The interconnection of molecular machines with different functionalities to form molecular communication systems can increase the number of design possibilities and overcome the limited reliability of the individual molecular machines. Artificial information exchange using molecular signals would also expand the capabilities of single engineered cell populations by providing them a way to cooperate across heterogeneous cell populations for the applications of synthetic biology and lab-on-a-chip systems. The realization of molecular communication systems necessitates analysis and design of the communication channel, where the information carrying molecular signal is transported from the transmitter to the receiver. In this thesis, significant progress towards the use of microfluidic channels to interconnect molecular transmitter and receiver pairs is presented. System-theoretic analysis of the microfluidic channels are performed, and a finite-impulse response filter is designed using microfluidic channels. The spectral density of the propagation noise is studied and the additive white Gaussian noise channel model is developed. Memory due to inter-diffusion of the transmitted molecular signals is also modeled. Furthermore, the interference modeling is performed for multiple transmitters and its impact on the communication capacity is shown. Finally, the efficient sampling of the signal transduction by engineered bacterial receivers connected to a microfluidic channel is investigated for the detection of the pulse-amplitude modulated molecular signals. This work lays the foundation for molecular communication over microfluidic channels that will enable interconnection of engineered molecular machines.

Electrolytic solutions contain mobile ions that can pass current, and are essential components of any solution-phase electrochemical system. The Nernst–Planck–Poisson equations describe the electrodynamics and transport dynamics of electrolytic solutions. This thesis applies modern numerical and mathematical techniques in order to solve these equations, and hence determine the behaviour of electrochemical systems involving charge transport. The following systems are studied: a liquid junction where a concentration gradient causes charge transport; an ideally polarisable electrode where an applied potential difference causes charge transport; and an electrochemical cell where electrolysis causes charge transport. The nanometre Debye length and nanosecond Debye time scales are shown to control charge separation in electrolytic solutions. At equilibrium, charge separation is confined to within a Debye length scale of a charged electrode surface. Non-equilibrium charge separation is compensated in solution on a Debye time scale following a perturbation, whereafter electroneutrality dictates charge transport. The mechanism for the recovery of electroneutrality involves both migration and diffusion, and is non-linear for larger electrical potentials. Charge separation is an extremely important consideration on length scales comparable to the Debye length. The predicted features of capacitive charging and electrolysis at nanoelectrodes are shown to differ qualitatively from the behaviour of larger electrodes. Nanoscale charge separation can influence the behaviour of a larger system if it limits the overall rate of mass transport or electron transfer. This thesis advocates the use of numerical methods to solve the Nernst–Planck–Poisson equations, in order to avoid the simplifying approximations required by traditional analytical methods. As this thesis demonstrates, this methodology can reveal the behaviour of increasingly elaborate electrochemical systems, while illustrating the self-consistency and generality of fundamental theories concerning charge transport.

Cette thèse porte sur la déformation et les migrations de fluides associées à la Faille Nord Anatolienne en Mer de Marmara (Turquie).Nous étudions tout d'abord l'évolution de la géométrie et du taux de glissement du système de faille, par deux approches indépendantes: - modélisation thermique de l'histoire d'un bassin, - définition d'un marqueur temporel de type Dépôt de Transport en Masse, daté par interprétation stratigraphique. Nous montrons que: -(1) le système de failles actuel, défini comme une faille principale accommodant la majorité de la déformation inter-plaque, n'a pas significativement évolué depuis 330.000 ± 100.000 ans dans la partie Ouest de la mer; -(2) le système de faille s'est progressivement réorganisé depuis 2.5-1.5 Ma.Dans un deuxième temps, nous étudions les processus d'initiation des Transports en Masse. Nous montrons que: -(1) même si les Transports en Masse sont contrôlés par des processus tectoniques (principalement les séismes et l'extension crustale), leur fréquence et leur taille sont conditionnées par les oscillations glacio-eustatiques; -(2) des Dépôts en Masse ont une périodicité corrélée aux transitions marins/lacustres. Cette cyclicité peut être expliquée par la diffusion d'eau saumâtre, dans les argiles marines entraînant leur gonflement et déstabilisant les sédiments. Dans une troisième partie, nous étudions la diversité des contextes des sites d'émissions de fluides en fonds de mer. Nous montrons que l'occurrence des sites d'émission de fluides est en partie liée au flux ascendant de gaz le long de couches perméables des bassins vers leurs bords, et le long des fractures du socle vers les bords des bassins et les anticlinaux. / This study addresses the issue on the deformation and the fluid migration, associated to the North Anatolian Fault within the Sea of Marmara (Turkey).First, we aim to constrain the evolution of the fault network and the slip rate through time, by two independent approaches: - historical thermal modeling of a basin of the Sea of Marmara; - definition of a Mass Transport Deposit as a fault lateral slip marker, and dated by stratigraphic interpretation. We show that: - (1) the present day fault system, formed by a main fault which accommodated the main part of the inter-plate deformation does not significantly evolved since 330.000 ± 100.000 years - (2) a progressive reorganization of the fault network occurred since the last 2.5-1.5 Ma.Secondly, we discuss the triggers of Mass Transport Processes. We show that: - (1) despite submarine mass movements are related to tectonic activity (mainly earthquakes and crustal stretching), their frequency and their size are also modulated by glacio-eustatic changes; -(2) remarkable Mass Transport Deposits display some cyclicity in stratigraphic sequences which are apparently correlated to transitions between salty marine and lacustrine environments. This cyclicity is perhaps explained by marine clay activity (swelling) under low brackish-fresh water conditions, which can trigger sediment destabilization.Third, we investigate the diversity of active fluid seepages contexts. We propose that the widespread occurrence of fluid expulsion sites can be explained by up-dip gas migration by buoyancy along permeable strata toward their edges, and along fractures within the basement toward both the edges of the basins and topographic highs.

Le Canal de Corse est un bassin confiné asymétrique localisé entre l’Île de Corse et l’Archipel de la Toscane, dont le flanc ouest est dominé par des processus turbiditiques et hémipélagiques et le flanc est par des mouvements en masse et des processus contouritiques. Le présent projet de doctorat a pour objectif de comprendre plus précisément les mécanismes contrôlant la formation des glissements sous-marins dans les contourites vaseuses (dépôts sédimentaires formés par les courants) pendant la période Plio-Quaternaire. Le vaste jeu de données disponible pour ce projet de doctorat inclut : la bathymétrie multifaisceaux, la sismique réflexion, les mesures géotechniques in situ, les mesures de vitesse de courant et les résultats d’un modèle hydrodynamique.Les contourites du Canal de Corse sont principalement composées de vase avec la présence de couches de sable formées par de forts courants de fond pendant les périodes de baisse du niveau marin. La croissance des dépôts contouritiques dépend de la disponibilité de sédiment fourni par le système turbiditique. Ainsi, cette croissance est lente pendant les périodes interglaciaires de haut niveau marin et rapide pendant les bas niveaux marins. Les courants contrôlent la morphologie du fond et génèrent les plastered drifts de forme convexe avec des pentes plus raides dans la partie avale, limités par une incision créée par les courants (moat). Le Pianosa Slump a été initié dans cette partie basse du plastered drift. Les moats pourraient être érodés préférentiellement pendant les périodes froides passées déclenchant ainsi certains glissements observés. Un autre facteur prédisposant l’instabilité de pente sur la Ride de Pianosa est la faiblesse d’une couche dont le comportement mécanique se caractérise par du radoucissement (perte de résistance avec le cisaillement). Cette propriété particulière est due à la présence de zéolites (produit de l’altération des roches volcaniques). Cette couche a formé la surface basale de rupture du Pianosa Slump. En conclusion, les deux principaux facteurs prédisposant la formation de glissements sous-marins sur la Ride de Pianosa sont : la morphologie du plastered drift avec une pente plus raide en aval et la couche faible composée de sédiment vaseux riche en zéolites. Le principal facteur déclenchant semble être l’érosion basale. / The Corsica Trough is an asymmetric confined basin located between the Corsica Island and the Tuscan Ar-chipelago, with the western flank dominated by turbiditic and hemipelagic processes and the eastern flank by mass transport and contouritic processes. The present PhD project aims to develop our understanding of the mechanisms that control the formation of submarine landslides within muddy contourites (sediment deposits related to bottom currents) during the Plio-Quaternary. The broad data set available for this PhD project includes: multibeam bathymetry, seismic reflection data, sediment cores, in situ geotechnical measurements, current ADCP measurements and results of a hydrodynamic model.The contourites of the Corsica Trough are mainly composed of mud with sandy layers formed by enhanced bottom currents during periods of sea level fall. The contourite drifts grow slowly during sea level high-stands and rapidly during sea level low-stands due to the high sediment availability provided by an active turbidite sys¬tem. Bottom currents control the seafloor morphology and generate plastered drifts on the slope. This is a con¬vex-shaped contourite with steep slope gradients in the lower part limited by a moat (incision created by bottom currents). The Pianosa Slump was initiated in this lower part of the plastered drift. The occurrence of continuous erosive processes during cold periods could undercut the slope and trigger submarine landslides. Another predis¬posing factor for slope instability identified is the presence of a potential weak layer with a post-peak strain soften¬ing behaviour (strength loss with increasing strain). This particular property is caused by the presence of zeolites (product of the alteration of volcanic rocks). This layer originated the basal failure surface of the Pianosa Slump.In summary, the two main factors predispose the formation of submarine landslides in the Pianosa Ridge are: the morphology of the plastered drift with steep slopes in the lower part and a potential weak layer composed of zeolitic muddy sediment. The main triggering factor seems to be undercutting by bottom currents.

A goal of the Swedish government is to increase the usage of renewable fuels and biomass-based fuels. Fuel cells, and especially the MCFC, are useful for these types of fuels. The Swedish market may benefit from the MCFC in two ways: increased efficiency of the biofuels and also utilisation of produced heat in district heating. Most of the commercial MCFC systems today are optimised for use with methane. The possibility to utilise biomass in Sweden makes it important to study how the MCFC may be adapted or optimised for good performance and low degradation with gas produced from biomass or other renewable fuels. This thesis is focused on methods that may be used to investigate and evaluate MCFC electrodes and electrolytes with renewable fuels i.e. CO2-containing gases. The methods and results are both experimental and mathematically modelled. The objectives of this thesis are to better understand how the performance of the anode is dependent on different fuels. Anode kinetics and the water-gas shift reaction have been investigated as well as the possibility to increase cell lifetime by increasing the initial electrolyte amount by having the anode as a reservoir. The effect of segregation of cations in the electrolyte during operation has also been studied. It was found that if the gas composition at the current collector inlet is in equilibrium according to the water gas-shift reaction the gas composition inside the electrode is almost uniform. However, if the gas is not in equilibrium then the concentration gradients inside the current collector have a large effect on the gas composition inside the electrode. The conversion of the gas in the gas flow channels according to the water-gas shift reaction depends on the gas flow rate. For an anode used in a gas mixture of humidified hydrogen and carbon dioxide that are not in equilibrium some solubility of Ni in a (Li/Na)2CO3 mixture was found. To have the anode act as an electrolyte reservoir to prolong cell lifetime the anode pore size should be carefully matched with that of the cathode and a bimodal pore-size distribution for the anode is preferable to have as good performance as possible for as large electrolyte filling degree interval as possible. Modelling results of segregation of cations in the electrolyte during operation indicate that the electrolyte composition changes during operation and that the lithium ions are enriched at the anode for both types of electrolyte used for the MCFC. The electrolyte composition changes are small but might have to be considered in long-time operation. The results from this thesis may be used to better understand how the MCFC may be used for operation with renewable fuels and how electrodes may be designed to prolong cell lifetime. / Ett av den svenska regeringens mål är att öka användandet av förnyelsebara bränslen och bränslen från biomassa. Bränsleceller och framförallt MCFC är användbara för dessa typer av bränslen. Den svenska marknaden kan dra fördelar av MCFC på två sätt; ökad bränsleutnyttjandegrad och utnyttjande av producerad värme för fjärrvärme. De flesta kommersiella MCFC-systemen idag är optimerade för användning av metan. Möjligheten att använda biomassa på den svenska marknaden gör det viktigt att studera hur MCFC kan anpassas eller optimeras för bra prestanda och låg degradering för användning med gas från biomassa eller andra förnyelsebara bränslen. Fokus i denna avhandling är på metoder som kan användas för att undersöka och utvärdera MCFC-elektroder och -elektrolyter med förnyelsebara bränslen, dvs. gaser innehållande CO2. Metoderna och resultaten är både experimentella och matematiskt modellerade. Målet med denna avhandling är att bättre förstå hur anodens prestanda beror på användningen av olika bränslen. Anodens kinetik och vattengasskiftreaktionen har studerats liksom möjligheten att förlänga cellens livstid genom att öka den initiala mängden elektrolyt medelst användning av anoden som reservoar. Effekten av segregation av katjoner i elektrolyten under last har också undersökts. Om gassammansättningen är i jämvikt enligt vattengasskiftreaktionen vid inloppet till strömtilledaren kommer gassammansättningen att vara nära uniform inuti elektroden. Om ingående gas inte är i jämvikt kommer stora koncentrationsgradienter uppkomma i strömtilledaren och påverka gassammansättningen i elektroden. Omsättningen med avseende på vattenskiftreaktionen av gasen i flödeskanalen verkar vara beroende av gasens flödeshastighet. För en anod som används i en uppfuktad blandning av vätgas och koldioxid som inte är i jämvikt befanns det att Ni har en viss löslighet i (Li/Na)2CO3. För att kunna använda anoden som reservoar för elektrolyt för att förlänga livstiden för MCFC skall anodens porstorleksfördelning överensstämma med katodens och ha en bimodal porstorleksfördelning för att ge en tillräckligt god prestanda i ett så stort elektrolytfyllnadsgradsintervall som möjligt. Modelleringsresultat för segregering av katjoner i elektrolyten under drift visar att litiumjoner anrikas i anoden för båda typerna av elektrolyt som används i MCFC. Elektrolytkoncentrationsförändringarna är små men kan behövas tas i beaktande vid långa driftstider. Denna avhandlings resultat kan användas för att bättre förstå hur MCFC skall anpassas för drift med förnyelsebara bränslen och hur elektroder kan utformas för att förlänga livstiden. / QC 20100630

The topic of this thesis is the degradation of fuel cell electrodes in proton exchange membrane fuel cells (PEMFCs). In particular, the degradation associated with localized fuel starvation, which is often encountered during start-ups and shut-downs (SUs/SDs) of PEMFCs. At SU/SD, O2 and H2 usually coexist in the anode compartment. This situation forces the opposite electrode, i.e. the cathode, to very high potentials, resulting in the corrosion of the carbon supporting the catalyst, referred to as carbon corrosion. The aim of this thesis has been to develop methods, materials and strategies to address the issues associated to carbon corrosion in PEMFC.The extent of catalyst degradation is commonly evaluated determining the electrochemically active surface area (ECSA) of fuel cell electrode. Therefore, it was considered important to study the effect of RH, temperature and type of accelerated degradation test (ADT) on the ECSA. Low RH decreases the ECSA of the electrode, attributed to re-structuring the ionomer and loss of contact with the catalyst.In the search for more durable supports, we evaluated different accelerated degradation tests (ADTs) for carbon corrosion. Potentiostatic holds at 1.2 V vs. RHE were found to be too mild. Potentiostatic holds at 1.4 V vs. RHE were found to induce a large degree of reversibility, also attributed to ionomer re-structuring. Triangle-wave potential cycling was found to irreversibly degrade the electrode within a reasonable amount of time, closely simulating SU/SD conditions.Corrosion of carbon-based supports not only degrades the catalyst by lowering the ECSA, but also has a profound effect on the electrode morphology. Decreased electrode porosity, increased agglomerate size and ionomer enrichment all contribute to the degradation of the mass-transport properties of the cathode. Graphitized carbon fibers were found to be 5 times more corrosion resistant than conventional carbons, primarily attributed to their lower surface area. Furthermore, fibers were found to better maintain the integrity of the electrode morphology, generally showing less degradation of the mass-transport losses. Different system strategies for shut-down were evaluated. Not doing anything to the fuel cell during shut-downs is detrimental for the fuel cell. O2 consumption with a load and H2 purge of the cathode were found to give around 100 times lower degradation rates compared to not doing anything and almost 10 times lower degradation rate than a simple air purge of the anode. Finally, in-situ measurements of contact resistance showed that the contact resistance between GDL and BPP is highly dynamic and changes with operating conditions. / Denna doktorsavhandling behandlar degraderingen av polymerelektrolytbränslecellselektroder. polymerelektrolytbränslecellselektroder. Den handlar särskilt om nedbrytningen av elektroden kopplad till en degraderingsmekanism som heter ”localized fuel starvation” oftast närvarande vid uppstart och nedstängning av bränslecellen. Vid start och stopp kan syrgas och vätgas förekomma samtidigt i anoden. Detta leder till väldigt höga elektrodpotentialer i katoden. Resultatet av detta är att kolbaserade katalysatorbärare korroderar och att bränslecellens livslängd förkortas. Målet med avhandlingen har varit att utveckla metoder, material och strategier för att både öka förståelsen av denna degraderingsmekanism och för att maximera katalysatorbärarens livslängd.Ett vanligt tillvägagångsätt för att bestämma graden av katalysatorns degradering är genom mätning av den elektrokemiskt aktiva ytan hos bränslecellselektroderna. I denna avhandling har dessutom effekten av temperatur och relativ fukthalt studerats. Låga fukthalter minskar den aktiva ytan hos elektroden, vilket sannolikt orsakas av en omstrukturering av jonomeren och av kontaktförlust mellan jonomer och katalysator.Olika accelererade degraderingstester för kolkorrosion har använts. Potentiostatiska tester vid 1.2 V mot RHE visade sig vara för milda. Potentiostatiska tester vid 1.4 V mot RHE visade sig däremot medföra en hög grad av reversibilitet, som också den tros vara orsakad av en omstrukturering av jonomeren. Cykling av elektrodpotentialen degraderade istället elektroden irreversibelt, inom rimlig tid och kunde väldigt nära simulera förhållandena vid uppstart och nedstängning.Korrosionen av katalysatorbäraren medför degradering av katalysatorn och har också en stor inverkan på elektrodens morfologi. En minskad elektrodporositet, en ökad agglomeratstorlek och en anrikning av jonomeren gör att elektrodens masstransportegenskaper försämras. Grafitiska kolfibrer visade sig vara mer resistenta mot kolkorrosion än konventionella kol, främst p.g.a. deras låga ytarea. Grafitiska kolfibrer visade också en förmåga att bättre bibehålla elektrodens morfologi efter accelererade tester, vilket resulterade i lägre masstransportförluster.Olika systemstrategier för nedstängning jämfördes. Att inte göra något under nedstängning är mycket skadligt för bränslecellen. Förbrukning av syre med en last och spolning av katoden med vätgas visade 100 gånger lägre degraderingshastighet av bränslecellsprestanda jämfört med att inte göra något alls och 10 gånger lägre degraderingshastighet jämfört med spolning av anoden med luft. In-situ kontaktresistansmätningar visade att kontaktresistansen mellan bipolära plattor och GDL är dynamisk och kan ändras beroende på driftförhållandena. / <p>QC 20131104</p>

Mechanical ventilation can be a life saving treatment. However, due to the inhomogeneous and anisotropic behavior of the lung tissue, ventilation can also lead to overdistensions of lung regions whereas other areas remain even collapsed. A first step is a more comprehensive understanding of the flow mechanics under normal breathing conditions in a healthy lung as well as for a diseased, collapsed lung. This is the aim of this work. Therefore, a realistic model of the upper human airways has been generated at which experimental and numerical investigations could be carried out. Experimentally, the flow was analyzed by means of Particle Image Velocimetry (PIV) measurements which revealed new details about the flow patterns occurring during different ventilation frequencies. Numerical results were in good agreement with the experimental results and could provide new details about the three-dimensional flow structure and emerging secondary flow within the upper airways. The study of reopening of collapsed airways has shown that larger frequencies lead to airway reopening without overdistension of already open parts. Higher frequencies also lead to homogenization of mass flow distribution within the human lung. / Künstliche Beatmung ist meist eine lebensrettende Maßnahme. Aufgrund der räumlich anisotropen und inhomogenen Eigenschaften der Lunge kann die Beatmung jedoch auch zu einer Schädigung der Lunge führen. Daraus ergibt sich die Forderung einer „Protektiven Beatmung“. Ein erster Schritt dahingehend ist ein verbessertes Verständnis der Atmung und Beatmung am Beispiel der gesunden sowie kranken, teilweise kollabierten Lunge. Dies ist das Ziel der Arbeit. Hierfür wurde ein realistisches Modell der oberen Atemwege (Tracheobronchialbaum) angefertigt. An diesem Modell können sowohl experimentelle als auch numerische Untersuchungen durchgeführt werden. Experimentell wurde die Strömung mittels Particle Image Velocimetry (PIV) untersucht, wobei neue Details bezüglich der auftretenden Strömungsmuster für unterschiedliche Frequenzen gefunden wurden. Numerische Strömungsberechnungen stimmen gut mit den experimentellen Ergebnissen überein. Dreidimensionale Strömungsstrukturen sowie die Entwicklung von Sekundärwirbeln in der Lunge konnten erklärt werden. Eine Studie am kranken, teilweise kollabierten Lungenmodell zeigte, dass mit steigender Frequenz kollabierte Bereiche wiedereröffnet werden können. Höhere Frequenzen führen weiterhin zu einer Homogenisierung der Massenstromverteilung in der Lunge.

The organotin compound tributyltin (TBT) has been used as a biocide on boats for anti-fouling paint and has been banned 1993 on all boats in Sweden. Storage sites for boats are therefore a contamination source, hull scraping and painting contribute to littering and spread to the waterbodies ultimately accumulating in Brunnsviken’s sediments. TBT is toxic in very small amounts for organism’s nerve-, immune- and production system and therefore becomes a threat to the bays ecosystem. The concentration of TBT in Brunnsviken’s sediments exceed acceptable threshold levels of what is considered hazardous to the environment. TBT bind to sediments and particles and are transported by the water currents, it is therefore of great importance to know the flow dynamics in Brunnsivken to get a larger understanding for the spread and accumulation of TBT. The origin and dissemination of TBT have to be evaluated for the right action to be made. According to new directive from EU, all surface waters must reach good chemical status. Whit in the frame of this Bachelor thesis and on behalf of the environmental administration Stockholm City, a field study has been conducted, regarding Brunnsviken’s water dynamics. The aim has been to see if a flow pattern could be found and explain the spread and high levels of the pollution of TBT in the northern parts of Brunnsviken’s sediments. Field investigations have been conducted using sonde and current floater in order to determine the stratification of water bodies and their propensity to behave vertically based on temperature, salinity and turbity. A second parameter was also considered in order to account for flow velocity and flow direction. High-resolution measurements were performed at 11 transects in Brunnsviken to determine if there are any geographical differences that could account for the spread of TBT. Calculations were made regarding volumetric flow, transport time and mass load at each transect, which was subsequently compared to turnover time previously established by the Swedish Metrological and Hydrological Institute (SMHI) and previous studies by Karlsson (2016) with longer time reference were used, in order to corroborate the momentary high-resolution results from this study, by integrating them into a broader perspective. The results elucidate geographical variations in different water bodies in regards to temperature, salinity and turbidity. A pronounced stratification was identified in waterbodies located in the southern- and middle parts of the bay, whereas the northern part was less well defined as stratified, indicative of a more homogenous water body. The direction of flow appeared to move toward Brunnsivken’s central region with a relatively uniform flow velocity throughout the bay. No conclusions regarding a spread of TBT form south to north have been drawn. This is because the narrowest point in Brunnsviken, which separates the north form the south, have the lowest transport time and mass transport values. However, interactions of water bodies with different origins seems play an important role in the central parts of the bay and mixing in the northern regions has been found, which may explain the spread of suspended matter and TBT between the central and northern parts. Proposal of further studies has been made in order to get a better understanding of the high level of TBT in the northern parts of Brunnsivken, providing preliminary evidence where the result of this study can be used as a foundation. / Den organiska tennföreningen tributyltenn (TBT) har används som biocid i båtbottenfärger och är sedan 1993 helt förbjuden i Sverige. Båtuppläggningsplatser ses som en föroreningskälla i och med skrovskarpning och bottenfärgmålning, vars spill sprids vidare till Brunnsvikens vatten och avsätts i dess bottensediment. TBT är ett hormonstörande ämne som är skadlig för organismers nervsystem, immunförsvar och fortplantningssystem vid mycket små koncentrationer och ses därför som ett hot mot vikens ekosystem. Halten TBT i Brunnsvikens sediment överstiger de Svenska riktvärdena för kemisk status. Vattnets strömningsförhållanden är därför viktiga att förstå då de påverkar transporten och avsättningen av sediment och partikelbundet TBT. Dess ursprung och spridning måste därför undersökas för att rätt åtgärder skall kunna framtas för att nå god kemisk status till år 2027, i enlighet med EUs ramdirektivför vatten (2000/60/EC). Inom ramen för detta kandidatarbete och på uppdrag av miljöförvaltningen i Stockholm stad, har en fältstudie utförts gällande Brunnsvikens vattendynamik för att se om det förekommer strömningsmönster som kan förklara spridningen och de svårförklarade höga halterna av TBT i vikens norra delar. Fältundersökningar har utförts där sond- och strömkors har använts för att ta reda på hur skiktningen i vattenmassorna ser ut för att vidare kunna beräkna strömningshastigheter och flödesriktning i de olika vattenmassorna. Högupplösta mätningar utfördes längs 11 transekter i Brunnsviken för att se om det förekommer geografiska skillnader i vattenmassorna som kan förklara spridningen av TBT. Enklare överslagsberäkningar utfördes gällande vattenföring, transporttid och masstransport vid vardera transekt. Beräkningar gällande vattenföring och transporttider har kompletterats med omsättningstider från Sveriges metrologiska och hydrologiska institut (SMHI) och tidigare utredningar av Karlsson (2016) med längre tidupplösning, för att bädda in de egna mätningarna i ett bredare perspektiv och för att se om dessa kan stödja de momentana resultaten från denna studie. Vid mättillfällena observerades variationer i vattenmassorna i de olika delarna i viken gällande temperatur, salinitet och tubiditet, med en tydligare skiktning i vikens södra och mellersta delar jämfört med de norra delarna. Strömningsriktningen ser ut att röra sig mot vikens mellersta delar, vilket möjligen kan förklaras av utpumpning av vatten som sker i dessa områden. Hastigheterna är relativt jämn i hela viken förutom i de norra delarna. Baserat på resultaten i denna studie, har inga slutsatser gällande spridning från söder till norr har kunnat göras då vikens smalaste delar som även separerar delarna åt visar sig ha lägsta transporttiderna och masstransporterna. Det har dock hittats interaktioner mellan ett möjligt möte av vattenmassor i vikens mellersta delar och en effektiv omblandning i vikens norra delar som skulle kunna förklara en spridning av suspenderat material och där med TBT från de mellersta till de norra delarna. Förslag på fortsatta studier har gjorts för att kunna få en större förståelse för de höga halterna av TBT i vikens norra delar, där resultat från denna studie kan användas som underlag.

Le champ électrique d'une puissance suffisante peut provoquer une augmentation de conductivité et perméabilité de la membrane cellulaire. L'effet est connu comme l'électroporation, attribuée à la création de voies aqueuses dans la membrane. Quantifier le transport de la matière dans le cadre d'électroporation est un objectif important. Comprendre ces processus a des ramifications dans l’extraction du jus ou l’extraction sélective des composés de cellules végétales, l'amélioration de l'administration de médicaments, et des solutions aux défis environnementaux. Il y a un manque de modèles qui pourraient être utilisés pour modéliser le transport de la matière dans les structures complexes (tissus biologiques) par rapport à l'électroporation. Cette thèse présente une description mathématique théorique (un modèle) pour étudier le transport de la matière et le transfert de la chaleur dans tissu traité par l’électroporation. Le modèle a été développé en utilisant les lois de conservation et de transport et permet le couplage des effets de l'électroporation sur la membrane des cellules individuelles au transport de la matière ou la chaleur dans le tissu. Une solution analytique a été trouvée par une simplification, mais le modèle peut être étendu avec des dépendances fonctionnelles supplémentaires et résolu numériquement. La thèse comprend cinq articles sur l'électroporation dans l'industrie alimentaire, la création de modèle pour le problème de diffusion, la traduction du modèle au problème lié à l’expression de jus, validation du modèle, ainsi que des suggestions pour une élaboration future du modèle. Un chapitre supplémentaire est dédié au transfert de la chaleur dans tissu. / An electric field of sufficient strength can cause an increase of conductivity and permeability of cell membrane. Effect is known as electroporation and is attributed to creation of aqueous pathways in the membrane. Quantifying mass transport in connection with electroporation of biological tissues is an important goal. The ability to fully comprehend transport processes has ramifications in improved juice extraction and improved selective extraction of compounds from plant cells, improved drug delivery, and solutions to environmental challenges. While electroporation is intensively investigated, there is a lack of models that can be used to model mass transport in complex structures such as biological tissues with relation to electroporation. This thesis presents an attempt at constructing a theoretical mathematical description – a model, for studying mass (and heat) transfer in electroporated tissue. The model was developed employing conservation and transport laws and enables coupling effects of electroporation to the membrane of individual cells with the resulting mass transport or heat transfer in tissue. An analytical solution has been found though the model can be extended with additional dependencies to account for the phenomenon of electroporation, and solved numerically. Thesis comprises five peer-reviewed papers describing electroporation in the food industry, model creation for the problem of diffusion, translation of the model to the mathematically-related case of juice expression, model validation, as well as suggestions for possible future development, extension, and generalization. An additional chapter is dedicated to transfer of heat in tissue.

Au cours de ce travail de thèse, des matériaux monomères amorphes bifonctionnels photochromes et fluorescents ont été élaborés et étudiés dans le but de former sous irradiation interférentielle des structures fluorescentes par migration de matière photoinduite . Pour contrer le phénomène d'extinction de fluorescence par l'unité photochrome azoïque, un espaceur saturé de type adduit de Diels-Alder a été introduit entre les deux entités photoactives. De telles molécules ont été obtenues avec succès ainsi que les composés modèles azoïques et fluorescents correspondants.L'introduction de nouveaux fragments comme l'espaceur ne modifiait pas les propriétés de photochromisme que ce fût en solution ou à l'état solide. A l'opposé, des études de spectroscopie de fluorescence stationnaire et résolue en temps ont montré que la présence de cet espaceur limitait efficacement les phénomènes d’extinction de fluorescence au sein des composés bifonctionnels. Dans le but de comprendre les mécanismes photophysiques sous-tendant l'extinction de fluorescence observée, des expériences de spectroscopie d'absorption transitoire femtoseconde ont été réalisées sur les composés modèles et bifonctionnels. Elles ont mis en évidence l’existence d’un transfert d’énergie électronique picoseconde de l’unité fluorescente vers l’unité photochrome.Sous forme de films minces non-dopés, ces nouveaux composés bifonctionnels ont conduit par photostructuration holographique à des reliefs de surface réinscriptibles, stables à température et sous lumière ambiantes et modulés en intensité de fluorescence, les maxima d'émission correspondant aux zones d'accumulation en composés bifonctionnels. Une nouvelle réaction photochimique consistant en la photocoupure de dérivés fluorescents nitrés de la triphénylamine a été mise en évidence. L’irradiation sous UV de solutions et de films minces provoquait une photorupture de l’état à transfert de charge intramoléculaire, conduisant à la modification de la couleur émise de l’orange au bleu. Des structures fluorescentes modulées en énergie ont pu ainsi être obtenues par irradiation au travers d’un masque tout en contrôlant la quantité de lumière apportée. / This PhD thesis presents the elaboration and the studies of bifunctional amorphous small molecule-based materials combining photochromic and fluorescent units in order to form fluorescent patterns by photoinduced mass transport under interferential irradiation A saturated spacer made of a Diels-Alder adduct was introduced between both photoactive units to inhibit emission quenching of the fluorophore by the azo photochromic moiety. Such compounds as well as their fluorescent and azo model compounds have successfully been synthesised.New fragments such as the spacer brought no modification to the photochromic properties in solution and in the solid state. Conversely, time-resolved and steady-state fluorescence studies showed that the spacer efficiently limited fluorescence quenching within the bifunctional compounds. In order to gain insight into the mechanism responsible for the fluorescence quenching, femtosecond transient absorption spectroscopy measurements have been performed on model and bifunctional compounds. They evidenced picosecond electronic energy transfer from the fluorescent unit towards the azo moiety.As non doped thin films, rewritable surface relief gratings (SRG) stable under ambient light and at room temperature could be written through holographic illumination and displayed fluorescence patterns. Modulation of the emission intensity resulted from the accumulation of fluorophores attached to the azo units undergoing photoinduced mass migration. A novel photochemical reaction leading to the photocleavage of fluorescent nitro-substituted triarylamine derivatives has been proved. UV irradiation in solution and in the solid state caused photodisruption of the intramolecular charge transfer state, yielding neat modification of the emission colour from orange into blue. Fluorescent patterns modulated in energy could have been obtained by using a mask and controlling the amount of photons.