This work elaborated the underlying mechanism for the non-passivation of CoCrFeMnNi HEA in chloride solution based on the dissolution-diffusion-deposition model. A novel N-alloying strategy was ...proposed to significantly improve the corrosion resistance of CoCrFeMnNi HEA. Modelling results indicated that N could consume H+ and relieve the acidification on the surface of HEA, thus accelerating deposition of Cr and Fe oxides and hydroxides. Thereby, the nucleation rate and growth rate of passive film were apparently enhanced after N-alloying, which agreed well with the less defective and thinner passive film. Finally, the element selection for designing corrosion resistant HEAs was recommended.
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•The model describing passive film formation on CoCrFeMnNi HEA was established.•The non-passivation of CoCrFeMnNi HEA in chloride solution was interpreted.•N accelerated passive film deposition and dramatically enhanced corrosion resistance.•The model gave recommendation for designing corrosion resistant HEAs.
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•Effect of N on corrosion of steel in S2O32−-Cl- solution was firstly reported.•N significantly enhanced corrosion resistance of 316 L in S2O32−-Cl- solution.•N restrained reduction ...of S2O32− by consuming H+ and alleviated its harmful effect.•N reduced defects and raised fraction of Cr2O3 and Fe2O3 in passive film.
Thiosulfate is a threat to corrosion resistance of steels in chloride solution. This work revealed the inhibitory effect of nitrogen (N) on thiosulfate-accelerated corrosion of stainless steel by electrochemical measurements, microscopy observation and X-ray photoelectron spectroscopy analyses. Results manifested that N-alloying significantly enhanced pitting corrosion resistance and repassivation ability of 316 L steel in thiosulfate-chloride solution. On the one hand, N consumed H+, then restrained reduction of S2O32− and subsequent formation of S and MS2. On the other hand, N reduced defect density and strengthened passive film by increasing fraction of Cr2O3 and Fe2O3, thus improving protective ability of passive film.
Abstract
Exposing and stabilizing undercoordinated platinum (Pt) sites and therefore optimizing their adsorption to reactive intermediates offers a desirable strategy to develop highly efficient ...Pt-based electrocatalysts. However, preparation of atomically controllable Pt-based model catalysts to understand the correlation between electronic structure, adsorption energy, and catalytic properties of atomic Pt sites is still challenging. Herein we report the atomically thin two-dimensional PtTe
2
nanosheets with well-dispersed single atomic Te vacancies (Te-SAVs) and atomically well-defined undercoordinated Pt sites as a model electrocatalyst. A controlled thermal treatment drives the migration of the Te-SAVs to form thermodynamically stabilized, ordered Te-SAV clusters, which decreases both the density of states of undercoordinated Pt sites around the Fermi level and the interacting orbital volume of Pt sites. As a result, the binding strength of atomically defined Pt active sites to H intermediates is effectively reduced, which renders PtTe
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nanosheets highly active and stable in hydrogen evolution reaction.
Autophagy is crucial for maintaining cell homeostasis. However, the precise mechanism underlying autophagy initiation remains to be defined. Here, we demonstrate that glutamine deprivation and ...hypoxia result in inhibition of mTOR-mediated acetyl-transferase ARD1 S228 phosphorylation, leading to ARD1-dependent phosphoglycerate kinase 1 (PGK1) K388 acetylation and subsequent PGK1-mediated Beclin1 S30 phosphorylation. This phosphorylation enhances ATG14L-associated class III phosphatidylinositol 3-kinase VPS34 activity by increasing the binding of phosphatidylinositol to VPS34. ARD1-dependent PGK1 acetylation and PGK1-mediated Beclin1 S30 phosphorylation are required for glutamine deprivation- and hypoxia-induced autophagy and brain tumorigenesis. Furthermore, PGK1 K388 acetylation levels correlate with Beclin1 S30 phosphorylation levels and poor prognosis in glioblastoma patients. Our study unearths an important mechanism underlying cellular-stress-induced autophagy initiation in which the protein kinase activity of the metabolic enzyme PGK1 plays an instrumental role and reveals the significance of the mutual regulation of autophagy and cell metabolism in maintaining cell homeostasis.
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•Glutamine deprivation and hypoxia result in ARD1-dependent PGK1 K388 acetylation•PGK1 functioning as a protein kinase phosphorylates Beclin1 at S30•Beclin1 S30 phosphorylation enhances VPS34-Beclin1-ATG14L complex activity•Beclin1 S30 phosphorylation is required for autophagy initiation and tumorigenesis
Qian et al. demonstrate that glutamine deprivation and hypoxia inhibit mTOR and mTOR-dependent ARD1 S228 phosphorylation, which allows ARD1 to bind to PGK1 for PGK1 K388 acetylation. The acetylated PGK1 binds to and phosphorylates Beclin1 at S30, leading to activation of the VPS34-Beclin1 complex to initiate autophagosomal formation.
A number of important reactions such as the oxygen evolution reaction (OER) are catalyzed by transition metal oxides (TMOs), the surface reactivity of which is rather elusive. Therefore, rationally ...tailoring adsorption energy of intermediates on TMOs to achieve desirable catalytic performance still remains a great challenge. Here we show the identification of a general and tunable surface structure, coordinatively unsaturated metal cation (MCUS), as a good surface reactivity descriptor for TMOs in OER. Surface reactivity of a given TMO increases monotonically with the density of MCUS, and thus the increase in MCUS improves the catalytic activity for weak-binding TMOs but impairs that for strong-binding ones. The electronic origin of the surface reactivity can be well explained by a new model proposed in this work, wherein the energy of the highest-occupied d-states relative to the Fermi level determines the intermediates’ bonding strength by affecting the filling of the antibonding states. Our model for the first time well describes the reactivity trends among TMOs, and would initiate viable design principles for, but not limited to, OER catalysts.
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•Mo reduces lattice distortion and increases structural stability of high N MSSs.•Pressurized metallurgy and Mo-alloying increase N solubility in solid solution.•Mo-alloying reduces ...M2N content and alleviates detrimental effect of Cr-depletion.•Mo-alloying significantly improves corrosion resistance of high N MSSs.
In this work, a new high corrosion resistant martensitic stainless steel (MSS) containing high nitrogen content (N > 0.33 wt.%) was designed based on density functional theory (DFT) calculation and pressurized metallurgy. The results indicate that Mo-N alloying significantly improve the corrosion resistance of MSS. This observation has been explained from point of view of crystal structural stability, wherein the reduced formation energy, bonding energy, density of state (DOS) and lattice distortion. It results in the increasing N content in solid solution and the decreasing fractions of Cr depletion induced by the precipitation of Cr2N.
Semiconductor‐based photocatalysis and photoelectrocatalysis have received considerable attention as alternative approaches for solar energy harvesting and storage. The photocatalytic or ...photoelectrocatalytic performance of a semiconductor is closely related to the design of the semiconductor at the nanoscale. Among various nanostructures, one‐dimensional (1D) nanostructured photocatalysts and photoelectrodes have attracted increasing interest owing to their unique optical, structural, and electronic advantages. In this article, a comprehensive review of the current research efforts towards the development of 1D semiconductor nanomaterials for heterogeneous photocatalysis and photoelectrocatalysis is provided and, in particular, a discussion of how to overcome the challenges for achieving full potential of 1D nanostructures is presented. It is anticipated that this review will afford enriched information on the rational exploration of the structural and electronic properties of 1D semiconductor nanostructures for achieving more efficient 1D nanostructure‐based photocatalysts and photoelectrodes for high‐efficiency solar energy conversion.
One‐dimensional nanostructured photocatalysts and photoelectrodes are reviewed in a comprehensive manner. The basic principles of photocatalysis and photoelectrocatalysis, strategies for improving the photocatalytic and photoelectrochemical water splitting performances of 1D semiconductors, and applications of 1D semiconductors in these two fields are elucidated. Moreover, the challenges and perspectives for achieving full potential of 1D nanostructures are discussed.
Considering hydrogen deteriorates the mechanical properties of pipeline steel, and may leads to premature failure of pipe, the dynamic burst behavior of X100 steel pipeline with hydrogen damage under ...internal high pressure was numerically studied in this work based on the ductile damage theory. Two models describing the dependence of failure strain ε‾0pl and the fracture energy Gf on hydrogen coverage φ were developed, and then they were incorporated into ABAQUS by a user defined VUSDFLD FORTRAN subroutine. After validating the model, the effect of different parameters, including hydrogen distribution, hydrogen concentration, stress-induced hydrogen enrichment effect, the diameter-to-thickness ratio and the geometry defects on the dynamic burst behavior of pipe were thoroughly studied, and the ultimate burst pressure and the burst morphology of pipe were shown. It indicated that the ductility of pipe decreases a lot while the burst strength was less affected when hydrogen damage was considered, thus sudden failure may occur without perceptible deformation. Besides, in the presence of corrosion defects, the burst strength decreases almost linearly as the corrosion depth increases.
•A simplified numerical simulation method for burst behavior of pipe with hydrogen damage was proposed.•Analytical models describing fail strain and fracture energy on hydrogen coverage were developed.•User defined VUSDFLD FORTRAN subroutine was developed for damage simulation.•The dynamic burst characteristic of pipe under different loading conditions was thoroughly studied.
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