El Objetivo del estudio fue establecer las características radiológicas y anatomopatológicas del Carcinoma in situ de la mama en pacientes evaluadas con mamografía a quienes se les realizo localización con aguja con guía estereotaxica y luego biopsia quirúrgica durante el Periodo Enero 2001 a Diciembre del 2003. En este intervalo se realizaron 706 LCA en el Servicio de Radiología del HNGAI en mujeres con sospecha de cáncer de mama por mamografía que presentaron lesiones no palpables, de los cuales 10.6%(75) correspondieron a Cáncer y 32%(24) fueron CIS de mama, siendo la edad promedio de presensación 55.16 años, correspondiendo principalmente a categoría BIRADS 4. En 95.8% se encontraron microcalcificaciones, solas 70.8% y asociadas a otros hallazgos como Distorsión asimétrica focal con menor frecuencia. Las microcalcificaciones estuvieron agrupadas en menos de 20por cm2 principalmente. La Variedad histológica mas frecuente encontrada las de tipo Mixto no Comedocarcinomas. No se encontró diferencias en cuanto al grado nuclear de los carcinomas. El Índice Pronostico de Van Nuys fue alto en 33.3%. En conclusión la incidencia de Carcinoma in situ de la mama en pacientes sometidas a LPA fue semejante a lo encontrado en estudios internacionales, presentándose como microcalcificaciones solas principalmente, agrupadas en numero menor de 20 por cm2 y correspondieron con mayor frecuencia al a la variedad histológica Mixta, de tipo no comedor carcinoma.

This thesis is based on experiments applying synchrotron based X-ray Absorption Spectroscopy(XAS) and Resonant Inelastic X-ray Scattering (RIXS) in the soft X-ray region to energy related systems. The main work of this thesis has been to develop a reaction cell that allowed for in situ XAS and RIXS investigations of the partial epoxidation of ethylene over a Ag catalyst at 1 atm and up to 250C. The developed in situ cell can be used in two sample modes: 1) the Ag catalyst is deposited directly onto the vacuum separating membrane with the reaction gases flowing beneath it or 2) a slightly compressed Ag powder sample is at a distance to the vacuum membrane with the reaction gases flowing between the Ag powder sample and the membrane.Both sample modes offers the total florescence yield, TFY, and the total electron yield, TEY, to be recorded simultaneously. By means of the developed in situ cell a number of oxygen species, residing in/on the Ag surface or in the Ag bulk, have been detected. We claim to detect adsorbed O2 under epoxidation conditions, as well as Ag–O–H groups. We are also able to monitor changes of the absorbed oxygen as we change the composition of the reaction gas feed. The first charging cycle of Li-ion batteries have been investigate by ex situ measurements on the cathode Li2-xMnSiO4 and the anode composite LixNi0:5TiOPO4/C . The initial crystalline material becomes amorphous due to lithiation during the first first charging. We find that the redox behaviors of these two states are significantly different. Sulfidation of natural copper oxides are is found to be strongly promoted when it is grown on the host metal by a disproportionation.

The level of information provided by electrochemical measurements can be substantial as evident by the use of electrochemistry in varied disciplines spanning from materials research to cellular biochemistry. However, electrochemistry on its own does not provide direct information concerning redox induced changes in molecular structure. This information can only be elucidated by coupling spectroscopic and/or separation techniques with traditional electrochemical methodologies. In principle, infrared (IR) spectroelectrochemistry (SEC) is ideal for such studies but in practice coupling IR spectroscopy and electrochemistry are often experimentally incompatible. Since the inception of in-situ IR SEC techniques in the 1980’s, two competing methodologies (using either external- or internal- IR reflection geometries), were developed to deal with the two major challenges associated with IR SEC (strong infrared absorption of the electrolytes and weak analytical signals). The primary focus of this thesis is the successful advancement of IR SEC techniques through the implementation of synchrotron infrared radiation with ultramicroelectrodes (UMEs; electrode diameters < 25 µm) to study spectroelectrochemical processes on the microsecond time scale. Several examples using Surface Enhanced Infrared Absorption Spectroscopy (SEIRAS) are presented including the adsorption of dimethylaminopyridine (DMAP) on gold substrates and the proton-coupled electron-transfer (PCET) kinetics of electrochemically-active 1,4-benzoquinone terminated self-assembled monolayers (SAMs). These studies highlight the benefits of coupling electrochemistry and infrared spectroscopy. For instance, in-situ spectroscopic evidence shows that small amounts of DMAP’s conjugate acid (DMAPH+) adsorb on gold electrodes in acidic electrolytes and at negative potentials. This result was not forthcoming from previous electrochemical measurements and was only realized through in-situ SEIRAS. Finally, the largest contribution in advancing in-situ IR SEC methodologies was through the development of utilizing synchrotron infrared radiation on UMEs to study fast electrochemical processes. This work was technically very challenging and emphasized the interfacing of an electrochemical cell containing an UME with fast infrared data acquisition techniques (i.e. rapid scan and step-scan interferometry). The use of a prototypical electrochemical system, i.e. the mass-transport controlled reduction of ferricyanide, indicate that at short times the spectroscopic signal closely matches the electrochemical signal but at long time scales it deviates due to edge effects associated with the diffusion environment of the UME.

Abstract Densification and mechanical properties (hardness, fracture toughness and flexural strength) of the SiC-TiB2 composite were studied. Pressureless sintering experiments were carried out on samples containing 0 to 50 vol % of TiB2 created by an in-situ reaction between TiO2 and C: 2TiO2 + B4C + 3C 2TiB2 + 4CO Al2O3 and Y2O3 were used as sintering additives to create a liquid phase and promote densification at sintering temperatures ranging from 1820 to 1940oC. The sintered samples were subsequently heat-treated at temperatures ranging from 1850 to 1970oC It was found that the presence of TiB2 formed by the above reaction serves as an effective obstacle to crack propagation thus increasing both the strength and fracture toughness of SiC while maintaining high a hardness of the sintered samples. Densities higher than 98 % TD were achieved depending on both the sintering temperature and heat treatment conditions. From a density viewpoint, the optimum volume fraction of TiB2 was from 12 to 24 vol %. Typical microstructures for samples with this volume fraction of TiB2 consist of TiB2 particles (< 5m) uniformly dispersed in a matrix of elongated SiC plates. The presence of TiB2 particles in the matrix of SiC inhibited exaggerated grain growth of the SiC grains and activated additional toughening mechanisms. The subsequent heat treatment of the sintered samples improved mechanical properties. The optimum sintering and heat treatment temperatures were 1940 and 1970oC, respectively. The maximum flexural strength of 593 MPa was obtained in sample with 12 vol % TiB2. A maximum fracture toughness of 6.6 MPa•m1/2 was measured in samples containing 24 vol % TiB2. While both fracture toughness and strength increased with the presence of TiB2 particles, hardness on the other hand decreased from ~18 GPa in samples without TiB2 to 16.4 and 15.9 GPa in samples with 12 and 24 vol % TiB2, respectively. A theoretical analysis was conducted to model the effect of microstructure on the fracture toughness of SiC-TiB2 composites and was experimentally verified. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2009-09-30 23:04:32.565

Succinic Acid (SA) is an intermediate in the production of fine and commodity chemicals. No commercial SA bioproduction process exists due to process limitations including end product inhibition and high product separation costs, which account for 70% of total production costs. Two-Phase Partitioning Bioreactors (TPPBs) can increase volumetric productivity through in-situ product removal, although SA uptake by polymers requires a pH below the pKA2 of SA (4.2). Sparging CO2 gas into the bioreactor was proposed to temporarily lower the pH of the medium, allowing for SA uptake. At 1atm CO2 sparging lowered the pH of Reverse Osmosis (RO) water to 3.8 but only to 4.75 in medium, requiring the use of H2SO4 and KOH for pH adjustment in subsequent experiments. Polymers were screened for SA uptake and the effect of pH on uptake from 2.2 to 6.2 was also studied. Only Hytrel® 8206 showed non-zero uptake with a partition coefficient for SA of 1.3. Cell cultures of Actinobacillus succinogenes was exposed to pH 4.2 for times from 5 minutes to 4 hours to determine whether cells could grow after low pH exposure. A. succinogenes resumed growth after up to 4 hours of low pH exposure, giving a sufficient time span for SA uptake in the bioreactor. A single-phase run was operated as a benchmark for comparison to the TPPB system which removed SA from the fermentation broth by pH cycling; lowering the pH to 3.8 for uptake, then increasing it to 6.7 to continue bioproduction. Uptake from fermentation broth took 60 minutes, within the time causing no effect on cell growth from low pH exposure. The two-phase run yielded 1.39g/L•h, unchanged compared to the single-phase run which gave 39g/L of SA after 28 hours. Though pH cycling reduced the concentration of SA through polymer uptake, the salts added for pH adjustment hindered further cell growth. The TPPB system demonstrated that SA can be efficiently removed from solution without complex separation methods. Future work will use pressurized vessels to increase the solubility of CO2 and lower the pH of fermentation broth for SA uptake without the need for strong acids. / Thesis (Master, Chemical Engineering) -- Queen's University, 2011-04-18 08:07:51.379

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Oxygenic photosynthesis is responsible for virtually all of the biochemical production of organic matter in both marine and terrestrial ecosystems. Despite the large amount of research on phytoplankton, macroalgae have received less attention despite them being, on a per-area basis, one of the most productive ecosystems on earth. Furthermore, there has been a tendency of studies to measure primary production in single thalli, or monospecific stands. The lack of studies examining in situ production of whole assemblages using photorespirometry, as is common practice in soft-sediment systems, may be related to a lack of suitable apparatus. This research aimed to develop unique techniques and an apparatus for measuring primary production of intact macroalgal assemblages in laboratory and field conditions. Photorespirometry chambers were developed and tested on in situ macroalgal assemblages, giving information on the role of species identity, biodiversity, irradiance and community structure on overall primary production. Furthermore, the successful application of these methods was used to model annual primary production over local and regional scales, as well as the potential effects of human disturbance on production. In this study, photosynthesis-irradiance relationships (P-E curves) of intact intertidal algal assemblages showed no signs of saturation at high irradiance levels, as is typically seen in single species curves. Furthermore, diverse macroalgal assemblages showed a two-stage rise in production, with a significant enhancement of production at high irradiance. Evidence from this study suggests that the three-dimensional structure of natural assemblages, functional diversity and their interaction with a complex light environment is responsible for the unique P-E curves. The increased efficiency of light use in complex assemblages suggests an important role of species complmentarity in enhancing production with species diversity. This research also shows the potential consequences of disturbance on macroalgal assemblages, with the loss of several species causing a major decline in net production. The methods developed in this thesis have allowed simple modelling of annual rates of primary production and the parameters driving production of macroalgae over long time-scales. Respiration rates have a particularly large influence on production models and indicate that increasing temperature due to climate change could have significant consequences for net carbon fixation of macroalgae. This research gives valuable insight into the production of marine macroalgae and reinforces the notion that they are amongst the most productive systems on earth. These results revealed the importance of examining natural communities, as opposed to randomised assemblages and suggest a vital role of species diversity and community composition. Although there was no functional redundancy of the canopy forming species there did appear to be significant redundancy within the subcanopy assemblage. The identity of subcanopy species had little effect on production, but over longer temporal scales, as species come and go, they may help buffer the communities in terms of primary production. Furthermore, the relationship between biodiversity and ecosystem function (primary production), although driven by diversity, is moderated by resource levels. The complex relationship between irradiance, diversity and production shows the importance of resource levels in the enhancement of function with increasing biodiversity. Due to fundamental differences in terrestrial and marine systems, I was able to examine the effects of discrete levels of irradiance on production, which indicated an important role of complementary light use. This study represents advancements not only in the understanding of primary production in macroalgal assemblages, but also has implications for how diversity may enhance function in other autotrophic systems. The important role of enhanced efficiency of photon capture in multi-canopy layer communities may prove an essential process in ecosystems as diverse as macroalgal beds and tropical rain-forests.

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Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1997. / Errata inserted. Bibliography: leaves 98-120.