The size of C‐nanodots can be electrochemically tuned by changing the applied potential during their preparation. The higher the applied potential, the smaller the resulting C‐nanodots. Moreover, the ...surface oxidation degree of the C‐nanodots can also be electrochemically tuned. The red‐shift of emission independent of the size provides an insight into the luminescence mechanism of C‐nanodots.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Ag2S quantum dots (QDs) are well‐known near‐infrared fluorophores and have attracted great interest in biomedical labeling and imaging in the past years. However, their photoluminescence efficiency ...is hard to compete with Cd‐, Pb‐based QDs. The high Ag+ mobility in Ag2S crystal, which causes plenty of cation deficiency and crystal defects, may be responsible mainly for the low photoluminescence quantum yield (PLQY) of Ag2S QDs. Herein, a cation‐doping strategy is presented via introducing a certain dosage of transition metal Pb2+ ions into Ag2S nanocrystals to mitigate this intrinsic shortcoming. The Pb‐doped Ag2S QDs (designated as Pb:Ag2S QDs) present a renovated crystal structure and significantly enhanced optical performance. Moreover, by simply adjusting the levels of Pb doping in the doped nanocrystals, Pb:Ag2S QDs with bright emission (PLQY up to 30.2%) from 975 to 1242 nm can be prepared without altering the ultrasmall particle size (≈2.7–2.8 nm). Evidently, this cation‐doping strategy facilitates both the renovation of crystal structure of Ag2S QDs and modulation of their optical properties.
Both the crystal structure and optical properties of narrow bandgap semiconductor Ag2S QDs have a revolutionary change upon the doping of transition metal Pb2+ ions. The ultrasmall size (≈2.7–2.8 nm), bright tunable emission (975–1242 nm), excellent stability and decent biocompatibility of the Pb‐doped Ag2S QDs render this material a promising application prospect in in vivo fluorescence‐based imaging.
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In recent years, a broad range of nanocrystals have been synthesized in droplet-based microfluidic reactors which provide obvious advantages, such as accurate manipulation, better reproducibility and ...reliable automation. In this review, we initially introduce general concepts of droplet reactors followed by discussions of their main functional regions including droplet generation, mixing of reactants, reaction controlling,
in situ
monitoring, and reaction quenching. Subsequently, the enhanced mass and heat transport properties are discussed. Next, we focus on research frontiers including sequential multistep synthesis, intelligent synthesis, reliable scale-up synthesis, and interfacial synthesis. Finally, we end with an outlook on droplet reactors, especially highlighting some aspects such as large-scale production, the integrated process of synthesis and post-synthetic treatments, automated droplet reactors with
in situ
monitoring and optimizing algorithms, and rapidly developing strategies for interfacial synthesis.
Different synthetic strategies derived from droplet reactors with integrated functional regions for NC synthesis.
Organic single‐crystalline semiconductors with long‐range periodic order have attracted much attention for potential applications in electronic and optoelectronic devices due to their high carrier ...mobility, highly thermal stability, and low impurity content. Molecular doping has been proposed as a valuable strategy for improving the performance of organic semiconductors and semiconductor‐based devices. However, a fundamental understanding of the inherent doping mechanism is still a key challenge impeding its practical application. In this study, solid evidence for the “perfect” substitutional doping mechanism of the stacking mode between the guest and host molecules in organic single‐crystalline semiconductors using polarized photoluminescence spectrum measurements and first‐principles calculations is provided. The molecular host–guest doping is further exploited for efficient color‐tunable and even white organic single‐crystal‐based light‐emitting devices by controlling the doping concentration. The clarification of the molecular doping mechanism in organic single‐crystalline semiconductor host–guest system paves the way for their practical application in high‐performance electronic and optoelectronic devices.
A fundamental understanding of the molecular doping mechanism in organic single‐crystalline semiconductors is provided using polarized PL spectrum measurement and first‐principles calculations. Color‐tunable and white single‐crystal‐based organic light‐emitting devices with high performance are realized, which have important implications for the practical application of organic single‐crystalline semiconductors.
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Telocytes (TCs), a distinct type of interstitial (stromal) cells, have been discovered in many organs of human and mammal animals. TCs, which have unique morphological characteristics and abundant ...paracrine substance, construct a three-dimensional (3D) interstitial network within the stromal compartment by homocellular and heterocellular communications which are important for tissue homeostasis and normal development. Fibrosis-related diseases remain a common but challenging problem in the field of medicine with unclear pathogenesis and limited therapeutic options. Recently, increasing evidences suggest that where TCs are morphologically or numerically destructed, many diseases continuously develop, finally lead to irreversible interstitial fibrosis. It is not difficult to find that TCs are associated with chronic inflammation and fibrosis. This review mainly discusses relationship between TCs and the occurrence of fibrosis in various diseases. We analyzed in detail the potential roles and speculated mechanisms of TCs in onset and progression of systemic fibrosis diseases, as well as providing the most up-to-date research on the current therapeutic roles of TCs and involved related pathways. Only through continuous research and exploration in the future can we uncover its magic veil and provide strategies for treatment of fibrosis-related disease.
Recent studies have identified a class of small non‐coding RNA molecules, named microRNA (miRNA), that is dysregulated in malignant brain glioblastoma. Substantial data have indicated that miRNA‐16 ...(miR‐16) plays a significant role in tumors of various origins. This miRNA has been linked to various aspects of carcinogenesis, including cell apoptosis and migration. However, the molecular functions of miR‐16 in gliomagenesis are largely unknown. We have shown that the expression of miR‐16 in human brain glioma tissues was lower than in non‐cancerous brain tissues, and that the expression of miR‐16 decreased with increasing degrees of malignancy. Our data suggest that the expression of miR‐16 and nuclear factor (NF)‐κB1 was negatively correlated with glioma levels. MicroRNA‐16 decreased glioma malignancy by downregulating NF‐κB1 and MMP9, and led to suppressed invasiveness of human glioma cell lines SHG44, U87, and U373. Our results also indicated that upregulation of miR‐16 promoted apoptosis by suppressing BCL2 expression. Finally, the upregulation of miR‐16 in a nude mice model of human glioma resulted in significant suppression of glioma growth and invasiveness. Taken together, our experiments have validated the important role of miR‐16 as a tumor suppressor gene in glioma growth and invasiveness, and revealed a novel mechanism of miR‐16‐mediated regulation in glioma growth and invasiveness through inhibition of BCL2 and the NF‐κB1/MMP‐9 signaling pathway. Therefore, our experiments suggest the possible future use of miR‐16 as a therapeutic target in gliomas.
We first report that miR‐16 and NF‐κB1expression were inversely correlated to glioma levels in the same patient samples. We further identified the miR‐16 as a negative regulator of tumor growth and invasion, both in vitro and in vivo. Mechanistically the tumor‐suppressive role of miR‐16 can be attributed to inhibition of BCL‐2 and NF‐kappaB1/MMP9 signaling pathways.
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The integration of 2D covalent organic frameworks (COFs) with atomic thickness with graphene will lead to intriguing two‐dimensional materials. A surface‐confined covalently bonded Schiff base ...network was prepared on single‐layer graphene grown on copper foil and the dynamic reaction process was investigated with scanning tunneling microscopy. DFT simulations provide an understanding of the electronic structures and the interactions between the surface COF and graphene. Strong coupling between the surface COF and graphene was confirmed by the dispersive bands of the surface COF after interaction with graphene, and also by the experimental observation of tunneling condition dependent contrast of the surface COF.
Co‐condensation between benzene‐1,3,5‐tricarbaldehyde and p‐phenylenediamine on a graphene surface leads to a surface covalent organic framework (COF) with single‐layer thickness. Strong coupling between the surface COF and graphene was confirmed by the significant mixing of states and the relatively large interaction energy revealed by STM and DFT simulation.
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The climate history of the Alxa desert of northwestern China must be sought both in recent instrumental records (dating from 1960) and in high‐resolution proxy data. Climate proxies are scarce in ...desert areas; however, long‐lived desert shrubs can offer one such proxy. We have used shrub‐ring data from Zygophyllum xanthoxylum, collected in the central Alxa desert, to reconstruct the Self‐calibrating Palmer Drought Severity Index (scPDSI) for the period 1880–2015. The data covers the May–July growth season. When we compared the history constructed from the shrub‐ring data with the instrumental data collected 1960–2015, we found that the reconstructed history explained 41% of the variance in scPDSI data (40% after adjusting for loss of degrees of freedom). The reconstructed history shows that this region has experienced six persistent droughts and four seasons wetter than usual during the period under study. Of note is a severe drought event in 1920s that affected much of northern China (as noted in contemporary documents). The droughts and wet seasons identified in our reconstruction are consistent with reports from other researchers who have studied the climate history or the region. Our study suggests that it is feasible to reconstruct climate history using shrub‐ring data from long‐lived desert shrubs.
Radial growth of long‐lived desert shrubs, Zygophyllum xanthoxylum was mainly affected by the pre‐growing‐season and growing‐season precipitation. It provides opportunity to reconstruct the climate history in the desert hinterland. The first attempt to reconstruct a regional history of scPDSI using Z. xanthoxylum shrub‐ring‐width records. The reconstruction spans the years 1880–2015.
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As an important passive radio monitoring and positioning technology, direction-of-arrival (DOA) estimation has always been a key problem in theoretical research and practice, and many algorithms have ...been developed under additive Gaussian noise environments. However, when the noise exhibits obvious impulsivity, the performance of these algorithms decreases significantly. To suppress impulsive noise, a new correntropy-based adaptive weight factor is derived. Furthermore, a new multilayer deep neural network (DNN) framework is constructed, and a DNN-based DOA estimator is proposed to realize DOA estimation under impulsive noise environments. Experiments results show that the proposed algorithm is significantly better than the existing algorithms in terms of DOA estimation accuracy and robustness.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
t is of great significance for gully prevention and management to identify the potential sediment source of debris flow. Debris flow in a gully always originates from tributaries that have different ...gravity potential energies and sediment condition. In this study, tributaries of the Jiangjia Gully (JJG) in Yunnan province, China, are taken as the study area to determine the possible sediment sources of debris flow. It was found that tributaries with a high evolution index (EI, the integral of the hypsometric curve) always had high gravity potential energy, which favors the occurrence of landslide activity. Furthermore, the relationship between sediment distribution, gravity potential energy, and EI is compared, respectively. The results showed that the EI had a greater influence on the occurrence of landslides, and sediments were concentrated in tributaries with EI between 0.5 and 0.6. Accordingly, tributaries with EI > 0.5 were identified as the sediment sources of debris flow. In addition, the shape of a tributary was related to EI and can reflect the condition of water and sediment storage.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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