Recognition and Stabilization of Unsaturated Fatty Acids by a Polyaromatic Receptor

Selective recognition of natural fatty acids is intrinsically difficult owing to the long, flexible, and poorly interactive hydrocarbon chains. Inspired by biological recognition systems, we herein demonstrate the exclusive binding of a monounsaturated fatty acid by an artificial polyaromatic receptor from a mixture of the unsaturated and corresponding saturated substrates (i.e., oleic and stearic acids) in water. The selectivity stems from multiple CH–π/π–π interactions between the host framework and the guest in its roughly coiled conformation. Moreover, competitive binding experiments elucidate higher binding affinities of the receptor for oligo‐ and polyunsaturated fatty acids (e.g., α‐linolenic acid and EPA). Within the receptor, the biosubstrates are remarkably stabilized against air, light, and heat owing to the polyaromatic shielding effect.     

Self-organized near-field etching of the sidewalls of glass corrugations

Using soda-lime glass with a nano-stripe pattern as a test specimen, we demonstrated self-organized near-field etching with a continuum-wave laser (λ=532 nm) light source. Atomic force microscopy confirmed that near-field etching decreases the flank roughness of the corrugations as well as the roughness of the flat surface.     

Facile synthesis and catalytic activity of MoS(2)/TiO(2) by a photodeposition-based technique and its oxidized derivative MoO(3)/TiO(2) with a unique photochromism

UV-light irradiation to TiO(2) in an aqueous ethanol solution of (NH(4))(2)MoS(4) under deaerated conditions has yielded molybdenum(IV) sulfide nanoparticles on a TiO(2) surface (MoS(2)/TiO(2)) to be transformed into molybdenum(VI) oxide species highly dispersed at a molecular level by a subsequent heating at 773K in air (m-MoO(3)/TiO(2)). In HCOOH aqueous solutions, the MoS(2)/TiO(2) system exhibits a high level of photocatalytic activity for H(2) generation, while the m-MoO(3)/TiO(2) system shows unique photochromism.     

Synergistic catalysis of metal-organic framework-immobilized Au-Pd nanoparticles in dehydrogenation of formic acid for chemical hydrogen storage

Bimetallic Au-Pd nanoparticles (NPs) were successfully immobilized in the metal-organic frameworks (MOFs) MIL-101 and ethylenediamine (ED)-grafted MIL-101 (ED-MIL-101) using a simple liquid impregnation method. The resulting composites, Au-Pd/MIL-101 and Au-Pd/ED-MIL-101, represent the first highly active MOF-immobilized metal catalysts for the complete conversion of formic acid to high-quality hydrogen at a convenient temperature for chemical hydrogen storage. Au-Pd NPs with strong bimetallic synergistic effects have a much higher catalytic activity and a higher tolerance with respect to CO poisoning than monometallic Au and Pd counterparts.     

Photodeposition of Ag2S quantum dots and application to photoelectrochemical cells for hydrogen production under simulated sunlight

UV light irradiation of TiO(2) (λ > 320 nm) in a mixed solution of AgNO(3) and S(8) has led to the formation of Ag(2)S quantum dots (QDs) on TiO(2), while Ag nanoparticles (NPs) are photodeposited without S(8). Photoelectrochemical measurements indicated that the Ag(2)S photodeposition proceeds via the preferential reduction of Ag(+) ions to Ag(0), followed by the chemical reaction with S(8). The application of this in situ photodeposition technique to mesoporous (mp) TiO(2) nanocrystalline films coated on fluorine-doped SnO(2) (FTO) electrodes enables formation of Ag(2)S QDs (Ag(2)S/mp-TiO(2)/FTO). Ag(2)S/mp-TiO(2)/FTO has the interband transition absorption in the whole visible region, while in the spectrum of Ag/mp-TiO(2)/FTO, a localized surface plasmon resonance absorption of Ag NPs is present centered at 490 nm. Ag(2)S QD-sensitized photoelectrochemical cells using the Ag(2)S/mp-TiO(2)/FTO and Ag/mp-TiO(2)/FTO photoanodes were fabricated. Under illumination of one sun, the Ag(2)S photoanode cell yielded H(2) at a rate of 0.8 mL·h(-1) with a total conversion efficiency of 0.29%, whereas the Ag/mp-TiO(2)/FTO photoanode is inactive.     

Artificially controlled synthesis of graphene intramolecular heterojunctions for phonon engineering

Because phonons are the main carriers for graphene heat transfer, modifying the dynamic properties of the crystal lattice by isotopes modulates the phonon behavior and alters the thermal properties. Here we demonstrate an artificially controlled texture synthesis of ¹²C‐graphene/¹³C‐graphene heterostructures via chemical vapor deposition and an O₂ plasma etching. The electrical and thermal properties of the graphene across the heterojunction show that ¹²C‐graphene and ¹³C‐ graphene are electronically connected as resistors in series, while the thermal conductivity across the junction is dramatically reduced due to the suppressed phonon propagation, which causes the conductivity across the junction to be lower than that of graphene sheets with randomly mixed isotopes. These findings should help realize novel two‐dimensional graphene thermoelectric devices where phonon modulation controls the electrons and heat transport independently. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Fabrication of superhydrophobic surfaces from mixtures of aluminum distearate and fatty acids via intermediate organogel formation

Superhydrophobic surfaces were obtained easily from the mixtures of aluminum distearate (AlDS) and typical saturated fatty acids with long alkyl chains by a casting method. In contrast to a mediocre water contact angle of 109?±?1° for the surface obtained from only AlDS, the mixture of AlDS and stearic acid (SA) gave a superhydrophobic surface having the contact angle of 164?±?2° and the sliding angle of 3?±?1° at the SA/AlDS weight ratio of 12. A homogeneous surface was not available from only SA on a macroscopic scale. To be superhydrophobic, the surface needs to take a hierarchical structure, like a table coral which consists of several tens of micrometer-size primary structure of widely branched SA crystals. In this study, the hierarchical structures were obtained by crystallizing fatty acids in the organogel composed of AlDS and a solvent, to avoid the formation of needle-like or plate-like bulky crystals as usually seen in the recrystallization of fatty acids.     

Release mechanism from a microsphere of a silkworm chitin derivative studied by single microparticle injection and absorption microspectroscopy.

The release process of phenol blue from a dibutyrylchitin microsphere, prepared with chitin from a silkworm, into an aqueous solution was kinetically analyzed by single microparticle injection/manipulation and absorption microspectroscopy. The distribution ratio and the release rate of phenol blue in the single microsphere/water system were significantly influenced by the pH of the solution. These results are discussed in terms of the protonation of phenol blue and dibutyrylchitin, and the pore and surface diffusion in the pores of the microsphere.