Author
Laurence Lemelle
Other affiliations: École Normale Supérieure, Centre national de la recherche scientifique, University of Sassari
Bio: Laurence Lemelle is an academic researcher from École normale supérieure de Lyon. The author has contributed to research in topics: Cosmic dust & Interplanetary dust cloud. The author has an hindex of 22, co-authored 63 publications receiving 3113 citations. Previous affiliations of Laurence Lemelle include École Normale Supérieure & Centre national de la recherche scientifique.
Papers published on a yearly basis
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Donald E. Brownlee1, Peter Tsou2, Jérôme Aléon3, Conel M. O'd. Alexander4 +182 more•Institutions (57)
TL;DR: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study, and preliminary examination shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin.
Abstract: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.
886 citations
United States Naval Research Laboratory1, Brookhaven National Laboratory2, Space Sciences Laboratory3, Kingsborough Community College4, University of Münster5, Michigan State University6, Osaka University7, Jet Propulsion Laboratory8, Lawrence Livermore National Laboratory9, Kobe University10, European Synchrotron Radiation Facility11, Washington University in St. Louis12, University of Chicago13, École normale supérieure de Lyon14, University of New Mexico15, Kyushu University16, University of Tokyo17, University of Washington18, Lawrence Berkeley National Laboratory19, University of Jena20, University of Hawaii21, American Museum of Natural History22, Case Western Reserve University23, University of Hyogo24, United States Geological Survey25, Imperial College London26, State University of New York System27, Open University28, Stanford University29
TL;DR: The bulk of the comet 81P/Wild 2 samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger ferromagnesian silicates, Fe-Ni sulfides,Fe-Ni metal, and accessory phases.
Abstract: The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.
644 citations
State University of New York at Plattsburgh1, European Synchrotron Radiation Facility2, Lawrence Livermore National Laboratory3, Goethe University Frankfurt4, Stanford University5, Open University6, University of Washington7, Smithsonian Institution8, Dartmouth College9, Lawrence Berkeley National Laboratory10, École normale supérieure de Lyon11, Washington University in St. Louis12, University of California, Berkeley13, Centre national de la recherche scientifique14, Max Planck Society15, Rutgers University16, University of Antwerp17, Natural History Museum18, University of Chicago19, university of lille20, Kyushu University21, National Institute of Advanced Industrial Science and Technology22, California Institute of Technology23, University of Georgia24, University of New Mexico25, University of Münster26, United States Naval Research Laboratory27, Cold Regions Research and Engineering Laboratory28, Osaka University29, Ghent University30
TL;DR: The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.
Abstract: We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed (similar to 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.
224 citations
University of California, Berkeley1, United States Naval Research Laboratory2, Lawrence Berkeley National Laboratory3, Goethe University Frankfurt4, State University of New York at Plattsburgh5, Jacobs Engineering Group6, Heidelberg University7, Carnegie Institution for Science8, Field Museum of Natural History9, University of Leicester10, University of Washington11, University of Kent12, Ghent University13, University of New Mexico14, European Synchrotron Radiation Facility15, University of Chicago16, Washington University in St. Louis17, Max Planck Society18, International Space Science Institute19, Natural History Museum20, Argonne National Laboratory21, École normale supérieure de Lyon22, university of lille23, Ames Research Center24, University of Stuttgart25, Jet Propulsion Laboratory26
TL;DR: The Stardust Interstellar Dust Collector captured seven particles and returned to Earth for laboratory analysis have features consistent with an origin in the contemporary interstellar dust stream and more than 50 spacecraft debris particles were also identified as discussed by the authors.
Abstract: Seven particles captured by the Stardust Interstellar Dust Collector and returned to Earth for laboratory analysis have features consistent with an origin in the contemporary interstellar dust stream. More than 50 spacecraft debris particles were also identified. The interstellar dust candidates are readily distinguished from debris impacts on the basis of elemental composition and/or impact trajectory. The seven candidate interstellar particles are diverse in elemental composition, crystal structure, and size. The presence of crystalline grains and multiple iron-bearing phases, including sulfide, in some particles indicates that individual interstellar particles diverge from any one representative model of interstellar dust inferred from astronomical observations and theory.
176 citations
TL;DR: The use of gold nanoparticles as biological probes requires the improvement of colloidal stability and the presence of DHLA on gold particles allows their functionalization by the electroluminescent luminol through amine coupling reactions assisted by 1-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide.
Abstract: The use of gold nanoparticles as biological probes requires the improvement of colloidal stability. Dihydrolipoic acid (DHLA), a dithiol obtained by the reduction of thioctic acid, appears therefore very attractive for the stabilization and the further functionalization of gold nanoparticles because DHLA is characterized by a carboxylic acid group and two thiol functions. The ionizable carboxylic acid groups ensure, for pH 8, the water solubility of DHLA-capped gold (Au@DHLA) nanoparticles, prepared by the Brust protocol, and the stability of the resulting colloid by electrostatic repulsions. Moreover almost all DHLA, adsorbed onto gold, adopts a conformation allowing their immobilization by both sulfur ends. It is proved by sulfur K-edge X-ray absorption near edge structure spectroscopy, which appears as an appropriate tool for determining the chemical form of sulfur atoms present in the organic monolayer. Such a grafting renders the DHLA monolayers more resistant to displacement by dithiothreitol than mercaptoundecanoic acid monolayers. The presence of DHLA on gold particles allows their functionalization by the electroluminescent luminol through amine coupling reactions assisted by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. As a luminol-functionalized particle is nine times as bright as a single luminol molecule, the use of the particles as a biological probe with a lower threshold of detection is envisaged.
160 citations
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TL;DR: The physics of locomotion of biological and synthetic microswimmers, and the collective behavior of their assemblies, are reviewed and the hydrodynamic aspects of swimming are addressed.
Abstract: Locomotion and transport of microorganisms in fluids is an essential aspect of life. Search for food, orientation toward light, spreading of off-spring, and the formation of colonies are only possible due to locomotion. Swimming at the microscale occurs at low Reynolds numbers, where fluid friction and viscosity dominates over inertia. Here, evolution achieved propulsion mechanisms, which overcome and even exploit drag. Prominent propulsion mechanisms are rotating helical flagella, exploited by many bacteria, and snake-like or whip-like motion of eukaryotic flagella, utilized by sperm and algae. For artificial microswimmers, alternative concepts to convert chemical energy or heat into directed motion can be employed, which are potentially more efficient. The dynamics of microswimmers comprises many facets, which are all required to achieve locomotion. In this article, we review the physics of locomotion of biological and synthetic microswimmers, and the collective behavior of their assemblies. Starting from individual microswimmers, we describe the various propulsion mechanism of biological and synthetic systems and address the hydrodynamic aspects of swimming. This comprises synchronization and the concerted beating of flagella and cilia. In addition, the swimming behavior next to surfaces is examined. Finally, collective and cooperate phenomena of various types of isotropic and anisotropic swimmers with and without hydrodynamic interactions are discussed.
1,220 citations
TL;DR: Simulation of the early Solar System shows how the inward migration of Jupiter to 1.5 au, and its subsequent outward migration, lead to a planetesimal disk truncated at 1’au; the terrestrial planets then form from this disk over the next 30–50 million years, with an Earth/Mars mass ratio consistent with observations.
Abstract: Jupiter and Saturn formed in a few million years from a gas-dominated protoplanetary disk, and were susceptible to gas-driven migration of their orbits on timescales of only approximately 100,000 years. Hydrodynamic simulations show that these giant planets can undergo a two-stage, inward-then-outward, migration. The terrestrial planets finished accreting much later and their characteristics, including Mars' small mass, are best reproduced by starting from a planetesimal disk with an outer edge at about one astronomical unit from the Sun (1 AU is the Earth-Sun distance). Here we report simulations of the early Solar System that show how the inward migration of Jupiter to 1.5 AU, and its subsequent outward migration, lead to a planetesimal disk truncated at 1 AU; the terrestrial planets then form from this disk over the next 30-50 million years, with an Earth/Mars mass ratio consistent with observations. Scattering by Jupiter initially empties but then repopulates the asteroid belt, with inner-belt bodies originating between 1 and 3 AU and outer-belt bodies originating between and beyond the giant planets. This explains the significant compositional differences across the asteroid belt. The key aspect missing from previous models of terrestrial planet formation is the substantial radial migration of the giant planets, which suggests that their behaviour is more similar to that inferred for extrasolar planets than previously thought.
1,174 citations
TL;DR: In this paper, the authors review the current state of the art as CT transforms from a qualitative diagnostic tool to a quantitative one, including the use of iterative reconstruction strategies suited to specific segmentation tasks and emerging methods that provide more insight than conventional attenuation based tomography.
Abstract: X-ray computer tomography (CT) is fast becoming an accepted tool within the materials science community for the acquisition of 3D images. Here the authors review the current state of the art as CT transforms from a qualitative diagnostic tool to a quantitative one. Our review considers first the image acquisition process, including the use of iterative reconstruction strategies suited to specific segmentation tasks and emerging methods that provide more insight (e.g. fast and high resolution imaging, crystallite (grain) imaging) than conventional attenuation based tomography. Methods and shortcomings of CT are examined for the quantification of 3D volumetric data to extract key topological parameters such as phase fractions, phase contiguity, and damage levels as well as density variations. As a non-destructive technique, CT is an ideal means of following structural development over time via time lapse sequences of 3D images (sometimes called 3D movies or 4D imaging). This includes information nee...
1,009 citations
TL;DR: A mini-review of fabrication strategies for AuNPs is presented and a selection of recent applications of these materials in bionanotechnology is highlighted.
Abstract: Gold nanoparticles (AuNPs) are important components for biomedical applications. AuNPs have been widely employed for diagnostics, and have seen increasing use in the area of therapeutics. In this mini-review, we present fabrication strategies for AuNPs and highlight a selection of recent applications of these materials in bionanotechnology.
988 citations
TL;DR: In this article, the authors review the physics of locomotion of biological and synthetic microswimmers, and the collective behavior of their assemblies, including synchronization and the concerted beating of flagella and cilia.
Abstract: Locomotion and transport of microorganisms in fluids is an essential aspect of life. Search for food, orientation toward light, spreading of off-spring, and the formation of colonies are only possible due to locomotion. Swimming at the microscale occurs at low Reynolds numbers, where fluid friction and viscosity dominates over inertia. Here, evolution achieved propulsion mechanisms, which overcome and even exploit drag. Prominent propulsion mechanisms are rotating helical flagella, exploited by many bacteria, and snake-like or whip-like motion of eukaryotic flagella, utilized by sperm and algae. For artificial microswimmers, alternative concepts to convert chemical energy or heat into directed motion can be employed, which are potentially more efficient. The dynamics of microswimmers comprises many facets, which are all required to achieve locomotion. In this article, we review the physics of locomotion of biological and synthetic microswimmers, and the collective behavior of their assemblies. Starting from individual microswimmers, we describe the various propulsion mechanism of biological and synthetic systems and address the hydrodynamic aspects of swimming. This comprises synchronization and the concerted beating of flagella and cilia. In addition, the swimming behavior next to surfaces is examined. Finally, collective and cooperate phenomena of various types of isotropic and anisotropic swimmers with and without hydrodynamic interactions are discussed.
983 citations