U of C Physics faculty conduct a broad program of experiments in condensed matter phenomena. The main site of this research is the interdisciplinary James Franck Institute or JFI, pictured above. The faculty of the Institute are physicists, physical chemists, geochemists, and applied mathematicians who combine their strengths to attack phenomena that go beyond the physics discipline. Physics students studying condensed matter interact closely and regularly with these other disciplines.
Below, each faculty member describes their research interests and representative publications. They update these every year or more. For more current information on our condensed matter experiments, see the Materials Center, a federally funded research center closely connected with the JFI. Another good place to find current research is the granular physics group site. It describes collaborative research on granular materials. The Institute for Biophysical Dynamics, IBD. This new institute will investigate physical phenomena in living organisms. Related research is described on our condensed matter theory page and our main experimental physics page.
Ph.D., Institut Marie Curie, Paris, 1996.
Asst. Prof., Dept. Physics, Inst. for Biophysical Dynamics, James Franck Inst., and the College
Experimental biological physics, non-equilibrium systems, biopolymers.
homepage: http://cluzel.uchicago.edu
Noise and information in biological systems. Sudden changes of environment and
life-cycle phases (growth, cell division, and death) characterize the conditions far from
the equilibrium of chemical reactions occurring within individual cells. Yet cells, or more
generally, biological systems, are able to process information accurately and to achieve
precise tasks. How do biological systems use or circumvent these noisy conditions? Most of
the experiments and mathematical models have assumed that the characteristics of the signaling
and chemical reactions occurring within individual cells could be inferred from ensemble measurements.
This approach, however, masks the temporal fluctuations and the dynamics of biological heterogeneous
systems. A more promising alternative is to describe individually and in "real time" these
strongly non-linear (living) systems. By developing novel single-molecule techniques, we can revisit
canonical biological systems and question the advantage of "noise" for inter/intracellular
signaling.
Noise in gene expression in bacteria. When few molecules are involved, chemical reactions
are subject to stochastic fluctuations. Important steps of the gene expression in bacteria can be
modeled by basic chemical reactions. A few molecules in the cell control these reactions.
Consequently, the pattern of protein concentration growth is expected to be highly stochastic,
exhibiting short bursts of variable numbers of proteins at varying time intervals. We are
interested in characterizing experimentally the statistics of those simple chemical reactions
that control the gene expression in individual living cells.
Signaling in chemotaxis. The chemotactic system of E. coli (the network that
governs the migration of bacteria towards chemical attractants) is used as a prototype for the
study of intracellular signal transduction networks. Our approach is to consider the chemotactic
network controlling cellular behavior as a biochemical circuit composed of independent modules.
We identify the modules' contribution to the output within single living cells as well as the
possible sources of their noise.
- Korobkova E., Emonet T., Park H, Cluzel P. Hidden stochastic nature of a single bacterial motor,
Phys. Rev. Letters, 96, 58105 (2006).
- TT, Harlepp S., Guet CC, Dittmar K, Emonet T., Pan T., Cluzel P. Real-time RNA profiling within a single
bacterium, Proc. Natl. Acad. Sci. U S A., 28; 102 (26):9160-4 (2005).
- Korobkova E., Emonet T., Vilar J., Shimizu T. & Cluzel P. From molecular
noise to behavioral variability in a single bacterium, Nature, 428,
574-578 (2004.)
- Aldana M and Cluzel P. A natural class of robust networks, Proc Natl
Acad Sci U S A. 22;100(15):8710-4 (2003).
- Cluzel P, Surette M, Leibler S. An ultrasensitive bacterial motor
revealed by monitoring signaling proteins in single cells, Science 287:
1652-1655 (2000).
- Cluzel P, Lebrun A, Heller C, Lavery R, Chatenay D, Caron F.. DNA : An Extensible Molecule, Science 271: 792-794. (1996)
updated 8/2006
Dean E. Eastman
Ph.D., MIT, 1965.
Prof., Dept. Physics and James Franck Inst.
Experimental physics; condensed matter physics.
My research interests include the development and application of leading edge synchrotron radiation techniques to interfaces, surfaces, thin films, and nanostructures relevant to future microelectronic devices and other novel material systems. Representative materials systems of interest include those relevant to (1) future Si CMOS-based technologies, (2) GaN and other III-V semiconductor films on Si and sapphire, and (3) multilayer magnetic thin film systems.
Synchrotron radiation techniques address physical structures; e.g., nanostructures, surface and interface structures, stress/strain distributions, dislocations, defects and doping distributions, as well as chemical and electronic properties. These techniques include various X-ray diffraction, microspectroscopy, microscopy, and other scattering techniques. Various types of photoelectron spectroscopy techniques (including band-mapping) using synchrotron radiation are used to study the electronic structure of surfaces, nanostructures, and solids. In addition to synchrotron radiation techniques, atomic scanning microscopy (STM, scanning tunneling microscope, and AFM, atomic force microscope) and STEM and SEM electron microscopy techniques offer powerful complemental capabilities to study physical and electronic structures.
This research utilizes leading edge synchroton radiation facilities (beamlines/end stations) at the Advanced Photon Source (APS), the Advanced Light Source (ALS), and others. It also involves collaborations with leading researchers in industry, at universities, and at government laboratories who provide samples, complementary characterization and processing capabilities as well as knowledge in addressing key questions and opportunities in advancing the state of the art. These advanced sample preparation and processing capabilities also facilitate studies of novel mesophysics phenomena involving nanostructures.
- X-ray micro-diffraction studies of dislocation induced micro-structures
in SiGe films. C. Stagarescue, G. Xu, D.E. Eastman, B. Lai, Z. Cai, P. M. Mooney, J.L. Jordan-Sweet. In preparation for Phys. Rev. Lett., 2001.
- Quantitative metrology study of Cu/SiO2 interconnect structures
using fluorescence x-ray microscopy. G. Xu, X. Su, C. Stagarescue, D.E. Eastman, B. Lai, Z. Cai, and C.-K. Hu. Appl. Phys. Lett. 78, 820, 2000.
- Quantitative nanoscale metrology study of Cu/SiO2 interconnect technology using nanoscale x-ray transmission microscopy. X. Su, C. Stagarescue, G. Xu, D.E. Eastman, I. McNulty, I. C. Noyan, and C.-K. Hu. Appl. Phys. Lett. 77, 3465, 2000.
- Orbital character of O2p unoccupied states near the Fermi level in CrO2. C.B. Stagarescu, X. Su, and D.E. Eastman, K.N. Altmann, and F.J. Himpsel, A. Gupta. Phys. Rev. B 61, R9233, 2000.
updated 6/2001
Philippe Guyot-Sionnest
Ph.D., California, Berkeley, 1987.
Prof., Depts. Chemistry and Physics, James Franck Inst., and the College
Experimental physics, surface physics, nonlinear optical spectroscopy.
homepage: Prof. Guyot-Sionnest
in the Department of Chemistry
Quantum Confined Semiconductors. Delocalized electronic wavefunctions are
readily achievable in semiconductor quantum dots, such as semiconductor nanocrystal
colloids. This leads to extraordinary optical properties, which may lead to applications
ranging from full-color displays, to photovoltaic cells. We synthesize semiconductor
nanocrystals, and control their sizes and their surfaces. Microscopy and nonlinear
spectroscopy are used to study the basic aspects of electron dynamics and interaction
in strongly confined structures. We currently focus on the doping of nanocrystals and
the very unusual infrared response, e.g. electrochromic, as well as the novel electrical
transport properties in films made of these artificial atoms.
Optical Response of Metallic Nanostructures. Metallic structures much smaller
than the wavelength of light allow to enhance locally the electromagnetic fields by
several orders of magnitude. The enhancement is achieved by the plasmon resonance which
is a collective excitation specific to the shape of the structure but involving all its
free electrons. The enhancement is thus often limited by electron scattering process, in
particular surface scattering which is increased in this small structures. Our research
aims to synthesize metallic nanostructures, characterize their optical response, and optimize
the materials combination to obtain much faster radiative emission of connected chromophores
as well as giant optical nonlinearities.
- Intraband relaxation in CdSe nanocrystals and the strong influence of the surface ligands
J. Chem. Phys. 123, 074709 (2005).
- Variable range hopping conduction in semiconductor nanocrystal solids, Phys. Rev. Lett. 92, 216802 (2004).
- Synthesis and optical characterization of Au/Ag core/shell nanorods, J. Phys. Chem. B 108, 5882 (2004).
- Light emission and amplification in charged CdSe quantum dots, J. Phys. Chem. B 108, 9027, (2004).
- Interband and Intraband Optical Studies of PbSe Colloidal Quantum Dots, J. Phys. Chem. B 106, 10634, 2002.
- Conducting n-type CdSe Nanocrystal solids, Science 300, 1277 (2003).
- Electrochromic nanocrystal quantum dots, Science, 201, 2390 (2001).
- N-type colloidal semiconductor nanocrystals, Nature, 407, 981 (2000).
updated 8/2006
Heinrich M. Jaeger
Ph.D., Minnesota, 1987.
Prof., Dept. Physics, James Franck Inst., and the College
Experimental condensed matter physics, mesoscopic physics, high-temperature superconductivity.
homepages: Prof. Jaeger; his research group
Nanoscale Physics. On size scales below typically one micrometer, metallic,
superconducting, and semiconducting structures display properties which differ
fundamentally from behavior on larger scales. In this so-called mesoscopic regime, the
quantum nature of electrons leads to novel behavior not present in the macroscopic limit.
We are investigating the electronic and magnetic properties of metallic and superconducting
nanostructures. This research explores the roles of carrier confinement, quantum fluctuations,
and disorder. We utilize experimental techniques such as cryogenic and high-magnetic field
measurements, scanning probe and electron microscopy, and electron-beam lithography. Current
research focuses on mechanisms for guided self-assembly of nanocrystal monolayers and
metal-copolymer nanocomposites, and on the emerging novel electronic transport behavior.
Granular Matter. Piles of dry grains of sand display a variety of behaviors that
differ strikingly from those of ordinary gases, liquids, or solids. Macroscopic granular
materials are typically found far from the most stable ("equilibrium") configurations.
Ordinary temperature is irrelevant in driving granular systems; instead, they exhibit
dynamic phase transitions in response to applied forces. An example is the transition from
solid- to liquid-like behavior at the onset of particle flow and avalanching down the slope
of a sandpile. In collaboration with Sidney Nagel, we have been investigating experimentally
the complex, non-linear dynamics of granular flow and find that the behavior of granular
materials has parallels in many other phenomena including magnetic flux creep in superconductors,
charge density waves, and relaxation in spin glasses. Our current research investigates
consequences of the inherently inhomogeneous force distributions inside granular matter, the
glassy settling behavior as the system explores phase space, spontaneous structure formation
and dynamic instabilities under applied stresses, and the propagation of energy and momentum
through these highly dissipative materials. We use capacitive probes, high-speed video, magnetic
resonance imaging (MRI), and x-ray tomography (at the
Advanced Photon Source) to probe non-invasively the behavior
of granular matter.
Nanoscale Physics
- Kinetically-Driven Self-Assembly of Highly-Ordered Nanocrystal Monolayers. Terry P. Bigioni, Xiao-Min Lin, Toan T. Nguyen, Eric Corwin, Thomas A. Witten, and Heinrich M. Jaeger. Nature Materials 5, 265-270 (2006).
- A model for the onset of transport in systems with distributed thresholds for conduction. Klara Elteto, Eduard G. Antonyan, T.T. Nguyen, and Heinrich M. Jaeger. Phys. Rev. B 71, 064206 (2005).
- Percolating Through Networks of Random Thresholds: Finite Temperature Electron Tunneling in Metal Nanocrystal Arrays. Raghuveer Parthasarathy, Xiao-Min Lin, Klara Elteto, T. F. Rosenbaum, and Heinrich M. Jaeger. Phys. Rev. Lett. 92, 076801 (2004).
- Hierarchical Self-Assembly of Metal Nanostructures on Diblock Copolymer Scaffolds. Ward A. Lopes and H.M. Jaeger. Nature. 414, 735, 2001.
Granular matter
- Sand, Jams and Jets. Heinrich M. Jaeger. Physics World 18, 34-39 (2005).
- Formation of Granular Jets Observed by High-Speed X-ray Radiography. John R. Royer, Eric I. Corwin, Andrew Flior, Maria-Luisa Cordero, Mark Rivers, Peter Eng, and Heinrich M. Jaeger. Nature Physics 1, 164-167 (2005).
- Structural signature of jamming in granular media. Eric Corwin, Heinrich Jaeger, and Sidney Nagel. Nature 435, 1075-1078 (2005).
- Intruders in the Dust: Air-Driven Granular Size Separation. Matthias E. Möbius, Xiang Cheng, Gregory Karczmar, Sidney R. Nagel, and Heinrich M. Jaeger. Phys. Rev. Lett., 93, 198001 (2004).
- Granular Solids, Liquids, and Gases. H.M. Jaeger, S.R. Nagel, and R.P. Behringer. Rev. Mod. Phys. 68, 1259, 1996.
updated 8/2006
Woowon Kang
Ph.D., Princeton, 1992.
Assoc. Prof., Dept. Physics, James Franck Inst., and the College
Experimental condensed matter physics, fractional quantum Hall effect, semi-conductor physics.
My research centers on the studies of novel, quantum mechanical effects in low-dimensional condensed matter systems. The collective response of a system consisting of many identical particles differs considerably from its single-particle behavior due to interaction between different particles. Unusual behaviors and phase transitions emerge as a classical system adiabatically enters the quantum regime. Model systems of interest include low-dimensional semiconductors and a class of charge-transfer molecular conductors. These systems serve as table-top testbed to study new types of ground states and excitations. Currently ongoing projects include:
- Tunneling between one dimensional, chiral edge states
- Spin physics in the fractional quantum Hall effect
- Superconductivity and spin density waves in molecular conductors
- Light emission in sonoluminescence
Prof. Kang has a home page.
- Hysteresis and Spin Transitions in the Fractional Quantum Hall Effect. H. Cho, J.B. Young, W. Kang, K.L. Campman, A.C. Gossard, M. Bichler, and W. Wegscheider. Phys. Rev. Lett. 81, 2522, 1998.
- Negative Hall Plateaus and Quantum Hall Effect in TMTSF2PF6. H. Cho and W. Kang. Phys. Rev. B 59, 9814, 1999.
- Quantum Hall Effect and Anomalous Transport in TMTSF2PF6. J. Eom, H. Cho and W. Kang. J. Phys. IV 9, 191, 1999.
- Quantum Hall Ferromagnetism in a Two-Dimensional Electron System. J. Eom, H. Cho, W. Kang, K.L. Campman, A.C. Gossard, M. Bichler, and W. Wegscheider. Science 289, 2320, 2000.
- Tunneling between the Edges of Two Lateral Quantum Hall Systems. W. Kang, H.L. Stormer, K.B. Baldwin, L.N. Pfeiffer, and K.W. West. Nature 403, 59, 2000.
- Hysteresis, Spin Transitions, and Magnetic Ordering in the Fractional Quantum Hall Effect. H. Cho, J.B. Young, W. Kang, K.L. Campman, A.C. Gossard, M. Bichler, and W. Wegscheider. Physica A 6 , 18, 2000 .
- Line emission in single-bubble sonoluminescence. J. B. Young, J.A. Nelson,
and W. Kang. Phys. Rev. Lett. 86, 2673, 2001.
updated 5/2001
Sidney R. Nagel
Ph.D., Princeton, 1974.
Stein-Freiler Distinguished Service Prof., Dept. Physics, James Franck Inst., and the College
Experimental physics, condensed-matter physics, non-linear dynamics.
Many complex phenomena are so familiar that we hardly realize that they defy our normal
intuition; we forget to ask whether or not they are understood. Examples of poorly understood
classical physics include the anomalous flow of granular material, the long messy tendrils left
by honey spooned from one dish to another, the pesky rings deposited by spilled coffee on a table
after the liquid evaporates or the common splash of a drop of liquid onto a countertop. Aside
from being uncommonly beautiful to see, many of these phenomena involve non-linear behavior where
the system is far from equilibrium. Although most of the world we know is beyond description by
equilibrium theories, we are still only at the threshold of learning how to deal with such deep
problems. Thus, these are phenomena which can lead the inquisitive into new realms of physics.
Problems such as these fuel much of my research effort.
I have worked on several different projects which involve a range of disciplines from
conventional solid-state physics to non-linear dynamics. I list here a few of the topics on
which my group is currently working:
Jamming. One emphasis of my work is to understand the properties of disordered materials.
Such materials have many common features which are different from their crystalline counterparts.
One example is of particular note. By varying some external parameter, these materials can become
structurally arrested - that is they jam. We are interested in understanding what controls the
onset of rigidity in a wide variety of situations. Do all jammed systems have a common set of
inherent properties? If so, can we learn about the nature of glasses (where the ability to flow
has been lost when the temperature is dropped to too low a value) by studying the jamming that
occurs in a granular material such as a sand pile as it suddenly stops flowing? In an effort to
deal with diverse phenomena where systems become stuck in a region far from equilibrium
(e.g., at the glass transition and in clogged granular materials flowing - unsuccessfully - through
a pipe), I have been investigating, along with Andrea Liu at Univ. of Pennsylvania, whether
there can be a more general way of looking at these systems in terms of a Jamming Phase Diagram.
Such a concept would relate the physics of granular materials with those of glasses.
Granular Materials. In collaboration with the group of Heinrich Jaeger,
we have been studying the properties of granular media. Despite their ubiquity and the simplicity
with which the can be described, we understand very little about how these materials (e.g., sand)
behave. In these studies we enter a new area of physics in which we are studying a statistical
system of many particles but where the temperature is totally irrelevant. Thus, these systems are
unavoidably always out of equilibrium, and we must come up with new concepts in order to understand
and predict their properties.
Glass Transition. We have been studying this transition using a variety of techniques
including neutron diffraction, specific heat spectroscopy, computer simulation, dielectric
susceptibility, and shear modulus. We have managed to produce a master curve onto which all the
dielectric data from all samples over 15 decades in frequency can be scaled. Such scaling has
important implications for the nature of the glass transition.
Singularities in Free-surface Flows. A drop falling from a faucet is a common example of
a liquid fissioning into two or more pieces. The cascade of structure that is produced in this process
is of uncommon beauty. As the drop falls, a long neck, connecting two masses of fluid, stretches out
and then breaks. What is the shape of the drop at the instant of breaking apart? Something dire must
happen to the mathematical description of the liquid at that point since the drop undergoes a
topological transition where it starts out as a single, connected fluid and ends up in two or more
separate pieces. This is an example of a finite-time singularity since the drop breakup occurs in
a short time after the drop becomes unstable and starts to fall. At the transition, a singularity
occurs since the radius of the neck holding the drop to the nozzle becomes vanishingly thin. As its
radius goes to zero, the curvature diverges and the surface tension forces become infinite. How can
such dramatic dynamics occur in something which had such smooth and innocuous initial conditions and
forcing terms? Using photographic techniques, we have been studying transitions such as these to
understand how the non-linearities in the governing equations (in this case the Navier-Stokes
equations) can be tamed and understood. Singularities of this kind occur in many areas of physics
from stellar structure to turbulence to bacterial colony growth. This drop breakup problem is one
of the simplest places to start an experiment which directly probes the singularity itself. In
collaboration with Wendy Zhang, we have uncovered
a variety of different singularities - some of which surprisingly retain a memory of their initial
conditions throughout the entire breakup process.
Encapsulation of Biological Cells for Transplantation. Using the fluid experiments of
the kind described above, in collaboration of
Milan Mrksich in our
Chemistry Department and
Dr. Marc Garfinkel in
our Department of Surgery we have invented a new procedure for encapsulating small particles.
This method may be particularly useful for coating biological cells for transplantation.
Splashing. How does a drop ol liquid splash when it hits a smooth dry solid surface
like a piece of glass? Our intuition tells us it must splash and eject thousands of tiny droplets.
We would expect the same behavior anywhere - here on Earth, on Mars and on the Moon. We would
be wrong! In collaboration with Wendy Zhang, we
have found that we can suppress splashing completely by removing the surrounding atmosphere.
A drop which splashes in Chicago would not necessarily splash on the top of Mt. Everest where
the pressure is less and would definitely not splash on the Moon which has no atmosphere.
- Physics at the Breakfast Table - or Waking Up to Physics (Klopsteg Memorial Lecture, August, 1998). S.R. Nagel. Am. J. Phys. 67, 17, 1999.
- Using Selective Withdrawal to Coat Micro Particles. I. Cohen, H. Li, J.L. Hougland, M. Mrksich, and S.R. Nagel. Science 292, 265, 2001.
- Jamming at zero temperature and zero applied stress: The epitome of disorder, C. S. O’Hern, L. E. Silbert, A. J. Liu and S. R. Nagel, Phys. Rev. E 68, 011306 (2003).
- Persistence of memory in drop break-up: The breakdown of universality, P. Doshi, I. Cohen, W. W. Zhang, M. Siegel, P. Howell, O. A. Basaran, and S. R. Nagel, Science 302, 1185 (2003).
- Drop Splashing on a Dry Smooth Surface, L. Xu, W. W. Zhang, and S. R. Nagel, Phys. Rev. Lett. 94, 184505 (2005).
- Vibrations and diverging length scales near the unjamming transition, L. E. Silbert, A. J. Liu and S. R. Nagel, Phys. Rev. Lett. 95, 098301 (2005).
- Structural signature of jamming in granular media, E. I. Corwin, H. M. Jaeger, and S. R. Nagel, Nature 435, 1075 (2005).
- Effects of compression on the vibrational modes of marginally jammed solids,” M. Wyart, L. E. Silbert, S. R. Nagel and T. A. Witten, Phys. Rev. E 72, 051306 (2005).
- Three-dimensional Shear in Granular Flow, X. Cheng, J. B. Lechman, A. Fernandez-Barbero, G. S. Grest, H. M. Jaeger, G. S. Karczmar, M. E. Möbius, and S. R. Nagel, Phys. Rev. Lett. 96, 038001 (2006).
- Stability and Growth of Single Myelin Figures, L.-N. Zou and S. R. Nagel, Phys. Rev. Lett. 96, 138301 (2006).
updated 8/2006
Thomas F. Rosenbaum
Ph.D., Princeton, 1982.
James Franck Prof., Dept. Physics, James Franck Inst., and the College
Experimental physics, solid state physics, low-temperature physics.
At temperatures near absolute zero, new collective phenomena become possible. The
quantum mechanical nature of materials is highlighted at the low temperatures, leading to
a different class of phase transitions and to states with unusual excitation spectra. I use
dilution refrigerator techniques to explore quantum magnets and glasses with connections
both to quantum phase transitions and to the encoding of information, metal-insulator
transitions with choreographed charge and spin degrees of freedom, new magnetoresistive
compounds, and exotic superconductivity. MilliKelvin temperatures often are combined with
symmetry-breaking fields (such as uniaxial stress or magnetic fields), diamond anvil cell
pressures, and x-ray and neutron scattering to help constrain theory on fundamental grounds.
These disparate topics are united by the theme of the interplay of correlation effects and
disorder and by the issue of how macroscopic order can emerge from microscopic disorder.
- MegaGauss Sensors, A. Husmann, J.B. Betts, G.S. Boebinger, A. Migliori, T.F. Rosenbaum, and M.-L. Saboungi. Nature 417, 421 (2002).
- Coherent Spin Oscillations in a Disordered Magnet, S. Ghosh, R. Parthasarathy, T.F. Rosenbaum, and G. Aeppli. Science 296, 2195 (2002).
- Quantum Fluctuations and the Closing of the Coulomb Gap in a Correlated Insulator, A.S. Roy, A.F.Th. Hoekstra, T.F. Rosenbaum, and R. Griessen, Phys. Rev. Lett. 89, 276402 (2002).
- Entangled Quantum State of Magnetic Dipoles, S. Ghosh, T.F. Rosenbaum, G. Aeppli, and S.N. Coppersmith, Nature 425, 48 (2003).
- High Resolution Study of Magnetic Ordering at Absolute Zero, M. Lee, A. Husmann, T.F. Rosenbaum, and G. Aeppli, Phys. Rev. Lett. 92, 187201 (2004).
- The Electron Glass in a Switchable Mirror, M. Lee, P. Oikonomou, P. Segalova, T.F. Rosenbaum, A.F.Th. Hoekstra and P.B. Littlewood, J. Phys.: Condens. Matter 17, L439 (2005).
- Quantum Phase Transition in a Spin Bath, H.M. Rønnow, R. Parthasarathy, J. Jensen, G. Aeppli, T.F. Rosenbaum, and D.F. McMorrow, Science 308, 389 (2005).
- Current Jets, Disorder and Linear Magnetoresistance in the Silver Chalcogenides, J. Hu, T.F. Rosenbaum and J.B. Betts, Phys. Rev. Lett. 95, 186603 (2005).
updated 8/2006
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