101 research outputs found
Re-entrant ferroelectricity in liquid crystals
The ferroelectric (Sm C) -- antiferroelectric (Sm C) -- 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 C stability (2) the double inversions of the helix
handedness at Sm C -- Sm C and Sm C% -- re-Sm C phase
transitions were found (3) the threshold electric field that is necessary to
induce synclinic ordering in the Sm C phase decreases near both Sm
C -- Sm C and Sm C -- re-Sm C phase boundaries, and it has
maximum in the middle of the Sm C 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
Pharmacokinetic study of tianeptine and its active metabolite MC5 in rats following different routes of administration using a novel liquid chromatography tandem mass spectrometry analytical method
Hydrogen bonding and the design of twist-bend nematogens
Acknowledgements The work was supported by the National Science Centre (Poland) under the grant no. 2016/22/A/ST5/00319. RW gratefully thanks the Carnegie Trust for the Universities of Scotland for the award of a PhD Scholarship (2015-2018). The Erasmus programme is thanked for supporting a study visit for CAC to Warsaw. Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author statement Rebecca Walker: Investigation, Formal analysis, Validation, Visualisation, Writing – Original Draft, Writing – Reviewing and Editing Damian Pociecha: Visualisation, Investigation, Formal analysis Catriona Crawford: Investigation, Formal analysis John MD Storey: Resources, Supervision Ewa Gorecka: Investigation, Formal analysis, Resources, Supervision Corrie T Imrie: Conceptualization, Supervision, Resources, Writing – Reviewing and EditingPeer reviewedPostprin
Critical behavior of the optical birefringence at the nematic to twist bend nematic phase transition
This research was supported by the National Science Centre (Poland) under the grant no. 2016/22/A/ST5/00319. NV acknowledges the support of the Slovenian Research Agency (ARRS), through the research programme P1-0055.Peer reviewedPublisher PD
Flexoelectricity and piezoelectricity - reason for rich variety of phases in antiferroelectric liquid crystals
The free energy of antiferroelectric liquid crystal which takes into account
polar order explicitly is presented. Steric, van der Waals, piezoelectric and
flexoelectric interactions to the nearest layers and dipolar electrostatic
interactions to the nearest and to the next nearest layers induce indirect tilt
interactions with chiral and achiral properties, which extend to the third and
to the fourth nearest layers. Chiral indirect interactions between tilts can be
large and induce helicoidal modulations even in systems with negligible chiral
van der Waals interactions. If indirect chiral interactions compete with chiral
van der Waals interactions, the helix unwinding is possible. Although strength
of microscopic interactions change monotonically with decreasing temperature,
effective interlayer interactions change nonmonotonically and give rise to
nonmonotouous change of modulation period through various phases. Increased
enatiomeric excess i.e. increased chirality changes the phase sequence.Comment: 4 pages, 1 figur
Helical phases assembled from achiral molecules : Twist-bend nematic and helical filamentary B4 phases formed by mesogenic dimers
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
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
A novel, pan-PDE inhibitor exerts anti-fibrotic effects in human lung fibroblasts via inhibition of TGF- signaling and activation of cAMP/PKA signaling
Phosphodiesterase (PDE) inhibitors are currently a widespread and extensively studied group of anti-inflammatory and anti-fibrotic compounds which may find use in the treatment of numerous lung diseases, including asthma and chronic obstructive pulmonary disease. Several PDE inhibitors are currently in clinical development, and some of them, e.g., roflumilast, are already recommended for clinical use. Due to numerous reports indicating that elevated intracellular cAMP levels may contribute to the alleviation of inflammation and airway fibrosis, new and effective PDE inhibitors are constantly being sought. Recently, a group of 7,8-disubstituted purine-2,6-dione derivatives, representing a novel and prominent pan-PDE inhibitors has been synthesized. Some of them were reported to modulate transient receptor potential ankyrin 1 (TRPA1) ion channels as well. In this study, we investigated the effect of selected derivatives (832-a pan-PDE inhibitor, 869-a TRPA1 modulator, and 145-a pan-PDE inhibitor and a weak TRPA1 modulator) on cellular responses related to airway remodeling using MRC-5 human lung fibroblasts. Compound 145 exerted the most considerable effect in limiting fibroblast to myofibroblasts transition (FMT) as well as proliferation, migration, and contraction. The effect of this compound appeared to depend mainly on its strong PDE inhibitory properties, and not on its effects on TRPA1 modulation. The strong anti-remodeling effects of 145 required activation of the cAMP/protein kinase A (PKA)/cAMP response element-binding protein (CREB) pathway leading to inhibition of transforming growth factor type β1 (TGF-β1) and Smad-dependent signaling in MRC-5 cells. These data suggest that the TGF-β pathway is a major target for PDE inhibitors leading to inhibitory effects on cell responses involved in airway remodeling. These potent, pan-PDE inhibitors from the group of 7,8-disubstituted purine-2,6-dione derivatives, thus represent promising anti-remodeling drug candidates for further research
Magnetic Liquid Crystals for Molecular Spintronics
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
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