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Powder bed fusion titanium alloys， as an important metallic material， are widely used in aerospace， medical devices and automotive industries.However， due to their unique material properties and processing methods， surface quality and performance remainone of key issues that constrain their application.In this paper， the research progress on surface polishing techniques for powder bed fusion titanium alloys was reviewed.The advancements in chemical polishing， electrochemical polishing， plasma electrolytic polishing， laser polishing and mechanical polishing were introduced.These techniques have provided options for achieving surface quality and performance that meet various application needs for powder bed fusion titanium alloys.Additionally， the development of composite polishing technologies and related advancements were also prospected.

To improve the quality of laser cladding， a finite element analysis process was established， focusing on laser power， scanning speed and powder feed rate as the main process parameters， aiming to reduce the research and development cycle and economic costs of optimizing cladding process parameters. By comparing the temperature and stress field simulation of GX4CrNi13-4 martensitic stainless steel laser cladding data with experimental results， the forming quality under different parameters is verified， optimizing the laser cladding process parameters. The results indicate that the adjustment range of laser power should be controlled between 1800 W to 2000 W to avoid substrate penetration and ensure sufficient density； increasing the powder feed rate effectively reduces temperature and residual stress. Among the three process parameters， laser power has the most significant impact on cladding quality. A comprehensive analysis of density and microhardness tests to assess the cladding quality and residual stress distribution under different parameters reveals that the optimal combination of process parameters is a laser power of 1800 W， scanning speed of 10 mm/s， powder feed rate of 10 g/min. The experimental results are consistent with the trends of stress field simulations， further validating the accuracy of the simulation data.

Using animate nouns to refer to entities in the world involves a complex interaction of ontology, cognition and language. The present study evaluates two accounts of the use of animate nouns, with Mandarin Chinese as the vehicle for testing between the competing accounts. One account was proposed by Cheng et al. (2008. How universal is the Universal Grinder? In Marjo van Koppen & Bert Botma (eds.), Linguistics in the Netherlands, 50–62. Amsterdam & Philadelphia: John Benjamins). These researchers contend that the count interpretation is basic for Mandarin animate nouns, due to a lexical blocking effect. To access the alternative, mass interpretation requires some kind of pragmatic coercion. A second account was proposed by Pelletier, based on English (1975. Non-Singular reference: Some preliminaries. Philosophia 5(4). 451–465; 2012. Lexical nouns are both +MASS and +COUNT, but they are neither +MASS nor + COUNT. In Diane Massam (ed.), Count and mass across languages, 9–26. Oxford: Oxford University Press). We extend this account to Mandarin animate nouns, proposing that they are encoded in the mental lexicon with both a count sense and a mass sense. To adjudicate between the accounts, we conducted four experiments that were designed to assess the interpretation assigned to animate nouns by Mandarin-speaking children and adults. The experimental conditions manipulated both the syntactic structures of the sentences and the non-linguistic contexts in which those sentences were presented. The experimental findings support our proposal that both mass and count interpretations of animate nouns are available to children and adults when sentences are presented in contexts that are congruent with these interpretations. The findings also suggest that syntactic structure is an even more critical factor in determining the interpretation that is assigned to animate nouns in Mandarin.

BackgroundLaser cladding, recognized for its cost-effectiveness and high efficiency, has become a focal point in the field of laser remanufacturing. GX4CrNi13-4 martensitic stainless steel produced by laser cladding is a widely used structural material in nuclear power plants.PurposeThis study aims to enhance the mechanical properties of GX4CrNi13-4 martensitic stainless steel, fabricated using laser cladding technology, through different heat treatments that cause microstructure modification.MethodsThe GX4CrNi13-4 stainless steel sample was prepared using laser cladding technology, and its heat treatment microstructure was studied in details. Firstly, thermal expansion experiments identified the onset temperature of austenitic phase transformation of sample at 620 °C, serving as a pivotal reference for developing heat treatment schemes. Two distinct heat treatment processes, i.e., solution treatment plus aging (STPA) at 1 050 °C for 1 h followed by a similar treatment at 550 °C for 4 h and single aging (SA) at 620 °C for 2 h, were applied to experiments. The effects of these treatments on the microstructure and mechanical performance of the cladding were comparatively analyzed by using X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize the post-treatment microstructure and phase distribution. Tensile tests at room temperature were performed on samples before and after heat treatment.ResultsExperimental results indicate that the as-cladded GX4CrNi13-4 stainless steel exhibits a dual-phase microstructure primarily comprising martensite and ferrite, with continuous network-like ferrite precipitated along martensitic boundaries, accompanied by a minor presence of residual austenite. Post STPA, the matrix still predominantly comprises martensite and ferrite, but the continuous network-like ferrite decomposes, and numerous micrometer-scale transgranular precipitates within the martensite are observed. This led to a slight improvement in plasticity but a significant decrease in strength. The SA treatment of the cladded samples, performed at the critical temperature for austenitic phase transformation, induces the formation of the reversed austenitic phase. This phase, during tensile deformation, triggers the transformation induced plasticity (TRIP) effect. Furthermore, the network-like ferrite precipitated along the martensite decomposes into a dispersed distribution post-SA. The combined effect of TRIP and ferrite decomposition notably enhances the plasticity of the laser-cladded GX4CrNi13-4 stainless steel while effectively maintaining its strength.ConclusionsThe use of austenitic phase transition temperature for aging in this study, coupled with the synergistic effect of reversed austenite TRIP and ferrite decomposition, successfully achieves a balanced strength-plasticity performance in laser-cladded GX4CrNi13-4 stainless steel. Appropriate heat treatment and microstructural control emerge as effective strategies to improve the comprehensive mechanical properties of materials.

The semantics of superordinate collectives (superordinates hereafter) such as English furniture are argued to be count or mass, or to allow both count and mass readings. When tested experimentally, however, it has repeatedly been reported that superordinates denote individuals in a wide range of typologically distinct languages, including Mandarin. A close examination of the experimental method and design commonly used in previous research suggests, however, that the attested individual-denoting reading might only be the preferred reading in neutral contexts rather than the only reading that superordinates allow. In the present study, using a Truth Value Judgment Task we investigate the interpretation of Mandarin superordinates by Mandarin-speaking adults and 4–6-year-old children. We found that bare superordinates can convey both individual-denoting and non-individual-denoting readings depending on specific contexts provided, but such contextual manipulation cannot override morphosyntax (the presence of an individual classifier that selects an individual-denoting reading only). Taken together, our experimental data indicate that both contextual and morphosyntactic information play an important role in the interpretation of Mandarin superordinates, but that they function in different ways. In a word, the present study contributes new data and opens new perspectives for further investigation in the interpretation of superordinates in Mandarin as well as in other languages.

The Asian citrus psyllid (ACP) is the main vector of Citrus Huanglongbing, the most damaging citrus disease, causing significant financial losses in the citrus industry. Global warming has expanded the habitat of this pest, allowing it to continue its northward migration to China. Population genetic information of ACP is fundamentally essential for species management. This study investigated the genetic diversity and population structure of Chinese ACP using the mitochondrial cytochrome oxidase subunit I gene by dataset comprised 721 sequences from 27 geographic sites in China. Low haplotype diversity (0.323 ± 0.022) and low nucleotide diversity (0.00071 ± 0.00007) were observed in the entire population, which may indicate recent founder events. Twenty-three haplotypes were identified and clustered into 2 haplogroups: haplogroup I and haplogroup II. Haplogroup II included only 2 unique haplotypes, which occurred exclusively in the Southwest China ACP population. Genetic differentiation analyses were also indicative of Southwest China population was significantly differentiated from the remaining populations. Demographic history analysis showed that ACP population in China has experienced demographic expansion. Our results provided a better understanding of the genetic distribution patterns and structures of ACP populations in China. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) is an outstanding additive manufacturing (AM) technology that can enable both complicated geometries and desired mechanical properties in high-value components. However, the process reliability and cost have been the obstacles to the extensive industrial adoptions of LPBF. This work aims to develop a powder recycling procedure to reduce production cost and minimize process uncertainties due to powder degradation. We used a recycle index (R) to reuse Ti-6Al-4V powder through 10 production cycles. Using this recycle index is more reasonable than simply replying on recycle numbers as it incorporates the powder usage history. A recycling procedure with simple virgin powder top-up can effectively mitigate powder degradation and maintain stable powder properties, chemical compositions, and tensile properties. The experimental finding points to a sustainable recycling strategy of Ti alloy powders with minimal material waste and without noticeable detriment to observed mechanical performance through LPBF production cycles. [ABSTRACT FROM AUTHOR]