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  • richardmitnick 8:44 am on May 13, 2015 Permalink | Reply
    Tags: , , Sandia Lab   

    From Sandia: “Starving cancer instead of feeding it poison” 


    Sandia Lab

    May 13, 2015
    Neal Singer
    nsinger@sandia.gov
    (505) 845-7078

    1
    Sandia National Laboratories researcher Susan Rempe says a new approach to treating cancer is being tested on laboratory mice. If successful, human testing will follow. (Photo by Randy Montoya)

    A patent application for a drug that could destroy the deadly childhood disease known as acute lymphoblastic leukemia — and potentially other cancers as well — has been submitted by researchers at Sandia National Laboratories, the University of Maryland and the MD Anderson Cancer Center in Houston.

    “Most drugs have to go inside a cell to kill it,” said Sandia researcher Susan Rempe. “Instead, our method withholds an essential nutrient from the cell, essentially starving it until it self-destructs.”

    The removed nutrient is called asparagine, which cancer cells can’t produce on their own. But there’s more to the story.

    It’s well-known that chemical attempts using drugs to kill cancers often sicken the patient. In the case of the cancer drug L-asparaginase type 2 (L-ASN2), whose primary effect is depleting asparagine, side effects are generally attributed to the corresponding depletion of a chemically similar molecule called glutamine. All human cells need asparagine and glutamine to survive because each is essential to key biological processes. While most normal cells can synthesize their own asparagine, certain cancer cells cannot. So the ideal nutrient-deprivation strategy for cancers requires a difficult balancing act: Remove enough asparagine from the blood to cripple the cancer, but leave enough glutamine that the patient can tolerate chemotherapy.

    The researchers at Sandia and the university did molecular computer simulations to predict what mutations would produce that desirable result when introduced into the enzyme-drug L-ASN2, commonly used to treat certain types of leukemia. The scientists’ simulations succeeded in identifying a point in that enzyme’s chain of amino acids where a mutation theoretically would eliminate the drug’s unwanted attack on glutamine.

    “Technically,” said Rempe, “we simulated which parts of the two molecules came in contact with the enzyme. Then we realized that by substituting a single amino acid in the enzyme’s chain, we might avoid glutamine degradation by removing it from contact with the enzyme.”

    In computer simulations, the change looked promising because the most notable difference between asparagine and glutamine was the way they interacted with that specific amino acid.

    “That made us feel that a chemical change at that single location was the key,” said Rempe.

    It required a mutation to change the amino acid’s chemistry. The mutation was achieved by collaborators at MD Anderson who used DNA substitutions to effect the change.

    “Most researchers agree that removing glutamine from a patient’s blood was the problem in previous use of this enzyme-drug,” said Rempe. “Our simulations, as it turned out, showed how to avoid that.”

    In test tube experiments, the new drug left glutamine untouched. Follow-up tests in petri dishes showed that the mutated enzyme killed a variety of cancers.

    Tests underway on laboratory mice at MD Anderson should be completed by early 2016, and if they are successful, Rempe said, human testing will follow.

    2
    A simulation by researchers at Sandia National Laboratories and the University of Maryland demonstrates that a mutated enzyme will degrade asparagine – food for some cancers — but leave glutamine, necessary for all proteins, untouched. (Graphic by Juan Vanegas)

    “If we’re wrong, and keeping glutamine intact is not the answer to the cancer problem, we’ll continue investigating because we think we’re onto something,” she said.

    That’s because, she said, “we used high-resolution computational methods to redesign the cancer drug to act differently, in this case to act only on asparagine. Laboratory tests showed that the predictions worked and that the new drug kills a variety of leukemias. We hope our method can do that in a patient, and for many more cancers. But if it doesn’t, then we’ll test the opposite strategy: redesign the enzyme to destroy glutamine and keep asparagine intact. Or fine-tune the enzyme to degrade the two molecules in a chosen ratio. We’re learning to control this enzyme.”

    The joint work among Sandia, the University of Maryland and MD Anderson began in 2009. Sandia managers Wahid Hermina and Steve Casalnuovo spearheaded the collaboration to use Sandia’s computational and biochemical expertise developed in national defense to help cure cancer.

    Sandia’s cancer-fighting research also can be applied to building enzymes that can assist with bio defense.

    Said Rempe, “If we could redesign an enzyme to break down specific small molecules, and not get diverted by interactions with non-toxic molecules, then we could apply our technique to develop safer and more effective enzymes.”

    Classical modeling was performed at the University of Maryland by Andriy Anishkin and Sergei Sukharev; at Sandia, post-doctoral researcher David Rogers (now at the University of South Florida) also carried out modeling studies. Sandia post-doctoral researcher Juan Vanegas is performing quantum modeling to map out the chemical degradation process to better understand how to optimize the enzyme, said Rempe. The experiments at MD Anderson were carried out by Wai Kin Chan, Phil Lorenzi, and colleagues in John Weinstein’s group. Earlier results have been published in the journal Blood.

    The work is supported by Sandia’s Laboratory Directed Research and Development office.

    See the full article here.

    Please help promote STEM in your local schools.

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    Sandia Campus
    Sandia National Laboratory

    Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
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  • richardmitnick 7:58 am on April 22, 2015 Permalink | Reply
    Tags: , , Sandia Lab   

    From Sandia: “Phonons, arise!” 


    Sandia Lab

    April 22, 2015
    Neal Singer, nsinger@sandia.gov, (505) 845-7078

    Small electric voltage alters conductivity in key materials

    1
    Sandia National Laboratories researchers Jon Ihlefeld, left, and David Scrymgeour use an atomic-force microscope to examine changes in a material’s phonon-scattering internal walls, before and after applying a voltage. The material scrutinized, PZT, has wide commercial uses.

    Modern research has found no simple, inexpensive way to alter a material’s thermal conductivity at room temperature.

    That lack of control has made it hard to create new classes of devices that use phonons — the agents of thermal conductivity — rather than electrons or photons to harvest energy or transmit information. Phonons — atomic vibrations that transport heat energy in solids at speeds up to the speed of sound — have proved hard to harness.

    Now, using only a 9-volt battery at room temperature, a team led by Sandia National Laboratories researcher Jon Ihlefeld has altered the thermal conductivity of the widely used material PZT (lead zirconate titanate) by as much as 11 percent at subsecond time scales. They did it without resorting to expensive surgeries like changing the material’s composition or forcing phase transitions to other states of matter.

    PZT, either as a ceramic or a thin film, is used in a wide range of devices ranging from computer hard drives, push-button sparkers for barbecue grills, speed-pass transponders at highway toll booths and many microelectromechanical designs.

    “We can alter PZT’s thermal conductivity over a broad temperature range, rather than only at the cryogenic temperatures achieved by other research groups,” said Ihlefeld. “And we can do it reversibly: When we release our voltage, the thermal conductivity returns to its original value.”

    The work was performed on materials with closely spaced internal interfaces — so-called domain walls — unavailable in earlier decades. The close spacing allows better control of phonon passage.

    “We showed that we can prepare crystalline materials with interfaces that can be altered with an electric field. Because these interfaces scatter phonons,” said Ihlefeld, “we can actively change a material’s thermal conductivity by simply changing their concentration. We feel this groundbreaking work will advance the field of phononics.”

    The researchers, supported by Sandia’s Laboratory Directed Research and Development office, the Air Force Office of Scientific Research, and the National Science Foundation, used a scanning electron microscope and an atomic force microscope. to observe how the domain walls of subsections of the material changed in length and shape under the influence of an electrical voltage. It is this change that controllably altered the transport of phonons within the material.

    “The real achievement in our work,” said Ihlefeld, “is that we’ve demonstrated a means to control the amount of heat passing through a material at room temperature by simply applying a voltage across it. We’ve shown that we can actively regulate how well heat — phonons — conducts through the material.”

    Ihlefeld points out that active control of electron and photon transport has led to technologies that are taken for granted today in computing, global communications and other fields.

    “Before the ability to control these particles and waves existed, it was probably difficult even to dream of technologies involving electronic computers and lasers. And prior to our demonstration of a solid-state, fast, room-temperature means to alter thermal conductivity, analogous means to control the transport of phonons have not existed. We believe that our result will enable new technologies where controlling phonons is necessary,” he said.

    The work, published last month in Nano Letters, was co-authored by Sandia researchers David A. Scrymgeour, Joseph R. Michael, Bonnie B. McKenzie and Douglas L. Medlin; Brian M. Foley and Patrick E. Hopkins from the University of Virginia; and Margeaux Wallace and Susan Trolier-McKinstry from Penn State University.

    The goal of future work is to reach a better understanding of “what caused this effect to happen so efficiently,” Ihlefeld said.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Sandia Campus
    Sandia National Laboratory

    Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
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  • richardmitnick 1:27 pm on March 18, 2015 Permalink | Reply
    Tags: , , , Sandia Lab   

    From Sandia: “Iron rain fell on early Earth, new Z machine data supports” 


    Sandia Lab

    March 18, 2015
    Neal Singer, nsinger@sandia.gov, (505) 845-7078

    Sandia Z machine
    Sandia National Laboratories Z machine is the most powerful producer of pulses of electrical energy on Earth. Thomas J. Gardner, Sandia Lab

    Researchers at Sandia National Laboratories’ Z machine have helped untangle a long-standing mystery of astrophysics: why iron is found spattered throughout Earth’s mantle, the roughly 2,000-mile thick region between Earth’s core and its crust.

    At first blush, it seemed more reasonable that iron arriving from collisions between Earth and planetesimals — ranging from several meters to hundreds of kilometers in diameter — during Earth’s late formative stages should have powered bullet-like directly to Earth’s core, where so much iron already exists.

    A second, correlative mystery is why the moon proportionately has much less iron in its mantle than does Earth. Since the moon would have undergone the same extraterrestrial bombardment as its larger neighbor, what could explain the relative absence of that element in the moon’s own mantle?

    To answer these questions, scientists led by Professor Stein Jacobsen at Harvard University and Professor Sarah Stewart at the University of California at Davis (UC Davis) wondered whether the accepted theoretical value of the vaporization point of iron under high pressures was correct. If vaporization occurred at lower pressures than assumed, a solid piece of iron after impact might disperse into an iron vapor that would blanket the forming Earth instead of punching through it. A resultant iron-rich rain would create the pockets of the element currently found in the mantle.

    As for the moon, the same dissolution of iron into vapor could occur, but the satellite’s weaker gravity would be unable to capture the bulk of the free-floating iron atoms, explaining the dearth of iron deposits on Earth’s nearest neighbor.

    Looking for experimental rather than theoretical values, researchers turned to Sandia’s Z machine and its Fundamental Science Program, coordinated by Sandia manager Thomas Mattsson. This led to a collaboration among Sandia, Harvard University, UC Davis, and Lawrence Livermore National Laboratory (LLNL) to determine an experimental value for the vaporization threshold of iron that would replace the theoretical value used for decades.

    Rick Kraus at LLNL (formerly at Harvard) and Sandia researchers Ray Lemke and Seth Root used Z to accelerate metals to extreme speeds using high magnetic fields. The researchers created a target that consisted of an iron plate 5 millimeters square and 200 microns thick, against which they launched aluminum flyer plates travelling up to 25 kilometers per second. At this impact pressure, the powerful shock waves created in the iron cause it to compress, heat up and — in the zero pressure resulting from waves reflecting from the iron’s far surface — vaporize.

    The result, published March 2 in Nature Geosciences under the title Impact vaporization of planetesimal cores in the late stages of planet formation, shows the shock pressure experimentally required to vaporize iron is approximately 507 gigapascals (GPa), undercutting by more than 40 percent the previous theoretical estimate of 887 GPa. Astrophysicists say that this lower pressure is readily achieved during the end stages of planetary growth through accretion.

    Principal investigator Kraus said, “Because planetary scientists always thought it was difficult to vaporize iron, they never thought of vaporization as an important process during the formation of the Earth and its core. But with our experiments, we showed that it’s very easy to impact-vaporize iron.”

    He continued, “This changes the way we think of planet formation, in that instead of core formation occurring by iron sinking down to the growing Earth’s core in large blobs (technically called diapirs), that iron was vaporized, spread out in a plume over the surface of the Earth and rained out as small droplets. The small iron droplets mixed easily with the mantle, which changes our interpretation of the geochemical data we use to date the timing of Earth’s core formation.”

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Sandia Campus
    Sandia National Laboratory

    Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
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  • richardmitnick 6:51 pm on January 20, 2015 Permalink | Reply
    Tags: , , , Sandia Lab   

    From isgtw and Sandia Lab: “8 Mind-Blowing Scientific Research Machines” 

    ISGTW

    Sandia Lab

    Scientific innovation and discovery are defining characteristics of humanity’s innate curiosity. Mankind has developed advanced scientific research machines to help us better understand the universe. They constitute some of the greatest human endeavors for the sake of technological and scientific progress. These projects also connect people of many nations and cultures, and inspire future generations of engineers and scientists.

    Apart from the last two experiments that are under construction, the images in this article are not fake or altered; they are real and showcase machines on the frontier of scientific innovation and discovery. Read on to learn more about the machines, what the images show, and how NI technology helps make them possible.

    1
    Borexino, a solar neutrino experiment, recently confirmed the energy output of the sun has not changed in 100,000 years. Its large underground spherical detector contains 2,000 soccer-ball-sized photomultiplier tubes.

    Borexino and DarkSide

    Gran Sasso National Laboratory, Assergi, Italy

    2
    PMTs are contained inside the Liquid Scintillator Veto spherical tank, a component of the DarkSide Experiment used to actively suppress background events from radiogenic and cosmogenic neutrons.

    Borexino and DarkSide are located 1.4 km (0.87 miles) below the earth’s surface in the word’s largest underground laboratory for experiments in particle astrophysics. Only a tiny fraction of the contents of the universe is visible matter, the rest is thought to be composed of dark matter and dark energy. A leading hypothesis for dark matter is that it comprises Weakly Interacting Massive Particles (WIMPs). The DarkSide experiment attempts to detect these particles to better understand the nature of dark matter and its interactions.

    These experiments use NI oscilloscopes to acquire electrical signals resulting from scintillation light captured by the photomultiplier tubes (PMTs). In DarkSide, 200 high-speed, high-resolution channels need to be tightly synchronized to make time-of-flight measurements of photons. Watch the NIWeek 2013 keynote or view a technical presentation for more information.

    Joint European Torus (JET)

    Culham Centre for Fusion Energy (CCFE), Oxfordshire, United Kingdom

    5
    Plasma is contained and heated in a torus within the interior of the JET tokamak.

    Currently the largest experimental tokamak fusion reactor in the world, JET uses magnetic confinement to contain plasma at around 100 million degrees Celsius, nearly seven times the temperature of the sun’s core (15 million degrees Celsius). Nuclear fusion is the process that powers the sun. Harnessing this type of energy can help solve the world’s growing energy demand. This facility is crucial to the research and development for future larger fusion reactors.

    Large Hadron Collider (LHC)
    CERN, Geneva, Switzerland

    a

    The A Toroidal LHC ApparatuS (ATLAS) is LHC’s largest particle detector involved in the recent discovery of the Higgs boson.

    The LHC is the largest and most powerful particle accelerator in the world, located in a 27 km (16.78 mile) ring tunnel underneath Switzerland and France. The experiment recently discovered the Higgs boson, deemed the “God Particle” that gives everything its mass. CERN is set to reopen the upgraded LHC in early 2015 at much higher energies to help physicists probe deeper into the nature of the universe and address the questions of supersymmetry and dark matter.

    National Ignition Facility (NIF)
    Lawrence Livermore National Laboratory (LLNL), California, USA

    7

    The image looks up into NIF’s 10 m (33 ft) diameter spherical target chamber with the target held on the protruding pencil-shaped arm.

    NIF is the largest inertial confinement fusion device in the world. The experiment converges the beams of 192 high-energy lasers on a single fuel-filled target, producing a 500 TW flash of light to trigger nuclear fusion. The aim of this experiment is to produce a condition known as ignition, in which the fusion reaction becomes self-sustaining. The machine was also used as the set for the warp drive in the latest Star Trek movie.

    Z Machine
    Sandia National Laboratories, Albuquerque, New Mexico, USA

    8

    The Z Machine creates residual lightning as it releases 350 TW of stored energy.

    The world’s largest X-ray generator is used for various high-pulsed power experiments requiring extreme temperatures and pressures. This includes inertial confinement fusion research. The extremely high voltages are achieved by rapidly discharging huge capacitors in a large insulated bath of oil and water onto a central target.

    European Extremely Large Telescope (E-ELT)

    European Southern Observatory (ESO), Cerro Armazones, Chile

    8

    This artist’s rendition of the E-ELT shows it at its high-altitude Atacama Desert site.

    The E-ELT is the largest optical/near-infrared ground-based telescope being built by ESO in northern Chile. It will allow astronomers to probe deep into space and investigate many unanswered questions about the universe. Images from E-ELT will be 16 times sharper than those from the Hubble Space Telescope, allowing astronomers to study the creation and atmospheres of extrasolar planets. The primary M1 mirror (shown in the image) is nearly 40 m (131 ft) in diameter, consisting of about 800 hexagonal segments.

    NASA Hubble Telescope
    Hubble

    International Thermonuclear Experimental Reactor (ITER)
    ITER Organization, Cadarache, France

    9

    This cutaway computer model shows ITER with plasma at its core. A technician is shown to demonstrate the machine’s size.

    ITER is an international effort to build the largest experimental fusion tokamak in the world, a critical step toward future fusion power plants. The European Union, India, Japan, China, Russia, South Korea, and United States are collaborating on the project, which is currently under construction in southern France.

     
  • richardmitnick 3:24 pm on July 21, 2014 Permalink | Reply
    Tags: , , , , Sandia Lab   

    From DOE Pulse: “Diamond plates create nanostructures through pressure, not chemistry “ 

    pulse

    July 21, 2014
    Darrick Hurst, 505.844.8009,
    drhurst@sandia.gov

    You wouldn’t think that mechanical force — the simple kind used to eject unruly patrons from bars, shoe a horse or emboss the raised numerals on credit cards — could process nanoparticles more subtly than the most advanced chemistry.

    Yet, in a recent paper in Nature Communications, Sandia National Laboratories researcher Hongyou Fan and colleagues appear to have achieved a start toward that end.

    three
    Sandia National Laboratories researcher Hongyou Fan, center, points out a nanoscience result to Sandia paper co-authors Paul Clem, left, and Binsong Li.
    (Photo by Randy Montoya)

    Their newly patented and original method uses simple pressure — a kind of high-tech embossing — to produce finer and cleaner results in forming silver nanostructures than do chemical methods, which are not only inflexible in their results but leave harmful byproducts to dispose of.

    Fan calls his approach “a simple stress-based fabrication method” that, when applied to nanoparticle arrays, forms new nanostructures with tunable properties.

    “There is a great potential market for this technology,” he said. “It can be readily and directly integrated into current industrial manufacturing lines without creating new expensive and specialized equipment.”

    Said Sandia co-author Paul Clem, “This is a foundational method that should enable a variety of devices, including flexible electronics such as antennas, chemical sensors and strain detectors.” It also would produce transparent electrodes for solar cells and organic light-emitting diodes, Clem said.

    The method was inspired by industrial embossing processes in which a patterned mask is applied with high external pressure to create patterns in the substrate, Fan said. “In our technology, two diamond anvils were used to sandwich nanoparticulate thin films. This external stress manually induced transitions in the film that synthesized new materials,” he said.

    The pressure, delivered by two diamond plates tightened by four screws to any controlled setting, shepherds silver nanospheres into any desired volume. Propinquity creates conditions that produce nanorods, nanowires and nanosheets at chosen thicknesses and lengths rather than the one-size-fits-all output of a chemical process, with no environmentally harmful residues.

    While experiments reported in the paper were performed with silver — the most desirable metal because it is the most conductive, stable and optically interesting and becomes transparent at certain pressures — the method also has been shown to work with gold, platinum and other metallic nanoparticles

    Clem said the researchers are now starting to work with semiconductors.

    Bill Hammetter, manager of Sandia’s Advanced Materials Laboratory, said, “Hongyou has discovered a way to build one structure into another structure — a capability we don’t have now at the nanolevel. Eight or nine gigapascal —the amount of pressure at which phase change and new materials occur — are not difficult to reach. Any industry that has embossing equipment could lay a film of silver on a piece of paper, build a conductive pattern, then remove the extraneous material and be left with the pattern. A coating of nanoparticles that can build into another structure has a certain functionality we don’t have right now. It’s a discovery that hasn’t been commercialized, but could be done today with the same equipment used by anyone who makes credit cards.”

    The method can be used to configure new types of materials. For example, under pressure, the dimensions of ordered three-dimensional nanoparticle arrays shrink. By fabricating a structure in which the sandwiching walls permanently provide that pressure, the nanoparticle array will remain at a constant state, able to transmit light and electricity with specific characteristics. This pressure-regulated fine-tuning of particle separation enables controlled investigation of distance-dependent optical and electrical phenomena.

    At even higher pressures, nanoparticles are forced to sinter, or bond, forming new classes of chemically and mechanically stable nanostructures that no longer need restraining surfaces. These cannot be manufactured using current chemical methods.

    Depending on the size, composition and phase orientation of the initial nanoparticle arrays, a variety of nanostructures or nanocomposites and 3-D interconnected networks are achievable.

    The stress-induced synthesis processes are simple and clean. No thermal processing or further purification is needed to remove reaction byproducts.
    This work was funded by the Department of Energy’s Office of Science. Other authors of the paper are from Cornell University and Los Alamos National Laboratory.

    See the full article here.

    DOE Pulse highlights work being done at the Department of Energy’s national laboratories. DOE’s laboratories house world-class facilities where more than 30,000 scientists and engineers perform cutting-edge research spanning DOE’s science, energy, National security and environmental quality missions. DOE Pulse is distributed twice each month.

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  • richardmitnick 1:14 pm on June 27, 2014 Permalink | Reply
    Tags: , , Sandia Lab   

    From Sandia Lab: “Diamond plates create nanostructures through pressure, not chemistry” 


    Sandia Lab

    You wouldn’t think that mechanical force — the simple kind used to eject unruly patrons from bars, shoe a horse or emboss the raised numerals on credit cards — could process nanoparticles more subtly than the most advanced chemistry.

    hf
    Sandia National Laboratories researcher Hongyou Fan, center, points out a nanoscience result to Sandia paper co-authors Paul Clem, left, and Binsong Li. (Photo by Randy Montoya)

    Yet, in a recent paper in Nature Communications, Sandia National Laboratories researcher Hongyou Fan and colleagues appear to have achieved a start toward that end.

    Their newly patented and original method uses simple pressure — a kind of high-tech embossing — to produce finer and cleaner results in forming silver nanostructures than do chemical methods, which are not only inflexible in their results but leave harmful byproducts to dispose of.

    Fan calls his approach “a simple stress-based fabrication method” that, when applied to nanoparticle arrays, forms new nanostructures with tunable properties.

    “There is a great potential market for this technology,” he said. “It can be readily and directly integrated into current industrial manufacturing lines without creating new expensive and specialized equipment.”

    Said Sandia co-author Paul Clem, “This is a foundational method that should enable a variety of devices, including flexible electronics such as antennas, chemical sensors and strain detectors.” It also would produce transparent electrodes for solar cells and organic light-emitting diodes, Clem said.

    The method was inspired by industrial embossing processes in which a patterned mask is applied with high external pressure to create patterns in the substrate, Fan said. “In our technology, two diamond anvils were used to sandwich nanoparticulate thin films. This external stress manually induced transitions in the film that synthesized new materials,” he said.

    The pressure, delivered by two diamond plates tightened by four screws to any controlled setting, shepherds silver nanospheres into any desired volume. Propinquity creates conditions that produce nanorods, nanowires and nanosheets at chosen thicknesses and lengths rather than the one-size-fits-all output of a chemical process, with no environmentally harmful residues.

    While experiments reported in the paper were performed with silver — the most desirable metal because it is the most conductive, stable and optically interesting and becomes transparent at certain pressures — the method also has been shown to work with gold, platinum and other metallic nanoparticles

    Clem said the researchers are now starting to work with semiconductors.

    Bill Hammetter, manager of Sandia’s Advanced Materials Laboratory, said, “Hongyou has discovered a way to build one structure into another structure — a capability we don’t have now at the nanolevel. Eight or nine gigapascal —the amount of pressure at which phase change and new materials occur — are not difficult to reach. Any industry that has embossing equipment could lay a film of silver on a piece of paper, build a conductive pattern, then remove the extraneous material and be left with the pattern. A coating of nanoparticles that can build into another structure has a certain functionality we don’t have right now. It’s a discovery that hasn’t been commercialized, but could be done today with the same equipment used by anyone who makes credit cards.”

    The method can be used to configure new types of materials. For example, under pressure, the dimensions of ordered three-dimensional nanoparticle arrays shrink. By fabricating a structure in which the sandwiching walls permanently provide that pressure, the nanoparticle array will remain at a constant state, able to transmit light and electricity with specific characteristics. This pressure-regulated fine-tuning of particle separation enables controlled investigation of distance-dependent optical and electrical phenomena.

    At even higher pressures, nanoparticles are forced to sinter, or bond, forming new classes of chemically and mechanically stable nanostructures that no longer need restraining surfaces. These cannot be manufactured using current chemical methods.

    Depending on the size, composition and phase orientation of the initial nanoparticle arrays, a variety of nanostructures or nanocomposites and 3-D interconnected networks are achievable.

    The stress-induced synthesis processes are simple and clean. No thermal processing or further purification is needed to remove reaction byproducts.

    This work was funded by the Department of Energy’s Office of Science. Other authors of the paper are from Cornell University and Los Alamos National Laboratory.

    See the full article here.

    Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
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  • richardmitnick 10:35 am on June 17, 2014 Permalink | Reply
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    From Sandia Lab: “Novel nanoparticle production method could lead to better lights, lenses, solar cells” 


    Sandia Lab

    June 17, 2014
    Sue Holmes, sholmes@sandia.gov, (505) 844-6362

    Sandia National Laboratories has come up with an inexpensive way to synthesize titanium-dioxide nanoparticles and is seeking partners who can demonstrate the process at industrial scale for everything from solar cells to light-emitting diodes (LEDs).

    Titanium-dioxide (TiO2) nanoparticles show great promise as fillers to tune the refractive index of anti-reflective coatings on signs and optical encapsulants for LEDs, solar cells and other optical devices. Optical encapsulants are coverings or coatings, usually made of silicone, that protect a device.

    Industry has largely shunned TiO2 nanoparticles because they’ve been difficult and expensive to make, and current methods produce particles that are too large.

    Sandia became interested in TiO2 for optical encapsulants because of its work on LED materials for solid-state lighting.

    two
    Sandia National Laboratories researchers Dale Huber, left, and Todd Monson have come up with an inexpensive way to synthesize titanium-dioxide nanoparticles, which could be used in everything from solar cells to light-emitting diodes. (Photo by Randy Montoya) Click on the thumbnail for a high-resolution image.

    Current production methods for TiO2 often require high-temperature processing or costly surfactants — molecules that bind to something to make it soluble in another material, like dish soap does with fat.

    Those methods produce less-than-ideal nanoparticles that are very expensive, can vary widely in size and show significant particle clumping, called agglomeration.

    Sandia’s technique, on the other hand, uses readily available, low-cost materials and results in nanoparticles that are small, roughly uniform in size and don’t clump.

    “We wanted something that was low cost and scalable, and that made particles that were very small,” said researcher Todd Monson, who along with principal investigator Dale Huber patented the process in mid-2011 as “High-yield synthesis of brookite TiO2 nanoparticles.”

    Low-cost technique produces uniform nanoparticles that don’t clump

    Their method produces nanoparticles roughly 5 nanometers in diameter, approximately 100 times smaller than the wavelength of visible light, so there’s little light scattering, Monson said.

    “That’s the advantage of nanoparticles — not just nanoparticles, but small nanoparticles,” he said.

    Scattering decreases the amount of light transmission. Less scattering also can help extract more light, in the case of an LED, or capture more light, in the case of a solar cell.

    TiO2 can increase the refractive index of materials, such as silicone in lenses or optical encapsulants. Refractive index is the ability of material to bend light. Eyeglass lenses, for example, have a high refractive index.

    Practical nanoparticles must be able to handle different surfactants so they’re soluble in a wide range of solvents. Different applications require different solvents for processing.

    Technique can be used with different solvents

    “If someone wants to use TiO2 nanoparticles in a range of different polymers and applications, it’s convenient to have your particles be suspension-stable in a wide range of solvents as well,” Monson said. “Some biological applications may require stability in aqueous-based solvents, so it could be very useful to have surfactants available that can make the particles stable in water.”

    The researchers came up with their synthesis technique by pooling their backgrounds — Huber’s expertise in nanoparticle synthesis and polymer chemistry and Monson’s knowledge of materials physics. The work was done under a Laboratory Directed Research and Development project Huber began in 2005.

    “The original project goals were to investigate the basic science of nanoparticle dispersions, but when this synthesis was developed near the end of the project, the commercial applications were obvious,” Huber said. The researchers subsequently refined the process to make particles easier to manufacture.

    Existing synthesis methods for TiO2 particles were too costly and difficult to scale up production. In addition, chemical suppliers ship titanium-dioxide nanoparticles dried and without surfactants, so particles clump together and are impossible to break up. “Then you no longer have the properties you want,” Monson said.

    The researchers tried various types of alcohol as an inexpensive solvent to see if they could get a common titanium source, titanium isopropoxide, to react with water and alcohol.

    The biggest challenge, Monson said, was figuring out how to control the reaction, since adding water to titanium isopropoxide most often results in a fast reaction that produces large chunks of TiO2, rather than nanoparticles. “So the trick was to control the reaction by controlling the addition of water to that reaction,” he said.

    Textbooks said making nanoparticles couldn’t be done, Sandia persisted

    Some textbooks dismissed the titanium isopropoxide-water-alcohol method as a way of making TiO2 nanoparticles. Huber and Monson, however, persisted until they discovered how to add water very slowly by putting it into a dilute solution of alcohol. “As we tweaked the synthesis conditions, we were able to synthesize nanoparticles,” Monson said.

    The next step is to demonstrate synthesis at an industrial scale, which will require a commercial partner. Monson, who presented the work at Sandia’s fall Science and Technology Showcase, said Sandia has received inquiries from companies interested in commercializing the technology.

    “Here at Sandia we’re not set up to produce the particles on a commercial scale,” he said. “We want them to pick it up and run with it and start producing these on a wide enough scale to sell to the end user.”

    Sandia would synthesize a small number of particles, then work with a partner company to form composites and evaluate them to see if they can be used as better encapsulants for LEDs, flexible high-index refraction composites for lenses or solar concentrators. “I think it can meet quite a few needs,” Monson said.

    See the full article here.

    Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.


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