Aluminum alloy castings are becoming commonplace for critical applications in the automotive and aerospace industries where materials failure is not an option. In order to meet such property demands, tight control over the cleanliness of the melt (mitigation of solid particle inclusions) and microstructure must be achieved. In order to control cleanliness, it must first be well defined and measured. Very few techniques exist in industry that can quantitatively measure inclusion levels in-situ. Laser-induced breakdown spectroscopy (LIBS) is presented as a promising technique to quantify solid particles, desired or undesired, in aluminum melts. By performing LIBS with subsequent statistical analysis on liquid aluminum with varying concentrations of Al2O3, AlB2, TiB2, and SiC particles, calibration curves relating particle concentration and elemental intensity were drawn. Through metallography and automated electron microscopy, it was found that inclusions less than 10 um in size could be detected with LIBS. Concentrations down to at least one part-per-million could be detected and accurately measured, allowing for LIBS to be use as a tool for complete, real-time melt cognition.

A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Master of Science (Haematology) / The region Ilpl3-pl5 on the short arm of chromosome 11 (lip) has been implicated in the initiation or progression of several human malignancies including the embryonic rhabdomyosarcoma Wilms' tumour, bladder, renal cell and ovarian carcinoma. In this study, Fluorescence In Situ hybridisation (FISH) was used to identify the nature of a chromosome llp+ abnormality present in two ovarian carcinoma cell lines after conventional cytogenetic techniques had failed to elucidate the chromosomal origin of the abnormality. Using whole chromosome library probes, the abnormality in cell line UW0V2 was found to be composed entirely of chromosome 3 material representing the translocation t (3;11) (pl2-14;pl5). In the protein-free subline UW0V2(Sf), the abnormality was found to consist of the complex translocation t (3;8; 11) (pl2-14 ;q22-24;pl5) . It is possible that the involvement of chromosome 8 in this translocation was a cell culture phenomenon. Other structural and numerical abnormalities elucidated with FISH in cell line UW0V2(Sf) included lq+, +5, +7, 7q-, 8q+, +12, +14, 14q+, -15, 16q- and -18. Using FISH together with the gene probe pSB|5 and the CEPH YAC probes 892g9, 785e5, 847al2, 954f4, 966e8 and 845a3, the breakpoint region on chromosome 11 in the _ two cell lines was narrowed down and mapped to the region Ilpl4.3-pl5.1 lying between probes 966e8 (D11S902) and 845a3 (D11S899). This represents a physical distance of approximately 1 Mb. The breakpoint in the two cell lines appeared to involve the same region on llplS.l. In a separate study, three epithelial ovarian tumour specimens and four ascitic fluid specimens were obtained. Tumour specimens T2 and T4 and ascitic fluid specimens AF-1, AF-2 and AF-3 were all cytogenetically uninformative. Cytogenetic analysis of specimen T5 revealed a single clonal abnormality involving a deletion in the region 6q21. Ascitic fluid specimen AF-5 yielded cytogenetically normal metaphases. Both specimens were hypodiploid and revealed a cytogenetically normal chromosome 11. Using FISH and CEPH YAC probes 966e8 and 845a3, no abnormalities were detected in the region llpl4.3-pl5.1 in these two specimens but one cannot rule out the possibility of submicroscopic abnormalities lying within the region between these probes. From this study we speculate that chromosome 6 abnormalities may be important in the initiation of these tumours. From the results obtained with cell lines UW0V2 and UW0V2 (Sf) we speculate that the chromosome 3 abnormalities were an early event in the evolution of these tumours while the chromosome 11 abnormality was a later event. Little is known about the region llpl4.3-pl5.1 and very few disease loci have been assigned to this region, however, we may speculate that this region harbours a tumour suppressor gene or an oncogene whose disruption or activation is critical to the pathophysiology of ovarian carcinoma and other genitourinary cancers. / WHSLYP2017

Les systèmes in situ sont des liquides à base de polymère et de solvant organique pharmaceutiquement acceptable, contenant le principe actif. Après injection sous-cutanée, lors du contact avec les fluides corporels, le polymère précipite sous forme d'implant (ISI) ou de microparticules (ISM) qui se dégradent progressivement en libérant le principe actif. Dans ce travail, des ISI et des ISM réalisés à partir d'un copolymère d'acide lactique et glycolique ont été développés pour la libération prolongée de S-nitrosothiols (RSNO), des donneurs de monoxyde d'azote. L'influence du type de formulation, du solvant, de l'hydrophobie du principe actif et de l'environnement (in vitro ou in vivo) sur la solidification, la dégradation de la matrice polymérique et sur la libération du RSNO ont été étudiés. Les expériences in vivo ont prouvé la prolongation par la formulation de l'effet des RSNO sur la pression artérielle chez le rat (jusque 42 h). Néanmoins, le temps de dégradation des formulations est supérieur à 1 mois et doit donc être optimisé pour une application de longue durée. Le potentiel de ces formulations dans un modèle d'infarctus a été évalué. La faisabilité d'une injection directe dans le myocarde infarci a été démontrée. D'après les premiers résultats, ces implants chargés en RSNO permettraient d'améliorer la perfusion du coeur. Enfin, la porosité de ces systèmes augmente durant leur dégradation, ce qui rend la matrice susceptible de recruter et d'héberger des cellules. In vitro, des ISI ont permis l'adhésion et la prolifération de cellules musculaires. Ces formulations adaptées aux RSNO pourraient constituer un outil thérapeutique dans le cadre des maladies ischémiques / In situ forming injectable systems are liquids based of a polymer and a pharmaceutically acceptable organic solvent, to which drug is added. After subcutaneous injection, contact with aqueous body fluids triggers polymer precipitation as implant (ISI) or microparticles (ISM). This matrix degrades then slowly while releasing the drug. In this work, ISI and ISM made of a copolymer of lactic and glycolic acid were developed for sustained release of S-nitrosothiols (RSNO), prodrugs of nitric oxide. Influence of formulation type, solvent, drug hydrophobicity and environment (in vitro vs in vivo) on polymeric matrix solidification, degradation and on RSNO release was studied. In vivo experiments proved that formulation extend (until 42 h) RSNO effect on arterial pressure of rats. However, matrix life-span is higher than 1 month, thus need optimization in view of an application requiring a long lasting release. Evaluation of these formulations has begun in a model of cardiac infarction. First, the feasibility of a direct injection into the infarct area has been established. Second, first results seem to indicate that these implants loaded with RSNO could enhance heart perfusion. Finally, porosity of these systems increases during their degradation, allowing cell recruitment and colonization of resulting matrix. An in vitro study conducted on implants with porosity artificially increased showed adhesion and proliferation of muscular cells seeded onto the systems. As a result, in situ formulations are suitable drug delivery systems for S-nitrosothiols, and represent a potential therapeutic tool, in particular in the field of ischemic diseases

The morphology, composition, and distribution of elements within nanocrystals are critical parameters which dictate the material's properties and performance in a diverse array of emerging applications. The (scanning) transmission electron microscope ((S)TEM) represents a powerful tool for probing the structure and chemistry of materials on the nanoscale. Understanding of the mechanisms by which nanocrystals grow, transform, and degrade is vital if we are to develop rational synthesis routes and hence control the properties of the resulting materials. Electron microscopy represents a key tool in developing such an understanding. In situ techniques, where the material of interest is subjected to stimuli such as heat or a chemically reactive environment in the microscope, allow direct observation of dynamic transformations. Ex situ approaches, where multiple samples are prepared in the lab with the reaction parameters systematically altered, can also give important mechanistic insights. This thesis explores the use of both in situ and ex situ (S)TEM to gain insights into the growth and transformation of nanocrystals. Ex situ TEM is used to assess the structure of PbS nanocrystals in a polymer matrix, revealing new methods of morphological control through reaction temperature, precursor structures (appendix 4), and the processing of the polymer matrix (appendix 5). In situ techniques are used to observe the solution phase growth and shelling of nanocrystals (appendix 1) as well as the transformations of nanocrystals during heating in vacuum (appendices 2 and 3). The subjects of my in situ investigations are systems with heterogeneous distributions of elements. Historically, in situ electron microscope has been largely limited to imaging. However, to understand many dynamic transformations knowledge of changing elemental distributions is vital. For this reason, I have focused on the use of energy dispersive X-ray (EDX) spectroscopy to reveal changes in composition and elemental distributions during in situ experiments (appendices 1-3). This type of in situ elemental mapping is especially challenging for liquid-cell experiments, and my results represent the first report of EDX spectrum imaging for nanomaterials in liquid (appendix 1).

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A conservaÃÃo in situ promovida atravÃs da criaÃÃo de unidades de conservaÃÃo tem sido um dos meios mais utilizados para a consecuÃÃo de uma polÃtica de proteÃÃo da biodiversidade. A implementaÃÃo dessas unidades, entretanto, afigura-se como um desafio constante do Poder PÃblico, principalmente em relaÃÃo Ãs unidades de conservaÃÃo de proteÃÃo integral, pois muitos sÃo os problemas encontrados para alcanÃar uma total implementaÃÃo, que causa inclusive crÃticas severas de autores nacionais que consideram um equÃvoco a adoÃÃo, na AmÃrica Latina, do modelo norte-americano de criaÃÃo de Ãreas protegidas. Com o objetivo de avaliar uma unidade de conservaÃÃo de proteÃÃo integral denominada Parque EcolÃgico da Lagoa da Maraponga, localizada na cidade de Fortaleza-CearÃ, cuja origem ocorreu de forma diferenciada atravÃs da participaÃÃo decisiva da populaÃÃo e movimento ambientalista, concretizou-se o presente trabalho, utilizando levantamentos bibliogrÃficos e cartogrÃficos, aplicaÃÃo de questionÃrio ao gerente da unidade, visitas de campo e entrevista com os freqÃentadores do Parque. Para anÃlise dos dados lanÃou-se mÃo de dez critÃrios adaptados do mÃtodo aplicado pela World Widelife Fund - WWF-Brasil, concluindo-se que o Parque EcolÃgico da Lagoa da Maraponga encontra-se precariamente implementado e, por isso, sugere-se uma aÃÃo urgente do Poder PÃblico responsÃvel, inclusive, no sentido de promover a necessÃria criaÃÃo da unidade nos termos da Lei do Sistema Nacional de Unidades de ConservaÃÃo da Natureza - SNUC.

Tesis para optar al grado de Magíster en Minería / La minería enfrentará en el futuro nuevos y distintos desafíos, siendo una de las principales dificultades no el agotamiento de los recursos, sino la falta de tecnologías adecuadas y a tiempo que permitan la recuperación de metales desde depósitos de baja ley. El aumento de los costos capitales y operacionales experimentados por la industria, dificulta la extracción de cobre de manera económicamente eficiente. Esto ha llevado a la búsqueda constante de nuevas tecnologías que complementen o reemplacen los métodos de explotación convencional y que permitan recuperar metales a menores costos. Con este objetivo se busca desarrollar los fundamentos de un nuevo método: la Minería in situ (MIS), método que integra la minería convencional y la lixiviación in situ (LIS). Esperando mejorar de esta forma la recuperación metalúrgica observada en LIS mediante la incorporación de parámetros mineros y el control de variables metalúrgicas como: temperatura, aireación y la compresión/extracción de material en la Minería in situ. Para la evaluación de estas variables en la recuperación de cobre, un modelo de laboratorio y un protocolo experimental fueron desarrollados. Las pruebas realizadas a minerales sulfurados de cobre, indican que la eficiencia de lixiviación disminuye con la compresión del material (de 19.9% obtenido en el caso base a un promedio de 14.9%) y aumenta con el alza de la temperatura y más aún con la aireación (de 19.9% a un 29.8% y 33.8% respectivamente). En cuanto al efecto de la extracción de material, no se obtienen resultados concluyentes. A partir de los resultados experimentales obtenidos, se concluye que la compresión debiese ser considerada en el dimensionamiento de los caserones. Caserones de mayor altura, implicarían una mayor compresión del mineral contenido, reduciendo la permeabilidad y la eficiencia de la lixiviación. Por otro lado, los beneficios de la temperatura y de la aireación debiesen incorporarse mediante el proceso de calentamiento de la solución lixiviante y a través de la operación de ventilación. Con el fin de comparar en términos económicos MIS y la minería convencional, se consideró un caso de estudio de Sublevel Stoping (SLS). Los costos e inversiones de MIS fueron estimados a partir del caso de estudio y de benchmarking de procesos de lixiviación, mientras que las recuperaciones metalúrgicas empleadas fueron estimadas a partir de los resultados experimentales utilizando el modelo cinético del núcleo sin reaccionar. De acuerdo a la evaluación realizada, MIS efectivamente registra costo mina, planta e inversiones inferiores a la minería convencional. En el caso estudiado, con una recuperación metalúrgica de MIS de 30% el primer año y de un 60% máximo, MIS y SLS presentan un VAN cercano a los 61 MUS$. De mantener el límite de recuperación, pero aumentar la recuperación de MIS en el tiempo mediante la aplicación de aire, el VAN alcanza los 77.9 MUS$ (incremento de 27.9%). De acuerdo a lo anterior y al análisis de sensibilidad realizado, el VAN de MIS es más sensible a la recuperación metalúrgica que a los costos. Lo que hace posible maximizar el VAN mediante el incremento de la recuperación aun cuando las operaciones requeridas para esto, impliquen el alza de los costos operacionales y capitales. Sin embargo, esta relación entre costos, recuperación y VAN no es constante en el tiempo ni equivalente entre distintos depósitos ya que depende de la cinética de lixiviación. La relación entre estos parámetros será variable considerando que existe un límite máximo de recuperación. Este límite deberá ser definido con el objeto de establecer el límite de costos bajo el cual es posible maximizar el beneficio de MIS.

An elasto-visco-plastic deformation model predicts stresses and distortions in a low-carbon steel casting. Features of the model include rate and hardening effects, temperature-dependent properties, and pressure-dependent deformation in the mushy zone. A volume-averaging technique considers the multiple phases during solidification and is used to formulate the conservation equations, which (due to a weak link between temperatures and deformations) are decoupled and solved sequentially using commercial software. Temperature fields are calculated first using MAGMAsoft (MAGMAsoft, MAGMA GmbH, Kackerstrasse 11, 52072 Aachen, Germany) and then exported to a finite element software package, ABAQUS (Abaqus/Standard, Abaqus, Inc., Providence, RI, 2006), which predicts stresses and distortions. In order to simulate the conditions encountered in an industrial casting process, predicted temperatures and distortions are matched with experimental data from in situ casting trials. Preliminary simulations do not agree with the experimental distortions, which suggest that stress-strain data from mechanical tests (from which the mechanical properties were estimated) does not accurately characterize the material behavior of a casting during solidification and cooling. The adjustments needed to match measured and predicted distortions provide valuable insight to the effect a solidified microstructure has on its mechanical properties.

Abstract not available

Bibliography: leaves 170-196. / xix, 199 leaves, [84] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The results presented in this thesis establish the growth-suppressive activity of the human GAS1 gene and provide the first direct evidence that GAS1 can inhibit the growth of tumours. In addition, this study demonstrates that the antiproliferative effect of GAS1 are mediated by a p53 dependent pathway and that functional inactivation of p53 by either mutation and/or overexpression of the MDM2 oncogene product inhibits the GAS1 mediated growth-suppression. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physiology, 1997?

Errata inserted. Bibliography: leaves 98-120. This study is concerned with the identification of genes related to the very early stages of meiosis when homologous pairing occurs. A cDNA library is prepared at the premeiotic interphase and prophase stages of meioses. Differential screening is used to identify and select clones showing preferential expression in anthers at early meiosis. Two selected clones are chosen for further analysis and to investigate a possible role in chromosome pairing.