Concrete construction methods and practices influence the final in-place quality of concrete. A low permeability concrete mixture does not alone ensure quality in-place concrete. If the concrete mixture is not transported, placed and cured properly, it may not exhibit the desired durability and mechanical properties. This study investigates the in-place permeation properties of low permeability concrete bridge decks mixtures used in the Commonwealth of Virginia. Permeation properties were assessed in both the laboratory and in the field using 4-point Wenner array electrical resistivity, surface air flow (SAF), and chloride ion penetrability (ASTM C 1202-97). Laboratory test specimens consisted of two concrete slabs having dimensions of 280 x 280 x 102-mm (11 x 11 x 4-in) and twelve 102 x 204-mm (4 x 8-in) cylinders per concrete mixture. Specimens were tested at 7, 28 and 91-days. Thirteen cylinder specimens per concrete mixture underwent standard curing in a saturated limewater bath. The simulated field-curing regimes used wet burlap and plastic sheeting for 3 (3B) and 7 days (7B) respectively and was applied to both slabs and cylinder specimens. Slab specimen were tested on finished surface using the SAF at 28 and 91 days, and 4-point electrical resistivity measurements at 1, 3, 7, 14, 28 and 91 days. Compressive strength (CS) tests were conducted at 7 and 28 days. Chloride ion penetrability tests were performed at 7, 28, and 91 days. Statistical analyses were performed to assess the significance of the relationships for the following: Total charge passed and initial current (ASTM C 1202-97); 3B resistivity and 7B resistivity; Slab and cylinder resistivity; Slab resistivity and ASTM C-1202-97 (Total Charge and Initial current); and Surface Air Flow and ASTM C-1202-97. Field cast specimens, test slabs and cylinders, were cast on-site during concrete bridge deck construction. The slab dimensions were 30.5 x 40.6 x 10.2-cm (12 x 16 x 4 in.), and the cylinders were 10.2 x 20.4-cm (4 x 8-in). In-situ SAF and resistivity measurements were taken on the bridge deck at 14, 42 and 91 days. In-place SAF and resistivity measurements on laboratory field cast slabs were taken at 7, 14 and 28-days. ASTM C 1202-97 specimens were prepared from field cast cylinders and tested at 7 and 28 and 42-days. The relationship between in-place permeation measures from field specimens was compared to laboratory data. Results indicated no difference in chloride ion penetrability (Figures 7.4 and 7.5) and 28-day compressive strength (Figure 7.2) with regard to differing simulated field curing regimes, for same age testing. There was no significant difference at the 95 % confidence level between 3B resistivity and 7B resistivity specimens tested at the same age (Figures 7.9 and 7.10). A well defined relationship was observed between total charge passed and initial current (Figure 7-6). An inverse power function was found to describe the relationship between charge passed/initial current and electrical resistivity for all laboratory mixtures used in this study (Figure 7.17 – 7.22). Field data was used to validate laboratory established models for charge passed/initial current and electrical resistivity. Laboratory established models were able to predict 30 to 50% of the field data (Figures 7.31 – 7.34). Results indicate that the SAF lacked the sensitivity to classify the range of concretes used in this study (Figure 7.24). / Ph. D.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Na+,K+-ATPase is ubiquitously expressed in the plasma membrane of all animal cells where serves as the principal regulator of intracellular ion homeostasis. Na+,K+-ATPase activity is activated by Na+ and K+ and current evidence indicates that total Na+,K+-ATPase activity is, in general, inhibited by anions. However, the effect of pharmacologically-induced Cl- flux on α1- and α2/3-subunit containing Na+,K+-ATPase activity is not established. In this study we investigated the effect of diazepam, a GABAA receptor positive allosteric modulator, on α1- and α2/3-subunit containing Na+,K+-ATPase activity. Hippocampal and cortical slices were incubated with diazepam (0, 0.05, 0.15 or 0.5 μM) and/or flumazenil (0, 0.005, 0.015, 0.05, 0.15, 0.5 or 1.5 μM) for 10 minutes. After incubation the slices were homogenized and α1 and α2/3 Na+,K+-ATPase activity were assayed using ouabain 3 μM (that inhibits α2/3-subunit containing Na+,K+-ATPase) and 4 mM (that inhibits both isoforms). Diazepam caused a 50% decrease of α2/3-subunit containing Na+,K+-ATPase activity in the hippocampus, but did not alter enzyme activity in the entorhinal cortex. The effect of diazepam was prevented by flumazenil, indicating that the decrease of Na+,K+-ATPase was involved GABAA receptors. Furthermore, a low chloride medium abolished the diazepam-induced decrease of Na+,K+-ATPase activity. Our data suggests that Na+,K+-ATPase in the hippocampus is sensitive to the pharmacological effects of a benzodiazepine by GABAA receptor-mediated mechanisms. Keywords: sodium pump. GABAA receptor. diazepam. flumazenil. chloride ion. hippocampus. entorhinal córtex. / A enzima Na+,K+-ATPase, ou bomba de sódio, é expressa na membrana plasmática de células eucarióticas, onde atua como principal regulador da homeostase iônica intracelular. A enzima Na+,K+-ATPase é ativada pelos íons Na+ and K+ e evidências indicam que a atividade total da enzima Na+,K+-ATPase é inibida por ânions. Entretanto, o efeito do fluxo de cloreto induzido farmacologicamente sobre a atividade das subunidades α1 e α2/3 da enzima Na+,K+-ATPase ainda não foi investigado. Neste estudo, nós investigamos o efeito do diazepam, um modulador alostérico positivo do receptor GABAA na atividade específica das subunidades α1 e α2/3 da Na+,K+-ATPase. Fatias de hipocampo e de córtex entorrinal foram incubadas com diazepam (0; 0,05; 0,15 ou 0,5 μM) e/ou flumazenil (0; 0,005, 0,015; 0,05; 0,15; 0,5 ou 1,5 μM) por 10 minutos. Após a incubação, as fatias foram homogeneizadas e a atividade das subunidades α1 e α2/3 da enzima Na+,K+-ATPase foi determinada. Diazepam diminuiu 50% a atividade da subunidade α2/3 da Na+,K+-ATPase no hipocampo, mas não alterou a atividade da enzima em córtex entorrinal. O efeito do diazepam foi prevenido por flumazenil, indicando que a diminuição da atividade da Na+,K+-ATPase envolveu a ativação dos receptores GABAA. Além disso, a baixa concentração de cloreto no meio de incubação aboliu a diminuição da atividade enzimática induzida por diazepam. Nossos dados sugerem que a enzima Na+,K+-ATPase no hipocampo é sensível a efeitos farmacológicos dos benzodiazepínicos por meio de mecanismos ativados por receptores GABAérgicos.

Prestressed concrete is a popular construction material for highway bridges. A variety of girder span values, cross-sectional shapes, and prestressing strand layouts has been used in bridges across the United States. A major concern for such bridges is the possibility of corrosion damage in the prestressing strands or reinforcing bars, which is commonly caused by the use of deicing salts on the deck or saltwater spray in coastal regions. The present study aims at establishing analytical tools for the accurate simulation of chloride ingress, corrosion and mechanical damage (cracking) in the concrete, and for the evaluation of the impact of corrosion on the flexural and shear strength of bridge girders. First, an efficient and accurate analytical scheme is formulated to enable the calculation of the load-carrying capacity of corrosion-damaged girders. The analyses rely on two types of models, namely, beam models and nonlinear truss models. The latter are deemed necessary to obtain reliable estimates of the shear capacity, as beam models are not well-tailored for capturing shear failures. A procedure to account for the reduction in area and deformability of corroded strands, based on visually observed corrosion damage, is proposed and implemented. The models are calibrated and validated with the results of experimental tests on prestressed girders which exhibited varying levels of corrosion damage. Further analyses allow the comparison of the capacity of corrosion-damaged girders to that of their undamaged counterparts. The accuracy of a simplified procedure, using equations in the AASHTO code to determine the flexural and shear capacity of the damaged girders, is also determined. Subsequently, a computation scheme was proposed to describe the intrusion of chloride ions in prestressed bridge girder sections. The approach accounts for multiple, coupled processes, i.e., heat transfer, moisture transport, and chloride advective and diffusive transport. The constitutive models for moisture and chloride transport rely on previous pertinent work, with several necessary enhancements. The modeling scheme is calibrated with data from previous experimental tests on concrete cylindrical and prismatic specimens. The calibrated models are then validated using data from chloride titration tests conducted on girders removed from two bridges in Virginia after 34 and 49 years of service. The results indicate that the proposed framework can accurately reproduce the experimentally measured chloride content. The modeling approach also allows the evaluation of the accuracy of simplified, design-oriented tools for estimating the evolution of chloride content with time. The multi-physics simulation scheme is further refined to account for the corrosion-induced mechanical damage (cracking), by incorporating a phenomenological description of the electrochemical reaction kinetics, generation of expansive corrosion products, and subsequent development of tensile stresses and cracking in the surrounding concrete. The impact of cracking on the chloride and moisture transport mechanisms is also taken into account. The last part of this dissertation pursues the quantification of the uncertainty governing the chloride ingress in bridge girders, through the use of a stochastic collocation approach. The focus is on understanding how the inherent uncertainty in the value of input parameters (e.g., material transport parameters, ambient conditions etc.) is propagated, leading to uncertainty in the evolution of chloride content and the expected corrosion initiation time for a given bridge. / Doctor of Philosophy / Prestressed concrete is widely utilized in the construction of highway bridges in the United States. A significant concern arises regarding potential corrosion damage in the prestressing strands or reinforcing bars, which is commonly attributed to the application of deicing salts on the deck or exposure to saltwater spray in coastal regions. This study aims to develop analytical tools that can accurately simulate the intrusion of corrosive agents (namely chloride ions), and subsequent damage (cracking) in concrete. Furthermore, the research seeks to assess the impact of corrosion on the bearing capacity of bridge girders. Two different classes of analytical approaches are pursued. The first class employs purely mechanical (stress/deformation) models for capturing the strength, deformability and failure modes of girders with visual corrosion damage. These models rely on two approaches to capture the flexural and shear capacity of specimens, namely, beam-based models and truss-based models. The impact of corrosion is established through appropriate modification of the model parameters, based on the extent of visually observed corrosion damage. The analytical approaches are validated through a series of experimental tests previously conducted on corrosion-damaged girders. The second class of analytical approaches employs multi-physics models, to describe the mechanisms leading to corrosion-induced damage. The models account for heat transfer, moisture transport, and chloride transport in prestressed beam sections. Model parameters are calibrated with experimental tests in literature. The computational scheme is used to quantitatively describe the chloride ingress on bridge girders decommissioned from two different bridges in Virginia, after 34 and 49 years of service. The analysis results are found capable of capturing the actual chloride content at various depths from the exposure surface, as determined by chloride titration tests. The temporal evolution of chloride on the surface of prestressing strands indicates that corrosion has been taking place over a period of time for the two bridges. The multi-physics simulation approach is further enhanced to account for the corrosion-induced mechanical damage (cracking), by explicitly incorporating a description of the reaction kinetics, generation of expansive corrosion products and subsequent development of cracking in the surrounding concrete. The last part of this dissertation pursues the quantification of the uncertainty in the expected service life of prestressed concrete bridge structures. Given the inherent uncertainty to key values of model parameters, a parametric study is employed to investigate the propagation of uncertainty to the time history of chloride content at particular locations of the section and the probability of corrosion initiation at specific age values.

Electrosorption-based capacitive deionization (CDI) has become a viable process for brackish water desalination and defluoridation. In this study, activated Douglas fir biochar is used as a low-cost electrode material with adsorption capacity comparable to activated carbon obtained from biomass precursors. Adding functional groups to the activated biochar enhanced salt removal capacity, providing cation and anion selectivity. The functionalized electrodes were prepared by Nafion, titanium isopropoxide, and p-phenylenediamine treatment, respectively, which introduced sulfonate, titanium dioxide and amine functional groups to the electrode surface. These modification methods are versatile and can be easily performed without sophisticated laboratory environment. Modified biochar electrodes were characterized by TEM, SEM-EDX, XRD, and XPS. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were performed to analyze the electrochemical properties of the electrodes. The salt adsorption capacity (SAC) was evaluated in a 3D-printed capacitive deionization flow cell using a chloride and fluoride ion sensor. It was found that functionalized biochar electrodes had increased SAC and charge efficiency in asymmetrical setup due to reduced co-ion effect. For example, the asymmetrical CDI cell with Nafion cathode and amine biochar anode improved NaCl removal capacity by 54% over the activated biochar symmetrical cell (identical anode and cathode), with SAC 6.01 mg NaCl/g biochar at the symmetrical cell and 9.25 mg/g for the asymmetrical cell. The charge efficiency also increased by ≈ 67% from symmetric AcB cell to asymmetric TB-05 cathode and AmB anode. This work shows that biochar can be engineered and explored broadly as an inexpensive sustainable electrode material for asymmetrical capacitive deionization.

Die globalen Herausforderungen unserer Zeit sind wesentlich geprägt vom Klimawandel und der Umweltzerstörung auf dem Planeten Erde, hervorgerufen durch die Existenz des Menschen. Damit sind die Themen der Nachhaltigkeit, des Umweltschutzes und der alternativen Energieerzeugung, verbunden mit der Energiespeicherung, allgegenwärtig. Auf dem Gebiet der mobilen Energiespeicher sind die Lithium-Ionen-Batterien (LIB) fest etabliert. Jedoch sind die Ressourcen für das Metall Lithium endlich und die großtechnische Anwendung dieser Systeme ist mit hohen Sicherheitsmaßnahmen und damit hohen Kosten verbunden. Deshalb wird zunehmend an Lithium-freien Batterien geforscht. Diese Arbeit befasste sich mit der Entwicklung von Komponenten einer Lithium-freien, rein-organischen Festkörperbatterie. Die Herausforderungen an solche komplexen Systeme sind besonders hoch, sodass sich diese Arbeit auf die gezielte Entwicklung geeigneter Elektrolytmaterialien für organische Festkörperbatterien fokussierte. Die bisher genutzten Flüssigelektrolytsysteme in LIB bringen einige Nachteile mit sich (z.B. Feuchtigkeitsempfindlichkeit, Toxizität, leichte Entzündlichkeit), welche adressiert werden müssen. Kohlenstoffhaltige Polymere sind prinzipiell relativ leicht synthetisierbar und die Verfügbarkeit an Kohlenstoff, ist im Vergleich zu Lithium deutlich größer. Weiterhin sind Polymere flexibler als herkömmliche Batteriekomponenten, was die Anwendung für dünne elektronische Geräte attraktiv macht. Basierend auf den Vorarbeiten der Arbeitsgruppe Pospiech, welche sich mit Bis(trifluormethansulfonyl)imid-haltigen ionisch-flüssigen Polymerelektrolyten für LIB beschäftigten, sollten in dieser Arbeit ebenfalls ionische Flüssigkeiten als Grundlage für Polymerelektrolyte für organische Redox-Batterien dienen. Der Neuheitsgrad dieser Arbeit liegt jedoch in der Verwendung von Chlorid-Ionen-haltigen, ionisch-flüssigen Polymerelektrolyten, welche als Chlorid-Ionen-Leiter in der organischen Batterie fungieren sollen. Aufgrund der festen Polymermatrix agieren diese dabei nicht nur als Festelektrolyte, sondern auch als Separatoren, weshalb eine gewisse mechanische Festigkeit mit einer ausreichenden Flexibilität kombiniert werden muss. Zur Realisierung der Aufgabenstellung wurden zunächst neuartige Chlorid-Ionen-haltige Polymerelektrolyte, sowohl als lineare Homopolymere als auch als vernetzte Polymere, synthetisiert. Dabei war das Ziel, die Systeme im Hinblick auf die ionischen Leitfähigkeiten und damit verbunden den Ladungstransfer der Chlorid-Ionen zu optimieren. Dies sollte zum einen durch strukturelle Veränderungen (Wahl des Spacers und der Endgruppe) als auch durch die Verwendung von verschiedenen Vernetzer- und Leitsalzkonzentrationen realisiert werden. Im zweiten Schritt wurde die systematische Variation der Polymerstruktur genutzt, um Struktur-Eigenschafts-Beziehungen, insbesondere hinsichtlich der ionischen Leitfähigkeit auszuarbeiten. Im dritten Schritt fanden ausgewählte Systeme dann letztendlich Anwendung in Batteriezellen, um die Frage zu beantworten, ob die Anforderungen an den Festkörperelektrolyten tatsächlich erreicht werden können und es damit möglich ist, in solchen Systemen lösungsmittelfrei zu arbeiten, oder ob die Eigenschaften, wie z.B. die ionische Leitfähigkeit, nicht ausreichen und durch Zugabe geeigneter Zusätze ein Gelelektrolyt angewandt werden sollte. Mit der dargestellten Vorgehensweise ist es im Rahmen dieser Doktorarbeit gelungen, neuartige Chlorid-Ionen-leitende Polymerelektrolyte für Batteriesysteme zu entwickeln, welche auf ionisch-flüssigen Monomeren basieren und somit ein deutlich geringeres Sicherheitsrisiko mit sich bringen, als es herkömmliche Flüssigelektrolytsysteme bisher tun. Das Gesamtziel dieser Arbeit wurde somit erfolgreich erreicht. Es wurden folgende wesentliche Ergebnisse erzielt: (1) Durch systematische Variationen in der Monomerstruktur, verschiedene Polymerisationsmethoden und Additive konnte eine Vielzahl an neuartigen Chlorid-haltigen Polymerelektrolyten synthetisiert und chemisch sowie chemisch-physikalisch charakterisiert werden. (2) Die Struktur-Eigenschafts-Beziehungen der Polymere wurden sehr detailliert herausgearbeitet. Dabei wurde insbesondere der Einfluss der C-Atom-Anzahl in der acrylischen Seitenkette, die Menge an Vernetzer und Leitsalz auf das thermische, mechanische, chemische und elektrochemische Verhalten der Proben untersucht und verstanden. (3) Damit wurde das Basiswissen für eine effiziente Übertragung auf ein Batteriesystem erarbeitet. (4) Erste Implementierungen der neuen Systeme als Elektrolyte in Poly(2,2,6,6-tetramethylpiperidinyloxyl-methacrylat)/ Zink-Batterien wurden erfolgreich durchgeführt und zeigten mit Leitfähigkeiten von 10-3 S·cm-1 vielversprechende Ergebnisse. Eine solche Breite an strukturellen Variationen in Chlorid-Ionen-haltigen Polymeren, welche mit zahlreichen Methoden detailliert analysiert und anschließend in Batteriezellen als Gel- und Festelektrolyte getestet wurden, konnte bisher in der Literatur noch nicht gefunden werden und stellt einen erheblichen Neuheitsgrad dieser Arbeit und einen guten Ausgangspunkt zur Implementierung in Batterien dar.:Inhaltsverzeichnis Danksagung i Inhaltsverzeichnis iii Abbildungsverzeichnis vii Tabellenverzeichnis xiv Abkürzungs- und Symbolverzeichnis xvi 1 Einleitung 1 2 Theoretischer Hintergrund 6 2.1 Die Lithium-Ionen-Batterie (LIB) 6 2.2 Struktur und Aufbau von polymerbasierten Batterien 8 2.2.1 Redox-Flow-Batterien (RFB) 8 2.2.2 Organische Festkörperbatterien (SSB) 11 2.3 Elektrolyttypen für (polymerbasierte) Batterien 19 2.3.1 Überblick 19 2.3.2 Flüssigelektrolyte 20 2.3.2.1 Lösungsmittel 20 2.3.2.2 Leitsalz 22 2.3.2.3 Elektrolyte basierend auf ionischen Flüssigkeiten 23 2.3.3 Polymerelektrolyte (PEL) 27 2.3.3.1 Überblick 27 2.3.3.2 Festelektrolyte (SPE) 28 2.3.3.3 Gelpolymerelektrolyte (GPE) 30 2.3.3.4 Elektrolyte aus polyionischen Flüssigkeiten (PIL) 30 2.4 Synthese polymerer ionischer Flüssigkeiten 37 2.4.1 Freie radikalische Polymerisation (FRP) von IL-Monomeren 38 2.4.2 Reaktionsverfolgung 42 3 Zielstellung und Aufbau der Arbeit 44 4 Experimenteller Teil 47 4.1 Verwendete Chemikalien 47 4.2 Synthesen 49 4.2.1 Monomersynthesen 49 4.2.2 Polymersynthesen 56 4.2.2.1 Lineare Homopolymere (LHP) 56 4.2.2.2 PIL-Netzwerke 59 4.3 Angewandte Methoden, Verfahren und Geräte 60 4.3.1 Raman-Spektroskopie als Methode zur Reaktionsverfolgung 60 4.3.2 Charakterisierung der linearen Homopolymere 61 4.3.2.1 Kernspinresonanzspektroskopie (NMR-Spektroskopie) 61 4.3.2.2 Thermische Feld-Fluss-Fraktionierung (ThFFF) 61 4.3.2.3 Matrix-unterstützte Laser-Desorption/Ionisation gekoppelt mit Flugzeit-Massenspektrometrie (MALDI-TOF MS) 63 4.3.3 Methoden zur thermischen und mechanischen Stabilität bzw. Eigenschaften 64 4.3.3.1 Thermogravimetrische Analyse (TGA) 64 4.3.3.2 Dynamische Differenzkalorimetrie (DSC) 64 4.3.3.3 Rheologie 64 4.3.3.4 Quelluntersuchungen 66 4.3.4 Methoden zur Bestimmung elektrochemischer Eigenschaften 67 4.3.4.1 Elektrochemische Impedanz-Spektroskopie (EIS) 67 4.3.4.2 Linear-Sweep-Voltammetrie (LSV) 71 4.3.4.3 Cyclovoltammetrie (CV) 72 4.3.4.4 Raster-Kelvin-Mikroskopie (KPFM) 75 4.3.5 Methoden zur Untersuchung der morphologischen Struktur bzw. Eigenschaften 76 4.3.5.1 Rasterelektronenmikroskopie (REM) 76 4.3.5.2 Kleinwinkelröntgenstreuung (SAXS) 76 4.4 Batterietests 77 4.4.1 Zellaufbau 77 4.4.2 Parameter und Materialien für Zyklisierungstests 77 5 Ergebnisse und Diskussion 78 5.1 Darstellung des Forschungskonzeptes 78 5.2 Synthese und Polymerisation der IL-Monomere 80 5.2.1 Monomersynthesen 80 5.2.2 Polymersynthesen 82 5.2.2.1 Lineare Homopolymere 82 5.2.2.2 PIL-Netzwerke 83 5.3 Quellverhalten der PIL-Netzwerke 86 5.4 Charakterisierung der linearen Homopolymere und der PIL-Netzwerke 91 5.4.1 Bestimmung der molaren Massen der linearen Homopolymere 91 5.4.1.1 Thermische Feld-Fluss-Fraktionierung 91 5.4.1.2 Matrix-unterstützte Laser-Desorption/Ionisation gekoppelt mit Flugzeit-Massenspektrometrie 94 5.4.2 Thermisches Verhalten 95 5.4.2.1 TGA-Untersuchungen der linearen Homopolymere 95 5.4.2.2 TGA-Untersuchungen der PIL-Netzwerke 97 5.4.2.3 DSC-Untersuchungen der linearen Homopolymere 98 5.4.2.4 DSC-Untersuchungen der PIL-Netzwerke 101 5.4.3 Dynamisch-mechanisches Verhalten der PIL-Netzwerke 105 5.4.3.1 Komplexe Viskosität als Funktion der Temperatur 105 5.4.3.2 Bestimmung der Maschenweite und Vernetzungsdichte der PIL-Netzwerke 110 5.4.4 Ionische Leitfähigkeit und elektrochemisches Verhalten 113 5.4.4.1 EIS-Messungen der linearen Homopolymere 113 5.4.4.2 EIS-Messungen der PIL- Netzwerke 115 5.4.4.3 Linear-Sweep Voltammetrie der linearen Homopolymere und PIL-Netzwerke und Cyclovoltammetrie der linearen Homopolymere 123 5.4.5 Untersuchungen zum Ladungsträgertransport 125 5.4.5.1 Chlorid-Ionen-Diffusion 125 5.4.5.2 Raster-Kelvin-Mikroskopie 127 5.4.6 Strukturaufklärung mittels Kleinwinkelröntgenstreuung 131 5.5 Integration ausgewählter Systeme als Polymerelektrolyte in Batteriezellen 138 5.5.1 Wahl geeigneter Elektroden- und Elektrolytkombinationen 138 5.5.2 Zyklisierungstests 141 6 Zusammenfassung und Ausblick 146 7 Literaturverzeichnis 154 8 Anhang A 9 Publikationsliste L 10 Selbstständigkeitserklärung M