A turbidity current is a process of sediment transport into subaqueous environments such as deep lakes and oceans (Daly, 1936;Johnson, 1939). Turbidites, the deposits of turbidity currents, are often characterized by graded bedding and sedimentary successions called the Bouma sequence (e.g., Bouma, 1962;Kuenen & Migliorini, 1950;Talling et al., 2012). Turbidites have been an active area of study due to their close association with petroleum resources and their role in the destruction of sea-floor equipment, such as submarine cables (Talling et al., 2015;Weimer & Slatt, 2007). Furthermore, turbidites are often deposited as a result of tsunami triggered turbidity currents (Arai et al., 2013) and thus can contribute to determine the recurrence intervals of geohazards.Studying the flow behavior of turbidity currents is essential for understanding the characteristics of turbidites and their implications (Talling et al., 2007). However, knowledge in this area remains limited because of the difficulties in the direct observation of turbidity currents. Several in-situ measurements have been conducted (e.g.,
Maize is an essential source of nutrition for humans and animals, which is rich in various metabolites and determine its quality. Different maize varieties show significant differences in metabolite content. Two kinds of waxy maize parental materials, S181 and 49B, created by the Chongqing Academy of Agricultural Sciences, are widely grown in China. S181 shows higher starch and sugar contents than 49B. This study generated metabolic profiles to assess the differences between the two varieties. A total of 674 metabolites that were significantly differentially expressed between the two varieties were identified by gas chromatography and untargeted metabolomics technology. These metabolites were associated with 21 categories, including antioxidant metabolites. Moreover, 6415 differentially expressed genes (DEGs) were identified by RNA-seq. Interestingly, these DEGs comprised starch and sugar synthesis pathway genes and 72 different transcription factor families. Of these, 6 families which were reported to play an essential role in plant antioxidant action accounted for 39.2% of the transcription factor families. Using the KEGG classification, the DEGs were mainly involved in amino acid biosynthesis, glycolysis/glucose metabolism, and the synthetic and metabolic pathways of antioxidant active substances. Furthermore, the correlation analysis of transcriptome and metabonomics identified five key transcription factors(ZmbHLH172, ZmNAC44, ZmNAC-like18, ZmS1FA2, ZmERF172, one ubiquitin ligase gene(ZmE2 5A) and one sucrose synthase gene(ZmSS1). They likely contribute to the quality traits of waxy corn through involvement in the metabolic regulatory network of antioxidant substances. Thus, our results provide new insights into maize quality-related antioxidant metabolite networks and have potential applications for waxy corn breeding.
Hydraulic jumps control the bypass, erosion, and depositional processes of Froude-supercritical turbidity currents, so they represent a significant process for understanding the development of submarine geomorphology. Hydraulic jumps actively occur from submarine canyons to fans, where the seafloor slope is relatively steep. Turbidites in such areas comprise large-scale bedforms called cyclic steps, and they exhibit complex internal structures, including localized erosion and the accumulation of coarse-grained fining-upward sequences. However, it is unclear which turbidity-current properties are reflected in the heterogeneous depositional characteristics and grain-size sorting of these deposits. To this end, we conducted flume experiments to reproduce deposits associated with the hydraulic jumps of surge-type flows. Turbidity-current surges were repeatedly generated in an experimental flume with a knickpoint that transitioned from a steep to a gentle slope, resulting in cyclic steps. Overall, the upstream migration of the cyclic steps produced a downstream-upward-fining succession of turbidites. However, hydraulic jumps occurred at several places over the trough to the stoss side of the step in a single flow due to the non-uniform and unsteady flow state of the surge-type turbidite succession. As a result, the reproduced succession exhibited multiple local scours and coarse-grained fill in the lower parts of the turbidites. This suggests that multiple local scours and fining-upward trends are discriminant characteristics of cyclic-step deposits formed by surge-type supercritical turbidity currents.
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