A Lumped Parameter Model of a Fibre-Reinforced Composite Plate with Temperature Dependence Based on Thermal Vibration Measurements

Experimental Mechanics - Background: Experimental modelling techniques are still rare for composite structures under complex thermal environments. Objective: In this paper, by taking a...     

Study of Electrochemical Oxidation of Xanthohumol by Ultra-Performance Liquid Chromatography Coupled to High Resolution Tandem Mass Spectrometry and Ion Mobility Mass Spectrometry

Electrochemically assisted oxidation off-line combined with UPLC/ESI–MS and ion mobility mass spectrometry enabled us to gain insight into the oxidation mechanisms of xanthohumol. Several types of monomeric oxidation products were identified, i.e., monohydroxylated and dehydrogenated derivatives and related quinones. Besides, high contents of dimers were observed. The structures of four main oxidative condensation products of two xanthohumol molecules were proposed based on combination of retention time, exact mass measurement, fragmentation pattern, data from on-line ion mobility mass spectrometric experiments and with the support of independent electrochemical experiments. To the best of our knowledge, this is the first evidence on formation of xanthohumol dimers. The effect of the pH on the generation of oxidation products was further investigated. The monomeric and dimeric oxidation products are favored at pH of 5.5 and 4.5, respectively.

     

Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons

We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs).     

Enantioselective Copper‐Catalyzed Azide–Alkyne Click Cycloaddition to Desymmetrization of Maleimide‐Based Bis(alkynes)

A copper catalyst system derived from TaoPhos and CuF₂ was used successfully for catalytic asymmetric Huisgen [3+2] cycloaddition of azides and alkynes to give optically pure products containing succinimide‐ and triazole‐substituted quaternary carbon stereogenic centers. The desired products were obtained in good yields (60–80 %) and 85:15 to >99:1 enantiomeric ratio (e.r.) in this click cycloaddition reaction.     

Deep oxidative desulfurization of benzothiophene and dibenzothiophene with a peroxophosphotungstate–ionic liquid brush assembly

A novel, efficient and reusable heterogeneous catalytic assembly of peroxophosphotungstate held in an ionic liquid brush was synthesized and an extraction and catalytic oxidative desulfurization (ECODS) procedure was developed for a model oil of benzothiophene (BT) and dibenzothiophene (DBT) using 30 wt% hydrogen peroxide as terminal oxidant and methanol as solvent under mild conditions. Several factors that affect sulfur removal were investigated in detail. The highest sulfur removal can reach 100% for BT in 7 h at 70 °C when the molar ratio of H₂O₂, S and catalyst is 10:1:0.025. The sulfur removal for DBT can also reach 100% in 4 h at 50 °C with the same molar ratio of H₂O₂, S and catalyst. The experimental results demonstrate that this ECODS process has no apparent scale‐up effect. The catalyst can be easily recovered (via simple filtration) and recycled five times without a significant decrease in activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Size,Charge, and Stability of Fully Serine‐Based Catanionic Vesicles: Towards Versatile Biocompatible Nanocarriers

Vesicles based on mixed cationic and anionic surfactants (catanionic vesicles) offer a number of advantageous colloidal features over conventional lipid‐based vesicles, namely spontaneity in formation, long‐term stability, and easy modulation of size and charge. If biocompatibility is added through rational design of the chemical components, the potential for biorelated applications further emerges. Here, we report for the first time on two catanionic vesicle systems in which both ionic amphiphiles are derivatized from the same amino acid—serine—with the goal of enhancing aggregate biocompatibility. Phase behavior maps for a mixture with chain length symmetry, 12Ser/12‐12Ser, and another with asymmetry, 16Ser/8‐8Ser, are presented, for which regions of vesicles, micelles, and coexisting aggregates are identified. For the asymmetric mixture, detailed phase behavior and microstructure characterization have been carried out based on surface tension, light microscopy, cryo‐SEM, cryo‐TEM, and dynamic light scattering analysis. Vesicles are found with tunable mean size, pH, and zeta potential. Changes in aggregate shape with varying composition and the effect of preparation methods and aging on vesicle features and stability have been investigated in detail. The results are discussed in the light of self‐assembly models and related catanionic systems reported before. A versatile system of robust vesicles is thus presented for potential applications.     

Chloride‐Selective Electrodes Based on “Two‐Wall” Aryl‐Extended Calix[4]Pyrroles: Combining Hydrogen Bonds and Anion–π Interactions to Achieve Optimum Performance

The performance of chloride‐selective electrodes based on “two‐wall” aryl‐extended calix[4]pyrroles and multiwall carbon nanotubes is presented. The calix[4]pyrrole receptors bear two phenyl groups at opposite meso‐positions. When the meso‐phenyl groups are decorated with strong electron‐withdrawing substituents, attractive anion–π interactions may exist between the receptor’s aromatic walls and the sandwiched anion. These anion–π interactions are shown to significantly affect the selectivity of the electrodes. Calix[4]pyrrole, bearing a p‐nitro withdrawing group on each of the meso‐phenyl rings, afforded sensors that display anti‐Hofmeister behavior against the lipophilic salicylate and nitrate anions. Based on the experimental data, a series of principles that help in predicting the suitability of synthetic receptors for use as anion‐specific ionophores is discussed. Finally, the sensors deliver excellent results in the direct detection of chloride in bodily fluids.