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Application of nanotechnologies in aquaculture
Full text linkLe nanotecnologie possiedono un vasto potenziale nella produzione di materiali con nuove ed uniche proprietà attraverso il controllo e la manipolazione della materia su scala atomica e molecolare.
Le nanoparticelle giocano un ruolo importante nello sviluppo della nanotecnologia, grazie alle loro caratteristiche uniche hanno favorito la crescita nella produzione di materiali su nanoscala e il loro impiego in molteplici settori. I principali vantaggi derivanti dall’uso delle nanoparticelle sono rappresentati dalle loro ridotte dimensioni ed il loro elevato rapporto superficie/volume che le rendono promotori chiave nella crescita di molti settori industriali e di ricerca.
L’acquacoltura rappresenta il settore in più rapida crescita nell’industria alimentare a livello mondiale, contribuendo in modo significativo alla fornitura mondiale di pesce per il consumo umano.
Per garantire una crescita sostenibile in grado di soddisfare le richieste del mercato globale, l’acquacoltura deve superare gli aspetti negativi legati alla sua stessa attività tra i quali, l’elevata concentrazione di composti organici nelle acque reflue non trattate, l’uso diffuso di antibiotici e la proliferazione di alcuni vettori di malattie. L’utilizzo delle nanotecnologie potrebbe offrire diverse soluzioni per risolvere tali problematiche permettendo uno sviluppo sostenibile dell’attività di acquacoltura. Grazie ad un approccio multidisciplinare che include analisi molecolari, chimiche e microscopiche, questo studio è stato in grado di testare l’utilizzo sicuro e innovativo di due diversi tipi di nanoparticelle in diversi settori dell’acquacoltura.
Sono stati scelti diversi organismi modello (Danio rerio, Sparus aurata, Aedes aegypti e Escherichia coli) considerati come le specie più rilevanti ed utili per questa ricerca.
Questa tesi di dottorato, ha evidenziato sia la grande versatilità sia il sicuro impiego di questi due tipi di nanomateriali per la risoluzione di diverse problematiche legate all’attività dell’acquacoltura. Tutti gli esperimenti sono stati condotti in ambiente controllato e ponendo le basi per studi futuri e possibili applicazioni pratiche nel settore dell’acquacoltura.Nanotechnology has a great potential to create new materials with enhanced properties through the control and manipulation of the matter at the atomic and molecular level.
Nanoparticles (NPs) play an important role in nanotechnology advances, unique NPs characteristics have accelerated the growth in the production of nanoscale materials and the rapid increase of their application in many areas. The major advantages of NPs are represented by their small size and high surface/volume ratio, which make them the key promoters of several industries and research sectors growth. Aquaculture represents the fastest growing food-producing sector in the world and significantly contributes to the world’s supply of fish for human consumption. In order to guarantee a sustainable growth that meets the global needs, aquaculture activity has to overcome some disadvantageous aspects deriving from its own practices, such as the high number of organic compounds in untreated wastewater, the large use of antibiotics and the proliferation of disease vectors. Nanotechnology application could offer different solutions to solve such issues and ensure the sustainable development of aquaculture activity.
Thanks to a multidisciplinary approach that includes molecular, chemical and microscopy analysis, this study was able to test the innovative and safe application of two different types of nanotechnology on different aquaculture aspects. Different model organisms (Danio rerio, Sparus aurata, Aedes aegypti, and Escherichia coli) were chosen as the most relevant and useful species to the present research.
This doctoral thesis highlighted at first, the great versatility and the safe application of these two types of nanomaterial to solve different aquaculture problems. All the experiments were conducted in a controlled aquatic environment laying the foundations for future studies aiming to a practical consequence in aquaculture activity
Silica coating prevents magnetic nanoparticles toxicity: a morphological and molecular study in Zebrafish
No full textNanoparticles (NPs) are novel man-made materials on the nanoscale. A wide range of nanomaterials is being developed for technical applications and for use in consumer products. Metal NPs, including superparamagnetic iron oxide NPs [magnetite (Fe3O4) and maghemite (γ-Fe2O3)], are interesting tools that can be used in a wide range of biomedical applications. Researches are still in progress and reports about the toxicity of iron oxide NPs are often contradictory. Recent studies carried out in fish, have described different sublethal effects ranging from respiratory toxicity, to oxidative stress involving gill, liver, and gut function and morphology (Li et al. 2009). Moreover, several investigations have found that early life stages, such as embryos and larvae, are more sensitive to NPs than adult forms. The main route of NPs exposure for fish is through the food and the food web and NPs biomagnification, bioaccumulation and bioconcentration phenomena have also been described.
NPs encapsulation procedures in a robust shell made of gold, silica, zinc oxide, a polymer, or liposomes not only protects the magnetic core from chemical reactions but also prevents interactions with sensitive biological media. In particular, the silica coating provides stable and multifunctional NPs. Considering that datasets on this topic are still limited and that the effects of dietary exposure to silica-coated magnetic NPs have never been studied so far, this study, explores for the first time silica-coated magnetic NPs direct action on zebrafish (ZF) larvae fed NP-contaminated food and longer-term effects on adults. A multidisciplinary approach, including morphometric examination (light, transmission electron, and confocal microscopy), inductively coupled plasma emission spectrometry and real-time PCRs was applied to detect NPs accumulation, structural and ultrastructural damage, and activation of detoxification processes in larvae and adults
One year study on the reproductive biology, ovary characterization and age of the European sardine (Sardina pilchardus) in the middle-west Adriatic Sea
Full text linkThe ecological and economic relevance of the European sardine (Sardina pilchardus) in the Adriatic area is well established. High exploitation rates and instability of environmental parameters could potentially impair the reproductive physiology of this species, compromising the stock's stability. To guarantee efficient stock management, there is a need to fill the lack of updated information regarding the structure, sex ratio and reproductive season of the sardine population in the Adriatic Sea. The present study provides new data on the distribution of females' maturation phases, sex ratio, age frequency and seasonality of the reproductive period in the middle-western Adriatic Sea. Sardine specimens were collected monthly, from April 2021 to March 2022 in the Adriatic waters off the coast of Ancona. Size, weight and sex were determined for a sub-sample of almost 144 specimens during each sampling period. Through otolith analysis and ovary characterization, population age and females' maturation phase were estimated respectively. The results obtained highlighted a general reduction in size (15.5cm the highest size class) and age (maximum age 2+, greater than 2 years old but less than 3 years) of the population that was characterized by the predominance of males. Also, an interesting scarcity of small female specimens (< 13 cm length) was observed. The reproductive period seemed to occur between October and June as suggested by ovarian characterization, GSI (0.50, 0.30 and 0.62 respectively) and Fulton's condition factor (0.73, 0.74 and 0.74 respectively) analysis that showed the lowest values in July, August and September corresponding to the rest period
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Growth and stress factors in ballan wrasse (Labrus bergylta) larval development
No full textBallan wrasse (Labrus bergylta) is a specialized cleaner fish used in salmon farms as a biological treatment against sea lice. Its commercial rearing is at present mostly experimental. A number of key aspects, including the molecular and physiological mechanisms that promote its growth and development, are still largely unexplored. In this study histological, biometric, biochemical and molecular approaches are combined for the first time to investigate the changes in growth (insulin-like growth factor 1 and 2 and myostatin) and stress (heat shock protein 70 and cortisol) markers that occur during ballan wrasse larval development by relating them to larval stages and feed changes. The real-time PCR data demonstrated that igf1 transcripts rose from 1 day post-hatching (dph) and were no longer detectable 38 dph, whereas igf2 and myostatin transcripts were low and stable until 28 dph, then rose in late larval stages. The biometric and histological data matched the molecular findings, documenting rapid growth and development of the larval digestive tract and assimilation ability. Cortisol was lowest at hatching, it rose slightly at first feeding, and then increased during larval development; a similar trend was detected for hsp70 gene expression. The low cortisol levels found at the earliest larval stages reflect a poor stress-coping ability, a feature that may actually protect larvae from the elevated metabolic demands involved by stress responses and promote faster growth and survival. The present data can be applied to improve the rearing performances of this important cleaner species and reduce captures from the wild. © 2016 John Wiley & Sons Ltd
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