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The structural, thermal, and fluid evolution of the Livingstone Range anticlinorium, and its regional significance to the southern Alberta foreland thrust and fold beltCooley, Michael Ames 08 April 2008 (has links)
The Livingstone Range anticlinorium (LRA) is a long (>65 km) narrow (<5 km) structural culmination that coincides with a major hanging-wall ramp across which the Livingstone thrust cuts ~1000 m up-section eastward from a regional décollement in the upper part of Devonian Palliser Formation to another regional décollement within Jurassic Fernie Formation. The presence of Precambrian basement fluids prior to thrusting and folding is recorded in the LRA by deformed jasper+/-fluorite+/-sphalerite veins, and adjacent haloes of altered dolomitic host rock with high 87Sr/86Sr ratios (0.7094 to 0.7100) relative to most host rocks. Basement fluids are a possible source for anomalously radiogenic strontium that occurs in the diagenetically altered Paleozoic carbonate rocks in the LRA and throughout the Western Canada Sedimentary Basin, but underlying thick shale strata such as the Exshaw Formation are also a possible source. The earliest stages of thrusting deformation involved the development of distinctive chevron-style, flexural-slip thrust-propagation folds that have conspicuous blind thrust faults along their hinge zones. The hinge-zone thrust system of the Centre Peak anticline consists of a series of stacked detachment thrusts, each of which emerges from a different zone of interbed slip in the backlimb of the anticline and deflects the hinge zone eastward. Each successively higher detachment thrust dies out in the hinge zone at approximately the same stratigraphic level at which an overlying detachment thrust fault emerges from a bedding detachment zone in the backlimb. Fluid flow during thrust-propagation folding is recorded by dolomite+/-calcite veins with isotopic compositions that are similar to those of host rocks. Fluid flow occurred along faults related to thrust-propagation folding, and also along many tear faults and larger thrust faults. Veins in these fault zones have slightly higher 87Sr/86Sr ratios relative to adjacent host rocks and are interpreted to have formed from a mixture of formation fluids and hotter basement fluids in a rock-dominated system. Oxygen isotope thermometry of four syn-folding veins indicates they precipitated at anomalously high temperatures (>250°C). The youngest episode of fluid flow along thrust faults and tear faults is recorded by calcite veins with very low δ18O values (-18 to -9‰ PDB), which are interpreted to have precipitated along faults that were active while the LRA was being transported eastward and elevated by underlying thrust faults, and cooled by infiltrating meteoric water. The conduits along which significant meteoric fluid circulation occurred are marked by visibly altered host rocks that have anomalously low δ18O values and slightly lower δ13C values relative to most host rocks.
Rapid cooling due to deep infiltration of meteoric water into the shallow brittle surface of the deforming earth is almost certainly not restricted to thrust and fold belts, nor is its thermal effect necessarily restricted to the upper few kilometers. This model for fluid flow has significant implications for predicting thermal conditions in deep metamorphic rocks that lie beneath the brittle crust, the most obvious effect being to push down the brittle/ductile transition zone, which would enhance even deeper meteoric fluid circulation and cause the deflection of underlying isotherms. / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2007-11-01 15:25:23.854
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Managing Environmental Risk in the Oil and Gas IndustryConner, Haley 01 January 2015 (has links)
Oil and gas industry operations place large pressures on the local environment and inhabitants. However, the continued rise in the demand for useable energy and resources has resulted in further production pressures for oil and gas companies. Meeting these demands comes with high risks and costs to both society and the environment. Oil and gas companies are thus faced with the challenge of meeting the world’s expanding energy demands while minimizing the negative externalities associated with these operations.
Many of the risks these corporations face are site specific, requiring detailed background research and precautionary measures that cannot be solved using a generalized framework. This paper aims to address these environmental operating concerns through risk management recommendations for oil and gas companies. If oil and gas corporations are able to embed environmental concerns into all aspects of daily operations, these companies can achieve socially beneficial outcomes, while avoiding potential disasters and more stringent legislation.
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Distal chevron osteotomy for hallux valgus surgery:role of fixation and postoperative regimens in the long-term outcomes of distal chevron osteotomy – a randomised, controlled, two-by-two factorial trial of 100 patientsPentikäinen, I. (Ilkka) 10 November 2015 (has links)
Abstract
Hallux valgus is a very common foot deformation and it is also very common reason for orthopaedic surgery in Western industrialised countries, including Finland. In Finland, about 90% of the patients are women.
Several early studies support the opinion that distal chevron osteotomy is a predictably successful treatment for mild-to-moderate hallux valgus deformities. Nevertheless, the necessity of chevron osteotomy fixation is controversial and only limited evidence supports the effectiveness of postoperative regimens. In this prospective randomised study, we compared the long-term results of 2 operative techniques (osteotomy fixation versus no fixation) and 2 postoperative regimens (a soft cast versus an elastic bandage) in 100 patients who underwent surgery for hallux valgus. Clinical evaluations based on the American Orthopedic Foot and Ankle Society (AOFAS) scale scoring were performed at baseline and again at 6 weeks, 6 months, 1 year, and a mean of 7.9 years postoperatively. Radiographic measurements were also made of the hallux valgus angle (HVA), first intermetatarsal angle (I/II IMA), distal metatarsal articular angle (DMAA), sesamoid position (LaPorta), congruence of the first metatarsophalangeal joint and the shift of the metatarsal head. Intraobserver repeatability and inter-observer reliability of radiographic measurements were evaluated by an experienced orthopaedic surgeon and an experienced radiologist.
The mean AOFAS function scores were better in the group treated without osteotomy fixation and with an elastic bandage at 6 weeks postoperatively, but the difference disappeared at later dates. AOFAS scores were significantly worse when the preoperative hallux valgus angle exceeded 30 degrees. The AOFAS scores did not differ statistically among the groups in our population.
Radiological recurrence of hallux valgus deformity of 15 degrees or more was very common at long-term follow-up after distal chevron osteotomy. Preoperative congruence, DMAA, sesamoid positon (LaPorta), HVA and I/II IMA affected recurrence. All recurrences were painless; thus, no revision surgery was required.
A statistically higher metatarsal head shift was observed in the fixation group, but the clinical significance of 0.8 mm was very small.
The experienced orthopaedic surgeon and experienced radiologist each exhibited good repeatability and reliability.
Based on this study, the fixation of the distal chevron osteotomy is not necessary, nor is a rigid soft cast bandage required. The risk of recurrence of hallux valgus is higher when the preoperative HVA is 30 degrees or over. / Tiivistelmä
Vaivaisenluu on hyvin yleinen jalan epämuotoisuus ja se on myös hyvin yleinen syy jalkakirurgiaan läntisissä teollistuneissa maissa ja myös Suomessa. Noin 90 % suomalaisista potilaista on naisia.
Useat aiemmat tutkimukset tukevat mielipidettä, jonka mukaan ensimmäisen jalkapöydänluun alaosan V-muotoinen luunkorjausleikkaus näyttäisi olevan suositeltava hoito lievän ja kohtalaisen vaivaisenluun hoidossa.
Luunkorjauksen kiinnityksen tarpeellisuus on kiistanalainen ja todisteet leikkauksen jälkeisen hoidon tehosta ovat rajalliset. Tässä eteenpäin suuntautuvassa, satunnaistetussa tutkimuksessa vertasimme kahden leikkaustekniikan (luunkorjauksen kiinnitys/ei kiinnitystä) ja kahden leikkauksen jälkeisen hoidon (kevyt kipsisidos/elastinen tukisidos) pitkäaikaistuloksia 100 potilaalla, jotka hoidettiin vaivaisenluun vuoksi. Kliininen arviointi suoritettiin Amerikan ortopedisen jalka- ja nilkkayhdistyksen pisteytyksen mukaan (AOFAS) ennen leikkausta ja 6 viikkoa, 6 kuukautta, 1 vuosi sekä keskimäärin 7.9 vuotta leikkauksen jälkeen. Samoin röntgenkuvista mitattiin vaivaisenluukulma (HVA), ensimmäisen ja toisen jalkapöydänluun välinen kulma (I/II IMA), ensimmäisen jalkapöydänluun alapään nivelpinnan kulma (DMAA), jänneluun asema (LaPorta), ensimmäisen jalkapöydänluun ja varpaan välisen nivelen asento sekä leikkauksessa tapahtunut jalkapöydänluun pään siirto. Röntgenkuvista tehtyjen mittausten toistettavuus ja luotettavuus arvioitiin kokeneen ortopedin ja kokeneen röntgenlääkärin välillä.
Keskimääräiset AOFAS toimintapisteet olivat parempia siinä leikkausryhmässä, jossa luunkorjausta ei kiinnitetty ja leikkauksen jälkeen käytettiin joustavaa tukisidosta 6 viikon kontrollissa, mutta seurannassa ero hävisi. AOFAS-pisteet olivat merkittävästi huonommat, jos vaivaisenluukulma oli ennen leikkausta yli 30 astetta. Aineistossamme AOFAS-pisteet eivät eronneet tilastollisesti merkittävästi eri ryhmien välillä.
Röntgenkuvissa vaivaisenluukulman uusiutuminen 15 asteeseen tai sen yli oli hyvin tavallinen jalkapöydänluun alaosan chevron osteotomian jälkeisessä pitkäaikaisseurannassa.
Ennen leikkausta arvioidut nivelen asema, DMAA, LaPorta, HVA ja I/II IMA vaikuttivat uusiutumiseen. Kaikki uusiutumiset olivat kivuttomia ja uusintaleikkauksia ei tarvittu.
Ryhmässä, jossa luunkorjaus kiinnitettiin, jalkapöydänluun pään siirto pysyi tilastollisesti paremmin, mutta 0.8 mm:n eron kliininen merkitys on olematon.
Röntgenkuvista tehtyjen mittausten toistettavuus ja luotettavuus olivat hyviä sekä ortopedilla että röntgenlääkärillä.
Tämän tutkimuksen perusteella ensimmäisen jalkapöydänluun alaosan luunkorjauksen kiinnittäminen ei ole tarpeellista eikä myöskään ole tarpeen käyttää kipsisidosta. Vaivaisenluun uusiutumisen riski on suurempi, jos vaivaisenluukulma on ennen leikkausta 30 astetta tai enemmän.
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Influencia de la magnitud del desplazamiento lateral de la cabeza metatarsal tras la osteotomía en chevron para hallux valgus sobre el resultado reportado por el pacienteBello-Tejeda, Laiz Lissette 09 March 2023 (has links)
Antecedentes: El hallux valgus (HV) es la patología del antepié más frecuente en adultos. Una de las técnicas quirúrgicas más ampliamente aceptada para su corrección es la osteotomía en chevron, cuyo objetivo es la realineación del primer metatarsiano mediante el desplazamiento lateral de su cabeza. Actualmente, no se ha determinado qué magnitud constituye un desplazamiento adecuado y satisfactorio para el paciente. Objetivos: El objetivo principal era analizar la influencia de la magnitud del desplazamiento lateral de la cabeza metatarsiana tras la osteotomía distal en chevron del primer metatarsiano sobre los resultados reportados por el paciente. Los objetivos secundarios fueron: (1) Identificar el desplazamiento mínimo de la cabeza metatarsiana necesario para obtener un resultado satisfactorio; (2) Evaluar si la posición sesamoidea cambiaba con el tiempo e influía en el resultado reportado por el paciente. Material y Métodos: Estudio de cohortes, prospectivo y comparativo de una muestra de 97 pacientes. El resultado clínico se evaluó mediante el cuestionario de calidad de vida Self-reported foot and ankle score (SEFAS), escala funcional de la Sociedad Americana del Pie y Tobillo (AOFAS), escala analógica visual del dolor (EVA) y satisfacción final del paciente con una escala Likert. Radiológicamente, el desplazamiento lateral de la cabeza metatarsiana fue cuantificado mediante: a) ángulo intermetatarsiano (AIM); y b) desplazamiento lineal lateral. Los pacientes se distribuyeron en dos grupos según presentaran un incremento postoperatorio mayor o igual o menor de la diferencia mínima clínicamente importante (DMCI) de 9 puntos en la escala SEFAS. Para el objetivo secundario (1) se realizó un análisis ROC, y para el (2) los pacientes se agruparon respecto a la posición sesamoidea obtenida con la cirugía. Resultados: No se encontró asociación significativa entre la magnitud del desplazamiento lateral de la cabeza metatarsiana medido mediante el AIM y la escala SEFAS al final del seguimiento. Aplicando una curva ROC, no se obtuvo un punto de corte significativo en el AIM para discriminar a los pacientes con un incremento igual o mayor a la DMCI en el resultado SEFAS final (área bajo la curva, AUC= 0,46; p= 0,611). Igualmente, no hubo un punto de corte significativo para el desplazamiento lineal lateral (AUC 0,47; p= 0,730). En el análisis multivariante realizado para identificar factores predictores de SEFAS satisfactorio, fueron significativos las variables finales de EVA-dolor y posición correcta de los sesamoideos. Los 66 pacientes con posición sesamoidea normal obtenida en la cirugía no tuvieron cambios en dicha posición al final del seguimiento. Por el contrario, 8 pacientes (25,8%) de los 31 en que la posición no fue correcta tuvieron un empeoramiento de la posición sesamoidea al final del seguimiento, y peor resultado final en SEFAS (p= 0,003), EVA-dolor (p= 0,026) y satisfacción (p= 0,011). Conclusión: La magnitud del desplazamiento de la cabeza metatarsiana no influye en el resultado funcional reportado por el paciente medido con la escala SEFAS, pero tiene influencia en la satisfacción del paciente con la cirugía. Una incorrecta posición sesamoidea obtenida en la cirugía puede conducir a un empeoramiento de dicha posición con el tiempo y peor resultado funcional. El principal factor de resultado favorable no es tanto la magnitud del desplazamiento lateral de la cabeza metatarsiana como la obtención en la cirugía de una correcta cobertura de los sesamoideos.
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Study of jet exhaust noise sources and their mitigation through lobed mixers and chevronsGrage, Danielle L. 04 August 2011 (has links)
No description available.
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Investigação de novas rotas de tratamento térmico em aço para rolamento. / Investigation of new treatment routes for bearing steel.Ramos, Diego da Rocha 25 August 2010 (has links)
Ao longo deste trabalho foi proposta uma nova rota de tratamento térmico para o aço AISI 52100, principal material utilizado na fabricação de rolamentos. Esta nova rota visa refinar a microestrutura de carbonetos presentes no material, com o objetivo de otimizar as propriedades mecânicas. Os tratamentos térmicos realizados conduziram a uma diminuição no tamanho dos carbonetos quando comparados com a amostra tradicional. Para medir a tenacidade à fratura evitando a dificuldade experimental de se nuclear pré-trincas em materiais frágeis, foi utilizada a metodologia Chevron, como formalizada na ASTM E-1304(97). Algumas das amostras submetidas a nova rota apresentaram maior tenacidade à fratura quando comparadas a amostra tratada na rota convencional. O material tratado na nova rota de tratamento térmico foi avaliado também em ensaio de impacto, usando-se corpos de prova Charpy de secção reduzida, sem entalhe. Os resultados obtidos mostraram que o material com carbonetos mais finos apresentavam menor energia absorvida no impacto quando comparados com a amostra tratada na rota convencional. Este comportamento a princípio contraditório foi explicado pela maior presença de sítios de nucleação na amostra com carbonetos mais finos. A maior densidade de sítios nas condições do ensaio de impacto conduziu a uma intensificação da nucleação de trincas, levando a uma menor energia absorvida durante o ensaio de impacto; este efeito ocorre mesmo quando o mecanismo de nucleação de trincas envolve a nucleação e coalescimento de microcavidades. Procurou-se fazer uma correlação entre a morfologia das superfícies de fratura obtidas no ensaio Chevron, o tamanho do carboneto das amostras e o micromecanismo atuante. Para amostras com superfície de fratura com aspecto fibroso foi associado o micromecanismo de fratura controlado por deformação. Para amostras com superfície de fratura com aspecto intergranular foi associado o micromecanismo de fratura controlado por tensão. / This work proposes a new heat treatment route for AISI 52100 steel, the most used material for bearings. The new route is designed so as to refine the carbides distribution in material, with the aim of increasing the fracture toughness. In order to measure the fracture toughness a Chevron notch methodology was used, as described in ASTM E-1304(97). Obtaining a static pre-crack on brittle materials is difficult and expensive; the Chevron notch methodology allows avoiding this difficulty. The heat treatments reduced the carbide sizes as compared with conventionally heat-treated steels. Some samples treated by this new route presented an increase in Chevron notch fracture toughness. The materials treated by the new heat treatment route were also tested in impact using a subsize Charpy specimen, without notch. Materials with fine carbides presented less dissipated energy in impact test then the material conventionally treated. This behavior is associated with the increase in number of carbide particles, as second phase particles are known to behave as sites for microvoid initiation and growth. The higher density of such sites presented in the material with fine carbides enhance this mechanism, lowering the dissipated energy measured in impact test. A correlation between fracture morphology, carbide size and fracture mechanisms was attempted. Samples with fine carbides presents fibrous transgranular fracture morphologies with strain controlled fracture micromechanism while samples with coarse carbides presented intergranular type morphologies with stress controlled micro-mechanism.
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Investigação de novas rotas de tratamento térmico em aço para rolamento. / Investigation of new treatment routes for bearing steel.Diego da Rocha Ramos 25 August 2010 (has links)
Ao longo deste trabalho foi proposta uma nova rota de tratamento térmico para o aço AISI 52100, principal material utilizado na fabricação de rolamentos. Esta nova rota visa refinar a microestrutura de carbonetos presentes no material, com o objetivo de otimizar as propriedades mecânicas. Os tratamentos térmicos realizados conduziram a uma diminuição no tamanho dos carbonetos quando comparados com a amostra tradicional. Para medir a tenacidade à fratura evitando a dificuldade experimental de se nuclear pré-trincas em materiais frágeis, foi utilizada a metodologia Chevron, como formalizada na ASTM E-1304(97). Algumas das amostras submetidas a nova rota apresentaram maior tenacidade à fratura quando comparadas a amostra tratada na rota convencional. O material tratado na nova rota de tratamento térmico foi avaliado também em ensaio de impacto, usando-se corpos de prova Charpy de secção reduzida, sem entalhe. Os resultados obtidos mostraram que o material com carbonetos mais finos apresentavam menor energia absorvida no impacto quando comparados com a amostra tratada na rota convencional. Este comportamento a princípio contraditório foi explicado pela maior presença de sítios de nucleação na amostra com carbonetos mais finos. A maior densidade de sítios nas condições do ensaio de impacto conduziu a uma intensificação da nucleação de trincas, levando a uma menor energia absorvida durante o ensaio de impacto; este efeito ocorre mesmo quando o mecanismo de nucleação de trincas envolve a nucleação e coalescimento de microcavidades. Procurou-se fazer uma correlação entre a morfologia das superfícies de fratura obtidas no ensaio Chevron, o tamanho do carboneto das amostras e o micromecanismo atuante. Para amostras com superfície de fratura com aspecto fibroso foi associado o micromecanismo de fratura controlado por deformação. Para amostras com superfície de fratura com aspecto intergranular foi associado o micromecanismo de fratura controlado por tensão. / This work proposes a new heat treatment route for AISI 52100 steel, the most used material for bearings. The new route is designed so as to refine the carbides distribution in material, with the aim of increasing the fracture toughness. In order to measure the fracture toughness a Chevron notch methodology was used, as described in ASTM E-1304(97). Obtaining a static pre-crack on brittle materials is difficult and expensive; the Chevron notch methodology allows avoiding this difficulty. The heat treatments reduced the carbide sizes as compared with conventionally heat-treated steels. Some samples treated by this new route presented an increase in Chevron notch fracture toughness. The materials treated by the new heat treatment route were also tested in impact using a subsize Charpy specimen, without notch. Materials with fine carbides presented less dissipated energy in impact test then the material conventionally treated. This behavior is associated with the increase in number of carbide particles, as second phase particles are known to behave as sites for microvoid initiation and growth. The higher density of such sites presented in the material with fine carbides enhance this mechanism, lowering the dissipated energy measured in impact test. A correlation between fracture morphology, carbide size and fracture mechanisms was attempted. Samples with fine carbides presents fibrous transgranular fracture morphologies with strain controlled fracture micromechanism while samples with coarse carbides presented intergranular type morphologies with stress controlled micro-mechanism.
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A teoria do risco integral aplicada à responsabilidade civil ambiental no caso chevron. / A teoría del riesgo Integral aplicada a la responsabilidad ambiental en el caso Chevron.Oliveira, Rosana dos Santos 17 June 2016 (has links)
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Previous issue date: 2016-06-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Esta investigación tiene como objetivo examinar si, en el caso de la contaminación del mar por la cuestión del petróleo causado por Chevron Brasil y contrató a Transocean se aplicó de manera efectiva a la Teoría Integral de Riesgos, la asunción de la responsabilidad ambiental en el sistema jurídico brasileño, ya que en benefician a la sociedad y el medio ambiente, no fue la celebración de un Término de Ajuste de Conducta (TAC), que, a su vez, condicionada al compromiso de los contaminadores para reparar y compensar el daño a la extinción de los casos civiles con una resolución de mérito. Este hecho derivó el debate en cuanto a la aplicación deliberada de la Teoría Integral de Riesgos, en los gustos de responsabilidad en caso de Chevron, o si lo había, de hecho, la relativización con respecto al uso de la teoría. / Esta pesquisa visa a analisar se, no caso de poluição do mar pela emissão de óleo causada pela Chevron Brasil e a contratada Transocean foi, efetivamente, aplicada a Teoria do Risco Integral, pressuposto da Responsabilidade Civil Ambiental no ordenamento jurídico brasileiro, vez que, em benefício da sociedade e do meio ambiente, houve a celebração de um Termo de Ajustamento de Conduta (TAC), que, por sua vez, condicionou o comprometimento das empresas poluidoras em reparar e compensar o dano à extinção dos processos cíveis com resolução do mérito. Desse fato, derivou o debate quanto à deliberada aplicação da Teoria do Risco Integral, na seara da responsabilidade civil, no Caso Chevron, ou se houve, na verdade, a relativização quanto ao emprego da Teoria.
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Contrôle sismique d'un bâtiment en acier de 3 étages à l'échelle 1/3 par amortisseurs élastomères et contreventements en chevronGauron, Olivier January 2010 (has links)
This study develops an innovative configuration of seismic natural rubber dampers for multistory low- and medium-rise steel braced frames. The dampers are directly integrated in an horizontal position in the seismic force resisting system of the structure. They are connected in a series with typical chevron brace systems.This control system provides not only additional structural damping to the structure but also a period shift, acting in the same way as a base isolation system. First, the fiber reinforced natural rubber used in the application was tested. It exhibited strong non linear dependance of its equivalent viscoelastic properties related to the shear strain. Then, a 1/3-scale 3-story chevron braced steel frame with and without dampers was considered. The structure was build and placed on the shaking table of the University of Sherbrooke Structures Laboratory. Numerical studies show that the efficiency of the control system reduces strongly the seismic induced forces of the undamped structure without any amplification of displacement or drift. Obtained seismic response reduction levels represent significant safety and economical benefits for the proposed application. Finally, the control system viability is experimentally demonstrated by shaking table tests at different reduced seismic intensities. Non linear behavior of the structure due to non linear behavior of the damping material is highlighted, and the dependance of seismic control performances is shown to be related to seismic intensities. Results allow an extrapolation of the experimental control peformances tending to the numerical results at higher intensities.
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Protein Folding Studies on the Ribosomal Protein S6: the Role of Entropy in NucleationLindberg, Magnus January 2005 (has links)
One of the most challenging tasks remaining in the field of biochemistry is the one of understanding how the information within the amino acid sequence of proteins translates into a unique structure. Solving this problem would lead to endless possibilities for application in the medical and biotechnology industry. Many decades ago scientists realized that the process that facilitates the folding of a polypeptide chain could not be random and happen by chance; there needs to be direction in the folding free energy landscape. This landscape is defined by the thermodynamic factors entropy and enthalpy. The contribution made by enthalpy i.e. the contact energies from intra- and intermolecular interactions have been extensively investigated by various mutational studies. The influence of entropy on the other hand, is less well understood. My work focuses on the effect of altering the entropic components of forming the various parts of a known protein scaffold. This is done by genetic engineering in combination with biophysical characterisation and analysis. The results show effects on protein folding rates as well as on the pathway for nucleation and emphasis the ability of the folding landscape to readjust to entropic variations. Proteins are therefore not required to fold along a unique route to their final structure but can do so in several ways. The folding pathways we observe today have hence likely evolved as an adaptation to biological demands.
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