Shear Localization in the Metallic Nanolayered Composites

In this dissertation, the influences of layer thickness (h), interface orientation relationship (OR) and dislocation slip activities on shear band (SB) formation mechanisms was investigated by means of molecular dynamics (MD) simulations. The effect of h and dislocation slip systems on the shear localization in Cu-FCC/Nb-BCC MNCs was studied. The strain softening observed in those samples was triggered by the SB formation. The microstructure evolutions and dislocation slips revealed that the unsymmetrical dislocation transmission across the interface induces the shear localization and promotes the SB formation. The quantitative analysis of the change in the separation distance of initially nearest neighbor atoms suggested that the plastic strain mainly comes from the interface sliding within the SB in large strains. Plastic deformation and mechanisms of SB behaviors of Cu/Au, Cu/Ag, Cu/Al and Cu/Ni MNCs subjected to the uniaxial compression loading were studied by MD. Results indicated that SB behaviors are associated with the layer thickness, stacking fault energy and interface structures. The SBs were only observed in Cu/Au and Cu/Ag MNCs, and the onset strain of SB behaviors increased with the increasing layer thickness. In comparison, no SB was observed in the Cu/Al and Cu/Ni MNCs. For the Cu/Au and Cu/Ag MNCs, deformation twinning was observed due to Shockley partial dislocations intersections, which could create steps within interfaces, meanwhile the SB was formed along the deformation twin plane direction. For the Cu/Al and Cu/Ni MNCs, many different dislocations slip systems could be activated during plastic deformation, leading to the relatively uniform deformation. The influence of thick three-dimension (3D) interface on the SB behaviors of Cu/Nb under compressive loading was studied using MD simulations. The 3D interface in Cu/Nb could weaken slip localization and prevent shear banding to some extent by changing dislocation-interface interactions. We analyzed dislocation slip activities, suggesting that 3D Cu/Nb has a relatively uniform dislocation slips in all the (111) planes, whereas 2D Cu/Nb has more strain contribution by dislocation slips in one plane leading to shear banding. Deformation twinning dominates the plasticity of Nb layers in 3D Cu/Nb, which prevents shear banding formation

Targeted Delivery of Chlorin e6 via Redox Sensitive Diselenide-Containing Micelles for Improved Photodynamic Therapy in Cluster of Differentiation 44-Overexpressing Breast Cancer

The off-target activation of photosensitizers is one of the most well-known obstacles to effective photodynamic therapy (PDT). The selected activation of photosensitizers in cancer cells is highly desired to overcome this problem. We developed a strategy that enabled diselenide bonds to link hyaluronic acid (HA) and photosensitizer chlorin e6 (Ce6) to assemble the micelles (HA-sese-Ce6 NPs) that can target cancer and achieve a redox responsive release of drugs to enhance the PDT efficiency in breast cancer. The HA was used to form a hydrophilic shell that can target cluster of differentiation 44 (CD44) on the cancer cells. The selenium-containing core is easily dissembled in a redox environment to release Ce6. The triggered release of Ce6 in a redox condition and the positive feedback release by activated Ce6 were observed in vitro. In cytotoxicity assays and in vitro cellular uptake assays, the increased PDT efficiency and targeted internalization of HA-sese-Ce6 NPs in the cells were verified, compared to a free Ce6 treated group. Similar results were showed in the therapeutic study and in vivo fluorescence imaging in an orthotopic mammary fat pad tumor model. In addition, a significant inhibition of metastasis was found after the HA-sese-Ce6 NPs treatment. In general, this study promises an ingenious and easy strategy for improved PDT efficiency

‘Doing’ leadership in interaction : a discursive investigation of emerging leadership construction in small group interaction

Exerting influence is essential in social life but how to exert influence over and lead others is a complex but intriguing question. Although the dynamic and procedural nature of leadership construction has drawn increasing attention in recent years, investigations on how interactional practices may be employed in order to emerge as a leader in non-hierarchal settings remain lacking. The present research aims to explore how emerging leadership is constructed through interactions in the Chinese context. In particular, this study emphasizes three aspects: interactional processes of micro-level emerging leadership construction, interactional strategies to construct emerging leadership, and interactional predictors of leadership emergence. The study adopts the combined methods of leaderless group discussion and follow-up interviews to collect data on actual leadership emergence practices and participants’ perceptions of emerging leadership construction. Conversation analysis was applied to reveal the processes and strategies by which emerging leadership is constructed. To identify predictors of leadership emergence, statistical analysis of data on participants’ interactional strategies and perceived leadership was conducted. It was found that emerging leadership is collaboratively constructed by participants claiming, negotiating and granting leadership positions in agenda-related proposal sequences and decision-making sequences. Six possible responses to negotiate leadership claims were also identified. Interactional strategies in terms of turn-taking, linguistic formats, prosodic cues and nonverbal behaviors were found to facilitate the construction of emerging leadership in two manners, namely, domineering and facilitative. Participants’ reports in follow-up interviews also aligned with the findings about leadership processes and leadership strategies found in the interactional data. In addition, the results of correlation analysis and mediation tests suggested that both how much participants say and what they say predict leadership emergence, but what participants say is the root cause of how much they say being predictive of leadership emergence. The present study has both theoretical and practical implications, as it advances the understanding of interactional patterns, strategies, and predictors of leadership emergence, and it offers interactional guideline for leadership training and practices.DOCTOR OF PHILOSOPHY (HSS

CONTACT ANALYSIS OF THE SPIRAL BEVEL GEAR BASED ON MATLAB

In this paper,the use of local synthesis method,study the tooth contact analysis（ TCA） of the CRH5 traction gear by programming with MATLAB,respectively,calculate contact tracing line on the tooth surface and the graph of the transmission error of the middle point,huge end and small end respectively,and the graph is analyzed and explained,not only improves the direct use of TCA method to solve tooth contact,such as programming complex,time-consuming,and laid a good foundation for the rational design of cutting parameters of the spiral bevel gears

Transition of Urban Morphology in the Mountainous Areas Since Early-Modern Times from the Perspective of Urban Historic Landscape—A GIS Tools and Historical Map Translation Approach

Regenerating cities must blend modernization and heritage. Both urban morphology and Historic Urban Landscape (HUL) highlight historical processes and may assist in regeneration. Using Chongqing as the study example may further understand mountain cities, which are prevalent worldwide but seldom examined in morphology research. This study explores and organizes the historical modernization of Chongqing’s parent city from early-modern times to the present day using a universal approach established in this research developed by the HUL perspective and research framework, Geographic information system (GIS), Depthmap tool, and historical map translation method. Large-scale modernization occurred prior to the 1980s, followed by more modest rehabilitation projects. The whole procedure is described by the phrase “Construction first, then planning, then transformation,” which entails a “free growth” block structure at the outset, along with planning control. The study contributes the following: (1) Establishing a theoretical framework and research technique for the universal city based on historical sources and modern instruments; (2) Chongqing’s future sustainable development and historical preservation depend in large part on figuring out the city’s complicated modernization history; (3) The study of mountain cities may benefit from understanding the geographical development and spatial dynamic layering of Chongqing. (4) This study bridges the gap in time by going beyond the early modern period covered by the previous ones and into the post-statehood era (1949–2022)

Transition of Urban Morphology in the Mountainous Areas Since Early-Modern Times from the Perspective of Urban Historic Landscape—A GIS Tools and Historical Map Translation Approach

Regenerating cities must blend modernization and heritage. Both urban morphology and Historic Urban Landscape (HUL) highlight historical processes and may assist in regeneration. Using Chongqing as the study example may further understand mountain cities, which are prevalent worldwide but seldom examined in morphology research. This study explores and organizes the historical modernization of Chongqing’s parent city from early-modern times to the present day using a universal approach established in this research developed by the HUL perspective and research framework, Geographic information system (GIS), Depthmap tool, and historical map translation method. Large-scale modernization occurred prior to the 1980s, followed by more modest rehabilitation projects. The whole procedure is described by the phrase “Construction first, then planning, then transformation,” which entails a “free growth” block structure at the outset, along with planning control. The study contributes the following: (1) Establishing a theoretical framework and research technique for the universal city based on historical sources and modern instruments; (2) Chongqing’s future sustainable development and historical preservation depend in large part on figuring out the city’s complicated modernization history; (3) The study of mountain cities may benefit from understanding the geographical development and spatial dynamic layering of Chongqing. (4) This study bridges the gap in time by going beyond the early modern period covered by the previous ones and into the post-statehood era (1949–2022)

Thickness-Dependent Shear Localization in Cu/Nb Metallic Nanolayered Composites

We performed molecular dynamics simulations to study the effect of the layer thickness on the shear localization in Cu/Nb metallic nanolayered composites (MNCs). Our simulation results achieve good agreement with experimental results that the inverse size effect in the strength occurs in samples with layer thickness below 2.0 nm. The strain softening observed in those samples was triggered by the shear localization. The quantitative analysis revealed that the unsymmetrical dislocation transmission across the interface induces the shear localization and promotes the shear band formation in Cu/Nb MNCs. The plastic strain mainly comes from the interface sliding within the shear band