Effect of homogenisation conditions on recrystallisation in the Al-Mg-Mn alloy AA5454

The purpose of the present work is to understand the microstructure development and, particularly, to control the progress of recrystallisation in hot strip in the Al-Mg-Mn alloy AA 5454, which is typically used for the manufacture of structural automotive components. The chemical composition, together with the thermomechanical processing history of this material, has a strong influence on the microstructure of the product and the resulting properties as it is supplied to the customer. Electrical conductivity measurements, thermal analysis and electron microscopy have been carried out to characterise the evolution of precipitation state at various stages in the processing route. The conditions of the homogenisation heat treatment have been varied, and the effect on subsequent recrystallisation after hot rolling has been evaluated in both the as cast and rough rolled condition by optical microscopy techniques. Results indicate that the conditions of homogenisation heat treatment and roughing rolling are critical for the generation of a suitable recrystallised microstructure in AA 5454 hot strip. A new two stage homogenisation practice has been developed to expedite post-rolling recrystallisation in this alloy

Effect of Substrate Ligand Presentation on the Motility of Human T-Lymphocytes

EFFECT OF SUBSTRATE LIGAND PRESENTATION ON THE MOTILITY OF HUMAN T-LYMPHOCYTES George Aaron Dominguez Daniel A. Hammer T lymphocyte homing and migration is critical for host defense and immunity. T lymphocytes must be captured from blood flow, tether and roll on the endothelial surface, engage chemokine receptors, and firmly adhere and migrate to sites of inflammation or to secondary lymphoid organs. How adhesive ligands, soluble factors such as chemokines, and fluid shear flow influence the motility of T lymphocytes is important for understanding this dynamic cascade of events. In this thesis, primary human T lymphocyte motility was quantified on various adhesive ligands (haptokinesis) in the presence of chemokines (chemokinesis) and in response to fluid flow. Through the use of microcontact printing onto PDMS surfaces we created surfaces that presented ligand at controlled densities either alone or in combination. The adhesive ligands ICAM-1, VCAM-1, and fibronectin were used to quantify cell migration in the absence of chemokine revealing different modes of T lymphocyte motility with ICAM-1 having an overall greater contribution. Using the homeostatic chemokines CCL19, CCL21, and CXCL12, we demonstrated that motility is biphasic and is dependent upon ICAM-1 concentration, and by presenting chemokines in combination, we can drive motility to higher levels than what was seen with each chemokine individually. Finally we demonstrated that directed migration either upstream or downstream of fluid flow is dependent upon the presence of ICAM-1, VCAM-1, or a combination of the two and the shear rate used. We have been able to show that adhesive ligands, chemokines, and shear flow all work in concert to promote robust primary human T lymphocyte adhesion and migration on microcontact printed PDMS surfaces. This research further elucidates how T lymphocytes interpret these signals for controlling homing to and motility within secondary lymphoid organs and the mechanisms of their migration

Design, Actuation, and Functionalization of Untethered Soft Magnetic Robots with Life-Like Motions: A Review

Soft robots have demonstrated superior flexibility and functionality than conventional rigid robots. These versatile devices can respond to a wide range of external stimuli (including light, magnetic field, heat, electric field, etc.), and can perform sophisticated tasks. Notably, soft magnetic robots exhibit unparalleled advantages among numerous soft robots (such as untethered control, rapid response, and high safety), and have made remarkable progress in small-scale manipulation tasks and biomedical applications. Despite the promising potential, soft magnetic robots are still in their infancy and require significant advancements in terms of fabrication, design principles, and functional development to be viable for real-world applications. Recent progress shows that bionics can serve as an effective tool for developing soft robots. In light of this, the review is presented with two main goals: (i) exploring how innovative bioinspired strategies can revolutionize the design and actuation of soft magnetic robots to realize various life-like motions; (ii) examining how these bionic systems could benefit practical applications in small-scale solid/liquid manipulation and therapeutic/diagnostic-related biomedical fields