Li含量对Mg-xLi-3(Al-Si)合金显微组织和力学性能的影响（英文）

基于α-Mg、α-Mg+β-Li和β-Li三种相结构,制备Mg-4Li-3(Al-Si)、Mg-8Li-3(Al-Si)和Mg-12Li-3(Al-Si)三种合金,用于研究Al-Si共晶体对其组织和力学性能的影响。在Mg-xLi(x=4%,8%和12%,质量分数)合金中添加Al-Si共晶体分别形成以下的Al-Li析出相:Al3Li、AlLi和Li3Al2。此外,在这三种合金中还发现大量的Mg2Si相颗粒。拉伸试验结果表明,Mg-4Li-3(Al-Si)合金的极限抗拉强度最高,为249MPa,其伸长率最低,为6.3%。Mg-12Li-3(Al-Si)合金的伸长率最高,为26%,但极限抗拉强度最低,为173 MPa。这三种合金力学性能的差异归因于晶体结构的不同以及析出物类型、形态和分布的不同。

Mg−Ca合金表面的原位层状双氢氧化物:Ca在镁合金中的作用

采用原位生长法在铸态Mg−xCa(x=0.5,0.8,2.0,质量分数,%)合金上制备Mg−Al双层氢氧化物(LDHs)。与镁基体相比,该合金具有良好的耐蚀性能。研究第二相(Mg_(2)Ca)对LDHs的影响机理。随着Ca含量的增加,Mg_(2)Ca的数量增加,导致Mg−xCa合金的晶粒尺寸减小,腐蚀速率降低。第二相数量的增加和晶粒细化促进LDHs的生长,从而降低Mg−xCa合金的腐蚀速率。同时,较高的Mg_(2)Ca数量使LDHs变得蓬松。由于第二相(Mg_(2)Ca)对LDHs的双重影响,LDHs/Mg−0.8Ca的腐蚀速率最低。

A self-healing coating based on facile pH-responsive nanocontainers for corrosion protection of magnesium alloy

The preparation of pH-responsive nanocontainers by typical silane modification of the mesoporous silica nanoparticle(MSN)surface is usually high-cost,complex,and time-consuming,which remains a great challenge for effective corrosion protection of magnesium alloy.Here,a new strategy to construct pH-responsive nanocontainers(MSN-MBT@LDH)is demonstrated.The nanocontainers consist of corrosion inhibitor(2-mercaptobenzothiazole,MBT)loaded MSN core and layered double hydroxide(LDH)nanosheet shell serving as gatekeepers.The successful loading of MBT and encapsulation by LDH nanosheets were confirmed by a series of characterization such as scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy(STEM-EDS)and N2 adsorption/desorption isotherms.The pH-responsive feature of the nanocontainers was demonstrated by determination of the MBT concentration in buffer solutions with different pH values.A smart corrosion protection system on Mg alloy is obtained by incorporating the synthesized nanocontainers into a self-assembled nanophase particle(SNAP)coating.The electrochemical tests and visual observations show that the hybrid coating has the best barrier properties and robustness in corrosion protection in NaCl corrosive solutions in comparison with the control coatings.The present method simplifies the synthesis processes of nanocontainers and eliminates the potential detrimental effect of excess gatekeepers on the coating.The findings provide new insights into the preparation of scalable nanocontainers.The self-healing coatings are expected to have widespread applications for corrosion protection of Mg alloy and other metals.

Review of advanced oxidation processes for treating hospital sewage to achieve decontamination and disinfection

Hospital sewage contains various harmful pharmaceutical contaminants(e.g.,antibiotics,anti-inflammatory agents,and painkillers)and pathogens(e.g.,bacteria,viruses,and parasites),whose direct discharge into the environment will induce diseases and pose a powerful threat to human health and safety,and environmental ecology.In recent years,advanced oxidation processes(AOPs),particularly photocatalysis,electrocatalysis,and ozone catalysis have been developed as widespread and effective techniques for hospital sewage treatments.However,there is a lack of systematic comparison and review of the prior studies on hospital sewage treatment using AOPs systems.This review elaborates on the mechanisms,removal efficiencies,and advantages/disadvantages of these AOPs systems for hospital wastewater decontamination and disinfection.Meanwhile,some novel and potential technologies such as photo-electrocatalysis,electro-peroxone,Fenton/Fenton-like,and piezoelectric catalysis are also included and summarized.Moreover,we further summarize and compare the capacity of these AOPs to treat the actual hospital wastewater under the impact of the water matrix and pH,and estimate the economic cost of these technologies for practical application.Finally,the future development directions of AOPs for hospital wastewater decontamination and disinfection have been prospected.Overall,this study provides a comparison and overview of these AOP systems in an attempt to raise extensive concerns about hospital wastewater decontamination and disinfection technologies and guide researchers to discover the future directions of technologies optimization,which would be a crucial step forward in the field of hospital sewage treatment.

Increased Efficacy of Antivenom Combined with Hyperbaric Oxygen on Deinagkistrodon acutus Envenomation in Adult Rats

Background：Snakebites are a neglected threat to global human health with a high morbidity rate.The present study explored the efficacy of antivenom with hyperbaric oxygen （HBO） intervention on snakebites,which could provide the experimental basis for clinical adjuvant therapy.Methods：Male Sprague-Dawley rats （n =96） were randomized into four groups：the poison model was established by injecting Deinagkistrodon acutus （D.acutus） venom （0.8 LD50） via the caudal vein;the antivenom group was injected immediately with specific antivenom via the caudal vein after successful establishment of the envenomation model;and the antivenom ＋ HBO group was exposed to HBO environment for 1 h once at predetermined periods of 0 h,4 h,12 h,and 23 h after antivenin administration.Each HBO time point had six rats;the control group was left untreated.The rats in the experimental group were euthanized at the corresponding time points after HBO therapy,and brain tissue and blood were harvested immediately.Hematoxylin and eosin （H＆E） staining was used to investigate the pathological changes in the rat brain.Immunohistochemistry （IHC）,real-time polymerase chain reaction （PCR）,and Western blotting were used to detect the expression ofNestin mRNA and protein in the subventricular zone （SVZ） of the brain.The levels of coagulation function （prothrombin time,activated partial thromboplastin time [APTT],and fibrinogen） and oxidation/antioxidation index （malondialdehyde [MDA] and superoxide dismutase [SOD]） were analyzed.Data were analyzed using one-way analysis of variance.Results：The brain tissue from rats in the poison model was observed for pathological changes using H＆E staining.Tissues showed edema,decreased cell number,and disordered arrangement in the SVZ in the snake venom group.The antivenom-HBO intervention significantly alleviated these observations and was more prominent in the antivenom ＋ HBO group.The serum levels of SOD and MDA in the snake venom group were increased and the antivenom-HBO intervention further increased the SOD levels but significantly decreased the MDA levels;however,this was enhanced within 1 h after HBO administration （MDA：F=5.540,P=0.008,SOD：F=7.361,P =0.000）.Activated partial thromboplastin time （APTT） was significantly abnormal after venom administration but improved after antivenom and was even more significant in the antivenom ＋ HBO group 5 h after envenomation （F =25.430,P =0.000）.Only a few nestin-positive cells were observed in the envenomation model.The expression levels were significant in the antivenom and antivenom ＋ HBO groups within 1 and 5 h after envenomation and were more significant in the antivenom ＋ HBO group as determined by IHC,real-time PCR,and Western blotting （P 〈 0.05）.D.acutus envenomation has neurotoxic effects in the brain of rats.Conclusions：Antivenin and HBO,respectively,induced a neuroprotective effect after D.acutus envenomation by attenuating brain edema,upregulating nestin expression in SVZ,and improving coagulopathy and oxidative stress.The intervention efficacy of antivenom with HBO was maximum within 5 h after envenomation and was more efficacious than antivenom alone.

One-pot scalable in situ growth of highly corrosion-resistant MgAl-LDH/MBT composite coating on magnesium alloy under mild conditions

Current corrosion-resistant layered double hydroxide(LDH)coating on Mg alloy is usually in situ grown in autoclave by hydrothermal methods under high temperature and high-pressure conditions,which is unfavorable for industrial application.We report that an inhibitor(2-mercaptobenzothiazole,MBT)incorporated composite(Mg Al-LDH/MBT)coating can be in situ deposited on bare AZ31 Mg alloy surface with the assistance of a chelating agent(ethylenediaminetetraacetic acid)under a relatively low temperature(95℃)and ambient pressure by a one-pot method.The successful formation of LDH/MBT composite coating is confirmed by a series of characterizations,such as X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and energy dispersive spectroscopy(EDS).The corrosion resistance of the composite coating is evaluated by means of hydrogen evolution measurement,electrochemical impedance spectroscopy(EIS),Tafel polarization curves,and neutral salt spray test.The tests show that the LDH/MBT composite coating has a very low corrosion current density(1.7310^(-8)A cm^(-2)),an extremely high charge transfer resistance(2.336 M cm^(2)),and does not show any corrosion pits even after 15 d of exposure to a Na Cl solution or 7 d of exposure to salt fog environment,manifesting the good and robust corrosion protection.Lastly,the deposition and corrosion protection mechanisms of the Mg Al-LDH/MBT composite coating are also discussed and proposed based on the EDS characterization of the coating after long-time exposure.

Coupling a titanium dioxide based heterostructure photoanode with electroless-deposited nickel-phosphorus alloy coating on magnesium alloy for enhanced corrosion protection

The utilization of photoelectrochemical cathodic protection(PECCP)enables an indirect corrosion pro-tection of metals with low self-corrosion potential by introducing a metallic nickel interlayer.However,the ability to enhance the PECCP efficiency remains challenging because of the inherent property of the semiconductor.Herein,this ability is demonstrated by coupling a covalent organic framework(TpBD)dec-orated TiO 2 photoanode(TiO 2/TpBD)with nickel coating on magnesium alloy for an effective corrosion protection.The composite photoanode showed direct PECCP for the nickel interlayer and indirect corro-sion protection of the magnesium alloy.The composite structure of the nanotube array and the covalent organic framework for the photoanode were confirmed by field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).The en-hanced photoelectrochemical conversion capability and PECCP performance of the nickel-coated Mg alloy were evidenced by the results from electrochemical and photoelectrochemical measurements including Mott-Schottky curves,photoinduced potential variations,and electrochemical impedance spectroscopy(EIS).Lastly,a corrosion protection mechanism is proposed,where the enhanced PECCP efficiency is at-tributed to the formation of a direct Z-scheme heterojunction,which is substantiated by the results from valence band(VB)XPS and electron spin resonance characterizations.