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

A simulation of recrystallization based on EBSD orientation microscopy data

The present paper introduces a novel stochastic two-dimensional model to simulate the evolution of microstructure and texture during recrystallization. The model is based on data derived by automated large-scale EBSD local texture analysis, i.e., by orientation microscopy. Each measured point is characterized by its coordinates x and y in the microstructure, its crystallographic orientation g and a parameter q describing the quality of the EBSD-pattern which is affected by lattice strain and hence discloses information on the dislocation density. The concurrent information on the local arrangement of orientations and dislocation densities is utilized to derive conclusions on the nucleation and subsequent growth of the new recrystallized grains. The principles of the model are outlined and three example are shown to illustrate the possibilities of the model to simulate the evolution of microstructure and texture during recrystallization

On the influence of dispersoids on the particle stimulated nucleation of recrystallization

Recrystallization of Al alloys is controlled by precipitates. Whereas large particles are generally assumed to promote recrystallization by particle stimulated nucleation, finely dispersed precipitates, either already present in the as-deformed state or precipitating during the recrystallization anneal, are known to strongly retard the progress of recrystallization. It was the aim of this study to elucidate these concurring effects of large particles, and small dispersoids as well as of a supersaturation of solutes on recrystallization in a ternary Al-Fe-Si model alloy. Samples were prepared with different pre-annealing treatments to produce different states of precipitation and supersaturation. Evolution of the microstructure and of the crystallographic texture was followed during cold rolling and recrystallization. Conclusions were drawn on the efficiency of recrystallization nucleation at the various nucleation sites and, especially, on the influence of dispersoids on recrystallization

Development of Epithelial Attachment and Gingival Sulcus in Rhesus Monkeys

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141260/1/jper0044.pd

Healing Following Simple Gingivectomy. A Tritiated Thymidine Radioautographic Study. I. Epithelialization

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142075/1/jper0298.pd

Conserved Endonuclease Function of Hantavirus L Polymerase.

Hantaviruses are important emerging pathogens belonging to the Bunyaviridae family. Like other segmented negative strand RNA viruses, the RNA-dependent RNA polymerase (RdRp) also known as L protein of hantaviruses lacks an intrinsic "capping activity". Hantaviruses therefore employ a "cap snatching" strategy acquiring short 5' RNA sequences bearing 5'cap structures by endonucleolytic cleavage from host cell transcripts. The viral endonuclease activity implicated in cap snatching of hantaviruses has been mapped to the N-terminal domain of the L protein. Using a combination of molecular modeling and structure-function analysis we confirm and extend these findings providing evidence for high conservation of the L endonuclease between Old and New World hantaviruses. Recombinant hantavirus L endonuclease showed catalytic activity and a defined cation preference shared by other viral endonucleases. Based on the previously reported remarkably high activity of hantavirus L endonuclease, we established a cell-based assay for the hantavirus endonuclase function. The robustness of the assay and its high-throughput compatible format makes it suitable for small molecule drug screens to identify novel inhibitors of hantavirus endonuclease. Based on the high degree of similarity to RdRp endonucleases, some candidate inhibitors may be broadly active against hantaviruses and other emerging human pathogenic Bunyaviruses