Engineering topics

Kim, Hyun Jeong

Publications and source records attributed to Kim, Hyun Jeong.

3 records

DOE OSTI2012

XIAP reverses various functional activities of FRNK in endothelial cells

Highlights: Black-Right-Pointing-Pointer FRNK domain is recruited into focal adhesion (FA), controlling endothelial cell adhesion. Black-Right-Pointing-Pointer XIAP binds the FRNK domain of FAK. Black-Right-Pointing-Pointer XIAP inhibits recruitment of FRNK into Fas and FRNK-promoted cell adhesion. Black-Right-Pointing-Pointer XIAP plays a key role in vascular functions of FRNK or FRNK domain-mediated vascular functions of FAK. -- Abstract: In endothelial cells, focal adhesion kinase (FAK) regulates cell proliferation, migration, adhesion, and shear-stimulated activation of MAPK. We recently found that FAK is recruited into focal adhesion (FA) sites through interactions with XIAP (X-chromosome linked inhibitor of apoptosis protein) and activated by Src kinase in response to shear stress. In this study, we examined which domain(s) of FAK is(are) important for various vascular functions such as FA recruiting, XIAP-binding and shear stress-stimulated ERK activation. Through a series of experiments, we determined that the FRNK domain is recruited into FA sites and promotes endothelial cell adhesion. Interestingly, XIAP knockdown was shown to reduce FA recruitment of FRNK and the cell adhesive effect of FRNK. In addition, we found that XIAP interacts with FRNK, suggesting cross-talk between XIAP and FRNK. We also demonstrated that FRNK inhibits endothelial cell migration and shear-stimulated ERK activation. These inhibitory effects of FRNK were reversed by XIAP knockdown. Taken together, we can conclude that XIAP plays a key role in vascular functions of FRNK or FRNK domain-mediated vascular functions of FAK.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2010

Growth of Crystalline Polyaminoborane through Catalytic Dehydrogenation of Ammonia Borane on FeB Nanoalloy

Tremendous effort has been devoted to the study of complex and chemical hydrides for hydrogen storage in the past decade [1, 2] . Ammonia Borane (NH 3 BH 3 , AB) with a hydrogen content of 19.6 wt % has received significant attention [3-5] . Methods to improve the kinetics of the step-wise dehydrogenation of AB are diverse including the uses of mesoporous frameworks [6] , catalysts [7-16] , and additives [17] . It was reported that when dissolving in organic solvents AB released hydrogen readily in the presence of transition metal catalysts through the formation of M∙∙∙HBH 2 NH 3 complex (where M is Ir, Ru, or Ni etc.) [8-10] ; Lewis or Brønsted acids, on the other hand, react with AB in solution to form the initiating species (BH 2 NH 3 ) + [11] , which may have the similar function as the [BH 2 (NH 3 ) 2 ] + BH 4 - (DADB) in the dehydrogenation of solid AB [17, 18] . However, comparatively little study has been reported on the catalytic dehydrogenation of AB in solid form. Other important but less investigated aspects in the solid-state reaction are the characterizations of functional catalytic species and products from the step-wise dehydrogenation.

08 HYDROGEN↗

DOE OSTI2010

Storing Hydrogen

Researchers have been studying mesoporous materials for almost two decades with a view to using them as hosts for small molecules and scaffolds for molding organic compounds into new hybrid materials and nanoparticles. Their use as potential storage systems for large quantities of hydrogen has also been mooted. Such systems that might hold large quantities of hydrogen safely and in a very compact volume would have enormous potential for powering fuel cell vehicles, for instance. A sponge-like form of silicon dioxide, the stuff of sand particles and computer chips, can soak up and store other compounds including hydrogen. Studies carried out at the XOR/BESSRC 11-ID-B beamline at the APS have revealed that the nanoscopic properties of the hydrogenrich compound ammonia borane help it store hydrogen more efficiently than usual. The material may have potential for addressing the storage issues associated with a future hydrogen economy. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

08 HYDROGEN↗