Microstructure and Properties of AlCoCrFeNiTi High-Entropy Alloy Coatings Prepared by Laser Cladding

21-4N(5Cr21Mn9Ni4N)is extensively employed in the production of engine valves,operating under severe conditions.Apart from withstanding high-temperature gas corrosion,it must also endure the impact of cylinder explosion pressure.The predominant failure mode of 21-4N valves is abrasive wear.Surface coatings serve as an effective approach to prevent such failures.In this investigation,Laser cladding technology was utilized to fabricate AlCoCrFeNiTi high entropy alloy coatings onto the surfaces of 21-4N valves.According to the findings,the cladding zone has a normal dendritic microstructure,a good substrate-to-cladding layer interaction,and no obvious flaws.In terms of hardness,the cladding demonstrates an average hardness of 620 HV.The hardness has increased by 140%compared to the substrate.The average hardness of the cladding remains at approximately 520 HV even at elevated temperatures.Regarding frictional wear performance,between 400℃and 800℃,the cladding layer exhibits an average friction coefficient of 0.4,with the primary wear mechanisms being abrasive wear,adhesive wear,and a minor degree of plastic deformation.

RETRACTED ARTICLE:SARS-CoV-2 infects T lymphocytes through its spike protein-mediated membrane fusion

The authors have retracted this article [1]. After the publication ofthis article, it came to the authors attention that in order tosupport the conclusions of the study, the authors should haveused primary T cells instead of T cell lines. Additionally, there areconcerns that the flow cytometry methodology applied here wasflawed. These points resulted in the conclusions being consideredinvalid.

Corrosion mechanism investigation of TiN/Ti coating and TC4 alloy for aircraft compressor application

It is imperative to develop multifunctional erosion and corrosion resistant coatings for compressor blades of aircraft engines in harsh environment.PVD(Physical Vapor Deposition)technology has the advances in processing erosion-resistant coatings;however,the performance of PVD coatings to combat corrosion depends on various coating defects.Determining and comparing the corrosion performances of PVD TiN/Ti coating and uncoated TC4 alloy was the main objective of present work.The 960 h salt spray corrosion and 116 h hot corrosion tests were conducted to simulate the grounding and working environments of the aircraft compressors.The corrosion mechanisms due to the coating defects such as pinhole,columnar boundary and large grain were analyzed based on the OM,Confocal microscope,electrochemical measurements,SEM,XRD and EDS results.Owing to the disordered state associated with the columnar boundary and the coating defect,nitrogen could be easily replaced by oxygen in the hot corrosion process,these structures were channels for fast diffusion of oxygen.Moreover,the Gibbs energy changes of Ti oxidation and TiN oxidation were thermodynamically calculated according to the working condition of aircraft compressors,and considerable research effort was focused on mapping out the phase diagram of Ti,TiN and high pressure gases.The findings of this research can provide insights into developing multifunctional coatings for future aircraft engines.

Retraction Note to:SARS-CoV-2 infects T lymphocytes through its spike protein-mediated membrane fusion

The authors have retracted this article1.After the publication of this article,it came to the authors attention that in order to support the conclusions of the study,the authors should have used primary T cells instead of T-cell lines.In addition,there are concerns that the flow cytometry methodology applied here was flawed.These points resulted in the conclusions being considered invalid.

Effect of chlorine dioxide on avian influenza A(H7N9)virus

Avian influenza remains a threat to human wellbeing.Hypochlorite derivatives are commonly used as disinfectants to prevent the spread of the disease.The World Health Organization(WHO)has listed chlorine dioxide(ClO_(2))as an A1‐level,safe,and efficient disinfectant.In this study,we tested the efficacy of ClO_(2),in aqueous solution and gas forms,against avian influenza A(H7N9)virus.The virus suspension was mixed with ClO_(2) aqueous solutions of various concentrations and for various time intervals.Aliquots of the mixture were then serially diluted,and the 50%tissue culture infective dose(TCID50)was measured with a hemagglutination test on MDCK cells.ClO_(2) gas produced from generators was introduced in a chamber containing the virus suspension in a Petri dish.The infective activity of the surviving virus was measured by the hemagglutination test.An aqueous solution of ClO_(2) at 126μg/mL for 15 s was effective given that no surviving virus was detected with the hemagglutination test.ClO_(2) gas at>5μL/L sustained for 1 h inactivated the virus effectively,while at 2.5μL/L for 1 h,it only partially inactivated the virus.ClO_(2) as gas or aqueous solution at a certain concentration is effective in inactivating the H7N9 virus,and can be applied for the decontamination and disinfection of environments.

ProtoporphyrinⅨand verteporfin potently inhibit SARS-CoV-2 infection in vitro and in a mouse model expressing human ACE2

The SARS-CoV-2 infection is spreading rapidly worldwide.Efficacious antiviral therapeutics against SARSCo V-2 is urgently needed.Here,we discovered that protoporphyrin IX(Pp IX)and verteporfin,two Food and Drug Administration(FDA)-approved drugs,completely inhibited the cytopathic effect produced by SARS-CoV-2 infection at 1.25 lmol/L and 0.31 lmol/L,respectively,and their EC50 values of reduction of viral RNA were at nanomolar concentrations.The selectivity indices of Pp IX and verteporfin were 952.74 and 368.93,respectively,suggesting a broad margin of safety.Importantly,Pp IX and verteporfin prevented SARS-CoV-2 infection in mice adenovirally transduced with human angiotensin-converting enzyme 2(ACE2).The compounds,sharing a porphyrin ring structure,were shown to bind viral receptor ACE2 and interfere with the interaction between ACE2 and the receptor-binding domain of viral S protein.Our study suggests that Pp IX and verteporfin are potent antiviral agents against SARS-CoV-2 infection and sheds new light on developing novel chemoprophylaxis and chemotherapy against SARS-CoV-2.