High device efficiency and color‐purity are the two essentials for high‐quality organic light‐emitting diodes (OLEDs). Multi‐resonance (MR) molecules show great potentials for high color‐purity OLEDs ...due to their sharp emission bands. However, most MR molecules exhibit emission limited from deep‐blue to green spectral region. Herein, through peripherally decorating MR emitter with electron donors, a new approach enabling the emission spectra of MR emitters red‐shift while retaining narrowband emission is demonstrated. By manipulating the numbers and electron‐donating abilities of the peripheries, the first narrowband yellow emitter with emission maxima of 562 nm and a full‐width at half‐maximum (FWHM) of 30 nm is realized. Highly efficient OLEDs with an external quantum efficiency of over 24% and excellent color purity are fabricated by employing these newly developed MR molecules as emitters.
This work demonstrates a versatile approach by peripheral decoration of multi‐resonance molecules, which enables emission spectra red‐shift while remains narrowband emission. Fully decorating the parent BNCz molecules with diphenylamine gives the first narrowband yellow emissive MR emitter with an emission maxima of 562 nm. Electroluminescence devices employing these MR emitters reveal narrowband emission with high external quantum efficiency of over 24%.
This study investigates the critical issue of mental health disparities within diverse populations in modern workplaces, a concern that significantly affects both individuals and organizational ...structures. By focusing on how prevailing workplace behaviors, including implicit biases, microaggressions, and the scarcity of diversity in leadership, exacerbate these disparities, the research highlights the urgent need for attention and action in this area. The mental health gap-disparities in conditions and access to care among different workplace groups-emerges from systemic inequalities and stigmatization, deeply influencing employee productivity, creativity, collaboration, and retention. Our research underscores the disproportionate impact of this gap on diverse populations, characterized by varying ethnicity, gender, age, socio-economic status, and other unique identity attributes. The paper articulates the substantial economic repercussions for organizations, manifesting as reduced productivity, increased absenteeism, and higher turnover rates. Recommendations include the implementation of cultural competency training, promotion of inclusive leadership, investment in tailored mental health resources and fostering open dialog about mental health. These strategies are pivotal in creating an inclusive, resilient, and harmonious work environment. Our findings aim to catalyze a shift in organizational practices toward mental well-being, advocating for comprehensive strategies to bridge the mental health divide in workplaces, thereby enhancing overall organizational health and cohesion.
A split Hopkinson pressure bar (SHPB) system with a special shape striker has been suggested as the test method by the International Society for Rock Mechanics (ISRM) to determine the dynamic ...characteristics of rock materials. In order to further verify this testing technique and microscopically reveal the dynamic responses of specimens in SHPB tests, a numerical SHPB test system was established based on particle flow code (PFC). Numerical dynamic tests under different impact velocities were conducted. Investigation of the stresses at the ends of a specimen showed that the specimen could reach stress equilibrium after several wave reverberations, and this balance could be maintained well for a certain time period after the peak stress. In addition, analyses of the reflected waves showed that there was a clear relationship between the variation of the reflected wave and the stress equilibrium state in the specimen, and the turning point of the reflected wave corresponded well with the peak stress in the specimen. Furthermore, the reflected waves can be classified into three types according to their patterns. Under certain impact velocities, the specimen deforms at a constant strain rate during the whole loading process. Finally, the influence of the micro-strength ratio (
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) and distribution pattern on the dynamic increase factor (DIF) of the strength DIF were studied, and the lateral inertia confinement and heterogeneity were found to be two important factors causing the strain rate effect for rock materials.
Multiresonance thermally activated delayed fluorescence (MR‐TADF) emitters manifest great potential for organic light‐emitting diodes (OLEDs) due to their high exciton‐utilization efficiency and ...narrowband emission. Nonetheless, their tendency toward self‐quenching caused by strong interchromophore interactions would induce doping sensitivity and deteriorate the device performances, and effective strategy to construct quenching‐resistant emitters without sacrifycing color purity is still to be developed. By segregating the planar MR‐TADF skeleton using two bulky carbazolyl units, herein a highly emissive molecule with enhanced quenching resistance is reported. The steric effect largely removes the formation of detrimental excimers/aggregates, and boosts the performance of the corresponding devices with a maximum external quantum efficiency (EQEmax) up to 40.0% and full width at half maximum (FWHM) of 25 nm, representative of the only example of single OLED that can concurrently achieve narrow bandwidth and high EL efficiency surpassing 40% to date. Even at doping ratio of 30 wt%, the EQEmax is retained to be 33.3% with nearly unchanged emission spectrum. This work provides a viable approach to realize doping‐insensitive MR‐TADF devices with extreme EL efficiency and color purity for high‐end OLED displays.
A molecular design tactic to achieve quenching‐resistant multiresonance thermally activated delayed fluorescence (MR‐TADF) emitters is proposed by fencing the MR‐skeleton with steric units. Excellent electroluminescence performances are recorded in corresponding organic light‐emitting diodes, with record‐breaking external quantum efficiencies up to 40.0% and full width at half maximum values of only 25 nm.
This study examines the development and trends of China's alfalfa market and imports, identifies key factors for the rapid increase in China's alfalfa imports, and discusses potential impacts of the ...U.S.–China trade dispute and retaliations on the alfalfa markets and trade in both nations. China's rapid transition toward larger-scale commercial dairy production, with enhanced feed and cost management as well as quality and safety control, and its limited resources for high-quality alfalfa production are key factors for the dramatic increase in its alfalfa imports, from 19 601 metric tons in 2008 to 1.38 million metric tons (mmt) in 2018. While the United States dominated China's alfalfa imports with an average share of 97.01% from 2007 to 2017, the share dropped to 83.76% in 2018 and 63.28% in January 2019 due to the trade dispute and retaliations started in 2018. China will likely remain a large importer of alfalfa because of both its growing demand and the comparative advantages of imported alfalfa in quality and price, but the imports from the United States will be highly affected by the ongoing trade dispute and negotiations. China is also expected to make more efforts to reduce its dependence on U.S. alfalfa through increased investment in domestic alfalfa production and identification of alternative sources of alfalfa and other hay imports.
Mounting evidence indicates that obesity may be associated with the risk of colorectal cancer (CRC). To conduct a systematic review of prospective studies assessing the association of obesity with ...the risk of CRC using meta-analysis.
Relevant studies were identified by a search of MEDLINE and EMBASE databases before January 2012, with no restrictions. We also reviewed reference lists from retrieved articles. We included prospective studies that reported relative risk (RR) estimates with 95% confidence intervals (CIs) for the association between general obesity measured using body mass index (BMI) or central obesity measured using waist circumference (WC) and the risk of colorectal, colon, or rectal cancer. Approximately 9, 000, 000 participants from several countries were included in this analysis. 41 studies on general obesity and 13 studies on central obesity were included in the meta-analysis. The pooled RRs of CRC for the obese vs. normal category of BMI were 1.334 (95% CI, 1.253-1.420), and the highest vs. lowest category of WC were 1.455 (95% CI, 1.327-1.596). There was heterogeneity among studies of BMI (P<0.001) but not among studies of WC (P=0.323).
Both of general and central obesity were positively associated with the risk of CRC in this meta-analysis.
We present the first electromagnetically driven, self-lifting, sub-100-mg, insect-inspired flapping-wing microaerial vehicle. This robot, with a weight of 80 mg and a wingspan of 3.5 cm, can produce ...sufficient thrust to lift off. The wing beat frequency is up to 80 Hz and the flapping amplitude is approximately ±70°. An electromagnetic actuator is employed to control the flapping amplitude and create passive wing rotation. To the best of our knowledge, this is the world's smallest electromagnetically driven flapping-wing robot that is capable of liftoff.
From every heartbeat to every footstep, human beings dissipate energy all the time. Researchers are trying to harvest energy from the human body and convert it into electricity, which can be supplied ...to electronic medical devices closely related to human health. Such an energy recycling form is currently a research hotspot in the fields of energy harvesting and bioelectronics. This review firstly summarizes the distribution and characteristics of three primary energy sources contained in the human body, including thermal energy, chemical energy, and mechanical energy. Afterwards, the applicable energy harvesting technologies and corresponding working mechanisms for different energy sources are introduced. Some typical demos and practical applications of each type of human body energy harvesting technology are also presented. Specifically, the advantages and critical issues of different energy harvesting technologies are summarized, and corresponding promising solutions are also provided. Besides, the interaction strategies between various energy harvesting devices and the human body are summarized from the aspects of wearable and implantable applications. Finally, the concept of a self-powered closed-loop bioelectronic system (SCBS) is put forward for the first time, which organically combines portable electronic devices, implantable electronic medical devices, energy harvesting devices, and the human body. The prospect of symbiosis between the SCBS and the human body is provided. The demands and future development trends of the SCBS are also discussed.
Word embeddings and CNN (convolutional neural networks) architecture are crucial ingredients of sentiment analysis. However, sentiment and lexicon embeddings are rarely used and CNN is incompetent to ...capture global features of sentence. To this end, semantic embeddings, sentiment embeddings and lexicon embeddings are applied for texts encoding, and three different attentions including attention vector, LSTM (long short term memory) attention and attentive pooling are integrated with CNN model in this paper. Additionally, a word and its context are explored to disambiguate the meaning of the word for rich input representation. To improve the performance of three different attention CNN models, CCR (cross-modality consistent regression) and transfer learning are presented. It is worth noticing that CCR and transfer learning are used in textual sentiment analysis for the first time. Finally, some experiments on two different datasets demonstrate that the proposed attention CNN models achieve the best or the next-best results against the existing state-of-the-art models.
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