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The behavior of a photovoltaic (PV) generator under specific irradiance and temperature conditions is mainly described by its current–voltage (I-V) characteristic. Therefore, the I-V curve tracing has to be considered the most accurate and effective diagnostic tool for the proper identification of PV panels’ failures. In this article, an innovative I-V curve tracer for individual PV panels is presented. It ensures the following advantages. 1) An optimized I-V curve measurement due to an innovative tracing algorithm. 2) In-situ characterization during normal operation owing to a proper disconnection circuit. 3) Full portability thanks to a Li-ion battery power supply and a Bluetooth communication. The proposed tool has been designed and realized. The resulting prototype has been used to measure the I-V curve of a PV panel both in uniform and partial shading conditions.

This study presents a comprehensive evaluation of an in-house developed current-voltage (I–V) curve tracer compared to the widely used Seaward PV200. Our device, a wireless, microcontroller-based tracer, is designed for precise monitoring of photovoltaic (PV) panels, significantly outperforming the PV200 in speed and measurement quality. Key features include an innovative disconnecting circuit that allows integration into PV strings without disrupting energy production and a control algorithm that evenly distributes measurement points along the I–V curve. Experimental results, obtained under nonuniform irradiation, demonstrate our tracer’s capability to accurately detect operational conditions, such as the activation of bypass diodes. Electroluminescence testing further validated the integrity and performance of the examined panels, emphasizing the importance of advanced instrumentation in enhancing solar energy system efficiency. Our findings highlight substantial advancements in PV diagnosis, offering a robust tool for performance analysis and fostering the development of efficient solar energy solutions.

This paper deals with operating speed and hazardousness on two-lane roads and will define the characteristics (components) of driving environments (scenarios) used in an analysis procedure developed by authors in a Decision Support System (DSS). DSS aims to identify infrastructure projects, given a total cost, suitable to produce maximum reduction of social cost of crashes. Results obtained are the improvement of the V85formula and the trend of the Crash Index as a function of flow/capacity ratio in limited access two-lane roads. Both results show that limited access roads and at grade intersections roads must be handled as different scenarios.

PSII catalyzes the oxidation of water and reduction of plastoquinone in oxygenic photosynthesis. PSII contains an oxygen-evolving complex, which is located on the lumenal side of the PSII reaction center and which contains manganese, calcium, and chloride. Four sequential photooxidation reactions are required to generate oxygen. This process produces five Sn-states, where nrefers to the number of oxidizing equivalents stored. Calcium is required for oxygen production. Strontium is the only divalent cation that replaces calcium and maintains activity. In our previous FT-IR work, we assessed the effect of strontium substitution on substrate-limited PSII preparations, which were inhibited at the S3to S0transition. In this work, we report reaction-induced FT-IR studies of hydrated PSII preparations, which undergo the full S-state cycle. The observed difference FT-IR spectra reflect long-lived photoinduced conformational changes in the oxygen-evolving complex; strontium exchange identifies vibrational bands sensitive to substitutions at the calcium site. During the S1′ to S2′ transition, the data are consistent with an electrostatic or structural perturbation of the calcium site. During the S3′ to S0′ and S0′ to S1′ transitions, the data are consistent with a perturbation of a hydrogen bonding network, which contains calcium, water, and peptide carbonyl groups. To explain our data, persistent shifts in divalent cation coordination must occur when strontium is substituted for calcium. A modified S-state model is proposed to explain these results and results in the literature.

In oxygenic photosynthesis, PSII carries out the oxidation of water and reduction of plastoquinone. The product of water oxidation is molecular oxygen. The water splitting complex is located on the lumenal side of the PSII reaction center and contains manganese, calcium, and chloride. Four sequential photooxidation reactions are required to generate oxygen from water; the five sequentially oxidized forms of the water splitting complex are known as the Sn states, where n refers to the number of oxidizing equivalents stored. Calcium plays a role in water oxidation; removal of calcium is associated with an inhibition of the S state cycle. Although calcium can be replaced by other cations in vitro, only strontium maintains activity, and the steady-state rate of oxygen evolution is decreased in strontium-reconstituted PSII. In this article, we study the role of calcium in PSII that is limited in water content. We report that strontium substitution or 18OH2 exchange causes conformational changes in the calcium ligation shell. The conformational change is detected because of a perturbation to calcium ligation during the S1 to S2 and S2 to S3 transition under water-limited conditions.

An intracellular mechanism activated by nicotinic acid adenine dinucleotide phosphate (NAADP+) contributes to intracellular Ca2+release alongside inositol 1,4,5-trisphosphate (Ins-P3) and ryanodine receptors. The NAADP+-sensitive mechanism has been shown to be operative in sea urchin eggs, ascidian eggs, and pancreatic acinar cells. Furthermore, most mammalian cell types can synthesize NAADP+, with nicotinic acid and NADP+as precursors. In this contribution, NAADP+-induced Ca2+release has been investigated in starfish oocytes. Uncaging of injected NAADP+induced Ca2+mobilization in both immature oocytes and in oocytes matured by the hormone 1-methyladenine (1-MA). The role of extracellular Ca2+in NAADP+-induced Ca2+mobilization, which was minor in immature oocytes, was instead essential in mature oocytes. Thus, the NAADP+-sensitive Ca2+pool, which is known to be distinct from those sensitive to inositol 1,4,5-trisphosphate or cyclic ADPribose, apparently migrated closer to (or became part of) the plasma membrane during the maturation process. Inhibition of both Ins-P3and ryanodine receptors, but not of either alone, substantially inhibited NAADP+-induced Ca2+mobilization in both immature and mature oocytes. The data also suggest that NAADP+-induced Ca2+mobilization acted as a trigger for Ca2+release via Ins-P3and ryanodine receptors.

Organelles and neurons of nematodes involved in sensing chemical signals present in the environment are described. Laser ablation of neurons has helped assign them a specific function. Genetic mutational analysis has led to the identification of genes controlling the behaviour of the worms and/or some cellular properties of the chemosensory neurons. Some conclusions on the general organization and functioning of chemoreception in nematodes can be drawn.

The neurodegenerative disease Friedreich's ataxia is caused by lower than normal levels of frataxin, an important protein involved in iron–sulfur (Fe-S) cluster biogenesis. An important step in designing strategies to treat this disease is to understand whether increasing the frataxin levels by gene therapy would simply be beneficial or detrimental, because previous studies, mostly based on animal models, have reported conflicting results. Here, we have exploited an inducible model, which we developed using the CRISPR/Cas9 methodology, to study the effects of frataxin overexpression in human cells and monitor how the system recovers after overexpression. Using new tools, which range from high-throughput microscopy to in cell infrared, we prove that overexpression of the frataxin gene affects the cellular metabolism. It also leads to a significant increase of oxidative stress and labile iron pool levels. These cellular alterations are similar to those observed when the gene is partly silenced, as occurs in Friedreich's ataxia patients. Our data suggest that the levels of frataxin must be tightly regulated and fine-tuned, with any imbalance leading to oxidative stress and toxicity.

Abruzzese: BMS, Novartis, Pfizer, Ariad: Consultancy. Assouline:BMS: Consultancy; Pfizer: Consultancy; Novartis: Consultancy. D'Emilio:Celgene: Research Funding. Dong-Wook:ll-Yang: Consultancy, Honoraria, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau.

No relevant conflicts of interest to declare.