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We explore a specific small geometry containing a single thin bounded grain on a substrate with a hole at its center. By employing a mathematical model based on surface diffusion, no flux boundary conditions, and prescribed contact angles, we study the evolution of the hole as well as the exterior surface of the grain, based on energetic considerations and dynamic simulations. Our results regarding the formation and evolution of holes in thin films in small geometries shed light on various nonlinear phenomena associated with wetting and dewetting.

Yes / Local scour around submarine pipelines can affect the stability of the pipeline. The accurate estimation of the scour around submarine pipelines has been a hot topic of research among marine engineers. This paper presents results from a numerical study of clear-water scour depth below a submarine pipeline for a range of the steady flow conditions. The flow field around the pipeline under scour equilibrium condition is numerically simulated by solving the Reynolds-Averaged Navier-Stokes (RANS) equations with the standard k-ε turbulence closure. The flow discharge through the scour hole for various flow conditions is investigated. The results are used to establish the relationship between the flow discharge and the maximum scour depth. Incorporated with the Colebrook-White equation, the bed shear stress is obtained and an iterative method is proposed to predict the scour depth around the submarine pipeline. The calculated scour depths using the present method agree well with the laboratory measurements, with the average absolute relative error being smaller than that using previous methods, indicating that the proposed method can be used to predict the clear-water scour around the submarine pipeline with satisfactory accuracy. / National Nature Science Fund of China (Grant No.50879084, 51279189), the Open Fund from the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKHL1302),China Scholarship Council, Public Projects of Zhejiang Province (2016C33095) and the Natural Science Fund of Zhejiang Province (LQ16E090004).

Yes / This paper presents the results of laboratory experiments and numerical simulations to investigate the effect of different piggyback pipeline configuration on the morphology of local seabed scour subject to steady currents. Piggyback pipeline configuration investigated includes the commonly used piggyback pipeline, namely a small pipe attached on the top of large pipe and new form of piggyback pipeline proposed in this study in which a small pipe is attached to the large pipe on the upstream and downstream side, respectively. Pressure gradient, drag coefficient, lift coefficient and scour extent around pipelines are measured and analyzed for a range of pipelines and current conditions. Results show that the vortex strength downstream of the commonly used piggyback pipeline is larger than that for a single as well as the new piggyback pipeline under the same condition. This new type piggyback pipeline can effectively reduce the depth and width of the scour hole. In particular, when the ratio of the small pipe diameter over the large pipe diameter is greater than 0.3, little scour under this new type piggyback pipeline occurs for the test conditions. The bed topography downstream of the pipe has also been altered to favor the backfill. / National Natural Science Foundation of China (No. 51279189).

The goal of a gas turbine engine designer is to reduce the amount of coolant used to cool the critical turbine surfaces, while at the same time extracting more benefit from the coolant flow that is used. Fan-shaped holes offer this opportunity, reducing the normal jet momentum and spreading the coolant in the lateral direction providing better surface coverage. The main drawback of fan-shaped cooling holes is the added manufacturing cost from the need for electrical discharge machining instead of the laser drilling used for cylindrical holes. This research focused on examining the performance of fan-shaped holes on two critical turbine surfaces; the vane and endwall. This research was the first to offer a complete characterization of film-cooling on a turbine vane surface, both in single and multiple row configurations. Infrared thermography was used to measure adiabatic wall temperatures, and a unique rigorous image transformation routine was developed to unwrap the surface images. Film-cooling computations were also done comparing the performance of two popular turbulence models, the RNG-kε and the v2-f model, in predicting film-cooling effectiveness. Results showed that the RNG-kε offered the closest prediction in terms of averaged effectiveness along the vane surface. The v2-f model more accurately predicted the separated flow at the leading edge and on the suction side, but did not predict the lateral jet spreading well, which led to an over-prediction in film-cooling effectiveness. The intent for the endwall surface was to directly compare the cooling and aerodynamic performance of cylindrical holes to fan-shaped holes. This was the first direct comparison of the two geometries on the endwall. The effect of upstream injection and elevated inlet freestream turbulence was also investigated for both hole geometries. Results indicated that fan-shaped film-cooling holes provided an increase in film-cooling effectiveness of 75% on average above cylindrical film-cooling holes, while at the same time producing less total pressure losses through the passage. The effect of upstream injection was to saturate the near wall flow with coolant, increasing effectiveness levels in the downstream passage, while high freestream turbulence generally lowered effectiveness levels on the endwall. / Ph. D.

Acetylcholinesterase (AChE) terminates cholinergic neurotransmission by catalyzing the hydrolysis of the neurotransmitter acetylcholine (ACh). Inhibition of AChE has proven an effective treatment for the memory loss exhibited by early stage Alzheimer's disease (AD) patients; four AChE inhibitors (AChEI) have been approved by the FDA for this purpose. The first AChEI approved for the palliative treatment of AD-related memory loss was 9-amino-1,2,3,4-tetrahydroacridine (tacrine). Inhibition of AChE may present either therapeutic or toxic effects depending upon the dose administered. With the goal of discovering safe and effective pesticides to control the population of Anopheles gambiae, a malaria-transmitting mosquito indigenous to Sub-Saharan Africa, the reoptimization of the tacrine pharmacophore was undertaken. Because the optimized drug would necessarily be a poor inhibitor for human AChE (hAChE), initial ligand design focused on modification to tacrine known to negatively impact the inhibition potency for hAChE. Ultimately, an AChEI was discovered, which exhibited micromolar inhibition of Anopheles gambiae AChE (AgAChE) and essentially no potency for hAChE. Two units of this lead compound were tethered through an alkyl chain to yield a nanomolar inhibitor of AgAChE that was more than 1,100-fold selective for the mosquito enzyme over hAChE. Dimerization of an active inhibitor is an effective strategy to increase the potency and selectivity of AChEI, and many examples of tacrine hetero- and homodimers complexed to AChE can be found in the RCSB Protein Data Bank (PDB). The bond formed between the exocyclic amine moiety and the heterocyclic ring system of tacrine is analogous to an amide bond when tacrine is protonated. Therefore, the rotational profile of protonated N-alkyltacrine should exhibit a conformational profile in which dihedral angles significantly out of the plane formed by the ring system are associated with high energies relative to those when the dihedral angles are nearly coplanar with the ring system. The barrier of rotation (ΔG^‡) produced by this phenomenon in two tacrine derivatives and two quinoline derivatives was experimentally determined using dynamic 1H NMR. These values were compared to density functional theory (DFT) derived values for the same phenomenon. Furthermore, since the ΔG^‡ proved to be impossible to experimentally determine for the optimal model compound for the active site portion of tacrine dimers, N-methyltacrine, the DFT method employed for modeling the ΔG^‡ of the tacrine and quinoline analogs was used to computationally derive the entire rotational conformation diagram of N-methyltacrine. The calculated values were then used to comment on the relative energies of adopting certain conformations found in the X-ray crystal structures of dimer/AChE complexes. / Ph. D.

No / BACKGROUND: A Full Thickness Macular Hole (FTMH) is often associated with vitreomacular traction, and this can be asymmetric with vitreomacular traction on one side of the hole but not the other. In cross-section, the elevated retinal rim around a developed FTMH is seen as a drawbridge elevation, and this drawbridge elevation may be used as a measure of morphological change. Examination of the drawbridge elevation of the retinal rim in FTMH with asymmetric vitreomacular traction may help to clarify the role of vitreomacular traction in the development of FTMH. METHOD: Cases of FTMH were identified with an initial OCT scan showing vitreomacular traction on one side of the hole only and that had a follow-up OCT scan showing progression of the hole. A tangent to the retinal surface at a distance of 700 microns from the axis of the hole was used as a marker of the drawbridge elevation of the retinal rim around the macular hole. Comparisons of the drawbridge elevation and change in drawbridge elevation between the sides with and without initial vitreomacular traction were made. RESULTS: There was no significant difference between the drawbridge elevation, or change in drawbridge elevation, on the side of the hole with initial vitreomacular traction compared to the side without initial traction. CONCLUSION: There is some intrinsic mechanism within the retina to link the morphological changes on the two sides of a FTMH. A bistable hypothesis of FTMH formation and closure is postulated to explain this linkage.

No / The inner retinal complex is a well-defined layer in spectral-domain OCT scans of the retina. The central edge of this layer at the fovea provides anatomical landmarks that can be observed in serial OCT scans of developing full-thickness macular holes (FTMH). Measurement of the movement of these points may clarify the mechanism of FTMH formation. This is a retrospective study of primary FTMH that had a sequence of two OCT scans showing progression of the hole. Measurements were made of the dimensions of the hole, including measurements using the central edge of the inner retinal complex (CEIRC) as markers. The inner retinal separation (distance between the CEIRC across the centre of the fovea) and the Height-IRS (average height of CEIRC above the retinal pigment epithelium) were measured. Eighteen cases were identified in 17 patients. The average increase in the base diameter (368 microns) and the average increase in minimum linear dimension (187 microns) were much larger than the average increase in the inner retinal separation (73 microns). The average increase in Height-IRS was 103 microns. The tangential separation of the outer retina to produce the macular hole is much larger than the tangential separation of the inner retinal layers. A model based on the histology of the Muller cells at the fovea is proposed to explain the findings of this study.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第25108号 / 理博第5015号 / 新制||理||1715(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 田中 貴浩, 准教授 久徳 浩太郎, 教授 橋本 幸士 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009. / Includes bibliographical references. / Tropical cyclone activity over the last 5000 years is investigated using overwash sediments from coastal lagoons on the islands of Vieques, Puerto Rico and Koshikijima, Japan. A simple sediment transport model can reproduce the landward fining deposits observed at Vieques, and reveals that although the record exhibits centennial-tomillennial changes in hurricane overwash frequency, the magnitude of these flooding events has remained relatively constant. Stochastic simulations of hurricane overwash show that breaks in activity at Vieques are extremely long and unlikely to occur under the current hurricane climatology and the present barrier morphology. Periods of less frequent hurricane deposition at Vieques are contemporaneous with intervals of increased El Nifio occurrences and reduced precipitation in West Africa, suggesting a dominant influence by these two climatic phenomena. Hiatuses in overwash activity between 3600-to-2500 and 1000-500 years ago are longer than what is generated by overwash simulations under a constant El Niflo-like state, indicating that mechanisms in addition to variability in the El Nifio/Southern Oscillation are required to completely produce the overwash variability at Vieques. Periods of low overwash activity at Vieques are concurrent with increased overwash activity at Kamikoshiki and may indicate a correspondence between tropical cyclone activity in the western Northern Atlantic and the western North Pacific. / by Jonathan D. Woodruff. / Ph.D.