Convincing evidence for the Halperin-Lubensky-Ma effect at the N-SmA transition in alkyloxycyanobiphenyl binary mixtures via a high-resolution birefringence study.

We present new high-resolution experimental data for the temperature behavior of optical birefringence for a series of mixture of the liquid crystals octyloxycyanobiphenyl (8OCB) and nonyloxycyanobiphenyl (9OCB) by using a rotating analyzer technique. The birefringence data have been used to probe the temperature dependence of the nematic order parameter [Formula: see text]. We have then arrived at values for possible entropy discontinuities at the nematic-smectic A transition temperature [Formula: see text] from the detailed inspection of [Formula: see text] data in the immediate vicinity of [Formula: see text]. The 9OCB mole fraction dependence of the obtained reduced entropy discontinuities has been shown to be well fitted with a crossover function which is itself consistent with the mean-field free energy expression with a non-zero cubic term arising from the Halperin-Lubensky-Ma (HLM) coupling. The obtained results are in good accordance with existing results from adiabatic scanning calorimetry (ASC). Our birefringence results and determined entropy discontinuities (consistent with calorimetry results) are in striking contrast with the recent birefringence results of Barman et al. (Phase Transit. 91, 58 (2018) published online 16 Aug. 2017) claiming second-order nematic-to-smectic A transitions for all mixtures. In this paper we present a possible explanation for this discrepancy. We have also extracted the effective critical exponent values [Formula: see text] characterizing the critical fluctuations near the N-SmA transition for all compositions by using the fact that the temperature derivative of the order parameter [Formula: see text] near [Formula: see text] exhibits the same power-law divergence as the specific heat capacity. Measurable latent heat values were extracted from optical birefringence data for mole fractions of 9OCB where the [Formula: see text] values are as low as 0.2, which is substantially lower than the tricritical value [Formula: see text]. This is qualitatively different from what has been observed so far in other liquid-crystal systems. Together with ASC data, these pecuilarities of the 8OCB+9OCB system render further convincing evidence for the presence of the HLM coupling effect at the N-SmA transition phase transition line.

Liquid crystal elastomer foams with elastic properties specifically engineered as biodegradable brain tissue scaffolds.

Tissue regeneration requires 3-dimensional (3D) smart materials as scaffolds to promote transport of nutrients. To mimic mechanical properties of extracellular matrices, biocompatible polymers have been widely studied and a diverse range of 3D scaffolds have been produced. We propose the use of responsive polymeric materials to create dynamic substrates for cell culture, which goes beyond designing only a physical static 3D scaffold. Here, we demonstrated that lactone- and lactide-based star block-copolymers (SBCs), where a liquid crystal (LC) moiety has been attached as a side-group, can be crosslinked to obtain Liquid Crystal Elastomers (LCEs) with a porous architecture using a salt-leaching method to promote cell infiltration. The obtained SmA LCE-based fully interconnected-porous foams exhibit a Young modulus of 0.23 ± 0.07 MPa and a biodegradability rate of around 20% after 15 weeks both of which are optimized to mimic native environments. We present cell culture results showing growth and proliferation of neurons on the scaffold after four weeks. This research provides a new platform to analyse LCE scaffold-cell interactions where the presence of liquid crystal moieties promotes cell alignment paving the way for a stimulated brain-like tissue.

Systemic associations and prevalence of exfoliation syndrome in patients scheduled for cataract surgery.

PURPOSE: To study the frequency of exfoliation syndrome (XFS) and its association with intraocular pressure (IOP) and systemic diseases in patients with age-related cataract scheduled for surgery. METHODS: All 1480 cataract patients had a comprehensive systemic and eye examination, including slit-lamp biomicroscopy before and after mydriasis, IOP measurement, gonioscopy, and fundus examination. RESULTS: The percentage of XFS among patients scheduled for cataract surgery was 16.4, with no gender difference (p=0.833). The mean age of XFS patients (74.3+/-7.0 years) was significantly higher when compared to the ones without XFS (66.5+/-10.9 years) (p<0.001). XFS was unilateral in 41.3% of the subjects and bilateral in 58.7%. The number of subjects with XFS increased significantly with aging (p<0.001) (OR=1.093, 95% CI=1.073-1.14) (p<0.001). The most common type of cataract was nuclear in the XFS group (33.5%) and 24.6% of patients with mature cataract had XFS. In the XFS group, 11.2% of the subjects had glaucoma, which was statistically higher than the non-XFS group (4.6%) (p<0.001) (OR=2.67, 95% CI=1.65-4.32). Eighty-four patients had glaucoma and 27 of them (32.1%) had exfoliative glaucoma. The only systemic disease that was found to be associated with XFS was coronary heart disease with an OR of 1.49 (95% CI=1.068-2.072) (p=0.019). CONCLUSIONS: XFS is a common problem in the aging cataract population of Turkey and increased IOP, glaucomatous optic neuropathy, and coronary heart disease occur more frequently in patients with XFS compared with subjects without XFS.

Gastrointestinal involvement in POEMS syndrome: a novel clinical manifestation.

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) is characterised by a rare multisystem disorder of unknown pathogenesis. Although its pathophysiology is not well understood, overexpression of proinflammatory cytokines has been implicated. Gastrointestinal system disorders have not been reported among the components of the syndrome. A case is reported of POEMS syndrome with gastrointestinal involvement shown by gastrointestinal endoscopy.