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  1. Article ; Online: Soft-matter physics: Ferromagnetic ferrofluids.

    Clark, Noel A

    Nature

    2013  Volume 504, Issue 7479, Page(s) 229–230

    Language English
    Publishing date 2013-12-15
    Publishing country England
    Document type Comment ; News
    ZDB-ID 120714-3
    ISSN 1476-4687 ; 0028-0836
    ISSN (online) 1476-4687
    ISSN 0028-0836
    DOI 10.1038/504229a
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    Zs.A 26: Show issues Location:
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  2. Article ; Online: Topological defect coarsening in quenched smectic-C films analyzed using artificial neural networks.

    Chowdhury, Ravin A / Green, Adam A S / Park, Cheol S / Maclennan, Joseph E / Clark, Noel A

    Physical review. E

    2022  Volume 107, Issue 4-1, Page(s) 44701

    Abstract: Mechanically quenching a thin film of smectic-C liquid crystal results in the formation of a dense array of thousands of topological defects in the director field. The subsequent rapid coarsening of the film texture by the mutual annihilation of defects ... ...

    Abstract Mechanically quenching a thin film of smectic-C liquid crystal results in the formation of a dense array of thousands of topological defects in the director field. The subsequent rapid coarsening of the film texture by the mutual annihilation of defects of opposite sign has been captured using high-speed, polarized light video microscopy. The temporal evolution of the texture has been characterized using an object-detection convolutional neural network to determine the defect locations, and a binary classification network customized to evaluate the brush orientation dynamics around the defects in order to determine their topological signs. At early times following the quench, inherent limits on the spatial resolution result in undercounting of the defects and deviations from expected behavior. At intermediate to late times, the observed annihilation dynamics scale in agreement with theoretical predictions and simulations of the 2D XY model.
    Language English
    Publishing date 2022-08-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2844562-4
    ISSN 2470-0053 ; 2470-0045
    ISSN (online) 2470-0053
    ISSN 2470-0045
    DOI 10.1103/PhysRevE.107.044701
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  3. Article ; Online: New examples of ferroelectric nematic materials showing evidence for the antiferroelectric smectic-Z phase.

    Nacke, Pierre / Manabe, Atsutaka / Klasen-Memmer, Melanie / Chen, Xi / Martinez, Vikina / Freychet, Guillaume / Zhernenkov, Mikhail / Maclennan, Joseph E / Clark, Noel A / Bremer, Matthias / Giesselmann, Frank

    Scientific reports

    2024  Volume 14, Issue 1, Page(s) 4473

    Abstract: We present a new ferroelectric nematic material, 4-((4'-((trans)-5-ethyloxan-2-yl)-2',3,5,6'-tetrafluoro-[1,1'-biphenyl]-4-yl)difluoromethoxy)-2,6-difluorobenzonitrile (AUUQU-2-N) and its higher homologues, the molecular structures of which include ... ...

    Abstract We present a new ferroelectric nematic material, 4-((4'-((trans)-5-ethyloxan-2-yl)-2',3,5,6'-tetrafluoro-[1,1'-biphenyl]-4-yl)difluoromethoxy)-2,6-difluorobenzonitrile (AUUQU-2-N) and its higher homologues, the molecular structures of which include fluorinated building blocks, an oxane ring, and a terminal cyano group, all contributing to a large molecular dipole moment of about 12.5 D. We observed that AUUQU-2-N has three distinct liquid crystal phases, two of which were found to be polar phases with a spontaneous electric polarization P
    Language English
    Publishing date 2024-02-23
    Publishing country England
    Document type Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-024-54832-0
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  4. Book ; Online: A self-assembled periodic nanoporous framework in aqueous solutions of the DNA tetramer GCCG

    Smith, Gregory P. / Fraccia, Tommaso P. / Zhu, Chenhui / Bellini, Tommaso / Clark, Noel A.

    2023  

    Abstract: The collective behavior of the shortest DNA oligomers in high concentration aqueous solutions is an unexplored frontier of DNA science and technology. Here we broaden the realm of DNA nanoscience by demonstrating that single-component aqueous solutions ... ...

    Abstract The collective behavior of the shortest DNA oligomers in high concentration aqueous solutions is an unexplored frontier of DNA science and technology. Here we broaden the realm of DNA nanoscience by demonstrating that single-component aqueous solutions of the DNA 4-base oligomer GCCG can spontaneously organize into three-dimensional (3D) periodic mesoscale frameworks. This oligomer can form B-type double helices by Watson-Crick (WC) pairing, into tiled brickwork-like duplex strands, which arrange into mutually parallel arrays and form the nematic and columnar liquid crystal phases, as is typical for long WC chains. However, at DNA concentrations above 400mg/mL, these solutions nucleate and grow an additional mesoscale framework phase, comprising a periodic network on a three dimensional body-centered cubic (BCC) lattice. This lattice is an array of nodes (valence-8, each formed by a pair of quadruplexes of GCCG terminal Gs), connected with a separation of 6.6 nm by struts (6-GCCG-long WC duplexes). This 3D-ordered DNA framework is of low density (DNA volume fraction ~0.2), but, due to its 3D crystal structure, is osmotically incompressible over its phase range. Atomistic simulations confirm the stability of such structures, which promise to form the basis of novel families of simply and inexpensively made nanoscale frameworks for templating and selection applications.

    Comment: 33 pages, 8 figures
    Keywords Condensed Matter - Materials Science ; Condensed Matter - Soft Condensed Matter
    Subject code 612
    Publishing date 2023-12-30
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Polar in-plane surface orientation of a ferroelectric nematic liquid crystal: Polar monodomains and twisted state electro-optics.

    Chen, Xi / Korblova, Eva / Glaser, Matthew A / Maclennan, Joseph E / Walba, David M / Clark, Noel A

    Proceedings of the National Academy of Sciences of the United States of America

    2021  Volume 118, Issue 22

    Abstract: We show that surface interactions can vectorially structure the three-dimensional polarization field of a ferroelectric fluid. The contact between a ferroelectric nematic liquid crystal and a surface with in-plane polarity generates a preferred in-plane ... ...

    Abstract We show that surface interactions can vectorially structure the three-dimensional polarization field of a ferroelectric fluid. The contact between a ferroelectric nematic liquid crystal and a surface with in-plane polarity generates a preferred in-plane orientation of the polarization field at that interface. This is a route to the formation of fluid or glassy monodomains of high polarization without the need for electric field poling. For example, unidirectional buffing of polyimide films on planar surfaces to give quadrupolar in-plane anisotropy also induces macroscopic in-plane polar order at the surfaces, enabling the formation of a variety of azimuthal polar director structures in the cell interior, including uniform and twisted states. In a π-twist cell, obtained with antiparallel, unidirectional buffing on opposing surfaces, we demonstrate three distinct modes of ferroelectric nematic electro-optic response: intrinsic, viscosity-limited, field-induced molecular reorientation; field-induced motion of domain walls separating twisted states of opposite chirality; and propagation of polarization reorientation solitons from the cell plates to the cell center upon field reversal. Chirally doped ferroelectric nematics in antiparallel-rubbed cells produce Grandjean textures of helical twist that can be unwound via field-induced polar surface reorientation transitions. Fields required are in the 3-V/mm range, indicating an in-plane polar anchoring energy of
    Language English
    Publishing date 2021-04-30
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2104092118
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    Zs.A 1148: Show issues Location:
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  6. Article ; Online: Correction: Surface alignment of ferroelectric nematic liquid crystals.

    Caimi, Federico / Nava, Giovanni / Barboza, Raouf / Clark, Noel A / Korblova, Eva / Walba, David M / Bellini, Tommaso / Lucchetti, Liana

    Soft matter

    2022  Volume 18, Issue 27, Page(s) 5126

    Abstract: Correction for 'Surface alignment of ferroelectric nematic liquid crystals' by Federico ... ...

    Abstract Correction for 'Surface alignment of ferroelectric nematic liquid crystals' by Federico Caimi
    Language English
    Publishing date 2022-07-13
    Publishing country England
    Document type Published Erratum
    ZDB-ID 2191476-X
    ISSN 1744-6848 ; 1744-683X
    ISSN (online) 1744-6848
    ISSN 1744-683X
    DOI 10.1039/d2sm90088b
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  7. Article ; Online: Understanding and Manipulating Helical Nanofilaments in Binary Systems with Achiral Dopants.

    Cao, Yu / Tan, Tianyi / Walba, David M / Clark, Noel A / Ungar, Goran / Zhu, Chenhui / Zhang, Lei / Liu, Feng

    Nano letters

    2022  Volume 22, Issue 11, Page(s) 4569–4575

    Abstract: Here, we report the relationship between helical pitch of the helical nanofilament (HNF) phase formed by bent-core molecule NOBOW and the concentration of achiral dopants 5CB and octane, using linearly polarized resonant soft X-ray scattering (RSoXS). ... ...

    Abstract Here, we report the relationship between helical pitch of the helical nanofilament (HNF) phase formed by bent-core molecule NOBOW and the concentration of achiral dopants 5CB and octane, using linearly polarized resonant soft X-ray scattering (RSoXS). Utilizing theory-based simulation, which fits well with the experiments, the molecular helices in the filament were probed and the superstructure of helical 5CB directed by groove of HNFs was observed. Quantitative pitch determination with RSoXS reveals that helical pitch variation is related to 5CB concentration with no temperature dependence. Doping rodlike immiscible 5CB led to a pitch shortening of up to 30%, which was attributed to a change in interfacial tension. By shedding light not only on phase behavior of binary systems but also enabling control over pitch length, our work may benefit various applications of HNF-containing binary systems, including optical rotation devices, circularly polarized light emitters, and chirality transfer agents.
    MeSH term(s) Computer Simulation ; Liquid Crystals/chemistry ; Temperature
    Language English
    Publishing date 2022-05-18
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, Non-U.S. Gov't
    ISSN 1530-6992
    ISSN (online) 1530-6992
    DOI 10.1021/acs.nanolett.2c01525
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  8. Article ; Online: Scanned conical illumination as a probe of electro-optic retro-reflection.

    Alshomrany, Ali S / Nguyen, Z / Maclennan, Joseph E / Clark, Noel A

    Optics express

    2019  Volume 27, Issue 13, Page(s) 18383–18398

    Abstract: We describe a prototype element for use in probing electro-optic retro-reflection in sensor applications, illuminating a planar-aligned nematic liquid crystal electro-optic cell with convergent light having a single, tunable angle of incidence (tunable ... ...

    Abstract We describe a prototype element for use in probing electro-optic retro-reflection in sensor applications, illuminating a planar-aligned nematic liquid crystal electro-optic cell with convergent light having a single, tunable angle of incidence (tunable conical illumination). This illumination is generated using a 100X, high numerical aperture, long working-distance microscope objective under conditions of extreme spherical aberration. The electro-optic effect observed is multiple-beam optical interference between polarized reflections from the two bounding plates of the cell, rendered tunable with voltage-controlled refractive index changes induced by molecular reorientation of the liquid crystal. Characterization of the reflectivity vs. angle of incidence and applied voltage enables identification of conditions of high-contrast, low power, electro-optic reflectivity control applicable to fiber optics.
    Language English
    Publishing date 2019-06-27
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.27.018383
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  9. Article ; Online: The smectic Z

    Chen, Xi / Martinez, Vikina / Korblova, Eva / Freychet, Guillaume / Zhernenkov, Mikhail / Glaser, Matthew A / Wang, Cheng / Zhu, Chenhui / Radzihovsky, Leo / Maclennan, Joseph E / Walba, David M / Clark, Noel A

    Proceedings of the National Academy of Sciences of the United States of America

    2023  Volume 120, Issue 8, Page(s) e2217150120

    Abstract: We have structurally characterized the liquid crystal (LC) phase that can appear as an intermediate state when a dielectric nematic, having polar disorder of its molecular dipoles, transitions to the almost perfectly polar-ordered ferroelectric nematic. ... ...

    Abstract We have structurally characterized the liquid crystal (LC) phase that can appear as an intermediate state when a dielectric nematic, having polar disorder of its molecular dipoles, transitions to the almost perfectly polar-ordered ferroelectric nematic. This intermediate phase, which fills a 100-y-old void in the taxonomy of smectic LCs and which we term the "smectic Z
    Language English
    Publishing date 2023-02-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2217150120
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  10. Book ; Online: Thermotropic reentrant isotropy and antiferroelectricity in the ferroelectric nematic material RM734

    Chen, Xi / Shuai, Min / Zhong, Bingchen / Martinez, Vikina / Korblova, Eva / Glaser, Matthew A. / Maclennan, Joseph E. / Walba, David M. / Clark, Noel A.

    2023  

    Abstract: We report a transition from the ferroelectric nematic liquid crystal ($N_F$) phase to a lower-temperature, antiferroelectric fluid phase having reentrant isotropic symmetry ($I_A$), in the liquid crystal compound RM734 doped with small concentrations of ... ...

    Abstract We report a transition from the ferroelectric nematic liquid crystal ($N_F$) phase to a lower-temperature, antiferroelectric fluid phase having reentrant isotropic symmetry ($I_A$), in the liquid crystal compound RM734 doped with small concentrations of the ionic liquids BMIM or EMIM. Even a trace amount of ionic liquid dopant facilitates the kinetic pathway for the transition from the $N_F$ to the $I_A$, enabling simple cooling to produce this isotropic fluid phase rather than resulting in crystallization. The $I_A$ was also obtained in the absence of specific ionic liquid doping by appropriate temperature cycling in three distinct, as-synthesized-and-purified batches of RM734, two commercial and one from our laboratory. An additional birefringent, lamellar-modulated, antiferroelectric phase with the director parallel to the layers, resembling the smectic $Z_A$, is found between the paraelectric and ferroelectric nematic phases in RM734/BMIM mixtures.

    Comment: 45 pages, including Supplementary Information
    Keywords Condensed Matter - Soft Condensed Matter
    Subject code 660
    Publishing date 2023-09-10
    Publishing country us
    Document type Book ; Online
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