Tag Archives: University of Namur

“Care to swap excitons?” asked one graphene layer to the other layer

Belgian science does not often make an appearance here perhaps due to language issues or the direction that science research has taken in that country or something else. In any event, a Feb. 3, 2014 news item on Nanowerk highlights some graphene research taking place in Belgium (Note: A link has been removed),

Belgian scientists have used a particle physics theory to describe the behaviour of particle-like entities, referred to as excitons, in two layers of graphene, a one-carbon-atom-thick honeycomb crystal. In a paper published in EPJ B (“Exciton swapping in a twisted graphene bilayer as a solid-state realization of a two-brane model”), Michael Sarrazin from the University of Namur, and Fabrice Petit from the Belgian Ceramic Research Centre in Mons, studied the behaviour of excitons in a bilayer of graphene through an analogy with excitons evolving in two abstract parallel worlds, described with equations typically used in high-energy particle physics.

I found the previous description a little more confusing that I’d hoped but do feel that this line present in the Jan. 21, 2014 EPJ B news release (also on EurekAlert but dated Feb. 3, 2014) helped clarify matters,

Equations used to describe parallel worlds in particle physics can help study the behaviour of particles in parallel graphene layers

One of the problems with skimming through material as I often do is that more complex sentences cause confusion and whoever removed the first line from the news item was relying on me (the reader) to carefully read through some 70 to 80 words before revealing that the scientists had created two parallel virtual worlds to test their theory. Once that was understood, this made more sense (from the news release),

The authors used the equations reflecting a theoretical world consisting of a bi-dimensional space sheet—a so-called brane—embedded in a space with three dimensions. Specifically, the authors described the quantum behaviour of excitons in a universe made of two such brane worlds. They then made an analogy with a bilayer of graphene sheets, in which quantum particles live in a separate space-time.

They showed that this approach is adapted to study theoretically and experimentally how excitons behave when they are confined within the plane of the graphene sheet.

Sarrazin and his colleague have also theoretically shown the existence of a swapping effect of excitons between graphene layers under specific electromagnetic conditions. This swapping effect may occur as a solid-state equivalent of known particle swapping predicted in brane theory.

To verify their predictions, the authors suggest the design for an experimental device relying on a magnetically tunable optical filter. It uses magnets whose magnetic fields can be controlled with a separate external magnetic field. The excitons are first produced by shining an incident light onto the first graphene layer. The device then works by recording photons in front of the second graphene layer, which provide a clue of the decay of the exciton after it has swapped onto the second layer from the first.

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

M. Sarrazin and F. Petit (2014), Exciton swapping in a twisted graphene bilayer as a solid-state realization of a two-brane model, European Physical Journal B, DOI 10.1140/epjb/e2013-40492-5

Clicking on the link will lead you directly to this open access paper.

Journal of Responsible Innovation is launched and there’s a nanotechnology connection

According to an Oct. 30, 2013 news release from the Taylor & Francis Group, there’s a new journal being launched, which is good news for anyone looking to get their research or creative work (which retains scholarly integrity) published in a journal focused on emerging technologies and innovation,

Journal of Responsible Innovation will focus on intersections of ethics, societal outcomes, and new technologies: New to Routledge for 2014 [Note: Routledge is a Taylor & Francis Group brand]

Scholars and practitioners in the emerging interdisciplinary field known as “responsible innovation” now have a new place to publish their work. The Journal of Responsible Innovation (JRI) will offer an opportunity to articulate, strengthen, and critique perspectives about the role of responsibility in the research and development process. JRI will also provide a forum for discussions of ethical, social and governance issues that arise in a society that places a great emphasis on innovation.

Professor David Guston, director of the Center for Nanotechnology in Society at Arizona State University and co-director of the Consortium for Science, Policy and Outcomes, is the journal’s founding editor-in-chief. [emphasis mine] The Journal will publish three issues each year, beginning in early 2014.

“Responsible innovation isn’t necessarily a new concept, but a research community is forming and we’re starting to get real traction in the policy world,” says Guston. “It is our hope that the journal will help solidify what responsible innovation can mean in both academic and industrial laboratories as well as in governments.”

“Taylor & Francis have been working with the scholarly community for over two centuries and over the past 20 years, we have launched more new journals than any other publisher, all offering peer-reviewed, cutting-edge research,” adds Editorial Director Richard Steele. “We are proud to be working with David Guston and colleagues to create a lively forum in which to publish and debate research on responsible technological innovation.”

An emerging and interdisciplinary field

The term “responsible innovation” is often associated with emerging technologies—for example, nanotechnology, synthetic biology, geoengineering, and artificial intelligence—due to their uncertain but potentially revolutionary influence on society. [emphasis mine] Responsible innovation represents an attempt to think through the ethical and social complexities of these technologies before they become mainstream. And due to the broad impacts these technologies may have, responsible innovation often involves people working in a variety of roles in the innovation process.

Bearing this interdisciplinarity in mind, the Journal of Responsible Innovation (JRI) will publish not only traditional journal articles and research reports, but also reviews and perspectives on current political, technical, and cultural events. JRI will publish authors from the social sciences and the natural sciences, from ethics and engineering, and from law, design, business, and other fields. It especially hopes to see collaborations across these fields, as well.

“We want JRI to help organize a research network focused around complex societal questions,” Guston says. “Work in this area has tended to be scattered across many journals and disciplines. We’d like to bring those perspectives together and start sharing our research more effectively.”

Now accepting manuscripts

JRI is now soliciting submissions from scholars and practitioners interested in research questions and public issues related to responsible innovation. [emphasis mine] The journal seeks traditional research articles; perspectives or reviews containing opinion or critique of timely issues; and pedagogical approaches to teaching and learning responsible innovation. More information about the journal and the submission process can be found at www.tandfonline.com/tjri.

About The Center for Nanotechnology in Society at ASU

The Center for Nanotechnology in Society at ASU (CNS-ASU) is the world’s largest center on the societal aspects of nanotechnology. CNS-ASU develops programs that integrate academic and societal concerns in order to better understand how to govern new technologies, from their birth in the laboratory to their entrance into the mainstream.

About Taylor & Francis Group


Taylor & Francis Group partners with researchers, scholarly societies, universities and libraries worldwide to bring knowledge to life.  As one of the world’s leading publishers of scholarly journals, books, ebooks and reference works our content spans all areas of Humanities, Social Sciences, Behavioural Sciences, Science, and Technology and Medicine.

From our network of offices in Oxford, New York, Philadelphia, Boca Raton, Boston, Melbourne, Singapore, Beijing, Tokyo, Stockholm, New Delhi and Johannesburg, Taylor & Francis staff provide local expertise and support to our editors, societies and authors and tailored, efficient customer service to our library colleagues.

You can find out more about the Journal of Responsible Innovation here, including information for would-be contributors,

JRI invites three kinds of written contributions: research articles of 6,000 to 10,000 words in length, inclusive of notes and references, that communicate original theoretical or empirical investigations; perspectives of approximately 2,000 words in length that communicate opinions, summaries, or reviews of timely issues, publications, cultural or social events, or other activities; and pedagogy, communicating in appropriate length experience in or studies of teaching, training, and learning related to responsible innovation in formal (e.g., classroom) and informal (e.g., museum) environments.

JRI is open to alternative styles or genres of writing beyond the traditional research paper or report, including creative or narrative nonfiction, dialogue, and first-person accounts, provided that scholarly completeness and integrity are retained.[emphases mine] As the journal’s online environment evolves, JRI intends to invite other kinds of contributions that could include photo-essays, videos, etc. [emphasis mine]

I like to check out the editorial board for these things (from the JRI’s Editorial board webpage; Note: Links have been removed),,


David. H. Guston , Arizona State University, USA

Associate Editors

Erik Fisher , Arizona State University, USA
Armin Grunwald , ITAS , Karlsruhe Institute of Technology, Germany
Richard Owen , University of Exeter, UK
Tsjalling Swierstra , Maastricht University, the Netherlands
Simone van der Burg, University of Twente, the Netherlands

Editorial Board

Wiebe Bijker , University of Maastricht, the Netherlands
Francesca Cavallaro, Fundacion Tecnalia Research & Innovation, Spain
Heather Douglas , University of Waterloo, Canada
Weiwen Duan , Chinese Academy of Social Sciences, China
Ulrike Felt, University of Vienna, Austria
Philippe Goujon , University of Namur, Belgium
Jonathan Hankins , Bassetti Foundation, Italy
Aharon Hauptman , University of Tel Aviv, Israel
Rachelle Hollander , National Academy of Engineering, USA
Maja Horst , University of Copenhagen, Denmark
Noela Invernizzi , Federal University of Parana, Brazil
Julian Kinderlerer , University of Cape Town, South Africa
Ralf Lindner , Frauenhofer Institut, Germany
Philip Macnaghten , Durham University, UK
Andrew Maynard , University of Michigan, USA
Carl Mitcham , Colorado School of Mines, USA
Sachin Chaturvedi , Research and Information System for Developing Countries, India
René von Schomberg, European Commission, Belgium
Doris Schroeder , University of Central Lancashire, UK
Kevin Urama , African Technology Policy Studies Network, Kenya
Frank Vanclay , University of Groningen, the Netherlands
Jeroen van den Hoven, Technical University, Delft, the Netherlands
Fern Wickson , Genok Center for Biosafety, Norway
Go Yoshizawa , Osaka University, Japan

Good luck to the publishers and to those of you who will be making submissions. As for anyone who may be as curious as I was about the connection between Routledge and Francis & Taylor, go here and scroll down about 75% of the page (briefly, Routledge is a brand).

Fireflies and their jagged scales lead to brighter LEDs (light emitting diodes)

According to the Jan. 8, 2013 news item on ScienceDaily, scientists have used an observation about fireflies to make brighter LEDs (light emitting diodes),

The nighttime twinkling of fireflies has inspired scientists to modify a light-emitting diode (LED) so it is more than one and a half times as efficient as the original.

Researchers from Belgium, France, and Canada studied the internal structure of firefly lanterns, the organs on the bioluminescent insects’ abdomens that flash to attract mates. The scientists identified an unexpected pattern of jagged scales that enhanced the lanterns’ glow, and applied that knowledge to LED design to create an LED overlayer that mimicked the natural structure. The overlayer, which increased LED light extraction by up to 55 percent, could be easily tailored to existing diode designs to help humans light up the night while using less energy.

The Optical Society of America’s Jan. 8, 2013 news release, which originated the news item, describes how the scientists came to make their observations,

“The most important aspect of this work is that it shows how much we can learn by carefully observing nature,” says Annick Bay, a Ph.D. student at the University of Namur in Belgium who studies natural photonic structures, including beetle scales and butterfly wings.  When her advisor, Jean Pol Vigneron, visited Central America to conduct field work on the Panamanian tortoise beetle (Charidotella egregia), he also noticed clouds of twinkling fireflies and brought some specimens back to the lab to examine in more detail.

Fireflies create light through a chemical reaction that takes place in specialized cells called photocytes. The light is emitted through a part of the insect’s exoskeleton called the cuticle.  Light travels through the cuticle more slowly than it travels through air, and the mismatch means a proportion of the light is reflected back into the lantern, dimming the glow. The unique surface geometry of some fireflies’ cuticles, however, can help minimize internal reflections, meaning more light escapes to reach the eyes of potential firefly suitors.

In Optics Express papers, Bay, Vigneron, and colleagues first describe the intricate structures they saw when they examined firefly lanterns and then present how the same features could enhance LED design. Using scanning electron microscopes, the researchers identified structures such as nanoscale ribs and larger, misfit scales, on the fireflies’ cuticles. When the researchers used computer simulations to model how the structures affected light transmission they found that the sharp edges of the jagged, misfit scales let out the most light. The finding was confirmed experimentally when the researchers observed the edges glowing the brightest when the cuticle was illuminated from below.

“We refer to the edge structures as having a factory roof shape,” says Bay.  “The tips of the scales protrude and have a tilted slope, like a factory roof.” The protrusions repeat approximately every 10 micrometers, with a height of approximately 3 micrometers. “In the beginning we thought smaller nanoscale structures would be most important, but surprisingly in the end we found the structure that was the most effective in improving light extraction was this big-scale structure,” says Bay.

Here’s how the scientists applied their observations to LEDs (from the news release),

Human-made light-emitting devices like LEDs face the same internal reflection problems as fireflies’ lanterns and Bay and her colleagues thought a factory roof-shaped coating could make LEDs brighter. In the second Optics Express paper published today, which is included in the Energy Express  section of the journal, the researchers describe the method they used to create a jagged overlayer on top of a standard gallium nitride LED. Nicolas André, a postdoctoral researcher at the University of Sherbrooke in Canada, deposited a layer of light-sensitive material on top of the LEDs and then exposed sections with a laser to create the triangular factory-roof profile. Since the LEDs were made from a material that slowed light even more than the fireflies’ cuticle, the scientists adjusted the dimensions of the protrusions to a height and width of 5 micrometers to maximize the light extraction.

“What’s nice about our technique is that it’s an easy process and we don’t have to create new LEDs,” says Bay.  “With a few more steps we can coat and laser pattern an existing LED.”

Other research groups have studied the photonic structures in firefly lanterns as well, and have even mimicked some of the structures to enhance light extraction in LEDs, but their work focused on nanoscale features. The Belgium-led team is the first to identify micrometer-scale photonic features, which are larger than the wavelength of visible light, but which surprisingly improved light extraction better than the smaller nanoscale features. The factory roof coating that the researchers tested increased light extraction by more than 50 percent, a significantly higher percentage than other biomimicry approaches have achieved to date. The researchers speculate that, with achievable modifications to current manufacturing techniques, it should be possible to apply these novel design enhancements to current LED production within the next few years.

For those who care to investigate further,

Both articles (HTML version) are open access; PDF versions were not checked.