Basalt geochemistry can be used as a diagnostic indicator for determining the tectonic setting of origin, because specific plate tectonic settings often impart distinctive geochemical ...characteristics. For example: (1) mid-ocean ridge basalts (MORB) and oceanic island basalts (OIB) have clearly distinguishable trace element and Sr-Nd isotope geochemical characteristics; (2) arc related basalts, including IOAB (intra-oceanic arc basalts), IAB (island arc basalts) and CAB (continental arc basalts), exhibit following distinguishing features: all are characterized by low Nb/La ratios (<0.85) and negative Nb, Ta and Ti anomalies; most exhibit low Nb concentrations (<8 ppm), high positive ɛNd values and low enrichment of incompatible elements except the continental arc shoshonitic basalts that possess high concentrations of incompatible trace elements and lower to negative ɛNd values; (3) although contamination by continental crust or lithosphere can impart subduction-like signature (e.g., low Nb, low Ta and low Ti) and lead to misidentification of contaminated continental intraplate basalts as arc related, there are still some essential differences between continental intraplate basalts and arc related ones; such as: uncontaminated continental intraplate basalts have high Nb concentrations, Nb/La > 1, “hump-shaped” OIB-like trace element patterns and moderate positive ɛNd values that distinguish them from the arc related ones; whereas, the contaminated continental intraplate basalts are characterized by pronounced negative Nb, Ta and Ti anomalies, but their concentrations of incompatible trace elements are conspicuously higher than those of subduction-zone basalts that also distinguishes them from the arc related ones; (4) an important difference between back-arc basin basalts (BABB) and the MORB is that the former exhibit both MORB-like and arc-like geochemical characteristics; (5) most oceanic plateau basalts (OPB) show diagnostic geochemical characteristics of enriched MORB (E-MORB) to transitional MORB (T-MORB); only the Kerguelen Plateau is an exception; the early (pre 90 Ma) volcanism of the Kerguelen Plateau is associated with the Early Cretaceous break-up of Gondwana and displays features of continental flood basaltic volcanism; with time, the tectonic setting of the Kerguelen plume-derived volcanism changed from a rifted continental margin setting (133–118 Ma) through a young, widening ocean (118–40 Ma), finally to an oceanic intraplate setting (~40 Ma to the present).
Tectonic discrimination diagrams should not be used in isolation, but can still be useful as part of holistic geochemical characterization. For example: (1) MORB and OIB are distinguishable from each other in the 3Tb-Th-2Ta diagram; (2) the arc related basalts, including IOAB, IAB and CAB, constantly plot in the arc-related basalts fields in the Th/Yb-Ta/Yb diagram; (3) the 3Tb-Th-2Ta diagram can be utilized to fully illustrate both MORB-like and arc-like characteristics of BABB; (4) some discriminant diagrams (such as Zr/Y-Zr, Th/Yb-Ta/Yb, 3Tb-Th-2Ta and Hf/3-Th-Nb/16 diagrams) can be used to distinguish continental intra plate basalts from arc related ones; (5) although there are not any discrimination diagrams published that delineate an OPB field, some trace element diagrams can still reveal diagnostic characteristics of the OPB.
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•Basalt geochemistry can be used as a diagnostic indicator of tectonic setting.•Basalt geochemistry plays a major role in identifying the tectonic setting of basalts.•The auxiliary role of some trace element discrimination diagrams should still be affirmed.
Metacognition is a process of self-cognition and self-thinking based on self-reflection, control, evaluation and regulation to achieve continuous cognition of individuals. Metacognition plays a very ...important role in coordination and guidance in college English education. Therefore, in this paper, the characteristics and rules of college English education were studied based on the cognitive process simulation. First of all, the basic theory of metacognition and the advantages and methods applied to English teaching were expounded. Then, a mathematical model was set up for college oral English teaching, and how to improve oral pronunciation for oral learners by quantitative and effective evaluation was discussed. After that, targeted information evaluation results were provided, and the algorithm was optimized and improved. Finally, by using computer aided technology and metacognitive method, the effect of oral English teaching was simulated and tested. The results show that the results of this study provide a useful exploration for improving the effectiveness of college English education and have good application value.
Chemical contamination in food is one of the most serious food safety problems. Competitive enzyme-linked immunosorbent assay (Cp-ELISA) is the most widely used analytical tool for detection of food ...chemical contaminants due to its high throughput, low cost, and straightforward readouts. However, conventional ELISA suffers from low sensitivity, which greatly limits its potential in highly sensitive detection. To fulfill increasingly stringent control requirement for chemical contaminants in food, improving the sensitivity of Cp-ELISA is important and meaningful. In this paper, we will briefly review various emerging strategies for increasing Cp-ELISA sensitivity, including: 1) screening higher affinity antibodies to target antigens; 2) preparing competing antigens with lower affinity to antibodies; 3) employing signal amplification; and 4) introducing novel signal transducer elements. This review will focus on clarifying the underlying mechanisms of these strategies in improving sensitivity and providing a careful comparison. Brief discussion on challenges and future directions will be elaborated.
•Emerging strategies for improving the detection sensitivity of competitive ELISA was systematically reviewed.•Three core elements of antibodies, competing antigens and signal transducers in competitive ELISA were highlighted.•Typical applications for food chemical contamination detection were selected.•This work perhaps stimulates an extensive and deep research in this field.
•We investigated the anti-JEV effect of luteolin in vitro.•Luteolin exhibited antiviral activity against JEV.•Luteolin showed extracellular virucidal activity on JEV.•Luteolin inhibited JEV at the ...post-entry stage.
Japanese encephalitis virus (JEV), a member of family Flaviviridae, is a neurotropic flavivirus that causes Japanese encephalitis (JE). JEV is one of the most important causative agents of viral encephalitis in humans, and this disease leads to high fatality rates. Although effective vaccines are available, no effective antiviral therapy for JE has been developed. Hence, identifying effective antiviral agents against JEV infection is important. In this study, we found that luteolin was an antiviral bioflavonoid with potent antiviral activity against JEV replication in A549 cells with IC50=4.56μg/mL. Luteolin also showed extracellular virucidal activity on JEV. With a time-of-drug addition assay revealing that JEV replication was inhibited by luteolin after the entry stage. Overall, our results suggested that luteolin can be used to develop an antiviral drug against JEV.
A solution to the unmet synthetic challenge of achieving highly atropo-enantioselective transesterification of Bringmann's lactones has been realized, employing a chiral bifunctional amine thiourea ...as promoter. The synergistic activation of the lactones and alcohols/phenols by the respective thiourea and amine groups is crucial for achieving the highly enantioselective, high-yielding dynamic kinetic resolution process. This protocol gives highly optically pure, axially chiral biaryl compounds with a broad substrate scope under mild reaction conditions.
The Carboniferous–Early Permian rift-related volcanic successions, covering large areas in the Chinese Tianshan and its adjacent areas, make up an important phanerozoic large igneous province in the ...word, which can be further divided into two sub-provinces: Tianshan and Tarim. The Early Permian volcanic rocks have been considered to be the products of an intraplate volcanism by most researchers. However, there is still strong controversy about the nature and geological setting of the Carboniferous volcanic rocks. The regional angular unconformity of Lower Carboniferous upon basement or pre-Carboniferous rocks, the ages (360–351 Ma) of the youngest ophiolite and the peak of subduction metamorphism of high pressure-low temperature metamorphic belt and the occurrence of Ni-Cu-bearing mafic-ultramafic intrusion with age of ~352 Ma and A-type granite with age of ~358 Ma reveal that the final closure of the Paleo-Asian Ocean might take place in the Early Mississippian. Our studies reveal that although contamination by continental crust or lithosphere can impart subduction-like signature (e.g., low Nb, low Ta and low Ti) and lead to misidentification of contaminated Carboniferous basaltic lavas from the Chinese Tianshan and its neighboring areas as arc related, there are still some essential differences between the Carboniferous basaltic lavas and arc related ones; such as: uncontaminated Carboniferous basaltic lavas have higher Nb concentrations (9–22 ppm), Nb/La > 1, “hump-shaped” OIB-like trace element patterns and moderate positive ɛNd values that distinguish them from the arc related ones; whereas, the contaminated Carboniferous basaltic lavas are characterized by pronounced negative Nb, Ta and Ti anomalies, but, their concentrations of incompatible trace elements are conspicuously higher than those of subduction-zone basalts that also distinguishes them from the arc related ones. Our summation suggests that the Carboniferous volcanic successions did indeed erupt in an intracontinental rift setting and their generation is likely confined to mantle plume.
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•The final closure of the Paleo–Asian Ocean might occur in the Early Mississippian.•The Tianshan Carboniferous volcanics did indeed erupt in an intracontinental rift setting.•The Tiashan–Tarim Carboniferous–Early Permian volcanics make up a large igneous province.
Colorectal cancer (CRC) is one of the most common malignant tumors globally. Angiogenesis is a key event maintaining tumor cell survival and aggressiveness. The expression of vascular endothelial ...growth factor A (VEGFA), one of the most significant tumor cell-secreted proangiogenic factors, is frequently upregulated in CRC.
The MTT assay was used to detect the viability of CRC cells. Transwell assays were performed to detect the invasion capacity of target cells. Relative protein levels were determined by immunoblotting. Pathological characteristics of tissues were detected by H&E staining and immunohistochemical (IHC) staining. A RIP assay was conducted to validate the predicted binding between genes.
We observed that circ-001971 expression was dramatically increased in CRC tissue samples and cells. Circ-001971 knockdown suppressed the capacity of CRC cells to proliferate and invade and HUVEC tube formation in vitro, as well as tumor growth in mice bearing SW620 cell-derived tumors in vivo. The expression of circ-001971 and VEGFA was dramatically increased whereas the expression of miR-29c-3p was reduced in tumor tissue samples. Circ-001971 relieved miR-29c-3p-induced inhibition of VEGFA by acting as a ceRNA, thereby aggravating the proliferation, invasion and angiogenesis of CRC. Consistent with the above findings, the expression of VEGFA was increased, whereas the expression of miR-29c-3p was decreased in tumor tissue samples. miR-29c-3p had a negative correlation with both circ-001971 and VEGFA, while circ-001971 was positively correlated with VEGFA.
In conclusion, the circ-001971/miR-29c-3p axis modulated CRC cell proliferation, invasion, and angiogenesis by targeting VEGFA.
•Degradation of bamboo mechanical properties with increasing moisture content is demonstrated.•Degradation is significant below fiber saturation point and less pronounced at higher moisture ...contents.•Location along the length of the culm also affects the observed degradation.•For scaffold applications, compression capacity is a conservative analogue for other mechanical properties.•In scaffold applications, the base of the culm and base of the scaffold will be most critical to performance.
Bamboo is widely used as scaffolding for which collapses, often associated with rain events, are not uncommon. The presented study quantifies the degradation of mechanical properties of bamboo samples following immersion in water for 1 and 7days to simulate the effects of significant rain events. Compression, longitudinal shear and splitting tests were conducted to obtain the respective strengths and moduli. The mechanical properties were observed to degrade significantly with increased moisture content (MC) up to about MC=30%, a value close to the expected fiber saturation point (FSP). Beyond MC=30%, further degradation, while apparent, was less significant. Immersion in water for one day was observed to be sufficient to achieve the FSP; under these conditions, compressive strength was observed to be 75% of that obtained from tests conducted at a standard ‘air-dry’ MC=12%. Accompanying the reduction in strength with increased MC, the bamboo was observed to transition from a relatively brittle behavior to a very ductile behavior. For scaffold applications, degradation of compression capacity is not only critical but also shown to be a conservative indicator for other mechanical properties.
Chemoresistance and immunosuppression are two major obstacles in the current anti-cancer treatments. This study investigates the involvements of a CCAAT enhancer binding protein delta (CEBPD)/vesicle ...associated membrane protein 3 (VAMP3) axis in paclitaxel (PTX) resistance and immune evasion in triple-negative breast cancer (TNBC).
PTX resistance-related genes were screened by bioinformatics. CEBPD and VAMP3 expression in clinical TNBC samples was examined by immunohistochemistry. Three PTX-resistant TNBC cell lines (MDA-MB-231/PTX, MDA-MB-468/PTX and MDA-MB-453/PTX) were generated, and their drug resistance was analyzed. Autophagy of cells was analyzed by immunofluorescence staining. Interaction between CEBPD and VAMP3 promoter was identified by immunoprecipitation and luciferase assays. The extracellular expression of programmed cell death-ligand 1 (PD-L1) in TNBC cells was detected. Extracellular vesicles (EVs) from TNBC cells were isolated to examine their effects on CD8
T cell exhaustion.
CEBPD and VAMP3 were upregulated in chemo-resistant tissue samples and in PTX-resistant TNBC cells. The CEBPD downregulation enhanced PTX sensitivity of cells. However, further upregulation of VAMP3 in cells restored PTX resistance, which was likely due to the activation of autophagy, as the autophagy antagonist chloroquine enhanced PTX sensitivity of cells. CEBPD was found to bind to the VAMP3 promoter to activate its transcription. The CEBPD/VAMP3 axis also increased the PD-L1 expression in the conditioned medium of TNBC cells. The TNBC cell-derived EVs increased the exhaustion of co-cultured CD8
T cells.
This study provides novel evidence that CEBPD plays a key role in enhancing PTX resistance in TNBC cells across various subtypes through VAMP3-mediated autophagy activation. Additionally, the CEBPD/VAMP3 axis also increases extracellular PD-L1 level, delivered by cancer cell-derived EVs, to suppress CD8
T cell-mediated anti-tumor immune response. These significant observations may provide new insights into the treatment of TNBC, suggesting CEBPD and VAMP3 as promising targets to overcome treatment resistance.
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