The effect of fluorine on the solubilities of Mn-columbite (MnNb2O6), Mn-tantalite (MnTa2O6), zircon (ZrSiO4) and hafnon (HfSiO4) were determined in highly fluxed, water-saturated haplogranitic melts at 800 to 1000 °C and 2000 bars. The melt corresponds to the intersection of the granite minimum with the albite-orthoclase tieline (Ab72Or28) in the quartz-albite-orthoclase system (Q-Ab-Or) due to the addition of P2O5 to the melt. The melt content of P2O5 is 1.7 wt. %, and also contains 1.1 and 2.02 wt. % of Li2O and B2O3, respectively. The composition of the starting glass represents the composition of melts from which rare-elements pegmatites crystallized. Up to 6 wt. % fluorine was added as AgF in order to keep the aluminum saturation index (ASI) of the melt constant. In an additional experiment F was added as AlF3 to make the glass peraluminous. The nominal ASI (molar Al/[Na+K]) of the melts is close to 1 and approximately 1.32 in peraluminous glasses, but if Li considered as an alkali, the ASI of the melts are alkaline (0.85) and subaluminous (1.04), respectively. The solubility products [MnO]*[Nb2O5] and [MnO]*[Ta2O5] are nearly independent of the F content of the melt, approximately 18.19 ± 1.2 and 43.65 ± 2.5 x10-4 KSP (mol2/kg2), respectively. By contrast, there is a positive dependence of zircon and hafnon solubilities on the fluorine content, which increases from 2.03 ± 0.03 x10-4 (mol/kg) ZrO2 and 4.04 ± 0.2 x10-4 (mol/kg) HfO2 for melts with 0 wt. % F to 3.81 ± 0.3 x10-4 (mol/kg) ZrO2 and 6.18 ± 0.04 x10-4 (mol/kg) HfO2 for melts with 8 wt. % F. Comparison of the data from this work and previous studies indicates that ASI of the melt seems to have a stronger effect than the contents of fluxing elements in the melt and the overall conclusion is that fluorine is less important (relative to melt compositions) than previously thought for the control on the behavior of high field strength elements in highly evolved granitic melts. Moreover, this study confirms that although Nb, Ta, Zr and Hf are all high field strength elements, Nb-Ta and Zr-Hf are complexed differently.

A flux declination predication model for nanoparticle-containing wastewaters treated by a simultaneous electrocoagulation/electro- filtration (EC/EF) process was investigated by perceiving blocked membrane pores, concentration polarization layer, cake layer, and applied electric field strength in this study. As nanotechnology develops, it has been used in many applications. However, its environmental impacts have not been extensively studied. Membrane technology is one of the direct and effective treatment methods for removing nanoparticles from wastewater. But nanoparticle-containing wastewater treated by membrane technology would face the problem of membrane fouling. In this study, oxide chemical mechanical polishing (CMP) wastewater, copper CMP wastewater, and nanosized TiO2-containing wastewater were treated by a EC/EF treatment module. In the EC/EF treatment module, iron, aluminum, and stainless steel were respectively selected as th anode and cathode. Polyvinylidene fluoride (PVDF) with a nominal pore size of 0.1 £gm and carbon/Al2O3 tubular inorganic composite membranes with a pore size ranging from 2 to 10 nm were used in this work. In this work, the changes of the relevant performance of membrane with changes of applied pressure (9.8-19.6 kPa), crossflow velocity (0.3-0.5 m/s) and applied electric filed strength (25-233 V/cm) were studied. The simulation results of a modified mathematic model showed that the flux declination would be fitted finely by an exponential function. Experimental results showed that a higher transmembrane pressure would yield a higher cake concentration and a higher crossflow velocity would yield the steady flux quickly. Overall speaking, the flux declination for nanoparticle-containing wastewaters treated by a simulataneous EC/EF process was described properly as a exponential form. The exponential function could simply show the flux declination of different samples treated by different modules in different situations.

ABSTRACT In this study, two chemical mechanical polishing (CMP) wastewaters were treated by crossflow electro-microfiltration. Also studied are the effects of operation parameters on their treatment efficiencies. In the semiconductor industry, presently, CMP has become the key technique to provide global planarization on interlevel dielectrics (ILD) and metal layers of wafers. In general, the post-CMP cleaning process will produce a great quantity of CMP wastewater. Normally, CMP wastewater consists of abrasives of high concentration and stability, chemicals (e.g., oxidant and surfactant), and a tremendous mass of de-ionized water. Because of the negatively charged suspended solids in CMP wastewater, crossflow electro-microfiltration was used to treat this type of wastewater. By applying an electric field to the system, the negatively charged suspended solids were expelled from the membrane surface moving toward the anode. Not only reducing the cake formation on the membrane, enhancement of the filtration rate and permeate flux have also been found when an external electric field is applied to the filtration system. In this investigation, CMP wastewaters obtained from wafer fabs A and B were first characterized by various standard methods. In CMP wastewater A, the suspended solids were found to have a high negative zeta potential, about ¡V78 mV. Its electrical conductivity was determined to be 127.2 £gS/cm. Before testing, each CMP wastewater was pre-filtered using a filter paper of 1.2 £gm in pore size. An experimental design based on the Taguchi method was employed. The L9 orthogonal arrays were utilized to investigate the effects of four experimental factors ( i.e., electric field strength, crossflow velocity, transmembrane pressure, and membrane pore size) on the filtration rate and permeate quality in the crossflow electro-microfiltration system. When the electric field strength applied was lower than the critical electric field strength, increases of the electric field strength, transmembrane pressure, and membrane pore size were found to be beneficial to the filtration rate. The experimental results were further subjected to the analysis of variance and regular analysis. For both CMP wastewaters A and B, the electric field strength and membrane pore size were determined to be very significant parameters. In this filtration system, the optimal treatment efficiency could be achieved by using a higher electric field strength, lower crossflow velocity, higher transmembrane pressure, and larger membrane pore size. The quality of permeate thus obtained was even better than the tap water quality standards. Therefore, the permeate might be worth recycling for various purposes.

The effect of fluorine on the solubilities of Mn-columbite (MnNb2O6), Mn-tantalite (MnTa2O6), zircon (ZrSiO4) and hafnon (HfSiO4) were determined in highly fluxed, water-saturated haplogranitic melts at 800 to 1000 °C and 2000 bars. The melt corresponds to the intersection of the granite minimum with the albite-orthoclase tieline (Ab72Or28) in the quartz-albite-orthoclase system (Q-Ab-Or) due to the addition of P2O5 to the melt. The melt content of P2O5 is 1.7 wt. %, and also contains 1.1 and 2.02 wt. % of Li2O and B2O3, respectively. The composition of the starting glass represents the composition of melts from which rare-elements pegmatites crystallized. Up to 6 wt. % fluorine was added as AgF in order to keep the aluminum saturation index (ASI) of the melt constant. In an additional experiment F was added as AlF3 to make the glass peraluminous. The nominal ASI (molar Al/[Na+K]) of the melts is close to 1 and approximately 1.32 in peraluminous glasses, but if Li considered as an alkali, the ASI of the melts are alkaline (0.85) and subaluminous (1.04), respectively. The solubility products [MnO]*[Nb2O5] and [MnO]*[Ta2O5] are nearly independent of the F content of the melt, approximately 18.19 ± 1.2 and 43.65 ± 2.5 x10-4 KSP (mol2/kg2), respectively. By contrast, there is a positive dependence of zircon and hafnon solubilities on the fluorine content, which increases from 2.03 ± 0.03 x10-4 (mol/kg) ZrO2 and 4.04 ± 0.2 x10-4 (mol/kg) HfO2 for melts with 0 wt. % F to 3.81 ± 0.3 x10-4 (mol/kg) ZrO2 and 6.18 ± 0.04 x10-4 (mol/kg) HfO2 for melts with 8 wt. % F. Comparison of the data from this work and previous studies indicates that ASI of the melt seems to have a stronger effect than the contents of fluxing elements in the melt and the overall conclusion is that fluorine is less important (relative to melt compositions) than previously thought for the control on the behavior of high field strength elements in highly evolved granitic melts. Moreover, this study confirms that although Nb, Ta, Zr and Hf are all high field strength elements, Nb-Ta and Zr-Hf are complexed differently.

A theory is developed to explain the dependence of carrier transport in a thin semiconducting film on film thickness, magnetic field strength, and the dominant bulk scattering mechanism. This theory is based on the solution of the linearized Boltzmann equation in relaxation time form. The semiconductor is assumed to be bounded and nondegenerate with spherical energy surfaces and a scalar effective mass, It is also assumed to be flat banded with totally diffuse scattering at the surface. Classical Boltzmann statistics are used for equilibrium. The dependence of the relaxation time on the carrier energy is approximated by a power law equation. The principle improvement over similar theories is the treatment of the dependence of the relaxation time on carrier energy. The power law approximation for this dependence is valid for randomizing and elastic scattering mechanisms.

Titel: Magnetfältstyrkans betydelse för personer med multipel skleros eller kliniskt isolerat syndrom - en litteraturstudie Bakgrund: Multipel skleros (MS) är en demyeliniserande autoimmun sjukdom i centrala nervsystemet som debuterar främst hos unga vuxna. MS diagnostiseras utifrån kliniska och radiologiska fynd enligt McDonaldkriterierna där inga krav ställs på vilken fältstyrka som bör användas. Magnetkameror med högre fältstyrkor blir dock vanligare. Syfte: Att undersöka om högre fältstyrka (Tesla, T) gav bättre detektion av lesioner vid magnetresonanstomografiundersökningar av personer med multipel skleros eller kliniskt isolerat syndrom. Metod: I denna litteraturstudie gjordes sökningarna i databaserna PubMed, Web of Science och Scopus mellan 8 och 11 mars 2016. Tio kvantitativa artiklar kvalitetsgranskades och analyserades för att slutligen sammanställas i resultatet. Resultat: Resultatet presenteras under fyra huvudrubriker och totalt tolv underrubriker. Huvudrubrikerna är skillnad mellan fältstyrkor, fältstyrkor och anatomiska regioner, fältstyrkor och pulssekvenser samt artefakter och bildkvalitet. Konklusion: 3T och 7T är bättre än 1,5T och att 7T ofta är bättre än 3T på att detektera lesioner. Dock måste andra aspekter tas i beaktning då det är många parametrar som spelar in vid en magnetresonanstomografiundersökning. Ytterligare studier gällande bland annat optimering av pulssekvenser samt patienters upplevelser av ultrahöga fältstyrkor rekommenderas. / Title: The importance of magnetic field strength for people with multiple sclerosis or clinically isolated syndrome - a literature study. Background: Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system debuting mostly in young adults. MS is diagnosed based on clinical and radiological findings according to the McDonald criteria where no requirements are placed on which field strength that should be used. Magnetic resonance imaging (MRI) scanners with higher field strengths are however becoming more common. Objective: To investigate whether higher field strength (Tesla, T) gave better detection of lesions at MRI examinations of people with MS or clinically isolated syndrome. Methods: In this literature study searches were made in the databases PubMed, Web of Science and Scopus between the 8th and 11th of March 2016. Ten quantitative articles were examined and analyzed to finally be compiled under the results. Results: The results are presented under four main headings and twelve sub- headings. The main headings are the differences between field strengths, field strength and anatomical regions, field strength and pulse sequences and artifacts and image quality. Conclusion: 3T and 7T are better than 1,5T and 7T is usually better than 3T at detecting lesions. However other aspects need to be taken into account because many parameters come into play during MRI examinations. Further studies regarding optimization of pulse sequences and field strength and patients’ experiences of ultrahigh field strength are recommended, among others.

Cell biological exposure studies in magnetic resonance imaging (MRI) environment, where a complex mixture of strong magnetic fields are present, have attracted considerable interest in recent years. The outcome of such studies might depend strongly on the conditions, for example exposure parameters and spatial variations of exposure. The aim of this thesis has been to give a detailed description of how the radio frequency (RF) magnetic field varies with position and sequence choice within an MRI bore from a patient perspective and to highlight the need of better consistency in future research. Method: A straightforward theoretical description on the contribution to the RF magnetic field from a birdcage coil is given. A one dimensional coaxial loop antenna has been used as a probe to measure spatial variations of the RF magnetic field in a 1.5T MRI scanner. An exposure matrix containing RF magnetic field strength (H1-field) amplitudes in three dimensions was constructed and used to study several clinical protocols and sequences. A qualified correspondence measurement was also made on a 3T MRI scanner. Results: Around isocenter, for a common field-of-view (FOV), changes in exposure conditions were small; however, rapid changes of exposure conditions occurred upon approaching the end rings. The dominating H1-field component switched from lying in the xy-plane to pointing the z-direction and was roughly 3 times larger than in isocenter. Practical difficulties indicate even larger differences at positions not measurable with the equipment at hand. The strongest H1-field component was 32.6 A/m at position (x,y,z)=(-24,8,24) cm from the isocenter. Conclusions: Machine parameters such as repetition time, echo time and flip angle have little to do with actual exposure. Specic absorption rate (SAR) values correlated well with the square of measured root-mean-square (RMS) values of the magnetic field (B1,RMS) but not with peak values of the magnetic field (B1,peak), indicating that peak values are not unlikely to be part of compromising factors in previous contradictory exposure research on genotoxicity. Furthermore exposure conditions depend strongly on position and unfavorable situations may occur in the periphery of the birdcage coil. Potentially elevated risks for conducting surfaces, for example arms or external fixations, in the proximity of the end rings, are proposed. Aside from spatial variation consideration on which type of geometry exposed cell-biological samples are placed in should be held since eddy currents, hot-spots and proper SAR depend on geometry. Conditions may vary considerably between in-vitro, ex-vivo and in-vivo studies since geometries of test tubes, petri dishes and humans differ.

Ce travail est une contribution à la compréhension de la structure à courte et moyenne distance des verres à base de TeO₂ via de nouveaux verres au sein des systèmes TeO₂-TiO₂-WO₃ (TTxWy) et TeO₂-NbO₂ ̩₅-WO₃ (TNxWy). De pertinentes corrélations sont révélées entre leurs propriétés structurales (en utilisant la spectroscopie Raman) et optiques. Globalement, l’ajout de TiO₂, WO₃ ou NbO₂ ̩₅ n’engendre aucune évolution structurale brutale. L’ajout de TiO2 induit une séparation de phases entre les régions amorphes riches en TiO2 et le réseau riche en TeO2. Cette interprétation est en accord avec le comportement structural prédit par la théorie de Dietzel sur la force de champ cationique. L’ajout de WO3 entraîne l’apparition (i) d’octaèdres WO₆ uniformément dispersés à travers le réseau des ponts Te–O–Te (pour de faibles teneurs en WO₃) et (ii) de régions riches en WO3 (pour des teneurs plus importantes en WO₃). L’ajout de NbO₂ ̩₅ engendre (i) une faible dépolymérisation structurale du réseau Te–O–Te et (ii) l’apparition des régions riches en NbO₂ ̩₅. Les verres étudiés sont dotés de forts indices de réfraction linéaires (2.19 dans TTxWy et 2.13 dans TNxWy en moyenne) et de remarquables susceptibilités non linéaires χ(3) (7.03 *10-13 esu dans TTxWy et 5.48 *10-13 esu dans TNxWy en moyenne, i.e., ~47 et ~37 fois plus élevées que la valeur de χ(3) du verre SiO₂). / In this work, we present a contribution to the understanding of the short- to medium-range structure of TeO₂-based glasses via new glasses within the TeO₂-TiO₂-WO₃ (TTxWy) and TeO₂-NbO₂ ̩₅-WO₃ (TNxWy) systems. Consistent correlations are revealed between their structural (using Raman spectroscopy) and optical properties. Globally, no striking structural evolutions take place upon adding TiO₂, WO₃ or NbO₂ ̩₅. Adding TiO2 results in a phase-separation between amorphous TiO₂-rich regions and TeO2-rich network, in harmony with the predicted structural behavior on the basis of Dietzel’s cationic field strength theory. Adding WO₃ leads to (i) uniformly dispersed WO₆ octahedra throughout the Te–O–Te network (at low WO₃ contents) and (ii) amorphous WO₃-rich regions (at higher WO₃ contents). Adding NbO₂ ̩₅ engenders (i) a weak structural depolymerization of the Te–O–Te network and (ii) occurrence of NbO₂ ̩₅-rich regions. The investigated glasses exhibit high linear refractive indices (averages of 2.19 in TTxWy and 2.13 in TNxWy) and remarkable nonlinear susceptibilities χ(3) (averages of 7.03 *10-13 esu in TTxWy and 5.48 *10-13 esu in TNxWy, i.e., ~47 and ~37 times higher than χ(3) of SiO₂ glass).

Multicomponent silicate and borosilicate glasses find wide technological applications ranging from optical fibers, biomedicine to nuclear waste disposal. As a common component of earth's mantle and nuclear waste, iron is a frequent encounter in silicate and borosilicate melts and glasses. The redox ratio in glass matrix defined by the ratio of ferrous and ferric ions is dependent on factors such as temperature, pressure, and oxygen fugacity. Understanding their roles on the short- and medium-range structure of these glasses is important in establishing the structure-property relationships which are important for glass composition design but usually difficult to obtain from experimental characterization techniques alone. Classical molecular dynamics simulations were chosen in this dissertation to study iron containing glasses due to challenges in experimental techniques such as NMR spectroscopy originated from the paramagnetic nature of iron. Magnesium is also a common element in the oxide glass compositions and its effect on the structure of boroaluminosilicate glasses were also investigated. Magnesium ion (Mg2+) has relatively higher cation field strength than other modifier cations and its structural role in oxide glasses is still under debate. Therefore, investigating the effects of cation field strength of modifier cations in light of MgO in boroaluminosilicate glasses is also an important goal of this dissertation. Overall, through detailed and systematic molecular dynamics simulations with effective interatomic potentials, the structures of iron and magnesium containing complex boroaluminosilicate glasses were obtained and used to interpret properties and their changes with glass composition for nuclear waste disposal and other applications.

To support the continuously increasing number of mobile telephone users around the world, mobile communication systems have become more advanced and sophisticated in their designs. As a result of the great success with the second generation mobile radio networks, deployment of the third and development of fourth generations, the demand for higher data rates to support available services, such as internet connection, video telephony and personal navigation systems, is ever growing. To be able to meet the requirements regarding bandwidth and number of users, enhancements of existing systems and introductions of conceptually new technologies and techniques have been researched and developed. Although new proposed technologies in theory provide increased network capacity, the backbone of a successful roll-out of a mobile telephone system is inevitably the planning of the network’s cellular structure. Hence, the fundamental aspect to a reliable cellular planning is the knowledge about the physical radio channel for wide sets of different propagation scenarios. Therefore, to study radio wave propagation in typical Australian environments, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Telecommunications Cooperative Research Centre (ATcrc) in collaboration developed a cellular code division multiple access (CDMA) pilot scanner. The pilot scanner measurement equipment enables for radio wave propagation measurements in available commercial CDMA mobile radio networks, which in Australia are usually deployed for extensive rural areas. Over time, the collected measurement data has been used to characterise many different types of mobile radio environments and some of the results are presented in this thesis. The thesis is divided into an introduction section and four parts based on peer-reviewed international research publications. The introduction section presents the reader with some relevant background on channel and propagation modelling. Also, the CDMA scanner measurement system that was developed in parallel with the research results founding this thesis is presented. The first part presents work on the evaluation and development of the different revisions of the Recommendation ITU-R P.1546 point-to-area radio wave propagation prediction model. In particular, the modified application of the terrain clearance angle (TCA) and the calculation method of the effective antenna height are scrutinized. In the second part, the correlation between the smallscale fading characteristics, described by the Ricean K-factor, and the vegetation density in the vicinity of the mobile receiving antenna is investigated. The third part presents an artificial neural network (ANN) based technique incorporated to predict path loss in rural macrocell environments. Obtained results, such as prediction accuracy and training time, are presented for different sized ANNs and different training approaches. Finally, the fourth part proposes an extension of the path loss ANN enabling the model to also predict small-scale fading characteristics.