Abstract Dense and well‐adherent enamel–nano‐Ni composite/enamel–nano‐nickel composite coatings were prepared on 304 steel. Their thermal shock (TS) resistance at 400°C as well as the chemical stability in sulfuric acid solution were investigated, and compared with pure enamel coatings. Results indicated that the nanocomposite coatings with 5 wt% of Ni particles exhibited the best resistance to TS. Almost no spalling of the coating occurs after 50 cycles of TS at 400°C. They also provided enough protective effect to the substrates from sulfuric acid corrosion. After 7 days of corrosion, the weight loss of Ni‐5 enamel coating was only 1.107 mg/cm 2 .
For the past few years, only a few monovalent EV71 vaccines have been developed, while other enterovirus vaccines are in short supply. We conducted a quantitative meta-analysis to explore the epidemiological characteristics, routine laboratory diagnosis, clinical signs and risk factors for hand, foot and mouth disease (HFMD).PubMed, Embase and the Web of Science were searched for eligible reports published before April 16, 2021, with no publication time or language restrictions. The primary outcome was the odds ratio of the epidemiological characteristics, routine laboratory diagnosis, and clinical signs associated with HFMD severity and death.After screening 10522 records, we included 32 articles comprising 781903 cases of hand, foot and mouth disease. Patients with severe illness developed some clinical signs (hypersomnia (OR = 21.97, 95% CI: 4.13 to 116.74), convulsion (OR = 16.18, 95% CI: 5.30 to 49.39), limb shaking (OR = 47.96, 95% CI: 15.17 to 151.67), and breathlessness (OR = 7.48, 95% CI: 1.90 to 29.40)) and had some changes in laboratory parameters (interleukin-6 levels standardized mean difference (SMD) = 1.57, 95%CI: 0.55 to 2.60), an increased neutrophils ratio (SMD = 0.55, 95%CI: 0.17 to 0.93), cluster of differentiation 4 (CD4+) (SMD = -1.38, 95%CI: -2.33 to -0.43) and a reduced lymphocytes ratio (SMD = -0.48, 95%CI: -0.93 to -0.33)) compared with patients with mild illness. The risk factors for death included cyanosis (OR = 5.82, 95% CI: 2.29 to 14.81), a fast heart rate (OR = 3.22, 95% CI: 1.65 to 6.30), vomiting (OR = 2.70, 95% CI: 1.33 to 5.49) and an increased WBC count (SMD = 0.60, 95% CI: 0.27 to 0.93).China has the highest incidence of HFMD. Our meta-analyses revealed important risk factors that are associated with the severity and mortality of HFMD.
In this study, a vanadium (V) and tannic acid-based composite conversion coating (VTACC) was prepared on 6063 aluminum alloy (AA6063) to increase its corrosion resistance. The surface morphology and compositions of the VTACCs were characterized using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the coatings was investigated by linear polarization and electrochemical impedance spectra (EIS). The self-healing ability of the coating was detected by SEM, EDS, and scanning vibrating electrode technique (SVET) measurements. The coating mainly consisted of metal oxides, including Al 2 O 3 , VO 2 , V 2 O 3 , and V 2 O 5 , and metal organic complexes (Al and V-complexes). The electrochemical measurement results indicated that the best corrosion resistance of VTACC was acquired when the treatment time was 12 min. Furthermore, because a new coating with vanadium rich oxide was developed on the scratch area, artificial scratch VTACC surfaces were repaired after several days of immersion in 3.5-wt% NaCl solution.
In this paper, the optimum fluoride component in the multifunctional refining flux used for recycling aluminum scrap was determined. Theoretical analysis of solid fluxing shows that strong stripping ability of oxide layer on aluminum surface for the flux and appropriate interfacial tensions between Al melt / inclusion (σM-I), flux / inclusion (σF-I), and flux / Al melt (σF-M) are indispensable for making the flux achieve the properties of covering, drossing, and cleaning simultaneously. In term of four preliminarily selected fluoride salts, i.e., KF, AlF3, K3AlF6 and KAlF4, the results of interfacial tension measurements indicates that, combined addition of A-type fluoride (KF) and B-type fluoride (AlF3, K3AlF6 and KAlF4) to equimolar NaCl-KCl can just offset the shortage of single addition of KF which means worsening the separating effect of flux from melt surface and weakening the wettability of flux on the inclusions due to the lower σF-M and the higher σF-I respectively. Additionally, coalescence behaviors of aluminum droplets in molten fluxes reveals that, KF, K3AlF6 or KAlF4 possesses stronger stripping ability of oxide layer, while the stripping ability of oxide layer for AlF3 is weaker. Ultimately, the combination of KF with K3AlF6 or/and KAlF4 is ascertained to be an optimum selection for fluoride component in the multifunctional refining flux.
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