Boosting oxygen reduction durability by embedding Co9S8 nanoparticles into Co single atoms anchored porous carbon frameworks

Developing an efficient and low-cost oxygen reduction electrocatalyst is essential for the application of aqueous zinc-air batteries (ZABs). Herein, we report a facile adsorption-confined pyrolysis strategy to fabricate the hybrid electrocatalyst (denoted as Co9S8/CoSA-PC) by embedding Co9S8 nanoparticles into Co single atoms (Co-SAs) anchored porous carbon sheets for boosting oxygen reduction reaction (ORR) durability. In this strategy, the Co2+ ions are first absorbed into oxygen-rich porous carbon nanosheets and further form the Co-SAs with the help of thiourea in the following pyrolysis procedure, which is believed to be able to confine the generated Co9S8 nanoparticles into carbon frameworks due to their interface interaction. Benefiting from the synergistic effect of different components, the obtained Co9S8/CoSA-PC electrocatalyst for ORR exhibits outstanding catalytic activity with a half-wave potential of 0.82 V and a distinguished long-term durability with a current retention of 80 % after cycling 80 h under alkaline conditions, which is superior to commercial Pt/C. Moreover, the assembled ZABs with Co9S8/CoSA-PC as cathodic catalyst deliver a high specific capacity of 764 mAh gZn-1 at 10 mA cm-2 and the outstanding peak power density of up to 221.4 mW cm-2. This work provides a novel structure design strategy to prepare transition metal sulfide-based electrocatalysts with superior durability for ORR.

Carbon cloth supporting spinel CuMn0.5Co2O4 nanoneedles with the regulated electronic structure by multiple metal elements as catalysts for efficient oxygen evolution reaction

Developing transition metal oxide catalysts to replace the noble metal oxide catalysts for efficient oxygen evolution reaction (OER) is essential to promote the practical application of water splitting. Herein, we designed and constructed the carbon cloth (CC) supporting spinel CuMn_0.5Co₂O₄ nanoneedles with regulated electronic structure by multiple metal elements with variable chemical valences in the spinel CuMn_0.5Co₂O₄. The carbon cloth not only provided good conductivity for the catalytic reaction but also supported the well-standing spinel CuMn_0.5Co₂O₄ nanoneedles arrays with a large special surface area. Meanwhile, the well-standing nanoneedles arrays and mesoporous structure of CuMn_0.5Co₂O₄ nanoneedles enhanced their wettability and facilitated access for electrolyte to electrochemical catalysis. Besides, the regulated electronic structure and generated oxygen vacancies of CuMn_0.5Co₂O₄/CC by multiple metal elements improved the intrinsic catalytic activity and the durability of OER activity. Profiting from these merits, the CuMn_0.5Co₂O₄/CC electrode exhibited superior OER activity with an ultralow overpotential of 189 mV at the current density of 10 mA⋅cm^-2 and a smaller Tafel slope of 64.1 mV⋅dec^-1, which was competitive with the noble metal oxides electrode. And the CuMn_0.5Co₂O₄/CC electrode also exhibited long-term durability for OER with 95.3% of current retention after 1000 cycles. Therefore, the competitive OER activity and excellent cycling durability suggested that the CuMn_0.5Co₂O₄/CC electrode is a potential candidate catalyst for efficient OER.

Long-term durability after surgical aortic valve replacement with the Trifecta and the Intuity valve-a comparative analysis

OBJECTIVES

Long-term durability of surgical bio-prostheses is a key factor, especially in the era of transcatheter aortic valve replacement. We compared the incidence of structural valve deterioration (SVD) between patients undergoing surgical aortic valve replacement (SAVR) with the Trifecta (Abbott Laboratories, Abbott Park, IL, USA) or the Intuity valve (Edwards Lifesciences, Irvine, CA, USA).

METHODS

Between April 2010 and May 2020, 1118 patients underwent SAVR with the Trifecta (n = 346) and the Intuity (n = 772) valve at a single centre. A total of 1070 patients (Trifecta n = 298, Intuity n = 772) were analysed after the exclusion of patients with pure regurgitation and endocarditis. Retro- and prospective echocardiographic and clinical follow-up was performed. Cox proportional hazards regression models were performed to identify prognostic factors for SVD, aortic re-interventions and mortality.

RESULTS

With 27 cases (Trifecta n = 23, Intuity n = 4) of SVD observed, cumulative incidence of SVD was significantly higher in the Trifecta cohort (P < 0.001). Implantation of a Trifecta valve [hazard ratio (HR) 11.20; 95% confidence interval 3.79-33.09], log-transformed preoperative creatinine (HR 2.47; 1.37-4.44) and sex (male HR 0.42; 0.19-0.92) emerged as prognostic factors of SVD. A significantly higher cumulative incidence of re-interventions was observed in the Trifecta cohort (P = 0.004) and valve type was an independent time-varying risk factor (HR at 12 months 2.78; 95% confidence interval 1.42-5.45). Overall, no significant differences in all-cause mortality were observed between the groups (log-rank test: P = 0.052).

CONCLUSIONS

SVD was significantly more frequent in patients receiving a Trifecta valve and its implantation was an independent risk factor for the occurrence of SVD and aortic valve re-interventions. This comparative analysis of 2 low-gradient bioprosthesis put the long-term durability of the Trifecta valve in question and need to be taken into consideration when performing bioprosthetic SAVR.

Immunogenicity and persistence of high-dose recombinant hepatitis B vaccine in adults infected with human immunodeficiency virus in China: A randomized, double-blind, parallel controlled trial

OBJECTIVES

To explore the immunogenicity and persistence of the 60 µg hepatitis B vaccine in adults infected with human immunodeficiency virus (HIV).

METHODS

We conducted a randomised controlled trial for adults infected with HIV. A total of 182 patients were randomly allocated to receive 20 µg (IM20 group) or 60 µg (IM60 group) of recombinant hepatitis B vaccine at months 0, 1, and 6 to assess the immunogenicity and were followed-up from month 7 to 42 to assess long-term immunogenicity.

RESULTS

Our data showed that the response rate and geometric mean concentration (GMC) of antibodies to hepatitis B surface antigen (anti-HBs) in the IM60 group at month 7 were higher than those in the IM20 group (P > 0.05). The GMC of anti-HBs among the two groups decreased rapidly during the follow-up period (P > 0.05). Survival analysis showed that 25% of patients with anti-HBs ≥ 10 mIU/mL were 20 months in the IM60 group and 9.3 months in the IM20 group.

CONCLUSION

The three-dose 60 µg hepatitis B vaccine showed partially better immunogenicity and persistence than the three-dose 20 µg vaccine.

TRIAL REGISTRATION

The trial was registered on clinicaltrials.gov, NCT03316807.

Natural History of a Carpentier-Edwards Pericardial Aortic Valve Replaced after 25 Years for Structural Valve Degeneration

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SVD is a main limitation of bioprostheses.

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Routine use of bioprostheses in younger patients (<60 years of age) is controversial.

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Data on the durability of surgical aortic bioprostheses beyond 20 years are limited.

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We report exceptional durability of an aortic bioprosthesis replaced after 25 years.

Influence of Configuration on Stress Distribution of Pulmonary Monocusp Leaflet

PURPOSE

For the relief of right ventricular outflow tract obstruction in operative treatment of tetralogy of Fallot and other complex congenital heart diseases, transannular monocusp patch operations are often necessary to prevent right ventricular pressure overload and reduce pulmonary regurgitation. However, long-term durability of a monocusp leaflet is unsatisfactory, its failure is believed to be related to mechanical stress, whose distribution is primarily affected by geometric configurations. Therefore, the influence of several geometrical parameters on stress distribution of leaflet is investigated.

METHODS

Five parameters affecting leaflet configuration were established: angle between free edge of the leaflet and vessel wall, angle formed by the two end points of free edge, length of the free edge of the leaflet, height of the leaflet, and shape of elliptic conical surface constituting the leaflet surface. The first four parameters were fixed, and two factors were defined to describe the last parameter. Seven models with different values of these factors were analyzed using finite element method at the pressure of the pulmonary artery loaded on the leaflet.

RESULTS

The peak stresses of all models occurred at end points of the free edge of the leaflet (tear high-risk regions). The middle of leaflet had the greatest stress gradient and produced tissue wrinkling; this area could be the risk region of calcification. Both factors were noted to influence the stress distribution, and one of the factors could also relieve the wrinkling.

CONCLUSIONS

The leaflet of model (1.2_min) had the most even stress distribution and lowest peak principal stress, which was the optimal choice among all the models.

Mechanical properties and long-term durability of recycled polysulfone plastic

In view of the recycling of PSU plastics has a good energy saving and environmental protection significance. This paper is concerned with the mechanical properties, and long-term durability of virgin and recycled polysulfone plastics (PSU) collected from wasted PSU nonwovens, the mechanical experiment of tensile test and Izod impact test are carried out to investigate the effect of cycle processing on the performance of PSU. The long-term durability of virgin and recycled PSU is studied base on time-temperature superposition by using a dynamic mechanical analysis (DMA). The thermal stability is evaluated by pyrolytic activation energy calculated by Iso-conversional kinetics method using a Thermogravimetric analysis (TGA). The results show that the recycled PSU exhibits the similar tensile property while lower impact strength than virgin PSU. The long-term durability and thermal stability of virgin PSU are better than recycled PSU and decreased with increasing the times of cycle processing, which is attributed to the mixing of impurities and degradation of the molecular structure in the recycling process.