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Manipulation of Nanofiller and Polymer Structures by Using Equal Channel Angular Extrusion
서영록,원종일 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.1
This study examined how an equal channel angular extrusion (ECAE) process manipulates the structural parameters of nanoclay and polymer in polyamide-6/clay nanocomposites. The ECAE process alters the aspect ratio and the orientation of the nanoclay, as well as the crystalline structures of polyamide-6. After processing the one-pass ECAE (A1), the nanoclays were shortened,well-aligned and closely packed, and the crystalline lamellae were compressed and diagonally well oriented. The two-pass ECAE process with a 180◦ rotation between passes (C2), however, leads to a random dispersion of nanoclay particles, and the recovery of the packed nanoclay interlayer spacing and the compressed lamellar long period.
서영록,정화진 생화학분자생물학회 2004 Experimental and molecular medicine Vol.36 No.6
The p53 tumor supresor has long been en-visaged to preserve genetic stability by the in-duction of cel cycle checkpoints and apopto-sis. More recently, p53 has been implicated to play roles in DNA repair responses to genotoxic stresses. UV-damage and the damage caused by certain chemotherapeutics including cisplatin and nitrogen mustards are known to be repaired which is reportedly regulated by p53 and its downstream genes. There are evidences to sug-gest that the base excision repair (BER) induced by the base-damaging agent methyl methane-sulfonate (MS) is partially deficient in cells lacking functional p53. This result sugests that the activity of BER might be also dependent on the p53 status. In this review, we discuss the posibilities that p53 regulates BER as well as NER; these are one of the most significant po-tentials of p53 tumor supresor for repairing cured from various environmental stresses.
내분비계장애물질인 Bisphenol A에 노출된 선충에서의 유전자 발현 패턴에 관한 연구
서영록,이철우,황정원,정화진,김은경,김현미,정영희,최경희 대한암예방학회 2006 Journal of cancer prevention Vol.11 No.4
Endocrine disruptors are potentially linked to decreases in fertility as well as increases in some types of cancers throughout the animals including humans. Recently, soil-dwelling nematode Caenorhabditis elegans (C.elegans) has been used to monitor the toxicity of endocrine disruptors. In this study, changes in gene expression in C. elegans in response to endocrine disruptor bisphenol A were investigated with a microarray consisting of the nematode-specific cDNA probes. Upon exposure to bisphenol A for 24 hrs, we found 26 different genes that were up- or down-regulated with statistically significant changes. Cytochrome P450 and phosphatse genes were up-regulated, however, heat shock protein, collagen and annexin were down-regulated. Compared to classical tests this C. elegans chip microarray will be useful in generating gene expression profiles at the same time and be used for well regulated biomarker genes to study of toxicogenomics more in detail. (Cancer Prev Res 11, 305-310, 2006)
항종양 인자 p53에 의해서 유도되는 Base Excision Repair (BER)에 관한 연구: DNA Polymerase Beta의 전사적 활성화를 중심으로
서영록,정화진 대한암예방학회 2006 Journal of cancer prevention Vol.11 No.2
BER activity has been known to increase when DNA damage is induced by ionizing radiation (IR), simple alkylating agents, as well as free radicals exposed by endogenous hydrolytic and oxidative processes. The DNA polymerase beta enzyme as an important component of BER pathway, fills in the incised repair patch and participates in removing the overhang created by the displaced strand when treated the alkylating agent such as methyl methanesulfonate (MMS). Recent work has demonstrated that the p53 affects the stability of DNA polymerase beta and apurinic/apyrimidinic (AP) endonuclease interaction although it is not known whether the expression of DNA polymerase beta is regulated by p53 or not. Our data showed that a critical participator of BER activity, DNA polymerase beta can be overexpressed in the wild-type p53 background. We also found that the consensus p53 binding site in the promoter of DNA polymerase beta gene, indicating that the DNA polymerase beta might be transcriptionally regulated by p53. The regulation mechanism of DNA polymerase beta at the transcription level as well as protein interaction between p53 and DNA polymerase beta will provide the potential evidence how repair proteins are regulated to restore DNA damage induced by the environmental carcinogenesis. (Cancer Prev Res 11, 107-113, 2006)
발암성 평가의 분자적 지표 체계의 구축을 위한 AP Quantification Assay을 이용한 DNA Damage 정량화 기법의 최적화
서영록,최원재 대한암예방학회 2006 Journal of cancer prevention Vol.11 No.4
The purpose of our study was to improve an evaluation system for DNA repair activity as one of highlighted molecular pathways for the assessment of environment risk using DNA damage quantification assay. Indeed, DNA repair has been able to use the molecular biomarker system of the environment toxicity assessment with building the quantification assay system to detect AP damage site. In this study, we focused on the optimization of DNA repair analysis in terms of the DNA purification, quantification procedure, and treatment of DNA-damaging agents. Our data showed that the methods were hardly differences between DNA isolation kit and manual purification in RKO human colon cancer cells. In addition, ARP solution concentration was optimized at 100μg/ml in ARP biding reaction. We observed that AP site detection was saturated in the treatment of MMS at 100μM for more than 1 hour. Our study provided the foundation of the novel toxicity assessment system to assay carcinogenic toxic materials such as environmental hazard chemicals heavy metals. Furthermore, the improved assay system for DNA repair might be one of useful for environmental health and cancer prevention. (Cancer Prev Res 11, 278-283, 2006)
서영록,홍윤표,이관중 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.5
This study examines the aerodynamic performances of a wing and multiple propellers through a parametric analysis of wing–propeller interactions. A flow analysis was conducted via simulations based on actuator disk method. The parameters analyzed included the number of propellers, rotating direction, and propeller interval. An increment in the number of propellers increased the wing lift and drag, in addition to the propeller thrust and power. Although the lift-to-drag ratio decreased, the ratio of the wing lift to the propeller power increased. The lift and lift-to-drag ratio of the co-rotating systems were larger than those of the counter rotating systems; however, the lift-to-drag ratio of the latter exceeded that of the former when the number of propellers was seven. An increment in the required thrust increased the lift-to-drag ratio of the counter rotating system in comparison with that of the co-rotating system. Configuration with propellers concentrated at the wing tip increased the lift and drag. However, when the tip propeller was fixed at the wing tip, with the other propellers concentrated in the vicinity of the wing center, the lift increased more, while the drag decreased.
목분/MASEBS/나노클레이가 충전된 PLA 바이오복합재의 기계적, 열적, 형태학적 특성에 관한 연구
서영록,김범준 한국가구학회 2019 한국가구학회지 Vol.30 No.1
Poly(lactic acid) (PLA) was first melt-compounded with wood flour (WF) to produce PLA and PLA/WF biocomposites using twin screw extruder. In order to improve performances further, maleic anhydride grafted styrene-ethylene-butylene-styrene (MASEBS) and nanoclay (NC) were added as a master-batch (MASEBS-NC). This study investigated the effect of MASEBS-NC on the mechanical, thermal and morphological properties of PLA and PLA/WF biocomposites. The incorporation of MASEBS-NC to PLA and PLA/WF biocomposites improved ductility and overall impact strength, but reduced flexural properties. The presence of MASEBS-NC in PLA and PLA/WF biocomposites enhanced the thermal stability by synergistic effect of MASEBS and NC. Morphological properties showed that good interfacial bonding between PLA and WF was achieved by the incorporation of MASEBS-NC. As a results of this study, it seems that the MASEBS-NC in the PLA and PLA/WF biocomposites effectively performed its role as functional filler and coupling agent.