The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Xi Li - One of the best experts on this subject based on the ideXlab platform.

  • influence of a static magnetic field on the distribution of solute cu and interdendritic constitutional undercooling in directionally solidified al 4 5wt cu alloy
    Materials Letters, 2019
    Co-Authors: Annie Gagnoud, Yves Fautrelle, Xi Li
    Abstract:

    Abstract The 3D-CT technology and Rank Sort method are applied to investigate the influence of a static magnetic field on the morphology of the liquid/solid Interface and the distribution of the solute Cu in directionally solidified Al-4.5wt.%Cu alloy. The results reveal that cells/dendrites refine, and the results of numerical simulation confirm that the magnetic field forms thermoelectric (TE) magnetic convection, resulting in the enrichment of the solute Cu in the liquid ahead of the liquid/solid Interface. The cells/dendrites refinement under the magnetic field should be attributed to the increase of the interdendritic constitutional undercooling caused by the enhancement of the solute Cu.

  • Modification of liquid/solid Interface shape in directionally solidifying Al-Cu alloys by a transverse magnetic field
    Journal of Materials Science, 2013
    Co-Authors: Jiang Wang, Imants Kaldre, Henri Nguyen-Thi, Georges Salloum Abou Jaoude, Zhong-ming Ren, Yunbo Zhong, Nathalie Mangelinck-noël, Yves Fautrelle, Xi Li, Andris Bojarevics
    Abstract:

    Al-0.85wt%Cu and Al-2.5wt%Cu alloys were directionally solidified under different transverse magnetic field (TMF) intensities to investigate the influence of TMF on the liquid/solid Interface shape with respect to the various length scales appearing (planar, cellular, and dendritic Interfaces). Results show that planar and cellular Interfaces tilt to one side and then level off with increasing TMF although the dendritic Interface appears not to behave in this manner. In situ synchrotron X-ray imaging was applied during directional solidification of the Al-4wt%Cu alloy under a 0.08T TMF, revealing leveling of the initially sloped Interface. Solute redistribution, caused by thermoelectric magnetic convection (TEMC), responds to the changes in the Interface shape. Because different typical length scales should be used in estimating the velocity of TEMC for planar, cellular, and dendritic Interfaces, the maximum velocity of the convection ahead of the Interface is obtained under different TMF intensities; correspondingly, leveling of the Interface's degree of slop varies with TMF. © 2012 Springer Science+Business Media, LLC.

  • influence of thermoelectric effects on the solid liquid Interface shape and cellular morphology in the mushy zone during the directional solidification of al cu alloys under a magnetic field
    Acta Materialia, 2007
    Co-Authors: Xi Li, Yves Fautrelle
    Abstract:

    Abstract In this work thermoelectromagnetic convection (TEMC) is evaluated at different scales and the result shows that the effect of TEMC is different for different scales. To validate this analysis, Al–Cu hypoeutectic alloys were solidified directionally under a magnetic field, and both the Interface shape and cellular morphology in the mushy zone investigated. The experimental results show that a weak magnetic field ( B  ⩽ 0.5 T) has a significant affect on the cellular liquid–solid Interface and the cellular morphology. This is attributed to the TEMC caused by the interaction between the field and the thermoelectric (TE) current, which is consistent with the analysis. Under a higher magnetic field, the field causes the cells to break and makes the liquid–solid Interface uneven; these effects are attributed to the magnetic force and the TE torque.

Steven De Feyter - One of the best experts on this subject based on the ideXlab platform.

  • Dynamics in self-assembled organic monolayers at the liquid/solid Interface revealed by scanning tunneling microscopy.
    Chimia, 2020
    Co-Authors: Steven De Feyter, Hong Xu, Kunal Mali
    Abstract:

    The liquid/solid Interface provides an interesting medium for molecular self-assembly and scanning tunneling microscopy is the preferred technique to analyse the structural features of the surface-supported self-assembled monolayers in this medium. An interesting aspect is the phenomenon of molecular dynamics at the liquid/solid Interface. In this mini-review, we report on our efforts and strategies to investigate and even induce molecular dynamics at the liquid/solid Interface, bringing insight to various kinds of processes such as conformational, translational and adsorption/desorption dynamics.

  • Supramolecular Chemistry at the Liquid/Solid Interface
    MRS Proceedings, 2015
    Co-Authors: Steven De Feyter, Hiroshi Uji-i, Atsushi Miura, Wael Mamdouh, Jian Zhang, J.h. Van Esch, Ben L. Feringa, Albertus P. H. J. Schenning, E. W. Meijer, F. Wuerthner
    Abstract:

    The liquid/solid Interface provides an ideal environment to investigate self-assembly phenomena and scanning tunneling microscopy (SIM) is the preferred methodology to probe the structure and the properties of physisorbed monolayers on the nanoscale. Physisorbed monolayers are of relevance in areas such as lubrication, patterning of surfaces on the nanoscale, and thin film based organic electronic devices, to name a few. It's important to gain insight in the factors which control the ordering of molecules at the liquid/solid Interface in view of the targeted properties. STM provides detailed insight into the importance of molecule-substrate (epitaxy) and molecule-molecule interactions to direct the ordering of both achiral and chiral molecules on the atomically flat surface. The electronic properties of the self-assembled physisorbed molecules can be probed by taking advantage of the operation principle of STM, revealing spatially resolved intramolecular differences within these physisorbed molecules.

  • Manifestations of Non‐Planar Adsorption Geometries of Lead Pyrenocyanine at the Liquid‐Solid Interface
    Chemistry-an Asian Journal, 2013
    Co-Authors: Kunal S. Mali, Lukas Zöphel, Oleksandr Ivasenko, Klaus Müllen, Steven De Feyter
    Abstract:

    : In this work, we provide evidence for multiple non-planar adsorption geometries of a novel pyrenocyanine derivative at the Liquid-Solid Interface under ambient conditions. When adsorbed at the organic Liquid-Solid Interface, lead pyrenocyanine forms well-ordered monolayers that exhibit peculiar non-periodic contrast variation. The different contrast of the adsorbed molecules is attributed to dissimilar adsorption geometries which arise from the non-planar conformation of the molecules. The non-planarity of the molecular backbone in turn arises due to a combination of the angularly extended pyrene subunits and the presence of the large lead ion, which is too big to fit inside the central cavity and thus is located out of the aromatic plane. The two possible locations of the lead atom, namely below and above the aromatic plane, could be identified as depression and protrusion in the central cavity, respectively. The manifestation of such multiple adsorption geometries on the structure of the resultant monolayer is discussed in detail. The packing density of these 2D arrays of molecules could be tuned by heating of the sample wherein the molecular packing changes from a low-density, pseudo six-fold symmetric to a high-density, two-fold symmetric arrangement. Finally, a well-ordered two-component system could be constructed by incorporating C60 molecules in the adlayer of lead pyrenocyanine at the Liquid-Solid Interface.

  • Chiral Induction and Amplification in Supramolecular Systems at the Liquid–Solid Interface
    ChemPhysChem, 2013
    Co-Authors: Hong Xu, Albertus P. H. J. Schenning, Elke Ghijsens, Subi J. George, Martin Wolffs, Željko Tomović, Steven De Feyter
    Abstract:

    : Chiral induction and amplification in surface-confined supramolecular monolayers are investigated at the Liquid-Solid Interface. Scanning tunneling microscopy (STM) proves that achiral molecules can self-assemble into globally chiral patterns through a variety of approaches, including induction by chiral solvents or by a novel chiral amplification method. Our study demonstrates the aptness of both approaches, which have already been applied to (supramolecular) polymers in solution, to create chiral supramolecular monolayers at the Liquid-Solid Interface.

  • Molecular Patterning at a Liquid/Solid Interface: The Foldamer Approach
    Langmuir, 2011
    Co-Authors: Min Li, Steven De Feyter, Cristian Gobbo, Rienk Eelkema, Bernard Vanaverbeke, Roberto Lazzaroni, Jan H. Van Esch
    Abstract:

    Molecular patterning has received a lot of attention in the past decade; however, the functionalization of these surface-confined 2D patterns on the nanoscale level remains a challenge. Assembling 2D patterns from oligomeric foldamers turns out to be an interesting approach to accomplishing the controlled positioning of functional elements. We designed a family of peptidomimetic foldamers bearing a 2D turn element folding at the liquid/solid Interface. The turning element was developed while studying derivatives with one turning unit. Furthermore, folding was found to be induced by the confinement of the surface. This achievement paves the way for the design of foldamers with multiple turns, providing a higher versatility in the functionalization of nanopatterns.

Yves Fautrelle - One of the best experts on this subject based on the ideXlab platform.

  • influence of a static magnetic field on the distribution of solute cu and interdendritic constitutional undercooling in directionally solidified al 4 5wt cu alloy
    Materials Letters, 2019
    Co-Authors: Annie Gagnoud, Yves Fautrelle, Xi Li
    Abstract:

    Abstract The 3D-CT technology and Rank Sort method are applied to investigate the influence of a static magnetic field on the morphology of the liquid/solid Interface and the distribution of the solute Cu in directionally solidified Al-4.5wt.%Cu alloy. The results reveal that cells/dendrites refine, and the results of numerical simulation confirm that the magnetic field forms thermoelectric (TE) magnetic convection, resulting in the enrichment of the solute Cu in the liquid ahead of the liquid/solid Interface. The cells/dendrites refinement under the magnetic field should be attributed to the increase of the interdendritic constitutional undercooling caused by the enhancement of the solute Cu.

  • Modification of liquid/solid Interface shape in directionally solidifying Al-Cu alloys by a transverse magnetic field
    Journal of Materials Science, 2013
    Co-Authors: Jiang Wang, Imants Kaldre, Henri Nguyen-Thi, Georges Salloum Abou Jaoude, Zhong-ming Ren, Yunbo Zhong, Nathalie Mangelinck-noël, Yves Fautrelle, Xi Li, Andris Bojarevics
    Abstract:

    Al-0.85wt%Cu and Al-2.5wt%Cu alloys were directionally solidified under different transverse magnetic field (TMF) intensities to investigate the influence of TMF on the liquid/solid Interface shape with respect to the various length scales appearing (planar, cellular, and dendritic Interfaces). Results show that planar and cellular Interfaces tilt to one side and then level off with increasing TMF although the dendritic Interface appears not to behave in this manner. In situ synchrotron X-ray imaging was applied during directional solidification of the Al-4wt%Cu alloy under a 0.08T TMF, revealing leveling of the initially sloped Interface. Solute redistribution, caused by thermoelectric magnetic convection (TEMC), responds to the changes in the Interface shape. Because different typical length scales should be used in estimating the velocity of TEMC for planar, cellular, and dendritic Interfaces, the maximum velocity of the convection ahead of the Interface is obtained under different TMF intensities; correspondingly, leveling of the Interface's degree of slop varies with TMF. © 2012 Springer Science+Business Media, LLC.

  • influence of thermoelectric effects on the solid liquid Interface shape and cellular morphology in the mushy zone during the directional solidification of al cu alloys under a magnetic field
    Acta Materialia, 2007
    Co-Authors: Xi Li, Yves Fautrelle
    Abstract:

    Abstract In this work thermoelectromagnetic convection (TEMC) is evaluated at different scales and the result shows that the effect of TEMC is different for different scales. To validate this analysis, Al–Cu hypoeutectic alloys were solidified directionally under a magnetic field, and both the Interface shape and cellular morphology in the mushy zone investigated. The experimental results show that a weak magnetic field ( B  ⩽ 0.5 T) has a significant affect on the cellular liquid–solid Interface and the cellular morphology. This is attributed to the TEMC caused by the interaction between the field and the thermoelectric (TE) current, which is consistent with the analysis. Under a higher magnetic field, the field causes the cells to break and makes the liquid–solid Interface uneven; these effects are attributed to the magnetic force and the TE torque.

Johannes A. A. W. Elemans - One of the best experts on this subject based on the ideXlab platform.

  • Little exchange at the liquid/solid Interface: defect-mediated equilibration of physisorbed porphyrin monolayers
    Chemical Communications, 2011
    Co-Authors: Michiel J. J. Coenen, Melissa Cremers, Duncan Den Boer, Fieke J. Van Den Bruele, Tony Khoury, Maxine Sintic, Maxwell J. Crossley, Willem J. P. Van Enckevort, Bas L. M. Hendriksen, Johannes A. A. W. Elemans
    Abstract:

    The transition from low to high density 2D surface structures of copper porphyrins at a liquid/solid Interface requires specific defects at which nearly all exchange of physisorbed molecules with those dissolved in the supernatant occurs.

  • Axial ligand control over monolayer and bilayer formation of metal-salophens at the liquid–solid Interface
    Chemical Communications, 2010
    Co-Authors: Johannes A. A. W. Elemans, Michiel J. J. Coenen, Duncan Den Boer, Sander J. Wezenberg, Eduardo C. Escudero-adán, Jordi Benet-buchholz, Sylvia Speller, Arjan W. Kleij, Steven De Feyter
    Abstract:

    Nickel salophens exclusively form monolayers at a liquid–solid Interface, while in contrast zinc salophens mainly self-assemble into bilayers via axial ligand self-coordination which can be disrupted by the addition of pyridine axial ligands.

  • Structure and function revealed with submolecular resolution at the liquid–solid Interface
    Soft Matter, 2009
    Co-Authors: Johannes A. A. W. Elemans, Steven De Feyter
    Abstract:

    The liquid–solid Interface is a unique medium to support the self-assembly of molecules into surface-confined networks. Non-covalent interactions are key in forming these two-dimensional (2D) architectures, and a deep understanding is crucial for successful 2D crystal engineering. Scanning tunnelling microscopy is the tool of choice to reveal the structure and function of these patterns with subnanometre resolution. A recent success is the formation of 2D nanoporous molecular patterns and their host–guest chemistry. However, this is not the only functionality addressed by this review. Surface-confined molecular architectures at the liquid–solid Interface are also relevant in the field of molecular electronics. Furthermore, inducing and probing chemical reactivity at the single-molecule level at the liquid–solid Interface might turn out to be one of the most exciting developments.

  • real time single molecule imaging of oxidation catalysis at a liquid solid Interface
    Nature Nanotechnology, 2007
    Co-Authors: Bas Hulsken, Tony Khoury, Maxwell J. Crossley, Richard Van Hameren, J W Gerritsen, Pall Thordarson, Alan E Rowan, Roeland J M Nolte, Johannes A. A. W. Elemans
    Abstract:

    Many chemical reactions are catalysed by metal complexes, and insight into their mechanisms is essential for the design of future catalysts. A variety of conventional spectroscopic techniques are available for the study of reaction mechanisms at the ensemble level, and, only recently, fluorescence microscopy techniques have been applied to monitor single chemical reactions carried out on crystal faces1 and by enzymes2,3,4. With scanning tunnelling microscopy (STM) it has become possible to obtain, during chemical reactions, spatial information at the atomic level5,6,7,8,9. The majority of these STM studies have been carried out under ultrahigh vacuum, far removed from conditions encountered in laboratory processes. Here we report the single-molecule imaging of oxidation catalysis by monitoring, with STM, individual manganese porphyrin catalysts, in real time, at a liquid–solid Interface. It is found that the oxygen atoms from an O2 molecule are bound to adjacent porphyrin catalysts on the surface before their incorporation into an alkene substrate.

  • Real-time single-molecule imaging of oxidation catalysis at a liquid–solid Interface
    Nature Nanotechnology, 2007
    Co-Authors: Bas Hulsken, Johannes A. A. W. Elemans, Tony Khoury, Maxwell J. Crossley, Richard Van Hameren, J W Gerritsen, Pall Thordarson, Alan E Rowan, Roeland J M Nolte, Sylvia Speller
    Abstract:

    Many chemical reactions are catalysed by metal complexes, and insight into their mechanisms is essential for the design of future catalysts. A variety of conventional spectroscopic techniques are available for the study of reaction mechanisms at the ensemble level, and, only recently, fluorescence microscopy techniques have been applied to monitor single chemical reactions carried out on crystal faces^ 1 and by enzymes^ 2 , 3 , 4 . With scanning tunnelling microscopy (STM) it has become possible to obtain, during chemical reactions, spatial information at the atomic level^ 5 , 6 , 7 , 8 , 9 . The majority of these STM studies have been carried out under ultrahigh vacuum, far removed from conditions encountered in laboratory processes. Here we report the single-molecule imaging of oxidation catalysis by monitoring, with STM, individual manganese porphyrin catalysts, in real time, at a liquid–solid Interface. It is found that the oxygen atoms from an O_2 molecule are bound to adjacent porphyrin catalysts on the surface before their incorporation into an alkene substrate.

Michael Thompson - One of the best experts on this subject based on the ideXlab platform.

  • slip and coupling phenomena at the liquid solid Interface
    Physical Chemistry Chemical Physics, 2004
    Co-Authors: Jonathan S Ellis, Michael Thompson
    Abstract:

    The no-slip boundary condition, as a precept of interfacial fluid dynamics, constitutes a central dogma amongst some physicists and engineers. However, over the past decade, it has become a topic of some controversy because of the proliferation of theoretical and experimental evidence for the existence of slip, especially at micro- and nanoscopic scales. In this review, we consider the models, techniques, and results, both experimental and by simulation, concerning interfacial slip and mechanical coupling at solid–liquid (outer slip), and adsorbate–substrate (inner slip) Interfaces. Outer slip is a viscous process, normally described by a planar discontinuity between the upper layer of surface particles and the adjacent liquid layer. A number of factors can lead to slip, including surface–liquid affinity, high shear rates, surface roughness, and the elasticity of any intermediary film layer. Inner slip can be a viscoelastic process, and is related to adhesion and friction. Although it has received little attention, it will be important when dealing with self-assembled monolayers and more complex biosensor applications. Finally, we consider stochastic coupling as an aspect of the concept of slip.