This work sought to enforce aromatic interactions between compatible π-molecular orbital systems with ionic bonding. In this case the interacting partners are oppositely charged discotic triangulene derivatives. The observed properties of the heterodimeric ion-pairs likely arise due to a hypothetical synergy between electrostatics and π-interactions. The work presented here describes investigation of putative covalency arising from this hypothetical synergy in the electrostatics driven π-stacking. In order to probe this, various hypotheses were made and experiments were designed to test their validity. The results from the experiments show existence of contact ion-pairs and complex solvent-separated discotic ions in solution. The formation of complex ion-pairs arise due to the fact that the electrostatic interaction that brings the discotic ions together is strong, but does not neutralize when the contact is made. So, the dipole created by the monopoles in a dimeric contact ion-pair can attract ions at both termini forming oligomers. This process apparently continues towards highly aggregated states and then to nanometric species and at some point the material precipitates. The propensity to aggregate and form complex-ions limited our approach to the measurement of the energetics of the ion-pairing for two reasons: (1) the observables had a complex dependence on temperature, solvent, concentration and ionic strength; and (2) the mass in solution was undergoing kinetic evolution towards solid states. The turbidimetric effects arising due to aggregate formation further complicated the extraction of weak interactions between the ions and hence effects determination of ion-pairing constants.

<p> </p><p>Infrared (IR) imaging devices based on energy detection has shown a dramatic development in technology along with an impressive price reduction in recent years. However, for a low-end market as in automotive applications, the present cost of IR cameras is still the main obstacle to broadening their usage. Ongoing research has continuously reduced the system cost. Apart from decreasing the cost of infrared optics, there are other key issues to achieve acceptable system costs, including wafer-level vacuum packaging of the detectors, low vacuum level operation, and the use of standard materials in the detector fabrication. This thesis presents concepts for cost reduction of low-end IR cameras.</p><p>     The thesis presents a study of detector performance based on the thermal conductance design of the pixel. A circuit analog is introduced to analyze the basic thermal network effect from the surrounding environment on the conductance from the pixel to the environment. A 3D simulation model of the detector array conductance has been created in order to optimize the performance of the arrays while operated in low vacuum. In the model, Fourier's law of heat transfer is applied to determine the thermal conductance of a composite material pixel. The resulting thermal conductance is then used to predict the performance of the detector array in low vacuum.</p><p>     The investigations of resist as the intermediate bonding material for 3D array integration are also reported in the thesis. A study has been made of the nano-imprint resists series mr-I 9000 using a standard adhesive wafer bonding scheme for thermosetting adhesives. Experiments have been performed to optimize the thickness control and uniformity of the nano-imprint resist layer. The evaluation, including assessment of the bonding surface uniformity and planarizing ability of topographical surfaces, is used to demonstrate the suitability of this resist as sacrificial material for heterogeneous detector array integration<em>. </em><em></em></p><p>     Moreover, the thesis presents research in wafer-level packaging performed by room temperature bonding. Sealing rings, used to create a cavity, are manufactured by electroplating. The cavity sealing is tested by liquid injection and by monitoring the deflection of the lid membrane of the cavities. A value for the membrane deflection is calculated to estimate the pressure inside the cavities.  </p>

<p>This thesis deals with the impact of hydrogen bonding on the properties of phenols. The possibility for tyrosine to form hydrogen bonds to other amino acids has been found to be important for its function as an electron transfer mediator in a number of important redox enzymes. This study has focused on modeling the function of tyrosine in Photosystem II, a crucial enzyme in the photosynthetic pathway of green plants.</p><p>Hydrogen bonds between phenol and amines in both inter- and intramolecular systems have been studied with quantum chemical calculations and also in some solid-state structures involving phenol and imidazole.</p><p>Different phenols linked to amines have been synthesized and their possibilities of forming intra- and intermolecular hydrogen bonds have been studied as well as the thermodynamics and kinetics of the generation of phenoxyl radicals via oxidation reactions.</p><p>Since carboxylates may in principle act as hydrogen bond acceptors in a manner similar to imidazole, proton coupled electron transfer has also been studied for a few phenols intramolecularly hydrogen bonded to carboxylates with the aim to elucidate the mechanism for oxidation. Electron transfer in a new linked phenol—ruthenium(II)trisbipyridine complex was studied as well.</p><p>The knowledge is important for the ultimate goal of the project, which is to transform solar energy into a fuel by an artificial mimic of the natural photosynthetic apparatus</p>

Microfluidic systems are being used in more and more areas and the demand for such systems is growing every day. To meet such high volume market needs, a cheap and rapid method for sealing these microfluidic platforms which is viable for mass manufacture is highly desirable. In this work low frequency induction heating (LFIH) is introduced as the potential basis of a cost-effective, rapid production method for polymer microfluidic device sealing. Thin metal layers or structured metal features are introduced between the device s substrates and heated inductively. The surrounding material melts and forms a bond when cooling. During the bonding process it is important to effectively manage the heat dissipation to prevent distortion of the microfluidic platform. The size of the heat affected zone (HAZ), and the area melted, must be controlled to avoid blockage of the microfluidic channels or altering the channels wall characteristics. The effects of susceptor shape and area, bonding pressure, heating time, etc, on the heating rate have been investigated to provide a basis for process optimisation and design rules. It was found that the maximum temperature is proportional to the square of the susceptor area and that round shaped susceptors heat most efficiently. As a result of the investigations higher bonding pressure was identified as increasing bond strength and allowing the reduction of heating time and thus the reduction of melt zone width. The use of heating pulses instead of continuous heating also reduced the dimensions of melt zones while maintaining good bond strength. The size of the HAZ was found to be negligible. An analytical model, which can be used to predict the heating rate, was derived. In validating the model by numeric models and experiments it was found that it cannot be used to calculate exact temperatures but it does correctly describe the effect of different heating parameters. Over the temperature range needed to bond polymer substrates, cooling effects were found not to have a significant impact on the heating rate. The two susceptor concepts using thin metal layers (metal-plastic bonds) or structured metal features (plastic-plastic bonds) were tested and compared. While the metal-plastic bonds turned out to be too weak to be useful, the bonds formed using structured susceptors showed good strength and high leakage pressure. Based on the knowledge gained during the investigations a microfluidic device was designed. Different samples were manufactured and tested. During the tests minor leaks were observed but it was found that this was mainly due to debris which occurred during laser machining of the channels. It was concluded that induction bonding can be used to seal plastic microfluidic devices. The following guidelines can be drawn up for the design of susceptors and process optimisation: Materials with low resistivity perform better; For very thin susceptors the effect of permeability on the heating rate is negligible; The cross-sectional area of the susceptor should be as large as possible to reduce resistance; The thickness of the susceptor should be of similar dimensions to the penetration depth or smaller to increase homogeneity of heat dissipation; The shape of the susceptor should follow the shape of the inductor coil, or vice-versa, to increase homogeneity of heat dissipation; The susceptor should form a closed circuit; Higher bonding pressure leads to stronger bonds and allows reduced heating times; Pulsed heating performs better than continuous heating in terms of limited melt area and good bond strength. The drawbacks of the technique are explained as well: introducing additional materials leads to additional process steps. Also the structuring and placement of the susceptor was identified to be problematic. In this project the structured susceptor was placed manually but that is not feasible for mass manufacture. To be able to use the technique efficiently a concept of manufacturing the susceptor has to be found to allow precise alignment of complex designs.

Nonwoven-fabrics have been in use since 1930s. Their advantages over other web fonnation methods like knitting and weaving have attracted many industries such as aerospace, automotive, sports, geotextiles, composites, battery separators etc. to explore and increase their usage. During nonwoven manufacturing, most of the laid loose webs have an insufficient strength as fonned, and require an additional bonding procedure in order to provide the produced nonwoven with its intended properties. To achieve the desired properties of the nonwoven web, the bonding process is therefore, the most important part during production. The thennal bonding through air is one of the modem techniques which is incrementally improved to increase the yield of manufactured nonwoven properties. The system has a disadvantage which is, that the production capacity and energy efficiency is very low. The entitled research aims an industrial optimisation of the thermal bonding through air by entailing a strategic approach and encompassing the whole process chain of the thennal bonding process. The comprehensive and flexible optimisation opportunities provided by the CFD has been used to aid in the control and optimisation of the thermal bonding process and machinery. To optimise the process and product quality, the complex system composing of several components and various physical phenomena occurring during processing is simulated using a hierarchical methodology. More specifically a hierarchical decomposition procedure to recast the original multi scale problem as a sequence of three scale decoupled macro-, meso-, and micro scale subproblems is exploited. The methodology is applied in conjunction with the validation of experiments on through-air bonding product lines. 2D and 3D computational fluid dynamics (CFD) models based on the continuum modelling approach and the theory of porous media coupled with the theory of mixtures are developed to treat the flow behavior, heat transfer, phase change and air moisture transport within the whole through-air bonding system. The model is concluded to be an economic computational tool hence providing rapid process optimisation and valuable infonnation early in the process, which can replace costly experiments and ensure product consistency under variable process and climate conditions. 2D and 3D hybrid modelling considering parametric discrete and continuum parts is also perfonned using conjugate heat transfer analyses. The approach precisely permits the optimisation of the machine component design and the associated optimisation of consistent process and product properties.

Background: The present study considers some of the underlying mechanisms that may be acting in postnatal depression (PND). It has been suggested that rumination predicts problem solving ability and that child temperament and maternal attributions predict mother-infant bonding. This study aims to investigate the role that brooding and reflective rumination may play in predicting and mediating these relationships in postnatal women. Methods: Postnatal women were recruited to complete an online survey.190 women responded and completed the Edinburgh Postnatal Depression Scale (EPDS), Maternal Attribution Scale (MAS), Postpartum Bonding Questionnaire (PBQ), Parental Problem Solving Task (PPST), Rumination Response Scale (RRS), Infant Behaviour Questionnaire (IBQ) and a confidence in problem solving using a Visual Analogue Scale (VAS). Results: Analyses showed that reflective rumination mediated the relationship between low infant soothability and high negative attributions, on maternal problem solving. Reflective and Brooding Rumination also predicted confidence in problem solving and mother-infant bonding. Analyses showed that infant temperament (soothability and distress) and maternal attributions (positive and negative) predicted confidence in problem solving and mother-infant bonding Limitations: This study employed a correlational design and therefore all inferences regarding possible causal pathways are tentative. Limitations include the use of self report measures to assess mother-infant bonding and infant temperament. Additionally the PPST is a new measure which needs further validation. Conclusions: Reflective rumination may act as an adaptive strategy for women in the postnatal period when faced with difficult child temperaments, and for those employing negative attributions, when faced with parent specific problem solving tasks. In addition, Brooding and Reflective Rumination may be important in predicting difficulties in mother-infant bonding. Difficult Infant temperaments and less positive or more negative maternal attributions, may affect problem solving, confidence in problem solving and mother-infant bonding in the postnatal period. Future research should look to replicate these findings and explicate possible causal relationships within a postnatal population.

This report aims to increase the scientific knowledge about long-term prospects for the adhesive and adhesive joints for bonding of stainless steels. The effects of water, temperature and chemicals on the adhesive and adhesive joints are investigated. Stainless steel plates are pretreated with a primer and isopropanol, there after joined together with single lap modeling. The strength of the joint is tested with a tensile test and additionally a watertightness test is performed to determine if the joints are watertight. For this project three versions of stainless steels is used and two different technologies of two- part adhesives, silicone and silane-modified polymer and one technology of tape, a double coated acrylic foam tape are tested. The result shows that all the adhesives fails cohesively and that tape fails partly adhesively. Result shows that all tests are affected by water, temperature and chemicals on different levels but tape is affected the most with a minimum of 40% loss in shear strength. Watertightness test shows that aged tape joints are not watertight. The polymer shows no signs of decreasing in shear strength and is watertight, but does become more viscous by aging. The report shows that a possible combination of adhesive and pretreatment that can withstand the effects of water, temperature and chemicals is found. The polymer presents a possibility to bond stainless steel with a simple pretreatment. Tape didn’t pass the test in a suitable way but presents opportunities if a sufficient pretreatment can be found.

The high cost of repairing reinforced or prestressed concrete structures due to steel corrosion has driven engineers to look for solutions. Much research has been conducted over the last two decades to evaluate the use of Fiber Reinforced Polymers (FRPs) in concrete structures. Structural engineering researchers have been testing FRP to determine their usability instead of steel for strengthening existing reinforced concrete structures, reinforcing new concrete members, and for prestressed concrete applications. The high strength-to-weight ratio of FRP materials, especially Carbon FRP (CFRP), and their non-corrosive nature are probably the most attractive features of FRPs. In this study, an experimental program was conducted to investigate the flexural behavior of prestressed concrete beams pre-tensioned with CFRP strands. The bond characteristics were examined by means of experimentally measuring transfer length, flexural bond length, and bond stress profiles. A total of four rectangular beams pre-tensioned with one 0.5-in. diameter CFRP strand were fabricated and tested under cyclic loading for five cycles, followed by a monotonically increasing load until failure. In investigating bond properties, the experimental results were compared to the equations available in the literature. The results from the four flexural tests showed that the main problem of CFRP strands, in addition to their liner-elastic tensile behavior, was lack of adequate bonding between FRP and concrete. Poor bonding resulted in early failure due to slippage between FRPs and concrete. As a result, a new technique was developed in order to solve the bonding issues and improve the flexural response of CFRP prestressed concrete beams. The new technique involved anchoring the CFRP strands at the ends of the concrete beams using a new "steel tube" anchorage system. It was concluded that the new technique solved the bond problem and improved the flexural capacity by about 46%. A computer model was created to predict the behavior of prestressed beams pre-tensioned with CFRP. The predicted behavior was compared to the experimental results. Finally, the experimental results were compared to the behavior of prestressed concrete beams pre-tensioned with steel strands as generated by the computer model. The CFRP beams showed higher strength but lower ductility.

A study of how the matrix environment impacts the structure and IR spectra of N-acetylglycine conformers. The conformational composition of this compound is determined according to an analysis of the FTIR spectra of N-acetylglycine isolated in low temperature argon matrices. Bands of three N-acetylglycine conformers are identified based on the spectra: one major and two minor. The structure of all observed conformers is stabilized by different intramolecular hydrogen bonds. The Gibbs free energies of the conformers were calculated (CCSD(T)/CBS method), and these energy values were used to calculate conformer population at a temperature of 360 K, of which 85.3% belonged to the main conformer, and 9.6% and 5.1% to the minor conformers. We also determined the size and shape of the cavities that form when the N-acetylglycine conformers are embedded in the argon crystal during matrix deposition. It is established that the most energetically favorable cavity for the planar main conformer is the cavity that forms when 7 argon atoms are replaced. At the same time, bulky minor conformers were embedded into cavities that correspond to 8 removed argon atoms. We calculated the complexation energy between argon clusters and conformers, and the deformation energy of the argon crystal and the N-acetylglycine conformers. The matrix-induced shifts to the conformer oscillation frequency are calculated. Published by AIP Publishing.

This research has investigated proton-coupled electron transfer (PCET) of quinone/hydroquinone and other simple organic PCET species for the purpose of furthering the knowledge of the thermodynamic and kinetic effects due to reduction and oxidation of such systems. Each of these systems were studied involving the addition of various acid/base chemistries to influence the thermodynamics and kinetics upon electron transfer. It is the expectation that the advancement of the knowledge of acid/base catalysis in electrochemistry gleaned from these studies might be applied in fuel cell research, chemical synthesis, the study of enzymes within biological systems or to simply advance the knowledge of acid/base catalysis in electrochemistry. Furthermore, it was the intention of this work to evaluate a system that involved concerted-proton electron transfer (CPET), because this is the process by which enzymes are believed to catalyze PCET reactions. However, none of the investigated systems were found to transfer an electron and proton by concerted means. Another goal of this work was to investigate a system where hydrogen bond formation could be controlled or studied via electrochemical methods, in order to understand the kinetic and thermodynamic effects complexation has on PCET systems. This goal was met, which allowed for the establishment of in situ studies of hydrogen bonding via 1H-NMR methods, a prospect that is virtually unknown in the study of PCET systems in electrochemistry, yet widely used in fields such as supramolecular chemistry. Initial studies involved the addition of Brønsted bases (amines and carboxylates) to hydroquinones (QH2’s). The addition of the conjugate acids to quinone solutions were used to assist in the determination of the oxidation processes involved between the Brønsted bases and QH2’s. Later work involved the study of systems that were initially believed to be less intricate in their oxidation/reduction than the quinone/hydroquinone system. The addition of amines (pyridine, triethylamine and diisopropylethylamine) to QH2’s in acetonitrile involved a thermodynamic shift of the voltammetric peaks of QH2 to more negative oxidation potentials. This effect equates to the oxidation of QH2 being thermodynamically more facile in the presence of amines. Conjugate acids were also added to quinone, which resulted in a shift of the reduction peaks to more positive potentials. To assist in the determination of the oxidation process, the six pKa’s of the quinone nine-membered square scheme were determined. 1H-NMR spectra and diffusion measurements also assisted in determining that none of the added species hydrogen bond with the hydroquinones or quinone. The observed oxidation process of the amines with the QH2’s was determined to be a CEEC process. While the observed reduction process, due to the addition of the conjugate acids to quinone were found to proceed via an ECEC process without the influence of a hydrogen bond interaction between the conjugate acid and quinone. Addition of carboxylates (trifluoroacetate, benzoate and acetate) to QH2’s in acetonitrile resulted in a similar thermodynamic shift to that found with addition of the amines. However, depending on the concentration of the added acetate and the QH2 being oxidized, either two or one oxidation peak(s) was found. Two acetate concentrations were studied, 10.0 mM and 30.0 mM acetate. From 1H-NMR spectra and diffusion measurements, addition of acetates to QH2 solutions causes the phenolic proton peak to shift from 6.35 ppm to as great as ~11 ppm, while the measured diffusion coefficient decreases by as much as 40 %, relative to the QH2 alone in deuterated acetonitrile (ACN-d3). From the phenolic proton peak shift caused by the titration of each of the acetates, either a 1:1 or 1:2 binding equation could be applied and the association constants could be determined. The oxidation process involved in the voltammetry of the QH2’s with the acetates at both 10.0 and 30.0 mM was determined via voltammetric simulations. The oxidation process at 10.0 mM acetate concentrations involves a mixed process involving both oxidation of QH2 complexes and proton transfer from an intermediate radical species. However, at 30.0 mM acetate concentrations, the oxidation of QH2-acetate complexes was observed to involve an ECEC process. While on the reverse scan, or reduction, the process was determined to be an CECE process. Furthermore, the observed voltammetry was compared to that of the QH2’s with amines. From this comparison it was determined that the presence of hydrogen bonds imparts a thermodynamic influence on the oxidation of QH2, where oxidation via a hydrogen bond mechanism is slightly easier. In order to understand the proton transfer process observed at 10.0 mM concentrations of acetate with 1,4-QH2 and also the transition from a hydrogen bond dominated oxidation to a proton transfer dominated oxidation, conjugate acids were added directly to QH2 and acetate solutions. Two different acetate/conjugate acid ratios were focused on for this study, one at 10.0 mM/25.0 mM and another at 30.0 mM/50.0 mM. The results of voltammetric and 1H-NMR studies were that addition of the conjugate acids effects a transition from a hydrogen bond oxidation to a proton transfer oxidation. The predominant oxidation species and proton acceptor under these conditions is the uncomplexed QH2 and the homoconjugate of the particular acetate being studied, respectively. Furthermore, voltammetry of QH2 in these solutions resembles that measured with the QH2’s and added amines, as determined by scan rate analysis. In an attempt to understand a less intricate redox-active system under aqueous conditions, two viologen-like molecules were studied. These molecules, which involve a six-membered fence scheme reduction, were studied under buffered and unbuffered conditions. One of these molecules, N-methyl-4,4’-bipyridyl chloride (NMBC+), was observed to be reduced reversibly, while the other, 1-(4-pyridyl)pyridinium chloride (PPC+), involved irreversible reduction. The study of these molecules was accompanied by the study of a hypothetical four-membered square scheme redox system studied via digital simulations. In unbuffered solutions each species, both experimental and hypothetical, were observed to be reduced at either less negative (low pH) or more negative (high pH), depending on the formal potentials, pKa’s of the particular species and solution pH. The presence of buffer components causes the voltammetric peaks to thermodynamically shift from a less negative potential (low pH buffer) to a more negative potential (high pH buffer). Both of these observations have been previously noted in the literature, however, there has been no mention, to our knowledge, of kinetic effects. In unbuffered solutions the reduction peaks were found to separate near the pKa,1. While in buffered solutions, there was a noted peak separation throughout the pH region defined by pKa’s 1 and 2 (pKa,1 and pKa,2) of the species under study. The cause for this kinetic influence was the transition from a CE reduction at low pH to an EC reduction process at high pH in both buffered and unbuffered systems. This effect was further amplified via the study of the hypothetical species by decreasing the rate of proton transfer. In an effort to further this work, some preliminary work involving the attachment of acid/base species at the electrode surface and electromediated oxidation of phenol-acetate complexes has also been studied. The attachment of acid/base species at the surface is believed to assist in the observation of heterogeneous acid/base catalysis, similar to that observed in homogeneous acid/base additions to quinone/hydroquinone systems. Furthermore, our efforts to visualize a concerted mechanism are advanced in our future experiments involving electromediated oxidation of phenol-acetate complexes by inorganic species. It may be possible to interrogate the various intermediates more efficiently via homogeneous electron-proton transfer rather than heterogeneous electron transfer/homogeneous proton transfer.