• Tribology and Lubricants
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• v.17 no.3
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• pp.171-178
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• 2001

In order to elucidate the lubricating mechanism of polyolester base oils [POEs], the wear characteristics of 27 kinds of polyolester base oils including mixed POEs were investigated. Their wear results were discussed in terms of the effect of molecular structure on wear performance and compared with those of mineral oil. In addition, the adsorption ability of POEs to reduced iron and their hydrolysis rates were measured and the effect of their molecular structures on the adsorptivity and hydrolysis rate of POEs was discussed, respectively. Finally, the lubricating mechanism anlyzed from these results of wear characteristics, adsorptivity and hydrolysis rate was proposed. That is to say, POEs are firstly adsorbed to friction surface and decomposed by hydrolysis or thermal degradation. Fatty acids obtained by degradation of POEs form adsorption film on friction surface. The larger become cohesive ability among fatty acid molecules in the adsorption film, the better gets the wear performance of POEs.

• Proceedings of the Botanical Society of Korea Conference
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• 1987.07a
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• pp.283-307
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• 1987

Glycinin and $\beta$-conglycinin are the most abundant storage protein in soybean. These proteins are known to be synthesized predominantly during germination and cell expansion phase of seed development for short period, and synthesized not in other tissues. Genes encoding these storage proteins are useful system to study the mechanism of development stage and tissue specific gene expression in eukaryotes, especially plants, at the molecular level. The cDNA and genomic clones coding for glycinin have been isolated and regulation mechanism of the gene expression has been studied. Initially, development and tissue-specific expression of the glycinin gene is regulated at the level of transcription. Post-transcriptional processing is also responsible for delayed accumulation of the mRNA. Translational control of the storage protein gene has not been reported. Post-translational modification is another strategic point to regulate the expression of the gene. It is possible to identify positive and/or negative reguratory clements in vivo by producing transgenic plants agter gene manipulation. Elucidation of activation and repression mechanism of soybean storage protein genes will contribute to the understanding of the other plant and eukaryotic genes at molecular level.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.518-520
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• 2007

Since all essential property of semiconductor materials are structure-sensitive, the understanding of the deformation mechanism and the deformed structure which can be formed in the nanometer-scale devices is very crucial. To investigate the deformation mechanism and the corresponding structures, nanometer-scale contact loading simulations are carried out using molecular dynamics in silicon and gallium-arsenide.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.750-753
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• 2016

Quorum sensing (QS) is a bacterium-to-bacterium cell communication mechanism allowing bio-cell network construction but such mechanism is not well defined yet. We construct a QS-based multiple access network (MAN) and then numerically analyse its average uplink channel capacity as well as BER performance over diffusion-based 3-D molecular communication channels.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2187-2190
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• 2013

• Molecules and Cells
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• v.46 no.1
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• pp.57-64
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• 2023

In eukaryotic cells, a key RNA processing step to generate mature mRNA is the coupled reaction for cleavage and polyadenylation (CPA) at the 3' end of individual transcripts. Many transcripts are alternatively polyadenylated (APA) to produce mRNAs with different 3' ends that may either alter protein coding sequence (CDS-APA) or create different lengths of 3'UTR (tandem-APA). As the CPA reaction is intimately associated with transcriptional termination, it has been widely assumed that APA is regulated cotranscriptionally. Isoforms terminated at different regions may have distinct RNA stability under different conditions, thus altering the ratio of APA isoforms. Such differential impacts on different isoforms have been considered as post-transcriptional APA, but strictly speaking, this can only be considered "apparent" APA, as the choice is not made during the CPA reaction. Interestingly, a recent study reveals sequential APA as a new mechanism for post-transcriptional APA. This minireview will focus on this new mechanism to provide insights into various documented regulatory paradigms.

• Proceedings of the Zoological Society Korea Conference
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• 1997.10b
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• pp.251.1-251
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• 1997

No Abstract, See Full Text

• Journal of Photoscience
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• v.9 no.2
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• pp.221-224
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• 2002

Carcinogenesis can be theoretically divided to intiation step and promotion step. Intiation associates with genetic alterations including p53 tumor suppressor gene and ras oncogene. Promotion involves in clonal expansion of of an initiated cell by epigenetic mechanism, mainly through signal transduction and gene expression. Ultraviolet light (UV) acts as both initiator and promoter. Initiation is closely related with DNA damage induced by UV, including cyclobutane pyrimidine dimers, (6-4) photoproducts and 8-hydroxy-2'-deoxyguanosine. Cyclobutane pyrimidine dimers and (6-4) photoproducts are directly induced by UV, while 8-hydroxy-2'-deoxyguanosine is induced indirectly by the reactive oxygen species. Because initiation is an irreversal genetic event, while promotion is a reversal and epigenetic event, to know the molecular mechanisms of tumor promotion in UV-carcinogenesis is crucial to develop preventive medicine and suppress UV-carcinogenesis. Because ROS is also involved in signal transduction of the cell, anti-oxidant could be the good candidate of anti-promoting agent. Here, we describe the suppressive effect of UV-carcinogenesis by various anti-oxidant including olive oil. In addition, we discuss about the mechanism of UVB-induced expression of cyclooxygenase-2, which might be a representative molecule involved in promotion of UV-carcinogenesis.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.917-923
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• 2009

The maize lipoxgyenase-1 is a non-traditional dual positional specific enzyme and the reaction proceeds via enzyme-initiated catalysis. Bioinformatic analysis indicated that the maize lipoxygenase-1 is structurally more similar to soybean LOX1 than pea LOXN2 in that it has an additional external loop (residues 318-351) in the carboxy-terminal catalytic domain. We analyzed the dependence of product distribution on concentration of linoleic acid and monitored the formation of hydroperoxyoctadecadienoic acid as a function of enzyme concentration. Product distribution was strongly influenced by substrate concentration, such that kinetically-controlled regioisomers were enriched and thermodynamically-controlled regioisomers were depleted at high substrate concentration. Kinetic studies indicated that the formation of hydroperoxyoctadecadienoic acid saturated rapidly in an enzyme concentration-dependent manner, which implied that reactivation by reoxidation of inactive Fe(II) failed to occur. Our results support the previously proposed enzyme-initiated catalytic mechanism of the maize lipoxgyenase-1 and reveals that a substrate molecule serves as a hydrogen atom donor in its enzyme-initiated catalysis.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7435-7439
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• 2015

A failure of a cell to self destruct has long been associated with cancer progression and development. The fact that tumour cells may not instigate cell arrest or activate cell death mechanisms upon cancer drug delivery is a major concern. Autophagy is a mechanism whereby cell material can be engulfed and digested while apoptosis is a self-killing mechanism, both capable of hindering multiplication after cell injury. In particular situations, autophagy and apoptosis seem to co-exist simultaneously or interdependently with the aid of mutual proteins. This review covers roles of microRNAs and chemopreventive agents and makes an attempt at outlining possible partnerships in maximizing cancer cell death with minimal normal cell damage.