97 research outputs found
Spatial and Temporal Changes of Tidal Inlet Using Object-Based Image Analysis of Multibeam Echosounder Measurements: A Case from the Lagoon of Venice, Italy
Scientific exploration of seabed substrata has significantly progressed in the last few years.
Hydroacoustic methods of seafloor investigation, including multibeam echosounder measurements,
allow us to map large areas of the seabed with unprecedented precision. Through time-series of
hydroacoustic measurements, it was possible to determine areas with distinct characteristics in the
inlets of the Lagoon of Venice, Italy. Their temporal variability was investigated. Monitoring the
changes was particularly relevant, considering the presence at the channel inlets of mobile barriers
of the Experimental Electromechanical Module (MoSE) project installed to protect the historical
city of Venice from flooding. The detection of temporal and spatial changes was performed by
comparing seafloor maps created using object-based image analysis and supervised classifiers.
The analysis included extraction of 25 multibeam echosounder bathymetry and backscatter features.
Their importance was estimated using an objective approach with two feature selection methods.
Moreover, the study investigated how the accuracy of classification could be affected by the scale of
object-based segmentation. The application of the classification method at the proper scale allowed
us to observe habitat changes in the tidal inlet of the Venice Lagoon, showing that the sediment
substrates located in the Chioggia inlet were subjected to very dynamic changes. In general, during
the study period, the area was enriched in mixed and muddy sediments and was depleted in sandy
deposits. This study presents a unique methodological approach to predictive seabed sediment
composition mapping and change detection in a very shallow marine environment. A consistent,
repeatable, logical site-specific workflow was designed, whose main assumptions could be applied to
other seabed mapping case studies in both shallow and deep marine environments, all over the world
Two-compartment micellar assemblies obtained via aqueous self-organization of synthetic polymer building blocks
Lamellar structured nanoparticles formed by complexes of a cationic block copolymer and perfluorodecanoic acid
Solid-state structure of polypeptide-based rod-coil block copolymers: Folding of helices
This work compares the solid-state structures of films made from a polystyrene-poly(Z-L-lysine) (1) and a polystyrene-poly(γ-benzyl-L-glutamate) (2) block copolymer, both having virtually the same numbers of repeating units and block length ratios. Small-angle X-ray scattering (SAXS) revealed a hexagonal-in-undulated lamellar morphology for both films. The long-period and the thickness of layers obtained for 2 were by a factor of three smaller as compared to 1, indicating that PBLGlu helices were folded twice, whereas PZLLys helices were fully stretched. Another difference shows up in the packing of helices, the level of ordering being considerably lower in 2. This might be due to spatial restrictions in the proper alignment of back-folded helical segments
Cylindrical micelles of alpha-fluorocarbon-omega-hydrocarbon end-capped poly(N-acylethylene imine)s
Multicompartment micelles formed by self-assembly of linear ABC triblock copolymers in aqueous medium
Thin layers of columns of an amphiphilic hexa-peri-hexabenzocoronene at silicon wafer surfaces
We present here the preparation and the structures of thin films of an amphiphilic hexa-peri-hexabenzocoronene (HBC) containing 1, 5, 9, and 15 layers of columns. These films were prepared by the Langmuir-Blodgett technique on poly(ethylene imine) functionalized silicon wafers and investigated by X-ray reflectivity measurements using synchrotron radiation. Columns of HBC cores were aligned parallel to the silicon wafer surface. The thicknesses of the films, which were composed of stacks of highly coherent HBC layers plus a polymer layer, were 3.70-34.6 nm. Each HBC layer has a thickness of 2.4 nm. The transfer rate of the HBC monolayers from the water/air surface to the silicon wafer surface is close to 100%. A macroscopic in-plane orientation of the columns with their main axis parallel to the dipping direction was determined by polarized UV-vis spectroscopy
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