Search

Carbapenem-resistant Klebsiella pneumoniae (CRKP), particularly those with high virulence, cause invasive disease in clinical settings. An epidemiological investigation was conducted on the evolution, virulence, and antimicrobial resistance of CRKP isolates in two tertiary teaching hospitals in Jiangsu, China from November 2020 to December 2021. There were 31 different CRKP strains discovered. We performed whole genome sequencing (WGS) on 13 SHV, cmlv, and FosA6-producing CRKP to reveal molecular characteristics. Five ST15/ST11 isolates had CRISPR-Cas systems. By conjugation tests, KPC-2 can be transmitted horizontally to E. coil. A conjugative pHN7A8-related multi-resistance plasmid (KPC-2, blaCTX-M-65, blaTEM-1, fosA3, catII, and rmtB) was first discovered in CRKP clinical isolates. Using bacteriological testing, a serum killing assay, and an infection model with Galleria mellonella, three ST11-K64 KPC-2 generating carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) were identified. These strains harbored a virulent plasmid and an IncFII-family pKPC/pHN7A8 conjugative plasmid, which led to hypervirulence and resistance. One of these CR-hvKPs, which co-harbored KPC-2, NDM-6, SHV-182, SHV-64, and blaCTX-M-122 genes, was first discovered. Importantly, this CR-hvKP strain also produced biofilm and had non-inferior fitness. The widespread use of ceftazidime/avibactam might provide this CR-hvKP with a selective advantage; hence, immediate action is required to stop its dissemination. Another important finding is the novel ST6136 in K. pneumoniae. Finally, the sterilization efficiency rates of Fe2C nanoparticles in CRKP were more than 98%. Furthermore, our novel antibacterial Fe2C nanoparticles may also provide a therapeutic strategy for infections. [ABSTRACT FROM AUTHOR]

Pt-based electrocatalysts in oxygen reduction reaction (ORR) have notably frustrated the large-scale application in the relevant energy technologies. Alternatively, polydopamine (PDA)-based materials have displayed great potential due to its adhesive uniqueness, componential and structural tailorability, but the inferior surface area due to the intrinsically dense coating of PDA is an imperfection. Herein, with 3-aminopropyltriethoxysilane (APTS), one mutual deposition method with organic PDA and inorganic APTS was proposed for ultrafine Fe 2 C embedded into porous N-doped carbon (Fe/PNC), benefitting from synergistic effect of the PDA-derived carbon and APTS-derived SiO 2 components produced from the pyrolysis of PDA-APTS hybrid, which can confine metal species more robustly than single PDA, together with the internal pore-making capacity. Accordingly, the as-obtained sample exhibits superior alkaline ORR activity with a half-wave potential of 0.87 V as well as robust long-time durability and strong poison tolerance. Additionally, the constructed zinc–air battery using Fe/PNC as cathode presents higher peak power density and much stronger long-time charge-discharge stability than Pt/C. Such strategy would be generally applicable for the rational design of highly-quality metal-based functional composites. One novel polydopamine-silane co-deposition strategy was proposed to synthesize highly dispersed Fe 2 C species in abundantly porous N-doped carbon, displaying remarkable performance for oxygen reduction reaction and rechargeable zinc-air battery. [Display omitted] • Polydopamine−silane co-deposition was explored for metal/carbon composite. • Highly dispersed Fe 2 C around 1∼2 nm richly interspersing in N-doped carbon. • Abundantly porous structures from silica template and SiO 2 from silane. • Excellent ORR activity matching with Pt/C and zinc–air battery performance. [ABSTRACT FROM AUTHOR]

In this work, the catalytic activity towards hydrogen evolution reaction (HER) was studied for hydrogen adsorption on Pt doped Fe 2 C (001) surface configuration (Pt/Fe 2 C) and compared with pure Pt (001). The adsorption of H on the pristine Fe 2 C, Pt doped Fe 2 C, and pure Pt in (001) slab was computed. The best and promising HER activity (ΔG H∗ = −0.02 eV) is obtained at the hollow site adsorption of Pt/Fe 2 C (Fe 13 Pt 3 C 8) compared to the experimental value of pure Pt (ΔG H∗ = −0.09 eV) suggesting the possibility of the H 2 formation on the surface of Fe 13 Pt 3 C 8. The structural stabilities of Fe 2 C and Pt/Fe 2 C were investigated by the formation energy analysis. Also, it is observed that to enhance the HER mechanism, the modification of the d-electron structure of Pt atoms is essential which can be achieved by the increased Pt doping. The Bader charge analysis demonstrated the charge transfer between the substrate and the adsorbed H atoms. The density of states (DOS) of pure Fe 2 C and optimal Pt/Fe 2 C were calculated which revealed the magnetic and metallic nature of these materials. In addition, the adsorption and resulted activation of H 2 were facilitated by the elongation of H–H bond length in Fe 13 Pt 3 C 8. This work supports the HER over single atom catalysts (SACs) with lower Pt loading but with high catalytic activity and the maximum atom utilization of SACs. Image 1 • The structural stabilities of the Fe 2 C and Pt/Fe 2 C were investigated. • Hydrogen adsorption energies were calculated as demonstrators of the HER activity. • Bader charge analysis signifies the charge transfer between substrate and H atom. • DOS reveal the magnetic and metallic nature of the Fe 2 C and Pt/Fe 2 C. [ABSTRACT FROM AUTHOR]

The Fischer-Tropsch synthesis (FTS) continues to be an attractive alternative for producing a broad range of fuels and chemicals through the conversion of syngas (H2 and CO), which can be derived from various sources, such as coal, natural gas, and biomass. Among iron carbides, Fe2C, as an active phase, has barely been studied due to its thermodynamic instability. Here, we fabricated a series of Fe2C embedded in hollow carbon sphere (HCS) catalysts. By varying the crystallization time, the shell thickness of the HCS was manipulated, which significantly influenced the catalytic performance in the FTS. To investigate the relationship between the geometric structure of the HCS and the physic-chemical properties of Fe species, transmission electron microscopy, X-ray diffraction, N2 physical adsorption, X-ray photo-electron spectroscopy, hydrogen temperature-programmed reduction, Raman spectroscopy, and Mössbauer spectroscopy techniques were employed to characterize the catalysts before and after the reaction. Evidently, a suitable thickness of the carbon layer was beneficial for enhancing the catalytic activity in the FTS due to its high porosity, appropriate electronic environment, and relatively high Fe2C content. [ABSTRACT FROM AUTHOR]

Carbapenem-resistant Klebsiella pneumoniae (CRKP), particularly those with high virulence, cause invasive disease in clinical settings. An epidemiological investigation was conducted on the evolution, virulence, and antimicrobial resistance of CRKP isolates in two tertiary teaching hospitals in Jiangsu, China from November 2020 to December 2021. There were 31 different CRKP strains discovered. We performed whole genome sequencing (WGS) on 13 SHV, cmlv, and FosA6 -producing CRKP to reveal molecular characteristics. Five ST15/ST11 isolates had CRISPR-Cas systems. By conjugation tests, KPC-2 can be transmitted horizontally to E. coil . A conjugative pHN7A8-related multi-resistance plasmid ( KPC-2 , bla CTX-M-65 , bla TEM-1 , fosA3 , catII , and rmtB ) was first discovered in CRKP clinical isolates. Using bacteriological testing, a serum killing assay, and an infection model with Galleria mellonella , three ST11-K64 KPC-2 generating carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) were identified. These strains harbored a virulent plasmid and an IncFII-family pKPC/pHN7A8 conjugative plasmid, which led to hypervirulence and resistance. One of these CR-hvKPs, which co-harbored KPC-2 , NDM-6 , SHV-182 , SHV-64, and bla CTX-M-122 genes, was first discovered. Importantly, this CR-hvKP strain also produced biofilm and had non-inferior fitness. The widespread use of ceftazidime/avibactam might provide this CR-hvKP with a selective advantage; hence, immediate action is required to stop its dissemination. Another important finding is the novel ST6136 in K. pneumoniae . Finally, the sterilization efficiency rates of Fe 2 C nanoparticles in CRKP were more than 98%. Furthermore, our novel antibacterial Fe 2 C nanoparticles may also provide a therapeutic strategy for infections., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhu, Ju, Zhou, Chen, Zhuge and Dai.)

Abstract: The Fischer−Tropsch synthesis (FTS) is a non‐petroleum‐based alternative route, which directly produces fuels and value‐added chemicals (e. g. lower olefins) from coal‐, biomass‐ or natural gas‐derived syngas. The ϵ‐iron carbide, such as Fe2C, has been predicted to be active but not stable under high‐temperature FTS conditions. In this work, we have fabricated a novel catalyst with Fe2C embedded in hollow carbon spheres (HCS) by pyrolyzing the coated polymer and Fe(NO3)3 on silica spheres and then etching the hard template. XRD, XPS, TEM and N2 physical adsorption were employed to characterize the evolution and properties of as‐prepared catalysts, which significantly depend on pyrolysis temperature. Under FTS conditions, the obtained catalysts exhibit good dispersion, robustness of geometric construction, and resistance to sintering. More importantly, Fe2C was confirmed as the dominant and stable iron carbide species. The unique chemical surrounding and confinement effect provided by carbon matrix contribute to these peculiarities that are responsible for superior activity and stability in FTS. Furthermore, we found that the products distribution could be manipulated by changing the geometric diameters of HCS, due to the tunable CO/H2 ratio. [ABSTRACT FROM AUTHOR]