No description available.

No description available.

No description available.

Rare Earth Elements (REEs: La–Lu, Y, and Sc) are critical components for technological innovations, therefore more effective methods for the domestic extraction and purification of REEs are in ever-increasing demand. Metal-chelating polymers have great potential in these applications due to their relatively low cost and high affinity for target elements. However, while much research has focused on specific ligands attached to polymers, little is known about the effect of polymer architecture itself on metal chelation. This dissertation reports recent progress in the design, synthesis, and application of polymers for the chelation of various REEs. In addition to synthesizing a series of metal-chelating polymers, we elucidated the thermodynamics of binding using isothermal titration calorimetry (ITC) to gain insight into the specific relationship between polymer structure and metal binding. ITC enables the direct measurement of the binding affinity (Ka), enthalpy changes (ΔH), and stoichiometry of the interactions between macromolecules and metal ions in solution. The thermodynamics of metal chelation underpins many technologies for REE extraction. Consequently, elucidating these parameters enables the rational design of future materials. / Doctor of Philosophy / Rare-Earth Elements (REEs) are critical metals used in many modern technologies, therefore more effective methods for the recovery and purification of REEs are in ever-increasing demand. Metal-chelating polymers—materials that can bind metals—have great potential in these applications due to their relatively low cost and high affinity for target elements. However, while much research has focused on the specific metal-binding group attached to the polymer, little is known about the effect of polymer architecture itself on metal chelation. This dissertation reports recent progress in the design, synthesis, and application of materials that bind to various REEs. In addition to synthesizing a series of metal-binding polymers, we measured the heat absorbed or produced during metal-binding interactions. These experiments produced fundamental insights into the interactions between the polymers, metals ions, and water molecules in solution. Overall, this work produces a depiction of the polymer–metal binding process, which enables insight into each polymer's properties as a metal-binding material. Future researchers can use these guidelines to develop the next generation of materials for the extraction of these critical metals.

The heats of immersion in n-alcohols of zeolites NaY, 5A and ZSM-5 and the kinetics of the immersion process have been determined using a Calvet MS-70 microcalorimeter. The specific heat of immersion decreased non-linearly as a function of chain length of alcohol for NaY and 5A. In contrast, the specific heat of immersion passed through a maximum at n-pentanol for ZSM-S. The specific immersion time as a function of chain length of alcohol showed an apparent linear increase in the order 5A > ZSM-S > NaY. NaY showed almost no increase. The effects of sample evacuation temperature and butyl alcohol isomer bulk on the heats of immersion were also investigated. These results were interpreted in terms of molecular accessibility of the wetting liquid into the pores of the zeolites and in terms of the Si/Al ratio of the zeolites. The overall kinetics of immersion appears to be first order. / Master of Science

A superconducting niobium triaxial cavity has been designed and fabricated to study residual surface resistance of planar superconducting materials. Unlike many other structures where the test samples are placed in strong magnetic field positions, the edge of a 25.4 mm or larger diameter sample in the triaxial cavity is located outside the strong field region. Therefore, the edge effects and possible losses between the thin film and the substrate have been minimized in this design, ensuring that the induced RF losses are intrinsic to the test material. The fundamental resonant frequency of the cavity is 1.5 GHz, the same as the working frequency of CEBAF cavities. The cavity has a compact size compared to its TE₀₁₁ counterpart, which makes it more sensitive to the sample's loss. / Ph. D.

No / Pterin-4a-carbinolamine dehydratase (PCD) is an essential component of the phenylalanine hydroxylase (PAH) system, catalyzing the regeneration of the essential cofactor 6(R)-L-erythro-5,6,7,8-tetrahydrobiopterin [6(R)BH4]. Mutations in PCD or its deactivation by hydrogen peroxide result in the generation of 7(R,S)BH4, which is a potent inhibitor of PAH that has been implicated in primapterinuria, a variant form of phenylketonuria, and in the skin depigmentation disorder vitiligo. We have synthesized and separated the 7(R) and 7(S) diastereomers confirming their structure by NMR. Both 7(R)- and 7(S)BH4 function as poor cofactors for PAH, whereas only 7(S)BH4 acts as a potent competitive inhibitor vs. 6(R)BH4 (Ki=2.3–4.9 μM). Kinetic and binding studies, as well as characterization of the pterin-enzyme complexes by fluorescence spectroscopy, revealed that the inhibitory effects of 7(R,S)BH4 on PAH are in fact specifically based on 7(S)BH4 binding. The molecular dynamics simulated structures of the pterin-PAH complexes indicate that 7(S)BH4 inhibition is due to its interaction with the polar region at the pterin binding site close to Ser-251, whereas its low efficiency as cofactor is related to a suboptimal positioning toward the catalytic iron. 7(S)BH4 is not an inhibitor for tyrosine hydroxylase (TH) in the physiological range, presumably due to the replacement of Ser-251 by the corresponding Ala297. Taken together, our results identified structural determinants for the specific regulation of PAH and TH by 7(S)BH4, which in turn aid in the understanding of primapterinuria and acute vitiligo. —Pey, A. L., Martinez, A., Charubala, R., Maitland, D. J., Teigen, K., Calvo, A., Pfleiderer, W., Wood, J. M., Schallreuter, K. U. Specific interaction of the diastereomers 7(R)- and 7(S)-tetrahydrobiopterin with phenylalanine hydroxylase: implications for understanding primapterinuria and vitiligo

This report represents an overall view on thermodynamical studies of wastewater treatment plant, concepts like exergy, emergy and entropy. In addition, there has been an introduction of calorimetry. A common unit of measurement of organic contents in wastewater treatment facilities is COD. However, the unit of measurement which shows the sustainability of an industry is exergy and emergy. According to the calculations represented in this report it has been tried to make a correlation between the COD and exergy in order to make it easier to assess the sustainability of a treatment plant. The calorific measurement methods which have been used in the food science can also be used in wastewater treatment industry. Therefore, it is possible to replace COD and BOD measurement devices with online calorific measurements. It has been tried to find a correlation between exergy value and calorific contents. Accordingly, if the calorific values in wastewater input and output are known they can be transferred into exergy values. The energy and exergy production from wastewater has been observed in a Microbial Fuel Cell made in the laboratory and the measured values of current produced by the microbial activities has been analyzed in this report. For future studies, exergy can be used directly in modeling a wastewater treatment plant and improving an already made one.

ransition metals are micronutrients that play critical roles in all forms of life, acting as stabilizing ions, catalytic centers, and as signaling ions. Due to their importance, classes of biomolecules have been designed with the sole purpose of regulating their intracellular concentrations. One group of which are transcription factors, which regulate intracellular metal concentration by activating or repressing transcription, dependent on metal availability. The activation of transcription factors by metal availability can be attested to conformational changes that are governed by both dynamics and thermodynamics. Due to the influential nature of transcription factors, their activity and activation mode have become a popular research field as well as targets for pharmaceuticals. This dissertation reports the biophysical characterizations of three distinct metal?dependent transcription factors of S. pneumoniae, a facultative anaerobic pathogen, with robust micronutrient regulatory systems. Chapter II describes the Adhesin Competence Repressor (AdcR) is a zinc(II) dependent uptake regulator that, although being biologically and crystallographically characterized, is not well understood in the thermodynamics that govern its activity. Chapter III investigates the Streptococcal czcD activator (SczA), another zinc(II) dependent transcription factor, which controls zinc(II) efflux, and has limited research performed aimed at describing its activity. Chapter IV explores copper regulation by the cop repressor (CopR), an oxidation-dependent transcriptional regulator. Techniques including differential scanning calorimetry (DSC), isothermal titration calorimetry (ITC), circular dichroism (CD), fluorescence spectroscopy, and UV-Vis spectroscopy were utilized to describe the thermodynamics and structural effects of metal ion and DNA binding. These provide insight into the activation mode and regulatory mechanisms of AdcR, SczA, and CopR.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-17T10:53:24Z No. of bitstreams: 1 2016 - Monique Barreto Santos.pdf: 2356049 bytes, checksum: 8a379b47682a5e067746503ee59b6d27 (MD5) / Made available in DSpace on 2016-10-17T10:53:24Z (GMT). No. of bitstreams: 1 2016 - Monique Barreto Santos.pdf: 2356049 bytes, checksum: 8a379b47682a5e067746503ee59b6d27 (MD5) Previous issue date: 2016-02-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Proteins are biopolymers of high nutritional and functional significance has been widely used as food ingredients. The interaction between two different proteins oppositely charged, and can give rise to complex coacervate currently used as an ingredient in food technology or as a microencapsulating agent. The formation of complex coacervates between Lysozyme and Ovalbumin and between Bovine serum albumin (BSA) and Lysozyme has been investigated as a function of pH, mass ratio of total and concentration of NaCl. For both interactions studied, complexing latched in a wide pH range which corresponds to the interval between the pI of proteins. Among Ovalbumin and Lysozyme interaction was more intense in the ratio r = 1 at pH 7.5 and BSA and Lysozyme most complex formation has occurred on the ratio r = 0.5 and pH 9.0. Changes in the ionic strength by adding NaCl negatively affected the interaction between Lysozyme and BSA already at a concentration of 0.01 mol / L and 0.03 mol / L abolished the interaction between Lysozyme and Ovalbumin. Through Potential - zeta can be seen that the formation of insoluble complexes was highest near the pI for all studied reasons, indicating that the interaction is given by neutralization of opposite charges. The Infrared spectra suggested that electrostatic interactions led interactions however, hydrogen bonds also had a hand in the coacervation process for the proteins under study. The micrographs showed that the insoluble complexes showed spherical structure and particle size showed the formation of structures with an average size around 2 ?m, much larger than the observable size for the isolated proteins. The isothermal titration calorimetry showed that the interaction between Lysozyme and Ovalbumin was exothermic and was performed in two steps, the first and second entropy directed enthalpy driven. The differential scanning calorimetry suggested the presence of a single point of denaturation, that the interaction between Lysozyme and BSA led to a new biopolymer with denaturation temperature 67 ? C differs from isolated proteins. These studies suggested that complex coacervates formed between Ovalbumin / Lysozyme and BSA / Lysozyme could be used as the encapsulating bioactive agent or as food ingredients in order to add nutritional value. / Prote?nas s?o biopol?meros de grande import?ncia nutricional e funcional tendo sido amplamente utilizadas como ingredientes alimentares. A intera??o entre duas prote?nas diferentes e opostamente carregadas pode dar origem aos complexo coacervado, atualmente utilizados como ingrediente na tecnologia de alimentos ou como agente de microencapsula??o. A forma??o de complexos coacervados entre Ovalbumina e Lisozima e entre Albumina s?rica bovina (BSA) e Lisozima foi investigada em fun??o do pH, raz?o de massa total e concentra??o de NaCl. Para as duas intera??es estudadas, a complexa??o acorreu em uma ampla faixa de pH, que corresponde ao intervalo entre os pI das prote?nas. Entre Ovalbumina e Lisozima a intera??o foi mais intensa na raz?o r=1 em pH 7,5 e para BSA e Lisozima a maior forma??o de complexos ocorreu na raz?o r=0,5 e pH 9,0. Altera??es na for?a i?nica por adi??o de NaCl influenciaram negativamente a intera??o entre Albumina BSA e Lisozima j? na concentra??o de 0,01 mol/L e a 0,03 mol/L suprimiu a intera??o entre Ovalbumina e Lisozima. Por meio do Potencial - zeta pode-se verificar que a forma??o de complexos insol?veis foi m?xima pr?ximo ao pI para todas as raz?es estudadas, indicando que a intera??o se deu por neutraliza??o de cargas opostas. Os espectros no infravermelho sugeriram que intera??es eletrost?ticas conduziram as intera??es no entanto, liga??es de hidrog?nio tamb?m tiveram participa??o no processo de coacerva??o para as prote?nas em estudo. As micrografias revelaram que os complexos insol?veis apresentavam estrutura esf?rica e o tamanho de part?cula demonstrou a forma??o de estruturas com tamanho m?dio em torno de 2 ?m, as quais s?o bem maiores do que o tamanho obervado para as prote?nas isoladas. A calorimetria de titula??o isot?rmica demonstrou que a intera??o entre Ovalbumina e Lisozima foi exot?rmica, a qual ocorreu em duas etapas, a primeira entropicamente dirigida e a segunda entalpicamente dirigida. A calorimetria diferencial de varredura sugeriu, pela presen?a de um ?nico ponto de desnatura??o, que a intera??o entre BSA e Lisozima deu origem a um novo biopol?mero com temperatura de desnatura??o a 67?C, diferente das prote?nas isoladas. Estes estudos sugeriram que complexos coacervados formados entre Ovalbumina / Lisozima e BSA / Lisozima poderiam ser utilizados como agente encapsulante de bioativos ou como ingredientes alimentares com o objetivo de agregar valor nutricional.