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Constructing non-noble metal-based catalysts has attracted more attention owing to these materials owning high abundance, low cost, and expected to take the place of Pt/C as a candidate commercial the oxygen reduction reaction (ORR) catalyst. Herein, hollow microspheres self-assembled by a layer of interweaving Fe2O3 nanorods are first fabricated by a one-step hydrothermal process, which are then covered by dopamine. Finally, annealing treatment at the assigned temperature in N2 is conducted to synthesize Fe/FexOy nanorod-based hollow microspheres (~ 900 nm in diameter) covered by N-doped carbon. Electrochemical measurements demonstrate that, by the side of the commercial 20% Pt/C, the as-obtained T-650 has a higher onset potential (83-mV positive shift), more positive half wave potential (55-mV positive shift), and larger limiting current density (increased by 0.9 mA cm-2). It is found that the simultaneous presence of zero-valence Fe and nitrogen atoms is the key to the high catalytic activity of the as-synthesized Fe–N-C material, and these unique hierarchical hollow porous microspheres make the electrocatalyst possess excellent catalytic performance, long-time stability, and superior methanol tolerance.

Synthesis of high-efficiency and low-cost electrocatalysts for oxygen reduction reaction (ORR) to replace Pt or its alloys become one of the key factors of fuel cells. In this work, a typical Co–N–C catalyst from ZIF-67 was fabricated by pyrolyzing the as-prepared ZIF-67. The characteristic and performance of the obtained Co–N–C catalyst was analyzed by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer -Emmette-Teller (BET) method. The results show that the obtained catalyst was composed of rhombic dodecahedrons particles about 300 ​nm, which came from pyrolyzing ZIF-67 at 700 ​°C, synthesized with 1:6 ​M ratio of cobalt nitrate and 2-methylimidazole. In O2 saturated 0.1 ​M KOH solution, the onset potential, half-wave potential and limiting current density of the catalyst were 0.91 ​V, 0.82 ​V, and 5.33 ​mA/cm2, behaving excellent electrochemical performance. These reasons such as exposing more Co–N active sites, more pyridinic nitrogen, even particles with rhombic dodecahedrons structure and larger specific surface area, contributed to its good catalytic activity.

Through to the highway undercrossing the railway analysis and study of this special construction node, and analyzes the factors which cause various types of accidents and causation, and build construction site accidents Fault Tree Analysis, Fault tree obtained minimal path sets, minimal cuts and each basic event structure importance and analyzes the result, according to the analysis results to establish construction site safety accident prevention and control measures, and provide measures to strengthen the safety of the construction site in the people, objects, managing three aspects. Provide a reference for the future of this type of construction site safety management and safety control.

Geopolymers with calcium contents were prepared from class C fly ash, metakaolin, and Ca(OH)2. Geopolymer products and ordinary cement hydration products were divided with gradient acid dissolution test. The effects of calcium in class C fly ash geopolymer were investigated through the calcium concentration of acid solution. In an appropriate alkali situation, most of the calcium will be dissolved from class C fly ash. Part of the calcium will react with silicate and aluminum to form geopolymeric gels as the presence of gismondine (zeolite). Part of calcium was hydrated to form calcium silicate hydrate(C-S-H), and the rest of calcium may be adsorbed within the geopolymeric binding structure to balance charge anion. The class C fly ash geopolymer is a composite system with the coexistence of geopolymeric and C-S-H gels.

Background The aims of this study were to deposit a zinc-hydroxyapatite (Zn-HA) coating on titanium surfaces by using the electrochemical process and investigate the cell response to the Zn-HA–coated titanium surface. Study Design Surface characteristics were evaluated by scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Murine preosteoblast cell (MC3T3-E1) proliferation, alkaline phosphatase (ALP) activity, and osteocalcin release on Zn-HA–coated surfaces were compared with HA-coated surfaces. Results Field-emission SEM observation showed rod-like HA crystals with a hexagonal cross-section on the HA-coated surface, although the hexagon of the cross-section of Zn-HA crystals became irregular. ICP-AES analysis showed that Zn was present in the Zn-HA coatings at a Zn/(Ca+Zn) molar ratio of 1.04%. Significant increases in cell proliferation, ALP activity on day 7, and osteocalcin produnction on day 14 ( P 2+ -containing HA-coated surfaces. Conclusions The present study showed that a Zn-HA coating deposited by using the electrochemical process enhances proliferation and differentiation of osteoblasts, which has the potential benefit to enhance implant osseointegration.

In the early research work,the concept of building energy smart grid based on natural gas based distributed energy system is proposed. For design of energy storage system applied to NDES-SG, basic principles of system design are given which follows energy saving and efficiency increasing in this paper. To interpret integration, energy saving potential and system evaluation method of NDES-SG, Combining with design principles of energy storage system, a simplified typical case system is presented. The influence of energy storage system design on the NDES-SG performance is studied taking ice thermo storage system as an example and system energy saving rate for evaluation criteria. The results show that NDES-SG with a reasonable storage system design can realize energy saving rate approximately 30% compared with NDES-SG without energy storage system. NDES-SG system energy efficiency is further improved.

Objective: The purpose of this study was to investigate the effects of a zinc-substituted nano-hydroxyapatite (Zn-HA) coating, applied by an electrochemical process, on implant osseointegraton in a rabbit model. Methods: A Zn-HA coating or an HA coating was deposited using an electrochemical process. Surface morphology was examined using field-emission scanning electron microscopy. The crystal structure and chemical composition of the coatings were examined using an X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). A total of 78 implants were inserted into femurs and tibias of rabbits. After two, four, and eight weeks, femurs and tibias were retrieved and prepared for histomorphometric evaluation and removal torque (RTQ) tests. Results: Rod-like HA crystals appeared on both implant surfaces. The dimensions of the Zn-HA crystals seemed to be smaller than those of HA. XRD patterns showed that the peaks of both coatings matched well with standard HA patterns. FTIR spectra showed that both coatings consisted of HA crystals. The Zn-HA coating significantly improved the bone area within all threads after four and eight weeks (P

Purpose The purpose of this study was to investigate the effect of the thin nano-hydroxyapatite (nano-HA) coating on implant osseointegration in an ovariectomized rat model. Materials and Methods Implants were divided into a control group and a test group (nano-HA–coated group). Surface morphology was examined using field-emission scanning electron microscopy (FSEM). Surface roughness of both groups was performed. Sixteen ovariectomized rats randomly received 2 implants in both tibiae. After 12 weeks of implantation, tibias were retrieved and prepared for histomorphometric evaluation and removal torque tests (RTQ). Results Rodlike crystals uniformly covered the porous surfaces and the surface morphology of the implant was still clear. No significant differences were found in surface roughness between the 2 groups ( P > .05). More bone tissue was formed around test implants compared with control implants. Test implants showed a significantly greater BIC, bone area within all threads, and RTQ values compared with control implants ( P Conclusions These results indicate the thin nano-HA coating by an electrochemical process has potential benefits to enhance implant osseointegration in ovariectomized rats.