Category Archives: nanotechnology

Sustainable Nanotechnologies (SUN) project draws to a close in March 2017

Two Oct. 31, 2016 news item on Nanowerk signal the impending sunset date for the European Union’s Sustainable Nanotechnologies (SUN) project. The first Oct. 31, 2016 news item on Nanowerk describes the projects latest achievements,

The results from the 3rd SUN annual meeting showed great advancement of the project. The meeting was held in Edinburgh, Scotland, UK on 4-5 October 2016 where the project partners presented the results obtained during the second reporting period of the project.

SUN is a three and a half year EU project, running from 2013 to 2017, with a budget of about €14 million. Its main goal is to evaluate the risks along the supply chain of engineered nanomaterials and incorporate the results into tools and guidelines for sustainable manufacturing.

The ultimate goal of the SUN Project is the development of an online software Decision Support System – SUNDS – aimed at estimating and managing occupational, consumer, environmental and public health risks from nanomaterials in real industrial products along their lifecycles. The SUNDS beta prototype has been released last October, 2015, and since then the main focus has been on refining the methodologies and testing them on selected case studies i.e. nano-copper oxide based wood preserving paint and nano- sized colourants for plastic car part: organic pigment and carbon black. Obtained results and open issues were discussed during the third annual meeting in order collect feedbacks from the consortium that will inform, in the next months, the implementation of the final version of the SUNDS software system, due by March 2017.

An Oct. 27, 2016 SUN project press release, which originated the news item, adds more information,

Significant interest has been payed towards the results obtained in WP2 (Lifecycle Thinking) which main objectives are to assess the environmental impacts arising from each life cycle stage of the SUN case studies (i.e. Nano-WC-Cobalt (Tungsten Carbide-cobalt) sintered ceramics, Nanocopper wood preservatives, Carbon Nano Tube (CNT) in plastics, Silicon Dioxide (SiO2) as food additive, Nano-Titanium Dioxide (TiO2) air filter system, Organic pigment in plastics and Nanosilver (Ag) in textiles), and compare them to conventional products with similar uses and functionality, in order to develop and validate criteria and guiding principles for green nano-manufacturing. Specifically, the consortium partner COLOROBBIA CONSULTING S.r.l. expressed its willingness to exploit the results obtained from the life cycle assessment analysis related to nanoTiO2 in their industrial applications.

On 6th October [2016], the discussions about the SUNDS advancement continued during a Stakeholder Workshop, where representatives from industry, regulatory and insurance sectors shared their feedback on the use of the decision support system. The recommendations collected during the workshop will be used for the further refinement and implemented in the final version of the software which will be released by March 2017.

The second Oct. 31, 2016 news item on Nanowerk led me to this Oct. 27, 2016 SUN project press release about the activities in the upcoming final months,

The project has designed its final events to serve as an effective platform to communicate the main results achieved in its course within the Nanosafety community and bridge them to a wider audience addressing the emerging risks of Key Enabling Technologies (KETs).

The series of events include the New Tools and Approaches for Nanomaterial Safety Assessment: A joint conference organized by NANOSOLUTIONS, SUN, NanoMILE, GUIDEnano and eNanoMapper to be held on 7 – 9 February 2017 in Malaga, Spain, the SUN-CaLIBRAte Stakeholders workshop to be held on 28 February – 1 March 2017 in Venice, Italy and the SRA Policy Forum: Risk Governance for Key Enabling Technologies to be held on 1- 3 March in Venice, Italy.

Jointly organized by the Society for Risk Analysis (SRA) and the SUN Project, the SRA Policy Forum will address current efforts put towards refining the risk governance of emerging technologies through the integration of traditional risk analytic tools alongside considerations of social and economic concerns. The parallel sessions will be organized in 4 tracks:  Risk analysis of engineered nanomaterials along product lifecycle, Risks and benefits of emerging technologies used in medical applications, Challenges of governing SynBio and Biotech, and Methods and tools for risk governance.

The SRA Policy Forum has announced its speakers and preliminary Programme. Confirmed speakers include:

  • Keld Alstrup Jensen (National Research Centre for the Working Environment, Denmark)
  • Elke Anklam (European Commission, Belgium)
  • Adam Arkin (University of California, Berkeley, USA)
  • Phil Demokritou (Harvard University, USA)
  • Gerard Escher (École polytechnique fédérale de Lausanne, Switzerland)
  • Lisa Friedersdor (National Nanotechnology Initiative, USA)
  • James Lambert (President, Society for Risk Analysis, USA)
  • Andre Nel (The University of California, Los Angeles, USA)
  • Bernd Nowack (EMPA, Switzerland)
  • Ortwin Renn (University of Stuttgart, Germany)
  • Vicki Stone (Heriot-Watt University, UK)
  • Theo Vermeire (National Institute for Public Health and the Environment (RIVM), Netherlands)
  • Tom van Teunenbroek (Ministry of Infrastructure and Environment, The Netherlands)
  • Wendel Wohlleben (BASF, Germany)

The New Tools and Approaches for Nanomaterial Safety Assessment (NMSA) conference aims at presenting the main results achieved in the course of the organizing projects fostering a discussion about their impact in the nanosafety field and possibilities for future research programmes.  The conference welcomes consortium partners, as well as representatives from other EU projects, industry, government, civil society and media. Accordingly, the conference topics include: Hazard assessment along the life cycle of nano-enabled products, Exposure assessment along the life cycle of nano-enabled products, Risk assessment & management, Systems biology approaches in nanosafety, Categorization & grouping of nanomaterials, Nanosafety infrastructure, Safe by design. The NMSA conference key note speakers include:

  • Harri Alenius (University of Helsinki, Finland,)
  • Antonio Marcomini (Ca’ Foscari University of Venice, Italy)
  • Wendel Wohlleben (BASF, Germany)
  • Danail Hristozov (Ca’ Foscari University of Venice, Italy)
  • Eva Valsami-Jones (University of Birmingham, UK)
  • Socorro Vázquez-Campos (LEITAT Technolоgical Center, Spain)
  • Barry Hardy (Douglas Connect GmbH, Switzerland)
  • Egon Willighagen (Maastricht University, Netherlands)
  • Nina Jeliazkova (IDEAconsult Ltd., Bulgaria)
  • Haralambos Sarimveis (The National Technical University of Athens, Greece)

During the SUN-caLIBRAte Stakeholder workshop the final version of the SUN user-friendly, software-based Decision Support System (SUNDS) for managing the environmental, economic and social impacts of nanotechnologies will be presented and discussed with its end users: industries, regulators and insurance sector representatives. The results from the discussion will be used as a foundation of the development of the caLIBRAte’s Risk Governance framework for assessment and management of human and environmental risks of MN and MN-enabled products.

The SRA Policy Forum: Risk Governance for Key Enabling Technologies and the New Tools and Approaches for Nanomaterial Safety Assessment conference are now open for registration. Abstracts for the SRA Policy Forum can be submitted till 15th November 2016.
For further information go to:
www.sra.org/riskgovernanceforum2017
http://www.nmsaconference.eu/

There you have it.

Spinach and plant nanobionics

Who knew that spinach leaves could be turned into electronic devices? The answer is: engineers at the Massachusetts Institute of Technology, according to an Oct. 31, 2016 news item on phys.org,

Spinach is no longer just a superfood: By embedding leaves with carbon nanotubes, MIT engineers have transformed spinach plants into sensors that can detect explosives and wirelessly relay that information to a handheld device similar to a smartphone.

This is one of the first demonstrations of engineering electronic systems into plants, an approach that the researchers call “plant nanobionics.”

An Oct. 31, 2016 MIT news release (also on EurekAlert), which originated the news item, describes the research further (Note: Links have been removed),

“The goal of plant nanobionics is to introduce nanoparticles into the plant to give it non-native functions,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the leader of the research team.

In this case, the plants were designed to detect chemical compounds known as nitroaromatics, which are often used in landmines and other explosives. When one of these chemicals is present in the groundwater sampled naturally by the plant, carbon nanotubes embedded in the plant leaves emit a fluorescent signal that can be read with an infrared camera. The camera can be attached to a small computer similar to a smartphone, which then sends an email to the user.

“This is a novel demonstration of how we have overcome the plant/human communication barrier,” says Strano, who believes plant power could also be harnessed to warn of pollutants and environmental conditions such as drought.

Strano is the senior author of a paper describing the nanobionic plants in the Oct. 31 [2016] issue of Nature Materials. The paper’s lead authors are Min Hao Wong, an MIT graduate student who has started a company called Plantea to further develop this technology, and Juan Pablo Giraldo, a former MIT postdoc who is now an assistant professor at the University of California at Riverside.

Environmental monitoring

Two years ago, in the first demonstration of plant nanobionics, Strano and former MIT postdoc Juan Pablo Giraldo used nanoparticles to enhance plants’ photosynthesis ability and to turn them into sensors for nitric oxide, a pollutant produced by combustion.

Plants are ideally suited for monitoring the environment because they already take in a lot of information from their surroundings, Strano says.

“Plants are very good analytical chemists,” he says. “They have an extensive root network in the soil, are constantly sampling groundwater, and have a way to self-power the transport of that water up into the leaves.”

Strano’s lab has previously developed carbon nanotubes that can be used as sensors to detect a wide range of molecules, including hydrogen peroxide, the explosive TNT, and the nerve gas sarin. When the target molecule binds to a polymer wrapped around the nanotube, it alters the tube’s fluorescence.

In the new study, the researchers embedded sensors for nitroaromatic compounds into the leaves of spinach plants. Using a technique called vascular infusion, which involves applying a solution of nanoparticles to the underside of the leaf, they placed the sensors into a leaf layer known as the mesophyll, which is where most photosynthesis takes place.

They also embedded carbon nanotubes that emit a constant fluorescent signal that serves as a reference. This allows the researchers to compare the two fluorescent signals, making it easier to determine if the explosive sensor has detected anything. If there are any explosive molecules in the groundwater, it takes about 10 minutes for the plant to draw them up into the leaves, where they encounter the detector.

To read the signal, the researchers shine a laser onto the leaf, prompting the nanotubes in the leaf to emit near-infrared fluorescent light. This can be detected with a small infrared camera connected to a Raspberry Pi, a $35 credit-card-sized computer similar to the computer inside a smartphone. The signal could also be detected with a smartphone by removing the infrared filter that most camera phones have, the researchers say.

“This setup could be replaced by a cell phone and the right kind of camera,” Strano says. “It’s just the infrared filter that would stop you from using your cell phone.”

Using this setup, the researchers can pick up a signal from about 1 meter away from the plant, and they are now working on increasing that distance.

Michael McAlpine, an associate professor of mechanical engineering at the University of Minnesota, says this approach holds great potential for engineering not only sensors but many other kinds of bionic plants that might receive radio signals or change color.

“When you have manmade materials infiltrated into a living organism, you can have plants do things that plants don’t ordinarily do,” says McAlpine, who was not involved in the research. “Once you start to think of living organisms like plants as biomaterials that can be combined with electronic materials, this is all possible.”

“A wealth of information”

In the 2014 plant nanobionics study, Strano’s lab worked with a common laboratory plant known as Arabidopsis thaliana. However, the researchers wanted to use common spinach plants for the latest study, to demonstrate the versatility of this technique. “You can apply these techniques with any living plant,” Strano says.

So far, the researchers have also engineered spinach plants that can detect dopamine, which influences plant root growth, and they are now working on additional sensors, including some that track the chemicals plants use to convey information within their own tissues.

“Plants are very environmentally responsive,” Strano says. “They know that there is going to be a drought long before we do. They can detect small changes in the properties of soil and water potential. If we tap into those chemical signaling pathways, there is a wealth of information to access.”

These sensors could also help botanists learn more about the inner workings of plants, monitor plant health, and maximize the yield of rare compounds synthesized by plants such as the Madagascar periwinkle, which produces drugs used to treat cancer.

“These sensors give real-time information from the plant. It is almost like having the plant talk to us about the environment they are in,” Wong says. “In the case of precision agriculture, having such information can directly affect yield and margins.”

Once getting over the excitement, questions spring to mind. How could this be implemented? Is somebody  going to plant a field of spinach and then embed the leaves so they can detect landmines? How will anyone know where to plant the spinach? And on a different track, is this spinach edible? I suspect that if spinach can be successfully used as a sensor, it might not be for explosives but for pollution as the researchers suggest.

Here’s a link to and a citation for the paper,

Nitroaromatic detection and infrared communication from wild-type plants using plant nanobionics by Min Hao Wong, Juan P. Giraldo, Seon-Yeong Kwak, Volodymyr B. Koman, Rosalie Sinclair, Tedrick Thomas Salim Lew, Gili Bisker, Pingwei Liu, & Michael S. Strano. Nature Materials (2016) doi:10.1038/nmat4771 Published online 31 October 2016

This paper is behind a paywall.

The last posting here which featured Strano’s research is in an Aug. 25, 2015 piece about carbon nanotubes and medical sensors.

Are living bacteria providing camouflage for crustaceans?

When you have no place to hide, you can develop some unique methods to avoid detection according to an Oct. 27, 2016 news item on ScienceDaily,

Crustaceans that thrive in the vastness of the open ocean have no place to hide from their predators. Consequently, many creatures that live at depths where sunlight fades to darkness have developed transparent bodies to be less visible when spotted against the twilight by upward-looking predators. But they also face predators with bioluminescent searchlights that should cause the clear animals to flash brightly, just like shining a flashlight across a window pane.

Well, it turns out the midwater crustaceans have camouflage for that too.

An Oct. 27, 2016 Duke University news release on EurekAlert, which originated the news item, expands on the theme,

A new study from Duke University and the Smithsonian Institution has found that these midwater hyperiid amphipods are covered with anti-reflective coatings on their legs and bodies that can dampen the reflection of light by 250-fold in some cases and prevent it from bouncing back to a hungry lantern fish’s eye.

Weirder still, these coatings appear to be made of living bacteria.

When viewed under an electron microscope, the optical coating appears as a sheet of fairly uniform beads, smaller than the wavelength of light. “This coating of little spheres reduces reflections the same way putting a shag carpet on the walls of a recording studio would soften echoes,” said study leader Laura Bagge, a Ph.D. candidate at Duke working with biologist Sönke Johnsen.

The spheres range from 50 to 300 nanometers in diameter on different species of amphipod, but a sphere of 110 nm would be optimal, resulting in up to a 250-fold reduction in reflectance, Bagge calculated. “But every size of these bumps helps.”

Adding to the impression that the spheres might be bacteria, they are sometimes connected with a net of filaments like a biofilm. Each of the seven amphipod species Bagge looked at appears to have its own species of symbiotic optical bacteria. But that’s not a sure thing yet.

“They have all the features of bacteria, but to be 100 percent sure, we’re going to have to perform an in-depth sequencing project,” Bagge said. That project is already underway.

If the spheres are bacteria, they’re very small ones. But it’s not hard to imagine the natural selection — having your host spotted and eaten — that would drive the microbes to an optimal size, said research zoologist Karen Osborn of the Smithsonian National Museum of Natural History, who provided some of the species for this study.

If the optical coating is alive, the researchers will have to figure out how this symbiotic relationship got started in the first place.

Crustaceans molt to grow, shedding the old shell and perhaps its attendant anti-reflective bacteria. But Osborn thinks it would be pretty easy to re-seed the animal’s new shell. “In that whole process, they’re touching the old carapace.” There’s also a species of hyperiid, Phronima, that raises its young in a little floating nest hollowed out of the body of a salp. In that case, the kids could adopt mom’s anti-reflective bacteria pretty easily, Osborn said.

Another amphipod species, Cystisoma, also extrudes brush-like structures on the exoskeleton of its legs which are just the right size and shape to serve the same purpose as the antireflective spheres. At up to six inches in length, Cystisoma has a serious need for stealth.

“They’re remarkably transparent,” Osborn said. “Mostly you see them because you don’t see them. When you pull up a trawl bucket packed full of plankton, you see an empty spot – why is nothing there? You reach in and pull out a Cystisoma. It’s a firm cellophane bag, essentially.”

“We care about this for the basic biology,” Bagge said. But the discovery of living anti-reflective coatings may have technological applications as well. Reflection-reducing “nipple arrays” are being used in the design of glass windows and have also been found in the eyes of moths, apparently to help them see better at night.

Here’s a link to and a citation for the paper,

Nanostructures and Monolayers of Spheres Reduce Surface Reflections in Hyperiid Amphipods by Laura E. Bagge, Karen J. Osborn, Sönke Johnsen. Current Biology DOI: http://dx.doi.org/10.1016/j.cub.2016.09.033 Publication stage: In Press Corrected Proof

This paper is behind a paywall.

Getting your brain cells to glow in the dark

The extraordinary effort to colonize our brains continues apace with a new sensor from Vanderbilt University. From an Oct. 27, 2016 news item on ScienceDaily,

A new kind of bioluminescent sensor causes individual brain cells to imitate fireflies and glow in the dark.

The probe, which was developed by a team of Vanderbilt scientists, is a genetically modified form of luciferase, the enzyme that a number of other species including fireflies use to produce light. …

The scientists created the technique as a new and improved method for tracking the interactions within large neural networks in the brain.

“For a long time neuroscientists relied on electrical techniques for recording the activity of neurons. These are very good at monitoring individual neurons but are limited to small numbers of neurons. The new wave is to use optical techniques to record the activity of hundreds of neurons at the same time,” said Carl Johnson, Stevenson Professor of Biological Sciences, who headed the effort.

Individual neuron glowing with bioluminescent light produced by a new genetically engineered sensor. (Johnson Lab / Vanderbilt University)

Individual neuron glowing with bioluminescent light produced by a new genetically engineered sensor. (Johnson Lab / Vanderbilt University)

An Oct. 27, 2016 Vanderbilt University news release (also on EurekAlert) by David Salisbury, which originated the news item, explains the work in more detail,

“Most of the efforts in optical recording use fluorescence, but this requires a strong external light source which can cause the tissue to heat up and can interfere with some biological processes, particularly those that are light sensitive,” he [Carl Johnson] said.

Based on their research on bioluminescence in “a scummy little organism, the green alga Chlamydomonas, that nobody cares much about” Johnson and his colleagues realized that if they could combine luminescence with optogenetics – a new biological technique that uses light to control cells, particularly neurons, in living tissue – they could create a powerful new tool for studying brain activity.

“There is an inherent conflict between fluorescent techniques and optogenetics. The light required to produce the fluorescence interferes with the light required to control the cells,” said Johnson. “Luminescence, on the other hand, works in the dark!”

Johnson and his collaborators – Associate Professor Donna Webb, Research Assistant Professor Shuqun Shi, post-doctoral student Jie Yang and doctoral student Derrick Cumberbatch in biological sciences and Professor Danny Winder and postdoctoral student Samuel Centanni in molecular physiology and biophysics – genetically modified a type of luciferase obtained from a luminescent species of shrimp so that it would light up when exposed to calcium ions. Then they hijacked a virus that infects neurons and attached it to their sensor molecule so that the sensors are inserted into the cell interior.

The researchers picked calcium ions because they are involved in neuron activation. Although calcium levels are high in the surrounding area, normally they are very low inside the neurons. However, the internal calcium level spikes briefly when a neuron receives an impulse from one of its neighbors.

They tested their new calcium sensor with one of the optogenetic probes (channelrhodopsin) that causes the calcium ion channels in the neuron’s outer membrane to open, flooding the cell with calcium. Using neurons grown in culture they found that the luminescent enzyme reacted visibly to the influx of calcium produced when the probe was stimulated by brief light flashes of visible light.

To determine how well their sensor works with larger numbers of neurons, they inserted it into brain slices from the mouse hippocampus that contain thousands of neurons. In this case they flooded the slices with an increased concentration of potassium ions, which causes the cell’s ion channels to open. Again, they found that the sensor responded to the variations in calcium concentrations by brightening and dimming.

“We’ve shown that the approach works,” Johnson said. “Now we have to determine how sensitive it is. We have some indications that it is sensitive enough to detect the firing of individual neurons, but we have to run more tests to determine if it actually has this capability.”

Here’s a link to and a citation for the paper,

Coupling optogenetic stimulation with NanoLuc-based luminescence (BRET) Ca++ sensing by Jie Yang, Derrick Cumberbatch, Samuel Centanni, Shu-qun Shi, Danny Winder, Donna Webb, & Carl Hirschie Johnson. Nature Communications 7, Article number: 13268 (2016)  doi:10.1038/ncomms13268 Published online: 27 October 2016

This paper is open access.

The memristor as computing device

An Oct. 27, 2016 news item on Nanowerk both builds on the Richard Feynman legend/myth and announces some new work with memristors,

In 1959 renowned physicist Richard Feynman, in his talk “[There’s] Plenty of Room at the Bottom,” spoke of a future in which tiny machines could perform huge feats. Like many forward-looking concepts, his molecule and atom-sized world remained for years in the realm of science fiction.

And then, scientists and other creative thinkers began to realize Feynman’s nanotechnological visions.

In the spirit of Feynman’s insight, and in response to the challenges he issued as a way to inspire scientific and engineering creativity, electrical and computer engineers at UC Santa Barbara [University of California at Santa Barbara, UCSB] have developed a design for a functional nanoscale computing device. The concept involves a dense, three-dimensional circuit operating on an unconventional type of logic that could, theoretically, be packed into a block no bigger than 50 nanometers on any side.

A figure depicting the structure of stacked memristors with dimensions that could satisfy the Feynman Grand Challenge Photo Credit: Courtesy Image

A figure depicting the structure of stacked memristors with dimensions that could satisfy the Feynman Grand Challenge. Photo Credit: Courtesy Image

An Oct. 27, 2016 UCSB news release (also on EurekAlert) by Sonia Fernandez, which originated the news item, offers a basic explanation of the work (useful for anyone unfamiliar with memristors) along with more detail,

“Novel computing paradigms are needed to keep up with the demand for faster, smaller and more energy-efficient devices,” said Gina Adam, postdoctoral researcher at UCSB’s Department of Computer Science and lead author of the paper “Optimized stateful material implication logic for three dimensional data manipulation,” published in the journal Nano Research. “In a regular computer, data processing and memory storage are separated, which slows down computation. Processing data directly inside a three-dimensional memory structure would allow more data to be stored and processed much faster.”

While efforts to shrink computing devices have been ongoing for decades — in fact, Feynman’s challenges as he presented them in his 1959 talk have been met — scientists and engineers continue to carve out room at the bottom for even more advanced nanotechnology. A nanoscale 8-bit adder operating in 50-by-50-by-50 nanometer dimension, put forth as part of the current Feynman Grand Prize challenge by the Foresight Institute, has not yet been achieved. However, the continuing development and fabrication of progressively smaller components is bringing this virus-sized computing device closer to reality, said Dmitri Strukov, a UCSB professor of computer science.

“Our contribution is that we improved the specific features of that logic and designed it so it could be built in three dimensions,” he said.

Key to this development is the use of a logic system called material implication logic combined with memristors — circuit elements whose resistance depends on the most recent charges and the directions of those currents that have flowed through them. Unlike the conventional computing logic and circuitry found in our present computers and other devices, in this form of computing, logic operation and information storage happen simultaneously and locally. This greatly reduces the need for components and space typically used to perform logic operations and to move data back and forth between operation and memory storage. The result of the computation is immediately stored in a memory element, which prevents data loss in the event of power outages — a critical function in autonomous systems such as robotics.

In addition, the researchers reconfigured the traditionally two-dimensional architecture of the memristor into a three-dimensional block, which could then be stacked and packed into the space required to meet the Feynman Grand Prize Challenge.

“Previous groups show that individual blocks can be scaled to very small dimensions, let’s say 10-by-10 nanometers,” said Strukov, who worked at technology company Hewlett-Packard’s labs when they ramped up development of memristors and material implication logic. By applying those results to his group’s developments, he said, the challenge could easily be met.

The tiny memristors are being heavily researched in academia and in industry for their promising uses in memory storage and neuromorphic computing. While implementations of material implication logic are rather exotic and not yet mainstream, uses for it could pop up any time, particularly in energy scarce systems such as robotics and medical implants.

“Since this technology is still new, more research is needed to increase its reliability and lifetime and to demonstrate large scale three-dimensional circuits tightly packed in tens or hundreds of layers,” Adam said.

HP Labs, mentioned in the news release, announced the ‘discovery’ of memristors and subsequent application of engineering control in two papers in 2008.

Here’s a link to and a citation for the UCSB paper,

Optimized stateful material implication logic for threedimensional data manipulation by Gina C. Adam, Brian D. Hoskins, Mirko Prezioso, &Dmitri B. Strukov. Nano Res. (2016) pp. 1 – 10. doi:10.1007/s12274-016-1260-1 First Online: 29 September 2016

This paper is behind a paywall.

You can find many articles about memristors here by using either ‘memristor’ or ‘memristors’ as your search term.

Solar and wind energy storage via food waste and carbon nanotubes

Scientists are researching devices other than batteries for wind and solar energy storage according to an Oct. 27, 2016 news item on Nanowerk,

Saving up excess solar and wind energy for times when the sun is down or the air is still requires a storage device. Batteries get the most attention as a promising solution although pumped hydroelectric storage is currently used most often. Now researchers reporting in ACS’ Journal of Physical Chemistry C are advancing another potential approach using sugar alcohols — an abundant waste product of the food industry — mixed with carbon nanotubes.

An Oct. 26, 2016 American Chemical Society (ACS) news release, which originated the news item, expands on the theme,

Electricity generation from renewables has grown steadily over recent years, and the U.S. Energy Information Administration (EIA) expects this rise to continue. To keep up with this expansion, use of battery and flywheel energy storage has increased in the past five years, according to the EIA. These technologies take advantage of chemical and mechanical energy. But storing energy as heat is another feasible option. Some scientists have been exploring sugar alcohols as a possible material for making thermal storage work, but this direction has some limitations. Huaichen Zhang, Silvia V. Nedea and colleagues wanted to investigate how mixing carbon nanotubes with sugar alcohols might affect their energy storage properties.

The researchers analyzed what happened when carbon nanotubes of varying sizes were mixed with two types of sugar alcohols — erythritol and xylitol, both naturally occurring compounds in foods. Their findings showed that with one exception, heat transfer within a mixture decreased as the nanotube diameter decreased. They also found that in general, higher density combinations led to better heat transfer. The researchers say these new insights could assist in the future design of sugar alcohol-based energy storage systems.

Here’s a link to and a citation for the paper,

Nanoscale Heat Transfer in Carbon Nanotubes – Sugar Alcohol Composite as Heat Storage Materials
by Huaichen Zhang, Camilo C. M. Rindt, David M. J. Smeulders, and Silvia V. Nedea. J. Phys. Chem. C, 2016, 120 (38), pp 21915–21924 DOI: 10.1021/acs.jpcc.6b05466 Publication Date (Web): August 30, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Should nanotechnology take its cue from green chemistry?

An editorial by John C. Warner for Green Chemistry Letters and Review suggests that nanotechnology should take its cue from green chemistry research (from a Taylor & Francis Publishing Oct. 27, 2016 press release [received via email]),

Warner is the President and Chief Technology Officer at the Warner Babcock Institute for Green Chemistry, and often whilst touring visitors around the campus finds himself posed with the question “do you work in nanotechnology?”, perhaps linked to the association between high-tech materials science and this area.

He feels that a new science such as nanotechnology is much like a new child trying to learn their native language. Whilst the basic understanding of the language is present to form sentences relating quite complex ideas, the structural understanding of the grammar is not. Soon the child will, somewhat ironically, start using verbs, nouns, and adjectives to learn about verbs, nouns, and adjectives!

He feels that the same can be said for nanotechnology, as often the instrumentation and tools used to study nanomaterials are constructed using nanostructures, and by understanding the rules governing their behaviour, so the scientific field can advance.

In such a new field, he feels that bringing in ideas from green chemistry will help words like ‘safety’ and ‘toxicity’ become embedded in the vocabulary of nanotechnology. This is critical to avoid creating materials and processes that have negative consequences – not only being unethical but also slowing the rate of progress in the field.

Warner makes some interesting points but I suspect his ‘child’ analogy works better in speech than in text.

Here’s a link and a citation for the editorial,

Purpose and intent at the intersection of nanotechnology and green chemistry by John C. Warner.  Green Chemistry Letters and Reviews
Volume 9, 2016 – Issue 4 Pages 208-209 Published online: 27 Sep 2016

This is open access.

Smartphone battery inspired by your guts?

The conversion of bacteria from an enemy to be vanquished at all costs to a ‘frenemy’, a friendly enemy supplying possible solutions for problems is fascinating. An Oct. 26, 2016 news item on Nanowerk falls into the ‘frenemy’ camp,

A new prototype of a lithium-sulphur battery – which could have five times the energy density of a typical lithium-ion battery – overcomes one of the key hurdles preventing their commercial development by mimicking the structure of the cells which allow us to absorb nutrients.

Researchers have developed a prototype of a next-generation lithium-sulphur battery which takes its inspiration in part from the cells lining the human intestine. The batteries, if commercially developed, would have five times the energy density of the lithium-ion batteries used in smartphones and other electronics.

An Oct. 26, 2016 University of Cambridge press release (also on EurekAlert), which originated the news item, expands on the theme and provides some good explanations of how lithium-ion batteries and lithium-sulphur batteries work (Note: A link has been removed),

The new design, by researchers from the University of Cambridge, overcomes one of the key technical problems hindering the commercial development of lithium-sulphur batteries, by preventing the degradation of the battery caused by the loss of material within it. The results are reported in the journal Advanced Functional Materials.

Working with collaborators at the Beijing Institute of Technology, the Cambridge researchers based in Dr Vasant Kumar’s team in the Department of Materials Science and Metallurgy developed and tested a lightweight nanostructured material which resembles villi, the finger-like protrusions which line the small intestine. In the human body, villi are used to absorb the products of digestion and increase the surface area over which this process can take place.

In the new lithium-sulphur battery, a layer of material with a villi-like structure, made from tiny zinc oxide wires, is placed on the surface of one of the battery’s electrodes. This can trap fragments of the active material when they break off, keeping them electrochemically accessible and allowing the material to be reused.

“It’s a tiny thing, this layer, but it’s important,” said study co-author Dr Paul Coxon from Cambridge’s Department of Materials Science and Metallurgy. “This gets us a long way through the bottleneck which is preventing the development of better batteries.”

A typical lithium-ion battery is made of three separate components: an anode (negative electrode), a cathode (positive electrode) and an electrolyte in the middle. The most common materials for the anode and cathode are graphite and lithium cobalt oxide respectively, which both have layered structures. Positively-charged lithium ions move back and forth from the cathode, through the electrolyte and into the anode.

The crystal structure of the electrode materials determines how much energy can be squeezed into the battery. For example, due to the atomic structure of carbon, each carbon atom can take on six lithium ions, limiting the maximum capacity of the battery.

Sulphur and lithium react differently, via a multi-electron transfer mechanism meaning that elemental sulphur can offer a much higher theoretical capacity, resulting in a lithium-sulphur battery with much higher energy density. However, when the battery discharges, the lithium and sulphur interact and the ring-like sulphur molecules transform into chain-like structures, known as a poly-sulphides. As the battery undergoes several charge-discharge cycles, bits of the poly-sulphide can go into the electrolyte, so that over time the battery gradually loses active material.

The Cambridge researchers have created a functional layer which lies on top of the cathode and fixes the active material to a conductive framework so the active material can be reused. The layer is made up of tiny, one-dimensional zinc oxide nanowires grown on a scaffold. The concept was trialled using commercially-available nickel foam for support. After successful results, the foam was replaced by a lightweight carbon fibre mat to reduce the battery’s overall weight.

“Changing from stiff nickel foam to flexible carbon fibre mat makes the layer mimic the way small intestine works even further,” said study co-author Dr Yingjun Liu.

This functional layer, like the intestinal villi it resembles, has a very high surface area. The material has a very strong chemical bond with the poly-sulphides, allowing the active material to be used for longer, greatly increasing the lifespan of the battery.

“This is the first time a chemically functional layer with a well-organised nano-architecture has been proposed to trap and reuse the dissolved active materials during battery charging and discharging,” said the study’s lead author Teng Zhao, a PhD student from the Department of Materials Science & Metallurgy. “By taking our inspiration from the natural world, we were able to come up with a solution that we hope will accelerate the development of next-generation batteries.”

For the time being, the device is a proof of principle, so commercially-available lithium-sulphur batteries are still some years away. Additionally, while the number of times the battery can be charged and discharged has been improved, it is still not able to go through as many charge cycles as a lithium-ion battery. However, since a lithium-sulphur battery does not need to be charged as often as a lithium-ion battery, it may be the case that the increase in energy density cancels out the lower total number of charge-discharge cycles.

“This is a way of getting around one of those awkward little problems that affects all of us,” said Coxon. “We’re all tied in to our electronic devices – ultimately, we’re just trying to make those devices work better, hopefully making our lives a little bit nicer.”

Here’s a link to and a citation for the paper,

Advanced Lithium–Sulfur Batteries Enabled by a Bio-Inspired Polysulfide Adsorptive Brush by Teng Zhao, Yusheng Ye, Xiaoyu Peng, Giorgio Divitini, Hyun-Kyung Kim, Cheng-Yen Lao, Paul R. Coxon, Kai Xi, Yingjun Liu, Caterina Ducati, Renjie Chen, R. Vasant Kumar. Advanced Functional Materials DOI: 10.1002/adfm.201604069 First published: 26 October 2016

This paper is behind a paywall.

Caption: This is a computer visualization of villi-like battery material. Credit: Teng Zhao

Caption: This is a computer visualization of villi-like battery material. Credit: Teng Zhao

Boron nitride-graphene hybrid nanostructures could lead to next generation ‘green’ cars

An Oct. 24, 2016 phys.org news item describes research which may lead to improved fuel storage in ‘green’ cars,

Layers of graphene separated by nanotube pillars of boron nitride may be a suitable material to store hydrogen fuel in cars, according to Rice University scientists.

The Department of Energy has set benchmarks for storage materials that would make hydrogen a practical fuel for light-duty vehicles. The Rice lab of materials scientist Rouzbeh Shahsavari determined in a new computational study that pillared boron nitride and graphene could be a candidate.

An Oct. 24, 2016 Rice University news release (also on EurekAlert), which originated the news item, provides more detail (Note: Links have been removed),

Shahsavari’s lab had already determined through computer models how tough and resilient pillared graphene structures would be, and later worked boron nitride nanotubes into the mix to model a unique three-dimensional architecture. (Samples of boron nitride nanotubes seamlessly bonded to graphene have been made.)

Just as pillars in a building make space between floors for people, pillars in boron nitride graphene make space for hydrogen atoms. The challenge is to make them enter and stay in sufficient numbers and exit upon demand.

In their latest molecular dynamics simulations, the researchers found that either pillared graphene or pillared boron nitride graphene would offer abundant surface area (about 2,547 square meters per gram) with good recyclable properties under ambient conditions. Their models showed adding oxygen or lithium to the materials would make them even better at binding hydrogen.

They focused the simulations on four variants: pillared structures of boron nitride or pillared boron nitride graphene doped with either oxygen or lithium. At room temperature and in ambient pressure, oxygen-doped boron nitride graphene proved the best, holding 11.6 percent of its weight in hydrogen (its gravimetric capacity) and about 60 grams per liter (its volumetric capacity); it easily beat competing technologies like porous boron nitride, metal oxide frameworks and carbon nanotubes.

At a chilly -321 degrees Fahrenheit, the material held 14.77 percent of its weight in hydrogen.

The Department of Energy’s current target for economic storage media is the ability to store more than 5.5 percent of its weight and 40 grams per liter in hydrogen under moderate conditions. The ultimate targets are 7.5 weight percent and 70 grams per liter.

Shahsavari said hydrogen atoms adsorbed to the undoped pillared boron nitride graphene, thanks to  weak van der Waals forces. When the material was doped with oxygen, the atoms bonded strongly with the hybrid and created a better surface for incoming hydrogen, which Shahsavari said would likely be delivered under pressure and would exit when pressure is released.

“Adding oxygen to the substrate gives us good bonding because of the nature of the charges and their interactions,” he said. “Oxygen and hydrogen are known to have good chemical affinity.”

He said the polarized nature of the boron nitride where it bonds with the graphene and the electron mobility of the graphene itself make the material highly tunable for applications.

“What we’re looking for is the sweet spot,” Shahsavari said, describing the ideal conditions as a balance between the material’s surface area and weight, as well as the operating temperatures and pressures. “This is only practical through computational modeling, because we can test a lot of variations very quickly. It would take experimentalists months to do what takes us only days.”

He said the structures should be robust enough to easily surpass the Department of Energy requirement that a hydrogen fuel tank be able to withstand 1,500 charge-discharge cycles.

Shayeganfar [Farzaneh Shayeganfar], a former visiting scholar at Rice, is an instructor at Shahid Rajaee Teacher Training University in Tehran, Iran.

 

Caption: Simulations by Rice University scientists show that pillared graphene boron nitride may be a suitable storage medium for hydrogen-powered vehicles. Above, the pink (boron) and blue (nitrogen) pillars serve as spacers for carbon graphene sheets (gray). The researchers showed the material worked best when doped with oxygen atoms (red), which enhanced its ability to adsorb and desorb hydrogen (white). Credit: Lei Tao/Rice University

Caption: Simulations by Rice University scientists show that pillared graphene boron nitride may be a suitable storage medium for hydrogen-powered vehicles. Above, the pink (boron) and blue (nitrogen) pillars serve as spacers for carbon graphene sheets (gray). The researchers showed the material worked best when doped with oxygen atoms (red), which enhanced its ability to adsorb and desorb hydrogen (white). Credit: Lei Tao/Rice University

Here’s a link to and a citation for the paper,

Oxygen and Lithium Doped Hybrid Boron-Nitride/Carbon Networks for Hydrogen Storage by Farzaneh Shayeganfar and Rouzbeh Shahsavari. Langmuir,  DOI: 10.1021/acs.langmuir.6b02997 Publication Date (Web): October 23, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

I last featured research by Shayeganfar and  Shahsavari on graphene and boron nitride in a Jan. 14, 2016 posting.

Growing shells atom-by-atom

The University of California at Davis (UC Davis) and the University of Washington (state) collaborated in research into fundamental questions on how aquatic animals grow. From an Oct. 24, 2016 news item on ScienceDaily,

For the first time scientists can see how the shells of tiny marine organisms grow atom-by-atom, a new study reports. The advance provides new insights into the mechanisms of biomineralization and will improve our understanding of environmental change in Earth’s past.

An Oct. 24, 2016 UC Davis news release by Becky Oskin, which originated the news item, provides more detail,

Led by researchers from the University of California, Davis and the University of Washington, with key support from the U.S. Department of Energy’s Pacific Northwest National Laboratory, the team examined an organic-mineral interface where the first calcium carbonate crystals start to appear in the shells of foraminifera, a type of plankton.

“We’ve gotten the first glimpse of the biological event horizon,” said Howard Spero, a study co-author and UC Davis geochemistry professor. …

Foraminifera’s Final Frontier

The researchers zoomed into shells at the atomic level to better understand how growth processes may influence the levels of trace impurities in shells. The team looked at a key stage — the interaction between the biological ‘template’ and the initiation of shell growth. The scientists produced an atom-scale map of the chemistry at this crucial interface in the foraminifera Orbulina universa. This is the first-ever measurement of the chemistry of a calcium carbonate biomineralization template, Spero said.

Among the new findings are elevated levels of sodium and magnesium in the organic layer. This is surprising because the two elements are not considered important architects in building shells, said lead study author Oscar Branson, a former postdoctoral researcher at UC Davis who is now at the Australian National University in Canberra. Also, the greater concentrations of magnesium and sodium in the organic template may need to be considered when investigating past climate with foraminifera shells.

Calibrating Earth’s Climate

Most of what we know about past climate (beyond ice core records) comes from chemical analyses of shells made by the tiny, one-celled creatures called foraminifera, or “forams.” When forams die, their shells sink and are preserved in seafloor mud. The chemistry preserved in ancient shells chronicles climate change on Earth, an archive that stretches back nearly 200 million years.

The calcium carbonate shells incorporate elements from seawater — such as calcium, magnesium and sodium — as the shells grow. The amount of trace impurities in a shell depends on both the surrounding environmental conditions and how the shells are made. For example, the more magnesium a shell has, the warmer the ocean was where that shell grew.

“Finding out how much magnesium there is in a shell can allow us to find out the temperature of seawater going back up to 150 million years,” Branson said.

But magnesium levels also vary within a shell, because of nanometer-scale growth bands. Each band is one day’s growth (similar to the seasonal variations in tree rings). Branson said considerable gaps persist in understanding what exactly causes the daily bands in the shells.

“We know that shell formation processes are important for shell chemistry, but we don’t know much about these processes or how they might have changed through time,” he said. “This adds considerable uncertainty to climate reconstructions.”

Atomic Maps

The researchers used two cutting-edge techniques: Time-of-Flight Secondary Ionization Mass Spectrometry (ToF-SIMS) and Laser-Assisted Atom Probe Tomography (APT). ToF-SIMS is a two-dimensional chemical mapping technique which shows the elemental composition of the surface of a polished sample. The technique was developed for the elemental analysis of complex polymer materials, and is just starting to be applied to natural samples like shells.

APT is an atomic-scale three-dimensional mapping technique, developed for looking at internal structures in advanced alloys, silicon chips and superconductors. The APT imaging was performed at the Environmental Molecular Sciences Laboratory, a U.S. Department of Energy Office of Science User Facility at the Pacific Northwest National Laboratory.

This foraminifera is just starting to form its adult spherical shell. The calcium carbonate spherical shell first forms on a thin organic template, shown here in white, around the dark juvenile skeleton. Calcium carbonate spines then extend from the juvenile skeleton through the new sphere and outward. The bright flecks are algae that the foraminifera “farm” for sustenance.Howard Spero/University of California, Davis

This foraminifera is just starting to form its adult spherical shell. The calcium carbonate spherical shell first forms on a thin organic template, shown here in white, around the dark juvenile skeleton. Calcium carbonate spines then extend from the juvenile skeleton through the new sphere and outward. The bright flecks are algae that the foraminifera “farm” for sustenance.Howard Spero/University of California, Davis

An Oct. 24, 2016 University of Washington (state) news release (also on EurekAlert) adds more information (there is a little repetition),

Unseen out in the ocean, countless single-celled organisms grow protective shells to keep them safe as they drift along, living off other tiny marine plants and animals. Taken together, the shells are so plentiful that when they sink they provide one of the best records for the history of ocean chemistry.

Oceanographers at the University of Washington and the University of California, Davis, have used modern tools to provide an atomic-scale look at how that shell first forms. Results could help answer fundamental questions about how these creatures grow under different ocean conditions, in the past and in the future. …

“There’s this debate among scientists about whether shelled organisms are slaves to the chemistry of the ocean, or whether they have the physiological capacity to adapt to changing environmental conditions,” said senior author Alex Gagnon, a UW assistant professor of oceanography.

The new work shows, he said, that they do exert some biologically-based control over shell formation.

“I think it’s just incredible that we were able to peer into the intricate details of those first moments that set how a seashell forms,” Gagnon said. “And that’s what sets how much of the rest of the skeleton will grow.”

The results could eventually help understand how organisms at the base of the marine food chain will respond to more acidic waters. And while the study looked at one organism, Orbulina universa, which is important for understanding past climate, the same method could be used for other plankton, corals and shellfish.

The study used tools developed for materials science and semiconductor research to view the shell formation in the most detail yet to see how the organisms turn seawater into solid mineral.

“We’re interested more broadly in the question ‘How do organisms make shells?'” said first author Oscar Branson, a former postdoctoral researcher at the University of California, Davis who is now at Australian National University in Canberra. “We’ve focused on a key stage in mineral formation — the interaction between biological template materials and the initiation of shell growth by an organism.”

These tiny single-celled animals, called foraminifera, can’t reproduce anywhere but in their natural surroundings, which prevents breeding them in captivity. The researchers caught juvenile foraminifera by diving in deep water off Southern California. Then they then raised them in the lab, using tiny pipettes to feed them brine shrimp during their weeklong lives.

Marine shells are made from calcium carbonate, drawing the calcium and carbon from surrounding seawater. But the animal first grows a soft template for the mineral to grow over. Because this template is trapped within the growing skeleton, it acts as a snapshot of the chemical conditions during the first part of skeletal growth.

To see this chemical picture, the authors analyzed tiny sections of foraminifera template with a technique called atom probe tomography at the Pacific Northwest National Laboratory. This tool creates an atom-by-atom picture of the organic template, which was located using a chemical tag.

Results show that the template contains more magnesium and sodium atoms than expected, and that this could influence how the mineral in the shell begins to grow around it.

“One of the key stages in growing a skeleton is when you make that first bit, when you build that first bit of structure. Anything that changes that process is a key control point,” Gagnon said.

The clumping suggests that magnesium and sodium play a role in the first stages of shell growth. If their availability changes for any reason, that could influence how the shell grows beyond what simple chemistry would predict.

“We can say who the players are — further experiments will have to tell us exactly how important each of them is,” Gagnon said.

Follow-up work will try to grow the shells and create models of their formation to see how the template affects growth under different conditions, such as more acidic water.

“Translating that into, ‘Can these forams survive ocean acidification?’ is still many steps down the line,” Gagnon cautioned. “But you can’t do that until you have a picture of what that surface actually looks like.”

The researchers also hope that by better understanding the exact mechanism of shell growth they could tease apart different aspects of seafloor remains so the shells can be used to reconstruct more than just the ocean’s past temperature. In the study, they showed that the template was responsible for causing fine lines in the shells — one example of the rich chemical information encoded in fossil shells.

“There are ways that you could separate the effects of temperature from other things and learn much more about the past ocean,” Gagnon said.

Here’s a link to and a citation for the paper,

Nanometer-Scale Chemistry of a Calcite Biomineralization Template: Implications for Skeletal Composition and Nucleation, Proceedings of the National Academy of Sciences, www.pnas.org/cgi/doi/10.1073/pnas.1522864113

This paper is behind a paywall.