1,721,039 research outputs found
Biofouling Processes in Industry - Fouling on artificial substrata
No full textFrom the initial adsorption of organic molecules, to the colonisation by microorganisms, to the development of complex and diverse sessile assemblages, fouling affects most man-made surfaces. Fouling affects the hulls of ships, oilrigs, mariculture cages, pipelines, heat exchangers and seawater intakes in general, resulting in significant economic costs. Fouled ships, for instance, need 40% more fuel in order to maintain the same speed. This leads to a global cost of about 1000 million per year (Alberte et al. 1992).
The costs of fouling are clearly not limited to ship hulls nor to the marine environment. Control of fouling in water intakes, piping systems and desalinisations plants cost over 10 billion per year (Jun & Puri 2005). Biofilm-associated infections extend hospital stays of an average of about three days and it is estimated that up to 65% of nosocomial infections are biofilm-based with an associated treatment cost in excess of $1 billion per year. Up to 82% of nosocomial bacteremias are the result of bacterial contamination of intravascular catheterizations (Archibald & Gaynes 1997).
Biofouling has been described as a four-step sequential ecological process (Wahl 1989). The first two steps, which produce a microbial biofilm, occur similarly whether on a surface in the sea or on a catheter in a hospital room. The following two steps are unique to aquatic habitats and involve the attachment of unicellular and multicellular eukaryotes to an inorganic or living surface.
The multi-step process results from the web of interactions in the initial biofilm and subsequent community of colonizers, culminating in the establishment of a mature community composed of prokaryotes, fungi, protists and adult invertebrates.
Biofouling assemblages on artificial substrata is a complex phenomenon resulting from several processes, the rate and extent of which are influenced by numerous physical, chemical and biological factors in the immediate proximity of the surface and cannot be defined as distinct and univocal entities.
The major structuring factors influencing the development of biofouling communities on artificial substrates are here considered. An emphasis is given on how the interaction between biological systems (micro and macrofouling) can interplay with the nature of substrate in regulating patterns of species settlement and assemblage development. Some guidelines on the use of artificial substrata in the management strategies for controlling fouling in industrial plans are also provided.Biofouling on artificial substrata results from several processes, whose rate and extent are influenced by the intertwining of numerous physical, chemical and biological factors in the immediate proximity of the surface. The importance of substratum features in influencing species settlement is considered here. An emphasis is given on how biological systems (micro- and macrofouling) can interplay with the nature of substratum in regulating patterns of biofouling development. The environmental issues related to the deployment of man-made structures in coastal waters are also discussed, and some guidelines on the use of artificial substrata in the management strategies for controlling fouling in industry are provided
Imposex in Pre-pollution times. Is TBT to blame?
No full textAn experimental analysis of imposex (a bioindicator of TBT marine pollution) in pre pollution tim
Studies on a promising anticancer molecule of marine origin. Results of an interdisciplinary study. . pp: 15-23
No full textAn anticholinesterase molecule may be used against cance
Preliminary analysis on the bioactivity of Salvia spp. exudates on marine model organisms
No full textRecently most interest has been focused on active compounds extracted from natural sources. The genus Salvia from the Lamiaceae family produce a variety of secondary metabolites, many of them have been investigated for their analgesic, anti-inflammatory, hemostatic, antioxidant, antimicrobial, antitumoral activities (Topçu, 2006). The aim of this study is to characterize the bioactivity of exudates extracted from several species of Salvia. A first screening detected the lethality’s effect of extracts from seventeen species of Salvia on Artemia salina; then two species of Salvia already known for their phytotoxicity (Bisio et al., 2010) were tested for their antifouling activity using larvae of the cirriped crustacean Amphibalanus amphitrite (cyprids and nauplii) as model organis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Shallow-water sea fans: the exceptional assemblage of Leptogorgia sarmentosa (Anthozoa: Gorgoniidae) in the Genoa harbour (Ligurian Sea)
No full textAn exceptional assemblage of the sea fan Leptogorgia sarmentosa (Anthozoa: Gorgoniidae) was observed inside the Genoa harbour, which represents one of the major Mediterranean ports. The studied assemblage is confined in a shaded portion of a floating dock thriving in extremely shallow water, with specimens even touching the sea surface. It represents the shallowest population of this species and of this genus known worldwide. A total of 188 specimens were observed and measured: the maximum density of 45 specimens m−2 was reached in the most shaded part of the dock, where the maximum height of colonies (30 cm) was also recorded. Light measurements showed that the illuminance along the dock was comparable to that observed outside the harbour at 20 m depth, where the nearest colonies of L. sarmentosa were recorded for this region. This suggests that high levels of incident light might be putatively interpreted as the limiting factor in the upper bathymetrical distribution of the species. Despite the extremely shallow distribution, however, the population cannot be defined as intertidal as the floating dock avoids exposing the gorgonians to air. The chance to grow far from the silted bottom, but still in a turbid, sciaphilous and nutrient-enriched environment, probably enhanced the settling and growth of the colonies and allowed the formation of a dense and healthy population
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