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The use of dc–dc converters for in-situ electrochemical impedance spectroscopy has been investigated by several works in recent years, with different implementation strategies and promising results. There are, however, two important limitations that still hinder a commercial application of this technique: first, the need to deal with the battery discharge during the measurement, particularly critical at very low frequencies; second, the difficulty of accurately measuring the small ac voltage response of several cells in a pack, with common-mode dc voltages that can be five (or more) orders of magnitude higher. This article addresses both challenges, from an instrumentation and measurement perspective, presenting a solution for impedance measurements down to 10 mHz, on a system composed of 16 lithium-iron-phosphate cells or modules connected in series. A dc–dc boost converter is used to inject a multisine current perturbation on all batteries, with closed-loop control, and all cell voltages are conditioned to optimize the measurement resolution and accuracy of their ac components. Suitable signal processing compensates for the voltage drift caused by the battery discharge, and evaluates the residual distortion in the signal, to assess the validity of the impedance estimate. Experimental tests confirm that the obtained results are sufficiently precise (or repeatable) to allow detecting impedance variations occurring during the battery discharge or after repeated charge/discharge cycles.

The IEEE Open Journal of Instrumentation and Measurement (OJIM) took its first steps in 2022 and opened a new and exciting venue for contributions on emerging topics from experts in the field. One of the long-standing subjects in the context of instrumentation and measurement is represented by power and energy measurements. In recent decades, this, so to speak, rather traditional field of research has received a new and impressive boost from the evolution of the industrial and economic context, but also from the pressing need to face the environmental problems affecting our Planet, whose mitigation demands a green revolution. Pursuing decarbonization means migrating from fossil fuel toward the intensive exploitation of renewable energy sources. A transition of such a magnitude relies on the ubiquitous presence of electricity and requires the electrification of most of our consumption. All these objectives ask for a new paradigm for energy systems, which shall combine centralized and distributed renewable energy generation, local energy storage, integration with electric mobility, communication, advanced automation, etc.

Endoplasmic reticulum (ER) to nucleus homeostatic signaling, known as the unfolded protein response (UPR), relies on the non-canonical splicing of XBP1 mRNA. The molecular switch that initiates splicing is the oligomerization of the ER stress sensor and UPR endonuclease IRE1α (inositol-requiring enzyme 1 alpha). While IRE1α can form large clusters that have been proposed to function as XBP1 processing centers on the ER, the actual oligomeric state of active IRE1α complexes as well as the targeting mechanism that recruits XBP1 to IRE1α oligomers remains unknown. Here, we have developed a single-molecule imaging approach to monitor the recruitment of individual XBP1 transcripts to the ER surface. Using this methodology, we confirmed that stable ER association of unspliced XBP1 mRNA is established through HR2 (hydrophobic region 2)-dependent targeting and relies on active translation. In addition, we show that IRE1α-catalyzed splicing mobilizes XBP1 mRNA from the ER membrane in response to ER stress. Surprisingly, we find that XBP1 transcripts are not recruited into large IRE1α clusters, which are only observed upon overexpression of fluorescently tagged IRE1α during ER stress. Our findings support a model where ribosome-engaged, immobilized XBP1 mRNA is processed by small IRE1α assemblies that could be dynamically recruited for processing of mRNA transcripts on the ER.

Early life events are associated with the susceptibility to chronic diseases in adult life. Perturbations of endoplasmic reticulum (ER) homeostasis activate the unfolded protein response (UPR), which contributes to the development of metabolic alterations. Our aim was to evaluate liver UPR in an animal model of intrauterine growth restriction (IUGR). A significantly increased expression of X-box binding protein-1 spliced (XBP1s) mRNA (p