Search results for "Fish"

On-line speciation of mercury in fish by cold vapour atomic fluorescence through ultrasound-assisted extraction

2004

A fully mechanized procedure has been developed for the speciation of mercury in fish samples by using cold vapour atomic fluorescence spectrometry (CV-AFS). Sample slurries in an acid mixture in the presence of a surfactant and with traces of K2Cr2O7, were injected into a flow system, sonicated and merged with 1 ml of an oxidant mixture of KBr/KBrO3 heated at 50 °C in a water bath and total Hg determined by CV-AFS. Sonicated sample slurries were also measured, in the absence of KBr/KBrO3, in order to obtain a second series of data which could be employed to establish the concentrations of free Hg(II). Different compositions of the acidic extractant solutions were evaluated by mixing HCl, H…

Development of a pressurised liquid extraction and liquid chromatography with electrospray ionization-tandem mass spectrometry method for the determi…

2006

Amnesic shellfish poisoning (ASP) is a potentially lethal human toxic syndrome which is caused by domoic acid (DA) that originates in marine phytoplankton belonging to the Pseudonitzschia genus. A confirmatory and sensitive procedure has been developed and validated for the determination of DA in shellfish. The proposed method includes pressurised liquid extraction (PLE) with methanol/acetone (9:1), florisil ® cleanup purification inside the PLE extraction cell and detection by liquid chromatography (LC) coupled to electrospray ionization in positive mode tandem mass spectrometry (ESI-MS–MS). Comparison of ionization sources (ESI, atmospheric pressure ionization (APCI) atmospheric pressure …

Experimental Study on the Diet of Mosquitofish (Gambusia holbrooki) under Different Ecological Conditions in a Shallow Lake

2004

We studied the diet of the eastern mosquitofish Gambusia holbrooki with in situ experimental mesocosms located in a shallow lake. Different nutrient concentrations (phosphorus and nitrogen) and fish population densities were tested. Our results confirm that it is a planktivorous species, with also a great ingestion of algae and detritus. Nutrient fertilization caused almost no changes in this species feeding behavior, but larger mosquitofish stocks induced a shift to zooplanktivory and a decline in detritivory. When macrophytes were present, the predation effect focused on zooplankton and plant-associated animals, otherwise predation on bottom macroinvertebrates increased. Females preyed up…

Imaging of nitric oxide in a living vertebrate using a diaminofluorescein probe

2007

Abstract Numerous approaches have been described to identify nitric oxide (NO), a free radical involved in various physiological and pathophysiological processes. One of these approaches is based on the use of chemical probes whose transformation by NO generates highly fluorescent derivatives, permitting detection of NO down to nanomolar concentrations. Here, we show that the cell-permeant diaminofluorophore 4-amino-5-methylamino-2′-7′-difluorofluorescein diacetate (DAF-FM-DA) can be used to detect NO production sites in a living vertebrate, the zebrafish Danio rerio. The staining pattern obtained in larvae includes the bulbus arteriosus, forming bones, the notochord, and the caudal fin. Th…

Bottlenecks in diagnostics of mediterranean fish diseases

2020

Three independent Horizon 2020 projects are prioritising a common task of solving diagnostic issues using different approaches and strategies. PerformFISH focuses its research objectives on diagnostic methods, MedAID has prepared a diagnostic manual for the most devastating fish diseases of the Mediterranean and ParaFishControl has prepared a diagnostic manual on parasitic diseases of European aquaculture species. Currently, the projects are investing large collaborative efforts to reinforce their tasks and to deliver mutual and cutting-edge material on the subject. Nevertheless, further efforts for the harmonisation, standardisation and validation of diagnostic methods for infectious disea…

Pesticides in the Ebro River basin: Occurrence and risk assessment

2016

In this study, 50 pesticides were analyzed in the Ebro River basin in 2010 and 2011 to assess their impact in water, sediment and biota. A special emphasis was placed on the potential effects of both, individual pesticides and their mixtures, in three trophic levels (algae, daphnia and fish) using Risk Quotients (RQs) and Toxic Units (TUs) for water and sediments. Chlorpyrifos, diazinon and carbendazim were the most frequent in water (95, 95 and 70% of the samples, respectively). Imazalil (409.73 ng/L) and diuron (150 ng/L) were at the highest concentrations. Sediment and biota were less contaminated. Chlorpyrifos, diazinon and diclofenthion were the most frequent in sediments (82, 45 and 2…

Simultaneous clean up of fish fat containing low levels of residues and separation of PCB from chlorinated pesticides by thin-layer chromatography

1974

Testing a theoretical resistance law for overland flow under simulated rainfall with different types of vegetation

2020

Abstract In this paper a recently theoretically deduced flow resistance equation, based on a power-velocity profile, was tested using data collected for overland flow under simulated rainfall carried out in plots with vegetation. The available data were obtained exploring a wide range of rainfall intensities (from 60 to 181 mm h−1) and slopes (from 3.6 to 39.6%), and with four different types of vegetation. The database, including measurements of flow velocity, water depth, cross sectional flow area, wetted perimeter and bed slope, was divided in four datasets (one for each vegetation type), which allowed the calibration of the relationship between the velocity profile parameter Γ, the slop…

Evaluating the Effects of Sediment Transport on Pipe Flow Resistance

2021

In this paper, the applicability of a theoretical flow resistance law to sediment-laden flow in pipes is tested. At first, the incomplete self-similarity (ISS) theory is applied to deduce the velocity profile and the corresponding flow resistance law. Then the available database of measurements carried out by clear water and sediment-laden flows with sediments having a quasi-uniform sediment size and three different values of the mean particle diameter Dm (0.88 mm, 0.41 mm and 0.30 mm) are used to calibrate the Γ parameter of the power-velocity profile. The fitting of the measured local velocity to the power distribution demonstrates that (i) for clear flow the exponent δ can be estimated b…

Common Fixed points for multivalued generalized contractions on partial metric spaces

2013

We establish some common fixed point results for multivalued mappings satisfying generalized contractive conditions on a complete partial metric space. The presented theorems extend some known results to partial metric spaces. We motivate our results by some given examples and an application for finding the solution of a functional equation arising in dynamic programming.