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Purpose: Tyrosine kinase inhibitors (TKIs) targeting epidermal growth factor receptor (EGFR) improve the prognosis of lung adenocarcinoma (LUAD). However, the factors affecting its clinical efficacy remain unclear. This study aimed to determine the correlation between Osteopontin (OPN) and EGFR, and explore the inhibitory effect of first-generation TKI gefitinib on LUAD cells. Methods: The correlation between OPN and EGFR was determined through bioinformatics technology, and the clinical information as well as samples of related patients were collected to verify the relationship between them. Using three different NSCLC cell lines A549, H1299 and PC9, we studied the effects of OPN expression and EGFR phosphorylation on the first-generation TKI's efficacy in vitro. Results: Our data revealed that OPN staining positively linked to a more advanced clinical stage. Compared with the control group, LUAD cells with elevated OPN levels are more sensitive to the growth inhibitory effect of TKI. Knocking down of OPN decreased the response of cells to gefitinib. Besides, OPN also upregulated the phosphorylation of EGFR, thereby affecting the effect of TKI. Conclusion: OPN enhanced the sensitivity of LUAD cells to gefitinib by promoting EGFR phosphorylation. OPN may be a potential target for evaluating TKI efficacy and a potential target for molecular therapy. [ABSTRACT FROM AUTHOR]

In this study, Saussurea bogedaensis Yu-J. Wang & Jie Chen, a new species from Bogeda Mountain in the eastern part of the Tianshan Mountains, is described and discussed based on evidence in terms of both morphological and genetic data. S. bogedaensis is morphologically similar to S. involucrata, which is distributed in the western part of the Tianshan Mountains, and it is well known because of its beauty, rarity, and medicinal value. The new species is also similar to S. orgaadayi, which is distributed in the nearby Altai Mountains. Our genetic data support the close relationships among these three species. According to their allopathic distributions, we suggest that these three species are derived from the same ancestor but that they differentiated after reaching their current range. In addition, we propose that the new species might serve as an alternative to S. involucrata in medicine due to their very high similarity. However, this species appears to be rare because we only found six mature individuals in the field despite extensive investigations. [ABSTRACT FROM AUTHOR]

To interact with humans more precisely and naturally, social robots need to "perceive" human engagement intention, especially need to recognize the main interaction person in multi-person interaction scenarios. By analyzing the intensity of human engagement intention (IHEI), social robots can distinguish the intention of different persons. Most existing research in this field mainly focus on analyzing whether a person has the intention to interact with the robot while lack of analysis of IHEI. In this regard, this paper proposes an approach for recognizing the engagement intention intensity. Four categories of visual features, including line of sight, head pose, distance and expression of human, are captured, and a CatBoost-based machine learning model is applied to train an optimal classifier for predicting the IHEI on the dataset. The experimental results show that this classifier can effectively predict the IHEI that can be applied into real human–robot interaction scenarios. Moreover, the proposed model is an interpretable machine learning model, where interpretability analysis on the trained classifier has been done to explore the deep associations between input features and engagement intention, thereby providing robust and effective robot social decision-making. [ABSTRACT FROM AUTHOR]

Homoploid hybrid speciation, the origin of a hybrid species without change in chromosome number, is currently considered to be a rare form of speciation. In the present study, we examined the phylogenetic origin of Hippophaë gyantsensis, a diploid species occurring in the western Qinghai-Tibet Plateau. Some of its morphological and molecular traits suggest a close relationship to H. rhamnoides ssp. yunnanensis while others indicate H. neurocarpa. We conducted phylogenetic analyses of sequence data of two maternally inherited chloroplast (cp) DNA fragments and the bi-parentally inherited nuclear ribosomal internal transcribed spacer ( ITS) from 17 populations of H. gyantsensis, 15 populations of H. rhamnoides ssp. yunnanensis and 27 populations of H. neurocarpa across their distributional ranges, and modelled the niche differentiation of the three taxa. Multiple lines of evidence suggested that H. gyantsensis is a morphologically stable, genetically independent and ecologically distinct species. The inconsistent phylogenetic placements of the H. gyantsensis clade that comprised the dominant cp DNA haplotypes and ITS ribotypes suggested a probable diploid hybrid origin from multiple crosses between H. rhamnoides ssp. yunnanensis and H. neurocarpa. This tentative hypothesis is more parsimonious than alternative explanations according to the data available, although more evidence based on further testing is needed. [ABSTRACT FROM AUTHOR]

Dense ZrC–W composite with 55.3 vol% ZrC and 44.7 vol% W was fabricated by reactive infiltration of molten Zr 2 Cu alloy into porous and rigid WC/W preform at low temperature (1300 °C) in vacuum. The liquid Zr 2 Cu alloy spontaneously infiltrated into the porous preform and underwent a displacement reaction with WC to fully form ZrC–W composite by substituting WC preform to WC/W perform. The formed ZrC–W composite had a flexural strength of 489 MPa, a Vickers hardness of 8.3 GPa, a Young's modulus of 352 GPa, and a fracture toughness of 9.8 MPa m 1/2 , which was two times higher than monoclinic ZrC. [ABSTRACT FROM AUTHOR]

Development of high-performance cutting tool materials is one of the critical parameters enhancing the surface finishing of high-speed machined products. Ti(C,N)-based cermets reinforced with and without different contents of silicon nitride were designed and evaluated to satisfy the requirements. In fact, the effect of silicon nitride addition to Ti(C,N)-based cermet remains unclear. The purpose of this study is to investigate the influence of Si3N4 additive on microstructure, mechanical properties, and thermal stability of Ti(C,N)-based cermet cutting tools. In the present work, α -Si3N4 "grade SN-E10" was utilized with various fractions up to 6 wt.% in the designed cermets. A two-step reactive sintering process under vacuum was carried out for the green compact of Ti(C,N)-based cermet samples. The samples with 4 wt.% Si3N4 have an apparent solid density of about 6.75 g/cm3 (relative density of about 98 %); however, the cermet samples with 2 wt.% Si3N4 exhibit a superior fracture toughness of 10.82 MP a.m 1 / 2 and a traverse rupture strength of 1425.8 MPa. With an increase in the contents of Si3N4, the Vickers hardness and fracture toughness of Ti(C,N)-based cermets have an inverse behavior trend. The influence of Si3N4 addition on thermal stability is clarified to better understand the relationship between thermal stability and mechanical properties of Ti(C,N)-based cermets. [ABSTRACT FROM AUTHOR]

Abstract: Fully dense ZrCcomposite was fabricated by reactive infiltration technique, where molten Zr2Cu alloy infiltrated into a porous WC preform at 1300°C in vacuum. The ZrCte exhibits a core-shell structure feature: gray WC cores were enveloped by bright tungsten shells, which are homogeneously distributed in the ZrC matrix. X-ray diffraction and transmission electron microscopy investigation show that nano-sized Zr x Cu y C z particles were formed in the ZrC matrix. The Vicker''s hardness, flexural strength and fracture toughness of the ZrCte are measured as 14.5GPa, 615MPa and 11.7MPam1/2, respectively. [Copyright &y& Elsevier]

Abstract: ZrC–W composite was produced by reactive infiltration of Zr2Cu into WC preform at 1200°C. The WC reacted completely with Zr in the alloy to form 61.8vol% ZrC and 38.2vol%W. The infiltrated composite reached a relative density of 98.3% and average grains sizes of about 0.5μm. The flexural strength and the fracture toughness of the ZrC–W composite was improved by the addition of W. [Copyright &y& Elsevier]

The genus Saussurea is distributed mainly in the temperate and subarctic regions of Eurasia and consists of about 300 species classified into six subgenera and 20 sections. Sect. Pseudoeriocoryne in the subgenus Eriocoryne comprises four species, and is delimited mainly by acaulescence and an inflorescence with congested capitula surrounded by a rosette of leaves. All of these species are endemic to the arid Qinghai–Tibet Plateau. Sequences from the chloroplast DNA trnL–F region were obtained for the four species in this section and 26 other species from four subgenera of Saussurea to resolve phylogenetic relationships among these species and to determine whether the shared characters that define sect. Pseudoeriocoryne are synapomorphic or were acquired by convergent evolution. The resulting phylogenies indicated that Saussurea sect. Pseudoeriocoryne as traditionally defined does not constitute a monophyletic group and that each of its species belongs to separate clades. Furthermore, none of these species showed a close relationship with the other species of subgenus Eriocoryne. Our results further indicated that none of the investigated subgenera are monophyletic, and that species from different subgenera clustered together. All these conclusions are provisional and their confirmation would require stronger phylogenetic support. Two possible explanations are suggested for low sequence divergence, poor resolution of internal clades and clustering of species with the rather distinct morphology of Saussurea detected in the present study. The first is rapid radiation and diversification triggered by fast habitat fragmentation due to the recent lifting of the Qinghai–Tibet Plateau and the Quaternary climate oscillations. This could have led to rapid morphological divergence while sequences diverged very little, and also caused the convergent acquisition of similar characteristics in unrelated lineages due to similar selection pressures. The second possible explanation is that both introgressive hybridization and reticulate evolution might have caused the transferring of cpDNA sequences between morphologically dissimilar species, thus leading to homogenization of sequences between lineages. [Copyright &y& Elsevier]

Mechanical activation followed by rotary heating has been successfully applied to the synthesis of Cr-doped lithium manganese oxide (LiMn2O4) powders. The precursor of LiCrxMn2−xO4 for Li-ion batteries has been synthesized from LiOH·H2O, MnO2, and Cr2O3 as starting materials by mechanical activation, which ensured a high level of homogeneity in the chemical composition of the precursor and resulted in a reduction in the synthesis temperature and heating time. Highly crystallized LiCrxMn2−xO4 (0.04≤x≤0.10) powders were obtained by subsequent rotary heating of the precursor at 550–750 °C for 2 h. Rotary heating enhanced the experimental control in chemical composition, particle size distribution and microstructure of the final products. The optimum mechanical activation condition was determined based on XRD analysis. The synthesized LiCrxMn2−xO4 powder has a narrow particle size distribution, high discharge capacities and good cyclability. The method of mechanical activation combined with rotary heating should be an excellent technique of decreasing synthesis temperature and shortening heating time, and enhancing the uniformity of particle size of the product. [Copyright &y& Elsevier]

Tungsten and tungsten alloys are widely used in high temperature environments where arc ablation or mechanical deformation and damage are the main sources of materials failure. For high temperature critical applications in thermomechanical environments, however, the low strength limits the use of tungsten and tungsten alloys. Hence, new tungsten based materials with good high temperature thermomechanical properties need to be developed in order to extend the use of tungsten. TiC particle-reinforced tungsten based composites (TiCp/W) were fabricated by hot pressing at 2000 °C, 20 MPa in a vacuum of 1.3×10−3 Pa. The composites were examined with respect to their thermophysical and mechanical properties at room temperature and at elevated temperature. Vickers hardness and elastic modulus increased with increasing TiC content from 0 to 40 vol.%. The highest flexural strength, 843 MPa, and the highest toughness, 10.1 MPa m1/2, of the composites at room temperature were all obtained when 20 vol.% TiC particle were added. As the test temperature rose, the flexural strength of the TiCp/W composites firstly increased and then decreased, except in the monolithic tungsten. The highest strength of 1155 MPa was measured at 1000 °C in the composite containing 30 vol.% TiC particles. The strengthening effect of TiC particles on the tungsten matrix is more significant at high temperatures. With the addition of TiC particles, the thermal conduction of tungsten composites was drastically decreased from 153 W m−1 K−1 for monolithic W to 27.9 W m−1 K−1 for 40 vol.% TiCp/W composites, and the thermal expansion was also increased. The new composites are successfully used to make high temperature grips and moulds. [Copyright &y& Elsevier]

In order to improve the elevated temperature mechanical properties and modify the thermophysical properties of tungsten, tungsten matrix composites containing 30 vol.% zirconium carbide particles (ZrC/W) were prepared by vacuum hot-pressing at 2000 °C. Flexural strength of ZrC/W composites increases gradually with increasing temperature and reaches a maximum value at 1000 °C. The observation of the fracture characteristics of ZrC/W composites at various temperatures reveals that the excellent elevated temperature strength is attributed to the brittle–ductile transition in the tungsten matrix, which allows a more effective strengthening effect from the zirconium carbide particles. The elastic modulus decreases slightly with increasing temperature from room temperature to 1200 °C, and as a result of the addition of zirconium carbide particles the modulus of ZrC/W is higher than that of monolithic tungsten at all testing temperatures. The addition of zirconium carbide remarkably decreases the thermal conductivity of the composites. The unique combination of high melting point, good high temperature strength, high elastic modulus, and low thermal conductivity is very beneficial to the high temperature application of ZrC/W composites. [Copyright &y& Elsevier]

A difference equation can well describe a lattice problem, and its dynamical property was always modeled approximately by a differential-difference equation. This paper suggests a fractal differential-difference model by taking into account the lattice's geometry. The fractal differential-difference Burgers equation and the fractal Klein–Gordon equation are used as examples to study the solution properties by the Lie group method, and various Lie algebras of the corresponding Lie transformation group are also obtained. [ABSTRACT FROM AUTHOR]

A new ternary Zr x Cu y C z phase is observed in the reactively infiltrated ZrC/W composite. The X-ray diffraction and transmission electron microscopy analyses reveal that the Zr x Cu y C z phase has a same rocksalt structure as ZrC, but possesses sixfold long-period structure with lattice constant of 2.88 ± 0.07 nm. This finding indicates the existence of Zr x Cu y C z compound, which expands the ternary carbides and nitrides permutation space. [ABSTRACT FROM AUTHOR]

The complete nucleotide sequence of the Taiwan red pinePinus taiwanensisHayata chloroplast genome (cpDNA) is determined in this study. The genome is composed of 119,741 bp in length, containing a pair of very short inverted repeat (IRa and IRb) regions of 495 bp, which was divided by a large single-copy (LSC) region of 65,670 bp and a small single-copy (SSC) region of 53,080 bp in length. The cpDNA contained 115 genes, including 74 protein-coding genes (73 PCG species), 4 ribosomal RNA genes (four rRNA species) and 37 tRNA genes (22 tRNA species). Out of these genes, 12 harbored a single intron, and one (rps12) contained a couple of introns. The overall AT content of the Taiwan red pine cpDNA is 61.5%, while the corresponding values of the LSC, SSC and IR regions are 62.2%, 60.6% and 63.6%, respectively. A maximum parsimony phylogenetic analysis suggested that the genusPinus, Picea, AbiesandLarixwere strongly supported as monophyletic, and the cpDNA ofP. taiwanensisis closely related to that ofP. thunbergii. [ABSTRACT FROM AUTHOR]

Graphical abstract Fabrication and microstructural characterization of nanostructured eutectic surface layers on conventionally sintered Al 2 O 3 -ZrO 2 ceramic via the laser rapid solidification. Highlights • Nanostructured surface layer is grown epitaxially on the as-sintered Al 2 O 3 -ZrO 2 polycrystalline ceramics. • The microstructural evolutions of nanostructured surface layer were initially explored. • The geometrical evolution of molten pool in response to laser remelting parameters was established. Abstract In the present work, nanostructured surface layers of Al 2 O 3 -ZrO 2 eutectic with a thickness of approximate 1000 μm and free of cracks and pores were produced on the surface of conventionally-sintered Al 2 O 3 -ZrO 2 ceramic via the laser irradiation rapid solidification process. The molten pool geometry and microstructure were characterized by scanning electron microscopy and Raman spectroscopy. The geometrical evolution of molten pool in response to laser power and laser scanning velocity was established, where the top view of molten pool exhibits a circular shape at low velocities and gradually evolves into an oval-shaped surface at high velocities. Singular Al 2 O 3 -ZrO 2 eutectic colonies with a size of 100–200 μm, which is formed around a spontaneously nucleated dendritic ZrO 2 core, are found on the surface of laser-remelted layer. The eutectic colony has an interphase spacing of 190–280 nm. The variation of eutectic spacing with growth rate is essentially linear on the logarithmic scale as λ = K V - 0.4 by binary regression analysis. Predicted by the Jackson-Hunt theory on eutectic solidification (JH theory), the eutectic spacing is consistent with the inverse-square-root dependence on growth rate with a proportionality constant of 3.32. The eutectic colonies consist of α -Al 2 O 3 , t -ZrO 2 and m -ZrO 2 phases, where α -Al 2 O 3 and t -ZrO 2 are the dominant phases and the m -ZrO 2 phase increases with the decrease of laser scanning velocity. [ABSTRACT FROM AUTHOR]

Abstract The nucleation and epitaxial growth behavior of a novel Al 2 O 3 -ZrO 2 nanoeutectic rapidly solidified from the oxyacetylene flame remelting have been investigated. The nanoeutectic ceramic consists mainly of highly textured cellular structure with an average interphase spacing of 136 nm. Especially, a singular transition mechanism associated with " one-step cellular refining " to " two-step cellular refining " is proposed in a variable region from a coarse irregular to an ultrafine lamellar structure, and the regional undercooling is estimated to be 0.57–2.86 K. The Al 2 O 3 phase nucleates as the leading phase in the rapidly solidified structure according to a quantitative calculation of nucleation rate. The cellular eutectic exhibits with a tilted feature, where its cellular growth deviates from the heat flow direction to a preferred growth orientation. [ABSTRACT FROM AUTHOR]

Nanocrystalline alumina-zirconia-based eutectic ceramics fabricated with high-energy beams and composed of ultrafine, three-dimensionally entangled, single-crystal domains are a special category of eutectic oxides that exhibit exceptionally high-temperature mechanical properties, such as strength and toughness as well as creep resistance. This paper aims to provide a comprehensive review on the basic principles, advanced solidification processes, microstructure and mechanical properties of alumina-zirconia-based eutectic ceramics, with particular attention to the status of the art on a nanocrystalline scale. Some basic principles of coupled eutectic growth are first introduced based on previously reported models, followed by concise introduction of solidification techniques and the control strategy of solidification behavior from the processing variables. Then, the microstructural formation of nanoeutectic structure is elucidated with regard to different hierarchical scales, and mechanical properties such as hardness, flexural and tensile strength, fracture toughness and wear resistance are discussed in detail for a comparative study. Nanocrystalline alumina-zirconia-based eutectic ceramics with unique microstructural and compositional characteristics have been produced with high-energy beam-based processes, and in many cases, promising improvements in mechanical performance have been reported as contrasting with conventional eutectic ceramics. [ABSTRACT FROM AUTHOR]

Calcia-magnesia-aluminosilicate (CMAS) corrosion behaviors of hot-pressed (Y 1- x Yb x) 2 SiO 5 ceramics at 1673 K and 1773 K have been investigated. The main corrosion product of nonstoichiometric Ca-RE-Si-O apatite phase evolves with increasing temperature or prolonging corrosion time. The growth of apatite layer at 1673 K follows approximately a linear rate law, however it follows a proximately parabolic rate law at 1773 K. The growth rate of the apatite layer at 1773 K is lower than that at 1673 K in the process of interaction between CMAS and rare-earth monosilicates. Yb-doping mediates the CMAS corrosion resistance of Y 2 SiO 5 effectively by changing the growth rate of apatite layer and the composition of formed apatite phase. This work provides new insights on compositional regulation of (Y 1- x Yb x) 2 SiO 5 EBCs materials to resist CMAS corrosion. [ABSTRACT FROM AUTHOR]

W-ZrC composites without residual WC have been prepared for the first time by reactive infiltration at 1300 °C for 1 h in vacuum using a molten Zr 2 Cu alloy and a newly designed partially-carburized W powder as raw materials. The as-synthesized composites consist of two major phases of W and ZrC, in which the content of W is 65 vol%. The reaction time needed to produce a fully densified W-ZrC bulk ceramic is distinctly shortened by this means, as contrasted with conventional WC/W or WC preforms. The microstructural evolution during reactive melt infiltration is investigated to obtain a better understanding of reaction mechanisms and mechanical properties of the W-ZrC composites derived by infiltrating Zr 2 Cu alloy into partially carburized W preforms. The flexural strength, Young's modulus and fracture toughness for the W-ZrC composite are 554 MPa, 339 GPa and 9.7 MPa·m 1/2 , respectively. [ABSTRACT FROM AUTHOR]

In the present work, microstructural refinement and mechanical response of Al 2 O 3 –ZrO 2 eutectics fabricated by a pulse discharge plasma assisted melting (PDPAM) method were investigated. The solidified microstructure evolves from polygonal eutectic colonies into irregular cellular colonies with increasing the superheating temperature of the melt from 1820 °C to 1900 °C. The average eutectic spacing inside the colonies decreases from 1.80 ± 0.10 μm to 0.25 ± 0.06 μm, and the coarse inter-colonial structure is refined, which is attributed to the increase in undercooling temperature. High-temperature microstructural stability of Al 2 O 3 –ZrO 2 eutectics is improved significantly as contrasted with the as-sintered ceramics. Besides, the load dependence of Vickers hardness for Al 2 O 3 –ZrO 2 eutectics is investigated. [ABSTRACT FROM AUTHOR]

The surface microstructure of advanced tool materials is critical, as it directly affects subsequent processing or the performance in use as original condition. In this work, the microstructural evolution and formation mechanism of metal capping on the surface of Ti(C, N)-based cermets, during liquid phase sintering were investigated. Surface metal capping on Ti(C, N)-based cermets is formed during the cooling stage of liquid phase sintering, driven by the contraction pressure of ceramic particle skeleton in the middle stage, in which an adequate amount of liquid phase and significant densification are vital prerequisites. The formation of a step-like textured metal capping is attributed to volume contraction during solidification of liquid phase on the sample surface, in which directional solidification caused by carbon gradient is necessary in this process. Transport behavior of molten metal associated with metal capping on Ti(C, N)-based cermets is divided into four stages in order as infiltration, extrusion, aggregation, and evaporation. The energy of crack propagation is greatly dissipated by plastic deformation of metal capping, thereby greatly improving the fracture toughness of original surface of the sample. [Display omitted] • The formation mechanism of surface metal capping and step-like texture on Ti(C, N)-based cermets is revealed. • The transport behavior of molten metal on the surface of Ti(C, N)-based cermets is clarified. • The presence of a metal capping greatly improves the fracture toughness of the original surface of Ti(C, N)-based cermets. [ABSTRACT FROM AUTHOR]

The composition complexity of Ti(C, N)-based cermets poses a great challenge to the controllability of their sintering process. The effects of both refractory TaC addition and original particle size of starting materials on densification behavior and microstructural evolution of Ti(C, N)-based cermets were investigated during liquid phase sintering. The particle rearrangement only plays a very limited role in promoting densification of Ti(C, N)-based cermets at the initial stage of liquid phase sintering, whereas the pore-filling in the presence of liquid phase becomes a dominant densification mechanism in the middle stage or even earlier. Enhanced densification of ultrafine Ti(C, N)-based cermets is realized by introducing refractory TaC additive based on the grain growth-induced liquid phase pore-filling mechanism, which is also verified by an extended study using other refractory carbide additives such as NbC, ZrC and HfC. This work provides a novel idea for the development of fully densified ultrafine Ti(C, N)-based cermets with outstanding mechanical properties, which are highlighted in machining applications of difficult-to-machine materials as well as other wear-resistant parts operating in high-temperature and high-stress environments. [Display omitted] • The effects of both TaC addition and the particle size of starting materials on the densification behavior of Ti(C, N)-based cermets are clarified. • Enhanced densification of ultrafine Ti(C, N)-based cermets is realized by introducing refractory TaC additive. • This work provides a novel idea for the development of fully densified ultrafine Ti(C, N)-based cermets. [ABSTRACT FROM AUTHOR]

Ultrafine Ti(C, N)-based cermets are vacuum-sintered by refining the particle size of raw materials and tailoring the WC/TaC ratio to achieve the improvements in comprehensive mechanical properties and cutting performance. The hardness, flexural strength and tool lifespan of ultrafine Ti(C, N)-based cermets are substantially higher than those of submicron Ti(C, N)-based cermets with the same composition because of the refined grains and the improved distributions of both metal phases and residual stress. The hardness attenuation behavior and strengthening mechanism in Ti(C, N)-based cermets at different test temperatures have been proposed. At 400 ℃, the hardness attenuation of Ti(C, N)-based cermets depends mainly upon the softening of metal phases. However, at 800 ℃, the hardness attenuation of Ti(C, N)-based cermets is mainly related to the reduced bearing capacity of hard ceramic phases and interfacial sliding. The addition of refractory TaC is beneficial for the improvement of high-temperature mechanical properties and the tool lifespan, attributed to the strengthening of the ceramic framework by tantalum atoms. • The strategy on synergistic refinement of raw powders with various constituents in ultrafine Ti(C, N)-based cermets is proposed for the first time. • The comprehensive properties of ultrafine Ti(C, N)-based cermets are substantially higher than those of submicron Ti(C, N)-based cermets. • The hardness attenuation behavior and strengthening mechanism in Ti(C, N)-based cermets at different test temperatures are proposed. [ABSTRACT FROM AUTHOR]

Revealing the grain growth behavior during liquid phase sintering is of great significance for scientific application of grain growth inhibition strategies and the regulation of microstructure. In this study, the effects of both TaC addition and the particle size of starting materials on microstructure of Ti(C, N)-based cermets were investigated. Ultrafine Ti(C, N)-based cermets modified with TaC addition exhibit an obvious grain growth of grey phase during liquid phase sintering. The grain growth of grey phase is typically controlled by liquid-phase diffusion, with the grain growth index of 3 and activation energy of 48–66 kJ/mol. In particular, the increase in grain contiguity of grey phase caused by the evaporation of metal liquid phase at high temperatures, faceted transition of grey phase grains, and the loss of carbon and nitrogen are considered to be the main reasons for the decrease in the grain growth rate of grey phase at high temperatures. • The effects of TaC addition and initial particle size of raw materials on microstructure of Ti(C, N)-based cermets were elucidated. • The growth mechanism of grey-phase grains in TaC-modified ultrafine Ti(C, N)-based cermets was revealed. • The reason why the growth rate of grey phase grains in Ti(C, N)-based cermets is reduced at high temperatures was clarified. [ABSTRACT FROM AUTHOR]

Four kinds of quinary high-entropy rare-earth (RE) monosilicates and (Y 1- x Yb x) 2 SiO 5 have been synthesized by solid-state reaction method. Selected rare-earth oxides of Lu 2 O 3 to Gd 2 O 3 react with silica to form homogeneous monosilicate solid solutions at a sintering temperature of 1773 K for 4 h. Wherein Gd-Si-O transforms from oxy-apatite type to X2-RE 2 SiO 5 with increasing the synthesis temperature from 1573 K to 1773 K. Increasing the rare-earth ion species changes the distortion degrees of [REO m ] a little bit. However, it's more effective to improve the distortion degrees with only introducing Yb3+ into Y3+ sites of Y 2 SiO 5. Stronger distortion of [REO m ] improves the high-temperature resistance to thermal deformation, resulting in a lower coefficient of thermal expansion (CTE). Due to the highest distortion degree of [REO m ], (Y 0.2 Yb 0.8) 2 SiO 5 exhibits the lowest CTE of 6.78 × 10−6 K−1 at 1473 K. Meanwhile, RE-doping enhances the distortion and phonon scattering, contributing to a lower thermal conductivity. [ABSTRACT FROM AUTHOR]

LiMn2−xAlxO4 (0.0⩽x⩽0.10) intercalation powders have been synthesized by mechanical alloying followed by rotary heating. The precursor of LiMn2−xAlxO4 has been prepared using LiOH · H2O, MnO2, and Al2O3 by mechanical alloying, which ensured a high level of homogeneity in the chemical composition of the precursor and resulted in a reduction in the synthesis temperature and heating time. Highly crystallized LiMn2−xAlxO4 powders were obtained by subsequent rotary heating of the precursor at 600 °C for 3 h. Rotary heating enhanced the experimental control in particle size distribution of the final products. The synthesized LiMn2−xAlxO4 powder has a narrow particle size distribution, high discharge capacities and good cycleability. Compared with the conventional solid-state reaction process, the present method of mechanical alloying combined with rotary heating should be a suitable technique of decreasing synthesis temperature and shortening heating time, and enhancing the uniformity of particle size of the product. [Copyright &y& Elsevier]

The high temperature ablation behavior of tungsten composites containing carbides produced by vacuum hot pressing is studied as a function of reinforcement chemistry (ZrC and TiC) and content using a self-made oxyacetylene ablation equipment. A dynamic responding multiwavelength pyrometer was employed to measure the temperature of the ablation surface, and a thermocouple was employed to measure the temperature of the back surface during the time that a specimen was being ablated. The mass and linear ablation rates are lower in composites containing ZrC, decreasing with increasing particle content in both composites system. The values of the mass and linear ablation rates were in the order from high to low: W>30TiC/W>40TiC/W>30ZrC/W>40ZrC/W (30TiC/W stands for 30 vol.% TiC particle content in the W matrix, the same below). The important temperature curves of the ablation surfaces of specimens were successfully detected online. Ablated surfaces and vertical sections of the specimens were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Thermochemical oxidation of tungsten, TiC, and ZrC was the main ablation mechanism of ZrC/W and TiC/W composites. These ablation behaviors are discussed based on the thermophysical and chemical properties of both the composite systems. [Copyright &y& Elsevier]

This work uses in situ transmission electron microscopy (TEM) based micromechanical testing to isolate and quantify the microstructural toughening mechanisms active in nanostructured Al 2 O 3 /GdAlO 3 eutectic samples. The effect of fracture direction across orthogonal sections of the rod-like eutectic was used to reveal the influence of different fracture paths and mechanisms on toughening. The average fracture toughnesses of the rod-like structures in the longitudinal cross-section and transverse cross-section are 2.4 MPa·m1/2 and 2.7 MPa·m1/2, respectively. Multiple samples tested in the longitudinal cross-section show significant R-curve toughening response, and obtain values greatly exceeding the initial values upon crack extension. It is concluded that nanoscale crack bridging induces deflection of the crack path, which leads extrinsic energy dissipation as the crack opens. Micropillar compressions are also performed to investigate the composite's strength. Sample orientation strongly affects the deformation mode and interfacial sliding occurs when the maximal shear stress is parallel to the interface. [ABSTRACT FROM AUTHOR]

As a special type of lung cancer, multiple primary lung cancer (MPLC) has unique biological characteristics, and its research remains limited. The aim of our research was to identify prognostic factors and construct a prognostic nomogram of dual primary lung cancer (DPLC). A population cohort study of patients with DPLC was conducted using the extracted data from the Surveillance, Epidemiology, and End Results (SEER) database. Relevant survival variables were identified using the Cox proportional hazard model. Prognostic nomogram was performed and its predictive performance was validated via the modeling and validating cohort data. Additionally, propensity score matching (PSM) was also applied to evaluate whether surgery affected the OS of this study population. 5411 eligible DPLC patients were included in this study cohort, with 41.0% of 3-year OS rate and 27.7% of 5-year OS rate. Age, sex, race, grade, stage, lymph node (LN) metastasis, histological type, primary site, and surgery were considered to be prognostic factors of OS. The C-indexes of the established nomogram were 0.70 (95% CI (0.69, 0.71)) in the modeling group and 0.70 (95% CI (0.68, 0.72)) in the validation group, which showed an ideal model discrimination ability. AUC and calibration plots of 3- and 5-year OS also proved the good performance of the established nomogram. After 1 : 1 PSM, surgery can potentially reduce the risk of OS (HR = 0.63, 95% CI: 0.56–0.72) of DPLC. The prognostic nomogram with reliable performance was developed to predict 3- and 5-year OS rates, which could assist clinicians to make more reasonable survival prediction for DPLC patients. For patients without absolute surgical contraindications, surgery should be actively considered. [ABSTRACT FROM AUTHOR]

To seek out novel promising biomarkers for predicting lung adenocarcinoma (LUAD) prognosis, we conducted this study. First, 279 upregulated and 37 downregulated differentially expressed genes were obtained from LUAD and para‐carcinoma tissues by the Affymetrix GeneChip Human Transcriptome Array. Then, we randomly classified samples of LUAD data set GSE31210 as training and testing sets in a 1:1 ratio. Alcohol dehydrogenase 1C (ADH1C) and secreted phosphoprotein 1 (SPP1) were finally identified correlating with the LUAD survival through least absolute shrinkage and selection operator penalized Cox proportion hazards regression model, and applied to build a 2‐gene signature related to prognosis in training set. Univariate and multivariable survival analyses suggested that overall survival (OS) and relapse‐free survival (RFS) in the 2‐gene signature low‐risk group were better than the high‐risk group. Kaplan–Meier curves proved that elevated ADH1C expression and reduced SPP1 expression were related to better OS and RFS. Besides, the SPP1 expressed higher in LUAD than para‐carcinoma tissues using quantitative reverse transcription polymerase chain reaction assay. Finally, the association between the two genes and clinicopathological parameters in 80 LUAD were analyzed, it is suggested that SPP1 was relevant to epidermal growth factor receptor mutation. These findings indicated that ADH1C and SPP1 might be novel promising biomarkers for predicting LUAD prognosis. [ABSTRACT FROM AUTHOR]

Li 7– x La 3 Zr 2– x Ta x O 12 (0 ≤ x ≤ 1) ceramics were prepared by pressureless sintering at 1230 °C in air. XRD, SEM and Impedance test were used to characterize the crystal structure, microstructure and electrical performance of Li 7– x La 3 Zr 2– x Ta x O 12 ceramics. According to XRD data, the specimens with x ≥ 0.2 sintered at 1230 °C for 1 h exhibit a cubic garnet structure without impurities. The Ta-doped specimens sintered at 1230°C for 1 h show high relative density of 91.6%–93.9%. Ta doping has a certain effect on the Li vacancy concentration, lithium arrangement, movable Li+ concentration and microstructure of the LLZO ceramic. The Li 6.6 La 3 Zr 1.6 Ta 0.4 O 12 ceramic sintered at 1230°C for 1 h has the highest total conductivity of 6.01 × 10–4 S·cm–1 at room temperature and the lowest activation energy of 0.27 eV. [ABSTRACT FROM AUTHOR]

This study aims to elucidate the impact of interfacial microstructure and properties on fracture toughness in binary Al 2 O 3 /SmAlO 3 eutectic and its polycrystalline samples via in-situ microcantilever deflection tests. Al 2 O 3 -SmAlO 3 eutectic with semi-coherent heterointerfaces exhibits superior interfacial toughness of 2.85 MPa⋅m1/2 relative to randomly oriented interfaces in Al 2 O 3 /SmAlO 3 polycrystals. SmAlO 3 grain boundaries (GBs) have the lowest toughness of 1.97 MPa⋅m1/2 among all the constituents, i.e. bulk and interfaces. The toughness of eutectic Al 2 O 3 -SmAlO 3 interfaces is intermediate between polycrystalline Al 2 O 3 -Al 2 O 3 GBs and SmAlO 3 -SmAlO 3 GBs. Fracture toughness values of both polycrystalline and eutectic Al 2 O 3 -SmAlO 3 samples obtained by mesoscopic indentation measurements are in the range of 4.2 MPa⋅m1/2to 4.7 MP⋅m1/2, which exceeds all constituent components. Much of the overall fracture toughness of the bulk samples derives from microstructural and geometric energy dissipation mechanisms. [ABSTRACT FROM AUTHOR]

The present work aims to provide fundamental insights into the grain size dependence and mechanical behavior of hot-pressed Al 2 O 3 -ZrO 2 ceramic at its eutectic composition, and further to explore the hardening effect of laser-induced surface nanoeutectic layer. The underlying correlations between densification behavior, grain size distribution and mechanical properties were elucidated. Sintering at 1550 °C promotes the densification without extensive grain growth, and in this case the sample exhibits a critical density of 99.3 %. The average grain size is tailored into a range of 0.6–0.9 μm, and the measured flexural strength and toughness reach 1100 MPa and 11 MPa·m1/2, respectively. The metastable t -ZrO 2 grains indeed play a pivotal role in energy dissipation at the crack tip through crack deflection and branching. In addition, the mechanical behavior is reasonably explained through constructing a multilevel toughening mechanism map associated with grain size distribution of ZrO 2. Particularly, surface nanocrystallized Al 2 O 3 -ZrO 2 eutectic layer with a thickness of 1000 μm free of pores and cracks is achieved by a rapid laser melting process. The outmost laser-modified nanoeutectic layer exhibits a fine cellular structure with an interphase spacing of only 105 nm and a hardness of as high as 26.1 GPa, which provides a promising potential in enhancing significantly the hardness and wear resistance for applications as sliding ceramic components. [ABSTRACT FROM AUTHOR]

Plasma electrolytic oxidation (PEO) has become an effective surface modification method to form ceramic coatings on orthorhombic Ti 2 AlNb alloy due to its high productivity, economic efficiency and ecological friendliness. In the present work, different contents of Al 2 O 3 additive were introduced into a NaAlO 2 basic electrolyte with the aim of improving the high-temperature properties of PEO ceramic coatings on Ti 2 AlNb alloy. The influence of Al 2 O 3 addition in NaAlO 2 electrolyte on microstructure, adhesive strength, isothermal oxidation behavior and tribological properties of PEO coatings at elevated temperatures was investigated by means of X-ray diffraction, scanning electron microscopy, the pull-off method, isothermal oxidation tests as well as ball-on-disc friction and wear tests. The introduction of Al 2 O 3 into the basic electrolyte promotes the formation of Al 2 TiO 5 phase in the PEO coatings. Isothermal oxidation tests at 800 °C up to 150 h showed that PEO coatings with Al 2 O 3 addition exhibit better oxidation resistance than those formed in the basic electrolyte. The PEO coating formed in the electrolyte with 4 g L−1 Al 2 O 3 additive exhibits the least mass gain of only 1.33 mg cm−2. The micro-hardness of the PEO coatings prepared with Al 2 O 3 additive is improved due to the presence of Al 2 TiO 5 phase, however, the adhesive strength of PEO coating is slightly weakened due to the formation of defects inside ceramic coating. The wear resistance of Ti 2 AlNb alloy is improved significantly by PEO coatings at room temperature due to high hardness and porous surface morphology. The friction coefficient and wear rate of the PEO coatings prepared with Al 2 O 3 addition is comparable to those formed in the basic electrolyte at both room temperature and 600 °C. • Al 2 O 3 additive was used to prepare PEO coatings and the influences were discussed. • Coatings with Al 2 O 3 additive exhibit better high temperature oxidation resistance. • Wear resistance of Ti 2 AlNb alloy is improved by PEO coatings at room temperature. [ABSTRACT FROM AUTHOR]

This work concerns the microstructure-mechanical properties relationship in Al 2 O 3 /SmAlO 3 composites prepared by hot pressing at temperatures from 1450 °C to 1650 °C. Dense samples have been prepared using co-precipitated trigonal α -Al 2 O 3 and orthorhombic SmAlO 3 at the pseudo-binary eutectic composition. The overall microstructure coarsens with increasing processing temperature, but the nanoscale precipitates within α -Al 2 O 3 and SmAlO 3 grains contribute to coherency strains and distortions in Al 2 O 3 /SmAlO 3 prepared at 1650 °C. The intragranular SmAlO 3 precipitates in Al 2 O 3 grains exhibit semi-coherent interface and an orientation relationship of the intragranular phase SmAlO 3 and alumina matrix close to two different zone axes, namely [ 2 3 ¯ 1 ] SmAlO 3 and [ 4 ¯ 401 ] Al 2 O 3 . Consequently, significant strengthening effect is found from the measured hardness values on the sample sintered at 1650 °C. The measured flexural strength and single edged notched beam fracture toughness of the Al 2 O 3 /SmAlO 3 ceramic are comparable to traditional secondary phases reinforced alumina composites. The sample sintered at 1500 °C exhibits a flexural strength of 558 MPa and a fracture toughness of 5.59 MPa⋅m1/2. [ABSTRACT FROM AUTHOR]

Abstract Gas burst has been commonly observed during reactive sintering, especially when combustion was initialized therein. In this study, a model system (Zr + 2B = ZrB 2) was chosen to investigate this phenomenon by a combination of thermo-analysis, mass spectrum investigation and electron microscopy studies. Results showed the combustion lead to a formation of various gaseous byproducts such as CO, CO 2 , N 2 , BO, BO 2 and B 2 O 3 etc. Especially for BO(g), its generation consumed boron in the raw materials, resulting in the residual Zr-containing phase that accelerated the formation of interlocked ZrB 2 grains in the sintered ceramics, which show relatively high strength (516 ± 42 MPa). Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract This present work explores initially the feasibility of producing in-situ surface nanoeutectic Al 2 O 3 -ZrO 2 (Y 2 O 3) (SNAZ) ceramics via the oxyacetylene flame remelting (OAFR) process. Singular cellular nanoeutectics consist of nanoscale lamellae, which prevail in the samples formed under different irradiation times. Ultrafine nanoeutectics are achieved by prolonging the irradiation time, and their formation mechanisms associated with eutectic refinement are proposed to obtain a better understanding on the melt thermal history and microstructural inheritance. The enhanced nucleation undercooling is the essential mechanism associated with the microstructural refinement. SNAZ formed by the OAFR-based rapid solidification seem to offer an inexpensive route to realize in-situ microstructure tailoring or surface shaping. [ABSTRACT FROM AUTHOR]

A highly wrinkled and textured Al2O3‐ZrO2 nanoeutectic induced by oxy‐acetylene flame remelting was elaborated for the first time from the perspective of morphological evolution and formation mechanism. The rapidly solidified Al2O3‐ZrO2 ceramic exhibits a wrinkled cellular nanoeutectic structure with a minimum interphase spacing of 0.12 μm. The Jackson‐Hunt (JH) eutectic theory is more appropriate to predict the growth of Al2O3‐ZrO2 nanoeutectic induced by oxy‐acetylene flame remelting than the Trivedi‐Magnin‐Kurz (TMK) model. The bulk growth rate of 7.8 μm3/s is close to the theoretically predicted value of 11.0 μm3/s by the JH model. The eutectic growth rates of Al2O3‐ZrO2 with average interphase spacings of 0.12 and 0.3 μm are estimated to be 763.8 and 122.2 μm/s, respectively. Especially, a mesoscopic insight into formation mechanism of the wrinkled and textured eutectic was proposed from a three‐dimensional perspective based on both the crystal growth orientation and the airflow effect. The formation mechanism and epitaxial growth behavior of a novel wrinkled and textured Al2O3‐ZrO2 nanoeutectic. [ABSTRACT FROM AUTHOR]

Abstract: This present work concentrated on a novel one‐step pulse discharge plasma melting method, directly from a powder mixture of nano‐sized Al2O3–ZrO2(Y2O3) to in situ fabricate Al2O3–ZrO2 binary eutectic in a short processing time. A continuous transition from submicro‐sized polycrystalline to non‐equilibrium eutectic was traced based on pulse discharge plasma semisolid to liquid processing. The uniform colony microstructure with an average inter‐lamellar or inter‐rod spacing of ~200 nm was obtained at a growth rate of ~275 μm/s, and the inter‐lamellar or inter‐rod spacing was a good fit for the inverse‐square‐root dependence of the growth rate as λa = 3.32 × v−1/2. [ABSTRACT FROM AUTHOR]

The present work concentrated on a novel one-step pulse discharge plasma melting method for in situ fabricating Al 2 O 3 -ZrO 2 binary eutectic in a short processing time. Al 2 O 3 -ZrO 2 eutectic exhibited well-aligned fibrous and colonial structure with a minimum lamellar spacing of ∼250 nm at the growth rate of ∼176.0 μm/s. The lamellar spacing was well consistent with the inverse-square-root dependence on the growth rate as λ = 2.90 × v − 1 / 2 , and the constant of proportionality of 2.90 was close to 3.32 predicted by the JH eutectic theory. The formation mechanism of Al 2 O 3 -ZrO 2 eutectic on primary faceted-alumina crystals was also proposed. The Al 2 O 3 -ZrO 2 eutectic originated from the faceted Al 2 O 3 primary crystals, which played the leading role in the coupled growth process. The interfacial fracture behavior across the coarse intercolony regions was explored, and the fracture toughness of Al 2 O 3 -ZrO 2 eutectic ceramics was comparable to those achieved by traditional directional solidification. [ABSTRACT FROM AUTHOR]

Plasma electrolytic oxidation (PEO) ceramic coatings were formed on Ti2AlNb alloy in various NaAlO2 electrolytes containing 2 g L−1, 4 g L−1, and 6 g −1 Na2CrO4 additive, respectively. The influence of Na2CrO4 additive in NaAlO2 electrolyte on structure and high-temperature oxidation behavior at 800 °C was investigated. The Na2CrO4 additive in the NaAlO2 electrolyte not only promotes the formation of γ-Al2O3 phase and densification of ceramic coatings, but also participates directly in the growth of ceramic coating to form new Cr3O and (Al0.948Cr0.052)2O3 phases. The PEO ceramic coatings formed in NaAlO2 electrolytes with 2 g L−1 and 4 g L−1 Na2CrO4 additive show better oxidation resistance than those PEO coatings formed in a NaAlO2 basic electrolyte based on isothermal oxidation tests at 800 °C up to 150 h. A thin and uniform isothermally oxidized layer is formed in the interlayer adjacent the substrate, which protects the substrate from the inward diffusion of oxygen and the outward diffusion of metallic elements. The PEO ceramic coatings formed in NaAlO2 electrolyte with 4 g L−1 Na2CrO4 additive exhibit the least mass gain among all the specimens, which is only a half of the ceramic coating formed in a NaAlO2 basic electrolyte without any Na2CrO4 additive. [ABSTRACT FROM AUTHOR]

In the present work, Al 2 O 3 -GdAlO 3 oxide nanopowders with eutectic composition of 77:23 (in molar ratio) were prepared via a chemical co-precipitation method. α-SiC particles were then incorporated with different volume fractions of 10, 15 and 20 vol% into the oxide powders. Al 2 O 3 -GdAlO 3 –SiC ceramics were hot-pressed at different sintering temperatures to obtain fully densified bulk ceramics. The as-sintered composites consist mainly of α-Al 2 O 3 , GdAlO 3 and α-SiC phases, and exhibit a dense and uniform microstructure. The GdAlO 3 grains are entangled with α-Al 2 O 3 grains as indicated by SEM observations. SiC nanoparticles are found within the interior of both α-Al 2 O 3 and GdAlO 3 grains or at the interfaces between entangled α-Al 2 O 3 and GdAlO 3 . With increasing the SiC content from 10 to 20 vol%, the high-temperature flexural strength of Al 2 O 3 -GdAlO 3 -SiC ceramics increases from 567 to 616 MPa, and the Vickers hardness increases from 17.5 to 19.5 GPa, while the fracture toughness of Al 2 O 3 -GdAlO 3 -SiC ceramics increases from 8.20 to 9.28 MPa m 1/2 , which is significantly improved with respect to that (7.5 MPa m 1/2 ) of unmodified Al 2 O 3 -GdAlO 3 ceramic. The toughening mechanisms of Al 2 O 3 -GdAlO 3 -SiC ceramics are attributed to crack deflection, pinning and bridging, and bifurcation due to the presence of SiC nanophases observed from the indentation. [ABSTRACT FROM AUTHOR]

An efficient and flexible chemical co-precipitation method has been used to synthesize nanoscale Al 2 O 3 -GdAlO 3 powders with eutectic composition. The as-synthesized powders exhibit a highly dispersive and homogeneous distribution with an average particle size of 50 nm. The phase transition in the resulting powders strongly depends upon the calcination temperature. GdAlO 3 undergoes complete crystallization after calcination at 1050 °C, however, the diffraction peaks of α-Al 2 O 3 are found at a relatively high calcination temperature of at least 1300 °C. The fully-densified Al 2 O 3 -GdAlO 3 ceramic with eutectic composition obtained by hot pressing the nanoscale powders at 1500 °C exhibits a room temperature flexural strength of 556 MPa, a Vickers hardness of 17.3 GPa and a fracture toughness of 7.5 MPa m 1/2 . The high temperature flexural strength of the as-sintered Al 2 O 3 -GdAlO 3 ceramic is measured to be 515 MPa after bending tests at 1000 °C. [ABSTRACT FROM AUTHOR]

The recognition of natural hybridization can help to understand the origin and maintenance of biodiversity. Based on intermediate morphology and overlapped distribution, Torreya grandis var. jiulongshanensis Z. Y. Li, Z. C. Tang & N. Kang was regarded as a putative natural hybrid between T. jackii Chun and T. grandis Fort. ex Lindl. in southeast China. This study tested the hybridization origin of T. grandis var. jiulongshanensis using nuclear internal transcribed spacer (ITS) and cytoplasm (chloroplast rbcL and rpl16 and mitochondrial rps3) DNA sequences. The results showed that most heterozygous sites of nuclear ITS sequences in T. grandis var. jiulongshanensis showed additivity between T. jackii and T. grandis. Cloned ITS sequences of T. grandis var. jiulongshanensis separately clustered with T. jackii and T. grandis in the phylogenetic analyses. Meanwhile, all of chloroplast and mitochondrial haplotypes of T. grandis var. jiulongshanensis were identical to those of T. jackii, not T. grandis. On the chloroplast DNA phylogenetic trees, T. grandis var. jiulongshanensis were grouped into the clade of T. jackii. These results suggest that T. grandis var. jiulongshanensis is a natural hybrid between T. jackii (maternal parent) and T. grandis (paternal parent). This study also implies that T. grandis should be cultivated with caution near the sites of T. jackii, because the endangered status of the latter might be deteriorated due to hybridization. [ABSTRACT FROM AUTHOR]

The single-phase (Ti 0.2 V 0.2 Nb 0.2 Ta 0.2 Mo 0.2)(C 0.9 N 0.1) high-entropy carbonitride powder with an average particle size of 203 nm and a low oxygen content of 0.2915 wt% was synthesized by the carbothermal reduction-nitridation method at 1600 °C for 4 h. Subsequently, (Ti,V,Nb,Ta,Mo)(C,N) high-entropy carbonitride ceramics were prepared by hot pressing at temperatures of 1600 °C to 1900 °C. Increasing the sintering temperature is conducive to the uniform distribution of metallic elements, however, the hardness of high-entropy carbonitride ceramics is also reduced. (Ti,V,Nb,Ta,Mo)(C,N) ceramic hot-pressed at 1600 °C for 1 h has a relative density of 99.8%, an average grain size of 0.37 ± 0.08 µm, nanoindentation hardness of 32.4 ± 0.9 GPa, Vickers' hardness of 24.0 ± 0.7 GPa at 9.8 N and fracture toughness of 4.87 ± 0.25 MPa·m1/2, which is comparable to those of high-entropy carbides and nitrides. In this study, a novel and convenient method for the preparation of (Ti,V,Nb,Ta,Mo)(C,N) high-entropy carbonitride ceramics was established. • High-entropy carbonitride powders with fine particle size can be synthesized by carbothermal reduction-nitridation method. • The carbon content in the raw powder mixture will affect the single-phase formation ability. • High-performance high-entropy carbonitride ceramics can be prepared from high-entropy carbonitride powders. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mechanism of phase transition from X2-RE 2 SiO 5 to apatite is revealed. • The formation of apatite in corroded Y 2 SiO 5 is inhibited by introducing Yb. • Silica-rich grain boundary is considered to reduce the corrosion degree. Environmental barrier coatings (EBCs) are usually coated on SiC ceramic or ceramic matrix composites (CMCs), in order to prevent the attack from corrosive media like water vapor and molten oxides. Solid-solutionizing strategy containing high-entropy engineering is considered as an effective way to mediate corrosion resistances of rare-earth silicates, which are promising candidates for the topcoats of EBCs. In this work, high-temperature corrosion behaviors of hot-pressed (Y 1− x Yb x) 2 SiO 5 ceramics have been investigated in a 50 %H 2 O–50 %O 2 environment at temperatures of 1573/1673/1773 K for 100 h. The main corrosion product of Y 2 SiO 5 is apatite phase, whose formation can be distinctly inhibited by introducing Yb. Consequently, introducing Yb avoids the tensile stress and cracks effectively, which are induced by the volume reduction due to the phase transition to apatite at elevated temperatures. The inhibition of apatite formation by introducing Yb is attributed to the relatively lower volatilization pressure of Yb 2 O 3 than Y 2 O 3 and the smaller cationic radius of Yb3+ than Y3+. Meanwhile, the composition deviations between grain boundary and grain surface results in the grain surface corrosion and ridge-like corrosion characteristics. [ABSTRACT FROM AUTHOR]

Eighteen different 5-component equimolar rare earth zirconates were successfully synthesized by solid state reaction method. Among them, 5 of them exhibit a high-entropy fluorite structure, 8 have a high-entropy pyrochlore structure, and the remaining 5 have dual-phase structures of both pyrochlore and fluorite. For high-entropy rare earth zirconates with single-phase structure, the lattice parameter is almost linearly correlated with the average cation radius ratio. In combination with a large number of previous reports, a summary is made to study the synergistic effects of the average cation radius ratio, configuration entropy and size disorder on the single-phase formation ability of multi-component rare earth zirconates. The conclusion verifies that the size disorder of about 5% is the boundary for the multi-component rare earth zirconates to form a single-phase or dual-phase region, while the average cation radius ratio of 1.467 is the demarcation between a pyrochlore and a defective fluorite structure in the single-phase zone, and the configuration entropy had less effect. Excessive size disorder leads to the enrichment or barrenness of certain components, which is the main reason for the formation of dual phase ceramics. • 18 Different equimolar 5-component rare earth zirconates have been prepared. • The size disorder (δ *) can predict the single-phase formation ability of zirconates. • δ * = 5% is the boundary between the single- and dual-phase rare earth zirconates. • The single-phase forming ability of rare-earth zirconates is independent of entropy. [ABSTRACT FROM AUTHOR]

Crack-healing behavior and strength recovery of ZrO 2 (Y 2 O 3 )–Al 2 O 3 –MoSi 2 (TZ3Y20A–MoSi 2 ) ceramics have been investigated. Heat treatment in air enhances distinctly the flexural strength of TZ3Y20A–MoSi 2 ceramics. Si–O oxide and ZrSiO 4 are found after heat treatment, in which the former heals the cracks and recovers the strength, however, the latter is one kind of brittle materials that reduces mechanical performance of ceramics. The TZ3Y20A–10 vol% MoSi 2 ceramic has a complete crack-healing effect and strength recovery by suitable heat treatment at 1373 K for 3 h in air, however, the strength does not recover completely under other heat treatment conditions. With further increasing the MoSi 2 contents to 20 vol%, the flexural strength of as heat-treated TZ3Y20A–MoSi 2 ceramics is higher than that of pre-cracked specimens, but remains lower than that of smooth specimens. Crack closure and rebonding of the crack walls are due to the formation of Si–O glassy phase by oxidation reaction. [ABSTRACT FROM AUTHOR]

In this work, CMAS corrosion behavior of hot-pressed (Y 1- x Yb x) 2 SiO 5 ceramics at 1573 K within 32 h has been investigated. The corrosion products contain non-stoichiometric apatite and garnet, which form according to the dissolution-reprecipitation mechanism. With abundant calcia-magnesia-aluminosilicate, the growth rate of apatite layer increases rapidly with prolonging corrosion time, which results in the rapid corrosion especially after 4 h. Furthermore, the measured thickness of apatite layer in (Y 1- x Yb x) 2 SiO 5 is much lower than the predicted value based on the optical basicity (OB) theory. This work provides a new insight of solid-solutionizing strategy in the resistance of rare-earth monosilicate to CMAS corrosion. • The producing conditions of two different CMAS corrosion products are revealed. • The variation on the growth rate of apatite layer over corrosion time is discussed. • The apatite layer thickness is smaller than the predicted value based on OB theory. [ABSTRACT FROM AUTHOR]