Academic literature on the topic 'Cerium dioxide (CeO2)'
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Journal articles on the topic "Cerium dioxide (CeO2)"
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Boyko, Yu I. "Structural rearrangement and change of cerium valence in cerium dioxide (CeO2) nanocrystals." Functional materials 23, no. 2 (June 15, 2016): 202–5. http://dx.doi.org/10.15407/fm23.02.202.
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Channei, Duangdao, Panatda Jannoey, Auppatham Nakaruk, and Sukon Phanichphant. "Photocatalytic Activity of Cu-Doped Cerium Dioxide Nanoparticles." Key Engineering Materials 751 (August 2017): 801–6. http://dx.doi.org/10.4028/www.scientific.net/kem.751.801.
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Pure CeO2 and Cu-doped CeO2 nanoparticles with different doping amounts of Cu in the range of 0.5-2.0 wt.% were synthesized by the combination of homogeneous precipitation and impregnation methods. The effect of Cu on the correlation of structural, optical and photocatalytic properties of CeO2 were studied. The XRD results indicated that phase structures of pure CeO2 and Cu-doped CeO2 nanoparticles were cubic fluorite phase and no other characteristic peaks related to Cu were detected. TEM images revealed that all samples were spherical in shape with the size less than 10 nm. The shift of absorption edge of Cu-doped CeO2 catalysts, corresponding to a decrease of band gap energies from 3.2 to 2.8 eV, was also observed as the amount of Cu dopant increased. The photocatalytic performances of the Cu-doped CeO2 exhibited higher activity than pure CeO2 for photocatalytic degradation of methylene blue under visible light irradiation, and the CeO2 doped with 1.0 wt.% Cu exhibited the highest photocatalytic activity.
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Strobel, Claudia, Martin Förster, and Ingrid Hilger. "Biocompatibility of cerium dioxide and silicon dioxide nanoparticles with endothelial cells." Beilstein Journal of Nanotechnology 5 (October 17, 2014): 1795–807. http://dx.doi.org/10.3762/bjnano.5.190.
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Cerium dioxide (CeO2) and silicon dioxide (SiO2) nanoparticles are of widespread use in modern life. This means that human beings are markedly exposed to them in their everyday life. Once passing biological barriers, these nanoparticles are expected to interact with endothelial cells, leading to systemic alterations with distinct influences on human health. In the present study we observed the metabolic impact of differently sized CeO2 (8 nm; 35 nm) and SiO2 nanoparticles (117 nm; 315 nm) on immortalized human microvascular (HMEC-1) and primary macrovascular endothelial cells (HUVEC), with particular focus on the CeO2 nanoparticles. The characterization of the CeO2 nanoparticles in cell culture media with varying serum content indicated a steric stabilization of nanoparticles due to interaction with proteins. After cellular uptake, the CeO2 nanoparticles were localized around the nucleus in a ring-shaped manner. The nanoparticles revealed concentration and time, but no size-dependent effects on the cellular adenosine triphosphate levels. HUVEC reacted more sensitively to CeO2 nanoparticle exposure than HMEC-1. This effect was also observed in relation to cytokine release after nanoparticle treatment. The CeO2 nanoparticles exhibited a specific impact on the release of diverse proteins. Namely, a slight trend towards pro-inflammatory effects, a slight pro-thrombotic impact, and an increase of reactive oxygen species after nanoparticle exposure were observed with increasing incubation time. For SiO2 nanoparticles, concentration- and time-dependent effects on the metabolic activity as well as pro-inflammatory reactions were detectable. In general, the effects of the investigated nanoparticles on endothelial cells were rather insignificant, since the alterations on the metabolic cell activity became visible at a nanoparticle concentration that is by far higher than those expected to occur in the in vivo situation (CeO2 nanoparticles: 100 µg/mL; SiO2 nanoparticles: 10 µg/mL).
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Filippova, A. D., A. E. Baranchikov, and V. K. Ivanov. "Enzyme-Like Activity of Cerium Dioxide Colloidal Solutions Stabilized with L-Malic Acid." Коллоидный журнал 85, no. 5 (September 1, 2023): 668–81. http://dx.doi.org/10.31857/s0023291223600529.
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For the first time, stable aqueous colloidal solutions of cerium dioxide stabilized with L-malic acid have been obtained at ligand : CeO2 molar ratios of 0.2, 0.5, 1.0, and 2.0. Using dynamic light scattering, it has been shown that CeO2 sols are characterized by a narrow monomodal size distribution of aggregates, and the sols remain to be aggregatively stable in a Tris-HCl buffer solution. According to the chemiluminescence analysis of the enzyme-like activity of cerium dioxide sols with respect to hydrogen peroxide, the surface modification of the cerium dioxide particles with malic acid increases the enzyme-like activity of СеО2 up to 4.5 times.
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Stegniy, B. T., O. A. Demchenko, O. M. Korneykov, M. Yu Stegniy, A. Yu Oleshko, O. B. Korneikova, I. V. Korovin, L. P. Babenko, and M. Ya Spivak. "Antiviral Effect of Cerium Dioxide Nanoparticles on the Model of the Causative Agent of Bovine Viral Diarrhea." Mikrobiolohichnyi Zhurnal 83, no. 6 (December 17, 2021): 65–74. http://dx.doi.org/10.15407/microbiolj83.06.065.
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Cerium dioxide nanoparticles (CeO2) have a wide range of biological properties, including antiviral activity. Preparations based on cerium oxide nanoparticles can be effective against animal RNA viruses, which have the greatest epizootic significance for Ukraine and potentially against human viruses, including SARS-CoV-2. In our studies, we determined the effect of cerium dioxide nanoparticles on bovine viral diarrhea virus (BVDV), a pestivirus that is the etiological agent of bovine viral diarrhea. To determine the antiviral efficacy of CeO2, a cytopathogenic strain of BVDV “BK-1” was used as an etiological agent of bovine viral diarrhea, which induces a cytopathic effect on cow embryo lungs (CEL) cell culture. When evaluating the antiviral efficacy of CeO2, it was determined that the MPC for CEL cell culture is 0.057 μg/cm3, and the CC50 is 0.077 μg/cm3. The antiviral activity of CeO2 was evaluated by the IC50 index, which was 0.036 μg/cm3 and the selectivity index, which after co-administration of CeO2 with BVDV was 2.14. There was a decrease in the titer of infectious activity of the virus during treatment with CeO2 by 2.09 lg TCD50/cm3.
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Ahire, Satish Arvind, Ashwini Ashok Bachhav, Thansingh Bhavsing Pawar, Arun Vitthal Patil, Swapnil Sampatrao Shendge, and Prashant Bhimrao Koli. "Green Synthesis of Ceria Nanoparticles Using Azadirachta Indica Plant Extract: Characterization, Gas Sensing and Antibacterial Studies." Material Science Research India 18, no. 3 (December 30, 2021): 285–97. http://dx.doi.org/10.13005/msri/180304.
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In the present investigation we have fabricated the cerium dioxide (CeO2) nanoparticles by green route. While preparing the cerium dioxide nanoparticles by co-precipitation method, Neem leaf extract mixed into the precursor of cerium. The synthesized nanoparticles of CeO2 were used for the preparation of thick film sensor by using screen printing strategy. The fabricated CeO2 sensor was characterized by XRD, SEM, EDS and TEM techniques. The structural characteristics investigated by x-ray diffraction technique (XRD). XRD confirms the formation of cubic lattice of CeO2 material. The surface, texture, porosity characteristics were investigated from SEM analysis, while chemical composition of the material was analysed by EDS technique. The transmission electron microscopy (TEM) confirms the formation cubic lattice of the cerium dioxide material. The thickness of the films was calculated from mass difference method, the prepared film sensors belong to thick region. The fabricated material CeO2 sensor was applied as gas sensor to sense the gases such as LPG, petrol vapors (PV), toluene vapors (TV) and CO2. The CeO2 sensor showed excellent gas response for LPG and PV, nearly 93.20 % and 78.23 % gas response. The rapid response and recovery of the prepared sensors was observed at the tested gases. CeO2 material also employed for antibacterial study at several pathogenic organism such as pseudomonas, staphylococcus aureus and salmonella typhae. From antibacterial study it was observed that the material is capable of inhibiting the growth of these pathogenic microbes.
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Huang, Hui, and Zhong Cheng Guo. "Preparation and Characterization of Conductive Polyaniline/Cerium Dioxide Composites." Materials Science Forum 663-665 (November 2010): 686–89. http://dx.doi.org/10.4028/www.scientific.net/msf.663-665.686.
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Conductive polyaniline/cerium dioxide (PANI/CeO2) composites have been synthesized by in-situ polymerization of aniline in the presence of CeO2 nanoparticles. The structure and thermal stability of obtained composites were characterized by Fourier-transform infrared spectra (FTIR), Fourier-transform Raman spectra (FT-Raman), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results showed that PANI and CeO2 nanoparticles were not simply blended, and a strong interaction existed at the interface of CeO2 and PANI. In the PANI/CeO2 composite, the degree crystallinity of PANI increased and diffraction pattern of CeO2 was amorphous. And that the composites were more thermally stable than that of the pure PANI. Electrical conductivity measurements indicated that the conductivity of PANI/CeO2 composites was much higher than that of the pure PANI and the maximum conductivity obtained was 11.68 S/cm at 17.5 wt% of CeO2.
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Kim, Young-Soo, Jin-Kyu Lee, Jae-Hoon Ahn, Eun-Kyung Park, Gil-Pyo Kim, and Sung-Hyeon Baeck. "Fabrication of Mesoporous Cerium Dioxide Films by Cathodic Electrodeposition." Journal of Nanoscience and Nanotechnology 7, no. 11 (November 1, 2007): 4198–201. http://dx.doi.org/10.1166/jnn.2007.109.
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Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templatingagent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating.
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Deval, Gaëlle, Sonja Boland, Thierry Fournier, and Ioana Ferecatu. "On Placental Toxicology Studies and Cerium Dioxide Nanoparticles." International Journal of Molecular Sciences 22, no. 22 (November 12, 2021): 12266. http://dx.doi.org/10.3390/ijms222212266.
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The human placenta is a transient organ essential for pregnancy maintenance, fetal development and growth. It has several functions, including that of a selective barrier against pathogens and xenobiotics from maternal blood. However, some pollutants can accumulate in the placenta or pass through with possible repercussions on pregnancy outcomes. Cerium dioxide nanoparticles (CeO2 NPs), also termed nanoceria, are an emerging pollutant whose impact on pregnancy is starting to be defined. CeO2 NPs are already used in different fields for industrial and commercial applications and have even been proposed for some biomedical applications. Since 2010, nanoceria have been subject to priority monitoring by the Organization for Economic Co-operation and Development in order to assess their toxicity. This review aims to summarize the current methods and models used for toxicology studies on the placental barrier, from the basic ones to the very latest, as well as to overview the most recent knowledge of the impact of CeO2 NPs on human health, and more specifically during the sensitive window of pregnancy. Further research is needed to highlight the relationship between environmental exposure to CeO2 and placental dysfunction with its implications for pregnancy outcome.
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Lukin, Anton V., Galina I. Lukina, Alexey V. Volkov, Alexander E. Baranchikov, Vladimir K. Ivanov, and Alexey A. Prokopov. "Morphometry Results of Formed Osteodefects When Using Nanocrystalline CeO2 in the Early Stages of Regeneration." International Journal of Dentistry 2019 (December 26, 2019): 1–9. http://dx.doi.org/10.1155/2019/9416381.
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This paper studies of the use of nanocrystalline cerium dioxide with artificially formed bone tissue defects. The results of morphometry confirmed the antialterative effect in the early stages of the reparative process of damaged bone tissue. When using calcium hydroxide with nanodispersed cerium dioxide, the nature of osteogenesis should be characterized as activated. In case of damage to the dentin of the roots of the teeth, dentinogenesis in presence of CeO2 occurs with the formation of a combined dentin and bone regenerates. Little or no studies of dentinogenesis in presence of CeO2 were performed by other researchers.
Dissertations / Theses on the topic "Cerium dioxide (CeO2)"
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Walker, Nicholas David Leyland. "The role of the nano-environmental interface in ZnO and CeO2 nanoparticle ecotoxicology." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3734.
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An increase in nanotechnology has seen an associated rise in nanoparticles released into the environment. Their potential toxicity and exposure to humans and the environment, the field of nanoecotoxicology, is not yet well understood. The interactions at the nanoparticle surface will play a fundamental role in the nanoparticle behaviour once released into the environment. This study aims to characterise the particle surface interaction, determining key parameters influential in the nanoparticle fate. Evanescent Wave Cavity Ring Down Spectroscopy techniques have been applied to study molecular interactions at the silica-water charged interface. The adsorption of the electronic spectrum of Crystal Violet has demonstrated the formation of a monolayer with different binding site orientation at the interface. The binding affinity for the chromophore was calculated as 29.15 ± 0.02 kJmol-1 at pH 9 and this was compared with other interface structures involving both inorganic and organic components. The study of the model interface was extended to the properties of CeO2 nanoparticles, where the surface charge density was determined to be 1.6 ± 0.3 e- nm-2.The nanoparticle surface charge controls the suspension stability which was measured for CeO2 nanoparticles giving a stability half-life of 330 ± 60 hours in pure water, and 3.6 ± 0.6 hours in ISOFish water. Studies were extended to the toxicity of ZnO nanoparticles. An assay was developed to quantify the photo-electron production for nanoparticles exposed to UV light both in deionised water and soil suspensions with a photo-radical production yield of 19 ± 2 % and an electron production of 709 e-s-1np-1 for a 100 mgL-1 suspension. The species-specific photo-radical assay was subsequently used to determine the rate of ZnO nanoparticle dissolution in water and soil suspensions. Comparable dissolution rates in complex cell growth media were also measured, detecting total zinc by Inductively Coupled Plasma Atomic Emission Spectroscopy, with comparable dissolution rates derived.
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Werner, Kristin. "On the Role of Oxygen Vacancies in the Surface Chemistry of Ceria (CeO2)." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20496.
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Ceroxid (CeO2) wurde in den letzten Jahren als Katalysator für die Hydrierung von Alkinen zu Alkenen entdeckt und hat als solcher großes wissenschaftliches Interesse geweckt. Um weitere Einblicke in die Funktion von CeO2 in der Reaktion zu gewinnen, beschäftigt sich diese Arbeit mit der Adsorption von H2, CO2 und Propin, sowie mit der Interaktion von Hydroxylgruppen und Propin auf CeO2(111)-Oberflächen. Ein besonderer Fokus liegt dabei auf der Rolle von Sauerstoffleerstellen.In recent years, ceria (CeO2) has attracted much scientific interest due to its activity as a catalyst in the selective hydrogenation of alkynes to alkenes. To gain further insights into the role of CeO2 in propyne hydrogenation, this thesis explores the fundamental processes of H2, CO2, and propyne adsorption, as well as the interaction of hydroxyls and propyne on well-defined CeO2(111) surfaces. A special emphasis thereby lies on the role of oxygen (O) vacancies in these processes.
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Rosalino, Israel. "Propriedades estruturais e eletrônicas de clusters de (TiO2)n e (CeO2)n, n = 1-15, usando a teoria do funcional da densidade." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-26072016-141834/.
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O uso de dióxidos de metais de transição em aplicações tecnológicas é bastante amplo, pois esses compostos possuem características importantes de semicondutores. Apesar de existir um grande número de estudos experimentais e teóricos, o entendimento das propriedades estruturais e eletrônicas desses compostos ainda não é satisfatória, principalmente quando se envolve o estudo de clusters. Clusters podem ser definidos como uma fase embrionária da matéria, pois são partículas contendo um número muito reduzido de átomos em comparação com partículas macroscópicas. Logo, suas propriedades estruturais e eletrônicas são totalmente distantes da fase cristalina do material, o que permite o desenvolvimento de novos materiais para aplicações tecnológicas. Portanto, existe um grande interesse em compreender as propriedades estruturais e eletrônicas dos clusters. Neste projeto de mestrado temos como objetivo estudar as propriedades estruturais e eletrônicas de clusters de TiO2 e CeO2 , usando para isso cálculos de primeiros princípios com base na teoria do funcional da densidade (DFT). Um dos principais problemas no estudo de clusters é a determinação da estrutura atômica, devido as dificuldades experimentais envolvidas em se trabalhar com estruturas tão pequenas. Dessa forma, um dos nossos maiores desafios foi a determinação das estruturas atômicas dos clusters desses dois tipos de dióxidos de metais de transição, uma vez que, o nosso grupo (QTnano) já conta com grande experiência, principalmente no desenvolvimento e implementação de algoritimos de otimização global. Devido as dificuldades envolvidas no estudo de partículas tão pequenas, ficamos restritos ao estudo de clusters com composição (MO2)n , com n = 1-15, ou seja, os nossos maiores clusters tem um total de 45 átomos, formando estruturas com diâmetro de inferior a 3 nm. Além da obtenção das estruturas, foi realizado o estudo das propriedades eletrônicas, energéticas e vibracionais para cada uma das composições geradas, o que propiciou a melhor compreensão sobre os efeitos eletrônicos nas estrutura atômica dos clusters.The use of transition metal dioxides in technological applications is wide spread, because these compounds have important characteristics of semiconductors. Although there a large number of theoretical and experimental studies, the acknowledgement about the structural and electronic properties these compounds are not yet satisfactory, especially when studying clusters. Clusters can be defined as an embryonic phase of matter, because they are particles that contain a very small number of atoms in comparison with macroscopic particles. So, the structural and electronic properties are very distinct of the material crystalline phase, when allow the development of new materials in technological applications. Therefore a large interest exist in understanding the structural and electronic properties of clusters. In this master\'s degree project we have as objective to study the electronic and structural properties of TiO2 and CeO2 clusters, using first principle calculations based on the density functional theory (DFT). One of the main problems in the study of clusters is to determine the atomic structure, due the experimental difficult of work with so small particles. Thus, a great challenge was to determine the atomic structures of these two different transition metal dioxides, considering that our group (QTnano), has a large knowledge in the development and implementation of global optimization algorithms. Due the difficulty involved in studying small particles, we were restricted to the clusters of composition (MO2)n, with n = 1-15. In other words, our largest clusters have 45 atoms and a diameter smaller than 3 nm. Along with securing the structures, we realize the study of electronic, energetic and vibrational properties to each generated composition, providing an understanding of electronic effects in the atomic structure of clusters.
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Abbadi, Meryem. "Synthèse et caractérisation de solutions solides ZnO/CeO2 et CeO2/La2O3/ZnO pour la minéralisation photocatalytique du diclofénac de sodium en solution aqueuse." Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAF019.
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La présence de résidus pharmaceutiques dans les milieux aquatiques est une préoccupation majeure. Parmi ceux-ci, le diclofénac de sodium est un anti-inflammatoire non stéroïdien détecté dans les eaux usées. Parmi les méthodes de traitement de ces eaux, la photocatalyse hétérogène constitue une méthode efficace et prometteuse. Comparé au TiO2, largement utilisé en photocatalyse, le ZnO est une alternative présentant une activité photocatalytique intéressante sous irradiation UV. Cependant, son activité photocatalytique est atténuée par une recombinaison de charge plus rapide et une mauvaise séparation des paires électron-trou sous irradiation visible, et sa sensibilité à la photo-corrosion limite sa capacité à minéraliser les polluants récalcitrants sous rayonnement UV-visible. Afin d'améliorer l’activité photocatalytique du ZnO dans la région visible, son association avec des espèces métalliques est très attractive. Pour cela, nous avons opté pour l’oxyde de cérium CeO2 considéré comme un bon accepteur d’électrons et un excellent support de stockage d’oxygène en dehors de sa grande stabilité thermique et sa non-toxicité. Des matériaux de la solution solide Ce1-xZnxO2-x lacunaires en oxygène ont été préparés par voie de chimie douce en présence d’acide citrique et caractérisés par diverses techniques. L'insertion du cérium génère des lacunes en oxygène et des sites actifs responsables d'une meilleure minéralisation photocatalytique du diclofénac sous la lumière visible. Ensuite, nous avons synthétisé des composés ternaires CeO2/La2O3/ZnO et leur activité photocatalytique a été évaluée sous irradiation solaire pour la dégradation du diclofénac. Les résultats ont montré que l’addition de lanthane au sein de la solution solide Ce1-xZnxO2-x permet d’améliorer d’avantage la minéralisation photocatalytique du diclofénac dans l’eauThe presence of pharmaceutical residues in aquatic environments is a major concern. Among these, diclofenac sodium is a non-steroidal anti-inflammatory drug detected in wastewater. Among the methods of water treatment, heterogeneous photo catalysis constitutes an effective and promising method. Compared to TiO2, widely used in photo catalysis, ZnO is an alternative, which presents an interesting photocatalytic activity under UV irradiation. However, its photocatalytic activity is attenuated by faster charge recombination and poor separation of electron-hole pairs under visible irradiation, and its sensitivity to photo-corrosion limits its ability to mineralize recalcitrant pollutants under UV-visible radiation. In order to improve the photocatalytic activity of ZnO in the visible region, its association with metallic species is very attractive. For this, we opted for cerium oxide CeO 2 considered a good electron acceptor and an excellent oxygen storage medium apart from its great thermal stability and non-toxicity. Ce1-xZnxO2-x materials were prepared by soft-chemistry in the presence of citric acid, and characterized by various techniques. The insertion of cerium generates oxygen vacancies and active sites responsible for better photocatalytic mineralization of diclofenac under visible light. Then, we synthesized CeO2/La2O3/ZnO ternary compounds and their photocatalytic activity was tested under solar irradiation for the degradation of diclofenac. The results showed that the addition of lanthanum to the Ce1-xZnxO2-x solid solution further improves the photocatalytic mineralization of diclofenac in water
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Benzakour, Mohammed. "Contribution à l'étude des composés non stoechiométriques partiellement ioniques application au dioxyde de cerium CeOx /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37611829r.
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Bourja, Lamia. "Étude du système CeO2-Bi2O3 pour applications catalytiques et conductimétriques." Phd thesis, Toulon, 2011. http://tel.archives-ouvertes.fr/tel-00659119.
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Dans le cadre général des études de matériaux multifonctionnels, électrolytiques et catalytiques, susceptibles d'être utilisés au sein de dispositifs de détection de gaz, un système d'oxydes (1-x)CeO2. x/2Bi2O3 avec 0≤x≤1 a été élaboré par coprécipitation puis traitement thermique à 600°C. Le système ainsi obtenu correspondrait à un diagramme de phases original, constitué d'un domaine de solutions solides (Ce1-xBixO2-z pour x ≤ 0,20), d'un domaine multiphasé pour 0,3≤x≤0,7 comportant une phase de type quadratique b'-Bi2O3 et une phase cubique substituée limite (x=0,20), d'un autre domaine multiphasé pour les compositions 0,8≤x≤1, comportant une phase quadratique b-Bi2O3 et une phase monoclinique. Ces deux phases ont déjà été considérées dans la littérature comme phases métastables résultant de divers modes de refroidissement de la phase pure Bi2O3. Dans le cas présent, la stabilisation de ces deux phases b' et b en présence d'une phase substituée cubique Ce1-xBixO2-z pourrait être due à la présence d'ions cérium au sein duréseau cristallin de Bi2O3. Les interactions catalytiques entre des échantillons polycristallins de ce système avec x variable et des mélanges air-CO et air CH4 ont été étudiées par spectroscopie infrarouge à transformée de Fourier dans le domaine 100 à 525°C. Il apparait que les composés riches en cérium ou riches en bismuth n'ont pas la même réactivité vis-à-vis des gaz CH4 ou CO. Cette diversité de propriétés catalytiques pourrait être utilisée au sein de systèmes multicapteurs de gaz.Une étude de la conduction électrique du système pour x variable a été effectuée par spectroscopie d'impédance électrique entre 100 et 750°C. Les représentations Nyquist des impédances électriques ont été interprétées en mettant en jeu des modèles de type élément de phase constante ou de type Warburg pour prendre en compte l'hétérogénéité des échantillons ainsi que les phénomènes de réaction-diffusion aux électrodes. La conductivité en volume (coeur de grains) augmente avec la composition, avec deux types d'évolutions distinctes : une évolution caractéristique de la phase substituée liée à l'augmentation du taux de lacunes, une évolution dans le système biphasé avec une forte augmentation de conductivité au-dessus de x=0,3 et un maximum atteint pour x=0,7. La phase quadratique de type b'-Bi2O3 connue comme phase métastable est ainsi stabilisée au sein de ce système mixte, au moins à 600°C: elle serait à l'origine de la forte conductivité ionique observée pour la composition proche de x = 0,7.
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Bourja, Lamia. "Étude du système CeO2-Bi2O3 pour applications catalytiques et conductimétriques." Electronic Thesis or Diss., Toulon, 2011. http://www.theses.fr/2011TOUL0007.
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Dans le cadre général des études de matériaux multifonctionnels, électrolytiques et catalytiques, susceptibles d’être utilisés au sein de dispositifs de détection de gaz, un système d’oxydes (1-x)CeO2. x/2Bi2O3 avec 0≤x≤1 a été élaboré par coprécipitation puis traitement thermique à 600°C. Le système ainsi obtenu correspondrait à un diagramme de phases original, constitué d’un domaine de solutions solides (Ce1-xBixO2-z pour x ≤ 0,20), d’un domaine multiphasé pour 0,3≤x≤0,7 comportant une phase de type quadratique b’-Bi2O3 et une phase cubique substituée limite (x=0,20), d’un autre domaine multiphasé pour les compositions 0,8≤x≤1, comportant une phase quadratique b-Bi2O3 et une phase monoclinique. Ces deux phases ont déjà été considérées dans la littérature comme phases métastables résultant de divers modes de refroidissement de la phase pure Bi2O3. Dans le cas présent, la stabilisation de ces deux phases b’ et b en présence d’une phase substituée cubique Ce1-xBixO2-z pourrait être due à la présence d’ions cérium au sein duréseau cristallin de Bi2O3. Les interactions catalytiques entre des échantillons polycristallins de ce système avec x variable et des mélanges air-CO et air CH4 ont été étudiées par spectroscopie infrarouge à transformée de Fourier dans le domaine 100 à 525°C. Il apparait que les composés riches en cérium ou riches en bismuth n'ont pas la même réactivité vis-à-vis des gaz CH4 ou CO. Cette diversité de propriétés catalytiques pourrait être utilisée au sein de systèmes multicapteurs de gaz.Une étude de la conduction électrique du système pour x variable a été effectuée par spectroscopie d’impédance électrique entre 100 et 750°C. Les représentations Nyquist des impédances électriques ont été interprétées en mettant en jeu des modèles de type élément de phase constante ou de type Warburg pour prendre en compte l’hétérogénéité des échantillons ainsi que les phénomènes de réaction-diffusion aux électrodes. La conductivité en volume (coeur de grains) augmente avec la composition, avec deux types d’évolutions distinctes : une évolution caractéristique de la phase substituée liée à l’augmentation du taux de lacunes, une évolution dans le système biphasé avec une forte augmentation de conductivité au-dessus de x=0,3 et un maximum atteint pour x=0,7. La phase quadratique de type b’-Bi2O3 connue comme phase métastable est ainsi stabilisée au sein de ce système mixte, au moins à 600°C: elle serait à l’origine de la forte conductivité ionique observée pour la composition proche de x = 0,7To develop multifunctional and sensitive materials for gas sensor, catalytic microsystems and electrolytic applications, the multiphase system (1-x).CeO2 + ½ x.Bi2O3 has been investigated in the bismuth composition range 0≤x≤1. A series of ceramics samples has been prepared via a coprecipitation route followed by a thermal treatment at 600°C. X-ray diffraction analyses showed that, for x ≤ 0.20, a solid solution Ce1- xBixO2-x/2 with fluorine structure was formed. For x ranging between 0.25 and 0.7, a tetragonal b’-Bi2O3 phase coexisting with the solid solution was observed. For x ranging between 0.8 and 0.9, a new tetragonal b'-Bi2O3 phase, closely related to the b' phase was evidenced. Finally, close to x=1, the classical monoclinic a-Bi2O3 structure crystallized. The formation of such intermediate tetragonal b and b’ phases could be due of theprobable presence of cerium cations in the Bi2O3 lattice. The solid–gas interactions between these polycristalline materials and air–CH4 and air–CO flows have been studied as a function of time, temperature and composition x, using Fourier transform infrared (FTIR) analyses of the conversions of CH4 and CO gases into the CO2 gas. For all compositions, a low catalytic reactivity was observed with air–CH4 gas flows, while, for the highest bismuth compositions, a high catalytic reactivity was observed with air–CO gas flows. The electrical conduction of this series of polycrystalline samples has been analyzed using electrical impedance spectroscopy, in the temperature range 25 to 750°C. To interpret the Nyquist representations of electrical analyses, various impedance models including constant phase elements and Warburg impedances have been used. The optimal conduction observed close to composition x=0.7 should be due to the stabilization of the tetragonal b’ Bi2O3 phase. This specific multiphase system could present a high interest in catalytic and electrolytic applications
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Salerno, Alicia. "Évaluation de l’efficacité de dégradation et de décontamination cutanée du CeO2 vis-à-vis d’un composé organophosphoré, le Paraoxon." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1145/document.
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Les neurotoxiques organophosphorés sont des agents chimiques qui font partie de la menace NRBC (nucléaire, radiologique, biologique, chimique). Ces agents peuvent pénétrer l'organisme par inhalation, ingestion ou absorption cutanée. La principale voie d'absorption des agents chimiques peu volatils (persistants), tels que le VX et l'ypérite, est la voie cutanée. La décontamination des surfaces cutanées non protégées est donc cruciale pour empêcher une absorption trop importante du toxique et une intoxication. Ce travail s'est attaché à évaluer la capacité de nanoparticules d'oxyde de cérium à adsorber et à dégrader les composés organophosphorés, en utilisant un pesticide organophosphoré, le Paraoxon, et un modèle d'étude in vitro, la peau d'oreille de porc. Les résultats ont montré que la cérine, sous forme de poudre de nanoparticules, dégrade le Paraoxon mais ne permet pas de réduire son absorption à travers la peau. Des formes liquides contenant la cérine (suspension aqueuse, émulsi on de Pickering) ont été développées, pour éviter la dispersion des nanoparticules dans l'air lors de l'utilisation. Elles permettent une élimination plus efficace du Paraoxon, mais l'activité de dégradation de la cérine est très faible. L'influence des conditions de synthèses sur les propriétés physico-chimiques de la cérine en relation avec l'efficacité de dégradation a été étudiée. Les résultats montrent que la surface spécifique est un paramètre clé et que le protocole d'application des décontaminants doit être adaptéThe organophosphorus nerve agents form part of chemical agents which pose the NRBC threat (nuclear, radio, biological, chemical). These agents can get into the body by inhalation, ingestion or skin absorption. The main route of chemical agent absorption which are low volatile, as VX or yperite, is the dermal route. Decontamination of unprotected skin areas is crucial to prevent excessive absorption of toxic. This work aimed at evaluating the ability of cerium oxide nanoparticles to adsorb and degrade organophosphorus compounds by using an organophosphorus pesticide, Paraoxon, and an in vitro model, pig-ear skin. The results showed that ceria, in powder form, degraded the Paraoxon but did not allow reducing its absorption through the skin. Liquid forms containing ceria (aqueous suspension, Pickering emulsion) have been formulated in order to avoid the dispersion of particles in the air during its use. While liquid formulations allow more efficient removal of Paraoxon during decontamin ation process, the degradation activity of ceria was low. The influence of the synthesis conditions on the physicochemical properties of ceria linked to degradation efficiency of nanoparticles has been studied. The results showed that specific surface area is the key parameter and that the application protocol of decontaminants must be adapted
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Koehle-Divo, Vanessa. "Effets de nanomatériaux chez deux espèces de bivalves le long d'un gradient de salinité : approches intégrées physiologiques et moléculaires." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0254.
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Les nanotechnologies sont en plein essor et mènent à l’incorporation de nanomatériaux manufacturés (NMM) dans les produits d’usage courant. La synthèse de NMM et l’utilisation des produits en contenant conduit au rejet dans l’environnement de NMM pour lesquels le risque n’est pas encore connu. Les propriétés physico-chimiques particulières des NMM rendent difficile l’évaluation de leur toxicité qui reste encore actuellement non complétement élucidée. Cette thèse est intégrée au projet ANR NanoSalt (2013 - 2017) et vise à évaluer le devenir et les effets de NMM de dioxyde de cérium et d’oxyde de cuivre sur deux espèces de bivalves représentatives des eaux douces (Corbicula fluminea) et des eaux marines (Scrobicularia plana). Les organismes ont été exposés à des concentrations réalistes de ces NMM à différentes étapes de leur cycle de vie et ce, à travers la mise en place d’expositions de plus en plus proches des conditions environnementales (micro- et mésocosmes). Actuellement, très peu d'études de nanotoxicologie ont adopté une approche de biologie moléculaire pour évaluer et comprendre les effets des NMM chez les invertébrés, particulièrement chez les espèces non séquencées. Un des objectifs de la thèse était d’utiliser l'approche de qPCR pour évaluer la perturbation de l’expression de gènes par les NMM. Ce travail a permis de déterminer le devenir et le comportement des NMM dans les différentes conditions d’exposition. L’évaluation des effets des NMM a été réalisée à différents niveaux biologiques (moléculaire, cellulaire, individuel). L’utilisation d’outils de statistiques multivariées s’est révélée particulièrement utile pour analyser les variations d’expression des nombreux gènes ciblés. L’approche multi-marqueurs sur plusieurs niveaux biologiques a permis l’intégration d’un grand nombre de données qui a généralement permis de départager les effets des différentes formes de NMMNanotechnology is constantly evolving and leads to the incorporation of engineered nanomaterials (ENM) into daily commercial products. The synthesis of ENM and the use of products containing those ENM leads to their release in the environment but the risk of ENM is not yet known. The particular physico-chemical properties of ENM makes the evaluation of their toxicity particularly difficult and still not completely solved now. This thesis is integrated to the ANR NanoSALT (2013-2017) and aims to evaluate the fate and the effects of cerium dioxide and copper oxide ENM in two bivalve species representative of freshwaters (Corbicula fluminea) and of seawaters (Scrobicularia plana). The organisms were exposed to realistic concentrations of these ENM at different stage of their life-cycle, and through the setting up of exposure increasingly closed to environmental conditions (micro- and mesocosms). Nowadays, few nanotoxicology studies have adopted an approach of molecular biology for the evaluation and the comprehension of ENM effects in invertebrates, and more particularly in non-sequenced species. One of the objective of the thesis was to use the qPCR approach for the evaluation of the gene expression perturbation by ENM. This work allowed to determine the fate and the behavior of ENM in the different exposure conditions. The evaluation of ENM effects has been done at different biological scales (molecular, cellular, individual). The use of multivariate statistical tools has been particularly useful for the analysis of the expression variations of the targeted genes. The multi-marker approach at different biological scales allowed the integration of a lot of data, which generally allowed us to differentiate the effects of the different forms of ENM
Book chapters on the topic "Cerium dioxide (CeO2)"
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Wang, Qun, Linyan Ye, Yi Yang, Xinglin Lv, and Jinfeng Lu. "Catalytic Ozonation of PA in Water in the Presence of Cerium Dioxide (CeO2)." In Advances in Intelligent and Soft Computing, 169–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29455-6_25.
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Grygorova, G., V. Klochkov, Ye Mamotyuk, and Yu Malyukin. "Cerium Dioxide CeO2-x and Orthovanadate (Gd0.9Eu0.1VO4) Nanoparticles for Protection of Living Body from X-Ray Induced Damage." In Nanomaterials for Security, 289–96. Dordrecht: Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-017-7593-9_23.
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Nawaz, Saba, Iqra Maqsood, Fatima Batool, Zainab Y. Sandhu, Sameera Hassan, Faheem Akram, and Bushra Rashid. "Improvement of Abiotic Stress Tolerance in Plants with the Application of Nanoparticles." In Abiotic Stress in Plants - Adaptations to Climate Change [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.110201.
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Plants are under the threat of climatic changes and there is a reduction in productivity and deterioration in quality. The application of nanoparticles is one of the recent approaches to improve plant yield and quality traits. A number of nanoparticles, such as zinc nanoparticles (ZnO NPs), iron nanoparticles (Fe2O3 NPs), silicon nanoparticles (SiO2 NPs), cerium nanoparticles (CeO2 NPs), silver nanoparticles (Ag NPs), titanium dioxide nanoparticles (TiO2 NPs), and carbon nanoparticles (C NPs), have been reported in different plant species to play a role to improve the plant physiology and metabolic pathways under environmental stresses. Crop plants readily absorb the nanoparticles through the cellular machinery of different tissues and organs to take part in metabolic and growth processes. Nanoparticles promote the activity of a range of antioxidant enzymes, including catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), in plant species, which in turn improve the growth and development under stressful conditions. The present review focuses on the mode of action and signaling of nanoparticles to the plant systems and their positive impact on growth, development, and ROS scavenging potential. The appropriate elucidation on mechanisms of nanoparticles in plants leads to better growth and yields under stress conditions, which will ultimately lead to increased agricultural production.
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Aneggi, Eleonora, Carla de Leitenburg, Marta Boaro, Paolo Fornasiero, and Alessandro Trovarelli. "Catalytic applications of cerium dioxide." In Cerium Oxide (CeO₂): Synthesis, Properties and Applications, 45–108. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-815661-2.00003-7.
Full textConference papers on the topic "Cerium dioxide (CeO2)"
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Krenzke, Peter, and Jane Davidson. "Thermodynamic Analysis of the Ceria Redox Cycle With Methane-Driven Reduction for Solar Fuel Production." In ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/es2014-6332.
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The nonstoichiometric cerium oxide (ceria) redox cycle is an attractive pathway for storing energy from concentrated sunlight in chemical bonds by splitting water and carbon dioxide. The endothermic reduction reaction (R1)CeO2-δox→CeO2-δed+Δδ2O2 is favored thermodynamically at high temperatures and low oxygen partial pressures, while the CO2 and H2O splitting reactions (R2, R3) are exothermic and favored at lower temperatures and higher oxygen partial pressures. The produced hydrogen and carbon monoxide, referred to collectively as syngas, are important feedstocks used in the synthesis of ammonia and liquid fuels.(R2)CeO2-δed+ΔδCO2→CeO2-δox+ΔδCO (R3)CeO2-δed+ΔδH2O→CeO2-δox+ΔδH2
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Kim, H. K., H. S. Choi, and C. H. Lee. "Failure Analysis of Plasma Sprayed ZrO2-CeO2-Y2O3 Thermal Barrier Coatings." In ITSC 1999, edited by E. Lugscheider and P. A. Kammer. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 1999. http://dx.doi.org/10.31399/asm.cp.itsc1999p0740.
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Abstract This paper aims to clarify the thermal and mechanical properties of zirconium dioxide-cerium(IV) oxide-yttrium oxide and zirconium dioxide-yttrium oxide plasma sprayed coatings. such as phase transformation, bond coat oxidation, and thermal expansion mismatch. Both coatings showed a 7 to 11% porosity fraction and typical lamellar structure, which formed due to continuous wetting by liquid droplets. It is observed that the zirconium dioxide-cerium(IV) oxide-yttrium oxide coating turned out to be better than the zirconium dioxide-yttrium oxide because there was no phase change from the tetragonal to the monoclinic phase (which leads to a spatial expansion), because there was a smaller thermal expansion offset and the effect of the oxide growth stress the better thermal insulation was relatively small. Paper includes a German-language abstract.
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Foral, Štěpán, David Salamon, Karel Katovský, Jan Varmuža, and Jakub Roleček. "Influence of Silicone Carbide on the Reactivity of Nuclear Fuels Using Cerium Dioxide as a Surrogate Material." In 2014 22nd International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icone22-31262.
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The most researched material in nuclear power industry is uranium dioxide however due to strict safety and sanitary restrictions this material can be researched only in specialized research institutes and universities which have sufficient technological background. For this reason it can be suitable to find material which would show physical properties similar to UO2 but would not suffer by the strict limitations in storage and handling. In this case much more workplaces could be incorporated in the material research and the list of investigated problems could be significantly enlarged. One of the possible substitutional materials is the cerium dioxide (CeO2) which shows similar chemical and physical properties like UO2 and in some cases shows also similar neutronic properties. The laboratory research was focused on comparing of the basic neutronic properties. For the comparison of nuclear properties the JANIS software [1] was used as it contains cross section libraries of both materials. It will be shown that similarity of both materials is significant and in several cases application of cerium dioxide as alternative material is possible with sufficient accuracy. As an example of the use of CeO2, research of influence of the SiC content on the reactivity of nuclear fuels is presented in this work.
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Vitorović-Todorović, Maja, Tamara Vujatović-Velimirov, Stevan Stupar, and Danica Bajić. "The design and preparation of cerium-dioxide and zirconium(IV)hydroxide-incorporated nanofibers for the degradation of chemical warfare agents." In 11th International Scientific Conference on Defensive Technologies - OTEX 2024, 463–68. Military Technical Institute, Belgrade, 2024. http://dx.doi.org/10.5937/oteh24083v.
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Specifically designed nanofibers enriched with chemically active nanoparticles, capable of destruction of chemical warfare agents (CWA's) and other toxic chemicals are highly desirable for the incorporation in personal protective equipment and decontamination items. In this work, we prepared six types of nanofibrous materials, based on the two types of polymers, polyvinylchloride (PVC) and polyvinylbutyral (PVB). As carriers of active chemistry, nanoparticles of cerium-dioxide (CeO2) and zirconium(IV)hydroxide (Zr(OH)4) were used. The morphology of the samples obtained and their qualitative chemical composition was investigated by scanning electron microscopy (SEM). The degradation ability of the nanofibrous mats was firstly investigated in an aqueous environment, over wide range of buffered pH conditions, using spectrophotometric method and paraoxon-ethyl as a model compound. A rather slow, but significant degradation of paraoxon-ethyl was observed on nanofibers which contained CeO2 nanoparticles in neutral conditions. The sulphur mustard (HD) adsorption was investigated in non-aqueous environment using GC-MS method. The samples made of PVC exerted strong adsorption of HD with almost six fold reduction in HD concentration but without any degradation of the test compound. In conclusion, nanofibers obtained showed strong adsorption ability in non-polar solvents, but further modification of CeO2 and Zr(OH)4 nanoparticles are necessary to enhance their CWA degradation ability.
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Wang, Qun, Xuedong Zhai, Jun Ma, and Yi Yang. "Catalytic Ozonation of MTBE in Water in the Presence of Iron Hydroxide (FeOOH) and Cerium Dioxide (CeO2)." In 2010 International Conference on Challenges in Environmental Science and Computer Engineering (CESCE 2010). IEEE, 2010. http://dx.doi.org/10.1109/cesce.2010.275.
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Sharma, Subodh Kumar, Arunesh Chandra, and K. V. Ojha. "Experimental Investigation on Emission Characteristics of Diesel-Neem Oil Biodiesel Blended with Nanoparticles in the Diesel-Powered Engine." In International Conference on Frontiers in Desalination, Energy, Environment and Material Sciences for Sustainable Development & Annual Congress of InDA. AIJR Publisher, 2023. http://dx.doi.org/10.21467/proceedings.161.20.
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In the past two decades, the global energy demand has been troubled by uncertainty in two aspects. First, the price of conventional fossil fuels is very expensive, putting a further burden on the economies of importing countries. Second, the primary contributor to the increase in atmospheric carbon dioxide (CO2) as a result of global warming is the burning of fossil fuels. So, we must introduce an alternate fuel that reduces the burden on the economies of importing countries and reduces the emission of harmful gases which cause global warming. Biodiesel is the best alternative to conventional diesel fuel which are both environmentally and economically friendly. For using biodiesel directly into the engine, there is no need for engine modification. Its main benefits include excellent lubricity, high biodegradability, and a lack of sulphur content. In the new era, not only biodiesel but also nanoparticles are widely employed by using their blends to decrease the emission of harmful gases and particles (like unburned hydrocarbons, nitrogen oxides, carbon dioxide, smoke, and many more) into the environment. The emission properties of three fuel series - pure diesel, biodiesel-diesel-TiO2 nanoparticles, and biodiesel-diesel-CeO2 nanoparticles - are examined in this experimental study. The titanium oxide (TiO2) and cerium oxide (CeO2) nanoparticles employed in this experimental inquiry were mixed with the fuel blends using an ultrasonicator at concentrations of 50 ppm, 100 ppm, and 150 ppm, respectively. By using biodiesel-diesel blends with nanoparticles as a fuel in the compression ignition engine, the diesel engine emits less pollutants.
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Siegel, Nathan P., Stephanie Livers, James E. Miller, and Richard B. Diver. "Cerium Oxide Materials for the Solar Thermochemical Decomposition of Carbon Dioxide." In ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90091.
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We have experimentally investigated the thermochemical decomposition of carbon dioxide using pure cerium oxide fibrous structures. Experiments were conducted on-sun with a solar furnace and include two reaction steps: the thermal reduction of CeOα to CeOβ between 1500°C and 1600°C, and the re-oxidation of CeOβ to produce carbon monoxide under flowing carbon dioxide at temperatures between 800°C and 1200°C. A ceria-based cycle offers some advantages over similar thermochemical cycles including the reduction of sintering and volatility issues during thermal reduction, a stable crystal structure over the range of operating temperatures, and the ability for all of the material to participate in the thermochemical reactions, i.e. there is no inert support. We present experimental results indicating that pure ceria structures perform at a level comparable to ferrite-based structures with respect to material utilization and better than the ferrites with respect to the carbon monoxide production rate during the oxidation step. We also discuss the performance potential of a solar reactor that continuously produces carbon monoxide using ceria in a two-step thermochemical cycle.