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Prior research recognizes intergroup emotions as crucial for intergroup attitudes and interactions, but the psychological mechanisms linking prior intergroup interactions to contact intentions remain incompletely understood. This study investigated the joint effects and interplay of Chinese students' positive and negative contact on behavioural intentions to interact with international students in the future. Six affective variables (fear, anger, anxiety, empathy, happiness, and trust) were tested as mediators. Results revealed that positive contact directly predicted stronger contact willingness and indirectly affected this variable through lower levels of fear, anger, and anxiety and higher levels of empathy, happiness, and trust. Negative contact, however, was negatively associated with positive emotions and contact willingness and predicted more negative emotions. All intergroup emotions played significant mediating roles in the relationship between intergroup contact and willingness for future contact, and anxiety, fear, and trust emerged as robust mediators. Notably, positive contact had larger effects as compared to negative contact. Moreover, no association was observed between negative contact and intergroup emotions when positive contact was frequent. However, when both positive and negative contact were at higher levels, positive contact emerged as a more influential predictor of all intergroup emotions. This research emphasizes examining both positive and negative contact and affective variables as contact mediators, shedding light on enhancing contact intentions. [ABSTRACT FROM AUTHOR]

This study aims to test a mediation model to understand how the second language motivational self-system (L2MSS) affects second language (L2) proficiency and intercultural communication competence (ICC) through the mediating effects of foreign language enjoyment, anxiety, and boredom among English as a foreign language (EFL) learners in China. A total of 2,713 Chinese EFL learners, comprising 1,376 English majors and 1,337 non-English majors, voluntarily participated in the present study. Structural equation modeling (SEM) analysis was conducted to analyse the collected data. Additionally, a multigroup SEM approach was applied to compare potential differences between the two major types in the hypothesized relationships. The results revealed that the impacts of the ideal self and learning experience positively and directly predicted L2 proficiency and ICC, whereas the ought-to self had a direct and negative influence. Foreign language enjoyment, anxiety, and boredom mediated the relationships between L2MSS, L2 proficiency, and ICC. Also, L2 proficiency positively affected ICC. Moreover, the multigroup SEM analysis revealed that these two groups did not differ significantly in the hypothesized pathways, suggesting that these relationships were not moderated by students’ majors. These research findings may present significant implications for EFL learners and teachers. [ABSTRACT FROM AUTHOR]

Two new ansamycin derivatives, damavaricin H (1) and protostreptovaricin VI (2) were isolated from the Streptomyces spectabilis CCTCC M2017417 derived mutants of ΔstvP5 and ΔstvA2, respectively. The structures of 1 and 2 were established by analysis of the HRESIMS as well as 1D and 2D NMR datasets. The minimum inhibitory concentration (MIC) results showed that compounds 1 and 2 possessed the corresponding anti-MRSA bioactivities of 4 ∼ 8 μg/ml and 8 ∼ 16 μg/ml, which confirmed the structure-activity relationships of streptovaricins reported previously and also revealed that addition of the hydroxyl group at C-8 increased the anti-MRSA activity. [ABSTRACT FROM AUTHOR]

Two new spirotetronate natural products, lobophorin L (1) and lobophorin M (2), together with three known lobophorin-like spirotetronate antibiotics (3–5) and two known ansamycins (6–7), were isolated from the marine-derived Streptomyces sp. 4506. The structures of 1 and 2 were established on the basis of HRESIMS as well as 1D and 2D NMR datasets. Antibacterial assay showed that, compounds 1 and 3–5 exhibited strong to moderate antibacterial activities against Micrococcus luteus and Bacillus thuringiensis with MIC values ranging from 0.0625 to 8 μg/mL, while compounds 3 and 6 showed weak antibacterial activities against Staphylococcus aureus and MRSA. The antibacterial activities of the lobophorins in this study indicated that the more substitution number of the sugar moieties at C-9 of the lobophorin, the stronger antimicrobial properties it may deserve, and the higher the oxidation degree of substituent group at C-3D, the better antibacterial activities of its corresponding compound could be. [ABSTRACT FROM AUTHOR]

A bioassay-guided fractionation led to the isolation of hangtaimycin (HTM) from Streptomyces spectabilis CCTCC M2017417 and the discovery of its hepatoprotective properties. Structure elucidation by NMR suggested the need for a structural revision. A putative HTM degradation product was also isolated and its structure was confirmed by total synthesis. The biosynthetic gene cluster was identified and resembles a hybrid trans-AT PKS/NRPS biosynthetic machinery whose first PKS enzyme contains an internal dehydrating bimodule, which is usually found split in other trans-AT PKSs. The mechanisms of such dehydrating bimodules have often been proposed, but have never been deeply investigated. Here we present in vivo mutations and in vitro enzymatic experiments that give first and detailed mechanistic insights into catalysis by dehydrating bimodules., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)