Tag Archives: Holland

‘Nano-hashtags’ for Majorana particles?

The ‘nano-hashtags’ are in fact (assuming a minor leap of imagination) nanowires that resemble hashtags.

Scanning electron microscope image of the device wherein clearly a ‘hashtag’ is formed. Credit: Eindhoven University of Technology

An August 23, 2017 news item on ScienceDaily makes the announcement,

In Nature, an international team of researchers from Eindhoven University of Technology [Netherlands], Delft University of Technology [Netherlands] and the University of California — Santa Barbara presents an advanced quantum chip that will be able to provide definitive proof of the mysterious Majorana particles. These particles, first demonstrated in 2012, are their own antiparticle at one and the same time. The chip, which comprises ultrathin networks of nanowires in the shape of ‘hashtags’, has all the qualities to allow Majorana particles to exchange places. This feature is regarded as the smoking gun for proving their existence and is a crucial step towards their use as a building block for future quantum computers.

An August 23, 2017 Eindhoven University press release (also on EurekAlert), which originated the news item, provides some context and information about the work,

In 2012 it was big news: researchers from Delft University of Technology and Eindhoven University of Technology presented the first experimental signatures for the existence of the Majorana fermion. This particle had been predicted in 1937 by the Italian physicist Ettore Majorana and has the distinctive property of also being its own anti-particle. The Majorana particles emerge at the ends of a semiconductor wire, when in contact with a superconductor material.

Smoking gun

While the discovered particles may have properties typical to Majoranas, the most exciting proof could be obtained by allowing two Majorana particles to exchange places, or ‘braid’ as it is scientifically known. “That’s the smoking gun,” suggests Erik Bakkers, one of the researchers from Eindhoven University of Technology. “The behavior we then see could be the most conclusive evidence yet of Majoranas.”

Crossroads

In the Nature paper that is published today [August 23, 2017], Bakkers and his colleagues present a new device that should be able to show this exchanging of Majoranas. In the original experiment in 2012 two Majorana particles were found in a single wire but they were not able to pass each other without immediately destroying the other. Thus the researchers quite literally had to create space. In the presented experiment they formed intersections using the same kinds of nanowire so that four of these intersections form a ‘hashtag’, #, and thus create a closed circuit along which Majoranas are able to move.

Etch and grow

The researchers built their hashtag device starting from scratch. The nanowires are grown from a specially etched substrate such that they form exactly the desired network which they then expose to a stream of aluminium particles, creating layers of aluminium, a superconductor, on specific spots on the wires – the contacts where the Majorana particles emerge. Places that lie ‘in the shadow’ of other wires stay uncovered.

Leap in quality

The entire process happens in a vacuum and at ultra-cold temperature (around -273 degree Celsius). “This ensures very clean, pure contacts,” says Bakkers, “and enables us to make a considerable leap in the quality of this kind of quantum device.” The measurements demonstrate for a number of electronic and magnetic properties that all the ingredients are present for the Majoranas to braid.

Quantum computers

If the researchers succeed in enabling the Majorana particles to braid, they will at once have killed two birds with one stone. Given their robustness, Majoranas are regarded as the ideal building block for future quantum computers that will be able to perform many calculations simultaneously and thus many times faster than current computers. The braiding of two Majorana particles could form the basis for a qubit, the calculation unit of these computers.

Travel around the world

An interesting detail is that the samples have traveled around the world during the fabrication, combining unique and synergetic activities of each research institution. It started in Delft with patterning and etching the substrate, then to Eindhoven for nanowire growth and to Santa Barbara for aluminium contact formation. Finally back to Delft via Eindhoven for the measurements.

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

Epitaxy of advanced nanowire quantum devices by Sasa Gazibegovic, Diana Car, Hao Zhang, Stijn C. Balk, John A. Logan, Michiel W. A. de Moor, Maja C. Cassidy, Rudi Schmits, Di Xu, Guanzhong Wang, Peter Krogstrup, Roy L. M. Op het Veld, Kun Zuo, Yoram Vos, Jie Shen, Daniël Bouman, Borzoyeh Shojaei, Daniel Pennachio, Joon Sue Lee, Petrus J. van Veldhoven, Sebastian Koelling, Marcel A. Verheijen, Leo P. Kouwenhoven, Chris J. Palmstrøm, & Erik P. A. M. Bakkers. Nature 548, 434–438 (24 August 2017) doi:10.1038/nature23468 Published online 23 August 2017

This paper is behind a paywall.

Dexter Johnson has some additional insight (interview with one of the researchers) in an Aug. 29, 2017 posting on his Nanoclast blog (on the IEEE [institute of Electrical and Electronics Engineers] website).

Cosmopolitanism and the Local in Science and Nature (a three year Canadian project nearing its end date)

Working on a grant from Canada’s Social Sciences and Humanities Research Council (SSHRC), the  Cosmopolitanism and the Local in Science and Nature project has been establishing a ‘cosmopolitanism’ research network that critiques the eurocentric approach so beloved of Canadian academics and has set up nodes across Canada and in India and Southeast Asia.

I first wrote about the project in a Dec. 12, 2014 posting which also featured a job listing. It seems I was there for the beginning and now for the end. For one of the project’s blog postings in its final months, they’re profiling one of their researchers (Dr. Letitia Meynell, Sept. 6, 2017 posting),

1. What is your current place of research?

I am an associate professor in philosophy at Dalhousie University, cross appointed with gender and women studies.

2. Could you give us some details about your education background?

My 1st degree was in Theater, which I did at York University. I did, however, minor in Philosophy and I have always had a particular interest in philosophy of science. So, my minor was perhaps a little anomalous, comprising courses on philosophy of physics, philosophy of nature, and the philosophy of Karl Popper along with courses on aesthetics and existentialism. After taking a few more courses in philosophy at the University of Calgary, I enrolled there for a Master’s degree, writing a thesis on conceptualization, with a view to its role in aesthetics and epistemology. From there I moved to the University of Western Ontario where I brought these three interests together, writing a thesis on the epistemology of pictures in science. Throughout these studies I maintained a keen interest in feminist philosophy, especially the politics of knowledge, and I have always seen my work on pictures in science as fitting into broader feminist commitments.

3. What projects are you currently working on and what are some projects you’ve worked on in the past?

4. What’s one thing you particularly enjoy about working in your field?

5. How do you relate your work to the broader topic of ‘cosmopolitanism and the local’?

As feminist philosophers have long realized, having perspectives on a topic that are quite different to your own is incredibly powerful for critically assessing both your own views and those of others. So, for instance, if you want to address the exploitation of nonhuman animals in our society it is incredibly powerful to consider how people from, say, South Asian traditions have thought about the differences, similarities, and relationships between humans and other animals. Keeping non-western perspectives in mind, even as one works in a western philosophical tradition, helps one to be both more rigorous in one’s analyses and less dogmatic. Rigor and critical openness are, in my opinion, central virtues of philosophy and, indeed, science.

Dr. Maynell will be speaking at the ‘Bridging the Gap: Scientific Imagination Meets Aesthetic Imagination‘ conference Oct. 5-6, 2017 at the London School of Economics,

On 5–6 October, this 2-day conference aims to connect work on artistic and scientific imagination, and to advance our understanding of the epistemic and heuristic roles that imagination can play.

Why, how, and when do scientists imagine, and what epistemological roles does the imagination play in scientific progress? Over the past few years, many philosophical accounts have emerged that are relevant to these questions. Roman Frigg, Arnon Levy, and Adam Toon have developed theories of scientific models that place imagination at the heart of modelling practice. And James R. Brown, Tamar Gendler, James McAllister, Letitia Meynell, and Nancy Nersessian have developed theories that recognize the indispensable role of the imagination in the performance of thought experiments. On the other hand, philosophers like Michael Weisberg dismiss imagination-based views of scientific modelling as mere “folk ontology”, and John D. Norton seems to claim that thought experiments are arguments whose imaginary components are epistemologically irrelevant.

In this conference we turn to aesthetics for help in addressing issues concerning scientific imagination-use. Aesthetics is said to have begun in 1717 with an essay called “The Pleasures of the Imagination” by Joseph Addison, and ever since imagination has been what Michael Polyani called “the cornerstone of aesthetic theory”. In recent years Kendall Walton has fruitfully explored the fundamental relevance of imagination for understanding literary, visual and auditory fictions. And many others have been inspired to do the same, including Greg Currie, David Davies, Peter Lamarque, Stein Olsen, and Kathleen Stock.

This conference aims to connect work on artistic and scientific imagination, and to advance our understanding of the epistemic and heuristic roles that imagination can play. Specific topics may include:

  • What kinds of imagination are involved in science?
  • What is the relation between scientific imagination and aesthetic imagination?
  • What are the structure and limits of knowledge and understanding acquired through imagination?
  • From a methodological point of view, how can aesthetic considerations about imagination play a role in philosophical accounts of scientific reasoning?
  • What can considerations about scientific imagination contribute to our understanding of aesthetic imagination?

The conference will include eight invited talks and four contributed papers. Two of the four slots for contributed papers are being reserved for graduate students, each of whom will receive a travel bursary of £100.

Invited speakers

Margherita Arcangeli (Humboldt University, Berlin)

Andrej Bicanski (Institute of Cognitive Neuroscience, University College London)

Gregory Currie (University of York)

Jim Faeder (University of Pittsburgh School of Medicine)

Tim de Mey (Erasmus University of Rotterdam)

Laetitia Meynell (Dalhousie University, Canada)

Adam Toon (University of Exeter)

Margot Strohminger (Humboldt University, Berlin)

This event is organised by LSE’s Centre for Philosophy of Natural and Social Science and it is co-sponsored by the British Society of Aesthetics, the Mind Association, the Aristotelian Society and the Marie Skłodowska-Curie grant agreement No 654034.

I wonder if they’ll be rubbing shoulders with Angelina Jolie? She is slated to be teaching there in Fall 2017 according to a May 23, 2016 news item in the Guardian (Note: Links have been removed),

The Hollywood actor and director has been appointed a visiting professor at the London School of Economics, teaching a course on the impact of war on women.

From 2017, Jolie will join the former foreign secretary William Hague as a “professor in practice”, the university announced on Monday, as part of a new MSc course on women, peace and security, which LSE says is the first of its kind in the world.

The course, it says, is intended to “[develop] strategies to promote gender equality and enhance women’s economic, social and political participation and security”, with visiting professors playing an active part in giving lectures, participating in workshops and undertaking their own research.

Getting back to ‘Cosmopolitanism’, some of the principals organized a summer 2017 event (from a Sept. 6, 2017 posting titled: Summer Events – 25th International Congress of History of Science and Technology),

CosmoLocal partners Lesley Cormack (University of Alberta, Canada), Gordon McOuat (University of King’s College, Halifax, Canada), and Dhruv Raina (Jawaharlal Nehru University, India) organized a symposium “Cosmopolitanism and the Local in Science and Nature” as part of the 25th International Congress of History of Science and Technology.  The conference was held July 23-29, 2017, in Rio de Janeiro, Brazil.  The abstract of the CosmoLocal symposium is below, and a pdf version can be found here.

Science, and its associated technologies, is typically viewed as “universal”. At the same time we were also assured that science can trace its genealogy to Europe in a period of rising European intellectual and imperial global force, ‘going outwards’ towards the periphery. As such, it is strikingly parochial. In a kind of sad irony, the ‘subaltern’ was left to retell that tale as one of centre-universalism dominating a traditionalist periphery. Self-described ‘modernity’ and ‘the west’ (two intertwined concepts of recent and mutually self-supporting origin) have erased much of the local engagement and as such represent science as emerging sui generis, moving in one direction. This story is now being challenged within sociology, political theory and history.

… Significantly, scholars who study the history of science in Asia and India have been examining different trajectories for the origin and meaning of science. It is now time for a dialogue between these approaches. Grounding the dialogue is the notion of a “cosmopolitical” science. “Cosmopolitics” is a term borrowed from Kant’s notion of perpetual peace and modern civil society, imagining shared political, moral and economic spaces within which trade, politics and reason get conducted.  …

The abstract is a little ‘high falutin’ but I’m glad to see more efforts being made in  Canada to understand science and its history as a global affair.

Art masterpieces are turning into soap

This piece of research has made a winding trek through the online science world. First it was featured in an April 20, 2017 American Chemical Society news release on EurekAlert,

A good art dealer can really clean up in today’s market, but not when some weird chemistry wreaks havoc on masterpieces. Art conservators started to notice microscopic pockmarks forming on the surfaces of treasured oil paintings that cause the images to look hazy. It turns out the marks are eruptions of paint caused, weirdly, by soap that forms via chemical reactions. Since you have no time to watch paint dry, we explain how paintings from Rembrandts to O’Keefes are threatened by their own compositions — and we don’t mean the imagery.

Here’s the video,

Interestingly, this seems to be based on a May 23, 2016 article by Sarah Everts for Chemical and Engineering News (an American Society publication) Note: Links have been removed,

When conservator Petria Noble first peered at Rembrandt’s “Anatomy Lesson of Dr. Nicolaes Tulp” under a microscope back in 1996, she was surprised to find pockmarks across the nearly 400-year-old painting’s surface.

Each tiny crater was just a few hundred micrometers in diameter, no wider than the period at the end of this sentence. The painting’s surface was entirely riddled with these curious structures, giving it “a dull, rather hazy, gritty surface,” Noble says.

A structure of lead nonanoate.

The crystal structures of metal soaps vary: Shown here is lead nonanoate, based on a structure solved by Cecil Dybowski at the University of Delaware and colleagues at the Metropolitan Museum of Art. Dashed lines are nearest oxygen neighbors.

This concerned Noble, who was tasked with cleaning the masterpiece with her then-colleague Jørgen Wadum at the Mauritshuis museum, the painting’s home in The Hague.

When Noble called physicist Jaap Boon, then at the Foundation for Fundamental Research on Matter in Amsterdam, to help figure out what was going on, the researchers unsuspectingly embarked on an investigation that would transform the art world’s understanding of aging paint.

More recently this ‘metal soaps in paintings’ story has made its way into a May 16, 2017 news item on phys.org,

An oil painting is not a permanent and unchangeable object, but undergoes a very slow change in the outer and inner structure. Metal soap formation is of great importance. Joen Hermans has managed to recreate the molecular structure of old oil paints: a big step towards better preservation of works of art. He graduated cum laude on Tuesday 9 May [2017] at the University of Amsterdam with NWO funding from the Science4Arts program.

A May 15, 2017 Netherlands Organization for Scientific Research (NWO) press release, which originated the phys.org news item, provides more information about Hermans’ work (albeit some of this is repetitive),

Johannes Vermeer, View of Delft, c. 1660 - 1661 (Mauritshuis, The Hague)Johannes Vermeer, View of Delft, c. 1660 – 1661 (Mauritshuis, The Hague)

Paint can fade, varnish can discolour and paintings can collect dust and dirt. Joen Hermans has examined the chemical processes behind ageing processes in paints. ‘While restorers do their best to repair any damages that have occurred, the fact remains that at present we do not know enough about the molecular structure of ageing oil paint and the chemical processes they undergo’, says Hermans. ‘This makes it difficult to predict with confidence how paints will react to restoration treatments or to changes in a painting’s environment.’

‘Sand grains’ In the red tiles of 'View of Delft' by Johannes Vermeer shows 'lead soap spheres' (Annelies van Loon, UvA/Mauritshuis)‘Sand grains’ In the red tiles of ‘View of Delft’ by Johannes Vermeer shows ‘lead soap spheres’ (Annelies van Loon, UvA/Mauritshuis)

Visible to the naked eye

Hermans explains that in its simplest form, oil paint is a mixture of pigment and drying oil, which forms the binding element. Colour pigments are often metal salts. ‘When the pigment and the drying oil are combined, an incredibly complicated chemical process begins’, says Hermans, ‘which continues for centuries’. The fatty acids in the oil form a polymer network when exposed to oxygen in the air. Meanwhile, metal ions react with the oil on the surface of the grains of pigment.

‘A common problem when conserving oil paintings is the formation of what are known as metal soaps’, Hermans continues. These are compounds of metal ions and fatty acids. The formation of metal soaps is linked to various ways in which paint deteriorates, as when it becomes increasingly brittle, transparent or forms a crust on the paint surface. Hermans: ‘You can see clumps of metal soap with the naked eye on some paintings, like Rembrandt’s Anatomy Lesson of Dr Nicolaes Tulp or Vermeer’s View of Delft’. Around 70 per cent of all oil paintings show signs of metal soap formation.’

Conserving valuable paintings

Hermans has studied in detail how metal soaps form. He began by defining the structure of metal soaps. One of the things he discovered was that the process that causes metal ions to move in the painting is crucial to the speed at which the painting ages. Hermans also managed to recreate the molecular structure of old oil paints, making it possible to simulate and study the behaviour of old paints without actually having to remove samples from Rembrandt’s Night Watch. Hermans hopes this knowledge will contribute towards a solid foundation for the conservation of valuable works of art.

I imagine this will make anyone who owns an oil painting or appreciates paintings in general pause for thought and the inclination to utter a short prayer for conservators to find a solution.

Explaining the link between air pollution and heart disease?

An April 26, 2017 news item on Nanowerk announces research that may explain the link between heart disease and air pollution (Note: A link has been removed),

Tiny particles in air pollution have been associated with cardiovascular disease, which can lead to premature death. But how particles inhaled into the lungs can affect blood vessels and the heart has remained a mystery.

Now, scientists have found evidence in human and animal studies that inhaled nanoparticles can travel from the lungs into the bloodstream, potentially explaining the link between air pollution and cardiovascular disease. Their results appear in the journal ACS Nano (“Inhaled Nanoparticles Accumulate at Sites of Vascular Disease”).

An April 26, 2017 American Chemical Society news release on EurekAlert, which originated the news item,  expands on the theme,

The World Health Organization estimates that in 2012, about 72 percent of premature deaths related to outdoor air pollution were due to ischemic heart disease and strokes. Pulmonary disease, respiratory infections and lung cancer were linked to the other 28 percent. Many scientists have suspected that fine particles travel from the lungs into the bloodstream, but evidence supporting this assumption in humans has been challenging to collect. So Mark Miller and colleagues at the University of Edinburgh in the United Kingdom and the National Institute for Public Health and the Environment in the Netherlands used a selection of specialized techniques to track the fate of inhaled gold nanoparticles.

In the new study, 14 healthy volunteers, 12 surgical patients and several mouse models inhaled gold nanoparticles, which have been safely used in medical imaging and drug delivery. Soon after exposure, the nanoparticles were detected in blood and urine. Importantly, the nanoparticles appeared to preferentially accumulate at inflamed vascular sites, including carotid plaques in patients at risk of a stroke. The findings suggest that nanoparticles can travel from the lungs into the bloodstream and reach susceptible areas of the cardiovascular system where they could possibly increase the likelihood of a heart attack or stroke, the researchers say.

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

Inhaled Nanoparticles Accumulate at Sites of Vascular Disease by Mark R. Miller, Jennifer B. Raftis, Jeremy P. Langrish, Steven G. McLean, Pawitrabhorn Samutrtai, Shea P. Connell, Simon Wilson, Alex T. Vesey, Paul H. B. Fokkens, A. John F. Boere, Petra Krystek, Colin J. Campbell, Patrick W. F. Hadoke, Ken Donaldson, Flemming R. Cassee, David E. Newby, Rodger Duffin, and Nicholas L. Mills. ACS Nano, Article ASAP DOI: 10.1021/acsnano.6b08551 Publication Date (Web): April 26, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

Carbon nanotubes self-assembling into transistors on a gold substrate

I’m not sure this work is ready for commercialization (I think not) but it’s certainly intriguing. From an April 5, 2017 news item on ScienceDaily,

Carbon nanotubes can be used to make very small electronic devices, but they are difficult to handle. University of Groningen scientists, together with colleagues from the University of Wuppertal and IBM Zurich, have developed a method to select semiconducting nanotubes from a solution and make them self-assemble on a circuit of gold electrodes. …

An April 5, 2017 University of Groningen (Netherlands) press release on EurekAlert, which originated the news item, explains the work in more detail,

The results look deceptively simple: a self-assembled transistor with nearly 100 percent purity and very high electron mobility. But it took ten years to get there. University of Groningen Professor of Photophysics and Optoelectronics Maria Antonietta Loi designed polymers which wrap themselves around specific carbon nanotubes in a solution of mixed tubes. Thiol side chains on the polymer bind the tubes to the gold electrodes, creating the resultant transistor.

Patent

‘In our previous work, we learned a lot about how polymers attach to specific carbon nanotubes’, Loi explains. These nanotubes can be depicted as a rolled sheet of graphene, the two-dimensional form of carbon. ‘Depending on the way the sheets are rolled up, they have properties ranging from semiconductor to semi-metallic to metallic.’ Only the semiconductor tubes can be used to fabricate transistors, but the production process always results in a mixture.

‘We had the idea of using polymers with thiol side chains some time ago’, says Loi. The idea was that as sulphur binds to metals, it will direct polymer-wrapped nanotubes towards gold electrodes. While Loi was working on the problem, IBM even patented the concept. ‘But there was a big problem in the IBM work: the polymers with thiols also attached to metallic nanotubes and included them in the transistors, which ruined them.’

Solution

Loi’s solution was to reduce the thiol content of the polymers, with the assistance of polymer chemists from the University of Wuppertal. ‘What we have now shown is that this concept of bottom-up assembly works: by using polymers with a low concentration of thiols, we can selectively bring semiconducting nanotubes from a solution onto a circuit.’ The sulphur-gold bond is strong, so the nanotubes are firmly fixed: enough even to stay there after sonication of the transistor in organic solvents.

The production process is simple: metallic patterns are deposited on a carrier , which is then dipped into a solution of carbon nanotubes. The electrodes are spaced to achieve proper alignment: ‘The tubes are some 500 nanometres long, and we placed the electrodes for the transistors at intervals of 300 nanometres. The next transistor is over 500 nanometres away.’ The spacing limits the density of the transistors, but Loi is confident that this could be increased with clever engineering.

‘Over the last years, we have created a library of polymers that select semiconducting nanotubes and developed a better understanding of how the structure and composition of the polymers influences which carbon nanotubes they select’, says Loi. The result is a cheap and scalable production method for nanotube electronics. So what is the future for this technology? Loi: ‘It is difficult to predict whether the industry will develop this idea, but we are working on improvements, and this will eventually bring the idea closer to the market.’

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

On-Chip Chemical Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes (SWNTs): Toward Robust and Scale Invariant SWNTs Transistors by Vladimir Derenskyi, Widianta Gomulya, Wytse Talsma, Jorge Mario Salazar-Rios, Martin Fritsch, Peter Nirmalraj, Heike Riel, Sybille Allard, Ullrich Scherf, and Maria A. Loi. Advanced Materials DOI: 10.1002/adma.201606757 Version of Record online: 5 APR 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

High-performance, low-energy artificial synapse for neural network computing

This artificial synapse is apparently an improvement on the standard memristor-based artificial synapse but that doesn’t become clear until reading the abstract for the paper. First, there’s a Feb. 20, 2017 Stanford University news release by Taylor Kubota (dated Feb. 21, 2017 on EurekAlert), Note: Links have been removed,

For all the improvements in computer technology over the years, we still struggle to recreate the low-energy, elegant processing of the human brain. Now, researchers at Stanford University and Sandia National Laboratories have made an advance that could help computers mimic one piece of the brain’s efficient design – an artificial version of the space over which neurons communicate, called a synapse.

“It works like a real synapse but it’s an organic electronic device that can be engineered,” said Alberto Salleo, associate professor of materials science and engineering at Stanford and senior author of the paper. “It’s an entirely new family of devices because this type of architecture has not been shown before. For many key metrics, it also performs better than anything that’s been done before with inorganics.”

The new artificial synapse, reported in the Feb. 20 issue of Nature Materials, mimics the way synapses in the brain learn through the signals that cross them. This is a significant energy savings over traditional computing, which involves separately processing information and then storing it into memory. Here, the processing creates the memory.

This synapse may one day be part of a more brain-like computer, which could be especially beneficial for computing that works with visual and auditory signals. Examples of this are seen in voice-controlled interfaces and driverless cars. Past efforts in this field have produced high-performance neural networks supported by artificially intelligent algorithms but these are still distant imitators of the brain that depend on energy-consuming traditional computer hardware.

Building a brain

When we learn, electrical signals are sent between neurons in our brain. The most energy is needed the first time a synapse is traversed. Every time afterward, the connection requires less energy. This is how synapses efficiently facilitate both learning something new and remembering what we’ve learned. The artificial synapse, unlike most other versions of brain-like computing, also fulfills these two tasks simultaneously, and does so with substantial energy savings.

“Deep learning algorithms are very powerful but they rely on processors to calculate and simulate the electrical states and store them somewhere else, which is inefficient in terms of energy and time,” said Yoeri van de Burgt, former postdoctoral scholar in the Salleo lab and lead author of the paper. “Instead of simulating a neural network, our work is trying to make a neural network.”

The artificial synapse is based off a battery design. It consists of two thin, flexible films with three terminals, connected by an electrolyte of salty water. The device works as a transistor, with one of the terminals controlling the flow of electricity between the other two.

Like a neural path in a brain being reinforced through learning, the researchers program the artificial synapse by discharging and recharging it repeatedly. Through this training, they have been able to predict within 1 percent of uncertainly what voltage will be required to get the synapse to a specific electrical state and, once there, it remains at that state. In other words, unlike a common computer, where you save your work to the hard drive before you turn it off, the artificial synapse can recall its programming without any additional actions or parts.

Testing a network of artificial synapses

Only one artificial synapse has been produced but researchers at Sandia used 15,000 measurements from experiments on that synapse to simulate how an array of them would work in a neural network. They tested the simulated network’s ability to recognize handwriting of digits 0 through 9. Tested on three datasets, the simulated array was able to identify the handwritten digits with an accuracy between 93 to 97 percent.

Although this task would be relatively simple for a person, traditional computers have a difficult time interpreting visual and auditory signals.

“More and more, the kinds of tasks that we expect our computing devices to do require computing that mimics the brain because using traditional computing to perform these tasks is becoming really power hungry,” said A. Alec Talin, distinguished member of technical staff at Sandia National Laboratories in Livermore, California, and senior author of the paper. “We’ve demonstrated a device that’s ideal for running these type of algorithms and that consumes a lot less power.”

This device is extremely well suited for the kind of signal identification and classification that traditional computers struggle to perform. Whereas digital transistors can be in only two states, such as 0 and 1, the researchers successfully programmed 500 states in the artificial synapse, which is useful for neuron-type computation models. In switching from one state to another they used about one-tenth as much energy as a state-of-the-art computing system needs in order to move data from the processing unit to the memory.

This, however, means they are still using about 10,000 times as much energy as the minimum a biological synapse needs in order to fire. The researchers are hopeful that they can attain neuron-level energy efficiency once they test the artificial synapse in smaller devices.

Organic potential

Every part of the device is made of inexpensive organic materials. These aren’t found in nature but they are largely composed of hydrogen and carbon and are compatible with the brain’s chemistry. Cells have been grown on these materials and they have even been used to make artificial pumps for neural transmitters. The voltages applied to train the artificial synapse are also the same as those that move through human neurons.

All this means it’s possible that the artificial synapse could communicate with live neurons, leading to improved brain-machine interfaces. The softness and flexibility of the device also lends itself to being used in biological environments. Before any applications to biology, however, the team plans to build an actual array of artificial synapses for further research and testing.

Additional Stanford co-authors of this work include co-lead author Ewout Lubberman, also of the University of Groningen in the Netherlands, Scott T. Keene and Grégorio C. Faria, also of Universidade de São Paulo, in Brazil. Sandia National Laboratories co-authors include Elliot J. Fuller and Sapan Agarwal in Livermore and Matthew J. Marinella in Albuquerque, New Mexico. Salleo is an affiliate of the Stanford Precourt Institute for Energy and the Stanford Neurosciences Institute. Van de Burgt is now an assistant professor in microsystems and an affiliate of the Institute for Complex Molecular Studies (ICMS) at Eindhoven University of Technology in the Netherlands.

This research was funded by the National Science Foundation, the Keck Faculty Scholar Funds, the Neurofab at Stanford, the Stanford Graduate Fellowship, Sandia’s Laboratory-Directed Research and Development Program, the U.S. Department of Energy, the Holland Scholarship, the University of Groningen Scholarship for Excellent Students, the Hendrik Muller National Fund, the Schuurman Schimmel-van Outeren Foundation, the Foundation of Renswoude (The Hague and Delft), the Marco Polo Fund, the Instituto Nacional de Ciência e Tecnologia/Instituto Nacional de Eletrônica Orgânica in Brazil, the Fundação de Amparo à Pesquisa do Estado de São Paulo and the Brazilian National Council.

Here’s an abstract for the researchers’ paper (link to paper provided after abstract) and it’s where you’ll find the memristor connection explained,

The brain is capable of massively parallel information processing while consuming only ~1–100fJ per synaptic event1, 2. Inspired by the efficiency of the brain, CMOS-based neural architectures3 and memristors4, 5 are being developed for pattern recognition and machine learning. However, the volatility, design complexity and high supply voltages for CMOS architectures, and the stochastic and energy-costly switching of memristors complicate the path to achieve the interconnectivity, information density, and energy efficiency of the brain using either approach. Here we describe an electrochemical neuromorphic organic device (ENODe) operating with a fundamentally different mechanism from existing memristors. ENODe switches at low voltage and energy (<10pJ for 103μm2 devices), displays >500 distinct, non-volatile conductance states within a ~1V range, and achieves high classification accuracy when implemented in neural network simulations. Plastic ENODes are also fabricated on flexible substrates enabling the integration of neuromorphic functionality in stretchable electronic systems6, 7. Mechanical flexibility makes ENODes compatible with three-dimensional architectures, opening a path towards extreme interconnectivity comparable to the human brain.

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

A non-volatile organic electrochemical device as a low-voltage artificial synapse for neuromorphic computing by Yoeri van de Burgt, Ewout Lubberman, Elliot J. Fuller, Scott T. Keene, Grégorio C. Faria, Sapan Agarwal, Matthew J. Marinella, A. Alec Talin, & Alberto Salleo. Nature Materials (2017) doi:10.1038/nmat4856 Published online 20 February 2017

This paper is behind a paywall.

ETA March 8, 2017 10:28 PST: You may find this this piece on ferroelectricity and neuromorphic engineering of interest (March 7, 2017 posting titled: Ferroelectric roadmap to neuromorphic computing).

A European nanotechnology ‘dating’ event for researchers and innovators

A Dec. 13, 2016 Cambridge Network press release announces a networking (dating) event for nanotechnology researchers and industry partners,

The Enterprise Europe Network, in partnership with Innovate UK, the Dutch Ministry of Economic Affairs, the Netherlands Enterprise Agency, Knowledge Transfer Network and the UK Department of Business Energy & Industrial Strategy invite you to participate in an international partnering event and information day for the Nanotechnologies and Advanced Materials themes of the NMBP [Nannotechnologies, Advanced Materials, Biotechnology and Production] Work Programme within Horizon 2020.

This one-day event on 4th April 2017 will introduce the forthcoming calls for proposals, present insights and expectations from the European Commission, and offer a unique international networking experience to forge the winning partnerships of the future

The programme will include presentations from the European Commission and its evaluators and an opportunity to build prospective project partnerships with leading research organisations and cutting-edge innovators from across industry.

A dedicated brokerage session will allow you to expand your international network and create strong consortia through scheduled one-to-one meetings. Participants will also have the opportunity to meet with National Contact Points (UK and Netherlands confirmed) and representatives of the Enterprise Europe Network and the UK’s Knowledge Transfer Network.

The day will also include an optional proposal writing workshop in which delegates will be given valuable tips and insight into the preparation of a winning proposal including a review of the key evaluation criteria.

This event is dedicated to Key Enabling Technologies and will target upcoming calls in the following thematic fields: Nanotechnologies; Advanced materials

Participation for the day is free of charge, but early registration is recommended as the number of participants is limited.  Please note that participation may be limited to a maximum of two delegates per organization.  To register, please do so via the b2match website using this link: https://www.b2match.eu/h2020nmp2017

How does it work? Once you have registered, your profile will be screened by our event management team and once completed you will receive a validation email confirming your participation. You can browse the participant list and book meetings with organisations you are interested in, and a week before the event you will receive your personal meeting schedule.

Why attend? Improve your chances of success by understanding the main issues and expectations for upcoming H2020 calls based on feedback from previous rounds. It’s a great opportunity to raise your profile with future project partners from industry and research through pre-arranged one-to-one meetings. There is also the chance to hear from an experienced H2020 evaluator to gain tips and insight for the preparation of a strong proposal.

Good luck on getting registered for the event. By the way, the Enterprise Europe Network webpage for this event describes it as an Horizon 2020 Brokerage Event.

2016 Nobel Chemistry Prize for molecular machines

Wednesday, Oct. 5, 2016 was the day three scientists received the Nobel Prize in Chemistry for their work on molecular machines, according to an Oct. 5, 2016 news item on phys.org,

Three scientists won the Nobel Prize in chemistry on Wednesday [Oct. 5, 2016] for developing the world’s smallest machines, 1,000 times thinner than a human hair but with the potential to revolutionize computer and energy systems.

Frenchman Jean-Pierre Sauvage, Scottish-born Fraser Stoddart and Dutch scientist Bernard “Ben” Feringa share the 8 million kronor ($930,000) prize for the “design and synthesis of molecular machines,” the Royal Swedish Academy of Sciences said.

Machines at the molecular level have taken chemistry to a new dimension and “will most likely be used in the development of things such as new materials, sensors and energy storage systems,” the academy said.

Practical applications are still far away—the academy said molecular motors are at the same stage that electrical motors were in the first half of the 19th century—but the potential is huge.

Dexter Johnson in an Oct. 5, 2016 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website) provides some insight into the matter (Note: A link has been removed),

In what seems to have come both as a shock to some of the recipients and a confirmation to all those who envision molecular nanotechnology as the true future of nanotechnology, Bernard Feringa, Jean-Pierre Sauvage, and Sir J. Fraser Stoddart have been awarded the 2016 Nobel Prize in Chemistry for their development of molecular machines.

The Nobel Prize was awarded to all three of the scientists based on their complementary work over nearly three decades. First, in 1983, Sauvage (currently at Strasbourg University in France) was able to link two ring-shaped molecules to form a chain. Then, eight years later, Stoddart, a professor at Northwestern University in Evanston, Ill., demonstrated that a molecular ring could turn on a thin molecular axle. Then, eight years after that, Feringa, a professor at the University of Groningen, in the Netherlands, built on Stoddardt’s work and fabricated a molecular rotor blade that could spin continually in the same direction.

Speaking of the Nobel committee’s selection, Donna Nelson, a chemist and president of the American Chemical Society told Scientific American: “I think this topic is going to be fabulous for science. When the Nobel Prize is given, it inspires a lot of interest in the topic by other researchers. It will also increase funding.” Nelson added that this line of research will be fascinating for kids. “They can visualize it, and imagine a nanocar. This comes at a great time, when we need to inspire the next generation of scientists.”

The Economist, which appears to be previewing an article about the 2016 Nobel prizes ahead of the print version, has this to say in its Oct. 8, 2016 article,

BIGGER is not always better. Anyone who doubts that has only to look at the explosion of computing power which has marked the past half-century. This was made possible by continual shrinkage of the components computers are made from. That success has, in turn, inspired a search for other areas where shrinkage might also yield dividends.

One such, which has been poised delicately between hype and hope since the 1990s, is nanotechnology. What people mean by this term has varied over the years—to the extent that cynics might be forgiven for wondering if it is more than just a fancy rebranding of the word “chemistry”—but nanotechnology did originally have a fairly clear definition. It was the idea that machines with moving parts could be made on a molecular scale. And in recognition of this goal Sweden’s Royal Academy of Science this week decided to award this year’s Nobel prize for chemistry to three researchers, Jean-Pierre Sauvage, Sir Fraser Stoddart and Bernard Feringa, who have never lost sight of nanotechnology’s original objective.

Optimists talk of manufacturing molecule-sized machines ranging from drug-delivery devices to miniature computers. Pessimists recall that nanotechnology is a field that has been puffed up repeatedly by both researchers and investors, only to deflate in the face of practical difficulties.

There is, though, reason to hope it will work in the end. This is because, as is often the case with human inventions, Mother Nature has got there first. One way to think of living cells is as assemblies of nanotechnological machines. For example, the enzyme that produces adenosine triphosphate (ATP)—a molecule used in almost all living cells to fuel biochemical reactions—includes a spinning molecular machine rather like Dr Feringa’s invention. This works well. The ATP generators in a human body turn out so much of the stuff that over the course of a day they create almost a body-weight’s-worth of it. Do something equivalent commercially, and the hype around nanotechnology might prove itself justified.

Congratulations to the three winners!

Nuclear magnetic resonance microscope breaks records

Dutch researchers have found a way to apply the principles underlying magnetic resonance imaging (MRI) to a microscope designed *for* examining matter and life at the nanoscale. From a July 15, 2016 news item on phys.org,

A new nuclear magnetic resonance (NMR) microscope gives researchers an improved instrument to study fundamental physical processes. It also offers new possibilities for medical science—for example, to better study proteins in Alzheimer’s patients’ brains. …

A Leiden Institute of Physics press release, which originated the news item, expands on the theme,

If you get a knee injury, physicians use an MRI machine to look right through the skin and see what exactly is the problem. For this trick, doctors make use of the fact that our body’s atomic nuclei are electrically charged and spin around their axis. Just like small electromagnets they induce their own magnetic field. By placing the knee in a uniform magnetic field, the nuclei line up with their axis pointing in the same direction. The MRI machine then sends a specific type of radio waves through the knee, causing some axes to flip. After turning off this signal, those nuclei flip back after some time, under excitation of a small radio wave. Those waves give away the atoms’ location, and provide physicians with an accurate image of the knee.

NMR

MRI is the medical application of Nuclear Magnetic Resonance (NMR), which is based on the same principle and was invented by physicists to conduct fundamental research on materials. One of the things they study with NMR is the so-called relaxation time. This is the time scale at which the nuclei flip back and it gives a lot of information about a material’s properties.

Microscope

To study materials on the smallest of scales as well, physicists go one step further and develop NMR microscopes, with which they study the mechanics behind physical processes at the level of a group of atoms. Now Leiden PhD students Jelmer Wagenaar and Arthur de Haan have built an NMR microscope, together with principal investigator Tjerk Oosterkamp, that operates at a record temperature of 42 milliKelvin—close to absolute zero. In their article in Physical Review Applied they prove it works by measuring the relaxation time of copper. They achieved a thousand times higher sensitivity than existing NMR microscopes—also a world record.

Alzheimer

With their microscope, they give physicists an instrument to conduct fundamental research on many physical phenomena, like systems displaying strange behavior in extreme cold. And like NMR eventually led to MRI machines in hospitals, NMR microscopes have great potential too. Wagenaar: ‘One example is that you might be able to use our technique to study Alzheimer patients’ brains at the molecular level, in order to find out how iron is locked up in proteins.’

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

Probing the Nuclear Spin-Lattice Relaxation Time at the Nanoscale by J. J. T. Wagenaar, A. M. J. den Haan, J. M. de Voogd, L. Bossoni, T. A. de Jong, M. de Wit, K. M. Bastiaans, D. J. Thoen, A. Endo, T. M. Klapwijk, J. Zaanen, and T. H. Oosterkamp. Phys. Rev. Applied 6, 014007 DOI:http://dx.doi.org/10.1103/PhysRevApplied.6.014007 Published 15 July 2016

This paper is open access.

*’fro’ changed to ‘for’ on Aug. 3, 2016.

3D brain-on-a-chip from the University of Twente

Dutch researchers have developed a 3D brain-on-a-chip according to a June 23, 2016 news item on Nanowerk,

To study brain cell’s operation and test the effect of medication on individual cells, the conventional Petri dish with flat electrodes is not sufficient. For truly realistic studies, cells have to flourish within three-dimensional surroundings.

Bart Schurink, researcher at University of Twente’s MESA+ Institute for Nanotechnology, has developed a sieve with 900 openings, each of which has the shape of an inverted pyramid. On top of this array of pyramids, a micro-reactor takes care of cell growth. Schurink defends his PhD thesis June 23 [2016].

A June 23, 2016 University of Twente press release, which originated the news item, provides more detail,

A brain-on-a-chip demands more than a series of electrodes in 2D, on which brain cells can be cultured. To mimic the brain in a realistic way, you need facilities for fluid flow, and the cells need some freedom for themselves even when they are kept at predefined spaces. Schurink therefore developed a micro sieve structure with hundreds of openings on a 2 by 2 mm surface. Each of these holes has the shape of  an inverted pyramid. Each pyramid, in turn, is equipped with an electrode, for measuring electrical signals or sending stimuli to the network. At the same time, liquids can flow through tiny holes, needed to capture the cells and for sending nutrients or medication to a single cell.

NEURONAL NETWORK

After neurons have been placed inside all the pyramids, they will start to form a network. This is not just a 2D network between the holes: by placing a micro reactor on top of the sieve, a neuron network can develop in the vertical direction as well. Growth and electrical activity can be monitored subsequently: each individual cell can be identified by the pyramid it is in. Manufacturing this system, demands a lot of both the production facilities at UT’s NanoLab and of creative solutions the designers come up with. For example, finding the proper way of guaranteeing  the same dimensions for every hole, is quite challenging.

Schurink’s new µSEA (micro sieve electrode array) has been tested with living cells, from the brains of laboratory rats. Both the positioning of the cells and neuronal network growth have been tested. The result of this PhD research is a fully new research platform for performing research on the brain, diseases and effects of medication.

Schurink (1982) has conducted his research within the group Meso Scale Chemical Systems, of Prof Han Gardeniers. The group is part of the MESA+ Institute for Nanotechnology of the University of Twente. Schurink’s thesis is titled ‘Microfabrication and microfluidics for 3D brain-on-chip’ …

I have written about one other piece about a ‘3D’ organ-on-a-chip project in China (my Jan. 29, 2016 posting).