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  • richardmitnick 12:24 pm on November 30, 2015 Permalink | Reply
    Tags: , Intermediate Energy X-ray (IEX) beamline, X-ray Technology   

    From APS at ANL: “Novel intermediate energy X-ray beamline opening for researchers” 

    News APS at Argonne National Laboratory

    November 20, 2015
    John Spizzirri

    Researchers working to create next-generation electronic systems and to understand the fundamental properties of magnetism and electronics to tackle grand challenges such as quantum computing have a new cutting-edge tool in their arsenal. The Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility located at Argonne National Laboratory, recently unveiled a new capability: the Intermediate Energy X-ray (IEX) beamline at sector 29.

    Intermediate Energy X-ray (IEX) beamline at sector 29

    Using relatively low-energy X-rays, the IEX beamline at the APS will help illuminate electronic ordering and emergent phenomena in ordered materials to better understand the origins of distinct electronic properties. Another important feature for users is a greater ability to adjust X-ray parameters to meet experimental needs.

    Currently in commissioning phase, the IEX beamline begins its first user runs in January 2016. With its state-of-the-art electromagnetic insertion device, highly adaptive X-ray optics, and compatible endstation techniques for X-ray photoelectron spectroscopy and scattering, it opens a new era for X-ray research in sciences ranging from condensed matter physics and materials science to molecular chemistry.

    “The nice thing about having both spectroscopy and scattering techniques available here is that there are different communities addressing the same science questions with different approaches,” said Jessica McChesney, an assistant physicist and beamline scientist at the APS who is responsible for operating the beamline and starting the user program. “We hope people will actually work together and talk to each other, and drive the science that way.”

    “The idea is, we’re going to look at electronic order in materials that may one day end up in your cell phone, either as battery materials, interconnects, or in the logic,” McChesney added. “Possibly one day, when we have spintronic devices, the materials may be something we studied here.”

    Conventional electronics use current, or the flow of electrons, while spintronics relies on the flow of the electrons’ spins, not just their charges. Other materials that can be studied at the IEX beamline include high-temperature superconductors, magnetic materials, and polymer self-assemblies.

    The new beamline was built to meet the specific requirements of its two shared scientific endstations that offer users varied but complementary techniques. Using Einstein’s discovery of the photoelectric effect, the angle-resolved photoemission spectroscopy (ARPES) endstation measures the energy and angle of emitted electrons and, by using conservation of energy and momentum, can reveal what the properties of these photoemitted electrons were before they left the material. The resonant soft X-ray scattering (RSXS) uses resonance, the tuning of the X-ray beam to a specific electronic excitation, to scatter off of an ordered electronic state to determine electron density.

    “So there was this freak convergence of a lot of different things: the right combination of science, geography, and technology all at the same time.”

    How it all started

    Like the formation of a new particle in a collider, it was the research trajectory of two scientists that forged the foundations for IEX beamline. Physicists Juan Carlos Campuzano of the University of Illinois at Chicago (UIC) and Peter Abbamonte of the University of Illinois in Urbana Champaign (UIUC) both studied the complicated dynamics of high-temperature superconducting materials.

    By 1985, Campuzano had already proposed a similar, but less advanced, beamline at the Swiss Light Source, in Villingen, Switzerland, while Abbamonte, as a postdoc, had been on the team that pioneered the RSXS endstation, at Brookhaven National Laboratory in Upton, NY. Eventually, both took jobs within the University of Illinois system and were seeking an intermediate energy X-ray source in the Midwest to conduct their research.

    Given the challenges presented by these superconducting materials, they decided a better, brighter beamline was in order. They wrote a proposal that garnered funding from the National Science Foundation (NSF), which suggested they build the instrument at the newly established APS at Argonne, where Campuzano held a joint appointment.

    They reached out to APS beamline scientist George Srajer, now deputy associate laboratory director for Photon Sciences, to forge a partnership with DOE to fine-tune the concept and secure the remaining funding. A beamline was born.

    “So there was this freak convergence of a lot of different things: the right combination of science, geography, and technology all at the same time,” said Abbamonte, now professor of physics at UIUC.

    “There is no other like it in the world.”

    Making the beamline unique

    With several similar beamlines in Japan and Europe already operating, the toughest challenge in requesting funds for and building the new IEX beamline at the APS was to create something unique, noted Campuzano.

    “And it doesn’t seem like a big deal, but deciding what not to do was very important,” added Abbamonte. “You build a $15 million machine and people want to make it do everything. But that ends up costing more and the experiment that is supposed to do everything ends up doing nothing, because the more versatile an instrument is the more difficult it is to make it work. So we decided to focus and pick a few really important things.”

    A key feature unique to IEX at the APS is the beamline’s insertion device (ID), the magnetic system responsible for shaping the properties of X-rays provided to the beamline.

    According to Srajer, there is no other like it in the world.

    The ID is an electromagnetic variable polarizing undulator (EMVPU), operating in a range of 250 to 2,500 electron volts (eV). Like a fixed magnet device, users can change the energy of the X-rays and polarization at the sample. But the new ID also allows the source to run in quasi-periodic mode, which suppresses the higher harmonics in the X-ray beamline, resulting in a much higher signal-to-noise ratio that is ideal for detecting small signals in a large background.

    One advantage to developing a lower-energy beamline at a high-energy storage ring is that the intensity produced by the undulator is rather flat across the whole 250- to 2500-eV energy range. This minimizes the need for normalization, unlike at lower-energy storage rings where users must switch between the different undulator harmonics.

    To accurately deliver the X-rays produced by the ID to the endstations required the complicated design and manufacturing of X-ray optics that precisely adjust X-ray parameters, such as focus, energy resolution, and coherence fraction. Users can further tailor the X-ray beam for a given experiment by selecting between one of three gratings in the monochromator, optimizing the total intensity or flux (109–1012 photons per second) and energy resolution (5–300 milli-electron volts [meV]).

    A means to the end(stations)

    Superconductors with transition temperatures above the temperature of liquid nitrogen hold the promise of practical applications, such as the efficient production and transport of electricity. However, how those moderate- to high-temperature superconductors function is not well understood.

    When Campuzano and Abbamonte joined forces to develop the IEX beamline, their shared interest in high-temperature superconductivity became the focal point for the design of its two scientific endstations. Years of collective work in photoemission spectroscopy and X-ray scattering, respectively, would culminate in a powerful combination of tools located in one place.

    Campuzano was already using ultraviolet ARPES and was considered one of the leading experts in the field when he set his sights to building a new APS beamline.

    “We already knew that low-energy photons released electrons mostly from the surface of a material, which is not necessarily representative of what’s going on inside it,” said Campuzano. “The way to get around that was to build a beamline that had much higher-energy photons, soft X-rays.”

    The IEX ARPES experimental station, designed and built by Campuzano’s team at UIC, uses photons in a relatively high-energy range of 1000 eV to probe electrons deeper within a solid. As electrons absorb incoming photons, they are ejected from the structure. This lets users better analyze the dynamics of electron, the electronic excitations, in a sample.

    By understanding what happens to the electronic structure when macroscopic properties are changed, scientists get a better idea of how they can manipulate those properties to their advantage, whether it’s finding the best remnant magnetic fields for spintronics or determining transition temperatures in superconductors.

    Where ARPES lets researchers know how electrons propagate in a material, the RSXS endstation lets them know where those electrons are located. Designed and built by Abbamonte’s team at UIUC, resonant soft X-ray scattering is a photon-in-photon-out technique that yields real-space information about electronic ordering and information about correlation lengths.

    For Abbamonte, the technique is central to his research in determining whether heterogeneity is relevant for optimizing superconductivity.

    “Set the beam energies to the right resonance value, and when the photons hit the sample, they’ll scatter in all different directions because of this heterogeneity that we’re interested in,” he explained. “Then you use an angle-resolving detector to scan and measure the angle dependence of the light to back out what the form of that heterogeneity is.”

    In addition to the traditional microchannel plate angle-resolving detector, the RSXS endstation is equipped with a two-dimensional energy-resolving detector, another of the highly unique applications on this beamline. Considered among the most sensitive energy-resolving detectors in the world, it is based on transition-edge sensor (TES) technology pioneered by the National Institute of Standards and Technology (NIST) for cosmology applications, such as research in cosmic microwave background radiation.

    This is the first time TES technology has been used for scattering, and could prove 1000 times more sensitive to heterogeneity than any previous technology.

    The development of IEX was jointly funded by DOE and NSF.

    See the full article here .

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  • richardmitnick 1:20 pm on November 24, 2015 Permalink | Reply
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    From MIT: “A new way to make X-rays” 

    MIT News

    November 23, 2015
    David L. Chandler

    MIT researchers have found a phenomenon that might lead to more compact, tunable X-ray devices made of graphene.

    By using plasmons to “wiggle” a free electron in a sheet of graphene, researchers have developed a new method for generating X-rays. In this image of one of their simulations, the color and height represent the intensity of radiation (with blue the lowest intensity and red the highest), at a moment in time just after an electron (grey sphere) moving close to the surface generates a pulse. Courtesy of the researchers

    The most widely used technology for producing X-rays – used in everything from medical and dental imaging, to testing for cracks in industrial materials – has remained essentially the same for more than a century. But based on a new analysis by researchers at MIT, that might potentially change in the next few years.

    The finding, based on a new theory backed by exact simulations, shows that a sheet of graphene – a two-dimensional form of pure carbon – could be used to generate surface waves called plasmons when the sheet is struck by photons from a laser beam. These plasmons in turn could be triggered to generate a sharp pulse of radiation, tuned to wavelengths anywhere from infrared light to X-rays.

    What’s more, the radiation produced by the system would be of a uniform wavelength and tightly aligned, similar to that from a laser beam. The team says this could potentially enable lower-dose X-ray systems in the future, making them safer. The new work is reported this week in the journal Nature Photonics, in a paper by MIT professors Marin Soljačić and John Joannopoulos and postdocs Ido Kaminer, Liang Jie Wong (now at the Singapore Institute of Manufacturing Technology), and Ognjen Ilic.

    Soljačić says that there is growing interest in finding new ways of generating sources of light, especially at scales that could be incorporated into microchips or that could reduce the size and cost of the high-intensity beams used for basic scientific and biomedical research. Of all the wavelengths of electromagnetic radiation commonly used for applications, he says, “coherent X-rays are particularly hard to create.” They also have the highest energy. The new system could, in principle, create ultraviolet light sources on a chip and table-top X-ray devices that could produce the sorts of beams that now require huge, multimillion-dollar particle accelerators.

    To make focused, high-power X-ray beams, “the usual approach is to create high-energy charged particles [using an accelerator] and ‘wiggle’ them,” says Kaminer. “The oscillations will produce X-rays. But that approach is very expensive,” and the few facilities available nationwide that can produce such beams are highly oversubscribed. “The dream of the community is to make them small and inexpensive,” he says.

    Most sources of X-rays rely on extremely high-energy electrons, which are hard to produce. But the new method gets around that, using the tightly-confined power of the wave-like plasmons that are produced when a specially patterned sheet of graphene gets hit by photons from a laser beam. These plasmons can then release their energy in a tight beam of X-rays when triggered by a pulse from a conventional electron gun similar to those found in electron microscopes.

    “The reason this is unique is that we’re substantially bypassing the problem of accelerating the electrons,” he says. “Every other approach involves accelerating the electrons. This is unique in producing X-rays from low-energy electrons.”

    In addition, the system would be unique in its tunability, able to deliver beams of single-wavelength light all the way from infrared, through visible light and ultraviolet, on into X-rays. And there are three different inputs that can be used to control the tuning of the output, Kaminer explains – the frequency of the laser beam to initiate the plasmons, the energy of the triggering electron beam, and the “doping” of the graphene sheet.

    Such beams could have applications in crystallography, the team says, which is used in many scientific fields to determine the precise atomic structure of molecules. Because of its tight, narrow beam, the system might also allow more precise pinpointing of medical and dental X-rays, thus potentially reducing the radiation dose received by a patient, they say.

    So far, the work is theoretical, based on precise simulations, but the group’s simulations in the past have tended to match quite well with experimental results, Soljačić says. “We have the ability in our field to model these phenomena very exactly.”

    They are now in the process of building a device to test the system in the lab, starting initially with producing ultraviolet sources and working up to the higher-energy X-rays. “We hope to have solid confirmation of the principles within a year, and X-rays, if that goes well, optimistically within three years,” Soljačić says.

    But as with any drastically new technology, he acknowledges, the devil is in the details, and unexpected issues could crop up. So his estimate of when a practical X-ray device could emerge from this, he says with a smile, is “from three years, to never.”

    Hrvoje Buljan, a professor of physics at the University of Zagreb in Croatia, who was not involved in this study, says the work provides “a significant new approach to produce X-ray radiation.” He adds, “The experimental implementation still needs to be performed. Based on the proposal, all of the ingredients for the proof of principle experiments are there, and such experiments will be feasible.”

    The work was supported by the U.S. Army Research Laboratory and the U.S. Army Research Office, through the Institute for Soldier Nanotechnologies, by the Science and Engineering Research Council, A*STAR, Singapore, and by the European Research Council Marie Curie IOF grant.

    See the full article here .

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  • richardmitnick 8:11 am on November 17, 2015 Permalink | Reply
    Tags: , , X-ray Technology   

    From SLAC: “X-ray Microscope Reveals ‘Solitons,’ a Special Type of Magnetic Wave” 

    SLAC Lab

    November 16, 2015

    Scientists Hope to Control its Properties to Create a New Form of Electronics

    X-rays at SSRL (purple) measure a special type of magnetic wave, called a spin wave soliton, that has the ability to hold its shape as it moves across a magnetic material. The arrows, like reorienting compass needles, represent localized changes in the material’s magnetic orientation. (SLAC National Accelerator Laboratory)

    Researchers used a powerful, custom-built X-ray microscope at the Department of Energy’s SLAC National Accelerator Laboratory to directly observe the magnetic version of a soliton, a type of wave that can travel without resistance. Scientists are exploring whether such magnetic waves can be used to carry and store information in a new, more efficient form of computer memory that requires less energy and generates less heat.

    Magnetic solitons are remarkably stable and hold their shape and strength as they travel across a magnetic material, just as tsunamis maintain their strength and form while traversing the ocean. This offers an advantage over materials used in modern electronics, which require more energy to move data due to resistance, which causes them to heat up.

    In experiments at SLAC’s Stanford Synchrotron Radiation Lightsource [SSRL] , a DOE Office of Science User Facility, researchers captured the first X-ray images of solitons and a mini-movie of solitons that were generated by hitting a magnetic material with electric current to excite rippling magnetic effects. Results from two independent experiments were published Nov. 16 in Nature Communications and Sept. 17 in Physical Review Letters.

    SLAC SSRL Tunnel

    “Magnetism has been used for navigation for thousands of years and more recently to build generators, motors and data storage devices,” said co-author Hendrik Ohldag, a scientist at SSRL. “However, magnetic elements were mostly viewed as static and uniform. To push the limits of energy efficiency in the future we need to understand better how magnetic devices behave on fast timescales at the nanoscale, which is why we are using this dedicated ultrafast X-ray microscope.”

    “This is an exciting observation because it shows that small magnetic waves – known as spin-waves – can add up to a large one in a magnet,” explains Andrew Kent, a professor of physics at New York University and a senior author for one of the studies.. “A specialized X-ray method that can focus on particular magnetic elements with very high resolution enabled this discovery and should enable many more insights into this behavior.”

    Solitons are a form of spin waves, which are disturbances that propagate in a magnetic material as a patterned, rippling response in the material’s electrons. This response is related to the spin of electrons, a fundamental particle property that can be thought of as either “up” or “down” – like the head or tail sides of a coin.

    An ultrafast camera coupled to a custom-built X-ray microscope at SLAC’s Stanford Synchrotron Radiation Lightsource allowed researchers to produce a six-frame “movie” of the soliton’s motion. It took about 12 hours to record enough X-ray data to produce the movie. (Stefano Bonetti/Stockholm University)

    In 1834 John Scott Russell, a Scottish civil engineer and shipbuilder, first described his observation of the soliton phenomenon in a boat-produced wave that held a uniform shape for over a mile as it traveled down a canal. Solitons had for decades been theorized to occur in magnets, but it took a specialized X-ray microscope like the one at SLAC to directly observe the effect.

    “We built a microscope that allowed us to look at these magnetic waves in a new way,” said Stefano Bonetti, the leading author of the study published in Nature Communications. Bonetti is a Stanford University postdoctoral fellow now at Stockholm University. “With this new microscope, we can actually see them moving,” he said. “We can see things directly.”

    An ultrafast camera coupled to the microscope allowed researchers to record six images that were compiled in sequence to form a “movie” of the soliton’s motion. It took about 12 hours to record enough X-ray data to produce the movie.

    The high resolution of the X-ray microscope revealed an anomaly in the spin-wave effects: While researchers expected the soliton to fully flip the local magnetic alignment of the material, like a compass switching from north to south, they found that the soliton caused the material’s magnetic orientation to change only slightly.

    “We would expect to see this reverse, or flip,” Bonetti said. “But it didn’t reverse – it just tilted about 25 degrees. The situation is not as simple as people thought.”

    Also, in one of the experiments researchers saw the soliton split in two: it was expected to take a spherical or circular form, but instead appeared split down the middle, as if an approaching ocean wave had split into two separate waves that were mirror images of each other. “In the simulations we were using before, we were blind to this possibility,” Bonetti said.

    More experiments are needed to understand both the tilting effect and the way that the soliton can split into a mirrored form, Bonetti said. Simulations could help researchers learn how to convert the mirrored pattern of the soliton into a more uniformly symmetrical shape, he said, or to understand how to use the split form for data applications.

    Researchers from Stanford University; SIMES, the Stanford Institute for Materials and Energy Sciences at SLAC; University of Barcelona in Spain; KTH Royal Institute of Technology in Sweden; New York University; HGST, a Western Digital Company; and Emory University in Georgia also contributed to the study. The work was supported by Everspin Technologies, the DOE Office of Science, the Knut and Alice Wallenberg Foundation, the Swedish Research Council, the Catalan Government, the National Science Foundation, the Forsk Foundation, the European Commission, the U.S. Army Research Office and Brookhaven National Laboratory.

    Citations: S. Bonetti, et al., Nature Communications, 16 November 2015 (10.1038/NCOMMS9889)

    D. Backes, et al., Physical Review Letters, 17 September 2015 (10.1103/PhysRevLett.115.127205)

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  • richardmitnick 7:26 am on October 30, 2015 Permalink | Reply
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    From TUM: “New state-of-the-art compact X-ray source” 

    Techniche Universitat Munchen

    Techniche Universitat Munchen

    Dr. Klaus Achterhold
    Technical University of Munich (TUM)
    Department of Physics (E17)
    Tel.: +49 (0)89 289 – 12559

    The new mini synchrotron “Munich Compact Light Source” is located in Garching at TUM Institute of Medical Engineering (IMETUM). (Photo: K. Achterhold / TUM)

    For some years now it has been possible to generate high-brilliance X-rays using ring-shaped particle accelerators (synchrotron sources). However, such installations are several hundred meters in diameter and cost billions of euros. The world’s first mini synchrotron was inaugurated today at Technical University of Munich (TUM). It can generate high-brilliance X-rays on a footprint measuring just 5 x 3 meters. The new unit will be used chiefly to research biomedical questions relating to cancer, osteoporosis, pulmonary diseases and arteriosclerosis.

    Scientists and physicians are still routinely using X-rays for diagnostic purposes 120 years after their discovery. A major aim has therefore been to improve the quality of X-rays in order to make diagnoses more accurate. For example, soft tissues could thereby be visualized better and even minute tumors detected. For a considerable time, a team at the Technical University of Munich (TUM) headed by Professor Franz Pfeiffer, Chair of Biomedical Physics, has been developing new X-ray techniques.

    Starting October 29th, the scientists will now be able to use the world’s first mini synchrotron for high-brilliance X-rays at their institute. The Munich Compact Light Source (MuCLS) is part of the new Center for Advanced Laser Applications (CALA), a joint project between TUM and Ludwig-Maximilians-Universität München (LMU).

    New technique: collision between electrons and a laser beam

    The California-based company Lyncean Technologies, which developed the mini synchrotron, employed a special technique. Large ring accelerators generate X-rays by deflecting high-energy electrons with magnets. They obtain high energies by means of extreme acceleration, and this requires big ring systems.

    The new synchrotron uses a technique where X-rays are generated when laser light collides with high-speed electrons – within a space that’s half as thin as a human hair. The major advantage of this approach is that the electrons can be traveling much more slowly. Consequently, they can be stored in a ring accelerator less than five meters in circumference, whereas synchrotrons need a circumference of nearly one thousand meters.

    “We used to have to reserve time slots on the large synchrotrons long in advance if we wanted to run an experiment. Now we can work with a system in our own laboratory – which will speed up our research work considerably,” says Pfeiffer.

    More intense, more variable and with better resolution

    Apart from being more compact, the new system has other advantages over conventional X-ray tubes. The X-rays it produces are extremely bright and intense. Moreover, the energy of the X-rays can be precisely controlled so that they can be used, for example, for examining different tissue types. They also provide much better spatial resolution, as the source of the beam is less diffuse thanks to the small collision space.

    “Brilliant X-rays can distinguish materials better, meaning that we will be able to detect much smaller tumors in tissue in the future. However, our research activities also include measuring bone properties in osteoporosis and determining altered sizes of pulmonary alveoli in diverse lung diseases,” explains Dr. Klaus Achterhold from the MuCLS team.

    The scientists will initially use the instrument mainly for preclinical research, i.e. examining tissue samples from patients. They will also combine the new X-ray source with other systems, such as phase contrast. The group headed by Franz Pfeiffer has developed and refined the new X-ray phase-contrast technique.

    See the full article here .

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  • richardmitnick 9:58 am on September 25, 2015 Permalink | Reply
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    From BNL: “NSLS-II Scientists Find Flexible Boundary Between Phases of Matter Within Supercritical Fluids” 

    Brookhaven Lab

    September 24, 2015
    Chelsea Whyte

    Dima Bolmatov and IXS Group Leader Yong Cai at the Inelastic X-ray Scattering (IXS) beamline at the National Synchrotron Light Source II.

    Imagine a planet, a gas giant like Jupiter. The biggest planet in our Solar System is composed mainly of helium and hydrogen, which make up a thick atmosphere above a molten rocky core. But where does the surface begin and the atmosphere end on a planet like that? Where is the line between the gas phase and the fluid at its center?

    Questions like these can be answered by understanding the boundaries between phases of matter. Through the classic example of water’s three phases – steam, liquid, and ice – we often come to the conclusion that these phases are delineated by strong boundaries that can’t be breached, like a brick wall.

    But expose certain gases to enough pressure and heat, and they will enter a hinterland between the phases, a supercritical area where they can have the properties of both a gas and a liquid at the same time. This extraordinary behavior of ordinary liquids is exploited for use in many technologies.

    Fluids in the supercritical phase share the properties of liquids and vapor, so they can easily diffuse through solids like a gas and dissolve materials as a liquid might. For example, supercritical fluids are used to “wash” caffeine out of coffee to produce decaf. This property also comes in handy for the production of pharmaceuticals and cosmetics, and even in dry-cleaning processes. These fluids are also a key component of nuclear waste cleanup methods.

    Dima Bolmatov, a physicist at the National Synchrotron Light Source II (NSLS-II)—a Department of Energy Office of Science User Facility at Brookhaven National Laboratory—led a study to better understand the nature of the boundary between phases and the behavior of supercritical fluids, using high-energy x-rays to examine the atomic structures of supercritical fluids at different temperatures and pressures. This work is published in The Journal of Physical Chemistry Letters.

    “People used to believe that supercritical phase was dynamically and structurally uniform,” Bolmatov said. “My phonon theory of liquids predicted that the supercritical state is not uniform, but that there is a boundary instead, namely the Frenkel line, that demarcates thermodynamic, dynamic, and structural properties on the phase diagram.”

    These two distinct domains within the supercritical phase were proven through the experimental work done by Bolmatov and his group. “We didn’t just detect the Frenkel line, we also explained how thermodynamics behaves within and beyond the boundary.”

    Knowledge about this boundary helps scientists fine-tune supercritical fluids using temperature or pressure in order to use them more efficiently and better predict the behavior of the fluid.

    “Tune those two parameters, and you can find the coexistence of two or even three phases,” Bolmatov said. “It’s about the rearrangements of atoms and molecules. That’s why pressure and temperature make a distinction between phases.”

    The IXS beamline team (from left to right): Dima Bolmatov, Alessandro Cunsolo, Yong Cai, Mikhail Zhernenkov.

    For the experiment, Bolmatov and his collaborators Mikhail Zhernenkov, Alessandro Cunsolo, and Yong Cai used a diamond anvil cell to increase pressure on a sample of argon, while also increasing the temperature until it reached the supercritical phase. At the Advanced Photon Source [APS], a DOE Office of Science User Facility at Argonne National Laboratory, they performed inelastic X-ray scattering measurements to determine the changes in the atomic dynamics as heat and pressure increased.


    Such measurements helped understanding how sound waves propagate through the fluid. All these tests resulted in a new understanding of the boundaries between phases. Instead of an abrupt change, they found that supercritical fluids transform between phases in a smooth, continuous manner.

    Bolmatov’s work will continue at the Inelastic X-ray Scattering (IXS) beamline at NSLS-II. Yong Cai, the NSLS-II IXS Beamline Lead Scientist, is in charge of the development, operation, and management of IXS.

    “IXS will offer the best energy resolution in the world for measurements of atomic and molecular dynamics at the nanometer length scale,” said Cai. “These capabilities enable scientists in the world to study sound control and heat manipulation in disordered materials, like liquid crystals and glasses, molecular transport through biomembranes, or to understand interaction of nanoparticles dissolved in water.”

    Now in the commissioning phase, the IXS beamline plans to be operational by the end of 2015, when it will begin hosting scientific users.

    See the full article here .

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

  • richardmitnick 9:31 am on September 18, 2015 Permalink | Reply
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    From DESY: “X-rays reveal electron puddles in ceramic superconductors” 


    No Writer Credit

    The superconducting current (red tubes) running in the interstitial space between puddles of electronic crystals. Credit: Alessandro Ricci/DESY

    Using high-energy X-rays, an international team of scientists has discovered a surprising inner structure of a special class of superconductors: Within these so-called high-temperature superconductors, the electrons form puddles of varying sizes throughout the material. This finding helps to understand the microscopic origin of high-temperature superconductivity that is still not fully known. The team reports its observations in the journal Nature.

    Superconductors are materials that can transport electric currents completely without loss. This feature makes them attractive for a wide spectrum of technical applications. Unfortunately, classic superconductors have to be cooled down to temperatures near absolute zero (minus 273,15 degrees Celsius) to work. This limits their application to a few special purposes. However, a couple of decades ago it was discovered that certain ceramics can become superconducting at much higher temperatures. Despite their name, these high-temperature superconductors still have to be cooled down, but not as much as classic superconductors. Some copper oxides (cuprates) can become superconducting at minus 170 degrees Celsius, for instance.

    High-temperature superconductors work different from classic superconductors, and with a better understanding of their function, the design of a room temperature superconductor might become possible one day. To investigate the microstructure of a high-temperature cuprate superconductor (HgBa2CuO4+y), the team led by Alessandro Ricci of DESY, Antonio Bianconi of the Rome International Centre for Materials Science Superstripes (RICMASS) and Gaetano Campi of the Italian Council of National Research (CNR) looked at it with high-energy X-rays at DESYs synchrotron light source DORIS (beamline BW5), the Italian synchrotron Elettra and the European Synchrotron Radiation Source ESRF.


    Elettra Synchrotron Italy

    Here they used a special space resolved diffraction technique (called scanning micro X-ray diffraction) that allows to investigate the microscopic aggregation of electrons in small crystalline domains.

    In conventional materials like metals and semiconductors, the electrons, carriers of the electric charge, move homogenous, like a liquid spreading out evenly in a canal. For many decades scientists believed that superconductivity also had to appear as a homogenous order in the material. By contrast, in the high-temperature cuprate superconductor investigated, the electrons start to aggregate and form puddles at minus 20 degrees Celsius already. „We discovered that the sizes of these puddles vary widely, like the chunks of a molten iceberg or the steam bubbles in a boiling pot“, explains Ricci. While the average puddle measures about 4 nanometres (millionths of a millimetre) across, puddles as large as 40 nanometres could be seen. The distribution of the puddle sizes can be described by a power-law which is typical for self-organisation.

    The scientists could show that the puddles fill the whole material, leaving free interstitial space. Not all electrons become aggregated in these puddles. The electric current, which is carried by pairs of electrons that have remained free, has to flow around the puddles. As the authors found, the interstitial space between the puddles can be described by a special form of geometry: While the world around us usually follows the rules of Euclidean geometry, in the interstitial space of the high-temperature superconductor a hyperbolic geometry applies, as Ricci point out. „These results open new avenues for the design of superconducting materials, and thus could advance the search for a room temperature superconductor.“

    The team consisted of scientists from DESY, RICMASS, CNR, ESRF, Elettra, the University of Twente in The Netherlands, the Queen Mary University of London, the Swiss Federal Institute of Technology, the Moscow State University and Ghent University in Belgium.

    „Inhomogeneity of charge-density-wave order and quenched disorder in a high-Tc superconductor“; G. Campi, A. Bianconi, A. Ricci et al.; Nature, 2015; DOI: 10.1038/nature14987

    See the full article here .

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    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

  • richardmitnick 3:05 pm on September 1, 2015 Permalink | Reply
    Tags: , , X-ray Technology   

    From phys.org: “Team harnesses intense X-ray beam, observes unusual phenomenon for the first time” 


    August 31, 2015

    Using an enormous X-ray laser—one of only two such machines on Earth—University of Nebraska-Lincoln physicist Matthias Fuchs and scientists from around the world beat formidable odds to observe one of the most fundamental interactions between X-rays and matter.

    The findings can aid future studies and may lead to novel new ways to diagnose matter in the future.

    Fuchs and his colleagues induced two X-ray photons to simultaneously collide with a single atom, which converts them into a single higher-energetic X-ray photon. It’s a phenomenon that doesn’t occur under normal circumstances, and the results of the first-ever experiment were published Monday in the journal Nature Physics.

    Fuchs, an assistant professor of physics and astronomy, is the article’s lead author. Others involved are from the Stanford Linear Accelerator Center, Stanford University and Bar-Ilan University in Israel.

    “The experiment was the very first investigation of this kind, which means that we were entering what you would call ‘Neuland’ (German for uncharted territory),” Fuchs said.

    Scientists first observed a similar process involving high-intensity visible light in the 1960s, resulting in a technology used in most laser laboratories and even with many laser pointers available to consumers. However, it had not been possible until recently to observe such interactions at X-ray wavelengths because there was no X-ray source that could produce X-rays of sufficient intensity.

    Because they have a small wavelength that allows scientists to resolve matter down to the size of its constituent atoms, X-rays are routinely used to take a “deep look” into matter, Fuchs said. The double-helix structure of DNA was one of the most famous discoveries using X-rays. The field of X-rays has generated at least 15 Nobel Prizes and as many as 28, if discoveries that indirectly use X-rays are counted.

    Fuchs and other team members used a new source of X-rays, an X-ray free-electron laser at the National Accelerator Laboratory in California, to conduct experiments. Measuring more than a kilometer in length, the only other machine like it is in Japan.

    SLAC Campus

    SLAC LCLS Inside
    LCLS at SLAC

    Focusing the machine’s full output into a spot of only 100 nanometers in size, the team generated an X-ray beam with intensity equivalent to all of the sun’s radiation that is striking the Earth’s surface but concentrated in an area with the diameter of a human hair.

    “We needed such extreme intensities to improve the chances of both of the two photons meeting up at exactly the right place and exactly the right time on one of the many atoms that were illuminated,” Fuchs said. “Even so, the probability that this nonlinear interaction occurs on any given atom is less than winning the lottery.”

    The scientists found some unexpected results, however. The energy of the converted photons was much lower than expected, indicating that the physics of the interaction may be richer and more interesting than anticipated.

    One scientist who anonymously reviewed the research said that when the phenomenon becomes better understood, it will become a part of textbooks on X-ray physics and nonlinear optics.

    “This experiment is just beginning,” Fuchs said. “If our new understanding of this fundamental process can be confirmed by future experiments, it can have significant impact on future experiments that are performed with high X-ray intensities and can lead to novel diagnostic methods of matter.”

    See the full article here.

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    About Phys.org in 100 Words

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

  • richardmitnick 1:13 pm on August 7, 2015 Permalink | Reply
    Tags: , , , X-ray Technology   

    From SLAC: “Unique SLAC Technology to Power X-ray Laser in South Korea” 

    SLAC Lab

    August 7, 2015

    In a diligent, two-month-long process, SLAC engineers tested the first of the XL4 klystrons built for PAL. (SLAC National Accelerator Laboratory)

    Accelerator technology pioneered at the Department of Energy’s SLAC National Accelerator Laboratory is on its way to powering X-ray science in South Korea: On Aug. 6, the lab shipped one of its unique radio-frequency amplifiers – an XL4 klystron – to Pohang Accelerator Laboratory (PAL), where it will become a key component for the optimal performance of a new X-ray free-electron laser under construction.

    Klystrons are the driving force behind many particle accelerators. They generate powerful radio-frequency fields that provide the energy to bring charged particles up to speed for collision experiments and the production of intense X-rays.

    However, SLAC’s XL4 klystron, which operates in a particular frequency range known as the X-band, will serve another purpose at PAL: It will power accelerator structures that let scientists optimize the electron beam in the future X-ray laser.

    “We are the world’s experts for X-band radio-frequency accelerator technology,” says SLAC’s Michael Fazio, who leads the lab’s Technology Innovation Directorate (TID). “PAL and SLAC have a collaborative agreement under which SLAC is providing klystrons and other accelerator components for the new X-ray laser.”

    Optimizing X-ray Laser Performance in South Korea

    PAL is building an X-ray laser similar to SLAC’s Linac Coherent Light Source (LCLS), a DOE Office of Science User Facility that generates the most powerful X-rays on Earth. With their extremely bright and ultrashort light pulses, X-ray lasers enable groundbreaking research in many scientific areas, from materials science to biology to studies of matter in extreme conditions.

    SLAC LCLS Inside
    LCLS interior

    These state-of-the-art light sources produce X-ray light by sending short electron bunches on a wavy path inside special magnets.

    “For the best X-ray laser performance, the electron bunches must be very short, on the order of only tens to hundreds of a quadrillionth of a second,” says SLAC engineer Erik Jongewaard, the project leader of the collaboration with PAL. “However, bunches produced by the laser’s electron source itself are too long and need to be shortened by bunch compressors.”

    This is where SLAC’s XL4 klystron comes in: It delivers energy to a so-called X-band linearizer – an accelerator structure that manipulates bunches in such a way that they can be optimally shortened in the subsequent bunch compressor.

    “This manipulation can conveniently be done in the X-band,” Jongewaard says. “When it comes to X-band accelerator technology, SLAC is the only place in the world where you can go from concept through design, engineering, fabrication, testing and operation all in one place and where the entire system can be specified and optimized.”

    For the South Korean X-ray laser project, PAL therefore began collaborating with SLAC in 2012.

    “Under the $3.4-million agreement, our team built the linearizer components including two XL4 klystrons,” says SLAC’s Lisa Bonetti, head of the TID Advanced Prototyping, Fabrication and Test Facilities department. “We also trained PAL engineers here on site in using our X-band technology.”

    The first klystron and other parts are now on their way to PAL. The second klystron, which will serve as a spare but could potentially also be used in a tool to diagnose the X-ray laser’s electron and X-ray beams, is currently being tested.

    Exporting Expertise Built on Decades of Research

    SLAC’s unparalleled expertise with X-band technology goes back to the 1980s when researchers began thinking about an energy upgrade of the lab’s 2-mile-long linear accelerator to enable new particle physics experiments. Given the choice of either building an even longer accelerator or developing klystrons that drive particles to higher energies, scientists opted for the latter. This marked the birth of SLAC’s X-band program.

    Although the linear accelerator never got its energy upgrade, the X-band technology kept developing. The latest klystron model is the XL4 – an extraordinarily stable radio-frequency source with 50 million watts of peak power. At SLAC, two of them are integrated into LCLS while others power experiments at the lab’s Next Linear Collider Test Accelerator (NLCTA) and Accelerator Structure Test Area (ASTA).

    “SLAC has built a total of 22 XL4 klystrons to date, including a modified version, called the XL5, for accelerator facilities in Europe,” Jongewaard says. “Three are used in Switzerland: one at CERN and two at the Paul Scherrer Institute. We also built another two for the Elettra research center in Italy.” The XL5 model is now commercially produced by Communications & Power Industries, a Palo Alto-based company.

    Soon, SLAC’s X-band radio-frequency technology will also benefit science in East Asia: Hopes are that PAL’s X-ray laser will produce its first light in 2016.

    Members of the Advanced Prototyping, Fabrication and Test Facilities department of SLAC’s Technology Innovation Directorate and engineers of the Pohang Accelerator Laboratory (PAL) in South Korea gather next to an XL4 klystron – a unique high-power radio-frequency amplifier used to accelerate and manipulate particle beams. Over the past 20 months, SLAC has built two klystrons and other parts needed to optimize the performance of PAL’s future X-ray laser. (SLAC National Accelerator Laboratory)

    See the full article here.

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

  • richardmitnick 3:55 pm on July 27, 2015 Permalink | Reply
    Tags: , , , , X-ray Technology   

    From SLAC: “New ‘Molecular Movie’ Reveals Ultrafast Chemistry in Motion” 

    SLAC Lab

    June 22, 2015

    This video describes how the Linac Coherent Light Source, an X-ray free-electron laser at SLAC National Accelerator Laboratory, provided the first direct measurements of how a ring-shaped gas molecule unravels in the millionths of a billionth of a second after it is split open by light. The measurements were compiled in sequence to form the basis for computer animations showing molecular motion. (SLAC National Accelerator Laboratory)

    Scientists for the first time tracked ultrafast structural changes, captured in quadrillionths-of-a-second steps, as ring-shaped gas molecules burst open and unraveled. Ring-shaped molecules are abundant in biochemistry and also form the basis for many drug compounds. The study points the way to a wide range of real-time X-ray studies of gas-based chemical reactions that are vital to biological processes.

    This illustration shows shape changes that occur in quadrillionths-of-a-second intervals in a ring-shaped molecule that was broken open by light. The molecular motion was measured using SLAC’s Linac Coherent Light Source X-ray laser. The colored chart shows a theoretical model of molecular changes that syncs well with the actual results. The squares in the background represent panels in an LCLS X-ray detector. (SLAC National Accelerator Laboratory)

    Researchers working at the Department of Energy’s SLAC National Accelerator Laboratory compiled the full sequence of steps in this basic ring-opening reaction into computerized animations that provide a “molecular movie” of the structural changes.

    Conducted at SLAC’s Linac Coherent Light Source, a DOE Office of Science User Facility, the pioneering study marks an important milestone in precisely tracking how gas-phase molecules transform during chemical reactions on the scale of femtoseconds. A femtosecond is a millionth of a billionth of a second.

    “This fulfills a promise of LCLS: Before your eyes, a chemical reaction is occurring that has never been seen before in this way,” said Mike Minitti, a SLAC scientist who led the experiment in collaboration with Peter Weber at Brown University. The results are featured in the June 22 edition of Physical Review Letters.

    “LCLS is a game-changer in giving us the ability to probe this and other reactions in record-fast timescales,” Minitti said, “down to the motion of individual atoms.” The same method can be used to study more complex molecules and chemistry.

    The free-floating molecules in a gas, when studied with the uniquely bright X-rays at LCLS, can provide a very clear view of structural changes because gas molecules are less likely to be tangled up with one another or otherwise obstructed, he added. “Until now, learning anything meaningful about such rapid molecular changes in a gas using other X-ray sources was very limited, at best.”

    New Views of Chemistry in Action

    The study focused on the gas form of 1,3-cyclohexadiene (CHD), a small, ring-shaped organic molecule derived from pine oil. Ring-shaped molecules play key roles in many biological and chemical processes that are driven by the formation and breaking of chemical bonds. The experiment tracked how the ringed molecule unfurls after a bond between two of its atoms is broken, transforming into a nearly linear molecule called hexatriene.

    “There had been a long-standing question of how this molecule actually opens up,” Minitti said. “The atoms can take different paths and directions. Tracking this ultimately shows how chemical reactions are truly progressing, and will likely lead to improvements in theories and models.”

    The Making of a Molecular Movie

    In the experiment, researchers excited CHD vapor with ultrafast ultraviolet laser pulses to begin the ring-opening reaction. Then they fired LCLS X-ray laser pulses at different time intervals to measure how the molecules changed their shape.

    Researchers compiled and sorted over 100,000 strobe-like measurements of scattered X-rays. Then, they matched these measurements to computer simulations that show the most likely ways the molecule unravels in the first 200 quadrillionths of a second after it opens. The simulations, performed by team member Adam Kirrander at the University of Edinburgh, show the changing motion and position of its atoms.

    Each interval in the animations represents 25 quadrillionths of a second ­– about 1.3 trillion times faster than the typical 30-frames-per-second rate used to display TV shows.

    “It is a remarkable achievement to watch molecular motions with such incredible time resolution,” Weber said.

    A gas sample was considered ideal for this study because interference from any neighboring CHD molecules would be minimized, making it easier to identify and track the transformation of individual molecules. The LCLS X-ray pulses were like cue balls in a game of billiards, scattering off the electrons of the molecules and onto a position-sensitive detector that projected the locations of the atoms within the molecules.

    A Successful Test Case for More Complex Studies

    “This study can serve as a benchmark and springboard for larger molecules that can help us explore and understand even more complex and important chemistry,” Minitti said.

    Additional contributors included scientists at Brown and Stanford universities in the U.S. and the University of Edinburgh in the U.K. The work was supported by the DOE Office of Basic Energy Sciences.

    See the full article here.

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

  • richardmitnick 1:36 pm on July 22, 2015 Permalink | Reply
    Tags: , , , X-ray Technology   

    From Rockefeller: “Atomic view of cellular pump reveals how bacteria send out proteins” 

    Rockefeller U bloc

    Rockefeller University

    July 22, 2015
    Wynne Parry | 212-327-7789

    A watery passage: The pump, a single-molecule machine, (yellow coils) carries proteins through the cell membrane (pink and dark blue). Within the pump, the researchers found a strikingly large water-filled channel (light blue), a natural environment for hydrophilic proteins. No image credit

    Bacteria have plenty of things to send out into world beyond their own boundaries: coordinating signals to other members of their species, poisons for their enemies, and devious instructions to manipulate host cells they have infected. Before any of this can occur, however, they must first get the shipments past their own cell membranes, and many bacteria have evolved specialized structures and systems for launching the proteins that do these jobs.

    Researchers at The Rockefeller University have determined the structure of a simple but previously unexamined pump that controls the passage of proteins through a bacterial cell membrane, an achievement that offers new insight into the mechanics that allow bacteria to manipulate their environments. The results were published in Nature on July 23.

    “This pump, called PCAT for peptidase-containing ATP-binding cassette transporter, is composed of a single protein, a sort of all-in-one machine capable of recognizing its cargo, processing it, then burning chemical fuel to pump that cargo out of the cell,” says study author Jue Chen, William E. Ford Professor and head of the Laboratory of Membrane Biology and Biophysics. “This new atomic-level structure explains for the first time the links between these three functions.”

    Of the many types of molecules cells need to move into and out of their membranes, proteins are the largest. PCATs specialize in pumping proteins out of the cell, and, because they are single-molecule machines that work alone, or with two partner proteins in some bacteria, they are the simplest such systems.

    Each PCAT molecule has three domains, each in duplicate: one recognizes the cargo by a tag it carries, and cuts off that tag; another binds to and burns ATP, a molecule that contains energy stored within its atomic bonds; and the third forms a channel that spans the cells membrane. Previous work had examined the structure of the first two domains, but the structure of the third, had remained a mystery, along with the details of how the components function together.

    “At this point, we have no idea how many PCATs exist, although we expect they are numerous, because each specializes in a specific type of cargo. For this study, we focused on one we called PCAT1, which transports a small protein of unknown function,” says first author David Yin-wei Lin, a postdoc in the lab. “To get a sense of how PCAT1 changes shape when powered by energy from ATP, we examined the structure in two states, both with and without ATP.”

    The team, which also included Shuo Huang, a research technician who is now a graduate student at Georgia Institute of Technology, purified and crystalized the PCAT1 protein from the heat-loving bacterium Clostridium thermocellum. To determine the structure of the crystals, they used a technique called X-ray diffraction analysis, in which a pattern produced by X-rays bounced off the crystallized protein can be used to infer the structure of the molecule.

    The first structure, determined without ATP, revealed a striking feature: a large, water-filled central channel, a natural environment for a water-loving, or hydrophilic, protein. Two side openings into this channel were guarded by the cargo-recognizing domain, acting as a sort of ticket taker. Sites on this domain would recognize and clip off the cargo’s tag, before ushering the protein into the channel.

    When ATP is present, they found that the side entrances close, freeing the cargo-recognizing domain to move from its station outside of them. In addition, the ATP-binding domains at the bottom of the channel inside the cell come together. The researchers also saw the water channel shrink, leading them to hypothesize that energy from ATP allows PCAT1 to change conformation in such a way that it pushes its cargo out. This suggests that PCAT1 uses a strategy commonly seen in transport proteins known as alternate access, in which one end of the channel is open while the other closes. However, they qualify that PCATs that transport much larger proteins may function differently.

    “By visualizing the structure of this pump, we have been able to determine the details of a transport pathway that, in its simplicity, is fundamentally different from the more complex systems that have been closely studied before. This new information adds to the understanding of how cells send out proteins in order to interact with their environment,” Chen says.

    See the full article here.

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    Rockefeller U Campus

    The Rockefeller University is a world-renowned center for research and graduate education in the biomedical sciences, chemistry, bioinformatics and physics. The university’s 76 laboratories conduct both clinical and basic research and study a diverse range of biological and biomedical problems with the mission of improving the understanding of life for the benefit of humanity.

    Founded in 1901 by John D. Rockefeller, the Rockefeller Institute for Medical Research was the country’s first institution devoted exclusively to biomedical research. The Rockefeller University Hospital was founded in 1910 as the first hospital devoted exclusively to clinical research. In the 1950s, the institute expanded its mission to include graduate education and began training new generations of scientists to become research leaders around the world. In 1965, it was renamed The Rockefeller University.

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