• Title/Summary/Keyword: Single-Cell Analysis

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A New Single-Stage PFC AC/DC Converter with Low Link-Capacitor Voltage

  • Lee, Byoung-Hee;Kim, Chong-Eun;Park, Ki-Bum;Moon, Gun-Woo
    • Journal of Power Electronics
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    • v.7 no.4
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    • pp.328-335
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    • 2007
  • A conventional Single-Stage Power-Factor-Correction (PFC) AC/DC converter has a link capacitor voltage problem under high line input and low load conditions. In this paper, this problem is analyzed by using the voltage conversion ratio of the DC/DC conversion cell. By applying this analysis, a new Single-Stage PFC AC/DC converter with a boost PFC cell integrated with a Voltage-Doubler Rectified Asymmetrical Half-Bridge (VDRAHB) is proposed. The proposed converter features good power factor correction, low current harmonic distortions, tight output regulations and low voltage of the link capacitor. An 85W prototype was implemented to show that it meets harmonic requirements and standards satisfactorily with near unity power factor and high efficiency over universal input.

Imaging Single-mRNA Localization and Translation in Live Neurons

  • Lee, Byung Hun;Bae, Seong-Woo;Shim, Jaeyoun Jay;Park, Sung Young;Park, Hye Yoon
    • Molecules and Cells
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    • v.39 no.12
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    • pp.841-846
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    • 2016
  • Local protein synthesis mediates precise spatio-temporal regulation of gene expression for neuronal functions such as long-term plasticity, axon guidance and regeneration. To reveal the underlying mechanisms of local translation, it is crucial to understand mRNA transport, localization and translation in live neurons. Among various techniques for mRNA analysis, fluorescence microscopy has been widely used as the most direct method to study localization of mRNA. Live-cell imaging of single RNA molecules is particularly advantageous to dissect the highly heterogeneous and dynamic nature of messenger ribonucleoprotein (mRNP) complexes in neurons. Here, we review recent advances in the study of mRNA localization and translation in live neurons using novel techniques for single-RNA imaging.

Identification of Ruditapes philippinarum and Meretrix lusoria Larvae Using Single Cell PCR Analysis and Microscopic Observation (Single Cell PCR과 현미경을 통한 바지락 및 백합 유생의 동정)

  • Jung, Seung-Won;Kim, Chang-Soo;Yoo, Jae-Won;Kim, Young-Ok;Lee, Jin-Hwan;Hong, Jae-Sang
    • Ocean and Polar Research
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    • v.32 no.3
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    • pp.247-254
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    • 2010
  • Single cell PCR analysis and light and scanning electron microscopic techniques were utilized to identify free living bivalve larvae in the coastal waters of Tae-an, on the west coast of Korea. Through DNA sequencing, venerid clam larvae were isolated and identified as Ruditapes philippinarum (99% similarity) and Meretrix lusoria (99%). Under microscopic observation, the D-veliger stage of R. philippinarum exhibited symmetrical shoulder angles and an elliptical ventral form. In contrast, M. lusoria displayed asymmetrical shoulder angles and a round ventral form in the umbonal stage. Size of the R. philippinarum larvae was $156{\pm}22{\mu}m$ in length, $126{\pm}12{\mu}m$ in height, $92{\pm}14{\mu}m$ in width with a length: height ratio of 1.23. Meretrix lusoria was $202{\pm}44{\mu}m$ in length, $161{\pm}35{\mu}m$ in height, $96{\pm}38{\mu}m$ in width with a length: height ratio of 1.25. Experimental results indicate that morphological and molecular characteristics provide evidence for the larval identification of these two venerid clam larvae species in nature.

Microfluidic Components and Bio-reactors for Miniaturized Bio-chip Applications

  • Euisik Yoon;Yun, Kwang-Seok
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.9 no.2
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    • pp.86-92
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    • 2004
  • In this paper miniaturized disposable micro/nanofluidic components applicable to bio chip, chemical analyzer and biomedical monitoring system, such as blood analysis, micro dosing system and cell experiment, etc are reported. This system includes various microfluidic components including a micropump, micromixer, DNA purification chip and single-cell assay chip. For low voltage and low power operation, a surface tension-driven micropump is presented, as well as a micromixer, which was implemented using MEMS technology, for efficient liquid mixing is also introduced. As bio-reactors, DNA purification and single-cell assay devices, for the extraction of pure DNA from liquid mixture or blood and for cellular engineering or high-throughput screening, respectively, are presented.

Phase Identification of Al-Ti Alloys Using Convergent Beam Electron Diffraction Pattern (수렴성 빔 전자회절 도형을 이용한 Al-Ti 합금의 상 분석)

  • Kim, Hye-Sung
    • Journal of the Korean Society of Industry Convergence
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    • v.4 no.2
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    • pp.149-155
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    • 2001
  • The use of primitive cell volume and zero order Laue (ZOLZ) pattern is proposed to identify phase in a complex microstructure. Single convergent beam electron pattern containing higher order Laue zone ring from a nanosized region is sufficient to calculate the primitive cell volume of the phase, while ZOLZ pattern is used to determine the zone axis of the crystal. A computer program is used to screen out possible phases from the value of measured cell volume from convergent beam electron diffraction (CBED) pattern. Indexing of ZOLZ pattern follows in the program to find the zone axis of the identification from a single CBED pattern. An example of the analysis is given from the rapidly solidified $Al-Al_3Ti$ system.

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The Workflow for Computational Analysis of Single-cell RNA-sequencing Data (단일 세포 RNA 시퀀싱 데이터에 대한 컴퓨터 분석의 작업과정)

  • Sung-Hun WOO;Byung Chul JUNG
    • Korean Journal of Clinical Laboratory Science
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    • v.56 no.1
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    • pp.10-20
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    • 2024
  • RNA-sequencing (RNA-seq) is a technique used for providing global patterns of transcriptomes in samples. However, it can only provide the average gene expression across cells and does not address the heterogeneity within the samples. The advances in single-cell RNA sequencing (scRNA-seq) technology have revolutionized our understanding of heterogeneity and the dynamics of gene expression at the single-cell level. For example, scRNA-seq allows us to identify the cell types in complex tissues, which can provide information regarding the alteration of the cell population by perturbations, such as genetic modification. Since its initial introduction, scRNA-seq has rapidly become popular, leading to the development of a huge number of bioinformatic tools. However, the analysis of the big dataset generated from scRNA-seq requires a general understanding of the preprocessing of the dataset and a variety of analytical techniques. Here, we present an overview of the workflow involved in analyzing the scRNA-seq dataset. First, we describe the preprocessing of the dataset, including quality control, normalization, and dimensionality reduction. Then, we introduce the downstream analysis provided with the most commonly used computational packages. This review aims to provide a workflow guideline for new researchers interested in this field.

Prevention of P-i Interface Contamination Using In-situ Plasma Process in Single-chamber VHF-PECVD Process for a-Si:H Solar Cells

  • Han, Seung-Hee;Jeon, Jun-Hong;Choi, Jin-Young;Park, Won-Woong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.204-205
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    • 2011
  • In thin film silicon solar cells, p-i-n structure is adopted instead of p/n junction structure as in wafer-based Si solar cells. PECVD is a most widely used thin film deposition process for a-Si:H or ${\mu}c$-Si:H solar cells. For best performance of thin film silicon solar cell, the dopant profiles at p/i and i/n interfaces need to be as sharp as possible. The sharpness of dopant profiles can easily achieved when using multi-chamber PECVD equipment, in which each layer is deposited in separate chamber. However, in a single-chamber PECVD system, doped and intrinsic layers are deposited in one plasma chamber, which inevitably impedes sharp dopant profiles at the interfaces due to the contamination from previous deposition process. The cross-contamination between layers is a serious drawback of a single-chamber PECVD system in spite of the advantage of lower initial investment cost for the equipment. In order to resolve the cross-contamination problem in single-chamber PECVD systems, flushing method of the chamber with NH3 gas or water vapor after doped layer deposition process has been used. In this study, a new plasma process to solve the cross-contamination problem in a single-chamber PECVD system was suggested. A single-chamber VHF-PECVD system was used for superstrate type p-i-n a-Si:H solar cell manufacturing on Asahi-type U FTO glass. A 80 MHz and 20 watts of pulsed RF power was applied to the parallel plate RF cathode at the frequency of 10 kHz and 80% duty ratio. A mixture gas of Ar, H2 and SiH4 was used for i-layer deposition and the deposition pressure was 0.4 Torr. For p and n layer deposition, B2H6 and PH3 was used as doping gas, respectively. The deposition temperature was $250^{\circ}C$ and the total p-i-n layer thickness was about $3500{\AA}$. In order to remove the deposited B inside of the vacuum chamber during p-layer deposition, a high pulsed RF power of about 80 W was applied right after p-layer deposition without SiH4 gas, which is followed by i-layer and n-layer deposition. Finally, Ag was deposited as top electrode. The best initial solar cell efficiency of 9.5 % for test cell area of 0.2 $cm^2$ could be achieved by applying the in-situ plasma cleaning method. The dependence on RF power and treatment time was investigated along with the SIMS analysis of the p-i interface for boron profiles.

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Protective Effects of Ginkgo Biloba Leaf Extract(GBE) against 1,2,4-benzenetriol Induced Toxicity in Vitro (Ginkgo biloga 잎 추출물의 1,2,4-benzenetriol에 대한 항산화 효과에 대한 연구)

  • 이영준;김태연;정해원
    • Journal of Environmental Health Sciences
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    • v.27 no.1
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    • pp.124-130
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    • 2001
  • Ginkgo biliba has been used for bronchitis and asthma in oriental countries and its leaf extract(GBE) contains 24% ginkgoflavone glycoside and 6% terpenoid. Flavonoids and terpenoids are known to have various antioxidant effects such as scavenging of free radicals and chelation of transtional metals. Antioxidant effect of GBE against 1,2,4-benzenetriol(BT), one of toxic metabolites of benzene, was demonstrated throughbsister chromatid exchange(SCE) analysis, single cell gel electrophoresis(SCGE) analysis, DNA cleavage assay and lipid peroxidation production analysis. The means of SCE frequencies at 10, 25 and 50$\mu$M concentration of BT were 7.72, 8.02, 9.22 respectively. In addition of GBE with concentration of 50, 200 and 500$\mu\textrm{g}$/$m\ell$, SCE frequencies were decreased significantly.(p<0.05) According to SCGE analysis, BT induced DNA damage in a dose-dependent manner at concentration of 10 and 50 $\mu$m and the DNA damage induced by BT was significantly protected by GBE(p<0.001). No genotoxicity was observed by GBE treatment alone on DNA cleavage. The effect of BT on lipid peroxidation product, Malondiadehyde(MDA), was increased with concentration of BT(10 and 50 $\mu$M) and reduction in MDA was noted when GBE was added. From above results it is suggested that GBE could protect the cell and DNA from pro-oxidant effect by reactive oxigen species induced by BT.

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Dynamic Characteristics of Composite Thin-Walled Beams with a Chord-Wise Asymmetric Cross-Section: II. Multi-Cell (시위 방향 비대칭 단면의 복합재료 박벽보의 동특성 연구: II. 다중-셀)

  • Kim, Keun-Taek
    • Journal of Aerospace System Engineering
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    • v.13 no.2
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    • pp.51-59
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    • 2019
  • Subsequently, Part I [1], which was about the single-cell model, a composite thin-walled beam with a multi-cell of chord-wise asymmetric cross-section, was selected in this study. Moreover, the theoretical dynamic characteristics of the model were analyzed. For this analysis, mathematical modeling was performed by considering the warping restraint effects, transverse shear effects, taper ratio and cross-section ratio. Similar to part I, the mass, stiffness coefficients and Eigen frequencies of the multi-cell section considered were investigated. In particular, the comparison between the multi-cell and single-cell sections and the effects of the cross-section ratio and taper ratio of the model on the Eigen frequencies were analyzed. However, the results compared when the asymmetry of the section was considered and warping function were not corrected.