The electrocyclic reaction is one of the most powerful tools for the construction of complex polycyclic scaffolds in a highly stereocontrolled fashion. In this review, recent advances in its application in the total synthesis of representative natural products are discussed, with the aim of providing a complement to existing reviews.1 Introduction2 4π Electrocyclization2.1 Neutral 4π Electrocyclization2.2 Cationic 4π Electrocyclization3 6π Electrocyclization3.1 All-Carbon 6π Electrocyclization3.2 Oxa-6π Electrocyclization3.3 Aza-6π Electrocyclization3.4 Retro-6π Electrocyclization4 8π Electrocyclization5 Conclusion and Outlook

Article HistoryTextbooks play an important role in teaching and learning and have a great impact on the students in aspects such as cultural values, norms, and attitudes towards social roles and identities. In particular, textbooks are of great importance to the education for gender equity. This study aims to explore the representation of genders to find if there is any bias and stereotype in a set of English textbooks used in primary schools in Guangzhou, a metropolitan city in South China with a population of more than ten million. The investigation looks at the textbooks from aspects of frequency of genders, the social roles females and males play in different settings, and the priority of mention when both genders are referred to on one occasion. The results suggest that stereotypes and imbalanced representation of genders and gender social roles are evident in the textbooks. The paper also gives some suggestions as to materials writing and teaching.Contribution/ Originality: This study examines the representation of gender in an English textbook series used in Chinese primary schools and finds evidence of stereotypes and imbalanced representation of gender. Besides, it gives some suggestions as to materials writing and teaching.

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Because of the excellent thermal conduction, corrosion resistance, and tribological properties, copper-based friction materials (CBFMs) were widely used in airplanes, high-speed trains, and wind power generation. With operating speed continuously increasing, CBFMs are suffering more complicated and extreme working conditions, which would cause abnormal abrasion. This paper presents an experiment to investigate how the tribological behaviors of CBFMs are regulated by granulation technology. Samples were prepared by the method of granulation and cool-pressed sinter. The tribological properties of specimens with different granule sizes were studied. The results showed that granulation could improve the tribological properties of CBFMs. The friction coefficient (COF) increased first and then decreased with increasing granule size. Specimen fabricated with 5–8 mm granules obtained the lowest COF, which was reduced by 22.49% than that made of powders. Moreover, the wear rate decreased first and then increased as granule size increased. The wear rate of samples prepared by granules 3–5 mm was lower than that of all of the other samples. This is because the structured samples prepared by wet granulation can promote the formation of secondary plateaus, which are beneficial for enhancing tribological properties. This makes granulation a promising method for enhancing the tribological performances of CBFMs.

To enhance the friction performance of resin‐based friction materials, five types of specimens with different polymer ether ketone (PEEK) contents were fabricated and their physiomechanical behaviours were tested and, their tribological properties were investigated using a JF150F‐II constant‐speed tester. It was found that the addition of PEEK had a positive influence on the properties of the friction materials, and sample FM‐3 (the shorthand of ‘Friction Materials‐3’, containing 2 wt% PEEK) exhibited improved friction performance with a fade ratio and recovery ratio of 8.6% and 101.1% respectively. Among all samples, FM‐4 (the shorthand of ‘Friction Materials‐4’, containing 3 wt% PEEK) had the lowest specific wear rate with a value of 0.622 × 10−7 cm3 (N·m)−1 at 350°C. The PEEK can fill the microcracks in the composite at a high temperature and can also cover the hard abrasive particles to prevent them from directly damaging the composite. The findings from this study afford a foundation for studies to further improve the properties of resin‐based friction materials.

To improve the picking rate and reduce the wrong picking rate of the existing wolfberry harvesting machinery, in this study, the binding force and physical appearance of the immature fruit stalk, mature fruit stalk, flower, and leaf were studied to guide the designing of new-generation wolfberry harvesting machinery and lay theoretical foundation for further studies on biomechanical properties of wolfberry. By preprocessing the experimental data with the Pauta criterion, the distribution range of the binding force and physical appearance of stalk were obtained; the binding force was not influenced by the picking temperature, mass of the fruit, and location of the branch of the fruit. The length-diameter ratio of mature fruit was confirmed by image processing. The constitutive equations for immature fruit stalks and mature fruit stalks were established. The breaking strength of the mature fruit stalk was obviously higher than that of the immature fruit stalk; moreover, the breaking strength of the mature and immature fruit stalk of the four wolfberry varieties differed obviously. The experimental results obtained in this study can provide detailed data for the parameter design of a new-generation wolfberry harvesting machinery.