Study on ceramic photonic bandgap structure with three-dimensional diamond lattice

A novel process, which was based on powder injection molding, was investigated for the fabrication of ceramic photonic bandgap structure with three-dimensional diamond lattice. The SiO2-TiO2 ceramic powder was mixed with a water-soluble agent to produce slurry. The slurry was then injected into an epoxy mold with inverse diamond lattice, fabricated by the stereolitographic rapid prototyping process. To increase the density of the green compact, cold isostatic pressing was applied on the unit. Using thermal debinding, the water-soluble agent and the epoxy were extracted at 360 and 650 K, respectively. Sintering was immediately done at 950 K for 5 h and the desired three-dimensional ceramic structure was obtained. The calculated band diagram for this structure indicated the existence of an absolute photonic bandgap for all wave vectors. At 14.7-18.5 GHz, a complete band gap was located with a maximum attenuation of 30 dB at 17 GHz, when transmission was measured in the 〈100〉 direction between 10 and 20 GHz.

Data-driven design of Ni-based turbine disc superalloys to improve yield strength

Increasing the thrust-weight ratio of aeroengines requires development of high-strength and stable high-temperature materials. A data-driven design of Ni-based turbine disc superalloys is performed to improve the yield strength to reach the target. Through first-principles calculations determining the design superalloy system, the theoretical models and Calculation of Phase Diagram (CALPHAD) screening compositions, and machine learning extrapolating prediction, 14 compositions are selected from 2,865,039 composition combinations. Ni-17Cr-8Co-1Mo-1W-6Al-3Ti-1Nb-1Ta is selected to verify the design accuracy. Experimental tests prove that the designed alloy has trade-offs of microstructure with satisfying design targets, and then, the yield strength is higher in the designed alloy than in commercial superalloys, reaching 728 MPa at 850 ℃. A scheme for increasing the performance of the designed alloy is proposed by discussing the strengthening mechanisms, machine learning process, and alloying chemistry effect. The cross-scale data-driven design is regarded as an accurate and efficient way to design novel high-strength Ni-based turbine disc superalloys, whose significance is the obvious reduction of trial-and-error tests.

Improvement of a High Velocity Compaction Technique for Iron Powder

Water atomized pure iron powder was compacted by high velocity compaction （HVC） with and without upper relaxation assist （URA） device. The influence of URA device on green density, spring back, green strength and hardness was studied. Morphological characteristics of the samples were observed by scanning electron microscope （SEM）. Green strength of the samples was measured by computer controlled universal testing machine. The results show that as stroke length increases, the green density, green strength and hardness of the compacts increase gradually. At the identical stroke length, the green density of the compacts pressed with URA devise was 2% higher than the compacts pressed without URA device. The green strength and hardness of the compacts pressed with URA device were higher than the compacts pressed without URA device. Furthermore, the radial spring back of the compacts decreased gradually with the increment in stroke length, whilst that of compacts prepared with URA device was lower.

An infrastructure with user-centered presentation data model for integrated management of materials data and services

With scientific research in materials science becoming more data intensive and collaborative after the announcement of the Materials Genome Initiative,the need for modern data infrastructures that facilitate the sharing of materials data and analysis tools is compelling in the materials community.In this paper,we describe the challenges of developing such infrastructure and introduce an emerging architecture with high usability.We call this architecture the Materials Genome Engineering Databases(MGED).MGED provides cloud-hosted services with features to simplify the process of collecting datasets from diverse data providers,unify data representation forms with user-centered presentation data model,and accelerate data discovery with advanced search capabilities.MGED also provides a standard service management framework to enable finding and sharing of tools for analyzing and processing data.We describe MGED’s design,current status,and how MGED supports integrated management of shared data and services.

Effects of gibberellin priming on seedling emergence and transcripts involved in mesocotyl elongation in rice under deep direct-seeding conditions

Mesocotyl elongation is a key trait influencing seedling emergence and establishment in direct-seeding rice cultivation.The phytohormone gibberellin(GA)has positive effects on mesocotyl elongation in rice.However,the physiological and molecular basis underlying the regulation of mesocotyl elongation mediated by GA priming under deep-sowing conditions remains largely unclear.In the present study,we performed a physiological and comprehensive transcriptomic analysis of the function of GA priming in mesocotyl elongation and seedling emergence using a direct-seeding japonica rice cultivar ZH10 at a5-cm sowing depth.Physiological experiments indicated that GA priming significantly improved rice seedling emergence by increasing the activity of starch-metabolizing enzymes and compatible solute content to supply the energy essential for subsequent development.Transcriptomic analysis revealed 7074 differentially expressed genes(false discovery rate of<0.05,|log2(fold change)|of≥1)after GA priming.Furthermore,gene ontology(GO)and Kyoto encyclopedia of genes and genomes(KEGG)enrichment analyses revealed that genes associated with transcriptional regulation,plant hormone biosynthesis or signaling,and starch and sucrose metabolism were critical for GA-mediated promotion of rice mesocotyl elongation.Further analyses showed that the expression of the transcription factor(TF)genes(v-myb avian myeloblastosis viral oncogene homolog(MYB)alternative splicing 1(MYBAS1),phytochrome-interacting factors 1(PIF1),Oryza sativa teosinte branched 1/cycloidea/proliferating cell factor 5(Os TCP5),slender 1(SLN1),and mini zinc finger 1(MIF1)),plant hormone biosynthesis or signaling genes(brassinazole-resistant 1(BZR1),ent-kaurenoic acid oxidase-like(KAO),GRETCHEN HAGEN 3.2(GH3.2),and small auxin up RNA 36(SAUR36)),and starch and sucrose metabolism genes(α-amylases(AMY2 A and AMY1.4))was highly correlated with the mesocotyl elongation and deep-sowing tolerance response.These results enhance our understanding of how nutrient metabolism-related substances and genes regulate rice mesocotyl elongation.This may facilitate future studies on related genes and the development of novel rice varieties tolerant to deep sowing.