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Reflectometry is known since long as an interferometric method which can be used to characterize surfaces and thin films regarding their structure and,to a certain degree,composition as well.Properties like layer structures,layer thickness,density,and interface roughness can be determined by fitting the obtained reflectivity data with an appropriate model using a recursive fitting routine. However,one major drawback of the reflectometric method is its restriction to planar surfaces.In this article we demonstrate an approach to apply X-ray and neutron reflectometry to curved surfaces by means of the example of bent bare and coated glass slides.We prove the possibility to observe all features like Fresnel decay,Kiessig fringes,Bragg peaks and off-specular scattering and are able to interpret the data using common fitting software and to derive quantitative results about roughness,layer thickness and internal structure. The proposed method has become practical due to the availability of high quality 2D-detectors. It opens up the option to explore many kinds and shapes of samples,which,due to their geometry,have not been in the focus of reflectometry techniques until now.
Foam has been employed as an improved or enhanced oil recovery method to overcome gravity override and the channeling and fingering of the injected gas, which arises because of the low density and viscosity of the injected fluid combined with the rock heterogeneity. A major challenge, however, is the stability of the generated foam when it contacts the oil. In this study we investigate the feasibility of using inexpensive nanoparticles made of coal fly ash, an abundantly available waste product of coal power plants, as a foam booster. We investigate the viability of reducing the size of fly ash particles to 100−200 nm using high-frequency ultrasonic grinding. We also study the foaminess (foamability), strength, and stability of the foams made with minor concentrations of fly ash nanoparticles and surfactant, both in bulk and porous media. The effect of monovalent and divalent ion concentration on the foaminess of the nanoash suspension combined with very low concentrations of a commercial alpha olefin sulfonate (AOS) surfactant, in the presence and absence of oil, is studied. We observe that bulk foam that contains very small amounts of nanoash particles shows a higher stability in the presence of model oils. Furthermore, experiments in porous media exhibit remarkably stronger foam with mixtures of nanoash and surfactant, such that the amount of produced liquids from the cores significantly increases. For the first time we show that nanoash can be used to stabilize nitrogen foam in the presence of crude oil at high temperature and pressure. In the presence of oil, the nanoash−AOS foam shows a higher stability, although crude oil tends to form stable emulsions in water in the presence of nanoash.