28 research outputs found
Heavy Mineral Assemblage Variation in Late Cenozoic Sediments from the Middle Yangtze River Basin: Insights into Basin Sediment Provenance and Evolution of the Three Gorges Valley
The Three Gorges valley is one of the two key capture points of the evolution of the Yangtze River, yet the formation of this valley—from the pre-Miocene to the late Pleistocene—remains uncertain. The Jianghan Basin, a late Mesozoic–Cenozoic basin located just downstream of the Three Gorges valley, is a crucial area for understanding the formation of the valley. In this study, we used heavy mineral assemblages to trace the provenance of Pliocene–Pleistocene sediments obtained from the 300-m-depth Zhoulao drillcore in the Jianghan Basin. Results show that heavy mineral concentrations, compositions, and species display a clear change at a depth of 110 m in the studied core, consistent with the change in values of magnetic indexes and trace-element geochemical indicators. The heavy mineral assemblage deposited below a depth of 110 m (lower section of the core) comprises zircon, epidote, leucoxene, rutile, anatase, pyrite, and titanite, whereas that deposited above 110 m (upper section) consists of hornblende, pyroxene, garnet, hematite-limonite, and magnetite. In addition, the heavy mineral assemblage of the upper section is similar to that of the modern surface fluvial sediments of the Yangtze, which indicates that materials of the upper core section of the Jianghan Basin were sourced from the upper Yangtze River Basin, west of the Three Gorges. After incision of the Three Gorges valley, sediments from the upper Yangtze were transported to the Jianghan Basin and deposited. Combining the results of this study with the known paleomagnetic chronology of the Jianghan Basin, we propose that the Three Gorges valley was incised at ca. 1.1 Ma
Clinical Value of Prenatal Ultrasound in the Diagnosis of Fetal Ductus Venosus Abnormality
Background: The fetal ductus venosus (DV) is an important vessel that connects the umbilical vein (UV) to the proximal end of the inferior vena cava (IVC). DV abnormality often leads to poor fetal outcome. Thus, careful prenatal ultrasound for the diagnosis of DV abnormality is of major clinical significance. Methods: We conducted a retrospective analysis of 166 cases diagnosed with DV abnormality by prenatal ultrasonography. The type of DV abnormality, aberrant DV connection, and combination with intra- and extra-cardiac malformations were evaluated, together with pregnancy outcomes and chromosomal anomalies. Results: Prenatal ultrasound screening revealed that 137 of the 166 fetal cases with DV abnormality showed an absence of ductus venosus (ADV) accompanied by aberrant drainage of the UV (119 cases with intrahepatic shunt of the UV and 18 cases were extrahepatic shunt of the UV). Another 27 cases showed aberrant DV connections (9 cases with intrahepatic shunt of the UV and 18 cases with extrahepatic shunt of the UV). In addition, one case showed DV bifurcation accompanied by extrahepatic shunt of the UV, and one case showed DV atresia accompanied by intrahepatic shunt of the UV. Moreover, 72 cases were also diagnosed with intra- or extra-cardiac malformations. A total of 105 fetuses were born, including 79 with ADV, 24 with aberrant DV connection, 1 with DV bifurcation, and 1 with DV atresia. These were followed up for an average period of 12 months (range 1 to 24 months). Liver-function tests and cardiac ultrasound were performed postpartum. Pregnancy was terminated in 61 cases due to severe fetal deformities, which were confirmed by pathological anatomy after abortion. Only 28 cases underwent chromosomal examination, of which one case was diagnosed with trisomy 21 and another with trisomy 18. Conclusions: Prenatal ultrasound can clearly show fetal DV abnormalities and aberrant connections, as well as associated intra- and extra-cardiac malformations. This procedure can therefore provide comprehensive support for the diagnosis of fetal DV abnormality. Careful attention should thus be paid during prenatal ultrasound examination in order to obtain valuable information for prenatal consultation and subsequent procedures and care
Performance Analysis of Multihop Relaying Caching for Internet of Things under Nakagami Channels
Performance analysis is studied in this paper for the wireless transmissions in Internet of Things (IoT) system, where both the direct link and the multihop relaying caching wireless transmission from the source node to the destination node are taken into the consideration. The key feature is the Nakagami channels of the wireless channel from the source node to the destination node, which results in the difficulty of the theoretical analysis over the system performance. To tackle this difficulty, the probability distribution function (PDF) of the received signal-to-noise ratio (SNR) at the destination node is derived by exploiting the function and integral properties. Then, the outage probability and bit error rate (BER) of the whole wireless IoT system are derived in the analytical expression without any approximation. Numerical simulations demonstrate the accuracy of the derived theoretical analysis for this system
Performance Analysis of Multihop Relaying Caching for Internet of Things under Nakagami Channels
Changing provenance of late Cenozoic sediments in the Jianghan Basin
The Yangtze River is one of the most important components of the East Asia river system. In this study, sediments in the Jianghan Basin, middle Yangtze River, were selected for trace element and rare earth element (REE) measurements, in order to decipher information on the change of sediment provenance and evolution of the Yangtze River. According to the elemental variations, the late Cenozoic sediments of the Jianghan Basin could be divided into four parts. During 2.68–2.28 Ma and 1.25–0 Ma, provenance of the sediments was consistent, whereas sediments were derived from variable sources during 2.28–1.25 Ma. Comparison of the elemental compositions between the Pliocene and Quaternary sediments revealed a change in sediment source from a more felsic source area to a more basic source area around the Pliocene–Quaternary boundary. Input from the Emeishan LIP should account for this provenance change. Based on the provenance analysis of sediments in the Jianghan Basin, we infer that the Yangtze River developed into a large river with its drainage basin extended to the Emeishan LIP no later than the Pliocene–Quaternary boundary
Provenance discrimination diagrams used to identify whether mixed sources exist. Geochemistry of loess deposits in northeastern China: constraint on provenance and implication for disappearance of the large Songliao palaeolake
Supplementary Fig. 6 Provenance discrimination diagrams used to identify whether mixed sources exist. Trend lines on scattergrams are mass gain-mass loss paths extending from the origin. Note that the geochemical compositions for the Harbin aeolian loess locate between average compositions of the Horqin Sandy Land and the Songnen Sandy Land, indicating mixture of these two sandy lands
UCC-normalized patterns for major and trace elements of the Harbin loess and paleosols. Geochemistry of loess deposits in northeastern China: constraint on provenance and implication for disappearance of the large Songliao palaeolake
Supplementary Fig. 1 The UCC-normalized patterns for major and trace elements of the Harbin loess and paleosols, in comparison with the potential sources. UCC values are from Taylor and McLennan (1985)
Sketch map of the Songliao paleolake and Basin. Geochemistry of loess deposits in northeastern China: constraint on provenance and implication for disappearance of the large Songliao palaeolake
Supplementary Fig. 7 Sketch map of the Songliao paleolake and Basin, illustrating distribution and evolution of the large Songliao paleolake in the Quaternary (modified from Yang <i>et al.</i>, 1983; Sun, 1990; Qiu <i>et al.</i>, 2012)
Agro-Based Spent Mushroom Compost Substrates Improve Soil Properties and Microbial Diversity in Greenhouse Tomatoes
Spent mushroom compost (SMC) substrates are commonly used as growth media for greenhouse crops and horticulture production. This study aimed to investigate the responses of physiochemical soil properties, enzyme activities, and microbial community compositions to different cultivation durations and SMC soil treatments on tomatoes. The experiment included the following treatments: SMC substrate and the surrounding soil after planting at 1, 3, and 7 years and comparing control treatments including non-planting SMC substrates and continuous mono-cropping soil. The results revealed that the SMC substrates had higher contents of total N P and organic C nutrients than the surrounding soil treatments. The physicochemical soil properties and soil enzyme activities of the SMC substrates were significantly decreased with longer cultivation duration. Microbial alpha diversity was higher in the SMC substrates regardless of cultivation duration than in the control treatments. It was observed that many beneficial microbes, such as bacteria of the Deinococcus-Thermus, Halanaerobiaeota, and Nitrospirae phyla, and the fungi of the Basidiomycota, Mortierellomycota, and Chytridiomycota phyla were enriched in the SMC substrates. The SMC substrate and surrounding soil had enriched several potentially beneficial microorganism genera such as the bacterial Saccharimonadales, Gaiella, Bacillus, and the fungal Thermomyces, Kernia, and Mortierella. Therefore, the agro-based SMC substrate grooved cultivation system is recommended as an environmentally compatible practice for tomato growth in the greenhouse
Provenance discrimination diagrams integrating immobile trace elements and REE for the Harbin loess and paleosols. Geochemistry of loess deposits in northeastern China: constraint on provenance and implication for disappearance of the large Songliao palaeolake
Supplementary Fig. 3: Provenance discrimination diagrams integrating immobile trace elements and REE for the Harbin loess and paleosols. Note that the Harbin dust samples fall within the field of the Songnen Sandy Land and the Horqin Sandy Land but far outside the field of the Hulun Buir Sandy Land, revealing a geochemical affinity of the Harbin aeolian loess with the the Songnen Sandy Land and Horqin Sandy Land