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News Article | May 25, 2017
Site: www.eurekalert.org

Water is the Earth's most abundant natural resource, but it's also something of a mystery due to its unique solvation characteristics -- that is, how things dissolve in it. "It's uniquely adapted to biology, and vice versa," said Poul Petersen, assistant professor of chemistry and chemical biology at Cornell University. "It's super-flexible. It dissipates energy and mediates interactions, and that's becoming more recognized in biological systems." How water relates to and interacts with those systems -- like DNA, the building block of all living things -- is of critical importance, and Petersen's group has used a relatively new form of spectroscopy to observe a previously unknown characteristic of water. "DNA's chiral spine of hydration," published May 24 in the American Chemical Society journal Central Science, reports the first observation of a chiral water superstructure surrounding a biomolecule. In this case, the water structure follows the iconic helical structure of DNA, which itself is chiral, meaning it is not superimposable on its mirror image. Chirality is a key factor in biology, because most biomolecules and pharmaceuticals are chiral. "If you want to understand reactivity and biology, then it's not just water on its own," Petersen said. "You want to understand water around stuff, and how it interacts with the stuff. And particularly with biology, you want to understand how it behaves around biological material -- like protein and DNA." Water plays a major role in DNA's structure and function, and its hydration shell has been the subject of much study. Molecular dynamics simulations have shown a broad range of behaviors of the water structure in DNA's minor groove, the area where the backbones of the helical strand are close together. The group's work employed chiral sum frequency generation spectroscopy (SFG), a technique Petersen detailed in a 2015 paper in the Journal of Physical Chemistry. SFG is a nonlinear optical method in which two photon beams -- one infrared and one visible -- interact with the sample, producing an SFG beam containing the sum of the two beams' frequencies, or energies. In this case, the sample was a strand of DNA linked to a silicon-coated prism. More manipulation of the beams and calculation proved the existence of a chiral water superstructure surrounding DNA. In addition to the novelty of observing a chiral water structure template by a biomolecule, chiral SFG provides a direct way to examine water in biology. "The techniques we have developed provide a new avenue to study DNA hydration, as well as other supramolecular chiral structures," Petersen said. The group admits that their finding's biological relevance is unclear, but Petersen thinks the ability to directly examine water and its behavior within biological systems is important. "Certainly, chemical engineers who are designing biomimetic systems and looking at biology and trying to find applications such as water filtration would care about this," he said. Another application, Petersen said, could be in creating better anti-biofouling materials, which are resistant to the accumulation of microorganisms, algae and the like on wetted surfaces. Collaborators included M. Luke McDermott; Heather Vanselous, a doctoral student in chemistry and chemical biology and a member of the Petersen Group; and Steven Corcelli, professor of chemistry and biochemistry at the University of Notre Dame. This work was supported by grants from the National Science Foundation and the Arnold and Mable Beckman Foundation, and made use of the Cornell Center for Materials Research, an NSF Materials Research Science and Engineering Center.


News Article | May 25, 2017
Site: phys.org

"It's uniquely adapted to biology, and vice versa," said Poul Petersen, assistant professor of chemistry and chemical biology. "It's super-flexible. It dissipates energy and mediates interactions, and that's becoming more recognized in biological systems." How water relates to and interacts with those systems – like DNA, the building block of all living things – is of critical importance, and Petersen's group has used a relatively new form of spectroscopy to observe a previously unknown characteristic of water. "DNA's chiral spine of hydration," published May 24 in the American Chemical Society journal Central Science, reports the first observation of a chiral water superstructure surrounding a biomolecule. In this case, the water structure follows the iconic helical structure of DNA, which itself is chiral, meaning it is not superimposable on its mirror image. Chirality is a key factor in biology, because most biomolecules and pharmaceuticals are chiral. "If you want to understand reactivity and biology, then it's not just water on its own," Petersen said. "You want to understand water around stuff, and how it interacts with the stuff. And particularly with biology, you want to understand how it behaves around biological material – like protein and DNA." Water plays a major role in DNA's structure and function, and its hydration shell has been the subject of much study. Molecular dynamics simulations have shown a broad range of behaviors of the water structure in DNA's minor groove, the area where the backbones of the helical strand are close together. The group's work employed chiral sum frequency generation spectroscopy (SFG), a technique Petersen detailed in a 2015 paper in the Journal of Physical Chemistry. SFG is a nonlinear optical method in which two photon beams – one infrared and one visible – interact with the sample, producing an SFG beam containing the sum of the two beams' frequencies, or energies. In this case, the sample was a strand of DNA linked to a silicon-coated prism. More manipulation of the beams and calculation proved the existence of a chiral water superstructure surrounding DNA. In addition to the novelty of observing a chiral water structure template by a biomolecule, chiral SFG provides a direct way to examine water in biology. "The techniques we have developed provide a new avenue to study DNA hydration, as well as other supramolecular chiral structures," Petersen said. The group admits that their finding's biological relevance is unclear, but Petersen thinks the ability to directly examine water and its behavior within biological systems is important. "Certainly, chemical engineers who are designing biomimetic systems and looking at biology and trying to find applications such as water filtration would care about this," he said. Another application, Petersen said, could be in creating better anti-biofouling materials, which are resistant to the accumulation of microorganisms, algae and the like on wetted surfaces. Explore further: An interesting twist on supercooled liquid water


News Article | May 29, 2017
Site: www.sciencedaily.com

Water is Earth's most abundant natural resource, but it's also something of a mystery due to its unique solvation characteristics -- that is, how things dissolve in it. "It's uniquely adapted to biology, and vice versa," said Poul Petersen, assistant professor of chemistry and chemical biology at Cornell University. "It's super-flexible. It dissipates energy and mediates interactions, and that's becoming more recognized in biological systems." How water relates to and interacts with those systems -- like DNA, the building block of all living things -- is of critical importance, and Petersen's group has used a relatively new form of spectroscopy to observe a previously unknown characteristic of water. "DNA's chiral spine of hydration," published May 24 in the American Chemical Society journal Central Science, reports the first observation of a chiral water superstructure surrounding a biomolecule. In this case, the water structure follows the iconic helical structure of DNA, which itself is chiral, meaning it is not superimposable on its mirror image. Chirality is a key factor in biology, because most biomolecules and pharmaceuticals are chiral. "If you want to understand reactivity and biology, then it's not just water on its own," Petersen said. "You want to understand water around stuff, and how it interacts with the stuff. And particularly with biology, you want to understand how it behaves around biological material -- like protein and DNA." Water plays a major role in DNA's structure and function, and its hydration shell has been the subject of much study. Molecular dynamics simulations have shown a broad range of behaviors of the water structure in DNA's minor groove, the area where the backbones of the helical strand are close together. The group's work employed chiral sum frequency generation spectroscopy (SFG), a technique Petersen detailed in a 2015 paper in the Journal of Physical Chemistry. SFG is a nonlinear optical method in which two photon beams -- one infrared and one visible -- interact with the sample, producing an SFG beam containing the sum of the two beams' frequencies, or energies. In this case, the sample was a strand of DNA linked to a silicon-coated prism. More manipulation of the beams and calculation proved the existence of a chiral water superstructure surrounding DNA. In addition to the novelty of observing a chiral water structure template by a biomolecule, chiral SFG provides a direct way to examine water in biology. "The techniques we have developed provide a new avenue to study DNA hydration, as well as other supramolecular chiral structures," Petersen said. The group admits that their finding's biological relevance is unclear, but Petersen thinks the ability to directly examine water and its behavior within biological systems is important. "Certainly, chemical engineers who are designing biomimetic systems and looking at biology and trying to find applications such as water filtration would care about this," he said. Another application, Petersen said, could be in creating better anti-biofouling materials, which are resistant to the accumulation of microorganisms, algae and the like on wetted surfaces.


News Article | May 25, 2017
Site: www.sciencedaily.com

Chemists at Ruhr-Universität Bochum have developed a new method that allows them to map changes in the dynamics and structure of water molecules in the vicinity of solutes. With this technique, called terahertz calorimetry, they investigated the properties of the hydration shell of dissolved alcohol molecules. In the future, they want to also use the method for water mapping around more complex systems such as enzymes, which can be important for drug design. The results were published by Prof Dr Martina Havenith, chair for Physical Chemistry II and spokeswoman for the cluster of excellence Resolv, with Dr Fabian Böhm and Dr Gerhard Schwaab in the journal Angewandte Chemie. Method can now be applied in real time Fundamental biological processes such as enzymatic catalysis or molecular binding occur in aqueous phase. Calorimetry serves as a powerful biophysical tool to study the molecular recognition and stability of biomolecular systems by measuring changes in thermodynamic state variables, e.g. upon protein folding or association, for the purpose of deriving the heat transfer associated with these changes. Calorimetry determines, enthalpy and entropy, which are measures of the heat transfer and disorder in the system. Calorimetry is restricted to timescales of 1 to 100 seconds. In contrast, spectroscopic processes, which are based on short laser pulses, are able to perform measurements on the time scale of a millionth or a billionth of a second. The Bochum-based chemists showed that both approaches are complementary. "By establishing a terahertz calorimeter in a proof of concept experiment, we have achieved the first aim that we had been working on using the Advanced Grant funds from the European Research Council," explains Martina Havenith. In 2016, she was awarded the grant endowed with 2.5 million euros. Determining the structure of the watery envelopes A shell of surrounding water molecules, the hydration shell, forms around any dissolved molecule. The solute affects the regular network of hydrogen bridges between the water molecules, causing the water in the hydration shell to behave differently to the free water. The structure of the hydration shell depends on the shape and the chemical composition of the dissolved molecule. Havenith's team investigated the hydration shell of five different alcohol chains and were able to classify differently structured hydration water by terahertz calorimetry. Exposure to terahertz pulses provides fingerprints of the vibrations within the water network. This, in turn, allows the researchers to deduce fundamental quantities such as entropy and enthalpy. "The method allows us for the first time to spectroscopically map entropy and enthalpy around solutes, which are crucial parameters to characterize molecular recognition," summarises Havenith.


News Article | May 11, 2017
Site: www.eurekalert.org

Chemists have discovered that tiny particulate matter called aerosols lofted into the atmosphere by sea spray and the bursting of bubbles at the ocean's surface are chemically altered by the presence of biological activity. Their finding, published in this week's issue of the journal Chem, is a critical discovery that should improve the accuracy of future atmospheric and climate models. "Simply put, most atmospheric and climate models assume sea spray aerosol particles are made of pure salt," said Vicki Grassian, a UC San Diego chemistry and biochemistry professor who headed the study, which included scientists at the University of Iowa, University of Wisconsin, UC Davis and Pacific Northwest National Laboratory in Richland, WA. "Our results show that these particles are much more complex in terms of what they are made of, and that this pure salt assumption is a bad one." "Biological activity in the water, which we measured by the amount of chlorophyll and bacteria present," she added, "play a big role in the what sea spray aerosols are, in fact, composed of--that is, mixtures of salts, organic compounds and biological components." The scientists noted in a paper detailing their results that one of the key factors in developing more accurate climate models is a better understanding of the chemical composition and diversity of sea spray aerosol particles. "We wanted to understand their climate properties, including 'hygroscopicity'--the ability to take up water, increase their size as a function of relative humidity and to form clouds," said Grassian, who holds the Distinguished Chair of Physical Chemistry in the Department of Chemistry and Biochemistry and is an associate dean in UC San Diego's Division of Physical Sciences. She is also a Distinguished Professor in the Department of Nanoengineering and at Scripps Institution of Oceanography. By increasing humidity and lofting particles into the atmosphere that can either reflect sunlight during the daylight hours or limit heat loss at night, sea spray aerosols as well as mineral dust are believed to have a major contributing effect on climate. To determine how biological activity impacted sea spray aerosols, scientists at UC San Diego's Center for Aerosol Impacts on Climate and the Environment, including Kimberly Prather, the director of the center and a professor of chemistry and biochemistry, used a unique wave flume facility located at Scripps Institution of Oceanography that allowed them to analyze the molecular composition of individual sea spray aerosol particles during different stages of a phytoplankton bloom. High-resolution mass spectrometry experiments at the Pacific Northwest National Laboratory also enabled the researchers to determine the major classes of organic molecules that make up the sea spray aerosol molecules as the biological conditions changed during the simulated phytoplankton bloom. Other coauthors of the study were (from UC San Diego) Richard Cochran, Jonathan Trueblood, Armando D. Estillore, Camille M. Sultana, Christopher Lee and Kimberly Prather; (from University of Iowa) Olga Laskina, Holly Morris, Thilina Jayarathne, Jacqueline Dowling, Alexi Tivanski, Zhen Qin and Elizabeth Stone; Pacific Northwest National Laboratory scientists Peng Lin, Julia Laskin and Alexander Laskin; UC Davis scientist Christopher Cappa; and Timothy Bertram of the University of Wisconsin-Madison. The study was funded by a grant from the National Science Foundation through the Center for Aerosol Impacts on Climate and the Environment (CHE 1305427).


DB Labs has hired Ben Chew to help oversee lab operations, including safety and regulatory compliance for their Las Vegas-based marijuana testing laboratory. Dr. Chew completed his PhD in Physical Chemistry at Cornell University before becoming a postdoctoral fellow at Georgetown University Medical Center. He brings 20 years of industrial chemistry experience working in and managing a variety of analytical chemistry laboratories to the DB Labs team. “We are thrilled that Ben chose to join the qualified team of DB Labs,” Susan Bunce, the DB Lab President stated. “He represents the integrity and leadership that we value as a company. We strive to continually improve the laboratory for the safety of the consumers, which was my primary concern when we interviewed candidates. I feel that Ben is a great addition to our already experienced management staff, including Kelly Zaugg and Glen Marquez.” In his role at DB Labs, Dr. Chew will be responsible for developing employees, adhering to state and county regulations, providing high-quality analytical results to clients, and managing daily operations for the cannabis testing laboratory. When asked why he chose DB Labs, Dr. Chew replied, “In the two years I have been in this industry, I have collaborated with them. They made it clear that they are a lab that takes accuracy and patient safety seriously.” About DB Labs: Located in Las Vegas, Nevada, DB Labs is an independent analytical testing laboratory specializing in organic, inorganic, and microbiological analyses. We take pride knowing our stringent cannabis analyses are of the highest quality. Founded in 2014, DB Labs is committed to meeting industry needs with the highest level of service. To learn more about DB Labs and its safe testing practices, contact DB Labs at Test@DBLabsLV.com.


Home > Press > 'Hot' electrons don't mind the gap: Rice University scientists find nanogaps in plasmonic gold wires enhance voltage when excited Abstract: If they're quick about it, "hot" electrons excited in a plasmonic metal can tunnel their way across a nanoscale gap to a neighboring metal. Rice University scientists said the cool part is what happens in the gap. A Rice team discovered those electrons can create a photovoltage about a thousand times larger than what is seen if there is no gap. The finding shows it should be possible to create nanoscale photodetectors that convert light into electricity and can be used as sensors or in other sophisticated electronics. Results from the Rice lab of condensed matter physicist Douglas Natelson appear in the American Chemical Society's Journal of Physical Chemistry Letters. Natelson's lab studies the electronic, magnetic and optical properties of nanoscale structures, often by testing the properties of systems that can only be viewed under a microscope. Some studies involve whole gold nanowires, and sometimes the lab breaks the wire to form a gap of just a few nanometers (billionths of a meter). One goal is to understand whether and how electrons leap the nanogap under various conditions, like ultracold temperatures. While looking at such structures, the researchers found themselves studying the nanoscale characteristics of what's known as the Seebeck (thermoelectric) effect, discovered in 1821, in which heat is converted to electricity at the junction of two wires of different metals. Seebeck discovered that a voltage would form across a single conductor when one part is hotter than the other. "If you want to make thermostats for your house or your car climate control, this is how you do it," Natelson said. "You join together two dissimilar metals to make a thermocouple, and stick that junction where you want to measure the temperature. Knowing the difference between the Seebeck coefficients of the metals and measuring the voltage across the thermocouple, you can work backward from that to get the temperature." To see how it works in a single metal on the nanoscale, Natelson, lead author and former postdoctoral researcher Pavlo Zolotavin and graduate student Charlotte Evans used a laser to induce a temperature gradient across a bowtie-shaped gold nanowire. That created a small voltage, consistent with the Seebeck effect. But with a nanogap splitting the wire, "the data made clear that a different physical mechanism is at work," they wrote. Gold is a plasmonic metal, one of a class of metals that can respond to energy input from a laser or other source by exciting plasmons on their surfaces. Plasmon excitations are the back-and-forth sloshing of electrons in the metal, like water in a basin. This is useful, Natelson explained, because oscillating plasmons can be detected. Depending on the metal and its size and shape, these plasmons may only show up when prompted by light at a particular wavelength. In the bowties, laser light absorbed by the plasmons created hot electrons that eventually transferred their energy to the atoms in the metal, vibrating them as well. That energy is dissipated as heat. In continuous, solid wires, the temperature difference caused by the laser also created small voltages. But when nanogaps were present, the hot electrons passed through the void and created much larger voltages before dispersing. "It's a neat result," Natelson said. "The main points are, first, that we can tune the thermoelectric properties of metals by structuring them on small scales, so that we can make thermocouples out of one material. Second, a focused laser can act as a scannable, local heat source, letting us map out those effects. Shining light on the structure produces a small photovoltage. "And third, in structures with truly nanoscale tunneling gaps (1-2 nanometers), the photovoltage can be a thousand times larger, because the tunneling process effectively uses some of the high-energy electrons before their energy is lost to heat," he said. "This has potential for photodetector technologies and shows the potential that can be realized if we can use hot electrons before they have a chance to lose their energy." Gold seems to be the best metal to show the effect so far, Natelson said, as control experiments with gold-palladium and nickel nanogapped wires did not perform as well. The researchers acknowledge several possible reasons for the dramatic effect, but they strongly suspect tunneling by the photo-generated hot carriers is responsible. "You don't need plasmons for this effect, because any absorption, at least in a short time, is going to generate these hot carriers," Zolotavin said. "However, if you've got plasmons, they effectively increase the absorption. They interact with light very strongly, and the effect gets bigger because the plasmons make the absorption bigger." ### Natelson is a professor of physics and astronomy, of electrical and computer engineering and of materials science and nanoengineering, and chair of the Rice Department of Physics and Astronomy. Zolotavin, a former postdoctoral researcher in Natelson's lab, is now a scientist with Lam Research. The U.S. Army Research Office, the Robert A. Welch Foundation and the National Science Foundation supported the research. About Rice University Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.com/RiceUniversityoverview . Follow Rice News and Media Relations via Twitter @RiceUNews For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article | May 9, 2017
Site: www.cemag.us

If they’re quick about it, “hot” electrons excited in a plasmonic metal can tunnel their way across a nanoscale gap to a neighboring metal. Rice University scientists said the cool part is what happens in the gap. A Rice team discovered those electrons can create a photovoltage about a thousand times larger than what is seen if there is no gap. The finding shows it should be possible to create nanoscale photodetectors that convert light into electricity and can be used as sensors or in other sophisticated electronics. Results from the Rice lab of condensed matter physicist Douglas Natelson appear in the American Chemical Society’s Journal of Physical Chemistry Letters. Natelson’s lab studies the electronic, magnetic and optical properties of nanoscale structures, often by testing the properties of systems that can only be viewed under a microscope. Some studies involve whole gold nanowires, and sometimes the lab breaks the wire to form a gap of just a few nanometers (billionths of a meter). One goal is to understand whether and how electrons leap the nanogap under various conditions, like ultracold temperatures. While looking at such structures, the researchers found themselves studying the nanoscale characteristics of what’s known as the Seebeck (thermoelectric) effect, discovered in 1821, in which heat is converted to electricity at the junction of two wires of different metals. Seebeck discovered that a voltage would form across a single conductor when one part is hotter than the other. “If you want to make thermostats for your house or your car climate control, this is how you do it,” Natelson says. “You join together two dissimilar metals to make a thermocouple, and stick that junction where you want to measure the temperature. Knowing the difference between the Seebeck coefficients of the metals and measuring the voltage across the thermocouple, you can work backward from that to get the temperature.” To see how it works in a single metal on the nanoscale, Natelson, lead author and former postdoctoral researcher Pavlo Zolotavin and graduate student Charlotte Evans used a laser to induce a temperature gradient across a bowtie-shaped gold nanowire. That created a small voltage, consistent with the Seebeck effect. But with a nanogap splitting the wire, “the data made clear that a different physical mechanism is at work,” they write. Gold is a plasmonic metal, one of a class of metals that can respond to energy input from a laser or other source by exciting plasmons on their surfaces. Plasmon excitations are the back-and-forth sloshing of electrons in the metal, like water in a basin. This is useful, Natelson explains, because oscillating plasmons can be detected. Depending on the metal and its size and shape, these plasmons may only show up when prompted by light at a particular wavelength. In the bowties, laser light absorbed by the plasmons created hot electrons that eventually transferred their energy to the atoms in the metal, vibrating them as well. That energy is dissipated as heat. In continuous, solid wires, the temperature difference caused by the laser also created small voltages. But when nanogaps were present, the hot electrons passed through the void and created much larger voltages before dispersing. “It’s a neat result,” Natelson says. “The main points are, first, that we can tune the thermoelectric properties of metals by structuring them on small scales, so that we can make thermocouples out of one material. Second, a focused laser can act as a scannable, local heat source, letting us map out those effects. Shining light on the structure produces a small photovoltage. “And third, in structures with truly nanoscale tunneling gaps (1 to 2 nanometers), the photovoltage can be a thousand times larger, because the tunneling process effectively uses some of the high-energy electrons before their energy is lost to heat,” he says. “This has potential for photodetector technologies and shows the potential that can be realized if we can use hot electrons before they have a chance to lose their energy.” Gold seems to be the best metal to show the effect so far, Natelson says, as control experiments with gold-palladium and nickel nanogapped wires did not perform as well. The researchers acknowledge several possible reasons for the dramatic effect, but they strongly suspect tunneling by the photo-generated hot carriers is responsible. “You don’t need plasmons for this effect, because any absorption, at least in a short time, is going to generate these hot carriers,” Zolotavin says. “However, if you’ve got plasmons, they effectively increase the absorption. They interact with light very strongly, and the effect gets bigger because the plasmons make the absorption bigger.” Natelson is a professor of physics and astronomy, of electrical and computer engineering and of materials science and nanoengineering, and chair of the Rice Department of Physics and Astronomy. Zolotavin, a former postdoctoral researcher in Natelson’s lab, is now a scientist with Lam Research. The U.S. Army Research Office, the Robert A. Welch Foundation and the National Science Foundation supported the research.


News Article | February 15, 2017
Site: www.eurekalert.org

Wearable electronics are here -- the most prominent versions are sold in the form of watches or sports bands. But soon, more comfortable products could become available in softer materials made in part with an unexpected ingredient: green tea. Researchers report in ACS' The Journal of Physical Chemistry C a new flexible and compact rechargeable energy storage device for wearable electronics that is infused with green tea polyphenols. Powering soft wearable electronics with a long-lasting source of energy remains a big challenge. Supercapacitors could potentially fill this role -- they meet the power requirements, and can rapidly charge and discharge many times. But most supercapacitors are rigid, and the compressible supercapacitors developed so far have run into roadblocks. They have been made with carbon-coated polymer sponges, but the coating material tends to bunch up and compromise performance. Guruswamy Kumaraswamy, Kothandam Krishnamoorthy and colleagues wanted to take a different approach. The researchers prepared polymer gels in green tea extract, which infuses the gel with polyphenols. The polyphenols converted a silver nitrate solution into a uniform coating of silver nanoparticles. Thin layers of conducting gold and poly(3,4-ethylenedioxythiophene) were then applied. And the resulting supercapacitor demonstrated power and energy densities of 2,715 watts per kilogram and 22 watt-hours per kilogram -- enough to operate a heart rate monitor, LEDs or a Bluetooth module. The researchers tested the device's durability and found that it performed well even after being compressed more than 100 times. The authors acknowledge funding from the University Grants Commission of India, the Council of Scientific and Industrial Research (India) and the Board of Research in Nuclear Sciences (India). The abstract that accompanies this study is available here. The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With nearly 157,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies. Its main offices are in Washington, D.C., and Columbus, Ohio. To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.


News Article | February 16, 2017
Site: www.sciencedaily.com

Wearable electronics are here -- the most prominent versions are sold in the form of watches or sports bands. But soon, more comfortable products could become available in softer materials made in part with an unexpected ingredient: green tea. Researchers report in ACS' The Journal of Physical Chemistry C a new flexible and compact rechargeable energy storage device for wearable electronics that is infused with green tea polyphenols. Powering soft wearable electronics with a long-lasting source of energy remains a big challenge. Supercapacitors could potentially fill this role -- they meet the power requirements, and can rapidly charge and discharge many times. But most supercapacitors are rigid, and the compressible supercapacitors developed so far have run into roadblocks. They have been made with carbon-coated polymer sponges, but the coating material tends to bunch up and compromise performance. Guruswamy Kumaraswamy, Kothandam Krishnamoorthy and colleagues wanted to take a different approach. The researchers prepared polymer gels in green tea extract, which infuses the gel with polyphenols. The polyphenols converted a silver nitrate solution into a uniform coating of silver nanoparticles. Thin layers of conducting gold and poly(3,4-ethylenedioxythiophene) were then applied. And the resulting supercapacitor demonstrated power and energy densities of 2,715 watts per kilogram and 22 watt-hours per kilogram -- enough to operate a heart rate monitor, LEDs or a Bluetooth module. The researchers tested the device's durability and found that it performed well even after being compressed more than 100 times.

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