High‐efficiency, thermally activated delayed‐fluorescence organic light‐emitting diodes based on exciplex emitters are demonstrated. The best device, based on a TAPC:DPTPCz emitter, shows a high ...external quantum efficiency of 15.4%. Strategies for predicting and designing efficient exciplex emitters are also provided. This approach allow prediction and design of efficient exciplex emitters for achieving high‐efficiency organic light‐emitting diodes, for future use in displays and lighting applications.
The recent introduction of thermally activated delayed fluorescence (TADF) emitters is regarded as an important breakthrough for the development of high efficiency organic light‐emitting devices ...(OLEDs). The planar D and A groups are generally used to construct TADF emitters for their rigid structure and large steric hindrance. In this work, it is shown that many frequently used nonaromatic (noncontinuous conjugation or without satisfying Hückel's rule) planar segments, such as 9,9‐dimethyl‐9,10‐dihydroacridine, are actually pseudoplanar segments and have two possible conformations–a planar form and a crooked form. Molecules constructed from pseudoplanar segments can thus have two corresponding conformations. Their existence can have significant impact on the performance of many TADF emitters. Two design strategies are presented for addressing the problem by either (1) increasing the rigidity of these groups to suppress its crooked form or (2) increasing the steric hindrance of the linked group to minimize energy of the emitters with the highly twisted form. Following these strategies, two new emitters are synthesized accordingly and successfully applied in OLEDs demonstrating high external quantum efficiencies (20.2% and 18.3%).
A schematic energy level diagram of (2‐(9,9‐dimethylacridin‐10(9H)‐yl) thianthrene‐5,5,10,10‐tetraoxide) shows that molecules constructed from pseudoplanar segments can have two corresponding conformations, which have significant impact on the performance of many thermally activated delayed fluorescence emitters. By either increasing the rigidity of these groups, or by increasing the steric hindrance of the linked group, the problem can be addressed.
Increasing evidence has confirmed that the antimicrobial and anti‐inflammatory effects of cinnamon essential oil (CEO) contribute to protection against inflammatory bowel disease (IBD). The dextran ...sodium sulfate (DSS)‐induced colitis mouse model was established to investigate the correlation between the protective effects of CEO and the regulation of intestinal microflora. The symptoms of IBD were assessed by measuring the hemoglobin content, myeloperoxidase activity, histopathological observation, cytokines, and toll‐like receptor (TLR4) expression. The alteration of the fecal microbiome composition was analyzed by 16S rRNA gene sequencing. The results indicated that the oral administration of CEO enriched with cinnamaldehyde effectively alleviated the development of DSS‐induced colitis. In contrast to the inability of antibiotics to regulate flora imbalance, the mice fed with CEO had an improved diversity and richness of intestinal microbiota, and a modified community composition with a decrease in Helicobacter and Bacteroides and an increase in Bacteroidales_S24‐7 family and short‐chain fatty acids (SCFA)‐producing bacteria (Alloprevotella and Lachnospiraceae_NK4A136_group). Moreover, the correlation analysis showed that TLR4 and tumor necrosis factor‐α was positively correlated with Helicobacter, but inversely correlated with SCFA‐producing bacteria. These findings indicated from a new perspective that the inhibitory effect of CEO on IBD was closely related to improving the intestinal flora imbalance.
Isoquinoline alkaloids, an important class of N‐based heterocyclic compounds, have attracted considerable attention from researchers worldwide since the early 19th century. Over the past 200 years, ...many compounds from this class were isolated, and most of them and their analogs possess various bioactivities. In this review, we survey the updated literature on bioactive alkaloids and highlight research achievements of this alkaloid class during the period of 2014–2018. We reviewed over 400 molecules with a broad range of bioactivities, including antitumor, antidiabetic and its complications, antibacterial, antifungal, antiviral, antiparasitic, insecticidal, anti‐inflammatory, antioxidant, neuroprotective, and other activities. This review should provide new indications or directions for the discovery of new and better drugs from the original naturally occurring isoquinoline alkaloids.
A high‐efficiency single‐emission‐layer (EML) hybrid white organic light emitting device is fabricated based on an ideal sky‐blue fluorophor, DADBT, using a novel doping concentration regulation ...strategy, which effectively separates and respectively utilizes the singlet and triplet excitons in the single‐EML. The white device shows excellent electroluminescence performance with maximum total efficiencies of 26.6%, 53.5 cd A−1 and 67.2 lm W−1.
We consider the exact rogue periodic wave (rogue wave on the periodic background) and periodic wave solutions for the Chen–Lee–Liu equation via the odd-th order Darboux transformation. Then, the ...multi-layer physics-informed neural networks (PINNs) deep learning method is applied to research the data-driven rogue periodic wave, breather wave, soliton wave and periodic wave solutions of well-known Chen–Lee–Liu equation. Especially, the data-driven rogue periodic wave is learned for the first time to solve the partial differential equation. In addition, using image simulation, the relevant dynamical behaviors and error analysis for there solutions are presented. The numerical results indicate that the rogue periodic wave, breather wave, soliton wave and periodic wave solutions for Chen–Lee–Liu equation can be generated well by PINNs deep learning method.
•The rogue periodic wave and periodic wave for CLL equation are derived firstly.•The PINN method is applied to research the data-driven solutions of CLL equation.•The data-driven rogue periodic wave is learned for the first time to solve the PDE.
A novel molecular model of connecting electron‐donating (D) and electron‐withdrawing (A) moieties via a space‐enough and conjugation‐forbidden linkage (D‐Spacer‐A) is proposed to develop efficient ...non‐doped thermally activated delayed fluorescence (TADF) emitters. 10‐(4‐(4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl) phenoxy) phenyl)‐9,9‐dimethyl‐9,10‐dihydroacridine (DMAC‐o‐TRZ) was designed and synthesized accordingly. As expected, it exhibits local excited properties in single‐molecule state as D‐Spacer‐A molecular backbone strongly suppress the intramolecular charge‐transfer (CT) transition. And intermolecular CT transition acted as the vital radiation channel for neat DMAC‐o‐TRZ film. As in return, the non‐doped device exhibits a remarkable maximum external quantum efficiency (EQE) of 14.7 %. These results prove the feasibility of D‐Spacer‐A molecules to develop intermolecular CT transition TADF emitters for efficient non‐doped OLEDs.
Non‐doped OLEDs: A novel molecular model of connecting electron‐donating (D) and electron‐withdrawing (A) moieties through a conjugation‐forbidden spacer is proposed to develop efficient thermally activated delayed fluorescence emitters for non‐doped organic light‐emitting diodes. The structure shows intermolecular charge‐transfer (CT) transitions as the major radiative channel and a suppressed effect of photoluminescence concentration quenching.
In this paper, the scheduling management of delay-constrained medical packet transmissions in Internet of Things (IoT)-based healthcare networks is studied. Unlike most existing works in the ...literature, we focus on beyond wireless body area network (beyond-WBAN) communications, i.e., data transmissions between smart WBAN-gateways (e.g., smartphones) and the base station (BS) of remote medical centers. In our model, various medical packets are randomly aggregated at each gateway (which ordinarily stands for one patient), and their delay-constrained beyond-WBAN transmission requests are immediately reported to the network controller (i.e., BS) with different priority levels reflecting their medical importance. The BS schedules the uplink beyond-WBAN transmissions by forming a queueing system which addresses specific medical-grade quality of service requirements, including the priority awareness and the delay constraints of medical packet transmissions. By taking into account the natural device intelligence of smart gateways in IoT-based networks, we design a truthful and efficient mechanism which can prevent gateways from strategically misreporting the priority levels of medical packets, while incentivizing the BS to manage the transmission scheduling according to the desired manner. Both theoretical and simulation results examine the feasibility of the proposed mechanism and demonstrate its superiority over the counterparts.
It has been speculated that the partial pressure of carbon dioxide (pCO
) in shelf waters may lag the rise in atmospheric CO
. Here, we show that this is the case across many shelf regions, implying ...a tendency for enhanced shelf uptake of atmospheric CO
. This result is based on analysis of long-term trends in the air-sea pCO
gradient (ΔpCO
) using a global surface ocean pCO
database spanning a period of up to 35 years. Using wintertime data only, we find that ΔpCO
increased in 653 of the 825 0.5° cells for which a trend could be calculated, with 325 of these cells showing a significant increase in excess of +0.5 μatm yr
(p < 0.05). Although noisier, the deseasonalized annual data suggest similar results. If this were a global trend, it would support the idea that shelves might have switched from a source to a sink of CO
during the last century.
Recently, a novel mechanical energy harvesting method named triboelectric nanogenerator (TENG) is reported, and it has aroused great repercussions in the academic fields. But, the complex preparation ...process still limits its wide application. In this paper, the cotton film was used as the triboelectric material to fabricate a novel wearable TENG (W-TENG). The polytetrafluoroethylene (PTFE) film and cotton film play the role of triboelectric pair. The W-TENG can be used to harvest low-frequency mechanical energy in our environment, especially for human body mechanical energy, and then convert them to electrical energy. In addition, the cotton coated with conductive ink plays the role of conductive material for TENG. The Voc and Isc of W-TENG can reach 556 V and 26 μA, respectively. As for the maximum power density of W-TENG, it can arrive at 0.66 mW/cm2. Also, a combined W-TENG was proposed to improve the electrical output. Moreover, the W-TENG can play the role of human motion sensor for human walking posture monitoring. This will open up a new path for the preparation of high output TENG at low cost, and promote the TENG devices in the field of sports monitoring.
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•We firstly reported a wearable TENG (W-TENG) based on the polytetrafluoroethylene (PTFE) film and cotton film to harvest mechanical energy in our environment.•The results also show that the W-TENG has wonderful charging effect and excellent reliability.•The W-TENG can play the role of human motion sensor for human walking posture monitoring.
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