Dissertations / Theses on the topic 'Fish yield'

<p>Melting of frozen water in food products is denoted thawing. The phase change requires energy, and takes place at a constant temperature for pure water. For mixtures of water, fat, protein and ashes (i.e. foodstuffs) this phase change will take place at a gliding temperature. Thawing is physically the opposite process to that of freezing. The heat flow is reversed and instead of extracting heat from the product, heat is directed into it. Although opposite processes, thawing is more difficult to carry out with respect to predictability and controllability. This is due mainly to three aspects:</p><p>1. Increased heat flow resistance as the thawing proceeds.</p><p>2. Reduced temperature difference (ΔT) between product and media.</p><p>3. More difficult to monitor the process and product end temperature accurat</p><p>The food processing industry depends on a continuously and safe supply of raw material, in order to utilise process equipment better, improve production planning and to create stable and secure working environment for the employees. The fish industry is very important for Norway, and its export value (NOK 30,6 billion in 2001¹) is the second highest after oil and higher than gas. The fact that supply of fresh raw material (i.e. fish) often is dependent on seasonal variations, weather conditions, quotes and regulations (governmental and international), has been a great intensive to use frozen raw material in the fish process industry.</p><p>A survey amongst 155 fish processing plants throughout Norway showed that 75 % of them used thawing in their production and further 23% claimed that they would do so in the future. 93 % of the companies that thawed did so in an uncontrolled manner. The challenges in industrial thawing are many:</p><p>• Block frozen products changes size during thawing and are generally more difficult to handle</p><p>• The product texture are temperature dependent</p><p>• Size variations – both single fish and batches</p><p>• Use of both fresh and frozen raw material</p><p>• Company culture</p><p>Thawing by heat transfer through the surface has been studied for three different products; Salmon, Cod and Mackerel. A slightly different approach has been used for these products depending on the raw material availability, industrial needs and relevance.</p>

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2018-04-20T19:26:59Z No. of bitstreams: 1 Nalva_Fritzen_2015.pdf: 1186463 bytes, checksum: bb35877d759f48f8281dbc14e226c99b (MD5)<br>Made available in DSpace on 2018-04-20T19:26:59Z (GMT). No. of bitstreams: 1 Nalva_Fritzen_2015.pdf: 1186463 bytes, checksum: bb35877d759f48f8281dbc14e226c99b (MD5) Previous issue date: 2015-02-27<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>The objective of this study was to analyze the productive performance, the physical and chemical composition and the cost benefit of tilapia production (Oreochromis niloticus) in cages, in three different weight classes (500, 700 and 900g) termination. 24.000 fish were used, with initial weight of 150 ± 5,4 g for analysis of cost of production, over thirty cages of 6 m3 of useful volume. A sample of five fish for cage was harvested for yield performance, including 10% of those steaks were used for chemical analysis. To survey costs and profitability, we used the Operating Cost (Effective and Total), Depreciation, Total Cost and Profit. At the end it was observed that the smaller fish (500g) showed a smaller amount of lipids (1,76%) and visceral (3,69%) and a higher content of ash (1,40%) in the fillet. The best fillet yield and main trunk was found in larger fish (900g), 32,48% and 50,82% respectively. The profitability of production, the average fish (700g) stood out (19,77%).<br>O objetivo neste trabalho foi analisar o desempenho produtivo, a composição físico-química e o custo benefício da produção de tilápias do Nilo (Oreochromis niloticus) em tanques-rede, em três diferentes classes de peso (500, 700 e 900g) de terminação. Foram utilizados 24.000 peixes, com peso inicial de 150±5,4g, para análise de custo da produção, distribuídos em trinta tanques-rede de 6m3 de volume útil. Uma amostra de cinco peixes por tanque foi abatida para o desempenho produtivo, dos quais 10% dos filés obtidos foram utilizados para análise bromatológica. Para o levantamento dos custos e rentabilidade, utilizou-se o Custo Operacional (Efetivo e Total), Depreciação, Custo Total e Lucro. Ao final observou-se que os peixes menores (500g) apresentaram menor quantidade de lipídeos (1,76%) e gordura visceral (3,69%) e, maior teor de matéria mineral (1,40%) no filé. O melhor rendimento de filé e tronco limpo foi encontrado nos peixes maiores (900g), 32,48% e 50,82% respectivamente. Quanto a lucratividade da produção, os peixes médios (700g) se destacaram (19,77%).

The biological characteristics of fisheries stocks that are assessed for management considerations are rarely homogeneous over time or space. However, stock assessment scientists largely ignore this heterogeneity in their models. This thesis addresses the effects of spatial and temporal heterogeneity on stock assessment models using Atlantic Weakfish (Cynoscion regalis) as a case study. First, spatial and temporal variation was incorporated into length-, weight-, and maturity-at-age estimates using mixed-effects models (Chapter Two). The resulting heterogeneous weight and maturity parameters then were applied to per-recruit analyses to examine the sensitivity of biological reference points to spatial and temporal variation in life history attributes (Chapter Three). Mixed-effects life history models incorporating spatial and temporal variation revealed distinct regional and annual trends that were not visible from standard homogeneous models. In several instances, the homogeneous modelling approach produced life history estimates that varied significantly from the spatial and temporal means produced by the heterogeneous models. In some cases, this difference was so great that the homogeneous means were much higher or lower than the heterogeneous means for all regions or years. Minimized AIC statistics revealed that spatially and temporally integrated mixed-effects models were more robust and descriptive of Atlantic Weakfish life history than the standard homogeneous models. Per-recruit and biological reference points derived from these life history estimates in Chapter Three were found to be highly sensitive to spatial and temporal variations in weight parameters. In several cases, reference points used as management targets were so significantly different that ignoring spatial and temporal heterogeneity in Atlantic Weakfish life history would likely cause overfishing and decline of Weakfish in certain regions and years.<br>Master of Science

Made available in DSpace on 2017-07-10T17:48:16Z (GMT). No. of bitstreams: 1 Cinthia Eyng.pdf: 424739 bytes, checksum: 17ff42a1bf54ac742ba44e376d980e11 (MD5) Previous issue date: 2009-03-12<br>Three experiments were carried out aimed to nutricional evaluation of meal from tilapia filleting industrial waste (TM) in broiler chickens feeding. On the first experiment the chemical composition, apparent metabolizable energy (AME), corrected apparent energy (AMEn) and it s coefficients of metabolizability were determined. The total excreta collecting method was used to determinate the energy values, where 60 broiler chicken Cobb, aging 22 days, were shared in a completely randomized design, with six replications and five birds per experimental unit. According to the chemical composition results of TM, it depends of fish specie and meal production process. The AME, AMEn, CAME and CAMEn values to TM were: 3.733 kcal/kg, 3.082 kcal/kg, 78,13 e 64,50, respectively. On the second experiment, the true digestibility coefficients and the values of true amino acid digestibility of TM were determined in cecectomized roosters by the forced feed method. The experiment was analyzed as a complete randomized design with one test ingredient (TM), one fast, six replicates and one rooster per experimental unit. The average values of essential and non essential true amino acids digestibility coefficients, in percentage, were as follows: 92,04 and 87,49. On the experiment III, the performance of broilers feeding with different inclusion levels of TM (0, 2, 4, 6 and 8%) was analyzed. Four hundred and eighty day-old chicks were used in a completely randomized design with five treatments, six replicates and sixteen birds per experimental unit. Weight gain, final weight, feed intake, feed conversion and mortality from 1 to 21 days and 1 to 42 days of age were evaluated. In the end of experimental period the blood parameters (calcium, phosphorus, triglycerides), carcass, breast, thigh, drumstick, wing yield, liver relative weight and percentage of abdominal fat were calculated. Protein and fat deposition rate in breast and legs (thigh/drumstick) were determined. Forty five not trained tasters were used to sensorial analysis of meat. The samples were assessed using the nine-point structured hedonic scale for the characteristics: flavour, taste, color, texture and global quality. The experimental diet cost, economic efficiency index and cost index were calculated on analysis of economic viability. The data analyses showed difference (P<0,05) between inclusion levels of TM and the evaluate characteristics on 21 days of age. Despite of quadratic effect of treatments, the Linear Response Plateau (LRP) model provided the best data fit, the levels of inclusion were estimated in 2,10 and 2,02, which are the plato point for final weight and weight gain, respectively. The LRP was the only model that showed adjustment for feed intake and the level of inclusion was estimated in 1,86, which are the plato point. On the total period (1 to 42 days) the inclusion of 8% of TM in broiler chickens feeding did not affected performance, yield parameters, protein and fat deposition rate on carcass and sensorial quality of meat. Despite of linear increasing on blood triglycerides values, this level of inclusion reduced blood P and Ca values and provided the best economic efficiency.<br>Foram conduzidos três experimentos para avaliação nutricional da farinha de resíduos da indústria de filetagem de tilápias (FT) na alimentação de frangos de corte. No experimento I, foram determinados os valores de composição química, os valores de energia metabolizável aparente (EMA), aparente corrigida (EMAn) e seus coeficientes de metabolizabilidade. Para determinação dos valores energéticos foi utilizado o método da coleta total de excretas, onde 60 aves da linhagem Cobb, com 22 dias de idade foram distribuídas em delineamento inteiramente casualizado, com seis repetições e cinco aves por unidade experimental. De acordo com os resultados encontrados de composição química para a FT constatou-se que as composições dependem da espécie de peixe utilizada e processamento pelo qual a farinha é obtida. Os valores de EMA, EMAn, coeficiente de metabolizabilidade da EMA (CEMA) e coeficiente de metabolizabilidade da EMAn (CEMAn) para FT foram de 3.733 kcal/kg, 3.082 kcal/kg, 78,13 e 64,50, respectivamente. No experimento II, objetivou-se determinar os coeficientes de digestibilidade e valores de aminoácidos digestíveis verdadeiros da FT. Utilizou-se o método da alimentação forçada, com galos adultos cecectomizados, em um delineamento experimental inteiramente casualizado, composto por um alimento-teste (FT) e um jejum, com seis repetições e um galo por unidade experimental. Os coeficientes médios de digestibilidade verdadeira dos aminoácidos essenciais e não-essenciais, em porcentagem, foram, respectivamente, 92,04 e 87,49. No experimento III, foi avaliado o desempenho de frangos de corte alimentados com diferentes níveis de inclusão de FT (0, 2, 4, 6 e 8%). Foram utilizados 480 pintos de um dia, da linhagem Cobb, distribuídos num delineamento experimental inteiramente casualizado, com cinco tratamentos, seis repetições e 16 aves por unidade experimental. As características avaliadas foram ganho de peso, peso final, consumo médio de ração, conversão alimentar, mortalidade de 1 a 21 dias e 1 a 42 dias de idade. Ao final do período experimental foi mensurado os parâmetros sanguíneos (cálcio, fósforo e triglicerídeos), rendimento de carcaça, peito, coxa, sobrecoxa, asa, peso relativo do fígado e percentual de gordura abdominal. Determinou-se a taxa de deposição de proteína e gordura do peito e pernas (coxa/sobrecoxa). A análise sensorial da carne foi realizada por 45 provadores não treinados. As amostras foram avaliadas utilizando a escala hedônica estruturada de nove pontos para as seguintes características: aroma, sabor, cor, textura e qualidade global. Dentro da análise da viabilidade econômica foram calculados os custos das dietas experimentais, o índice de eficiência econômica e o índice de custo. Observou-se diferença (P<0,05) dos níveis de inclusão da FT sobre as características avaliadas aos 21 dias de idade, sendo que na análise de regressão para a fase de 1 a 21 dias, embora tenha variado de forma quadrática, o modelo Linear Response Plateau (LRP) se ajustou melhor aos dados de peso final e ganho médio de peso, estimando a ocorrência de platô a partir do nível de inclusão de 2,10 e 2,02, respectivamente. Para consumo médio de ração o modelo LRP foi o único que se ajustou aos dados, estimando a ocorrência de platô a partir do nível de inclusão de 1,86. No entanto, considerando o período total (1 a 42 dias) pode-se incluir 8% de FT nas rações de frangos de corte, sem prejuízo para o desempenho produtivo, parâmetros de rendimento, deposição de gordura e proteína na carcaça e qualidade sensorial da carne. Apesar do aumento linear dos valores de triglicerídeos sanguíneo, este nível de inclusão reduziu os valores de P e Ca sanguíneo e proporcionou o melhor desempenho econômico

The main purpose of LARAMED project (LAboratoty of Radioisotopes for MEDicine), founded at LNL-INFN, is the R&D on cyclotron production of conventional, such as Tc-99m (TECHN-OSP projects), and emerging, such as Cu-67 (COME project), metallic medical radioisotopes. The aim of my PhD has been the development, optimization and automation of post-irradiation target processing systems, enabling to recover in high yield highly pure radioisotopes (RI), one of the most critical steps in the RI cyclotron production. The possibility of a reactor-produced molybdenum-99 shortage, used as parent nuclide of in 99Mo/99m Tc generators, is still a potential scenario. The direct cyclotron-production of Tc-99m through the (p,2n) reaction on a Mo-100 target seemed to be a reliable solution. In the framework of TECHN-OSP project, a technology for enabling the in-hospital cyclotron self-production of Tc-99m, in order to afford the availability of the most used radiometal in diagnostic applications in case of shortages, has been developed. The Tc-99m cyclotron-production optimization included the design of a solid target, the development of an automatic module for target processing and enriched target material recovery study. In this thesis, the description of Tc-99m production experiments, performed in collaboration with the Sant’Orsola Hospital in Bologna, and the development of the automatic module for target processing, are well detailed. During my PhD I had the opportunity to collaborate with the Canadian research group at TRIUMF (Vancouver, CA), also working on Tc-99m cyclotron-production, by contributing at the optimization and automation of molybdenum target dissolution and purification procedure of cyclotron-produced Tc-99m. In this thesis a comparison between the two developed, Italian and Canadian, target processing setup is also reported. Alongside that, I have collaborated to COME project whose purpose is the evaluation of the cyclotron production efficiency of Cu-67, a particularly interesting RI for its application in “theranostics”. The large scale cyclotron-production of this RI is still a poorly studied key point. In order to define the Cu-67 best cyclotron-production route, we focused our attention on unknown cross-section measurement of nuclear reactions on a Zn-70 target (35-70MeV energy range). Essential for this project was the development and optimization of a high yield separation and purification procedure of Cu-67 from the Zn-70 bulk and the co-produced Ga-67 contaminant that, having the same γ-lines of Cu-67 (both decay to Zn-67 with similar half-lives), poses a serious issue for the determination of the activity of Cu-67. The description of the experiments, performed in collaboration with ARRONAX, is reported in this thesis. Finally, the clinical needs of larger amount of the PET radiometal generator-produced Ga-68 prompted TRIUMF Life Sciences division to investigate Ga-68 cyclotron-production from liquid target since it is based on the existing medical-cyclotron network and technology. This technique will improve the availability of Ga-68 in hospitals housing an appropriate cyclotron by making them independent self-producers. Since the major problem affecting liquid targets is the contamination with radioactive/stable metals (e.g. iron) coming from the dissolution of some material from vacuum isolation or target body components during the irradiation, a separation and purification procedure together with a semi-automatic system, particularly focused on the purification of Ga-68 from Zn and Fe, have been developed. The main purpose is to obtain a final product suitable for medical use and to enable radiolabeling and in-vivo imaging studies with cyclotron produced 68Ga-DOTATOC.<br>Il progetto LARAMED (LAboratoty of Radioisotopes for MEDicine), fondato presso i LNL-INFN, ha come scopo l’R&D per la produzione da ciclotrone di radioisotopi metallici convenzionali, come il Tc-99m (progetto TECHN-OSP, ed emergenti, come il Cu-67 (progetto COME), per uso medicale. L'obiettivo del mio dottorato di ricerca è stato lo sviluppo, ottimizzazione e automazione di sistemi di processamento dei target irraggiati al fine di estrarre, in alta resa e purezza, il radioisotopo (RI) di interesse, uno dei passaggi più critici nella produzione da ciclotrone dei RI per la medicina. La possibilità di un’ulteriore crisi di produzione da reattori nucleari di Mo-99, nuclide genitore nei generatori Mo-99/Tc-99m, è ancora uno scenario possibile. La produzione diretta di Tc-99m da ciclotrone per mezzo della reazione nucleare Mo-100(p,2n) sembra essere una soluzione alternativa affidabile. Nell’ambito del progetto TECHN-OSP è stata sviluppata una tecnologia in grado di rendere le radiofarmacie delle Medicine Nucleari, che ospitano un ciclotrone appropriato, indipendenti nella produzione di Tc-99m al fine di sopperire ad ogni eventuale carenza nell’approvvigionamento dei generatori. L’ottimizzazione della produzione ha previsto la progettazione di un target, lo sviluppo di un modulo automatico per il processamento del target e lo studio del recupero del materiale arricchito costituente il target stesso. In questa tesi sono descritti i test di produzione di Tc-99m, eseguiti in collaborazione con l'ospedale Sant'Orsola di Bologna, ed in particolare lo sviluppo di un modulo automatico di processamento del target. Nel corso del dottorato, ho avuto l'opportunità di collaborare con il gruppo di ricerca canadese al TRIUMF (Vancouver, CA), anch’esso coinvolto nell’ottimizzazione della produzione di Tc-99m da ciclotrone, contribuendo all'ottimizzazione e automazione delle procedure di dissoluzione e purificazione di Tc-99m da target di Mo-100. In questa tesi viene anche riportato un confronto tra i due sistemi di processamento target da me sviluppati, in Italia e in Canada. Parallelamente ho collaborato al progetto COME il cui obiettivo risiede nella valutazione dell'efficienza di produzione di Cu-67 da ciclotrone, RI particolarmente interessante per le sue applicazioni in “teranostica”. La produzione da ciclotrone su larga scala di questo RI è ancora un punto chiave scarsamente studiato. Al fine di definire la migliore via di produzione di Cu-67, abbiamo focalizzato l’attenzione su misure di sezioni d’urto inedite (target Zn-70, protoni incidenti di energie 35-70MeV). Essenziale per questo progetto è stato lo sviluppo di un processo altamente efficiente di separazione di Cu-67 dal target e dal Ga-67, coprodotto che, avendo le stesse linee γ del Cu-67, crea problemi nella determinazione dell'attività di Cu-67. La descrizione degli esperimenti, eseguita in collaborazione con ARRONAX, è riportata in questa tesi. Infine, le esigenze cliniche di una maggiore quantità di Ga-68, RI PET attualmente prodotto da generatore Ge-68/Ga-68, hanno spinto il gruppo di ricerca del TRIUMF a studiare la produzione di Ga-68 da ciclotrone a partire da un target liquido di Zn-68, al fine di migliorare la disponibilità di Ga-68 negli ospedali che ospitano un ciclotrone appropriato rendendoli produttori indipendenti. Poiché il problema principale che colpisce la produzione da target liquido è la contaminazione da metalli (es. Fe) provenienti dalla degradazione di alcuni componenti del corpo del target, è stata sviluppata una procedura di separazione e purificazione del Ga-68 da Zn e Fe. Lo scopo principale è quello di ottenere un prodotto finale adatto all’uso medico e di consentire la radio-marcatura di (Ga-68)-DOTATOC e studi di imaging in vivo con Ga-68 prodotto da ciclotrone.

Unrelenting advances in the field of nanoscience are fostering the progress in diverse research fields, ranging from light-emitting to medicine and diagnostics, from energy conversion to communication technologies. Besides representing the most paradigmatic example of nanoscience, semiconductor quantum dots (QDs) avowedly brought revolutions in many of the research fields mentioned above. Nowadays, some QDs-based devices and applications reported efficiencies almost as good as current state-of-the-art technologies. The founding concept of QDs is the application of quantum confinement effects on excitons, i.e., the main players of optical properties in bulk semiconductors. Among the wealth of ensuing properties, the size- and shape- tunability of the electronic excitations and increased coupling with light field aroused much interest. Also, the colloidal approach endows QDs with high processability and low cost, thereby encouraging their implementation in existing technologies and extending their impact to other fields. Howbeit, despite three decades of investigations, the bottom line has not been reached yet, and researchers are still delving deeper into the photophysics of these nanosystems. Though many of the low hanging fruit of QDs have been harvested, higher-lying ones seem to be even more succulent. This thesis deals with the quest for highly performing nanostructures, as a prerequisite for some high impact optoelectronic applications, e.g., QD-Lasers and QD-Solar Cells. Within this framework, the struggle against fast Auger recombinations and trapping of either hot carriers or cold excitons was addressed mainly by sophisticated core/shell technologies. Thus, the first part of the thesis reports how tuning different shell parameters (e.g., the smoothness of the interface potential, the height of the confining potential, and the interfacial strain) it is possible to exert control on these detrimental recombination processes. Though often disregarded, even the role of organic capping ligand is reconsidered in promoting the outcoupling of QDs excited states and addressing their interaction. Besides the useful and technologically relevant advice gathered within these studies, the primary inheritance of the first part is the comprehensive photophysical scenario, portrayed by a phenomenological model that successfully describes many aspects of the exciton dynamics in QDs. This amount of knowledge was capitalized in the second part of this thesis, dealing with the quest for novel materials, potentially outpacing conventional CdSe-based QDs. Perovskite-based QDs reported promising results, whereas some pitfall in the conventional characterization of carbon-based QDs were discovered. The rationalization of both nature and dynamics of this materials is expected to expedite their development as alternative (and potentially superior) technologies concerning those studied in the first part.<br>---

The rheology of soft-flowing systems, such as concentrated emulsions, foams, gels, slurries, colloidal glasses and related complex fluids, has a larger and larger impact in modern science and engineering. Much of the fascination of these systems stems from the fact that they do not fall within any of three basic states of matter, gas-liquid-solid, but live rather on a moving border between them. To understand the flow mechanism, it is necessary to have a look at the micro-scale dynamics of its constituents (i.e, droplets for emulsions, bubbles for foams, blobs for gels, etc.). In fact, in these fluids, the flow occurs via successive elastic deformations and plastic rearrangements, which create fragile regions enhancing the “fluidization” of the material. Despite the fluidization of Soft Glassy Materials (SGMs) is strongly affected by the surface roughness, the role played by the density, the orientation and the periodicity of rough elements has not been quantitatively addressed so far. In fact, predict and control the flow of SGMs is particularly important for an ample variety of technological applications from food to pharmaceutical industries. In this work, we study the flow of concentrated emulsions in microfluidic channels, one wall of which is patterned with micron-size grooves with different patterns. Using equally spaced grooves, we find a scaling law describing the roughness-induced fluidization as a function of the density of the grooves, thus fluidization can be predicted and quantitatively regulated. Furthermore, we quantitatively report the existence of two physically different scenarios. When the gap is large, compared to the droplets in the emulsion, the droplets hit the solid obstacles and easily escape scrambling with their neighbors. Conversely, as the gap spacing is reduced, droplets get trapped inside, creating a “soft roughness” layer, i.e., a complementary series of deformable posts. Introducing an asymmetrical micro-roughness (herringbone pattern), the flow presents, in turn an asymmetric behavior. The emulsion flows faster in the same direction of the herringbone groove respect when it flows in the opposite direction. Our experimental observations are suitably complemented and confirmed by lattice Boltzmann simulations. These numerical simulations are key to highlight the change in the spatial distribution of the plastic rearrangements caused by surface roughness and to elucidate the micro-mechanics of the roughness induced fluidization.<br>La reologia dei sistemi soffici, quali emulsioni concentrate, schiume, gel, fanghi, vetri colloidali ha un grande impatto in ambito scientifico e ingegneristico. Gran parte del fascino di questi sistemi deriva dal fatto che essi non si collocano in nessuno dei tre stati base della materia, gas-liquido-solido, ma si posizionano ai limiti di ciascuna di esse. Per comprendere il meccanismo con il quale questi materiali scorrono è necessario osservare la dinamica dei loro costituenti (gocce per le emulsioni, bolle per le schiume, etc.) su scala microscopica. Infatti, il flusso è caratterizzato da una successione di deformazioni elastiche e riarrangiamenti plastici. Questi, creano delle regioni a maggior ``fluidità” in cui il materiale scorre. Il processo di fluidizzazione degli Soft Glassy Materials (SGMs) è fortemente influenzato dalla presenza di rugosità sulla superficie con cui sono a contatto, tuttavia il ruolo giocato dalla periodicità, l’orientazione e la forma degli elementi che costituiscono questa rugosità non è ancora stato del tutto compreso. Infatti, prevedere e controllare il flusso di questi SGMs è fondamentale in numerose applicazioni tecnologiche che vanno dall'industria alimentare a quella farmaceutica. In questo lavoro di tesi abbiamo studiato il flusso di emulsioni concentrate in canali microfluidici. Questi ultimi presentavano una rugosità controllata, su scala micrometrica, posizionata sul fondo del canale. Utilizzando come micro-rugosità una sequenza di ``grooves" (solchi) posti ortogonalmente al flusso, abbiamo osservato che la fluidizzazione indotta dipende dalla densità e dalla periodicità dei solchi. Ne consegue che, la fluidizzazione può essere controllata e regolata in modo quantitativo agendo sulla spaziatura di questi solchi. Inoltre, abbiamo osservato l’esistenza di due scenari con meccaniche di riarrangiamento differenti. Quando la spaziatura dei solchi è grande, rispetto alla dimensione delle gocce, queste colpiscono gli ostacoli e facilmente riarrangiano andando ad interagire con altre gocce vicine. Al contrario, riducendo lo spazio tra i solchi, le gocce ve ne rimangono intrappolate creando uno strato di ``rugosità soffice" creando a loro volta una nuova serie di ostacoli deformabili. Con l’introduzione di rugosità dalla geometria asimmetrica (a spina di pesce) abbiamo osservato che, anche il flusso all’interno del canale presenta un comportamento non simmetrico. L’emulsione, infatti, scorre più velocemente nello stesso verso della spina di pesce, rispetto a quando scorre nel verso opposto. Le nostre osservazioni sperimentali sono e supportate e confermate da simulazioni lattice Boltzmann. Queste simulazioni, cruciali per evidenziare le variazioni nella distribuzione spaziale dei riarrangiamenti plastici, sono un potente mezzo per studiare e comprendere le micro-dinamiche che portano alla fluidizzazione del materiale.

Interest of in vitro methods has grown exponentially throughout the years especially due to the ethical problems surrounding the use of animals in in vivo studies. Cell-based assays for the isolation of hepatocytes using enzymatic methods have been credited in fish toxicology and play a substantial role in the propagation of in vitro methodologies, having been implemented with various degrees of success to a variety of fish species, especially in freshwater species. Isolated hepatocytes provide an optimal system to study the role of hepatic metabolism in the activation of environmental pollutants, such as polycyclic aromatic hydrocarbons (PAHs). For these reasons, the present work focused on the optimization of the isolation of two marine fish hepatocytes (P. maxima and S. aurata) using two enzymatic methods of isolation, pancreatin digestion and 2-step collagenase perfusion, for posterior validation in cytotoxicity testing. The two main parameters studied were cell viability and yield after isolation. Cell viability was assessed via the Trypan blue exclusion test and cell yield was counted with the use of a hemocytometer. The pancreatin method accounted for better overall cell yield and also produced the highest viability out of all experiments. Pancreatin digestion isolations also produced purer cultures, largely with 100% viability, which was made possible by way of modifications made during isolations, such as the use of histopaque for blood cell separation and addition of another smaller mesh filter (60 μm) to achieve better purity and fewer cell debris, respectively. A cytotoxicity assay was also performed using the MTT colorimetric assay to access cell viability after contamination with Phenanthrene and Benzo[b]fluoranthene, two polycyclic aromatic hydrocarbons (PAHs) of interest for cytotoxicity studies. Viabilities after contamination with both compounds only exhibited small variability demonstrating no dose-response curve, likely due to factors such as intra-species individual variability and the precipitation of contaminants in the highest concentrations, which might have affected absorbance readings and could cause misleading cell viabilities. Therefore, we call for further studies to access the cytotoxic effect on P. maxima and S. aurata by Phe and B[b]f. In conclusion, the research showed that the best method for isolation was the pancreatin digestion and the marine fish primary hepatocyte cultures obtained are suitable for the application in cytotoxicity assays.

Population escalation in the developing world has been associated with increased poverty, food insecurity and environmental degradation. The situation in Rwanda, with 2.82% annual population increase is no exception. The objective of the present study was to investigate an innovative integrated system of sustainable production suitable for resource-poor rural farmers, the Integrated Rabbit–Fish–Rice (IRFR) system. The study was targeted towards contributing to Rwanda government’s goals of eradicating extreme poverty and hunger, enhancing food security as well as abating environmental degradation. Three experiments, were carried out between 2008 and 2010, and designed to fertilise pond water with rabbit droppings and boost phytoplankton production. We also used results from our previous study, conducted in 2005 in the same ponds and under similar experimental conditions, especially rabbit and fish species and age, fishpond dimensions, as well as the fertilisation mode. The fishpond effluent was re-used to irrigate rice fields rather than being discharged into the environment. This study advocated the potential adaptation of rabbits to wetland conditions and the role of rabbit droppings as organic fertilisers in providing a better environment for fish production. On-farm resources, including rabbit droppings, were the main source of nutrients in the system. The analysis of nutrient flow revealed that 27% N and 79% P of the total nitrogen and phosphorus in fertilizing input in fishponds were supplied by rabbit droppings only. Nile tilapia Oreochromis niloticus were able to recover 18.5–37.6% N and 16.9–34.3% P of the total nitrogen and phosphorus inputs, the rest being accumulated in the pond water and the sediment, making them useful for soil fertilisation. The re-use of nutrient-rich effluent in rice irrigation increased rice production, allowing a successful complete substitution of inorganic fertilisers. The irrigation also reduced environmental pollution as the water seeping through rice field was 31.8 and 83.3% less concentrated in total phosphorus and nitrite pollutants, respectively, than was the pond water. Economically, the IRFR generated up to 597% net return over that of the rice inorganically fertilised, thereby substantiating the sustainability of the system. Overall, it is concluded that the IRFR system works well, is readily applicable, and capable of high, diversified, and sustainable production on limited land. As such, the study demonstrates the potentialities of the IRFR system to contribute successfully to poverty reduction, and the enhancement of food security in rural areas. The system promises economic returns and is environmental friendly. The research recommends the optimal range of rabbit density, that is, 800–1200 rabbits per hectare of pond, and the best fish stocking density, that is, 3 fish.mˉ², for a sustainable IRFR culture system.<br>Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

The relationship between spawning stock biomass (SSB) and 3 spatial distribution metrics (SDMs), measuring range, concentration, and density, using fisheries independent survey data for 10 demersal Northwest Atlantic fish populations (9 species), show metrics of density offer the best correlate of SSB. The concave, positive relationship between high density area (HDA) and SSB indicates that a decline in HDAs beyond a spatial threshold is associated with disproportionately large SSB declines in 6 populations. HDAs might indicate highly productive areas and/or positive fitness consequences, enhancing the ability of individuals to successfully spawn, locate prey, and evade predators. HDAs can help to assess the status of a population’s spatial structure and serve as a spatial reference point. By comparing spatial reference point locations relative to existing biomass reference points (based on MSY), scenarios are described wherein spatial reference points contribute to biomass reference points and to a precautionary approach to fisheries management.

One of the most important problems to consider in particle accelerators is Synchrotron Radiation (SR). SR causes significant problems like heat load on the accelerator walls, photon stimulated desorption, production of secondary electrons (electron cloud effect) and consequently beam instability (coupled bunch and single bunch instabilities). Thus, it is very important to have an experimental characterization of properties of technical surfaces, in particular Reflectivity and Photo Yield (PY). PY, also known as quantum efficiency, measures the number of electrons generated per incident photon as a function of energy and incidence angle. Such material properties are essential ingredients to calculate single and multi bunch instabilities, vacuum behaviour, e—cloud instabilities, etc. There is an increasing demand from the accelerator community towards the availability of experimental data taken from representative materials and in conditions as close as possible to the one that will actually occur in the machine. In the FCC-hh contest it has been highlighted that high reflectivity could be advantageous for reducing SR induced heat load in cold dipoles. Carbon Coating of smooth vacuum chamber surfaces was suggested as a mean to reduce the heat load in cold part of the machine, by forward reflecting most SR and its deposited power towards ad hoc designed room temperature absorbers. In these Ph.D. a systematic experimental campaign has been launched and is still ongoing to study Reflectivity and Photo Yield. We identified the Optics Beamline and the Reflectometer endstation in Berlin (HZB BESSY-II), as an ideal tool to get realistic experimental values to be used in most relevant simulations. Access to this beamtime has been granted trough beamtime accepted proposals. The first experimental results will be presented and discussed here. We studied reflectivity and photo yield in UV and XUV range (from 35 eV to 1800 eV) at grazing angles (0.25, 0.5 and 1 degree), using copper samples as targets, differently prepared. We studied also the effect of Carbon Coating on reflectivity and PY.