Search results for "MORPHOLOGY"
showing 10 items of 1425 documents
Rank-order and morphological enhancement of image details with an optoelectronic processor.
2010
In all-optical processors, enhancement of image details is the result of high-pass filtering. We describe an optoelectronic processor in which detail enhancement results from the digitally calculated difference between an original input image and its low-pass filtered version. The low-pass filtering is realized through the rank-order median and the morphological opening and closing operations calculated by use of the optical convolver. It is shown that the normalized difference between the morphological white and black top hats enhances bright and dark image details analogously to the rank-order unsharp masking.
High magnification SEM observations for two types of granularity in a high burnup PWR fuel rim
1998
Abstract Rim microstructure of an UO2 pellet irradiated up to 61 GWd/tU, observed with high magnification scanning electron microscopy, presented two types of subgrains: polyhedral and round subgrains. Round subgrains were also observed on the surface of fabrication pores along the pellet radius. These round-shaped subgrains seem to be associated to free surface rearrangement. This new type of round subgrains was proved to be independent of the rim effect. Observations of the fuel structure in the vicinity of rim area evidenced two types of defects specific to rim effect: planar defects and small intergranular pores. Hypothesis is made that the accumulation of planar defects could generate …
Theoretical Study of the Charge Transfer Exciton Binding Energy in Semiconductor Materials for Polymer:Fullerene-Based Bulk Heterojunction Solar Cells
2019
Recent efforts and progress in polymer solar cell research have boosted the photovoltaic efficiency of the technology. This efficiency depends not only on the device architecture but also on the material properties. Thus, insight into the design of novel semiconductor materials is vital for the advancement of the field. This paper looks from a theoretical viewpoint into two of the factors for the design of semiconductor materials with applications to bulk heterojunction solar cells: the charge transfer exciton binding energy and the nanoscale arrangement of donor and acceptor molecules in blend systems. Being aware that the exciton dissociation of local excitons in charge transfer states in…
Seawater carbonate chemistry and shell mineralogy, microstructure, and mechanical strength of four Mediterranean gastropod species near a CO2 seep
2017
Marine CO2 seeps allow the study of the long-term effects of elevated pCO2 (ocean acidification) on marine invertebrate biomineralization. We investigated the effects of ocean acidification on shell composition and structure in four ecologically important species of Mediterranean gastropods (two limpets, a top-shell snail, and a whelk). Individuals were sampled from three sites near a volcanic CO2 seep off Vulcano Island, Italy. The three sites represented ambient (8.15 pH), moderate (8.03 pH) and low (7.73 pH) seawater mean pH. Shell mineralogy, microstructure, and mechanical strength were examined in all four species. We found that the calcite/aragonite ratio could vary and increased sign…
Physiological advantages of dwarfing in surviving extinctions in high-CO2 oceans
2015
Excessive CO2 in the present-day ocean-atmosphere system is causing ocean acidification, and is likely to cause a severe biodiversity decline in the future, mirroring effects in many past mass extinctions. Fossil records demonstrate that organisms surviving such events were often smaller than those before, a phenomenon called the Lilliput effect. Here, we show that two gastropod species adapted to acidified seawater at shallow-water CO2 seeps were smaller than those found in normal pH conditions and had higher mass-specific energy consumption but significantly lower whole-animal metabolic energy demand. These physiological changes allowed the animals to maintain calcification and to partial…
The impact of ocean acidification and warming on the skeletal mechanical properties of the sea urchin Paracentrotus lividus from laboratory and field…
2016
Increased atmospheric CO2 concentration is leading to changes in the carbonate chemistry and the temperature of the ocean. The impact of these processes on marine organisms will depend on their ability to cope with those changes, particularly the maintenance of calcium carbonate structures. Both a laboratory experiment (long-term exposure to decreased pH and increased temperature) and collections of individuals from natural environments characterized by low pH levels (individuals from intertidal pools and around a CO2 seep) were here coupled to comprehensively study the impact of near-future conditions of pH and temperature on the mechanical properties of the skeleton of the euechinoid sea …
Seawater carbonate chemistry and kelp densities and coral coverages at three study locations and photosynthesis and calcification of corals measured …
2021
Ocean warming is altering the biogeographical distribution of marine organisms. In the tropics, rising sea surface temperatures are restructuring coral reef communities with sensitive species being lost. At the biogeographical divide between temperate and tropical communities, warming is causing macroalgal forest loss and the spread of tropical corals, fishes and other species, termed “tropicalization”. A lack of field research into the combined effects of warming and ocean acidification means there is a gap in our ability to understand and plan for changes in coastal ecosystems. Here, we focus on the tropicalization trajectory of temperate marine ecosystems becoming coral-dominated systems…
Insights fromsodium into the impacts of elevated pCO2 and temperature on bivalve shell formation
2017
Ocean acidification and warming are predicted to affect the ability of marine bivalves to build their shells, but little is known about the underlying mechanisms. Shell formation is an extremely complex process requiring a detailed understanding of biomineralization processes. Sodium incorporation into the shells would increase if bivalves rely on the exchange of Na+/H+ to maintain homeostasis for shell formation, thereby shedding new light on the acid-base and ionic regulation at the calcifying front. Here, we investigated the combined effects of seawater pH (8.1, 7.7 and 7.4) and temperature (16 and 22 °C) on the growth and sodium composition of the shells of the blue mussel, Mytilus edul…
Sodium provides unique insights into transgenerational effects of ocean acidification on bivalve shell formation
2016
Ocean acidification is likely to have profound impacts on marine bivalves, especially on their early life stages. Therefore, it is imperative to know whether and to what extent bivalves will be able to acclimate or adapt to an acidifying ocean over multiple generations. Here, we show that reduced seawater pH projected for the end of this century (i.e., pH 7.7) led to a significant decrease of shell production of newly settled juvenile Manila clams, Ruditapes philippinarum. However, juveniles from parents exposed to low pH grew significantly faster than those from parents grown at ambient pH, exhibiting a rapid transgenerational acclimation to an acidic environment. The sodium composition of…
Ocean acidification impairs vermetid reef recruitment
2014
Vermetids form reefs in sub-tropical and warm-temperate waters that protect coasts from erosion, regulate sediment transport and accumulation, serve as carbon sinks and provide habitat for other species. The gastropods that form these reefs brood encapsulated larvae; they are threatened by rapid environmental changes since their ability to disperse is very limited. We used transplant experiments along a natural CO2 gradient to assess ocean acidification effects on the reef-building gastropod Dendropoma petraeum. We found that although D. petraeum were able to reproduce and brood at elevated levels of CO2, recruitment success was adversely affected. Long-term exposure to acidified conditions…