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Enhancing the mechanical properties and cytocompatibility of decellularized heart valves is the key to promote the application of biological heart valves. In order to further improve the mechanical properties, the electrospinning and non-woven processing methods are combined to prepare the polylactic acid (PLA)/decellularized heart valve nanofiber-reinforced sandwich structure electrospun scaffold. The effect of electrospinning time on the performance of decellularized heart valve is investigated from the aspects of morphology, mechanical properties, softness, and biocompatibility of decellularized heart valve. Results of the mechanical tests show that compared with the pure decellularized heart valve, the mechanical properties of the composite heart valve were significantly improved with the tensile strength increasing by 108% and tensile strain increased by 571% when the electrospinning time exceeded 1 h. In addition, with this electrospinning time, the composite heart valve has a certain promoting effect on the human umbilical vein endothelial cells proliferation behavior. This work provides a promising foundation for tissue heart valve reendothelialization to lay the groundwork for organoid.

This paper explores an explainable AI model in the financial industry. Macroeconomic and market data serve as inputs of Hierarchical Clustering to distinguish among different economic regimes. Compared with traditional models such as Investment Clock, this method can adjust the classification standard in time according to recent market sentiment. The regime, therefore, can be interpreted by not only macro indicators but also investors’ mood swings using Artificial Intelligence. When we compute the statistical characteristics of returns of each asset, we find that they can be well distinguished among regimes. This method can also identify the abnormally large wave of the stock market from 2015 to 2016 by separating it as an unusual regime, which cannot be realized by traditional methods. The clustering technique enables us to explain and understand the current market status and predict different assets’ performances. Therefore, thanks to the superior interpretability of AI, the mean and variance of returns in each regime are estimated and viewed as viewpoints of the Black-Litterman asset allocation model to construct portfolios. To simulate the real situation, a dynamic backtesting method is used and asset weights change because of the rolling time windows. The results show that equipped with a simple timing strategy, the clustering technique can improve the results and yield excess returns. Some other machine learning techniques are also applied in an attempt to improve the model.

ortho-Linkages are effective in improving the performance of organic light-emitting diode (OLED) materials but may weaken the local chemical bonds and even incur chemical degradation due to bond cleavage reactions in operating OLEDs, especially for blue-emitting materials. Here, we conducted a systematic theoretical study on a series of carbazole (Cz)-based molecules with typical donor (D)−π−acceptor (A) structures to investigate the influence of ortho-substituents on the bond dissociation energies (BDEf) of their fragile D−π bonds (i.e., C–N bonds), where “fragile” means that the bonds have the minimum or a comparable-to-the-minimum BDE in the molecule. Through calculations, it was found that different substituents or even the same substituent on different sites of the molecule could bring variable effects on the polar D−π bond. Specifically, in the π-group, the effects of a substituent on BDEf mainly depend on the steric hindrance that it brings to the D−π bond. Thus, ortho-CH3 groups hardly affect BDEf...

The simultaneous realization of high quantum yield and exciton utilizing efficiency (ηr) is still a formidable challenge in near-infrared (NIR) fluorescent organic light-emitting diodes (FOLEDs). Here, to achieve a high quantum yield, a novel NIR dye, 4,9-bis(4-(diphenylamino)phenyl)-naphtho[2,3-c][1,2,5]selenadiazole, is designed and synthesized with a large highest occupied molecular orbital/lowest unoccupied molecular orbital overlap and an aggregation-induced emission property, which demonstrates a high photoluminescence quantum yield of 27% at 743 nm in toluene and 29% at 723 nm in a blend film. For a high ηr, an orange-emitting thermally activated delayed fluorescent material, 1,2-bis(9,9-dimethyl-9,10-dihydroacridine)-4,5-dicyanobenzene, is chosen as the sensitizing host to harvest triplet excitons in devices. The optimized devices achieve a good ηr of 45.7% and a high external quantum efficiency up to 2.65% at 730 nm, with a very small efficiency roll-off of 2.41% at 200 mA cm−2, which are among the most efficient values for NIR-FOLEDs over 700 nm. The effective utilization of triplet excitons via the thermally activated delayed fluorescence-sensitizing host will pave a way to realize high-efficiency NIR-FOLEDs with small efficiency roll-off.

An increasing demand for the online tension measurement in developing parafoil has arisen. In this paper, a new design for surface acoustic wave (SAW) tension sensor, which can be used to test the parafoil riser tension wirelessly and passively, is discussed. An SAW resonator is used for sensing tension by determining the frequency of the resonant reflection device. In accordance with the test requirements, a nondestructive side-loading tension testing structure is created by which stress analysis and optimization can be operated in ANSYS. To understand the relationship between size and frequency of the antenna in the sensor, a new antenna design called microstrip antenna is proposed following the high frequency structure simulator analysis. The proposed design shows good linearity and sensitivity between the SAW frequency and the riser tension through the actual experiment, which meets the stringent requirement for the shape of the sensor. Thus, the sensor can obtain tension measurement during the operation of the parafoil riser.

Flame stability is an important issue for combustion-based micro power generation systems. In the present work, we developed a planar micro-combustor with a bluff body fro micro power generation systems. Comparative study on lean and stoichiometric hydrogen/air flames in the micro-combustor with and without a bluff body was performed numerically. The results show that the blowoff limit is extended by 2–4 times with the bluff body. Moreover, flame remains symmetric under near-limit conditions in the micro combustor with a bluff body, while it becomes inclined in the case without a bluff body. Furthermore, the combustion efficiency is higher than 96% under most conditions in the new combustor. These demonstrate that the micro-combustor with a bluff body has a better performance.

Along with the continual escalation of the developing stage of FMCG, the small and medium-sized enterprises pays more and more attention to the delivery activities of FMCG to reduce their costs and develop their competitive advantage. Making FMCG as a research goal, based on the analyses of the characteristics of FMCG, their delivery and delivery mode, the paper brings up the evaluation indexes on the delivery mode of FMCG, and researches and evaluates the better delivery mode of FMCG by comprehensively making use of the advanced subjective Analytic Hierarchy process which is based on Judgment Matrix Scaled with Cloud Model.

With the development of the information society, it is important to take advantage of e-commerce to improve business efficiency, reduce operating costs, and develop new markets in order to significantly improve the enterprises' competitiveness. We want to see if e-procurement improves the procurement management a lot for steel enterprises and what advantages would give to them through this article. Combined with the actual situation and the procurement model in Bao Steel Company, we would research into its e-procurement model design and find some improvements after using the new procurement system.