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The Cellular Response to Graphene Oxide and Its Related Nano-derivatives
( Jong Wook Shin ),( Chang Seok Park ),( Jae Kook Nam ),( Young Ae Baik ),( Jae Woo Jung ),( Jae Chol Choi ),( Jae Yeol Kim ),( In Won Park ),( Byoung Whui Choi ),( Kyung Soon Choi ),( Juhyun Park ),( 대한결핵 및 호흡기학회 2012 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.114 No.0
The graphene which is an allotrope of carbon has the honeycombing structure of one-atom-thick planar sheets. it is used in modern electronic, informative technologies sensors and drug delivery system. Graphene oxide (GO) has oxygen functional groups on the graphene plane. We performed this experiment to define the cellular effect of GO. GO was prepared by the modified Hummers method using 2 g of graphite powder. After sequential procedure, GO in water was used for experiment. U-937, Raw264.7 cells and A549 cells were cultivated with GO and related nanoparticles. We checked the microscopic charac-teristics, MTT assay and Western blotting. The X-ray diffraction patterns showed that the pristine graphite had a peak centered at 2θ=26.5o (d=0.33 nm). This peak was shifted to 2θ=11.3o (d=0.78 nm) after applying the Hummers method. U937 cells aggregated sround GO. During 48 hours, modified GO with methyl group (DA-GO) and SDS-hydrazine GO(SDS-HYDrGO) diminished A549 proliferation than GO. In contrast, GO inhibited proliferation of Raw264.7 cells than DA-GO and SDS-HYD rGO. The shifting from LC3B-I to LC3B-II was minimal in GO, DA-GO, SDS-HYD rGO. In conclusion, GO in water may be phagocytosed by mononuclear cells. GO and its ligand-modified derivatives may affect differentially on proliferation or survival in airway epithelial cells and mononuclear cells. Acknowledgement: This research was supported by Mid-career Research Program (2011-0028752) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology.
Phase Jitter Analysis of Overlapped Signals for All-to-All TWSTFT Operation
Juhyun Lee,Ju-Ik Oh,Joon Hyo Rhee,Gyeong Won Choi,Young Kyu Lee,Jong Koo Lee,Sung-hoon Yang 사단법인 항법시스템학회 2023 Journal of Positioning, Navigation, and Timing Vol.12 No.3
Time comparison techniques are necessary for generating and keeping Coordinated Universal Time (UTC) and distributing standard time clocks. Global Navigation Satellite System (GNSS) Common View, GNSS All-in-View, Two-Way Satellite Time and Frequency Transfer (TWSTFT), Very Long Baseline Interferometry (VLBI), optical fiber, and Network Time Protocol (NTP) based methods have been used for time comparison. In these methods, GNSS based time comparison techniques are widely used for time synchronization in critical national infrastructures and in common areas of application such as finance, military, and wireless communication. However, GNSS-based time comparison techniques are vulnerable to jamming or interference environments and it is difficult to respond to GNSS signal disconnection according to the international situation. In response, in this paper, Code-Division Multiple Access (CDMA) based All-to-All TWSTFT operation method is proposed. A softwarebased simulation platform also was designed for performance analysis in multi-TWSTFT signal environments. Furthermore, code and carrier measurement jitters were calculated in multi-signal environments using the designed simulation platform. By using the technique proposed in this paper, it is anticipated that the TWSTFT-based time comparison method will be used in various fields and satisfy high-performance requirements such as those of a GNSS master station and power plant network reference station.
Regulation of MicroRNA-Mediated Developmental Changes by the SWR1 Chromatin Remodeling Complex
Choi, Kyuha,Kim, Juhyun,Muller, Sebastian Y.,Oh, Mijin,Underwood, Charles,Henderson, Ian,Lee, Ilha American Society of Plant Biologists 2016 Plant Physiology Vol.171 No.2
<P>The ATP-dependent SWR1 chromatin remodeling complex (SWR1-C) exchanges the histone H2A-H2B dimer with the H2A.Z-H2B dimer, producing variant nucleosomes. Arabidopsis thaliana SWR1-C contributes to the active transcription of many genes, but also to the repression of genes that respond to environmental and developmental stimuli. Unlike other higher eukaryotic H2A.Z deposition mutants (which are embryonically lethal), Arabidopsis SWR1-C component mutants, including arp6, survive and display a pleiotropic developmental phenotype. However, the molecular mechanisms of early flowering, leaf serration, and the production of extra petals in arp6 have not been completely elucidated. We report here that SWR1-C is required for miRNA-mediated developmental control via transcriptional regulation. In the mutants of the components of SWR1-C such as arp6, sef, and pie1, miR156 and miR164 levels are reduced at the transcriptional level, which results in the accumulation of target mRNAs and associated morphological changes. Sequencing of small RNA libraries confirmed that many miRNAs including miR156 decreased in arp6, though some miRNAs increased. The arp6 mutation suppresses the accumulation of not only unprocessed primary miRNAs, but also miRNA-regulated mRNAs in miRNA processing mutants, hyl1 and serrate, which suggests that arp6 has a transcriptional effect on both miRNAs and their targets. We consistently detected that the arp6 mutant exhibits increased nucleosome occupancy at the tested MIR gene promoters, indicating that SWR1-C contributes to transcriptional activation via nucleosome dynamics. Our findings suggest that SWR1-C contributes to the fine control of plant development by generating a balance between miRNAs and target mRNAs at the transcriptional level.</P>
Choi, Yeol Kyo,Lee, Dabin,Lee, Sang Yup,Shin, Tae Joo,Park, Juhyun,Ahn, Dong June American Chemical Society 2017 Macromolecules Vol.50 No.17
<P>Revealing the nature of chain packing in conjugated polymer nanoparticles (CPNs) is one of the important issues to polymer physics research. Surfactant-stabilized CPNs in water show significantly enhanced luminescence intensity in comparison to small molecular organic dyes and single polymer chains dissolved in solvents. The importance of the conjugated polymer structure in nanomaterials is undoubted. However, details of the relationship between alignment of conjugated polymer backbone in CPNs and its luminescent property have not been established. Furthermore, there are yet no methods that can predict the atom-resolved structure of conjugated polymer in the CPNs. Herein, we employ coarse-grained (CG) molecular dynamic simulations to investigate the structure of phase-separated film and the film shattering process for a mixture of poly[2,6-(4,4-bis(2-ethylhexyl)-4<I>H</I>-cyclopenta[2,1-<I>b</I>;3,4-<I>b</I>′]-dithiophene)-<I>alt</I>-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and 1,2-dioctanoyl-<I>sn</I>-glycero-3-phosphocholine (D8PC). The π-π stacked structure of PCPDTBT is significantly enhanced when the ratio of D8PC increases in both dried and water exposed film. We also show that the amount of D8PC is at least 2.5 times larger than that of PCPDTBT to wrap the conjugated polymer chain, and the direct retrieval of atomistic details is achieved through back-mapping from the morphology of CG. Finally, we confirmed that conjugated backbones inside the nanoparticles were completely shielded from the aqueous solution by the dense layers of alkyl chains, resulting in remarkably enhanced chain packing. These simulated results are correlated with experimentally observed structure through UV-vis-near-infrared (UV-vis-NIR) spectrometry, scanning electron microscopy (SEM), particle size analyzer (PSA), transmission electron microscopy (TEM), and grazing-incidence X-ray diffraction (GIXD).</P> [FIG OMISSION]</BR>
Choi, Eun-Ji,Lee, Je-Hwan,Lee, Jung-Hee,Park, Han-Seung,Ko, Sun-Hye,Hur, Eun-Hye,Moon, Juhyun,Goo, Bon-Kwan,Kim, Yeonhee,Seol, Miee,Lee, Young-Shin,Kang, Young-Ah,Jeon, Mijin,Woo, Ji Min,Lee, Kyoo-Hyu Elsevier 2018 Leukemia research Vol.68 No.-
<P><B>Abstract</B></P> <P>This retrospective analysis compared anthracyclines (as part of an induction regimen) in 128 newly diagnosed <I>FLT3</I>-ITD-mutated AML patients. Induction regimens comprised high-dose daunorubicin (HD-DN; 90 mg/m<SUP>2</SUP>/d × 3d; n = 44), standard-dose daunorubicin (SD-DN; 45 mg/m<SUP>2</SUP>/d × 3d; n = 51), or idarubicin (IDA; 12 mg/m<SUP>2</SUP>/d × 3d; n = 33) in combination with cytarabine (100–200 mg/m<SUP>2</SUP>/d × 7d). Fifty-three patients showing persistent leukemia on interim bone marrow examination received a second course of induction chemotherapy comprising 2 days of daunorubicin (45 mg/m<SUP>2</SUP>/d) or IDA (8 or 12 mg/m<SUP>2</SUP>/d) in addition to 5 days of cytarabine. Complete remission (CR) rates were 77.3%, 56.9%, and 69.7% for HD-DN, SD-DN, and IDA, respectively (<I>P</I> = 0.101; HD-DN <I>vs.</I> SD-DN, <I>P</I> = 0.036; HD-DN <I>vs.</I> IDA, <I>P</I> = 0.453; IDA <I>vs.</I> SD-DN, <I>P</I> = 0.237). The HD-DN showed higher overall survival (OS) and event-free survival (EFS) than SD-DN and IDA: the differences between HD-DN and SD-DN (<I>P</I> = 0.009 for OS and <I>P</I> = 0.010 for EFS) were statistically significant.</P> <P>Results of <I>in vitro</I> studies using <I>FLT3</I>-ITD-mutated cell lines supported these findings. In conclusion, HD-DN improved the CR rate, OS, and EFS of <I>FLT3</I>-ITD-mutated AML patients. HD-DN also tended to yield better outcomes than IDA, though the difference was not significant. The superiority of HD-DN over IDA should be confirmed in future studies.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>FLT3</I>-ITD-mutated AML patients benefited from high-dose daunorubicin. </LI> <LI> High-dose daunorubicin seems to yield better results than idarubicin. </LI> <LI> The results of <I>in vitro</I> studies support these findings. </LI> </UL> </P>
Choi, Hyeongsu,Lee, Jeongsu,Shin, Seokyoon,Lee, Juhyun,Lee, Seungjin,Park, Hyunwoo,Kwon, Sejin,Lee, Namgue,Bang, Minwook,Lee, Seung-Beck,Jeon, Hyeongtag IOP Pub 2018 Nanotechnology Vol.29 No.21
<P>Representative tin sulfide compounds, tin monosulfide (SnS) and tin disulfide (SnS<SUB>2</SUB>) are strong candidates for future nanoelectronic devices, based on non-toxicity, low cost, unique structures and optoelectronic properties. However, it is insufficient for synthesizing of tin sulfide thin films using vapor phase deposition method which is capable of fabricating reproducible device and securing high quality films, and their device characteristics. In this study, we obtained highly crystalline SnS thin films by atomic layer deposition and obtained highly crystalline SnS<SUB>2</SUB> thin films by phase transition of the SnS thin films. The SnS thin film was transformed into SnS<SUB>2</SUB> thin film by annealing at 450 °C for 1 h in H<SUB>2</SUB>S atmosphere. This phase transition was confirmed by x-ray diffractometer and x-ray photoelectron spectroscopy, and we studied the cause of the phase transition. We then compared the film characteristics of these two tin sulfide thin films and their switching device characteristics. SnS and SnS<SUB>2</SUB> thin films had optical bandgaps of 1.35 and 2.70 eV, and absorption coefficients of about 10<SUP>5</SUP> and 10<SUP>4</SUP> cm<SUP>−1</SUP> in the visible region, respectively. In addition, SnS and SnS<SUB>2</SUB> thin films exhibited p-type and n-type semiconductor characteristics. In the images of high resolution-transmission electron microscopy, SnS and SnS<SUB>2</SUB> directly showed a highly crystalline orthorhombic and hexagonal layered structure. The field effect transistors of SnS and SnS<SUB>2</SUB> thin films exhibited on–off drain current ratios of 8.8 and 2.1 × 10<SUP>3</SUP> and mobilities of 0.21 and 0.014 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively. This difference in switching device characteristics mainly depends on the carrier concentration because it contributes to off-state conductance and mobility. The major carrier concentrations of the SnS and SnS<SUB>2</SUB> thin films were 6.0?×?10<SUP>16</SUP> and 8.7?×?10<SUP>13</SUP> cm<SUP>−3</SUP>, respectively, in this experiment.</P>