Cu supported on Al2O3, prepared by impregnation, was thermally aged at different temperatures, and the influence of thermal aging on the local structure, redox behavior of Cu, and catalytic activity for a stoichiometric NO–CO–C3H6–O2 reaction was investigated. Crystalline CuO was mainly formed on Al2O3 after thermal aging at ≤700 °C, whereas aging at higher temperatures induced Cu2+ incorporation into tetrahedral (Td-Cu2+) rather than octahedral (Oh-Cu2+) sites of γ-Al2O3. Despite its lower surface area, thermally aged Cu/Al2O3 with Td-Cu2+ sites showed higher catalytic performance for the stoichiometric NO–CO–C3H6–O2 reaction compared with the as-prepared catalyst, especially for NO reduction. Td-Cu2+ was reduced to Td-Cu+ during reaction with CO and/or C3H6, and NO could be reduced in subsequent reoxidation of Td-Cu+ to Td-Cu2+ by NO. This redox behavior is more probable on Td-Cu rather than crystalline CuO, resulting in enhancement of NO reduction during the three-way catalyst reaction.

The effects of the Cr/Cu ratios of Cr−Cu-embedded CeO 2 surfaces (0.065 wt % Cu loading) on their local structures and catalytic activities were studied using experimental and theoretical approaches. The sample with a weight ratio of Cr/Cu = 1, which was prepared by wet impregnation followed by subsequent thermal aging at 900 °C for 25 h, showed catalytic activity higher than that of the Cu/CeO 2 sample in both CO−O 2 and CO−NO reactions. The activity of the catalyst was enhanced by increasing the Cr/Cu ratio. The highest activity occurred for a Cr/Cu ratio of around 3, and after it had been thermally aged, its activity was superior to that of Rh/CeO 2 . Having more Cr than Cu increases the surface concentration of the Cu + sites, which promotes CO adsorption and its reaction with surface O atoms. As-formed surface O vacancies are filled by the dissociative adsorption of O 2 and/or NO. At the optimum composition, almost all of the Ce sites on the outermost layer are replaced by Cr and Cu, and oxidative chemisorption of CO and NO as carbonate and nitrate/nitrite, respectively, on the CeO 2 surface becomes difficult. This situation enables more efficient dissociation of adsorbed NO and faster desorption of CO 2 , thereby leading to higher catalytic activity. Isocyanate species (NCO) that form on the Cu + sites are a possible reaction intermediate for the CO−NO reaction.

This study aims to clarify the effect of Ni addition on the enhancement of the NO reduction activity of Cu/Al2O3, which possesses high thermal durability, and to elucidate the associated structure–catalysis relationship. Thermal aging of Ni and Cu supported on γ-Al2O3 at a high temperature (900 °C) induced the formation of a pseudo-spinel (NiCu)­Al2O4 solid solution on the γ-Al2O3 surface, which was observed using X-ray diffraction and high-angle annular dark-field scanning transmission electron microscopy techniques. Owing to the co-presence of Ni, the preferential occupation of octahedral sites by Ni increased the number of tetrahedrally coordinated Cu2+ ions, which played a key role in the reduction of NO in a stoichiometric NO–CO–C3H6–O2 reaction. XPS analysis revealed that Cu active sites with electron-rich states were formed in pseudo-spinel (NiCu)­Al2O4 owing to electron donation from Ni to Cu, which promoted NO adsorption on Cu+ and accelerated NO reduction. The tetrahedrally coordinated Cu formed on the pseudo-spinel oxide was structurally robust, and its local structure remained unchanged even after the redox cycle occurred at a high temperature; this indicated that the formation of pseudo-spinel (NiCu)­Al2O4 was effective for the enhancement of NO reduction activity and thermal durability.

<b><i>Introduction:</i></b> Aspiration pneumonia, an important issue for the older adults, is caused by an increase in pathogenic microorganisms in the saliva, aspiration, and weakened host immunity. Recently, decreased tongue pressure has been reported to be associated with dysphagia. This study aimed to investigate the relationship between decreased tongue pressure and the number of bacteria in the saliva of the older adults requiring long-term care. <b><i>Methods:</i></b> This cross-sectional study involved 95 older adults requiring long-term care in a facility or at home, eating orally, and who could understand the instructions for measuring tongue pressure. Sex, age, slowness, weakness, shrinking, exhaustion, low activity, number of teeth, functional teeth unit, denture use, oral hygiene, tongue coating index, dry mouth, tongue pressure, and number of bacteria in the saliva were examined. Bacterial counts were analyzed by real-time PCR for total bacteria, total streptococci, methicillin-resistant <i>Staphylococcus aureus</i>, <i>Streptococcus pneumoniae</i>, <i>Pseudomonas aeruginosa</i>, <i>Porphyromonas gingivalis</i>, and <i>Candida albicans</i>. <b><i>Results:</i></b> Multiple regression analysis showed that poor oral hygiene and decreased tongue pressure were independent risk factors for increased bacteria in the saliva. Decreased tongue pressure is significantly correlated with an increased number of total bacteria and the presence of <i>P. gingivalis</i>. <b><i>Discussion/Conclusion:</i></b> Our results suggest that tongue pressure not only maintains the swallowing function but also prevents the increase of bacteria in the saliva of older adults requiring long-term care.