This study is aimed to evaluate the chemical compositions and biological activities of quinoa, a novel and excellent food crop. Quinoa extract and its fractions were prepared by ethanol extraction ...and liquid-liquid extraction, including ethanol crude extract, and petroleum ether, chloroform, ethyl acetate (EAF), and n-butanol and water fractions. The total phenolic and flavonoid contents, antioxidant activities, α-glucosidase and acetylcholinesterase inhibitory abilities of the extract and fractions were further determined. Based on these foundations, the chemical composition of the EAF fraction exhibiting the strongest functional activity was analyzed by ultra-performance liquid chromatography-mass spectrometry. The results showed the EAF fraction had the highest phenolic and flavonoid contents, and the highest antioxidant activities, as well as the strongest α-glucosidase and acetylcholinesterase inhibitory abilities, which is even better than the positive control. The phytochemical composition of the EAF fraction indicated that 661 and 243 metabolites were identified in positive and negative ion modes, which were classified into superclass, class and subclass levels, respectively. Phenolic acids and flavonoids were the major bioactive compounds in the EAF fraction. This study found that quinoa, especially its ethyl acetate fraction, had the potential for the development of natural antioxidants, acetylcholinesterase inhibitors, and hypoglycemic agents.
SnTe has attracted worldwide interest since its theoretical predication as topological crystalline insulator. Because of promising applications of one-dimensional topological insulator in nanoscale ...electronics and spintronics device, it is very important to realize the observation of topological surface states in one-dimensional SnTe. In this work, for the first time we successfully synthesized high-quality single crystalline SnTe nanowire via gold-catalyst chemical vapor deposition method. Systematical investigation of Aharonov-Bohm and Shubnikov-de Haas oscillations in single SnTe nanowire prove the existence of Dirac electrons. Further analysis of temperature-dependent Shubnikov-de Haas oscillations gives valuable information of cyclotron mass, mean-free path, and mobility of Dirac electrons in SnTe nanowire. Our study provides the experimental groundwork for research in low-dimensional topological crystalline insulator materials and paves the way for the application of SnTe nanowire in nanoelectronics and spintronics device.
Integrating two-dimensional (2D) materials into semiconductor manufacturing lines is essential to exploit their material properties in a wide range of application areas. However, current approaches ...are not compatible with high-volume manufacturing on wafer level. Here, we report a generic methodology for large-area integration of 2D materials by adhesive wafer bonding. Our approach avoids manual handling and uses equipment, processes, and materials that are readily available in large-scale semiconductor manufacturing lines. We demonstrate the transfer of CVD graphene from copper foils (100-mm diameter) and molybdenum disulfide (MoS
) from SiO
/Si chips (centimeter-sized) to silicon wafers (100-mm diameter). Furthermore, we stack graphene with CVD hexagonal boron nitride and MoS
layers to heterostructures, and fabricate encapsulated field-effect graphene devices, with high carrier mobilities of up to Formula: see text. Thus, our approach is suited for backend of the line integration of 2D materials on top of integrated circuits, with potential to accelerate progress in electronics, photonics, and sensing.
BACKGROUND:The efficacy of autologous fat transplantation is reduced by fat absorption and fibrosis that are closely related to unsatisfactory vascularization. Extracellular vesicles are key ...components of the cell secretome, which can mirror the functional and molecular characteristics of their parental cells. Growing evidence has revealed that adipose-derived mesenchymal stem cells have the ability to enhance vascularization, which is partly ascribed to extracellular vesicles. The authors evaluated whether adipose-derived mesenchymal stem cell–derived extracellular vesicles improved vascularization of fat grafts and increased their retention rate.
METHODS:To test the angiogenesis ability of adipose-derived mesenchymal stem cell–derived extracellular vesicles, they were isolated from the supernatant of cultured human adipose-derived mesenchymal stem cells and incubated with human umbilical vein endothelial cells in vitro. Then, the vesicles were co-transplanted with fat into nude mice subcutaneously. Three months after transplantation, the retention rate and inflammatory reaction of the grafts were analyzed by histologic assay.
RESULTS:The experimental group could significantly promote migration and tube formation at the concentration of 20 μg/ml. At 3 months after transplantation, the volume of the experimental group (0.12 ± 0.03 mm) was larger compared with the blank group (0.05 ± 0.01 mm). Histology and immunohistology results demonstrated significantly fewer cysts and vacuoles, less fibrosis, and more neovessels in the extracelluar vesicle group.
CONCLUSIONS:The authors co-transplanted adipose-derived mesenchymal stem cell–derived extracellular vesicles with fat into a nude mouse model and found that the vesicles improved volume retention by enhancing vascularization and regulating the inflammatory response.
While hydrogels enable a variety of applications in wearable sensors and electronic skins, they are susceptible to fatigue fracture during cyclic deformations owing to their inefficient fatigue ...resistance. Herein, acrylated β-cyclodextrin with bile acid is self-assembled into a polymerizable pseudorotaxane via precise host-guest recognition, which is photopolymerized with acrylamide to obtain conductive polymerizable rotaxane hydrogels (PR-Gel). The topological networks of PR-Gel enable all desirable properties in this system due to the large conformational freedom of the mobile junctions, including the excellent stretchability along with superior fatigue resistance. PR-Gel based strain sensor can sensitively detect and distinguish large body motions and subtle muscle movements. The three-dimensional printing fabricated sensors of PR-Gel exhibit high resolution and altitude complexity, and real-time human electrocardiogram signals are detected with high repeating stability. PR-Gel can self-heal in air, and has highly repeatable adhesion to human skin, demonstrating its great potential in wearable sensors.
Defects play a crucial role in determining electric transport properties of two-dimensional transition metal dichalcogenides. In particular, defect-induced deep traps have been demonstrated to ...possess the ability to capture carriers. However, due to their poor stability and controllability, most studies focus on eliminating this trap effect, and little consideration was devoted to the applications of their inherent capabilities on electronics. Here, we report the realization of robust trap effect, which can capture carriers and store them steadily, in two-dimensional MoS
Se
via synergistic effect of sulphur vacancies and isoelectronic selenium atoms. As a result, infrared detection with very high photoresponsivity (2.4 × 10
A W
) and photoswitching ratio (~10
), as well as nonvolatile infrared memory with high program/erase ratio (~10
) and fast switching time, are achieved just based on an individual flake. This demonstration of defect engineering opens up an avenue for achieving high-performance infrared detector and memory.
Nonvolatile memories based on van der Waals heterostructures have been proved to be promising candidates for next‐generation data storage devices. However, little attention has been focused on the ...structure with separated floating and control gates (the floating gates and control gates distribute at the different side of the channels), which were recently predicted to be capable of further improving device performance. Here, nonvolatile multibit optoelectronic memories are demonstrated using MoS2, hexagonal boron nitride (h‐BN), and graphene in a top‐floating‐gated structure. With separated top graphene floating gate, the devices show a large memory window (≈95 V) via sweeping gate voltage from 80 to −80 V, a high on/off ratio (≈106) with an ultralow dark current (≈10−14 A), as well as excellent retention characteristic (≈104 s) and cyclic endurance. In addition, these devices can also be erased by a laser illumination with broadband spectrum after being electrically programmed. For the multilevel storage property, 7/6 stages controlled by different electrical operations, and 13/6/3 stages by different laser pulse illuminations are gained. The obtained results show a promising performance for nonvolatile optoelectronic memory using a top‐floating‐gated structure.
A nonvolatile multibit optoelectronic memory in top‐floating‐gated van der Waals heterostructures is demonstrated. The fabricated device exhibits excellent electrical and optoelectrical memory performance, including large memory windows (95 V), a high on/off ratio (106), excellent retention (104), and multibit storage (7/6 for the electrical operation, 13/6/3 for the optical operation).
It is an important issue to explore achieving high accuracy long-term crop classification with limited historical samples. The West Liaohe River Basin (WLRB) serves as a vital agro-pastoral ecotone ...of Northern China, which experiences significant changes in crop planting structure due to a range of policy. Taking WLRB as a case study, this study constructed multidimensional features for crop classification suitable for Google Earth Engine cloud platform and proposed a method to extract main grain crops using sample augmentation and model migration in case of limited samples. With limited samples in 2017, the method was employed to train and classify crops (maize, soybean, and rice) in other years, and the spatiotemporal changes in the crop planting structure in WLRB from 2014 to 2020 were analyzed. The following conclusions were drawn: (1) Integrating multidimensional features could discriminate subtle differences, and feature optimization could ensure the accuracy and efficiency of classification. (2) By augmenting the original sample size by calculating the similarity of the time series NDVI (normalized difference vegetation index) curves, migrating the random forest model, and reselecting the samples for other years based on the model accuracy scores, it was possible to achieve a high crop classification accuracy with limited samples. (3) The main grain crops in the WLRB were primarily distributed in the northeastern and southern plains with lower elevations. Maize was the most predominant crop type with a wide distribution. The planting area of main grain crops in the WLRB exhibited an increasing trend, and national policies primarily influenced the variations of planting structure in maize and soybean. This study provides a scheme for extracting crop types from limited samples with high accuracy and can be applied for long-term crop monitoring and change analysis to support crop structure adjustment and food security.
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