Towards high-throughput microstructure simulation in compositionally complex alloys via machine learning

The coupling of computational thermodynamics and kinetics has been the central research theme in Integrated Computational Material Engineering (ICME). Two major bottlenecks in implementing this coupling and performing efficient ICME-guided high-throughput multi-component industrial alloys discovery or process parameters optimization, are slow responses in kinetic calculations to a given set of compositions and processing conditions and the quality of a large amount of calculated thermodynamic data. Here, we employ machine learning techniques to eliminate them, including (1) intelligent corrupt data detection and re-interpolation (i.e. data purge/cleaning) to a big tabulated thermodynamic dataset based on an unsupervised learning algorithm and (2) parameterization via artificial neural networks of the purged big thermodynamic dataset into a non-linear equation consisting of base functions and parameterization coefficients. The two techniques enable the efficient linkage of high-quality data with a previously developed microstructure model. This proposed approach not only improves the model performance by eliminating the interference of the corrupt data and stability due to the boundedness and continuity of the obtained non-linear equation but also dramatically reduces the running time and demand for computer physical memory simultaneously. The high computational robustness, efficiency, and accuracy, which are prerequisites for high-throughput computing, are verified by a series of case studies on multi-component aluminum, steel, and high-entropy alloys. The proposed data purge and parameterization methods are expected to apply to various microstructure simulation approaches or to bridging the multi-scale simulation where handling a large amount of input data is required. It is concluded that machine learning is a valuable tool in fueling the development of ICME and high throughput materials simulations.publishedVersio

Kagome surface states and weak electronic correlation in vanadium-kagome metals

RV6Sn6 (R = Y and lanthanides) with two-dimensional vanadium-kagome surface states is an ideal platform to investigate kagome physics and manipulate the kagome features to realize novel phenomena. Utilizing the micron-scale spatially resolved angle-resolved photoemission spectroscopy and first-principles calculations, we report a systematical study of the electronic structures of RV6Sn6 (R = Gd, Tb, and Lu) on the two cleaved surfaces, i.e., the V- and RSn1-terminated (001) surfaces. The calculated bands without any renormalization match well with the main ARPES dispersive features, indicating the weak electronic correlation in this system. We observe 'W'-like kagome surface states around the Brillouin zone corners showing R-element-dependent intensities, which is probably due to various coupling strengths between V and RSn1 layers. Our finding suggests an avenue for tuning electronic states by interlayer coupling based on two-dimensional kagome lattices

A colorimetric method for point mutation detection using high-fidelity DNA ligase

The present study reported proof-of-principle for a genotyping assay approach that can detect single nucleotide polymorphisms (SNPs) through the gold nanoparticle assembly and the ligase reaction. By incorporating the high-fidelity DNA ligase (Tth DNA ligase) into the allele-specific ligation-based gold nanoparticle assembly, this assay provided a convenient yet powerful colorimetric detection that enabled a straightforward single-base discrimination without the need of precise temperature control. Additionally, the ligase reaction can be performed at a relatively high temperature, which offers the benefit for mitigating the non-specific assembly of gold nanoparticles induced by interfering DNA strands. The assay could be implemented via three steps: a hybridization reaction that allowed two gold nanoparticle-tagged probes to hybrid with the target DNA strand, a ligase reaction that generates the ligation between perfectly matched probes while no ligation occurred between mismatched ones and a thermal treatment at a relatively high temperature that discriminate the ligation of probes. When the reaction mixture was heated to denature the formed duplex, the purple color of the perfect-match solution would not revert to red, while the mismatch gave a red color as the assembled gold nanoparticles disparted. The present approach has been demonstrated with the identification of a single-base mutation in codon 12 of a K-ras oncogene that is of significant value for colorectal cancers diagnosis, and the wild-type and mutant type were successfully scored. To our knowledge, this was the first report concerning SNP detection based on the ligase reaction and the gold nanoparticle assembly. Owing to its ease of operation and high specificity, it was expected that the proposed procedure might hold great promise in practical clinical diagnosis of gene-mutant diseases

Observation of electronic nematicity driven by three-dimensional charge density wave in kagome lattice KV3_3Sb5_5

Kagome superconductors AV$_3$Sb$_5$ (A = K, Rb, Cs) provide a fertile playground for studying various intriguing phenomena such as non-trivial band topology, superconductivity, giant anomalous Hall effect, and charge density wave (CDW). Remarkably, the recent discovery of $C_2$ symmetric nematic phase prior to the superconducting state in AV$_3$Sb$_5$ has drawn enormous attention, as the unusual superconductivity might inherit the symmetry of the nematic phase. Although many efforts have been devoted to resolve the charge orders using real-space microscopy and transport measurements, the direct evidence on the rotation symmetry breaking of the electronic structure in the CDW state from the reciprocal space is still rare. The underlying mechanism is still ambiguous. Here, utilizing the micron-scale spatially resolved angle-resolved photoemission spectroscopy, we observed the fingerprint of band folding in the CDW phase of KV$_3$Sb$_5$, which yet demonstrates the unconventional unidirectionality, and is indicative of the rotation symmetry breaking from $C_6$ to $C_2$. We then pinpointed that the interlayer coupling between adjacent planes with $\pi$-phase offset in the 2$\times$2$\times$2 CDW phase would lead to the preferred twofold symmetric electronic structure. Time-reversal symmetry is further broken at temperatures below $\sim$ 40 K as characterized by giant anomalous Hall effect triggered by weak magnetic fields. These rarely observed unidirectional back-folded bands with time-reversal symmetry breaking in KV$_3$Sb$_5$ may provide important insights into its peculiar charge order and superconductivity

Direct observation of topological surface states in the layered kagome lattice with broken time-reversal symmetry

Magnetic topological quantum materials display a diverse range of fascinating physical properties which arise from their intrinsic magnetism and the breaking of time-reversal symmetry. However, so far, few examples of intrinsic magnetic topological materials have been confirmed experimentally, which significantly hinder our comprehensive understanding of the abundant physical properties in this system. The kagome lattices, which host diversity of electronic structure signatures such as Dirac nodes, flat bands, and saddle points, provide an alternative and promising platform for in-depth investigations into correlations and band topology. In this article, drawing inspiration from the stacking configuration of MnBi$_2$Te$_4$, we conceive and then synthesize a high-quality single crystal EuTi$_3$Bi$_4$, which is a unique natural heterostructure consisting of both topological kagome layers and magnetic interlayers. We investigate the electronic structure of EuTi$_3$Bi$_4$ and uncover distinct features of anisotropic multiple Van Hove singularitie (VHS) that might prevent Fermi surface nesting, leading to the absence of a charge density wave (CDW). In addition, we identify the topological nontrivial surface states that serve as connections between different saddle bands in the vicinity of the Fermi level. Combined with calculations, we establish that, the effective time-reversal symmetry S=$\theta$$\tau_{1/2}$ play a crucial role in the antiferromagnetic ground state of EuTi$_3$Bi$_4$, which ensures the stability of the topological surface states and gives rise to their intriguing topological nature. Therefore, EuTi$_3$Bi$_4$ offers the rare opportunity to investigate correlated topological states in magnetic kagome materials.Comment: 9 pages, 4 figure

Characterization of coal fines generation: a micro-scale investigation

Coal fines are commonly generated as by-product during coalbed methane production mainly due to the interaction of coal with inseam water flow. A portion of the created coal fines may settle and plug the coal cleats and hydraulic fractures due to the gravity and coal pore size constraint. This could result in the reduction of coal permeability and blockage of coalbed methane wells or gas drainage boreholes. Despite the increasing awareness of the importance of understanding coal fines, limited research has been carried out on the characterization of coal fines creation. This study aimed to numerically characterize the generation process of coal fines in micro-scale coal cleats. The Scanning Electron Microscopy (SEM) images for a coal sample from Bulli Seam of the Sydney Basin in Australia were obtained and analysed to determine the actual cleat geometries and the characteristics of coal fines distribution. Then a fully coupled fluid-structure numerical model was developed to identify the creation process of coal fines at micro-scale. The impact of pertinent production conditions on coal fines generation was studied, including production pressure drawdown, temperature, coal fines Young's modulus and strength. The SEM images revealed that the particle size distributions of the coal fines in the examined cleats were in the order of hundreds of nanometres to several microns. The results of the numerical studies showed the coal fines production increased with pressure build-up, and decreased with increasing coal fines strength with more sensitivity compared with pressure. Critical values for production pressure drawdown were obtained, above which failure area began to expand; threshold values were also determined, below which remarkable reduction of coal fines production was achieved. Coal cleat geometry plays an important role in determining coal fines production. It was noted that exposed microstructures, cleat elbow regions and micro-fracture tips are more likely to generate coal fines. Based on these findings, guidance can be provided on the control of production conditions to mitigate coal fines issue, and new insight into where and how coal fines are created by inseam water flow can be achieved. (C) 2015 Elsevier B.V. All rights reserved

Shape Memory Polyurethane with Porous Architectures for Potential Applications in Intracranial Aneurysm Treatment

Conventional endovascular embolization of intracranial (or brain) aneurysms using helical detachable platinum coils can be time-consuming and occasionally requires retreatment due to incomplete coil packing. These shortcomings create a need for new biomedical devices and methods of achieving brain aneurysm occlusion. This paper presents a biocompatible and highly porous shape memory polymer (SMP) material with potential applications in the development of novel endovascular devices for treating complex intracranial aneurysms. The novel highly porous polyurethane SMP is synthesized as an open cell foam material with a glass transition temperature (Tg) of 39 °C using a sugar particle leaching method. Once heated above the Tg, the compressed SMP foam is able to quickly return to its original shape. An electrical resistance heating method is also employed to demonstrate a potential triggering design for the shape recovery process in future medical applications. The mechanical properties of the developed SMP foam are characterized at temperatures up to 10 °C above the respective Tg. The results from this work demonstrate that the porous SMP material developed in this study and the electrical resistance heating trigger mechanism provide a solid foundation for future design of biomedical devices to enhance the long-term therapeutic outcomes of endovascular intracranial aneurysm treatments.Open access fees fees for this article provided whole or in part by OU Libraries Open Access Fund.Ye

Comparison of the effects of rumen-protected and unprotected L-leucine on fermentation parameters, bacterial composition, and amino acids metabolism in in vitro rumen batch cultures

This study was conducted to compare the effects of rumen-protected (RP-Leu) and unprotected L-leucine (RU-Leu) on the fermentation parameters, bacterial composition, and amino acid metabolism in vitro rumen batch incubation. The 5.00 g RP-Leu or RU-Leu products were incubated in situ in the rumen of four beef cattle (Bos taurus) and removed after 0, 2, 4, 6, 12, 16, and 24 h to determine the rumen protection rate. In in vitro incubation, both RP-Leu and RU-Leu were supplemented 1.5 mmol/bottle (L-leucine HCl), and incubated after 0, 2, 4, 6, 8, 12, and 16 h to measure gas production (GP), nutrient degradability, fermentation parameters, bacterial composition, and amino acids metabolism. Results from both in vitro and in situ experiments confirmed that the rumen protection rate was greater (p < 0.01) in RP-Leu than in RU-Leu, whereas the latter was slow (p < 0.05) degraded within incubation 8 h. Free leucine from RP-Leu and RU-Leu reached a peak at incubation 6 h (p < 0.01). RU-Leu supplementation increased (p < 0.05) gas production, microbial crude protein, branched-chain AAs, propionate and branched-chain VFAs concentrations, and Shannon and Sobs index in comparison to the control and RP-Leu supplementation. RU-Leu and RP-Leu supplementation decreased (p < 0.05) the relative abundance of Bacteroidota, which Firmicutes increased (p < 0.05). Correlation analysis indicated that there are 5 bacteria at the genus level that may be positively correlated with MCP and propionate (p < 0.05). Based on the result, we found that RP-Leu was more stable than RU-Leu in rumen fluid, but RU-Leu also does not exhibit rapid degradation by ruminal microbes for a short time. The RU-Leu was more beneficial in terms of regulating rumen fermentation pattern, microbial crude protein synthesis, and branched-chain VFAs production than RP-Leu in vitro rumen conditions

The bracteatus pineapple genome and domestication of clonally propagated crops

Domestication of clonally propagated crops such as pineapple from South America was hypothesized to be a 'one-step operation'. We sequenced the genome of Ananas comosus var. bracteatus CB5 and assembled 513 Mb into 25 chromosomes with 29,412 genes. Comparison of the genomes of CB5, F153 and MD2 elucidated the genomic basis of fiber production, color formation, sugar accumulation and fruit maturation. We also resequenced 89 Ananas genomes. Cultivars 'Smooth Cayenne' and 'Queen' exhibited ancient and recent admixture, while 'Singapore Spanish' supported a one-step operation of domestication. We identified 25 selective sweeps, including a strong sweep containing a pair of tandemly duplicated bromelain inhibitors. Four candidate genes for self-incompatibility were linked in F153, but were not functional in self-compatible CB5. Our findings support the coexistence of sexual recombination and a one-step operation in the domestication of clonally propagated crops. This work guides the exploration of sexual and asexual domestication trajectories in other clonally propagated crops