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Melt growth ceramics (MGC) is a new type of ceramic material with microstructure obtained by melting and solidification of raw materials. The clean and high-strength bonding interface shared by atoms makes it have excellent high-temperature mechanical properties and microstructure stability close to the melting point. It shows great application potential in the field of high thrust weight ratio aero-engine and heavy gas turbine hot end components in the future. Laser directed energy deposition (LDED) technology can effectively overcome the limitations of traditional preparation methods of MGC in terms of cycle, energy consumption and structural complexity. It provides a new solution for direct additive manufacturing of MGC components, and has become a research hotspot at home and abroad. Based on the introduction of the process principle of LDED technology, the microstructure characteristics and properties of different MGCs prepared by this technology at home and abroad were summarized in this paper, and the main research on the control of microstructure and cracking behaviour was comprehensively discussed. Based on the existing research progress, the development trend and key scientific problems to be further solved in this field were discussed. It was pointed out that inhibiting cracking and improving microstructure and properties are the primary problems faced at present. The development of materials and new processes is the key to breaking through the existing bottleneck and promote the development and application of MGC-LDED.

Epiphytism is an example of an obligate interspecific interaction between plants, where a plant species grows on another plant species for physical support. In epiphytic orchids that rely on suitable host tree species (phorophytes) and mycorrhizal fungi for germination and growth, a distinct preference has been observed for particular host tree species. However, the factors driving this host preference remain unclear.In this study, we investigated whether mycorrhizal fungi that promote seedling development determine the preference of phorophytes in the epiphytic orchid Dendrobium wangliangii. First, we identified the preferred host tree species for this orchid. Next, in vitro and in situ germination experiments were conducted to identify potential fungi that promote seed germination. Finally, high‐throughput sequencing was used to assess the distribution of these fungi on both colonized host trees and potential host trees, including individual trees of the host species not yet colonized by the orchid and trees of another species growing in the vicinity of a colonized tree.Dendrobium wangliangii exhibited a preference for trees within the Fagaceae family. Two Fusarium species from the bark of host trees were identified as the primary fungi that promote seed germination. Successful protocorm formation and seedling development were observed exclusively on preferred phorophytes. Fungal community analyses further indicated that both Fusarium spp. occurred on all potential host trees, suggesting that the host preference of this epiphytic orchid is not constrained by the distribution of suitable mycorrhizal fungi.Synthesis: Regarding the epiphytes that depend on mycorrhizal fungi for successful seedling recruitment, we conclude that strong epiphyte–phorophyte associations do not arise from the limited distribution of mycorrhizal fungi but are more likely the result of other factors inherent in the phorophyte environment. [ABSTRACT FROM AUTHOR]

Diterpenoid alkaloids (DAs) have been often utilized in clinical practice due to their analgesic and anti‐inflammatory properties. Natural DAs are prevalent in the family Ranunculaceae, notably in the Aconitum genus. Nevertheless, the evolutionary origin of the biosynthesis pathway responsible for DA production remains unknown. In this study, we successfully assembled a high‐quality, pseudochromosome‐level genome of the DA‐rich species Aconitum vilmorinianum (A. vilmorinianum) (5.76 Gb). An A. vilmorinianum‐specific whole‐genome duplication event was discovered using comparative genomic analysis, which may aid in the evolution of the DA biosynthesis pathway. We identified several genes involved in DA biosynthesis via integrated genomic, transcriptomic, and metabolomic analyses. These genes included enzymes encoding target ent‐kaurene oxidases and aminotransferases, which facilitated the activation of diterpenes and insertion of nitrogen atoms into diterpene skeletons, thereby mediating the transformation of diterpenes into DAs. The divergence periods of these genes in A. vilmorinianum were further assessed, and it was shown that two major types of genes were involved in the establishment of the DA biosynthesis pathway. Our integrated analysis offers fresh insights into the evolutionary origin of DAs in A. vilmorinianum as well as suggestions for engineering the biosynthetic pathways to obtain desired DAs. [ABSTRACT FROM AUTHOR]

Directed laser deposition (DLD) is a new method for rapidly preparing melt‐grown ceramics, but cracking problem greatly limited its application. In this study, cracking behavior of Al2O3 ceramics was suppressed by doping ZrO2. Crack suppression mechanism of ZrO2 doping in melt‐grown ceramics was also analyzed. Process parameters which are prone to generating cracks were adopted in the experiments, and they contribute to showing the crack clearly. Results show that ZrO2 doping has remarkable crack suppression effects. It is most obvious when ZrO2 content is 37 mol%. Compared with those of pure Al2O3 ceramics, crack density reduces by 43.2%, and the number of longitudinal main cracks reduces by 63.2%. Doping of ZrO2 forms dense composite microstructure with primary α‐Al2O3 grains discretely distributing in eutectic continuous matrix. Therefore, initial crack sources are effectively reduced. Morphology of primary Al2O3 grains transforms from cellular to dendritic, which changes crack propagation mode from inter‐granular to trans‐granular. Mismatch of thermo‐physical properties of different phase promotes the arrest, deflection, and bridging phenomena in crack propagation, contributing to crack suppression. On the basis of ZrO2 doping, we have realized the preparation of crack‐free eutectic ceramic (37 mol%ZrO2) samples through further process optimization. The maximum size of the sample reaches 230 mm. [ABSTRACT FROM AUTHOR]