Modifications of the 1H NMR metabolite profile of processed mullet (Mugil cephalus) roes under different storage conditions

¹H NMR spectroscopy was employed to study the modifications over time of the water‐soluble low molecular weight metabolites extracted from samples of salted and dried mullet (Mugil cephalus) roes (mullet bottarga) stored at different conditions. Samples of grated mullet bottarga were stored for 7 months at ?20 °C, at 3 °C, and at room temperature in the presence and in the absence of light and then timely extracted and analyzed by NMR. Principal component multivariate data analysis applied to the spectral data indicated that samples stored at ?20 °C maintained similar features over time whereas, along PC1, samples stored at room temperature in the presence and in the absence of light showed, over time, marked metabolite modifications. The comparative analysis of the integrated areas of the selected regions of the ¹H NMR spectra indicated that the major compositional changes due to storage conditions were (i) the increase of the derivatives of the breakdown of phosphatidylcholine (choline, phosphorylcholine, and glycerol), (ii) the breakdown of nucleosides, (iii) the decrease of methionine, tryptophan, and tyrosine, and (iv) the cyclization of creatine. These changes were observed at different storage conditions, with more pronounced trends in the samples stored at room temperature. The role of metabolites in food aging is discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Substituent effect on supercapacitive performances of conducting polymer‐based redox electrodes: Poly(3′,4′‐bis(alkyloxy) 2,2′:5′,2″‐terthiophene) derivatives

This work reports the synthesis of novel poly(3′,4′‐bis(alkyloxy)terthiophene) derivatives (PTTOBu, PTTOHex, and PTTOOct) and their supercapacitor applications as redox‐active electrodes. The terthiophene‐based conducting polymers have been derivatized with different alkyl pendant groups (butyl‐, hexyl‐, and octyl‐) to explore the effect of alkyl chain length on the surface morphologies and pseudocapacitive properties. The electrochemical performance tests have revealed that the length of alkyl substituent created a remarkable impact over the surface morphologies and charge storage properties of polymer electrodes. PTTOBu, PTTOHex, and PTTOOct‐based electrodes have reached up to specific capacitances of 94.3, 227.3, and 443 F g⁻¹ at 2.5 mA cm⁻² constant current density, respectively, in a three‐electrode configuration. Besides, these redox‐active electrodes have delivered satisfactory energy densities of 13.5, 29.3, and 60.7 W h kg⁻¹ and power densities of 0.98, 1, and 1.1 kW kg⁻¹ with good capacitance retentions after 10,000 charge/discharge cycles in symmetric solid‐state micro‐supercapacitor devices. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 480–495     

Density functional theory calculations of the metal-doped carbon nanostructures as hydrogen storage systems under electric fields: A review

This review covers structural, electronic, and hydrogen storage properties of carbon-based materials with doped metals under electric fields with different orientations and intensities, which are determined by density functional theory (DFT) simulations. The special application case is considered in investigating variations of electronic structures, binding, and hydrogen storage properties. External fields that are often met in practical applications lead to changes of the above properties.     

Cold flame-sprayed and oil-impregnated porous metallic coatings

Porous metallic coatings were prepared from three commercial alloy powders on 16MnCr5 steel by cold flame spraying. The mechanical characterisation of the coatings was performed by Vickers microindentation and debonding tests. Porosity was determined by image analysis of the optical micrographs of the polished cross-sections. The coatings were impregnated with motor oil 15W40 with the aim of preparing a lubricating system. The amounts of oil uptake and release by the coatings were determined under controlled conditions. The surfaces of the coatings were examined by X-ray photoelectron spectroscopy (XPS) and wettability studies. The amounts of oil uptake and release showed inverse relationship with the oxygen concentration at the surface and also with the Lifshitz-van der Waals component of surface energy. These relationships offer the possibility of controlling the lubrication properties of cold flame-sprayed and oil-impregnated porous metallic coatings.     

LaNi_(3.8-x)Al_x(0≤x≤0.5)多相储氢合金的结构及电化学性能

采用真空电弧熔炼法制备了LaN i3.8-xA lx(0≤x≤0.5)储氢合金,并在氩气气氛中进行退火处理。通过X射线衍射(XRD),S ievert′s方法和电化学测试分别分析了合金的物相结构、储氢和电化学性能。研究结果表明:LaN i3.8-xA lx(0≤x≤0.5)合金主要由LaN i5,Ce2N i7,Pr5Co19和Ce5Co19型相组成。随着A l的变化,各相相丰度发生变化,而相丰度的变化影响了合金的滞后和吸/放氢平台压力。随着x的增加,LaN i3.8-xA lx(0≤x≤0.5)合金的放电容量先增大至270 mAh.g-1(x=0.3),然后缓慢降低;在x=0.3时合金显示出较好的充/放电循环稳定性。极化电阻和电化学交流阻抗则随着x的增加缓慢降低,交换电流密度增大,导致高倍率放电有所增大。     

Intercalated MXene-based layered composites:Preparation and application

Combining high conductivity,hydrophilicity and excellent electrochemical perfo rmance in one,MXe nes have attracted increasing attention since their inception.However,easy to stack caused by the van der Waals' force between the layers limits their practical application.Fortunately,intercalating other substances between layers of MXe nes and getting intercalated MXene-based layered composites(IMLCs)with open structure can improve their physical and chemical properties effectively.Larger available surface helps expose more active sites and enlarged layer spacing facilitates ion transport.In addition,other substances fixed in the interlayers by MXenes' two-dimensional confinement effect can produce synergistic effect and expand their applicable range greatly.This review is dedicated to summarizing the preparation methods and applications of IMLCs,emphasizing the advantages of them in the fields of energy storage,catalysis,sensors,electromagnetic interference(EMI) shielding and biomedicine.Furthermore,prospects and further developments in these gratifying fields are also commented.     

Quasiparticle band structure and optical properties of NH3BH3

The quasiparticle band structure of the low temperature orthorhombic phase of NH₃BH₃ is studied by using the GW approximation. It is found that NH₃BH₃ is an insulator with a value of the band gap of 5.90 eV with GGA and of 9.60 eV with the GW approximation. Then, the optical properties of NH₃BH₃ are obtained by the calculation of the dielectric function, corrected by a scissor shift operation corresponding to the GW correction on the band gap. Also, the optical anisotropy in NH₃BH₃ is analyzed through the refractive index and static dielectric constants along the different crystallographic directions. Finally, it is found that the energy loss function has a prominent peak at 22.26 eV; at these frequencies (above 22.26 eV) NH₃BH₃ becomes transparent. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Bis‐Calix[4]arenes: From Ligand Design to the Directed Assembly of a Metal–Organic Trigonal Antiprism

Calix[4]arenes (C[4]s) are versatile platforms for the construction of polymetallic clusters containing paramagnetic metal ions. Synthetic modification at the C[4] methylene bridge allows for the design of bis‐C[4]s that, depending on the linker employed, can be used to either dictate which clusters can be formed or direct the assembly of a new metal–organic polyhedron (MOP). The assembly resulting from the latter approach displays thermal stability and uptake of N₂ or H₂ gas, confirming that this is a viable route to the synthesis of new, functional supramolecular architectures.