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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Advanced analytical methods for platinum group elements:applications in the research of catalyst materials, recycling and environmental issues

Suoranta, T. (Terhi) 02 August 2016 (has links)
Abstract Platinum group elements (PGEs) have a high commercial value and variety of applications in different fields of industry. One of the well-known applications is the use of palladium, platinum and rhodium in the catalytic converters of automobiles to reduce the amount of harmful gases emitted to the environment. Advanced analytical methods are needed to deal with issues related to development of new catalyst materials, recycling of PGEs from spent materials and for monitoring PGE emissions to the environment. In the first part of this study the emphasis was on the catalyst materials. Especially, reliable determination of ruthenium content in catalyst materials required further studies. Consequently, acid digestions in closed vessels using a microwave oven or high pressure asher were compared with a previously reported fusion method. Furthermore, the recovery of PGEs from spent materials is important due to many factors, for example, the high value of these metals, environmental aspects related to their production and possible availability issues in the future. Thus, utilization of microwave-assisted leaching and cloud point extraction (CPE) for the recovery of palladium, platinum, rhodium and ruthenium from catalyst materials was investigated. The second part of this study concentrated on the PGEs in environmental samples and the analytical challenges related to PGE determinations with inductively coupled plasma mass spectrometry (ICP-MS). Due to the use of PGEs in catalytic converters of automobiles, they are emitted to the roadside environment. The use of Pleurozium schreberi, a terrestrial moss, for active biomonitoring of these emissions was evaluated. Advanced analytical methods were needed to perform interference-free determinations of palladium, platinum and rhodium in these samples. Two alternative approaches for interference elimination were studied. Firstly, the interfering elements were removed using CPE as a chemical separation method. Secondly, interferences were eliminated using ammonia as a reaction gas with the novel ICP-MS/MS (inductively coupled plasma tandem mass spectrometry) technique. / Tiivistelmä Platinaryhmän alkuaineita hyödynnetään monissa teknisissä sovelluksissa. Yksi tunnetuimmista on autoliikenteen haitallisten päästöjen vähentäminen käyttäen palladiumia, platinaa ja rodiumia autojen pakokaasukatalysaattoreissa. Luotettavia analyysimenetelmiä tarvitaan esimerkiksi kehitettäessä uusia katalyyttimateriaaleja, kierrätettäessä platinaryhmän alkuaineita käytetyistä materiaaleista tai seurattaessa platinaryhmän alkuaineiden määrää ympäristössä. Tämän tutkimuksen ensimmäinen osa liittyi katalyyttien ruteniumpitoisuuksien määrittämiseen ja platinaryhmän alkuaineiden kierrätykseen katalyyttimateriaaleista. Erityisesti näytteenhajotusvaihe aiheuttaa usein ongelmia ruteniummäärityksissä. Tämän vuoksi tutkimuksessa verrattiin keskenään mikroaaltotekniikalla tai korkeapainetuhkistimella suoritettuja happohajotuksia ja aiemmin raportoidulla sulatemenetelmällä suoritettuja hajotuksia. Mikroaaltoavusteista liuotusta sovellettiin yhdessä samepisteuuton kanssa tutkittaessa katalyyttimateriaalien palladiumin, platinan, rodiumin ja ruteniumin kierrätysmahdollisuuksia. Aihe on ajankohtainen, kun huomioidaan platinaryhmän alkuaineiden korkea hinta, niiden tuotantoon liittyvät ympäristöasiat sekä saatavuuteen liittyvät epävarmuustekijät. Tutkimuksen toisessa osassa keskityttiin ympäristönäytteisiin ja erityisesti niiden ICP-MS -analytiikan (induktiiviplasmamassaspektrometria) haasteisiin. Autojen katalysaattoreista lähtöisin olevia platinaryhmän alkuaineita päätyy ympäristöön lähinnä teiden varsille. Näitä päästöjä arvioitiin aktiivista biomonitorointia käyttäen. Spektraaliset häiriöt vaikeuttivat kerättyjen sammalnäytteiden (Pleurozium schreberi) palladium-, platina- ja rodiumpitoisuuksien määrityksiä. Tämän vuoksi mittauksissa esiintyvien häiriöiden poistossa hyödynnettiin kahta eri lähestymistapaa. Näistä ensimmäisessä häiritsevät alkuaineet poistettiin kemiallisen erotusmenetelmän, samepisteuuton, avulla. Toisessa tavassa häiriöt poistettiin uudella ICP-MS/MS -tekniikalla (induktiiviplasmatandemmassaspektrometria) käyttäen ammoniakkia reaktiokaasuna.
92

Phylogeography and speciation in the genus arthroleptella

Turner, Andrew Alexander January 2009 (has links)
Philosophiae Doctor - PhD / Moss frogs are restricted to permanently moist terrestrial habitats in the south-western Cape Fold Mountains. There is a very close association between Arthroleptella distribution and Table Mountain Sandstone. Suitable habitats are generally occupied by allopatric populations of moss frogs. Comprehensive spatial sampling of moss frogs (genus Arthroleptella) in the Cape Floristic Region biodiversity hotspot yielded 192 new distribution records; 5 842 advertisement calls from 240 individual male frogs; 31 Rag-1,76 16S, 54 12S sequences and morphological measurements of 90 specimens. There are many differences in male advertisement call and genetic sequences between populations on different mountain ranges, even over small distances. A mitochondrial and nuclear gene phylogeny of the southern African Pyxicephalidae places Natalobatrachus as the sister genus to Arthroleptella. Application of a Bayesian relaxed molecular clock model indicates that Arthroleptella arose between 20 and 39 Ma. Phylogenetic trees return two main clades within Arthroleptella: one consists of species which exhibit chirp-like calls and the second contains species with longer calls composed of a series of clicks. These two clades diverged between 19 and 22 Ma. There is a general pattern of strong phylogeographic structure with many small, isolated populations. Three species are identified within the Chirping clade and seven in the Clicking clade, including three undescribed species. This population structure is a result of the patchy distribution of suitable habitat and low vagility of the moss frogs.The distribution and speciation of moss frogs has been affected by drying and cooling climate change, changing geomorphology over the last 20 Ma and the increasing prevalence of fire over the last 5 Ma. An assessment of the threat status of each species according to IUCN criteria categorised one species as Least Concern, seven as Near Threatened, one as Vulnerable and one as Critically Endangered. The primary threats to Arthroleptella are invasive alien plants and increased fire frequencies and intensities.
93

Mini One Stop Shop a jeho implementace v IS Finanční správy ČR / Mini One Stop Shop and its implementation in IS of Financial Administration of the Czech Republic

Růžičková, Veronika January 2014 (has links)
This thesis deals with the system Mini One Stop Shop and its implementation in IS of Financial Administration of the Czech Republic (ADIS). The first part describes the concept of the Mini One Stop Shop including basic concepts and related legislative documents. In the next part, were analyzed of the current conditions of the Financial administration of the Czech Republic in the area of IS / ICT in order to define a baseline for the implementation of MOSS payments area. The main outcome of this thesis is to design implementation of MOSS payments area in ADIS, which is composed of a detailed process analysis, catalog of functional requirements and an example of a specific analytical design for the selected functional requirements. The main contribution of this work is to link the general principles and requirements of MOSS that are defined uniformly for all EU Member States, with the principles and procedures implemented in the ADIS result in a the design implementation of MOSS payments area.
94

Hodnocení průmyslového znečištění životního prostředí Moravskoslezského kraje s použitím radioanalytických metod / Evaluation of Industrial Pollution of the Environment in the Moravian-Silesian Region Using Radioanalytical Methods

Brunčiaková, Miriama January 2016 (has links)
Moravian-Silesian Region is a part of an area so called „small black triangle". It is an area of higher pollution caused by some kind of industrial zone. This region belongs to the most polluted atmosphere in the Czech Republic. The pollution is caused by various factors but the most negative one is metallurgic industry but also mine-mining, transport, and small local furnaces. To analyze pollution, the instrumental neutron activation analysis with analyzing of moss samples were used. The moss has rudimentary root system so it takes nutrients as well as heavy metals from the atmosphere. All irradiation has performed in the Joint Institute for Nuclear Research (JINR) in the Frank Laboratory of Neutron Physics (FLNP) at the reactor IBR-2M. Two kinds of irradiation have been performed as short-term irradiation as long-term irradiation. Short-term irradiation took about 3 mins and then short-lived isotopes were measured for about 15 mins. The long-lived isotopes were measured twice after about 4 days for 30 mins and after 23 days for 90 mins after 3 days of irradiation. For long term irradiation, the cadmium-screened irradiation channel was used. For analyzation and data processing the software Genie 2000 as well as software developed at FLNP JINR were used. In sum, 43 samples of the terrestrial mosses (Hypnum cupressiforme, Pleurozium schreberi and Brachythecium rutabulum) were collected in autumn of 2015 in which the concentration of 38 elements were determined, including heavy metals. As a result, the factor analysis have been performed as well as maps analyzation.
95

Role komplexu exocyst v růstu a vývoji mechu Physcomitrella patens / Role of exocyst complex in growth and development of moss Physcomitrella patens

Rawat, Anamika Ashok January 2017 (has links)
During the course of evolution the early land plants gained extensive innovations that can be seen in modern day plants. The polar growth is an ancient feature of eukaryotic cells and is one of preadaptations that helped plants in successful colonization of land. The polar growth in plants regulates not only the direction of cell expansion and structural properties of cell wall but especially also the orientation of cell division, and is governed by various factors, including the exocyst complex. The exocyst is a well conserved vesicle tethering multi-subunit complex involved in tethering of secretory vesicles to the target membrane. The essential role of the exocyst complex in regulation of various cellular processes in Angiosperms is now well documented. Here I present results of a doctoral project that contributed to phylogenetic analyses of the land plant exocyst complex and especially to uncovering functions of three moss exocyst subunits, namely EXO70 (isoform PpEXO70.3d), SEC6 and SEC3 (isoforms PpSEC3A and PpSEC3B) in the model organism Physcomitrella patens. Various knock-out (KO) mutants in several moss exocyst subunits (Ppexo70.3d, Ppsec6, Ppsec3a and Ppsec3b) show pleiotropic defects directly or indirectly linked to the cell polarity regulation. Cell elongation and differentiation,...
96

Populační dynamika polštářovité rostliny silenky bezlodyžné ve Vysokých Tatrách / Population dynamics of cushion plant Silene acaulis in the High Tatras

Krchová, Emma January 2021 (has links)
This diploma thesis is studying population dynamics of endangered species Silene acaulis in the High Tatra Mountains in Slovakia. Silene acaulis is a species of extreme alpine habitats creating cushions that provide a microclimate acting as a facilitator of establishment of other species in the alpine communities. This dome-like structure has one woody taproot making it easier to distinguish each individual. It is thus a perfect model species for determining the population dynamics drivers. The findings help in understanding future behaviour of the species and whole alpine ecosystems. Population data have been collected since 2013 or 2014 in two valleys in the High Tatras providing a database suitable to study various effects on species performance. Data collection includes marking, measuring, counting of flowers and capsules, viability and new seedlings recording, gender identification and comparison of vegetation structure within and in close proximity of a cushion. The data on vegetation were analysed using CCA ordination and the population data were analysed using Integral Projection Models. The results show that the breeding system of Slovak S. acaulis is gynodioecious and the gender affects the size of cushions, individuals with both female and hermaphrodite flowers being the biggest. The...
97

Materializing. / Matrialisering.

Persson, Matilda January 2018 (has links)
This project is about how we can create architecture that hold the same atmospheric qualities as a tale. By using different media like film, dioramas and technology the tales have been analysed for qualities that have been carried through into architecture. The blend of the real and the unreal is central to any tale and so also to my project; this mixed expression is carried through into the resulting structure. The final product becomes a bath house full of expression, impressions and varying realities.
98

Peat exploitation on Thorne Moors. A case-study from the Yorkshire-Lincolnshire border 1626-1963, with integrated notes on Hatfield Moors

Limbert, Martin January 2011 (has links)
In its industrial heyday, Thorne Moors was the most extensive commercial peat operation in Britain. It became closely tied to nearby Hatfield Moors, and at both the methods of exploitation were essentially the same. Although much of Thorne Moors is situated in Yorkshire, the eastern extent lies in Lincolnshire. Recognizable differences in scale and methodology existed between the Yorkshire and Lincolnshire parts. After regional drainage in the 1620-30s, there was increased trade in the peat of Thorne Moors along the River Don. A succession of uses included unrefined and refined fuel, products from carbonization and distillation, and moss litter for working horses. From the mid-19th century, companies were formed to exploit the new uses, especially moss litter, and export became increasingly focused on railways. In 1896, the British Moss Litter Co. Ltd was set up (restructured 1899) to assume the Thorne/Hatfield interests of several smaller companies, including the Anglo-Dutch Griendtsveen Moss Litter Co. Ltd. The British Moss Litter Co. was acquired by Fisons Ltd in 1963. Following a contextual history, descriptions are given of both muscle-powered peat winning and transportation methodologies. These comprise exploitation in the 17th and 18th centuries, an examination of the 19th century writings of William Casson, and written allusions spanning 1863-1963. Information is imparted on the Griendtsveen Moss Litter Co. In addition to creating a 'Dutch' peat canal system, this company introduced an immigrant Dutch workforce, proficient in their native methods and intended inter alia to retrain local workers looking for employment with Griendtsveen. Dutch methodology persisted alongside the local methods for c.60 years. Accounts are also presented of the evolutionary limit of indigenous peat winning, and the use of narrow gauge railways. Finally the transition to mechanisation of peat cutting and narrow gauge haulage is outlined.
99

Zinnia Growth and Water Use Efficiency in a Rate Study of Coconut Coir Pith and Sphagnum Peat Moss in Container Growing Substrates

Lowry, Bonita Kristine 15 May 2015 (has links)
No description available.
100

Living on the edge : effectiveness of buffer strips in protecting biodiversity on boreal riparian forests

Hylander, Kristoffer January 2004 (has links)
<p>The objective of this thesis is to evaluate the ecological consequences of buffer strip retention on riparian and terrestrial biodiversity. Earlier studies on forest buffer strips have evaluated their effectiveness in relation to water quality and aquatic biota. However, forests along streams are species rich habitats for many organism groups. Buffer strip management is assumed to be important also for protecting such species. Current approaches to biodiversity-oriented forest management practices need to be scientifically evaluated. In this thesis the effects on bryophytes and land snails have been evaluated.</p><p>A before-and-after experiment along 15 small streams in northern Sweden showed that buffer strips of 10 m on each side of the stream moderated the negative effects exhibited at the clear-cuts. The number of land snail species remained similar as to before logging and the number of vanished bryophyte species was lower in the buffer strips than in the clear-cuts. The ground moisture influenced the survival rate of land snails at the clear-cuts. At mesic sites many species vanished but at wet sites the snail fauna was unaffected by the logging.</p><p>Many bryophyte species, most of them liverworts, decreased or disappeared in the buffer strips. These were mostly growing on substrates elevated from the forest floor, such as logs, stumps and tree-bases. A number of nationally red-listed species, sensitive for changes in microclimate, were among those decreasing most. Thus, for the species in most need of protection the buffer strips were too narrow.</p><p>An experiment with bryophyte transplants followed over a season showed that wet ground moisture moderated the negative edge effects in narrow buffer strips. On the other hand, the growth in mesic and moist sites was almost as low as in comparable clear-cuts.</p><p>Microclimatic edge effects are stronger at south facing than north-facing edges of forest clear-cuts. This was shown in an experiment using bryophyte growth as an indicator of differences in microclimate. However, the depth of edge influence seemed to be similar between north- and south-facing forest edges, >30 m for one species. An explanation for this could be that wind penetrates deeper into edges than solar radiation and has a more variable direction.</p><p>In conclusion, narrow buffer strips consist entirely of edge habitat. For many species the environment in buffer strips is good enough for persistence. For others, most notably bryophyte species on convex substrates, wider buffer strips are needed to ensure long-term survival. </p>

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