University of Patras

About: University of Patras is a education organization based out in Pátrai, Greece. It is known for research contribution in the topics: Population & Catalysis. The organization has 13372 authors who have published 31263 publications receiving 677159 citations. The organization is also known as: Panepistímio Patrón.

Subjecting a graphene monolayer to tension and compression

Abstract: The mechanical behaviour of graphene flakes under both tension and compression is examined using a cantilever-beam arrangement. Two different sets of samples were employed involving flakes just supported on a plastic bar but also embedded within the plastic substrate. By monitoring the shift of the 2D Raman line with strain, information on the stress transfer efficiency as a function of stress sign and monolayer support were obtained. In tension, the embedded flake seems to sustain strains up to 1.3%, whereas in compression there is an indication of flake buckling at about 0.7% strain. The retainment of such a high critical buckling strain confirms the relative high flexural rigidity of the embedded monolayer.

Modeling complex systems using fuzzy cognitive maps

Abstract: This research deals with the soft computing methodology of fuzzy cognitive map (FCM). Here a mathematical description of FCM is presented and a new methodology based on fuzzy logic techniques for developing the FCM is examined. The capability and usefulness of FCM in modeling complex systems and the application of FCM to modeling and describing the behavior of a heat exchanger system is presented. The applicability of FCM to model the supervisor of complex systems is discussed and the FCM-supervisor for evaluating the performance of a system is constructed; simulation results are presented and discussed.

Influence of the preparation method on the performance of CuO–CeO2 catalysts for the selective oxidation of CO

Abstract: In this work we report on the influence of the preparation method on the physicochemical and catalytic properties of CuO–CeO2 catalysts for the selective CO oxidation in simulated reformate gas. Four CuO–CeO2 samples were prepared using the co-precipitation, the citrate-hydrothermal, the urea-nitrates combustion, and the impregnation methods, and characterized by N2 adsorption–desorption, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction by H2 (TPR-H2). The combustion-prepared sample exhibited the best catalytic performance, closely followed by that prepared with the citrate-hydrothermal method. The co-precipitated sample was less active followed by the impregnated one. The activity of all samples decreases in the presence of CO2 and, to a higher degree, in the simultaneous presence of both CO2 and H2O in the feed. The resistance to this deactivation was higher in the case of the sample prepared by the urea-nitrates combustion method, which remained the most active and selective, closely followed by the specimen prepared by the citrate-hydrothermal method. The superior catalytic performance of the samples prepared by the urea-nitrates combustion and the citrate-hydrothermal methods is attributed to the existence of well dispersed, strongly interacting with the ceria surface, copper oxide species.