The purpose of this work was to study the performance of a sodium-ion battery based on the sodium vanadium phosphate /sodium titanate in the temperature range from +20 to-45 °C. To achieve this goal the methods of galvanostatic cycling and pulse chronopotentiometry were used. The performance of sodium-ion battery at low temperatures was found to be limited by the functioning of the negative electrode based on sodium titanate, which remains operational only at temperatures not less than-35 °C. The positive electrode based on sodium vanadium phosphate is efficient at temperatures down to-45 °C. The activation energy of sodium diffusion in the sodium vanadium phosphate and the sodium titanate is about 42 and 70 kJ / mol, respectively.

No abstract

Bioimaging techniques require development of a wide variety of fluorescent probes that absorb and emit red light. One way to shift absorption and emission of a chromophore to longer wavelengths is to modify its chemical structure by adding polycyclic aromatic hydrocarbon (PAH) fragments, thus increasing the conjugation length of a molecule while maintaining its rigidity. Here, we consider four novel classes of conformationally locked Green Fluorescent Protein (GFP) chromophore derivatives obtained by extending their aromatic systems in different directions. Using high-level ab initio quantum chemistry calculations, we show that the alteration of their electronic structure upon annulation may unexpectedly result in a drastic change of their fluorescent properties. A flip of optically bright and dark electronic states is most prominent in the symmetric fluorene-based derivative. The presence of a completely dark lowest-lying excited state is supported by the experimentally measured extremely low fluorescence quantum yield of the newly synthesized compound. Importantly, one of the asymmetric modes of annulation provides a very promising strategy for developing red-shifted molecular emitters with an absorption wavelength of ∼600 nm, having no significant impact on the character of the bright S-S1 transition.