#Tunable antenna could end annoying dropped calls Cornell University rightoriginal Studyposted by Anne Ju-Cornell on October 22 2013.
A new iller materialcan help put an end to dropped calls by making cell phones that tune to different frequencies without wasting battery power.
Like a radio tuned to different stations cell phone antennas have tuning circuits that quickly switch frequencies
when controlled by a voltage applied to a tunable capacitor. Cell phone companies want to improve these circuits to pack more discrete signals into a finite allocation of spectrum
and minimize those pesky dropped calls. Researchers have developed what is perhaps the world s best material for tunable capacitors broadly called a tunable dielectric a special insulator
whose ability to store electrical charge changes when a voltage is applied. The research was published online in the journal Nature. his is a radically different material compared to
what people have been using for decadessays Darrell Schlom professor of industrial chemistry at Cornell University who led the international research team. hat we have discovered is the world's lowest-loss tunable dielectric. ossrefers to wasted energy
which drains cell phone batteries. The new type of tunable dielectric could greatly improve the performance of microwave circuit capacitors found in every cell phone
and open up new possibilities for wireless communication at much higher frequencies. The scientific achievement is twofold.
It is the material itself a layered strontium titanium oxide not found in nature created through molecular beam epitaxy
which Schlom's lab uses to build up layered materials one atomic layer at a time by prayingatoms onto a surface.
The tunable dielectric and its properties were envisioned first on paper tested on the computer created in the lab atom by atom patterned into a capacitor device
The result is a tunable dielectric capacitor with at least five times the performance of commercial tunable capacitors available today according to Schlom.
By comparison today's commercially used tunable dielectric material is layered not a material and contains barium in addition to strontium oxygen and proprietary additives.
and greatly lower the films performance in circuitsâ##a problem cell phone companies would like to solve.
which keep them away from the ricksdrastically improving the performance of this new variety of tunable capacitors.
and how to push its performance even further. t is clear that we have discovered a killer materialschlom says ut it is likely that even better tunable dielectrics can be found using our approach. he Army Research Office
#Ceramic converter tackles solar cell problem Stanford university rightoriginal Studyposted by Mark Shwartz-Stanford on October 21 2013coating a solar cell component in ceramics makes it more heat resistant
which can be absorbed by solar cells to make electricity a technology known as thermophotovoltaics. Unlike earlier prototypes that fell apart before temperatures reached 2200 degrees Fahrenheit (1200 degrees Celsius) the new thermal emitter remains stable at temperatures as high as 2500 F
(1400 C). his is a record performance in terms of thermal stability and a major advance for the field of thermophotovoltaicssays Shanhui Fan a professor of electrical engineering at Stanford university.
Fan and his colleagues at the University of Illinois-Urbana Champaign (Illinois) and North carolina State university collaborated on the project.
A typical solar cell has a silicon semiconductor that absorbs sunlight directly and converts it into electrical energy.
But silicon semiconductors only respond to infrared light. Higher energy light waves including most of the visible light spectrum are wasted as heat
while lower energy waves simply pass through the solar panel. n theory conventional single-junction solar cells can only achieve an efficiency level of about 34 percent
but in practice they don t achieve thatsays study co-author Paul Braun a professor of materials science at Illinois. hat s
because they throw away the majority of the sun s energy. hermophotovoltaic devices are designed to overcome that limitation.
Instead of sending sunlight directly to the solar cell thermophotovoltaic systems have an intermediate component that consists of two parts:
which is beamed then to the solar cell. ssentially we tailor the light to shorter wavelengths that are ideal for driving a solar cellfan explains. hat raises the theoretical efficiency of the cell to 80 percent
which is quite remarkable. o far thermophotovoltaic systems have achieved only an efficiency level of about 8 percent Braun notes.
which is made typically of tungsten##an abundant material also used in conventional light bulbs. ur thermal emitters have a complex three-dimensional nanostructure that has to withstand temperatures above 1800 F 1000 C to be practicalbraun says n fact the hotter
however the 3-D structure of the emitter was destroyed at temperatures of around 1800 F (1000 C). To address the problem Braun and his Illinois colleagues coated tungsten emitters in a nanolayer of a ceramic material called hafnium
When subjected to temperatures of 1800 F (1000 C) the ceramic-coated emitters retained their structural integrity for more than 12 hours.
The ceramic-coated emitters were sent to Fan and his colleagues at Stanford who confirmed that devices were still capable of producing infrared light waves that are ideal for running solar cells. hese results are unprecedentedsays former Illinois graduate student Kevin Arpin the lead author of the study. e demonstrated for the first time that ceramics
could help advance thermophotovoltaics as well other areas of research including energy harvesting from waste heat high-temperature catalysis
and electrochemical energy storage. raun and Fan plan to test other ceramic-type materials and determine if the experimental thermal emitters can deliver infrared light to a working solar cell. e ve demonstrated that the tailoring of optical properties at high temperatures is possiblebraun says. afnium
and tungsten are abundant low-cost materials and the process used to make these heat-resistant emitters
is established well. opefully these results will motivate the thermophotovoltaics community to take another look at ceramics
and other classes of materials that haven t been considered. tanford s Global climate and Energy project and the Department of energy s Light-Material Interactions in Energy conversion Center supported the work along with the National Science Foundation and the Research Triangle Solar fuels Institute.
Source: Stanford Universit
#There s a thermostat that stops neurons from spazzing out Brandeis University rightoriginal Studyposted by Leah Burrows-Brandeis on October 17 2013for the first time scientists have seen evidence in a living animal of a hermostatthat controls
with remarkable precision how often neurons fire. Neurons make new pathways and connections as our brain processes new information.
Scientists have theorized long a larger internal system monitors these individual gauges like a neural thermostat regulating average firing rates across the whole brain.
Without this thermostat they reasoned our flexible neurons would fire out of control making bad connections or none at all.
A demonstrated neural firing-rate set point opens up a whole new approach to thinking about neurological disorders such as epilepsy in
which the brain is excited too and autism in which the brain is excited not enough. f we can figure out how these set points are built we may be able to adjust them
and bring the brains of people suffering from such disorders back into balancesays Gina Turrigiano a professor at Brandeis University who led the study.
The average firing rate is regulated so well by this neural thermostat that the rates do not change between periods of sleep and wakefulness.
when the brain does most of its wiring affected largely by the environment in which the animal is being raised.
In the first 48 hours the neuronal firing rates dropped significantly from lack of external stimuli.
But within the next 48 hours those neurons rebounded back to their set-point rateâ##like a cold house heating up.
Soon the neocortical neural firing rates were the same in both hemispheres one with visual data and one without.
although the pattern of neural firing changed the rate of firing stayed exactly the same.
and wakefulnesshengen says. he other rules in the brain have to play out in the context of this tightly regulated system of locked-in average firing rates. ource:
#Shortcut lets brain make memories in a flash Mcgill University rightoriginal Studyposted by Anita Kar-Mcgill U. on October 16 2013nerve cells have a special re-assemblytechnique that enables the brain to quickly form memories.
when it s the wrong timesays Wayne Sossin a neuroscientist at the Montreal Neurological Institute and Hospital at Mcgill University and senior investigator on the paper. his is especially important with nerve cells in the brain as you only want the brain to make precise
#Drop an internet in the ocean to detect tsunamis University at Buffalo rightoriginal Studyposted by Cory Nealon-Buffalo on October 14 2013a deep-sea internet network is expected to improve the way scientists detect tsunamis monitor pollution
and analyze data from our oceans in real timesays Tommaso Melodia associate professor of electrical engineering at the University at Buffalo
and the projectâ#lead researcher. aking this information available to anyone with a smartphone or computer especially when a tsunami or other type of disaster occurs could help save lives. elodia will present his paper at the Association for Computing Machineryâ
Land-based wireless networks rely on radio waves that transmit data via satellites and antennae. Unfortunately radio waves work poorly underwaterâ
##which is why agencies like the Navy and National oceanic and atmospheric administration use sound wave-based techniques to communicate underwater.
For example NOAA relies on acoustic waves to send data from tsunami sensors on the sea floor to surface buoys.
The buoys convert the acoustic waves into radio waves to send the data to a satellite which then redirects the radio waves back to land-based computers.
but sharing data between them is difficult because each system often has a different infrastructure.
The new framework will solve that problem by transmitting data from existing and planned underwater sensor networks to laptops smartphones and other wireless devices in real time.
Melodia tested the system recently in Lake erie a few miles south of downtown Buffalo. Hovannes Kulhandjian and Zahed Hossain both doctoral candidates in his lab dropped two 40-pound sensors into the water.
Kulhandjian typed a command into a laptop. Seconds later a series of high-pitched chirps ricocheted off a nearby concrete wall an indication that the test worked.
A deep-sea internet has many applications Melodia says including linking together buoy networks that detect tsunamis.
In these situations it could deliver a more reliable warning thereby increasing the odds that coastal residents can evacuate.
It may also help collect oceanographic data and monitoring pollution. The framework will encourage collaboration among researchers
and potentially eliminate the duplicative deployments of sensors and other equipment he says. There are also military and law enforcement applications.
For example drug smugglers recently have deployed makeshift submarines to clandestinely ferry narcotics long distances underwater. An improved more robust underwater sensor network could help spot these vessels.
The framework could also be useful to the energy industry which typically relies on seismic waves to search for underwater oil and natural gas.
Industryâ#efforts could be aided by network of interconnected devices working together. e could even use it to monitor fish
and marine mammals and find out how to best protect them from shipping traffic and other dangersmelodia says. n internet underwater has so many possibilities. ource:
University at Buffaloyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license o
#Tiny water sensor embedded in plant stems Cornell University Posted by Krishna Ramanujan-Cornell on October 14 2013researchers are completing soil tests on a water sensor within a fingertip-sized silicon chip
and will soon test it in plants embedding their ab on a chipin the stems of grape vines for example.
They hope to mass produce the sensors for as little as $5 each. Crop growers wine grape and other fruit growers food processors and even concrete makers all benefit from water sensors for accurate steady and numerous moisture readings.
But current sensors are large may cost thousands of dollars and often must be read manually.
The new chip which is a hundred times more sensitive than current devices is fitted with wires that can be hooked up to a card for wireless data transmission
or is compatible with existing dataloggers. Chips may be left in place for years though they may break in freezing temperatures.
Such inexpensive and accurate sensors can be spaced strategically in plants and soil for accurate measurements in agricultural fields.
For example sophisticated vintners use precise irrigation to put regulated water stress on grapevines to create just the right grape composition for a premium cabernet or a chardonnay wine.
While growers can use the sensors to monitor water in soils for their crops civil engineers can embed the chips in concrete to determine optimal moisture levels as the concrete cures. ne of our goals is to try
and develop something that is not only a great improvement but also much cheaper for growers and others to usesays Alan Lakso professor of horticulture at Cornell University.
The sensors make use of microfluidic technologyâ##developed by Abraham Stroock associate professor of chemical and biomolecular engineeringâ##that places a tiny cavity inside the chip.
The cavity is filled with water and then the chip may be inserted in a plant stem or in the soil where it through a nanoporous membrane exchanges moisture with its environment and maintains an equilibrium pressure that the chip measures.
Using chips embedded in plants or spaced across soil and linked wirelessly to computers allows growers toâ ontrol the precise moisture of blocks of land based on target goalssays Vinay Pagay who helped develop the chip as a doctoral student in Lakso s lab
. The Cornell Center for Technology Enterprise and Commercialization is handling the intellectual property rights and patents.
Source: Cornell Universityyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license
#Nanoribbon material keeps gases captive Rice university rightoriginal Studyposted by Mike Williams-Rice on October 11 2013an enhanced polymer could make vehicles that run on compressed natural gas more practical and even prolong the shelf life of bottled beer
and soda. The material is more impermeable to pressurized gas and far lighter than the metal in tanks now used to contain the gas say researchers.
Rice university chemist James Tour and colleagues report their results this week in the online edition of ACS Nano.
By adding modified single-atom-thick graphene nanoribbons (GNRS) to thermoplastic polyurethane (TPU) the team at Rice made it 1000 times harder for gas molecules to escape Tour says.
That s due to the ribbons even dispersion through the material. Because gas molecules cannot penetrate GNRS they are faced with a ortuous pathto freedom he says.
The researchers acknowledge that a solid two-dimensional sheet of graphene might be the perfect barrier to gas
but the production of graphene in such bulk quantities is not yet practical Tour says. But graphene nanoribbons are already there.
Tour s breakthrough nzippingtechnique for turning multiwalled carbon nanotubes into GNRS first revealed in Nature in 2009 has been licensed for industrial production. hese are being produced in bulk
The researchers led by Rice graduate student Changsheng Xiang produced thin films of the composite material by solution casting GNRS treated with hexadecane and TPU a block copolymer of polyurethane that combines hard and soft materials.
But the overlapping 200-to 300-nanometer-wide ribbons dispersed so well that they were nearly as effective as large-sheet graphene in containing gas molecules.
The GNRS geometry makes them far better than graphene sheets for processing into composites Tour says.
Stress and strain tests also found that the 0. 5 percent ratio was optimal for enhancing the polymer s strength. he idea is to increase the toughness of the tank
and make it impermeable to gastour says. his becomes increasingly important as automakers think about powering cars with natural gas.
Metal tanks that can handle natural gas under pressure are often much heavier than the automakers would like. e says the material could help to solve longstanding problems in food packaging too. emember
when you were a kid you d get a balloon and it would be wilted the next day?
but a glass bottle until they figured out how to modify plastic to contain the carbon dioxide bubbles.
And even now bottled soda goes flat after a period of months. eer has a bigger problem
and in some ways it s the reverse problemhe says. xygen molecules get in through plastic and make the beer go bad.
University of Ljubljana Slovenia; University of Szeged Hungary; and Cochin University of Science and Technology India.
The Air force Research Laboratory through the University Technology Corp. the Office of Naval Research MURI graphene program and the Air force Office of Scientific research MURI program supported the research.
Source: Rice Universityyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license u
#Signs of water detected in exoplanet s debris University of Warwick rightoriginal Studyposted by Anna Blackaby-Warwick on October 11 2013the remains of a water-rich rocky exoplanet have been discovered outside
our solar system orbiting a white dwarf star 170 light years away. Using observations obtained with the Hubble Space Telescopeâ
and debris that has been pulled into the orbit of its dying parent starâ#says Boris Gänsicke professor of physics at the University of Warwick. owever this planetary graveyard swirling around the embers of its parent star is a rich source
The finding of water in a large asteroid means the building blocks of habitable planets existedâ ##and maybe still existâ##in the GD 61 system and likely also around substantial number of similar parent starssays lead author Jay Farihi from the Institute of Astronomy at the University of Cambridge. hese water-rich building blocks
and the terrestrial planets they build may in fact be commonâ##a system cannot create things as big as asteroids
. or their analysis the researchers used ultraviolet spectroscopy data obtained with the Cosmic Origins Spectrograph on board the Hubble space telescope of the white dwarf GD 61.
As the atmosphere of the Earth blocks the ultraviolet light such study can only be carried out from space.
The Hubble and Keck data allows the researchers to identify the different chemical elements that are polluting the outer layers white dwarf.
Using a sophisticated computer model of the white dwarf atmosphere developed by Detlev Koester at the University of Kiel they were able to infer the chemical composition of the shredded minor planet.
University of Warwickyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license h
#rtificial nose detects dangerous vapors Researchers have developed a way to sniff out solvent gases by combining a common mineral zeolite with a metallic compound based on rhenium.
The challenge for Angel Mart assistant professor of chemistry and bioengineering at Rice university and his team of student researchers was to get their large metallic particles through the much smaller pores of a zeolite cage.
but when they self-assemble inside the zeolite they re trapped. Once washed to eliminate complexes that form outside the zeolites the compound is ready for use.
The study is published in the journal Angewandte Chemie. The relatively simple technique which two undergraduate alumni initially developed
and studied could provide a scalable inexpensive platform to monitor toxic vapors from industrial solvents.
Solvents are liquid chemicals often petroleum-based that are used widely to dissolve solid materials. They are found in paints thinners aerosol sprays dyes marking pens adhesives and other products.
and gases can t interact with themhe says. o we started thinking of ways to create space between them. nter zeolites. hese zeolites are cages with big cavities
The question was how to trap the bigger rhenium complexes inside. ther groups have trapped ruthenium complexes in zeolites
Then researchers developed the method to put rhenium complexes inside zeolites. The results were outstanding Mart says.
to detect three distinct characteristics for each vapor a team led by graduate student Avishek Saha built a 3d plot to map the fingerprints of 17 types of solvents.
#Gene keeps wheat from sprouting on the stalk A new way to keep high humidity from damaging wheat crops could save farmers millions of dollars
This phenomenon pre-harvest sprouting or PHS has such important economic repercussions for farmers around the world that scientists have been working on finding a solution to the problem for decades.
and on the interaction between genotypes and the environment as they have tried to breed wheat that is resistant to PHS but with little success so far.
But now findings published in the journal PLOS ONE suggest that the solution may lie not with genetics alone but rather with a combination of genetic and epigenetic factors.
A team of researchers led by Professor Jaswinder Singh of Mcgill University s Department of Plant science has identified a key gene that acts as a switch to determine how a particular plant will respond to high humidity
he complex Rddm machinery is composed of several proteins that guide the genome in response to growth developmental and stress signals.
versus PHS susceptible varieties of wheat. his discovery is important for other cereals like barley as well as for wheatsays Surinder Singh a doctoral student
and one of the authors of the study currently working in Professor Singh s laboratory. his means that not only should we be able to avoid the ugly bread
It should also save farmers and governments around the world significant amounts of money in the future.
#Lava pillars in Iceland may have formed without a boom University at Buffalo rightoriginal Studyposted by Charlotte Hsu-Buffalo on October 9 2013land-based lava pillars in Iceland may have formed through an unusual reaction typically seen
That finding is more likely than the one that suggests the rocky pillars dotting Icelandâ#Skaelingar valley were tossed projectiles into the fields by warring trollsâ##a theory University at Buffalo geologist Tracy Gregg heard from a tour guide and local hiker.
and made from basalt likely formed in a surprising reaction where lava met water without any explosion occurring. sually
when lava and water meet in aerial environments the water instantly flashes to steamsays Gregg associate professor of geology. hatâ#a volume increase of eight timesâ##boom.?
This has implications for the way we view volcanic risk. eep-sea basalt pillars form
and remain standing even after volcanic eruptions end and lava levels fall again. In a new study published in the Journal of Volcanology
so slowlyâ##centimeters per secondâ##that it was able to react with the water in a inder gentlermanner. f youâ##re driving your car at 5 miles per hour
if you hit that same stop sign at 40 miles an hourgregg says. hereâ#a lot more energy that will be released. he Iceland formations some over 2 meters tall display telltale features that hint at how they were created.
so I was just hysterical saying â##Look at these!''n the future Gregg says scientists could hunt for land-based lava pillars near oceans to learn about the height of ancient seas
University at Buffaloyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license i
#At super high temps, white graphene stops rust Atomically thin sheets of hexagonal boron nitride (h-BN) have the handy benefit of protecting
materialsays Jun Lou an associate professor of mechanical engineering and materials science at Rice university. verybody has been talking about these materials for electronic
or photonic devices but if this can be realized on a large scale it'#going to cover a broad spectrum of applications. ltrathin h-BN protection might find a place in turbines jet engines oil exploration
and underwater or in other harsh environments where minimal size and weight would be an advantage.
Wear and abrasion could become an issue the researcher say and optimum thicknesses need to be worked out for specific applications.
which may make it useful for protecting solar cells from the elements Lou says. ssentially this can be a very useful structural material coating
and found it withstood high temperature in an oxygen-rich environment. They also grew h-BN on graphene
and steel with similar results. hat's amazing is that these layers are ultra thin
and they stand up to such ultrahigh temperaturessays Pulickel Ajayan professor of mechanical engineering and materials science and of chemistry. t a few nanometers wide they'##re a totally noninvasive coating.
They take almost no space at all. ther researchers from Rice university the University of Texas at Austin Oak ridge National Laboratory
and the National University of Singapore contributed to the study which was supported by Army Research Office the Office of Naval Research the Welch Foundation the Korean Institute of Machinery and Materials the National Science Foundation Oak ridge National Laboratory and the Department of energy.
Source:
#Chemical program controls synthetic DNA California Institute of technology University of Washington rightoriginal Studyposted by Michelle Ma-Washington on October 7 2013soon chemists could use a structured set of instructions##like using Python
or Java##to rogramhow DNA molecules interact in a test tube or cell. A team has developed a programming language for chemistry that it hopes will streamline efforts to design a network that can guide the behavior of chemical-reaction mixtures in the same way that embedded electronic controllers guide cars robots and other devices.
In medicine such networks could serve as martdrug deliverers or disease detectors at the cellular level.
The findings are published in Nature Nanotechnology. Chemists and educators teach and use chemical reaction networks a century-old language of equations that describes how mixtures of chemicals behave.
The engineers take this language a step further and use it to write programs that direct the movement of tailor-made molecules. e start from an abstract mathematical description of a chemical system
and then use DNA to build the molecules that realize the desired dynamicssays corresponding author Georg Seelig am assistant professor of electrical engineering
and of computer science and engineering at the University of Washington. he vision is that eventually you can use this technology to build general-purpose tools. urrently
when a biologist or chemist makes a certain type of molecular network the engineering process is complex cumbersome and hard to repurpose for building other systems.
The engineers wanted to create a framework that gives scientists more flexibility. Seelig likens this new approach to programming languages that tell a computer what to do. think this is appealing
because it allows you to solve more than one problemseelig says. f you want a computer to do something else you just reprogram it.
This project is very similar in that we can tell chemistry what to do. umans and other organisms already have complex networks of nano-sized molecules that help to regulate cells and keep the body in check.
Scientists now are finding ways to design synthetic systems that behave like biological ones with the hope that synthetic molecules could support the body s natural functions.
To that end a system is needed to create synthetic DNA molecules that vary according to their specific functions.
The new approach isn t ready to be applied in the medical field but future uses could include using this framework to make molecules that self-assemble within cells
and serve as martsensors. These could be embedded in a cell then programmed to detect abnormalities
and respond as needed perhaps by delivering drugs directly to those cells. Additional co-authors of the paper contributed from University of Washington;
University of California San francisco; California Institute of technology; and Microsoft Research. The National Science Foundation the Burroughs Wellcome Fund and the National Centers for Systems Biology supported the research.
Source: University of Washingto h
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