Introduction Anyone who has ever overseen the installation of a new cyclotron is aware of the importance of addressing the numerous vendor-supplied site specifications prior to its arrival. If the site is not adequately prepared, the facility may face project cost overruns, poor cyclotron performance and unintended maintenance costs. Once a facility has identified the space, providing sufficient power is the next step. Every cyclotron vendor will provide you with a set of power specifications, but meeting these specifications can be difficult, especially when the cyclotron is placed in an existing structure. The cyclotron is an interesting collection of power supplies providing power to sensitive electronic circuitry. It is not sufficient to just provide enough power; you must also provide quality power. It is hoped that our efforts to resolve our poor power quality problems will assist others as they replace aging cyclotrons in existing institutions whose power quality has degraded over the years. The University of Iowa Hospitals and Clinics completed installation of a GE PETtrace 800 cyclotron in November 2011. Four months prior to installation, GE service personnel arrived to do a power assessment. The result was that we met their specifications, but with reservations. We could easily provide the quantity of power required, but the specification also states that GE recommends that primary power remain at 480 VAC ± 5%. GE service personnel attached a power quality analyzer to the cyclotron main power panel and determined that we did have some events of 7 to 8 % sag, but they were in-frequent, perhaps once or twice a week lasting 20 to 50 msec. Sags were confirmed to be the result of large non-linear loads elsewhere in the hospital. If these occurred during a run, they may shut down the cyclotron, specifically the RF power supply. Further investigation revealed the presence of harmonics on our power. Harmonics are the multiples of 60Hz power that are reflected back into your facility’s power grid from large motor drivers. Commercial air handler, water pump and fan motors often use variable frequency drives (VFDs) for proportional control to meet the changing facility demands. This pro-vides a significant on-going cost savings, but may play havoc with power quality throughout the institution. Harmonic distortion is often quantified as a total harmonic distortion (THD) percentage. Though not specifically mentioned in the site-specifications, our experience here will show that it is important not to overlook harmonic distortion. Its effects can be varied, erratic and wide-spread throughout the cyclotron system. When asked, GE service referred us to IEEE standards for electrical systems and equipment which states that THD is recommended to be below 5 % for most applications, but below 3 % for sensitive settings including airports and hos-pitals1. Mitigation of voltage sag and harmonic distortion is an expensive and complex topic. It is recommended that you consult with your cyclotron vendor to determine if there exists a field-tested solution. Additionally, you should consult a power systems specialist to do an audit of your building’s power system. Material and Methods Characterization of Power Quality: This was accomplished using a Hioki 3197 Power Quality Analyzer and a couple Dranetz PX-5 Power Xplorers. Each monitoring cycle logged data for about a week, which seemed to be about the limit for these units when logging both THD and surge/sag events down to the duration of a single 60Hz cycle. Analysis of the circuit diagrams and communication with GE engineers indicated that the main power contactors to the cyclotron RF system were dropping power to protect the system. The feedback for this shutoff is a detection signal from the front-end EHT (high-voltage generation) circuit that is set at a level to be representative of the 5% AC deviation specification. RF Power System Contactors: Every time the contactors of the RF power distribution system are energized/de-energized, some arching occurs at the contact surfaces. This arching pits the contactor surfaces such that over time the contactor surfaces become irregular and potentially resistive. Since the RF protection circuit triggered by the EHT circuit is downstream from the contactors, it is not so hard to envision why the system becomes more sensitive over time2. Additionally, the harmonic distortion also exists on the AC voltage energizing the contactors. As a result, they may not actuate as smoothly (de-pendent of degree of harmonic distortion) and further hasten the normal rate of pitting of contactor surfaces. Results and Conclusion Within weeks of installation, we began to get RF power shutoffs. They were infrequent at first, but soon began to occur numerous times a week, then numerous times a day. At approximately 3 months post installation, it was often difficult to get through a standard 30 to 45 minute bombardment to make F-18 for our daily patient FDG doses. We limped along for over a year until the University was willing to invest in a solution to address our power problems. Periodic Power Analyses: These analyses, per-formed over the next year, indicated that our power quality worsened in the winter and re-turned to functional levels in the summer. The instance of voltage sag remained approximately the same throughout the year (a few short sags per week), but the THD was down to 6 % in the summer and nearly 10% in the winter. This result, combined with RF shutdown tracking and lack of correlation between observed power sags and RF shutdowns, led us to the conclusion that our very high harmonic distortion combined with small power fluctuations (< 5 %) were the culprit. Mitigation Planning: There are a number of power conditioning technologies, but imposing the need to remove both voltage sag as well as harmonic distortion, quickly narrows the field. What remains are the following options: 1) UPS line conditioner with batteries, 2) UPS line conditioner with flywheel or 3) motor-generator power isolator. Battery maintenance costs ruled out the UPS battery line conditioner. Of the remaining two, if you have the space, the motor-generator is the simplest and cheapest (favored by forward military hospital units). But for the space constrained user, like us, the UPS flywheel line conditioner became the preferred option. Additionally, it was identified in a power audit that the THD was only 4% at the transformers connected directly to the local power utility company supply (upstream of load effect and harmonic distortion sources). This was to be expected as load effects and harmonic distortion are worse if your tie-in point to the building power grid is at the same level or downstream of their sources. Additionally, a test was performed during a hospital backup generator test, wherein the suspected primary offenders (large motors and VFDs) were diverted to backup. As a result, the THD measured at the cyclotron primary power panel dropped by 2.5 %. Working with University electricians, an outside power consultant, GE engineering and University Hospital Radiology Engineering, a two phase plan was created. Phase 1: With a repurposed utility transformer, the cyclotron and PET cameras got their own dedicated transformer connected to the main utility power feed. We also replaced the old contactors in the RF power distribution system. Since installation, the measured THD has remained at 4.5 to 5 % year round and the sag incidence and magnitude are slightly improved. Phase 2: With a quote from GE for a flywheel UPS we should be able to fully condition the power entering our facility, removing the load effect voltage sags as well as the harmonic distortion. One year of operation after Phase 1 implementation, it has been decided that Phase 1 was all that was required. We haven’t had a single new instance of RF shutdown since.

Os motores a jato são componentes importantes e complexos de engenharia cuja eficiência e desempenho estão diretamente ligados à temperatura de operação na câmara de combustão, ou seja, quanto maior a temperatura dos gases nesta região, maior a eficiência global do processo, resultando em economia de combustível e maior potência. A superliga aeronáutica a base de níquel é o material atualmente utilizado nestes componentes mais críticos das turbinas, mas o seu desenvolvimento está chegando cada vez mais próximo do limite e, por isso, existe uma demanda de materiais que possam substituí-las. Os materiais constituídos de microestruturas multifásicas, como as ligas MR-Si-B (MR= Metal Refratário) apresentam potencial para a substituição das superligas nestas aplicações. Estudos recentes no sistema Ta-Si-B identificaram a existência de uma fase ainda não catalogada, denominada &#966;. No entanto, a sua estrutura cristalina permanece indefinida devido à dificuldade em se obter uma amostra com grande fração volumétrica de &#966;. A substituição do silício por germânio nesse sistema pode aumentar o campo de estabilidade de &#966; possibilitando assim, a obtenção de uma amostra através da qual a estrutura cristalina dessa fase possa ser determinada. Entretanto, para o estudo do ternário Ta-Ge-B, é importante o conhecimento dos binários que o compõem (Ta-Ge, Ta-B, Ge-B) e não foi encontrada na literatura uma proposta para o diagrama binário Ta-Ge nem informações suficientes para construí-lo. Este trabalho, portanto, tem como objetivo propor um diagrama de fases para o sistema Ta-Ge, e investigar a possível existência da fase &#966; no sistema ternário Ta-Ge-B. Para isto foram confeccionadas amostras, a partir de matérias primas (tântalo, germânio e boro) de alta pureza, em toda a extensão composicional do sistema Ta-Ge e na região rica em tântalo do sistema Ta-Ge-B. As amostras, em seu estado bruto de fusão bem como após tratamentos térmicos, foram caracterizadas por microscopia eletrônica de varredura (MEV), microanálise eletrônica por energia dispersiva (EDS) e difratometria de raios X (DRX). Com os resultados obtidos neste trabalho foi proposto um diagrama para o sistema Ta-Ge. A temperatura do eutético na região rica em Ta (2444°C) foi medida através de pirometria ótica. Devido a dificuldades encontradas em fundir a arco amostras com altos teores de Ge, novos experimentos serão necessários para melhor determinar esta região do diagrama de fases. Os resultados obtidos nas amostras ternárias sugerem que a fase ternária &#966; é estável no sistema Ta-Ge-B. / Jet engines are important and complex engineering devices, whose efficiency and performance are directly related to the operating temperature of the combustion chamber, the higher the gas temperature in this region, the greater the overall efficiency of the process, resulting in economy of fuel and more efficiency. Ni-based superalloys are currently used in the most critical jet engine components. Their development is coming close to a temperature limit and, therefore, there is a demand for new materials to replace them. Materials with multiphase microstructures, such as MR-Si-B alloys (MR = Refractory Metal), have a good potential for substituting superalloys in these applications. Recent studies in the Ta-Si-B system shows the stability of a phase &#966; whose crystal structure remains unknown due to the difficulty in obtaining a sample with large volume fraction of &#966;. The substitution of silicon by germanium in this system may increase the stability of &#966;, enabling the production of a sample by which the crystal structure of this phase can be determined. The study of the Ta-Ge-B ternary system requires the knowledge of the phase relations on its limiting binaries. However, there is no Ta-Ge phase diagram available in the literature, nor enough experimental information to propose one. Therefore, the present work aims at the experimental investigation of the phase relations on the Ta-Ge system, and of the stability of phase &#966; on the Ta-rich region of the Ta-Ge-B ternary system. Samples were prepared by arc melting high purity materials (tantalum, germanium and boron) under Ti-gettered argon. Their microstructures, in the as cast state as well as after heat treatments were characterized by scanning electron microscopy (SEM), energy dispersive electron probe microanalysis (EDS) and X-ray diffraction (XRD). A Ta-Ge binary phase diagram is proposed based on the results of the present work. The temperature of the Ta-rich eutetic (2444°C) was measured by optical pirometry. Due to the difficulty of arc melting samples with high Germanium contents, further investigation is still necessary for this region of the phase diagram. The results for the ternary samples suggest the stability of the &#966; phase in the Ta-Ge-B system.

Nanomaterials (NMs) can be defined as having at least one external dimension between 1-100nm. Due to their small size, NMs have a large surface area giving them characteristics that differ from bulk material. NMs are incorporated into numerous applications making environmental exposure to NMs likely. Increased reliance on plastic results in accumulation of nano-plastics in fresh waters. Polystyrene (PS) acts as a representative of both nano-plastic and NMs. The deposition of gold (Au) NMs is also likely due to their use in medical applications so that both PS and Au have a potential to interact with environmental organisms. Daphnia manga (D. magna) is an ideal candidate in fresh water toxicity testing. Toxicity, uptake and retention of NMs by organisms is dependent on several factors such as NM charge, shape, chemical composition and the absorption of natural biomolecules binding to the surface of the NM creating an eco-corona, altering stability of the NMs thereby changing their toxicity. This work investigates the toxicity of PS and Au NMs and explores the effects of charge, shape, presence of a corona and the impact of realistic modes of presentation of NMs to D. magna and how these factors impact toxicity, uptake, retention and depuration.

This thesis applies the construction grammar framework to a corpus-based study of the development of post-verbal ge in Chinese. Ge in Mandarin Chinese is widely considered as a general classifier (Li and Thompson 1981, Zhu 1982, Lü 1984). As a classifier, the main function of ge is to categorize the entity denoted by the following noun and enable numeral attachment. Thus, ge is typically preceded by numerals and followed by referential nouns. In a post-verbal position, when the numeral before ge is yi ‘one’, the numeral tends to be omitted. The ‘bare ge’ in post-verbal position is found co-occurring with non-referential nouns and non-nominal elements, such as predicative adjectives and verb phrases. The function of the post-verbal ge with these atypical collocations has attracted much attention in Chinese linguistic research (Zhang, 2003; Lü, 1984; Biq, 2004). One of the features of the previous research is that the researchers focus on a sub-set of post-verbal ge variations and try to provide a generalized claim about all instances of post-verbal ge used in Mandarin. Another feature is that the research focus is on ge alone and little attention has been paid to its co-texts and contexts of use. In addition, very little work has been done on the emergence of the mysterious function of post-verbal ge or the internal links between ge as a classifier and this new function. The main task of this thesis is to identify the semantic and syntactic properties of the post-verbal ge with atypical collocations and to explore how ge developed these properties in the post-verbal position. Within a construction grammar framework, the post-verbal ge with this special function and its co-texts are identified as a construction with a telic and bounded aspectual meaning. This [V ge X] construction of telic and bounded aspectual meaning is different from the classifier construction in terms of morpho-syntactic features as well as semantic and pragmatic properties. With the constructional approach, this research shows that the unit to which changes apply is not ge alone but the [V ge X] construction and the morpho-syntactic and semantic relations between these three elements have changed over time. Furthermore, the investigation into the mechanism of these changes also reveals that the development of micro-constructions of the [V ge X] construction of telic and bounded aspectual meaning occurred in a constructional network, which links different constructions with the [V ge X] schema.

Os motores a jato são componentes importantes e complexos de engenharia cuja eficiência e desempenho estão diretamente ligados à temperatura de operação na câmara de combustão, ou seja, quanto maior a temperatura dos gases nesta região, maior a eficiência global do processo, resultando em economia de combustível e maior potência. A superliga aeronáutica a base de níquel é o material atualmente utilizado nestes componentes mais críticos das turbinas, mas o seu desenvolvimento está chegando cada vez mais próximo do limite e, por isso, existe uma demanda de materiais que possam substituí-las. Os materiais constituídos de microestruturas multifásicas, como as ligas MR-Si-B (MR= Metal Refratário) apresentam potencial para a substituição das superligas nestas aplicações. Estudos recentes no sistema Ta-Si-B identificaram a existência de uma fase ainda não catalogada, denominada &#966;. No entanto, a sua estrutura cristalina permanece indefinida devido à dificuldade em se obter uma amostra com grande fração volumétrica de &#966;. A substituição do silício por germânio nesse sistema pode aumentar o campo de estabilidade de &#966; possibilitando assim, a obtenção de uma amostra através da qual a estrutura cristalina dessa fase possa ser determinada. Entretanto, para o estudo do ternário Ta-Ge-B, é importante o conhecimento dos binários que o compõem (Ta-Ge, Ta-B, Ge-B) e não foi encontrada na literatura uma proposta para o diagrama binário Ta-Ge nem informações suficientes para construí-lo. Este trabalho, portanto, tem como objetivo propor um diagrama de fases para o sistema Ta-Ge, e investigar a possível existência da fase &#966; no sistema ternário Ta-Ge-B. Para isto foram confeccionadas amostras, a partir de matérias primas (tântalo, germânio e boro) de alta pureza, em toda a extensão composicional do sistema Ta-Ge e na região rica em tântalo do sistema Ta-Ge-B. As amostras, em seu estado bruto de fusão bem como após tratamentos térmicos, foram caracterizadas por microscopia eletrônica de varredura (MEV), microanálise eletrônica por energia dispersiva (EDS) e difratometria de raios X (DRX). Com os resultados obtidos neste trabalho foi proposto um diagrama para o sistema Ta-Ge. A temperatura do eutético na região rica em Ta (2444°C) foi medida através de pirometria ótica. Devido a dificuldades encontradas em fundir a arco amostras com altos teores de Ge, novos experimentos serão necessários para melhor determinar esta região do diagrama de fases. Os resultados obtidos nas amostras ternárias sugerem que a fase ternária &#966; é estável no sistema Ta-Ge-B. / Jet engines are important and complex engineering devices, whose efficiency and performance are directly related to the operating temperature of the combustion chamber, the higher the gas temperature in this region, the greater the overall efficiency of the process, resulting in economy of fuel and more efficiency. Ni-based superalloys are currently used in the most critical jet engine components. Their development is coming close to a temperature limit and, therefore, there is a demand for new materials to replace them. Materials with multiphase microstructures, such as MR-Si-B alloys (MR = Refractory Metal), have a good potential for substituting superalloys in these applications. Recent studies in the Ta-Si-B system shows the stability of a phase &#966; whose crystal structure remains unknown due to the difficulty in obtaining a sample with large volume fraction of &#966;. The substitution of silicon by germanium in this system may increase the stability of &#966;, enabling the production of a sample by which the crystal structure of this phase can be determined. The study of the Ta-Ge-B ternary system requires the knowledge of the phase relations on its limiting binaries. However, there is no Ta-Ge phase diagram available in the literature, nor enough experimental information to propose one. Therefore, the present work aims at the experimental investigation of the phase relations on the Ta-Ge system, and of the stability of phase &#966; on the Ta-rich region of the Ta-Ge-B ternary system. Samples were prepared by arc melting high purity materials (tantalum, germanium and boron) under Ti-gettered argon. Their microstructures, in the as cast state as well as after heat treatments were characterized by scanning electron microscopy (SEM), energy dispersive electron probe microanalysis (EDS) and X-ray diffraction (XRD). A Ta-Ge binary phase diagram is proposed based on the results of the present work. The temperature of the Ta-rich eutetic (2444°C) was measured by optical pirometry. Due to the difficulty of arc melting samples with high Germanium contents, further investigation is still necessary for this region of the phase diagram. The results for the ternary samples suggest the stability of the &#966; phase in the Ta-Ge-B system.

none

Over the past years, semiconductor quantum crystallite or micro-crystals of Si and Ge have received considerable attention for both fundamental and technological reasons. Quantum size effect and visible photoluminescence have been observed in nanometer-sized Si or Ge quantum crystallites. It has two practical applications. one is to prove to be optical semiconductor devices¡Fthe other is to turn into nano-crystal memories. The material Ge is considered a promising material for optical device fabrication. It has been found that Ge quantum dots embedded in Si matrices exhibit photoluminescence (PL) originating from the spatially indirect no-phonon recombination between holes confined within the Ge dots and electrons from the conduction band of the Si. For nano-crystal memories employing discrete charge traps as storage elements have exhibited great potential in device performance, power consumption, and technology scalability, thus recently attracting much research attention as promising candidates to replace the conventional DRAM or Flash memories. In the thesis, we will discuss the material properties of SiNGe and SiCNGe films, such as FTIR, AES, Raman Scattering spectrum analysis. The write/erase and retention characteristics of the nano-crystal are presented through current¡Vvoltage (I¡VV) and capacitance¡Vvoltage (C¡VV) measurements.

No description available.

Ocean chemistry has oscillated throughout Earth history to favour the dominant non-biogenic polymorph of calcium carbonate (CaCO3) to be either calcite or aragonite (Sandberg, 1983). Throughout the Phanerozoic these oscillations have occurred to facilitate aragonite-dominant conditions three times and calcite-dominant conditions twice. These aragonite-calcite seas conditions have previously been viewed as a global phenomenon where conditions fluctuate over time, but not in space, and represent the main environmental context in which the evolution of CaCO3 biomineralisation has occurred (Stanley and Hardie, 1998). CaCO3 is one of the most widely distributed minerals in the marine environment, occurring throughout geological history, both biogenically and non-biogenically (Lowenstam and Weiner, 1989). Marine non-biogenic precipitates are commonly found as carbonate ooids, sedimentary cements and muds (Nichols, 2009). Biogenic CaCO3 is formed via biomineralisation in calcifying organisms (Lowenstam and Weiner, 1989; Allemand et al., 2004), and is much more abundant than the non-biogenic forms. Although CaCO3 is abundant, it only accounts for a small proportion of the global carbon budget. Biogenic CaCO3 is representative of a larger proportion of the global carbon budget than non-biogenically formed CaCO3 (Berelson et al., 2007). The main driving force controlling the precipitation of CaCO3 polymorphs is the Mg:Ca molar ratio of seawater (Morse et al., 2007). However, other parameters such as temperature (Burton and Walter, 1984; Morse et al, 1997; Balthasar and Cusack, 2015), pCO2 (Lee and Morse, 2010), and SO4 (Morse et al., 2007) are also known to influence CaCO3 polymorph formation but are often overlooked in the context of aragonite-calcite seas. Fluctuations in these parameters of Mg:Ca ratio, SO42+ and pCO2 of seawater have been suggested to cause shifts in original composition of non-biogenic marine carbonates, and in turn viewed as the main driving mechanisms facilitating the switch between aragonite and calcite dominance (Morse et al., 1997; Lee and Morse, 2010; Bots et al., 2011). Specifically the influence of temperature is important because it is likely to result in aragonite-calcite sea conditions to vary spatially (Balthasar and Cusack, 2015). Today marine temperatures are changing across the latitudes due to environmental factors. Global CO2 levels have increased significantly since industrialisation (Doney et al., 2009), with 33% entering the oceans and reducing pH (Raven et al., 2005) accelerating climate change (IPCC, 2013) and influencing marine calcification (Fitzer et al., 2014a; 2015b; Bach, 2015; Zhao et al., 2017). Strong links between the carbon cycle and climate change observed in the rock record give evidence that environmental changes such as pCO2 and global warming have impacts on calcification and marine biota (Hönish et al., 2012). The first objective was to determine the influence of Mg:Ca ratio, temperature and water movement on the first-formed precipitates of non-biogenic CaCO3 precipitation yielded via a continuous addition technique experiments (Chapter 3). CaCO3 precipitation was induced by continuously adding bicarbonate to a bulk solution of known Mg:Ca ratio (1,2 or 3), and fixed salinity of 35 (practical salinity scale), at 20°C and 30ºC in still conditions, and then repeated with the solution being shaken at 80rpm mimicking more natural marine conditions. The mineralogy and crystal morphology of precipitates was determined using Raman Spectroscopy and Scanning Electron Microscopy. Results in Chapter 3 indicated that polymorphs co-precipitate, with the ratio of aragonite to calcite increasing with increased Mg:Ca ratio and elevated temperature. The main difference between still and shaken conditions was that overall, more crystals of aragonite compared to calcite precipitate in shaking conditions. The crystal size is less influenced in aragonite, but calcite crystals were smaller. These results contradict current views on aragonite-calcite seas as spatially homogenous ocean states need to be re-examined to include the effect of temperature on the spatial distribution of CaCO3 polymorphs. Examining polymorph growth under these experimental constraints allows us to gain a better understanding of how temperature and Mg:Ca together control non-biogenic aragonite and calcite precipitation providing a more realistic environmental framework in which to evaluate the evolution of biomineralisation. To further this work, the same continuous addition technique was used with the presence of sulphate in the mother solution (Chapter 4). Sulphate being the 4th most common marine ion (Halvey et al., 2012) and known to have an influence on mineralogy (Kontrec et al., 2004). The presence of sulphate increase the aragonite to calcite proportion formed compared to sulphate-free conditions (Chapter 4). Elevated temperature with sulphate further increased the proportion of aragonite to calcite facilitated (Chapter 4). In the presence of sulphate the main difference between sulphate-free environments and those with sulphate environments was: in still conditions the presence of sulphate increased the crystal number more than the crystal size at 20°C; at 30°C or in shaken conditions the presence of sulphate increased the crystal size of aragonite to calcite much more than it had influence on the crystal number. Non-biogenically the influence of sulphate lowered the threshold of Mg:Ca ratio that the switch between calcite and aragonite would be facilitated at (Bots et al., 2011). This would have implications for marine calcification as pure calcite seas would become very rare and imply that organisms would be forming calcified hard parts out with the supported mineralogies. Biogenic application of these results is complex however as organisms often have the ability to select aragonite as their main polymorph for their own functional requirements (Weiner and Dove, 2003). The growth parameters of non-biogenic polymorph formations grown from artificial seawater can be used to understand how organism control can influence the polymorph formation under similar conditions (Kawano et al., 2009). Assessing the elemental composition of mussel shells grown under know conditions of temperature and pCO2 allowed the environmental influences on mineralogy be assessed under possible the projected changes in climate forecast to occur by 2100 by IPCC (2013). Prior to this research, no study had used Mytilus edulis shell elemental composition to test the influence of aragonite-calcite sea conditions on mineralogy. This research compiles a detailed source of information on the constraints from environmental sources such as temperature and pCO2, on the elemental concentrations within shell formation and what potential changes could occur in response to a changing marine environment (Chapter 5). Here elevated temperature significantly increased the concentration of magnesium in calcite, but did not influence the magnesium concentration of aragonite unless combined with elevated pCO2. The concentrations of sulphur in calcite were significantly decreased at elevated pCO2 or combined increased temperature and pCO2 as concentrations of sodium were found to be increased under these conditions. In aragonite the concentrations of both sulphur and sodium were significantly different under all scenarios. Strontium did not yield any significant results in this research in either calcite or aragonite. Results observed indicate that the shell elemental concentrations are influenced differently in aragonite or calcite, and further influenced by environmental conditions based on the original mineralogy. This suggests that physiological mechanisms under the constraints of increased temperature and pCO2 can override the seawater chemistry influences of aragonite-calcite seas impacting on mineralogy. / This research allows comparison of how non-biogenic and biogenic CaCO3 formation is influenced by seawater chemistry and environmental parameters to determine the dominant mineralogy. Increased temperature in both formations has shown to increase the impact of magnesium on calcite enabling the facilitation of aragonite. However, magnesium has influence on biogenic aragonite in extreme combined conditions of elevated temperature and pCO2. This work indicates that CaCO3 formation is complex and requires a multi-variable approach to understanding the mechanisms that facilitate the dominant mineralogy. By including variables such as temperature, this research suggests that aragonite-calcite seas conditions do not facilitate globally homogeneous switches in mineralogy, but the mineralogy is indeed influenced on latitudinal scales by other factors that influence the mechanisms involved.

No description available.