We establish a criterion for the existence of an invariant measure for Markov processes acting on measures defined on an arbitrary complete separable metric space. This criterion is applied to time-homogeneous Markov processes associated with a nonlinear heat equation driven by an impulsive noise. 相似文献
We report the preliminary results on simple one‐step chemical synthesis of exfoliated graphite and other carbon‐related nanostructures via a novel combustion synthesis route. We found previously that different solid carbonates could be decomposed to elements upon reducing in solid phase by using a strong reducers and the produced carbon vapors instantly condense towards 1‐D nanocarbons. Here such combustion processing is extended towards the direct heterogeneous, efficient, and autothermic high‐pressure reduction of gaseous carbon oxides (CO2 and CO) to elements using the following reducers: Li, Mg, Ca, B, Ti, Zr, and Al. The solid products (layered graphite and nanocarbides) were chemically purified and characterized using XRD, SEM, and Raman spectroscopy.
The catalytic activity in the formic acid (HCOOH) electrooxidation reaction of the Pd multiwall carbon nanotubes (MWCNTs) supported catalyst, prepared by a microwave‐assisted polyol method, treated under different gas atmospheres, and temperatures (200 and 300 °C), was investigated. Their respective catalysts surface characterization proceeded in UHV using the electron spectroscopy methods. Content of constituents, i.e., Pd nanoparticles, C and O, was examined quantitatively. Content of Pd phases and chemical forms of C atoms was analyzed assuming respective binding energy (BE) values to Pd 3d and C 1s X‐ray photoelectron spectra (XPS) spectra fitted to Gaussian–Lorentzian components. Surface structure was examined from the 3D nanostructure analysis by quantitative analysis of surfaces by electron spectroscopy (QUASES). Catalytic activity of Pd/MWCNTs after various surface treatments was attributed to different surface content and forms of Pd nanoparticles, and PdOx/C overlayer morphology, coverage, and thickness. 相似文献
It is known that palladium‐based catalysts are initially very active in direct formic acid oxidation but they suffer from fast deactivation caused by a strongly adsorbed CO intermediate. Reactivation of the catalysts involving application of anodic potential may cause palladium dissolution. The aim of the present study is to increase the stability and performance of palladium‐based catalysts in direct formic acid fuel cells (DFAFCs). Preparation and characterization of palladium/multiwalled carbon nanotubes (Pd/MWCNTs) and towards formic acid oxidation via different treatments are described. The catalysts were characterized by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry (CV). It was shown that the Pd and Pd–Au MWCNTs supported catalysts after reduction in H2–Ar at 200 °C (R200 treatment) were highly active in formic acid electro‐oxidation, whereas the catalysts after heating in argon at 250 °C (C250 treatment) were inactive. The catalysts after hydrogen treatment have smaller metal particles and better contact with MWCNTs support. CV, simulating reactivation of the catalysts, showed that the Pd catalyst suffers from severe Pd dissolution, whereas for the Pd–Au selective leaching of Pd is considerably slower. 相似文献
In this paper, a vertical distribution of 137Cs in agricultural soil was investigated. 137Cs is an anthropogenic radioisotope which is strongly adsorbed in soil and can be used to study soil erosion. This paper presents some preliminary results of measurements of activity of 137Cs in soil in Bia?a and Odonów areas. In both areas, the upper part of the soil profile was cultivated. The experimental results show that the vertical distribution of 137Cs in agricultural soil is different from the vertical distribution of 137Cs in undisturbed soil. The 137Cs is more uniformly distributed in the cultivated soil layer than in an undisturbed site. Migration of 137Cs below plough depth is limited. These data show that the depth distribution of 137Cs in soil profiles for cultivated fields should be considered for precise determination of soil erosion. 相似文献
