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排序方式: 共有147条查询结果,搜索用时 31 毫秒
91.
Sebastian Kunze Liviu C. Tnase Mauricio J. Prieto Philipp Grosse Fabian Scholten Lucas de Souza Caldas Dennis van Vrden Thomas Schmidt Beatriz Roldan Cuenya 《Chemical science》2021,12(42):14241
Oxidized copper surfaces have attracted significant attention in recent years due to their unique catalytic properties, including their enhanced hydrocarbon selectivity during the electrochemical reduction of CO2. Although oxygen plasma has been used to create highly active copper oxide electrodes for CO2RR, how such treatment alters the copper surface is still poorly understood. Here, we study the oxidation of Cu(100) and Cu(111) surfaces by sequential exposure to a low-pressure oxygen plasma at room temperature. We used scanning tunnelling microscopy (STM), low energy electron microscopy (LEEM), X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption fine structure spectroscopy (NEXAFS) and low energy electron diffraction (LEED) for the comprehensive characterization of the resulting oxide films. O2-plasma exposure initially induces the growth of 3-dimensional oxide islands surrounded by an O-covered Cu surface. With ongoing plasma exposure, the islands coalesce and form a closed oxide film. Utilizing spectroscopy, we traced the evolution of metallic Cu, Cu2O and CuO species upon oxygen plasma exposure and found a dependence of the surface structure and chemical state on the substrate''s orientation. On Cu(100) the oxide islands grow with a lower rate than on the (111) surface. Furthermore, while on Cu(100) only Cu2O is formed during the initial growth phase, both Cu2O and CuO species are simultaneously generated on Cu(111). Finally, prolonged oxygen plasma exposure results in a sandwiched film structure with CuO at the surface and Cu2O at the interface to the metallic support. A stable CuO(111) surface orientation is identified in both cases, aligned to the Cu(111) support, but with two coexisting rotational domains on Cu(100). These findings illustrate the possibility of tailoring the oxidation state, structure and morphology of metallic surfaces for a wide range of applications through oxygen plasma treatments.A low-pressure oxygen plasma oxidized Cu(100) and Cu(111) surfaces at room temperature. The time-dependent evolution of surface structure and chemical composition is reported in detail for a range of exposure times up to 30 min. 相似文献
92.
Gonçalves Daniel Bozzi Barbeiro Lilian Tonon de Souza Patrícia Caldas Batista Eduardo Augusto de Almeida Meirelles Antonio José 《Journal of Thermal Analysis and Calorimetry》2022,147(21):11857-11874
Journal of Thermal Analysis and Calorimetry - Glycerol is a by-product from transesterification for biodiesel production. Due to the presence of hydroxyl groups (–OH), glycerol is pointed as... 相似文献
93.
To an inverse semigroup, we associate an étale groupoid such that its actions on topological spaces are equivalent to actions of the inverse semigroup. Both the object and the arrow space of this groupoid are non-Hausdorff. We show that this construction provides an adjoint functor to the functor that maps a groupoid to its inverse semigroup of bisections, where we turn étale groupoids into a category using algebraic morphisms. We also discuss how to recover a groupoid from this inverse semigroup. 相似文献
94.
Alcides Lins Neto 《Bulletin of the Brazilian Mathematical Society》2012,43(1):129-169
The Baum-Bott map associates to a foliation the Baum-Bott indexes of their singularities. In this paper we study the fibers
of the Baum-Bott map in the space of foliations of degree two on the projective plane ℙ2. In the main result we prove that its generic fiber contains exactly 240 orbits of the natural action of Aut(ℙ2) onthespace of foliations. 相似文献
95.
GR de Morais Lima IR de Sales MR Caldas Filho NZ de Jesus H de Sousa Falcão JM Barbosa-Filho AG Cabral AL Souto JF Tavares LM Batista 《Molecules (Basel, Switzerland)》2012,17(8):9142-9206
The Combretaceae is a large family of herbs, shrubs and trees, comprising about 20 genera and 600 species with tropical distribution around the globe and centers of diversity in Africa and Asia. Some Combretum species are extensively used in traditional medicine against inflammation, infections, diabetes, malaria, bleeding, diarrhea and digestive disorders and others as a diuretic. The present work is a literature survey of Combretum species that have been evaluated for their ability to exert biological activities. A total number of 36 Combretum species are discussed with regard to plant parts used, component tested and bioassay models. This review is of fundamental importance to promoting studies on Combretum species, thereby contributing to the development of new therapeutic alternatives that may improve the health of people suffering from various health problems. 相似文献
96.
R.L. Viana S.R. Lopes I.L. Caldas J.D. Szezech Z. Guimarães-Filho G.Z. dos Santos Lima P.P. Galuzio A.M. Batista Yu. Kuznetsov I.C. Nascimento 《Communications in Nonlinear Science & Numerical Simulation》2012,17(12):4690-4699
Turbulence is one of the key problems of classical physics, and it has been the object of intense research in the last decades in a large spectrum of problems involving fluids, plasmas, and waves. In order to review some advances in theoretical and experimental investigations on turbulence a mini-symposium on this subject was organized in the Dynamics Days South America 2010 Conference. The main goal of this mini-symposium was to present recent developments in both fundamental aspects and dynamical analysis of turbulence in nonlinear waves and fusion plasmas. In this paper we present a summary of the works presented at this mini-symposium. Among the questions to be addressed were the onset and control of turbulence and spatio-temporal chaos. 相似文献
97.
98.
We introduce and study two new weak separation axioms called ΛΘ-R 0 and ΛΘ-R 1 by using the notions of (Λ,Θ)-open sets and (Λ,Θ)-closure operators. 相似文献
99.
C. Silva João M. P. Coelho P. Caldas O. Frazão P. A. S. Jorge J. L. Santos 《Fiber and Integrated Optics》2013,32(3):160-169
Abstract In the field of aqueous environment studies, long-period fiber gratings are very attractive for the real-time monitoring of physical parameters, such as temperature and salinity. However, due to the fiber jacket removal, these are fragile devices when applied in real conditions, where mechanical loads and contamination with algae and other organic materials must be taken into account. This work describes a refractive index sensing head that has been developed and characterized for in situ measurement of water salinity and resistance to hard conditions. 相似文献
100.
C. S. Q. De Caldas J. Límaco R. K. Barreto 《Mathematical Methods in the Applied Sciences》2008,31(3):339-361
In this article, we present results concerning with the existence of global solutions and a rate decay estimate for energy associated with an initial and boundary value problem for a beam evolution equation with variable coefficients in non‐cylindrical domains. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献