Search results for "MORPHOLOGY"
showing 10 items of 1425 documents
Amendement et renouvellement des sols dans la viticulture bourguignonne aux XIVe et XVe siècles
2019
International audience
Mapping Susceptibility to Debris Flows Triggered by Tropical Storms: A Case Study of the San Vicente Volcano Area (El Salvador, CA)
2021
In this study, an inventory of storm-triggered debris flows performed in the area of the San Vicente volcano (El Salvador, CA) was used to calibrate predictive models and prepare a landslide susceptibility map. The storm event struck the area in November 2009 as the result of the simultaneous action of low-pressure system 96E and Hurricane Ida. Multivariate Adaptive Regression Splines (MARS) was employed to model the relationships between a set of environmental variables and the locations of the debris flows. Validation of the models was performed by splitting 100 random samples of event and non-event 10 m pixels into training and test subsets. The validation results revealed an excellent (…
Vorlesungen in der Miologie: gehalten in der Universität Latvia
1921
On the synonymization of Acaulon longifolium Herrnst. & Heyn with Acaulon fontiquerianum Casas & Sérgio (Pottiaceae)
2021
During bryological work conducted in the Sharon plane region (Israel), a colony of Acaulon Müll. Hal. was discovered. The plants showed morphological affinities both to A. longifolium Herrnst. & Heyn and A. fontiquerianum Casas & Sérgio depending on the floras used for their identification which challenged their recognition as separate species. In order to solve this taxonomic dilemma, we conducted a detailed morphological characterization of the two species based on representative samples. The micromorphological study of vegetative, sporophytic and spore traits revealed the large overlap of range values between both species. Both species showed the characteristic combination of morphologic…
Low-density polyethylene/polyamide/clay blend nanocomposites: Effect of morphology of clay on their photooxidation resistance
2017
The photooxidation behaviour of low-density polyethylene (LDPE)/polyamide (PA) blends, containing polyamide 11 (PA11) or polyamide 6 (PA6), has been investigated in the absence and presence of a small amount of commercial organomodified clay (OMMT). The polymer blends LDPE/PA11 and LDPE/PA6 at 75/25 wt./wt.%, with and without OMMT, have been prepared by a two-step procedure: extrusion and sheet formulation. The formulated complex systems have been subjected to accurate morphological analysis in order to evaluate the effect of the OMMT presence on the refinement of the blend morphology. Furthermore, the produced sheets have been subjected to arterial UVB exposure and the variations of the me…
Morphology of nanocomposites from ethylene-acrylic acid copolymers
2005
AbstractNew nanocomposites have been prepared by melt-compounding from commercial ethylene-acrylic acid copolymers (EAA) of different molar mass, molecular structure (branched or linear) and AA concentration, and a Zn-ionomer, with three commercial clays containing different proportions of the same organic modifier (dimethyldi(hydrogenated tallow)ammonium ion). Their morphology has been preliminarily investigated by X-ray scattering and transmission electron microscopy. The nanocomposites showed disordered intercalated morphology, with an expansion of the average gallery height, which appears to depend quite strongly on the molecular architecture of the EAA, whereas the other investigated v…
UV-stabilisation of polystyrene-based nanocomposites provided by polyhedral oligomeric silsesquioxanes (POSS)
2012
Abstract The photo-ageing behaviour of Polyhedral Oligomeric SilSequioxane (POSS)-polystyrene (PS) nanocomposites has been investigated for the first time. POSS having different inorganic framework and pendant organic groups have been used in the PS nanocomposite preparation and the formulated films were subjected to accelerated weathering. Compared to pristine PS, the POSS-containing PS developed a lower level of carbonyl and hydroxyl groups as a function of the exposure time, indicating a significantly improved resistance of the nanocomposites to photo-degradation. The results suggest that all of the investigated POSS molecules play a protective role and may extend the in-use lifetime of …
Intercalation effects in LDPE/o-Montmorillonites nanocomposites
2007
Abstract Typical montmorillonite clays (Cloisite ® Na + , Cloisite ® 30B) were modified by treatment with octadecyl ammonium chloride (ODC) and successive additions of octadecylamine (ODA). XRD analyses of the modified clays indicated an increase of the basal spacing of the (0 0 1) planes depending on the ODC or ODA additions. Nanocomposites were prepared by dispersing the modified clays (3% w/w concentration) in LDPE, using a Brabender mixer. XRD measurements of the obtained products indicated in some cases the achievement of intercalation effects, which were confirmed by TEM analysis. Some thermal, mechanical, dynamic-mechanical and rheological properties were evaluated and correlated to …
Formation of ZnO nanowires by anodization under hydrodynamic conditions for photoelectrochemical water splitting
2020
[EN] The present work studies the influence of hydrodynamic conditions (from 0 to 5000 rpm) during Zn anodization process on the morphology, structure and photoelectrocatalytic behavior of ZnO nanostructures. For this purpose, analysis with Confocal Laser-Raman Spectroscopy, Field Emission Scanning Electron Microscope (FE-SEM) and photoelectrochemical water splitting tests were performed. This investigation reveals that hydrodynamic conditions during anodization promoted the formation of ordered ZnO nanowires along the surface that greatly enhance its stability and increases the photocurrent density response for water splitting in a 159% at the 5000 rpm electrode rotation speed.
On the Role of Extensional Flow in Morphology and Property Modifications of MWCNT/Polyamide-Based Fibers
2011
Unfilled and MWCNT-filled PA fibers are prepared and the effect of the extensional flow on their mechanical performance and morphological variations is investigated. Morphological analyses using SEM, TEM, and SAXS suggest a stronger orientation of the MWCNTs along the fiber direction with increasing extensional flow. A particular MWCNT bundle formation in the PA drawn nanocomposite fibers is observed for the first time, and a pull-out of the central nanotube in some bundles is noted. The maintenance of the "shish-kebab" structure upon extensional flow is responsible for the mechanical improvements and dimensional stability in MWCNT-filled PA fibers.