[pt] Aços de alta resistência contendo frações significativas de austenita retida têm alcançado grande interesse comercial principalmente quando associados ao fenômeno TRIP durante o processo de conformação final. Recentemente, um novo conceito de tratamento térmico, denominado Têmpera e Partição, vem sendo estudado como mais uma alternativa no desenvolvimento de aços multifásicos. Neste processo, o controle da fração volumétrica da austenita retida é possível uma vez que durante o tratamento de partição, a supersaturação de carbono na martensita temperada é utilizada para estabilizar a austenita não transformada, evitando assim transformações futuras que poderiam ocorrer em temperaturas mais baixas. A seqüência de processamento térmico envolve o tratamento de têmpera numa faixa de temperatura entre Ms e Mf, seguido de partição numa temperatura igual ou superior à temperatura de têmpera. A partição do carbono da martenista para a austenita é possível caso reações competitivas, como por exemplo, a precipitação de carbetos, sejam suprimidas pela adição de elementos de liga tais como Si e/ou Al. Uma condição básica para o modelo está relacionada à restrição de movimentação da interface martensita/austenita, uma vez que a difusão em temperaturas baixas está limitada aos átomos interticiais. Essa restrição leva a um novo conceito de equilíbrio denominado Equilíbrio Constrito de Carbono, que é caracterizado pela igualdade do potencial químico na interface austenita-martensita apenas para o carbono. Nesse trabalho foram desenvolvidos quatro aços, contendo diferentes percentuais de C e Ni e com a presença dos elementos Si, Mn, Mo e Cr. A adição desses elementos teve finalidade reduzir a temperatura Bs, visando desacoplar o tratamento de têmpera e partição de uma eventual transformação bainítica. Um conjunto de condições para o tratamento de têmpera e partição foi então desenhado, envolvendo diferentes temperaturas de têmpera e diferentes temperaturas e tempos de partição. A avaliação microestrutural foi realizada utilizando recursos de microscopia ótica e microscopia eletrônica de varredura e de transmissão. A técnica de difração de raios-X foi empregada para quantificar a fração de austenita retida e seu enriquecimento em carbono. Foi modelado o processo de partição do carbono utilizando o programa DICTRATM. Os resultados dessas simulações foram analisados em termos dos parâmetros microestruturais, do tempo e da temperatura, e como essa combinação influência a cinética de partição do carbono. Os resultados obtidos para as amostras ensaiadas em tração indicaram uma vasta combinação de resistência e ductilidade, confirmando o potencial do processo na otimização das propriedades mecânicas. / [en] High strength steels containing significant fractions of retained austenite have been developed in recent years and are the subject of growing commercial interest when associated with the TRIP phenomenon during deformation. A new process concept, Quenching and Partitioning, has been recently proposed for production of steel microstructures containing carbon-enriched austenite. The heat treatment sequence involves quenching to a temperature between the martensite-start (Ms) and martensite-finish (Mf) temperatures, followed by a partitioning treatment, above or at the initial quench temperature, designed to enrich the remaining untransformed austenite with the carbon escaping from the supersaturated martensite phase, thereby stabilizing the retained austenite phase during the subsequent quench to room temperature. To enable the austenite enrichment, competing reactions, principally carbide precipitation, must be suppressed by appropriate alloying elements, such as Si and/or Al. The concept assumes a stationary martensite/austenite interface and the absence of shortrange movements of iron and substitutionals elements. The condition under which partitioning occur has been called Constrained Carbon Equilibrium (ECC), due to the restriction in movement of the interface and the assumption that only carbon equilibrates its chemical potencial at the interface. In this work, a group of four alloys was investigated, containing different additions of C and Ni and containing Si, Mn, Mo e Cr. These alloys were designed to preclude bainite formation at the partitioning temperatures of interest. Several heat-treatments, were performed in these alloys, using the Q&P concept, to evaluate its effect on the resulting microstructure and mechanical properties. Each alloy was quenched at selected temperatures and partitioned from 350 to 450°C for times ranging from 10 to 1000s. Microstructural characterization was performed by optical microcoscopy, scanning and transmission electron microscopy, while X-ray diffraction was used to determine both the fraction and the carbon content of the retained austenite. Partitioning kinetics were simulated with DICTRATM. The results were analyzed taking into consideration the scale of the microstructure, as well as the partitioning temperature. Tensile test results indicated that very high levels of strength with moderate toughness can be achieved confirming the potential of the Q&P to produce a superior combination of mechanical properties.

M.Tech. (Industrial Design) / This study investigated the user’s perspective with reference to the regular use of the WonderbagTM retained-heat cooker in low-income communities in a South African context. This research addresses the limitations of the literature available to support the investigation of the design of a fabric retained-heat cooker from a user’s perspective. As with the WonderbagTM retained-heat cooker, products aimed at underserved low-income communities are often designed without the participation of the end-user. This research focuses on the user’s experience of the fabric retained-heat cooker and seeks to include the user in the process of improving the design of these products. Participatory action research and user-centred design were utilised as the chosen methodologies for this study. The history of retained-heat cookers has been reflected upon when considering the use of insulation materials and alternative fabric improvements. Methods of manufacture, material cost and usage have been considered as critical elements of the design process as well as the skill level of the existing users. Participants indicated their personal interest in the design and development of the prototype retained-heat cooker. They were intensively involved in the design process from the focus group discussion where their perceptions were elicited, right through to their testing of the final prototype. A final workshop concluded the last of three workshops where participants provided individual feedback in terms of their personal experiences of using the prototype retained-heat cooker. Participants were able to selectively customise their prototypes, which brought about a sense of ownership and pride that was not evident in their use of previous retained-heat cookers. Participants indicated personal interest in creating their own retained-heat cookers from the experience that they acquired during the research process. As a result of this experience, the participants believed that they could manufacture their own retained-heat cookers to sell within their community, which could provide income for themselves and other members of their community. The saving of energy in terms of the fuel required to complete the cooking process translated into a direct saving of money, which was highlighted as a recurring theme and identified benefit of retained-heat cooking. By encouraging the use of energy-efficient retained-heat cookers, low-income communities could directly benefit from spending less on fuel costs and more on other essentials.

We contribute to the empirical literature on the debt bias of corporate income taxation through a firm-level evaluation of the European Commission's recent proposal of an Allowance for Growth and Investment (AGI). We use the introduction, the application and the repeal of a similar allowance in Austria during the early 2000s to evaluate the effects of the AGI on corporate equity and profit distribution. Our analysis provides evidence that such an allowance could increase corporate equity ratios by 5.5 percentage points and reduce profit distributions by 7.6 percentage points. These effects are stronger than those the previous literature for traditional Allowance for Corporate Equity (ACE) tax systems has identified. Additionally, we contribute to the recently expanding literature on the influence of ownership on tax planning as we find significant differences in the utilization of the AGI depending on individual specifics of the majority shareholder as well as depending on the number of shareholders of the respective firms. / Series: WU International Taxation Research Paper Series

Os objetivos foram avaliar os efeitos da aplicação de vitamina E pré-parto sobre a incidência de retenção de placenta e desempenho reprodutivo de vacas leiteiras. Entre maio de 2012 e abril de 2013, 890 animais, sendo 390 Holandesas (132 nulíparas e 258 vacas) e 500 mestiças Holandês x Gir (199 nulíparas e 301 vacas) foram envolvidas no estudo em três fazendas. Vacas e novilhas pré-parto foram alojadas em áreas de pastagem com piquetes rotacionados entre outubro e março e receberam 2 kg/d de concentrado, contendo fubá de milho, farelo de soja, minerais e vitaminas. De abril a setembro, as fêmeas pré-parto receberam dieta total composta de silagem de milho, fubá de milho, farelo de soja, minerais e vitaminas. Durante o período pré-parto, as fêmeas receberam 280 (Fazenda 1), 390 (Fazenda 2) e 480 (Fazenda 3) UI de vitamina E por dia via dieta. Em cada fazenda, os animais foram aleatorizados a não receberam tratamento algum (Controle), ou receberem aplicações semanais de 1.000 UI de vitamina E via intramuscular, aos 258 ± 3, 265 ± 3 e 272 ± 3 d de gestação (VitE). Amostras de sangue foram colhidas de um subgrupo de 141 fêmeas imediatamente antes de serem aleatorizadas para determinar a concentração sérica de ?-tocoferol. Amostras de sangue também foram analisadas para determinar as concentrações de cortisol e ácidos graxos não esterificados (AGNEs). As análises estatísticas foram feitas através dos procedimentos GLIMMIX, MIXED, PHREG E LIFETEST do SAS. Variáveis binárias foram analisadas por regressão logística, variáveis contínuas foram analisadas por ANOVA e variáveis relacionadas a tempo a um evento foram avaliadas através de curva de sobrevivência. O ?-tocoferol sérico não diferiu entre grupos Controle e VitE, com concentração média de 2,97 ± 0,10 ?g/mL. 53,2% das fêmeas apresentaram concentração inadequada de ?-tocoferol sérico baseado em 3 ?g/mL como ponto de corte. A probabilidade das vacas terem retenção de placenta diminuiu à medida em que a concentração sérica de ?-tocoferol aumentou (P = 0,01). A produção de leite foi igual nos grupos Controle e VitE. Aplicação de vitamina E pré-parto reduziu a incidência de natimortos, retenção de placenta e mortalidade até os 200 DEL. O grupo VitE apresentou tendência (P = 0,08) de aumento na taxa de concepção à primeira IA (36,7 vs 30,1%) pela menor perda embrionária/fetal entre 30 e 60 d de gestação (12,5 vs 20,5%). Apesar de similar taxa de inseminação entre os grupos, suplementação com vitamina E pré-parto acarretou em 22% de aumento na taxa de prenhez em relação ao grupo Controle. As fêmeas no grupo VitE tiveram menores concentrações de cortisol e AGNEs ao redor do parto. Em resumo, quando as vacas e novilhas foram alimentadas com quantidades limitadas de vitamina E, 28 a 48% das recomendações do NRC para vacas no pré-parto, a suplementação com vitamina E injetável melhorou a saúde e o desempenho reprodutivo das mesmas. / Objectives were to evaluate the effects of injectable vitamin E supplementation during the last 3 weeks prepartum on the incidence of retained fetal membranes (RFM) and reproductive performance of dairy cows. Eight-hundred and ninety dairy cows and heifers, being 390 Holsteins (132 nuliparous and 258 parous) and 500 crossbred Holstein x Gyr (199 nuliparous and 301 parous) from three dairy farms were assigned to the study from May 2012 to April 2013. In all three farms, prepartum females were housed in pastures, and from October to March, cows had access to pasture and were managed under grazing and received 2 kg/d of a mixture of finely ground corn, soybean meal, and minerals and vitamins. From April to September, prepartum animals received a TMR composed of corn silage, finely ground corn, soybean meal, and minerals and vitamins. During the prepartum period, animals received 280 (Farm 1), 390 (Farm 2), and 480 (Farm 3) IU of vitamin E/d. Within each farm, cows and heifers were randomly assigned to remain as untreated controls or to receive three i.m. injections of 1,000 IU each of DL-?-tocopherol administered at 258 ± 3, 265 ± 3, and 272 ± 3 d of gestation (VitE). Blood was sampled from a subset of 141 animals immediately before enrollment to determine the _-tocopherol status. Blood was also analyzed for concentrations of cortisol and nonesterified fatty acids (NEFA). Statistical analysis was performed with SAS software using the GLIMMIX, MIXED, PHREG and LIFETEST procedures. The concentration of ?-tocopherol in serum of females did not differ between treatments and averaged 2.97 ± 0.10 ?g/mL. A total of 53.2% of the animals had inadequate concentration of serum ?-tocopherol based on the 3.0 ?g/mL cut-off for adequacy. The probability of cows to have RFM decreased as the concentration of ?-tocopherol in serum increased (P = 0,01). Milk production did not differ between Control and VitE cows. Treatment with injectable ?-tocopherol improved postpartum health by reducing the incidence of stillbirths, RFM, and death by 200 d postpartum. Cows receiving VitE tended (P = 0,08) to have improved pregnancy per insemination (P/AI) at first AI (36.7 vs. 30.1%) because of less pregnancy loss between 30 and 60 d of gestation (12.5 vs. 20.5%). Despite similar insemination rate, cows receiving VitE had 22% greater pregnancy rate than control cows, which was attributed to the improved P/AI and reduced pregnancy loss in all inseminations during the first 200 d in milk. Females in VitE had reduced concentrations of cortisol and NEFA around calving. In summary, when cows and heifers were fed limited amounts of supplemental vitamin E, 28 to 48% of the recommendations for prepartum dry cows, supplementation with injectable ?-tocopherol improved postpartum health and reproduction.

The diploma thesis deals with phase composition measurement of the TRIP steel, using EBSD method. The steel was delivered as thermo-mechanically treated via two different routes. The phase composition of the steel was examined during gradual plastic deformation in the range 0 to10.99%. One route of thermo-mechanical treatment exhibited good agreement with the literature in terms of measured fraction of the retained austenite (15.6%) as well as its decrease during the deformation (to 8.9% at the maximum imposed strain). The samples of the second route did not show any agreement in either of the parameters spoken.

PURPOSE: Hemothorax, the collection of blood in the intrapleural space, commonly arises in patients suffering from thoracic trauma. Fluid collections in this space can compromise cardiac and respiratory function and if left untreated, can result in hypovolemic crisis. Fluid is often successfully drained via a tube thoracostomy, in which an intercostal drain is inserted into the pleural space. If residual blood remains, however, clotting may occur and result in a retained hemothorax (RH). Intrapleural administration of tissue plasminogen activator (tPA), a fibrinolytic drug typically utilized in ischemic stroke, has been shown to be both a safe and effective technique to hydrolyze RH clots and reduce the need for more invasive surgical interventions. The present study aims to evaluate the safety and efficacy of tPA administration at Boston Medical Center (BMC) and compare this data to those of prior studies. This study will also investigate if tPA as a definitive treatment for RH, could reduce the need for additional interventions such as surgical procedures including Video-Assisted Thoracoscopic Surgery (VATS) and/or invasive thoracaotomy. Hospital/intensive care unit (ICU) lengths of stay (LOS), ventilator time, and complication rates will be used to determine if tPA may allow for a significant decrease in patient cost and burden of care versus surgery. An analysis of patient demographics and injury data will be used to determine the individual factors that could be used to predict the success of tPA as a definitive treatment. Using evidence-based treatment protocols, the aforementioned data will be critically evaluated to determine the appropriate timing and sequential positioning of tPA administration in the treatment algorithm for retained hemothorax. METHODS: A single-institution retrospective chart review was conducted of patients treated for traumatic pneumohemothorax by the Department of Acute Care and Trauma Surgery at Boston Medical Center. A study on predictive factors of the development of retained hemothorax included all such patients that presented to the emergency department (ED) between May 2014 and June 2016. Demographic and injury characteristics were analyzed to determine if patients from specific groups or with specific injuries are more prone to develop RH. To evaluate the safety of intrapleural tissue plasminogen activator, the incidence of complications such as post-trauma infection and mortality were determined in patients that were administered tPA to resolve retained hemothorax between May 2014 through December 2016. Next, utilizing an expanded data set, the efficacy of tPA was evaluated by determining the percentage of cases in which tPA was able to definitively resolve RH. Secondary efficacy data including average hospital length of stay, average ICU length of stay, average mechanical ventilation time, and rate of readmission were compared between various interventions as well. Finally, to elucidate the risk factors for RH and independent predictors of tPA as a definitive treatment, demographic data including age, ethnicity, and gender as well as injury data including mechanism of injury, the presence or absence of multisystem trauma, and the presence or absence of specific injuries such as rib fracture, pulmonary contusion, or diaphragmic insult were collected. RESULTS: A statistically significant positive correlation was observed between the likelihood of developing RH and both abdominal alimentary tract and extremity injuries, indicating that these injuries may serve as predictive factors for RH development. In a study investigating the safety of intrapleural tPA, there was no statistically significant difference in post-trauma infection rates between individuals treated with tPA and those who were not. Additionally, tPA treatment was associated with a lower mortality rate. Efficacy studies revealed that tPA therapy was associated with a statistically significant decrease in mechanical ventilation time, as compared to surgical intervention, however, tPA carried a RH resolution rate of just 43% with one patient experiencing a major adverse systemic reaction to the drug. Finally, demographic and injury data were analyzed to determine predictive factors of tPA success, but no statistically significant relationships were observed between any of these characteristics and the outcome of tPA therapy. CONCLUSION: Intrapleural tPA is a safe and effective alternative to more invasive surgical procedures. The success rate of tPA therapy in the present study was less than previous studies have indicated, however, the potential decreased ventilation time is important for preventing ventilator associated pneumonia (VAP) and the high rate of mortality it carries. Although the success rate is lower than expected, tPA should still be considered in the RH treatment protocol, prior to surgery, to decrease required ventilation time and potentially prevent the need for more invasive interventions with higher costs, morbidity, mortality rates, and patient burden.

This study examines the specific ways in which private equity firms influence their portfolio companies to enhance their value, with a focus on the relationship between the level of retained ownership and post-IPO performance. Private Equity firms influence their portfolio companies in specific ways to enhance their value. Private Equity firms are typically limited partnerships, and to realize the value created during the life of the investment, the exit strategy is crucial. An initial public offering is stated as the preferable exit. However, private equity firms usually stay invested in their portfolio companies for up to several years after an initial public offering. Their retained ownership is crucial for underpricing at the IPO and performance post-IPO. This study aims to discover this relationship and to determine its effects. It will contribute to understanding how the portfolio companies' price changes on the first day of trading and their performance, in the long run, is affected by the stake held by the private equity firms. This research will try to clarify the current uncertainty about the effect of underpricing that prevails. It will also fill the existing gap in the academic literature about performance. It can also be potentially helpful for investors. Given knowledge about how retained ownership by PE firms affects underpricing at the IPO and performance post-IPO, this study can help investors to make better investment decisions. However, it should not be seen as investment advice but rather as a contribution to increasing the investor's understanding and knowledge. Publicly listed portfolio companies in the Nordic region constitute the sample for the analysis, and pooled OLS is the econometric method used in this study. We utilized a panel dataset for performance and obtained 2411 unique observations. The long-run performance has been measured as 36 months following the IPO. Our findings indicate a positive relationship between the level of ownership held by the PE firm and both underpricing and performance. These relationships are both statistically significant on the 1% level. Control variables were also included to capture other possible factors that might impact our dependent variables. The positive relationship between the level of ownership held by the PE firm and performance was in line with previous similar research and our expectations. However, the relationship between the PE firm's level of ownership and underpricing was the opposite of what we expected. Previous research has also presented contradictory results, making it difficult to predict the relationship. We hope our results have contributed to clarity regarding underpricing and broadening existing literature about performance for private equity-backed companies.

<p>Rolling contact fatigue (RCF) is a common cause of failure in tribological machine components such as rolling-element bearings (REBs). Steels selected for RCF applications are subject to various material processes in order to produce martensitic microstructures. An effect of such material processing is the retention of the austenitic phase within the steel microstructure. Retained austenite (RA) transformation in martensitic steels subjected to RCF is a well-established phenomenon. In this investigation, a novel approach is developed to predict martensitic transformations of RA in steels subjected to RCF. A criteria for phase transformations is developed by comparing the required thermodynamic driving force for transformations to the energy dissipation in the microstructure. The method combines principles from phase transformations in solids with a damage mechanics framework to calculate energy availability for transformations. The modeling is then extended to incorporate material alterations as a result of RA transforming within the material. A continuum damage mechanics (CDM) FEM simulation is used to capture material deterioration, phase transformations, and the formation of internal stresses as a result of RCF. Crystal lattice orientation is included to modify energy requirements for RA transformation. Damage laws are modified to consider residual stresses and different components of the stress state as the drivers of energy dissipation. The resulting model is capable of capturing microstructural evolution during RCF.</p> <p>The development and stability of internal stresses caused by RA transformation in bearing steel material was experimentally investigated. Specimens of 8620 case carburized steel were subjected to torsional fatigue at specific stress levels for a prescribed number of cycles. X-ray diffraction techniques were used to measure residual stress and RA volume fraction as a function of depth in the material. A model is set forth to predict compressive residual stress in the material as a function of RA transformation and material relaxation. Modeling results are corroborated with experimental data. In addition, varying levels of retained austenite (RA) were achieved through varying undercooling severity in uniformly treated case carburized 8620 steel. Specimens were characterized via XRD and EBSD techniques to determine RA volume fraction and material characteristics prior to rolling contact fatigue (RCF). Higher RA volume fractions did not lead to improvement in RCF lives. XRD measurements after RCF testing indicated that little RA decomposition had occurred during RCF. The previously established RCF simulations were modified to investigate the effects of RA stability on RCF. The results obtained from the CDM FEM captured similar behavior observed in the experimental results. Utilizing the developed model, a parametric study was undertaken to examine the effects of RA quantity, RA stability, and applied pressure on RCF performance. The study demonstrates that the energy requirements to transform the RA phase is critical to RCF performance.</p>

TBF 1180 steel was studied under various conditions focusing on the correlation of ductility and amount of retained austenite. Samples were prepared from sheet stock and then strained using limiting dome height tooling (LDH), a standard uniaxial test frame, and a tensile stage for use in an electron microscope. The steel was observed in plane, biaxial, and uniaxial strain to determine its effect on retained austenite transformation and ultimately, ductility. Retained austenite was observed using a scanning electron microscope (SEM) equipped with an electron backscatter detector (EBSD) to distinguish the different phases present. Initial austenite levels were around 5% by volume and was quickly reduced as the sample was strained. The biaxial samples were the slowest to transform, having about 2.5% austenite at .05 effective strain, which allowed the specimen to reach an effective strain of .3 with 1.1% austenite remaining. In contrast, the plane strain samples had the fastest rate of transformation having only 1.2% austenite at .05 effective strain and .7% austenite at a final effective strain of .18. Both forms of uniaxial, (in-situ and ex-situ), were near identical, as expected, and exhibited an austenite transformation curve between that of the plane and biaxial curves. The uniaxial austenite level at .05 strain was 2.1% and was able to reach about .15 strain with a final austenite percentage around 1%. It was concluded that the biaxial strain path had the greatest ductility due in part to its slower austenite transformation rate while plane and uniaxial strain paths were not as ductile with their faster austenite transformation rates.

Gene duplications can facilitate genetic innovation, reduce pleiotropy and catalyze reproductive incompatibilities and speciation. Therefore, the molecular and transcriptional fate of duplicate genes plays an important role in the evolutionary trajectory of entire genomes and transcriptomes. Using the polyploid African clawed frog Xenopus, I have investigated mechanisms that promote the retained expression of duplicate genes (paralogs) after whole genome duplication. The studies herein estimated molecular evolution and characterized expression divergence of thousands of duplicate genes and a singleton ortholog from a diploid outgroup. In this thesis, I have discussed the multiple mechanisms for the retention of duplicate genes in a polyploid genome and examined the potential effects that gene characteristics before duplication have on the odds of duplicate gene persistence. I have also explored the use of microarrays for comparative transcriptomics between duplicate genes, and between diverged genomes. The main objectives of my thesis were to better understand the genetic mechanisms that promote the retained expression of gene duplicates. My research utilized the duplicated genome from the allopolyploid clawed frog Xenopus. Genome duplication in clawed frogs offers a compelling opportunity to study factors that influence the genetic fates of gene duplicates because many paralogs in these frogs are of the same age, permitting one to control for the influence of time when evaluating the impact of duplication. My work has major impacts on several biological fronts including evolutionary genomics and comparative transcriptomics, and also on technical aspects of using microarrays. I have provided among the most comprehensive studies of its kind, in terms of examining molecular and regulatory aspects of thousands of expressed duplicates of the same age, and exploring various alternative hypotheses to explain how these genes are retained. / Thesis / Doctor of Philosophy (PhD)