Chemical short-range order (CSRO) in high entropy alloys (HEAs) has attracted interests recently and is believed to be capable for tuning their mechanical properties. However, the characterization of ...CSRO in HEAs through experimental methods remains challenging. In this work, a modified embedded-atom method interatomic potential with good accuracy for studying CSRO in HfNbTaTiZr alloy system was developed. By employing the potential, molecular dynamic/Monte Carlo simulation was performed to investigate the CSRO in HfNbTaZr HEA. The results indicated that Hf-Zr and Nb-Ta atom pairs were preferred in the BCC solid solution of HfNbTaZr, and a new type of CSRO with topological B2 order was predicted, which can help to understand the mechanical properties of HfNbTaZr HEA. It was also found that forming of CSRO was an incubation process for the precipitation in HfNbTaZr, implying the significance of CSRO on the phase stability or precipitation behavior of HEAs. The findings in the present work can help in understanding CSRO and establishing its relationship with precipitates in HEAs, and more topics related to CSRO and phase stability in HfNbTaTiZr alloy system can be further investigated by atomistic simulation.
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•A modified embedded-atom method potential for HfNbTaTiZr alloy system was developed.•Hf-Zr and Nb-Ta atom pairs were preferred in the BCC solid solution of HfNbTaZr.•A new type of CSRO with topological B2 order in HfNbTaZr was predicted.•Forming of CSRO was an incubation process for the precipitation in HfNbTaZr.
Convolutional neural networks (CNN) have led to a successful breakthrough for hyperspectral image classification (HSIC). Due to the intrinsic spatial-spectral specificities of a hyperspectral cube, ...feature extraction with 3-D convolution operation is a straightforward way for HSIC. However, the overwhelming features obtained from the original 3-D CNN network suffers from the overfitting and more training cost problem. To address this issue, in this article, a novel HSIC framework based on a simplified 2D-3D CNN is implemented by the cooperation between a 2-D CNN and a 3-D convolution layer. First, the 2-D convolution block aims to extract the spatial features abundantly involved spectral information as a training channel. Then, the 3-D CNN approach primarily concentrates on exploiting band co-relation data by using a reduced kernel. The proposed architecture achieves the spatial and spectral features simultaneously based on a joint 2D-3D pattern to achieve superior fused feature for the subsequent classification. Furthermore, a deconvolution layer intends to enhance the robustness of the deep features is utilized in the proposed CNN network. The results and analysis of extensive real HSIC experiments demonstrate that the proposed light-weighted 2D-3D CNN network can effectively extract refined features and improve the classification accuracy.
Learning analysis is one of the most important applications of machine learning. Many studies have proposed solutions to learning performance prediction using online learning data. Unlike the ...previous studies, this paper analyzes online learning environment and formalizes the problem of online learning prediction. Based on the formalization, a multi-feature based learning prediction model for SPOC is proposed, called SPOC-MFLP, which generalizes the prediction problem of SPOC learning including objective, constraints, system and algorithms. The proposed SPOC-MFLP could be extended for MOOC and other online learning forms. Principle components analysis is adopted to discover the correlations of students' online multi features, and linear regression and deep neural network are used to predict the learning performance. The predicted results include specific scores or segmented grades of the final exam of SPOC, as well as students' future specialized courses. Experimental data are collected from a SPOC in Chuzhou University for two years and the experimental results reveal that the proposed SPOC-MFLP performs well.
The variation of the lattice constant with alloying elements is an essential issue in alloy design. In the traditional single-based alloys, there is a tremendous database for predicting the lattice ...constant. However, the traditional database is not suitable to the emerging multi-principal components alloys referred as high entropy alloys. Here, a framework is proposed to describe the variation of lattice constants in high entropy alloys. Based on the quantitative measurement of the lattice constants of fourteen alloys, we constructed the lattice constant database for concentrated CoCrFeNi alloys. The discrepancy between binary alloys and high entropy alloys revealed the atomic chemical interactions.
Quantitative determination of the lattice constant in CoCrFeNi high entropy alloys. A model is proposed to describe the lattice constant in high entropy alloys. The coefficients in the model are obtained from the precise XRD measurements of designed CoCrFeNi alloys with different compositions. The results greatly derivate the traditional binary alloys. Display omitted
R2R3-MYB transcription factors (TFs) play important roles in plant growth and development, and response to biotic and abiotic stresses. However, their regulatory mechanisms in wound-induced ...anthocyanin biosynthesis in woody plants are largely unknown.
In this work, we report that expression of anthocyanin biosynthesis genes (ABGs) were activated by PdMYB118, a MYB TF encoding gene from Populus deltoids, and the activation of PdMYB118 was significantly enhanced by PdTT8, a bHLH protein, through its direct interaction with PdMYB118. PdMYB118 and some ABGs were evidently induced by wound induction and methyl jasmonate (MeJA) treatment. Overexpression of PdMYB118 promoted anthocyanin accumulation in transgenic poplar upon wound induction. Furthermore, a poplar JASMONATE ZIM-domain (JAZ) protein, PtrJAZ1, repressed the transcriptional function of PdMYB118/PdTT8 complex by binding to PdTT8, and wound stimulated the biosynthesis of jasmonic acid (JA) and the degradation of PtrJAZ1.
Based on these observations, we proposed that PtrJAZ1 degradation triggered the expression of ABGs, leading to increased biosynthesis of anthocyanins in the wounded leaves of transgenic poplar. Therefore, our findings not only illustrate the crucial role of PdMYB118 in wound-induced anthocyanin biosynthesis in poplar, but also provide a molecular basis for the genetic engineering of colorful tree species.
Multiple phytohormones, including auxin, ethylene, and cytokinin, play vital roles in regulating cell development in the root epidermis. However, their interactions in specific root hair cell ...developmental stages are largely unexplored. To bridge this gap, we employed genetic and pharmacological approaches as well as transcriptional analysis in order to dissect their distinct and overlapping roles in root hair initiation and elongation in Arabidopsis thaliana. Our results show that among auxin, ethylene, and cytokinin, only ethylene induces ectopic root hair cells in wild-type plants, implying a special role of ethylene in the hair initiation stage. In the subsequent elongation stage, however, auxin, ethylene, and cytokinin enhance root hair tip growth equally. Our data also suggest that the effect of cytokinin is independent from auxin and ethylene in this process. Exogenous cytokinin restores root hair elongation when the auxin and ethylene signal is defective, whereas auxin and ethylene also sustain elongation in the absence of the cytokinin signal. Notably, transcriptional analyses demonstrated that auxin, ethylene, and cytokinin regulate a similar set of root hair-specific genes. Together these analyses provide important clues regarding the mechanism of hormonal interactions and regulation in the formation of single-cell structures.
A type VI secretion system (T6SS) gene cluster has been reported in Acidovorax citrulli. Research on the activation conditions, functions, and the interactions between key elements in A. citrulli ...T6SS is lacking. Hcp (Hemolysin co-regulated protein) is both a structural protein and a secretion protein of T6SS, which makes it a special element. The aims of this study were to determine the role of Hcp and its activated conditions to reveal the functions of T6SS. In virulence and colonization assays of hcp deletion mutant strain Δhcp, tssm (type VI secretion system membrane subunit) deletion mutant strain Δtssm and double mutant ΔhcpΔtssm, population growth was affected but not virulence after injection of cotyledons and seed-to-seedling transmission on watermelon. The population growth of Δhcp and Δtssm were lower than A. citrulli wild type strain Aac5 of A. citrulli group II at early stage but higher at a later stage. Deletion of hcp also affected growth ability in different culture media, and the decline stage of Δhcp was delayed in KB medium. Biofilm formation ability of Δhcp, Δtssm and ΔhcpΔtssm was lower than Aac5 with competition by prey bacteria but higher in KB and M9-Fe3+ medium. Deletion of hcp reduced the competition and survival ability of Aac5. Based on the results of Western blotting and qRT-PCR analyses, Hcp is activated by cell density, competition, ferric irons, and the host plant. The expression levels of genes related to bacterial secretion systems, protein export, and several other pathways, were significantly changed in the Δhcp mutant compared to Aac5 when T6SS was activated at high cell density. Based on transcriptome data, we found that a few candidate effectors need further identification. The phenotypes, activated conditions and transcriptome data all supported the conclusion that although there is only one T6SS gene cluster present in the A. citrulli group II strain Aac5, it related to multiple biological processes, including colonization, growth ability, competition and biofilm formation.
•A marine oil spill risk mapping approach was constructed.•The marine oil spill risk system was composed by risk source and risk receptor.•Hazard directly proportional to risk factors state and ...predisposing factors.•Hazard is inversely proportional to control state.•Vulnerability directly proportional to exposure, inversely proportional to resilience.
Accidental marine oil spill pollution can result in severe environmental, ecological, economic and other consequences. This paper discussed the model of Marine Oil Spill Risk Mapping (MOSRM), which was constructed as follows: (1) proposing a marine oil spill risk system based on the typical marine oil spill pollution accidents and prevailing risk theories; (2) identifying suitable indexes that are supported by quantitative sub-indexes; (3) constructing the risk measuring models according to the actual interactions between the factors in the risk system; and (4) assessing marine oil spill risk on coastal city scale with GIS to map the overall risk. The case study of accidental marine oil spill pollution in the coastal area of Dalian, China was used to demonstrate the effectiveness of the model. The coastal areas of Dalian were divided into three zones with risk degrees of high, medium, and low. And detailed countermeasures were proposed for specific risk zones.
MADS-box transcription factors are vital regulators participating in plant growth and development process and the functions of most of them are still unknown. ANR1 was reported to play a key role in ...controlling lateral root development through nitrate signal in Arabidopsis. OsMADS25 is one of five ANR1-like genes in Oryza Sativa and belongs to the ANR1 clade. Here we have investigated the role of OsMADS25 in the plant's responses to external nitrate in Oryza Sativa. Our results showed that OsMADS25 protein was found in the nucleus as well as in the cytoplasm. Over-expression of OsMADS25 significantly promoted lateral and primary root growth as well as shoot growth in a nitrate-dependent manner in Arabidopsis. OsMADS25 overexpression in transgenic rice resulted in significantly increased primary root length, lateral root number, lateral root length and shoot fresh weight in the presence of nitrate. Down-regulation of OsMADS25 in transgenic rice exhibited significantly reduced shoot and root growth in the presence of nitrate. Furthermore, over-expression of OsMADS25 in transgenic rice promoted nitrate accumulation and significantly increased the expressions of nitrate transporter genes at high rates of nitrate supply while down-regulation of OsMADS25 produced the opposite effect. Taken together, our findings suggest that OsMADS25 is a positive regulator control lateral and primary root development in rice.
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