Transport imaging is a SEM-based technique used to directly image the motion and recombination of charge in luminescent semiconductors, allowing for the extraction of transport parameters critical to device operation. In this thesis, transport imaging for 1D structures was initiated with work on sample preparation, modeling and initial characterization. One dimensional structures are being integrated into forefront electronics due to their inherent advantages in size, packing density and power consumption. In this work the one dimensional equation for steady state minority carrier recombination distribution solved for the Gaussian source is derived and results from numerical simulations are presented. The diameter of the SEM beam is determined experimentally allowing for accurate simulation parameters. Intensity and drift measurements on four batches of top-down wire structure samples, fabricated on a AlGaAs/GaAs/AlGaAs double heterostructure using a FIB, are presented. Significant decreases in luminescence in FIB exposed regions are reported. Spatial luminescence from single bottom-up GaN and ZnO nanowires deposited by metal initiated metal-organic CVD on Au and SiO2 substrates is imaged. CL spectra for GaN and ZnO, with peak intensities at 3.27 and 3.29 eV, are characterized. Finally, several suggestions for further research are offered including transport imaging on contacted bottom-up nanowires and a potential application of transport imaging to FIB damage characterization.

Astrocytes are the most abundant non-neuronal cells in vertebrate brains. Although Drosophila melanogaster has fewer astrocytic cells relative to neuronal and other glial cell populations, they, like vertebrate astrocytes, are located in synaptic regions, organized into exclusive, minimally-overlapping domains, and play developmental roles in synaptogenesis. But, do Drosophila astrocytes have parallel roles in the regulation of synaptic signaling? Preliminary electron microscopic (EM) data indicates that astrocytic processes are located at a greater distance, on average, from Drosophila synapses than they are from vertebrate synapses, thus raising questions about their capacity to alter synaptic signals. Do astrocytic cells and processes occupy stereotyped synaptic regions across repeating segmental structures and across individuals? In the studies presented here, we have addressed these questions directly in the ventral nerve cord (VNC) of the third-instar larva. We collected the first whole-cell patch-clamp recordings from Drosophila astrocytes. These indicate that intrinsic membrane properties, such as low membrane resistance, high capacitance, a hyperpolarized resting potential relative to neurons, a passive current-voltage relationship, coupling to other astrocytic cells, and an absence of voltage-gated currents, are shared between astrocytes of highly divergent species. Next, we optogenetically activated of a group of glutamatergic pre-motor neurons and showed that astrocytes respond with a glutamate transporter current that is mediated by Eaat1, and that acute, pharmacological and chronic, genetic blockades of this transporter have subsequent effects on the decay of post-synaptic motor neuron currents. Then, we used three-dimensional EM to locate the pre-motor glutamatergic neurons that were activated in the physiological study and measured the distance from each presynaptic site to the nearest astrocytic process. We found that these distances vary 100-fold even along a single neurite and that these structures are rarely in direct contact, but that no synapse is positioned greater than one micron from an astrocytic process. Thus, it is in this anatomical configuration that the regulation of post-synaptic currents by Eaat1 occurs. Finally, we generated a library of single, fluorescently-labeled astrocytes that were co-labeled with fiduciary landmarks, and used this library to compare the placement of astrocyte cell bodies and arbors across VNC segments and individuals. We found substantial variation in the gross shape, size, and territory covered by astrocytes, and conclude that their neuropil domains are not reliably stereotyped. Given the consistent placement of neuronal connectome elements, this indicates that signals of a specific synapse are not regulated by a designated astrocyte. Together, these findings reveal new functional parallels between Drosophila and vertebrate astrocytes. These findings argue for the relevance and applicability of mechanistic discovery in Drosophila astrocytes, and set the stage for further inquiry into the genetic determinants of astrocyte morphology and physiology.

The focus of this thesis was to gather and analyze micromorphological and petrographic data on soils at the archaeological site of Dmanisi in order to better understand the extent to which the deposition and alteration of the sediments has affected the preservation of artifacts and faunal remains. A major goal of this research was to test hypothesis related to why bone material is discovered in some strata and not in others. This research focuses on the application of micromorphology (supplemented with other methods) to the soils through the use of petrographic analysis of thin sections and scanning electron microscopy. These techniques complement previous field analyses by providing a quantitative assessment of individual strata through point counting and chemical mapping. The results of this research support the hypothesis that the sediments are predominantly mafic ashes, while showing that there is very little soil development in the strata. This suggests quick episodic burial in a relatively dry climate, confirming the hypothesis for a short time sequence in the strata. Additionally, differential weathering probably did not play a significant role in the differential abundance of bone remains among the strata at Dmanisi.

Magnetic resonance imaging (MRI) methods thought to assess myelin and axon integrity are improving the understanding of white matter diseases like multiple sclerosis (MS). This thesis improved the understanding of how microstructural tissue changes caused by various pathologies influence MRI metrics by developing and applying MRI methods in a longitudinal study using the cuprizone mouse model of MS. In vivo and ex vivo MRI measurments (T1 and T2 relaxometry, diffusion tensor imaging, and quantitative magnetization transfer imaging) were correlated with tissue measurements taken from electron microscopy images of control and cuprizone fed mice at weeks 2 and 3 of cuprizone feeding. Significant Spearman correlations included mean diffusivity vs. myelinated axon fraction (ρ=0.84), ex vivo T2 vs. myelinated axon fraction (ρ=0.68), and normalized T2-weighted signal vs. myelinated axon fraction (ρ =-0.80). Multiparametric MRI studies show promise in bridging the gap between damage detected in images and clinical status associated with MS. / May 2016

A dissertation submitted to the University of the Witwatersrand in fulfilment of the requirements for the degree of Master of Science in Engineering (Metallurgy & Materials) 2016 / The surfaces of AISI 316L stainless steel plate were laser alloyed with ruthenium powder as well as a mixture of ruthenium and nickel powders using a Nd:YAG laser set at fixed operating parameters. The microstructure, elemental composition, and corrosion characteristics of the alloyed zone were analysed using optical and scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and corrosion potential measurements. EDS analysis of the alloyed specimen showed that through the laser surface alloying, 2 mm surface layers with 12.5wt % Ru and 5.2wt% Ru were produced on an AISI 316L stainless steel. Similar microstructures which were dendritic and columnar grains, typical of weld beads under non-equilibrium cooling conditions were observed for all samples. Hardness profile measurements showed a significant increase from 160 HV for the substrate to a maximum of 247 HV for the alloyed layer. Using an Autolab potentiostat, the corrosion behaviour and resistance of the laser alloyed layers, substrate AISI 316L, and Hastelloy© C-276 were evaluated and compared in sulphuric acid solution of different concentration and temperatures. The Hastelloy© C-276, followed by the 12.5wt% Ru presented the most noble corrosion potential (Ecorr) and the lowest corrosion current density (icorr). However, in 60wt% H2SO4 and 40oC, the 5.22 wt% Ru alloys exhibited slightly better anticorrosive properties than 12.5wt% Ru. The observed corrosion potential, Ecorr, for untreated AISI 316L stainless steel sample in 40wt% sulphuric acid solution at 40oC was -277 mV. The 5.22 wt% Ru and 12.5wt% Ru alloyed stainless steel samples presented -240 mV, and 61 mV respectively in the same solution. Besides showing comparable performance to 5.2wt%Ru sample within specific short potential ranges, Hastelloy© C-276 was generally superior in all solutions. In addition it was found that the stability of the passive layer was improved with additions of Ru. Based on the developed costing equation the cost of 5 mm AISI 316L stainless steel plate with surface area (A = 1 m2) surface alloyed with 5.2wt% Ru to a depth of 2 mm using Nd: YAG laser is estimated at R15 989, and it is less than the cost of a Hastelloy© C-276 plate of similar size which is estimated at R19 900. As the material thickness increases, the cost benefit of laser surface treatment increases and vice versa. Reduction of the Ru additions to levels below 5.2wt% would improve cost competition without detracting from performance. / MT2017

The electron microscope is an ideal tool to prepare an electron into a specified quantum state, entangle that state with states in a specimen of interest, and measure the electron final state to indirectly gain information about the specimen. There currently exist excellent technologies to prepare both momentum eigenstates (transmission electron microscopy) and position eigenstates (scanning transmission electron microscopy) in a narrow band of energy eigenstates. Similarly, measurement of the momentum and position final states is straightforward with post-specimen lenses and pixelated detectors. Measurement of final energy eigenstates is possible with magnetic electron energy loss spectrometers. In 2010 and 2011, several groups independently showed that it was straightforward to prepare electrons into orbital angular momentum eigenstates. This disseratation represents my contributions to the toolset we have to control these eigenstates: preparation, application (interaction with specimen states), and measurement. My collaborators and I showed that phase diffraction gratings efficiently produce electron orbital angular momentum eigenstates; that control of orbital angular momentum can be used to probe chirality and local magnetic fields; and that there are several routes toward efficient measurement.

Quando se utilizam os instrumentos rotatórios, oscilatórios e os recíprocos, de NiTi (Níquel-Titânio), cortando ou raspando as paredes do conduto radicular, estes também sofrem desgastes em suas lâminas de corte. Tal ocorrência determina atritos cada vez maiores, proporcionais à perda do corte de suas lâminas, diminuindo a eficiência do instrumento, exigindo mais torques e força de penetração, aumentando ainda mais o atrito e o esforço que este sofre para desgastar a dentina, predispondo acidentes. O presente estudo avaliou o desgaste nas lâminas de corte das limas Reciproc, após 3,6 e 9 usos em canais de dentes naturais. Foram utilizados 180 dentes pré-molares inferiores e 40 instrumentos R40. Após o preparo dos canais os instrumentos foram incluídos em corpos de prova e submetidos a cortes transversais a 3 mm e 6 mm, contados a partir da ponta do instrumento. Nas imagens dessas secções transversais obtidas no MEV foi mesurada a distância entre as extremidades das lâminas de corte. O desgaste dos instrumentos foi estabelecido pela diferença entre as medidas das distâncias dos instrumentos sem uso com a média de cada instrumento, nos diferentes grupos experimentais. Observou-se diferença significante, quando comparados os grupos de 6 e 9 usos com o grupo controle. Já o grupo com 3 utilizações não apresentou diferença estatisticamente significante em relação ao grupo controle. As diferenças percentuais de desgaste a 3 mm após 3, 6 e 9 utilizações foram de 5,96%, 8,01% e 18,09%, respectivamente, em relação ao Grupo controle. As diferenças percentuais de desgaste a 6 mm, após 3, 6 e 9 utilizações foram de 2,32%, 9,54% e 21,00%, respectivamente, em relação ao Grupo controle. Conclui-se, assim, que ocorre desgaste significante das lâminas de corte dos instrumentos Reciproc, já a partir do terceiro uso reforçando a recomendação do fabricante em utilizar cada instrumento em molar e, então, descartá-lo. Palavras-chave: Microscopia eletrônica de varredura. Sistema Rotatório. / The fracture of nickel-titanium instrument, whose consequences can range from the difficulty of its removal until the absolute inaccessibility to the apical portion of the canal, remains a situation to be avoided in the safest way possible. When using the rotary instruments, and reciprocal oscillatory, NiTi, cutting or scraping the walls of the root canal, they also suffer wear in its cutting blades. Such an occurrence determines friction increasing in proportion to the loss of cutting blades, reducing the efficiency of the instrument, requiring higher torque and penetration force, further increasing friction and effort that suffers when wearing the dentin. Different rotational speeds to the long axis of the active part of the instrument are thus provoked in areas of high friction, favoring fractures, regardless of the type of movement, even if it is rotating or reciprocating. The present study sought to assess whether there is wear on cutting blades System Reciproc, since this system works through reciprocal movement within the root canal. For that, we will instrumentation in selected teeth with the kinematic system recommended by the manufacturer at zero, three, six and nine uses, corresponding to a molar tooth, two molar teeth and three molar teeth after 10 uses in each experimental group (zero , three, six and nine) according to the number of uses. The instruments are inserted into a quadrangular centralized device in the same position, and fixed in resin, which have been cut into their cross initial 3 mm and 6 mm initial these selected samples with the cross section of the system is brought to the SEM, and thus wear measured by measuring the radius of your cutting blades, and thus statistically analyzed. The results showed statistically significant differences after successive instrumentations.

Este trabalho apresenta o estudo e caracterização de dois complexos moleculares, hRXRálfadeltaAB e hemocianina de Acanthoscurria gomesiana, através de técnicas estruturais e biofísicas. O uso da técnica de crio-microscopia eletrônica para o estudo da hemocianina de Acanthoscurria gomesiana, resultou em um modelo estrutural com resolução de 14 angstron- pelo métodode Fourier Shell Correlation com critério de 1/2 bit. Neste limite de resolução, já é possível observar detalhes estruturais que o mostram como sendo comptível com outros modelos de hemocianinas. Com relação ao estudo de hRXRalfadeltaAB, mostrou-se, através das técnicas de cromatografia analítica de exclusão por tamanho, eletroforese de gel de poliacrilamida e SAXS, que a proteína pode se apresentar no estado dimérico em solução, mesmo na ausência do seu ligante, 9-cis-RA. Também foi estudado a associação de hRXRalfadeltaAB a elementos responsivos: DR1, DR4, F2 e PAL. Suas constantes de dissociação foram calculadas através da técnica de espectroscopia por anisotropia de fluorescência. Os resultados obtidos mostram maior afinidade por DR1 e DR2 e indicam uma origem entrópica para o processo de associação / This work describes characterization of two biomolecular complexes: hRXR deltaAB and a hemocyanin from Acanthoscurria gomesiana using structural and biophysical techniques. Application of cryo-electron microscopy to studies of a hemocyanin from Acanthoscurria gomesiana resulted in its structural model to 14Å resolution, which was calculated by Fourier Shell Correlation with cut-off of 1/2 bit. At this resolution limit one can observe structural details of the complex which are compatible with other hemocyanin models. With respect to hRXR deltaAB, we showed using analytic size exclusion chromatography, SDS PAGE and SAXS, that the protein is dimeric in solution even at the absence of its ligand, 9-cis-RA. hRXR deltaAB binding to the responsive elements of DNA, DR1, DR4, F2 and PAL was investigated and the binding constants to these responsive elements have been determined using fluorescence anisotropy technique. Our results show higher affinity of the receptor to DR1 and DR4 and indicate entropic mechanism of DNA binding

Os crustáceos do gênero Aegla, endêmicos da América do Sul, são os únicos decápodes anomuros que vivem em ambientes de água doce. A descoberta de fósseis em sedimentos marinhos deixou poucas dúvidas sobre a origem do grupo. Diversos estudos taxonômicos, morfológicos e de distribuição geográfica têm sido realizados sobre os eglídeos. Entretanto, informações filogenéticas baseadas na morfologia do grupo limitam-se, basicamente, aos trabalhos sobre a posição da família Aeglidae na infraordem Anomura e a um trabalho pioneiro, no qual os autores propuseram um cladograma para sete espécies com ocorrência no Chile. A partir de revisões taxonômicas e de uma análise cladística, com base em caracteres morfológicos, das espécies de Aegla que ocorrem nas bacias hidrográficas do Alto Paraná e Alto Uruguai, obteve-se: 1. O não-monofiletismo do clado Alto Paraná-Alto Uruguai; 2. Aegla leptochela relacionada filogeneticamente com outras espécies do Alto Ribeira; 3. Aegla marginata é uma espécie parafilética e forma um complexo com Aegla quilombola n. sp.; 4. Aegla franca e A. perobae são espécies irmãs; 5. Aegla lata, entre outras espécies, aparecem relacionadas com populações de diferentes bacias hidrográficas demonstrando tanto a falta de caracteres derivados dentro de Aeglidae, bem como a possibilidade de existirem mais complexos de diferentes espécies nessa família; 6. A invasão ao ambiente subterrâneo ocorreu mais de uma vez ao longo do tempo e espécies estigobiontes não são irmãs recíprocas exclusivas; 7. Aegla paulensis trata-se de um complexo de sete espécies distintas: Aegla paulensis s. str., A. rosanae, A. lancinhas, A. japi n. sp., A. jaragua n. sp., A. jundiai n. sp. e A. vanini n. sp. Além disso, análises em microscopia eletrônica de varredura dos tubos sexuais de machos de 39 espécies de Aegla, revelaram dois principais tipos, o longo estreito e o curto largo e, ainda, que cada espécie possui um conjunto de características específicas para essa estrutura, podendo, então, ser utilizada como caráter diagnóstico em descrições taxonômicas / The South American endemic genus Aegla represents the only anomuran decapod crustaceans strictly living in freshwaters. Marine fossil records left no doubts regarding the origin of the group. A number of studies on taxonomy, morphology and geographical distribution of aeglid have been carried out. Nevertheless, morphology based phylogenetic information about the group is limited to studies of the positioning of Aeglidae into the Anomuran infraorder and one pioneer work which presented a cladogram for seven species from Chile. Through cladistic analysis based on morphological characters of Aegla species occurring in the upper Paraná and upper Uruguay hydrographic basins the following results were obtained: 1. The non-monophyletic condition of the upper Paraná-upper Uruguay clade; 2. Aegla leptochela phylogenetically related to other species from Alto Ribeira; 3. Aegla marginata is paraphyletic, constituting a complex with Aegla quilombola n. sp.; 4. Aegla franca and A. perobae are sister species; 5. Aegla lata and other species were related with populations from different hydrographic basins, showing the lack of derived characters in Aeglidae and the possibility of existence of other species complexes in this family; 6. Invasion to the underground environments occurred more than once and the stygobiont species are not exclusive reciprocal sisters; 7. Aegla paulensis is a species complex encompassing seven species: Aegla paulensis s. str., A. rosanae, A. lancinhas, A. japi n. sp., A. jaragua n. sp., A. jundiai n. sp. e A. vanini n. sp.. In addition, scanning electron microscopy revealed two main types of sexual tubes (long and narrow; short and wide) in males from 39 Aegla species. Each species has a specific set of characters for this structure, hence indicating it can be used as diagnostic character in taxonomic descriptions

by Chan Lap-kong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 77-80). / ABSTRACT / ACKNOWLEDGEMENTS / LIST OF FIGURES / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Problems in Testing VLSI Circuits --- p.3 / Chapter 1.2.1 --- Test-cost-per-gate --- p.3 / Chapter 1.2.2 --- Tester Complexity --- p.3 / Chapter 1.3 --- Tester Based on Terminals Characteristics -Automatic Testing Equipment(ATE) --- p.4 / Chapter 1.4 --- Tester Based on Terminal and Internal Characteristics --- p.6 / Chapter 1.4.1 --- Mechanical Probing Method --- p.6 / Chapter 1.4.2 --- E-beam Probing Method --- p.7 / Chapter 1.5 --- Movitation for this Research --- p.7 / Chapter 1.6 --- Outline of the Remaining Chapters --- p.9 / Chapter 2. --- E-BEAM TESTER --- p.10 / Chapter 2.1 --- State-of-art of E-Beam Tester --- p.10 / Chapter 2.2 --- An Electron-optical Column of a SEM --- p.12 / Chapter 2.3 --- Beam Rastering Methods --- p.13 / Chapter 2.4 --- Voltage Contrast Phenomenon --- p.14 / Chapter 2.5 --- Configuration of an E-Beam Test System --- p.18 / Chapter 2.6 --- Advantages of an E-beam Tester --- p.20 / Chapter 3. --- BASIC PRINCIPLES --- p.21 / Chapter 3.1 --- Single-Stuck-At Fault Model --- p.21 / Chapter 3.2 --- Observability and Controllability --- p.24 / Chapter 3.3 --- Netlist Format --- p.25 / Chapter 3.4 --- Level --- p.27 / Chapter 3.5 --- Reconvergent Fanout --- p.28 / Chapter 4. --- CONVENTIONAL TEST GENERATION --- p.29 / Chapter 4.1 --- Conventional Automatic Test Generation for ATEs --- p.29 / Chapter 4.3 --- Conventional E-Beam Test Generation --- p.31 / Chapter 5. --- TEST AND PROBE POINT GENERATION --- p.32 / Chapter 5.1 --- Wafer Stage E-beam Testing --- p.32 / Chapter 5.2 --- Critical Paths Generation --- p.33 / Chapter 5.3 --- Assumptions of the Test and Probe Point Generation Algorithm --- p.35 / Chapter 5.4 --- Rules of the Test and Probe Point Generation Algorithm --- p.36 / Chapter 5.5 --- Probe Points Selection and Reduction --- p.38 / Chapter 5.6 --- Test and Probe Point Generation Algorithm --- p.40 / Chapter 5.7 --- Propagation and Justification at Fanout Site --- p.42 / Chapter 6. --- EXAMPLES --- p.45 / Chapter 6.1 --- Example of Test and Probe Point Generation for Circuit sc2 --- p.45 / Chapter 6.2 --- Example of Test and Probe Point Generation for Circuit sfc4 --- p.53 / Chapter 7. --- CONCLUSIONS --- p.61 / Chapter 7.1 --- Summary of Results --- p.61 / Chapter 7.2 --- Further Research --- p.63 / APPENDIX / Appendix A: Algorithm to Find Reconvergent Fanouts / Appendix B: Results of Test Generation for Circuit sc1 / Appendix C: Results of Test Generation for Circuit sc3 / REFERENCES --- p.77