https://www.selleckchem.com/products/bay-1161909.html Theoretical description of a four-level system for luminescent thermometry was proposed. Based on this description, the sensitivity was proved not to exceed Sr =|E23 - E12|/T2, where T is the temperature and |E23 - E12| is the absolute energy difference between the excited state energy gaps. The analysis was verified for the terbium-europium coordination compounds, the most studied class of four-level thermometry systems, which revealed that most of the examples fall within either this theory or represent three-level systems, where the ligand is not involved in the thermally-activated processes. From this description, it follows that the highest Sr can be reached either when the triplet state is not involved or when the ligand triplet state is very high, which in the case of terbium-europium coordination compounds means exceeding 26 800 cm-1.Correction for 'X-ray pair distribution function analysis and electrical and electrochemical properties of cerium doped Li5La3Nb2O12 garnet solid-state electrolyte' by Bo Dong et al., Dalton Trans., 2020, 49, 11727-11735, DOI 10.1039/d0dt02112a. RNA viruses exhibit an extraordinary ability to evolve in a changing environment and to switch from animal hosts to humans. The ongoing COVID-19 pandemic, recognized as a respiratory disease, is an example of zoonotic transmission of the RNA virus known as SARS-CoV-2. The development and regulatory approval of a vaccine against SARS-CoV-2 pose multiple preventive and therapeutic challenges, especially during an ongoing pandemic. The review intended to examine the challenges and recent achievements in the development of vaccine candidates against COVID-19. The research team performed a literature review, searching relevant and up to date information from the literature. The sources of data included Google Scholar, PubMed, NCBI, and Yahoo. The search terms used were COVID-19 challenges, SARS-CoV-2 prospective challenges, RNA viruses ado