• Title/Summary/Keyword: Center of resistance

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Development of resistance welding technology for producing Ir-192 industrial radiation sources (Ir-192 산업용 방사선원의 생산을 위한 저항용접기술 개발)

  • Han, In-Su;Son, Kwang-Jae;Lee, Jun-Sig;Jang, Kyung-Duk;Park, Ul-Jae
    • Proceedings of the KWS Conference
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    • 2007.11a
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    • pp.288-290
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    • 2007
  • Ir-192 source is one of the most widely used radioisotopes in the field of non-destructive testing applications. To obtain radiation safety it is necessary to take into consideration integrity of welded joint in the production of sealed radiation source. Generally, the quality of a resistance welded joint is strongly influenced by process parameters during the welding process such as current, welding time and applied force. In this study, resistance welding technology and system were developed for sealing of Ir-192 industrial radiation source capsules. In order to evaluate the weld quality in real time, quantitative relationships between process parameters and electrode displacement were also established.

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Damage Detection in Fiber Reinforced Composites Containing Electrically Conductive Phases

  • Shin, Soon-Gi;Hideaki Matsubara
    • The Korean Journal of Ceramics
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    • v.6 no.3
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    • pp.201-205
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    • 2000
  • Fiber reinforced plastic (FRP) composites and ceramic matrix composites (CMC) which contain electrically conductive phases have been designed and fabricated to introduce the detection capability of damage/fracture detection into these materials. The composites were made electrically conductive by adding carbon and TiN particles into FRP and CMC, respectively. The resistance of the conductive FRP containing carbon particles showed almost linear response to strain and high sensitivity over a wide range of strains. After each load-unload cycle the FRP retained a residual resistance, which increased with applied maximum stress or strain. The FRP with carbon particles embedded in cement (mortar) specimens enabled micro-crack formation and propagation in the mortar to be detected in situ. The CMC materials exhibited not only sensitive response to the applied strain but also an increase in resistance with increasing number of load-unload cycles during cyclic load testing. These results show that it is possible to use these composites to detect and/or fracture in structural materials, which are required to monitor the healthiness or safety in industrial applications and public constructions.

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A Long Non-Coding RNA snaR Contributes to 5-Fluorouracil Resistance in Human Colon Cancer Cells

  • Lee, Heejin;Kim, Chongtae;Ku, Ja-Lok;Kim, Wook;Kim Yoon, Sungjoo;Kuh, Hyo-Jeong;Lee, Jeong-Hwa;Nam, Suk Woo;Lee, Eun Kyung
    • Molecules and Cells
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    • v.37 no.7
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    • pp.540-546
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    • 2014
  • Several types of genetic and epigenetic regulation have been implicated in the development of drug resistance, one significant challenge for cancer therapy. Although changes in the expression of non-coding RNA are also responsible for drug resistance, the specific identities and roles of them remain to be elucidated. Long non-coding RNAs (lncRNAs) are a type of ncRNA (> 200 nt) that influence the regulation of gene expression in various ways. In this study, we aimed to identify differentially expressed lncRNAs in 5-fluorouracil-resistant colon cancer cells. Using two pairs of 5-FU-resistant cells derived from the human colon cancer cell lines SNU-C4 and SNU-C5, we analyzed the expression of 90 lncRNAs by qPCR-based profiling and found that 19 and 23 lncRNAs were differentially expressed in SNU-C4R and SNU-C5R cells, respectively. We confirmed that snaR and BACE1AS were down-regulated in resistant cells. To further investigate the effects of snaR on cell growth, cell viability and cell cycle were analyzed after transfection of siRNAs targeting snaR. Down-regulation of snaR decreased cell death after 5-FU treatment, which indicates that snaR loss decreases in vitro sensitivity to 5-FU. Our results provide an important insight into the involvement of lncRNAs in 5-FU resistance in colon cancer cells.

Antibiotic Resistance and Genetic Diversity of Listeria monocytogenes Isolated from Chicken Carcasses in Korea

  • Jang Sung-Sik;Choo Eui-Young;Han Ki-Seon;Miyamoto Takahisa;Heu Sung-Gi;Ryu Sang-Ryeol
    • Journal of Microbiology and Biotechnology
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    • v.16 no.8
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    • pp.1276-1284
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    • 2006
  • Listeria monocytogenes is a well-known high-risk foodborne pathogen that grows at refrigeration temperature and is responsible for outbreaks of listeriosis. We report here the incidence of L. monocytogenes in fresh chicken carcasses and present genetic diversity of L. monocytogenes isolates. In this study, 25 g of chicken carcasses from markets in Korea were examined according to the FDA method, and presumptive isolates were confirmed by multiplex PCR assay. L. monocytogenes isolates were analyzed by Pulsed-Field Gel Electrophoresis using restriction enzymes, ApaI and AscI, to obtain strain-specific DNA fragments profiles. Antimicrobial resistance of L. monocytogenes strains against generally used antibiotics (Penicillin G, Kanamycin, Tetracycline, Vancomycin, Cephalothin, Rifampicin, Erythromycin, Ampicillin, Gentamicin, Streptomycin, and Chloramphenicol) were analyzed by NCCLS protocols to examine the presence of antimicrobial resistance in natural L. monocytogenes. Of a total 274 chicken samples, 81 samples (29.6%) were positive for L. monocytogenes. Listeria innocua (50.1%), Listeria welshimeri (6.9%), and Listeria grayi (11.3%) were also detected. PFGE analysis, using restriction enzymes ApaI and AscI, showed 27 pulsotypes of L. monocytogenes. Antimicrobial resistance analysis confirmed the existence of antimicrobial resistance for penicillin G and tetracycline in isolated L. monocytogenes strains.

$V_2O_5/V/V_2O_5$ based uncooled infrared detector by MEMS technology ($V_2O_5/V/V_2O_5$ 다층박막 및 MEMS기술을 이용한 비냉각형 적외선 감지 소자의 제작)

  • Han, Yong-Hee;Hur, Jae-Sung;Park, In-Hoon;Kim, Kun-Tae;Chi-Anh;Shin, Hyun-Joon;Sung Moon
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.131-131
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    • 2003
  • Surface micromachined uncooled IR detector with the optimized VOx bolometric layer was fabricated based on sandwich structure of the V$_2$O$_{5}$V/V$_2$O$_{5}$. In order to improve the detectivity of the IR detector, we optimized a few factors in the viewpoint of bolometric material. Vanadium oxide thin film is a promising material for uncooled microbolometers due to its high temperature coefficient of resistance at room temperature. It is, however, very difficult to deposit vanadium oxide thin films having high temperature coefficient of resistance and low resistance because of process limits in microbolometer fabrication. In order to increase the responsivity and decrease noise, we increase TCR of bolometric material and decrease room temperature resistance based on the sandwich structure of the V$_2$O$_{5}$V/V$_2$O$_{5}$ by conventional sputter. By oxygen diffusion through low temperature annealing of V$_2$O$_{5}$V/V$_2$O$_{5}$ in oxygen ambient, various mixed phase vanadium oxide was formed and we obtained TCR in range of-1.2 ~-2.6%/$^{\circ}C$ at room temperature resistance of 5~100k$\Omega$.mega$.

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A small molecule approach to degrade RAS with EGFR repression is a potential therapy for KRAS mutation-driven colorectal cancer resistance to cetuximab

  • Lee, Sang-Kyu;Cho, Yong-Hee;Cha, Pu-Hyeon;Yoon, Jeong-Soo;Ro, Eun Ji;Jeong, Woo-Jeong;Park, Jieun;Kim, Hyuntae;Kim, Tae Il;Min, Do Sik;Han, Gyoonhee;Choi, Kang-Yell
    • Experimental and Molecular Medicine
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    • v.50 no.11
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    • pp.12.1-12.12
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    • 2018
  • Drugs targeting the epidermal growth factor receptor (EGFR), such as cetuximab and panitumumab, have been prescribed for metastatic colorectal cancer (CRC), but patients harboring KRAS mutations are insensitive to them and do not have an alternative drug to overcome the problem. The levels of ${\beta}$-catenin, EGFR, and RAS, especially mutant KRAS, are increased in CRC patient tissues due to mutations of adenomatous polyposis coli (APC), which occur in 90% of human CRCs. The increases in these proteins by APC loss synergistically promote tumorigenesis. Therefore, we tested KYA1797K, a recently identified small molecule that degrades both ${\beta}$-catenin and Ras via $GSK3{\beta}$ activation, and its capability to suppress the cetuximab resistance of KRAS-mutated CRC cells. KYA1797K suppressed the growth of tumor xenografts induced by CRC cells as well as tumor organoids derived from CRC patients having both APC and KRAS mutations. Lowering the levels of both ${\beta}$-catenin and RAS as well as EGFR via targeting the $Wnt/{\beta}$-catenin pathway is a therapeutic strategy for controlling CRC and other types of cancer with aberrantly activated the $Wnt/{\beta}$-catenin and EGFR-RAS pathways, including those with resistance to EGFR-targeting drugs attributed to KRAS mutations.

Vacuum infiltration transformation of non-heading Chinese cabbage (Brassica rapa L. ssp. chinensis) with the pinII gene and bioassay for diamondback moth resistance

  • Zhang, Junjie;Liu, Fan;Yao, Lei;Luo, Chen;Zhao, Qing;Huang, Yubi
    • Plant Biotechnology Reports
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    • v.5 no.3
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    • pp.217-224
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    • 2011
  • Non-heading Chinese cabbage (Brassica rapa L. ssp. chinensis) is a popular vegetable in Asian countries. The diamondback moth (DBM), Plutella xylostella (L.), an insect with worldwide distribution, is a main pest of Brassicaceae crops and causes enormous crop losses. Transfer of the anti-insect gene into the plant genome by transgenic technology and subsequent breeding of insect-resistant varieties will be an effective approach to reducing the damage caused by this pest. We have produced transgenic non-heading Chinese cabbage plants expressing the potato proteinase inhibitor II gene (pinII) and tested the pest resistance of these transgenic plants. Non-heading Chinese cabbages grown for 45 days on which buds had formed were used as experimental materials for Agrobacterium-mediated vacuum infiltration transformation. Forty-one resistant plants were selected from 1166 g of seed harvested from the infiltrated plants based on the resistance of the young seedlings to the herbicide Basta. The transgenic traits were further confirmed by the Chlorophenol red test, PCR, and genomic Southern blotting. The results showed that the bar and pinII genes were co-integrated into the resistant plant genome. A bioassay of insect resistance in the second generation of individual lines of the transgenic plants showed that DBM larvae fed on transgenic leaves were severely stunted and had a higher mortality than those fed on the wild-type leaves.

A Practical Method of Prediction of Resistance for Displacement Vessels

  • Doctors, Lawrence J.
    • Journal of Ship and Ocean Technology
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    • v.1 no.2
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    • pp.1-10
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    • 1997
  • The prediction of the total resistance of a ship is generally based on considering it to be a simple sum of the viscous resistance and the wave resistance. An experimental approach for predicting full-size ship resistance on this basis is practical but obviously has the deficiency that a model has to be built for each prototype of interest and the resulting tank tests are time consuming. On the other hand, purely theoretical calculations of the wave resistance, using, for example, the Michell theory, require relatively little computer time and give an excellent portrayal of the overall variation of the vessel resistance as a function of forward speed. Unfortunately, there are sufficient differences between this theory and the measured results to make this method impractical for design purposes. The proposal examined here is to use a data bank of experimental resistance results to modify the theoretical predictions. It is demonstrated that the technique will produce remarkably accurate resistance predictions and can take into account the effects of the water depth, any restriction of canal or river width, as well as the prismatic coefficient, and other geometric parameters.

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Performance Assessment on Temperature Calibration Capability of the Calibration Laboratories Using High-Precision Platinum Resistance Thermometers (고정밀 백금저항온도계를 이용한 교정기관의 온도교정능력 수행평가)

  • Gam, Kee Sool;Lee, Young Hee;Yang, Inseok
    • Journal of Sensor Science and Technology
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    • v.22 no.6
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    • pp.415-420
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    • 2013
  • Calibration capabilities for thermometer calibration by comparison method were assessed using high-precision industrial platinum resistance thermometers (IPRT). It was found in the performance assessment that out of 31 laboratories who participated, 28 laboratories resulted magnitude of En number less than 1 at every calibration points they submitted results in the range from 50 to $500^{\circ}C$. The results of about 75% of the laboratories showed the difference from the assigned values less than 1/10 of the tolerance level of the class B IPRT. This indicates that the participating calibration laboratories performed with satisfactory level that was enough to calibrate IPRTs to significant precision. The sensors used in this work were manufactured and chosen by the criteria of long-term instability less than 4 mK and hysteresis less than 8 mK in the temperature range used in this work. Furthermore, the change in the resistance of the sensors in the calibration temperature range were less than the uncertainty of the calibration, 25 mK (k=2).

Clinical Perspectives to Overcome Acquired Resistance to Anti-Programmed Death-1 and Anti-Programmed Death Ligand-1 Therapy in Non-Small Cell Lung Cancer

  • Lee, Yong Jun;Lee, Jii Bum;Ha, Sang-Jun;Kim, Hye Ryun
    • Molecules and Cells
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    • v.44 no.5
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    • pp.363-373
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    • 2021
  • Immune checkpoint inhibitors have changed the paradigm of treatment options for non-small cell lung cancer (NSCLC). Monoclonal antibodies targeting programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) have gained wide attention for their application, which has been shown to result in prolonged survival. Nevertheless, only a limited subset of patients show partial or complete response to PD-1 therapy, and patients who show a response eventually develop resistance to immunotherapy. This article aims to provide an overview of the mechanisms of acquired resistance to anti-PD-1/PD-L1 therapy from the perspective of tumor cells and the surrounding microenvironment. In addition, we address the potential therapeutic targets and ongoing clinical trials, focusing mainly on NSCLC.