Search results for "Mixtures"
showing 10 items of 913 documents
Characterization of gas flow through low-permeability claystone: laboratory experiments and two-phase flow analyses
2014
For the characterization of gas migration through a low-permeability clay host rock for deep underground repositories, a comprehensive understanding of the relevant phenomena of gas and fluid flow through low-permeability clay is required. The National Cooperative for the Disposal of Radioactive Waste (Nagra) in Switzerland has developed a comprehensive programme to characterize gas flow in low-permeability Opalinus Clay through laboratory tests and detailed numerical analyses for developing appropriate constitutive models. Laboratory tests were performed on cores by two different laboratories, the Laboratory for Soil Mechanics at EPFL and the Department of Geotechnical Engineering and Geos…
Exposure to nitrogen dioxide and respiratory health at 2 years in the INMA-Valencia cohort
2018
Resumen Objetivo Analizar la relación entre la exposición a dióxido de nitrógeno (NO2) en las etapas prenatal y posnatal y la incidencia de problemas respiratorios en niños/as hasta los 2 años de edad. Método La población consistió en 624 niños/as de la cohorte INMA-Valencia. Se estimó la exposición individual al NO2 en el exterior de la vivienda durante el periodo prenatal y hasta los 2 años de edad, a partir de la combinación de datos empíricos y el desarrollo de métodos geoestadísticos. Se aplicó un cuestionario para obtener la información sobre los síntomas respiratorios a los 2 años. La asociación entre la exposición al NO2 y los eventos respiratorios se realizó mediante regresión logí…
A Study on Acidification and Intercalation of Illite Clay Minerals and their Potential Use as a Filler in SPEEK Composite Membranes
2018
The acidification and intercalation of illite containing clays were studied for potential use as fillers for sulphonated poly (ether ether ketone) (SPEEK) composite membrane preparation and future proton exchange membrane fuel cells application. The acidification and dimethyl sulfoxide (DMSO) intercalation of illite clays have been studied by powder X-ray diffractometry, X-ray fluorescence spectrometry, and thermogravimetric analysis. SPEEK composite membranes were made with 1, 3 and 5% purified, acidified, DMSO intercalated clay fillers. SPEEK/clay composite membranes were characterized by proton conductivity, water uptake, and mechanical strength.
A new simple chromo-fluorogenic probe for NO2 detection in air.
2015
[EN] A new chromo-fluorogenic probe, consisting of a biphenyl derivative containing both a silylbenzyl ether and a N,N-dimethylamino group, for NO2 detection in the gas phase has been developed. A clear colour change from colourless to yellow together with an emission quenching was observed when the probe reacted with NO2. A limit of detection to the naked eye of about 0.1 ppm was determined and the system was successfully applied to the detection of NO2 in realistic atmospheric conditions.
The impact of a disused mine on uranium transport in the River Fal, South West England.
2004
Unfiltered and filtered (0.45 and 0.2 microm) water samples and sediment samples (sieved to180 microm and 180-1000 microm) were collected along an approximately 15 km transect of the River Fal, Cornwall, UK, to examine the impact of the disused South Terras uranium mine on the uranium concentrations of the river water and underlying sediments. The uranium concentration of the water samples fluctuated along the river, with the 0.45 microm filtered water showing the largest, seven-fold, difference between minimum (0.19 microg L(-1)) and maximum (1.34 microg L(-1)) concentrations. The historical uranium mine and spoil heaps were not a significant source of uranium to the river water, as water …
Micro-scale post-fire surface cover changes monitored using high spatial resolution photography in a semiarid environment: A useful tool in the study…
2012
[ES] Although post-fire soil erosion has been studied, little attention has been paid to changes in soil surface cover following fires, despite this being a key factor in understanding the water and sediment yield. This study, at Peñaflor (Spain), investigated the effect of fire on soil erosion using data from soil erosion plots and high spatial resolution photography (HSRP). Measurements were made from October 2003 to October 2005 in a control plot and a plot experimentally exposed to a fire in October 2004. Ground cover components were identified, including vegetation, bare soil, stones, charcoal and ash. Runoff and sediment concentrations were low because of the absence of intense rainfa…
Modelling the Impacts of Wildfire on Ash Thickness in a Short‐Term Period
2013
Ash can provide valuable soil protection. However, ash is also very mobile, and soil protection patterns can be quickly changed, favouring the protection of some areas and exposing others with implications for soil erosion. In this research, the effects of a high severity wildfire on ash thickness were studied, 1 and 15 days after the fire. For this evaluation, several interpolation methods were tested to identify the best spatial predictor of ash distribution. The results showed that 1 day after the fire, ash was thinner in high severity areas. Fifteen days after the fire, ash thickness decreased, and the spatial pattern changed. This implies that evaluation of fire severity based on ash t…
Comparison of Structure and Properties of Differently Treated Illite Clay and Products
2014
The investigation is focused on modification of the structure 2:1 sheet silicates - illite clay by subjecting them to chemical and microbiological impact. It is shown that alkaline activation of illite clay by sodium hydroxide leads to the slight structural changes mainly characterized by water link changes. The effect of bacteria Ps. fluorescens AM PS11on structure changes of illite is small and is influenced on rheology of treated clay.It is shown that the influence of chemical treatment on porosity, bulk density and increase of compressive strength of sintered ceramic samples is notable.
Comparative study of initial stages of copper immersion deposition on bulk and porous silicon
2013
Initial stages of Cu immersion deposition in the presence of hydrofluoric acid on bulk and porous silicon were studied. Cu was found to deposit both on bulk and porous silicon as a layer of nanoparticles which grew according to the Volmer-Weber mechanism. It was revealed that at the initial stages of immersion deposition, Cu nanoparticles consisted of crystals with a maximum size of 10 nm and inherited the orientation of the original silicon substrate. Deposited Cu nanoparticles were found to be partially oxidized to Cu2O while CuO was not detected for all samples. In contrast to porous silicon, the crystal orientation of the original silicon substrate significantly affected the sizes, dens…
Covalently modified nanoclays: synthesis, properties and applications
2020
Abstract Clay minerals are phyllosilicates of nanoscale dimensions. According to their ability to entrap and release organic moieties, they have found applications in several fields, such as drug carrier and delivery, support for catalyst, environmental remediation and filler for polymeric matrices. The possibility to modify, by covalent linkage, their surfaces gives the possibility to form new nanomaterials with improved properties respect to the pristine clay minerals. In this chapter, the modifications of the siloxane surfaces of the most representative clay minerals, namely montmorillonite, sepiolites, laponite and halloysite were reviewed and discussed.