EL spectrum of the fabricated WLEDs device. Inset illustrates the schematic diagram for the fabrication of LED device. Luminescent images of the prepared WLEDs device without and with input current.
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•NaBiF4:Eu3+ nanoparticles were synthesized by an ultra-fast method.•UV excitation induced bright red emissions with quantum efficiency of 73.1%.•They possessed good thermal stability with activation energy of 0.237 eV.•The cathodoluminescence properties of the nanoparticles were also studied.•LED devices were fabricated by using the nanoparticles and UV LED chips.
A series of novel Eu3+-activated NaBiF4 nanoparticles were synthesized by an ultra-fast chemical precipitate method at room temperature. Under the excitation of 394 nm, all the compounds emitted glaring red emissions originating from the intra-4f transitions of Eu3+ ions. The optimal doping concentration was found to be 40 mol% and the concentration quenching mechanism was dominated by dipole–dipole interaction. The temperature-dependent photoluminescence emission spectra revealed that the resultant nanoparticles possessed admirable thermal stability with an activation energy of 0.237 eV. The internal quantum efficiency of the synthesized nanoparticles was estimated to be as high as 73.1%. Furthermore, the optical transition parameters of Eu3+ ions were calculated using a facile method based on the Judd-Ofelt theory to explore the local structure environment around the Eu3+ ions in the NaBiF4 host lattice. Additionally, the packaged light-emitting diode (LED) device, which was composed of a near-ultraviolet LED chip, synthesized nanoparticles and commercial blue-emitting/green-emitting phosphors, exhibited brightly white light with high color rendering index of 88.2 and proper correlated color temperature of 6851 K. Ultimately, the studied nanoparticles also had splendid cathodoluminescence properties. These results suggest that the Eu3+-activated NaBiF4 nanoparticles were promising bifunctional materials for simultaneous white LEDs and field emission displays.
Lilium is a large genus that includes approximately 110 species distributed throughout cold and temperate regions of the Northern Hemisphere. The species-level phylogeny of Lilium remains unclear; ...previous studies have found universal markers but insufficient phylogenetic signals. In this study, we present the use of complete chloroplast genomes to explore the phylogeny of this genus. We sequenced nine Lilium chloroplast genomes and retrieved seven published chloroplast genomes for comparative and phylogenetic analyses. The genomes ranged from 151,655 bp to 153,235 bp in length and had a typical quadripartite structure with a conserved genome arrangement and moderate divergence. A comparison of sixteen Lilium chloroplast genomes revealed ten mutation hotspots. Single nucleotide polymorphisms (SNPs) for any two Lilium chloroplast genomes ranged from 8 to 1,178 and provided robust data for phylogeny. Except for some of the shortest internodes, phylogenetic relationships of the Lilium species inferred from the chloroplast genome obtained high support, indicating that chloroplast genome data will be useful to help resolve the deeper branches of phylogeny.
On 6 February 2023, a local tsunami was recorded in the southeastern Mediterranean Sea following the Mw 7.7 Turkey–Syria inland strike‐slip earthquake. Due to the lack of underwater observation, the ...tsunami generation mechanism remains mysterious. To understand the source mechanisms, we analyzed the tsunami waveforms of four nearby tide gauges and located possible sources using a backward tsunami ray tracing approach. We then conducted forward numerical modelings for a range of possible source parameters. We show that there were probably two tsunami sources, inside and outside Iskenderun Bay, which may be related to thick coastal sediments. A source inside the Bay with a characteristic length of 7 km produced dominant periods of 10–30 min with negative initial motion, possibly generated by a landslide. Another source of 6 km length outside the Bay produced dominant periods of 2–10 min with positive initial motions, possibly related with liquefaction.
Plain Language Summary
Inland earthquakes, especially inland strike‐slip earthquakes rarely produce tsunamis since tsunami waves are normally generated by vertical displacements accompanied with fault ruptures. On 6 February 2023, the Turkey–Syria strike‐slip inland earthquake of Mw 7.7 mysteriously generated a small‐scale tsunami in the southeastern Mediterranean Sea. Due to the complexity of the earthquake source and lack of underwater observation, how the tsunami waves were generated remains mysterious. To understand the tsunami origins, we analyzed the tsunami waveforms in different aspects and adopted numerical modelings to explore the possible sources. We find that there existed two tsunami sources probably generated by landslides inside the Iskenderun Bay and related with liquefactions outside the Bay. We therefore highlight the potential threat caused by the disaster chain of coastal strike‐slip earthquakes.
Key Points
We find distinctly different tsunami wave properties inside and outside the Iskenderun Bay
We obtain possible tsunami sources that can well explain the observed tsunami waveforms
Underestimated and unpredictable tsunami origins due to the disaster chain caused by coastal strike‐slip earthquakes call for more attention
The genus Fritillaria comprises approximately 130 perennial herbaceous species. In the Pharmacopoeia of the People's Republic of China, the bulbs of 11 Fritillaria species are used in Chinese herbal ...medicines. However, the traditional methods of morphological classification cannot accurately identify closely related species of Fritillaria. Previous studies have attempted to identify these species with universal molecular markers, but insufficient phylogenetic signal was available. In this study, the complete chloroplast genomes of eight Fritillaria species were compared. The length of the eight Fritillaria chloroplast genomes ranges from 151,009 bp to 152,224 bp. A total of 136 SSR loci were identified, including 124 polymorphic SSR loci. For large repeat sequences, 108 repeat loci and four types of repeats were observed. Ten highly variable regions were identified as potential molecular markers. These SSRs, large repeat sequences and highly variable regions provide important information for the development of genetic markers and DNA fingerprints. Phylogenetic analyses showed that the topological structures of all data sets (except the IR regions) were in complete agreement and well resolved. Overall, this study provides comprehensive chloroplast genomic resources, which will be valuable for future studies of evolution and species identification in Fritillaria.
Adsorption of three selected pharmaceuticals and personal care products (PPCPs) (ketoprofen (KEP), carbamazepine (CBZ), and bisphenol A (BPA)) by two reduced graphene oxides (rGO1 and rGO2) and one ...commercial graphene was examined under different solution conditions. Single-walled carbon nanotubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs), and powdered graphite were also investigated for comparison. All adsorption isotherms followed the order of SWCNTs > rGO1 > rGO2 > MWCNTs > graphene > graphite, consistent with the orders of their surface areas and micropore volumes. After surface area normalization, adsorption affinities of the three PPCPs onto graphenes were lower than onto graphite, suggesting incomplete occupation for adsorption sites because of the aggregation of graphene sheets and the presence of oxygen-containing functional groups. The observed pH effects on adsorption correlated well with the pH-regulated distribution of the protonated neutral species of the three PPCPs. Increasing ionic strength from 0 to 20 mM increased KEP adsorption due to the electrostatic screening by Na(+) and Ca(2+). Both humic acid (HA) and sodium dodecylbenzenesulfonate (SDBS) suppressed PPCPs adsorption to all adsorbents, but their impacts onto graphenes were lower than those onto CNTs because of their lower adsorption by graphenes. More severe HA (or SDBS) effect was found on negatively charged KEP at the tested solution pH 6.50 due to the electrostatic repulsion between the same charged KEP and HA (or SDBS). The findings of the present study may have significant implications for the environmental fate assessment of PPCPs and graphene.
The typical conductive polymer of PEDOT:PSS has recently attracted intensive attention in thermoelectric conversion because of its low cost and low thermal conductivity as well as high electrical ...conductivity. However, compared to inorganic counterparts, the relatively poor thermoelectric performance of PEDOT:PSS has greatly limited its development and high-tech applications. Here, we report a dramatic enhancement in the thermoelectric performance of PEDOT:PSS by constructing unique composite films with graphene quantum dots (GQDs). At room temperature, the electrical conductivity and Seebeck coefficient of PEDOT:PSS/GQDs reached to 7172 S/m and 14.6 μV/K, respectively, which are 30.99% and 113.2% higher than those of pristine PEDOT:PSS. As a result, the power factor of the optimized PEDOT:PSS/GQDs composite is 550% higher than that of pristine PEDOT:PSS. These significant improvements are attributed to the ordered alignment of PEDOT chains on the surface of GQDs, originated from the strong interfacial interaction between PEDOT:PSS and GQDs and the separation of PEDOT and PSS phases. This study evidently provides a promising route for PEDOT:PSS applied in high-efficiency thermoelectric conversion.
Developing bifunctional electrocatalysts with high activities and long durability for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial toward the practical ...implementation of rechargeable metal–air batteries. Here, a 3D nanoporous graphene (np‐graphene) doped with both N and Ni single atoms/clusters is reported. The predoping of N by chemical vapor deposition (CVD) dramatically increases the Ni doping amount and stability. The resulting N and Ni codoped np‐graphene has excellent electrocatalytic activities for both the ORR and the OER in alkaline aqueous solutions. The synergetic effects of N and Ni dopants are revealed by density functional theory calculations. The free‐standing Ni,N codoped 3D np‐graphene shows great potential as an economical catalyst/electrode for metal–air batteries.
The presence of N facilitates the loading of a high density of isolated Ni single atoms on graphene. The Ni and N codopod 3D nanoporous graphene exhibits greatly enhanced bifunctional oxygen catalytic activities due to the synergetic effect between Ni and N. Due to the superior catalytic performance and structure advantage, a nanoporous graphene‐based all‐solid‐state Zn–air battery exhibits superior performance.
The allotropes of semiconducting Si have stimulated more and more interest in both experiment and theory. Here, we have studied the thermal property and lattice thermal conductivity of a novel ...three-dimensional (3D) pentagonal Si by using the first-principle calculations based on the density functional theory and Boltzmann transport equation. The special pentagonal structure exhibits almost isotropic and low lattice thermal conductivities, which is about 60 W/m⋅K at room temperatures, less than half that of diamond Si. The low thermal conductivity of pentagonal Si mainly comes from its relatively short phonon lifetimes and mean free paths. Our work could be useful for future experimental studies and possible applications of the 3D pentagonal Si.
•All the as-prepared samples can exhibit a strong red emission.•With addition of Bi3+ ions, the CT band and intensity of excitation peaks of Eu3+ ions were affected.•CaWO4:0.08Eu3+/0.02Bi3+ phosphor ...had strong PL and CL properties.•The as-prepared phosphor had potential applications in WLEDs and FEDs as a red-emitting phosphor.
The CaWO4:xEu3+ and CaWO4:0.08Eu3+/yBi3+ phosphors were synthesized via a high-temperature solid-state reaction method. The crystal structure and luminescence properties were investigated by X-ray diffraction patterns, photoluminescence excitation and emission spectra. The results indicate that both CaWO4:xEu3+ and CaWO4:0.08Eu3+/yBi3+ phosphors can be excited by near-ultraviolet and blue lights, and a strong red emission located at 616nm (5D0→7F2) corresponding to the characteristic emission of Eu3+ ions was observed in all the samples. Furthermore, the cathodoluminescence (CL) spectra as a function of filament current and accelerating voltage were also measured. Compared to the CaWO4:0.08Eu3+ phosphor, the CaWO4:0.08Eu3+/0.02Bi3+ phosphor had a stronger CL emission intensity with good Commission International de I’Eclairage chromaticity coordinate. The CaWO4:0.08Eu3+/0.02Bi3+ phosphor shows great potential for applications in white light-emitting diodes and field-emission displays as an excellent red-emitting phosphor.
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