Search results for "MARINE"

Performance improvement of a Savonius water rotor with novel blade shapes

2021

Abstract Savonius water rotor is a prominent drag based turbine able to extract energy available in flowing water with low velocity like river streams, tidal currents or other man made water canals. However, in view of its low performance, an enhanced design of the rotor blades is necessary to better its efficiency. Therefore, the present study aims to improve the efficiency of Savonius rotor by changing the blade design. Different blade shapes were investigated numerically using computational fluid dynamics (CFD). Using conventional design, the peak power coefficient was found to be 0.166 at tip-speed ratio of 0.78. However, the peak power coefficient reaches 0.184 using the optimal blade …

Cultivable Fungal Endophytes in Roots, Rhizomes and Leaves of Posidonia oceanica (L.) Delile along the Coast of Sicily, Italy

2022

The presence of endophytic fungi in the roots, rhizomes, and leaves of Posidonia oceanica was evaluated in different localities of the Sicilian coast. Samples of roots, rhizomes, and leaves were submitted to isolation techniques, and the obtained fungal colonies were identified by morphological and molecular (rRNA sequencing) analysis. Fungal endophytes occurred mainly in roots and occasionally in rhizomes and leaves. Lulwoana sp. was the most frequent of the isolated taxa, suggesting a strong interaction with the host. In addition, eight other fungal taxa were isolated. In particular, fungi of the genus Ochroconis and family Xylariaceae were identified as endophytes in healthy plants at al…

Reto un izzūdošo Latvijas savvaļas orhideju bioloģiskās īpatnības in situ un in vitro

2012

Promocijas darbs (publikāciju kopa) tika izstrādāts V/a „Nacionālais Botāniskais dārzs Augu valsts bioloģiskās daudzveidības in vitro saglabāšanas nodaļā laika posmā no 2008. līdz 2011. gadam. Ģenētiskie pētījumi tika veikti LU Bioloģijas institūta Augu Ģenētikas laboratorijā 2010. un 2012. gadā.

Cold plumes trigger contamination of oceanic mantle wedges with continental crust-derived sediments: Evidence from chromitite zircon grains of easter…

2018

The origin of zircon grains, and other exotic minerals of typical crustal origin, in mantle-hosted ophiolitic chromitites are hotly debated.We report a population of zircon grains with ages ranging from Cretaceous (99 Ma) to Neoarchean (2750 Ma), separated from massive chromitite bodies hosted in the mantle section of the supra-subduction (SSZ)-type Mayarí-Baracoa Ophiolitic Belt in eastern Cuba. Most analyzed zircon grains (n = 20, 287 +/- 3 Ma to 2750 +/- 60 Ma) are older than the early Cretaceous age of the ophiolite body, show negative εHf(t) (+/-26 to +/-0.6) and occasional inclusions of quartz, K-feldspar, biotite, and apatite that indicate derivation from a granitic continental crust…

Modelling biogeochemical processes in sediments from the north-western Adriatic Sea: response to enhanced particulate organic carbon fluxes

2018

This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural particulate organic carbon (POC) downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment trap data, and its effects on sediment bioirrigation capacity and organic matter (OM) degradation pathways were investigated constraining an early diagenesis model by using original data collected in sediment porewater. The measurements were performed at stations located inside and outside the ar…

Global sea-to-air flux climatology for bromoform, dibromomethane and methyl iodide

2013

Volatile halogenated organic compounds containing bromine and iodine, which are naturally produced in the ocean, are involved in ozone depletion in both the troposphere and stratosphere. Three prominent compounds transporting large amounts of marine halogens into the atmosphere are bromoform (CHBr3), dibromomethane (CH2Br2) and methyl iodide (CH3I). The input of marine halogens to the stratosphere has been estimated from observations and modelling studies using low-resolution oceanic emission scenarios derived from top-down approaches. In order to improve emission inventory estimates, we calculate data-based high resolution global sea-to-air flux estimates of these compounds from surface ob…

Investigation of marine and continental layers in a stalactite older than 1 million years (Custonaci, north-western sector of Sicily)

2012

Questo lavoro si basa sul ritrovamento, in una grotta carsica, a 100 metri di quota a Custonaci in provincia di Trapani, di una stalattite di notevole interesse paleo climatico, ricoperta da coralli marini, la cui sezione rivela la presenza di 3 Iatus che denotano una interruzione della deposizione di carbonato continentale presumibilmente in seguito a trasgressioni marine. Il carbonato, datato attraverso la metodologia 230Th/U MC-ICPMS (NeptunePlus), ha fornito una età più antica del limite temporale massimo di applicabilità del metodo ( 600 ka). I coralli, che ricoprono il livello continentale più giovane, analizzati usando il rapporto 87Sr/86Sr, hanno fornito una età di 1.1±0.2 Myrs. Al…

Paris Biota: At the dawn of modern marine faunas?

2021

Modéliser la réponse des espèces marines antarctiques aux changements environnementaux. Méthodes, applications et limites.

2021

Among tools that are used to fill knowledge gaps on natural systems, ecological modelling has been widely applied during the last two decades. Ecological models are simple representations of a complex reality. They allow to highlight environmental drivers of species ecological niche and better understand species responses to environmental changes. However, applying models to Southern Ocean benthic organisms raises several methodological challenges. Species presence datasets are often aggregated in time and space nearby research stations or along main sailing routes. Data are often limited in number to correctly describe species occupied space and physiology. Finally, environmental datasets …

Effects of hydrostatic pressure on yeasts isolated from deep-sea hydrothermal vents

2015

International audience; Hydrostatic pressure plays a significant role in the distribution of life in the biosphere. Knowledge of deep-sea piezotolerant and (hyper)piezophilic bacteria and archaea diversity has been well documented, along with their specific adaptations to cope with high hydrostatic pressure (HHP). Recent investigations of deep-sea microbial community compositions have shown unexpected micro-eukaryotic communities, mainly dominated by fungi. Molecular methods such as next-generation sequencing have been used for SSU rRNA gene sequencing to reveal fungal taxa. Currently, a difficult but fascinating challenge for marine mycologists is to create deep-sea marine fungus culture c…