The plastic deformation of TWIP steel is greatly inhibited during the expansion process. The stress-strain curves obtained through expansion experiments and observations of fracture morphology ...confirmed the low plastic behavior of TWIP steel during expansion deformation. Through an analysis of the mechanical expansion model, it was found that the expansion process has a lower stress coefficient and a faster strain rate than stretching, which inhibits the plasticity of TWIP steel during expansion deformation. Using metallographic microscopy, transmission electron microscopy, and EBSD to observe the twin morphology during expansion deformation and tensile deformation, it was found that expansion deformation has a higher twin density, which is manifested in a denser twin arrangement and a large number of twin deliveries in the microscopic morphology. During the expansion deformation process, dislocation slips are hindered by twins, the free path of the slips is reduced, and dislocations accumulate significantly. The accumulation area is the initial point of crack expansion. The results show that the significant dislocation accumulation caused by the delivery of a large number of twins under expansion deformation is the main reason for the decrease in the plasticity of TWIP steel.
Key message
FtMYB18 plays a role in the repression of anthocyanins and proanthocyanidins accumulation by strongly down-regulating the
CHS
and
DFR
genes in Tartary buckwheat, and the C5 motif plays an ...important role in this process.
Anthocyanins and proanthocyanidins (PAs) are important flavonoids in Tartary buckwheat (
Fagopyrum tataricum
Gaertn
.
), which provides various vibrant color and stronge abiotic stress resistance. Their synthesis is generally regulated by MYB transcription factors at transcription level. However, the negative regulations of MYB and their effects on flavonol metabolism are poorly understood. A SG4-like MYB subfamily TF, FtMYB18, containing C5 motif was identified from Tartary buckwheat. The expression of
FtMYB18
was not only showed a negative correlation with anthocyanins and PAs content but also strongly respond to MeJA and ABA. As far as the transgenic lines with
FtMYB18
overexpression, anthocyanins and PAs accumulations were decreased through down-regulating expression levels of
NtCHS
and
NtDFR
in tobacco,
AtDFR
and
AtTT12
in Arabidopsis,
FtCHS
,
FtDFR
and
FtANS
in Tartary buckwheat hairy roots, respectively. However,
FtMYB18
showed no effect on the
FLS
gene expression and the metabolites content in flavonol synthesis branch. The further molecular interaction analysis indicated FtMYB18 could mediate the inhibition of anthocyanins and PAs synthesis by forming MBW transcriptional complex with FtTT8 and FtTTG1, or MYB-JAZ complex with FtJAZ1/-3/-4/-7. Importantly, in FtMYB18 mutant lines with C5 motif deletion (FtMYB18-C), both of anthocyanins and PAs accumulations had recovered to the similar level as that in wild type, which was attributed to the weakened MBW complex activity or the deficient molecular interaction between FtMYB18ΔC5 with FtJAZ3/-4. The results showed that FtMYB18 could suppress anthocyanins and PAs synthesis at transcription level through the specific interaction of C5 motif with other proteins in Tartary buckwheat.
Tartary buckwheat (Fagopyrum tataricum) is rich in flavonols, which are thought to be highly beneficial for human health. However, little is known about the regulatory mechanism of flavonol ...biosynthesis in Tartary buckwheat. In this study, we identified and characterized a novel SG7 R2R3-MYB transcription factor in Tartary buckwheat, FtMYB6. We showed that FtMYB6 is located in the nucleus and acts as a transcriptional activator. The FtMYB6 promoter showed strong spatiotemporal specificity and was induced by light. The expression of FtMYB6 showed a significant correlation with rutin accumulation in the roots, stems, leaves, and flowers. Overexpression of FtMYB6 in transgenic Tartary buckwheat hairy roots and tobacco (Nicotiana tabacum) plants significantly increased the accumulation of flavonols. In transient luciferase (LUC) activity assay, FtMYB6 promoted the activity of FtF3H and FtFLS1 promoters and inhibited the activity of the Ft4CL promoter. Collectively, our results suggest that FtMYB6 promotes flavonol biosynthesis by activating FtF3H and FtFLS1 expression.
•A permeative anti-rutting agent (PARA) enhancing rutting resistance was developed.•PARA’s optimum composition was determined firstly.•PARA’s effect on pavement performance of asphalt mixture was ...then analyzed.•PARA enhanced the pavement section demanding specific rutting resistance flexibly.•Aging and fatigue performance can be improved by PARA.
Rutting distress has adverse effects on driving safety and comfort. However, how to enhance the rutting resistance of specific pavement sections contrapuntally and flexibly still requires further study. A permeative anti-rutting agent (PARA) based on epoxy resin and Buton rock asphalt was developed in this study to enhance the rutting resistance of asphalt pavement. It can improve the rutting resistance by permeating and curing in the asphalt pavement. Its optimum composition was characterized and determined at first. PARA’s effect on pavement performance of asphalt mixture was then tested and analyzed. Results suggested that the optimum mass proportion of epoxy resin, curing agent, curing accelerator and Buton rock asphalt was determined as 1.6:1:0.02:0.32. The lowest exudative percentage of PARA was found when its content was 0.9%. Higher PARA content will result in lower void volume and void in mineral aggregate of asphalt mixture. The mixture’s Marshall stability, moisture resistance, and dynamic stability were positively correlated to PARA’s content. The lowest flexural tensile strain and flexural tensile strength in low temperature occurred when PARA content was 0.9%. Asphalt mixture with 0.90% PARA showed optimum fatigue performance and aging resistance. Therefore, PARA can be used to enhance the asphalt pavement at low cost. Its advantage in flexibility and convenience results in its excellent application prospect.
H. Lév is a medicinal plant that has a variety of pharmacological activities, but its study is at a standstill due to the shortage of resources.
This study utilized the surface sterilization method ...to isolate endophytic fungi, and they were preliminarily identified by morphology. Flavonoid-producing strains were screened by NaNO
-Al(NO)
colorimetry and further identified by the ITS sequence. Additionally, we used five antioxidant assays (DPPH, Hydroxyl radical, ABTS, FRAP and T-AOC assays) to systematically evaluate the antioxidant capacity of total flavonoids , and we also determined their antibacterial activity.
In this study, 21 endophytic fungi were isolated from wild
H. Lév for the first time. There were six flavonoid-producing strains, especially CBL11, whose total flavonoid content reached 50.78 ± 2.4 mg/L. CBL12, CBL12-2 and CBL1-1 all exhibited excellent antioxidant activity. The effect of CBL12 was similar to that of ascorbic acid at low concentrations, and its radical scavenging rates for DPPH and ABTS were 94.56 ± 0.29 % and 99.88 ± 0.27%, respectively, while its IC
values were only 0.11 ± 0.01 mg/mL and 0.2 ± 0.01 mg/mL. Through LC-MS, we found that CBL12 could produce many high-value flavonoids, such as 3-methoxyflavone, nobiletin, formononetin, scopoletin, and daidzein. Additionally, CBL9 had good antibacterial activity against both gram-positive and gram-negative bacteria. Notably, we obtained the high-yield strains CBL12 and CBL9, which not only had high yields (10.64 ± 1.01 mg/L and 10.17 ± 0.11 mg/L, respectively) but also had excellent biological activity. Hence, the results of this study provide new ideas for endophytic fungi that can be exploited as a source of flavonoids and other medicinal components from
H. Lév. Moreover, this study can serve as a reference for the development of rare medicinal materials.
Reconstructing the role of provenance and transport mechanism of sediments deposited in deep-water environments is often complex because of myriad of factors such as variability in sediment sources, ...tectonics, bottom morphology, climatic changes and sea level fluctuations as well as current regime. The South China Sea (SCS) is situated at the tectonic intersection of the Pacific, Eurasian, and Indo-Australian plates, and provides an excellent natural laboratory for understanding source-to-sink transport processes of fluvial sediments. The Qiongdongnan Basin (QDNB) is located in the northern part of the SCS, and the deep-water area (>300 m) of the QDNB has a good hydrocarbon source and hydrocarbon accumulation conditions with a tremendous thickness since the late Miocene-Quaternary. However, the complex sources and transport mechanisms of sediments in the QDNB are undefined. In previous study QDNB may have a major provenance or a mixture of sources. In this paper, the sediments of two cores from the deep-water area of QDNB have been analyzed using several sedimentological and geochemical approaches, including measurements of grain size distribution(433 samples), the occurrence of minerals, and trace element geochemistry(37 samples)as well as strontium and neodymium isotopes(20 samples).The granularity analysis results first show that the 19S37 core can be divided into three stages while the 19S40 core is divided into two stages by clear vertical variations in grain size characteristics. Chlorite (62.0%) and Muscovite (33.6%) appear to be the predominant minerals in the 19S37 core, while the mineral assemblage of sediments from 19S40 mainly consists of kaolinite (37.4%), muscovite (29.2%) and chlorite (27.1%). The primitive mantle standardization curves and chondrite standardized distribution patterns of 19S37 and 19S40 are consistent and display enrichments in Th, U, Pb, and Nd and depletions in Ba, Nb, Sr, and Eu. In addition, the content of Sr fluctuates greatly with depth, which should reflect the influences of sea level changes and the relative proportion of various provenance components. The 143Nd/144Nd ratios and εNd values of the sediments from 19S37 are higher than those of the sediments from 19S40, and all the εNd values show narrow variations and range from −10.085 to −11.080. We conclude that the sediments of the deep-water area in the upper Pleistocene-Holocene were mainly from the sources of the Red River, Taiwan, Pearl River, Hainan Island, and Vietnam. The transport mechanism of the sediments from Hainan Island can be explained by the short distance between the source region and the sedimentary site, while the large amounts of terrigenous sediment inputs derived from the Red River and advantageous morphology make the Red River the largest sediment source to cores 19S37 and 19S40. The transport distance and amount of Deep Water Current could be even more powerful to make Taiwan be the second largest source of modern sediments in QDNB.
•19S37 core can be divided into three stages while the 19S40 core is divided into two stages.•The sediment of the deep-water area QDNB is mainly from the sources of the Red River.•The Pearl River and Taiwan Island have significant contributions to the whole NSCS.•The deep-water current and shallower Kuroshio current are the main pathways.•Sediments from the Pearl River were mainly transported by the Guangdong Coastal Current.
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