<p>Molecular recognition is arguably the most elementary physical process essential for life that arises at the molecular scale. Molecular recognition drives events across virtually all length scales, from the folding of proteins and binding of ligands, to the organization of membranes and the function of muscles. Understanding such events at the molecular level is massively complicated by the unique medium in which life occurs: water. In contrast to recognition in non-aqueous solvents, which are driven largely by attractive interactions between binding partners, binding reactions in water are driven in large measure by the properties of the medium itself. Aqueous binding involves the loss of solute-solvent interactions (desolvation) and the concomitant formation of solute-solute interactions. Despite decades of research, aqueous binding remains poorly understood, a deficit that profoundly limits our ability to design effective pharmaceuticals and new enzymes. Particularly problematic is understanding the energetic consequences of aqueous desolvation, an area the Toone and Beratan groups have considered for many years.</p><p> In this dissertation, we embark on a quest to shed new light on aqueous desolvation from two perspectives. In one component of this research, we improve current computational tools to study aqueous desolvation, employing quantum mechanics (QM), molecular dynamics (MD) and Monte Carlo (MC) simulations to better understand the behavior of water near molecular surfaces. In the other, we use a synthetic host, cucurbit[7]uril (CB[7]), in conjunction with a de novo series of ligands to study the structure and thermodynamics of aqueous desolvation in the context of ligand binding with atomic precision, a feat hitherto impossible. A simple and rigid macrocycle, CB[7] alleviates the drawbacks of protein systems for the study of aqueous ligand binding, that arise from conformational heterogeneity and prohibitive computational costs to model.</p><p> </p><p> We first constructed a novel host-guest system that facilitates internalization of the trimethylammonium (methonium) group from bulk water to the hydrophobic cavity of CB[7] with precise (atomic-scale) control over the position of the ligand with respect to the cavity. The process of internalization was investigated energetically using isothermal titration microcalorimetry and structurally by nuclear magnetic resonance (NMR) spectroscopy. We show that the transfer of methonium from bulk water to the CB[7] cavity is accompanied by an unfavorable desolvation enthalpy of just 0.49±0.27 kcal*mol-1, a value significantly less endothermic than those values suggested from previous gas-phase model studies. Our results offer a rationale for the wide distribution of methonium in biology and demonstrate important limitations to computational estimates of binding affinities based on simple solvent-accessible surface area approaches.</p><p> To better understand our experimental results, we developed a two-dimensional lattice model of water based on random cluster structures that successfully reproduces the temperature-density anomaly of water with minimum computational cost. Using reported well-characterized ligands of CB[7], we probed water structure within the CB[7] cavity and identified an energetically perturbed cluster of water. We offer both experimental and computational evidence that this unstable water cluster provides a significant portion of the driving force for encapsulation of hydrophobic guests.</p><p> The studies reported herein shed important light on the thermodynamic and structural nature of aqueous desolvation, and bring our previous understanding of the hydrophobic effect based on ordered water and buried surface area into question. Our approach provides new tools to quantify the thermodynamics of functional group desolvation in the context of ligand binding, which will be of tremendous value for future research on ligand/drug design.</p> / Dissertation

The aim of this thesis was to construct undergraduate chemistry students’ conceptions of enthalpy and its change, internal energy and its change, heat and work. Conceptions make it possible to identify students’ problems with the taught content. How students’ exam results are affected by qualitative/conceptual questions was also investigated. Two chemistry teachers in both secondary school and higher education participated in the first study. Thereafter, three empirical studies with undergraduate students were done, including a total number of 64, 22 and 10 participants. Methods and tasks from chemistry education research were used and new tasks were developed during the research process. Answers to questionnaires, hand-ins, exams and interview transcripts were analyzed qualitatively. The constructed conceptions were descriptive categories divided into two types, the underlying and the logical. Nine conceptions were constructed. Students expressed enthalpy change as heat at constant pressure like a mantra, since their responses to specific issues contradicted the explicitly used definition. An artifact was necessary to identify work and expansion work and technical work were primarily described as functions of volume. Enthalpy and enthalpy change were considered as a form of energy or as interchangeable. Students argued that enthalpy change and heat were the same, since the reactions were the same, regardless of constant pressure or constant volume. Enthalpy change was heat when no work was done. One possible explanation was that students argued that ΔU was the energy transferred as heat. Students’ interpretations of the tasks clarified that tasks can be further developed. On three of four exams students succeeded better when the qualitative/conceptual questions were excluded. The sample size affected the t-tests and only one result was significant. Implications for teaching and research are given. / Syftet med avhandlingen var att konstruera kemistudenters föreställningar om entalpi och dess förändring, inre energi och dess förändring samt värme och arbete. Föreställningar gör det möjligt att identifiera problemområden då ämnesinnehållet undervisas. Hur studenternas resultat på tentamen påverkades av att kvalitativa/konceptuella frågor inkluderades, undersöks också. En studie med två kemilärare på både gymnasiet och inom högre utbildning samt tre studier med totalt 64, 22 och 10 kemistudenter, på olika utbildningsnivåer inom högre utbildning, utfördes. Metoder och uppgifter från ämnesdidaktisk forskning användes och nya uppgifter utvecklades under forskningsprocessen. Svar på enkät-, inlämnings- och tentamensuppgifter samt intervjutranskript analyserades kvalitativt. Föreställningarna som konstruerades var beskrivande kategorier som delats in i två grupper, de underliggande och de logiska föreställningarna. Resultatet visade att studenterna uttryckte att entalpiförändringen är värme vid konstant tryck. Det var likt ett mantra eftersom de samtidigt bortsåg från uttrycket i resten av sina svar. För att arbete ska identifieras krävdes en artefakt och när tryckvolymarbete samt tekniskt arbete beskrevs var det primärt som en funktion av volymen. Entalpi och entalpiförändring tillämpades av studenterna som en energiform eller så var innebörden av begreppen densamma. Studenterna beskrev att samma reaktion ger samma entalpiförändring och värme oberoende av konstant tryck och volym. Vidare beskrevs entalpiförändringen som värmet när inget arbete sker. En möjlig förklaring var att studenterna argumenterade att ΔU var energiöverföringen som värme. Studenternas tolkningar av frågorna tydliggör att frågorna fortfarande kan utvecklas. På tre av fyra tentamina lyckades studenterna bättre när de kvalitativa/konceptuella frågorna exkluderades. t-testen utfördes på gränsen till sitt giltighetsområde och endast ett resultat var signifikant. Även om entalpi och dess förändring är viktiga inom teoribildningen visade empirin att studenterna inte kände till syftet med att införa begreppen i teoribildningen. Implikationer för undervisning och forskning ges.

The building sector has become the largest consumer of end use energy in the world, exceeding both the industry and the transportation sectors. Extensive types of energy saving techniques have been developed in the past two decades to mitigate the impact of buildings on the environment. Instead of the conventional active building environmental control approaches that solely rely on the mechanical air conditioning systems, increasing attention is given to the passive and mixed-mode approaches in buildings. This thesis aims to explore the integration of passive cooling approaches and active air conditioning approaches with different dehumidification features, by making effective use of the information on: 1) various dynamic response properties of the building system and mechanical plants, 2) diverse variations of the building boundary conditions over the whole operation process, 3) coupling effect and synergistic influence of the key operational parameters, and 4) numerous parameter conflicts in the integrated active-passive operation. These issues make the proposed integration a complex multifaceted process operation problem. In order to deal with these challenges, a systematic approach is developed by integrating a number of advanced building/system physical models and implementing well established advanced dynamic optimization algorithms. Firstly, a reduced-order model development and calibration framework is presented to generate differential-algebraic equations (DAE) based physical building models, by coupling with the high-order building energy simulations (i.e., EnergyPlus) and implementing MLE+ co-simulation programs in the Matlab platform. The reduced-order building model can describe the dynamic building thermal behaviors and address substantial time delay effects intrinsic in the building heat transfer and moisture migration. A calibration procedure is developed to balance the modelling complexity and the simulation accuracy. By making use of the advanced modeling and simulation features of EnergyPlus, the developed computational platform is able to handle real buildings with various geometric configurations, and offers the potential to cooperate with the dominant commercial building modeling software existing in the current AEC industry. Secondly, the physical model for the active air conditioning systems is developed, which is the other critical part for the dynamic optimization. By introducing and integrating a number of sub-models developed for specific building components, the model is able to specify the dynamic hygrothermal behavior and energy performance of the system under various operating conditions. Two representative air conditioning systems are investigated as the study cases: variable air volume systems (VAV) with mechanical dehumidification, and the desiccant wheel system (DW) with chemical dehumidification. The control variables and constraints representing the system operational characteristics are specified for the dynamic optimization. Thirdly, the integrated active-passive operations are formulated as dynamic optimization problems based on the above building and system physical models. The simultaneous collocation method is used in the solution algorithm to discretize the state and control variables, translating the optimization formulation into a nonlinear program (NLP). After collocation, the translated NLP problems for the daily integrated VAV/DW operation for a case zone have 1605/2181 variables, 1485/2037 equality constraints and 280/248 inequality constraints, respectively. It is found that IPOPT is able to provide the optimal solution within minutes using an 8-core 64-bit desktop, which illustrates the efficiency of the problem formulation. The case study results indicate that the approach can effectively improve the energy performance of the integrated active-passive operations, while maintaining acceptable indoor thermal comfort. Compared to the conventional local control strategies, the optimized strategies lead to remarkable energy saving percentages in different climate conditions: 29.77~48.76% for VAV and 27.85~41.33% for DW. The energy saving is contributed by the improvement of both the passive strategies (around 33%) and active strategies (around 67%). It is found that the thermal comfort constraint defined in the optimization also affects the energy saving. The total optimal energy consumption drops by around 3% if the value of the predicted percentage dissatisfied (PPD) limit is increased by one unit between 5~15%. It is also found that the fitted periodic weather data can lead to similar operation strategies in the dynamic optimization as the realistic data, and therefore can be a reasonable alternative when the more detailed realistic weather data is not available. The method described in the thesis can be generalized to supervise the operation design of building systems with different configurations.

Die vorliegende Dissertation stellt die experimentelle Bestimmung von grundlegenden thermodynamischen und kinetischen Stoffdaten im System Lithium-Silicium vor. Ausgehend von der Synthese qualitativ hochwertiger Lithiumsilicide wurden Wärmekapazitäten über einen großen Temperaturbereich (2-873 K) bestimmt, die aufgrund der Ergebnisse bei tiefen Temperaturen die Ermittlung weiterer Parameter wie beispielsweise der Standardentropien bzw. der Bildungsentropien der Lithiumsilicide ermöglichte. Die Eigenschaft der Silicide, mit Wasserstoff Verbindungen einzugehen, führte zudem zur Ausdehnung der Untersuchungen auf das System Li-Si-H. Aus der Erweiterung resultierte neben der formalkinetischen Beschreibung ablaufender Gleichgewichtsreaktionen die Bestimmung von Bildungsenthalpien der Silicide. Auf Grundlage der experimentell bestimmten Stoffgrößen (Cp, S°, ∆BH°), die für theoretische und praxisrelevante Berechnungen sehr verlässliche Stoffdaten darstellen, wurden thermodynamische Modellierungen im stofflichen System durchgeführt.

Submitted by Maria Suzana Diniz (msuzanad@hotmail.com) on 2015-11-11T15:24:04Z No. of bitstreams: 1 arquivototal.pdf: 2659414 bytes, checksum: daffe4d3b79a46f98678d09a7952e81b (MD5) / Made available in DSpace on 2015-11-11T15:24:04Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2659414 bytes, checksum: daffe4d3b79a46f98678d09a7952e81b (MD5) Previous issue date: 2015-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work, will be characterized two types of adsorptive wheels, an active effect and the other passive effect, known respectively as desiccant wheel and enthalpy wheel. These devices are used to compose the climatization adsorption systems as a means of promoting the dehumidification of air using the adsorption phenomenon that occurs in their adsorptive matrices. This phenomenon involves both the mass transfer and the heat, its cycles are defined by two processes taking place simultaneously, the adsorption and desorption. In the study, the characterization will boil down to assess the equipment in different working conditions with the main objective to achieve better dehumidification of air using the least amount of energy possible. Procedures were used for low air flow rates set in three categories: the process flow, which is the airflow to be treated, or dehumidified, a regeneration flow, which is the air stream in countercurrent flow desiccant rotor with process flow will serve as a means of maintaining the adsorptive cycle always performing heat exchange and mass, and the return flow, which flow against the enthalpy rotor will also serve as a means of promoting the dehumidification of process air. In the regeneration flow rates will be assessed the effects of low temperature heating and in both wheels will be evaluated the effects of different rotational speeds. Will also take place, procedures in order to verify the possibility of the wheel enthalpy work as a wheel desiccant . The findings contributed significantly to the climate control by adsorption systems is taken increasingly as a viable alternative to replacing conventional cooling. / No presente trabalho foram caracterizados dois tipos de rotores adsortivos, um de efeito ativo e outro de efeito passivo, conhecidos respectivamente como rotor dessecante e rotor entálpico. Esses equipamentos são usados para compor os sistemas de climatização por adsorção como meio de promover a desumidificação do ar usando o fenômeno da adsorção que ocorre em suas matrizes adsortivas. Esse fenômeno envolve tanto a transferência de massa quanto a de calor, seus ciclos são definidos por dois processos que ocorrem simultaneamente, a adsorção e a dessorção. No estudo, a caracterização se resume em avaliar os equipamentos em diferentes condições de trabalho tendo como principal objetivo alcançar a melhor desumidificação do ar usando a menor quantidade de energia possível. Durante os procedimentos foram usadas baixas vazões de ar definidas em três categorias: a vazão de processo, que é a corrente de ar a ser tratada, ou seja, desumidificada, a vazão de regeneração, que é a corrente de ar que em contra fluxo no rotor dessecante com a vazão de processo servirá como meio de manter o ciclo adsortivo sempre realizando as trocas de calor e massa, e a vazão de retorno, que em contra fluxo no rotor entálpico servirá também como meio de promover a desumidificação do ar de processo. Nas vazões de regeneração foram avaliados os efeitos de baixas temperaturas de aquecimento e em ambos os rotores foram avaliados os efeitos de diferentes rotações. Foram realizados também, procedimentos com o intuito de verificar a possibilidade de o rotor entálpico trabalhar como rotor dessecante. Os resultados desse trabalho contribuíram significativamente para que os sistemas de climatização por adsorção seja tido cada vez como uma alternativa viável à substituição da refrigeração convencional.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The enthalpy of fusion of a perfect crystal of cellulose acetate was calculated in this thesis. In order to do so, cellulose samples from different sources were acetylated through the heterogenous acetilation methodology. The cellulose acetate samples were characterized by differencial scanning calorimetry (DSC) and by wide angle X-ray diffraction (WAXD). The X-ray diffractograms were deconvoluted into halos and peaks using the Pseudo-Voigt peak function of program Origin® 7.0. Two hypotheses were proposed in order to fit the deconvolution patterns into the two-phase model. In the first, the amorphous regions of the material was considered to be represented by the area of the halo located at 21º and the crystalline area by the maxima at 8º, 11º, 13º and 16º. In the second hypothesis, the amorphous region was considered to be represented by the areas of the maxima at 11º and 21º, and the crystalline region by the maxima at 8º, 13º and 16º. The WAXD crystallinities of the samples were then calculated from these values. The first hypothesis was ignored for presenting a very high crystallinity value for a sample that did not present an enthalpy of fusion. The second hypothesis was used, but the linear regression that defined the relationship between the enthalpy of fusion and the crystallinity of the materials was forced through zero. Through this relationship, the enthalpy of fusion of a perfect crystal of cellulose acetate was calculated to be 58.8 J/g. / A entalpia de fusão de um cristal perfeito de acetato de celulose foi calculada nessa dissertação. Para isso, amostras de celulose de diferentes origens foram acetiladas através do método de acetilação heterogêneo. As amostras de acetato de celulose foram caracterizadas por calorimetria diferencial de varredura (DSC) e difração de raios-X a alto ângulo (WAXD). Os difratogramas de raios-X foram deconvoluídos em halos e picos utilizando a função pico Pseudo-Voigt do programa Origin® 7.0. Duas hipóteses foram propostas para que as deconvoluções estivessem de acordo com o modelo de duas fases. Na primeira, foi considerado que a parte amorfa do material era representada pela área do halo localizado em 21º e a área cristalina pela soma das áreas dos máximos em 8º, 11º, 13º e 16º. Na segunda hipótese, a região amorfa foi considerada como sendo representada pelas áreas dos máximos em 11º e 21º, e a região cristalina pelos máximos em 8º, 13º e 16º. A partir desses valores se calculou a cristalinidade das amostras de acetato de celulose via WAXD. A primeira hipótese foi desconsiderada por apresentar um valor muito alto de cristalinidade para uma amostra que não apresentou entalpia de fusão. A segunda hipótese foi utilizada, porém a regressão linear que definiu a relação entre a entalpia de fusão e cristalinidade dos materiais foi forçada a passar pela origem. Através dessa relação, calculou-se a entalpia de fusão de um cristal perfeito de acetato de celulose como sendo 58,8 J/g. / Mestre em Química

Ce travail porte sur le développement de nouvelles méthodes de mesure permettant la caractérisation de réactions chimiques très exothermiques dans des conditions de sécurité. Pour cela, nous souhaitons combiner l’analyse thermique des réactions et la technologie microfluidique. L’utilisation de la microfluidique rend possible l’utilisation de très faibles volumes réactionnels limitant ainsi tout risque lié à la dangerosité des réactions explosives. Le premier appareil développé est un microcalorimètre qui mesure le flux de chaleur global dégagé lors d’un écoulement co-courant ou gouttes. Plusieurs paramètres peuvent être déterminés : enthalpie de mélange et de réaction, concentration par dosage calorimétrique et cinétique. Le deuxième dispositif consiste à mesurer le champ de température du milliréacteur isopéribolique à l’aide d’une caméra InfraRouge et ainsi de suivre localement l’évolution de la réaction pour déterminer les paramètres thermocinétiques. / This work deals with the development of new measurement methods in order to characterize high exothermic chemical reactions in safe conditions. Thus, we combine thermal analysis with microfluidic technology. The use of microfluidics allows to manipulate a very small amount of product safely. First, we have developed a microcalorimeter to measure the global heat flux produced in co-flow or droplet-flow configurations. Several parameters can be determined: reaction and mixing enthalpy, concentrations by calorimetric titration and kinetics. The second method uses an InfraRed camera to measure the temperature field of the isoperibolic millireactor. Then, the local evolution of the reaction is estimated by thermal processing. From such inverse methods, the thermokinetic parameters can be determined.

Orientadores: Pedro Luiz Onófrio Volpe, Ricardo Belchior Tôrres / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T22:29:35Z (GMT). No. of bitstreams: 1 Hoga_HeloisaEmi_D.pdf: 3636468 bytes, checksum: 5e4d8bd5f23dc45b0e386f59f4dd3f74 (MD5) Previous issue date: 2015 / Resumo: Propriedades excesso têm sido um caminho qualitativo e quantitativo para predizer o desvio da idealidade de soluções líquidas binárias. Além disso, as grandezas excesso têm sido usadas para desenvolver modelos e novas teorias de soluções. Neste trabalho teve como objetivo o estudo experimental de grandezas volumétricas, viscosimétricas, acústicas e das entalpias excesso de soluções líquidas binárias de água + etanol, ou + etileno glicol, ou + dietileno glicol, ou + trietileno glicol, ou + polietileno glicol 200 (PEG 200), ou + polietileno glicol 300 (PEG 300), ou + polietileno glicol 400 (PEG 400), ou + polietileno glicol 600 (PEG 600), ou + glicerol em função da composição, a diferentes temperaturas e à pressão atmosférica. Os dados de densidade e de velocidade do som foram determinados usando um densímetro e velocímetro (Anton Paar, Modelo DSA 5000). Os valores de viscosidade foram determinados usando um viscosímetro (Anton Paar, Modelo SVM 3000). Os valores da entalpia foram determinados utilizando um microcalorímetro (Thermal Activity Monitor, Titration mode, LKB2277, Thermometric). As temperaturas estudadas foram de 293,15, 298.15, 303,15 e 308,15 K. Somente a entalpia foi estudada a 298,15 K. Os resultados experimentais foram usados para calcular o volume molar excesso, o desvio da compressibilidade isentrópica, o desvio da viscosidade, a energia de Gibbs de ativação excesso e a entalpia molar excesso. As propriedades excesso foram correlacionadas usando os polinômios do tipo Redlich-Kister e Myers-Scott. Os resultados foram comparados e discutidos com base nas interações intermoleculares entre os componentes estudados / Abstract: Excess properties have been a qualitative and quantitative way to predict ideality deviation of liquid binary mixtures. Moreover the excess properties have been used to development molecular theories and new solution models. In this study, density, speed of sound, viscosity and enthalpy of binary mixtures of water + ethanol, or + ethylene glycol, or + diethylene glycol, or + triethylene glycol, or + polyethylene glycol 200, or + polyethylene glycol 300, or + polyethylene glycol 400, or + polyethylene glycol 600, or + glycerol have been determined as a function of composition at several temperatures and atmospheric pressure. The density and speed of sound data were determined using a density and sound velocity meter (Anton Paar, Model DSA 5000) The viscosity data was determined using a viscometer (Anton Paar, Model SVM 3000). The enthalpy date was determined using a microcalorimeter (Thermal Activity Monitor, Titration mode, LKB2277, Thermometric). The temperatures studied were 293.15, 298.15, 303.15 and 308.15 K. Only enthalpy data was measured at 298.15 K. The experimental results have been used to calculated the excess molar, deviations in isentropic compressibility, deviations in viscosity, excess Gibbs free energy of activation of viscous flow and excess molar enthalpy. The excess properties were correlated by using a Redlich-Kister and Myers-Scott polynomial equation. The results were discussed on the basis of intermolecular interactions between the components of the analyzed mixtures / Doutorado / Físico-Química / Doutora em Ciências

Goal of this dissertation is design of rotary reduction for entered input parameters that it is connected in parallel with reducing station. Further I´m looking into thermodynamic calculation of stage and chosen parts of turbine, making of project design of connection of rotary reduction to steam circulation. Dissertation is concluded by designed cross-section of turbine.

The main goal of master’s thesis is a propsal of the heat exchanger. The heat exchanger is double way of water side with the integrated air-vapor mixture cooler. Another aims are heat computation, heat loss computation, solidity dimensioning and selection of a material for a major selection. The last task is about detection of a vapor pressure trought the tube bundle.