Search results for " MORPHOLOGY"
showing 10 items of 543 documents
Micro‐tomographic characterization of composite recycled glass‐silicone foams for applications in civil engineering
2019
Noninvasive X‐ray micro‐computed tomography was applied for a complete quantitative and qualitative analysis of the cellular structure of composite foams constituted by a silicone matrix and a glass production waste filler. Composite foams with different glass filler weight content in the range 0–80% were synthesized and characterized. The tomographic analysis was employed in order to assess the structural heterogeneities, void fraction values, and bubble size distribution for all composite foams. The 3D micro‐CT images analysis, performed at different cross‐sections, highlighted heterogeneous cell growth or more elongated cells in the case of low and high filler content foams, respectively…
Effect of ageing on the morphology and creep and recovery of polymer-modified bitumens
2018
Polymer additives are used to improve the properties of road bitumens including their oxidative resistance. However, their usage as anti-oxidative materials remains relatively unclear. This study aims to investigate the changes in the morphology and the rheological response of polymer modified bitumens used in road pavement construction caused by ageing. An elastomer (radial styrene butadiene styrene, SBS) and a plastomer (ethyl vinyl acetate, EVA) polymer were mixed with one base bitumen at three polymer concentrations. The bitumens were RTFO and PAV aged. The morphology of the bitumens was captured by fluorescence microscopy while the rheological properties were measured by means of the m…
Morphology, mechanical properties and thermal degradation kinetics of PMMA-zirconia nanocomposites prepared by melt compounding
2012
Zirconia nanoparticles were synthesized by means of a sol-gel method and embedded in poly(methyl methacrylate) (PMMA) by melt compounding. The zirconia was well dispersed in the PMMA matrix, with only a few clusters, especially for the highest investigated zirconia content. NMR results showed heteronuclear dipolar interactions involving the carbons and the surrounding hydrogen nuclei. The effect of the amount of zirconia, in the range of 1–5!wt%, on the thermomechanical properties and thermal degradation kinetics of PMMA was also investigated by means of dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), and Fourier-transform infrared spectroscopy (FTIR). The presenc…
PHENOLOGICAL AND MORPHOLOGICAL STUDIES OF PISTACIA TEREBINTHUS L. GENOTYPES NATIVE OF BULGARIA WITH DIFFERENT ASSET OF TREE SEXUALITY
2009
The genus Pistacia is a dioecious species staminate and pistillate inflorescences born on different trees and are wind pollinated. In pistachio orchards, female and male flowering periods are often not synchronized. In fact, male trees spread their pollen before the flowers of female trees become receptive. Pollination is commonly devoted to spontaneous males of P. terebinthus. In this research authors refer to the results obtained observing the phenology of the blooming period of monoicous genotypes of P. terebinthus discovered in the Rhodope Mountains (Bulgaria). In some selected trees phenological stages have been observed in situ. The blooming date is influenced by local environmental c…
A new species of Ferula (Apiaceae) from Malta
2018
Ferula melitensis, a new species from the Malta Archipelago, is described and illustrated. It belongs to the taxonomic group of F. communis, showing close relationships mainly with F. tunetana, F. arrigonii, F. communis s.str. and F. glauca, from which it differs in several features regarding the stem, leaves (mainly for shape and size of terminal segments), flowers and mericarps; other significant differences regard the ecology and phenology. The investigations, carried out on living plants, herbarium material and literature data, regard the morphological analysis of vegetative and reproductive structures, the anatomy of terminal leaf segments and mericarps, as well as the shape and size o…
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…
Plant Morphology: The Historic Concepts of Wilhelm Troll, Walter Zimmermann and Agnes Arber
2001
Recent molecular systematic and developmental genetic findings have drawn attention to plant morphology as a discipline dealing with the phenotypic appearance of plant forms. However, since different terms and conceptual frameworks have evolved over a period of more than 200 years, it is reasonable to survey the history of plant morphology; this is the first of two papers with this aim. The present paper deals with the historic concepts of Troll, Zimmermann and Arber, which are based on Goethe's morphology. Included are contrasting views of ‘unity and diversity’, ‘position and process’, and ‘morphology and phylogeny’, which, in part, are basic views of current plant morphology, phylogenetic…
Long term effects of peripubertal stress on excitatory and inhibitory circuits in the prefrontal cortex of male and female mice.
2021
Abstract The impact of stressful events is especially important during early life, because certain cortical regions, especially the prefrontal cortex (PFC), are still developing. Consequently, aversive experiences that occur during the peripubertal period can cause long-term alterations in neural connectivity, physiology and related behaviors. Although sex influences the stress response and women are more likely to develop stress-related psychiatric disorders, knowledge about the effects of stress on females is still limited. In order to analyze the long-term effects of peripubertal stress (PPS) on the excitatory and inhibitory circuitry of the adult PFC, and whether these effects are sex-d…
Influence of cadmium on the morphology and functionality of haemocytes in the compound ascidian Botryllus schlosseri
2013
In order to get insights into the effects of cadmium (Cd) on cell morphology and functions, we exposed haemocytes of the colonial ascidian Botryllus schlosseri to sub-lethal concentrations of CdCl(2). Results indicate that Cd hampers haemocyte spreading and phagocytosis in a dose-dependent way, through the alteration of the actin cytoskeleton. In addition, the metal decreases the stability of the internal membranes, as revealed by the Neutral Red assay. The fraction of cells showing positivity for the lysosomal enzyme acid phosphatase is also reduced in the presence of Cd, whereas the number of cells responsive to the Annexin-V assay and showing chromatin condensation increases, suggesting …
Niche
2020
No concept in ecology has been more variously defined or more universally confused than ‘niche’.