• BMB Reports
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• v.48 no.7
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• pp.367-368
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• 2015

It has long been thought that glucocorticoid receptor (GR) functions as a DNA-binding transcription factor in response to its ligand (a glucocorticoid) and thus regulates various cellular and physiological processes. It is also known that GR can bind not only to DNA but also to mRNA; this observation points to the possible role of GR in mRNA metabolism. Recent data revealed a molecular mechanism by which binding of GR to target mRNA elicits rapid mRNA degradation. GR binds to specific RNA sequences regardless of the presence of a ligand. In the presence of a ligand, however, the mRNA-associated GR can recruit PNRC2 and UPF1, both of which are specific factors involved in nonsense-mediated mRNA decay (NMD). PNRC2 then recruits the decapping complex, consequently promoting mRNA degradation. This mode of mRNA decay is termed "GR-mediated mRNA decay" (GMD). Further research demonstrated that GMD plays a critical role in chemotaxis of immune cells by targeting CCL2 mRNA. All these observations provide molecular insights into a previously unappreciated function of GR in posttranscriptional regulation of gene expression. [BMB Reports 2015; 48(7): 367-368]

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.160.2-160.2
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• 2014

Recently silicon has attracted intense interest as a promising anode material of lithium-ion batteries due to its extremely high capacity of 4200 mA/g (for Li4.2Si) that is much higher than 372 mAh/g (for LiC6) of graphite. However, it seriously suffers from large volume change (even up to 300%) of the electrode upon lithiation, leading to its pulverization or mechanical failure during lithiation/delithiation processes and the rapid capacity fading. To overcome this problem, Si nanowires have been considered. Use of such Si nanowires provides their facile relaxation during lithiation/delithiation without mechanical breaking. To design better Si electrodes, a study to unveil atomic-scale mechanisms involving the volume expansion and the phase transformation upon lithiation is critical. In order to investigate the lithiation mechanism in Si nanowires, we have developed a reactive force field (ReaxFF) for Si-Li systems based on density functional theory calculations. The ReaxFF method provides a highly transferable simulation method for atomistic scale simulation on chemical reactions at the nanosecond and nanometer scale. Molecular dynamics (MD) simulations with the ReaxFF reproduces well experimental anisotropic volume expansion of Si nanowires during lithiation and diffusion behaviors of lithium atoms, indicating that it would be definitely helpful to investigate lithiation mechanism of Si electrodes and then design new Si electrodes.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.81-81
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• 2017

Nanotechnology is of great importance to molecular biology and medicine because life processes are maintained by the action of a series of molecular nanomachines in the cell machinery. Recent advances in nanoscale materials that possess emergent physical properties and molecular organization hold great promise to impact human health in the diagnostic and therapeutic arenas. In order to be effective, nanomaterials need to navigate the host biology and traffic to relevant biological structures, such as diseased or pathogenic cells. Moreover, nanoparticles intended for human administration must be designed to interact with, and ideally leverage, a living host environment. Inspired by nature, we use peptides to transfer biological trafficking properties to synthetic nanoparticles to achieve targeted delivery of payloads. In this talk, development of nanoscale materials will be presented with a particular focus on applications to three outstanding health problems: bacterial infection, cancer detection, and traumatic brain injury. A biodegradable nanoparticle carrying a peptide toxin trafficked to the bacterial surface has antimicrobial activity in a pneumonia model. Trafficking of a tumor-homing nanoprobes sensitively detects cancer via a high-contrast time-gated imaging system. A neuron-targeted nanoparticle carrying siRNA traffics to neuronal populations and silences genes in a model of traumatic brain injury. Unique combinations of material properties that can be achieved with nanomaterials provide new opportunities in translational nanomedicine. This framework for constructing nanomaterials that leverage bio-inspired molecules to traffic diagnostic and therapeutic payloads can contribute on better understanding of living systems to solve problems in human health.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.24-25
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• 2011

Molecular self-assembly has several advantages over other nanofabrication methods. Molecular building blocks ensure ultrafine pattern precision, parallel structure formation allows for mass production and a variety of three-dimensional structures are available for fabricating complex structures. Nevertheless, the molecular interaction for self-assembly generally relies on weak forces such as van der Waals force, hydrogen bonding, or hydrophobic interaction. Due to the weak interaction, the structure formation is usually slow and the degree of ordering is low in a self-assembled structure. To promote self-assembly, directed assembly methods employing prepatterned substrates or external fields have been developed and gathered a great deal of technological attention as a next generation nanofabrication process. In this presentation a variety of directed assembly methods for soft nanomaterials including block copolymers, peptides and carbon nanomaterials will be introduced. Block copolymers are representative self-assembling materials extensively utilized in nanofabrication. In contrast to colloid assembly or anodized metal oxides, various shapes of nanostructures, including lines or interconnected networks, can be generated with a precise tunability over their shape and size. Applying prepatterned substrates$^{1,2}$ or introducing thickness modulation$^3$ to block copolymer thin films allowed for the control over the orientational and positional orderings of self-assembled structures. The nanofabrication processes for metals, semiconductors$^4$, carbon nanotubes$^{5,6}$, and graphene$^{6,7}$ templating block copolymer self-assembly will be presented.

• Genomics & Informatics
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• v.13 no.4
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• pp.102-111
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• 2015

The karyotypes of most species of crocodilians were studied using conventional and molecular cytogenetics. These provided an important contribution of chromosomal rearrangements for the evolutionary processes of Crocodylia and Sauropsida (birds and reptiles). The karyotypic features of crocodilians contain small diploid chromosome numbers (30~42), with little interspecific variation of the chromosome arm number (fundamental number) among crocodiles (56~60). This suggested that centric fusion and/or fission events occurred in the lineage, leading to crocodilian evolution and diversity. The chromosome numbers of Alligator, Caiman, Melanosuchus, Paleosuchus, Gavialis, Tomistoma, Mecistops, and Osteolaemus were stable within each genus, whereas those of Crocodylus (crocodylians) varied within the taxa. This agreed with molecular phylogeny that suggested a highly recent radiation of Crocodylus species. Karyotype analysis also suggests the direction of molecular phylogenetic placement among Crocodylus species and their migration from the Indo-Pacific to Africa and The New World. Crocodylus species originated from an ancestor in the Indo-Pacific around 9~16 million years ago (MYA) in the mid-Miocene, with a rapid radiation and dispersion into Africa 8~12 MYA. This was followed by a trans-Atlantic dispersion to the New World between 4~8 MYA in the Pliocene. The chromosomes provided a better understanding of crocodilian evolution and diversity, which will be useful for further study of the genome evolution in Crocodylia.

• Journal of the Korean Applied Science and Technology
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• v.6 no.1
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• pp.1-7
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• 1989

To developed new process for obtaining maximum molecular weight of anionic acrylamide and acrylic acid copolymer by inverse emulsion polymerization. Concentration of initiator, reducing agent, surfactant and mole ratio of acrylamide-acrylic acid were studied for the process. Semi-batch processes with method of redox, control of reaction temperature, feeding method of monomer and reaction time, was suitable for maximum molecular weight of P(AMAC) from this process obtained $3.09\;{\time}\;10^6({\bar{M}}n.)$ and $4.41\;{\time}\;10^6({\bar{M}}w.)$ in molecular weight measured by the intrinsic viscosity method. inverse emulsion polymerization mechanism of P(AMAC) does not followed the Smith-Ewart and Medvedev theory, but selected for concentration of initiator, reducing agent, surfactant, water solubility of monomer.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1835-1838
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• 2009

Inhibition of human phenylethanolamine N-methyltransferase (hPNMT) has been proposed as a method for the treatment of several mental processes which related on adrenaline metabolism. We performed in silico screening to identify flavonoid inhibitors of hPNMT using automated docking method and selected 9 inhibitor candidates based on ligand score (LigScore) and binding free energy (${\Delta}G_{bind}$) estimation. Among 9 flavonoid candidates, 7 flavonoids belong to flavones while the rest of them belong to flavanone. All candidates have common chemical features; two hydrogen bond interactions with side chain of Lys75 and backbone carbonyl oxygen of Asn39, and two hydrophobic interactions. One hydrophobic site is formed by Val53, Leu262, and Met258 and the other is made up of Phe182, Ala186, Tyr222, and Val269. This study can be helpful to understand the structural features for inhibition of PNMT and showed flavonoids as promising inhibitor candidates for hPNMT.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.85.2-85.2
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• 2012

The interstellar medium (ISM) of galaxies in the galaxy cluster can well be affected by the intracluster medium (ICM). Among many suggested environmental processes, ram pressure stripping can effectively remove gas through the interaction with the ICM. In fact, Cluster galaxies are lower in HI gas mass compared to their field counterparts, and in recent high resolution HI imaging studies, many galaxies in dense environments have been found to be ram pressure stripped in HI. However, it is still under debate whether the ICM pressure can also remove dense molecular gas from the galactic disk, which plays more important role in star formation and hence galaxy evolution. To answer this question, we have obtained high resolution 12/13 CO (2-1) data from the Sub Millimeter Array (SMA) of four galaxies at various HI stripping stages to study how the molecular gas properties change as the galaxy experiences the ICM pressure. We investigate the physical properties of molecular gas with 12/13 CO images. By comparing with other wavelength data, i.e. data(optical, HI, $H{\alpha}$, etc), we discuss how and in which timescale galaxies can migrate from the blue cloud to the red sequence due to ram pressure stripping.

• Molecules and Cells
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• v.39 no.6
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• pp.484-494
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• 2016

Plant cells have a remarkable ability to induce pluripotent cell masses and regenerate whole plant organs under the appropriate culture conditions. Although the in vitro regeneration system is widely applied to manipulate agronomic traits, an understanding of the molecular mechanisms underlying callus formation is starting to emerge. Here, we performed genome-wide transcriptome profiling of wild-type leaves and leaf explant-derived calli for comparison and identified 10,405 differentially expressed genes (> two-fold change). In addition to the well-defined signaling pathways involved in callus formation, we uncovered additional biological processes that may contribute to robust cellular dedifferentiation. Particular emphasis is placed on molecular components involved in leaf development, circadian clock, stress and hormone signaling, carbohydrate metabolism, and chromatin organization. Genetic and pharmacological analyses further supported that homeostasis of clock activity and stress signaling is crucial for proper callus induction. In addition, gibberellic acid (GA) and brassinosteroid (BR) signaling also participates in intricate cellular reprogramming. Collectively, our findings indicate that multiple signaling pathways are intertwined to allow reversible transition of cellular differentiation and dedifferentiation.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.11a
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• pp.195-200
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• 2004

Carbon dioxide ($CO_2$) and methane (CH$_4$) are two major greenhouse Bases. $CO_2$is a stack gas of many industrial processes and the main product of the hydrocarbon combustion. There is recent research interest on the synthesis gas (syngas) formation from $CO_2$ and CH$_4$, via the following reaction: CH$_4$+$CO_2$longrightarrow 2H$_2$+$CO_2$, in order to reduce the greenhouse effects and to synthesize various chemicals, Preliminary experiments were conducted on the conversion of $CO_2$ and CH$_4$ to syngas by making use of a microwave plasma torch at atmospheric pressure. Conversion rates of $CO_2$and CH$_4$ to hydrogen (H$_2$), carbon monoxide (CO) and higher hydrocarbons were investigated using Gas Chromatography (GC) and Fourier Transform Infrared (FTIR). The experimental data indicate that the main products were H$_2$, CO and small amount of higher hydrocarbons, such as ethylene (C$_2$H$_4$).