The latest rendition of the POSMOL conference, being comprised of the 20th International Workshop on Low-energy Positron and Positronium Physics and the 21st International Symposium on Electron–Molecule Collisions and Swarms, was successfully held at the Serbian Academy of Arts and Sciences, Belgrade, from July 18th to 20th 2019. Immediately thereafter, a one day workshop in honour of Professor Zoran Lj. Petrović, to acknowledge his many scientific contributions over a very distinguished career and to celebrate his retirement, was also held. This topical issue showcases contributions that encompass original research papers and topical reviews, on themes consistent with both POSMOL and the Workshop, as well as further contributions from the wider POSMOL community.

中文翻译：

---

电子，正电子和正电子的最新研究

POSMOL会议的最新成果包括在第20届低能正电子和正电子物理学国际研讨会以及第21届电子-分子碰撞与碰撞国际研讨会上，该研讨会在贝尔格莱德的塞尔维亚艺术与科学学院成功举行。从2019年7月18日至20日。此后不久，为纪念Zoran Lj教授举行的为期一天的研讨会。彼得罗维奇（Petrović）也要表彰他在非常杰出的职业生涯中所做的许多科学贡献并庆祝他的退休。本期主题展示了与POSMOL和研讨会一致的主题，包括原创研究论文和主题评论的贡献，以及来自更广泛的POSMOL社区的进一步贡献。