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The lead–acid battery is still widely used today and will continue to be one of the benchmarks for diverse scenarios and applications. Although their energy densities are lower than more modern chemistries, the economic advantages of lead–acid batteries outweigh the disadvantages for numerous applications in transportation and stationary markets, uninterruptible power supply, and energy storage for wind or solar-based renewable systems. Nevertheless, optimizing their utility requires the continuous assessment of the state of health (SoH). The existing SoH estimation techniques use extrinsic quantities such as current, voltage, impedance, and temperature obtained through invasive (i.e., probing) methods. However, probing methods do not facilitate seamless cell-level charging to balance the SoH of the entire battery. Our study explored the non-invasive estimation of the battery SoH using acoustic energy. This method used sound both as an emitted and received signal propagating across the internal structure of a battery cell element unit (CEU) during its operation. Information from the received signals is analyzed relative to the aging degree of the lead–acid battery. The patterns of the received sound contain information on the CEU structure, which a data-driven algorithm subsequently encoded into a binary classifier of SoH levels: above 80% and below 80%. Results show that the binary classifier can distinguish between the two classes. A non-invasive SoH estimation technique can support the seamless operation of cell-level charging for lead–acid batteries. Balancing the SoH among all cells is needed to sustain the use life of the entire battery.

The podand-type ligand L, based on a tertiary amine substituted by three pyridyl-6-phosphonic acid functions, forms hydrated complexes with Ln3+ cations. The luminescence properties of the YbL complex were studied in D2O as a function of the pD and temperature. In basic conditions, increases in the luminescence quantum yield and the excited state lifetime of the Yb centered emission associated with the 2F5/2 → 2F7/2 transition were observed and attributed to a change in the hydration number from two water molecules in the first coordination sphere of Yb at acidic pH to a single one in basic conditions. Upon the addition of TbCl3 salts to a solution containing the YbL complex in D2O, heteropolynuclear Yb/Tb species formed, and excitation of the Yb at 980 nm resulted in the observation of the typical visible emission of Tb as a result of a cooperative upconversion (UC) photosensitization process. The UC was further evidenced by the quadratic dependence of the UC emission as a function of the laser power density.

Rare-earth ion (REI)-doped systems are well suited for realising coherent light-spin interfaces, but demonstrations of spectral hole burning (SHB) in optical transitions of REI-based systems have been so far limited to REIs dispersed in matrices. Here, the authors report on transient SHB in a binuclear Eu(III) complex.

Mn2+ complexes of 2,4‐pyridyl‐disubstituted bispidine ligands have emerged as more biocompatible alternatives to Gd3+‐based MRI probes. They display relaxivities comparable to that of commercial contrast agents and high kinetic inertness, unprecedented for Mn2+ complexes. The chemical structure, in particular the substituents on the two macrocyclic nitrogens N3 and N7, are decisive for the conformation of the Mn2+ complexes, and this will in turn determine their thermodynamic, kinetic and relaxation properties. We describe the synthesis of four ligands with acetate substituents in positions N3, N7 or both. We evidence that the bispidine conformation is dependent on N3 substitution, with direct impact on the thermodynamic stability, kinetic inertness, hydration state and relaxivity of the Mn2+ complexes. These results unambiguously show that (i) solely a chair‐chair conformation allows for favorable inertness and relaxivity, and (ii) in this family such chair‐chair conformation is accessible only for ligands without N3‐appended carboxylates. [ABSTRACT FROM AUTHOR]

Up conversion is an Anti-Stokes luminescent process by which photons of low energy are piled up to generate light at a higher energy. Here, the authors report a supramolecular assembly of fluoride-bridged erbium complexes which exhibit this behaviour in D2O solution at room temperature.