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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
331

Micelas gigantes : o processo de formação e a influência da estrutura molecular dos co-solutos / Wormlike micelles : the process of formation and the influence of the molecular structures of co-solutes

Ito, Thiago Heiji, 1984- 04 July 2015 (has links)
Orientadores: Edvaldo Sabadini, René Alfonso Nome Silva / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T10:23:43Z (GMT). No. of bitstreams: 1 Ito_ThiagoHeiji_D.pdf: 8761085 bytes, checksum: 521d52e10af7805f341661ecc562599c (MD5) Previous issue date: 2015 / Resumo: Micelas gigantes têm sido muito estudadas desde os anos de 1980 e suas propriedades têm atraído a atenção tanto do setor produtivo quanto acadêmico. Aumento de viscosidade, capacidade de reduzir o atrito hidrodinâmico, formação de fluidos viscoelásticos e do tipo gel, são alguns dos fenômenos que fazem deste, um sistema de interesse em ambos os setores. Na literatura, está relatada uma grande quantidade de sistemas com propriedades particulares, inclusive, responsivos a estímulos luminosos, elétricos ou mudança no pH, todas advindas de diversas combinações entre diferentes componentes. No entanto, pouco se conhece a respeito dos fatores que levam à formação (crescimento), à estabilidade e, consequentemente, aos diversos fenômenos que despertam tanto interesse desse tipo de sistema supramolecular. Neste trabalho, buscou-se compreender e sistematizar a influência da estrutura molecular de vários compostos aromáticos na capacidade de induzir a formação de micelas gigantes com surfactantes catiônicos, além de uma interpretação baseada na termodinâmica para compreender o processo de crescimento deste sistema supramolecular. Para isso foram utilizadas várias técnicas como reologia, espalhamento de luz e nêutrons, e calorimetria de titulação isotérmica, que demonstraram uma grande influência de fatores estruturais dos co-solutos aromáticos como a presença de carga, hidrofobicidade e, especialmente, a capacidade de empacotamento devido à planaridade da molécula, demostrado pela primeira vez. Além disso, os ensaios de calorimetria e espalhamento de luz elucidaram como se dá o processo de crescimento da micela, bem como, mostraram a importância que a carga superficial do agregado tem para transição entre micelas curtas e alongadas / Abstract: Giant micelles have been studied since the 1980s and their properties have attracted the attention of both the productive sector and the academic. Viscosity increase, the ability in promote hydrodynamic drag reduction, formation of viscoelastic and gel-like fluids, are some of the phenomena that turn interesting the system in both approaches. In the literature, it is reported a large number of systems showing particular properties, including light, electrical stimuli or pH responsive, resulting from combinations of several different components. However, little is known about the factors that lead to formation (growth), stability and, consequently, to many phenomena which arouse such interest on that kind of supramolecular system. In this study, we tried to understand the influence of the molecular structure of various aromatic compounds in the ability to induce the formation of wormlike micelles with cationic surfactants, and an interpretation based on thermodynamics to understand the growth process of such supramolecular system. Several techniques like rheology, light and neutrons scattering, and isothermal titration calorimetry, have been used in order to study the system, which showed the influence of structural factors of the aromatic co-solutes such as presence of electrostatic charge, hydrophobicity, and the packing capacity due the planarity of the molecule, demonstrated for the first time. Additionally, calorimetric and light scattering measurements elucidated the growth process of the micelle, and showed the importance of the surface charge in transition between small and elongated micelles / Doutorado / Físico-Química / Doutor em Ciências
332

Desenvolvimento de algoritmo de clusterização para calorímetro frontal do experimento ALICE no LHC / Development of clustering algorithm for foward calorimeter in the ALICE experiment at the LHC

Danilo Anacleto Arruda da Silva 22 September 2014 (has links)
O Grande Colisor de Hádrons (Large Hadron Collider - LHC) é um acelerador de prótons e íons pesados localizado no CERN (Conseil Européen pour la Recherche Nucléaire). Em um de seus experimentos, ALICE (A Large Ion Collider Experiment ), está sendo projetado um detector dedicado a explorar os aspectos únicos de colisões núcleo-núcleo. A principal finalidade do ALICE é estudar a formação de um novo estado da matéria, o plasma de quarks e glúon. Para isto devem-se ter medidas precisas de hádrons, elétrons, múons e fótons produzidos em colisões chumbo-chumbo. Assim está sendo proposto um calorímetro frontal (Foward Calorimeter - FoCal) como um upgrade para o ALICE. A função deste calorímetro é o estudo das funções de distribuição de pártons (Partons distribuction Functions - PDF) no regime de pequenos valores do x de Bjorken. Nesta região é esperado que estas PDFs tenham um comportamento não linear devido ao processo de saturação de glúons. Para o estudo desta região é necessária a medida de fótons diretos produzidos na colisão. Estes, por sua vez, ficam mascarados pelo fundo de fótons provenientes do decaimento de píon, o que leva a uma necessidade de suas identificações. Com isto surge a oportunidade para a utilização do método de clusterização que é uma ferramenta de mineração de dados. Este trabalho contribuiu para o desenvolvimento inicial de um algoritmo de clusterização para o calorímetro FoCal. / The Large Hadron Collider (LHC) is a CERN\'s accelerator that collides protons and heavy ions. One of its experiments, ALICE, is building a new detector to explore new aspects of heavy ions collisions. The Alice\'s main goal is to study the formation of quark-gluon plasma (QGP). To do that it\'s necessary to get accurate data on hadrons, electrons, muons and gammas created in lead-lead collision. So, to accomplish that a new calorimeter is in study to scan the foward region of experiment, the Foward Calorimeter (FoCal). It\'s proposed to study Parton Distribution Functions (PDFs) in a regime of very small Bjorken-x, where it is expected that the PDFs evolve non-linearly due to the high gluon densities, a phenomena referred to as gluon saturation.But to do that it\'s required to measure the direct gammas created on collision. These fotons are blended on by fotons descendant of pion. So there\'s a need to separate it from the direct gammas. One way to solve this problem is to use clustering methods (a type of mining data algorithm). This work helped on early stages of development that clustering algorithm.
333

Photothermal Studies of Carboxymyoglobin

Small, Meagan 15 July 2010 (has links)
Small ligand diffusion in heme proteins is not fully understood. To help better understand CO diffusion, three systems were investigated: L29H/F43H site-directed sperm whale myoglobin, horse heart myoglobin in a heavy water buffer, and calix[4]resorcinarene. Binding of copper to calix[4]resorcinarene was photophysically characterized to unravel transient binding of small molecules in heme-copper proteins. Copper binding was found to have a low dissociation constant of approximately 8.6 micrometers.. Reaction profiles using photoacoustic calorimetry were constructed for the myoglobin systems. In deuterium oxide, ligand escape is not rate limited by water entry. Large enthalpy differences arise from the thermodynamic properties of deuterium oxide and the extensive hydrogen bonding network in myoglobin. In the mutant, CO rebinds primarily to the heme and is exothermic with a large volume contraction because of altered electrostatics within the binding pocket and higher water occupancy.
334

Gelace mucinu – příprava artificiálních modelů pro studium biologických mukózních systémů / Mucin hydrogels - artificial models of native mucus systems

Mikušová, Janka January 2021 (has links)
The scope of this masters thesis is the preparation of a model mucin system and its utilization as an artificial model of the native mucus system. The creation of this model system, according to several designed methods was a part of experimental part of the thesis. The preparation of mucin system comprised of physical and chemical methods of hydrogel formation, screening and characterisation of the various physical conditions of the mucin properties on its molecular level, and the preparation of sorbent with sorption surface containing mucin. Methods of light scattering, namely dynamic light scattering (DLS), used for mucin particles size change monitoring, and electroforetic light scattering (ELS), used for Zeta potential change monitoring, were used for the screening of the impact of physical factors on the properties of mucin.For the characterisation of impact of the temperature on changes in mucin sctructure was, apart from monitoring of light scattering, used also a diferential scanning calorimetry (DSC), which registered temperature value, at which mucin thermal denaturation occurs. In the next part of the thesis we subdued the created sorption surfaces to various physical-chemical analyses, which task is the characterisation and projection of surface and confirmation of mucin presence.Substancial part in monitoring and characterisation of changes in surface sctructure of sorption surface was accomplished by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscophy (SEM) was used for the final, more detailed, projection of the mucin enriched, sorbent surface structure. Suggested methods of mucin hydrogel, didnt prove sufficient results for the possibility of application of hydrogel as a artificial model of real mucus system, but the sorbent application was indicated as a suitable alternative and an instrument for the further mucin behaviour research and possibly subsequent bacterial adhesion, which represents the first step in the formation of the bacterial biofilm.
335

Příprava a průběh hydratace pojivového systému na bázi stroncium aluminátového cementu / Synthesis, properties and product of hydration of strontium aluminate cement

Kocián, Karel January 2015 (has links)
This diploma thesis deals with non-traditional binder, which is strontium aluminate, with his preparation and hydration. The behaviour of binary and ternary mixtures of strontium-calcium-barium aluminates was also studied. These aluminates were prepared by firing an equimolar mixture of aluminum oxide and the appropriate carbonate. Samples prepared this way, including their mixtures, were characterized by analytical methods such as X-ray diffraction analysis (XRD), thermal analysis with evolved gas analysis (TG-DTA and EGA), scanning electron microscopy (SEM), infrared spectroscopy (IR) and calorimetry, with the greatest importance for the study of the hydration process.
336

Vliv vztahu délky dolní končetiny a velikosti ráfku na psychofiziologickou odezvu organismu / Effect of lower limb length-bike rime size relationship on psychophysilogocal response of the organism

Sukovič, Richard January 2020 (has links)
VLIV VZTAHU DÉLKY DOLNÍ KONČETINY A VELIKOSTI RÁFKU NA PSYCHOFZIOLOGICKOU ODEZVU ORGANISMU Cíle: Cílem této práce je posoudit vliv délky dolní končetiny (DK) na psychofyziologickou odezvu organismu při jízdě na horském kole s odlišnými velikostmi ráfků. Metody: Soubor probandů tvořilo 20 mužů ve věku 26,4 ± 4,2 let. Jednalo se o experiment. Psychofyziologická odezva byla stanovena na základě výkonu (zajetého času), tepové frekvence a subjektivním hodnocení jízdních vlastností horského kola a vlastního vynaloženého úsilí hodnoceného na Borgově škále. Ke kontrolní analýze při testování byl použit přístroj MetaMax 3B. Testovány byly tři velikosti ráfků o stejné šíři plášťů. Jízdy byly realizovány na 800 m dlouhém okruhu. Testované osoby absolvovali každou jízdu s individuálně zvoleným fixním převodem v poloze v sedle s maximálním možným úsilím. Výsledky: Při jízdě na různě velkých ráfcích jsme u skupiny č. 2 (85 -90 cm DK) shledali velký rozdíl (P = 0,016) v dosažených časech při jízdě na různě velkých ráfcích. U skupiny č. 1 jsme shledali významné rozdíly v průměrné tepové frekvenci (P = 0,010), který činil 3 tepy a u subjektivního hodnocení vlastního vynaloženého úsilí pomocí Borgovy škály jsme se pohybovali na hranici významnosti (P = 0,060). Skupina č. 3 (97 - 101 cm DK) se pohybovala na hranici...
337

Zhodnocení ekonomiky lezení a fyziologické odezvy organizmu při různých rychlostech lezení / Movement economy and physiological response during differing climbing speeds in sport climbers

Podoba, Peter January 2020 (has links)
Title: Movement economy and physiological response during differing climbing speeds in sport climbers. Aims: The work aims to evaluace climbing economy and physiological responses of intermediate and advanced climbers in different climbing speeds. Methodology: 32 climbers (11 advanced men, 11 intermediate men, 10 intermediate women) performed 3 submaximal tests in treadwall at slope of 90ř at speeds 4, 6 and 9 m.min-1 . Each of the tests lasted exactly 4 minutes. Oxygen consumption (VO2), heart rate (HR), ventilation (VE), respiratory ratio (RER) and energy expenditure were monitored. Results: Advanced men reported lower energy expenditure than intermediate men in all climbing speeds (4 m.min-1 : -0,06 kcal.kg-1 , P = 0,007; 6 m.min-1 : -0,06 kcal.kg-1 P = 0,048; 9 m.min-1 : -0,07 kcal.kg-1 P = 0,022). Intermediate women reported only slightly lower energy expenditure than intermediate men (4 m.min-1 : -0,01 kcal.kg-1 P = 0,051; 6 m.min-1 : 0,06 kcal.kg-1 P = 0,091; 9 m.min-1 : -0,03 kcal.kg-1 P = 0,115). Energy expenditure was significantly lower at 4 m.min-1 than at 6 m.min-1 (-9,82 kcal, p = 0,001) and also signicantly lower at 6 m.min-1 than at 9 m.min-1 (-8,3 kcal, p = 0,001). Advanced men reported significantly lower VO2 at speeds 4 a 6 m.min-1 (- 2,2 ml.kg- 1 .min-1, P = 0,022; -3,9 ml.kg-1...
338

Exploring sources of variability in metal organic frameworks through high throughput adsorption and calorimetric methods / Exploration des sources de variabilité dans les réseaux métallo-organiques par adsorption à haut débit et méthodes calorimétiques

Iacomi, Paul Adrian 15 November 2018 (has links)
Les réseaux métallo-organiques (MOF) sont une nouvelle classe de matériaux poreux hybrides. Néanmoins leurs propriétés uniques introduisent également des difficultés significatives dans la caractérisation par adsorption de gaz. Dans cette thèse, la création d'un code source libre est détaillé, pour standardiser le traitement des isothermes. En utilisant ce code, un traitement à haut débit de plus de 18 000 isothermes est utilisé pour explorer l'échelle d'incertitude présente dans les données publiées sur l'adsorption dans les matériaux poreux. De plus, la mesure directe de l'enthalpie différentielle de l'adsorption en utilisant la microcalorimétrie s'avère être un excellent moyen d'obtenir la contribution des interactions particulières sur l'énergie d'adsorption. Ensemble, ces méthodes peuvent être utilisées pour étudier les sources d'incertitude des MOF. On étudie d’abord l’impact des défauts structurels au moyen d’une méthode post-synthétique alternative de génération de linker/cluster manquants dans l'UiO-66(Zr). Le traitement des matériaux pour leurs utilisations dans un environnement industriel par façonnage est étudié ici sous l’effet de la granulation par voie humide sur trois MOF topiques (UiO-66(Zr), MIL-100(Fe) et MIL-127(Fe)). Enfin, les comportements contre-intuitifs intrinsèques aux cristaux poreux «souples» sont étudiés, où la structure elle-même est responsable de la fluctuation dans les isothermes d'adsorption. Ici, une étude fondamentale sur un matériau flexible DUT-49 (Cu), apporte des informations sur la source de flexibilité induite par adsorption et sa changeabilité par modification structurelle / Metal organic frameworks (MOF) are novel adsorption materials with unique and desirable properties. However, structural defects, processing and structural compliance can lead to irreproducibility in adorption measurements. In this thesis, the creation of an open-source codebase is detailed, which is intended to standardize the processing of isotherms. Using this framework, high throughput processing of over 18 000 isotherms is used to explore the scale of uncertainty present in published adsorption data. Then, direct measurement of the differential enthalpy of adsorption using microcalorimetry is shown to be an excellent avenue of obtaining further insight into the contribution of guest-host and host-host interactions to the overall energetics of adsorption. Together, these methods are used to study some of the sources of the variability of MOFs, and quantify their effect. First, the impact of structural defects is investigated, through an alternative post-synthetic method of missing linker/cluster generation in the prototypical UiO-66(Zr) MOF. The processing of materials for their use in an industrial environment through shaping is another potential source of performance modification, which is here studied as the effect of wet granulation on three topical MOFs (UiO-66(Zr), MIL-100(Fe) and MIL-127(Fe)). Finally, counterintuitive behaviours intrinsic to ``soft'' porous crystals are investigated, where the structure itself is responsible for fluctuation in adsorption isotherms. A fundamental study on a copper paddlewheel based material, DUT-49(Cu) yields know-how on the source of adsorption induced compliance and its tunability through structural modification
339

Grain boundary wetting in the Al–Zn and Al–Mg alloys

Kogtenkova, O.A., Straumal, B.B. 17 September 2018 (has links)
No description available.
340

Investigation of Zinc Interactions to Human Serum Albumin and Their Modulation by Fatty Acids

Al-Harthi, Samah 03 1900 (has links)
Zinc is an essential metal ion for the activity of multiple enzymes and transcription factors. Among many other transporting proteins human serum albumin (HSA) is the main carrier of Zn(II) in the blood plasma. HSA displays multiple ligand binding sites with extraordinary binding capacity for a wide range of ions and molecules including fatty acids. Hence, HSA controls the availability and distribution of those molecules throughout the body. Previous studies have established that the existence of one zinc site with high affinity (MBS-A) that is modulated by the presence of fatty acids. Therefore, the fatty acid concentration in the blood influences zinc distribution which may result in a significant effect on both normal physiological processes and a range of diseases. Based on the current knowledge of HSA's structure and its coordination chemistry with zinc ion, here, we attempted to investigate zinc interactions and coordination with HSA and the effect of different fatty acids on the protein structure, stability and on Zn(II) binding. By NMR titration, we examine the Zn(II) binding to HSA and the spectra show distinct movements of some resonances showing a conformational change has occurred as a result of Zn(II) binding. Isothermal calorimetry titrations study was performed to evaluate zinc binding affinity to HSA in the absence and presence of fatty acids. Free HSA results indicates the existence of one high affinity site and multiple low affinity sites. Upon the binding of fatty acids to HSA, three distinct behaviors of Zn(II) affinity was observed ranging from no effect to moderate to significant depending on the FAs. By the use of circular dichroism, we investigate secondary and tertiary structure of HSA in the presence and absence of FAs and Zn(II). We found albumin is predominately α-helical and the overall conformation of the protein remains unchanged even after interacting with FAs and Zn(II) with some exception. The structural stability of HSA was evaluated by obtaining the denaturation temperature in the presence and absence of fatty acid and we found the thermal denaturation of HSA increases with the increase of amount of fatty acids.

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