'Helix-to-tube' a simple strategy to synthesize covalent organic nanotubes

'Helix-to-tube' a simple strategy to synthesize covalent organic nanotubes

 

 

Synthesis of organic nanotubes by the "helix-to-tube" method.

 

Credit: Image courtesy of Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University

 

Organic nanotubes (ONTs) are tubular nanostructures composed of organic molecules that have unique properties and have found various applications, such as electro-conductive materials and organic photovoltaics.

 A group of scientists at Nagoya University have developed a simple and effective method for the formation of robust covalent ONTs from simple molecules. This method is expected to be useful in generating a range of nanotube-based materials with desirable properties.

Kaho Maeda, Dr. Hideto Ito, Professor Kenichiro Itami of the JST-ERATO Itami Molecular Nanocarbon Project and the Institute of Transformative Bio-Molecules (ITbM) of Nagoya University, and their colleagues have reported in the Journal of the American Chemical Society, on the development of a new and simple strategy, "helix-to-tube" to synthesize covalent organic nanotubes.

Organic nanotubes (ONTs) are organic molecules with tubular nanostructures. Nanostructures are structures that range between 1 nm and 100 nm, and ONTs have a nanometer-sized cavity. Various applications of ONTs have been reported, including molecular recognition materials, transmembrane ion channel/sensors, electro-conductive materials, and organic photovoltaics. Most ONTs are constructed by a self-assembly process based on weak non-covalent interactions such as hydrogen bonding, hydrophobic interactions and π-π interactions between aromatic rings. Due to these relatively weak interactions, most non-covalent ONTs possess a relatively fragile structure.

Covalent ONTs, whose tubular skeletons are cross-linked by covalent bonding (a bond made by sharing of electrons between atoms) could be synthesized from non-covalent ONTs. While covalent ONTs show higher stability and mechanical strength than non-covalent ONTs, the general synthetic strategy for covalent ONTs was yet to be established.

A team led by Hideto Ito and Kenichiro Itami has succeeded in developing a simple and effective method for the synthesis of robust covalent ONTs (tube) by an operationally simple light irradiation of a readily accessible helical polymer (helix). This so-called "helix-to-tube" strategy is based on the following steps: 1) polymerization of a small molecule (monomer) to make a helical polymer followed by, 2) light-induced cross-linking at longitudinally repeating pitches across the whole helix to form covalent nanotubes.

With their strategy, the team designed and synthesized diacetylene-based helical polymers (acetylenes are molecules that contain carbon-carbon triple bonds), poly(m-phenylene diethynylene)s (poly-PDEs), which has chiral amide side chains that are able to induce a helical folding through hydrogen-bonding interactions.

The researchers revealed that light-induced cross-linking at longitudinally aligned 1,3-butadiyne moieties (a group of molecules that contain four carbons with triple bonds at the first and third carbons) could generate the desired covalent ONT. "This is the first time in the world to show that the photochemical polymerization reaction of diynes is applicable to the cross-linking reaction of a helical polymer," says Maeda, a graduate student who mainly conducted the experiments.

The "helix-to-tube" method is expected to be able to generate a range of ONT-based materials by simply changing the arene (aromatic ring) unit in the monomer.

"One of the most difficult parts of this research was how to obtain scientific evidence on the structures of poly-PDEs and covalent ONTs," says Ito, one of the leaders of this study. "We had little experience with the analysis of polymers and macromolecules such as ONTs. Fortunately, thanks to the support of our collaborators in Nagoya University, who are specialists in these particular research fields, we finally succeeded in characterizing these macromolecules by various techniques including spectroscopy, X-ray diffraction, and microscopy."

"Although it took us about a year to synthesize the covalent ONT, it took another one and a half year to determine the structure of the nanotube," says Maeda. "I was extremely excited when I first saw the transmission electron microscopy (TEM) images, which indicated that we had actually made the covalent ONT that we were expecting," she continues.

"The best part of the research for me was finding that the photochemical cross-linking had taken place on the helix for the first time," says Maeda. "In addition, photochemical cross-linking is known to usually occur in the solid phase, but we were able to show that the reaction takes place in the solution phase as well. As the reactions have never been carried out before, I was dubious at first, but it was a wonderful feeling to succeed in making the reaction work for the first time in the world. I can say for sure that this was a moment where I really found research interesting."

"We were really excited to develop this simple yet powerful method to achieve the synthesis of covalent ONTs," says Itami, the director of the JST-ERATO project and the center director of ITbM. "The "helix-to-tube" method enables molecular level design and will lead to the synthesis of various covalent ONTs with fixed diameters and tube lengths with desirable functionalities."

"We envisage that ongoing advances in the "helix-to-tube" method may lead to the development of various ONT-based materials including electro-conductive materials and luminescent materials," says Ito. "We are currently carrying out work on the "helix-to-tube" methodology and we hope to synthesize covalent ONTs with interesting properties for various applications."

Story Source:

The above post is reprinted from materials provided by Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University. Note: Content may be edited for style and length.

Journal Reference:

1. Kaho Maeda, Liu Hong, Taishi Nishihara, Yusuke Nakanishi, Yuhei Miyauchi, Ryo Kitaura, Naoki Ousaka, Eiji Yashima, Hideto Ito, Kenichiro Itami. Construction of Covalent Organic Nanotubes by Light-Induced Cross-Linking of Diacetylene-Based Helical Polymers. Journal of the American Chemical Society, 2016; DOI: 10.1021/jacs.6b05582

Cite This Page:

Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University. "'Helix-to-tube' a simple strategy to synthesize covalent organic nanotubes." ScienceDaily. ScienceDaily, 30 August 2016. <www.sciencedaily.com/releases/2016/08/160830084008.htm>.

 

Better batteries: Next-generation smart separator membranes

Better batteries: Next-generation smart separator membranes

ULL STORY

From left are Sa Hoon Min, Jung-Hwan Kim, Prof. Sang-Young Lee (School of Energy and Chemical Engineering), Prof. Byeong-Su Kim (School of Natural Science), and Minsu-Gu.

 

Credit: UNIST

 

A team of Korean researchers, affiliated with UNIST is receiving the media spotlight as they have proposed a green material strategy for the development of smart battery separators beyond the current state-of-the-art counterparts.

The findings appear in the July 6th issue of Nano Letters, co-authored by Prof. Sang-Young Lee (School of Energy and Chemical Engineering), Prof. Byeong-Su Kim (School of Natural Science), the lead authors of the study Jung-Hwan Kim (School of Energy and Chemical Engineering) and Minsu Gu (School of Energy and Chemical Engineering), and four others.

In the study, the research team presented a new class of battery seperator based on the hierarchical/asymmetric porous structure of the heterolayered nanomat ("c-mat separator"), as an unprecedented membrane opportunity to enable remarkable advances in cell performance far beyond those accessible with conventional battery separators.

Among major battery components, separator membranes have not been the center of attention compared to other electrochemically active materials, despite their important roles in allowing ionic flow and preventing electrical contact between electrodes. This study introduces novel chemical functionalities to seperator membranes, thereby bringing unprecedented benefits to battery performance.

The c-mat separator consisted of a thin nanoporous TPY-CNF mat as the top layer and a thick macroporous electrospun PVP/PAN mat as the support layer. According to the research team, in addition to the aforementioned structural uniqueness, another salient feature of the c-mat separator is the higher ion conductivity compared with the existing PP/PE/PP separators.

"This ground-breaking discovery will pave the way towards next generation lithium-ion batteries, exhibiting significantly enhanced performance and increased energy efficiency," says JungHwan Kim, the lead author on the study.

The research team noted, "We envision that the c-mat separator, benefiting from its structural uniqueness and chemical functionalities, will open a new path for the development of high-performance smart separator membranes for potential use in next-generation power sources and in permselective membrane filtration systems for high mass flux/removal of heavy-metal ions."

Story Source:

The above post is reprinted from materials provided by Ulsan National Institute of Science and Technology(UNIST). Note: Content may be edited for style and length.

Journal Reference:

1. Jung-Hwan Kim, Minsu Gu, Do Hyun Lee, Jeong-Hoon Kim, Yeon-Su Oh, Sa Hoon Min, Byeong-Su Kim, Sang-Young Lee. Functionalized Nanocellulose-Integrated Heterolayered Nanomats toward Smart Battery Separators. Nano Letters, 2016; DOI: 10.1021/acs.nanolett.6b02069

Cite This Page:

Ulsan National Institute of Science and Technology(UNIST). "Better batteries: Next-generation smart separator membranes." ScienceDaily. ScienceDaily, 26 August 2016. <www.sciencedaily.com/releases/2016/08/160826092708.htm>.

 

The first autonomous, entirely soft robot

The first autonomous, entirely soft robot

Powered by a chemical reaction controlled by microfluidics, 3-D-printed 'octobot' has no electronics

 

The octobot is powered by a chemical reaction and controlled with a soft logic board. A reaction inside the bot transforms a small amount of liquid fuel (hydrogen peroxide) into a large amount of gas, which flows into the octobot's arms and inflates them like a balloon. The team used a microfluidic logic circuit, a soft analog of a simple electronic oscillator, to control when hydrogen peroxide decomposes to gas in the octobot.

 

Credit: Lori Sanders

 

A team of Harvard University researchers with expertise in 3D printing, mechanical engineering, and microfluidics has demonstrated the first autonomous, untethered, entirely soft robot. This small, 3D-printed robot -- nicknamed the octobot -- could pave the way for a new generation of completely soft, autonomous machines.

Soft robotics could revolutionize how humans interact with machines. But researchers have struggled to build entirely compliant robots. Electric power and control systems -- such as batteries and circuit boards -- are rigid and until now soft-bodied robots have been either tethered to an off-board system or rigged with hard components.

Robert Wood, the Charles River Professor of Engineering and Applied Sciences and Jennifer A. Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) led the research. Lewis and Wood are also core faculty members of the Wyss Institute for Biologically Inspired Engineering at Harvard University.

"One long-standing vision for the field of soft robotics has been to create robots that are entirely soft, but the struggle has always been in replacing rigid components like batteries and electronic controls with analogous soft systems and then putting it all together," said Wood. "This research demonstrates that we can easily manufacture the key components of a simple, entirely soft robot, which lays the foundation for more complex designs."

The research is described in the journal Nature.

"Through our hybrid assembly approach, we were able to 3D print each of the functional components required within the soft robot body, including the fuel storage, power and actuation, in a rapid manner," said Lewis. "The octobot is a simple embodiment designed to demonstrate our integrated design and additive fabrication strategy for embedding autonomous functionality."

Octopuses have long been a source of inspiration in soft robotics. These curious creatures can perform incredible feats of strength and dexterity with no internal skeleton.

Harvard's octobot is pneumatic-based, i.e., it is powered by gas under pressure. A reaction inside the bot transforms a small amount of liquid fuel (hydrogen peroxide) into a large amount of gas, which flows into the octobot's arms and inflates them like a balloon.

"Fuel sources for soft robots have always relied on some type of rigid components," said Michael Wehner, a postdoctoral fellow in the Wood lab and co-first author of the paper. "The wonderful thing about hydrogen peroxide is that a simple reaction between the chemical and a catalyst -- in this case platinum -- allows us to replace rigid power sources."

To control the reaction, the team used a microfluidic logic circuit based on pioneering work by co-author and chemist George Whitesides, the Woodford L. and Ann A. Flowers University Professor and core faculty member of the Wyss. The circuit, a soft analog of a simple electronic oscillator, controls when hydrogen peroxide decomposes to gas in the octobot.

"The entire system is simple to fabricate, by combining three fabrication methods -- soft lithography, molding and 3D printing -- we can quickly manufacture these devices," said Ryan Truby, a graduate student in the Lewis lab and co-first author of the paper.

The simplicity of the assembly process paves the way for more complex designs. Next, the Harvard team hopes to design an octobot that can crawl, swim and interact with its environment.

"This research is a proof of concept," Truby said. "We hope that our approach for creating autonomous soft robots inspires roboticists, material scientists and researchers focused on advanced manufacturing,"
The paper was co-authored by Daniel Fitzgerald of the Wyss Institute and Bobak Mosadegh, of Cornell University. The research was supported by the National Science Foundation through the Materials Research Science and Engineering Center at Harvard and by the Wyss Institute.

Story Source:

The above post is reprinted from materials provided by Harvard John A. Paulson School of Engineering and Applied Sciences. The original item was written by Leah Burrows. Note: Content may be edited for style and length.

Journal Reference:

1. Michael Wehner, Ryan L. Truby, Daniel J. Fitzgerald, Bobak Mosadegh, George M. Whitesides, Jennifer A. Lewis, Robert J. Wood. An integrated design and fabrication strategy for entirely soft, autonomous robots. Nature, 2016; 536 (7617): 451 DOI: 10.1038/nature19100

Cite This Page:

Harvard John A. Paulson School of Engineering and Applied Sciences. "The first autonomous, entirely soft robot: Powered by a chemical reaction controlled by microfluidics, 3-D-printed 'octobot' has no electronics." ScienceDaily. ScienceDaily, 24 August 2016. <www.sciencedaily.com/releases/2016/08/160824135032.htm>.

 

 

Bubble-wrapped sponge creates steam using sunlight

Bubble-wrapped sponge creates steam using sunlight

Bubble-wrapped structure requires no mirrors or lenses to focus the sun's heat

 

MIT graduate student George Ni holds a bubble-wrapped, sponge-like device that soaks up natural sunlight and heats water to boiling temperatures, generating steam through its pores.

 

How do you boil water? Eschewing the traditional kettle and flame, MIT engineers have invented a bubble-wrapped, sponge-like device that soaks up natural sunlight and heats water to boiling temperatures, generating steam through its pores.

The design, which the researchers call a "solar vapor generator," requires no expensive mirrors or lenses to concentrate the sunlight, but instead relies on a combination of relatively low-tech materials to capture ambient sunlight and concentrate it as heat. The heat is then directed toward the pores of the sponge, which draw water up and release it as steam.

From their experiments -- including one in which they simply placed the solar sponge on the roof of MIT's Building 3 -- the researchers found the structure heated water to its boiling temperature of 100 degrees Celsius, even on relatively cool, overcast days. The sponge also converted 20 percent of the incoming sunlight to steam.

The low-tech design may provide inexpensive alternatives for applications ranging from desalination and residential water heating, to wastewater treatment and medical tool sterilization.

The team has published its results today in the journal Nature Energy. The research was led by George Ni, an MIT graduate student; and Gang Chen, the Carl Richard Soderberg Professor in Power Engineering and the head of the Department of Mechanical Engineering; in collaboration with TieJun Zhang and his group members Hongxia Li and Weilin Yang from the Department of Mechanical and Materials Engineering at the Masdar Institute of Science and Technology, in the United Arab Emirates.

Building up the sun

The researchers' current design builds on a solar-absorbing structure they developed in 2014 -- a similar floating, sponge-like material made of graphite and carbon foam, that was able to boil water to 100 C and convert 85 percent of the incoming sunlight to steam.

To generate steam at such efficient levels, the researchers had to expose the structure to simulated sunlight that was 10 times the intensity of sunlight in normal, ambient conditions.

"It was relatively low optical concentration," Chen says. "But I kept asking myself, 'Can we basically boil water on a rooftop, in normal conditions, without optically concentrating the sunlight? That was the basic premise."

In ambient sunlight, the researchers found that, while the black graphite structure absorbed sunlight well, it also tended to radiate heat back out into the environment. To minimize the amount of heat lost, the team looked for materials that would better trap solar energy.

A bubbly solution

In their new design, the researchers settled on a spectrally-selective absorber -- a thin, blue, metallic-like film that is commonly used in solar water heaters and possesses unique absorptive properties. The material absorbs radiation in the visible range of the electromagnetic spectrum, but it does not radiate in the infrared range, meaning that it both absorbs sunlight and traps heat, minimizing heat loss.

The researchers obtained a thin sheet of copper, chosen for its heat-conducting abilities and coated with the spectrally-selective absorber. They then mounted the structure on a thermally-insulating piece of floating foam. However, they found that even though the structure did not radiate much heat back out to the environment, heat was still escaping through convection, in which moving air molecules such as wind would naturally cool the surface.

A solution to this problem came from an unlikely source: Chen's 16-year-old daughter, who at the time was working on a science fair project in which she constructed a makeshift greenhouse from simple materials, including bubble wrap.

"She was able to heat it to 160 degrees Fahrenheit, in winter!" Chen says. "It was very effective."
Chen proposed the packing material to Ni, as a cost-effective way to prevent heat loss by convection. This approach would let sunlight in through the material's transparent wrapping, while trapping air in its insulating bubbles.

"I was very skeptical of the idea at first," Ni recalls. "I thought it was not a high-performance material. But we tried the clearer bubble wrap with bigger bubbles for more air trapping effect, and it turns out, it works. Now because of this bubble wrap, we don't need mirrors to concentrate the sun."

The bubble wrap, combined with the selective absorber, kept heat from escaping the surface of the sponge. Once the heat was trapped, the copper layer conducted the heat toward a single hole, or channel, that the researchers had drilled through the structure. When they placed the sponge in water, they found that water crept up the channel, where it was heated to 100 C, then turned to steam.

Chen and Ni say that solar absorbers based on this general design could be used as large sheets to desalinate small bodies of water, or to treat wastewater. Ni says other solar-based technologies that rely on optical-concentrating technologies typically are designed to last 10 to 20 years, though they require expensive parts and maintenance. This new, low-tech design, he says, could operate for one to two years before needing to be replaced.

"Even so, the cost is pretty competitive," Ni says. "It's kind of a different approach, where before, people were doing high-tech and long-term [solar absorbers]. We're doing low-tech and short-term."
"What fascinates us is the innovative idea behind this inexpensive device, where we have creatively designed this device based on basic understanding of capillarity and solar thermal radiation. Meanwhile, we are excited to continue probing the complicated physics of solar vapor generation and to discover new knowledge for the scientific community," Zhang says.

This research was funded, in part, by a cooperative agreement between the Masdar Institute of Science and Technology; and by the Solid-State Solar Thermal Energy Conversion Center, an Energy Frontier Research Center funded by U.S. Department of Energy.

Story Source:

The above post is reprinted from materials provided by Massachusetts Institute of Technology. The original item was written by Jennifer Chu. Note: Content may be edited for style and length.

Journal Reference:

1. George Ni, Gabriel Li, Svetlana V. Boriskina, Hongxia Li, Weilin Yang, TieJun Zhang, Gang Chen. Steam generation under one sun enabled by a floating structure with thermal concentration. Nature Energy, 2016; 1: 16126 DOI: 10.1038/nenergy.2016.126

Cite This Page:

Massachusetts Institute of Technology. "Bubble-wrapped sponge creates steam using sunlight: Bubble-wrapped structure requires no mirrors or lenses to focus the sun's heat." ScienceDaily. ScienceDaily, 22 August 2016. <www.sciencedaily.com/releases/2016/08/160822124924.htm>.

 

 

Natural scale caterpillar soft robot is powered and controlled with light

Caterpillar micro-robot sitting on a finger tip.

Researchers at the Faculty of Physics at the University of Warsaw, using the liquid crystal elastomer technology, originally developed in the LENS Institute in Florence, demonstrated a bioinspired micro-robot capable of mimicking caterpillar gaits in natural scale. The 15-millimeter long soft robot harvests energy from green light and is controlled by spatially modulated laser beam. Apart from travelling on flat surfaces, it can also climb slopes, squeeze through narrow slits and transport loads.

For decades scientists and engineers have been trying to build robots mimicking different modes of locomotion found in nature. Most of these designs have rigid skeletons and joints driven by electric or pneumatic actuators. In nature, however, a vast number of creatures navigate their habitats using soft bodies -- earthworms, snails and larval insects can effectively move in complex environments using different strategies. Up to date, attempts to create soft robots were limited to larger scale (typically tens of centimeters), mainly due to difficulties in power management and remote control.

Liquid Crystalline Elastomers (LCEs) are smart materials that can exhibit large shape change under illumination with visible light. With the recently developed techniques, it is possible to pattern these soft materials into arbitrary three dimensional forms with a pre-defined actuation performance. The light-induced deformation allows a monolithic LCE structure to perform complex actions without numerous discrete actuators.

Researchers from the University of Warsaw with colleagues from LESN (Italy) and Cambridge (UK) have now developed a natural-scale soft caterpillar robot with an opto-mechanical liquid crystalline elastomer monolithic design. The robot body is made of a light sensitive elastomer stripe with patterned molecular alignment. By controlling the travelling deformation pattern the robot mimics different gaits of its natural relatives. It can also walk up a slope, squeeze through a slit and push objects as heavy as ten times its own mass, demonstrating its ability to perform in challenging environments and pointing at potential future applications.

- Designing soft robots calls for a completely new paradigm in their mechanics, power supply and control. We are only beginning to learn from nature and shift our design approaches towards these that emerged in natural evolution -- says Piotr Wasylczyk, head of the Photonic Nanostructure Facility at the Faculty of Physics of the University of Warsaw, Poland, who led the project.

Researchers hope that rethinking materials, fabrication techniques and design strategies should open up new areas of soft robotics in micro- and millimeter length scales, including swimmers (both on-surface and underwater) and even fliers.

Story Source:
The above post is reprinted from materials provided by Faculty of Physics University of Warsaw. Note: Content may be edited for style and length.

Journal Reference:

1. Mikołaj Rogóż, Hao Zeng, Chen Xuan, Diederik Sybolt Wiersma, Piotr Wasylczyk. Light-Driven Soft Robot Mimics Caterpillar Locomotion in Natural Scale. Advanced Optical Materials, 2016; DOI: 10.1002/adom.201600503

Cite This Page:

Faculty of Physics University of Warsaw. "Natural scale caterpillar soft robot is powered and controlled with light." ScienceDaily. ScienceDaily, 18 August 2016. <www.sciencedaily.com/releases/2016/08/160818102611.htm>.

 

Recording analog memories in human cells

Engineers program human cells to store complex histories in their DNA

MIT biological engineers have devised a memory storage system illustrated here as a DNA-embedded meter that is recording the activity of a signaling pathway in a human cell.

MIT biological engineers have devised a way to record complex histories in the DNA of human cells, allowing them to retrieve "memories" of past events, such as inflammation, by sequencing the DNA.

This analog memory storage system -- the first that can record the duration and/or intensity of events in human cells -- could also help scientists study how cells differentiate into various tissues during embryonic development, how cells experience environmental conditions, and how they undergo genetic changes that lead to disease.

"To enable a deeper understanding of biology, we engineered human cells that are able to report on their own history based on genetically encoded recorders," says Timothy Lu, an associate professor of electrical engineering and computer science, and of biological engineering. This technology should offer insights into how gene regulation and other events within cells contribute to disease and development, he adds.

Lu, who is head of the Synthetic Biology Group at MIT's Research Laboratory of Electronics, is the senior author of the new study, which appears in the Aug. 18 online edition of Science. The paper's lead authors are Samuel Perli SM '10, PhD '15 and graduate student Cheryl Cui.

Analog memory

Many scientists, including Lu, have devised ways to record digital information in living cells. Using enzymes called recombinases, they program cells to flip sections of their DNA when a particular event occurs, such as exposure to a particular chemical. However, that method reveals only whether the event occurred, not how much exposure there was or how long it lasted.

Lu and other researchers have previously devised ways to record that kind of analog information in bacteria, but until now, no one has achieved it in human cells.

The new MIT approach is based on the genome-editing system known as CRISPR, which consists of a DNA-cutting enzyme called Cas9 and a short RNA strand that guides the enzyme to a specific area of the genome, directing Cas9 where to make its cut.

CRISPR is widely used for gene editing, but the MIT team decided to adapt it for memory storage. In bacteria, where CRISPR originally evolved, the system records past viral infections so that cells can recognize and fight off invading viruses.

"We wanted to adapt the CRISPR system to store information in the human genome," Perli says.

When using CRISPR to edit genes, researchers create RNA guide strands that match a target sequence in the host organism's genome. To encode memories, the MIT team took a different approach: They designed guide strands that recognize the DNA that encodes the very same guide strand, creating what they call "self-targeting guide RNA."

Led by this self-targeting guide RNA strand, Cas9 cuts the DNA encoding the guide strand, generating a mutation that becomes a permanent record of the event. That DNA sequence, once mutated, generates a new guide RNA strand that directs Cas9 to the newly mutated DNA, allowing further mutations to accumulate as long as Cas9 is active or the self-targeting guide RNA is expressed.

By using sensors for specific biological events to regulate Cas9 or self-targeting guide RNA activity, this system enables progressive mutations that accumulate as a function of those biological inputs, thus providing genomically encoded memory.

For example, the researchers engineered a gene circuit that only expresses Cas9 in the presence of a target molecule, such as TNF-alpha, which is produced by immune cells during inflammation. Whenever TNF- alpha is present, Cas9 cuts the DNA encoding the guide sequence, generating mutations. The longer the exposure to TNF-alpha or the greater the TNF-alpha concentration, the more mutations accumulate in the DNA sequence.

By sequencing the DNA later on, researchers can determine how much exposure there was.

"This is the rich analog behavior that we are looking for, where, as you increase the amount or duration of TNF-alpha, you get increases in the amount of mutations," Perli says.

"Moreover, we wanted to test our system in living animals. Being able to record and extract information from live cells in mice can help answer meaningful biological questions," Cui says. The researchers showed that the system is capable of recording inflammation in mice.

Most of the mutations result in deletion of part of the DNA sequence, so the researchers designed their RNA guide strands to be longer than the usual 20 nucleotides, so they won't become too short to function. Sequences of 40 nucleotides are more than long enough to record for a month, and the researchers have also designed 70-nucleotide sequences that could be used to record biological signals for even longer.

Tracking development and disease

The researchers also showed that they could engineer cells to detect and record more than one input, by producing multiple self-targeting RNA guide strands in the same cell. Each RNA guide is linked to a specific input and is only produced when that input is present. In this study, the researchers showed that they could record the presence of both the antibiotic doxycycline and a molecule known as IPTG.

Currently this method is most likely to be used for studies of human cells, tissues, or engineered organs, the researchers say. By programming cells to record multiple events, scientists could use this system to monitor inflammation or infection, or to monitor cancer progression. It could also be useful for tracing how cells specialize into different tissues during development of animals from embryos to adults.

"With this technology you could have different memory registers that are recording exposures to different signals, and you could see that each of those signals was received by the cell for this duration of time or at that intensity," Perli says. "That way you could get closer to understanding what's happening in development."

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Story Source:

The above post is reprinted from materials provided by Massachusetts Institute of Technology. The original item was written by Anne Trafton.Note: Content may be edited for style and length.

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Journal Reference:

1. Samuel D. Perli, Cheryl H. Cui, Timothy K. Lu. Continuous genetic recording with self-targeting CRISPR-Cas in human cells. Science, August 2016 DOI: 10.1126/science.aag0511

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Cite This Page:

Massachusetts Institute of Technology. "Recording analog memories in human cells: Engineers program human cells to store complex histories in their DNA." ScienceDaily. ScienceDaily, 18 August 2016. <www.sciencedaily.com/releases/2016/08/160818150004.htm>

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Wearable cloud could be less expensive, more powerful form of mobile computing

Wearable cloud could be less expensive, more powerful form of mobile computing

Wearable personal cloud graphic.

 

 

Researchers at the University of Alabama at Birmingham are exploring the concept of a wearable personal cloud -- a fully functioning, yet compact and lightweight cloud computing system embedded into clothing.

Ragib Hasan, Ph.D., assistant professor of computer and information sciences in the UAB College of Arts and Sciences, and Rasib Khan, Ph.D., a recent postdoctoral graduate student, presented the concept and prototype of a wearable cloud jacket at the 40th Institute of Electrical and Electronics Engineers Computer Society International Conference on Computers, Software & Applications (IEEE COMPSAC) in June.
Using 10 low-cost, credit-card-sized computers called Raspberry Pi's, an old winter jacket, three power banks and a small remote touch screen display, Hasan and Khan developed a wearable system that brings all mobile computing solutions together, creating the ultimate smart device. The cloud jacket could make the design of mobile and wearable devices simple, inexpensive and lightweight by allowing users to tap into the resources of the wearable cloud, instead of relying solely on the capabilities of their mobile hardware.
"Currently if you want to have a smart watch, smartphone, an exercise tracker and smart glasses, you have to buy individual expensive devices that aren't working together," Hasan said. "Why not have a computational platform with you that can support many forms of mobile and wearable devices? Then all of these capabilities can become really inexpensive."

The need for more powerful processors and consumer expectations for high-performance applications have caused the design of wearable and mobile devices to be complex and expensive. Someone who wishes to own a smart watch, smart glasses, a smartphone and a wearable health device would have to spend between $2,000 and $3,000 to purchase such devices. The cloud jacket prototype has roughly 10 gigabytes of RAM, while the average smartphone has only one to three gigabytes. In regard to storage, each Raspberry Pi within the jacket has 32 gigabytes of memory available.

Most wearable and mobile devices are made with processors that are nearly 10 times slower than desktop or laptop processors, limiting the types of applications that can be run on them. With mobile apps' becoming more complex, newer, more powerful versions of mobile and wearable devices are continuously released in order to keep up with changes in technology, resulting in increased prices.

To make up for resource limitations, many mobile applications are also powered by cloud servers, which require constant communication over the internet. Mobile and wearable device users are required to upload all personal data to remote public clouds or local cloud data centers, without the knowledge of where their personal data is actually being stored.

"Our overall approach is to create a generic atmosphere or platform that users can customize to fit their needs," Khan said. "The wearable cloud can act as an application platform, so instead of modifying or having to upgrade hardware, this wearable model provides a platform, and developers can build anything on top of it."

With a wearable cloud, mobile and wearable devices would no longer need complex, powerful processors. By turning them into "dumb terminal devices" or controllers, the wearable cloud would provide the experience of a smart device. By connecting the terminal devices via Bluetooth or Wi-Fi, a user utilizes the devices to request services via a user intuitive display and interactions. The computational task is sent to the wearable private cloud.

Nodes inside the jacket are engaged and compute the task collectively. Upon completion, the displayable result is sent back to the terminal device. The tasks are performed from the privately owned wearable cloud jacket, which also retains most, if not all, personal data.

"Once you have turned everything else into a 'dumb device,' the wearable cloud becomes the smart one," Hasan said. "The application paradigm becomes much more simple and brings everything together. Instead of individual solutions, now you have everything as a composite solution."

Hasan and Khan's wearable cloud concept differs from existing "smart clothing" solutions in that they only act as input devices. Current products such as the Levi's "Smart Jacket" allow a user to make hand gestures on the jacket to answer a phone call or shuffle through a playlist.

The wearable personal cloud concept is not limited to clothing. The system model allows the personal cloud to extend to any item carried on a daily basis, from a jacket to a briefcase, purse or backpack. Hasan and Khan believe this type of technology solution could aid in a variety of ways, from the way first responders communicate and share information during disasters to the way soldiers communicate on the battlefield.

"With seven to 10 people wearing such a cloud together, they create what we call a hyper-cloud, a much more powerful engine," Hasan said. "The jacket can also act as a micro or picocell tower. All of its capabilities can be shared on a private network with other devices via Wi-Fi or Bluetooth. If a first responder is out in the field and doesn't have complete information to act on a mission, but someone else does, it can be shared and updated through the cloud in real time."

Suppose a disaster occurs and first responders are entering a damaged building. They may have blueprints of what the building looked like prior to the incident, but only those inside know what areas are now damaged or where an injured person is located. By pairing the wearable cloud with a device like Google Glass or night vision goggles, anyone with access to the cloud can see whatever the person wearing the cloud is seeing in real time, without the need for platform- or device-specific hardware and software.
Hasan and Khan call this a delegated experience.

"Another potential application area that we are looking into is hospital gowns," Hasan said. "When a patient comes in, they are connected to monitors to obtain heart rate, blood pressure and other vitals. Whenever a patient has to go to the restroom or needs to be moved around, they have to take everything off or maneuver around with a large pole carrying all of the connected devices. Instead, we are putting sensors inside a vest that can be placed over the hospital gown itself. There will be a small version of the wearable cloud within the vest so that the vest itself can collect information, like a patient's temperature."

Story Source:

The above post is reprinted from materials provided by University of Alabama at Birmingham. The original item was written by Tiffany Westry. Note: Content may be edited for style and length.

Cite This Page:

 

University of Alabama at Birmingham. "Wearable cloud could be less expensive, more powerful form of mobile computing." ScienceDaily. ScienceDaily, 10 August 2016. <www.sciencedaily.com/releases/2016/08/160810114119.htm>.

 

 

Prototype chip could help make quantum computing practical

Prototype chip could help make quantum computing practical

Built-in optics could enable chips that use trapped ions as quantum bits

 

Researchers from MIT and MIT Lincoln Laboratory report an important step toward practical quantum computers, with a paper describing a prototype chip that can trap ions in an electric field and, with built-in optics, direct laser light toward each of them. (Stock image)

 

 

Quantum computers are largely hypothetical devices that could perform some calculations much more rapidly than conventional computers can. Instead of the bits of classical computation, which can represent 0 or 1, quantum computers consist of quantum bits, or qubits, which can, in some sense, represent 0 and 1 simultaneously.

Although quantum systems with as many as 12 qubits have been demonstrated in the lab, building quantum computers complex enough to perform useful computations will require miniaturizing qubit technology, much the way the miniaturization of transistors enabled modern computers.

Trapped ions are probably the most widely studied qubit technology, but they've historically required a large and complex hardware apparatus. In today's Nature Nanotechnology, researchers from MIT and MIT Lincoln Laboratory report an important step toward practical quantum computers, with a paper describing a prototype chip that can trap ions in an electric field and, with built-in optics, direct laser light toward each of them.

"If you look at the traditional assembly, it's a barrel that has a vacuum inside it, and inside that is this cage that's trapping the ions. Then there's basically an entire laboratory of external optics that are guiding the laser beams to the assembly of ions," says Rajeev Ram, an MIT professor of electrical engineering and one of the senior authors on the paper. "Our vision is to take that external laboratory and miniaturize much of it onto a chip."

Caged in

The Quantum Information and Integrated Nanosystems group at Lincoln Laboratory was one of several research groups already working to develop simpler, smaller ion traps known as surface traps. A standard ion trap looks like a tiny cage, whose bars are electrodes that produce an electric field. Ions line up in the center of the cage, parallel to the bars. A surface trap, by contrast, is a chip with electrodes embedded in its surface. The ions hover 50 micrometers above the electrodes.

Cage traps are intrinsically limited in size, but surface traps could, in principle, be extended indefinitely. With current technology, they would still have to be held in a vacuum chamber, but they would allow many more qubits to be crammed inside.

"We believe that surface traps are a key technology to enable these systems to scale to the very large number of ions that will be required for large-scale quantum computing," says Jeremy Sage, who together with John Chiaverini leads Lincoln Laboratory's trapped-ion quantum-information-processing project. "These cage traps work very well, but they really only work for maybe 10 to 20 ions, and they basically max out around there."

Performing a quantum computation, however, requires precisely controlling the energy state of every qubit independently, and trapped-ion qubits are controlled with laser beams. In a surface trap, the ions are only about 5 micrometers apart. Hitting a single ion with an external laser, without affecting its neighbors, is incredibly difficult; only a few groups had previously attempted it, and their techniques weren't practical for large-scale systems.

Getting onboard

That's where Ram's group comes in. Ram and Karan Mehta, an MIT graduate student in electrical engineering and first author on the new paper, designed and built a suite of on-chip optical components that can channel laser light toward individual ions. Sage, Chiaverini, and their Lincoln Lab colleagues Colin Bruzewicz and Robert McConnell retooled their surface trap to accommodate the integrated optics without compromising its performance. Together, both groups designed and executed the experiments to test the new system.

"Typically, for surface electrode traps, the laser beam is coming from an optical table and entering this system, so there's always this concern about the beam vibrating or moving," Ram says. "With photonic integration, you're not concerned about beam-pointing stability, because it's all on the same chip that the electrodes are on. So now everything is registered against each other, and it's stable."
The researchers' new chip is built on a quartz substrate. On top of the quartz is a network of silicon nitride "waveguides," which route laser light across the chip. Above the waveguides is a layer of glass, and on top of that are the niobium electrodes. Beneath the holes in the electrodes, the waveguides break into a series of sequential ridges, a "diffraction grating" precisely engineered to direct light up through the holes and concentrate it into a beam narrow enough that it will target a single ion, 50 micrometers above the surface of the chip.

Prospects

With the prototype chip, the researchers were evaluating the performance of the diffraction gratings and the ion traps, but there was no mechanism for varying the amount of light delivered to each ion. In ongoing work, the researchers are investigating the addition of light modulators to the diffraction gratings, so that different qubits can simultaneously receive light of different, time-varying intensities. That would make programming the qubits more efficient, which is vital in a practical quantum information system, since the number of quantum operations the system can perform is limited by the "coherence time" of the qubits.

Story Source:

The above post is reprinted from materials provided by Massachusetts Institute of Technology. The original item was written by Larry Hardesty. Note: Content may be edited for style and length.

Journal Reference:

1. Karan K. Mehta, Colin D. Bruzewicz, Robert McConnell, Rajeev J. Ram, Jeremy M. Sage, John Chiaverini. Integrated optical addressing of an ion qubit. Nature Nanotechnology, 2016; DOI: 10.1038/nnano.2016.139

Cite This Page:

Massachusetts Institute of Technology. "Prototype chip could help make quantum computing practical: Built-in optics could enable chips that use trapped ions as quantum bits." ScienceDaily. ScienceDaily, 8 August 2016. <www.sciencedaily.com/releases/2016/08/160808120715.htm>.

 

 

 

Atomic blimp stretches a crystal

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Scientists inserted helium ions into a thin crystalline film (gold) to controllably increase the out-of-plane crystal dimension, while the underlying substrate (black) fixed the in-plane directions. The red balloon represents one helium atom in the crystalline lattice.

 

 

With just a bit of helium, the lighter-than-air element that makes balloons float, scientists have done what was once thought impossible -- they stretched a crystal lattice in just one dimension, allowing them to tune the structure's electronic and magnetic properties. To achieve this elongation, scientists devised a new method called "strain doping." Scientists implant helium ions into a crystal. The helium gently pushes up against the structure, like a balloon under a sheet. The process does not cause structural damage.

"Strain doping" could let scientists tune the electronic and magnetic properties of complex materials creating what's needed to advance transmitting, storing, and otherwise working with electricity. These new types of materials could transmit electricity without loss. Also, this technique brings complex oxide materials closer to commercialization because it can be scaled up for wafer-scale processing and uses existing infrastructure in the semiconductor industry -- leveraging this multi-billion industry with existing fabrication facilities including clean rooms to eliminate dust and specialized machines. Commercializing complex oxides is important because they exhibit exciting phenomena that can address limitations in solar cells, thermoelectrics (conversion of waste heat to electricity), and energy conversion, transmission, and storage. In addition, this technique lets scientists controllably vary one parameter in a material, allowing them to experimentally investigate theoretical predictions of promising properties in different materials.

Scientists believed that changing only one dimension of the crystal lattice structure was impossible. Now researchers led by scientists from Oak Ridge National Laboratory have controllably elongated one direction of a crystalline lattice, using a technique called "strain doping." In this technique, scientists implant a helium ion to achieve a level of structural control previously only available to theory. The team implanted a few helium ions into a crystalline thin film and stretched the structure of the crystal film in one direction, while the other two directions were fixed by an underlying substrate.

 The crystalline film was a complex oxide with electronic properties that are very sensitive to stretching and pulling. The research shows that implanting the helium atoms into the crystalline lattice lets scientists control the strain in the film, thereby tuning the magnetic and electronic properties of the oxide film, and is reversible by removing the helium. Scientists could use this strain doping technique to tune electronic and magnetic properties of other materials. Because this technique uses existing ion implantation infrastructure currently found in the semiconductor industry, it could accelerate the commercial use of complex oxides with finely controlled properties. The research also shows that the elusive goal of experimentally probing theoretical models of materials' properties by varying one parameter at a time may now be a reality.

Story Source:
The above post is reprinted from materials provided by Department of Energy, Office of Science. Note: Content may be edited for style and length.

Journal Reference:

1. Hangwen Guo, Shuai Dong, Philip D. Rack, John D. Budai, Christianne Beekman, Zheng Gai, Wolter Siemons, C. M. Gonzalez, R. Timilsina, Anthony T. Wong, Andreas Herklotz, Paul C. Snijders, Elbio Dagotto, Thomas Z. Ward. Strain Doping: Reversible Single-Axis Control of a Complex Oxide Lattice via Helium Implantation. Physical Review Letters, 2015; 114 (25) DOI: 10.1103/physrevlett.114.256801

Department of Energy, Office of Science. "Atomic blimp stretches a crystal." ScienceDaily. ScienceDaily, 3 August 2016. <www.sciencedaily.com/releases/2016/08/160803095339.htm>.

 

Scientists convert carbon dioxide, create electricity

This graphic explains novel method for capturing the greenhouse gas and converting it to a useful product -- while producing electrical energy.

While the human race will always leave its carbon footprint on the Earth, it must continue to find ways to lessen the impact of its fossil fuel consumption.

"Carbon capture" technologies -- chemically trapping carbon dioxide before it is released into the atmosphere -- is one approach. In a recent study, Cornell University researchers disclose a novel method for capturing the greenhouse gas and converting it to a useful product -- while producing electrical energy.

Lynden Archer, the James A. Friend Family Distinguished Professor of Engineering, and doctoral student Wajdi Al Sadat have developed an oxygen-assisted aluminum/carbon dioxide power cell that uses electrochemical reactions to both sequester the carbon dioxide and produce electricity.

Their paper, "The O2-assisted Al/CO2 electrochemical cell: A system for CO2capture/conversion and electric power generation," was published July 20 inScience Advances.

The group's proposed cell would use aluminum as the anode and mixed streams of carbon dioxide and oxygen as the active ingredients of the cathode. The electrochemical reactions between the anode and the cathode would sequester the carbon dioxide into carbon-rich compounds while also producing electricity and a valuable oxalate as a byproduct.

In most current carbon-capture models, the carbon is captured in fluids or solids, which are then heated or depressurized to release the carbon dioxide. The concentrated gas must then be compressed and transported to industries able to reuse it, or sequestered underground. The findings in the study represent a possible paradigm shift, Archer said.

"The fact that we've designed a carbon capture technology that also generates electricity is, in and of itself, important," he said. "One of the roadblocks to adopting current carbon dioxide capture technology in electric power plants is that the regeneration of the fluids used for capturing carbon dioxide utilize as much as 25 percent of the energy output of the plant. This seriously limits commercial viability of such technology. Additionally, the captured carbon dioxide must be transported to sites where it can be sequestered or reused, which requires new infrastructure."

The group reported that their electrochemical cell generated 13 ampere hours per gram of porous carbon (as the cathode) at a discharge potential of around 1.4 volts. The energy produced by the cell is comparable to that produced by the highest energy-density battery systems.

Another key aspect of their findings, Archer says, is in the generation of superoxide intermediates, which are formed when the dioxide is reduced at the cathode. The superoxide reacts with the normally inert carbon dioxide, forming a carbon-carbon oxalate that is widely used in many industries, including pharmaceutical, fiber and metal smelting.

"A process able to convert carbon dioxide into a more reactive molecule such as an oxalate that contains two carbons opens up a cascade of reaction processes that can be used to synthesize a variety of products," Archer said, noting that the configuration of the electrochemical cell will be dependent on the product one chooses to make from the oxalate.

Al Sadat, who worked on onboard carbon capture vehicles at Saudi Aramco, said this technology in not limited to power-plant applications. "It fits really well with onboard capture in vehicles," he said, "especially if you think of an internal combustion engine and an auxiliary system that relies on electrical power."

He said aluminum is the perfect anode for this cell, as it is plentiful, safer than other high-energy density metals and lower in cost than other potential materials (lithium, sodium) while having comparable energy density to lithium. He added that many aluminum plants are already incorporating some sort of power-generation facility into their operations, so this technology could assist in both power generation and reducing carbon emissions.

A current drawback of this technology is that the electrolyte -- the liquid connecting the anode to the cathode -- is extremely sensitive to water. Ongoing work is addressing the performance of electrochemical systems and the use of electrolytes that are less water-sensitive.

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Story Source:

The above post is reprinted from materials provided by Cornell University. The original item was written by Melissa Osgood. Note: Materials may be edited for content and length.

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Journal Reference:

1. W. I. Al Sadat, L. A. Archer. The O2-assisted Al/CO2 electrochemical cell: A system for CO2 capture/conversion and electric power generation. Science Advances, 2016; 2 (7): e1600968 DOI:10.1126/sciadv.1600968

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Cite This Page:

Cornell University. "Scientists convert carbon dioxide, create electricity." ScienceDaily. ScienceDaily, 4 August 2016. <www.sciencedaily.com/releases/2016/08/160804171642.htm>.

Ultrathin, transparent oxide thin-film transistors developed for wearable display

This image shows ultrathin, flexible, and transparent oxide thin-film transistors produced via the ILLO process.

With the advent of the Internet of Things (IoT) era, strong demand has grown for wearable and transparent displays that can be applied to various fields such as augmented reality (AR) and skin-like thin flexible devices. However, previous flexible transparent displays have posed real challenges to overcome, which are, among others, poor transparency and low electrical performance. To improve the transparency and performance, past research efforts have tried to use inorganic-based electronics, but the fundamental thermal instabilities of plastic substrates have hampered the high temperature process, an essential step necessary for the fabrication of high performance electronic devices.

As a solution to this problem, a research team led by Professors Keon Jae Lee and Sang-Hee Ko Park of the Department of Materials Science and Engineering at the Korea Advanced Institute of Science and Technology (KAIST) has developed ultrathin and transparent oxide thin-film transistors (TFT) for an active-matrix backplane of a flexible display by using the inorganic-based laser lift-off (ILLO) method. Professor Lee's team previously demonstrated the ILLO technology for energy-harvesting (Advanced Materials, February 12, 2014) and flexible memory (Advanced Materials, September 8, 2014) devices.

The research team fabricated a high-performance oxide TFT array on top of a sacrificial laser-reactive substrate. After laser irradiation from the backside of the substrate, only the oxide TFT arrays were separated from the sacrificial substrate as a result of reaction between laser and laser-reactive layer, and then subsequently transferred onto ultrathin plastics (4μm thickness). Finally, the transferred ultrathin-oxide driving circuit for the flexible display was attached conformally to the surface of human skin to demonstrate the possibility of the wearable application. The attached oxide TFTs showed high optical transparency of 83% and mobility of 40 cm^2 V^(-1) s^(-1) even under several cycles of severe bending tests.

Professor Lee said, "By using our ILLO process, the technological barriers for high performance transparent flexible displays have been overcome at a relatively low cost by removing expensive polyimide substrates. Moreover, the high-quality oxide semiconductor can be easily transferred onto skin-like or any flexible substrate for wearable application."

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Story Source:

The above post is reprinted from materials provided by The Korea Advanced Institute of Science and Technology (KAIST). Note: Materials may be edited for content and length.

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Journal Reference:

1. Han Eol Lee, Seungjun Kim, Jongbeom Ko, Hye-In Yeom, Chun-Won Byun, Seung Hyun Lee, Daniel J. Joe, Tae-Hong Im, Sang-Hee Ko Park, Keon Jae Lee. Skin-Like Oxide Thin-Film Transistors for Transparent Displays. Advanced Functional Materials, 2016; DOI:10.1002/adfm.201601296

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Cite This Page:

The Korea Advanced Institute of Science and Technology (KAIST). "Ultrathin, transparent oxide thin-film transistors developed for wearable display." ScienceDaily. ScienceDaily, 29 July 2016. <www.sciencedaily.com/releases/2016/07/160729132848.htm>

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