Synergistic Effects of La and Y on the Microstructure and Mechanical Properties of Cast Al-Si-Cu Alloys

The effects of La and Y on the microstructure and mechanical properties of cast Al-Si-Cu alloys were investigated by X-ray diffractometer (XRD), optical microscope (OM), and scanning electron microscope (SEM). The results indicated that the addition of La and Y had a great effect on the refinement of α-Al grains, the modification of eutectic Si phase, and the reduction of β-Al5FeSi length in Al-Si-Cu alloys. The A380 + 0.6 wt.% La/Y alloy exhibited the best microstructure and mechanical properties. The UTS and EI of the A380 + 0.6 wt.% La/Y alloy were 215.3 MPa and 5.1%, which were 22.9% and 37.8% higher than those of the matrix alloy, respectively. In addition, neither Al11La3 nor Al3Y generated by the addition of La and Y could not serve as the nucleation core of α-Al grains, so the grain refinement of α-Al originated from the growth limitation and constitutional supercooling. Since La and Y promote twinning generation and constitutional supercooling, the eutectic Si phase also changed from stripe-like to short fibrous or even granular and was significantly refined. Furthermore, thermodynamic calculations indicated that the Al11La3 phase was formed first and the Al3Y phase was generated on the Al11La3 phase

Vacuum Brazing Effect on the Interlayer Failure Behaviors of Elastic-Porous Sandwich Structure with Entangled Metallic Wire Mesh

Particular attention has been given to the complexity of the elastic-porous sandwich structure with entangled metallic wire mesh (EMWM), which is a novel rigid-flexible heterogeneous and symmetrical material. The orthogonal experiment design for vacuum brazing was adopted for sensitivity analysis of the key fabrication process on the performances of an EMWM sandwich structure. The shear behaviors of the sandwich structures with different vacuum brazing parameters (e.g., heating rate, brazing temperature, and holding time) were analyzed by mechanical experiments and an interfacial microstructure. The results indicated that the failure behavior of the sandwich structure could be divided into four stages in the mode-I experiment. In addition, the joint quality of the different vacuum brazing process could be shown by the mode-II experiment, and the failure behaviors involves three stages. Additionally, the failure behaviors of the sandwich structure were mainly associated with the deformation of the EMWM core and the strength of the brazing joint. In addition, the relationship between the joint strength and the shear performance of the sandwich structure was revealed through the interfacial microstructure. Furthermore, the importance of the optimized vacuum brazing parameters to fabricate the novel sandwich structure with the best joint performance was demonstrated in this work

Comparison of Dynamic Performance of an All-Metallic Vibration Isolator by Elliptic Method and Frequency Sweeping Method

A horizontally symmetric all-metallic vibration isolator (AM-VI) is proposed to further investigate the dynamic mechanical performance. The novel AM-VI was constructed by combining hat-shaped metal rubber and oblique springs, which were connected in parallel. The springs were arranged symmetrically relative to the support. The elliptic method and the frequency sweeping method were used to compare the dynamic stiffness and the loss factor of the AM-VI. The results demonstrated that the dynamic stiffness and the loss factor calculated by two distinct test methodologies were considerably different, indicating that the inertial force effect of the dynamic testing equipment should be taken into count when adopting the elliptic method. Furthermore, when the vibration isolation performance was evaluated by utilizing mechanical impedance and force transmissibility, the AM-VI achieved excellent vibration isolation performance within a broad frequency range

Characterization of GATA gene family in Vitis vinifera: genome-wide analysis, expression profiles, and involvement in light and phytohormone response

The plant GATA family is one of the most important transcription factors involved in light-responsive development, nitrogen metabolism, phytohormone signaling, and source/sink balance. However, the function of the GATA gene is less known in grape (Vitis vinifera L.). In this study, we comprehensively analyzed the GATA family in grape (V. vinifera L.), particularly the phylogenetic evolution, duplication patterns, conserved motifs, gene structures, cis-elements, tissue expression patterns, and predicted function of VvGATA genes in response to abiotic stress. The potential roles of VvGATA genes in berry development were also investigated. The GATA transcription factors displayed expression diversity among different grape organs and tissues, and some of them showed preferential expression in a specific tissue. Heterotrophic cultured cells were used as model systems for the functional characterization of the VvGATA gene and study of its response to light and phytohormone. The results indicated that some VvGATA genes displayed differential responses to light and phytohormones, suggesting their role in light and hormone signaling pathways. A thorough analysis of GATA transcription factors in grape (V. vinifera L.) presented the characterization and functional prediction of VvGATA genes. The data presented here lay the foundation for further functional studies of grape GATA transcription factors.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Comparison of Dynamic Performance of an All-Metallic Vibration Isolator by Elliptic Method and Frequency Sweeping Method

A horizontally symmetric all-metallic vibration isolator (AM-VI) is proposed to further investigate the dynamic mechanical performance. The novel AM-VI was constructed by combining hat-shaped metal rubber and oblique springs, which were connected in parallel. The springs were arranged symmetrically relative to the support. The elliptic method and the frequency sweeping method were used to compare the dynamic stiffness and the loss factor of the AM-VI. The results demonstrated that the dynamic stiffness and the loss factor calculated by two distinct test methodologies were considerably different, indicating that the inertial force effect of the dynamic testing equipment should be taken into count when adopting the elliptic method. Furthermore, when the vibration isolation performance was evaluated by utilizing mechanical impedance and force transmissibility, the AM-VI achieved excellent vibration isolation performance within a broad frequency range

Psychological Impact and Compliance with Staying at Home of the Public to COVID-19 Outbreak during Chinese Spring Festival

In December 2019, COVID-19 was reported in Wuhan, China. Most of the studies related to the psychological impact and compliance with staying at home due to COVID-19 focused on ten days or one month after the initial “stay-at-home” phase of the COVID-19 pandemic. The early psychological impact and behavior change to COVID-19 during the Chinese Spring Festival (the start time for recommendations to stay at home) is uncertain. In this study, people from 23 provinces in China were recruited to participate in an online survey, using Credamo. Psychological impact and compliance with staying at home were evaluated by a self-designed and validated questionnaire. The results indicated that anxiety was the most often reported feeling (mean: 3.69), followed by sadness (mean: 3.63). Participants employed in foreign-owned companies were most likely to express anxiety and sadness. Overall, 61.8% of participants reported hardly going out, whereas 2.4% said they frequently went out during the initial “stay-at-home” phase of the COVID-19 pandemic. Participants with higher levels of anxiety and sadness were most likely to stay at home against the spread of COVID-19, as were female gender. This survey is an important study of the first reaction to staying at home during the initial “stay-at-home” phase coinciding with Chinese Spring Festival. Our findings identified factors associated with higher level of psychological impact and better compliance with staying at home recommendations during Chinese Spring Festival. The findings can be used to formulate precaution interventions to improve the mental health of vulnerable groups and high uptake of policy during the COVID-19 epidemic

Effects of sunlight on anthocyanin accumulation and associated co-expression gene networks in developing grape berries

Three Vitis species were used to investigate the effects of sunlight exposure on anthocyanin accumulation in five developmental stages. The berries of these three grapes were treated with exclusion of sunlight or recovery of sunlight during different developmental stages. Vitis labrusca cannot accumulate anthocyanins in its berries under dark conditions. V. acerifolia and V. cinerea can accumulate anthocyanins under dark conditions. Using high-throughput RNA sequencing, we produced transcriptomes for these samples. Then, we constructed a weighted gene co-expression network of these three Vitis species and defined 17 modules which were correlated to anthocyanin concentrations, developmental stages and species. Analysis of the anthocyanin correlated co-expression network module revealed that two novel bHLH genes might be involved in anthocyanin regulation in grapes. Moreover, the hormone transductions might enhance anthocyanin accumulation in V. acerifolia and V. cinerea under dark. Further functional analysis of anthocyanin negatively correlated modules revealed that anthocyanin accumulation might be inhibited by COP1-dependent protein degradation before veraison and under dark conditions in grape berries

<em>VvSWEET10</em> Mediates Sugar Accumulation in Grapes

Sugar accumulation is a critical event during grape berry ripening that determines the grape market values. Berry cells are highly dependent on sugar transporters to mediate cross-membrane transport. However, the role of sugar transporters in improving sugar accumulation in berries is not well established in grapes. Herein we report that a Sugars Will Eventually be Exported Transporter (SWEET), that is, VvSWEET10, was strongly expressed at the onset of ripening (véraison) and can improve grape sugar content. VvSWEET10 encodes a plasma membrane-localized transporter, and the heterologous expression of VvSWEET10 indicates that VvSWEET10 is a hexose-affinity transporter and has a broad spectrum of sugar transport functions. VvSWEET10 overexpression in grapevine calli and tomatoes increased the glucose, fructose, and total sugar levels significantly. The RNA sequencing results of grapevine transgenic calli showed that many sugar transporter genes and invertase genes were upregulated and suggest that VvSWEET10 may mediate sugar accumulation. These findings elucidated the role of VvSWEET10 in sugar accumulation and will be beneficial for the improvement of grape berry quality in the future

A Rapid and Sensitive Aptamer-Based Biosensor for Amnesic Shellfish Toxin Domoic Acid

With the incidence of harmful algal blooms (HABs) increasing in recent years, the urgent demand for the detection of domoic acid (DA), an amnesic shellfish toxin mainly produced by red tide algae Pseudonitzschia, has aroused increasing attention. Aptamers, a new molecular recognition element, provide clarity in the monitoring of DA. In this study, aptamers of DA were successfully screened by Capture-SELEX. Through identification and truncation optimization, aptamer C1-d with a high affinity (KD value, 109 nM) and high specificity for DA was obtained. The binding mechanism between DA and the aptamer was explored by molecular docking and molecular dynamics (MD) simulation, revealing the critical sites for DA&ndash;aptamer interaction. Meanwhile, a BLI-based aptasensor was constructed by C1-d, which displayed a linear range from 0.625 to 10 &mu;M and a LOD of 13.7 nM. This aptasensor exhibited high specificity, good precision and repeatability, and high recovery rates for real samples; the process of detection could be completed in 7 min. This study is the first to identify and investigate the binding mechanism of DA&ndash;aptamer interaction and constructed a BLI-based aptasensor for DA, which lays a theoretical foundation for the detection and prevention of DA