76 research outputs found

    Re-entrant ferroelectricity in liquid crystals

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    The ferroelectric (Sm C∗^*) -- antiferroelectric (Sm CA∗^*_A) -- reentrant ferroelectric (re Sm C∗^*) phase temperature sequence was observed for system with competing synclinic - anticlinic interactions. The basic properties of this system are as follows (1) the Sm C∗^* phase is metastable in temperature range of the Sm CA∗^*_A stability (2) the double inversions of the helix handedness at Sm C∗^* -- Sm CA∗^*_A and Sm CA∗^*_A% -- re-Sm C∗^* phase transitions were found (3) the threshold electric field that is necessary to induce synclinic ordering in the Sm CA∗^*_A phase decreases near both Sm CA∗^*_A -- Sm C∗^* and Sm CA∗^*_A -- re-Sm C∗^* phase boundaries, and it has maximum in the middle of the Sm CA∗^*_A stability region. All these properties are properly described by simple Landau model that accounts for nearest neighboring layer steric interactions and quadrupolar ordering only.Comment: 10 pages, 5 figures, submitted to PR

    Helical phases assembled from achiral molecules : Twist-bend nematic and helical filamentary B4 phases formed by mesogenic dimers

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    Funding Information: National Science Centre (Poland) under the grant no. 2016/22/A/ST5/00319. Special acknowledgement and thanks to professor Dong Ki Yoon's group for providing the AAO membranes.Peer reviewedPublisher PD

    Spontaneous chirality through mixing achiral components : A twist-bend nematic phase driven by hydrogen-bonding between unlike components

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    Acknowledgments: The work was supported by the National Science Centre (Poland) under the grant no. 2016/22/A/ST5/00319. RW gratefully acknowledges the Carnegie Trust for the Universities of Scotland for funding the award of a PhD scholarship.Peer reviewedPostprin

    Magnetic Liquid Crystals for Molecular Spintronics

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    The magnetic properties of Ni(II) and Cu(II) complexes were measured. In the case of Ni(II) samples strong enhancement of the magnetic susceptibility below 23 K was observed. The model of structural transition was proposed to explain this behavior

    Role of salicylic acid in acclimation to low temperature

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    Low temperature is one of the most important limiting factors for plant growth throughout the world. Exposure to low temperature may cause various phenotypic and physiological symptoms, and may result in oxidative stress, leading to loss of membrane integrity and to the impairment of photosynthesis and general metabolic processes. Salicylic acid (SA),phenolic compound produced by a wide range of plant species, a may participate in many physiological and metabolic reactions in plants. It has been shown that exogenous SA may provide protection against low temperature injury in various plant species, while various stress factors may also modify the synthesis and metabolism of SA. In the present review, recent results on the effects of SA and related compounds in processes leading to acclimation to low temperatures will be discussed
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