3D Continuous Water Nanosheet as a Gyroid Minimal Surface Formed by Bicontinuous Cubic Liquid-Crystalline Zwitterions

Co-organization of amphiphilic zwitterions and bis­(trifluoromethanesulfonyl)­imide led to the formation of bicontinuous cubic liquid-crystalline structures having 3D continuous hydrophilic gyroid minimal surface. The gyroid surface, incorporating a small amount of water, provided extremely thin but macroscopically continuous water nanosheet with a thickness of approximately 5 Å. The water nanosheet functioned as alignment free proton conduction pathway

Maintenance-Free Cellulose Solvents Based on Onium Hydroxides

Here, we report maintenance-free cellulose solvents that dissolve much cellulose within a few minutes under mild conditions even in the presence of water. We have examined a series of aqueous solutions of tetraalky-phosphonium and tetraalkyl-ammonium hydroxides to clarify the effect of cation species on cellulose dissolving. Aqueous solutions of the many hydroxides examined here were found to dissolve cellulose at room temperature, and electrostatic interaction and/or steric hindrance of component ions are suggested to affect the cellulose-dissolving ability. In spite of increasing water content after dissolution of wet cellulose, the water content automatically reduced to less than 60% just by keeping the filtrated solution in the air. The solvation state of cellulose in aqueous onium hydroxide solutions is discussed with ¹³C NMR chemical shift of cellobiose signals in these solutions. They dissolve cellulose only when the ¹³C NMR signal of the carbon atom at the 12 position of cellobiose is 64.8 ppm or larger in the hydroxide aqueous solution

Isolation and Quantification of Polyamide Cyclic Oligomers in Kitchen Utensils and Their Migration into Various Food Simulants

<div><p>Small amounts of cyclic monomers and oligomers are present in polyamide (PA)-based kitchen utensils. In this study, we isolated eight PA-based cyclic monomers and oligomers from kitchen utensils made from PA6 (a polymer of ε-caprolactam) and PA66 (a polymer of 1,6-diaminohexane and adipic acid). Their structures were identified using high-resolution mass spectrometry and ¹H- and ¹³C-nuclear magnetic resonance spectroscopy, and their residual levels in PA-based kitchen utensils and degree of migration into food simulants were quantified by high-performance liquid chromatography/mass spectrometry using purchased PA6 monomer and isolated PA66 monomers, and isolated PA6 and PA66 oligomers as calibration standards. Their total residual levels among 23 PA-based kitchen utensils made from PA6, PA66, and copolymers of PA6 and PA66 (PA6/66) ranged from 7.8 to 20 mg/g. Using water, 20% ethanol, and olive oil as food simulants, the total migration levels of the PA monomers and oligomers ranged from 0.66 to 100 μg/cm² under most examined conditions. However, the total migration levels of the PA66 monomer and oligomers from PA66 and PA6/66 kitchen utensils into 20% ethanol at 95°C were very high (1,700 and 2,200 μg/cm², respectively) due to swelling by high-temperature ethanol.</p></div

Migration levels of PA cyclic monomers and oligomers from the sesame grinder (PA6) and cake server (PA6/66) into three simulants at 60°C.

<p>Migration levels of PA cyclic monomers and oligomers from the sesame grinder (PA6) and cake server (PA6/66) into three simulants at 60°C.</p

Hydrolysis of CPL to 6-aminohexanoic acid.

<p>(A) Before and (B) after hydrolysis.</p

Condensation reactions of PA6 and PA66.

<p>Condensation reactions of PA6 and PA66.</p

¹H NMR Evaluation of Polar and Nondeuterated Ionic Liquids for Selective Extraction of Cellulose and Xylan from Wheat Bran

Cellulose and xylan, extracted from wheat bran with polar ionic liquids (ILs), were quantified using ¹H NMR spectroscopy. Both No-D NMR and solvent suppression techniques were applied to realize direct analysis of extracts in nondeuterated ILs. As models of extracts, mixtures of cellulose and xylan dissolved in ILs were measured with ¹H NMR spectroscopy. There was a linear relation between mixing ratio and specific peak area of each polysaccharide. Extracts from bran in ILs were analyzed with the obtained calibration curve. This NMR analysis was confirmed to be applicable to three representative ILs used for extraction of polysaccharides. A relation between extracted amount and extraction conditions was obtained

LC/MS total ion chromatograms (SCAN mode) of the extracts.

<p>(A) Ladle 1 (PA6), (B) turner 1 (PA66), and (C) cake scraper (PA6/66). LC/MS: liquid chromatography/mass spectrometry.</p

Retention times and MS (SIR mode) conditions for quantification.

<p>Retention times and MS (SIR mode) conditions for quantification.</p

Structures of PA monomers and oligomers.

<p>The numbers for CPL, PA6 cyclic dimer, and PA66 cyclic monomer represent the positions shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0159547#pone.0159547.t001" target="_blank">Table 1</a>.</p