Structure-dependent growth control in nanowire synthesis via on-film formation of nanowires

Shim, Wooyoung,Ham, Jinhee,Noh, Jin-Seo,Lee, Wooyoung Springer 2011 Nanoscale research letters Vol.6 No.1

<P>On-film formation of nanowires, termed OFF-ON, is a novel synthetic approach that produces high-quality, single-crystalline nanowires of interest. This versatile method utilizes stress-induced atomic mass flow along grain boundaries in the polycrystalline film to form nanowires. Consequently, controlling the magnitude of the stress induced in the films and the microstructure of the films is important in OFF-ON. In this study, we investigated various experimental growth parameters such as deposition rate, deposition area, and substrate structure which modulate the microstructure and the magnitude of stress in the films, and thus significantly affect the nanowire density. We found that Bi nanowire growth is favored in thermodynamically unstable films that facilitate atomic mass flow during annealing. A large film area and a large thermal expansion coefficient mismatch between the film and the substrate were found to be critical for inducing large compressive stress in a film, which promotes Bi nanowire growth. The OFF-ON method can be routinely used to grow nanowires from a variety of materials by tuning the material-dependent growth parameters.</P>

On-film formation of bi nanowires with extraordinary electron mobility.

Shim, Wooyoung,Ham, Jinhee,Lee, Kyoung-Il,Jeung, Won Young,Johnson, Mark,Lee, Wooyoung American Chemical Society 2009 NANO LETTERS Vol.9 No.1

<P>A novel stress-induced method to grow semimetallic Bi nanowires along with an analysis of their transport properties is presented. Single crystalline Bi nanowires were found to grow on as-sputtered films after thermal annealing at 260-270 degrees C. This was facilitated by relaxation of stress between the film and the thermally oxidized Si substrate that originated from a mismatch of the thermal expansion. The diameter-tunable Bi nanowires can be produced by controlling the mean grain size of the film, which is dependent upon the thickness of the film. Four-terminal devices based on individual Bi nanowires were found to exhibit very large transverse and longitudinal ordinary magnetoresistance, indicating high-quality, single crystalline Bi nanowires. Unusual transport properties, including a mobility value of 76900 cm(2)/(V s) and a mean free path of 1.35 mum in a 120 nm Bi nanowire, were observed at room temperature.</P>

Isolation of Antimicrobial Strains Inhibiting Vibrio harveyi from Korean traditional salted food

Wooyoung Choi(최우영),Kyung Nam Han(한경남),Eunki Kim(김은기) 한국해양환경·에너지학회 2010 한국해양환경공학회 학술대회논문집 Vol.2010 No.6

Experimental analysis of Radio Multipath Propagation Characteristics for Antenna Tilt in Urban Microcells

( Wooyoung Kwak ) 고려대학교 공학기술연구소 1997 공학기술연구소보 Vol.4 No.-

Activity of Lignin Degrading Enzymes and Ability of Dye Decolorization according to Compounds of Strains by Mushroom Fungi

Wooyoung YANG,Yeonju CHOI,Yumi KIM,Heewook RYU 한국생물공학회 2016 한국생물공학회 학술대회 Vol.2016 No.10

X-86 기반 안드로이드 플랫폼에 ATOM 디바이스 탑재

Wooyoung Jeong, Joongnam Jeon 충북대학교 컴퓨터 정보통신 연구소 2011 컴퓨터정보통신연구 Vol.19 No.1

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Effects of EGF, IGF-I, VEGF and CSF2 on development of porcine conceptus trophectoderm during early pregnancy

Wooyoung Jeong 한국발생생물학회 2014 한국발생생물학회 학술발표대회 Vol.2014 No.9

The majority of early conceptus mortality in pregnancy occurs during the peri-implantation stage, suggesting that this period is important for conceptus viability and the establishment of pregnancy. Successful establishment of pregnancy in all mammalian species depends on the orchestrated molecular events that transpire at the conceptus-uterine interface during the peri-implantation phase. This maternal-conceptus interaction is especially crucial in pigs because in them non-invasive epitheliochorial placentation occurs, in which the pre-implantation phase is prolonged. During the pre-implantation period, conceptus survival and the establishment of pregnancy are known to depend on the developing conceptus receiving an adequate supply of histotroph, which contains a wide range of nutrients and growth factors. Evidence links epidermal growth factor (EGF), insulin- like growth factor-I (IGF-I), vascular endothelial growth factor (VEGF), and colony-stimulating factor 2 (CSF2) to embryogenesis or implantation in various mammalian species; however, in the case of pig, little is known about such functions of these growth factors, especially their regulatory mechanisms at the maternal-conceptus interface. Therefore, the objectives of this study were to determine: 1) the temporal and cell-specific expression of EGF, IGF-I, VEGF, and CSF2 signaling systems in the porcine endometrium during the estrous cycle and early pregnancy; 2) the potential intracellular signaling pathways responsible for the activities of these four factors in primary porcine trophectoderm (pTr) cells; and 3) the changes in cellular activities induced by these promising factors. First, the functional effect and cellular signaling cascades in pTr cells induced by EGF, which exhibits potential growth-promoting activities on the conceptus and endometrium, were investigated. EGFR mRNA and protein were abundant in endometrial luminal epithelia (LE) and glandular epithelia (GE), stratum compactum stroma, and conceptus trophectoderm on Days 13-14 of pregnancy, but not in any other cells of the uterus. EGF treatment of pTr cells increased the abundance of phosphorylated (p)-AKT1, p-ERK1/2 MAPK and p-P90RSK in the nucleus and/or cytoplasm when compared with the levels in control cells. Furthermore, EGF-stimulated phosphorylation of AKT1 and ERK1/2 MAPK were inhibited in pTr cells transfected with an EGFR siRNA, and compared with control siRNA- transfected pTr cells, the EGFR siRNA-transfected pTr cells exhibited an increase in the expression of gene encoding interferon (IFN)-δ and transforming growth factor (TGF) β-1; by contrast, no effect was detected on the expression of the gene encoding IFN-γ. Moreover, EGF stimulated the proliferation and migration of pTr cells, but these stimulatory effects were blocked by pharmacological inhibitors such as SB203580 (a p38 inhibitor), U0126 (a MAPK inhibitor), rapamycin (an MTOR inhibitor), and LY294002 (a PI3K inhibitor). Second, IGF-I was examined. IGF-1 is another promising growth factor that is known to play key roles in reproductive processes; however, little is known about IGF-I-induced functional effects and regulatory mechanisms during peri-implantation in pigs. In this study, endometrial type I IGF receptor (IGF-IR) mRNA was determined to increase substantially during early pregnancy relative to the level during the estrous cycle, and the mRNAs of both IGF-I and IGF-IR were abundant in endometrial LE and GE, stroma and conceptus trophectoderm on Day 12 of pregnancy. Moreover, IGF-I treatment potently increased the amounts of p-AKT1 and, ERK1/2 MAPK in the nucleus and cytoplasm and of RPS6 in the cytosol when compared with the amounts in untreated pTr cells, and IGF-I-induced activation of AKT1 and ERK1/2 was blocked by LY294002. Furthermore, IGF-I strongly stimulated both the proliferation and the migration of pTr cells, but these effects were inhibited by SB203580, U0126, rapamycin and LY294002. Third, this study focused on VEGF, which was identified as a potential mediator of the fetal-maternal dialog that regulates the development of the peri-implantation porcine conceptus. In addition to its known angiogenic effects, VEGF has been suggested to play roles in the development of the early embryo, but VEGF-induced effects on the peri-implantation conceptus remain unknown. Results of this study revealed that endometrial VEGF, VEGF receptor (VEGFR)-1, and VEGFR-2 mRNA levels in endometrial LE and GE, endothelial blood vessels, and scattered cells in the stroma were more abundant during the peri-implantation period of pregnancy than during the estrous cycle. Moreover, VEGF treatment of pTr cells increased the abundance of p-AKT1, p-ERK1/2, p-p70RSK, p-RPS6 and p-4EBP1, and the addition of LY294002 suppressed VEGF-induced phosphorylation of ERK1/2 and AKT1. Furthermore, VEGF potently stimulated both the proliferation and the migration of pTr cells, but these effects were inhibited in the presence of SB203580, U0126, rapamycin and LY294002. The fourth promising cytokine studied was CSF2, which is also known as granulocyte-macrophage colony-stimulating factor (GM-CSF). CSF2 plays a role in facilitating mammalian early embryonic development. In this study, endometrial CSF2 mRNA expression was determined to be increased during the peri-implantation period relative to the mRNA level during the estrous cycle. In pTr cells, CSF2 significantly induced the activation of AKT1, ERK1/2, MTOR, p70RSK, and RPS6, but not of STAT3, and the addition of LY294002 abolished CSF2-induced increases in p-ERK1/2, p-MTOR, and p-AKT1 levels. Furthermore, CSF2 strongly stimulated pTr cell proliferation, an effect that was blocked by U0126, rapamycin and LY294002. Collectively, these results provide new insights into the potential mediators that regulate the development of the peri-implantation conceptus at the fetal-maternal interface. These results indicate that endometrial- and/or conceptus derived EGF, IGF-I, VEGF, and CSF2 critically affect the growth and development of porcine trophectoderm cells, and that these stimulatory effects are coordinately regulated by multiple cellular signaling cascades including the PI3K-AKT and ERK1/2 MAPK pathways during early pregnancy in pigs.

Consumer Perception of GM Food: Factors that Influence Purchasing of GM Food in South Korea

Wooyoung Kim,Kim, Jinkyung Choi 한국식생활문화학회 2018 韓國食生活文化學會誌 Vol.33 No.4

This study examined how the consumers’ perception of GM food affects their purchasing behavior. In addition, this study investigated how the amount of knowledge a consumer has regarding GM food affects their perception of this type of food. The quantitative research method was used to collect data. The data from a self-administered survey, which was conducted in South Korea, was analyzed using descriptive analysis, ANOVA, factor analysis, and multiple regression analysis methods. The results of the survey indicate that most respondents may have unknowingly purchased GM food. Further, the respondents reported that they likely had known about or had heard of GM food. In addition, the survey indicated that the amount of knowledge possessed by the respondents regarding GM food greatly affected their perceptions of this type of food. These findings will contribute to the current GM food market by providing the food market with additional information relating to the consumers’ perceptions of GM food.

Image-based Force Estimation of Deformable Tissue using Depth Map for Single-Port Surgical Robot

Wooyoung Kim,Sungmin Seung,Hongseok Choi,Sukho Park,Seong Young Ko,Jong-Oh Park 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

This paper explains an image-based force estimation of deformable tissue for a small single-port surgical robot. Since the end-effectors of a single-port surgical robot are thin and slender, it is one of challenging issues to install a force-torque sensor on its tip. Instead of using a force sensor, image-based estimation of interacting forces between deformable tissue and surgical end-effectors are proposed in this paper. For this purpose, a depth map extracted from stereo-endoscopic images is compared with an original shape of the deformable tissue which is obtained from the pre-operative medical images. To mitigate computational burden and to distinguish interaction forces of two end-effectors, subsets of whole nodes near contact points are utilized to calculate the interaction forces. This image-based force estimation will be integrated with the developed single-port neurosurgical robotic system to show its efficiency and performance.

The Dropout Rates and Associated Factors in Patients with Mood Disorders in Long-term Naturalistic Treatment

Wooyoung Jung,Eunsoo Moon,Hyun Ju Lim,Je Min Park,Byung Dae Lee,Young Min Lee,Hee Jeong Jeong,Hwagyu Suh,Kyungwon Kim 대한정신약물학회 2024 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.22 No.2

Objective: Although maintenance treatment for mood disorders is important, the treatment discontinuation rate is reported to be high. This study aimed to investigate the dropout rates and associated factors in mood disorders. Methods: The patients in a mood disorder clinic (n = 535) were examined. Demographic and clinical factors, scores of psychometric scales, time to dropout from initial treatment in patients with bipolar disorder (BP) (n = 288) and depressive disorder (DD) (n = 143) were evaluated based on database of the mood disorder clinic. Results: Among the studied patients with BP and DD, 50% showed dropout in 4.05 and 2.17 years, respectively. The mean survival times were 8.90 years in bipolar disorder I (BP-I), 5.19 years in bipolar II disorder, 3.22 years in bipolar disorder not otherwise specified, 4.24 years in major depressive disorder, and 4.03 years in other depressive disorders. In the multivariate Cox proportional hazards regression model in the BP group, diagnosis BP-I was found to be significantly related to the decrease in dropout rate (hazard ratio [HR] = 0.22, p = 0.001); however, increased past suicide attempt number was significantly related to the increase in dropout rate (HR = 1.13, p = 0.017). In the DD group, none of anxiety disorders as comorbidity, increased scores of openness, and extraversion personality were related to the increase in dropout rate. Conclusion: Patients with BP, especially BP-I, showed a lower dropout rate as compared to patients with other mood disorders.