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  • richardmitnick 4:35 pm on March 17, 2017 Permalink | Reply
    Tags: , Chemistry, , , Scientists make microscopes from droplets, Tunable microlenses   

    From MIT: “Scientists make microscopes from droplets” 

    MIT News

    MIT Widget

    MIT News

    March 10, 2017
    Jennifer Chu

    1
    Researchers at MIT have devised tiny “microlenses” from complex liquid droplets, such as these pictured here, that are comparable in size to the width of a human hair. Courtesy of the researchers

    With chemistry and light, researchers can tune the focus of tiny beads of liquid.

    Liquid droplets are natural magnifiers. Look inside a single drop of water, and you are likely to see a reflection of the world around you, close up and distended as you’d see in a crystal ball.

    Researchers at MIT have now devised tiny “microlenses” from complex liquid droplets comparable in size to the width of a human hair. They report the advance this week in the journal Nature Communications.

    Each droplet consists of an emulsion, or combination of two liquids, one encapsulated in the other, similar to a bead of oil within a drop of water. Even in their simple form, these droplets can magnify and produce images of surrounding objects. But now the researchers can also reconfigure the properties of each droplet to adjust the way they filter and scatter light, similar to adjusting the focus on a microscope.

    The scientists used a combination of chemistry and light to precisely shape the curvature of the interface between the internal bead and the surrounding droplet. This interface acts as a kind of internal lens, comparable to the compounded lens elements in microscopes.

    “We have shown fluids are very versatile optically,” says Mathias Kolle, the Brit and Alex d’Arbeloff Career Development Assistant Professor in MIT’s Department of Mechanical Engineering. “We can create complex geometries that form lenses, and these lenses can be tuned optically. When you have a tunable microlens, you can dream up all sorts of applications.”

    For instance, Kolle says, tunable microlenses might be used as liquid pixels in a three-dimensional display, directing light to precisely determined angles and projecting images that change depending on the angle from which they are observed. He also envisions pocket-sized microscopes that could take a sample of blood and pass it over an array of tiny droplets. The droplets would capture images from varying perspectives that could be used to recover a three-dimensional image of individual blood cells.

    “We hope that we can use the imaging capacity of lenses on the microscale combined with the dynamically adjustable optical characteristics of complex fluid-based microlenses to do imaging in a way people have not done yet,” Kolle says.

    Kolle’s MIT co-authors are graduate student and lead author Sara Nagelberg, former postdoc Lauren Zarzar, junior Natalie Nicolas, former postdoc Julia Kalow, research affiliate Vishnu Sresht, professor of chemical engineering Daniel Blankschtein, professor of mechanical engineering George Barbastathis, and John D. MacArthur Professor of Chemistry Timothy Swager. Moritz Kreysing and Kaushikaram Subramanian of the Max Planck Institute of Molecular Cell Biology and Genetics are also co-authors.

    Shaping a curve

    The group’s work builds on research by Swager’s team, which in 2015 reported a new way to make and reconfigure complex emulsions. In particular, the team developed a simple technique to make and control the size and configuration of double emulsions, such as water that was suspended in oil, then suspended again in water. Kolle and his colleagues used the same techniques to make their liquid lenses.

    They first chose two transparent fluids, one with a higher refractive index (a property that relates to the speed at which light travels through a medium), and the other with a lower refractive index. The contrast between the two refractive indices can contribute to a droplet’s focusing power. The researchers poured the fluids into a vial, heated them to a temperature at which the fluids would mix, then added a water-surfactant solution. When the liquids were mixed rapidly, tiny emulsion droplets formed. As the mixture cooled, the fluids in each of the droplets separated, resulting in droplets within droplets.

    To manipulate the droplets’ optical properties, the researchers added certain concentrations and ratios of various surfactants — chemical compounds that lower the interfacial tension between two liquids. In this case, one of the surfactants the team chose was a light-sensitive molecule. When exposed to ultraviolet light this molecule changes its shape, which modifies the tension at the droplet-water interfaces and the droplet’s focusing power. This effect can be reversed by exposure to blue light.

    “We can change focal length, for example, and we can decide where an image is picked up from, or where a laser beam focuses to,” Kolle says. “In terms of light guiding, propagation, and tailoring of light flow, it’s really a good tool.”

    Optics on the horizon

    Kolle and his colleagues tested the properties of the microlenses through a number of experiments, including one in which they poured droplets into a shallow plate, placed under a stencil, or “photomask,” with a cutout of a smiley face. When they turned on an overhead UV lamp, the light filtered through the holes in the photomask, activating the surfactants in the droplets underneath. Those droplets, in turn, switched from their original, flat interface, to a more curved one, which strongly scattered light, thereby generating a dark pattern in the plate that resembled the photomask’s smiley face.

    The researchers also describe their idea for how the microlenses might be used as pocket-sized microscopes. They propose forming a microfluidic device with a layer of microlenses, each of which could capture an image of a tiny object flowing past, such as a blood cell. Each image would be captured from a different perspective, ultimately allowing recovery of information about the object’s three-dimensional shape.

    “The whole system could be the size of your phone or wallet,” Kolle says. “If you put some electronics around it, you have a microscope where you can flow blood cells or other cells through and visualize them in 3-D.”

    He also envisions screens, layered with microlenses, that are designed to refract light into specific directions.

    “Can we project information to one part of a crowd and different information to another part of crowd in a stadium?” Kolle says. “These kinds of optics are challenging, but possible.”

    This research was supported, in part, by the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, and the Max Planck Society.

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  • richardmitnick 9:10 am on March 13, 2017 Permalink | Reply
    Tags: , Chemistry, , , Stanford engineers use soup additive to create a stretchable plastic electrode   

    From Stanford: “So long stiffness: Stanford engineers use soup additive to create a stretchable plastic electrode” 

    Stanford University Name
    Stanford University

    March 10, 2017
    Shara Tonn

    .
    Courtesy Bao Research Group
    Access mp4 video here .
    A robotic test instrument stretches over a curved surface a nearly transparent, flexible electrode based on a special plastic developed in the lab of Stanford chemical engineer. Zhenan Bao.

    Chemical engineer Zhenan Bao is trying to change that. For more than a decade, her lab has been working to make electronics soft and flexible so that they feel and operate almost like a second skin. Along the way, the team has started to focus on making brittle plastics that can conduct electricity more elastic.

    Now in Science Advances, Bao’s team describes how they took one such brittle plastic and modified it chemically to make it as bendable as a rubber band, while slightly enhancing its electrical conductivity. The result is a soft, flexible electrode that is compatible with our supple and sensitive nerves.

    “This flexible electrode opens up many new, exciting possibilities down the road for brain interfaces and other implantable electronics,” said Bao, a professor of chemical engineering. “Here, we have a new material with uncompromised electrical performance and high stretchability.”

    The material is still a laboratory prototype, but the team hopes to develop it as part of their long-term focus on creating flexible materials that interface with the human body.

    1
    A printed electrode pattern of the new polymer being stretched to several times of its original length (top), and a transparent, highly stretchy “electronic skin” patch forming an intimate interface with the human skin to potentially measure various biomarkers (bottom). (Image credit: Bao Lab)

    Flexible interface

    Electrodes are fundamental to electronics. Conducting electricity, these wires carry back and forth signals that allow different components in a device to work together. In our brains, special thread-like fibers called axons play a similar role, transmitting electric impulses between neurons. Bao’s stretchable plastic is designed to make a more seamless connection between the stiff world of electronics and the flexible organic electrodes in our bodies.

    “One thing about the human brain that a lot of people don’t know is that it changes volume throughout the day,” says postdoctoral research fellow Yue Wang, the first author on the paper. “It swells and deswells.” The current generation of electronic implants can’t stretch and contract with the brain and make it complicated to maintain a good connection.

    “If we have an electrode with a similar softness as the brain, it will form a better interface,” said Wang.

    To create this flexible electrode, the researchers began with a plastic that had two essential qualities: high conductivity and biocompatibility, meaning that it could be safely brought into contact with the human body. But this plastic had a shortcoming: It was very brittle. Stretching it even 5 percent would break it.

    Tightly wound and brittle

    As Bao and her team sought to preserve conductivity while adding flexibility, they worked with scientists at the SLAC National Accelerator Laboratory to use a special type of X-ray to study this material at the molecular level. All plastics are polymers; that is, chains of molecules strung together like beads. The plastic in this experiment was actually made up of two different polymers that were tightly wound together. One was the electrical conductor. The other polymer was essential to the process of making the plastic. When these two polymers combined they created a plastic that was like a string of brittle, sphere-like structures. It was conductive, but not flexible.

    The researchers hypothesized that if they could find the right molecular additive to separate these two tightly wound polymers, they could prevent this crystallization and give the plastic more stretch. But they had to be careful – adding material to a conductor usually weakens its ability to transmit electrical signals.

    After testing more than 20 different molecular additives, they finally found one that did the trick. It was a molecule similar to the sort of additives used to thicken soups in industrial kitchens. This additive transformed the plastic’s chunky and brittle molecular structure into a fishnet pattern with holes in the strands to allow the material to stretch and deform. When they tested their new material’s elasticity, they were delighted to find that it became slightly more conductive when stretched to twice its original length. The plastic remained very conductive even when stretched 800 percent its original length.

    “We thought that if we add insulating material, we would get really poor conductivity, especially when we added so much,” said Bao. But thanks to their precise understanding of how to tune the molecular assembly, the researchers got the best of both worlds: the highest possible conductivity for the plastic while at the same transforming it into a very robust and stretchy substance.

    “By understanding the interaction at the molecular level, we can develop electronics that are soft and stretchy like skin, while remaining conductive,” Wang says.

    Other authors include postdoctoral fellows Chenxin Zhu, Francisco Molina-Lopez, Franziska Lissel and Jia Liu; graduate students Shucheng Chen and Noelle I. Rabiah; Hongping Yan and Michael F. Toney, staff scientists at SLAC National Accelerator Laboratory; Christian Linder, an assistant professor of civil and environmental engineering who is also a member of Stanford Bio-X and of the Stanford Neurosciences Institute; Boris Murmann, a professor of electrical engineering and a member of the Stanford Neurosciences Institute; Lihua Jin, now an assistant professor of mechanical and aerospace engineering at the University of California, Los Angeles; Zheng Chen, now an assistant professor of nano engineering at the University of California, San Diego; and colleagues from the Materials Science Institute of Barcelona, Spain, and Samsung Advanced Institute of Technology.

    This work was funded by Samsung Electronics and the Air Force Office of Science Research.

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  • richardmitnick 10:58 pm on March 3, 2017 Permalink | Reply
    Tags: , , Chemistry, ,   

    From MIT: “MIT researchers create new form of matter” 

    MIT News

    MIT Widget

    MIT Physics

    March 2, 2017
    Julia C. Keller

    1
    The Ketterle group at MIT’s Killian court. Pictured from left to right: Furkan Çağrı Top, Junru Li, Sean Burchesky, Alan O. Jamison, Wolfgang Ketterle, Boris Shteynas, Wujie Huang, and Jeongwon Lee.
    Photo courtesy of the researchers.

    2
    This image shows the equipment used by the Ketterle group to create a supersolid. Photo courtesy of the researchers.

    Supersolid is crystalline and superfluid at the same time.

    MIT physicists have created a new form of matter, a supersolid, which combines the properties of solids with those of superfluids.

    By using lasers to manipulate a superfluid gas known as a Bose-Einstein condensate, the team was able to coax the condensate into a quantum phase of matter that has a rigid structure — like a solid — and can flow without viscosity — a key characteristic of a superfluid. Studies into this apparently contradictory phase of matter could yield deeper insights into superfluids and superconductors, which are important for improvements in technologies such as superconducting magnets and sensors, as well as efficient energy transport. The researchers report their results this week in the journal Nature.

    “It is counterintuitive to have a material which combines superfluidity and solidity,” says team leader Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT. “If your coffee was superfluid and you stirred it, it would continue to spin around forever.”

    Physicists had predicted the possibility of supersolids but had not observed them in the lab. They theorized that solid helium could become superfluid if helium atoms could move around in a solid crystal of helium, effectively becoming a supersolid. However, the experimental proof remained elusive.

    The team used a combination of laser cooling and evaporative cooling methods, originally co-developed by Ketterle, to cool atoms of sodium to nanokelvin temperatures. Atoms of sodium are known as bosons, for their even number of nucleons and electrons. When cooled to near absolute zero, bosons form a superfluid state of dilute gas, called a Bose-Einstein condensate, or BEC.

    Ketterle co-discovered BECs — a discovery for which he was recognized with the 2001 Nobel Prize in physics.

    “The challenge was now to add something to the BEC to make sure it developed a shape or form beyond the shape of the ‘atom trap,’ which is the defining characteristic of a solid,” explains Ketterle.

    Flipping the spin, finding the stripes

    To create the supersolid state, the team manipulated the motion of the atoms of the BEC using laser beams, introducing “spin-orbit coupling.”

    In their ultrahigh-vacuum chamber, the team used an initial set of lasers to convert half of the condensate’s atoms to a different quantum state, or spin, essentially creating a mixture of two Bose-Einstein condensates. Additional laser beams then transferred atoms between the two condensates, called a “spin flip.”

    “These extra lasers gave the ‘spin-flipped’ atoms an extra kick to realize the spin-orbit coupling,” Ketterle says.

    Physicists had predicted that a spin-orbit coupled Bose-Einstein condensate would be a supersolid due to a spontaneous “density modulation.” Like a crystalline solid, the density of a supersolid is no longer constant and instead has a ripple or wave-like pattern called the “stripe phase.”

    “The hardest part was to observe this density modulation,” says Junru Li, an MIT graduate student who worked on the discovery. This observation was accomplished with another laser, the beam of which was diffracted by the density modulation. “The recipe for the supersolid is really simple,” Li adds, “but it was a big challenge to precisely align all the laser beams and to get everything stable to observe the stripe phase.”

    Mapping out what is possible in nature

    Currently, the supersolid only exists at extremely low temperatures under ultrahigh-vacuum conditions. Going forward, the team plans to carry out further experiments on supersolids and spin-orbit coupling, characterizing and understanding the properties of the new form of matter they created.

    “With our cold atoms, we are mapping out what is possible in nature,” explains Ketterle. “Now that we have experimentally proven that the theories predicting supersolids are correct, we hope to inspire further research, possibly with unanticipated results.”

    Several research groups were working on realizing the first supersolid. In the same issue of Nature, a group in Switzerland reported an alternative way of turning a Bose-Einstein condensate into a supersolid with the help of mirrors, which collected laser light scattering by the atoms. “The simultaneous realization by two groups shows how big the interest is in this new form of matter,” says Ketterle.

    Ketterle’s team members include graduate students Junru Li, Boris Shteynas, Furkan Çağrı Top, and Wujie Huang; undergraduate Sean Burchesky; and postdocs Jeongwon Lee and Alan O. Jamison, all of whom are associates at MIT’s Research Laboratory of Electronics.

    This research was funded by the National Science Foundation, the Air Force Office for Scientific Research, and the Army Research Office.

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  • richardmitnick 8:42 am on February 22, 2017 Permalink | Reply
    Tags: , Actinides, , Chemistry, , Unravelling the atomic and nuclear structure of the heaviest elements   

    From phys.org: “Unravelling the atomic and nuclear structure of the heaviest elements” 

    physdotorg
    phys.org

    February 22, 2017
    http://www.kuleuven.be/english/

    1
    The metallic chemical elements known as actinides take their name from the first element in the series: actinium. Actinium is one of the heavy, radioactive elements in Mendeleev’s table that are still largely beyond the frontiers of knowledge. Credit: Shutterstock

    Periodic Table 2016
    Periodic Table 2016

    Little is known about the heaviest, radioactive elements in Mendeleev’s table. But an extremely sensitive technique involving laser light and gas jets makes it possible for the very first time to gain insight into their atomic and nuclear structure. An international team led by scientists from the Institute for Nuclear and Radiation Physics at KU Leuven report these findings in Nature Communications.

    In 2016 scientists added four more elements to Mendeleev’s periodic table [113, 115, 117, and 118]. These heavy elements are not found on Earth and can only be generated using powerful particle accelerators. “The elements are usually generated in minuscule quantities, sometimes just a couple of atoms per year. These atoms are also radioactive, so their decay is quick: sometimes they only exist for a fraction of a second. That is why scientific knowledge of these elements is very limited,” say nuclear physicists Mark Huyse and Piet Van Duppen from the KU Leuven Institute for Nuclear and Radiation Physics.

    The KU Leuven researchers are now hoping to change that through a new use of the laser ionization technique. “We produced actinium (Ac), the name-giving element of the heavy actinides, in a series of experiments using the particle accelerator at Louvain-la-Neuve.

    2
    Testing bench, atom smasher, particle accelerator, Cyclotron, #UCL, Louvain-la-Neuve, #LLN, Journées du patrimoine 2012

    The quickly decaying atoms of this element were captured in a gas chamber filled with argon, sucked into a supersonic jet, and spotlighted with laser beams. By doing so we bring the outer electron in a different orbit. A second laser beam then shoots the electron away. This ionizes the atom, meaning that it becomes positively charged and is now easy to manipulate and detect. The colour of the laser light is like a fingerprint of the atomic structure of the element and the structure of its nucleus.”

    In itself, laser ionization is a well-known technique but its use in a supersonic jet is new and very suitable for the heavy, radioactive elements: “By ionizing the atom we significantly increase the sensitivity of the technique. The production of a few atoms per second is already enough for measurements during the experiments. This technology increases the sensitivity, accuracy, and speed of the laser ionization by at least ten times. This marks an entirely new era for research on the heaviest elements and makes it possible to test and correct the theoretical models in nuclear physics. Our method will be used in the new particle accelerator of GANIL, which is currently under construction in France.”

    3
    A photo taken on October 28, 2016 shows a part of the Spiral 2 particle accelerator at he Large Heavy Ion National Accelerator nuclear physics research center (GANIL – Grand Accelérateur National d’Ions Lourds) in Caen, nortwestern France. / AFP / CHARLY

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 8:07 am on February 21, 2017 Permalink | Reply
    Tags: , , , Chemistry, , , The thread of star birth   

    From ESA: “The thread of star birth” 

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    European Space Agency

    1
    Title Star formation on filaments in RCW106
    Released 20/02/2017 9:30 am
    Copyright ESA/Herschel/PACS, SPIRE/Hi-GAL Project. Acknowledgement: UNIMAP / L. Piazzo, La Sapienza – Università di Roma; E. Schisano / G. Li Causi, IAPS/INAF, Italy
    Description

    ESA/Herschel spacecraft
    “ESA/Herschel spacecraft

    Stars are bursting into life all over this image from ESA’s Herschel space observatory. It depicts the giant molecular cloud RCW106, a massive billow of gas and dust almost 12 000 light-years away in the southern constellation of Norma, the Carpenter’s Square.

    Cosmic dust, a minor but crucial ingredient in the interstellar material that pervades our Milky Way galaxy, shines brightly at infrared wavelengths. By tracing the glow of dust with the infrared eye of Herschel, astronomers can explore stellar nurseries in great detail.

    Sprinkled across the image are dense concentrations of the interstellar mixture of gas and dust where stars are being born. The brightest portions, with a blue hue, are being heated by the powerful light from newborn stars within them, while the redder regions are cooler.

    The delicate shapes visible throughout the image are the result of radiation and mighty winds from the young stars carving bubbles and other cavities in the surrounding interstellar material.

    Out of the various bright, blue regions, the one furthest to the left is known as G333.6-0.2 and is one of the most luminous portions of the infrared sky. It owes its brightness to a stellar cluster, home to at least a dozen young and very bright stars that are heating up the gas and dust around them.

    Elongated and thin structures, or filaments, stand out in the tangle of gas and dust, tracing the densest portions of this star-forming cloud. It is largely along these filaments, dotted with many bright, compact cores, that new stars are taking shape.

    Launched in 2009, Herschel observed the sky at far-infrared and submillimetre wavelengths for almost four years. Scanning the Milky Way with its infrared eye, Herschel has revealed an enormous number of filamentary structures, highlighting their universal presence throughout the Galaxy and their role as preferred locations for stellar birth.

    This three-colour image combines Herschel observations at 70 microns (blue), 160 microns (green) and 250 microns (red), and spans over 1º on the long side; north is up and east to the left. The image was obtained as part of Herschel’s Hi-GAL key-project, which imaged the entire plane of the Milky Way in five different infrared bands. A video panorama compiling all Hi-GAL observations was published in April 2016.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 1:31 pm on February 16, 2017 Permalink | Reply
    Tags: , Chemistry, , , Triangulene   

    From Futurism: “Scientists Have Finally Created a Molecule That Was 70 Years in the Making” 

    futurism-bloc

    Futurism

    2.16.17
    Neil C. Bhavsar

    Creating the Impossible

    Move over graphene, it’s 2017 and we have a new carbon structure to rave about: Triangulene. It’s one atom thick, six carbon hexagons in size, and in the shape of – you guessed it – a triangle.

    1

    Development of the molecule has eluded chemists for a period of nearly seventy years. It was first predicted mathematically in the 1950s by Czech scientist, Eric Clar. He noted that the molecule would be unstable electronically due to two unpaired electrons in the six benzene structure. Since then, the mysterious molecule has ushered generations of scientists in a pursuit for the unstable molecule – all resulting in failure due to the oxidizing properties of two lone electron pairs.

    Now, IBM researchers in Zurich, Switzerland seem to have done the impossible: they created the molecule. While most scientists build molecules from the ground up, Leo Gross and his team decided to take the opposite approach. They worked with a larger precursor model and removed two hydrogens substituents from the molecule to conjure up the apparition molecule that is triangulene.

    On top of this, they were able to successfully image the structure with a scanning probe microscope and note the molecule’s unexpected stability in the presence of copper. Their published work is available at Nature Nanotechnology.

    This new material is already proving to be impressive. The two unpaired electrons of the triangulene molecules were discovered to have aligned spins, granting the molecule magnetic properties. Meaning triangulene has a lot of potential in electronics, specifically by allowing us to encode and process information by manipulating the electron spin – a field known as spintronics.

    The IBM researchers still have a lot to learn about triangulene. Moving forward, other teams will attempt to verify whether the researchers actually created the triangle-shaped molecule or not. Until then, the technique the team developed could be used for making other elusive structures. Although, it still isn’t ideal, as it is a slow and expensive process. Even so, this could push us closer to the age of quantum computers.

    References: ScienceAlert – Latest, Nature

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  • richardmitnick 1:57 pm on February 15, 2017 Permalink | Reply
    Tags: , , , Chemistry, Fixing the Big Bang Theory’s Lithium Problem,   

    From AAS NOVA: “Fixing the Big Bang Theory’s Lithium Problem” 

    AASNOVA

    American Astronomical Society

    15 February 2017
    Susanna Kohler

    Inflationary Universe. NASA/WMAP
    Inflationary Universe. NASA/WMAP
    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey
    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    “The Big Bang theory is the most widely accepted cosmological model of the universe, but it still contains a few puzzles.”

    How did our universe come into being? The Big Bang theory is a widely accepted and highly successful cosmological model of the universe, but it does introduce one puzzle: the “cosmological lithium problem.” Have scientists now found a solution?

    Too Much Lithium

    In the Big Bang theory, the universe expanded rapidly from a very high-density and high-temperature state dominated by radiation. This theory has been validated again and again: the discovery of the cosmic microwave background radiation and observations of the large-scale structure of the universe both beautifully support the Big Bang theory, for instance. But one pesky trouble-spot remains: the abundance of lithium.

    2
    The arrows show the primary reactions involved in Big Bang nucleosynthesis, and their flux ratios, as predicted by the authors’ model, are given on the right. Synthesizing primordial elements is complicated! [Hou et al. 2017]

    According to Big Bang nucleosynthesis theory, primordial nucleosynthesis ran wild during the first half hour of the universe’s existence. This produced most of the universe’s helium and small amounts of other light nuclides, including deuterium and lithium.

    But while predictions match the observed primordial deuterium and helium abundances, Big Bang nucleosynthesis theory overpredicts the abundance of primordial lithium by about a factor of three. This inconsistency is known as the “cosmological lithium problem” — and attempts to resolve it using conventional astrophysics and nuclear physics over the past few decades have not been successful.

    In a recent study led by Suqing Hou (Institute of Modern Physics, Chinese Academy of Sciences), however, a team of scientists has proposed an elegant solution to this problem.

    3

    4
    Time and temperature evolution of the abundances of primordial light elements during the beginning of the universe. The authors’ model (dotted lines) successfully predicts a lower abundance of the beryllium isotope — which eventually decays into lithium — relative to the classical Maxwell-Boltzmann distribution (solid lines), without changing the predicted abundances of deuterium or helium. [Hou et al. 2017]

    Questioning Statistics

    Hou and collaborators questioned a key assumption in Big Bang nucleosynthesis theory: that the nuclei involved in the process are all in thermodynamic equilibrium, and their velocities — which determine the thermonuclear reaction rates — are described by the classical Maxwell-Boltzmann distribution.

    But do nuclei still obey this classical distribution in the extremely complex, fast-expanding Big Bang hot plasma? Hou and collaborators propose that the lithium nuclei don’t, and that they must instead be described by a slightly modified version of the classical distribution, accounted for using what’s known as “non-extensive statistics”.

    The authors show that using the modified velocity distributions described by these statistics, they can successfully predict the observed primordial abundances of deuterium, helium, and lithium simultaneously. If this solution to the cosmological lithium problem is correct, the Big Bang theory is now one step closer to fully describing the formation of our universe.

    Citation

    S. Q. Hou et al 2017 ApJ 834 165. doi:10.3847/1538-4357/834/2/165

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  • richardmitnick 9:17 am on February 10, 2017 Permalink | Reply
    Tags: (ReACT) - redox activated chemical tagging, , Chemistry,   

    From LBNL: Chemicals Hitch a Ride onto New Protein for Better Compounds” 

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    Berkeley Lab

    February 9, 2017
    Sarah Yang
    (510) 486-4575
    scyang@lbl.gov

    Chemists have developed a powerful new method of selectively linking chemicals to proteins, a major advance in the manipulation of biomolecules that could transform the way drugs are developed, proteins are probed, and molecules are tracked and imaged.

    1
    Researchers have developed a new method of protein ligation, the joining of molecules with proteins. The technique, called Redox Activated Chemical Tagging (ReACT), involves the modification of proteins by attaching chemical cargos to the amino acid methionine. ReACT functions as a new type of chemical Swiss army knife that supports a wide variety of fields, spanning fundamental studies of protein function to applications in cancer treatment and drug discovery. (Credit: Shixian Lin/Berkeley Lab)

    The new technique, called redox activated chemical tagging (ReACT), is described in the Feb. 10 issue of the journal Science. Developed at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), it could fundamentally change the process of bioconjugation, the process by which chemicals and tags are attached to biomolecules, particularly proteins.

    “We’ve essentially invented a new type of chemical Swiss army knife for proteins, the first that can be used for the essential and naturally occurring amino acid methionine,” said study principal investigator Christopher Chang. “This ReACT method can be incorporated into a variety of different tools depending on what you need it to do. You can mix-and-match different reagents for a variety of applications.”

    Chang and fellow Berkeley Lab faculty scientist F. Dean Toste led this work as part of the Catalysis Program at Berkeley Lab’s Chemical Sciences Division. Chang is also a Howard Hughes Medical Institute Investigator.

    Hitching a ride onto a new protein

    Toste compared the process of bioconjugation to hitching cargo onto the back of a pickup truck.

    “That cargo can be used for many purposes,” he said. “It can deliver drugs to cancerous cells, or it can be used as a tracking device to monitor the truck’s movements. We can even modify the truck and change it to an ambulance. This change can be done in a number of ways, like rebuilding a truck or putting on a new hitch.”

    Bioconjugation traditionally relies upon the amino acid cysteine, which is highly reactive. Cysteine is often used as an attachment point for tags and chemical groups because it is one of two amino acids that contain sulfur, providing an anchor for acid-base chemistry and making it easy to modify.

    But cysteine is often involved in the actual function of proteins, so “hitching cargo” to it creates instability and disrupts its natural function.

    For this reason, people have been looking for ways to circumvent cysteine, and they naturally turned to methionine, the only other sulfur amino acid available. However, methionine has an extra carbon atom attached to its sulfur, which blocks most hitches. The researchers developed a new hitch using a process called oxidation-reduction chemistry that allows cargo to be attached to the methionine sulfur with this extra carbon still attached.

    The potential of a chemical Swiss army knife

    A key benefit to methionine is that it is a relatively rare amino acid, which allows researchers to selectively target it with fewer side effects and less impact on the biomolecule.

    They put ReACT to the test by synthesizing an antibody-drug conjugate to highlight its applicability to biological therapeutics. They also identified the metabolic enzyme enolase as a potential therapeutic target for cancer, showing that the tool could help home in on new targets for drug discovery.

    In the long term, the researchers say, this new bioconjugation tool could be used in:

    Nanotechnology, where protein conjugation can help make nanomaterials compatible with air and water, reducing toxicity.
    The creation of artificial enzymes that can be recycled, have better stability, and have improved activity and selectivity through chemical protein modification.
    Synthetic biology, where it can be used to selectively make new proteins or augment the function of existing ones.

    “This method could also add to the functionality of living organisms by directly modifying natural proteins to improve their stability and activity without making a genetically modified organism that relies on gene editing,” said Chang. “It could have implications for the sustainable production of fuels, food, or medicines, as well as in bioremediation.”

    Co-lead authors of the study are Shixian Lin and Xiaoyu Yang, postdoctoral researchers at UC Berkeley. Both Chang and Toste are also professors of chemistry at UC Berkeley.

    This work was supported DOE’s Office of Science. The National Institutes of Health also supported some of the pilot protein labeling studies that contributed to this work.

    See the full article here .

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  • richardmitnick 1:34 pm on February 7, 2017 Permalink | Reply
    Tags: , Biomathematics, Chemistry, , New study is an advance toward preventing a ‘post-antibiotic era’,   

    From UCLA: “New study is an advance toward preventing a ‘post-antibiotic era’ “ 

    UCLA bloc

    UCLA

    February 07, 2017
    Stuart Wolpert

    UCLA biologists identify drug combinations that may be highly effective at reducing growth of deadly bacteria

    1
    UCLA’s Elif Tekin, Casey Beppler, Pamela Yeh and Van Savage are gaining insights into why certain groups of three antibiotics interact well together and others don’t.

    A landmark report by the World Health Organization in 2014 observed that antibiotic resistance — long thought to be a health threat of the future — had finally become a serious threat to public health around the world. A top WHO official called for an immediate and aggressive response to prevent what he called a “post-antibiotic era, in which common infections and minor injuries which have been treatable for decades can once again kill.”

    A team of UCLA biologists has been responding to the challenge, exploring possible ways to defeat life-threatening antibiotic-resistant bacteria. In 2016, they reported that combinations of three different antibiotics can often overcome bacteria’s resistance to antibiotics, even when none of the three antibiotics on its own — or even two of the three together — is effective.

    Their latest work, which is published online and appears in the current print edition of the Journal of the Royal Society Interface, extends their understanding of that phenomenon and identifies two combinations of drugs that are unexpectedly successful in reducing the growth of E. coli bacteria.

    A key to the study is an understanding that using two, three or more antibiotics in combination does not necessarily make the drugs more effective in combating bacteria — in fact, in many cases, their effectiveness is actually reduced when drugs are used together — so the combinations must be chosen carefully and systematically. The new paper also provides the first detailed explanation of how the scientists created a mathematical formula that can help predict which combinations of drugs will be most effective.

    The scientists tested every possible combination of a group of six antibiotics, including 20 different combinations of three antibiotics at a time.

    Among the three-drug combinations, the researchers found two that were noticeably more effective than they had expected. Those groupings used treatments from three different classes of antibiotics, so the combinations used a wide range of mechanisms to fight the bacteria. (Five of the three-drug combinations were less effective than they expected, and the other 13 groupings performed as they predicted.)

    2
    Pamela Yeh. Reed Hutchinson/UCLA

    “So many bacteria are now so resistant to antibiotics,” said Pamela Yeh, the study’s senior author and a UCLA assistant professor of ecology and evolutionary biology. “We have a logical, methodical way to identify three-drug combinations to pursue. We think it’s vital to have this framework for identifying the best possible combinations of antibiotics.”

    The researchers have identified cases where the effects of the interactions are larger than the sum of the parts.

    “Doctors may want to super-efficiently kill the bacteria, and that is what these enhanced interactions make possible,” said lead author Casey Beppler, who was an undergraduate in Yeh’s laboratory and is now a graduate student at UC San Francisco.

    For the current study, the scientists evaluated the drug combinations on plates in a lab. Beppler said a next step will be to test the most effective combinations in mice.

    In addition to reporting on how well various combinations of antibiotics worked, the paper also presents a mathematical formula the biologists developed for analyzing how three or more factors interact and of explaining complex, unexpected interactions. The framework would be useful for solving other questions in the sciences and social sciences in which researchers analyze how three or more components might interact — for example, how climate is affected by the interplay among temperature, rainfall, humidity and ocean acidity.

    The biologists are gaining a deep understanding of why certain groups of three antibiotics interact well together, and others don’t, said Van Savage, a co-author of the paper and a UCLA professor of ecology and evolutionary biology and of biomathematics.

    Beppler said more research is needed to determine which combinations are optimal for specific diseases and for specific parts of the body. And the researchers now are using the mathematical formula to test combinations of four antibiotics.

    Co-authors of the new research are Elif Tekin, a UCLA graduate student in Savage’s laboratory; Zhiyuan Mao, Cynthia White, Cassandra McDiarmid and Emily Vargas, who were undergraduates in Yeh’s laboratory; and Jeffrey H. Miller, a UCLA distinguished professor of microbiology, immunology and molecular genetics.

    Yeh’s research was funded by the Hellman Foundation. Savage’s research was funded by a James S. McDonnell Foundation Complex Systems Scholar Award and from the National Science Foundation. Beppler received funding from the National Institutes of Health Initiative to Maximize Student Development.

    See the full article here .

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    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

     
  • richardmitnick 12:20 pm on February 7, 2017 Permalink | Reply
    Tags: , Chemistry, , First-principles evolutionary algorithm called USPEX, Na2He electride, , Scientists discover helium chemistry   

    From EurekaAlert: “Scientists discover helium chemistry” 

    eurekaalert-bloc

    EurekaAlert

    1
    Crystal structure of Na2He, resembling a three-dimensional checkerboard. The purple spheres represent sodium atoms, which are inside the green cubes that represent helium atoms. The red regions inside voids of the structure show areas where localized electron pairs reside. Credit: Illustration is provided courtesy of Artem R. Oganov.

    6-Feb-2017
    Media Contact
    Asya Shepunova
    shepunova@phystech.edu
    7-916-813-0267

    Although helium is the second most-abundant element (after hydrogen) in the universe, it doesn’t play well with others. It is a member of a family of seven elements called the noble gases, which are called that because of their chemical aloofness — they don’t easily form compounds with other elements. Helium, widely believed to be the most inert element, has no stable compounds under normal conditions.

    Now, an international team of researchers led by Skoltech’s Prof. Artem R. Oganov (also a professor at Stony Brook University and head of Computational Materials Discovery laboratory at Moscow Institute of Physics and Technology) has predicted two stable helium compounds — Na2He and Na2HeO. The scientists experimentally confirmed and theoretically explained the stability of Na2He. This work could hold clues about the chemistry occurring inside gas giant planets and possibly even stars, where helium is a major component. The work is published by Nature Chemistry.

    The authors of the study used a crystal structure-predicting tool, the first-principles evolutionary algorithm called USPEX, to conduct a systematic search for stable helium compounds. They predicted the existence of Na2He, which was then successfully synthesized in a diamond anvil cell (DAC) experiment performed at the Carnegie Institution for Science in Washington by Prof. Alexander F. Goncharov and his colleagues. The compound appeared at pressures of about 1.1 million times Earth’s atmospheric pressure and is predicted to be stable at least up to 10 million times that.

    “The compound that we discovered is very peculiar: helium atoms do not actually form any chemical bonds, yet their presence fundamentally changes chemical interactions between sodium atoms, forces electrons to localize inside cubic voids of the structure and makes this material insulating,” says Xiao Dong, the first author of this work, who was a long-term visiting student in Oganov’s laboratory at the time when this work was done.

    Na2He is what’s called an electride, which is a special type of an ionic salt-like crystal. It has a positively charged sublattice of sodium ions and another negatively charged sublattice formed of localized electron pairs. Because electrons are strongly localized, this material is an insulator, meaning that it cannot conduct the free-flowing electrons that make up an electric current.

    The other predicted helium compound, Na2HeO, was found to be stable in the pressure range from 0.15 to 1.1 million atmospheres. It is also an ionic crystal with a structure similar to that of Na2He. However, in place of electron pairs, it has negatively charged oxygen in the form of O²?.

    “This study shows how new surprising phenomena can be discovered by combination of powerful theoretical methods and state-of-the-art experiments. It shows that very weird chemical phenomena and compounds can emerge at extreme conditions, and the role of such phenomena inside planets needs to be explored,” says Oganov.

    See the full article here .

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    EurekAlert!, the premier online news source focusing on science, health, medicine and technology, is a free service for reporters worldwide.

    Since 1996, EurekAlert! has served as the leading destination for scientific organizations seeking to disseminate news to reporters and the public. Today, thousands of reporters around the globe rely on EurekAlert! as a source of ideas, background information, and advance word on breaking news stories.

    More than 1,000 peer-reviewed journals, universities, medical centers, government agencies and public relations firms have used EurekAlert! to distribute their news. EurekAlert! is an authoritative and comprehensive research news source for journalists all over the world.

     
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