Highly Selective Tandem Electroreduction of CO2 to Ethylene over Atomically Isolated Nickel-Nitrogen Site/Copper Nanoparticle Catalysts.

Herein, an effective tandem catalysis strategy is developed to improve the selectivity of the CO2 RR towards C2 H4 by multiple distinct catalytic sites in local vicinity. An earth-abundant elements-based tandem electrocatalyst PTF(Ni)/Cu is constructed by uniformly dispersing Cu nanoparticles (NPs) on the porphyrinic triazine framework anchored with atomically isolated nickel-nitrogen sites (PTF(Ni)) for the enhanced CO2 RR to produce C2 H4 . The Faradaic efficiency of C2 H4 reaches 57.3 % at -1.1 V versus the reversible hydrogen electrode (RHE), which is about 6 times higher than the non-tandem catalyst PTF/Cu, which produces CH4 as the major carbon product. The operando infrared spectroscopy and theoretic density functional theory (DFT) calculations reveal that the local high concentration of CO generated by PTF(Ni) sites can facilitate the C-C coupling to form C2 H4 on the nearby Cu NP sites. The work offers an effective avenue to design electrocatalysts for the highly selective CO2 RR to produce multicarbon products via a tandem route.

Boosting the oxygen reduction activity of non-metallic catalysts via geometric and electronic engineering through nitrogen and chlorine dual-doping.

The development of heteroatom dual-doped porous carbon frameworks with uniform doping is highly desirable for achieving highly efficient oxygen reduction reaction (ORR) activity, due to their tunable chemical and electronic structures. Herein, porous covalent triazine-based frameworks (CTFs) incorporating nitrogen/chorine dual-doped porous carbon networks were fabricated by selecting 1,3-bis(4-cyanophenyl) imidazolium chloride as a building block, in a facile and controllable way via a bottom-up strategy. The resulting nitrogen/chorine dual-doped catalyst CCTF-700 exhibits excellent ORR performance with a more positive onset and half-wave potential (0.85 V vs. RHE), higher diffusion-limited current density and significantly improved stability in comparison with the benchmark commercial 20 wt% Pt/C catalyst. It is worth mentioning that CCTF-700 shows one of the best ORR performances among all the reported metal-free electrocatalysts under alkaline conditions. This work paves the way for a controllable and reliable strategy to craft highly efficient heteroatom dual-doped carbon catalysts for energy conversion.

Newly Detected Transmission of blaKPC-2 by Outer Membrane Vesicles in Klebsiella Pneumoniae.

OBJECTIVE: The prevalence of carbapenem-resistant Klebsiella pneumoniae (CR-KP) is a global public health problem. It is mainly caused by the plasmid-carried carbapenemase gene. Outer membrane vesicles (OMVs) contain toxins and other factors involved in various biological processes, including ß-lactamase and antibiotic-resistance genes. This study aimed to reveal the transmission mechanism of OMV-mediated drug resistance of Klebsiella (K.) pneumoniae. METHODS: We selected CR-KP producing K. pneumoniae carbapenemase-2 (KPC-2) to study whether they can transfer resistance genes through OMVs. The OMVs of CR-KP were obtained by ultracentrifugation, and incubated with carbapenem-sensitive K. pneumoniae for 4 h. Finally, the carbapenem-sensitive K. pneumoniae was tested for the presence of blaKPC-2 resistance gene and its sensitivity to carbapenem antibiotics. RESULTS: The existence of OMVs was observed by the electron microscopy. The extracted OMVs had blaKPC-2 resistance gene. After incubation with OMVs, blaKPC-2 resistance gene was detected in sensitive K. pneumoniae, and it became resistant to imipenem and meropenem. CONCLUSION: This study demonstrated that OMVs isolated from KPC-2-producing CR-KP could deliver blaKPC-2 to sensitive K. pneumoniae, allowing the bacteria to produce carbapenemase, which may provide a novel target for innovative therapies in combination with conventional antibiotics for treating carbapenem-resistant Enterobacteriaceae.

Protein Phosphatase 2A as a Drug Target in the Treatment of Cancer and Alzheimer's Disease.

Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase which participates in the regulation of multiple cellular processes. As a confirmed tumor suppressor, PP2A activity is downregulated in tumors and its re-activation can induce apoptosis of cancer cells. In the brains of Alzheimer's disease (AD) patients, decreased PP2A activity also plays a key role in promoting tau hyperphosphorylation and Aß generation. In this review, we discussed compounds aiming at modulating PP2A activity in the treatment of cancer or AD. The upstream factors that inactivate PP2A in diseases have not been fully elucidated and further studies are needed. It will help for the refinement and development of novel and clinically tractable PP2A-targeted compounds or therapies for the treatment of tumor and AD.

Erratum to: Protein Phosphatase 2A as a Drug Target in the Treatment of Cancer and Alzheimer's Disease.

The article "Protein Phosphatase 2A as a Drug Target in the Treatment of Cancer and Alzheimer's Disease", written by Hui WEI, Hui-liang ZHANG, Jia-zhao XIE, Dong-li MENG, Xiao-chuan WANG, Dan KE, Ji ZENG, Rong LIU, was originally published electronically on the publisher's internet portal on 13 March 2020 without open access. With the author(s)' decision to opt for Open Choice the copyright of the article changed to © The Author(s) 2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.The original article has been corrected.Corresponding authors: Dan KE, E-mail: kedan@hust.edu.cn; Ji ZENG, E-mail: whzjmicro@163.com.

Alterations of fatty acid composition and metabolism in APP/PS1 transgenic mice.

Accumulating evidence suggests that abnormal fatty acid composition is related to the development of Alzheimer's disease (AD). However, there is no consistency in the fatty acid profile and metabolism associated with AD pathogenesis. This study aims to define the characteristics of fatty acid composition and metabolism in AD. Using 6-month-old APP/PS1 transgenic mice with wild-type mice as a control, we examined the serum lipids, brain fatty acid composition, and the expression levels of various genes involved in liver fatty acid ß-oxidation. The results of our study demonstrate that APP/PS1 mice present decreased serum free fatty acids, altered brain fatty acid profiles, and minimal change in liver fatty acid ß-oxidation. Our results suggest that abnormal fatty acid compositions and contents may play potential roles in AD progression. This study provides further evidence for the metabolic basis of AD pathogenesis.

Migration-Prevention Strategy to Fabricate Single-Atom Fe Implanted N-Doped Porous Carbons for Efficient Oxygen Reduction.

It is highly desired but challenging to achieve highly active single-atom Fe sites from iron-based metal-organic frameworks (MOFs) for efficient oxygen reduction reaction (ORR) due to the easy aggregation of iron species and formation of the inactive Fe-based particles during pyrolysis. Herein, a facile migration-prevention strategy is developed involving the incorporation of polyaniline (PANI) into the pores of iron porphyrinic-based MOF PCN-224(Fe) and followed by pyrolysis to obtain the single-atom Fe implanted N-doped porous carbons material PANI@PCN-224(Fe)-900. The introduced PANI inside the pores of PCN-224(Fe) not only served as protective fences to prevent the aggregation of the iron species during thermal annealing, but also acted as nitrogen sources to increase the nitrogen content and form Fe-Nx-C active sites. Compared with the pristine PCN-224(Fe) derived carbonization sample containing Fe-based particles, the carbonaceous material PANI@PCN-224(Fe)-900 without inactive Fe-based particles exhibited superb ORR electrocatalytic activity with a more positive half-wave potential, significantly improved stability in both alkaline media, and more challenging acidic condition. The migration-prevention strategy provides a new way to fabricate atomically dispersed metal active sites via pyrolysis approach for promoting catalysis.

Unraveling the relationship between the morphologies of metal-organic frameworks and the properties of their derived carbon materials.

Metal-organic framework (MOF) derived carbon materials are promising for energy storage and conversion as they could inherit the advantages of MOF precursors, such as high porosity, large surface area and uniform heteroatom doping. Although the morphologies of MOF precursors have a significant effect on the properties of the resulting materials, up to now, there has been no systematic study on the relationship of the morphologies of MOFs and the properties of their pyrolized carbonaceous materials. Herein, three isomorphous imidazolate-based ZIF-7 materials with different morphologies (sphere, polyhedron and rod shape) have been selected as precursors and carbonized to obtain porous N-doped carbon materials with a tunable morphology, pore features and surface areas. The spherical precursor ZIF-7-S with an average size of 45 nm was cross-linked to form carbon networks during pyrolysis, while the rod shape of ZIF-7-R (0.6 µm in diameter and 3 µm in length) was well retained in the NC-R-800 material. NC-D-800 derived from polyhedral ZIF-7-D (125 nm) was constructed by partially interlinked particles and interparticle mesopores were formed. NC-D-800 has the highest Brunauer-Emmett-Teller (BET) surface area of 538 m2 g-1 of the three carbon materials. Moreover, NC-D-800 shows superiority over NC-S-800 and NC-R-800 in the oxygen reduction reaction. This work discloses that the morphologies of MOF precursors could indeed affect the morphologies, and physical and catalytic properties of their corresponding carbon materials.