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  • richardmitnick 12:53 pm on January 14, 2016 Permalink | Reply
    Tags: , Chemistry,   

    From Princeton: “‘Radiolabeling’ lets scientists track the breakdown of drugs” 

    Princeton University
    Princeton University

    January 14, 2016
    Tien Nguyen, Department of Chemistry

    1
    Renyuan Pony Yu, a graduate student working with Princeton Professor Paul Chirik, has discovered a new way to radiolabel compounds for use in drug development.

    A new method for labeling molecules with radioactive elements could let chemists more easily track how drugs under development are metabolized in the body.

    Chemists consider thousands of compounds in the search for a new drug, and a candidate’s metabolism is a key factor that must be evaluated carefully and quickly. Researchers at Princeton University and pharmaceutical company Merck & Co., Inc. report in the journal Nature that scientists can selectively replace hydrogen atoms in molecules with tritium atoms — a radioactive form of hydrogen that possesses two extra neutrons — to “radiolabel” compounds. This technique can be done in a single step while preserving the biological properties of the parent compound.

    While current state-of-the-art techniques are quite reliable, they only work when dissolved in specific solvents, ones that aren’t always capable of dissolving the drug compound of interest. The researchers’ method, however, used an iron-based catalyst that is tolerant to a wider variety of solvents, and it labels the molecules at the opposite positions as compared to existing methods.

    “The fact that you can access other positions is what makes this reaction really special,” said corresponding author Paul Chirik, the Edwards S. Sanford Professor of Chemistry at Princeton. Previous methods only incorporate radioactive tritium atoms into the molecule directly next to an atom or a group of atoms called a directing group. The new iron-catalyzed method does not require a directing group, and instead places tritium at whatever positions in the molecules are the least crowded.

    “Radiolabeled compounds help medicinal chemists get a better picture of what actually happens to the drug by showing how the drug is metabolized and cleared,” said David Hesk, a collaborator at Merck and co-author on the work. By rapidly assessing the compounds’ metabolism early on, scientists can shorten the time it takes to develop and bring a drug to market. “Having another labeling reaction is very powerful because it gives radiochemists another tool in the toolbox,” he said.

    This unique reactivity was actually discovered unexpectedly. Renyuan Pony Yu, a graduate student in the Chirik lab, had originally set out to use their iron catalyst for a different reaction that they were collaborating on with Merck. To study the iron catalyst’s capabilities, Yu subjected it to a technique called proton nuclear magnetic resonance spectroscopy (NMR), which allows chemists to deduce the positions of hydrogen atoms in molecules.

    “We started seeing this beautiful, very systematic pattern of signals in the NMR, but we didn’t really know what they were,” said Yu, who is first author on the new study. Particularly puzzling was the fact that the pattern of signals would disappear over time.

    The researchers turned to Istvan Pelczer, Director of the NMR Facility at Princeton chemistry and co-author on the work, who developed a special technique that helped them analyze the signals with much greater confidence. Using this method, they realized that the iron catalyst was reacting with the liquid solvent used to dissolve the NMR sample. The solvent’s deuterium atoms, another form of hydrogen that has one extra neutron and is not radioactive, were replacing the hydrogen atoms.

    It wasn’t until Yu presented his findings to Matt Tudge, the Princeton authors’ collaborator at Merck, that the catalyst’s potential to introduce tritium atoms into radiolabeled molecules was recognized. “This is a classic example where you really need both partners,” Chirik said. “We were the catalyst experts, but they were the applications experts.”

    Though tritium-labeled compounds are used mostly in metabolism studies, they can also be helpful at the very outset of a drug-discovery project to identify a biological target that the potential drugs can be tested against. The biological target could be an enzyme or protein associated with a certain disease. For example, statins are a well-known class of cholesterol-lowering drugs that target a specific enzyme in the body called HMG-CoA reductase.

    To explore the scope of the reaction, Yu first optimized the reaction to incorporate deuterium atoms, which is commonly accepted as a model system for tritium. He found that the iron catalyst was surprisingly robust and successfully labeled many different types of compounds, including some from Merck’s library of past drug candidates.

    “It was a very exciting project for me because I got to work with real drugs that are fully functionalized and useful,” Yu said. One of their test substrates was Claritin, which Yu bought from a local store; he extracted its active ingredient back in the lab.

    Finally, Yu traveled to Merck’s campus in Rahway, where he received radioactivity training — Chirik’s laboratory isn’t equipped to handle radioactivity — and performed the reactions using tritium gas. The reactions were run in a special apparatus that looks like a steel-lined box and releases radioactive tritium gas. The apparatus can capture any unspent gas to limit the amount of radioactive waste produced.

    Chemists take care to handle radioactive compounds and waste very carefully, but tritium’s radioactivity is so weak that the particles it emits cannot penetrate simple glassware. For this reason, tritium-labeled compounds can’t be used in any human imaging studies such as PET scans, which require radiolabeled compounds that emit high-energy particles.

    This past summer, Yu presented the preliminary results of the iron-catalyzed reaction at the 2015 International Isotope Society Symposia to researchers in the radiolabeling and pharmaceutical community. They were very excited about the research and eager to use the catalyst in their own studies, Yu said.

    But the major challenge for the researchers is that the iron catalyst is extremely air and moisture sensitive, and it can only be handled inside a glovebox, a special chamber in which oxygen and water vapor have been excluded. The Chirik group is working to develop a more stable catalyst that can be made commercially available, and have recently entered into a partnership with Green Center Canada, a company that helps bring academic research to market.

    In the meantime, the Chirik group has found that the iron catalyst can replace hydrogen atoms with other groups besides deuterium and tritium atoms and is extending this chemistry into many other projects in the lab.

    “This project is always going to be a special one for me because it’s kind of a pivot point for the type of chemistry that our group can do,” Chirik said, “and there’s this really cool application.”

    Read the abstract.

    Yu, R. P.; Hesk, D.; Rivera, N.; Pelczer, I.; Chirik, P. J. Iron-Catalyzed Tritiation of Pharmaceuticals. Nature, 2016, DOI: 10.1038/nature16464.

    This work was supported by Merck & Co. and Princeton University’s Intellectual Property Accelerator Fund.

    See the full article here .

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    Princeton University Campus

    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

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  • richardmitnick 7:58 am on January 9, 2016 Permalink | Reply
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    From The Conversation: “The race to find even more new elements to add to the periodic table” 

    Conversation
    The Conversation

    January 5, 2016
    David Hinde
    Director, Heavy Ion Accelerator Facility, Australian National University

    Temp 1

    In an event likely never to be repeated, four new superheavy elements were last week simultaneously added to the periodic table. To add four in one go is quite an achievement but the race to find more is ongoing.

    Back in 2012, the International Unions of Pure and Applied Chemistry (IUPAC) and Pure and Applied Physics (IUPAP) tasked five independent scientists to assess claims made for the discovery of elements 113, 115, 117 and 118. The measurements had been made at Nuclear Physics Accelerator laboratories in Russia (Dubna) and Japan (RIKEN) between 2004 and 2012.

    Late last year, on December 30, 2015, IUPAC announced that claims for the discovery of all four new elements had been accepted.

    Periodic Table 2016
    The completed seventh row in the periodic table. Wikimedia Commons

    This completes the seventh row of the periodic table, and means that all elements between hydrogen (having only one proton in its nucleus) and element 118 (having 118 protons) are now officially discovered.

    After the excitement of the discovery, the scientists now have the naming rights. The Japanese team will suggest the name for element 113. The joint Russian/US teams will make suggestions for elements 115, 117 and 118. These names will be assessed by IUPAC, and once approved, will become the new names that scientists and students will have to remember.

    Until their discovery and naming, all superheavy elements (up to 999!) have been assigned temporary names by the IUPAC. Element 113 is known as ununtrium (Uut), 115 is ununpentium (Uup), 117 is ununseptium (Uus) and 118 ununoctium (Uuo). These names are not actually used by physicists, who instead refer to them as “element 118”, for example.

    The superheavy elements

    Elements heavier than Rutherfordium (element 104) are referred to as superheavy. They are not found in nature, because they undergo radioactive decay to lighter elements.

    Those superheavy nuclei that have been created artificially have decay lifetimes between nanoseconds and minutes. But longer-lived (more neutron-rich) superheavy nuclei are expected to be situated at the centre of the so-called island of stability, a place where neutron-rich nuclei with extremely long half-lives should exist.

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    Measured (boxed) and predicted (shaded) half-lives of isotopes, sorted by number of protons and neutrons. The expected location of the island of stability is circled.

    Currently, the isotopes of new elements that have been discovered are on the “shore” of this island, since we cannot yet reach the centre.

    How were these new elements created on Earth?

    Atoms of superheavy elements are made by nuclear fusion. Imagine touching two droplets of water – they will “snap together” because of surface tension to form a combined larger droplet.

    The problem in the fusion of heavy nuclei is the large numbers of protons in both nuclei. This creates an intense repulsive electric field. A heavy-ion accelerator must be used to overcome this repulsion, by colliding the two nuclei and allowing the nuclear surfaces to touch.

    This is not sufficient, as the two touching spheroidal nuclei must change their shape to form a compact single droplet of nuclear matter – the superheavy nucleus.

    It turns out that this only happens in a few “lucky” collisions, as few as one in a million.


    view or download mp4 video here .
    Superheavy reaction fails to fuse (ANU)

    There is yet another hurdle; the superheavy nucleus is very likely to decay almost immediately by fission. Again, as few as one in a million survives to become a superheavy atom, identified by its unique radioactive decay.

    The process of superheavy element creation and identification thus requires large-scale accelerator facilities, sophisticated magnetic separators, efficient detectors and time.

    Finding the three atoms of element 113 in Japan took 10 years, and that was after the experimental equipment had been developed.

    The payback from the discovery of these new elements comes in improving models of the atomic nucleus (with applications in nuclear medicine and in element formation in the universe) and testing our understanding of atomic relativistic effects (of increasing importance in the chemical properties of the heavy elements). It also helps in improving our understanding of complex and irreversible interactions of quantum systems in general.

    The Australian connection in the race to make more elements

    The race is now on to produce elements 119 and 120. The projectile nucleus Calcium-48 (Ca-48) – successfully used to form the newly accepted elements – has too few protons, and no target nuclei with more protons are currently available. The question is, which heavier projectile nucleus is the best to use.

    To investigate this, the leader and team members of the German superheavy element research group, based in Darmstadt and Mainz, recently travelled to the Australian National University.

    They made use of unique ANU experimental capabilities, supported by the Australian Government’s NCRIS program, to measure fission characteristics for several nuclear reactions forming element 120. The results will guide future experiments in Germany to form the new superheavy elements.

    It seems certain that by using similar nuclear fusion reactions, proceeding beyond element 118 will be more difficult than reaching it. But that was the feeling after the discovery of element 112, first observed in 1996. And yet a new approach using Ca-48 projectiles allowed another six elements to be discovered.

    Nuclear physicists are already exploring different types of nuclear reaction to produce superheavies, and some promising results have already been achieved. Nevertheless, it would need a huge breakthrough to see four new nuclei added to the periodic table at once, as we have just seen.

    See the full article here .

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    The Conversation US launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 2:09 pm on January 1, 2016 Permalink | Reply
    Tags: , Chemistry, ,   

    From LLNL: “Lawrence Livermore credited with discovery of elements 115, 117 and 118” 


    Lawrence Livermore National Laboratory

    Dec. 31, 2015

    Anne M. Stark
    stark8@llnl.gov
    925-784-3926

    The International Union of Pure and Applied Chemistry (link is external) (IUPAC) has confirmed that Lawrence Livermore National Laboratory scientists and international collaborators have officially discovered elements 115, 117 and 118.

    The announcement means those three elements are one step closer to being named.

    Lawrence Livermore teamed with the Joint Institute for Nuclear Research (link is external)in Dubna, Russia (JINR) in 2004 to discover elements 113 [?, claimed by RIKEN http://www.riken.jp/en/pr/press/2015/20151231_1/ ] and 115. LLNL worked again with JINR in 2006 to discover element 118. The LLNL/JINR team then jointly worked with researchers from the Research Institute for Advanced Reactors (Dimitrovgrad), Oak Ridge National Laboratory, (link is external) Vanderbilt University and the University of Nevada, Las Vegas, to discover element 117 in 2010.

    “This is a very exciting time for our collaboration and shows that all of the hard work has paid off. It is especially gratifying to receive this news right as we enter a new year,” said Dawn Shaughnessy, Lawrence Livermore’s principle investigator for the Heavy Element Group. “I am so proud of all of the hard work that this group has done over the years performing these experiments. Our colleagues in Russia have worked endless hours at the accelerator working toward these results. It is a wonderful gift to the entire group that we are recognized for our efforts in accomplishing these highly difficult experiments and for the years of work it takes to successfully create a new chemical element. Congratulations also to the team in Japan for their efforts in creating element 113. Those were extremely lengthy and difficult experiments and it is a credit to their program to be recognized in this way.”

    This discovery brings the total to six new elements reported by the Dubna-Livermore team (113, 114, 115, 116, 117, and 118, the heaviest element to date). The IUPAC announced that a Japanese collaboration officially discovered element 113. The LLNL/JINR team had submitted a paper on the discovery of elements 113 and 115 about the same time as the Japanese group.

    In 2011, the IUPAC confirmed the name Livermorium for element 116 [symbol Lv].

    Temp 1

    Temp 2
    Periodic Table showing Livermorium

    Livermorium (atomic symbol Lv) was chosen to honor Lawrence Livermore National Laboratory and the city of Livermore, Calif. A group of researchers from the Laboratory, along with scientists at the Flerov Laboratory of Nuclear Reactions at JINR, participated in the work carried out in Dubna on the synthesis of superheavy elements, including element 116. (Lawrencium — Element 103 — was already named for LLNL’s founder E.O. Lawrence.)

    Elements beyond atomic number 104 are referred to as superheavy elements. Although superheavy elements have not been found in nature, they can be produced by accelerating beams of nuclei and shooting them at the heaviest possible target nuclei. Fusion of two nuclei — a very rare event — occasionally produces a superheavy element. They generally only exist for a short time.

    The discovery of heavier and heavier elements brings researchers one step closer to the island of stability, a term in nuclear physics that refers to the possible existence of a region beyond the current periodic table where new superheavy elements with special numbers of neutrons and protons would exhibit increased stability.

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    Island of stability

    Such an island would extend the periodic table to even heavier elements and support longer isotopic lifetimes to enable chemistry experiments.

    See the full article here .

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    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
    Administration
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  • richardmitnick 7:55 am on December 31, 2015 Permalink | Reply
    Tags: , Chemistry, Element 113 [Ununtrium],   

    From RIKEN: “It’s official! Element 113 was discovered at RIKEN” 

    RIKEN bloc

    RIKEN

    December 31, 2015

    Element 113, discovered by a RIKEN group led by Kosuke Morita, has become the first element on the periodic table found in Asia.

    1
    Ununtrium in the periodic table

    Rewarding nearly a decade of painstaking work by Morita’s group, a Joint Working Party of the International Union of Pure and Applied Chemistry (IUPAC) and International Union of Pure and Applied Physics (IUPAP) has recommended that the group, from the RIKEN Nishina Center for Accelerator-based Science (RNC), be given recognition for the discovery of the new element. This news was conveyed to Dr. Morita through a letter on December 31 from IUPAC.

    In the late 1980s, the group began using RIKEN’s Linear Accelerator Facility and the GARIS ion separator, developed by Morita and his group, to explore new synthetic superheavy elements.

    RIKEN Linear Accelerator
    RIKEN’s Linear Accelerator Facility

    RIKEN GARIS Ion Separator
    GARIS Ion Seoarator

    The work of discovering new superheavy elements is very difficult, and the elements tend to decay extremely quickly—the isotopes of 113 produced at RIKEN lasted for less than a thousandth of a second.

    3
    Position of the transactinide elements in the periodic table.

    Researchers persevere, however, as the research is important for understanding the structure of atomic nuclei. Scientists hope that the work will lead eventually to the discovery of a so-called “island of stability” where elements with longer half-lives will be found.

    4
    Measured (boxed) and predicted (shaded) half-lives of isotopes, sorted by number of protons and neutrons. The expected location of the island of stability is circled.

    The search at RIKEN for element 113 started in September 2003, when Morita’s group began bombarding a thin layer of bismuth with zinc ions travelling at about 10% the speed of light. Theoretically, they would occasionally fuse, forming an atom of element 113.

    The team achieved its first success on July 23, 2004, less than a year after starting the experiment. Two atomic nuclei fused, leading to the creation of a nucleus of element 113, which quickly underwent four alpha decays to transform into dubnium-262 (element 105), which then underwent spontaneous fission. Less than a year later, on April 2, 2005, the team saw a second event—an identical decay to dubnium-262 followed by fission. Though these were good demonstrations, they were not considered conclusive evidence for the existence of element 113, because the decay chain did not demonstrate “firm connections to known nuclides” (according to the Joint Working Party’s 2011 report). The team pushed on with its efforts. In order to create a better picture of the decay chain from bohrium-266 to lawrencium-258, which had not been well characterized, the group performed a new experiment, where a sodium beam was collided with a curium target, creating borhium-266 and its daughter nucleus, dubnium-262. With this demonstration, the grounds for a stronger claim were laid. They just needed to wait to see an atom decaying through the alpha chain rather than spontaneous fission.

    Following the two initial events, however, the team’s luck seemed to run dry. “For over seven years,” says Morita, “we continued to search for data conclusively identifying element 113, but we just never saw another event. I was not prepared to give up, however, as I believed that one day, if we persevered, luck would fall upon us again.”

    Then, on August 12, 2012, the group observed the crucial third event. This time, following the four initial decays, the dubnium-262 continued to undergo alpha decays rather than spontaneous fission, transforming into lawrencium-258 (element 103) and then finally mendelevium-254 (element 101). As the chain had been clearly characterized, it demonstrated clearly that element 113 was the source of the decay chain.

    In response to the new event, coupled with the group’s demonstration of the decay chain, IUPAC has announced that Morita’s group will be given priority for the discovery of the new element, a privilege that includes the right to propose a name for it.

    For Morita, then, part of the coming year will be devoted to thinking of and proposing a formal name for element 113, but he is also looking forward to the next step in his research. “Now that we have conclusively demonstrated the existence of element 113,” he says, “we plan to look to the uncharted territory of element 119 [Ununennium] and beyond, aiming to examine the chemical properties of the elements in the seventh and eighth rows of the periodic table, and someday to discover the island of stability.”

    The results of these experiments were reported in the Journal of Physical Society of Japan. The IUPAC report granting the naming rights to Morita’s group will be published in an early 2016 issue of the IUPAC journal Pure and Applied Chemistry (PAC).

    See the full article here .

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    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 1:18 pm on December 22, 2015 Permalink | Reply
    Tags: , , Chemistry,   

    From Caltech: “Toward Liquid Fuels from Carbon Dioxide” 

    Caltech Logo
    Caltech

    12/22/2015
    Ker Than

    1
    C1 to C2: Connecting carbons by reductive deoxygenation and coupling of CO Credit: Kyle Horak and Joshua Buss/Caltech

    In the quest for sustainable alternative energy and fuel sources, one viable solution may be the conversion of the greenhouse gas carbon dioxide (CO2) into liquid fuels.

    Through photosynthesis, plants convert sunlight, water, and CO2 into sugars, multicarbon molecules that fuel cellular processes. CO2 is thus both the precursor to the fossil fuels that are central to modern life as well as the by-product of burning those fuels. The ability to generate synthetic liquid fuels from stable, oxygenated carbon precursors such as CO2 and carbon monoxide (CO) is reminiscent of photosynthesis in nature and is a transformation that is desirable in artificial systems. For about a century, a chemical method known as the Fischer-Tropsch process has been utilized to convert hydrogen gas (H2) and CO to liquid fuels. However, its mechanism is not well understood and, in contrast to photosynthesis, the process requires high pressures (from 1 to 100 times atmospheric pressure) and temperatures (100–300 degrees Celsius).

    More recently, alternative conversion chemistries for the generation of liquid fuels from oxygenated carbon precursors have been reported. Using copper electrocatalysts, CO and CO2 can be converted to multicarbon products. The process proceeds under mild conditions, but how it takes place remains a mystery.

    Now, Caltech chemistry professor Theo Agapie and his graduate student Joshua Buss have developed a model system to demonstrate what the initial steps of a process for the conversion of CO to hydrocarbons might look like.

    The findings, published as an advanced online publication for the journal Nature on December 21, 2015 (and appearing in print on January 7, 2016), provide a foundation for the development of technologies that may one day help neutralize the negative effects of atmospheric accumulation of the greenhouse gas CO2 by converting it back into fuel. Although methods exist to transform CO2 into CO, a crucial next step, the deoxygenation of CO molecules and their coupling to form C–C bonds, is more difficult.

    In their study, Agapie and Buss synthesized a new transition metal complex—a metal atom, in this case molybdenum, bound by one or more supporting molecules known as ligands—that can facilitate the activation and cleavage of a CO molecule. Incremental reduction of the molecule leads to substantial weakening of the C–O bonds of CO. Once weakened, the bond is broken entirely by introducing silyl electrophiles, a class of silicon-containing reagents that can be used as surrogates for protons.

    This cleavage results in the formation of a terminal carbide—a single carbon atom bound to a metal center—that subsequently makes a bond with the second CO molecule coordinated to the metal. Although a carbide is commonly proposed as an intermediate in CO reductive coupling, this is the first direct demonstration of its role in this type of chemistry, the researchers say. Upon C–C bond formation, the metal center releases the C2 product. Overall, this process converts the two CO units to an ethynol derivative and proceeds easily even at temperatures lower than room temperature.

    “To our knowledge, this is the first example of a well-defined reaction that can take two carbon monoxide molecules and convert them into a metal-free ethynol derivative, a molecule related to ethanol; the fact that we can release the C2 product from the metal is important,” Agapie says.

    While the generated ethynol derivative is not useful as a fuel, it represents a step toward being able to generate synthetic multicarbon fuels from carbon dioxide. The researchers are now applying the knowledge gained in this initial study to improve the process. “Ideally, our insight will facilitate the development of practical catalytic systems,” Buss says.

    The scientists are also working on a way to cleave the C–O bond using protons instead of silyl electrophiles. “Ultimately, we’d like to use protons from water and electron equivalents derived from sunlight,” Agapie says. “But protons are very reactive, and right now we can’t control that chemistry.”

    The research in the paper, “Four-electron deoxygenative reductive coupling of carbon monoxide at a single metal site,” was funded by Caltech and the National Science Foundation.

    See the full article here .

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 12:37 pm on November 30, 2015 Permalink | Reply
    Tags: , Chemistry,   

    From ORNL via DOE Pulse: “ORNL Wigner Fellow writes the recipe for glowing research” 

    i1

    Oak Ridge National Laboratory

    November 30, 2015

    1
    ORNL’s Michael Chance

    In 2013, an inorganic chemistry student at the University of South Carolina conducted neutron experiments at DOE’s Oak Ridge National Laboratory for his Ph.D. work.

    Two years later, Michael Chance is picking right back up on his research at ORNL as a Eugene P. Wigner Fellow, the most prestigious fellowship at ORNL.

    The Wigner Fellowship, established in 1975, was created in honor of Nobel Laureate and the first ORNL Director of Research and Development.

    ORNL Wigner Fellows are exceptional early career scientists like Chance who, for his doctoral thesis, established a new crystal growth technique. As a Wigner Fellow, Chance has a rare opportunity to pursue research programs, collaborate with ORNL distinguished scientists and staff and access national laboratory expertise, facilities, and programs.

    “It’s exciting, being a Wigner Fellow and getting this support from a national lab to do real science and solve real problems,” said Chance.

    As a Wigner Fellow, Chance has had the opportunity to work with the Critical Materials Institute (CMI), an Energy Department Innovation Hub led by Ames Laboratory. CMI, supported by the Advanced Manufacturing Office in DOE’s Office of Energy Efficiency and Renewable Energy, is dedicated to reducing the nation’s dependence on vital, yet expensive and critical materials.

    Chance’s CMI research requires him to pull from his training as a solid-state chemist to reimagine and improve an important, everyday technology: fluorescent lighting.

    Flick on a fluorescent light switch, and chemistry happens. Within the glass light tube is mercury vapor that bombards a luminescent coating, called phosphor, with UV rays. This causes the phosphors to emit visible light.

    “The problem with the fluorescent lights that are commonly used is that they require phosphors with a large amount of rare earths in them,” said Chance.

    Fluorescent lights are more energy-efficient than incandescent light bulbs, but LED lighting has recently emerged as a forerunner in efficient lighting technology. Transitioning to the next-generation technology won’t happen rapidly, Chance explained.

    “LEDs (light emitting diodes) are rapidly growing their market share, but fluorescent lighting is poised to remain relevant for some time,” said Chance.

    Chance is part of an ORNL Materials Science and Technology Division team whose goal is to lessen the dependence on rare earths in the popular fluorescent lighting source.

    “Currently, we’re depending on these materials that are very expensive and at risk for supply disruptions,” Chance said. “DOE targets require us to significantly reduce the amount of rare earths in the phosphor coating to address this.”

    To do so, the team is testing new combinations of chemicals, tweaking the recipe for creating phosphors to find direct substitutes for the current phosphor blend.

    “A lot of solid-state science is like cooking—you’ve got to find the right recipe,” he said. “It’s not just what goes in the recipe, it’s the way you cook it that really makes a difference. Once I make a phosphor, it’s got to stand up to a really tough testing environment. It’s not easy,” said Chance.

    He points to his background in crystal growth methods as a big part of helping in the Edisonian approach for finding the right combination of chemicals.

    “You need to use chemistry knowledge and intuition for the phosphor research. You need to discover trends from what’s in the literature, new and old, to see what to try next,” Chance said.

    He keeps a lab notebook prominently on his desk, full of what he calls “scrupulous notes” on his successes and setbacks in synthesizing manganese-based phosphors.

    “It is paramount to keep track of everything in the process so others can reproduce it.”

    The transition to the thriving science culture at the national laboratory from university studies has been relatively easy for Michael Chance. Though he’s a native of Marshall County, Kentucky, Chance recently settled in East Tennessee with his wife, an art teacher at a local elementary school.

    He’s adjusted to life at ORNL with ease.

    “While I was a student at the University of South Carolina, our research group collaborated on a project at ORNL with Lynn Boatner [leader of the Synthesis and Properties of Novel Materials Group in ORNL’s Materials Science and Technology Division,” said Chance.

    See the full article here .

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  • richardmitnick 1:31 pm on November 16, 2015 Permalink | Reply
    Tags: , , , Chemistry,   

    From ASU: “Forged in the hearts of stars” 

    ASU Bloc

    Arizona State University

    November 16th, 2015
    Nikki Cassis

    ASU and UNC researchers to study thermonuclear reaction rates to determine how much of certain elements exploding stars can produce

    We are all made from stars. And that’s not just a beautiful metaphor.

    Apart from hydrogen, as many have heard from the Carl Sagan and Neil DeGrasse Tyson Cosmos series, every ingredient in the human body is made from elements forged by stars.

    The calcium in our bones, the oxygen we breathe, the iron in our blood – all those are forged in the element factories of stars. Even the carbon in our apple pie.

    Stars are giant element furnaces. Their intense heat can cause atoms to collide, creating new elements – a process known as nuclear fusion. That process is what created chemical elements like carbon or iron – the building blocks that make up life as we know it.

    It sounds pretty simple, but it is a very intricate process. And there are still many uncertainties.

    Professors Sumner Starrfield and Frank Timmes, both from Arizona State University, and Professor Christian Iliadis, from the University of North Carolina at Chapel Hill, hope to resolve some of those uncertainties.

    “Broad brush we have a good idea that massive stars become one kind of supernova and binary stars with white dwarfs become another type of supernova. We know a lot about what may have caused the explosions but there are many unexplained parts that need to be worked out,” said Starrfield, Regents’ Professor in ASU’s School of Earth and Space Exploration.

    The team was awarded a NASA grant of nearly $700,000 to better understand how supernovae evolve to an explosion. The study is aimed at determining how much of certain elements a star can produce.

    Inside these element factories, how much carbon for our apple pies gets made, how much calcium is available to make our bones, depends on their nuclear reaction rates.

    For example, as shown in the recent movie The Martian, if you were trying to make water, you would take hydrogen and oxygen and some energy and put it together in a container and it would make water at a certain rate depending on the temperature of the container. Add more heat, and the reaction speeds up, producing more water.

    A similar thing happens inside stars – except it’s nuclear reactions releasing a factor of one million times more energy than a chemical reaction. Stars run on nuclear reactions. Smash together a carbon nucleus and a helium nucleus inside the furnace of a star, and out pops the oxygen we breathe. Speed up that reaction, and the star yields more oxygen.

    Researchers use computers and solve equations to predict how a star evolves. Part of that input into how stars evolve are nuclear reaction rates. One set rate has been used to arrive at an estimate of how much of a certain element a star can produce. But is that number optimal? Is it some super optimistically high value, or it pessimistically low?

    “What we will define is a meaningful range, given the uncertainties of what is measured here on Earth, of what actually comes out. At the end of the day, what we are going to know is the variation – how much variation is there in a star’s output. How much calcium or carbon comes out of the star?” said Timmes, an astrophysicist in ASU’s School of Earth and Space Exploration.

    Investigating the range of elements that a star can produce is based on what is measured in the terrestrial laboratory. This is where nuclear physicist Iliadis, who recently published a textbook on the nuclear physics of stars, fits in; he’s the experimentalist providing the data on the nuclear fusion reaction rates and their uncertainties.

    “It is not quite “The power of the Sun, in the palm of my hands”, as muttered by Dr. Octavius in Spiderman 2; nevertheless we do measure with our accelerator facilities the very same nuclear fusion reactions that occur in stars,” said Iliadis.

    But uncertainties are inherent in lab measurements. What you want to do is connect what you do in the lab with what you see in the night sky. And that’s Starrfield’s contribution – he’s an expert in dead and dying suns. He will use the reaction rates from Iliadis in new calculations of how different types of stars can become supernovae.

    This proposal ties in a tight loop experiments done here on earth with observations in the night sky. For over two decades Timmes has been doing modeling of stars; the models he creates will serve as the glue between what is measured on earth by Iliadis and what is seen in the dark night sky by Starrfield.

    The team is going to be checking roughly 50 of the most important nuclear reaction rates for producing elements that form the building blocks of life as we know it. And just as important, some of these reaction rates are useful in nuclear fusion experiments to produce clean power on Earth.

    As a star ages, hydrogen and then helium nuclei fuse to form heavier elements. These reactions continue in stars today as lighter elements are transformed into heavier ones.

    Late in life, most stars will explode, ejecting the elements they forged into interstellar space. If a star is heavy enough, or has a close companion, it will explode in a supernova that creates many heavy elements including iron and nickel. The explosion also disperses the different elements across the galaxy, scattering the stellar material that will eventually make up planets, including Earth.

    Starrfield will compare their calculations with observations of exploding stars and determine the amounts of chemical elements blown into space. “We are the results,” said Starrfield.

    See the full article here .

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    ASU is the largest public university by enrollment in the United States.[11] Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under control of the Arizona Board of Regents and was renamed Arizona State College.[12][13][14] A 1958 statewide ballot measure gave the university its present name.
    ASU is classified as a research university with very high research activity (RU/VH) by the Carnegie Classification of Institutions of Higher Education, one of 78 U.S. public universities with that designation. Since 2005 ASU has been ranked among the Top 50 research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded patents and awarded research grant proposals. The Center for Measuring University Performance currently ranks ASU 31st among top U.S. public research universities.[15]

    ASU awards bachelor’s, master’s and doctoral degrees in 16 colleges and schools on five locations: the original Tempe campus, the West campus in northwest Phoenix, the Polytechnic campus in eastern Mesa, the Downtown Phoenix campus and the Colleges at Lake Havasu City. ASU’s “Online campus” offers 41 undergraduate degrees, 37 graduate degrees and 14 graduate or undergraduate certificates, earning ASU a Top 10 rating for Best Online Programs.[16] ASU also offers international academic program partnerships in Mexico, Europe and China. ASU is accredited as a single institution by The Higher Learning Commission.

    ASU Tempe Campus
    ASU Tempe Campus

     
  • richardmitnick 8:00 am on October 7, 2015 Permalink | Reply
    Tags: , , Chemistry   

    From NYT: “Nobel Prize in Chemistry Awarded to Tomas Lindahl, Paul Modrich and Aziz Sancar for DNA Studies” 

    New York Times

    The New York Times

    OCT. 7, 2015
    WILLIAM J. BROAD

    1
    The portraits of the winners of the Nobel Prize in Chemistry in Stockholm on Wednesday: Tomas Lindahl, Paul L. Modrich and Aziz Sancar Credit: Jonathan Nackstrand/Agence France-Presse — Getty Images

    Tomas Lindahl, Paul L. Modrich and Aziz Sancar were awarded the Nobel Prize in Chemistry on Wednesday for having mapped and explained how the cell repairs its DNA and safeguards its genetic information.

    Dr. Lindahl, of the Francis Crick Institute in London, was honored for his discoveries on base excision repair — the cellular mechanism that repairs damaged DNA during the cell cycle. Dr. Modrich, of the Howard Hughes Medical Institute and Duke University School of Medicine, was recognized for showing how cells correct errors that occur when DNA is replicated during cell division. Dr. Sancar, of the University of North Carolina, Chapel Hill, was cited for mapping the mechanism cells use to repair ultraviolet damage to DNA.

    “Their systematic work has made a decisive contribution to the understanding of how the living cell functions, as well as providing knowledge about the molecular causes of several hereditary diseases and about mechanisms behind both cancer development and aging,” the Royal Swedish Academy of Sciences, which awarded the prize, said in a statement.

    They shared the prize of 8 million Swedish kronor, or about $960,000. The prize was announced in Stockholm by Goran K. Hansson, the academy’s permanent secretary.

    The three winners joined the 169 laureates, including Ernest Rutherford, Marie Curie and Linus Pauling, who have been honored with the prize since 1901. (One of them, Frederick Sanger, won twice.)

    See the full article here .

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  • richardmitnick 3:40 pm on September 22, 2015 Permalink | Reply
    Tags: , Chemistry,   

    From ETH Zürich: “Chemistry for the methanol economy” 

    ETH Zurich bloc

    ETH Zürich

    22.09.2015
    Fabio Bergamin

    Unstable crude oil prices and limited oil resources have made the production of petrochemicals from methanol increasingly popular – above all in China. Scientists at ETH Zurich have now deciphered the complex chemistry behind the start of this process.

    1
    The Shenhua Baotou production plant in north China converts coal into so-called olefins since 2010. It is the first industrial plant of its kind worldwide. (Photo: Syn Energy Technology Co. Ltd.)

    Ethylene is produced in greater amounts than any other basic chemical in the world. The small molecule consisting of two carbon atoms and four hydrogen atoms, it is a basic building block in the manufacture of a wide range of basic chemicals, polymers and plasticisers. The packaging material polyethylene (PE) is just one popular application among many. Today ethylene is primarily manufactured from crude oil in a process known as cracking, but the ongoing price volatility and the finite availability of crude oil have caused a surge for an alternative manufacturing approach: its synthesis from methanol in the so-called methanol-to-olefins (MTO) process. Now a team of scientists at ETH Zurich and ENS Lyon has worked out in detail how the reaction begins.

    Chemists developed the MTO process in the late 1970s, and today there are manufacturing plants all over the world. China has more MTO plants than any other country: five large-scale facilities are currently in operation and a further thirteen are planned. The reason for this is simple: China has a huge demand for petrochemicals with limited access to oil deposits. What the country does have is large coal reserves, and methanol can be manufactured quite easily by gasifying coal. In addition, methanol can be made from natural gas. Consequently, Chinese investors are planning to manufacture methanol in the United States for export to China, drawing on the U.S.’s plentiful shale gas reserves.

    Where does the carbenium ion come from?

    For the MTO reaction to occur, methanol is brought together with so-called zeolites at 400 degrees Celsius. These zeolites are porous, granular aluminosilicate minerals facilitating the reaction as catalysts. For a long time, chemists were unable to exactly explain the MTO reaction. 20 years ago scientists postulated that other molecules had to be involved: positively charged cyclic hydrocarbon molecules in which five to six carbon atoms are bonded together, also known as cyclic carbenium ions. Such species actually react with methanol: They stitch two methanol molecules together and form a carbon-carbon bond, before producing ethylene.

    However, if these cyclic carbenium ions are involved and necessary for the reaction to start, the question is where do they come from? Many scientists proposed that these ions must be present as adventitious contaminants in methanol.

    Now the Franco-Swiss research team has proposed a different explanation. “We have shown that alumina, which is always present in zeolites, can easily transform methanol into ethylene and other hydrocarbons, which can then be converted into carbenium ions in the pores of the zeolite catalyst,” explains Christophe Copéret, Professor of Surface and Interface Chemistry at ETH Zurich and one of the authors of the study. “While the MTO process is up and running at industrial scale, this work shades new light on how the process starts. And it shows that simple oxide materials like alumina can trigger carbon-carbon bond formation from methanol derivatives, thus opening new avenues for the upgrading of methanol into long chain hydrocarbons.”

    See the full article here .

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    ETH Zurich campus
    ETH Zurich is one of the leading international universities for technology and the natural sciences. It is well known for its excellent education, ground-breaking fundamental research and for implementing its results directly into practice.

    Founded in 1855, ETH Zurich today has more than 18,500 students from over 110 countries, including 4,000 doctoral students. To researchers, it offers an inspiring working environment, to students, a comprehensive education.

    Twenty-one Nobel Laureates have studied, taught or conducted research at ETH Zurich, underlining the excellent reputation of the university.

     
  • richardmitnick 8:52 am on August 11, 2015 Permalink | Reply
    Tags: , Chemistry,   

    From Princeton: “Nozomi Ando: Breaking free with a love of chemistry” 

    Princeton University
    Princeton University

    August 10, 2015
    Tien Nguyen, Department of Chemistry

    1
    The research of Nozomi Ando (above), a Princeton University assistant professor of chemistry, pushes the limits of using X-ray-based methods to unravel the structure of enzymes, which could help scientists understand how these incredibly complex molecules are central to biological processes such as cellular metabolism and DNA replication. Photos by Todd Reichart, Department of Chemistry

    At two in the morning, Princeton University’s Frick Chemistry Laboratory appears quiet and cavernous. But if you listen closely, faint drumbeats might be heard coming from the lab of Nozomi Ando as she and her students work to their favorite late-night band, Queen.

    “The hours aren’t required — we’ve just been driven by excitement about the science,” said Ando, an assistant professor in chemistry who joined the Princeton faculty in 2014. Almost a year later, Ando said the lab is still in the fun phase, energized by the constant collection of new data: “For me, it’s brain candy.”

    The Ando lab has already attracted two postdoctoral researchers, a graduate student and five undergraduates, all of them eager to be involved in her ambitious research program. These projects aim to push the limits of using X-ray-based methods in structural enzymology, which is the study of the structure of enzymes such as those responsible for cellular metabolism and DNA replication. Unraveling the structure of these incredibly complex molecules helps scientists understand how the enzymes operate in these biological processes.

    In a common application of X-ray methods, known as X-ray crystallography, scientists shoot X-rays at a crystalline sample and use the beam’s scattering patterns to produce a model of the compound’s structure. In one project the Ando group has termed “hacking crystallography,” Ando proposed that instead of collecting the X-ray scattering patterns in the experiment, they gather the background data, which can be an intricate and unruly set of data.

    Because the atoms in the sample are moving slightly, if the researchers can find a way to interpret this data, they could construct a molecular movie instead of a snapshot. The way enzymes change position reveals information about their function, as enzymes often must adopt specific conformations to carry out their jobs. Only 10 or so articles have been published around this challenging concept, but Ando said she hopes to create a “renaissance” in this area.

    Garnet Chan, the Hepburn Professor of Theoretical Chemistry at Princeton, said that with Ando’s unique application of X-ray techniques, she would be at the forefront of a new class of discoveries. “I see her contributing in a big way to the development of the department,” he said.

    2
    With X-ray crystallography, scientists typically model a compound’s structure by shooting a light beam at a crystalline sample of the compound and recording how the beams scatter. In one project, Ando proposed instead collecting the background data, which can be used to create a molecular movie instead of a snapshot. The X-ray image above is visualized as a topographical map that shows sharp diffraction peaks as well as weak, noisy signals, all of which form a comprehensive view of a compound’s structure. (Data visualization courtesy of Nozomi Ando, Department of Chemistry)

    Developing a laser focus

    Ando has always been very independent, said her father Teichii Ando, a professor of materials science at Northeastern University. He recounted how she became interested in singing as a teen, and sought out lessons on her own, paying with her earnings from tutoring. Ando’s passion for classical singing continued well into her graduate studies at Cornell University, and she even performed operatic arias during site visits from the National Science Foundation (NSF) to Cornell’s High Energy Synchrotron Source, where her Ph.D. adviser, Sol Gruner, was director.

    As a physics graduate student in Gruner’s lab, Ando became an expert on small-angle X-ray scattering (SAXS), a specialized technique for studying the structure of proteins in solution. The X-ray beams used in her experiments were generated by the Cornell synchrotron, which is a massive underground particle accelerator that shoots subatomic particles around a half-mile-long circular track at close to the speed of light. Attached to the ring are laboratory spaces crowded with computers, fumehoods for prepping samples and a large metal box where the beam enters the room. “It felt like walking through a spaceship,” Ando said.

    Because there are only five synchrotrons in the United States, researchers must apply for time at these Department of Energy or NSF-funded facilities. During the Ando lab’s first trip to Cornell’s synchrotron last October, they collected months’ worth of data over the course of four sleepless nights — and afterward emerged with their shared appreciation for Queen.

    3
    Ando works with chemistry major and rising senior Emily Adler to interpret scattering images from an experiment conducted on a synchrotron, which is a massive underground particle accelerator that shoots subatomic particles around a half-mile-long circular track at close to the speed of light.

    “It’s definitely a team effort to get everything done,” said Kate Davis, a postdoctoral researcher in the Ando lab. She described the lab environment as incredibly positive and non-judgmental, a particularly beneficial characteristic because the group members all come from different scientific backgrounds.

    “It’s an atmosphere where it’s OK to say ‘I don’t know,’ but then of course we apply ourselves to learning the answer,” said Buz Barstow, a Burroughs Wellcome Fund CASI Fellow at Princeton and Ando’s husband. His research is focused on engineering biological processes to store renewable energy. Barstow and Ando’s research teams work together closely and share scientific expertise at joint group meetings.

    To ensure the researchers develop a solid grasp on the fundamentals of the work, Ando and Barstow have rotating group members present chapters of a physical biochemistry textbook. “Being able to explain something simply is really important — it’s the ultimate indicator of understanding,” Ando said.

    Ando is herself a gifted communicator, colleagues said.

    “It’s rare to find someone who can hold a meaningful back-and-forth with biologists, biochemists and physicists,” said Ando’s postdoctoral adviser, Catherine Drennan, a professor of chemistry and biology at the Massachusetts Institute of Technology and the Howard Hughes Medical Institute. “It’s one of the things that makes her special.”

    4
    Rising junior and chemistry major Isao Anzai inoculates cultures in Ando’s laboratory. Since joining Princeton’s faculty in 2014, Ando has already attracted two postdoctoral researchers, a graduate student and five undergraduates with her ambitious research program.

    As a postdoctoral researcher, Ando brought her skills in small-angle X-ray scattering to a project that involved three lab groups. The goal was to elucidate the structure of ribonucleotide reductase (RNR), a key enzyme for DNA replication and repair, using a combination of strategies. The team had modeled possible structures using electron microscopy, crystallography and small-angle X-ray scattering techniques that didn’t make sense. They expected to see a ring structure but instead their model looked like a crazy lattice, Ando said.

    Drennan recalled how Ando gathered the whole team around the computer so that they could look at it as a group. Upon tweaking the color scheme, they realized that they were actually looking at not one ring, but two interlocking rings. In this ring configuration, RNR was essentially inactive and unable to participate in electron transfer. Their findings provided a vital connection between the enzyme’s conformation and activity, and were reported in the journal Proceedings of the National Academy of Sciences in 2011.

    Ando also is promoting scientific collaboration at Princeton. She has begun working with researchers in the laboratory of Mohammad Seyedsayamdost, an assistant professor of chemistry, who shares Ando’s interest in complex enzymes. “It was very clear from Nozomi’s interview that with her skill set she would be the focal point of many different collaborations,” Seyedsayamdost said.

    Ando brings people together even beyond the lab bench. When she coordinated the Drennan lab’s participation in the competitive departmental Halloween group costume contest at MIT, they won dressed as free radicals by donning Che Guevara-esque berets and T-shirts that Ando had designed with chemical structures of radical molecules.

    When preparing to start her assistant professorship at Princeton, Ando said she briefly pondered adopting a more conservative style, but decided against it. “Have I ever liked being conventional?” she said, reflecting on her personal and professional decisions. “No.”

    See the full article here.

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    Princeton University Campus

    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

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