In-situ observation of transition between surface relief and wrinkling in thin film shape memory alloys.

Significant surface morphology evolution between relief and wrinkling was observed on a 3.5 microm thick TiNiCu film sputter-deposited on a silicon substrate. At room temperature, variation in surface relief morphology (from separated martensite crystals embedded in amorphous matrix to fully interweaved martensite plates) was observed with slight change in film composition. The phenomenon was attributed to variations in crystallization temperatures of as-deposited amorphous films during annealing because of the compositional difference. During thermal cycling between room temperature and 100 degrees C, reversible surface morphology changes can be observed between surface relief and wrinkling patterns. The formation of the surface wrinkling is attributed to the large compressive stress in the film during high temperature post-annealing and crystallization, whereas surface relief is caused by the martensitic transformation to relieve the large tensile stress in the film. Compositional effect on this surface morphology evolution is discussed. Results also indicate that there is a critical dimension for the wrinkling to occur, and a small circular island can only relax by in-plane expansion.

Nucleosome remodeling at the IL-12 p40 promoter is a TLR-dependent, Rel-independent event.

Lipopolysaccharide (LPS) induction of the gene encoding interleukin 12 p40 requires remodeling of a promoter-encompassing nucleosome and the Toll-like receptor (TLR)-mediated activation of a c-Rel-containing complex. Analysis of TLR4-mutant mice revealed that remodeling requires TLR signaling. However, Rel proteins and other proteins required for transcription of an integrated p40 promoter were insufficient for remodeling. c-Rel was also unnecessary for remodeling, as remodeling was observed in c-Rel-/- macrophages, which lack p40 transcripts. These results suggest that remodeling requires TLR signaling pathways that diverge from the c-Rel activation pathways. The factors that stimulate remodeling may represent, therefore, newly identified targets of TLR signaling and of agents that regulate inflammatory responses and TH1 development.

Selective requirement for c-Rel during IL-12 P40 gene induction in macrophages.

A major challenge in the study of gene regulation by NF-kappaB/Rel transcription factors is to understand, at the biological and mechanistic levels, the selective functions of individual Rel family members. To study selectivity, we have examined the NF-kappaB/Rel protein binding site (Rel site) within the IL-12 p40 promoter. IL-12 is a proinflammatory cytokine expressed by activated macrophages that serves as an essential inducer of T helper 1 cell development. In nuclear extracts from lipopolysaccharideactivated macrophages, the predominant Rel dimers capable of binding the IL-12 p40 Rel site were the p50/p65 and p50/c-Rel heterodimers and p50/p50 homodimer. The two heterodimers bound the site with comparable affinities and exhibited comparable transactivation activities. In striking contrast, p40 mRNA and protein concentrations were reduced dramatically in c-Rel(-/-) macrophages and only modestly in p65(-/-) macrophages. Other proinflammatory cytokine mRNAs and proteins were not significantly reduced in c-Rel(-/-) macrophages. These results reveal that a c-Rel-containing complex is an essential and selective activator of p40 transcription, which may reflect unique regulatory mechanisms or biological functions of IL-12. Furthermore, because selectivity was not observed in vitro or in transient transactivation experiments, these findings suggest that an understanding of the selectivity mechanism may require an analysis of the endogenous p40 locus.