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There are many lexical studies on euphemisms and general studies, and there is currently a lack of research on euphemisms in context. There is a lack of relevant articles based on euphemisms for chronological studies. This article examines English euphemisms through chronological comparisons and focuses on the influence of different cultures of different generations on euphemisms. The article explains the fundamental logic of the change and development of euphemisms. The culture of Western countries emphasizes personality development, while Chinese culture emphasizes restraint. Under the influence of Western cultures, Western euphemisms are relatively simple and mostly used to express politeness. It is relatively complex and emphasizes the human understanding that Chinese culture influences Chinese euphemisms. Along with the Europeanization of Chinese, Chinese euphemisms have also been influenced to some extent by English euphemisms. However, as time passed, Chinese and English euphemisms developed in a more concise direction, but both languages retained the polite function of euphemisms. Euphemisms are meant to show politeness and avoid conflict. Therefore, it is important to use the right euphemisms in intercultural communication and inter-age communication.

The air/oil two-phase flow is extremely complex in the aero-engine bearing chamber, so the comprehensive understanding of the flow phenomenon is helpful to improve the design of the lubrication and heat exchange system. In this paper, transient CFD simulation is developed to analyse the air/oil two-phase flow in the bearing chamber. The velocity and temperature distributions of air and oil with time and space are discussed. The results show that under the periodic conditions, the velocity and temperature of the air and oil in the bearing chamber present quasi periodic characteristics. And the velocity and temperature distribution of air/oil two-phase flow in bearing chamber is independent with time in the bearing chamber. The research work will contribute to understand the nonlinear characteristics of air/oil two-phase flow in the bearing chamber.

The storage systems have been challenged by the development of cloud computing. The traditional data index cannot satisfy the requirements of cloud computing because of the huge index volumes and quick response time. Meanwhile, because of the increasing size of data index and its dynamic characteristics, the previous ways, which rebuilding the index or fully backup the index before the data has changed, cannot satisfy the need of today’s big data index. To solve these problems, we propose a double-layer index structure that overcomes the throughput limitation of single point server. Then, a clone based B+ tree structure is proposed to achieve high performance and adapt dynamic environment. The experimental results show that our clone-based solution has high efficiency.

As the last common enzyme in the biosynthetic pathway leading to heme and chlorophyll, protoporphyrinogen oxidase (PPO; EC 1.3.3.4) is an ideal target for herbicide development. Currently, about 30 PPO inhibitors have been developed as agricultural herbicides. PPO inhibitors have displayed environmentally benign, but advantageous characteristics, including low toxicity, low effective concentration, broad herbicidal spectrum (active against both monocotyledon and dicotyledon weeds), quick onset of action, and long lasting effect. Over the last several years, great achievements have been made in revealing the structural biology of PPO. Five PPO crystal structures, four isolated in enzyme-inhibitor complexes and one in the native form, have been determined, including those from Nicotiana tabacum, Myxococcus Xanthus, Bacillus subtilis, and human. Although PPO inhibitors have been developed for over forty years, we continue to uncover exciting future prospects for novel PPO-inhibiting herbicides. In this review, we have summarized the structures of PPOs from plants, human, and bacteria; the interactions between PPOs and inhibitors; the quantitative structure–activity relationships of PPO inhibitors; and the molecular design of new PPO inhibitors.