108 research outputs found

    Performances of Solid Oxide Cells with La0.97_{0.97}Ni0.5_{0.5}Co0.5_{0.5}O3δ_{3-\delta} as Air-Electrodes

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    Based on previous studies of perovskites in the quasi-ternary system LaFeO3_{3}–LaCoO3_{3}–LaNiO3_{3}, La0.97_{0.97}Ni0.5_{0.5}Co0.5_{0.5}O3_{3} (LNC) is chosen as the most promising air-electrode material in the series for solid oxide cells (SOCs). The properties of the material itself have been investigated in detail. However, the evaluation of LNC97 air electrodes in practical SOCs is still at a very early stage. In the present study, SOCs were prepared based on LNC97 air electrodes. The I-U performance of the SOCs in both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes, i.e. reversible SOCs (r-SOCs), was investigated systematically for different air-electrode designs, temperatures and fuel gases. In general, the performance of the r-SOCs tested in the present study is higher than the published results of other LaFeO3_{3}–LaCoO3_{3}–LaNiO3_{3}-based SOCs and is comparable to or even better than state-of-the-art La1x_{1-x}Srx_{x}Fe1y_{1-y}Coy_{y}O3_{3} (LSCF)-based SOCs. Mid-term operation of about 1000 h for SOCs in both SOFC and SOEC modes primarily proved the stability of LNC97-based air electrodes. Impedance spectra were systematically applied to understand the polarization processes of the SOCs

    Direct Recycling of Hot‐Deformed Nd–Fe–B Magnet Scrap by Field‐Assisted Sintering Technology

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    Recycling of Nd–Fe–B magnets is an ongoing challenge regarding circular economy. State‐of‐the‐art magnet production methods, such as hot deformation, have limitations with respect to direct recycling of magnet scrap particles that differ from pristine melt‐spun Nd–Fe–B powder. Recent work has shown that a combination of presintering by field‐assisted sintering technology/spark plasma sintering (FAST/SPS) and hot deformation by flash spark plasma sintering (flash SPS) has the potential to directly produce Nd–Fe–B magnets from 100% scrap material. Both processes have the capability to adjust and monitor process parameters closely, resulting in recycled magnets with properties similar to commercial magnets but made directly from crushed and recycled Nd–Fe–B powder that partially or completely replaces pristine melt‐spun Nd–Fe–B powder. Herein, a systematic study is done inserting recycled magnet particles into a flash SPS deformed magnet, considering the effects of different weight percentages of scrap material of varied particle size fractions. In some cases, coercivity HcJ of >1400 kAm⁻¹ and remanence Br of 1.1 T can be achieved with 20 wt% scrap material. The relationship between particle size fraction, oxygen uptake, and percentage of recyclate in a final magnet are all explored and discussed with respect to magnets made from pristine material

    Perinatal preterm brain injury. Risk assessment, antenatal surveillance and managing

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    This work reports the results of two different lines of research: 1. On the employment of ultrasound in the management of fetuses with intra-uterine growth restriction (IUGR); 2. On management of preterm birth for prevention of neurological impairment in high-risk pregnancies and low risk pregnancies. Pre-natal flow data and post-natal neurological outcome in IUGR fetuses have been evaluated. Doppler ultrasound in obstetrics has allowed the detection of the early signs of fetal demise, involving the management of pregnancies at risk of fetal hypoxia. The second line of research focuses on the need to identify strategies to predict preterm birth in asymptomatic low-risk women as well as in those presenting with threatened preterm labor (symptomatic high risk women) and underlines the importance to prevent brain injury and long-term neurological sequelae related to preterm deliveries. Neurological insults result in significant immediate and longterm physical, emotional, and financial costs. Advances in obstetrical and neonatal care have led to survival at earlier gestational ages and consequently increasing numbers of periviable infants who are at significant risk for long-term neurological deficits. Therefore, efforts to decrease and prevent cerebral insults attempt not only to improve neurological outcomes in infants delivered preterm but also primarily to decrease preterm delivery
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