Search results for "Mixing"

Phytoplankton assemblages in twenty-one Sicilian reservoirs: relationships between species composition and environmental factors

2000

Data collected in a limnological survey, carried out between 1987 and 1988 on 21 Sicilian reservoirs of varying trophic state, were ordinated using CANOCO 3.1 to generalise the way in which the structure of phytoplankton assemblage is conditioned by both physical and chemical variables. The results showed that in these man-made lakes, characterised by conspicuouswater-level fluctuations, the annual and interannual variability in the abundance and composition of phytoplankton may be strongly influenced by their peculiar hydraulic regimes rather than by nutrient availability. In particular, it was highlighted that, from the early summer, water abstraction often leads to increased circulation …

Steady-state assemblages in a Mediterranean hypertrophic reservoir. The role of Microcystis ecomorphological variability in maintaining an apparent e…

2003

Lake Arancio is a hypertrophicMediterranean man-made lake, located on the southern coast of Sicily. Its artificial origin and the climate make it a very dynamic environment, strongly characterised by very wide water-level fluctuations. These vertical water movements interfere with the thermal stability of the water body often causing the breaking of the thermocline in mid-summer. In addition, the summer level-decrease influences the nutrient dynamics and modifies the zmix/zeu ratio. All these modifications were observed to support a high environmental variability, which was reflected by the richness of its phytoplankton composition and by its dynamics. Nevertheless, an investigation carried…

Trophic structure of vermetid reef community: High trophic diversity at small spatial scales

2013

Stable isotopes were used to investigate contributions of autochthonous (i.e. benthic: epilithon and macroalgae) and allochthonous (i.e. pelagic: phytoplankton) organic matter sources to the diet of suspension-feeders, grazers and predators associated to small reef-pools (cuvettes) created by the reef-building species Dendropoma petraeum in the north-western coast of Sicily (Italy). Contributions of potential food sources were calculated using Bayesian mixing-models and integrated to a multivariate approach to highlight the diversity of C and N pathways within Dendropoma cuvettes. Both pelagic and benthic organic matter sources were exploited by benthic consumers, although clear differences…

Contribution of planktonic and benthic food sources to the diet of the reef-forming vermetid gastropod Dendropoma petraeum in the western Mediterrane…

2012

Abstract In the Mediterranean Sea, the vermetid Dendropoma petraeum (Monterosato, 1884) forms highly biodiverse reefs that have received increasing attention in recent years although very little is known about the food habit of this species. The main goal of this study was to describe the trophic role of planktonic and benthic food sources for D. petraeum . Specimens from three morphological zones of the reef (inner edge, cuvette and outer edge) at two sites with different wave exposure along the north-western coast of Sicily (Italy; western Mediterranean) were compared for δ 13 C and δ 15 N. Isotopic determinations were also carried out on potential food sources identified in epilithon, re…

Discussion on "Protein crystallization: universal thermodynamic vs. specific effects of PEG"

2008

Flank Margin Caves In Telogenetic Limestones In Italy

2017

Almost 20% of Italy is characterized by the outcropping of carbonate massifs ranging in age from Cambrian to Quaternary. Coastal karst is present in many Italian regions: from North-East to South and West: the Gulf of Trieste, the Conero (South of Ancona, Marche), the Adriatic coast of Apulia including Gargano, Murge and Salento, Maratea in Basilicata, Cilento in Campania, Circeo and Gaeta in Latium, Argentario and Giannutri Island in Tuscany, the southernmost part of the Ligurian Alps, Palermo Mts., San Vito Lo Capo, Syracuse coast and Marettimo Island in Sicily, and, especially, in Sardinia, which has carbonate rocks touching the sea along the coast of Balai near Porto Torres, Capo Caccia…

MIXING TIME IN UNBAFFLED STIRRED TANKS

2012

Unbaffled stirred tanks, despite their poorer mixing performance with respect to baffled vessels, are gaining a growing industrial interest as they provide significant advantages in selected applications, including a number of biochemical, food and pharmaceutical processes. There still is however a general lack of information on their mixing performance, that needs to be addressed in order to fully exploit their application potential. The present work is aimed at providing experimental information on mixing rates in an unbaffled vessel operated without top-cover (Uncovered Unbaffled Stirred Tank, UUST). The planar laser induced fluorescence (PLIF) technique was adopted for measuring the dis…

POWER CONSUMPTION IN UNBAFFLED TANKS: SUB AND SUPER-CRITICAL REGIMES

2013

Unbaffled stirred tanks are increasingly recognized as a viable alternative to common baffled tanks for a range of processes (e.g. crystallization, food and pharmaceutical processes, etc) where the presence of baffles is undesirable for some reason. Also, in the case of bioreactors for animal cell cultivation, where cell damage is mainly related to bubbles bursts at the air –liquid interface, unbaffled tanks have been shown to be able to provide sufficient mass transfer through the free surface vortex. As a consequence bubble formation and subsequent bursting is conveniently avoided (Scargiali et al., 2012). The same feature clearly makes unbaffled vessels potentially advantageous for any f…

Reattore per la precipitazione di micro e nano-particelle

2009

Digital Image Analysis Technique for mixing pattern measurements in bi-dispersed 2D gas fluidized beds

2011

This work concerns a new experimental technique based on Digital Image Analysis aimed at the measurement of the mixing behaviour of the granular phase in a 2D fluidized bed. In particular, the preliminary results obtained about the mixing pattern of a bi-disperse 2D gas fluidized bed are reported. Two different kind of particles were fluidized having the same density but different size. The technique is based on suitable colour-field decomposition of the fluidized bed, in which particles of different colours are employed. The technique here proposed can effectively measure the concentration field in the whole bed during operation, thus obtaining data that can be reliably used for CFD simula…