This thesis explored, as its major aim, the crystallographic and compositional characteristics of a particular type of peridotitic garnet associated with kimberlite. This garnet has a highly sinusoidal rare-earth element (REE) pattern as its distinguishing feature. Before the main research question could be addressed, a technique had to be developed that enabled the rapid and straight-forward acquisition of a full profile digital X-ray diffractogram from a single sub-milligram crystal fragment. After extensive experimentation and testing, successful development and realization of a method that is capable of producing such data was achieved. The next step of this research project was to empirically investigate and assess the crystal lattice strain model (CLSM) of Blundy and Wood (1994). Careful analyses of the REE present in a suite of clinopyroxenes were compared to the crystal structure data given from the XRD technique outlined above. Clinopyroxene is particularly useful for such an assessment because the radius of the M2 site in this mineral is between the largest and smallest REE, making the distribution of REE particularly sensitive to variation of the M2 site, which in turn is a direct consequence of the overall pyroxene structure. Subsequent to illustrating that XRD data could be collected on such small material and the XRD data and structural data given from the CLSM correlate strongly, peridotitic garnets with sinusoidal REE patters were investigated. The conclusions drawn in the first two contributions – namely that it was possible to collect accurate and precise XRD data from sub-milligram specimens and that the crystal structure and REE distribution were directly related – were imperative for the deduction of conclusions in the final, major research question. The XRD analysis of many garnets with and without sinusoidal REE patterns showed the presence of a small amount of an additional phase in some of these garnets. While this phase (2 out of 3 peaks indexed as possibly orthorhombic perovskite) is not present in sufficient quantities to give rise to such a strong sinusoidal segment in the garnet REE pattern, it prompted the critical step forward in formulating a working hypothesis for the otherwise inexplicable REE patterns. Specifically, I posit that many of the sinusoidal garnets may originally have precipitated as a very high pressure phase (in the mantle transition zone or deeper) that subsequently underwent a subsolidus isochemical transformation to garnet. Possible original precursor mineralogy is a combination of two perovskites or a perovskite + iv garnet assemblage. Theoretical calculation using experimental partition coefficients demonstrated that a mixture of Ca-perovskite (CaPv) and Mg-perovskite (MgPv) REE patterns in the approximate proportions of 10% CaPv and 90% MgPv produce a REE diagram that is strikingly similar to those observed in sinusoidal single phase garnet. It has been shown experimentally that with increasing depth in the mantle, garnet plus a progressively increasing CaPv component is the stable mineral assemblage. Initial precipitation of two perovskites or CaPv + garnet as cumulates from a deep magma ocean would preserve the REE distribution of these minerals. Subsequent exhumation of such an assemblage would result in the retrogressive subsolidus phase transformation to a mineral stable at conditions of T and P of the shallow mantle environment, i.e. garnet, while retaining the REE pattern of the initial precipitate mineral assemblage. While this working hypothesis will require many more tests, its proposal may have significant implications for the mantle structure.

Heterogeneous Templated Grain Growth (HTGG) is a developing method to fabricate designedcrystallographic textures of polycrystalline materials. Designed crystallographic texturesare important for enhancing desired material properties for specific applications. Four steps toHTGG have been identified: fabricating single crystal seeds, aligning seeds embedded into a powdermatrix, compacting seeds in the powder matrix, and promoting templating through sintering.Experimental research was performed on processing parameters, powder particle size and compaction,to indicate template coarsening trends during sintering. The results demonstrated thatlarger powder particles were influenced faster by the seeds crystallographic orientations comparedto smaller particles. The local effects of porosity on the seed and powder interface were analyzedand this powder size effect was explained in the context of the theory of Zener pinning.

<p> The crystal structures of four compounds of the type (Zn,Cd,Mn)3(PO4)2 have been determined by X-ray diffraction methods. These structures are the high temperature (β) phase of Zn3(PO4)2, the related structures of β1-Mn3(PO4)2 and β1-Cd3(PO4)2, and the structure of a member of a solid solution of median composition Zn2Cd(PO4)2 which is similar in structure to the mineral graftonite. The orthophosphates of the small divalent metal ions have been separated into four structure classes and the stability of each of these classes is discussed in terms of cation concentration and the types of cation sites which exist in these structures. The correlation of a host crystal structure and the luminescence of Mn++ when this ion is added as an impurity is also discussed.</p> / Thesis / Doctor of Philosophy (PhD)

Thesis advisor: Yvette D. Kuiper / Crystallographic Preferred Orientations (CPO) are common in deformed rocks, and usually result from crystal plastic deformation by dislocation creep. Whether deformation mechanisms that occur at lower differential stress and lower temperature than dislocation creep, such as Dissolution-Precipitation Creep (DPC), may result in the development of a CPO is less certain. DPC, a process also known as pressure-solution creep or dissolution creep, has caused substantial removal and reprecipitation of quartz within the Purgatory Conglomerate of Rhode Island. The conglomerate is exposed within the southeastern region of the Pennsylvanian Narragansett basin and experienced folding during the Alleghanian orogeny. Strain within the southeastern portion of the Narragansett basin increases from west to east and is associated with a metamorphic gradient from very low grade greenschist facies in the west to the lower biotite zone in the east. Within the Pugatory Conglomerate DPC has led to the dissolution of quartz along cobble surfaces perpendicular to the shortening direction, and to be precipitated as overgrowths at the ends of the cobbles (strain shadows), parallel to the maximum extension direction. This offers a unique opportunity to study the effects of dissolution and precipitation separately, because the quartz grains within the cobbles experienced dissolution only, while precipitation occurred in the strain shadows. Cathodoluminescence (CL) analysis was conducted on regions within the strain shadow in order to determine what amount of the quartz was formed authigenically. The results suggest that quartz-rich areas of the strain shadow were comprised primarily of authigenic quartz and formed channels or wedges. Electron Backscatter Diffraction (EBSD) analysis was used to test whether quartz dissolution processes within the cobbles and/or quartz precipitation within the strain shadows resulted in CPO development. Quartz grain c-axis orientations of various domains within the cobbles and strain shadows indicate that CPO patterns are absent in both domains of dissolution and of precipitation irrespective of the degree of strain or metamorphic grade. The existence of discrete mica selvages along the cobble margins suggests that quartz dissolution only occurred along the cobble surface and did not affect the grains, or result in a CPO, within the cobble's interior. Quartz precipitation within the strain shadows did not result in a CPO, probably because the strain shadows are truly localized regions of low strain with little to no differential stress, allowing quartz grain growth in random orientations. / Thesis (MS) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

Un procédé de traitement de surface avant projection plasma d’alumine, développé pour des substrats en acier C40E, a été étendu à des substrats en nickel. Afin de remplacer l’étape de sablage, une pré-oxydation sous CO2 a été réalisée, ayant pour objectif de créer une couche de protoxyde de nickel avec une épaisseur contrôlée. Cette couche d’oxyde permet d’augmenter significativement l’adhérence du dépôt d’alumine sur le substrat nickel. La formation de cette couche de protoxyde a été suivie par une étude de la cinétique d’oxydation. L'observation des interfaces alumine/nickel au MET a mis en évidence que des relations d'hétéroépitaxie entre le monoxyde de nickel et l’alumine sont à l’origine d'une adhésion chimique forte du dépôt. Cette forte adhérence (environ 105 MPa) a pu être quantifiée à l’aide d’un test de traction modifié (ASTM C633-13), dont le développement a été mis en place pour des échantillons en acier C40E pré-oxydés. / A surface treatment process, developed for C40E steel substrates before alumina plasma spraying, has been extended to nickel substrates. As an alternative to sand blasting, nickel substrates were pre-oxidized under CO2, to create a protoxide nickel layer of controlled thickness. This oxide layer significantly increases the alumina coating adherence on nickel substrates. A kinetic study of nickel oxidation under CO2has been realized, in order to better control the nickel preoxidation. TEM investigations of alumina/nickel interfaces showed a heteroepitaxial growth of alumina on nickel monoxide, which justify the strong alumina coatings adhesion. This high adherence (around 105 MPa) has been measured using a modified tensile test (ASTM C633-13), specifically set up for pre-oxidized steel C40E substrates.

Since 2011, the Institute of Petrology and Structural Geology, Charles University in Prague, worked with CIP - Computer Integrated Polarization microscopy as fast, inexpensive measurement of c-axis orientation of uniaxial minerals, mostly quartz in high definition. CIP method is developed from the early nineties in Switzerland (Heilbronner & Pauli 1993) and later in many other workplaces. The aim of this work was testing and calibration of optical and camera equipment to verify the accuracy and reliability of data obtained. Served as an independent measurement of EBSD (Electron Backscatter Diffraction) data obtained from the same part of the studied thinsections. The data obtained were analyzed by quantitative analysis of microstructures (PolyLX - MATLABTM toolbox; Lexa 2003). The samples used for testing the methodology mentioned were taken on the profile of Hvězdná and Zdobnice near Rokytnice in the Eagle Mountains by contact orlica-snieznik complex and its mantle. Field studies showed the existence of west dipping shear zone along the said contact and deformed orthogneiss show a macroscopic superposition of several deformation events. The resulting frequency histograms similarities and differences of angles c-axes and angles misorientace grains have a high consensus in the azimuthal criterion, axes...

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In this dissertation, we design and develop a novel direction-of-arrival (DOA) finding system. We investigate the problems of DOA finding using canonical and crystallographic antenna array structures, develop a novel integrated algorithm consisting of combined multiple signal classification (MUSIC) algorithm, Kalman Filter and Kent Distribution to improve the accuracy and robustness of DOA estimation, design and conduct the real time testing of DOA and verify the accuracy and efficiency of the designed DOA finding system. We first examine the ability of mitigating the aliasing and enhancing the DOA estimation of different antenna structures, including canonical and crystallographic antenna structures. Our results show that the crystallographic antenna array has a better performance of overcoming aliasing in many circumstances, improving the estimation accuracy and covering more spatial region of DOA estimation. Then we propose a novel integrated algorithm to achieve a more robust DOA finding with higher accuracy. We show that the DOA estimation using MUSIC algorithm can be strongly influenced by the size, spacing and distributions of elements of the receiving antenna array as well as noise and mutual coupling. We propose a combined MUSIC and Kalman Filter algorithm to reduce the noise and enhance the robustness of the DOA estimation. Further more we map the DOA estimation onto the sphere and use Kent distribution to characterize the spread of DOA points on the sphere. We calculate the mean direction of Kent distribution to present the DOA vector, which further improves the accuracy of DOA finding. At last, we design and build a multi-channel and real time automated measurement system to validate the proposed antenna structure and integrated algorithms. Our testing results indicate that the designed DOA finding system can work practically and efficiently, with higher accuracy and stronger robustness.

Conversion of 1-Methylpentacyclo[5.4.0.0²⋅⁶.0³⋅¹⁰.0⁵⋅⁹]undecane- 8,11-dione into the corresponding mono(ethylene ketal) followed by Wolff-Kishner reduction resulted in a mixture of two isomers (i.e., 1- and 7-methyl-8-[2',-(1',3',dioxolano)]pentacyclo[5.4.0.0²⋅⁶.0³⋅¹⁰.0⁵⋅⁹] undecane. Hydrolysis of each isomer in turn resulted in 1- and 7- methyl pentacyclo[5.4.0.0²⋅⁶.0³⋅¹⁰.0⁵⋅⁹ ]undecan-8-ones (i.e.,"methylated PCU-8-ones"), respectively. "Titanium-promoted reductive dimerization of each of the methylated pentacycloundecane (PCU)-8-ones afforded mixtures of "methylated PCU alkene dimers". Individual isomers have been isolated from these mixtures via column chromatography by using silver nitrate impregnated silica gel as adsorbent followed by fractional recrystallizations of individual chromatography fractions. Structures of three isomerically pure methylated PCU alkene dimers (C₂₄H₂₈) have been established unequivocally by application of single crystal X-ray crystallographic methods.

Crystallographic complex reflection groups are generated by reflections about affine hyperplanes in complex space and stabilize a full rank lattice. These analogs of affine Weyl groups have infinite order and were classified by V.L. Popov in 1982. The classical Braid theorem (first established by E. Artin and E. Brieskorn) asserts that the Artin group of a reflection group (finite or affine Weyl) gives the fundamental group of regular orbits. In other words, the fundamental group of the space with reflecting hyperplanes removed has a presentation mimicking that of the Coxeter presentation; one need only remove relations giving generators finite order. N.V Dung used a semi-cell construction to prove the Braid theorem for affine Weyl groups. Malle conjectured that the Braid theorem holds for all crystallographic complex reflection groups after constructing Coxeter-like reflection presentations. We show how to extend Dung's ideas to crystallographic complex reflection groups and then extend the Braid theorem to some groups in the infinite family [G(r,p,n)]. The proof requires a new classification of crystallographic groups in the infinite family that fail the Steinberg theorem.