Construction of a sandwich-like Gr/Ni composite coating on AZ91D magnesium alloy to achieve excellent corrosion and wear resistances in the seawater

Preventing AZ91D magnesium alloy from severely wear and corrosion should be of significance so as to extend its applications. In this work, we systemically investigated graphene (Gr) doping concentration to influence the structure and performance of Gr/Ni composite coatings on AZ91D Mg alloy in the seawater. The results showed that the optimal Gr doping Gr/Ni composite coating on Mg alloy could possess much higher hardness and better adhesive strength as well as much lower wear rate in the seawater. Moreover, the novel composite sandwich structure was utilized to construct multi-interfacial Gr/Ni composite coating on AZ91D Mg alloy, which successfully achieved much more excellent long-term corrosion and wear resistances in the marine. Density functional theory calculations clarified the mechanism of sequential adsorption of nickel to graphene, indicating that it easily gave rise to graphene agglomeration in electroplating process. However, the multi-interfaces could provide more stretching space for graphene sheets and reduce the folding tendency of graphene. These results indicated that the sandwich-like structure Gr/Ni composite coating brought excellent properties for AZ91D magnesium alloy to enhance its services in the marine and aviation environments

Achieving Good Protection on Ultra-High Molecular Weight Polythene by In Situ Growth of Amorphous Carbon Film

Ultra-high molecular weight polythene (UHMWPE), with outstanding characteristics, is widely applied in modern industry, while it is also severely limited by its inherent shortcomings, which include low hardness, poor wear resistance, and easy wear. Implementation of feasible protection on ultra-high molecular weight polythene to overcome its shortcomings would be of significance. In the present study, amorphous carbon (a-C) film was fabricated on ultra-high molecular weight polythene (UHMWPE) to provide good protection, and the relevant growth mechanism of a-C film was revealed by controlling carbon plasma currents. The results showed the in situ transition layer, in the form of chemical bonds, was formed between the UHMWPE substrate and the a-C film with the introduction of carbon plasma, which provided strong adhesion, and then the a-C film continued epitaxial growth on the in situ transition layer with the treatment of carbon plasma. This in situ growth of a-C film, including the in situ transition layer and the epitaxial growth layer, significantly improved the wetting properties, mechanical properties, and tribological properties of UHMWPE. In particular, good protection by in situ growth a-C film on UHMWPE was achieved during sliding wear

Anti-Metastatic Benefits Produced by Hyperthermia and a CCL3 Derivative

Significant numbers of malignant tumor cells that have spread to surrounding tissues and other distant organs are often too small to be picked up in a diagnostic test, and prevention of even such small metastases should improve patient outcomes. Using a mouse model, we show in this article that intravenous administration of a human CCL3 variant carrying a single amino acid substitution after mild local hyperthermia not only induces tumor growth inhibition at the treated site but also inhibits metastasis. Colon26 adenocarcinoma cells (1 × 105 cells/mouse) were grafted subcutaneously into the right hind leg of syngeneic BALB/c mice and after nine days, when tumor size reached ~11 mm in diameter, the local tumor mass was exposed to high-frequency waves, by which intratumoral temperature was maintained at 42 °C for 30 min. Mice received the CCL3 variant named eMIP (2 μg/mouse/day) intravenously for five consecutive days starting one day after heat treatment. We found that tumor growth in eMIP recipients after hyperthermia was inhibited markedly but no effect was seen in animals treated with either hyperthermia or eMIP alone. Furthermore, the number of lung metastases evaluated at 18 days after hyperthermia treatment was dramatically reduced in animals receiving the combination therapy compared with all other controls. These results encourage future clinical application of this combination therapy

Approach to excellent superhydrophobicity and corrosion resistance of carbon-based films by graphene and cobalt synergism

A new series of carbon-based films doped with graphene oxide and cobalt (G-Co/a-C:H films) were successfully prepared on Si substrate via one-step electrochemical deposition of methanol as the carbon source and graphene oxide/cobalt as the dopant. G-Co/a-C:H films were fabricated at various graphene oxide concentration for comparative experiments. It can be found that the graphene oxide and cobalt were well embedded in amorphous carbon matrix to form superhydrophobic G-Co/a-C:H film at the doping GO concentration of 0.007 mg/mL, which was confirmed by transmission electron microscopy (TEM). It was noted that the superhydrophobicity of the resulting surface derives from its rough surface with hierarchical micro-nanostructures and the presence of the low-surface-energy GO components on it. The hierarchical micro-nanostructures are attributed to the corporate joint of GO and cobalt to form the multilevel nanoscale composite interface. Specially, the as-fabricated superhydrophobic G-Co/a-C:H film could exhibit excellent self-cleaning ability and corrosion resistance, revealed by the self-cleaning and corrosion tests

Outstanding superhydrophobicity and corrosion resistance on carbon-based film surfaces coupled with multi-walled carbon nanotubes and nickel nano-particles

In order to solve the problem of poor stability and repeatability of superhydrophobic films to improve its application in industrial production. In this study, nickel nanoparticles and multi-walled carbon nanotubes (MWCNTs) were doped into DLC films for the first time, and a robust superhydrophobic and corrosion resistance nanocomposite MWCNTs-Ni/a-C:H film was prepared via one-step electrochemical deposition under atmospheric pressure and low temperature. The as-prepared film surface had a static water contact angle measured as 158.89° and a sliding angle about 1.99° which is attributed to the micro-nanoscale hierarchical structure of the film surface. More importantly, the superhydrophobic nanocomposite MWCNTs-Ni/a-C:H film not only shows good mechanical property, but also has outstanding corrosion resistance and excellent self-cleaning ability. This research highlights a promising route for the preparation of robust superhydrophobic film, providing potential uses including self-cleaning, antifouling and anti-corrosion applications such as ship hulls and aeroplane wings.</p

Lentinan stabilized bimetallic PdPt₃ dendritic nanoparticles with enhanced oxidase-like property for L-cysteine detection

The development of nanozymes with enhanced catalytic activity has been drawing great interest. Lentinan with special structure may be used to prepare bimetallic nanomaterials to enhance their catalytic activity. Herein, lentinan stabilized PdPt3 dendritic nanoparticles (PdPt3-LNT NDs) were prepared through reduction of Na2PdCl4 and K2PtCl4 with a molar ratio of 1:3 using lentinan as a biological template. PdPt3-LNT NDs had dendritic shape with size of 10.76 ± 1.82 nm. PdPt3-LNT NDs had the hydrodynamic size about 25.7 nm and the zeta potential between −1.4 mV and − 4.9 mV at different pH. Furthermore, PdPt3-LNT NDs catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) to produce oxidized TMB, suggesting their oxidase-like property. The catalytic activity of PdPt3-LNT NDs was the highest when pH was 4 and the temperature was 40 °C. The catalytic mechanism was the generation of reactive oxygen species− from O2 catalyzed by PdPt3-LNT NDs. More importantly, L-cysteine detection method was set up based on the oxidase-like property of PdPt3-LNT NDs. This method had wide linear range for 0–200 μM and low detection limit for 3.099 μM. Taken together, PdPt3-LNT NDs have good potential applications in bio-related detection in the future.</p

Effects of uric acid-lowering therapy on the progression of chronic kidney disease: a systematic review and meta-analysis

Objectives: Whether uric acid levels were associated with the progression of chronic kidney disease (CKD) remained controversial. This meta-analysis was aimed to assess the effect of lowering serum uric acid therapy on the progression of CKD to clarify the role of uric acid in the progression of CKD indirectly. Methods: Pubmed, Embase, the Cochrane library, CBM were searched for randomized controlled trials (RCTs) that assessed the efficiency of lowering serum uric acid therapy on the progression of CKD without language restriction. Summary estimates of weighted mean differences (WMDs) and relative risk (RR) were obtained by using random-effect or fixed-effect models. Sensitivity analyses were performed to identify the source of heterogeneity. Results: A total of 12 randomized controlled trials with 832 CKD participants were included in the analysis. Pooled estimate for eGFR was in favor of lowering serum uric acid therapy with a mean difference (MD) of 3.88 ml/min/1.73 m2, 95% CI 1.26–6.49 ml/min/1.73 m2, p = .004 and this was consistent with results for serum creatinine. The risk of worsening of kidney function or ESRD or death was significantly decreased in the treatment group compared to the control group (RR 0.39, 95% CI 0.28–0.52, p< .01). Conclusions: Uric acid-lowering therapy may be effective in retarding the progression of CKD. Further randomized controlled trials should be performed to confirm the effect of lowering serum uric acid therapy on the progression of CKD

Comparative corrosion resistance of graphene sheets with different structures in waterborne epoxy coatings

Although substantial statements report the capability of graphene for corrosion prevention, its further application is limited by the non-comprehension of its structural variation in different coatings. Herein, graphene sheets with four structures were incorporated waterborne epoxy to fabricate different types of composite coatings (named EP-G(a), EP-G(b), EP-GO and EP-GS, respectively) as well as the pure waterborne epoxy coating was fabricated for comparison. The corrosion behaviors of as-fabricated coatings with and without graphene sheets were systematically characterized via potential, impedance testing and Tafel curves by immersing in 3.5 wt % NaCl solution. It was remarkable to point out that EP-G(a) composite coating could possess a promising long-term corrosion protection capability. The corrosion protection mechanism of graphene-based composite coatings were verified as the barrier effect of impermeable graphene sheets that confirmed by the analysis of corrosion products. Moreover, the scanning vibrating electrode technique in-depth revealed the relationship between the graphene structures and corrosion performances of the composite coatings. With the occurrence of commercialized application of graphene-based coatings, these works displayed a suitable approach toward the long-term corrosion behavior, which was able to be extended to other two-dimensional materials for anti-corrosion coatings