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15.07.2016
 
A drone that gets around obstacles like an insect



15.07.16 - Physics student Darius Merk has used an insect-inspired algorithm to develop a drone that can navigate around obstacles. His research could prove particularly useful in a natural disaster.

How do you send a drone on a reconnaissance mission in a hard-to-reach area without it getting stuck in the rubble? The drone could of course be remotely controlled, but you could lose contact with the device if it went behind a wall. EPFL physics student and robot enthusiast Darius Merk has found another solution – one that is inspired by insects’ vision and that he developed in EPFL’s Laboratory of Intelligent Systems for his Master’s project.

The drone is completely autonomous and can detect obstacles in order to avoid a collision. Unlike human sight, the drone does not use stereoscopic vision to determine depth and distance. “Using cameras to simulate the human eye requires a lot of computing power,” says Merk. “For this, the drone would need to have a small on-board computer, which would make it difficult to miniaturize.”



So Merk came up with a drone that can see like insects with their faceted eyes. “Insects find their way by using their optical flow to assess how an image moves, with a distant object moving more slowly than a closer one,” explains Merk. A drone that sees like an insect requires only two 15g cameras – one at the front and one at the back – to get a 360-degree view of the terrain. The device uses very little computing power, so it could potentially be reduced to around 10cm in size.

The technology would be extremely handy in a natural disaster, as it could be used to help rescuers and to scout the terrain. The drone is light, autonomous and capable of getting round obstacles – it will be able to follow a programmed course in order to bring back videos and images of areas that are hard to reach.

The Laboratory of Intelligent Systems (LIS) website: http://lis.epfl.ch/


EPFL news
 
14.07.2016
 
Four steps for validating stem cells



14.07.16 - Scientists at EPFL and in the US have developed a robust method for characterizing human embryonic stem cells and their potential for medical applications.

The key to utilizing stem cells for regenerative medicine and tissue engineering lies in a property of theirs called pluripotency. This refers to the cells’ ability to differentiate into different types of cells. This means that we need to be able to reliably obtain, culture and maintain fully pluripotent stem cells. It has been difficult to generate human embryonic stem cells at the earliest stage of pluripotency, in what is named “ground” or “naïve” state, whereas this is readily done with mouse cells. The labs of Rudolf Jaenisch at MIT, Joe Ecker at the Salk Institute, and Didier Trono at EPFL have now developed a four-step process for determining accurate signatures of human embryonic stem cells and relating them to precise developmental stages. The work, a first for human embryonic stem cells, is published in Cell Stem Cell.

The first criterion involves a rigorous assay to see how much the naïve stem cells contribute to a mouse-human embryo. If the resulting organism (a so-called “chimera”) contains any human DNA, it signals successful engraftment of the stem cells.

The second criterion looks at the expression profile of 4.5 million RNA biomarkers called “transposable elements”, which are genetic units that can move around the genome – in fact, they make up half of the human genome. Because they can cause dangerous mutations by inserting themselves inside genes, transposable elements are actually suppressed in the early developmental stages of the embryo. However, transposable elements also regulate gene expression, and are essential in maintaining the organism’s homeostasis. The researchers demonstrated that profiling which transposable elements are active in the stem cells is an extremely sensitive and highly reproducible indicator of their pluripotency stage.

The third criterion focuses on DNA methylation state of the cells, which is lower in the naïve compared to the primed state. Finally, the fourth criterion is the epigenetic state of the X chromosome in female naïve cells, which resembles that found in the human pre-implantation embryo.

The study provides a roadmap for broadly evaluating stage, state and quality of human pluripotent cells, and can overcome current limitations with using such cells in research and clinical applications. Based on this work, the researchers have developed a startup project named Cellphmed. The company’s mission is to streamline the experimental work of the second criterion, which involves the transcriptional profiling of transposable elements to generate human cell markers for broad research and clinical applications.

This work involved a collaboration between EPFL’s School of Life Sciences, MIT’s Whitehead Institute for Biomedical Research (Cambridge, MA), and the Salk Institute for Biological Studies (La Jolla, CA). It was funded by the Simons Foundation, the National Institutes of Health (NIH), the Swiss National Science Foundation (SNSF), the European Research Council (ERC), the Howard Hughes Medical Institute, the Gordon and Betty Moore Foundation, the Mary K. Chapman Foundation, the Wellcome Trust, a Foundation Bettencourt Award, the Association pour la Recherche sur le Cancer (ARC), and the Fonds de la Recherche en Santé du Québec.

Reference

Theunissen TW, Friedli M, He Y, Planet E, Oneil R, Markoulaki S, Pontis J, Wang H, Iouranova A, Imbeault M, Duc J, Cohen MA, Wert KJ, Castanon RG, Zhang Z, Huang Y, Nery JR, Drotar J, Lungjangwa T, Trono D, Ecker JR, Jaenisch R. Molecular Criteria for Defining the Naive Human Pluripotent State. Cell Stem Cell 14 July 2016. DOI: 10.1016/j.stem.2016.06.011


EPFL news
 
14.07.2016
 
International Aerospace R&D Project Exhibition Event 2016 - AEROEX

International Aerospace R&D Project Exhibition Event 2016 - AEROEX

13-15 October 2016, in Kayseri, TURKEY

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14.07.2016
 
Electricity generated with water, salt ? and a 3 atoms thick membrane



14.07.16 - EPFL researchers have developed a system that generates electricity from osmosis with unparalleled efficiency. Their work, featured in Nature, uses seawater, fresh water, and a new type of membrane just three atoms thick.

Proponents of clean energy will soon have a new source to add to their existing array of solar, wind, and hydropower: osmotic power. Or more specifically, energy generated by a natural phenomenon occurring when fresh water comes into contact with seawater through a membrane.

Researchers at EPFL’s Laboratory of Nanoscale Biology have developed an osmotic power generation system that delivers never-before-seen yields. Their innovation lies in a three atoms thick membrane used to separate the two fluids. The results of their research have been published in Nature.

The concept is fairly simple. A semipermeable membrane separates two fluids with different salt concentrations. Salt ions travel through the membrane until the salt concentrations in the two fluids reach equilibrium. That phenomenon is precisely osmosis.

If the system is used with seawater and fresh water, salt ions in the seawater pass through the membrane into the fresh water until both fluids have the same salt concentration. And since an ion is simply an atom with an electrical charge, the movement of the salt ions can be harnessed to generate electricity.

A 3 atoms thick, selective membrane that does the job
EPFL’s system consists of two liquid-filled compartments separated by a thin membrane made of molybdenum disulfide. The membrane has a tiny hole, or nanopore, through which seawater ions pass into the fresh water until the two fluids’ salt concentrations are equal. As the ions pass through the nanopore, their electrons are transferred to an electrode – which is what is used to generate an electric current.

Thanks to its properties the membrane allows positively-charged ions to pass through, while pushing away most of the negatively-charged ones. That creates voltage between the two liquids as one builds up a positive charge and the other a negative charge. This voltage is what causes the current generated by the transfer of ions to flow.

“We had to first fabricate and then investigate the optimal size of the nanopore. If it’s too big, negative ions can pass through and the resulting voltage would be too low. If it’s too small, not enough ions can pass through and the current would be too weak,” said Jiandong Feng, lead author of the research.

What sets EPFL’s system apart is its membrane. In these types of systems, the current increases with a thinner membrane. And EPFL’s membrane is just a few atoms thick. The material it is made of – molybdenum disulfide – is ideal for generating an osmotic current. “This is the first time a two-dimensional material has been used for this type of application,” said Aleksandra Radenovic, head of the laboratory of Nanoscale Biology

Powering 50’000 energy-saving light bulbs with 1m2 membrane
The potential of the new system is huge. According to their calculations, a 1m2 membrane with 30% of its surface covered by nanopores should be able to produce 1MW of electricity – or enough to power 50,000 standard energy-saving light bulbs. And since molybdenum disulfide (MoS2) is easily found in nature or can be grown by chemical vapor deposition, the

system could feasibly be ramped up for large-scale power generation. The major challenge in scaling-up this process is finding out how to make relatively uniform pores.

Until now, researchers have worked on a membrane with a single nanopore, in order to understand precisely what was going on. '' From an engineering perspective, single nanopore system is ideal to further our fundamental understanding of 8=-based processes and provide useful information for industry-level commercialization'', said Jiandong Feng.

The researchers were able to run a nanotransistor from the current generated by a single nanopore and thus demonstrated a self-powered nanosystem. Low-power single-layer MoS2 transistors were fabricated in collaboration with Andras Kis’ team at at EPFL, while molecular dynamics simulations were performed by collaborators at University of Illinois at Urbana–Champaign

Harnessing the potential of estuaries
EPFL’s research is part of a growing trend. For the past several years, scientists around the world have been developing systems that leverage osmotic power to create electricity. Pilot projects have sprung up in places such as Norway, the Netherlands, Japan, and the United States to generate energy at estuaries, where rivers flow into the sea. For now, the membranes used in most systems are organic and fragile, and deliver low yields. Some systems use the movement of water, rather than ions, to power turbines that in turn produce electricity.

Once the systems become more robust, osmotic power could play a major role in the generation of renewable energy. While solar panels require adequate sunlight and wind turbines adequate wind, osmotic energy can be produced just about any time of day or night – provided there’s an estuary nearby.

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Contacts
Lionel Pousaz, EPFL Press Service lionel.pousaz@epfl.ch or +41 79 559 71 61

Aleksandra Radenovic, EPFL researcher aleksandra.radenovic@epfl.ch or +41 79 535 00 15

Press material
Press kit (documents, images): bit.ly/OsmosisNature2016

This research is being carried out jointly by the Laboratory of Nanoscale Biology and the Laboratory of Nanoscale Electronics and Structures; the simulation work is done in a collaboration with the Narayana Aluru group of University of Illinois at Urbana–Champaign. The work was funded by the SNSF Consolidator Grant Bionic.


EPFL news
 
13.07.2016
 
HEALCON final conference

The EU-funded HEALCON project will be hosting its final conference in Delft, the Netherlands, from 28 to 29 November 2016.

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