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•NCDs effectively suppress copper corrosion in aggressive acid medium.•NCDs can be designated as a modest cathodic-type inhibitor.•The NCDs–adsorption film involves both physisorption ...and chemisorption.
Researchers recent reported that N-doped carbon dots (NCDs) effectively inhibit steel corrosion in HCl solution, whereas the action mechanism is still uncertain to date. Herein, novel NCDs have been prepared using a facile hydrothermal method. Combining electrochemical, weight loss, and micromorphology techniques, the resultant NCDs were found to effectively suppress copper corrosion in aggressive H2SO4 medium. NCDs–adsorption film was formed on copper substrate as a barrier that could prevent transportation of corrosive particles. The relevant anticorrosion mechanism of NCDs was proposed in detail, which could provide powerful guidance to design and synthesis new nanomaterials for metal protection from corrosion.
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•Superhydrophobic GP was prepared by one step reaction between POSS-NH2 and GO.•The graft of POSS in GP nanosheets was greatly improved the dispersity of GO.•Anti-corrosion and ...anti-wear abilities of EP was enhanced by superhydrophobic GP.
Super-hydrophobic polyhedral oligomeric silsesquioxane functionalized graphene oxide (GP) was synthesized by one-step condensation reaction. Addition of 0.5 wt% GP into epoxy matrix (0.5 wt% GP/EP) could enhance the impedance by 2 orders of magnitude after 150 days immersion compared with pure epoxy (EP) coating. Moreover, the 0.5 wt% GP/EP specimen displayed better lubrication properties than EP, 0.5 wt% GO/EP, and 1 wt% GP/EP composites. Such outstanding anti-corrosion and wear-resistant abilities were ascribed to the comprehensive action of repellent GP with excellent shielding effect, the self-lubrication of GP with well dispersibility and the great improvement of mechanical property.
Graphene （G） was dispersed uniformly in water and used as an inhibitor in waterborne epoxy coatings. The effect of dispersed G on anticorrosion performance of epoxy coatings was evaluated. The ...composite coatings displayed outstanding barrier properties against H20 molecule compared to the neat epoxy coating. Open circuit potential （OCP）, Tafel and electrochemical impedance spectroscopy （EIS） analysis confirmed that the corrosion rate exhibited by composite coatings with 0.5 wt% G was an order of magnitude lower than that of neat epoxy coating. Salt spray test results revealed superior corrosion resistance offered by the composite coating.
Graphene(G)-based polymer nanocomposites have attracted great interest owing to their superior physicochemical properties over polymers. However, the tendency of graphene sheets to aggregate makes it ...difficult to achieve homogenous dispersion in polymer matrix. Herein, by utilization of poly(2-butylaniline) (P2BA) as a dispersing agent, stable dispersion of graphene in organic solvents was achieved via non-covalent π-π interactions between P2BA and graphene nanosheets. The exfoliated graphene nanosheets were then integrated with coating matrix by curing reaction of epoxy resin with P2BA functionalized graphene (P2BA-G) and amine hardener. Embedding a small percentage of well-dispersed graphene nanosheets (P2BA0.5%-G0.5%) in epoxy coating remarkably improved anticorrosion performance and wear resistance properties, which was attributed to the synergistic effects of the redox catalytic capability of P2BA, high mechanical and barrier properties of well-dispersed graphene nanosheets in the epoxy matrix. The present study provides a promise strategy for development of graphene reinforced organic coatings with superior physical-mechanical properties for metal protection.
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•MgAl-NO2 LDH was synthesized by acidizing shock treatment of Mg-Al-CO3 and ion exchange.•LDH can be regarded as a transit station, receiving chloride ions and releasing nitrite ...ions.•The electrochemical impedance of the coating improved significantly after adding LDH nanofillers.•Controllable release of nitrite realizes self-repairing of coatings
Layered double hydroxide (LDH) with NO2− intercalation was successfully prepared via acidification oscillation and ion exchange. The nano-fillers were incorporated into the resin to prepare anti-corrosion coatings with the thickness of ca. 50 ± 5 μm. The electrochemical and self-repairing properties of the LDH-doped coatings were studied by EIS and LEIS. Results indicated that the addition of LDH loaded with nitrite induced obvious increased in the impedance of coating (from 4.64 × 108 Ω cm2 to 2.14 × 1010 Ω cm2) and improved the anticorrosion performance of the coating. In addition, the localized corrosion of coatings could be largely inhibited, and the released nitrite ions from LDH interlayers exhibited active anticorrosion functions. When LDH nanosheets were added to the coatings, the lamella structures improved the barrier performances of the coatings. At the same time, the excellent ion exchanges ability of LDH could be used as storage stations for chloride ions, and the release of nitrite ions could play an active anti-corrosion role. Both of them cooperated to synergistically improve the anti-corrosion performance of the coating.
Laser cleaning is a high-efficient, newly emerging and environmentally friendly technology. Removing paint from aircraft skin is an important application of this technology. This paper describes how ...a high repetition frequency fiber laser of 1064 nm was used to remove the 50-μm-thick polyacrylic resin primer paint layer on an aircraft skin (LY12 aluminum alloy plate). Experiments were conducted to study the cleaning performance by varying process parameters such as scanning speed, pulse frequency, scanning line interval and laser power. This paper found that the quality and efficiency could be improved by selecting the appropriate combination of scanning speed and pulse frequency. The amount of paint stripped by the single pulsed laser increased with an increase in laser power. By analyzing the cleaned surface and the particles collected from the process, we propose three different kinds of possible stripping mechanisms: combustion reaction, thermal stress vibration effect and plasma shock effect.
Sirt1 is a member of the sirtuin family of proteins and has important roles in numerous biological processes. Sirt1
mice display an increased frequency of abnormal spermatozoa, but the mechanism of ...Sirt1 in spermiogenesis remains largely unknown. Here, we report that Sirt1 might be directly involved in spermiogenesis in germ cells but not in steroidogenic cells. Germ cell-specific Sirt1 knockout mice were almost completely infertile; the early mitotic and meiotic progression of germ cells in spermatogenesis were not obviously affected after Sirt1 depletion, but subsequent spermiogenesis was disrupted by a defect in acrosome biogenesis, which resulted in a phenotype similar to that observed in human globozoospermia. In addition, LC3 and Atg7 deacetylation was disrupted in spermatids after knocking out Sirt1, which affected the redistribution of LC3 from the nucleus to the cytoplasm and the activation of autophagy. Furthermore, Sirt1 depletion resulted in the failure of LC3 to be recruited to Golgi apparatus-derived vesicles and in the failure of GOPC and PICK1 to be recruited to nucleus-associated acrosomal vesicles. Taken together, these findings reveal that Sirt1 has a novel physiological function in acrosome biogenesis.
Cells have evolved the DNA damage response (DDR) pathways in response to DNA replication stress or DNA damage. In the ATR-Chk1 DDR pathway, it has been proposed that ATR is recruited to RPA-coated ...single-stranded DNA (ssDNA) by direct ATRIP-RPA interaction. However, it remains elusive how ATRIP is recruited to ssDNA in an RPA-independent manner. Here, we provide evidence that APE1 directly associates ssDNA to recruit ATRIP onto ssDNA in an RPA-independent fashion. The N-terminal motif within APE1 is required and sufficient for the APE1-ATRIP interaction in vitro and the distinct APE1-ATRIP interaction is required for ATRIP recruitment to ssDNA and the ATR-Chk1 DDR pathway activation in
egg extracts. In addition, APE1 directly associates with RPA70 and RPA32 via two distinct motifs. Taken together, our evidence suggests that APE1 recruits ATRIP onto ssDNA in an RPA-dependent and -independent manner in the ATR DDR pathway.
The contents and forms of nitrogen (N), phosphorus (P), and organic carbon (C) were determined with 40 cm (approximately 1600 s) core sediments from Erhai Lake on the Yungui Plateau of China as the ...sample. The vertical distribution characteristics, coupling relationships and ecological indicator significance of C–N–P were studied and identified. The results showed that the total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) contents were in the ranges of 1436–8255 mg·kg
−1
, 1287–5462 mg·kg
−1
, and 870.26–1507.74 mg·kg
−1
, respectively. In the Erhai Lake sediments, the main forms of TOC, organic nitrogen (ON) and organic phosphorus (OP) were humus, TN, and TP, respectively. The deposition of C, N, and P in the Erhai Lake sediments was divided into four periods. In the initial development period (from 40 to 23 cm), C, N and P were deposited and released synchronously; the main form of N was nontransferable total nitrogen (NTN), and that of P was inorganic phosphorus (IP). In the ecological recovery period (from 22 to 14 cm), C and N were deposited synchronously, and their deposition amounts were more than that of P. C, N and P were released synchronously. The main form of N was transferable total nitrogen (TTN), and that of P was IP. In the rapid economic growth period (from 13 to 0 cm), C, N, and P were deposited and released synchronously; the main form of N was NTN, and that of P was OP. In comparison to the other periods, this period was a period of higher active soil organic carbon (ASOC). In the integrated management period (surface sediment), C and N were deposited and released synchronously, and their deposition amounts were greater than that of P. The main form of N was NTN, that of P was OP, and the ASOC content was high. When exogenous inputs were the main sources of C, N, and P, the deposition forms of P and N were mainly OP and NTN, respectively, and those of IP and TTN were calcium-bound P (Ca–P) and ion-exchange form N (IEF–N), respectively. When endogenous inputs were the main sources of C, N and P, the deposition forms of P and N were mainly IP and TTN, respectively, and those of IP and TTN were Fe/Al–P and weak acid extractable form (WAEF–N), respectively. The content ratio of Ca–P and Fe/Al–P, as well as that of IEF–N and WAEF–N, could reflect the changes in the contribution of endogenous and exogenous sources to the Erhai Lake sediments.
In the paper, the underlying fundamental mechanisms of laser stripping of mixture paint of two polymers of polyacrylate resin and polyisocyanate resin are elucidated by molecular dynamics ...simulations, focusing on the mechanisms of breakage of bonds. In addition, experimental investigations of stripping mixture paint are conducted with a pulsed Nd:YAG laser in the air. The formed gas products and the residual paint surface during laser stripping are analyzed by GC/MS, FTIR, XPS, and RISE. Simulation results indicate that the breaking of the C–N bonds is the origin of the damage of polymers and facilitates the fracture process of polymers chain, leading to evaporation of individual atoms and single-chain excitation which is closely accompanied by breaking and rearrangement of the bonds. The main microscopic destruction mechanisms of polymers revealed by simulations include breakage of bonds, dissociation of a carbon backbone with the evaporation of individual atoms, and new components produced by rearrangement of bonds, which is very consistent with the experimental results. The structural damage of polymers has a significant influence on stimulating the stripping of the paint with laser loading. The resulting experimental and theoretical observations can provide a guideline and practical references for a better understanding of the mechanism of the paint removal.
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