A series of CuxCo3−xO4 catalysts were prepared and presented as active and stable catalysts in the oxidation of CO into CO2 at relatively low temperatures. These nanoparticles were synthesized by co-precipitation assisted ultrasonic radiation method. The thermal behavior, structural, spectroscopic, texture, and morphological characterizations were carried out adopting TG-DTA, XRD, XPS, FTIR, N2-sorption, and TEM techniques. In addition, electrical conductivity and surface chemisorbed oxygen measurements were also studied. The quantity and strength of basic sites were estimated using CO2-TPD. The results revealed that the insertion of Cu2+ with values of x from 0.25 to 0.75, into Co3O4 catalysts calcined at 400 °C monotonically increases the SBET, the amount of surface chemisorbed oxygen, catalyst basicity, electrical conductivity and catalytic activity. In addition, the activity increases to an optimal amount of Cu2+ substitution for Co2+ with x=0.75 which exhibited the most active catalyst with a value of T100 of 125 °C. Results of CO2-TPD demonstrated that, incorporation of Cu2+ with a value of x of 0.75 not only increases the total basicity, but also altered strength and distribution of basic sites over the surface of the catalyst. The role of the active redox sites existed on the surface of these catalysts such as, Co3+/Co2+, Cu2+/Cu+ and Co3+/Cu+, which are accountable for such alteration, was also debated. The most active catalyst Cu0.75Co2.25O4 displayed a long-term stability up to 100 h.

A series of CuxCo3−xO4 catalysts were prepared and presented as active and stable catalysts in the oxidation of CO into CO2 at relatively low temperatures. These nanoparticles were synthesized by co-precipitation assisted ultrasonic radiation method. The thermal behavior, structural, spectroscopic, texture, and morphological characterizations were carried out adopting TG-DTA, XRD, XPS, FTIR, N2-sorption, and TEM techniques. In addition, electrical conductivity and surface chemisorbed oxygen measurements were also studied. The quantity and strength of basic sites were estimated using CO2-TPD. The results revealed that the insertion of Cu2+ with values of x from 0.25 to 0.75, into Co3O4 catalysts calcined at 400 °C monotonically increases the SBET, the amount of surface chemisorbed oxygen, catalyst basicity, electrical conductivity and catalytic activity. In addition, the activity increases to an optimal amount of Cu2+ substitution for Co2+ with x=0.75 which exhibited the most active catalyst with a value of T100 of 125 °C. Results of CO2-TPD demonstrated that, incorporation of Cu2+ with a value of x of 0.75 not only increases the total basicity, but also altered strength and distribution of basic sites over the surface of the catalyst. The role of the active redox sites existed on the surface of these catalysts such as, Co3+/Co2+, Cu2+/Cu+ and Co3+/Cu+, which are accountable for such alteration, was also debated. The most active catalyst Cu0.75Co2.25O4 displayed a long-term stability up to 100 h.

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The evolution of animal behaviour is poorly understood. Despite numerous correlations between interspecific divergence in behaviour and nervous system structure and function, demonstrations of the genetic basis of these behavioural differences remain rare. Here we develop a neurogenetic model, Drosophila sechellia, a species that displays marked differences in behaviour compared to its close cousin Drosophila melanogaster, which are linked to its extreme specialization on noni fruit (Morinda citrifolia). Using calcium imaging, we identify olfactory pathways in D. sechellia that detect volatiles emitted by the noni host. Our mutational analysis indicates roles for different olfactory receptors in long- and short-range attraction to noni, and our cross-species allele-transfer experiments demonstrate that the tuning of one of these receptors is important for species-specific host-seeking. We identify the molecular determinants of this functional change, and characterize their evolutionary origin and behavioural importance. We perform circuit tracing in the D. sechellia brain, and find that receptor adaptations are accompanied by increased sensory pooling onto interneurons as well as species-specific central projection patterns. This work reveals an accumulation of molecular, physiological and anatomical traits that are linked to behavioural divergence between species, and defines a model for investigating speciation and the evolution of the nervous system.

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