High-performance white light-emitting diodes (WLEDs) hold great potential for the next-generation backlight display applications. However, achieving highly efficient and stable WLEDs with ...wide-color-gamut has remained a formidable goal. Reported here is the first example of pure red narrow bandwidth emission triangular CQDs (PR-NBE-T-CQDs) with photoluminescence peaking at 610 nm. The PR-NBE-T-CQDs synthesized from resorcinol show high quantum yield (QY) of 72% with small full width at half maximum of 33 nm. By simply controlling the reaction time, pure green (PG-) NBE-T-CQDs with high QY of 75% were also obtained. Highly efficient and stable WLEDs with wide-color-gamut based on PR- and PG-NBE-T-CQDs was achieved. This WLED showed a remarkable wide-color gamut of 110% NTSC and high power efficiency of 86.5 lumens per Watt. Furthermore, such WLEDs demonstrate outstanding stability. This work will set the stage for developing highly efficient, low cost and environment-friendly WLEDs based on CQDs for the next-generation wide-color gamut backlight displays.
Aqueous rechargeable batteries are desirable for energy storage because of their low cost and high safety. However, low capacity and short cyclic life are significant obstacles to their practical ...applications. Here, we demonstrate a highly reversible aqueous zinc–iodine battery using encapsulated iodine in microporous carbon as the cathode material by controlling solid–liquid conversion reactions. We identified the factors influencing solid–liquid conversion reactions, e.g., the pore size, surface chemistry of carbon host, and solvent effect. Rational manipulation of the competition between the adsorption in carbon and solvation in electrolytes for iodine species is responsible for the high reversibility and cyclic stability. The zinc–iodine battery delivers a high capacity of 174.4 mAh g–1 at 1C, stable cyclic life over 3000 cycles with ∼90% capacity retention, and negligible self-discharge. We believe that the principles for stabilizing the zinc–iodine system could provide new insight for other conversion systems such as lithium–sulfur systems.
The development of efficient red bandgap emission carbon quantum dots (CQDs) for realizing high‐performance electroluminescent warm white light‐emitting diodes (warm‐WLEDs) represents a grand ...challenge. Here, the synthesis of three red‐emissive electron‐donating group passivated CQDs (R‐EGP‐CQDs): R‐EGP‐CQDs‐NMe2, ‐NEt2, and ‐NPr2 is reported. The R‐EGP‐CQDs, well soluble in common organic solvents, display bright red bandgap emission at 637, 642, and 645 nm, respectively, reaching the highest photoluminescence quantum yield (QY) up to 86.0% in ethanol. Theoretical investigations reveal that the red bandgap emission originates from the rigid π‐conjugated skeleton structure, and the ‐NMe2, ‐NEt2, and ‐NPr2 passivation plays a key role in inducing charge transfer excited state in the π‐conjugated structure to afford the high QY. Solution‐processed electroluminescent warm‐WLEDs based on the R‐EGP‐CQDs‐NMe2, ‐NEt2, and ‐NPr2 display voltage‐stable warm white spectra with a maximum luminance of 5248–5909 cd m−2 and a current efficiency of 3.65–3.85 cd A−1. The warm‐WLEDs also show good long‐term operational stability (L/L0 > 80% after 50 h operation, L0: 1000 cd m−2). The electron‐donating group passivation strategy opens a new avenue to realizing efficient red bandgap emission CQDs and developing high‐performance electroluminescent warm‐WLEDs.
Red‐emissive electron‐donating group passivated carbon quantum dots (R‐EGP‐CQDs) with quantum yield up to 86.0% and good organic solubility are successfully synthesized. Solution‐processed electroluminescent warm white light emitting diodes (WLEDs) based on R‐EGP‐CQDs show high‐performance with maximum luminance of 5248–5909 cd m−2. The electron‐donating group passivation strategy opens a new avenue to realizing efficient red bandgap emission CQDs.
Multiple-scale mesoporous zinc ferrite (ZF) nanoparticles were prepared by controlling the calcination temperature and used in epoxy resin (ER). The scale effect of ZF nanoparticles on thermal ...stability, flame retardancy, and mechanical properties of ER composites was studied in detail. Results showed that ZF nanoparticles at all scales could improve the flame-retardant performance of ER. In particular, the 400-ZF nanoparticles show the best performance. When 5 phr of 400-ZF nanoparticles were added to the ER matrix, the peak heat release rate, peak smoke release, and peak carbon monoxide production of the ER were reduced by 38.3%, 36.3%, and 50.0%, respectively. In addition, the 400-ZF nanoparticles decreased the thermal stability and mechanical properties of ER slightly. These properties are attributed to its suitable crystal size and specific surface area. This flame-retardant system provided the possibility of the relationship between particle size and specific surface area, catalytic carbonization, and flame-retardant performance.
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•Multiple-scale zinc ferrite was prepared by controlling the calcination temperature.•The scale effect of Zinc ferrite nanoparticles on flame retardancy of ER was studied.•The 400-ZF has the best char-forming ability and flame retardancy in the ER matrix.•Excellent properties are attributed to suitable crystal size and specific surface area.
Abstract
Flux emergence is responsible for various solar eruptions. Combining observation and simulations, we investigate the influence of flux emergence at one footpoint of an arcade on coronal rain ...as well as induced eruptions. The emergence changes the pressure in the loops, and the internal coronal rain all moves to the other side. The emerging flux reconnects with the overlying magnetic field, forming a current sheet and magnetic islands. The plasma is ejected outwards and heated, forming a cool jet ∼6000 K and a hot X-ray jet ∼4 million Kelvin (MK) simultaneously. The jet dynamical properties agree very well between observation and simulation. In the simulation, the jet also displays transverse oscillations with a period of 8 minutes, in a so-called whiplike motion. The movement of the jet and dense plasmoids changes the configuration of the local magnetic field, facilitating the occurrence of the Kelvin–Helmholtz instability, and vortex-like structures form at the boundary of the jet. Our simulation clearly demonstrates the effect of emergence on coronal rain, the dynamical details of reconnecting plasmoid chains, the formation of multithermal jets, and the cycling of cool mass between the chromosphere and the corona.
NaNO3 and other alkali nitrate salts, which are present in the molten state during use, have been described as facilitators or catalysts for CO2 absorption by both MgO and MgO-containing double ...salts. Although MgO exhibits a high capacity (exceeding 70 wt %), its regenerability in multicycle tests shows a significant loss of capacity with cycle number prior to lining out. On the other hand, the MgO–Na2CO3 double salt shows a lower (∼16 wt %) but stable capacity over multiple cycles under pressure swing operation. The purpose of this paper is to elaborate on the concept of molten salts as catalysts for CO2 absorption by MgO, and extend these observations to the MgO-containing double salt oxides. We will show that the phenomena involved with CO2 absorption by MgO and MgO-based double salts are similar and general, but with some important differences. This paper focuses on the following key concepts: (i) identification of conditions that favor or disfavor participation of isolated MgO during double salt absorption, and investigation of methods to increase the absorption capacity of double salt systems by including MgO participation; (ii) examination of the relationship between CO2 uptake and melting point of the promoter salt, leading to the recognition of the role of premelting (surface melting) in these systems; and (iii) extension of the reaction pathway model developed for the MgO–NaNO3 system to the double salt systems. This information advances our understanding of MgO-based CO2 absorption systems for application with precombustion gas streams.
Cardiovascular diseases (CVDs) present a major social problem worldwide due to their high incidence and mortality rate. Many pathophysiological mechanisms are involved in CVDs, and oxidative stress ...plays a vital mediating role in most of these mechanisms. The ubiquitin–proteasome system (UPS) is the main machinery responsible for degrading cytosolic proteins in the repair system, which interacts with the mechanisms regulating endoplasmic reticulum homeostasis. Recent evidence also points to the role of UPS dysfunction in the development of CVDs. The UPS has been associated with oxidative stress and regulates reduction–oxidation homeostasis. However, the mechanisms underlying UPS-mediated oxidative stress’s contribution to CVDs are unclear, especially the role of these interactions at different disease stages. This review highlights the recent research progress on the roles of the UPS and oxidative stress, individually and in combination, in CVDs, focusing on the pathophysiology of key CVDs, including atherosclerosis, ischemia–reperfusion injury, cardiomyopathy, and heart failure. This synthesis provides new insight for continued research on the UPS–oxidative stress interaction, in turn suggesting novel targets for the treatment and prevention of CVDs.
When drilling holes for gas pre-extraction from soft coal seams having low permeability, phenomena such as hole collapse and drill pipe sticking can occur. These problems are due to the coal's low ...intensity and high gas pressure, both of which severely limit the efficiency of gas extraction. Based on an analysis of borehole collapse in soft seams, and on a study of the pore-formation mechanism in stiff layers, this paper proposes a new drilling technique that uses a high-pressure pulsed water jet. This technique can be used to drill holes in stiff layers of the roof/floor until the soft layers of the coal seam are reached. This method can improve the gas extraction rate. According to damage models for rock, a theoretical analysis and numerical simulation was performed for a high-pressure pulsed water jet. This analysis examined the instantaneous dynamic loads, the damage features when using a flexible impact regime, the changes in fracture field patterns, and the high-pressure pulsed water jet's oscillatory effect upon the gas flow of coal-mass. The impact and vibration effects of a high-pressure pulsed water jet could effectively contribute to crushing of the coal, to improvement of the coal's cracking and connectivity rate and to improvement in the permeability of the coal. Additionally, the high-pressure pulsed water jet's dynamic pressure and flow rate must be calculated for breaking rock during drilling and slotting. The developed system was applied in the Sanhui mine of Sichuan Province, China. The hole drilled by the new method is 2.7 times deeper than that of the hole drilled in the coal seam. In the Yutianbao mine, the average length was 148
m when drilling between the roof and the seam, and this value was more than 2.4 times deeper than that previously drilled in the coal seam. The gas flow was about 1.06
m
3/min per meter, which is more than 5 times that of a traditional hole.
►Based on the theoretical analysis of slotting pressure and flow of high-pressure pulse water jet when slotting coal seam, a novel technology used to drill long borehole and improve coal seam permeability in soft and low permeability seam was developed. Besides, the system devices which were applicable to the novel technology were developed. The application results showed that the system could guarantee the length of the borehole and improve the permeability of the coal seam. And the most important was that the devices were maneuverable. ►Through numerical simulation, the mechanism of high-pressure pulse water jet improving coal seam permeability was revealed. That was, the pulse of the water jet could prompt the generation and connection of the cracks, and then, the channels of the gas extraction were improved.
Diffusional limitations of mass transport have adverse effects on engineering tissues that normally have high vascularity and cellularity. The current electrospinning method is not always successful ...to create micropores to encourage cell infiltration within the scaffold, especially when relatively large-sized pores are required. In this study, a slow rotating frame cylinder was developed as the collector to extend the pore size and increase the porosity of electrospun fibrous scaffolds. Fibrous mats with porosity as high as 92.4% and average pore size of 132.7 μm were obtained. Human dermal fibroblasts (HDFs) were seeded onto these mats, which were fixed on a cell-culture ring to prevent the shrinkage and contraction during the incubation. The viability test indicated that significantly more HDFs were generated on highly porous fibrous mats. Toluidine blue staining showed that the highly porous scaffold provided mechanical support for cells to maintain uniform distribution. The cross-section observations indicated that cells migrated and infiltrated more than 100 μm inside highly porous fibrous mats after 5 d incubation. The immunohistochemistry analysis demonstrated that cells began secreting collagen, which is the main constituent of extracellular matrix. It is supposed that highly porous electrospun fibrous scaffolds could be constructed by this elaboration and may be used for skin tissue engineering.
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