Microscopic and IR spectroscopic comparison of the underwater adhesives produced by germlings of the brown seaweed species Durvillaea antarctica and Hormosira banksii

Adhesives from marine organisms are often the source of inspiration for the development of glues able to create durable bonds in wet environments. In this work we investigated the adhesive secretions produced by germlings of two large seaweed species from the South Pacific, Durvillaea antarctica, also named “the strongest kelp in the word”, and its close relative Hormosira banksii. The comparative analysis was based on optical and scanning electron microscopy imaging as well as FTIR spectroscopy and principal component analysis (PCA). For both species, the egg surface presents peripheral vesicles which are released soon after fertilization to discharge a primary adhesive. This is characterized by peaks representative of carbohydrate molecules. A secondary protein-based adhesive is then secreted in the early developmental stages of the germlings. EDX, FTIR and PCA indicate that D. antarctica secretions also contain sulphated moieties, and become cross-linked with time, both conferring strong adhesive and cohesive properties. On the other hand, H. banksii secretions are complemented by the putative adhesive phlorotannins, and are characterized by a simple mechanism in which all constituents are released with the same rate and with no apparent cross-linking. It is also noted that the release of adhesive materials appears to be faster and more copious in D. antarctica than in H. banksii. Overall, this study highlights that both quantity and quality of the adhesives matter in explaining the superior attachment ability of D. antarctica

Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

Polarisation-channel-interleaved carrier-suppressed RZ ETDM/DWDM transmission at 40 Gbit/s with 0.8 bit/s/Hz spectral efficiency

The polarization-channel-interleaved carrier-suppressed dense wavelength division multiplexing (DWDM) transmission at 40 Gbit/s at 0.8 bit/s spectral efficiency was demonstrated. The approach used was successful in minimizing the impact of non-linear multichannel crosstalk. The loss in polarization orthogonality was attributed to the use of very narrow bandwidth demultiplexers

Polarisation-channel-interleaved CS-RZ transmission at 40 Gbit/s with 0.8 bit/s/Hz spectral efficiency

Experimental results are reported of polarisation-channel-interleaved carrier-suppressed RZ (PCI CS-RZ) ETDM/DWDM transmission of 8 × 40 Gbit/s over 320 km (2 × 160 km) NDSF, with 0.8 bit/s/Hz spectral efficiency. An average system linear Q of 6.5 at a PRBS pattern length of 231 - 1 and tolerance to at least 50% degradation in orthogonality are demonstrated