The relationship existing between aging conditions, redox behavior, and surface/bulk structural properties of two thermally aged ceria-zirconia mixed oxides, CZ-MO and CZ-SO, is analyzed. The samples were prepared by applying to a fresh Ce 0.62 Zr 0.38 O 2 mixed oxide two alternative aging routines consisting of a reduction with H 2 at 1223 K (5 h), followed by either a mild, CZ-MO, or severe, CZ-SO, re-oxidation treatment. By combining high-resolution electron microscopy and a number of chemical charcterization techniques, it is shown that the nanostructure of the aged oxides, specifically the total amount and surface presence of the phase exhibiting an ordered cationic sublattice (κ-like phase), is a key factor in determining their redox response. In the low-temperature reduction range (T redn e 773 K), the enhanced reducibility of the CZ-MO sample is proposed to be kinetically controlled by its surface structure mainly consisting of the κ-like phase. In accordance with the reported results, the surface activation of the H 2 molecule, much faster on the CZ-MO sample, is proposed to be the rate controlling step of the overall reduction process. This proposal was further confirmed by the dramatic downward shift observed in the temperatureprogrammed reduction diagrams recorded for the corresponding oxide-supported rhodium samples. By contrast, in the high-temperature reduction range (T redn g 973 K), the observed difference of reducibility, higher in the case of the CZ-MO sample, is interpreted as due to thermodynamic factors related to the nature of the predominant cationic sublattice structure, ordered for CZ-MO and disordered in the case of the CZ-SO sample.

Background Few studies have examined nano-sized plastic particulates (NPs) exposure in relation to oxidative stress and biochemical responses in rodents, commonly used for toxicity evaluations on which to base risk assessment for humans. Methods Here we explored possible oxidative stress and biochemical responses of ve weeks oral exposure to polystyrene (PS) nanoparticles (1, 3, 6 and 10 mg/kg body weight per day) in male rats. We used variance analysis and variance explained statistic eta-squared (2) to estimate the strength of relationships worked out. The whole body scanning further provided insight into the bio-distribution of nanoplastics upon oral exposure. Results Results demonstrated the accumulation of PS-NPs through whole body and also a dose-dependent increase in the production of reactive oxygen species (ROS). Signi cant alterations in antioxidant responses including serum levels of catalase, superoxide dismutase (SOD), and total glutathione content were noticed, pointing towards a perturbation of redox state induced by the exposure conditions. Acetylcholinesterase level in highest dose group was about 40 percent lower than those in control group. Biochemical parameters viz. glucose, cortisol, lipase, lactate, lactate dehydrogenase (LDH), alkaline phosphatase, gamma-glutamyl transpeptidase (GGT), triglycerides, and urea showed a signi cant increase, while total protein, albumin and globulin levels showed an appreciable decline. Conclusion The pattern of associations noticed with AChE activity and biochemical responses in our study suggests the possibility that a neurobehavioral effect or dysfunctions in energy metabolism, or both, may be the potential mode of action, possibly through stress response as well as liver function. Perturbations of creatinine and uric acid levels are indeed plausible biological explanations for the association with kidney dysfunction. Although we provided a new scienti c clue for exploring the biological effects of plastics nanoparticles, the results warrant additional research with a larger sample size. The suggested potential mechanisms also remains to be investigated. 10 5.78 c 2.8 c 2.97 c 15.25 b 21.75 d 25.75 b 205 b 510.25 d 123 c 55.13 c 162.75 b *Different letters for the signi cances demonstrate that there are signi cant differences among groups (p < 0.05).

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Nowadays, the occurrence of a large volume of plastic litter in oceanic and coastal zones has increased concern about its impacts on marine organisms. The degradation of plastic polymers leads to the formation of smaller fragments at both micro and nano scale (<5 mm and <1 µm respectively). Nanoplastics (NPs), due to their smaller size and high specific surface area can establish colloidal interactions with marine microalgae, therefore potential toxicity can be led. . To assess this hypothesis, the aim of the present study is to examine the behaviour of polystyrene nanoparticles (PS NPs) of different sizes (50 and 100 nm) in marine water and their possible effects at different physiological and cellular levels in the marine diatom Phaeodactylum tricornutum. Different biomarkers and stress responses in P. tricornutum were analysed when organisms were exposed to environmentally relevant PS NPs concentrations between 0.1-50 mg•L -1 . Our results showed significant differences between controls and exposure microalgae, indicating toxicity. After 24h, an increase in oxidative stress biomarkers, damage to the photosynthetic apparatus, DNA damage and depolarization of mitochondrial and cell membrane from 5 mg•L -1 were observed. Further after 72 h the inhibition of population growth and chlorophyll content were observed. Examining effects the effects related to PS NPs size, the smallest (50 nm) induced greater effects at 24 h while bigger PS NPs (100 nm) at72 h. This bigger particles (100nm) showed more stability (in size distribution and spherical form) in the different culture media assayed, when compared with the rest of particles used. Strong adsorption and/or internalization of PS NPs was confirmed through changes in cell complexity and cell size as well as the fluorescence of 100 nm fluoresbrite PS NPs after washing cell surface.

On the basis of detailed previous knowledge about the correlation existing between the Oxygen Storage Capacity (OSC) of ceria-zirconia mixed oxides, the nature of redox pretreatments and the nanostructure of this family of complex materials, it has been possible to design a synthetic strategy allowing one to prepare ceria-zirconia and ceria-yttria-doped zirconia materials, with total ceria contents below 20%, featuring OSC values higher than those observed for catalysts which incorporate supported noble metal particles in their formulation, especially in the very low, 373-473 K, temperature range. These novel, noble-metal free and highly reducible, ceria-zirconia materials allow a much more efficient usage of ceria as a component of oxygen storage formulations, which is nowadays considered one of the key innovation targets in the field of lanthanide oxide based catalysts.

After being heated in a flow of 5% O2/He, at 1073 or 1123 K for 30 min, a Ce0.62Zr0.38O2 sample showing an ordered cationic sublattice had very subtle surface nanostructural changes induced on it. In parallel with them, a significant loss of low-temperature (T ≤ 773 K) oxygen storage capacity (OSC), with no modification of its high-temperature (T ≥ 973 K) redox response, was observed. These nanostructural and chemical features characterize the very first stage of the process leading to the destruction of the ordered Ce−Zr sublattice, a structural phenomenon playing a key role in the control of redox behavior of ceria−zirconia mixed oxides. The reported results, including OSC, hydrogen chemisorption, and nanostructural and nanoanalytical data, lend further support to a model providing a comprehensive interpretation of the complex relationship linking thermal aging conditions, nanostructural properties, surface chemistry, and redox behavior in these materials.

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