The urinary bladder is a unique organ in that its normal function is storage and release of urine, and vasculature in its wall exhibits specialized features designed to accommodate changes in pressure with emptying and filling. Although we have previously described the fine details of the microvasculature of the urinary bladder of the rabbit and dog, information on the fine details of the microvasculature of the mouse bladder were deemed to be of value because of the increasing use of this species in developing genetic models for studying human disorders. The present study shows that many of the special features of the microvasculature of the mouse urinary bladder are similar to those described in the rabbit and dog, including vessel coiling, abundant collateral circulation, arterial sphincters, and a dense mucosal capillary plexus.

The urinary bladder is a unique organ in that its normal function is storage and release of urine, and vasculature in its wall exhibits specialized features designed to accommodate changes in pressure with emptying and filling. Although we have previously described the fine details of the microvasculature of the urinary bladder of the rabbit and dog, information on the fine details of the microvasculature of the mouse bladder were deemed to be of value because of the increasing use of this species in developing genetic models for studying human disorders. The present study shows that many of the special features of the microvasculature of the mouse urinary bladder are similar to those described in the rabbit and dog, including vessel coiling, abundant collateral circulation, arterial sphincters, and a dense mucosal capillary plexus.

The cast products Mg–Sn based alloys are promising candidates for automobile industries, since they provide a cheap yet thermally stable alternative to existing alloys. One drawback of the Mg–Sn based alloys is their insufficient hardness. The hardenability can be improved by engineering the microstructure through additions of Zn to the base alloy and selective aging conditions. Therefore, detailed knowledge about the microstructural characteristics and the role of Zn to promote precipitation hardening is essential for age hardenable Mg-based alloys. In this work, microstructural investigation of the Mg–1.4Sn–1.3Zn–0.1Mn (at.%) precipitation system was performed using TEM. The chemical composition of the precipitates was analyzed using EDS. APT was employed to obtain precise chemical information on the distribution of Zn in the microstructure. It was found from microstructural studies that different precipitates with varying sizes and phases were present; lath-shaped precipitates of the Mg2Sn phase have an incoherent interface with the matrix, unlike the lath-shaped MgZn2 precipitates. Furthermore, nano-sized precipitates dispersed in the microstructure with short-lath morphology can either be enriched with Sn or Zn. On the other hand, APT analysis revealed the strong repulsion between Sn and Zn atoms in a portion of the analysis volume. However, larger reconstruction volume required to identify the role of Zn is still limited to the optimization of specimen preparation.

abstract: Non-stoichiometric oxides play a critical role in many catalytic, energy, and sensing technologies, providing the ability to reversibly exchange oxygen with the ambient environment through the creation and annihilation of surface oxygen vacancies. Oxygen exchange at the surfaces of these materials is strongly influenced by atomic structure, which varies significantly across nanoparticle surfaces. The studies presented herein elucidate the relationship between surface structure behaviors and oxygen exchange reactions on ceria (CeO2) catalyst materials. In situ aberration-corrected transmission electron microscopy (AC-TEM) techniques were developed and employed to correlate dynamic atomic-level structural heterogeneities to local oxygen vacancy activity. A model Ni/CeO2 catalyst was used to probe the role of a ceria support during hydrocarbon reforming reactions, and it was revealed that carbon formation was inhibited on Ni metal nanoparticles due to the removal of lattice oxygen from the ceria support and subsequent oxidation of adsorbed decomposed hydrocarbon products. Atomic resolution observations of surface oxygen vacancy creation and annihilation were performed on CeO2 nanoparticle surfaces using a novel time-resolved in situ AC-TEM approach. Cation displacements were found to be related to oxygen vacancy creation and annihilation, and the most reactive surface oxygen sites were identified by monitoring the frequency of cation displacements. In addition, the dynamic evolution of CeO2 surface structures was characterized with high temporal resolution AC-TEM imaging, which resulted in atomic column positions and occupancies to be determined with a combination of spatial precision and temporal resolution that had not previously been achieved. As a result, local lattice expansions and contractions were observed on ceria surfaces, which were likely related to cyclic oxygen vacancy activity. Finally, local strain fields on CeO2 surfaces were quantified, and it was determined that local strain enhanced the ability of a surface site to create oxygen vacancies. Through the characterization of dynamic surface structures with advanced AC-TEM techniques, an improvement in the fundamental understanding of how ceria surfaces influence and control oxygen exchange reactions was obtained. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2019

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19379号 / 農博第2149号 / 新制||農||1037(附属図書館) / 学位論文||H28||N4959(農学部図書室) / 32393 / 新制||農||1037 / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 髙部 圭司, 教授 髙野 俊幸, 教授 杉山 淳司 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

No description available.

Two-dimensional (2D) materials have properties that are often different from their three-dimensional (3D) bulk form. Many of these materials are stable at ambient conditions, which allows them to be integrated with other 2D- or 3D-materials to form heterostructures. Integration of various dimensional materials attains unique electrical and optical properties that aid in developing novel electronic devices. The interface of the heterogeneous integration of these films can exhibit a weak van der Waals-like bonding. In this thesis, an advanced characterization (from atomic to millimeter resolution) of various dimensional materials with weakly bonded interfaces is developed and employed to understand their behavior at scale. First, a large-area single-crystal cadmium telluride thin film is grown incommensurately and strain-free to a sapphire substrate despite a significant 3.7% lattice mismatch. The film remarkably delaminates as a bulk single crystal film due to an atomically thin tellurium that spontaneously forms at the interface. Aberration-corrected electron microscopy and spectroscopy reveal both the van der Waals-like structure and bonding at the film/substrate interface. Second, a large-area atomically thin gallium is intercalated at the interface of epitaxial graphene. Correlative microscopy workflows are applied to understand the thickness uniformity and area coverage of the 2D–gallium over few millimeters of the sample. Utilizing multiple correlative methods, SEM image contrast is found to be directly related to the presence of the intercalated gallium. The origin of the SEM contrast is investigated as a function of the surface potential. Then, the heterostructure characterization is scaled up over a few square millimeter areas by segmenting SEM images, each acquired with nanometer-scale resolution. Additionally, transmission electron microscopy is applied to investigate the interface of gallium–SiC, the gallium air–stability, and the role of the substrate on the heteroepitaxial growth of 2D–gallium, which charts a path for further development of these materials. / Thesis / Doctor of Philosophy (PhD)

No description available.

Masters of Science / The infants of women who smoke during pregnancy have a lower birth mass than those born of women who abstain. Animal studies reveal that reduced growth due to maternal nicotine exposure during gestation is accompanied by lung hypoplasia. Biochemical analysis suggests that these lungs contain more cells which implies that lung damage occurs. In this study we examined the in vivo effects of maternal nicotine exposure (lmg/Kg/day), the equivalent of 32 cigarettes per day, on the following parameters of fetal and neonatal Wistar rat lung:(i) the content and distribution of glycogen in fetal and neonatal lung (ii) the status of connective tissue in neonatal lung (iii) the cell composition of the alveoli in neonatal lung. Fetal rat lungs of ages 17, 18, 19 and 20 days and neonatal lungs of 1, 7, 14 and 21 day old pups were used. Light microscope techniques and special stains were used to investigate glycogen, connective tissue, macrophage numbers and morphological status of the lungs. Fetal rat lungs of ages 17, 18, 19 and 20 days and neonatal lungs of 1, 7, 14 and 21 day old pups were used. Light microscope techniques and special stains were used to investigate glycogen, connective tissue, macrophage numbers and morphological status of the lungs. Transmission electron microscope (TEM) techniques were employed to investigate the characteristics and composition of the alveolus The results show clearly that maternal nicotine exposure elevates pulmonary alveolar macrophage numbers'(PAM's) and lung glycogen levels. The quantity of elastic fibres in 1 day old neonates was significantly reduced but no changes in the quantity of reticulin and collagen fibres was observed. As a result of this change in connective tissue status, emphysema-like lesions and alveolar collapse was evident in the lungs of nicotine-exposed pups. TEM investigations revealed that changes to the composition of alveoli occurred. These included increased numbers of type II pneumocytes with high numbers of lamellar bodies with degenerative changes. Thickening of the blood-air barrier was also observed. The effect of maternal nicotine exposure has been documented in this study. However, it has not been possible to pinpoint the mechanisms involved but explanations have been proposed. Further research is required to elucidate the mechanisms by which nicotine produces these effects. Information thus obtained could help prevent the harmful effects to the fetus and neonate caused by smoking during pregnancy.

InGaAs quantum dot chains were grown with a low-temperature variation of the Stranski-Krastanov method, the conventional epitaxial method. This new method seeks to reduce indium segregation and intermixing in addition to giving greater control in the growth process. We used photoluminescence spectroscopy techniques to characterize the quality and electronic structure of these samples. We have recently used a transmission electron microscope to show how the quantum dots vary with annealing temperature. Some questions relating to the morphology of the samples cannot be answered by photoluminescence spectroscopy alone. Using transmission electron microscopy, we verified flattening of the quantum dots with annealing temperature and resolved the chemical composition with cross-section cuts and plan view cuts.