Characterization of LiFePO4/C Cathode for Lithium Ion Batteries

International audienceLiFePO4/C was synthesized from a mixture of different precursors of Li, Fe, and C by solid-state reaction. The initial mixture obtained was heated in different calcination conditions under inert atmosphere. The precursor of LiFePO4 doped with carbon was studied using different techniques such as thermal analysis, chemical and physical characterizations, and Mosbauer spectroscopy. A calculation of the crystallinity of the final product with two different methods is also presented. The chemical analysis techniques used were IRTF, XRD, and SEM. This characterization confirmed that we obtained a well-crystallized LiFePO4/C in all the operating conditions tested. The SEM showed aggregation and sintering during the calcination process, which were confirmed by the particle-size distribution measurements and by the physical characterizations. Mosbauer spectroscopy was used to determine the quantity of Fe(II) and Fe(III) contained in the final product. Our calcination conditions did not significantly modify the quantity of the two oxidation states

Psychological distress among hospital caregivers during and after the first wave of COVID-19: Individual factors involved in the severity of symptoms expression

Coronavirus disease 2019 has spread rapidly over the globe and has put an unprecedent psychological pressure on health care workers (HCWs). The present study aimed at quantifying the psychological consequences of the COVID-19 pandemic on HCWs during and after the first wave and identify sociodemographic, situational, and psychological risk/protective factors for symptoms severity. An online survey was sent by e-mail to all nurses and physicians employed by a teaching hospital in Brussels, Belgium. 542 (20,62%) completed the survey. 47%, 55%, 32% and 52% of participants reported posttraumatic stress, anxiety, depression and insomnia symptoms, respectively, during the peak. Two to three months later, posttraumatic symptoms emerged de novo in 54% of HCWs. It persisted in 89% of those presenting severe symptoms initially. Neuroticism was the strongest predictor of posttraumatic stress, anxiety, and insomnia. Work overload was the strongest predictor of depression and second predictor of posttraumatic stress, anxiety, and insomnia. Other significant predictors included being a nurse, the number of past traumatic experiences, avoidant coping style, and expressive suppression of emotion

Effect of physicochemical and thermal treatment on the environmental behavior of sediments

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Effect of phosphatation and calcination on the environmental behaviour of sediments

International audienceDredging operations produce considerable quantities of materials, to be managed and this opens an opportunity for valorization in civil engineering. However, the contamination of the dredged sediments has become a major problem to solve. The major contaminants are heavy metals and organic compounds. This study focuses on the use of phosphoric acid (H3PO4) to stabilize heavy metals from sediments and destroy organic matter by calcination at 650 °C with a goal of using sediments in roadworks. Several studies have been conducted in this field. The stabilized materials obtained have been used in civil engineering. The main purpose of this work is to discuss the environmental behavior of marine sediment treated by phosphatation and calcination. Two types of phosphoric acids were used. The pH dependence leaching test has been used as the basic characterization to evaluate the effect of the type of phosphoric acid on the metals behavior in a valorization scenario. The standard leaching test and the Toxicity Characteristic Leaching Procedure (TCLP) were conducted as compliance tests. In regards of the obtained results, the environmental assessment has also shown a reduction in the availability of targeted heavy metals in alkaline environment whatever the type of acid used for treatment. This opens opportunities for co-valorization

Effect of physicochemical and thermal treatment on the environmental behavior of sediments

International audienc

Effect of physicochemical and thermal treatment on the environmental behavior of sediments

International audienc

Effects of treatments on the environmental behavior of dredged sediment

International audienc

Clay/phosphate-based ceramic materials for thermal energy storage – Part I: Effect of synthetic phosphate content on microstructure, thermo-physical and thermo-mechanical properties

Fired clay ceramics are promising materials for TES, thanks to their thermal stability, availability worldwide, low cost and easy shaping and handling. However, their thermo-physical and thermo-mechanical properties have to be improved. For the first time, clay-phosphate ceramics, with synthetic calcium hydroxyapatite (TCP, Ca10(PO4)6(OH)2) as additive, were developed in view of TES application. A parametric study was carried out for different clay/TCP mixtures, wherein the TCP percentage varies from 0 to 16.7 wt%. The best material containing 4.7 wt% TCP allowed increasing up to 20% of the thermal conductivity and 23% of the mechanical strength. Moreover, it was thermally stable up to 1000 °C. These original results demonstrate the suitability of these new materials for heat storage in energy systems such as in a concentrated solar power (CSP) plant, or in a unit of heat recovery from an industrial waste heat source

SITUATIONAL AND PERSONAL PREDICTORS OF MENTAL HEALTH OUTCOMES AMONG HEALTH CARE WORKERS DURING COVID-19: DIFFERENCES BETWEEN NURSES AND PHYSICIANS

Background: Caregivers have been exposed to important stresses during the COVID-19 pandemic leading to important mental health issues. Previous researches showed that nurses were particularly emotionally affected compared to physicians. Aims: To study the differences in psychological symptoms between nurses and physicians during the first wave of the COVID-19 pandemic as well as three months later and to compare the predictors of these symptoms between both professions. Method: An online survey was sent to all nurses and physicians employed by a university hospital in Belgium. It assessed symp- toms of post-traumatic stress, anxiety, depression and insomnia induced by the COVID-19 experienced during the peak and at the moment of assessment (3 months after the peak). Sociodemographic and work-related characteristics as well as psychological factors, i.e., emotion regulation habits, coping strategies and personality traits were also evaluated as potential predictors of psychological symptoms. Results: Nurses reported more pronounced psychological symptoms associated to the COVID situation compared to physicians. In nurses, the strongest predictor of psychological symptoms was the level of neuroticism while in physicians it was the work overload. Conclusions: Our study provided essential information which may allow to better orient interventions according to the difficul- ties and specificities presented by each occupation