Search results for "Mixture"
showing 10 items of 1178 documents
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.
Microstructure Characteristics of Unsaturated Compacted Scaly Clay
2012
Microstructure characteristics of unsaturated compacted scaly clay are investigated by MIP tests on freeze dried samples and observation of SEM photomicrographs. Effects of scale microstructure and increasing compaction stresses, and microstructure changes induced by loading and unloading paths and clay saturation are analysed.
Calcium silicate hydrates: Solid and liquid phase composition
2015
© 2015 Elsevier Ltd. This paper presents a review on the relationship between the composition the structure and the solution in which calcium silicate hydrate (C S H) is equilibrated. The silica chain length in C S H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space preferentially at low calcium concentrations and thus by low Ca/Si C S H. Aluminium uptake in C S H increases strongly at higher aluminium concentrations in the solution. At low Ca/Si aluminium substitutes silica in the bridging position at Ca/Si. > 1 aluminium is bound in TAH. Recently developed ther…
Accelerated Light-Induced Defect Transformation Study of Elkem Solar Grade Silicon
2012
AbstractSolar cells made of silicon feedstock from a metallurgical route must qualify not only the initial efficiency, but must also be comparable to the solar cells made from reference polysilicon on the spectral response after light induced degradation. A detailed comparative study of light induced defects and its impact on cell performance is necessary for both materials. We have studied accelerated light induced degradation (ALID) defect transformation for Elkem Solar Silicon and polysilicon solar cells by selecting wafers from different positions from respective silicon bricks. Active boron-oxygen complexes and iron ions in multicrystalline silicon solar cells have been analyzed, and t…
Natural Radioactivity in Clay Ceramics and their Raw Materials in Latvia
2018
Natural radionuclides K-40, and Th-232, U-238 (Ra-226) decay chain products contained in building materials are the main source of radiation dose received by population and the only source of indoor radiation exposure. Present work contains results of the study of natural radionuclide activity level in clay, clay ceramics and silica bricks used in Latvia. Obtained data show that radionuclide content in different clay products can differ up to five times. However, determined activity index values for all tested materials, except fireproof bricks, were below radionuclide concentration level permitted by EU and Latvian national regulations. Comparison with analogous data from other North Europ…
Modeling of the N-terminal Section and the Lumenal Loop of Trimeric Light Harvesting Complex II (LHCII) by Using EPR
2015
The major light harvesting complex II (LHCII) of green plants plays a key role in the absorption of sunlight, the regulation of photosynthesis, and in preventing photodamage by excess light. The latter two functions are thought to involve the lumenal loop and the N-terminal domain. Their structure and mobility in an aqueous environment are only partially known. Electron paramagnetic resonance (EPR) has been used to measure the structure of these hydrophilic protein domains in detergent-solubilized LHCII. A new technique is introduced to prepare LHCII trimers in which only one monomer is spin-labeled. These heterogeneous trimers allow to measure intra-molecular distances within one LHCII mon…