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<Refereed Article>Impact of the Characteristics of Contractors on the Construction Quality of Public Works
No full textThis study aimed to clarify whether the characteristics of contractors and the winning bid rate impact the quality of construction projects. The winning bid rate is the ratio of the winning bid amount to the target price, which is the estimated amount determined by the client based on the substance of the work and the required technology. This study used data on the pre-qualification system and construction quality evaluation for public works in Japan. We conducted an empirical analysis using panel regression to examine whether contractor characteristics and winning bid rates affect construction quality. The empirical analysis showed that the quality of construction projects tended to be high for contractors with high profitability, financial soundness and technical expertise. Moreover, the quality tended to be high for contractors with high winning bid rates. The originality of this research lies in its use of quantitative data from the actual pre-qualification system and construction quality evaluation and statistical methods to demonstrate the relationship between the winning bid rate, characteristics of contractors and quality of public works projects
Fabrication of Multiscale, Multidirectional Orientated Collagen Hydrogels with Guided Cell Alignment Using Fluidics and a Three-Dimensional Printing
Get PDFVarious tissues have oriented collagen structures that confer mechanical strength and stability. However, creating models that precisely mimic the size and direction of these tissues remains challenging. In the present study, we developed a collagen tissue with multiscale and multidirectional controlled orientation using fluidic devices prepared using three-dimensional (3D) printing technology. Two types of fluidic channels were fabricated: a one-directional “horizontal orientation model” and vertical protrusions added to create a two-directional “vertical/horizontal orientation model”. A type I collagen solution, mixed with or without cells, was introduced into the fluidic channel and gelled. As a result, in the horizontal orientation model, collagen fibrils and fibers were oriented by the flow. Both the fibroblasts and stem cells were aligned parallel to the flow along the collagen structure. In the vertical/horizontal orientation model, both the horizontal and vertical parts confirmed the orientation of collagen fibrils, fibers, and fibroblasts in both directions. Observation of the model at the nanoscale level using scanning electron microscopy (SEM) can explain the collagen orientation mechanism at the molecular and fibril levels. Prior to full gelation, collagen molecules and fibrils align parallel to the flow owing to the influence of flow and channel wall effects. This wall effect, starting from the outer channel wall, creates a gelated collagen “wall” toward the inside of the channel. Collagen fibrils aggregate into collagen fibers. In our experiments focusing on collagen contraction, the cell orientation was also described. As cells proliferate in response to the contact guidance of collagen fibrils and fiber orientation, focal adhesions and F-actin are activated and organize anisotropic traction forces that, in turn, drive cell orientation. Therefore, our method enables the customization of models with the desired tissue-specific orientations, thereby advancing future possibilities in tissue engineering
界面活性剤を含有する水系電解液の基礎物性と次世代蓄電池への応用に関する研究
Get PDF横浜国立大学博士（工学）この学位論文の全文は、中央図書館で平日17時までに申請することで閲覧が可能です。The full text of this thesis is available for viewing at the Central Library upon request by 5:00 p.m. on weekdays
The establishment of modern land ownership and its legal challenges: perspectives for contemporary Cambodia based on the experience of Meiji Japan
Get PDF横浜国立大学博士（法学）この学位論文の全文は、中央図書館で平日17時までに申請することで閲覧が可能です。The full text of this thesis is available for viewing at the Central Library upon request by 5:00 p.m. on weekdays
Material-Mechanistic Interplay in SiCN Wafer Bonding for 3D Integration
Get PDFWafer bonding is a step in processing of state-of-theartintegration architectures in CMOS devices. Sufficiently high bonding strength and low distortion with high alignment accuracy are essential to realize these device structures. A challenge in realizing advanced architectures is reducing the thermal history associated with the bonding process. Although much research has been conducted on wafer bonding methods compatible with the latest semiconductor manufacturing processes, discussions on the interface mechanisms during low temperature annealing have been insufficient. In this study, plasma-activated bonding was carried out using SiCN, which is a major bonding dielectric material. The bonding strength and water remaining at the interface were subsequently evaluated. We found that a SiCN film achieved greater bonding strength after post bond annealing at a low temperature of 250 °C and completely consumed the interfacial water. Analyses of the surface and interface revealed the carbon bonding leads to great bonding interface by low-temperature annealing