoms travel across such an electric field, they are drawn to places of minimum potential in this case, the troughs.
an ion crystal essentially, a grid of charged atoms in order to study friction effects, atom by atom.
To generate the ion crystal, the group used light to ionize, or charge, neutral ytterbium atoms emerging from a small heated oven,
and pull the ion crystal across the lattice, as well as to stretch and squeeze the ion crystal,
much like an accordion, altering the spacing between its atoms. An earthquake and a caterpillarin general, the researchers found that
when atoms in the ion crystal were spaced regularly, at intervals that matched the spacing of the optical lattice, the two surfaces experienced maximum friction,
much like two complementary Lego bricks. The team observed that when atoms are spaced so that each occupies a trough in the optical lattice,
when the ion crystal as a whole is dragged across the optical lattice, the atoms first tend to stick in the lattice troughs,
bound there by their preference for the lower electric potential, as well as by the Coulomb forces that keep the atoms apart.
If enough force is applied, the ion crystal suddenly slips, as the atoms collectively jump to the next trough. t like an earthquake,
Vuletic says. here force building up, and then there suddenly a catastrophic release of energy. he group continued to stretch
and squeeze the ion crystal to manipulate the arrangement of atoms, and discovered that if the atom spacing is mismatched from that of the optical lattice,
friction between the two surfaces vanishes. In this case the crystal tends not to stick then suddenly slip,
but to move fluidly across the optical lattice, much like a caterpillar inching across the ground.
For instance, in arrangements where some atoms are in troughs while others are at peaks, and still others are somewhere in between,
as the ion crystal is pulled across the optical lattice, one atom may slide down a peak a bit,
releasing a bit of stress, and making it easier for a second atom to climb out of a trough
not only for realizing nanomachines, but also for controlling proteins, molecules, and other biological components. n the biological domain, there are various molecules
and atoms in contact with one another, sliding along like biomolecular motors, as a result of friction or lack of friction, Gangloff says. o this intuition for how to arrange atoms so as to minimize
or maximize friction could be applied. obias Schaetz, a professor of physics at the University of Freiburg in Germany, sees the results as a lear breakthroughin gaining insight into therwise inaccessible fundamental physics.
The technique he says, may be applied to a number of areas, from the nanoscale to the macroscale. he applications and related impact of their novel method propels a huge variety of research fields investigating effects relevant from raft tectonics down to biological systems
and motor proteins, says Schaetz, who was involved not in the research. ust imagine a nanomachine where we could control friction to enhance contact for traction,
or mitigate drag on demand. his work was funded in part by the National Science Foundation and the National Science and Engineering Research Council of Canada.
Publication: Alexei Bylinskii, et al. uning friction atom-by-atom in an ion-crystal simulator, Science 5 june 2015:
#Engineers Develop a Computer That Operates on Water Researchers at Stanford university have developed a synchronous computer that operates using the unique physics of moving water droplets.
Their goal is to design a new class of computers that can precisely control and manipulate physical matter.
Computers and water typically don mix, but in Manu Prakash lab, the two are one and the same.
Prakash, an assistant professor of bioengineering at Stanford, and his students have built a synchronous computer that operates using the unique physics of moving water droplets.
The computer is nearly a decade in the making incubated from an idea that struck Prakash
when he was a graduate student. The work combines his expertise in manipulating droplet fluid dynamics with a fundamental element of computer science an operating clock. n this work,
we finally demonstrate a synchronous, universal droplet logic and control, Prakash said. Because of its universal nature, the droplet computer can theoretically perform any operation that a conventional electronic computer can crunch,
although at significantly slower rates. Prakash and his colleagues, however, have a more ambitious application in mind. e already have digital computers to process information.
Our goal is not to compete with electronic computers or to operate word processors on this, Prakash said. ur goal is to build a completely new class of computers that can precisely control
and manipulate physical matter. Imagine if when you run a set of computations that not only information is processed
but physical matter is manipulated algorithmically as well. We have made just this possible at the mesoscale. The ability to precisely control droplets using fluidic computation could have a number of applications in high-throughput biology and chemistry,
and possibly new applications in scalable digital manufacturing. The crucial clock For nearly a decade since he was in graduate school,
an idea has been nagging at Prakash: What if he could use little droplets as bits of information
and utilize the precise movement of those drops to process both information and physical materials simultaneously.
Eventually, Prakash decided to build a rotating magnetic field that could act as clock to synchronize all the droplets.
and in the early stages of the project, Prakash recruited a graduate student, Georgios orgoskatsikis, who is the first author on the paper.
Computer clocks are responsible for nearly every modern convenience. Smartphones, DVRS, airplanes, the Internet without a clock, none of these could operate without frequent and serious complications.
Nearly every computer program requires several simultaneous operations each conducted in a perfect step-by-step manner. A clock makes sure that these operations start
and stop at the same times, thus ensuring that the information synchronizes. The results are dire if a clock isn present.
It like soldiers marching in formation: If one person falls dramatically out of time, it won be long before the whole group falls apart.
Prakash explained. he reason computers work so precisely is that every operation happens synchronously; it what made digital logic so powerful in the first place,
A magnetic clock Developing a clock for a fluid-based computer required some creative thinking.
Prakash realized that a rotating magnetic field might do the trick. Katsikis and Prakash built arrays of tiny iron bars on glass slides that look something like a Pac-Man maze.
Then they carefully injected into the mix individual water droplets that had been infused with tiny magnetic nanoparticles.
Next, they turned on the magnetic field. Every time the field flips, the polarity of the bars reverses, drawing the magnetized droplets in a new, predetermined direction, like slot cars on a track.
Every rotation of the field counts as one clock cycle, like a second hand making a full circle on a clock face,
allowing observation of computation as it occurs in real time. The presence or absence of a droplet represents the 1s and 0s of binary code
and the clock ensures that all the droplets move in perfect synchrony, and thus the system can run virtually forever without any errors. ollowing these rules,
wee demonstrated that we can make all the universal logic gates used in electronics, simply by changing the layout of the bars on the chip,
said Katsikis. he actual design space in our platform is incredibly rich. Give us any Boolean logic circuit in the world,
and demonstrates building blocks for synchronous logic gates, feedback and cascadability hallmarks of scalable computation. A simple-state machine including 1-bit memory storage (known as lip-flop is demonstrated also using the above basic building blocks.
A new way to manipulate matter The current chips are about half the size of a postage stamp,
and the droplets are smaller than poppy seeds, but Katsikis said that the physics of the system suggests it can be made even smaller.
Combined with the fact that the magnetic field can control millions of droplets simultaneously, this makes the system exceptionally scalable. e can keep making it smaller and smaller
so that it can do more operations per time, so that it can work with smaller droplet sizes
and do more number of operations on a chip, said graduate student and co-author Jim Cybulski. hat lends itself very well to a variety of applications.
Prakash said the most immediate application might involve turning the computer into a high-throughput chemistry and biology laboratory.
Instead of running reactions in bulk test tubes, each droplet can carry some chemicals and become its own test tube,
and the droplet computer offers unprecedented control over these interactions. From the perspective of basic science, part of why the work is so exciting
Prakash said, is that it opens up a new way of thinking of computation in the physical world.
Although the physics of computation has been applied previously to understand the limits of computation, the physical aspects of bits of information has never been exploited as a new way to manipulate matter at the mesoscale (10 microns to 1 millimeter).
Because the system is extremely robust and the team has uncovered universal design rules, Prakash plans to make a design tool for these droplet circuits available to the public.
to enable everyone to design new circuits based on building blocks we describe in this paper or discover new blocks.
Right now, anyone can put these circuits together to form a complex droplet processor with no external control something that was a very difficult challenge previously
computation takes a special place. We are trying to bring the same kind of exponential scale up because of computation we saw in the digital world into the physical world
#Researchers Increase Energy-Burning Brown Fat cells A team of researchers has discovered a way to increase energy-burning human brown fat cells
and to make them more active, a discovery that could have therapeutic potential for diabetes, obesity,
and other metabolic diseases. Harvard Stem Cell Institute (HSCI) scientists have found a way to both make more energy-burning human brown fat cells
and make the cells themselves more active, a discovery that could have therapeutic potential for diabetes, obesity,
and other metabolic diseases. Unlike energy-storing white, or ad, fat cells, oodbrown fat cells make a protein called UCP1 that converts energy stored in glucose
and fatty acids into heat to keep the body warm. When active brown fat cells can also use energy stored by white fat cells,
and as a result reduce the size of nearby white fat cells. The research team, made up of scientists at Harvard university
and at Harvard-affiliated Joslin Diabetes Center and led by HSCI principal faculty member Yu-Hua Tseng,
determined that the amount of energy burned varies from person to person and from cell to cell.
As it turns out, said Tseng, ot all fat cells are created equal. he researchers determined that a whole suite of genes help determine how much UCP1 a brown fat cell will produce once it has matured,
and those genes control UCP1 production in different ways. Some, Tseng said, act like on/off switches:
a brown fat cell can make the energy-burning protein, and when it is turned off, it doesn.
The research was published online today in the journal Nature Medicine. Tseng collaborated with HSCI Lee Rubin and researchers at the National institutes of health, the Joslin, Boston University, Beth Israel Deaconess Hospital,
and Fudan University in China. Knowing which genes control UCP1 should help scientists develop therapies. e could take fat samples from patients undergoing liposuction
and we could purify this specific population of progenitor cells, keeping only those that would eventually make highly active brown fat cells,
nd let them differentiate into brown cells, and then get them back into the individual,
the additional brown fat cells would burn energy from the existing white fat cells. Tseng hopes this technique could eventually replace invasive procedures such as liposuction and gastric bypass surgery.
While liposuction removes white fat cells, it does not make the brown fat cells more efficient. And gastric bypass,
Tseng believes cell therapy would be uch safer and much less invasive. ontrolling the genes might allow scientists to make mediocre brown fat cells work better.
This could potentially allow the brown fat cells to remove the high numbers of circulating glucose associated with type 2 diabetes
and circulating fatty acids and triglycerides that are the hallmark of metabolic syndrome. y further understanding how adipose cells become thermogenically active,
meaning they use energy to produce heat and thus burn calories, we may discover novel therapeutics for the treatment of obesity
and metabolic disease, said Chad Cowan, an HSCI principal faculty member who, among other things, also studies the therapeutic potential of brown fat cells.
In 2014, Cowan identified two drugs with the potential to convert stem cells that make white fat into those that would make brown. his latest study gives us new tools and targets to use in the battle against obesity
Cowan said. Publication: Ruidan Xue, et al. lonal analyses and gene profiling identify genetic biomarkers of the thermogenic potential of human brown and white preadipocytes, Nature Medicine, 2015;
doi: 10.1038/nm. 3881source: Hannah Robbins, Harvard Gazetteimage: Tseng Laboratory, Joslin Diabetes Cente T
#Deriving Power Directly from Evaporation Eva, the first evaporation-powered car, rolls along, thanks to a moisture mill a turbine engine driven by water evaporating from wet paper strips lining its walls.
Eva is one of the many devices created to harness evaporation energy. Credit: Sahin Laboratory, Columbia University An immensely powerful yet invisible force pulls water from the earth to the top of the tallest redwood
and delivers snow to the tops of The himalayas. Yet despite the power of evaporating water,
its potential to propel self-sufficient devices or produce electricity has remained largely untapped until now. In the June 16 online issue of Nature Communications, Columbia University scientists report the development of two novel devices that derive power directly from evaporation a floating,
piston-driven engine that generates electricity causing a light to flash, and a rotary engine that drives a miniature car.
When evaporation energy is scaled up the researchers predict, it could one day produce electricity from giant floating power generators that sit on bays or reservoirs,
or from huge rotating machines akin to wind turbines that sit above water, said Ozgur Sahin, Ph d,
. an associate professor of biological sciences and physics at Columbia University and the paper lead author. vaporation is a fundamental force of nature,
Sahin said. t everywhere, and it more powerful than other forces like wind and waves.
Last year, Sahin found that when bacterial spores shrink and swell with changing humidity, they can push
and pull other objects forcefully. They pack more energy pound for pound, than other materials used in engineering for moving objects,
he reported in a paper published in Nature Nanotechnology, which was based on work Sahin had started as a Scholar in Residence at the Wyss Institute for Biologically Inspired Engineering at Harvard university.
Building on last year findings, Sahin and his Columbia colleagues sought to build actual devices that could be powered by such energy.
To build a floating, piston-driven engine, the researchers first glued spores to both sides of a thin, double-sided plastic tape akin to that in cassette tapes,
creating a dashed line of spores. They did the same on the opposite side of the tape
but offset the line so dashes on one side overlapped with gaps on the other.
When dry air shrinks the spores, the spore-covered dashes curve. This transforms the tape from straight to wavy,
shortening the tape. If one or both ends of the tape are anchored, the tape tugs on whatever it attached to.
Conversely, when the air is moist, the tape extends, releasing the force. The result is a new type of artificial muscle that is controlled by changing humidity.
creating a stronger artificial muscle that they then placed inside a floating plastic case topped with shutters.
Coupling that piston to a generator produced enough electricity to cause a small light to flash. e turned evaporation from a pool of water into light,
With its current power output, the floating evaporation engine could supply small floating lights or sensors at the ocean floor that monitor the environment,
speculating that an improved version with stickier plastic tape and more spores could potentially generate even more power per unit area than a wind farm.
The Columbia team other new evaporation-driven engine the Moisture Mill contains a plastic wheel with protruding tabs of tape covered on one side with spores.
and the other half sits in humid environment, where the tabs straighten. As a result, the wheel rotates continuously,
The researchers next built a small toy car, powering it with the Moisture Mill and were successful in getting the car to roll on its own,
powered only by evaporation. In the future, Sahin said, it may be possible to design engines that use the mechanical energy stored in spores to propel a full-sized vehicle.
Such an engine, if achieved, would require neither fuel to burn nor an electrical battery.
A larger version of the Moisture Mill could also produce electricity Sahin said, suggesting a wheel that sits above a large body of water
and evaporates saltwater, causing the wheel to rotate and generate electricity. This development would steadily produce as much electricity as a wind turbine,
Sahin said
#Safe drinking water Via Solar power Desalination Natasha Wright, an MIT Phd student in mechanical engineering, has designed a solar powered system that makes water safe to drink for rural, off-grid Indian villages.
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,
nor had she ever been to India, where this is an ongoing need. Now, three years and six trips to India later, this is the sole focus of her work.
Wright joined the lab of Amos Winter an assistant professor of mechanical engineering, in 2012. The lab was just getting established,
and the aim of Wright project was vague at first: Work on water treatment in India, 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, and during her second trip to India, Wright interviewed a number of villagers,
finding that many of them weren using these filters. She became skeptical of how useful it would be to develop yet another device like 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.
Wright solution offers an alternative to grid power: She 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 that it. The system is equipped also to treat the biological contaminants that Wright initially thought she be treating,
using ultraviolet light. The end result is safe drinking water that also tastes good. Earlier this year, Wright 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. Wright 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 won tolerate the saltiness of this water. t useful to install a small-scale desalination system where people are
#Half Price Lithium-ion Batteries With Improved Performance and Recyclability MIT spinoff company 24m has reinvented the manufacturing process for lithium-ion batteries to reduce cost,
An advanced manufacturing approach for lithium-ion batteries, developed by researchers at MIT and at a spinoff company called 24m,
promises to significantly slash the cost of the most widely used type of rechargeable batteries while also improving their performance
says Yet-Ming Chiang, the Kyocera Professor of Ceramics at MIT and a cofounder of 24m (and previously a cofounder of battery company A123).
The existing process for manufacturing lithium-ion batteries, he says, has changed hardly in the two decades
and colleagues including W. Craig Carter, the POSCO Professor of Materials science and engineering. In this so-called low battery, the electrodes are suspensions of tiny particles carried by a liquid
and pumped through various compartments of the battery. The new battery design is a hybrid between flow batteries and conventional solid ones:
In this version, while the electrode material does not flow, it is composed of a similar semisolid, colloidal suspension of particles.
Chiang and Carter refer to this as a emisolid battery. impler manufacturing processthis approach greatly simplifies manufacturing,
and also makes batteries that are flexible and resistant to damage, says Chiang, who is senior author of a paper in the Journal of Power Sources analyzing the tradeoffs involved in choosing between solid
and flow-type batteries, depending on their particular applications and chemical components. This analysis demonstrates that
while a flow battery system is appropriate for battery chemistries with a low energy density (those that can only store a limited amount of energy for a given weight),
for high-energy density devices such as lithium-ion batteries, the extra complexity and components of a flow system would add unnecessary extra cost.
Almost immediately after publishing the earlier research on the flow battery, Chiang says, e realized that a better way to make use of this flowable electrode technology was to reinvent the lithium ion manufacturing process. nstead of the standard method of applying liquid coatings to a roll of backing material,
and then having to wait for that material to dry before it can move to the next manufacturing step,
the new process keeps the electrode material in a liquid state and requires no drying stage at all.
Using fewer thicker electrodes, the system reduces the conventional battery architecture number of distinct layers, as well as the amount of nonfunctional material in the structure, by 80 percent.
Having the electrode in the form of tiny suspended particles instead of consolidated slabs greatly reduces the path length for charged particles as they move through the material a property known as ortuosity.
A less tortuous path makes it possible to use thicker electrodes, which, in turn, simplifies production
and lowers cost. Bendable and foldablein addition to streamlining manufacturing enough to cut battery costs by half,
Chiang says, the new system produces a battery that is more flexible and resilient. While conventional lithium-ion batteries are composed of brittle electrodes that can crack under stress
the new formulation produces battery cells that can be bent, folded or even penetrated by bullets without failing.
This should improve both safety and durability, he says. The company has made so far about 10,000 batteries on its prototype assembly lines, most
of which are undergoing testing by three industrial partners, including an oil company in Thailand and Japanese heavy-equipment manufacturer IHI Corp. The process has received eight patents
and has 75 additional patents under review; 24m has raised $50 million in financing from venture capital firms and a U s. Department of energy grant.
The company is initially focusing on grid-scale installations, used to help smooth out power loads
and provide backup for renewable energy sources that produce intermittent output, such as wind and solar power. But Chiang says the technology is suited also well to applications where weight
and volume are limited, such as in electric vehicles. Another advantage of this approach, Chiang says, is that factories using the method can be scaled up by simply adding identical units.
With traditional lithium-ion production plants must be built at large scale from the beginning in order to keep down unit costs,
so they require much larger initial capital expenditures. By 2020, Chiang estimates that 24m will be able to produce batteries for less than $100 per kilowatt-hour of capacity.
Venkat Viswanathan, an assistant professor of mechanical engineering at Carnegie mellon University who was involved not in this work, says the analysis presented in the new paper ddresses a very important question of
when is it better to build a flow battery versus a static model. This paper will serve as a key tool for making design choices
and go-no go decisions. iswanathan adds that 24m new battery design ould do the same sort of disruption to lithium ion batteries manufacturing as
what mini-mills did integrated to the steel mills. n addition to Chiang, the Power Sources paper was authored co by graduate student Brandon Hopkins, mechanical engineering professor Alexander Slocum,
and Kyle Smith of the University of Illinois at Urbana-Champaign. The work was supported by the U s. Department of energy Center for Energy storage Research,
based at Argonne National Laboratory in Illinois. Source: David L. Chandler, MIT Newsimages: 24 v
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