Devido à importância do monitoramento da composição iônica da solução do solo, no que diz respeito ao meio ambiente e ao manejo da fertirrigação, associada às limitações práticas dos métodos tradicionais de sua determinação é crescente a procura por um método confiável que possibilite o monitoramento desta composição em tempo real e em curtos intervalos de tempo. Neste sentido a TDR tem sido uma alternativa viável. O presente trabalho objetivou, pelo uso da TDR, avaliar o desempenho de sete modelos na determinação da CEw; relacioná-los com a concentração dos íons potássio nitrato e cloreto avaliando os modelos em determinar a concentração dos íons; e por fim monitorar e determinar a concentração destes íons na água lixiviada em coluna de solo não saturado. O trabalho foi divido em dois experimentos, no primeiro os modelos foram calibrados em colunas de solo sendo formado por 24 tratamentos composto por 4 faixas de umidade volumétrica e 6 concentrações da solução de KCl. Para cada coluna de solo era realizada uma leitura com a TDR ( e CEa) e a CEw na solução do solo era determinada por condutivímetro de mesa, nesta solução foram determinadas as concentrações de potássio e cloreto. No segundo experimento o mesmo procedimento foi realizado, entretanto, foi aplicado KNO3 e determinados potássio e nitrato. Desta forma, foi possível calibrar os modelos para a estimativa da CEw, e para determinação das concentrações dos íons potássio, nitrato e cloreto. Os modelos foram avaliados pelos coeficientes de determinação (R²) e exatidão (d), pela estimativa do erro padrão (EEP) e, ainda, foram classificados de acordo com o índice c, produto dos dois coeficientes citados. Os resultados mostram que os modelos de Rhoads et al. (1976) e Vogeler et al. (1996) se ajustam melhor para solos com características texturais argilosas sendo classificados como Ótimos métodos para a determinação da CEw, tanto pela aplicação de KCl como pela aplicação de KNO3 via água de irrigação. Na estimativa da CEw no solo arenoso os modelos de Munõz-Carpena et al. (2005), Mualen e Friedman (1991), Vogeler et al. (1996) e Rhoads et al. (1976) apresentam melhores ajustes na determinação da CEw, sendo classificados com Muito bom. Na determinação do potássio pelos modelos avaliados o melhor ajuste se dá pela associação da relação K-CEw do tipo potência aplicada para solos argilosos e linear para solos arenosos, apresentando classificação de: Ótimo e Muito bom, respectivamente. Para o cloreto e o nitrato o melhor ajuste se dá pela relação de CEw-Cl e CEw-NO do tipo linear, apresentando classificação de Muito Bom e Ótimo respectivamente. A TDR é uma técnica confiável no monitoramento da concentração dos íons potássio e cloreto lixiviados no perfil do solo. / There is a growing demand for a reliable method applied to monitoring ionic composition of soil solution in real-time and short time intervals, due the importance to environmental sustainability and fertigation management and limitations of traditional methods for determination. Time domain reflectometry (TDR) is often considered a viable alternative to traditional methods. Consequently, this research looks for using TDR evaluate the performance of seven mathematical models for determining electrical conductivity (CEw) by comparing simulated and measured concentrations of potassium, nitrate and chloride, and to monitor and determine the concentration of these ions in water leached from unsaturated soil columns. The research was carried out under two experiments conditions. In the first experiment the models were calibrated with input data from 24 soil columns consisting of four soils with six different KCl concentrations. For each soil column CEw was determined by both TDR ( and CEa readings) and the CEw of soil solution was determined by direct measurements of potassium and chloride concentrations. In the second experiment the procedure was the same, but with KCl being replaced with KNO3. This was possible to calibrate the models to estimate the CEw, and to determine potassium, nitrate and chloride ions concentrations. The models were ranked using the c-index, the coefficient of determination (R²) and estimated standard error (ESE). The results showed were Rhoads et al. (1976) and Vogel et al. (1996) classified as \"Great\" for the CEw determination associated with the application of both KCl and KNO3 to irrigation water in clay soils. For estimating CEw in sandy soils, the models Muñoz-Carpena et al. (2005), Mualen and Friedman (1991), Vogel et al. (1996) and Rhoads et al. (1976) were classified as \"Very Good.\" The relationship between CEw and potassium concentration was best represented by a power function in clay soils, and a linear function in sandy soils, with index of \"Great\" and \"Very Good\", respectively. For chloride and nitrate, the best fits were obtained by representing the CEw-Cl and CEw-NO3 relationships with linear functions, which were classified as Very Good and Good, respectively. TDR proved to be a reliable technique for monitoring the concentration of potassium and chloride ions leached in soil profiles.

A porção sul do Leque Aluvial do Taquari, chamada Nhecolândia, é uma sub-região do Pantanal Mato-Grossense, que apresenta um complexo sistema de lagoas arredondadas, vazantes, cordilheiras, corixos e pequenas depressões. Estudos anteriores mostraram que os fluxos de águas subsuperficiais dependem da intensidade das cheias, e da presença e forma dos horizontes verdes argilosos, localmente cimentados, que limitam fortemente a permeabilidade, e comandam os fluxos laterais. Inicialmente associados a ambientes alcalinos das salinas, esses horizontes também ocorrem em ambientes diluídos, como as pequenas depressões. O objetivo geral deste trabalho é compreender o funcionamento hídrico de três pequenas depressões, em relação com as características morfológicas dos solos. Métodos de indução eletromagnética foram utilizados para mapear a condutividade elétrica aparente (CEa); complementados por métodos de descrições das características morfológicas dos solos, e de análises granulométricas e mineralógicas em laboratório. Estes trabalhos foram complementados por análises físico-químicas das águas nas depressões; e pelo monitoramento do nível do lençol freático entre uma depressão e uma baía. O horizonte verde argiloso, mais ou menos endurecido, aparece na base das sequências de solos nas três pequenas depressões, ao qual se superpõem horizontes arenosos superficiais e subsuperficiais. As principais diferenciações morfológicas observadas referem-se aos processos de redistribuição de ferro e da matéria orgânica, ligados ao regime hídrico. No período seco, quando ocorre um rebaixamento do nível freático, o horizonte verde argiloso funciona como uma soleira e fragmenta o lençol, que passa a funcionar como dois segmentos, um ligado à Depressão Fechada, e outro à Baía. Ao longo do ano, a Depressão Fechada acumula água apenas temporária e fugazmente. Na maior parte do tempo, ela funciona como área dispersora de água às unidades morfológicas adjacentes, salientando sua importância funcional na Nhecolândia. / The southern part of the Taquari alluvial fan, called Nhecolândia, is a sub-region of the Pantanal of Mato-Grosso exhibiting a complex of round shape lakes, draining fields, forested sandy areas, small watercourses and small depressions. Former studies have shown that the sub-superficial water fluxes depend on the intensity of the flood and on the presence and shape of a sandy clay loam greenish horizon, locally cemented, which acts as an impervious layer and drives lateral fluxes. Although its presence has always been associated to the alkaline-saline parts of this singular landscape, it also occurs below small freshwater depressions. The objective of this study is to understand the hydrological functioning of these small depressions in relation to the soil cover layout. Electromagnetic induction methods were used to draw apparent electrical conductivity (CEa) maps, crossed with direct auger holes and pits observations, and laboratory analysis (grain size distribution and mineralogy). Physico-chemical analysis of the ground water in the depressions and a monitoring of the groundwater fluctuation along one year were also performed. The greenish horizon, more or less cemented, occurred at the base of the soil system in all the studied depressions. It was overlaid by more sandy horizons. The main pedological differentiation was organic matter and iron redistribution along the soil sequences, in relation with the hydrological regime. During the dry season, the watertable goes down and the greenish horizon acts as a threshold, disconnecting various watertables in the different parts of the landscape. Along the year, the closed depressions accumulate the water only temporarily and fleetingly. Most of the time, they work as areas of water redistribution towards the surrounding landscape units, and therefore have a essential function in the Nhecolândia.

Ce travail propose une optimisation de la conductivité électrique transverse des composites structuraux matrice/fibres de carbone. L'influence de la fonctionnalisation électrique de l'ensimage sur la conductivité des composites est particulièrement étudiée. Des feuillets submicroniques d'argent (AgNpts) ont été élaborés en présence de citrate de sodium (TSC). Leur morphologie plane est particulièrement adaptée à une dispersion dans un ensimage. Les feuillets ont été dispersés dans une matrice modèle. Le seuil de percolation électrique des feuillets est déterminé à 5,9 %. Cette valeur est cohérente avec un facteur de forme modéré, compris entre 12 et 28. L'ensimage fonctionnalisé a ensuite été déposé sur une mèche de fibres de carbone, elle-même imprégnée par une matrice PAEK hautes performances. Avant imprégnation des fibres de carbone, des fils submicroniques d'argent ont été introduits dans la matrice PAEK. Des composites matrice-fils submicroniques d'argent/fibres de carbone avec ensimage conducteur ont été mis en œuvre. Leur conductivité électrique est élevée (7 S.m-1), alors que la fraction volumique en particules d'argent (fils et feuillets) est inférieure à 1 % en volume. / This PhD thesis deals with the optimization of transverse electrical conductivity of Thermoplastic Carbon Fiber Reinforced Polymer. The influence of an electrically conductive sizing has been investigated. Silver nanoplates (AgNpts) have been successfully synthesized by a soft chemical reduction, with trisodiumcitrate (TSC) as surfactant. Silver nanoplates have been dispersed into a model matrix, percolation threshold has been determined near 5.9 % in volume fraction. This value is consistent with their moderate aspect ratio (between 12 and 28). Size and morphology of silver nanoplates are suitable for their dispersion in the sizing. Carbon fiber has been coated with conductive sizing. Carbon fiber will be further impregnated by a PAEK thermoplastic matrix. A higher conductivity level has been achieved by introducing silver nanowires in the PAEK matrix. Structural composites consisting of matrix-silver nanowires / continuous carbon fiber sized with conductive sizing have been elaborated. Their electrical conductivity reached 7 S.m-1 for a total silver volume fraction of 1 %.vol.

The use of remote sensing techniques can eliminate the need for extensive sampling in the field, reducing the cost of sampling and increase the accuracy of the results. In this context, the present study had the following objectives: I-evaluate the effectiveness of an optical sensor for determining the nitrogen nutritional status of cotton crop subjected to different doses of N and correlate with the crop yield. II- to determine the electrical conductivity in two fields of classification Oxisols by using a sensor and relate this index with other chemical soil parameters and productivity of corn. Regarding the first objective, the experiment was conducted in the agricultural year of 2012/13 on a Oxisol with the cotton crop. The experimental design was a randomized block design with seven treatments and three replications. Treatments consisted of the following N rates: 0, 45, 90, 130, 150, 180 and 220 kg ha-1 applied at 43 days after sowing (DAS). The vegetation index readings were taken at three different times, corresponding to 63, 75 and 97 DAE with the optical sensor N-Sensor ALS ® (YARA). Concerning the objective II electrical conductivity was evaluated of two areas using the Veris ® 3100 sensor to depths of 0-30 cm and 0-90 cm. The evaluations were conducted in the agricultural year 2012/13, the cultivated culture, in both areas, was the corn. Chemical parameters of the soil and the electrical conductivity were compared by method of multiple regression 'stepwise'. Regarding the first objective, the vegetation index reading by sensor showed high correlation with N rates in three stages evaluated, this correlation was also found with the parameters plant height, dry matter and N absorbed. The highest yield of cotton was achieved with rate of 152 kg ha-1 of N. Regarding the objective II, the EC of Area 1, for 0-30 cm layer, was explained by factors V% and Mg and in the layer of 0-90 cm by SB factor. For Area II, the EC in the 0-30 cm layer, was explained by clay contente, CTCpH7,0 and SB and for 0-90 cm layer by clay content. Increasing productivity of Area 1 showed a quadratic fit with increasing EC at both depths evaluated, in Area 2 increased productivity correlated linearly with increasing EC at both depths. / O uso de técnicas de sensoriamento remoto pode eliminar a necessidade de extensivas amostragens na lavoura diminuindo o custo da amostragem além de aumentar a acurácia dos resultados obtidos. Nesse contexto, o presente trabalho teve os seguintes objetivos: I- avaliar a eficácia de um sensor óptico na determinação do estado nutricional nitrogenado na cultura do algodoeiro submetido a diferentes doses de N e correlacionar com a produtividade da cultura. II- determinar a condutividade elétrica em duas áreas de classificação Latossolos, através do uso de sensor e relacionar esse índice com os demais parâmetros químicos do solo e com a produtividade da cultura do milho. Em relação ao objetivo I, o experimento foi conduzido no ano agrícola de 2012/13 em um Latossolo Vermelho Amarelo com a cultura do algodoeiro. O Delineamento experimental foi em blocos ao acaso, com sete tratamentos e três repetições. Os tratamentos consistiram das seguintes doses de N: 0, 45, 90, 130, 150, 180 e 220 kg ha-1 aplicados aos 43 dias após semeadura (DAS). As leituras de índice de vegetação foram realizadas em três épocas, correspondentes aos 63, 75 e 97 DAE com o sensor óptico N-Sensor ALS® (YARA). Em relação ao objetivo II foi avaliada a condutividade elétrica de duas áreas com uso do sensor Veris® 3100, para as profundidades de 0-30 cm e 0-90 cm. As avaliações foram realizadas no ano agrícola de 2012/13 e a cultura cultivada, em ambas as áreas, foi a do milho. Os parâmetros químicos do solo e a condutividade elétrica foram comparados pelo método de regressão múltipla do tipo stepwise‟. Sobre o objetivo I, a leitura do índice de vegetação do sensor apresentou alta correlação com as doses de N nos três estágios avaliados, essa correlação também foi verificada com os parâmetros altura de planta, massa seca e N absorvido. A maior produtividade da cultura do algodão foi alcançada com a dose de 152 kg ha-1 de N. Com relação ao objetivo II, a CE da Área 1 para a camada de 0-30 cm foi explicada pelos fatores V% e Mg e para a camada de 0-90 cm pelo fator SB. Para a Área II a CE na camada de 0-30 cm foi explicada pela argila, CTCpH7,0 e SB e para a camada de 0-90 cm pelo teor de argila. O aumento da produtividade da Área 1, apresentou ajuste quadrático com o aumento da CE em ambas as profundidades avaliadas, já na Área 2, o aumento da produtividade se correlacionou linearmente com o aumento da CE em ambas as profundidades.

Three-dimensional graphene foam (3D GrF) is an interconnected, porous structure of graphene sheets with excellent mechanical, electrical and thermal properties, making it a candidate reinforcement for polymer matrices. GrF’s 3D structure eliminates nanoparticle agglomeration and provides seamless pathways for electron travel. The objective of this work is to fabricate low density GrF reinforced epoxy composites with superior mechanical and electrical properties and study the underlying deformation mechanisms. Dip coating and mold casting fabrication methods are employed in order to tailor the microstructure and properties. The composite’s microstructure revealed good interfacial interaction. By adding mere 0.63 wt.% GrF, flexural strength was improved by 56%. The addition of 2 wt.% GrF showed a surge in glass transition temperature (56oC), improvement in damping behavior (150%), and electrical conductivity 11 orders of magnitude higher than pure epoxy. Dip coated and mold casted composites showed a gauge factor of ~2.4 indicating electromechanically robust composite materials.

The cold test is one of the oldest and most acceptable vigour tests as it is used to simulate stress conditions commonly occurring in the field. In recent years, some of South Africa’s top maize hybrids, with high cold test scores, have shown emergence problems under cold, wet planting conditions. It resulted in major complaints from commercial maize producers with sizable claims involved. Therefore, the need arose to find a more sensitive vigour test that takes into account cold, wet conditions. In practice, South African maize producers would not plant if it is too cold and wet. However, cold, wet conditions are commonly experienced during planting time in the main maize production regions of South Africa, especially during October and even November. Furthermore, in most of the commercial maize production areas, such as the western Free State, chances of thunder and hailstorms are high during the planting period. These weather conditions are major causes for sudden drops in temperature and flooding which can expose maize seed and emerging maize seedlings to stress conditions The effects of cold, wet conditions on germination and emergence of nine maize hybrids were investigated in laboratory, glasshouse and field experiments. Growth chamber and glasshouse experiments were conducted under 10°C, 20°C and 30°C and 0, 24, 48 and 72 hours flooding. Field experiments were conducted under different climatic conditions, resulting in cool and wet, cold and wet and favourable conditions during planting. The objectives were to investigate the correlations between different laboratory vigour tests and field emergence of maize hybrids under cold, wet conditions in order to identify the most suitable laboratory vigour test for predicting field emergence under cold, wet conditions. Eight different vigour tests were conducted and each was compared with field emergence under cold, wet conditions. The eight tests conducted, were the cold test, soak test, complex stressing vigour test, electrical conductivity test, accelerated ageing test, tetrazolium test, fast green test and emergence rate test. The soak test was the most sensitive vigour test when considering cold, wet conditions, as it measures seed germination, based on the warm test, after a 48 hour soak in water at 27°C. Correlations found between the soak test and field emergence (53%) under cold, wet conditions was unexpected, since the soak test does not account for low temperatures. The complex stressing vigour test was conducted to study the effect of fluctuating soaking temperatures on germination of maize seed. Seeds of nine maize hybrids were soaked for 48 hours at a moderate temperature (25°C), followed by another 48 hours soak at a low temperature (5°C), and then planted in sand and grown for 4 days at 25°C, before evaluation. Highly significant correlations were found between the complex stressing vigour test and simulated field emergence under both controlled conditions in a glasshouse (89.9%) and cold, wet conditions in the field (90.0%). The complex stressing vigour test was the best test to predict field performance under a wide range of climatic conditions, especially cold, wet conditions. Implementation of the complex stressing test as a routine vigour test, will be to the advantage of maize seed companies, especially in being proactive in predicting emergence of maize hybrids under cold, wet conditions. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Plant Production and Soil Science / unrestricted

L’étude du comportement des composantes des intérieurs planétaires dans des conditions extrêmes de pression (megabar) et température (milliers de Kelvin) est essentielle afin de construire des modèles fiables décrivant l’évolution et la structure des planètes. Dans ce travail, nous avons étudié plusieurs composantes par compression par choc laser sur les installations LULI2000 (France) et GEKKO XII (Japon).Nous avons employé des chocs décroissants pour étudier des conditions de haute-pression / haute-température. Afin d’accéder à des conditions de température modérée, nous avons utilisé des techniques de pre-compression statique (couplage compression par choc — cellules à enclumes de diamant) et dynamique (génération de doubles chocs).Nous avons étudié l’équation d’état des mélanges eau-ethanol-ammoniac et de l’eau et ammoniac purs, d’intérêt pour la description des intérieurs des planètes géantes de glace. L’étude de l’ammoniac a été particulièrement délicate en raison de sa forte réactivité et donc de la complexité du design des cibles ; nous présentons les premières données obtenues par choc laser, dans un domaine de pression jamais exploré. Les données des mélanges confirment des calculs ab initio récents basés sur une approximation de mélange linéaire.Nous avons également mesuré la réflectivité des mélanges liquides et de la silice, une composante-clé des intérieurs des planètes terrestres. Nous avons ensuite estimé la conductivité électrique — un paramètre crucial pour modéliser la génération des champs magnétiques planétaires dans les intérieurs via un mécanisme dynamo — de ces composantes.Eau, ammoniac et mélanges eau-ethanol-ammoniac affichent des réflectivités différentes, ce qui suggère que l’eau pure ne peut pas être considérée comme représentative des mélanges planétaires dans les modèles dynamo.Par ailleurs, nous avons apporté une confirmation expérimentale de calculs ab initio récents selon lesquels la conductivité de la silice n’est pas monotone le long d’une ligne isotherme pour des températures modérées.Nos données supportent des calculs qui prédisent qu’une dynamo peut avoir lieu dans les océans de magma dans des super-Terres ainsi que dans la jeune Terre. / Characterising the behaviour of planetary interiors’ components at extreme conditions (megabar pressures, temperatures of a few thousand Kelvin) is essential to build reliable models describing the evolution and structure of planets. In this thesis, we investigated various components on a wide set of conditions using laser-driven shock compression techniques at the LULI2000 (France) and GEKKO XII (Japan) facilities.Single decaying shocks were employed to study high-pressure / high-temperature states. To reach moderate-temperature conditions, closer to planetary interior profiles, we employed static and dynamic pre-compression techniques coupling Diamond Anvil Cells to shock compression and generating double shocks, respectively.We studied the equation of state of water-ethanol-ammonia mixtures and of pure liquid water and ammonia, of interest for icy giant structure models. Pure ammonia measurements have been particularly challenging due to cell design complexity in reason of its reactivity; we provide the first data obtained with laser shocks, in a pressure domain up to now unexplored. Mixtures data are in agreement with recent ab initio calculations based on the linear mixing approximation.We measured the optical reflectivity of liquid mixtures and silica, a key component of rocky planets’ interiors. From reflectivity data we estimated the electrical conductivity of such components — a crucial parameter for modelling the generation of planetary magnetic fields in the interiors via a dynamo mechanism.Water, ammonia, and water-ethanol-ammonia mixtures exhibit different reflectivity (hence conductivity) behaviours as a function of pressure and temperature. This suggests that pure water should not be used in dynamo models as representative of the icy mixtures.Moreover, we provide the first experimental confirmation of recent ab initio studies showing that the conductivity of silica along isothermal lines is not monotonic at moderate temperatures. Our data provide experimental support for the calculations predicting a dynamo action to occur in super-Earths’ and early Earth’s magma oceans.

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have recently emerged for potential applications in (opto-)electronics, chemiresistive sensing, and energy storage and conversion, due to their excellent electrical conductivity, abundant active sites, and intrinsic porous structures. However, developing ultrathin 2D c-MOF nanosheets (NSs) for facile solution-processing and integration into devices remains a great challenge, mostly due to unscalable synthesis, low yield, limited lateral size and low crystallinity. Here, we report a surfactant-assisted solution synthesis toward ultrathin 2D c-MOF NSs, including HHB-Cu (HHB=hexahydroxybenzene), HHB-Ni and HHTP-Cu (HHTP=2,3,6,7,10,11-hexahydroxytriphenylene). For the first time, we achieve single-crystalline HHB-Cu(Ni) NSs featured with a thickness of 4-5 nm (~8-10 layers) and a lateral size of 0.25-0.65 μm², as well as single-crystalline HHTP-Cu NSs with a thickness of ~5.1±2.6 nm (~10 layers) and a lateral size of 0.002-0.02 μm². Benefiting from the ultrathin feature, the synthetic NSs allow fast ion diffusion and high utilization of active sites. As a proof of concept, when serving as a cathode material for Li-ion storage, HHB-Cu NSs deliver a remarkable rate capability (charge within 3 min) and long-term cycling stability (90% capacity retention after 1000 cycles), superior to the corresponding bulk materials and other reported MOF cathodes.

Temporary streams and their dynamics have often been largely overseen in hydrological research and there is relatively little knowledge about how the occurrence of flow in these streams varies temporally and spatially. Temporary streams are important from a hydro- logical perspective because they affect water quantity and quality in downstream peren- nial reaches, and from an ecological perspective because they provide habitat to unique species. In order to gain knowledge about these important streams, this maser thesis was conducted, within the Msc program in Water and Environmental Engineering at Uppsala University and the Swedish University of Agricultural Sciences, in collaboration with the Hydrology and Climate group at the University of Zurich. In this study, the temporal and spatial variation of the temporary streams in a small pre-Alpine catchment in Switzerland were investigated, both in terms of the presence of flowing water and stream chemistry. The 20 ha Studibach catchment is typical for the pre-Alpine area, with frequent precipi- tation. The streams in the lower part of the Studibach catchment were mapped in the field during September 2020. The temporal and spatial variations of the presence of flow and stream chemistry within the stream network was investigated in September and October 2020 during varying weather conditions. During ten field campaigns the flow state of the streams was classified and the Electrical Conductivity (EC) of the streams was mea- sured approximately every 20 meter. The findings from the field campaigns were related to topographic indices, in particular the Topographic Wetness Index (TWI) and Upslope Accumulated Area (A), in order to see how topography influenced the presence of stream- flow and stream EC. The results show a high temporal and spatial variation in both stream chemistry and streamflow. The active network length expanded by a factor of two in re- sponse to precipitation events. The stream EC also had a large spatial variation, and the streams in the southeast part of the catchment had a higher EC than the other streams. This spatial variation is expected to reflect the large variability in groundwater EC within the catchment. The spatial variation of the streamflow demonstrated a difference between the north-middle and the south part of the catchment, where the south part responded quicker to events and drained and retracted faster after the event. The findings also indicate that topographic indices can predict the occurrence of flow in the stream network, with sites with higher topographic index values having a higher probability of flowing water in the stream. Topography also influences the stream chemistry. The variation in stream chem- istry was smaller for sites with higher values for the topographic indices, something that can be explained by the Representative Elementary Area (REA) concept, because sites with higher topographic index values are located further downstream and water at these locations is a mixture of the smaller streams that feed these streams. / Temporära bäckar och dess dynamik har länge varit förbisedda inom hydrologisk forskn- ing, och en djupgående kunskap rörande temporära och rumsliga variationer saknas. Tem- porära bäckar är viktiga utifrån ett hydrologisk perspektiv eftersom de påverkar både kvantitet och kvalitet på vattnet nedströms, och från ett ekologiskt perspektiv eftersom de bidrar med habitat till unika arter. Detta examensarbete har genomförts för att öka kunskapen kring dynamiken i dessa temporära nätverk. Examensarbetet genomfördes inom Civilingenjörsprogrammet i Miljö och Vattenteknik vid Uppsala Universitet och Sveriges Lantbruksuniversitet, i ett samarbete med Hydrologi- och Klimatgruppen vid University of Zurich. Studien har undersökt temporära och rumsliga variationer i ett tem- porärt bäcknätverk med avseende på flöden och kemin i vattnet, i ett mindre pre-alpint avrinningsområde i centrala Schweiz. Bäckarna i den nedre delen av avrinningsområdet Studibach karterades i fält för hand med karta och kompass under september 2020. Avrin- ningsområdet är på 20 ha och räknas som typiskt för ett pre-Alpint område, med frekvent nederbörd. Tio fältkampanjer genomfördes där temporära och rumsliga variationer un- dersöktes genom klassificering av flöden och mätningar av Elektrisk Konduktivitet (EC) i bäckarna ungefär var 20e meter, under september och oktober 2020 i varierande väder- förhållanden. Resultaten från fältkampanjerna relaterades till de topografiska indexen Topographic Wetness Index (TWI) och Upslope Accumulated Area (A) för att undersöka hur topografin påverkar flöden och bäckkemin. Studien kom fram till att bäckarna i den nedre delen av Studibach visar både en temporär och en rumslig variation för både flöde och bäckkemi. De aktiva bäckarna i nätverket visade på en expansion med en faktor två som svar på nederbörd. En rumslig variation för flödet påträffades även mellan den södra och nord-centrala delen av nätverket där den södra svarade snabbare mot event och även drogs ihop snabbare. Kemin i bäckvattnet visade på en stor rumslig variation, med högt EC i den sydöstra delen av avrinningsområdet, vilket förmodas bero på den stora rumsliga variationen av EC i grundvattnet. Resultaten visar även på att topografiska index kan till viss del förutspå flöden i bäckarna, där platser med högre topografiska index har högre sannolikhet att det flödar i bäcken. Topografin påverkar även bäckkemin. Variationen i bäckkemin var mindre för platser med högre topografiska index, vilket kan förklaras med Representative Elementary Area (REA) konceptet, eftersom platser med högre to- pogragiska index värden återfinns längre nedströms och vattnet på dessa platser är en blandning av de mindre bäckarna som tillför vattnet till de större.

Thin layers are widely used in many fields of technology and today we can say that they are found in all modern technologies. Thin layers can be created in two ways, namely by chemical or physical means. This work focuses on the latter method, more particularly a technology of thermal evaporation of thin layers in a vacuum. The work focuses on the process principles during and after the evaporation. Much of the work focuses on the development and design of experiments. These experiments illustrate some of the phenomena that take place on thin films produced by the aforementioned technology. Work helps to better understand processes during formation of thin layers and properties that influence the quality and stability of thin films. In conclusion we describe results of experiments and new developments in the field of thin films deposition using evaporation under vakuum are summarized.