Histotripsy is a non-thermal, non-invasive, focused ultrasound ablation method that uses acoustic cavitation to mechanically break down tissues [1-8]. Histotripsy is heavily dependent on the mechanical properties of the tissue, allowing it to mechanically ablate tissues of lower mechanical stiffness while preserving the stiffer critical structures [15]. However, the mechanical properties of clinically relevant abdominal tissues and critical structures have not yet been adequately quantified under uniform testing parameters. Previous studies have tested and modeled the tissue selectivity of histotripsy, but these studies have been limited by the lack of mechanical property data available for these tissue types. In addition, there remains a need for additional experimental studies directly comparing the differential treatment doses required to induce histotripsy tissue damage in intra-abdominal tissue types. This thesis investigates the mechanical properties of intra-abdominal tissues under uniaxial tension, the effect of histotripsy treatment dose on intra-abdominal soft tissues and critical structures, and the potential of inducing damage to critical structures along the acoustic path pre-focal to the targeted histotripsy treatment. Results show that there are significant differences between the parenchymal tissues (liver, kidney) and the critical structure (stomach, gallbladder, small intestine, ducts, and vessels) elastic modulus, yield stress, yield strain, post-yield strain, energy to yield, and maximum stress and strain at yield. In general, histology analysis from the histotripsy experiments showed that there was an increase in tissue damage with increasing histotripsy pulses/point for all tissues. Critical structures with higher mechanical strength were more resistant to ablation compared to tissues with lower mechanical strength. Pre-focal studies showed damage to gallbladder and small intestine only in cases in which pre-focal cavitation was observed, while no damage occurred in skin and stomach for any samples treated at varying distances from the bubble cloud. Overall, this work improves our understanding of tissue selectivity of histotripsy and provides mechanical properties measurements for clinically relevant tissues that can be used to improve predictive models of tissue-selective histotripsy treatments. This work can be used in the planning of histotripsy treatments to establish proper margins of safety for treating intra-abdominal tumors. / Master of Science / Histotripsy is a non-invasive cancer treatment that mechanically breaks down tissues by rapidly forming and bursting bubbles within the tumor [1-8]. Histotripsy is heavily dependent on the mechanical properties of the tissue, allowing it to destroy weaker tissues while preserving the stiffer tissues in the surrounding area [15]. The mechanical properties of clinically relevant intra-abdominal tissues have not been quantified under uniform testing parameters. Previous studies have tested and modeled the tissue selectivity of histotripsy, but these studies have been limited by the mechanical property data available. This thesis investigates the mechanical properties of intra-abdominal tissues under tension, the effect of histotripsy treatment dose on intra-abdominal tissue damage, and the damage to critical structures from histotripsy treatment at varying distances from the tissue. Results show that there are significant differences between the liver and kidney mechanical stiffness and strength compared to the other tissues. In general, histology analysis showed that there is an increase in tissue damage with increasing histotripsy dose. Tissues with higher mechanical strength were more resistant to damage at lower doses compared to tissues with lower mechanical strength. Histotripsy damage to critical structures that are along the beam path, set distances in front of the focal point of the cavitation bubble cloud was studied. This study showed damage to gallbladder and small intestine only in cases in which pre-focal cavitation, cavitation bubbles that are not within the focal point of the cloud but are in contact with the tissue, was observed, while no damage occurred in skin and stomach for any samples treated at varying distances from the bubble cloud. Overall, this work improves our understanding of tissue selectivity of histotripsy and provides mechanical properties for clinically relevant tissues that can be used to improve predictive models of tissue-selective histotripsy treatments. This work can be used in the planning of histotripsy treatments to establish proper margins of safety for treating intra-abdominal tumors.

In the lowlands of Southeast Asia, the island of Borneo faces rates of primary forest degradation and deforestation exceeding tropical forests across the globe. For critically endangered Bornean orangutans (Pongo pygmaeus wurmbii), habitat loss greatly threatens the long-term stability of remaining populations. With rates of forest loss and fragmentation on the rise, it is critical we explore the role of anthropogenically-modified landscapes in conserving wild orangutans. Here I investigate orangutan habitat quality within Gunung Palung National Park (GPNP), in Borneo, Indonesia, focusing on the conservation value of a secondary forest with a history of logging. Orangutans in GPNP flexibly inhabit a range of habitats within the primary forest, suggesting the nearby secondary forest could provide population support if sufficient resources are available. Monthly phenology and focal follow data were utilized to assess feeding behavior in relation to food availability. While overall fruit availability was consistently higher in the primary forest, the abundance and fruiting frequency of preferred foods were significantly greater in the secondary forest. The fruiting pattern of preferred resources also significantly predicted orangutan presence. These findings suggest post-disturbance landscapes, if safeguarded and able to become secondary forest, could be vital areas of refuge for Bornean orangutans across an ever-changing landscape.

The selectivity mechanism of the UV-light activated metal oxide semiconductor (MOS) gas sensors was studied. A reaction model based on two competing redox processes was presented to solve the selectivity problem. A concept named dynamic equilibrium of adsorbed oxygen concentration was brought about in this model and two reaction responses were discussed: (1) when most of the MOS surface is adsorbed with oxygen, the resistance of the MOS gas sensor will decrease upon the injection of reducing agents (RAs); (2) when most of the MOS surface is not adsorbed with oxygen, the resistance of the MOS gas sensor will increase upon the injection of RAs. Finally, experiments were conducted on ZnO MOS gas sensors to prove the proposed hypothesis of the reaction mechanism. / Thesis / Master of Applied Science (MASc)

cAMP receptors contain highly conserved cAMP binding pockets, in part responsible for allosteric activation, yet CBDs exhibit a wide array of cAMP binding affinities. While several cAMP:CBD crystallographic structures have been solved, they are insufficient to explain differences in cAMP:CBD affinities. We hypothesize that it is the position of the apo autoinhibitory equilibrium and/or a change in the state-specific association constants of the active and inactive CBD forms that are primarily responsible for modulating ~1000-fold difference in cAMP affinities. Interestingly, we discovered that PKARIα and HCN2 have comparable state-specific association constants, suggesting that the position of the apo autoinhibitory equilibrium is primarily responsible for the large difference in observed cAMP affinities in these systems. In addition, the individual components of the cAMP binding pocket (i.e. BBR, PBC, and lid) show functional variability across different CBDs. In RIα, both the BBR and lid are dispensable for high affinity cAMP binding, leaving the PBC as the key determinant of cAMP affinity. Interestingly, in addition the PBC:cAMP contact side-chains, non-contact side-chains are also important in modulating cAMP affinity (ie. L201 and Y205). Further dissection of the contributions arising from the apo pre-equilibrium and the cAMP binding pockets is required to better understand cAMP affinity and selectivity. / Thesis / Master of Science (MSc)

The progress in fuel cell technology has resulted in an increased interest towards hydrogen fuel. Consequently, water gas shift reaction has found a renewed significance. Even though iron- and copper-based catalysts have been used for water gas shift reaction for decades, the catalysts are not strong enough to bring carbon monoxide concentration to a level tolerable for a fuel cell working at low temperatures. This study is focused on hydrogen production from water gas shift reaction using a nickel catalyst. Literature review revealed that nickel is one of the promising catalysts for water gas shift reaction. A thermodynamic analysis proved that exothermic water gas shift reaction is thermodynamically favorable at low temperatures but kinetically limited, and vice versa at higher temperatures. Initial experiments using 12 catalysts supported over monolith alumina revealed that nickel supported on ceria-promoted monolith alumina (Ni/CeO2-Al2O3) performed best, especially at 500oC. At this temperature and steam flowrates of 0.1-0.5 ml/min, the nickel catalyst had an activity of 94-99%, H2 yield of 55-61 vol.%, and H2 selectivity of 77-99%. A second set of experiments examined nine nickel based catalysts using different supports (mostly in powder form) which also demonstrated that Ni/CeO2-Al2O3 is the most promising catalyst for high temperature (450oC) water gas shift reaction. When nickel loading was varied from 1 to 8% (w/w), it was apparent that the catalyst performance increased with the nickel loading. Powder alumina resulted in better catalysis than monolith alumina. In this experiment, it was evident that the presence of minor amounts (1% (w/w) of the nickel loading) of a dopant material that included cobalt, chromium, molybdenum, or ruthenium affected the catalytic activity of the primary catalyst. The addition of cobalt or chromium resulted in positive effect on the performance of Ni/CeO2-Al2O3 catalyst. There was no appreciable effect due to the addition of ruthenium, and there was negative effect owing to the presence of molybdenum. Undoped, cobalt-doped, or chromium-doped Ni/CeO2-Al2O3 catalyst performed much better for water gas shift reaction at 450oC than that of a commercial (control) catalyst. A kinetic study revealed that the activation energy of water gas shift reaction over Ni/CeO2-Al2O3 was to be 104.5 kJ/mol.

No description available.

<p>The transport of ammonia by various tissues throughout the body is of fundamental importance for nitrogen excretion in invertebrates, yet sites and mechanisms of ammonia transport are not presently well understood. In this thesis a novel ammonium-selective microelectrode was developed using the ionophore TD19C6, which is approximately 3800-fold more selective for NH₄⁺ than Na⁺ compared with the 100-fold difference of nonactin used in previous microelectrodes. We investigated the accuracy of the ammonium microelectrode in solutions simulating <em>Drosophila</em> haemolymph (25 mM K⁺) and secreted fluid (120 mM K⁺). In haemolymph-like solutions, ammonium could be measured down to about 1 mM, with an error of 0.5 mM, while in secreted fluid-like conditions ammonium could be determined to within 0.3 mM down to a level of 1 mM NH₄⁺ in the presence of 100 to 140 mM K⁺. These results suggested that the ammonium microelectrode could be used to measure ammonium in the presence of physiological levels of potassium, unlike previous studies. We also quantified ammonium secretion by the Malpighian (renal) tubules of larvae. Ammonium concentrations of secreted fluid were consistently equivalent to or above ammonium concentrations of bathing salines. With a lumen-positive transepithelial potential, these results suggested an active secretory mechanism for ammonia transport. Under conditions of low K⁺ concentrations, the ability of the tubules to concentrate ammonium in secreted fluid was significantly enhanced, indicating some level of competition between NH₄⁺ and K⁺ for common transporters. The new ammonium-selective microelectrode is sufficiently sensitive to detect ammonium at the picomol level.</p> / Master of Science (MSc)

京都大学 / 新制・課程博士 / 博士(薬科学) / 甲第23138号 / 薬科博第137号 / 新制||薬科||15(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 川端 猛夫, 教授 高須 清誠, 教授 大野 浩章 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

Feeding selectivity by the rainbow mussel (Villosa iris) was examined for three age groups; 2-3 days old, 50-53 days old, and 3-6 years old. The mussels were fed an algal diet consisting of Scenedesmus quadricauda (22.3 - 44.5 μm), Nannochloropsis oculata (2.8 – 8.1 μm), and Selenastrum capricornutum (3.6 – 8.5 μm) in equal cell densities. The change in relative abundance of each algal species within feeding chambers over a 5 hr feeding trial was used to discern selectivity. At the conclusion of the feeding trials, the gut contents of mussels were analyzed for preferential ingestion. The mussels selected for N. oculata and S. capricornutum over S. quadricauda (p < 0.05). This may be an indication of particle size-dependent selection. Feeding trials also suggest that selectivity by the rainbow mussel does not change with age. Gut content analyses showed a preferential ingestion of algae, in the sequence N. oculata, S. capricornutum, then S. quadricauda. The suitability of two algal diets, S. quadricauda and N. oculata, for rearing captive juveniles of V. iris in 145-L recirculating culture systems was compared. Juveniles were fed their assigned diet at a density rate of approximately 30,000 cells/ml for 42 days, and sampled weekly for percent survival and shell length. Regardless of diet, juvenile survival decreased rapidly after 21 days, and growth did not exceed approximately 450 μm. High mortality rates and slow growth of juveniles was likely due to inadequate diets. Juveniles that were fed S. quadricauda lacked chlorophyll coloration in their guts, indicating that the juveniles did not ingest this species of algae. Colonies of S. quadricauda were likely too large for the juveniles to ingest. The gut content of juveniles fed N. oculata showed chlorophyll coloration, indicating that the juveniles ingested this species, but N. oculata may have been difficult for the juveniles to assimilate. Under the culture conditions provided, survival and growth did not compare favorably to those of other studies with V. iris. Newly metamorphosed juveniles of V. iris were reared in 145-L recirculating culture systems containing sediment (< 600 μm) of two depths, 5 mm and 15 mm. Mussels were fed a bi-algal diet of Nannochloropsis oculata and Neochloris oleoabundans. Survival differed significantly between treatments (p=0.04), and was higher for juveniles reared in 5 mm of sediment over a 40-day period. Growth was not significantly different between treatments. After 40 days, juveniles achieved a mean length of approximately 578 μm in both treatments. Survival and growth of juveniles compared favorably to those of other culture studies using juveniles of V. iris. A shallow layer of sediment is recommended for the culture of juvenile mussels. / Master of Science

In this study, the effects of writing ability and mode of discourse of cognitive capacity engagement were investigated. Sixty-three college freshmen of varying writing abilities (basic, average, and honors) were randomly assigned to experimental treatments (descriptive writing, narrative writing, and persuasive writing). Using the secondary task method, it was found that writing ability differentially affects cognitive capacity engagement across modes. For example, honors writers were least engaged when writing descriptive essays but were most engaged when writing persuasive essays whereas average writers were most engaged when writing descriptive essays but were least engaged when writing narrative essays. Analytic quality scores and engagement were related and results were interpreted in the context of schema theory to estimate the learning potential of a given mode of discourse. Also, engagement and syntactic complexity treasures were related. It was found that as words per clause increased, engagement also increased; whereas, as clauses per T-unit increased, engagement decreased. / Ed. D.