Perovskite light-emitting diodes (PeLEDs) with an external quantum efficiency exceeding 20% have been achieved in both green and red wavelengths
; however, the performance of blue-emitting PeLEDs ...lags behind
. Ultrasmall CsPbBr
quantum dots are promising candidates with which to realize efficient and stable blue PeLEDs, although it has proven challenging to synthesize a monodispersed population of ultrasmall CsPbBr
quantum dots, and difficult to retain their solution-phase properties when casting into solid films
. Here we report the direct synthesis-on-substrate of films of suitably coupled, monodispersed, ultrasmall perovskite QDs. We develop ligand structures that enable control over the quantum dots' size, monodispersity and coupling during film-based synthesis. A head group (the side with higher electrostatic potential) on the ligand provides steric hindrance that suppresses the formation of layered perovskites. The tail (the side with lower electrostatic potential) is modified using halide substitution to increase the surface binding affinity, constraining resulting grains to sizes within the quantum confinement regime. The approach achieves high monodispersity (full-width at half-maximum = 23 nm with emission centred at 478 nm) united with strong coupling. We report as a result blue PeLEDs with an external quantum efficiency of 18% at 480 nm and 10% at 465 nm, to our knowledge the highest reported among perovskite blue LEDs by a factor of 1.5 and 2, respectively
.
Anthocyanins are water-soluble natural pigments with good antioxidant and antibacterial properties, and their colors are pH sensitive to the environment. At present, the use of plant anthocyanins to ...prepare active and smart packaging film has attracted increasing attention in the field of food engineering. The use of anthocyanin-based pH-sensitive smart packaging films can not only effectively prolong the shelf life, but also monitor the freshness of food. This review mainly summarizes the mostly used packaging materials, preparation, structural and physicochemical properties, and the applications of anthocyanin-based films as pH-sensitive smart packaging for monitoring food freshness.
Display omitted
•Biopolymers and their combinations are widely used in food packaging industry.•Anthocyanins (ACNs) can be used to develop pH-sensitive smart packaging films.•The film preparation technique should ensure the chemical stability of ACNs.•The structural and physicochemical properties of the films are correlated with ACNs.•ACN-based smart packaging facilitates real-time and visual food freshness monitoring.
In this paper, calcination and subsequent acid treatment were performed on halloysite to investigate their effects on dynamic benzene adsorption performance. Calcination at 800 °C had little effect ...on halloysite's tubular morphology, but it caused dehydroxylation and phase separation of amorphous SiO2 and Al2O3. The occurrence of dehydroxylation resulted in removal of hydroxyl groups, which reduced halloysite's hydrophilicity, leading to an improvement in the halloysite's affinity for hydrophobic benzene molecules. The dynamic benzene adsorption capacity increased from 68.1 mg/g in the original halloysite to 103.6 mg/g in the calcined halloysite. The acid treatment after pre-calcination preserved the halloysite's tubular morphology and introduced massive micropores as a result of the rapid dissolution of Al2O3 layers. The emergence of these massive micropores substantially improved the specific surface area and dynamic benzene adsorption capacity of the acid-treated calcined halloysite, which reached 472.3 m2/g and 204.2 mg/g, respectively. In addition, the recycling efficiency of the acid-treated calcined halloysite for benzene adsorption reached 92.5%, thus displaying good regeneration performance. These results demonstrate that calcination and subsequent acid treatment play important roles in promoting the halloysite's benzene adsorption performance, which makes the resulting halloysite a promising adsorbent for the treatment of volatile organic compounds.
Display omitted
•The effects of calcination and acid treatment on the benzene adsorption by halloysite were studied.•Calcination improved the affinity of halloysite for benzene molecule.•Acid treatment after pre-calcination preserved the tubular morphology of halloysite and generated massive micropores.•The acid-treated calcined halloysite exhibited excellent dynamic benzene adsorption performance.•The acid-treated calcined halloysite possessed good reusability for benzene adsorption.
Using generative adversarial network (GAN) Goodfellow et al. (2014) for data enhancement of medical images is significantly helpful for many computer-aided diagnosis (CAD) tasks. A new GAN-based ...automated tampering attack, like CT-GAN Mirsky et al. (2019), has emerged. It can inject or remove lung cancer lesions to CT scans. Because the tampering region may even account for less than 1% of the original image, even state-of-the-art methods are challenging to detect the traces of such tampering. This paper proposes a two-stage cascade framework to detect GAN-based medical image small region forgery like CT-GAN. In the local detection stage, we train the detector network with small sub-images so that interference information in authentic regions will not affect the detector. We use depthwise separable convolution and residual networks to prevent the detector from over-fitting and enhance the ability to find forged regions through the attention mechanism. The detection results of all sub-images in the same image will be combined into a heatmap. In the global classification stage, using gray-level co-occurrence matrix (GLCM) can better extract features of the heatmap. Because the shape and size of the tampered region are uncertain, we use hyperplanes in an infinite-dimensional space for classification. Our method can classify whether a CT image has been tampered and locate the tampered position. Sufficient experiments show that our method can achieve excellent performance than the state-of-the-art detection methods.
Aiming at the problems of Uyghur oblique deformation, character adhesion and character similarity in scene images, this paper proposes a scene Uyghur recognition model with enhanced visual ...prediction. First, the content-aware correction network TPS++ is used to perform feature-level correction for skewed text. Then, ABINet is used as the basic recognition network, and the U-Net structure in the vision model is improved to aggregate horizontal features, suppress multiple activation phenomena, better describe the spatial characteristics of character positions, and alleviate the problem of character adhesion. Finally, a visual masking semantic awareness (VMSA) module is added to guide the vision model to consider the language information in the visual space by masking the corresponding visual features on the attention map to obtain more accurate visual prediction. This module can not only alleviate the correction load of the language model, but also distinguish similar characters using the language information. The effectiveness of the improved method is verified by ablation experiments, and the model is compared with common scene text recognition methods and scene Uyghur recognition methods on the self-built scene Uyghur dataset.
•Allophane is readily dissolved in acidic conditions, especially in pH < 3.0.•Destruction of allophane structure decreases the porosity of allophane.•A conceptual model regarding allophane changes in ...acidic conditions is proposed.•Better understanding of the behavior and properties of allophane in acidified allophanic Andosols.
Acidification of allophanic Andosols has significant effects on their physicochemical properties and productivity. Understanding of the acidification and related effects is limited by the structural changes of allophane – the major mineral composition of allophanic Andosols. In this work, we systematically investigated the structural stability of allophane and the mechanisms of structural changes under different acidic conditions (initial pH 4.0–2.0) by using chemical analysis, transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, solid-state magic-angle-spinning nuclear magnetic resonance, and N2 physisorption analysis. The results indicated that the structure of allophane was readily altered in acidic conditions. Acid leaching in conditions with initial pH > 3.0 only dissolved some polymerized silicates from allophane, enlarging the defect pores. By contrast, the dissolution of the imogolite-like local structure was observed in strongly acidic conditions (initial pH < 3.0) and released large amounts of Al and Si, which can further enlarge defect pores or even make hollow spherules collapse followed by the precipitation of amorphous silica. As a result, the microporous parameters increased, reaching maxima in Allo2.2, while the total porosity and specific surface area of products decreased with the decrease of initial pH of the leaching solutions. These changes are supposed to diminish the adsorption and storage capacities of guest species of allophane. These findings suggest that the rapid responsiveness of allophane to acid supposedly plays a crucial role in the acid buffering capacity of allophanic Andosols and that the structural destruction of allophane may significantly contribute to Al toxicity and to breaking the porous structure of acidified allophanic Andosols. For the management of allophanic Andosols, prudent measures should be taken to protect the allophane structure. And it is possible to restore the soil productivity of weakly acidified allophanic Andosols through soil remediation.
Lysine acetylation is a frequently occurring post-translational modification (PTM), emerging as an important metabolic regulatory mechanism in prokaryotes. This process is achieved enzymatically by ...the protein acetyltransferase (KAT) to specifically transfer the acetyl group, or non-enzymatically by direct intermediates (acetyl phosphate or acetyl-CoA). Although lysine acetylation modification of glucosyltransferases (Gtfs), the important virulence factor in Streptococcus mutans, was reported in our previous study, the KAT has not been identified. Here, we believe that the KAT ActG can acetylate Gtfs in the enzymatic mechanism. By overexpressing 15 KATs in S. mutans, the synthesized water-insoluble extracellular polysaccharides (EPS) and biofilm biomass were measured, and KAT (actG) was identified. The in-frame deletion mutant of actG was constructed to validate the function of actG. The results showed that actG could negatively regulate the water-insoluble EPS synthesis and biofilm formation. We used mass spectrometry (MS) to identify GtfB and GtfC as the possible substrates of ActG. This was also demonstrated by in vitro acetylation assays, indicating that ActG could increase the acetylation levels of GtfB and GtfC enzymatically and decrease their activities. We further found that the expression level of actG in part explained the virulence differences in clinically isolated strains. Moreover, overexpression of actG in S. mutans attenuated its cariogenicity in the rat caries model. Taken together, our study demonstrated that the KAT ActG could induce the acetylation of GtfB and GtfC enzymatically in S. mutans, providing insights into the function of lysine acetylation in bacterial virulence and pathogenicity.
Neuroinflammation-induced injury is intimately associated with poor prognosis in patients with cerebral venous sinus thrombosis (CVST). The cyclic GMP-AMP synthase-stimulator of interferon gene ...(cGAS-STING) axis is a cytoplasmic double-stranded DNA (dsDNA) sensing pathway has recently emerged as a crucial mediator of neuroinflammation in ischemic stroke. However, the role of the cGAS-STING pathway in modulating post-CVST inflammation and the underlying mechanisms involved remain unclear.
A CVST model was induced by ferric chloride in male C57BL/6J mice. The selective cGAS inhibitor RU.521, STING agonist 2'3'-cGAMP, and STING siRNA were delivered by intranasal administration or intraventricular injection. Post-CVST assessments included rotarod test, TUNEL staining, Fluoro-Jade C staining, dihydroethidium staining, western blotting, qPCR, immunofluorescence, immunohistochemistry, ELISA and flow cytometry.
cGAS, STING, NLRP3 and GSDMD were significantly upregulated after CVST and mostly in the microglia of the mouse brain. CVST triggered the release of dsDNA into the cytoplasm and elicited an inflammatory response via activating the cGAS-STING axis. RU.521 decreased the levels of 2'3'-cGAMP, STING and downstream inflammatory cytokines, and suppressed the expressions of NLRP3 inflammasome and pyroptosis-pertinent components containing cleaved caspase-1, GSDMD, GSDMD-C, pro- and cleaved IL-1β, and cleaved IL-1β/pro-IL-1β. Besides, RU.521 treatment also reduced oxidative stress, lessened the numbers of microglia and neutrophils, and ameliorated neuronal apoptosis, degeneration along with neurological deficits post-CVST. 2'3'-cGAMP delivery enhanced the expressions of STING and related inflammatory mediators, NLRP3 inflammasome and pyroptosis-relevant proteins, whereas these alterations were significantly abrogated by the silencing of STING by siRNA.
Our data demonstrate that repression of the cGAS-STING pathway diminishes the neuroinflammatory burden of CVST and highlight this approach as a potential therapeutic tactic in CVST-mediated pathologies.
Constrained image splicing detection and localization (CISDL) is a newly formulated image forensics task and plays an important role in verifying the generating process of a forged image. CISDL ...conducts dense matching between two investigated images and detects whether one image has forged regions pasted from the other. In this work, we introduce a novel attention-aware encoder-decoder deep matching network named as AttentionDM for CISDL. An encoder-decoder with atrous convolution is newly designed for hierarchical features dense matching and fine-grained masks generation. A novel attention-aware correlation computation module is built on normalization operations and informative features recalibration with channel attention blocks. Last but not least, VGG and ResNets are respectively formulated as feature extractors for comprehensive comparisons in CISDL. Extensive experiments demonstrate the superior performance of AttentionDM over the state-of-the-art methods.
In this study, a series of bacteria capable of degrading starch and cellulose were isolated from the aging flue-cured tobacco leaves. Remarkably, there was a thermophilic bacterium,
Bacillus subtilis
...ZIM3, that can simultaneously degrade both starch and cellulose at a wide range of temperature and pH values. Genome sequencing, comparative genomics analyses, and enzymatic activity assays showed that the ZIM3 strain expressed a variety of highly active plant biomass-degrading enzymes, such as the amylase AmyE1 and cellulase CelE1. The
in vitro
and PhoA-fusion assays indicated that these enzymes degrading complex plant biomass into fermentable sugars were secreted into ambient environment to function. Besides, the amylase and cellulase activities were further increased by three- to five-folds by using overexpression. Furthermore, a fermentation strategy was developed and the biodegradation efficiency of the starch and cellulose in the tobacco leaves were improved by 30–48%. These results reveal that
B. subtilis
ZIM3 and the recombinant strain exhibited high amylase and cellulase activities for efficient biodegradation of starch and cellulose in tobacco and could potentially be applied for industrial tobacco fermentation.
PDF
