STUDY OF CATALYTIC GROWTH OF OLEFIN NANO FIBRILS AND CARBON NANO FIBRILS OVER SOLID SURFACE AND ITS APPLICATION

In this dissertation, the catalytic growth of nano fibrils over solid surface of different geometric types is studied and their applications are also investigated. The new experimental results on olefin polymerization with metallocene catalyst over silica supports of different geometries are presented. Flat surface silica, nano-sized spherical silica, straight cylindrical pore silica, macroporous silica, and conventional silica are used as support materials. The presence or absence of intraparticle monomer diffusion resistance and particle fragmentation has been shown to have significant effects on the catalytic activity. Also the effects of support geometry on the morphology of polymers and intrinsic catalytic activity are analyzed. The catalytic growth of olefin nano fibrils are applied in micro/milli reactors. Unlike many conventional olefin reactors, the reaction temperature, heat transfer and bimodal distribution of polymer molecular weight can easily be controlled in the micro/milli reactor systems developed during this study. The catalytic growth of carbon nano fibrils on silicon has been investigated for application as anode materials in Li-ion batteries. This research is aimed at developing a binder free silicon anode system that consists of a modified Cu foil (current collector), Si nanoparticles (SiNPs), and carbon nanotubes (CNTs). This anode system includes the nanostructured Cu surface layer as a hub for the Si nanoparticles that undergo deformation and fragmentation during the charge/discharge cycles. SiNPs are deposited with Fe-Co bimetallic catalyst and CNTs are grown in situ at the catalyst sites. The surface layer of the Cu is modified via an oxidation and reduction processes to have knife-like nanostructures with high void fractions. The SiNPs are deposited on/in to the nanostructured Cu foil without any binders. The CNTs growing at the surface of the SiNPs serve as the electron conductor and also holds the SiNP during the lithiation/delithiation cycles. Since Si/CNT particles are surrounded by thin protrusions on the surface of Cu current collector, the maximum connectivity between silicon and current collector can be obtained, and excellent cycle stability of the battery can be maintained without any binders

An isoform of the plastid RNA polymerase-associated protein FSD3 negatively regulates chloroplast development

Background Plastid-encoded RNA polymerase (PEP) plays an essential role in chloroplast development by governing the expression of genes involved in photosynthesis. At least 12 PEP-associated proteins (PAPs), including FSD3/PAP4, regulate PEP activity and chloroplast development by modulating formation of the PEP complex. Results In this study, we identified FSD3S, a splicing variant of FSD3; the FSD3 and FSD3S transcripts encode proteins with identical N-termini, but different C-termini. Characterization of FSD3 and FSD3S proteins showed that the C-terminal region of FSD3S contains a transmembrane domain, which promotes FSD3S localization to the chloroplast membrane but not to nucleoids, in contrast to FSD3, which localizes to the chloroplast nucleoid. We also found that overexpression of FSD3S negatively affects photosynthetic activity and chloroplast development by reducing expression of genes involved in photosynthesis. In addition, FSD3S failed to complement the chloroplast developmental defects in the fsd3 mutant. Conclusion These results suggest FSD3 and FSD3S, with their distinct localization patterns, have different functions in chloroplast development, and FSD3S negatively regulates expression of PEP-dependent chloroplast genes, and development of chloroplasts.This work was carried out with the support of the Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ01323901 and PJ01364301) Rural Development Administration, Republic of Korea, and the National Research Foundation of Korea Grant funded by the Korean Government (MOE) [NRF-2019R1A2C1007103]

Jasmonate Zim-Domain Protein 9 Interacts With Slender Rice 1 to Mediate the Antagonistic Interaction Between Jasmonic and Gibberellic Acid Signals in Rice

The jasmonic acid (JA) and gibberellic acid (GA) signaling pathways interact to coordinate stress responses and developmental processes. This coordination affects plant growth and yield, and is mediated by interactions between the repressors of each pathway, the JASMONATE ZIM-DOMAIN PROTEIN (JAZ) and DELLA proteins. In this study we attempted to identify rice (Oryza sativa) JAZs that interact with rice DELLAs such as SLENDER RICE 1 (SLR1). Analysis of protein–protein interactions showed that OsJAZ8 and OsJAZ9 interact with SLR1; OsJAZ9 also interacted with the SLR1-LIKE (SLRL) protein SLRL2. Based on this broader interaction, we explored the function of OsJAZ9 in JA and GA responses by analyzing transcript levels of the JA-responsive gene OsbHLH148 and the GA-responsive gene OsPIL14 in OsJAZ9-overexpressing (OsJAZ9-Ox) and osjaz9 mutant plants. OsbHLH148 and OsPIL14 encode key transcription factors controlling JA and GA responses, respectively, and JA and GA antagonistically regulate their expression. In OsJAZ9-Ox, the expression of OsbHLH148 was downregulated and the expression of OsPIL14 was upregulated. By contrast, in osjaz9 mutants, the expression of OsbHLH148 was upregulated and the expression of OsPIL14 was downregulated. These observations indicated that OsJAZ9 regulates both JA and GA responses in rice, and this finding was supported by the opposite expression patterns of OsDREB1s, downstream targets of OsbHLH148 and OsPIL14, in the OsJAZ9-Ox and osjaz9 plants. Together, these findings indicate that OsJAZ9 suppresses JA responses and promotes GA responses in rice, and the protein–protein interaction between OsJAZ9 and SLR1 is involved in the antagonistic interplay between JA and GA