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Zajištění stavební jámy a založení objektu CARLA Brno / Securing of Foundation Pit CARLA in BrnoNovák, Michal January 2014 (has links)
The topic of the master’s thesis is the statically compliant and economical design of the ensuring of foundation pit for building Carla Brno. The calculation part will be solved through program GEO5. The part of this thesis is also to describe the technological process of implementing elements and the relevant project documentation.
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Založení stavby River Garden III v Praze / Foundation design of River Garden III in PragueMalinský, Martin January 2015 (has links)
The topic of this master's thesis are the design of ensuring foundation pit and foundation of administrative building in Prague. In the vicinity of foundation pit is situated the river Vltava, which directly influences the ground water level at the job site. During construction, it is necessary to envisage the possibility of occurrence of the old building structures of docks.
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Užití otolitů pro studium růstu a populační dynamiky okounovitých a kaprovitých ryb v zatopeném důlním díle Most / The use of otoliths for growth and population dynamics studies of Percidae and Cyprinidae in Most water reservoirTůmová, Eliška January 2013 (has links)
This Master thesis compares growth of Percidae and Cyprinidae in flooded mining pit Most with water reservoir Vír, which is stable, fifty years old. Fish were cought using toils by workers from Hydrobiology institute, Academy of Sciences, Czech Republic, which are exploring fish stock. Otoliths, scales, and operculas from both families, Cyrinidae and Percidae, were removed from fish for age determination and growth back-calculation in individual years. Due to surplus of nutrients and food in flooding mining pit is assumed a huge growth difference in the first two years of life. The aim of this thesis is not only to describe the difference in the expected growth of individual species, but also to estimate its causes. At the same time will be in a very contrasting conditions compared different methods of age determination. Key words: otolith, fish age, fish population, fish growth, water reservoir, flooded mining pit, growth back-calculations
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Treatment of acid mine lakes: lab and field studiesSchipek, Mandy 22 November 2011 (has links)
Mining of lignite in Lusatia has a long history of over 100 years. The extracted brown coal is utilized to generate electricity in three large power plants: Jänschwalde, Boxberg, and Schwarze Pumpe. With an annual carbon dioxide (CO2) output of approximately 50 million tons, these power plants are among Germany’s large-scale CO2 emitters.
The environmental impact from open-pit mining is of a considerable degree and currently poses a challenging problem. The groundwater deficit in 1990 was 7 billion m3 over a surface area of approximately 2100 km2 (Luckner, 2006a) and was bisected in value until today. Due to the decline of mining activity and the termination of mine drainage at most open pits in the Lusatian region, the groundwater table has recovered forming 28 pit lakes (Zschiedrich, 2011). The majority of the post mining lakes do not meet the quality standards for pH, iron or sulfate parameters; because of pyrite oxidation that produces acid mine drainage (Luckner, 2006b, Klapper and Schultze, 1995, Schultze et al., 2010). The post mining lakes in Lusatia have low pH values (3 – 4), high sulfate contents (up to 2800 ppm) as well as high iron concentrations (100 – 150 ppm).
Lakes are flooded by groundwater and using surface water from Spree and Neisse River to achieve fast filling and dilution; however, due to the limited availability of surface water, further rehabilitation strategies for the region had to be investigated.
Between 1970 and 1990, approximately 26 million m3 of suspended fly ash were deposited in the lake Burghammer and settled as an ash body at its base; where it may be used for rehabilitation. In a first experiment conducted in 2001 material from the ash body was picked up and redistributed throughout the lake. By this treatment the pH of the lake was raised temporarily; however, a sustainable remediation was not achieved.
Based on these experiments it was investigated whether the ash reacts more sufficiently through additional CO2 injection or not. Aim was to combine the rehabilitation of acid mine lakes with the utilization of atmospheric carbon dioxide emissions from coal-fired power plants. The CO2 sequestration is achieved through the generation and accumulation of carbonates in the lake. The following equations describe the precipitation of carbonate by using CO2 and alkaline earth cations M:
CO2 + MO → MCO3 (s)
CO2 + M(OH)2 → MCO3 (s) + H2O
Therefore, neutral pH conditions are necessary for the long-term accumulation of carbonates in the lakes.
In laboratory investigations it was shown, that the 20 to 30 years old fly ash deposits of lake Burghammer can be used for carbonate sequestration and lake water treatment. Bivalent ions (Ca2+, Mg2+) are eluable and available for carbonate precipitation; on average we assumed 1 wt.-% of reactive calcium to be contained in the settled ash sediments. Settled fly ash sediments are less reactive than fresh fly ash from a power plant (e.g. Schwarze Pumpe). During batch experiments, we increased the buffering capacity to maximum values of 7 mmol/L. Beforehand no buffering capacity exists due to the low pH of 2.9 in the lake. Batch investigations provided a sequestration potential of 17 g CO2/kg ash sediment; in comparison fresh fly ash results in a sequestration potential of 33 g CO2/kg ash (Schipek and Merkel, 2008b, Schipek and Merkel, 2008a, Schipek, 2009).
Based on the laboratory results a field experiment was conducted. In this field experiment gas injection lances were installed to a sediment depth of 12 m. Gaseous CO2 was applied with a pressure of 2.2 bar and 2.2 m³/h for 3 months and lake water was monitored during injection. Variations in total inorganic carbon due to diffusion processes of CO2 saturated pore waters could be observed. As the pilot experiment comprised only a small area of lake Burghammer no initial neutralisition (e.g. by a suction excavator) was possible. Thus, no further changes in water chemistry were observed.
Drilling cores in the vicinity of the injection area provided mineralogical and geochemical conditions before and after CO2 treatment. No trace metal mobilization was found during CO2 injection. Most elements showed decreasing trends or didn’t change significantly. Calculated saturation indices for calcite indicated equilibrium conditions or slightly oversaturated conditions (SICalcite,average +0.12; SICalcite,median +0.31). Geochemical and mineralogical investigations proved that CO2 sequestration is possible with an average precipitation rate of 0.5 wt.-% (2.2 g CO2/kg). The maximum rate for carbonate precipitation was determined with 7.4 wt.-% Calcite, according to 32.6 g CO2 per kilogram treated ash.
Besides the use of the settled fly ash as neutralizing agent in acidic mining lakes, laboratory and field investigations were conducted in order to improve in-lake liming. In batch and columns experiments, different liming agents (synthetic marble powder and industrial products) were tested and investigated. Significant differences in reactivity were obvious at pCO2 > 3.8 • 10-4 atm. Ions typical for acid mine drainage (e.g. Mn2+, Cd2+, SO42-) do have different effects on the kinetic of carbonate dissolution. Manganese concentrations typical for acidic mining lakes inhibit calcite dissolution. Cadmium has as well a significant influence on dissolution and kinetics. Only circa 50 % of the calcium concentration was reached with cadmium as inhibitor compared to the dissolution in pure water. Increased CO2 partial pressure might be used to compensate inhibtion by material impurities and/or water constituents.
Column experiments showed that a multi-stage application of liming agent increases the efficiency of a lake treatment. The combination of a first application of calcite (up to pH 4.5) and further application of Ca(OH)2 seemed to be the most promising method. This treatment sheme was successfully applied in lake Burghammer from March 2009 – December 2010 (initial neutralisation and 6 follow-up treatments).
Finally, it can be concluded, that in lignite mining districts in-lake treatment of acidic mining lakes is a seminal method to handle water quality problems. Using gaseous CO2 in combination with industrial by-products can be accounted as sustainable method for CO2 sequestration and for treatment of AMD. The advantage for mining areas lays in the prevention during treatment of acid mine lakes. Nevertheless, this method presents only a niche solution due to the dependence on alkaline materials, e.g. fly ash.
The development of further strategies and optimization during lake water treatment by in-lake liming might improve the effectiveness of the method. Using calcite instead of NaOH or CaO as liming agent will provide advantages in being more economic and ecological (CO2 bilance). In order to enhance efficiency the use of calcite in combination with CO2 can be a worth considering suggesting. If meteorological parameters (wind) and lake specific characteristics (morphology, currents, etc.) will be considered efforts and costs for in-lake liming will be minimized. / Der Abbau von Braunkohle im Lausitzer Bergbaurevier hat seit über 100 Jahren Tradition. Die abgebaute Braunkohle wird dabei hauptsächliche zur Energieerzeugung in den drei großen Kraftwerken Jänschwalde, Boxberg und Schwarze Pumpe genutzt. Mit einem jährlichen Kohlenstoffdioxid (CO2) – Ausstoß von circa 50 Millionen Tonnen gehören diese Kraftwerke zu Deutschlands größten CO2-Emittenten.
Der Einfluss auf die Umwelt durch Tagebau-Betrieb ist von beträchtlichem Ausmaß und bringt große Probleme mit sich. Im Jahr 1990 betrug das Grundwasser-Defizit im Lausitzer Bergbaurevier 7 Milliarden m³ auf einer Fläche von circa 2100 km² (Luckner, 2006a). Dieses Defizit hat sich bis zum heutigen Zeitpunkt halbiert. Durch den Rückgang der Bergbauaktivitäten und die Beendigung der Wasserhaltungsmaßnahmen in den meisten Tagebauen, hat der ansteigende Grundwasserspiegel 28 Tagebaufolgeseen geschaffen (Zschiedrich, 2011). Der überwiegende Teil der Tagebaufolgeseen ist aufgrund der Pyritoxidation, welche AMD (acid mine drainage) produziert, hinsichtlich der Wasserqualitätsparameter stark beeinflusst (Luckner, 2006b, Klapper and Schultze, 1995, Schultze et al., 2010). Die Tagebaufolgeseen im Lausitzer Bergbaurevier sind durch niedrige pH-Werte (3 – 4), hoche Sulfat-Konzentrationen (bis zu 2800 ppm) und hohe Eisengehalte (100 – 150 ppm) gekennzeichnet.
Die entstehenden Seen sind hauptsächlich durch aufsteigendes Grundwasser und Oberflächenwasser aus den Flüssen Spree und Neisse geflutet. Aufgrund der geringen Verfügbarkeit von Oberflächenwasser mussten weitere Sanierungsmaßnahmen für die Region untersucht werden.
Zwischen 1970 und 1990 wurden im Tagebaufolgesee Burghammer circa 26 Millionen m³ Flugasche-Suspension als Aschekörper abgelagert, wobei eine Nutzung zu Sanierungszwecken angedacht war. Im Rahmen einer Aschesedimentumlagerung im Jahr 2001 wurde der pH-Wert des Seewassers kurzzeitig angehoben, eine nachhaltige Sanierung fand jedoch nicht statt.
Auf Grundlage dieser Ergebnisse wurde im Rahmen dieser Dissertation untersucht, ob die abgelagerten Aschesedimente nachhaltiger durch Einsatz von CO2 reagieren. Ziel war es die Sanierung von Tagebaufolgeseen mit der Reduktion von CO2-Emissionen aus Kohlekraftwerken zu kombinieren. Diese CO2-Sequestrierung sollte durch die Bildung und Ablagerung von Carbonaten im Seesediment erfolgen. Die Gleichungen (1) und (2) beschreiben dabei die Fällungsreaktion von Carbonaten aus CO2 mit dem Alkalimetall M (aus Oxiden bzw. Hydroxiden):
CO2 + MO → MCO3 (s)
CO2 + M(OH)2 → MCO3 (s) + H2O
Zur Carbonatfällung und nachhaltigen Ablagerung sind neutrale pH-Bedingungen notwendig.
In Laboruntersuchungen konnte gezeigt werden, dass die 20 bis 30 Jahre alten Flugaschesedimente zur CO2-Sequestrierung in Kombination mit Seewasserbehandlung genutzt werden können. Zweiwertige Ionen (Ca2+, Mg2+) sind aus den Aschesedimenten eluierbar und stehen für die Fällungsreaktion zur Verfügung. Durchschnittlich 1 Masse-% reaktives Calcium befindet sich in den Sedimenten. Die abgelagerten Aschesedimente sind dabei weniger reaktiv als frische Flugaschen aus Kohlekraftwerken (z.B. Schwarze Pumpe). In Batch-Versuchen mit Tagebaufolgesee-Wasser konnte die Säure-Pufferkapazität auf maximal 7 mmol/L erhöht werden. Sequestrierungs-Raten von 17 g CO2/kg Aschesediment wurden im Rahmen der Versuche erreicht. Im Vergleich dazu betrugen die Sequestrierungs-Raten in Versuchen mit frischen Flugaschen bis 33 g CO2/kg Asche (Schipek and Merkel, 2008b, Schipek and Merkel, 2008a, Schipek, 2009).
Auf Grundlage dieser Laborergebnisse wurde ein Feldversuch im Tagebaufolgesee Burghammer geplant. Während diesem wurden Gasinjektionslanzen bis in eine Sedimenttiefe von 12 m im abgelagerten Aschesediment installiert. Gasförmiges CO2 wurde mit einem durchschnittlichen Druck von 2.2 bar und 2.2 m³/h für eine Dauer von 3 Monaten injiziert. Während dieser Zeit fand ein kontinuierliches Monitoring des Seewassers im Bereich der Injektion statt. Veränderungen des Gehaltes an TIC (total inorganic carbon) aufgrund von Diffusionprozessen von CO2-gesättigtem Porenwasser aus dem Aschekörper waren beobachtbar. Da der Feldversuch nur in einem begrenzten Bereich des Tagebaufolgesees Burghammer stattfand und keine Initialneutralisierung vorsah, konnten keine weiteren, großmaßstäblichen Veränderungen im Wasserkörper festgestellt werden.
Bohrkernentnahmen im Umfeld des Behandlungsgebietes lieferten Aussagen bezüglich der mineralogischen und geochemischen Beschaffenheit vor und nach CO2-Injektion. Im Porenwasser wurde keine Spurenmetall-(re)-mobilisierung durch die Behandlung mit CO2 festgestellt. Nahezu alle Elemente zeigten einen abnehmenden Trend durch die Behandlung mit CO2, bzw. keine signifikanten Veränderungen. Modellierte Sättigungsindizes für Calcit wiesen auf Gleichgewichtsbedingungen oder leichte Übersättigung bzgl. Calcit hin (SICalcit, Mittelwert +0.12; SICalcit, Median +0.31). Geochemische und mineralogische Untersuchungen zeigten, daß CO2-Sequestrierung mit einer durchschnittlichen Fällungsrate von 0.5 Masse-% (2.2 g CO2/kg Aschesediment) erreicht wurde. Die maximale Fällungsrate wurde mit 7.4 Masse-% Calcit bestimmt, dies entspricht einer Festlegung von 32.6 g CO2/ kg Aschesediment.
Neben der Nutzung der abgelagerten Aschesedimente zur Behandlung des Tagebaufolgeseewassers wurden desweiteren Labor- und Feldversuche durchgeführt um In-Lake-Behandlungen mit industriellen Kalkprodukten zu optimieren. In Batch- und Säulenversuchen wurden verschiedene Kalkprodukte (synthetisches Marmorpulver und industrielle Produkte) getestet und untersucht. Signifikante Unterschiede auf die Reaktivität wurde bei erhöhten CO2-Partialdrücken (pCO2 > 3.8 • 10-4 bar) beobachtet. Wasserinhaltsstoffe, die typisch für AMD sind (z.B.. Mn2+, Cd2+, SO42-) zeigten einen signifikanten Einfluss auf die Calcit-Lösungskinetik. Mangankonzentrationen, wie sie in Lausitzer Tagebaufolgeseen vorkommen, zeigten – ebenso wie Cadmium - eine inhibitierende Wirkung auf die Kinetik. Im Vergleich zu Versuchen mit destilliertem Wasser wurden nur ungefähr 50 % der Calcium-Gleichgewichtskonzentration mit Cadmium als Inhibitor erreicht. Erhöhte CO2-Partialdrücke könnten genutzt werden, um die inhibitierende Wirkung von vorhanden Materialverunreinigungen und/oder Wasserinhaltsstoffen zu kompensieren.
Säulenversuche zeigten, dass der mehrstufige Einsatz von Kalkprodukten die Effizienz während einer Seewasserbehandlung erhöht. Die Kombination einer Erstbehandlung mit Kalksteinmehl (bis pH 4.5), und einer Behandlungsfortsetzung mit Ca(OH)2 erwies sich als wirkungsvollste Methode. Dieses Behandlungsschema (Initialneutralisation, 6 Nachfolgebehandlungen) wurde im Tagebaufolgesee Burghammer von März 2009 – Dezember 2010 erfolgreich angewandt.
Zusammenfassend lässt sich sagen, dass in ehemaligen Bergbaurevieren die In-Lake-Behandlung von Tagebaufolgeseen eine zukunftsträchtige Methode zur Behandlung von Wasserqualitätsproblemen darstellt. Die Nutzung von gasförmigen CO2 in Kombination mit industriellen „Abfall-Produkten“ kann als nachhaltige Methode zur CO2-Sequestrierung und zur Behandlung von AMD bezeichnet werden. Der Vorteil in Bergbaurevieren liegt dabei in der Vorbeugung der Entstehung von Wasserqualitätsproblemen. Dennoch stellt diese Methode nur eine Nischenlösung aufgrund der Verfügbarkeit der alkalischen Materialien (Flugasche) dar.
Die Entwicklung und Optimierung weiterführender Strategien zur In-Lake-Behandlung durch Kalkung wird zur Effizienzerhöhung beitragen. Die Nutzung von Kalksteinmehl anstelle von NaOH bzw. CaO als Neutralisationsprodukt wird Vorteile hinsichtlich ökonomischer und ökologischer Sicht (CO2-Bilanz) mit sich führen. Um die Effizienz beim Einsatz von Kalksteinmehl zu steigern, kann der Einsatz von CO2 in Betracht gezogen werden. Sobald meteorologische Parameter (Wind) und see-spezifische Merkmale (Morphologie, Strömungen, etc.) berücksichtigt werden, kann der Aufwand und die Kosten für In-Lake-Behandlungen minimiert werden.
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Geomorfologická analýza a vývoj reliéfu centrální části Troskovické vrchoviny / Geomorphological analysis and relief development of central part of Troskovická HighlandDavid, Daniel January 2010 (has links)
David, D. (2010): Geomorphological analysis and development relief of central part in Troskovická vrchovina (Highland) (Bohemian Paradise). Charles University in Prague, Faculty of Sience, Department of Physical Geography and Geoecology. The central part of Troskovická vrchovina Highland lies between towns Turnov and Jičín in Jičínská pahorkatina (Hilly land) in Geopark Bohemian Paradise. It is a rugged rocky area mostly built of sedimetary rocks (Cretaceous quartz sandstones). The relief is cut by canyons and in the center of plateau is vulcanic neck Trosky. This book contains results of detailed geomorphological mapping and analysing of the area. The major product of this study is detailed geomorphological map 1:10 000. Key words: Bohemian Paradise, detailed geomorphological mapping, geomorphological analysis, Střeleč pit (main), sandstone relief, vulcanic rocks and Trosky neck.
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Klíčové faktory akumulace půdní organické hmoty / Key factors in soil organic matter accumulationVindušková, Olga January 2017 (has links)
Soil organic matter (SOM) is highly important for soil quality and the global carbon cycle. SOM content is influenced by a complex interplay of many different factors such as time, climate, parent material, vegetation, and others. The effect of time is often studied using the chronosequence approach using a set of study sites differing in age but comparable in other soil-forming factors. The effect of other factors can be studied by comparing two or more chronosequences. An important assumption of these approaches is that the SOM quantification methods produce comparable results both among sites of each sequence and among different sequences. In this thesis, I explored the key factors in SOM accumulation and dealt with SOM quantification methods. I studied SOM accumulation in two model situations - in post-mining sites after open-cast coal and oil shale mining and in landslides in the Western Carpathians. The results of this thesis are summarized in one book chapter accepted for publication and four papers, out of which three have been published and one is prepared for publication in an international journal with impact factor. The key factor affecting the rate of SOM accumulation after a major disturbance is time. The accumulation rates found in the first 40 to 100 years in both post-mining sites...
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Rekonstrukce zdraví a životního stylu jedinců pohřbených v sídlištních jamách a hrobech starší a střední doby bronzové na základě patologických znaků na kostře / Health reconstruction of individuals buried in settlements and graves in Early Bronze Age based on pathological traces on skeletonsPankowská, Anna January 2014 (has links)
An increase in the diversity of Early Bronze Age (EBA) burial practices is well documented in central and southern Moravia between 2200-1500 BC. Apart from scarce cremations and pithoi burials, two more frequent parallel burial types appear. One is the standard burials in cemeteries, the other burials in settlement pits, the latter considered a deviation until recently. Thanks to recent excavations and new quantification procedures, however, abundance of settlement burials as well as uniformity and predictability of body deposition and grave equipment in pit burials has been shown. My intention is to show the existence of two parallel burial rites on the basis of bioarchaeological and archaeological evidence. I focus on the reconstruction of health and social status of individuals buried in settlement pits and graves. I observe the amount of demographic variability, diseases and trauma within each group. I suppose the distribution of diseases according to age, sex and archaeological record will be similar within each of the groups. As a result, we may speak about two equivalent burial practices. If deviations are encountered within settlement pits, however, we should speak about deviations or burials determined for a minority and homogeneous segment of population. Skeletons originate in two...
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Propuesta de ajuste al modelo predictivo Kuz-Ram empleando análisis granulométrico de imágenes para mejorar la estimación de la fragmentación de roca volada en un yacimiento hidrotermal de alta sulfuración del PerúArispe García, Rolando Alberto, Sosa Valdivia, Manuel Martin 07 January 2022 (has links)
Este trabajo de investigación busca mejorar la estimación de la fragmentación de roca volada en minería a cielo abierto, específicamente en la empresa Minera Aruntani S.A.C. Unidad Arasi. La investigación se lleva a cabo mediante una reestructuración a la ecuación de predicción del tamaño de rocas, Kuz-Ram, modelo tradicional, cambiando el coeficiente de tierra, permitiendo disminuir los márgenes de error tomando en consideración aspectos relevantes del diseño como los parámetros geológicos, así como parámetros de perforación y voladura. Para efectuar dicho logro, se planteó una función objetivo y su posterior solución mediante el método iterativo de Newton-Raphson desarrollado en un entorno del software Matlab. El pertinente planteamiento y desarrollo permitió obtener un nuevo valor para el coeficiente de tierra con el cual se logra disminuir los porcentajes de error en la estimación de fragmentación de 40%, con el método tradicional, a un 8% en promedio logrando así una mejora considerable. / This research work seeks to improve the prediction of the fragmentation of blasted rock in open pit mining, specifically in the company Minera Aruntani S.A.C. Arasi unit. The research is carried out through a modification to the Kuz-Ram fragmentation estimation model, a traditional model, changing the land coefficient, allowing to reduce the margins of error taking into consideration relevant aspects of the design such as geological parameters, as well as parameters of drilling and blasting. To carry out this achievement, an objective function was proposed and its subsequent solution by means of the iterative Newton-Raphson method developed in a Matlab software environment. The pertinent approach and development allowed obtaining a new value for the land coefficient with which it is possible to reduce the error percentages in the fragmentation estimation from 40%, with the traditional method, to 8% on average, achieving a considerable improvement. / Tesis
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Phenotypic correlates of spawning migration behaviour for roach (Rutilus rutilus) and ide (Leuciscus idus) in the stream Oknebäcken, Sweden.Lindbladh, Emma, Eriksson, Johanna January 2020 (has links)
Migration occurs among many animal species for the purpose of, among other things, finding food or to reproduce. Spawning migration is a form of migration that occurs among many fish species where they move to another site for reproduction. The movement can be obstructed by migration barriers like road culverts. Barriers to migration pose one of the greatest threats to biodiversity and ecosystem functions in freshwater. They impair the connectivity of watercourses and may prevent fish from improving reproductive success or completing their life histories altogether. There are both benefits and costs with migration, benefits such as increased survival for the adults and offspring, and costs such as increased energy consumption and increased mortality. The costs are often dependent on the morphological traits of the individual, like body shape and size. In this study, the spawning migration of two species of fish of the family Cyprinidae, ide (Leuciscus idus) and roach (Rutilus rutilus) was investigated. Few studies have been made on ide or on roach compared to other cyprinids and salmonids. This study might therefore enhance the overall knowledge of these two species. The overall aims of this project are to study and compare phenotypic correlates of spawning migration behaviour of ide and roach. The field studies were performed in Oknebäcken, Mönsterås (SE632310-152985), Sweden in March and April 2020. To describe the watercourse and define the location and characteristics of different potential migration barriers, a simplified biotope mapping method was used. The fish were caught in a hoop net and then measured, weighted, sexed, and injected with passive integrated transponder using the bevel down method. In order to register in stream movement of fish, reading stations with antennas were placed, at two locations upstream from the marking station and one downstream at the estuary. The sex ratio differed from the expected 1:1 with a majority of females for both species. This might be a result of fluctuations in survival of spawn coupled with different age-at-maturity between sexes. We found that individuals that arrived early to the stream were larger for both study species, as other studies also reported. Also, male ide was both larger and arrived before female ide. There might be an energy cost associated with early arrival to the stream and therefore, larger individuals arrive first. For roach, there was no difference in arrival time between the sexes although female roach were larger. There was no difference in the time spent in the stream between the species. For ide, females stayed for a longer period of time in the stream than males. However, the opposite was true for roach. This may be because male roach might benefit from more fertilization events when staying longer. There might therefore be a trade-off between the energy cost in staying in the stream and the increased fitness advantage in fertilization events. We found no correlation between any of the morphological traits and migration distance. However, since very few individuals were registered at the upstream reading stations, there might be an effect of migration barriers on the spawning migration. The mortality after spawning was higher for roach than for ide. For ide, a larger proportion of females than males died. For roach, individuals that arrived early was classified as alive to a greater extent than those who arrived late. Both similarities and differences between the species were discovered in this study which concludes that even closely related species might differ substantially from each other.
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Effect of nylon-6 and chitosan nanofibers on the physicomechanical and antibacterial properties of an experimental resin-based sealantHamilton, Maria Fernanda January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Purpose: Dental sealant forms a physical barrier to prevent pit and fissure caries; therefore, the retention rate becomes a main factor of the sealant’s effectiveness. Electrospun nylon-6/N6 nanofibers have shown good mechanical properties, such as high tensile strength and fracture toughness. Chitosan/CH has received significant attention due to properties such as antibacterial activity. The purpose of this study was to synthesize and evaluate the effect of incorporating N6 and CH electrospun nanofibers on the physical-mechanical and antibacterial properties of an experimental resin-based sealant. Methods and Materials: Nanofiber synthesis: N6 pellets were dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol at a concentration of 10wt%. Practical-grade chitosan was dissolved in trifluoroacetic acid and dichloromethane (60:40 TFA/DCM) at 7 wt%. Electrospinning parameters were optimized in order to fabricate defect-free N6 and chitosan nanofiber mats. Morphological and chemical characterizations were performed by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively after vacuum drying the mats for 48 h. The average fiber diameter was determined from SEM images by measuring the diameter of 120 fibers using ImageJ software. Experimental Sealant: N6 and CH electrospun mats (3×3cm2) were immersed into a resin mixture of BIS-GMA/TEGDMA. Once no bubbles were seen, the resin-modified N6 and CH mats were put on a glass plate, light-cured (“TRIAD 2000”) for 2 min and then submitted to a cryomilling process to obtain a fine micron-sized powder. Three different filler levels (1 wt%, 2.5 wt%, 5 wt%) were used to prepare the N6 and CH incorporated resin-based sealants. Additionally, a commercially available resin-based sealant and the experimental resin mixture (unfilled) were used as controls. Three-point flexural testing, Vickers microhardness testing, and agar diffusion testing were performed on the experimental sealants and the commercial sealant. Data were analyzed by one-way ANOVA and Fisher's Protected Least Significant Differences Pair-wise comparisons between groups (5%). Results: The average fiber diameter for N6 was found to be 503±304 nm and 595±411 nm for CH. No significant difference was found between fiber diameter (p = 0.0601). FTIR confirmed the characteristic peaks for N6 ((CO-NH and [-(CH2)5-].) and CH (N-H and C2F3O2-). CH-5% group had significantly higher (p = 0.0000) FS (115.3±4.5 MPa) than all other groups. CH-1% and CH-2.5% groups had significantly higher FS than the control (unfilled) (p = 0.0016 and p = 0.0033 respectively); Helioseal Clear (p = 0.0000), and nylon groups. N6-5% had significantly higher flexural strength than Helioseal Clear (p = 0.0013) and N6-2.5% (p = 0.0250).
CH-1% had significantly higher hardness values than all other groups, and CH-5% (p = 0.0414) had significantly higher values than N6-2.5%. No antibacterial inhibition was seen in any of the tested groups. Conclusions: CH and N6 nanofibers were successfully prepared via electrospinning and used to modify the experimental resin-based dental sealants. The overall results indicated that CH-containing sealants presented the highest flexural strength and hardness; however, none of the CH groups displayed antimicrobial properties. Further investigation is needed to enhance the physico-mechanical properties of the experimental resin-based sealants using nylon-6 and CH.
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