News Article | March 4, 2016
A new one atom-thick flat material that could upstage the wonder material graphene and advance digital technology has been discovered by a physicist at the University of Kentucky working in collaboration with scientists from Daimler in Germany and the Institute for Electronic Structure and Laser (IESL) in Greece.
Tsalikis D.G.,University of Patras |
Mavrantzas V.G.,University of Patras |
Mavrantzas V.G.,ETH Zurich |
Vlassopoulos D.,Institute for Electronic Structure and Laser |
Vlassopoulos D.,University of Crete
ACS Macro Letters | Year: 2016
Atomistic configurations of pure, precisely monodisperse ring poly(ethylene oxide) (PEO) melts accumulated in the course of very long molecular dynamics (MD) simulations at T = 413 K and P = 1 atm have been subjected to a detailed geometric analysis involving three steps (reduction to ensembles of coarse-grained paths, triangulation of the resulting three-dimensional polygons, and analysis of interpenetrations using vector calculus) in order to locate ring-ring threading events and quantify their strength and survival times. A variety of threading situations have been identified corresponding to single and multiple penetrations. The percentage of inter-ring threadings that correspond to full penetrations has also been quantified. By repeating the analysis for several PEO melts, the dependence of the degree of inter-ring threading on molecular weight (MW) has been obtained. Simulations with MWs up to 10 times the reported entanglement molecular weight (Me) of linear PEO have revealed several multiple threading events in all systems, with their relative number increasing with increasing MW. Our analysis indicates the existence of strong ring-ring topological interactions, which can last up to several times the corresponding average orientational ring polymer relaxation time. We show that these ring-ring interactions, together with the additional ring-linear threadings due to the remaining linear impurities, can explain the appearance of slow relaxation modes observed experimentally in entangled rings. © 2016 American Chemical Society.
News Article | April 2, 2015
Doudna’s Caribou Bio Raises $11M To Expand Uses For Gene Editing Tech Caribou Biosciences, one of the biotech startups working to advance a much-watched new technology for precise gene editing, announced today it has raised an $11 million Series A round from venture capital firms and Swiss drug giant Novartis. The money will help Berkeley, CA-based Caribou speed up its efforts to adapt a versatile genome editing technique co-discovered by one of its founders, UC Berkeley professor Jennifer Doudna, for a range of uses, including drug research and development, and industrial technology. Doudna (pictured above) and her collaborator, Emmanuelle Charpentier of the Helmholtz Center for Infection Research in Braunschweig, Germany, and Umeå University in Sweden, figured out how to transform a bacterial defense against viral infection into a tool to edit out abnormal sections of genes, such as those that cause hereditary diseases. Caribou’s gene editing platform is based on two elements of that bacterial molecular machinery: a guiding mechanism called CRISPR (clustered, regularly interspaced palindromic repeats), and an enzyme called Cas9, or CRISPR-associated protein 9, molecular scissors that cut a segment of DNA. Caribou was founded in 2011 to commercialize the work from Doudna’s lab. Doudna was one of the investors in Caribou’s Series A round. The other investors include Fidelity Biosciences, Novartis, Mission Bay Capital, 5 Prime Ventures, and an undisclosed strategic partner. Caribou recently formed a collaboration with Novartis Institutes for Biomedical Research in Cambridge, MA, to use the startup’s gene editing technology to screen potential new drug targets. In 2014, Caribou co-founded another gene editing startup, Cambridge-based Intellia Therapeutics, and assigned it exclusive rights to develop and commercialize human gene cell therapies using its CRISPR-Cas9 gene editing platform. In November, Intellia raised a $15 million Series A round from Atlas Venture and the research arm of Novartis. (NYSE: NVS). A few months later, Intellia and Novartis teamed up again, this time on an effort to use Intellia’s gene editing tools with a promising cancer immunotherapy technology called chimeric antigen receptor T-cells, or CAR-T. Caribou still has rights to use its gene editing system for therapeutic research and development, and to develop anti-microbial products in human health as well as industrial products for agriculture and other fields. Caribou and Intellia aren’t alone in the pursuit of commercial breakthroughs based on the new gene editing techniques. Doudna was a scientific co-founder of Cambridge-based Editas Medicine, another startup in the race to develop drugs with CRISPR-Cas9 technology, backed by Polaris Partners, Third Rock Ventures, and Flagship Ventures. Rights to Doudna’s foundational discoveries, however, rest with Caribou, and Doudna is no longer involved with Editas. Doudna’s collaborator Charpentier assigned her portion of the CRISPR-Cas9 rights to CRISPR Therapeutics of Basel, Switzerland. Other scientists, like Feng Zhang of the Broad Institute of MIT and Harvard (an Editas co-founder), have laid claim to intellectual property rights related to the promising novel gene editing technique, which may become entangled in a legal snarl at the U.S. Patent Office.
Rissanou A.N.,University of Crete |
Rissanou A.N.,Institute of Applied and Computational Mathematics FORTH |
Georgilis E.,University of Crete |
Kasotakis E.,University of Crete |
And 4 more authors.
Journal of Physical Chemistry B | Year: 2013
Diphenylalanine (FF) is a very common peptide with many potential applications, both biological and technological, due to a large number of different nanostructures which it attains. The current work concerns a detailed study of the self-assembled structures of FF in two different solvents, an aqueous (H2O) and an organic (CH3OH) through simulations and experiments. Detailed atomistic molecular dynamics (MD) simulations of FF in both solvents have been performed, using an explicit solvent model. The self-assembling propensity of FF in water is obvious while in methanol a very weak self-assembling propensity is observed. We studied and compared structural properties of FF in the two different solvents and a comparison with a system of dialanine (AA) in the corresponding solvents was also performed. In addition, temperature-dependence studies were carried out. Finally, the simulation predictions were compared to new experimental data, which were produced in the framework of the present work. A very good qualitative agreement between simulation and experimental observations was found. © 2013 American Chemical Society.
A new one atom-thick material could upstage the wonder material graphene and advance computing technology, say the scientists who discovered it. Reported in Physical Review B, the new two-dimensional (2D) material is made up of silicon, boron and nitrogen, which are all light, inexpensive and abundant elements, and is extremely stable, a property many other graphene alternatives lack. "We used simulations to see if the bonds would break or disintegrate – it didn't happen," said Madhu Menon, a physicist in the Center for Computational Sciences at the University of Kentucky, who helped discover the material. "We heated the material up to 1000°C and it still didn't break." Menon discovered that material in collaboration with scientists from Daimler in Germany and the Institute for Electronic Structure and Laser (IESL) in Greece. Using state-of-the-art theoretical computations, Menon and his collaborators demonstrated that silicon, boron and nitrogen can be combined to produce a one atom-thick material with properties that can be fine-tuned for applications beyond the abilities of graphene. The bulk of these theoretical computations were performed on computers at the Center for Computational Sciences. While graphene is touted as being the world's strongest material with many unique properties, it has one downside: it isn't a semiconductor. The search for 2D materials with semiconducting properties has led researchers to a new class of three-layer materials called transition-metal dichalcogenides (TMDCs). Most TMDCs are semiconductors and can be made into digital processors that are more efficient than those made with silicon. However, TMDCs are much bulkier than graphene and made of substances that are not necessarily abundant or inexpensive. Searching for new 2D materials made from substances that are light, abundant, inexpensive and semiconducting, Menon and his colleagues studied different combinations of elements from the first and second row of the Periodic Table. Although there are many ways to combine silicon, boron and nitrogen to form planar structures, the team’s computations revealed that only one specific arrangement of these elements resulted in a stable structure. This arrangement follows the same hexagonal pattern as graphene, but that is where the similarity ends. The three elements forming the new material all have different sizes; the bonds connecting the atoms are also different. As a result, the sides of the hexagons formed by these atoms are unequal, unlike in graphene. The new material is metallic, but can easily be made semiconducting by attaching other elements on top of the silicon atoms. The presence of silicon also offers the exciting possibility of a seamless integration with current silicon-based computing technology, allowing the industry to slowly move away from silicon instead of replacing it entirely. What is more, attaching other elements to the 2D material not only creates the electronic band gap that confers semiconducting properties, but can also selectively change the band gap values – a key advantage over graphene for solar energy conversion and electronics applications. "We know that silicon-based technology is reaching its limit because we are putting more and more components together and making electronic processors more and more compact," Menon said. "But we know that this cannot go on indefinitely; we need smarter materials." Other graphene-like materials have been proposed but lack the strength of the material discovered by Menon and his team. Silicene, for example, a 2D version of silicon, does not have a flat surface and eventually forms a 3D surface. Other materials are highly unstable, only lasting for a few hours at most. Menon and his team are now working in close collaboration with a team led by Mahendra Sunkara in the Conn Center for Renewable Energy Research at the University of Louisville to create this material in the lab. The Conn Center team has already collaborated with Menon on a number of new materials systems, testing his theory with experiments for several new solar materials. "We are very anxious for this to be made in the lab," Menon said. "The ultimate test of any theory is experimental verification, so the sooner the better!" Some of the proposed properties of this new 2D material, such as the ability to form various types of nanotubes, are discussed in the paper but Menon expects more to emerge with further study. "This discovery opens a new chapter in material science by offering new opportunities for researchers to explore functional flexibility and new properties for new applications," he said. "We can expect some surprises." This story is adapted from material from the University of Kentucky, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.