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In this work, the distribution and segregation behaviors of helium (He) and the effect of yttrium (Y) on these behaviors in the symmetrical tilt tungsten (W) Σ5(310)/[001] grain boundary (GB) region were studied using first-principles calculations. The results revealed that the GB has a significant impact on the behaviors of He in W. The solution and segregation energies of He in the W Σ5(310)/[001] GB region increase with increasing the distance from He to the GB and are inversely proportional to the effective electrons of He. The density of states analysis showed that the GB can suppress partial hybridization between He and W atoms. In addition, we find that the strengthening element Y facilitates the dissolution of He in the W GB region. [ABSTRACT FROM AUTHOR]

We have systematically investigated the solution and aggregation behaviors of yttrium (Y) on symmetrically inclined tungsten (W) grain boundary (GB) Σ 5 (310)/[001] by first-principles simulation. It is found that the most stable site for Y is located on the GB plane, and the solution energy of the Y substitutional site increases with increasing the distance from the GB plane. The charge redistribution of Y atoms is positively correlated with the solution energy, i.e., the deviation of the electrons of Y atoms is beneficial to its solution in the W–GB system. Further, the segregation of multiple Y atoms in the W–GB is clearly observed, where the Y atoms preferentially occupy the GB plane substitutional sites. The alloying Y atoms at the GB plane sites can effectively strengthen the GB when the concentration is less than 3.367%. The stronger binding energy of W–Y than the binding energy of W–W in the GB region is the main factor for the strengthening of the GB. [ABSTRACT FROM AUTHOR]

As a smart material with controllable rheological properties, magnetorheological fluids (MRFs) have been increasingly used in various fields. The temperature of MRFs inevitably changes during operation, which markedly affects the rheological properties; thus, the modeling of temperature effects is critical for the control and design of magnetorheological devices. However, most studies only examine the temperature effects of MRFs in a narrow temperature range, which fails to effectively cover the operating temperature range of MRFs, and the viscosity-temperature models used have notable limitations. This paper proposes to use free volume theory, in the form of the universal Doolittle equation, to study the viscosity-temperature behavior of MRFs and their base oils over a wide temperature range. Compared with the existing Reynolds and Arrhenius equations, the Doolittle equation achieves an accuracy improvement of up to 17 times and eight times, respectively. It predicts the overall viscosity-temperature behavior of liquids based on four data points taken over a narrow temperature range, with a relative root-mean-square error (RMSE) of no more than 5%. Ignoring the limited effect of off-state yield stress, the Doolittle equation with strong expandability can be used to establish temperature-dependent MRF constitutive equations. It can even develop multiphysics models based on the highly similar viscosity-temperature characteristics between MRFs and their base oils, which will greatly facilitate the development and optimization of MRFs. [ABSTRACT FROM AUTHOR]

We systematically investigated the influence of yttrium (Y) on the evolution behavior of helium (He) in tungsten (W) by first-principles calculations. It is found that the addition of Y reduces the solution energy of He atoms in W. Interestingly, the solution energy of He decreases with decreasing distance between Y and He. The binding energies between Y and He are inversely correlated with the effective charge of He atoms, which can be attributed to the closed shell structure of He. In addition, compared with pure W, the diffusion barrier (0.033 eV) of He with Y is lower, calculated by the climbing-image nudged elastic band (CI-NEB) simulations, reflecting that the existence of Y contributes to the diffusion of He in W. The obtained results provide a theoretical direction for understanding the diffusion of He. [ABSTRACT FROM AUTHOR]

Hyperuricemia (HUA) and its associated metabolic diseases seriously threaten human health, and commensal microbiota has been identified as one of the environmental triggers of HUA. The role of berberine (BBR) in the treatment of HUA has begun to receive attention in recent years. However, how BBR modulates the microbiota to slow HUA progression is unclear. In this study, we showed that BBR alleviated potassium oxonate (PO)-induced HUA in mice by suppressing the expression of xanthine oxidase (XOD) in the liver and urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) in the kidney. The BBR also improved renal inflammation by inhibiting the expression of TNF- α , IL-1 β , and caspase-1. Subsequently, we evaluated whether the observed anti-HUA effects of BBR were associated with changes in gut microbial structure in mice. 16S rRNA sequencing data showed that BBR significantly altered the community compositional structure of the gut microbiota. Specifically, BBR enriched the abundance of Coprococcus, Bacteroides, Akkermansia, and Prevotella. Antibiotic treatment can reverse the anti-HUA effects of BBR that further supports the role of the gut microbiota. In conclusion, our study provides evidence that BBR ameliorates PO-induced HUA by modulating the gut microbiota. [ABSTRACT FROM AUTHOR]

Tanshinone IIA (Tan-IIA) is a major component extracted from the traditional herbal medicine Danshen, which has shown antipulmonary fibrosis by suppress reactive oxygen species-mediated activation of myofibroblast. However, the exact mechanism of Tan-IIA against pulmonary fibrosis (PF) remains unclear. This work aimed to explore the underlying mechanism of the protective effects of Tan-IIA on PF. By using high-throughput RNA-Seq analysis, we have compared the genome-wide gene expression profiles and pathway enrichment of Tan-IIA-treated NIH-3T3 cells with or without transforming growth factor beta 1 (TGF- β 1) induction. In normal NIH-3T3 cells, Tan-IIA treatment up-regulated 181 differential expression genes (DEGs) and down-regulated 137 DEGs. In TGF- β 1-induced NIH-3T3 cells, Tan-IIA treatment up-regulated 709 DEGs and down-regulated 1075 DEGs, and these DEGs were enriched in extracellular matrix organization, collagen fibril organization, cell adhesion, ECM–receptor interaction, PI3K-Akt signaling pathway and P53 signaling pathway. Moreover, there were 207 co-expressed DEGs between Tan-IIA treatment vs. the Control and TGF- β 1 plus Tan-IIA treatment vs. TGF- β 1 alone treatment, some of which were related to anti-oxidative stress. In both normal and TGF- β 1-induced NIH-3T3 cells, protein–protein interaction network analysis indicated that Tan-IIA can regulate the expression of several common anti-oxidant genes including Heme oxygenase 1 (Ho-1, also known as Homx1), Sestrin2 (Sesn2), GCL modifier subunit (Gclm), GCL catalytic subunit (Gclc) and Sequestosome-1 (Sqstm1). Quantitative Real-time polymerase chain reaction analysis confirmed some DEGs specifically expressing on Tan-IIA treated cells, which provided new candidates for further functional studies of Tan-IIA. In both in vitro and in vivo PF models, the protein expression of Sesn2 was significantly enhanced by Tan-IIA treatment. Overexpression and knockdown experiments showed that Sesn2 is required for Tan-IIA against TGF- β 1-induced myofibroblast activation by reinforcing nuclear factor-erythroid 2-related factor 2 (Nrf2)-mediated anti-oxidant response via downregulation of kelch-like ECH-associated protein 1 (Keap1). These results suggest Tan-IIA inhibits myofibroblast activation by activating Sesn2-Nrf2 signaling pathway, and provide a new insight into the essential role of Sesn2 in PF. [ABSTRACT FROM AUTHOR]

A landslide is a kind of geological disaster, which seriously threatens the production and lives of people around it. In collapsible loess areas, landslides occur more frequently. There are many cracks at the edge of the loess platform. This paper studies the relationship between the characteristics of cracks at the edge of the platform and the stability of the loess platform slope through numerical simulation. It is found that some cracks will eventually form a through sliding surface and form a landslide, while some cracks are relatively safe for the time being. According to the calculation results, the statistical formula is obtained to reveal the relationship between them, which is helpful to predict the loess platform landslide according to the cracks at the edge of the tableland in the future. [ABSTRACT FROM AUTHOR]

Cost-effective Fe-based Al-Cr-Fe-Ni alloys were prepared by arc melting process, and Al/Ni ratio in Al x Ni (40- x) Fe 40 Cr 20 (0 ≤ x ≤ 40, at.%) alloys was adjusted for superior mechanical properties. With increasing x , the initial FCC phase diminishes and A2/B2 phase is promoted. Two typical A2/B2 structures are observed, one consists of spherical/cuboidal B2 nanoparticles distributed in A2 matrix (denoted as AMBP), and the other consists of ellipsoidal and plate-like A2 particles distributed in B2 matrix (denoted as BMAP). The fraction of AMBP domains decreases while that of BMAP increases with increasing x , which is harder with lowered plasticity/toughness, accompanied with some micro-cracks propagating along the plate-like A2/B2 interfaces in BMAP domains. The alloy shows the best strength-plasticity combination at x = 15 with >95 vol% AMBP domains. This study suggests a cost-effective Al 15 Ni 25 Fe 40 Cr 20 medium-entropy alloy with superior strength-plasticity combination. The Al 15 Ni 25 Fe 40 Cr 20 alloy per metric ton is 13% and 18% cheaper than well-known equiatomic AlCrFeNi alloy and AlCrFe 2 Ni 2 alloy, respectively. • Tuning Al/Ni ratio in Al x Ni (40- x) Fe 40 Cr 20 alloy for optimized microstructure and mechanical properties. • Increasing x leads to microstructural changes from FCC + A2/B2, through A2/B2 + FCC, to A2/B2 duplex structure. • Two type A2/B2 structures are observed; nano-B2 in A2 matrix (AMBP), and nano-A2 in B2 matrix (BMAP). • Fraction of AMBP decreases while that of BMAP increases with x, leading to higher H but lowered %EL. • A cost-effective Al 15 Ni 25 Fe 40 Cr 20 medium-entropy alloy with superior strength-plasticity combination is identified. [ABSTRACT FROM AUTHOR]

The small-scale linear magnetic hole (LMH) is a magnetic dip with a size less than or on the order of ρi (proton gyroradius), which may contribute to turbulence properties in the solar wind and other astrophysical plasmas. Based on one-month measurements of the Mars Atmosphere and Volatile EvolutioN mission, 174 small-scale LMH events in the Martian magnetosheath are used to investigate their statistical properties in this study. Our results show that small-scale linear LMHs are ubiquitous in the Martian magnetosheath, and their occurrence rate is estimated to be approximately 1.5 events per hour based on one-month observations. Compared with the ambient plasma, the averaged magnitude of the magnetic field in these holes can decrease from 6.8–3.5 nT. Nearly 66% of events have a Bmin/B value in the range of (0.45, 0.75). The duration of small-scale MHs is mainly less than 0.4 s. For 90% of the events, the size along the solar wind flow is less than ρi. As the rotation angle increases, the occurrence rate of small-scale LMHs decrease. However, the Bmin/B, size, and duration of small-scale LMHs have no obvious dependence on their rotation angle. [ABSTRACT FROM AUTHOR]

We investigate the reflection of low-harmonic fast magnetosonic (MS) waves at the local two-ion cutoff frequency (fcutHe+). By comparing the wave signals of the two Van Allen Probes satellites, a distinct boundary where wave energies cannot penetrate inward are found in the time–frequency domain. The boundary is identified as the time series of local fcutHe+. For a certain frequency, there exists a spatial interface formed by fcutHe+ , where the incident waves should be reflected. The waves with small incident angles are more likely to penetrate the thin layer where the group velocity reduces significantly and then slow down in a period of several to tens of seconds before the reflection process complete. The cutoff reflection scenario can explain the intense outward waves observed by probe A. These results of MS reflection at fcutHe+ may help to predict the global distribution of MS waves and promote the understanding of wave–particle dynamics in the radiation belt. [ABSTRACT FROM AUTHOR]

AlCrFeCoNi is one of widely studied high-entropy alloys, in which Co is considered to be beneficial. Here we demonstrate in detail that Co does not play a positive role. Instead, Co-free AlCrFeNi possesses higher ductility than AlCrFeCoNi while maintaining a similar mechanical strength. It is of interest to observe that removing Co results in a two-fold increase in the wear resistance. The improvements are related to the formation of a soft-hard alternating lamellar structure which is absent in the Co-containing alloy. We further tailor the alloy by replacing Co with Ti, leading to further enhanced wear resistance. AlCrFeCo x Ni (x = 0.5 and 1) and Co-free AlCrFeNiTi x (x = 0, 0.2, 0.5, 0.7 and 1) all contain a Fe-Cr-rich disordered BCC phase (A2) and a NiAl (Ti)-rich ordered BCC phase (B2). For x = 0.5, a small amount of L2 1 phase with embedded nanoscale A2 phase is observed. For x ≥ 0.7, an additional CrFeTi Laves phase forms mainly at grain boundaries. The increase in Ti content alters the lamellar eutectic microstructure of AlCrFeNi, forming a cellular eutectic microstructure. Ti considerably increases hardness and compressive strength at the expense of ductility. AlCrFeNiTi 0.7 appears to have a proper balance between hardness and ductility with a superior wear resistance comparable to that of a well-known industrial wear-resistant high-Cr cast iron (Cr30C2.85). This HEA has demonstrated itself a promising candidate for the mechanical and anti-wear applications. [Display omitted] • Co does not play a beneficial role in affecting mechanical properties of classic AlCrFeCoNi high-entropy alloy. • Removal of Co results in a two-fold increased wear resistance with higher ductility and ultimate strength. • Replacing Co by Ti further enhances the wear resistance due to raised hardness and a protective oxide film. • AlCrFeNiTi0.7 shows a higher wear resistance than a widely-used industrial wear-resistant cast iron, Cr30C2.85. • Excessive Ti (x > 0.7) increases brittleness, deteriorating the wear resistance especially under larger loads. [ABSTRACT FROM AUTHOR]

The mechanism of removal of humic acid, phosphate and kaolin particles by coagulation with alum and PACl or adsorption by their pre-formed precipitates was investigated, and it was found that the coagulation mechanisms for monomeric Al at neutral pH and polymeric Al 13 at alkaline pH were very similar. The removal of phosphate and humic acid by coagulation with alum or PACl did not change with stirring time (between 1 min and 15 min), independent of the dose and species of coagulants. However, for adsorption of these impurities by pre-formed precipitates, the results were significantly different. Both Al3+ and nano-sized Al 13 could precipitate and form aggregates at pH 7 and pH 9, respectively, and their precipitates became less active (fewer binding sites on the surface of precipitate) with the increase of shear time or shear rates before adsorbing pollutants. Thus, although the total surface area increased (the average size of flocs became smaller) at higher applied shear rates or longer shear time, the removal efficiency of humic acid and phosphate decreased. Also, from the MW distributions, it was confirmed that less humic acid was removed by the adsorption on alum precipitate pre-formed with longer shear time. Chemical groups (OH 2 and OH) on the surface of precipitate determined the removal efficiency of phosphate and humic acid, and the activity of precipitate become lower as a result of higher applied shear and longer shear time. This is confirmed be due to some crystallization of the amorphous precipitate, forming inactivated hydroxyl. When kaolin was added 10 min after the alum or PACl precipitate formed, the precipitates captured kaolin particles only on their surface, whereas when alum was added to kaolin suspensions particles were trapped within the growing flocs. When alum/kaolin flocs were broken at high shear rate re-growth of flocs decreased with increasing shear time, but after a short breakage period, long aging of broken flocs had little effect on floc regrowth. Graphical abstract Image 1 Highlights • Al3+ and Al 13 could precipitate and form aggregates at pH 7 and pH 9, respectively. • Their precipitates became less active with the increase of shear time or shear rates. • Crystallization of amorphous precipitates occurred during great applied shear. • Less humic acid was removed by alum precipitate pre-formed with longer shear time. [ABSTRACT FROM AUTHOR]

The Co-free AlCrFeNi HEA has good application prospects for its simple duplex BCC phase structure and attractive mechanical properties. In this work, influences of Ti on corrosion and corrosive wear of AlCrFeNi alloy in salty and acidic solutions were investigated and compared with those of AlCrFeCoNi. Results showed that removing Co led to little influence on hardness but only a slight decrease in corrosion resistance. However, the corrosive wear resistance was significantly improved, which was attributed to improved ductility, which benefited the toughness, of the Co-free AlCrFeNi alloy. AlCrFeNiTi 0.5 showed the lowest passivation current and its corrosion current density was only about one-third that of SS316. A strong correlation was found among the corrosive wear resistance, corrosion resistance, hardness and brittleness. Titanium can improve the anti-corrosive wear ability of AlCrFeNi alloy with increased hardness, higher corrosion resistance, and enhanced protectiveness of formed surface oxide film. However, as the Ti content exceeded a certain level, corrosive wear of Ti-containing alloys was accelerated by easy formation of crack and delamination in substrate which led to a negative effect on the corrosive wear resistance, although the alloys showed higher hardness. • Removing Co significantly improves corrosive wear resistance attributing to enhanced ductility of AlCrFeNi alloy. • Ti promotes the formation of continuous protective film on AlCrFeNiTi x. • AlCrFeNiTi 0.5 shows the highest corrosion resistance. • Corrosive wear of AlCrFeNiTi x is reduced with increasing Ti until x = 1 due to increased hardness and the more protective passive film. • Corrosive wear of less tough AlCrFeNiTi 1.5 increases due to local fracture in addition to wear-corrosion synergy. [ABSTRACT FROM AUTHOR]

An equiaxed-structure TC21 titanium alloy, consisting of predominant equiaxed α grains and remained β phase, was hot rolled at 750 °C, and subsequently annealed at different temperatures. Based on electron back-scattered diffraction (EBSD) observation, the microstructure evolution and static recrystallization (SRX) during rolling and annealing were investigated. An apparent evolution of grain morphology occurred during rolling and annealing. The equiaxed α grain was elongated along the transverse direction (TD) during hot rolling, and then got an equiaxed morphology due to the SRX and boundary splitting during annealing. In contrast, subsequent annealing had a limited effect on the textures. The Kernel Average Misorientation (KAM) calculation showed that the β phase endured a larger deformation amount than α phase, which induced a more preferential SRX in β phase. Meanwhile, the different SRX mechanism between α and β phases caused a different evolution of SRX and grain morphology with increasing annealing temperature. The continuous SRX (cSRX) in α phase made the SRX fraction increase and grain size decrease with increasing annealing temperature, with an exception of a grain growth at 940 °C. However, SRX occurred in β phase by subgrain coalescence, which induced the increase of grain size and decrease of SRX fraction with increasing annealing temperature. Conclusively, 880 °C was an appropriate annealing temperature to get a uniform and refined microstructure for the hot-rolled TC21 titanium alloy. [ABSTRACT FROM AUTHOR]

The coexistence of equiaxed α, lamellar α and β phase in a duplex-structure α/β titanium alloy not only benefits the balance between strength and ductility, but also arouses a complicated microstructure evolution during hot deformation. The research objective herein is first to investigate the dynamic restoration mechanism, including dynamic recovery (DRC) and dynamic recrystallization (DRX), of both α and β phases during hot deformation of a duplex-structure TC21 titanium alloy. The results show that, after deformation, the geometric morphologies of lamellar α and β phase change more apparently than equiaxed α. Based on the analysis on the distribution and frequency of misorientation angle, it reveals that DRC and continuous DRX (CDRX) occur in all of equiaxed α, lamellar α and β phase, and the increasing deformation temperature restrains the occurrence of CDRX. Synthetically, the correlation between geometric morphology and dynamic restoration is well established. Meanwhile, the heterogeneous degree of DRX indicates a morphology dependent deformation heterogeneity between equiaxed and lamellar α, and between different local regions in β phase which is closely related to the distribution of equiaxed and lamellar α. The further discussion reveals that the morphology dependent deformation heterogeneity is fundamentally attributed to the different orientation relationship (OR) between β phase and equiaxed/lamellar α. This new find enriches the understanding on the deformation heterogeneity of titanium alloy, which was mainly attributed to the difference in crystallographic orientations in past decades. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron (nZVI) has been widely used in the reductive removal of contaminants from water, yet it still fights against the inherent passive cover and the raise of medium pH. In this study, nZVI was supported onto a nitrogen-doped biochar (NBC) that was prepared by pyrolyzing shrimp shell for efficiently sequestrating aqueous selenite (Se(IV)). The resultant composite (NBC-nZVI) revealed a higher reactivity and electron utilization efficiency (EUE) than the bare nZVI in Se(IV) sequestration because of the positive charge, the buffering effect and the good conductivity of NBC. The kinetic rate and EUE of NBC-nZVI were increased by 143.4% and 15.3% compared to the bare nZVI, respectively, at initial pH of 3.0. The high removal capacity of 605.4 mg g−1 for NBC-nZVI was obtained at Se(IV) concentration of 1000 mg L−1, initial pH of 3.0, NBC-nZVI dosage of 1.0 g L−1 and contact time of 12 h. Moreover, NBC-nZVI exhibited a strong tolerance to solution pHs and coexisting compounds (e.g., humic acid) and could reduce the Se(IV) concentration from 5.0 mg L−1 to below the limit of drinking water (50 μg L−1) in real-world samples. This work exemplified a utilization of shrimp shell-derived NBC to simultaneously enhance the reactivity and EUE of nZVI for reductively removing contaminants. [Display omitted] • N-doped porous biochar (NBC) derived from shrimp shell was used to support nZVI. • NBC simultaneously increased the reactivity and EUE of nZVI toward Se(IV) capture. • NBC improved the tolerance of nZVI to solution pH and coexisting compounds. • This work exemplified a high-valued utilization of seafood waste. [ABSTRACT FROM AUTHOR]

Electron acceleration in the near-Earth magnetotail during the substorm period is still an unresolved question. In this paper, by tracing electron trajectories in the dynamically evolving electromagnetic fields obtained from a two-dimensional (2D) global hybrid simulation, we investigate electron acceleration in the near-Earth magnetotail during dipolarization. In our simulation, electrons with energies above several keV can gain energy in the plasma sheet due to the adiabatic acceleration mechanism when these electrons propagate earthward. In the near-Earth magnetotail (about 9-15 $R_{E}$ from the Earth), these electrons can be accelerated by betatron acceleration which is due to the compression of magnetic field associated with dipolarization of magnetotail. Additionally, in the middle and high latitudes of the near-Earth magnetotail, the parallel electric field carrying by kinetic Alfvén waves can also accelerate electrons when these electrons bounce between the mirror points. The combination effects of these three acceleration mechanisms can accelerate electrons from several keV to about one hundred keV. Our results indicate that both the large-scale structure and wave-particle interactions need to be taken into account for electron acceleration in the near-Earth magnetotail. [ABSTRACT FROM AUTHOR]

Insulin or insulin like signaling (IIS) pathway is a crucial pathway in Caenorhabditis elegans associated with mediating longevity, and stress resistance. Regulators of G protein signaling (RGS) also modulate stress resistance and longevity in multiple in vitro and in vivo models. However, the mechanism underlying RGS mediating stress resistance and longevity remains largely unclear. Here we report that rgs-1 , an important member of rgs family, is a novel modulator of IIS pathway in C. elegans . We found that the loss of rgs-1 dramatically promoted paraquat resistance in C. elegans . Further genetic analyses demonstrated that rgs-1 acted downstream of daf-2 and upstream of age-1, pdk-1, daf-16 . Instead of affecting those IIS-associated genes in transcriptional process, loss of rgs-1 promoted DAF-16′s nucleus translocation and subset genes’ expression in paraquat-induced oxidative status. By this way, rgs-1 mutant worms exhibited lower ROS damage and longer survival time than wild type worms when both exposed to paraquat. Other than paraquat exposure, rgs-1 mutant also promoted lifespan and cadmium resistance relying on daf-16 . As rgs is evolutionarily conserved, our findings open a new insight into rgs family and its role in paraquat-induced oxidative stress and longevity in C. elegans or even mammals. [ABSTRACT FROM AUTHOR]

We systematically studied the solution and aggregation behavior of Potassium (K) in the symmetrical tilt Tungsten (W) grain boundary (GB) Ʃ5(310)/[001] through first-principles simulations. The lowest-energy substitutional sites are the nearest neighbor sites of GB (V 1) in the W-GB, instead of the GB sites themselves, which can be understood by the charge redistribution between the K and W atoms. Interestingly, our simulations show that segregation of multiple K atoms in W GB will form a cluster structure around the GB, which is well consistent with previous experimental reports. Electronic analysis reveals that previously trapped K atoms adjust the electronic densities around them to be more suitable for trapping more K atoms. Due to the greater binding energy of K-K over W-W at the GB, incorporation of K atoms leads to a slight increase in the fracture energy of the GB structure. [ABSTRACT FROM AUTHOR]

Electron beam welding (EBW) is a fusion joining process particularly suitable for the welding of thick titanium plates. In the present work, commercial high-purity titanium plates with a thickness of 30 mm were welded by EBW. Color metallography and electron backscattered diffraction (EBSD) were used to investigate the microstructure and texture after welding. The results show that the grains become elongated or coarsened in the weld zone (including the fusion zone and the heat-affected zone). Meanwhile, as revealed by the (0001) pole figures, the texture of the weld zone is enhanced. Despite the grain coarsening, the welded plates exhibit higher yield strength than the base metal. A Schmid factor analysis revealed that this increase in yield strength could be attributed to texture strengthening. Specifically, the grains in the weld zone are re-oriented. For the weld zone, the Schmid factor is relatively small for prismatic slip, which is the most easily activated deformation mode for titanium at room temperature. Compared to the base metal, the Schmid factors for { 10 1 ¯ 2 } twinning and { 11 2 ¯ 2 } twinning are larger for the weld zone. The EBSD observations confirmed that a large number of { 10 1 ¯ 2 } twins and { 11 2 ¯ 2 } twins are formed in the weld zone during tension. However, the plastic strain caused by the twin formation is much smaller than that caused by the prismatic slip in the base metal. As a result, necking occurred in the base metal during the transverse tensile tests. [ABSTRACT FROM AUTHOR]

As the service environment has become increasingly harsh, high-temperature protective coatings were widely researched and applied in industrial fields. K444 is a typical Cr-rich Ni-based superalloy used in power system. Its protection at high temperatures relies on the formation of chromia which is not alone but accompanied by the growth of other oxides or compounds thereby decreasing the oxidation resistance of chromia. In this paper, an enamel–alumina composite coating was prepared on the K444 alloy. Its oxidation behavior at 900 °C was investigated and the oxidation mechanisms were carefully elucidated. Results indicate that oxidation resistance of the K444 superalloy has been increased for more than six times by the enamel–alumina composite coatings. As the traditional theory suggested, the enamel composite coatings retard oxygen diffusion to the superalloy surface, leading to the decrease of oxidation rate. However, it is found that the protection mechanism is more associated with the change of oxidation mode of the alloy substrate, i.e. preventing Cr oxidation while promoting Al and Ti oxidation by the enamel coatings. Furthermore, this protection depends strongly on the alumina content of the enamel composite coating. With higher alumina content, the enamel composite coating retards oxygen diffusion more effectively, and the oxidation mode with respect to the selective oxidation of Al keeps unchanged for longer times. [ABSTRACT FROM AUTHOR]

The impact mechanism of sand blasting on oxidation resistance of K38G superalloys was investigated. Results show that sand blasting influenced little on the oxidation kinetics but suppressed the DIR (diffusion induced recrystallization) process, i.e. keep the original crystal orientation of substrate. Besides, sand blasting refined the crystal size and changed the growing mode of oxide scales by changing the diffusion mechanism, being reflected in the variation in surface morphologies of scales from a feature of piles plus valleys for the polished ones to a feature of flat surface appearance with micrograins for the sand blasted alloys. [ABSTRACT FROM AUTHOR]

An electron phase-space hole (electron hole) is considered to be unstable to the transverse instability. In this paper, two-dimensional (2D) electrostatic particle-in-cell (PIC) simulations are used to explore the dissipation process of a one-dimensional (1D) electron hole in a weakly magnetized plasma and its consequence on electron heating, which consists of two stages. In the first stage, the electron hole is still kept as a quasi-1D structure, however, with the excitation of the transverse instability and the generation of the perpendicular electric field, the electrons are scattered and then heated along the perpendicular direction in the electron hole. In the second stage, the quasi-1D electron hole is broken into several 2D electron holes. The temperature of the electrons outside of these 2D electron holes also increase, and at last the velocity distribution of the electrons become almost isotropic in the whole simulation domain. Our results provide a new dissipation mechanism of an electron hole. [ABSTRACT FROM AUTHOR]

Wear behaviors of 5-element AlCrFeCoNi and 6-element AlCrFeCoNiTi 0.5 high entropy alloys (HEAs) against the Si 3 N 4 ball respectively in 3.5 wt% NaCl and HCl (pH = 3) solutions were investigated. The role of the Ti addition in affecting microstructure, hardness, wear and corrosion of the HEA was analyzed. Results showed that the AlCrFeCoNiTi 0.5 exhibited higher hardness, ascribed to the solid solution strengthening and precipitation strengthening. The wear loss of AlCrFeCoNiTi 0.5 is markedly lower than that of AlCrFeCoNi under the dry condition against Si 3 N 4 balls of 4 mm and 6 mm in diameter, respectively. The Ti addition also improved the corrosion resistance, especially the pitting corrosion resistance, of the HEA, evidenced by lowered I corr and I pit and elevated R p and R ct. This was attributed to the contribution of Ti in the formation of a more protective passive film, which impeded the point defect transport and passive film breakdown. The surface potential measured by means of atomic force microscopy (AFM) shows a smaller difference between adjacent domains in AlCrFeCoNiTi 0.5 , which should only result in weak local galvanic coupling. Thus, the Ti addition helps suppress the pitting attack to the HEA. The solutions and size of counterpart ball have large influences on the performance of AlCrFeCoNiTi 0.5 during corrosive wear. Efforts are made to clarify the mechanism for the beneficial role of Ti addition in affecting the performance of the HEA during the destructive processes. • Ti addition rendered the microstructure of AlCrFeCoNi high-entropy alloy more heterogeneous with higher hardness. • Ti addition improved the corrosion resistance of the AlCrFeCoNi alloy, especially its pitting corrosion resistance. • Ti reduced corrosive wear of AlCrFeCoNi, which was more obvious as larger Si3N4 balls were used for the test. • The benefits of Ti addition to the HEA against corrosive wear can be maximized when utilized appropriately. [ABSTRACT FROM AUTHOR]

• Three interface reaction stages between TiAl alloy and multilayer graphene from 1100 to 1350 °C. • Ti 2 AlC directly formed by TiAl, Ti 3 Al and multilayer graphene without the TiC mesophase. • Ti 2 AlC and Ti 3 AlC with nano-lamellar structures transformed from multilayer graphene and TiAl alloy. • Difference in interface reaction mechanisms between multilayer graphene/TiAl and graphite/TiAl. TiAl alloy added with multilayer graphene (MLG) was prepared by spark plasma sintering (SPS) from 1100 to 1350 °C. The interface reaction products and corresponding reaction mechanisms were analyzed via transmission electron microscope (TEM). It is found that MLG hardly reacts with TiAl below 1150 °C. However, at the temperatures ranging from 1150 to 1250 °C, the interface reaction occurs and the product is mainly characterized as Ti 2 AlC phase. It is demonstrated that Ti 2 AlC is directly synthesized by TiAl, Ti 3 Al, and MLG, rather than the traditional reaction path with the formation of TiC mesophase. With the increase of reaction temperature, Ti 3 AlC emerges above 1250 °C and eventually replaces Ti 2 AlC as the primary interface product above 1300 °C. It is revealed that Ti 2 AlC and Ti 3 AlC phases formed at the interface are characterized as nano-lamellar structures, which are basically coincident with the original MLG morphology. [ABSTRACT FROM AUTHOR]

A modified, robust adaptive fault compensation design is proposed for rigid spacecraft systems with uncertain actuator failures and unknown disturbances. The feedback linearization method is first introduced to linearize the nonlinear dynamics, and a model-reference adaptive controller is designed to suppress the unknown external disturbances and stabilize the linearized system. Then, a composite adaptive controller is developed by integrating multiple controllers designed for the corresponding actuator failure conditions, which can handle the essentially multiple uncertainties (failure time, values, type, and failure pattern) of actuator failures simultaneously. To further improve the transient performance problem in the failure compensation control, an H∞ compensator is introduced as an additional item in the basic controller to attenuate the adverse effects on tracking performance caused by parameter estimation errors. From the theoretical analysis and simulation results, it is obvious that the designed scheme can not only guarantee the stability of the closed-loop system is stable and asymptotical tracking properties for a given reference signal but also greatly improve the transient performance of the spacecraft system during the process of failure compensation. [ABSTRACT FROM AUTHOR]

Abstract: Morphology plays an important role in the properties of nanomaterials. We successfully synthesized three new SnO2 morphologies, nanocorals, nanofragments and nanograss, via a simple hydrothermal method with surfactant additives. The final products were characterized by field-emission scanning electron microscopy and X-ray diffraction. We found that the surfactants played a critical role in the synthesis of different SnO2 nanostructures. In particular, when poly(ethylene glycol) was added as a surfactant, a unique grass-like structure was obtained. The mechanism of formation for this novel structure is discussed. The gas-sensing performance of all the products was investigated. The results show that the nanograss morphology had a superior gas response to formaldehyde than the other morphologies. [Copyright &y& Elsevier]

It is well known that the parallel cuts of the parallel and perpendicular electric field in electron phase-space holes (electron holes) have bipolar and unipolar structures, respectively. Recently, electron holes in the Earth's plasma sheet have been observed by THEMIS satellites to have detectable fluctuating magnetic field with regular structures. Du et al. () investigated the evolution of a one-dimensional (1D) electron hole with two-dimensional (2D) electromagnetic particle-in-cell (PIC) simulations in weakly magnetized plasma (Ω< ω, where Ω and ω are the electron gyrofrequency and electron plasma frequency, respectively), which initially exists in the simulation domain. The electron hole is unstable to the transverse instability and broken into several 2D electron holes. They successfully explained the observations by THEMIS satellites based on the generated magnetic structures associated with these 2D electron holes. In this paper, 2D electromagnetic particle-in-cell (PIC) simulations are performed in the x- y plane to investigate the nonlinear evolution of the electron two-stream instability in weakly magnetized plasma, where the background magnetic field $(\mathbf{B}_{0} =B_{0}\vec{\mathbf{e}} _{x})$ is along the x direction. Several 2D electron holes are formed during the nonlinear evolution, where the parallel cuts of E and E have bipolar and unipolar structures, respectively. Consistent with the results of Du et al. (), we found that the current along the z direction is generated by the electric field drift motion of the trapped electrons in the electron holes due to the existence of E, which produces the fluctuating magnetic field δB and δB in the electron holes. The parallel cuts of δB and δB in the electron holes have unipolar and bipolar structures, respectively. [ABSTRACT FROM AUTHOR]

Electron phase space holes (electron holes) are found to be unstable to the transverse instability. Two-dimensional (2D) electromagnetic particle-in-cell simulations are performed to investigate the structures of the fluctuating magnetic field associated with electron holes. The combined actions between the transverse instability and the stabilization by the background magnetic field (B0=B0evector x) lead a one-dimensional electron hole into several 2D electron holes which are isolated in both the x and y directions. The electrons trapped in these 2D electron holes suffer the electric field drift vE=E×B0/B02 due to the existence of the perpendicular electric field Ey, which generates the current along the z direction. Then, the unipolar and bipolar structures are formed for the parallel cut of the fluctuating magnetic field along the x and y directions, respectively. At the same time, these 2D electron holes move along the x direction, and the unipolar structures are formed for the parallel cut of the fluctuating magnetic field along the z direction. [ABSTRACT FROM AUTHOR]

Tungsten (W) is considered as the potential plasma facing material of the divertor and the first wall material in fusion. To further improve the ductility of W, the structural and mechanical properties of W–M (M = rare earth element Y, La, Ce and Lu) alloys are systematically investigated by first-principles calculations. Our results reveal that all the W1−xMx (x = 0.0625, 0.125, 0.1875, 0.25) alloys can form binary solid solution at the atomic level, and the alloys keep bcc lattice structures until the concentration of M increases to a certain value. Although the moduli of the alloys are reduced compared to that of pure W metal, the characteristic B/G ratio and Poisson's ratio significantly increase, implying all the four rare earth elements can efficiently improve the ductility of W metal. Considering both factors of mechanical strength and ductility, La and Ce are better alloying elements than Y and Lu. [ABSTRACT FROM AUTHOR]

The purpose of this work is to develop a low-cost and high-performance catalyst for the selective catalytic hydrogenation of acetylene to ethylene. Non-precious metals Cu and Ni were selected as active ingredients for this study. Using ZSM-12 as a carrier, Cu-Ni bimetallic catalysts of CuNix/ZSM-12 (x = 5, 7, 9, 11) with different Ni/Cu ratios were prepared by incipient wetness impregnation method. The total Cu and Ni loading were 2 wt%. Under the optimal reaction conditions, the acetylene conversion was 100%, and the ethylene selectivity was 82.48%. The CuNi7/ZSM-12 prepared in this work exhibits good performance in the semi-hydrogenation of acetylene to ethylene with low cost and has potential for industrial application. [ABSTRACT FROM AUTHOR]

Abstract: Self-assembly of one-dimensional nanoscale building blocks into functional 2D or 3D complex superstructures has stimulated a great deal of interest. In current work, using the hydrothermal method and reagent of hexamethylenetetramine (HMT), we synthesize the SnO2 3D hierarchical nanostructures with an average diameter of 200–400nm, which exhibit flower-like architectures assembled by numerous one-dimensional tetragonal prism nanorods. Further comparative studies demonstrate that the HMT provides nucleation sites for the assembling of the nanorods, which plays a crucial role in producing such unique flower-like architectures. Meantime, a novel growth mechanism is proposed in detail. In property, the prepared SnO2 nanoflowers show excellent gas-sensing performances to ethanol of 50ppm at an optimal temperature as low as 250°C. Such unique architectures may open up an avenue to further enhance the gas-sensing performances of SnO2 nanostructures for future sensor application. [Copyright &y& Elsevier]

Originally defined high-entropy alloys (HEAs) are generally in a solid-solution state, which are solution-strengthened by multiple-elements with desired toughness. However, the mixture of multiple elements likely result in certain microstructure features, which could also benefit the HEAs. In this study, AlCrFeCoNi and AlCrFeCoNiTi 0.5 high entropy alloys (HEAs) were fabricated, and their microstructures and sliding wear behaviors (in comparison with stainless steel) were investigated using XRD, SEM, EDS and a pin-on-disc tribometer, respectively. It is shown that the two HEAs consist of ordered Al–Ni/Al–Ni–Ti rich BCC and disordered Fe–Cr rich BCC domains. The AlCrFeCoNi alloy has an intertwined structure with plate-like Fe–Cr rich domains embedded in the Al–Ni rich matrix. The AlCrFeCoNiTi 0.5 alloy shows a similar microstructure but has honeycomb-like Fe–Cr rich interdendrites. The Ti addition markedly increases the hardness of the alloy, leading to considerably enhanced resistance to sliding wear. Through wear tests with and without air-flow to minimize frictional heating along with worn surface analysis, we demonstrate that the Ti addition also enhances the oxide scale, making additional contribution to the wear resistance. • High-entropy alloy, AlCrFeCoNi, has an intertwined microstructure with Al–Ni-rich and Fe–Cr-rich BCC domains. • Adding Ti to AlCrFeCoNi induces honeycomb-like Fe–Cr-rich interdendrites. • The Ti addition markedly increases hardness of AlCrFeCoNi, considerably enhancing its wear resistance. • The Ti addition improves the oxide scale, reducing wear when frictional heating is large enough to induce oxidation. • 316 SS showed less wear than AlCrFeCoNi when oxidation was involved, benefiting from its stronger oxide scale. [ABSTRACT FROM AUTHOR]

• NK cells are activated rather than suppressed in PQ-induced lung injury. • The NK cells are reduced in acute PQ poisoning model. • Depletion of NK cells in vivo attenuates PQ-induced lung injury. • Depletion of NK cells reverses the PQ induced-macrophages polarization. Acute lung injury is the main causative factor in paraquat dichloride (PQ)-induced mortality. The innate immune system-triggered detrimental inflammatory cascade plays a vital role in PQ-induced acute lung injury. However, the role of natural killer (NK) cells, which are essential for innate response, in PQ-induced acute lung injury remains largely unknown. Here, we found that in an acute PQ poisoning model, depletion of NK cells attenuated PQ-induced lung injury by inhibiting macrophage polarization towards the M1 type. Specifically, the percentages of NK cells were reduced in the lung, spleen, and peripheral blood in a murine model of acute PQ poisoning. NK cells were aberrantly activated, evidenced by upregulation of the activating markers CD69, CD107a, and NKG2D and downregulation of the inhibitive marker KLRG1. Further, NK-specific depletion in mice greatly prolonged the survival time and ameliorated reactive oxygen species-induced damage following PQ treatment compared with the control group. Importantly, NK cell depletion alleviated macrophage and neutrophil infiltration in the lung and reversed PQ induced-macrophage polarization towards the pro-inflammatory M1 type. Our study demonstrates a crucial role of NK cells and NK cell-to-macrophage interaction in PQ-induced acute lung injury. [ABSTRACT FROM AUTHOR]

• The generation of 252cf with different irradiation conditions are calculated. • Transport-burnup coupling system with STEP1.0 and MCMG-II is used for calculation. • Using optimized epithermal spectrum in CEFR can be considered as a feasible way. • The 252cf production will be more practical and efficient with CFR. The generation and transmutation process of the transplutoniums in the conversion chains for 252cf production is calculated and analyzed. The production and conversion efficiency of the chains with different target nuclides and neutron spectrums including fast, thermal and moderated neutron spectrums is computed. The conversion paths for 252cf under different neutron spectrums and neutron flux levels are analyzed. The multi-group depletion program STEP1.0 based on linear chain method is used to calculate the nuclide densities. The model of the reactor is simulated by the transport-burnup coupling system based on the STEP1.0 and MCMG-II for the detailed description of the target designs in the fast reactor. The differences of the conversion efficiency caused by the neutron spectrums can be qualified more accurately with the multi-group cross section calculations. The higher conversion efficiency than the typical thermal neutron spectrum can be obtained by some moderated spectrum optimized for absorption reaction in fast reactor (CEFR China Experimental Fast Reactor) through the irradiation of some transplutoniums (242Pu, 241Am, 244Cm). The neutron flux of large scale demonstration fast reactor or prototype fast breeder reactor is usually higher than the experimental fast reactor (CEFR) or reactor device. China is also developing the demonstration fast reactor (CFR China Fast Reactor) which will have a maximum neutron flux higher than 5.0E15 n/(cm2·s). Therefore, the 252cf production will be more practical and efficient with CFR. [ABSTRACT FROM AUTHOR]

The lightweight Al 3 Ti intermetallic compound shows superior properties at elevated temperatures but its room-temperature brittleness largely limits its usefulness. We propose Al 3 Ti-based lightweight medium-entropy alloys (MEAs) with selected alloying elements, which change Al 3 Ti from a tetragonal D0 22 structure to a ductile cubic L1 2 one with embedded hard B2 and D8a phases. A combination of improved ductility and strength can be achieved. Four lightweight AlTiCrMnFeCu MEAs (ρ = 3.65∼4.27 g/cm3) with tunable balance between hardness and ductility were fabricated. Ti and Fe promoted the formation of hard B2 phase, while Cr and Mn favored the formation of D8a phase which strengthened the alloy at the minor expense of ductility. The compressive yield and peak strengths of the MEAs e.g., Al 55 Ti 20 Cr 5 Mn 10 Fe 5 Cu 5 , can reach as high as 650 MPa and 1366 MPa, respectively, with its fracture strain around 17 %. This study provides useful information for designing Al 3 Ti-based lightweight MEAs with desirable properties. [Display omitted] [ABSTRACT FROM AUTHOR]

With the advantage of fast plasma measurements of the Magnetospheric Multiscale (MMS) mission in the magnetotail, we investigate the particle carriers of field-aligned currents (FACs) in the plasma sheet boundary layer for three cases. In all cases, electrons are the main carriers of FACs while the contribution of ions can be neglected. Our results indicate that thermal electrons (energy range from 0.5 Te to 5 Te, where Te is the electron parallel temperature) are the main carrier of the FAC. However, cold electrons (energy less than 0.5 Te) can also significantly contribute to the FACs. In 1 of 3 cases, suprathermal electron (energy greater than 5 Te) only contributes a small portion to the total current. The difference between all cases may depend on the local dynamics in the magnetotail. [ABSTRACT FROM AUTHOR]

With the MMS observations in the magnetotail, we report an earthward, dense, high speed, bulk flow event. In this event, two dense high speed flows (DHSF) are observed. Compared with the plasma sheet, the DHSF contains much denser and colder plasma. Ion density of DHSFs is about 8 times higher to plasma sheet density, while temperature of DHSFs is several times lower to plasma sheet plasma. Due to the high density, DHSFs can transport mass more effective than BBFs. Such DHSF can be generated by magnetic reconnection, but the generation mechanism is still unclear. [ABSTRACT FROM AUTHOR]

Antiangiogenic therapy with sorafenib (SF) alone is ineffective in eradicating tumors, and its long-term application can exacerbate tumor hypoxia, which in turn restricts SF's therapeutic efficacy. Here, a redox-responsive fluorinated peptide (DEN-TAT-PFC) consisting of dendritic poly-lysine, cell-penetrating peptide TAT, and perfluorocarbon was designed and synthesized to co-load siRNA-targeting hypoxia-inducible factors (siHIF-1α) and SF. The unique architecture of the peptide and fluorinated modifications enhanced the siRNA delivery efficiency, including increased siRNA binding, GSH-responsive release, cellular uptake, endosomal escape, and serum resistance. Simultaneously, the DEN-TAT-PFC/SF/siHIF-1α co-delivery system achieved efficient knockdown of HIF-1α at mRNA and protein levels, thus alleviating hypoxia and further substantially reducing VEGF expression. Additionally, the excellent oxygen-carrying ability of DEN-TAT-PFC may facilitate relief of the hypoxic microenvironment. As a result of these synergistic effects, DEN-TAT-PFC/SF/siHIF-1α exhibited considerable anti-tumor cell proliferation and anti-angiogenesis effects. Therefore, DEN-TAT-PFC can be a versatile platform for fabricating fluorine-containing drugs/siRNA complex nano-systems. [ABSTRACT FROM AUTHOR]

In this paper, with the in-situ observations from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes we report a wavy dipolarization front (DF) event, where the DF has different magnetic structures and electron distributions at different y positions in the Geocentric Solar Magnetospheric (GSM) coordinates. At y∼2.1RE (RE is the radius of Earth), the DF has a relatively simple structure, which is similar to that of a conventional DF. At y∼3.0RE, the DF is revealed to have a multiple DF structure, where the plasma exhibits a vortex flow. Such a wavy DF could be the results of the interchange instability. The different structure of such a wavy DF at different sites has a great effect on electron acceleration. Fermi acceleration can occur at the site of the DF with a simple or multiple DF structure, while betatron acceleration as a local process has the contribution to energetic electrons only at the site of the DF with a simple structure. [ABSTRACT FROM AUTHOR]

Mirror-mode structures widely exist in various space plasma environments. Here, we investigate a train of mirror-mode structures in the terrestrial plasma sheet on 11 August 2017 based on the Magnetospheric Multiscale mission. We find that bipolar current densities exist in the cross section of two hole-like mirror-mode structures, referred to as magnetic dips. The bipolar current density in the magnetic dip with a size of ∼2.2 ρi (the ion gyro radius) is mainly contributed by variations of the electron velocity, which is mainly formed by the magnetic gradient–curvature drift. For another magnetic dip with a size of ∼6.6 ρi , the bipolar current density is mainly caused by an ion bipolar velocity, which can be explained by the collective behaviors of the ion drift motions. The current density inside the mirror dip contributes to the maintenance of the hole-like structure's stable. Our observations suggest that the electrons and ions play different roles in the formation of currents in magnetic dips with different sizes. [ABSTRACT FROM AUTHOR]

The wear resistance of high-entropy alloy (HEA), AlCrFe 2 Ni 4 Ti, can be enhanced by increasing the Ti content, which raises the hardness of the alloy due to the formation of harder phases, including an L2 1 phase with disordered-BCC nano-precipitates, a η -Ni 3 Ti hexagonal phase, and a MgZn 2 -type Fe 2 Ti Laves phase. However, these hard but relatively brittle phases have negative influences on the wear resistance of the alloy if their amount exceeds a certain level, especially when large impact forces or large fluctuations in wearing force are involved. In this work, we added carbon to AlCrFe 2 Ni 4 Ti 2 to reduce the Ti-containing brittle phases and form in situ TiC particles in the metallic matrix with improved ductility. Samples of AlCrFe 2 Ni 4 Ti 2 C X (x = 0, 0.5 and 1.0, in molar ratio) were fabricated by arc melting. The fabricated HEA-matrix with in situ TiC particles showed improved ductility, e.g., the compressive ductility was increased by up to 30%, along with increased ultimate compressive strength, although the yield strength was slightly decreased, compared with the alloy without carbon addition. Wear tests demonstrated that the HEA with in situ TiC particles showed consequently enhanced wear resistance (10%–19% higher). This study demonstrates an effective approach to modify the high-entropy alloy for enhanced wear resistance by eliminating or minimizing Ti-containing brittle phases using carbon to react with Ti, forming in situ TiC particles in a HEA matrix with improved ductility. • High-entropy AlCrFe 2 Ni 4 Ti 2 -C X alloys with in situ synthesized TiC particles were prepared via arc melting. • The added carbon reacted with Ti to form in situ TiC particles, leading to improved ductility through reducing brittle η -Ni 3 Ti and Laves Fe 2 Ti phase. • Wear resistance of the alloy was enhanced due to the in situ TiC particles and improved toughness. • Surface and subsurface cracks caused by wear decreased due to improved ductility/toughness, helping lowering stress concentrations and thus wear. [ABSTRACT FROM AUTHOR]

• Laser power had the most importance on the yield strength, UTS, and elongation. • Powder feeding rate had the most importance on the microhardness and yield strength. • Scanning speed had the most importance on the maximum load value. • Optimal process parameters for the laser cladding coatings were identified. • The reduction of the Laves phase might be the main reason for the improvement of coating performance after optimization. The purpose of this study is to improve the quality of the multi-track laser cladding coating. The Taguchi-Grey relation method was selected to realize process parameter optimization. The Taguchi method is used to design an L 16 orthogonal experiment. The influence of three important laser cladding parameters (laser power, powder feeding rate, and scanning speed) on the micro-hardness, maximum load value, yield strength, UTS, and elongation had been analyzed based on the analysis of variance (ANOVA) and signal to noise ratio (SNR) methods. The results showed that the yield strength, UTS, and elongation were significantly affected by the laser power; the powder feeding rate denoted a highly significant influence on the microhardness and yield strength; and the scanning speed was a highly significant factor that had an influence on the maximum load value. Then, grey relational analysis (GRA) was used to convert five response targets into a single grey relational grade (GRG) that could be quantified in order to optimize the parameters for maximum micro-hardness, maximum load value, yield strength, UTS, and elongation. Finally, the optimum cladding process parameters were obtained. Through analysis of microstructure, the reduction of the Laves phase might be the main reason for the improvement of coating performance after optimization. [ABSTRACT FROM AUTHOR]

Selective CO2 photoreduction into C2 fuels under mild conditions suffers from low product yield and poor selectivity owing to the kinetic challenge of C−C coupling. Here, triatomic sites are introduced into bimetallic sulfide to promote C−C coupling for selectively forming C2 products. As an example, FeCoS2 atomic layers with different oxidation degrees are first synthesized, demonstrated by X‐ray photoelectron spectroscopy and X‐ray absorption near edge spectroscopy spectra. Both experiment and theoretical calculation verify more charges aggregate around the introduced oxygen atom, which enables the original Co−Fe dual sites to turn into Co−O−Fe triatomic sites, thus promoting C−C coupling of double *COOH intermediates. Accordingly, the mildly oxidized FeCoS2 atomic layers exhibit C2H4 formation rate of 20.1 μmol g−1 h−1, with the product selectivity and electron selectivity of 82.9 % and 96.7 %, outperforming most previously reported photocatalysts under similar conditions. [ABSTRACT FROM AUTHOR]

Selective CO2 photoreduction into C2 fuels under mild conditions suffers from low product yield and poor selectivity owing to the kinetic challenge of C−C coupling. Here, triatomic sites are introduced into bimetallic sulfide to promote C−C coupling for selectively forming C2 products. As an example, FeCoS2 atomic layers with different oxidation degrees are first synthesized, demonstrated by X‐ray photoelectron spectroscopy and X‐ray absorption near edge spectroscopy spectra. Both experiment and theoretical calculation verify more charges aggregate around the introduced oxygen atom, which enables the original Co−Fe dual sites to turn into Co−O−Fe triatomic sites, thus promoting C−C coupling of double *COOH intermediates. Accordingly, the mildly oxidized FeCoS2 atomic layers exhibit C2H4 formation rate of 20.1 μmol g−1 h−1, with the product selectivity and electron selectivity of 82.9 % and 96.7 %, outperforming most previously reported photocatalysts under similar conditions. [ABSTRACT FROM AUTHOR]

Purpose: The influence of the number and arrangement of bolts on the tensile properties of bolted composite laminates was studied in the present study. Design/methodology/approach: Based on the finite element model, the stiffness degradation method is used to simulate the damage evolution process for the failure of bolted composite laminates. Using ABAQUS finite element software combined with material failure criteria, the numerical calculation of the connection strength and failure mode of bolted composite laminates was carried out. Findings: The results of the study show that the tensile strength of the composite laminates connected by three bolts is higher than that of the laminates connected by two bolts. And the arrangement of different bolts has a great influence on the failure strength of bolted laminates. Originality/value: Bolted connection of composite laminates is a common problem in engineering practice. The effect of bolt arrangement and number on the strength of composite laminates is studied in this manuscript. [ABSTRACT FROM AUTHOR]

Magnetorheological fluid (MRF) is a widely used smart material that suffers from sedimentation. Since sedimentation is unavoidable, it is crucial to study and improve the redispersibility of MRFs. However, previous redispersibility testing methods have problems, such as complicated operation and low precision. Simultaneously, a simple and effective method is urgently needed for high-precision modeling of MRF sedimentation to test the rheological properties of settled MRFs at different depths. After systematically analyzing the redispersion problem, this paper proposes decoupling the energy required for redispersing settled MRFs into two parts, which are related to different factors. These two parts are the energy required to separate the agglomerated particles (related to the MRF formula) and that to redisperse the settled MRF uniformly vertically against gravity (related to the solid concentration and packing limit). The energy that separates the agglomerated particles is proportional to the shear stress of slowly shearing the corresponding agglomerated samples, i.e., the yield stress. Thus, this paper proposes a simple microdamage quasi-static indentation method to measure the yield stresses of settled MRFs at different depths to characterize the redispersibility of the corresponding MRFs. Herein, this method is applied to study the mechanisms of the influences of surfactants, thixotropic agents, and their networks on the redispersibility of MRFs. The results indicate that a well-dispersed plate-like thixotropic agent network can effectively improve redispersibility, while surfactants with poor compatibility degrade redispersibility. In summary, this redispersibility test method will greatly facilitate studies of MRFs, such as optimizing the formulas and establishing sedimentation models. [ABSTRACT FROM AUTHOR]

In this study, CO2‐ and Fe3O4‐assisted corrosion of the cement–casing interface for the magnetite (Fe3O4) high‐density cement–casing steel system in simulated formation water is investigated under the normal and high CO2 pressure conditions. Results show that the degradation of the cement–casing interface is affected by the competition of cement hydration and CO2 corrosion. The migration of CO2 and corrosive species to the cement–casing interface is facilitated under the high pressure condition, resulting in enhanced corrosion rate as compared to the normal pressure condition. The casing steel is in active corrosion state while the corrosion rate gradually increases with time. After long term of immersion, a layer of thick corrosion products with multiple cracks/microgaps forms at the cement–casing interface, which can hardly protect the casing steel from further corrosion. The corrosion products on the steel surface are mainly FeCO3 accompanied by a small amount of CaCO3 and Fe3O4, suggesting the prevalence of CO2 corrosion. The mechanism of the CO2‐ and Fe3O4‐facilitated corrosion of the cement–casing interface for the magnetite high‐density cement–casing system is proposed. [ABSTRACT FROM AUTHOR]