982 resultados para leaching and dissolution experiment
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Octopus vulgaris on-growing in floating cages is a promising activity implemented in Spain at industrial level, with productions of 16-32 tons/year from 1998. Nevertheless, some aspects of the culture system need to be evaluated to warrantee its profitability. In the present study two rearing systems and two dietary treatments were evaluated. Individual and group rearing, in PVC net compartments and floating cages respectively, were compared under two dietary treatments. One diet was composed by bogue, supplied as ?discarded? species from local fish farms, and the other was based on a 40-60% discarded bogue-crab Portunus pelagicus. All octopuses were PIT-tagged and the experiment lasted two months. Animals were sampled once throughout the experimental period and absolute growth rate (AGR, g./day) and mortality (%) were calculated. AGR of group rearing was above 30 g./day, however individual rearing showed 100% survival so biomass increment was higher. On the other hand, males grew more than females regardless of dietary treatment.
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Programa de Doctorado: Fuentes, Métodos e Historiografía para la Investigación en el Mundo Atlántico
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Abstract This PhD thesis focuses on two projects carried out by Oswald Mathias Ungers in the city of Trier. More specifi cally, this study focuses on the relationship between composition principles, architectural forms, historical context and the nature of the city where these buildings have been built. The works carried out by Ungers in Trier are unique experiences - if taken in this master’s works context - and each one of them refl ects - in its specifi c project and architectural composition theme - the results - in terms of design - of a complex research on the fundamentals of architecture carried out by Ungers in more than fi ve decades of his activity. The theoretical and compositional experiment aspect is one of the main subjects to defi ne these buildings in terms of architecture. This aspect is so crucial that it is possible to consider them as an example of radical and specifi c experiences, referred to a specifi c place and based on a specifi c theoretical corpus. More specifi cally, this study focuses on the design activity carried out by Ungers in this city, mainly between the 80s and 90s and in the fi rst decade of the 21st century. It puts forward an interpretation that does not only defi ne the essential features, elements and questions lying behind these two architectures, but fi rst and foremost analyzes the theoretical, methodological and compositional relationship between Ungers and Trier, his adopted city. An increasingly closer relationship between the architect and his city highlights the wider relationship network established between the place and the projects carried out by Ungers in this city and makes it possible to understand the importance of Trier in the work of this architect, in his education and in his way to see, think and make architecture. The projects analyzed - the Thermen am Forum Museum (1988-1996) and the Kaiserthermen entrance hall (2003-2007) - were analyzed in terms of their architectural composition in an attempt to highlight the poetry of these architectures and to fi nd out their progressive, rational - and therefore transmissible - character. This study is an attempt to assess and unveil the compositional themes characterizing these projects while detecting the compositional principles lying behind the works and verifying the design process through which such principles were translated into architecture. Looking at these works as architectural composition examples makes it possible to clarify Ungers’ hermeneutic relationship established with the city’s history and structure. More specifi cally, the main subject of this thesis is the relationship between the architect, his city and history in the architectural solutions offered by two exemplary case studies, which were both built and placed in the historical city center of Trier and both connected with the ancient core of the city. The Thermen am Forum Museum and the Kaiserthermen entrance hall projects are - though being developed at different times of Ungers’ architectural life and though being extremely different in terms of approach to their context, due to their architectural image - two works that can be compared with the historical heritage of the city and this makes them ideal examples of the relationship between architectural forms, history and environment.
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The evolution of a sub-family of south-american freshwater catfishes has created a great diversification of its representants into a huge number of species, usually members of characteristic mimicry communities. After the work of Alexandrou (Alexandrou, 2011) on the phylogeny of the group that discovered the existence of more deep divisions, from the taxonomic point of view, of the sub-family, even from the ecological point of view, I tried to reconfirm these statements from the ethological point of view, settling watching and recording sessions and an experiment that could show their interactions on the environment by observing their substrate mixing action.
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La presente tesi di dottorato ha come argomento la produzione d’idrogeno per via fermentativa sfruttando il metabolismo anaerobico di particolari batteri estremofili del genere Thermotoga. In questo lavoro, svolto in seno al progetto Bio-Hydro, sfruttando reattori batch da 116 mL, è stato selezionato il ceppo migliore di Thermotoga fra i quatto ceppi testati: T. neapolitana. Una volta individuato il candidato batterico migliore è stato individuato il valore ottimale di pH (8.5 a t.amb) per la produzione d’idrogeno. Un intenso lavoro è stato svolto sul medium di coltura permettendone la minimizzazione e rendendolo così economicamente sostenibile per il suo utilizzo nel reattore da 19L; in questo caso il glucosio è stato completamente sostituito con due sottoprodotti agroindustriali individuati in precedenza, il melasso di barbabietola e il siero di latte. Sono stati poi eliminati i gravosi micronutrienti e le vitamine. È stata sfruttata la capacità di T. neapolitana di produrre biofilm e sono stati testati 4 diversi supporti in vetro sinterizzato e ceramici, tali test hanno permesso di individuare Biomax come supporto migliore. Sono stati svolti studi sul metabolismo di T. neapolitana volti ad individuare le concentrazioni inibenti di ogni substrato testato, l’inibizione da prodotto (idrogeno) e l’inibizione da ossigeno. Tutte queste prove hanno dato le conoscenze di base per la conduzione di esperienze su reattore da 19L. L’innovativo reattore di tipo SPCSTR è stato interamente studiato, progettato e costruito presso il DICMA. dell’Università di Bologna. La conduzione di esperienze batch su SPCSTR ha dato la possibilità di verificare il funzionamento del nuovo tipo d’impianto. Presso il Wageningen UR (NL), è stata svolta la selezione del miglior ceppo di Caldicellulosisruptor fra 3 testati e del miglior supporto per la produzione d’idrogeno; è stato poi costruito testato e condotto in continuo l’innovativo reattore CMTB.
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Gli avvenimenti politico-istituzionali degli ultimi anni hanno determinato un vivace dibattito sulla questione dei cc.dd. “governi del Presidente”, con cui si suole far riferimento ad Esecutivi il cui procedimento di formazione e le cui crisi registrano un interventismo del Presidente della Repubblica superiore a quello richiesto e/o consentito dal dettato costituzionale. Obiettivo dell’elaborato è duplice: fornire un tentativo definitorio della categoria “governi del Presidente”, nonché valutare la compatibilità di questa con la forma di governo parlamentare, soprattutto in considerazione dei recenti sviluppi delle dinamiche politico-istituzionali italiane. Sulla base di questo presupposto, nel presente lavoro si procede a una ricostruzione dell’evoluzione della prassi e delle consuetudini costituzionali in merito all’esercizio dei poteri presidenziali nella gestione delle crisi di governo, con particolare riferimento al procedimento di formazione dell’Esecutivo. La tesi si presenta articolata in due parti, corrispondenti a due differenti periodi storici (cc.dd. Prima e Seconda Repubblica), organizzate per capitoli, relativi alle principali fasi di evoluzione del sistema politico attraversate nel corso della storia della Repubblica. Questa scelta si giustifica in ragione del fatto che il modus operandi del Presidente della Repubblica risulta fortemente condizionato dai mutamenti del contesto politico-istituzionale. Nei singoli paragrafi, dedicati ai presidenti, vengono trattati l’elezione del Presidente, le modalità di formazione dei governi nominati, nonché ulteriori temi la cui disamina è stata ritenuta opportuna allo scopo di fornire una contestualizzazione più adeguata dell’analisi svolta (utilizzo del potere di esternazione e di scioglimento delle Camere, gestione delle attività di politica interna e politica estera, principali avvenimenti dei periodi storici considerati, e così via).
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In order to reduce the costs of crystalline silicon solar cells, low-cost silicon materials like upgraded metallurgical grade (UMG) silicon are investigated for the application in the photovoltaic (PV) industry. Conventional high-purity silicon is made by cost-intensive methods, based on the so-called Siemens process, which uses the reaction to form chlorosilanes and subsequent several distillation steps before the deposition of high-purity silicon on slim high-purity silicon rods. UMG silicon in contrast is gained from metallurgical silicon by a rather inexpensive physicochemical purification (e.g., acid leaching and/or segregation). However, this type of silicon usually contains much higher concentrations of impurities, especially 3d transition metals like Ti, Fe, and Cu. These metals are extremely detrimental in the electrically active part of silicon solar cells, as they form recombination centers for charge carriers in the silicon band gap. This is why simple purification techniques like gettering, which can be applied between or during solar cell process steps, will play an important role for such low-cost silicon materials. Gettering in general describes a process, whereby impurities are moved to a place or turned into a state, where they are less detrimental to the solar cell. Hydrogen chloride (HCl) gas gettering in particular is a promising simple and cheap gettering technique, which is based on the reaction of HCl gas with transition metals to form volatile metal chloride species at high temperatures.rnThe aim of this thesis was to find the optimum process parameters for HCl gas gettering of 3d transition metals in low-cost silicon to improve the cell efficiency of solar cells for two different cell concepts, the standard wafer cell concept and the epitaxial wafer equivalent (EpiWE) cell concept. Whereas the former is based on a wafer which is the electrically active part of the solar cell, the latter uses an electrically inactive low-cost silicon substrate with an active layer of epitaxially grown silicon on top. Low-cost silicon materials with different impurity grades were used for HCl gas gettering experiments with the variation of process parameters like the temperature, the gettering time, and the HCl gas concentration. Subsequently, the multicrystalline silicon neighboring wafers with and without gettering were compared by element analysis techniques like neutron activation analysis (NAA). It was demonstrated that HCl gas gettering is an effective purification technique for silicon wafers, which is able to reduce some 3d transition metal concentrations by over 90%. Solar cells were processed for both concepts which could demonstrate a significant increase of the solar cell efficiency by HCl gas gettering. The efficiency of EpiWE cells could be increased by HCl gas gettering by approximately 25% relative to cells without gettering. First process simulations were performed based on a simple model for HCl gas gettering processes, which could be used to make qualitative predictions.
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Ziel dieser Arbeit war der Aufbau und Einsatz des Atmosphärischen chemischen Ionisations-Massenspektrometers AIMS für boden- und flugzeuggetragene Messungen von salpetriger Säure (HONO). Für das Massenspektrometer wurden eine mit Gleichspannung betriebene Gasentladungsionenquelle und ein spezielles Druckregelventil entwickelt. Während der Instrumentenvergleichskampagne FIONA (Formal Intercomparisons of Observations of Nitrous Acid) an einer Atmosphären-Simulationskammer in Valencia (Spanien) wurde AIMS für HONO kalibriert und erstmals eingesetzt. In verschiedenen Experimenten wurden HONO-Mischungsverhältnisse zwischen 100 pmol/mol und 25 nmol/mol erzeugt und mit AIMS interferenzfrei gemessen. Innerhalb der Messunsicherheit von ±20% stimmen die massenspektrometrischen Messungen gut mit den Methoden der Differenziellen Optischen Absorptions-Spektrometrie und der Long Path Absorption Photometrie überein. Die Massenspektrometrie kann somit zum schnellen und sensitiven Nachweis von HONO in verschmutzter Stadtluft und in Abgasfahnen genutzt werden.rnErste flugzeuggetragene Messungen von HONO mit AIMS wurden 2011 bei der Messkampagne CONCERT (Contrail and Cirrus Experiment) auf dem DLR Forschungsflugzeug Falcon durchgeführt. Hierbei konnte eine Nachweisgrenze von < 10 pmol/mol (3σ, 1s) erreicht werden. Bei Verfolgungsflügen wurden im jungen Abgasstrahl von Passagierflugzeugen molare HONO zu Stickoxid-Verhältnisse (HONO/NO) von 2.0 bis 2.5% gemessen. HONO wird im Triebwerk durch die Reaktion von NO mit OH gebildet. Ein gemessener abnehmender Trend der HONO/NO Verhältnisse mit zunehmendem Stickoxid-Emissionsindex wurde bestätigt und weist auf eine OH Limitierung im jungen Abgasstrahl hin.rnNeben den massenspektrometrischen Messungen wurden Flugzeugmessungen der Partikelsonde Forward Scattering Spectrometer Probe FSSP-300 in jungen Kondensstreifen ausgewertet und analysiert. Aus den gemessenen Partikelgrößenverteilungen wurden Extinktions- und optische Tiefe-Verteilungen abgeleitet und für die Untersuchung verschiedener wissenschaftlicher Fragestellungen, z.B. bezüglich der Partikelform in jungen Kondensstreifen und ihrer Klimawirkung, zur Verfügung gestellt. Im Rahmen dieser Arbeit wurde der Einfluss des Flugzeug- und Triebwerktyps auf mikrophysikalische und optische Eigenschaften von Kondensstreifen untersucht. Unter ähnlichen meteorologischen Bedingungen bezüglich Feuchte, Temperatur und stabiler thermischer Schichtung wurden 2 Minuten alte Kondensstreifen der Passagierflugzeuge vom Typ A319-111, A340-311 und A380-841 verglichen. Im Rahmen der Messunsicherheit wurde keine Änderung des Effektivdurchmessers der Partikelgrößenverteilungen gefunden. Hingegen nehmen mit zunehmendem Flugzeuggewicht die Partikelanzahldichte (162 bis 235 cm-3), die Extinktion (2.1 bis 3.2 km-1), die Absinktiefe des Kondensstreifens (120 bis 290 m) und somit die optische Tiefe der Kondensstreifen (0.25 bis 0.94) zu. Der gemessene Trend wurde durch Vergleich mit zwei unabhängigen Kondensstreifen-Modellen bestätigt. Mit den Messungen wurde eine lineare Abhängigkeit der totalen Extinktion (Extinktion mal Querschnittsfläche des Kondensstreifens) vom Treibstoffverbrauch pro Flugstrecke gefunden und bestätigt.
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Stratosphärische Partikel sind typischerweise mit dem bloßen Auge nicht wahrnehmbar. Dennoch haben sie einen signifikanten Einfluss auf die Strahlungsbilanz der Erde und die heteorogene Chemie in der Stratosphäre. Kontinuierliche, vertikal aufgelöste, globale Datensätze sind daher essenziell für das Verständnis physikalischer und chemischer Prozesse in diesem Teil der Atmosphäre. Beginnend mit den Messungen des zweiten Stratospheric Aerosol Measurement (SAM II) Instruments im Jahre 1978 existiert eine kontinuierliche Zeitreihe für stratosphärische Aerosol-Extinktionsprofile, welche von Messinstrumenten wie dem zweiten Stratospheric Aerosol and Gas Experiment (SAGE II), dem SCIAMACHY, dem OSIRIS und dem OMPS bis heute fortgeführt wird. rnrnIn dieser Arbeit wird ein neu entwickelter Algorithmus vorgestellt, der das sogenannte ,,Zwiebel-Schäl Prinzip'' verwendet, um Extinktionsprofile zwischen 12 und 33 km zu berechnen. Dafür wird der Algorithmus auf Radianzprofile einzelner Wellenlängen angewandt, die von SCIAMACHY in der Limb-Geometrie gemessen wurden. SCIAMACHY's einzigartige Methode abwechselnder Limb- und Nadir-Messungen bietet den Vorteil, hochaufgelöste vertikale und horizontale Messungen mit zeitlicher und räumlicher Koinzidenz durchführen zu können. Die dadurch erlangten Zusatzinformationen können verwendet werden, um die Effekte von horizontalen Gradienten entlang der Sichtlinie des Messinstruments zu korrigieren, welche vor allem kurz nach Vulkanausbrüchen und für polare Stratosphärenwolken beobachtet werden. Wenn diese Gradienten für die Berechnung von Extinktionsprofilen nicht beachtet werden, so kann dies dazu führen, dass sowohl die optischen Dicke als auch die Höhe von Vulkanfahnen oder polarer Stratosphärenwolken unterschätzt werden. In dieser Arbeit wird ein Verfahren vorgestellt, welches mit Hilfe von dreidimensionalen Strahlungstransportsimulationen und horizontal aufgelösten Datensätzen die berechneten Extinktionsprofile korrigiert.rnrnVergleichsstudien mit den Ergebnissen von Satelliten- (SAGE II) und Ballonmessungen zeigen, dass Extinktionsprofile von stratosphärischen Partikeln mit Hilfe des neu entwickelten Algorithmus berechnet werden können und gut mit bestehenden Datensätzen übereinstimmen. Untersuchungen des Nabro Vulkanausbruchs 2011 und des Auftretens von polaren Stratosphärenwolken in der südlichen Hemisphäre zeigen, dass das Korrekturverfahren für horizontale Gradienten die berechneten Extinktionsprofile deutlich verbessert.
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A new liquid-fuel injector was designed for use in the atmospheric-pressure, model gas turbine combustor in Bucknell University’s Combustion Research Laboratory during alternative fuel testing. The current liquid-fuel injector requires a higher-than-desired pressure drop and volumetric flow rate to provide proper atomization of liquid fuels. An air-blast atomizer type of fuel injector was chosen and an experiment utilizing water as the working fluid was performed on a variable-geometry prototype. Visualization of the spray pattern was achieved through photography and the pressure drop was measured as a function of the required operating parameters. Experimental correlations were used to estimate droplet sizes over flow conditions similar to that which would be experienced in the actual combustor. The results of this experiment were used to select the desired geometric parameters for the proposed final injector design and a CAD model was generated. Eventually, the new injector will be fabricated and tested to provide final validation of the design prior to use in the combustion test apparatus.
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Ocean acidification might reduce the ability of calcifying plankton to produce and maintain their shells of calcite, or of aragonite, the more soluble form of CaCO3. In addition to possibly large biological impacts, reduced CaCO3 production corresponds to a negative feedback on atmospheric CO2. In order to explore the sensitivity of the ocean carbon cycle to increasing concentrations of atmospheric CO2, we use the new biogeochemical Bern3D/PISCES model. The model reproduces the large scale distributions of biogeochemical tracers. With a range of sensitivity studies, we explore the effect of (i) using different parameterizations of CaCO3 production fitted to available laboratory and field experiments, of (ii) letting calcite and aragonite be produced by auto- and heterotrophic plankton groups, and of (iii) using carbon emissions from the range of the most recent IPCC Representative Concentration Pathways (RCP). Under a high-emission scenario, the CaCO3 production of all the model versions decreases from ~1 Pg C yr−1 to between 0.36 and 0.82 Pg C yr−1 by the year 2100. The changes in CaCO3 production and dissolution resulting from ocean acidification provide only a small feedback on atmospheric CO2 of −1 to −11 ppm by the year 2100, despite the wide range of parameterizations, model versions and scenarios included in our study. A potential upper limit of the CO2-calcification/dissolution feedback of −30 ppm by the year 2100 is computed by setting calcification to zero after 2000 in a high 21st century emission scenario. The similarity of feedback estimates yielded by the model version with calcite produced by nanophytoplankton and the one with calcite, respectively aragonite produced by mesozooplankton suggests that expending biogeochemical models to calcifying zooplankton might not be needed to simulate biogeochemical impacts on the marine carbonate cycle. The changes in saturation state confirm previous studies indicating that future anthropogenic CO2 emissions may lead to irreversible changes in ΩA for several centuries. Furthermore, due to the long-term changes in the deep ocean, the ratio of open water CaCO3 dissolution to production stabilizes by the year 2500 at a value that is 30–50% higher than at pre-industrial times when carbon emissions are set to zero after 2100.
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In this thesis I have tried to determine the suitable temperature, time and the amount of soda ash and lime needed for the calcining process. The leaching and purification tests were studied experimentally. The earlier process for making chromate from chromite was not the same as is used today. Therefore I have found it useful to put into this thesis the newest method for making chromate salts and their important uses.
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General information on talc, including foreign and United States occurrences, origin, and uses is covered. Montana deposits are discussed in greater detail as to location, geology, mineralogy, and mining. Studies of talc by petrographic and x-ray methods and an experiment to determine the porosity are described and discussed.
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Abstract concepts like numbers or time are thought to be represented in the more concrete domain of space and the sensorimotor system. For example, thinking of past or future events has a physical manifestation in backward or forward body sway, respectively. In the present study, we investigated the reverse effect: can passive whole-body motion influence the processing of temporal information? Participants were asked to categorize verbal stimuli to the concepts future or past while they were displaced forward and backward (Experiment 1), or upward and downward (Experiment 2). The results showed that future related verbal stimuli were categorized faster during forward as compared to backward motion. This finding supports the view that temporal events are represented along a mental time line and that the sensorimotor system is linked to that representation. We showed that body motion is not just an epiphenomenon of temporal thoughts. Passive whole-body motion can influence higher-order temporal cognition.
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[1] In the event of a termination of the Gravity Recovery and Climate Experiment (GRACE) mission before the launch of GRACE Follow-On (due for launch in 2017), high-low satellite-to-satellite tracking (hl-SST) will be the only dedicated observing system with global coverage available to measure the time-variable gravity field (TVG) on a monthly or even shorter time scale. Until recently, hl-SST TVG observations were of poor quality and hardly improved the performance of Satellite Laser Ranging observations. To date, they have been of only very limited usefulness to geophysical or environmental investigations. In this paper, we apply a thorough reprocessing strategy and a dedicated Kalman filter to Challenging Minisatellite Payload (CHAMP) data to demonstrate that it is possible to derive the very long-wavelength TVG features down to spatial scales of approximately 2000 km at the annual frequency and for multi-year trends. The results are validated against GRACE data and surface height changes from long-term GPS ground stations in Greenland. We find that the quality of the CHAMP solutions is sufficient to derive long-term trends and annual amplitudes of mass change over Greenland. We conclude that hl-SST is a viable source of information for TVG and can serve to some extent to bridge a possible gap between the end-of-life of GRACE and the availability of GRACE Follow-On.