Enhanced absorption by coherent control in a photonic crystal resonator coupled with a microfiber

Choi, Jihoon,Noh, Heeso The Optical Society 2018 Optics letters Vol.43 No.22

A novel allylic transfer reaction of chirally modified 2-borylbutadiene: synthesis of chiral homoallenyl alcohols

Choi, Jihoon,Lee, Bobin,Yu, Chan-Mo Royal Society of Chemistry 2011 Chemical communications Vol.47 No.13

<P>An enantioselective synthesis of the homoallenyl alcohols was achieved from the reaction of chiral 2-borylbutadiene with aldehydes through an allylic transfer reaction in good yields and enantioselectivities.</P> <P>Graphic Abstract</P><P>An enantioselective synthesis of the homoallenyl alcohols was achieved from the reaction of chiral 2-borylbutadiene with aldehydes through an allylic transfer reaction in good yields and enantioselectivities. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0cc05751g'> </P>

Real-time PCR quantification of 9 periodontal pathogens in saliva samples from periodontally healthy Korean young adults

Choi, Heeyoung,Kim, Eunhye,Kang, Jihoon,Kim, Hyun-Joo,Lee, Ju-Youn,Choi, Jeomil,Joo, Ji-Young Korean Academy of Periodontology 2018 Journal of Periodontal & Implant Science Vol.48 No.4

Purpose: Few studies have examined periodontal pathogens from saliva samples in periodontally healthy young adults. The purposes of this study were to determine the prevalence of periodontopathic bacteria and to quantify periodontal pathogens in saliva samples using real-time polymerase chain reaction (PCR) assays in periodontally healthy Korean young adults under 35 years of age. Methods: Nine major periodontal pathogens were analyzed by real-time PCR in saliva from 94 periodontally healthy young adults. Quantification of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Peptostreptococcus anaerobius, and Eikenella corrodens was performed by DNA copy number measurement. Results: F. nucleatum and E. corrodens were detected in all subjects; the numbers of positive samples were 87 (92.6%), 91 (96.8%), and 90 (95.7%) for P. gingivalis, P. anaerobius, and C. rectus, respectively. Other pathogens were also detected in periodontally healthy subjects. Analysis of DNA copy numbers revealed that the most abundant periodontal pathogen was F. nucleatum, which was significantly more prevalent than all other bacteria (P<0.001), followed by P. anaerobius, P. gingivalis, E. corrodens, C. rectus, and T. denticola. There was no significant difference in the prevalence of each bacterium between men and women. The DNA copy number of total bacteria was significantly higher in men than in women. Conclusions: Major periodontal pathogens were prevalent in the saliva of periodontally healthy Korean young adults. Therefore, we suggest that the development of periodontal disease should not be overlooked in periodontally healthy young people, as it can arise due to periodontal pathogen imbalance and host susceptibility.

Polymer Diffusion from Attractive and Athermal Substrates

Choi, Jihoon,Clarke, Nigel,Winey, Karen I.,Composto, Russell J. American Chemical Society 2017 Macromolecules Vol.50 No.7

<P>Given the exceedingly high interfacial area-to-volume ratios in polymer nanocomposites and the ability to manipulate the polymer/nanoparticle interfacial interactions, manipulating the chain dynamics at these interfaces has immense potential for impacting macroscopic properties. There, the polymer center-of-mass tracer diffusion coefficient (D) from attractive (hydroxyl terminated) and athermal (phenyl-terminated or polymer-grafted) substrates was measured over a range of temperatures and tracer molecular weights using elastic recoil detection. The tracer polymer diffusion slows significantly relative to the bulk when polymers are in direct contact with an attractive substrate and exhibits a weaker molecular weight dependence, D M M. For polymers without direct contacts on the attractive substrates and for athermal substrates, the diffusion coefficients are similar to the bulk case. The temperature dependence of these diffusion coefficients indicates that the slower diffusion at the interfaces is coupled to differences in polymer conformation and smaller fractional free volumes. These deviations from bulk are more pronounced for higher molecular weights and more attractive interfaces.</P>

Differential Cytotoxic Effects of Jaspine B in Various Cancer Cells

Jihoon Lee(이지훈),Kwangik Choi(최광익),Mihwa Kwon(권미화),Dongjoo Lee(이동주),Min-Koo Choi(최민구),Im-Sook Song(송임숙) 한국생명과학회 2016 생명과학회지 Vol.26 No.12

Jaspine B는 석회해면류에서 추출된 sphingosine유도체로 인간 암세포에서의 항암활성이 보고되었다. 그러므로 본 연구는 다양한 인간 암세포주에서 항암활성을 비교하고, 암세포주에서의 Jaspine B의 농도를 측정하여 항암활성과의 연관성을 확인하고자 하였다. 항암활성은 MTT 방법을 이용하여 측정하였고, EC50 값으로 표현하였다. 암세포주내 Jaspine B의 농도는 LC-MS/MS를 이용하여 분석하였다. 항암활성은 세포주마다 다양하게 나타났는데, 유방암과 흑색종 세포주에서 항암활성이 높게 나타났으며(EC50 각각 2.3 μM과 2.6 μM), 신장암세포주에서는 EC50 값이 29.4 μM이었다. 암세포주에서의 EC50 값은 동일한 세포에서의 Jaspine B 농도와 높은 상관성을 나타내었으며(r=0.838), 암세포내 약물농도를 조절하는 것으로 잘 알려진 P-glycoprotein과 breast cancer resistance protein 등의 배출수송계와는 관련이 없음을 확인하였다. 이상의 결과는 세포내 약물농도를 높게 유지하는 것이 항암활성에 매우 중요하며, 세포내 약물농도가 암세포주에 따라 다른 약효를 보이는 원인으로 사료된다. Jaspine B is an anhydrophytosphingosine that is isolated from a marine sponge. Because of its structural similarity to sphingosine, it shows anti-cancer effects in human carcinomas. Therefore, this study aims to investigate its anti-proliferative effect on various cancer cells and to correlate its association with the intracellular accumulation of Jaspine B in relevant cancer cells. The anti-proliferative effect of Jaspine B in various cancer cells was determined by a cell viability test, and the intracellular concentration of Jaspine B in relevant cancer cells was determined using mass spectrometry coupled with liquid chromatography. The correlation coefficient and p value between the cytotoxicity and the cell accumulation of Jaspine B were determined using SPSS 16.1. The cytotoxicity of Jaspine B varied depending on the type of cancer cell when compared the EC50 values of Jaspine B. Breast and melanoma cancer cells were susceptible to Jaspine B, whereas renal carcinoma cells were resistant. The intracellular concentrations of Jaspine B had a reciprocal correlation with the EC50 values in the same cells (r = 0.838). The results suggested that the anti-proliferative effect of Jaspine B was associated with the cellular accumulation of this compound. However, Jaspine B was not a substrate for P-glycoprotein and breast cancer resistance protein, as major efflux pumps caused multidrug resistance. The maintenance of a high intracellular concentration is crucial for the cytotoxic effect of Jaspine B; however, efflux pumps may not be a controlling factor for Jaspine B-related resistance in cancer cells.

FTTP: A Fast Tree Traversal Protocol for Efficient Tag Identification in RFID Networks

Jihoon Choi,Inkyu Lee,Ding-Zhu Du,Wonjun Lee IEEE 2010 IEEE communications letters Vol.14 No.8

<P>This letter presents an efficient tag collision arbitration protocol, viz., the Fast Tree Traversal Protocol (FTTP). It estimates the number of tags using maximum likelihood estimation and adjusts the splitting factor to reduce the identification delay. We show that our protocol effectively reduces the identification delay via the performance analysis and simulation results.</P>

Performance Analysis of an LMS Based Adaptive Feedback Canceller for On-Channel Repeaters

CHOI, Jihoon,JUNG, Young-Ho 'Institute of Electronics, Information and Communi 2015 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb98 No.5

On the Calculation of the Maximal MOT Throughput in T-DMB

Jihoon Choi,Donghwan Lee,Jieun Yu,Kyunghwi Kim,Wonjun Lee IEEE 2007 IEEE transactions on consumer electronics Vol.53 No.3

<P>Digital multimedia broadcasting (DMB) is one of burgeoning communication technologies, which can provide audio, video, and data services to mobile terminals using broadcasting infrastructures. Data services in terrestrial- digital multimedia broadcasting (T-DMB) inherently have the disadvantage of retransmitting a lot of data unnecessarily for reliability. This paper proposes a novel optimized transmission policy using segment size and repetition number variability, which maximizes the object- level throughput as well as improves reliability. The theoretical modeling and simulation results demonstrate that our policy provides a throughput gain over the conventional protocol.</P>

Adaptive MIMO decision feedback equalization for receivers with time-varying channels

Choi, Jihoon,Yu, Heejung,Lee, Y.H. Institute of Electrical and Electronics Engineers 2005 IEEE transactions on signal processing Vol.53 No.11

In an attempt to reduce the computational complexity of vertical Bell Labs layered space time (V-BLAST) processing with time-varying channels, an efficient adaptive receiver is developed based on the generalized decision feedback equalizer (GDFE) architecture. The proposed receiver updates the filter weight vectors and detection order using a recursive least squares (RLS)-based time- and order-update algorithm. The convergence of the algorithm is examined by analysis and simulation, and it is shown that the proposed adaptive technique is considerably simpler to implement than a V-BLAST processor with channel tracking, yet the performances are almost comparable.

Long-Term Outcomes in Patients Undergoing Percutaneous Coronary Intervention with or without Preprocedural Exercise Stress Test

Jihoon Kim,Joo Myung Lee,Taek Kyu Park,Jeong Hoon Yang,Young Bin Song,Jin-Ho Choi,Seung-Hyuk Choi,Hyeon-Cheol Gwon,Sang Hoon Lee,Joo-Yong Hahn 대한의학회 2020 Journal of Korean medical science Vol.35 No.1

Background: Although current guidelines recommend noninvasive stress tests prior to elective percutaneous coronary intervention (PCI), it is unknown whether antecedent exercise stress test (EST) affects the outcomes of patients undergoing PCI for stable ischemic heart disease (SIHD). This study aimed to investigate long-term outcomes in patients undergoing elective PCI with or without EST. Methods: We studied 2,674 patients undergoing elective PCI using drug-eluting stents for SIHD. Patients were divided into the 2 groups: the test group underwent EST with a positive result within 180 days prior to PCI (n = 668), whereas the non-test group did not undergo any noninvasive stress tests (n = 2,006). The primary outcome was all-cause death or myocardial infarction (MI). Results: Over 5 years after the index PCI, the risk of all-cause death or MI was significantly lower in the test group than in the non-test group in overall population (3.3% vs. 10.9%; adjusted hazard ratio [HR], 0.34; 95% confidence interval [CI], 0.22–0.55; P < 0.001), and in propensity score-matched population (668 pairs) (3.3% vs. 6.3%; adjusted HR, 0.52; 95% CI, 0.30–0.89; P = 0.018). However, the incidence of any revascularization was similar between the 2 groups in overall (16.7% vs. 16.8%; adjusted HR, 0.99; 95% CI, 0.79–1.25; P = 0.962) and matched population (16.7% vs. 18.3%; adjusted HR, 0.91; 95% CI, 0.70–1.19; P = 0.509). Conclusion: Patients who underwent elective PCI with EST had a reduced risk of all-cause death or MI than those undergoing PCI without stress tests.