Long-term instability of Li–S batteries is one of their major disadvantages compare to other secondary batteries. The reasons for the instability include dissolution of polysulfide intermediates and ...mechanical instability of the electrode film caused by volume changes during charging/discharging cycles. In this paper, we report a novel graphene–sulfur–carbon nanofibers (G-S-CNFs) multilayer and coaxial nanocomposite for the cathode of Li–S batteries with increased capacity and significantly improved long-cycle stability. Electrodes made with such nanocomposites were able to deliver a reversible capacity of 694 mA h g–1 at 0.1C and 313 mA h g–1 at 2C, which are both substantially higher than electrodes assembled without graphene wrapping. More importantly, the long-cycle stability was significantly improved by graphene wrapping. The cathode made with G-S-CNFs with a initial capacity of 745 mA h g–1 was able to maintain ∼273 mA h g–1 even after 1500 charge–discharge cycles at a high rate of 1C, representing an extremely low decay rate (0.043% per cycle after 1500 cycles). In contrast, the capacity of an electrode assembled without graphene wrapping decayed dramatically with a 10 times high rate (∼0.40% per cycle after 200 cycles). These results demonstrate that the coaxial nanocomposites are of great potential as the cathode for high-rate rechargeable Li–S batteries. Such improved rate capability and cycle stability could be attributed to the unique coaxial architecture of the nanocomposite, in which the contributions from graphene and CNFs enable electrodes with improved electrical conductivity, better ability to trap soluble the polysulfides intermediate and accommodate volume expansion/shrinkage of sulfur during repeated charge/discharge cycles.
The invention of pottery introduced fundamental shifts in human subsistence practices and sociosymbolic behaviors. Here, we describe the dating of the early pottery from Xianrendong Cave, Jiangxi ...Province, China, and the micromorphology of the stratigraphie contexts of the pottery sherds and radiocarbon samples. The radiocarbon ages of the archaeological contexts of the earliest sherds are 20,000 to 19,000 calendar years before the present, 2000 to 3000 years older than other pottery found in East Asia and elsewhere. The occupations in the cave demonstrate that pottery was produced by mobile foragers who hunted and gathered during the Late Glacial Maximum. These vessels may have served as cooking devices. The early date shows that pottery was first made and used 10 millennia or more before the emergence of agriculture.
Nitrogen-coordinated single-atom catalysts (SACs) have emerged as a frontier for electrocatalysis (such as oxygen reduction) with maximized atom utilization and highly catalytic activity. The precise ...design and operable synthesis of SACs are vital for practical applications but remain challenging because the commonly used high-temperature treatments always result in unpredictable structural changes and randomly created single atoms. Here, we develop a pyrolysis-free synthetic approach to prepare SACs with a high electrocatalytic activity using a fully π-conjugated iron phthalocyanine (FePc)-rich covalent organic framework (COF). Instead of randomly creating Fe-nitrogen moieties on a carbon matrix (Fe-N-C) through pyrolysis, we rivet the atomically well-designed Fe-N-C centers via intermolecular interactions between the COF network and the graphene matrix. The as-synthesized catalysts demonstrate exceptional kinetic current density in oxygen reduction catalysis (four times higher than the benchmark Pt/C) and superior power density and cycling stability in Zn-air batteries compared with Pt/C as air electrodes.
Here we present one of the world’s oldest examples of large-scale and formalized water management, in the case of the Liangzhu culture of the Yangtze Delta, dated at 5,300–4,300 years cal B.P. The ...Liangzhu culture represented a peak of early cultural and social development predating the historically recorded Chinese dynasties; hence, this study reveals more about the ancient origins of hydraulic engineering as a core element of social, political, and economic developments. Archaeological surveys and excavations can now portray the impressive extent and structure of dams, levees, ditches, and other landscape-transforming features, supporting the ancient city of Liangzhu, with an estimated size of about 300 ha. The results indicate an enormous collective undertaking, with unprecedented evidence for understanding how the city, economy, and society of Liangzhu functioned and developed at such a large scale. Concurrent with the evidence of technological achievements and economic success, a unique relationship between ritual order and social power is seen in the renowned jade objects in Liangzhu elite burials, thus expanding our view beyond the practicalities of water management and rice farming.
China's historiographical traditions tell of the successful control of a Great Flood leading to the establishment of the Xia dynasty and the beginning of civilization. However, the historicity of the ...flood and Xia remain controversial. Here, we reconstruct an earthquake-induced landslide dam outburst flood on the Yellow River about 1920 BCE that ranks as one of the largest freshwater floods of the Holocene and could account for the Great Flood. This would place the beginning of Xia at ∼1900 BCE, several centuries later than traditionally thought. This date coincides with the major transition from the Neolithic to Bronze Age in the Yellow River valley and supports hypotheses that the primary state-level society of the Erlitou culture is an archaeological manifestation of the Xia dynasty.
DNA methylation plays a pivotal role in regulating cellular processes, and altered DNA methylation pattern is a general hallmark of cancer. However, DNA methylome in circulating tumor cells (CTCs) is ...still a mystery due to the lack of proper analytical techniques. We introduced an efficient workflow, LCM-µWGBS, which can efficiently profile the DNA methylation of microdissected CTC samples. LCM-µWGBS combines the laser capture microdissection (LCM)-based CTC capture method and whole-genome bisulfite sequencing in very small CTC population (µWGBS) to gain insight into the DNA methylation landscape of CTCs. We herein profiled the DNA methylome of CTCs from lung cancer patients. Deriving from a comprehensive analysis of CTC methylome, a unique "CTC DNA methylation signature" that is distinct from primary lung cancer tissues was identified. Further analysis showed that promoter hypermethylation of epithelial genes is a hallmark of stable epithelial-mesenchymal transition process. Moreover, it has been suggested that CTCs are endowed with a stemness-related feature during dissemination and metastasis. This work constitutes a unique DNA methylation analysis of CTCs at single base-pair resolution, which might facilitate to propose noninvasive CTC DNA methylation biomarkers contributing to clinical diagnosis.
The reliability and validity of Vis-NIR hyperspectral imaging were investigated for the determination of heavy metal content in tomato leaves under different cadmium stress. Besides, a method ...involving wavelet transform and least square support vector machine regression (WT-LSSVR) is proposed to select the optimal wavelength and establish the detection model. The Vis-NIR hyperspectral images of 405 tomato leaf samples were obtained and the whole region of tomato leaf sample spectral data was collected and preprocessed. In addition, WT-LSSVR is used to select optimal wavelength and establish the detection model using db4 and db6 as wavelet basis function, respectively. Furthermore, the best prediction performances for detecting cadmium (Cd) content in tomato leaves was obtained by second derivative (2nd Der) pre-processing method, with Rc2 of 0.9437, RMSEC of 0.0988 mg/kg, Rp2 of 0.8937, RMSEP of 0.2331 mg/kg, Rcv2 of 0.9357, RMSECV of 0.1455 mg/kg, RPD of 3.081 and bias of 0.00863 using db6 (daubechies 6) as wavelet basis function with wavelet fourth layer decomposition. The results of this study indicated that WT-LSSVR can effectively select the optimal wavelength and Vis-NIR hyperspectral imaging has great potential for detecting heavy metal content in tomato leaves under different cadmium stresses.
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•WT-LSSVR is proposed to select the optimal wavelength and establish the detection model.•There is a correlation between the spectrum and cadmium content in tomato leaves.•Vis-NIR hyperspectral imaging has great potential for detecting heavy metal content.
Abstract
Aims
Inadequate autophagy contributed to endothelial dysfunction in diabetic patients. We aimed to investigate the relationship between inadequate autophagy and endothelial cells (ECs) ...apoptosis in diabetes and its underlying mechanism.
Methods and results
Aortic intima and ECs were isolated from diabetic patients. Cultured human aortic endothelial cells (HAECs) were stimulated with advanced glycation end products (AGEs). The expression of autophagy and apoptosis-related proteins were determined by western blotting. Autophagosomes were observed by electron microscopy. The fusion of autophagosome and lysosomes was detected by immunofluorescence. Compared with non-diabetic subjects, the levels of LC3-II, p62, FoxO1, and Ac-FoxO1 were increased in ECs from diabetic patients, accompanied by the decreased expressions of Atg14, STX17, and co-localization of LC3-II/LAMP2 and Atg14/STX17. Long-term stimulation with AGEs up-regulated LC3-II and p62 expression and the number of autophagosomes with decreased level of Atg14, STX17, Ras-related protein 7 (Rab7), and co-localization of LC3-II/LAMP2 and Atg14/STX17 in HAECs. The apoptosis rates were increased with elevated cleaved-caspase-3 and declined Bcl-2 expression. Inhibition of autophagy with 3-methyladenine could reduce long-term AGEs-induced apoptosis. Higher levels of FoxO1, Ac-FoxO1, and Ac-FoxO1 binding to Atg7 were detected in AGEs-treated HAECs. AGEs-induced FoxO1 enhanced Akt activity, decreased SIRT1-deacetylase activity by phosphorylation and elevated Ac-FoxO1. Knockout of FoxO1 reduced AGEs-induced autophagy and promoted the expression of Atg14 and the co-localization of LC3-II/LAMP 2 and Atg14/STX17.
Conclusion
Inadequate autophagy with impaired autophagosome-lysosomal fusion exists in aortic intima and ECs from diabetic patients. FoxO1 mediates AGEs-induced ECs autophagic apoptosis through impairing autophagosome-lysosomes fusion by inhibiting Atg14 expression.
In order to effectively realize the spectral detection of heavy metal content, a deep learning method which consisted of stacked auto-encoders (SAE) and partial least squares support vector machine ...regression (LSSVR) is proposed to obtain depth features and establish cadmium (Cd) detection model. The Vis-NIR hyperspectral images of 1120 lettuce leaf samples were obtained and the whole region of lettuce leaf sample spectral data was collected and preprocessed with different spectral pre-treatment methods. Successive projections algorithm (SPA), partial least squares regression (PLSR) and SAE were used to acquire the optimum wavelength, respectively. Besides, the characteristic wavelengths were used to build partial least squares support vector machine regression (LSSVR) models. Furthermore, the best prediction performance for detecting Cd content in lettuce leaves was obtained by Savitzky-Golay combined with first derivative (SG-1st) pre-processing method, with Rp2 of 0.9487, RMSEP of 0.01049 mg/kg and RPD of 3.330 using SAE-LSSVR method. The results of this study indicated that deep learning method coupled with hyperspectral imaging technique has great potential for detecting heavy metal content in lettuce leaves.
•Vis-NIR hyperspectral imaging was used to detect Cd content in lettuce leaves.•SAE-LSSVR is proposed to establish depth feature regression model.•Deep learning has a great potential for the identification of Cd content.
Northern maize leaf blight is one of the major diseases that endanger the health of maize. The complex background of the field and different light intensity make the detection of diseases more ...difficult. A multi-scale feature fusion instance detection method, based on convolutional neural network, is proposed to detect maize leaf blight. The proposed technique incorporates three major steps of data set preprocessing part, fine-tuning network and detection module. In the first step, the improved retinex is used to process data sets, which successfully solves the problem of poor detection effects caused by high-intensity light. In the second step, the improved RPN is utilized to adjust the anchor box of diseased leaves. The improved RPN network identifies and deletes negative anchors, which reduces the search space of the classifier and provides better initial information for the detection network. In this paper, a transmission module is designed to connect the fine-tuning network with the detection module. On the one hand, the transmission module fuses the features of the low-level and high-level to improve the detection accuracy of small target diseases. On the other hand, the transmission module converts the feature map associated with the fine-tuning network to the detection module, thus realizing the feature sharing between the detection module and the fine-tuning network. In the third step, the detection module takes the optimized anchor as input, focuses on detecting the diseased leaves. By sharing the features of the transmission module, the time-consuming process of using candidate regions layer by layer to detect is eliminated. Therefore, the efficiency of the whole model has reached the efficiency of the one-stage model. In order to further optimize the detection effect of the model, we replace the loss function with generalized intersection over union (GIoU). After 60000 iterations, the highest mean average precision (mAP) reaches 91.83%. The experimental results indicate that the improved model outperforms several existing methods in terms of greater precision and frames per second (FPS).
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