One-Step Fabrication and Localized Electrochemical Characterization of Continuous Al-Alloyed Intermetallic Surface Layer on Magnesium Alloy

A continuous intermetallic compound coating was fabricated on AZ91D magnesium alloy via heat treatment at 400 °C in AlCl3-NaCl molten salts for 10 h. The microstructure and composition of the coating were characterized by scanning electron microscope and energy dispersive X-ray spectrometry. The results showed that the coating has a two-layer structure (the outer Mg2Al3 phase layer and the inner Mg17Al12 phase layer) up to 37 μm thick with compact and planar interfaces between the layers and the substrate. The corrosion property of the coating was investigated using electrochemical impedance spectroscopy (EIS) and two localized electrochemical techniques, i.e., localized electrochemical impedance spectroscopy (LEIS) and scanning vibrating electrode technique (SVET). The charge transfer resistance (Rct) of the Al-alloyed coating was 2119 Ω cm2. The localized impedance and current density maps obtained through LEIS and SVET indicate not only significantly improved corrosion resistance (the impedance modulus increased by one order of magnitude and the current density decreased to approximately 3.8%, compared with the substrate) but also defect-free surface condition

Controlled Generation of Uniform Spherical LaMnO₃, LaCoO₃, Mn₂O₃, and Co₃O₄ Nanoparticles and Their High Catalytic Performance for Carbon Monoxide and Toluene Oxidation

Uniform hollow spherical rhombohedral LaMO₃ and solid spherical cubic MO_<i>x</i> (M = Mn and Co) NPs were fabricated using the PMMA-templating strategy. Hollow spherical LaMO₃ and solid spherical MO_<i>x</i> NPs possessed surface areas of 21–33 and 21–24 m²/g, respectively. There were larger amounts of surface-adsorbed oxygen species and better low-temperature reducibility on/of the hollow spherical LaMO₃ samples than on/of the solid spherical MO_<i>x</i> samples. Hollow spherical LaMO₃ and solid spherical MO_<i>x</i> samples outperformed their nanosized counterparts for oxidation of CO and toluene, with the best catalytic activity being achieved over the solid spherical Co₃O₄ sample for CO oxidation (<i>T</i>_50% = 81 °C and <i>T</i>_90% = 109 °C) at space velocity = 10 000 mL/(g h) and the hollow spherical LaCoO₃ sample for toluene oxidation (<i>T</i>_50% = 220 °C and <i>T</i>_90% = 237 °C) at space velocity = 20 000 mL/(g h). It is concluded that the higher surface areas and oxygen adspecies concentrations and better low-temperature reducibility are responsible for the excellent catalytic performance of the hollow spherical LaCoO₃ and solid spherical Co₃O₄ NPs. We believe that the PMMA-templating strategy provides an effective route to prepare uniform perovskite-type oxide and transition-metal oxide NPs

Co-infecting pathogens can contribute to inflammatory responses and severe symptoms in COVID-19

Background: The current COVID-19 pandemic is posing a major challenge to public health on a global scale. While it is generally believed that severe COVID-19 results from over-expression of inflammatory mediators (i.e., a "cytokine storm"), it is still unclear whether and how co-infecting pathogens contribute to disease pathogenesis. To address this, we followed the entire course of the disease in cases with severe or critical COVID-19 to determine the presence and abundance of all potential pathogens present-the total "infectome"-and how they interact with the host immune system in the context of severe COVID-19. Methods: We examined one severe and three critical cases of COVID-19, as well as a set of healthy controls, with longitudinal samples (throat swab, whole blood, and serum) collected from each case. Total RNA sequencing (meta-transcriptomics) was performed to simultaneously investigate pathogen diversity and abundance, as well as host immune responses, in each sample. A Bio-Plex method was used to measure serum cytokine and chemokine levels. Results: Eight pathogens, SARS-CoV-2, Aspergillus fumigatus (A. fumigatus), Mycoplasma orale (M. orale), Myroides odoratus (M. odoratus), Acinetobacter baumannii (A. baumannii), Candida tropicalis, herpes simplex virus (HSV) and human cytomegalovirus (CMV), identified in patients with COVID-19 appeared at different stages of the disease. The dynamics of inflammatory mediators in serum and the respiratory tract were more strongly associated with the dynamics of the infectome compared with SARS-CoV-2 alone. Correlation analysis revealed that pulmonary injury was directly associated with cytokine levels, which in turn were associated with the proliferation of SARS-CoV-2 and co-infecting pathogens. Conclusions: For each patient, the cytokine storm that resulted in acute lung injury and death involved a dynamic and highly complex infectome, of which SARS-CoV-2 was a component. These results indicate the need for a precision medicine approach to investigate both the infection and host response as a standard means of infectious disease characterization