Perovskite light‐emitting diodes (PeLEDs) show great application potential in high‐quality flat‐panel displays and solid‐state lighting due to their steadily improved efficiency, tunable colors, ...narrow emission peak, and easy solution‐processing capability. However, because of high optical confinement and nonradiative charge recombination during electron–photon conversion, the highest reported efficiency of PeLEDs remains far behind that of their conventional counterparts, such as inorganic LEDs, organic LEDs, and quantum‐dot LEDs. Here a facile route is demonstrated by adopting bioinspired moth‐eye nanostructures at the front electrode/perovskite interface to enhance the outcoupling efficiency of waveguided light in PeLEDs. As a result, the maximum external quantum efficiency and current efficiency of the modified cesium lead bromide (CsPbBr3) green‐emitting PeLEDs are improved to 20.3% and 61.9 cd A−1, while retaining spectral and angular independence. Further reducing light loss in the substrate mode using a half‐ball lens, efficiencies of 28.2% and 88.7 cd A−1 are achieved, which represent the highest values reported to date for PeLEDs. These results represent a substantial step toward achieving practical applications of PeLEDs.
Highly efficient perovskite light‐emitting diodes are achieved by implementing a simple and cost‐effective method for efficient outcoupling of waveguided light. A record external quantum efficiency of 28.2% is realized for the device based on cesium lead bromide (CsPbBr3), while retaining the same spectral response for broad viewing angles.
Natural product analysis has gained wide attention in recent years, especially for herbal medicines, which contain complex ingredients and play a significant clinical role in the therapy of numerous ...diseases. The constituents of natural products are usually found at low concentrations, and the matrices are complex. Thus, the extraction of target compounds from natural products before analysis by analytical instruments is very significant for human health and its wide application. The commonly used traditional extraction methods are time‐consuming, using large amounts of sample and organic solvents, as well as expensive and inefficient. Recently, microextraction techniques have been used for natural product extraction to overcome the disadvantages of conventional extraction methods. In this paper, the successful applications of and recent developments in microextraction techniques including solvent‐based and sorbent‐based microextraction methods, in natural product analysis in recent years, especially in the last 5 years, are reviewed for the first time. Their features, advantages, disadvantages, and future development trends are also discussed.
The direct amination of cyanohydrins with amines
via
a catalytic cyano-borrowing reaction was developed. The transformation features broad substrate scope, excellent functional group compatibility, ...and very mild and simple operations. Moreover, a titanium catalyst supported by quinine and (
S
)-BINOL ligands enabled an asymmetric cyano-borrowing reaction with moderate to high enantioselectivity.
The direct amination was developed of cyanohydrins with amines
via
catalytic cyano-borrowing reaction based on the use of a titanium catalyst supported by quinine and (
S
)-BINOL ligands.
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Experimental evidence has shown that per- and polyfluoroalkyl substances (PFAS) alternatives and mixtures may exert hepatotoxic effects in animals. However, epidemiological evidence ...is limited. This research aimed to explore associations of PFAS and the alternatives with liver function in a general adult population. The study participants consisted of 1,303 adults from a community-based cross-sectional investigation in Guangzhou, China, from November 2018 to August 2019. We selected 13 PFAS with detection rates > 85% in serum samples and focused on perfluorooctane-sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and their alternatives 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), 8:2 Cl-PFESA, and perfluorohexanoic acid (PFHxA) as predictors of outcome. Six liver function biomarkers (ALB, ALT, AST, GGT, ALP, and DBIL) were chosen as outcomes. We applied regression models with restricted cubic spline function to explore correlations between single PFAS and liver function and inspected the combined effect of PFAS mixtures on liver by applying Bayesian kernel machine regression (BKMR). We discovered positive associations among PFAS and liver function biomarkers except for ALP. For example, compared with the 25th percentile of PFAS concentration, the level of ALT increased by 12.36% (95% CI: 7.91%, 16.98%) for ln-6:2 Cl-PFESA, 5.59% (95% CI: 2.35%, 8.92%) for ln-8:2 Cl-PFESA, 3.56% (95% CI: −0.39%, 7.68%) for ln-PFHxA, 13.91% (95% CI: 8.93%, 19.13%) for ln-PFOA, and 14.25% (95% CI: 9.91%, 18.77%) for ln-PFOS at their 75th percentile. In addition, higher exposed serum PFAS was found to be correlated with greater odds of abnormal liver function. Analysis from BKMR models also showed an adverse association between PFAS mixtures and liver function. The combined effect of the PFAS mixture appeared to be non-interactive, in which PFOS was the main contributor to the overall effect. Our findings provide evidence of associations between PFAS alternatives, PFAS mixtures, and liver function in the general adult population.
A parametric experimental study has been conducted to investigate the effect of polypropylene fiber on the workability and durability of the concrete composite containing fly ash and silica fume. ...Four different fiber volume fractions (0.06%, 0.08%, 0.1% and 0.12%) were used. The results indicate that the addition of polypropylene fiber has a little adverse effect on the workability of concrete composite containing fly ash and silica fume. With the increase of fiber volume fraction, both of the slump and slump flow are decreasing gradually. However, the addition of polypropylene fiber has greatly improved the durability of the concrete composite containing fly ash and silica fume. The length of water permeability, the dry shrinkage strain and the carbonation depth of concrete containing fly ash and silica fume are decreasing gradually with the increase of fiber volume fraction as the fiber volume fraction is below 0.12%. Besides, freeze–thaw resistance of polypropylene fiber reinforced concrete containing fly ash and silica fume was found to slightly increase when compared to the concrete composite without fibers. Moreover, there is a tendency of increase in the freeze–thaw resistance with the increase of fiber volume fraction as the fiber volume fraction is below 0.08%. However, the freeze–thaw resistance begins to decrease slightly after the fiber volume fraction beyond 0.08%.
This paper considers a dual channel supply chain consisting of a risk-neutral supplier and a risk-averse retailer, in which the market demand is uncertain and the supplier opens an e-channel, thus ...directly participating in the market. At the beginning of the sales season, the supplier and the retailer construct their initial stocks, and they follow a consistent pricing strategy. Under the Value-at-Risk (VaR) criterion and the Conditional Value-at-Risk (CVaR) criterion, we formulate the problem as a Stackelberg game model and obtain the equilibrium solutions in the decentralized and centralized situations. Based on the advantage of the CVaR measure, we further explore the effects of the retailer's risk indicator on the retail price, the ordering quantities of the two channels and the profits of the two members, and the total profits of the supply chain. Further, an improved risk-sharing contract is presented to coordinate the dual-channel supply chain and ensures that both supply chain members achieve a win–win outcome. In addition, we make an extension to the case of the inconsistent prices in the two channels, and we also verify that the dual-channel supply chain can be coordinated by the similar improved risk-sharing contract.
There is an increasingly urgent need of lightweight components in aerospace industry, among which aluminum (Al) alloys have been the optimal materials of choice for aircraft structural parts since ...being used in the Junkers F.13 aircraft in the 1920s. Compared to other metal materials, Al alloys have a lower density, and the use of Al alloys reduces the total weight of the aircraft and improves fuel efficiency and load capacity. Meanwhile, the strength and hardness of Al alloys with alloying and heat treatment can be significantly enhanced for uses in high loads and vibration environments. Furthermore, in the harsh aerospace environment, aircraft may receive various climatic conditions and chemical corrosion. Due to good corrosion and fatigue resistance, Al alloys demonstrate excellent performance under these conditions, ensuring the long–term service life of aircraft. In addition, Al alloys have good recyclability, and they can be recycled to reduce resource consumption and environmental load, in line with the principle of sustainable development. In recent years, although composites have been widely used in aerospace, high–strength Al alloys are still in an indispensable position. Therefore, this article reviews the progress and applications of Al alloys commonly used in aerospace. The common strengthening methods and advanced manufacturing and processing technologies of Al alloy are also discussed, which can provide references for the development of advanced high–performance aviation Al alloys in the future.
Irritable bowel syndrome (IBS) is a common disorder in gastrointestinal system and impairs the quality of life of the patients. Clostridium butyricum (CB) is a probiotics that has been used in ...several gastrointestinal diseases. The efficacy of CB in treating IBS is still unknown. This prospective, multi-centre, randomized, double-blind, placebo-controlled trial aimed to assess the efficacy and safety of CB in treating diarrhea-predominant IBS (IBS-D) and analyze the fecal microbiota after treatment. Two hundred patients with IBS-D were recruited and were given CB or placebo for 4 weeks. End points included change from baseline in IBS symptoms, quality of life, stool consistency and frequency. Compared with placebo, CB is effective in improving the overall IBS-D symptoms (-62.12 ± 74.00 vs. -40.74 ± 63.67, P = 0.038) as well as quality of life (7.232 ± 14.06 vs. 3.159 ± 11.73, P = 0.032) and stool frequency (-1.602 ± 1.416 vs. -1.086 ± 1.644, P = 0.035). The responder rates are found higher in CB compared with the placebo (44.76% vs. 30.53%, P = 0.042). The change in fecal microbiota was analyzed and function pathways of CB in treating IBS-D were predicted. In conclusion, CB improves overall symptoms, quality of life and stool frequency in IBS-D patients and is considered to be used as a probiotics in treating IBS-D clinically.
Single‐wall carbon nanotubes (SWCNTs), especially in the form of large‐area and high‐quality thin films, are a promising material for use in flexible and transparent electronics. Here, a continuous ...synthesis, deposition, and transfer technique is reported for the fabrication of meter‐scale SWCNT thin films, which have an excellent optoelectrical performance including a low sheet resistance of 65 Ω/◽ with a transmittance of 90% at a wavelength of 550 nm. Using these SWCNT thin films, high‐performance all‐CNT thin‐film transistors and integrated circuits are demonstrated, including 101‐stage ring oscillators. The results pave the way for the future development of large‐scale, flexible, and transparent electronics based on CNT thin films.
Meter‐scale single‐wall carbon nanotube (SWCNT) thin films with an excellent optoelectrical performance and uniformity are produced by a continuous growth, deposition, and transfer technique. Using these SWCNT thin films, highly flexible and transparent all‐CNT TFTs and ICs including 101‐stage ring oscillators are constructed and show excellent performance.
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