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The development of non-precious metal catalysts for the electrochemical oxygen evolution reaction (OER) is especially important for the water electrolysis process. Herein, a two-dimensional (2D) ultrathin hybrid Co–NiFe layered double hydroxide (LDH) is synthesized via a facile hydrothermal method. In 1.0 M KOH electrolyte, Co–NiFe LDH exhibits remarkable activities for OER. At the current density of 10 mA cm−2, it only needs an overpotential of 278 mV, which is ca. 50 mV and 20 mV lower than those for NiFe LDH (328 mV) and RuO2 catalysts (298 mV), respectively. In addition, Co–NiFe LDH also shows impressive long-term stability for OER. Besides the stable morphology and crystal structure, the potential is always kept at 1.50 V and shows almost no attenuation during the 20 h of durability test. Changes in the electronic structure of LDH due to introduction of Co ions, as well as the large specific surface area facilitate the mass/electron transfer and the oxygen bubbles release, and thus lead to the enhanced catalytic properties for OER. This work can be informative not only for understanding the role of physical and electronic structures on OER but also for designing high-performance non-precious metal OER electrocatalysts.

A series of PdmAg/C electrocatalysts (m being the atomic Pd/Ag ratio, m = 0.05, 0.1, 0.5, 1.0) for both ethanol and methanol oxidation reactions (EOR and MOR) are prepared via a facile co-reduction method. The morphologies and crystal structures are characterized by transmission electron microscopy techniques (TEM) and X-ray diffraction (XRD). Cyclic voltammetry (CV) and chronoamperometry (CA) techniques are applied to explore the catalytic performance of the PdmAg/C electrocatalysts for EOR and MOR in alkali medium. Our findings show that the catalytic performance of the PdmAg/C electrocatalysts rests with m and Pd0.5Ag/C has the highest activity among the PdmAg/C electrocatalysts. Furthermore, the activities of the PdmAg/C electrocatalysts are associated with the potential scope of CV curves. When Pd0.5Ag/C is tested in a relatively wide potential scope (−1.0 to 0.5 V), the current density of EOR is ca. 9.39 times higher than that tested in the narrow potential scope (−1.0 to 0.1 V). The improvement is ascribed to the promotion effects of Ag oxide formed at relatively high potential, that is, the synergistic effects between Ag oxide and Pd contribute to the improvement in the catalytic properties of Pd.

Phospholipids are the main constituent of cellular membranes and have recently been identified to have diagnostic value as biomarkers for many diseases. Accordingly, much emphasis is now laid on developing optimal analytical techniques for the phospholipid profiles of various biological samples. In the present study, different classes of phospholipids are first separated by optimized hydrophilic interaction chromatography with evaporative light scattering detector (HILIC-ELSD). The phospholipids in each class are then identified by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Validation results confirm that this approach meets the requirements of quantitative analysis. Finally, the approach is adopted to analyze the phospholipid profiles in Caenorhabditis elegans. A total of 111 phospholipid species is identified according to the mass fragments. Major fatty acyl chains in phospholipids are found to be formed by oleic acid (C18:1), arachidonic acid (C20:4), and eicosapentaenoic acid (C20:5). Overall, this study improves current knowledge on analytical techniques of the phospholipid composition in C. elegans and provides a basis for future lipidomics research. Practical applications: Phospholipids reportedly play a crucial role in the development of many diseases. Until now, only a small portion of phospholipids in Caenorhabditis elegans has been reported by using one-dimensional analysis strategy. The offline 2D2D liquid chromatography method developed in this study identifies 111 phospholipid species in Caenorhabditis elegans. The obtained phospholipid profiles complement the lipid database of Caenorhabditis elegans. The study also provides the basis for the future development of a 2D online approach.

Additional file 1. Table S1. The sequence of primer for mtDNAcn detection. Table S2. The associations between CADASIL and mtDNAcn in different adjusted models. Table S3. The associations between CADASIL and D-loop methylation levels in different adjusted models. Table S4. The associations between mtDNAcn and D-loop methylation levels in different adjusted models.

In the present work, CeO2 nanocrystals with three well-defined morphologies including nanooctahedra, nanosphere and nanocube are synthesized and used as the promoter to Pt catalyst toward methanol electrooxidation reaction (MOR). The promotion effects of the CeO2 nanocrystals are investigated through electrochemical techniques including cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). Results indicate that the promotion effects are closely related to the nanostructure of CeO2 nanocrystals. Among the Pt-CeO2/C catalysts, Pt-CeO2/C-S catalyst with CeO2 nanosphere as the promoter shows the highest catalytic performance for MOR, which arises from both physical interaction and electronic effects between CeO2 and Pt. The loosened nanosphere structure with rough surface allows the Pt nanoparticles (NPs) to highly disperse onto the surface and thereby produce a strong physical interaction between Pt and CeO2. In addition, the change in the valence state from Ce4+ to Ce3+ generates abundant oxygen vacancies (VO) into the crystal lattice, and the increased vacancies lead to surplus electrons which would transfer from CeO2 to Pt. The increased electron density lowers the d-band center and thus improves the intrinsic activities (IA) of Pt. These data are used to discuss the role of physical interaction and electronic effects between the promoter and Pt and would be promising in designing the nanostructure of the Pt-based catalysts for DMFCs and other applications.

Although the conventional locally resonant acoustic metamaterials (LRAMs) have shown better sound absorption performance in the low frequency band, the effective frequency range of the sound absorption performance is quite narrow relatively. To overcome this drawback, a novel type of multilayered locally resonant acoustic metamaterials (M-LRAMs) is proposed in this paper. The sound absorption performance of the proposed LRAMs can be broadened and enhanced by coupled resonance with embedding multilayered locally resonant scatterers into the matrix structure. The finite element method (FEM) is employed to investigate the band gap characteristics and the sound absorption performance of the proposed M-LRAMs. The coupled resonance effects of the scatterers on the band gap characteristics and the sound absorption performance of acoustic metamaterials are studied as well. Moreover, the effects of the physical parameters of matrix, the thickness of each layer, the number of locally resonant scatterers and the materials of the scatterers on sound absorption performance are investigated. Results indicate that coupled resonance can broaden band gaps and engender multiple band gaps, and the M-LRAMs have many advantages in underwater sound absorption over the conventional LRAMs due to the enhanced coupled resonance effects. Keywords: Underwater sound absorption, M-LRAMs, Multilayered locally resonant scatterers, Band gaps

To achieve zero-energy building target, both China and the US have planned pathway by formulating guidelines and standards. China has published National China technical standard for nearly zero energy building (CTS-NZEB), which defines detailed principles of zero-energy building. The US LEED zero energy evaluation system has been released based on LEED rating system. Defined target and scope have been introduced in this evaluation system; however, there are no technical and detailed approaches in the rating system. To support future projects achieving the LEED Zero Energy certification in China, accessible applications have been analyzed in perspectives of technology and economy in this article. The comparison and analysis results show that the strategies and technical index of CTS-NZEB can be adopted comprehensively in LEED Zero Energy rating system for Chinese buildings except for renewable energy resources because air source or ground source heat pump system, which are extensively used in China but not acceptable in LEED Zero Energy rating system. High-performance strategies, including low U-value envelope, exterior shading devices, high air tightness envelope, high-efficiency heating, ventilation, and air-conditioning system, and low thermal bridge impact, can be applied to pursue LEED Zero Energy rating system. The incremental costs of NZEBs in China are also supported by government through market and financial policies. This would make significant impacts on Chinese buildings to achieve the LEED Zero Energy target.