This research work was undertaken to solve an industrial problem related to roll-to- roll production of dye-sensitised solar cells (DSCs). It is possible to manufacture DSCs in a roll-to-roll production line on a sheet metal such as titanium. However, DSCs produced in such a way are not commercially viable due to the use of expensive titanium metal. Therefore, the intention behind this work was to utilize a cheap sheet metal such as ECCS (electro chrome coated steel) to manufacture DSCs in a roll-to-roll production facility of TATA steel Europe, as this project was funded by them. Unfortunately, ECCS corrodes in the I[-]/I[3-] redox electrolyte present in a DSC therefore, to protect ECCS from the corrosion whilst using it as a DSC substrate was the real challenging task in this research. In order to solve this problem high temperature resistant polyimide based coatings were developed which can be used to coat ECCS substrates whilst maintaining excellent dimensional stability at the DSC processing temperatures. Such coatings were electrically conducting which helped preserve the electrical conductivity of the underlying metallic substrate. Electrically conductive polyimides were developed by simply blending conductive fillers such as carbon materials and titanium nitride. It was initially thought that carbon/polyimide based coatings would be suitable for this application. However, severe interfacial charge recombination and poor reflectivity made carbon/PI coatings inferior compared to the TiN/PI coatings. TiN/PI coatings performed well but poor reflectivity produced low current outputs. Moreover, TiN/PI was found to reduce the catalytic activity of thermally deposited platinum therefore it was not useful as a counter electrode material. As a solution to these problems, TiN and carbon materials based hybrid coatings were developed. Hybrid coatings did perform efficiently in terms of overall PV performance but due to poor reflectivity, such coatings also produced low J[sc] values. However, counter electrodes prepared using hybrid coating demonstrated excellent PV performance with thermally deposited platinum. Furthermore, TCO (transparent conducting oxide) free glass substrates can also be used to manufacture low-cost PV devices when coated with these conductive coatings.

abstract: Small molecules have proven to be very important tools for exploration of biological systems including diagnosis and treatment of lethal diseases like cancer. Fluorescent probes have been extensively used to further amplify the utilization of small molecules. The manipulation of naturally occurring biological targets with the help of synthetic compounds is the focus of the work described in this thesis. Bleomycins (BLMs) are a class of water soluble, glycopeptide-derived antitumor antibiotics consisting of a structurally complicated unnatural hexapeptide and a disaccharide, clinically used as an anticancer chemotherapeutic agent at an exceptionally low therapeutic dose. The efficiency of BLM is likely achieved both by selective localization within tumor cells and selective binding to DNA followed by efficient double-strand cleavage. The disaccharide moiety is responsible for the tumor cell targeting properties of BLM. A recent study showed that both BLM and its disaccharide, conjugated to the cyanine dye Cy5**, bound selectively to cancer cells. Thus, the disaccharide moiety alone recapitulates the tumor cell targeting properties of BLM. Work presented here describes the synthesis of the fluorescent carbohydrate conjugates. A number of dye-labeled modified disaccharides and monosaccharides were synthesized to study the nature of the participation of the carbamoyl moiety in the mechanism of tumor cell recognition and uptake by BLM saccharides. It was demonstrated that the carbamoylmannose moiety of BLM is the smallest structural entity capable for the cellular targeting and internalization, and the carbamoyl functionality is indispensible for tumor cell targeting. It was also confirmed that BLM is a modular molecule, composed of a tumor cell targeting moiety (the saccharide) attached to a cytotoxic DNA cleaving domain (the BLM aglycone). These finding encouraged us to further synthesize carbohydrate probes for PET imaging and to conjugate the saccharide moiety with cytotoxins for targeted delivery to tumor cells. The misacylated suppressor tRNA technique has enabled the site-specific incorporation of noncanonical amino acids into proteins. The focus of the present work was the synthesis of unnatural lysine analogues with nucleophilic properties for incorporation at position 72 of the lyase domain of human DNA polymerase beta, a multifunctional enzyme with dRP lyase and polymerase activity. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2014

As interações entre as moléculas de corante e as partículas de argila em suspensão podem envolver diferentes processos dependendo da argila e da maneira pela qual as suspensões corante/argila são preparadas. Os processos que ocorrem são: a adsorção de moléculas de nas superfícies externas das partículas de argila seguidas de migração para as regiões interlamelares, outro processo é devido a interações partícula-partícula, onde as moléculas de corante ficam envoltas em aglomerados de partículas de argila e um terceiro processo é devido a migração das moléculas de corante entre partículas de argila. No presente trabalho foi estudada a influência de diferentes metodologias nos processos de migração de moléculas do corante azul de metileno (AM) entre partículas de argilas em suspensão aquosa. Experimentos adicionando-se partículas de argila nas suspensões corante/argila foram realizados com acompanhamento das variações espectrais em função do tempo. Foi possível detectar variações espectrais nas suspensões corante/argila atribuídas a processos de migração de moléculas de corante adsorvidas em partículas de argila para outras partículas na suspensão. Os resultados indicaram que o processo de migração entre diferentes partículas de argila depende da razão corante/argila. Em outro tipo de experimento, utilizando diferentes formas de adição do corante à suspensão de argila (lenta, rápida e diálise) constatou-se que o modo de adição do corante pode afetar os processos de adsorção, para alguns sistemas corante/argila é muito importante considerar a forma de adição do corante à suspensão de argila, para que se tenham suspensões corante/argila com propriedades desejáveis. / Interactions between dye molecules and suspended clay particles may follow different processes depending on how the dye/clay suspensions are prepared. The processes that occur are: adsorption of molecules on the external surfaces of clay followed by migration to the interlamelar areas, another process is due to particle-particle interactions, in which the dye molecules are wrapped in clay particle agglomerates and a third process due to the migration of the dye molecules between clay particles. In the presente work the influence of different metodologies on the migration processes for the methylene blue dye between clay particles in aqueous suspension was studied. Experiments adding clay particles to the system dye/clay were done monitoring following the spectral changes in function of time. It was possible to detect spectral variations in the dye/clay suspensions attributed to the migration of adsorbed dye molecules to other particles in the suspension dye molecules adsorbed in clay particles migration process. The results indicated that the migration process between different clay particles depend on the nature of the clay and on the dye/clay ratio. In another type of experiment, using different forms for adding dye to the clay suspension (slow, fast and dialysis) it was seen that the adding way for the dye can affect the adsorption processes, for some dye/clay systems it is very important to consider the adding way of the dye to the clay suspension, so that dye/clay suspensions with desirable properties are obtained.

No description available.

The molecular design, synthesis and spectroscopic characterization of a series of ruthenium(II), metal-free and platinum(II) photosensitizers were discussed. The applications of some of these compounds in dye-sensitized solar were also outlined. To start with, a brief overview on the background of dye-sensitized solar cells (DSSCs) was presented in Chapter 1. In Chapter 2, a series of new thiocyanate-free ruthenium(II) cyclometalated complexes with different ligands were successfully synthesized and some of them were fully characterized by spectroscopic and computational methods. The nature of cyclometalating ligands effectively tunes the properties of the metal complexes and the resulting DSSC performance. In Chapter 3, new di-anchoring organic dyes have been synthesized and characterized. This molecular design strategy can significantly enhance the . value because this successfully inhibits the undesirable charge combination and prolongs the electron lifetime. The discoveries open up a new avenue to the evolution of organic sensitizers and the optimization of bridged di-anchoring dyes for highly efficient co-adsorbent-free DSSCs. In Chapter 4, a series of new thiophene-free platinum sensitizers for the application of DSSCs was developed. Four unsymmetrical platinum(II) di-acetylide complexes containing phenothiazine moiety with different donor units were designed and synthesized. These photosensitizers were fully characterized by spectroscopic as well as computational studies and also successfully employed in DSSC fabrication. These findings provided positive evidence that platinum-acetylide complexes have a great potential and prospect for the use as promising metal-based photosensitizers in DSSC applications. Finally, Chapters 5 and 6 present the concluding remarks and the experimental details of the work described in Chapters 2–4.

In this research, the ability of anaerobic and aerobic biological sludges to reduce and stabilize azo dye compounds was studied. Synthetic dye solutions and an industrial textile wastewater were both treated using anaerobic and aerobic biomass, separately and in sequential step-treatment processes. The primary objective was to reduce the wastewater color to an intensity that complies with the Virginia Pollutant Discharge Elimination System (VPDES) permit level. This level is set at 300 American Dye Manufactures Institute (ADMI) units. Further objectives were to achieve reductions in the total kjehdal nitrogen (TKN) and total organic carbon (TOC) in the wastewater. Anaerobic and aerobic treatment systems were both effective in reducing the wastewater color; however, anaerobic treatment generally produced the greatest color removal. Anaerobic/aerobic (ANA/AER) sequential step-treatment provided the best reductions in ADMI color, TKN and TOC. Anaerobic/aerobic/anaerobic/aerobic (ANA/AER/ANA/AER) sequential step-treatment did not yield greater reductions in ADMI color, TKN, or TOC as compared to ANA/AER sequential step-treatment. / Master of Science

In this study an improved description of the bandwidth limiting tuning filters has been introduced into a semiclassical model for a synchronously pumped mode-locked dye laser system. This model is an improvement over the traditional rate equation approach since it has detailed representations of the energy levels, rotational distribution, and coherence effects. The new set of equations has been solved numerically using the best available values for the various parameters, and autocorrelations have been computed for a range of different length detuning and bandwidth limiting elements. In the experiments, an acousto-optically mode-locked argon ion laser is used to synchronously pump a rhodamine 6G dye laser. To study the tuning effects, two and three plate birefringent filters and a tuning wedge have been used. Transmission and bandwidth of these filters have been carefully measured as a function of the length detuning. The autocorrelated pulses have been measured as a function of the length detuning. The experimental pulse shapes agree closely with the theoretical solutions for all values of detuning and filter bandwidth. Through a sensitivity analysis, it is shown how this model can be used to select values for the transmission and the bandwidth of the filter to obtain optimum pulse characteristics.

Lipoproteins are macromolecular assemblies of lipids and proteins that are essential for the transportation of the water insoluble lipids in the circulation. The major lipoproteins, are low density lipoproteins (LDL) and high-density lipoproteins (HDL). LDL, also called the “bad cholesterol”, delivers cholesterol to peripheral tissues and is directly correlated with increased risk of cardiovascular disease, stroke and type II diabetes. HDL, on the other hand, is called the “good cholesterol” as it removes excess cholesterol from peripheral tissues for elimination by the liver in a process called reverse cholesterol transport (RCT). HDL is therefore, cardioprotective. The first and rate-limiting step in HDL biogenesis involves interaction of apolipoprotein A-I (apoA-I), the major protein of HDL, with the membrane transporter ABCA1 to promote cholesterol efflux to form nascent HDL. Food additives and sugar substitutes have been widely consumed in recent years. While the FDA deems sweeteners such as stevia, sucralose, acesulfame and erythritol and food dyes such as Sunset Yellow and Allura Red safe for human consumption, their direct effects on HDL biogenesis are unknown. In this study, we examined effects of the above-mentioned additives and sugar substitutes on HDL biogenesis using macrophage-derived cells, J774. We used a fluorescent analog, BODPIY-cholesterol, to label the cholesterol pool and to measured its efflux by fluorescence. HDL biogenesis was determined by analyzing efflux media using native PAGE followed by immunoblotting using antibodies to apoA-I. Lipids were determined using cholera toxin subunit B to detect the ganglioside GM1. We found that all sweeteners and food dyes exerted inhibitory effects on cholesterol efflux and HDL biogenesis to varying degrees under physiologically-relevant concentrations. Steviol, the metabolite of stevia, appeared to exert the largest inhibition. It reduced cholesterol efflux by > 50% and HDL biogenesis was reduced the most, as compared to the other sugar substitutes. Under control conditions nascent HDL particles varying from less than 7 to about 12 nm diameter produced. However, under most experimental conditions, additives appeared to have an impact on the larger particles (8-12 nm diameter) as they were either reduced substantially or absent). Interestingly, the sweetener Erythritol at low concentration (5mg/ml) was inhibitory but at higher concentration (15 mg/ml) appears to reverse this effect. Since ABCA1 is essential for optimal cholesterol efflux and HDL biogenesis, we hypothesized that their inhibition by food additives and sugar substitutes was due to a decreased level of ABCA1. Surprisingly, we found that ABCA1 level under all conditions were either similar or higher than control levels. Therefore, we suggest that the additives used in this study presumably led to mislocalization of ABCA1 and/or caused a conformational change of the transporter. This could result in decreased binding of apoA-I thus leading to reduced cholesterol efflux resulting in decreased HDL biogenesis. On the basis of this study we suggest that the FDA guidelines should be modified and sugar substitutes and foods containing artificial dyes should be consumed in moderation.

No description available.

No description available.