Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals

Materials showing coupling phenomena between magnetism and (ferro)electricity, i.e., magnetoelectric effects, have attracted a great deal of attention due ...

Osaka University

The present study was designed to evaluate the metabolism of chylomicron and chylomicron remnants by measuring serum apolipoprotein B-48 (apoB-48) levels in 335 normolipidemic and 253 hyperlipidemic subjects using a novel ELISA system. The distribution of fasting serum apoB-48 levels in normolipidemic subjects varied widely, ranging from <1 to >24 microgram/ml (mean, 5.2 +/- 3.8 microgram/ml; median, 3.9 microgram/ml). Serum apoB-48 levels correlated with serum triglyceride (TG) concentrations (r = 0.45, P < 0.001), but not with total cholesterol levels. Serum apoB-48 levels were 7 to 18 times higher in patients with Type I, Type V, and Type III hyperlipidemia, and only slightly higher in patients with Type IIa, Type IIb, and Type IV hyperlipidemia, compared with normolipidemic subjects. The calculated apoB-48/TG ratio was elevated only in patients with dysbetalipoproteinemia (apoE2/2 phenotype). In normolipidemic subjects, oral fat loading resulted in about 2-fold increase in serum apoB-48 levels, with a peak level recorded at 3-4 h postloading, and then returned to the baseline level within 6 h. On the other hand, in patients with dysbetalipoproteinemia, serum apoB-48 levels did not change considerably. Our results indicate that serum apoB-48 is a very useful parameter for evaluating lipoprotein metabolism in exogenous pathways.

Measurement of fasting serum apoB-48 levels in normolipidemic and hyperlipidemic subjects by ELISA.

To identify the origin of the magneto-LC effects, which refer to the enhancement of intermolecular magnetic interactions in the LC phases of all-organic radical compounds, we have designed and synthesized H-bonded all-organic radical compounds showing nematic and cholesteric phases for the first time. They show stronger magneto-LC effects than in the same LC phases of analogous covalent-bonded all-organic radical LC compounds. Variable-temperature electron paramagnetic resonance spectroscopy of the hydrogen-bonded compounds reveals that the inhomogeneous intermolecular contacts give rise to the magneto-LC effects.

Magneto-LC effects in hydrogen-bonded all-organic radical liquid crystal.

We have designed and synthesized a new chiral paramagnetic liquid crystalline compound with a nitroxide radical moiety showing chiral smectic A (SmA*) and C (SmC*) phases. This compound shows pretransitional layer contraction prior to the SmA*-to-SmC* phase transition in the cooling run. Electron paramagnetic resonance spectroscopy, X-ray diffraction analysis, and polarized optical microscopy reveal that a temperature-dependent conformational change is responsible for the pretransitional layer contraction.

Pretransitional layer contraction at the chiral smectic A-to-chiral smectic C phase transition of a chiral nitroxide radical.

Omnidirectional laser action in W/O/W emulsion with CLC shells is demonstrated. The emulsion, in which the helical axis of the CLC phase is normal to the surface, is successfully fabricated by using a microfluidic device. The whole emulsion system with dispersed core-shell droplets with a CLC shell can serve as a flexible omnidirectional resonator for dye lasers.

Controlled fabrication and photonic structure of cholesteric liquid crystalline shells.

Nanosheets (∼1 nm) are formed using a nonionic hyperswollen lyotropic lamellar phase as a template. The accumulation and reaction of ingredients in the highly separated (several hundred nm) bilayers in the hyperswollen lyotropic lamellar phase should result in very thin nanosheets. This method could be applied to the synthesis of a wide variety of two-dimensional organic and inorganic materials. 

Nanosheet Formation in Hyperswollen Lyotropic Lamellar Phases.

The kinetic/thermodynamic origin of preferential enrichment (PE), which is a spontaneous enantiomeric resolution phenomenon applicable to racemic crystals, is described. The mechanism of PE, which was unveiled with respect to the first-generation of chiral organic compounds showing PE, has been interpreted in terms of a nonlinear complexity phenomenon including two unique processes: a solvent-assisted solid-to-solid polymorphic transition and subsequent selective redissolution of the excess one enantiomer from the transformed disordered crystals into the mother liquor. The present works confirm that PE takes place because of the unique nonlinear solubility properties of the two enantiomers after the occurrence of a polymorphic transition under PE crystallization conditions at high supersaturation. Furthermore, a ternary phase diagram that is consistent with the mechanism of PE is proposed. 

A Kinetic/Thermodynamic Origin of Regular Chiral Fluctuation or Symmetry Breaking Unique to Preferential Enrichment.

Microfluidic devices, which can continuously fabricate single emulsion with monodispersed droplets having a pore diameter of more than 100 μm in large numbers, can be applied to manufacture ordered macroporous films. 3D ordered macroporous films with a diameter of more than 100 μm can be fabricated using ordered arrays of the monodispersed droplets as templates of the macropores, which are self-assembled in the space between two parallel flat glass plates. As the gap between the glass plates increases, the number of the layer increases. Furthermore, in the case with two or more layers, the lattice structure of the macroporous films also changes due to the confinement effects.

3D Lattice Structure Control of Ordered Macroporous Material by Self-Assembly of Liquid Droplets.

The evaluation of the transport rates of hydrophilic substances is important in agricultural and pharmaceutical chemistry and in the cosmetics and food-processing industries. Although there are some estimation methods focusing on the diffusion of the substances through the oil phase of the W/O/W core-shell double emulsions (oil microcapsules), all of them take several hours or days. This long-time measurement has a risk of rupture of the oil microcapsules, which causes significant errors. If it were possible to measure the transport rate of substances in the oil phase of the oil microcapsules in real time, the risk of rupture could be reduced. Here, we propose a new estimation method for the transport rates of hydrogen peroxide (HO) in the oil phase of an oil microcapsule for real-time estimation by means of chemiluminescence (CL) emission of the luminol reaction. We theoretically give the relationship among the CL emission intensity, diffusion coefficient, microcapsule size, and experimental time and successfully estimate the diffusion coefficient of HO in the oil phase of the oil microcapsule from the experimental data. Moreover, we discuss the dependence of the permeation of HO through the oil phase on the concentration of the oil-soluble surfactant; the difference in the permeation rate is likely to be attributed not to the diffusion coefficient but to the partition coefficient of HO in the oil microcapsule.

Real-Time Observation of Hydrogen Peroxide Transport through the Oil Phase in a W/O/W Double Emulsion with Chemiluminescence Emission.

With a view to developing a theranostic nanomedicine for targeted drug delivery systems visible by magnetic resonance (MR) imaging, robust metal-free magnetic nanoemulsions (mean particle size less than 20 nm) consisting of a biocompatible surfactant and hydrophobic, low molecular weight 2,2,5-trimethyl-5-(4-alkoxy)phenylpyrrolidine-N-oxyl radicals were prepared in pH 7.4 phosphate-buffered saline (PBS). The structure of the nanoemulsions was characterized by electron paramagnetic resonance spectroscopy, and dynamic light scattering and small-angle neutron-scattering measurements. The nanoemulsions showed high colloidal stability, low cytotoxicity, enough reduction resistance to excess ascorbic acid, and sufficient contrast enhancement in the proton longitudinal relaxation time (T ) weighted MR images in PBS in vitro (and preliminarily in vivo). Furthermore, the hydrophobic anticancer drug paclitaxel could be encapsulated inside the nanoparticles, and the resulting paclitaxel-loaded nanoemulsions were efficiently incorporated into HeLa cells to suppress cell growth.

Preparation of Robust Metal-Free Magnetic Nanoemulsions Encapsulating Low-Molecular-Weight Nitroxide Radicals and Hydrophobic Drugs Directed Toward MRI-Visible Targeted Delivery.

Carbon dioxide (CO) capture and storage (CCS) technologies have been attracting attention in terms of tackling with global warming. To date, various CO capture technologies including solvents, membranes, cryogenics, and solid adsorbents have been proposed. Currently, a liquid adsorption method for CO using amine solution (monoethanolamine) has been practically used. However, this liquid phase CO adsorption process requires heat regeneration, and it can cause many problems such as corrosion of equipment and degradation of the solution. Meanwhile, solid adsorption methods using porous materials are more advantageous over the liquid method at these points. In this context, we here evaluated if hydrogen titanate (HTiO) nanotubes and the surface modification effectively capture CO. For this aim, we first developed a facile synthesis method of HTiO nanotubes different from any conventional methods. Briefly, they were converted from the precursors-amorphous TiO nanoparticles at room temperature (25 °C). We then determined the outer and the inner diameters of the HTiO nanotubes as 3.0 and 0.7 nm, respectively. It revealed that both values were much smaller than the reported ones; thus the specific surface area showed the highest value (735 m/g). Next, the outer surface of HTiO nanotubes was modified using ethylenediamine to examine if CO adsorption capacity increases. The ethylendiamine-modified HTiO nanotubes showed a higher CO adsorption capacity (50 cm/g at 0 °C, 100 kPa). We finally concluded that the higher CO adsorption capacity could be explained, not only by the high specific surface area of the nanotubes but also by tripartite hydrogen bonding interactions among amines, CO, and OH groups on the surface of HTiO.

Low Temperature Synthesized HTiO Nanotubes with a High CO Adsorption Property by Amine Modification.

The supramolecular chirality of aggregates consisting of achiral trans-bis(salicylaldiminato)Ni complex 1 bearing long alkyl chains can be generated and controlled precisely in a chiral nematic liquid-crystalline (LC) solvent, whereas the complex naturally forms achiral gel fibers in achiral nematic LC solvents and crystals in nonmesogenic solvents. The direction and intensity of the helicity of the gel fibers of 1 in the LC gel state can be adjusted by means of the nature of the helical twisting and the concentration of the chiral dopants. Helicity control was precisely detected in the circular dichroism (CD) spectra of LC gels and by direct SEM observation of the dried gel fibers. XRD analysis revealed that the flexibility of the herringbone-based lamellar alignment of this complex is the key to the LC-specific gelation and helicity control of the gel fibers.

Helicity Control of Supramolecular Gel Fibers Consisting of an Achiral Ni Complex in a Chiral Nematic Solvent.

We synthesized new chiral all-organic liquid crystalline (LC) compounds with nitroxide (NO) and hydroxy (OH) groups, which form intermolecular hydrogen bonds between the NO and OH groups. The LC compounds show hexagonal columnar phases at room temperature, which solidify as LC glasses at low temperature. The experimental magnetic susceptibility of each of the compounds in the LC and isotropic phases is larger than that theoretically estimated on the simple assumption about the amount of the spins, whereas it accords with the theoretical one in the LC glass state. It is called magneto-LC effects. The difference between experimental and theoretical magnetic susceptibilities gradually increases as temperature increases through the LC glass state-to-LC phase transition. It suggests that molecular mobility is one of the origins of the magneto-LC effects.

Yoshiaki Uchida

Division of Chemical Engineering,
Graduate School of Engineering Science,
Division of Chemical Engineering, Graduate School of Engineering Science

Osaka University

Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals

Yoshiaki Uchida

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Division of Chemical Engineering,Graduate School of Engineering Science,Division of Chemical Engineering, Graduate School of Engineering Science

Osaka University

Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals

Division of Chemical Engineering,
Graduate School of Engineering Science,
Division of Chemical Engineering, Graduate School of Engineering Science