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RISS 인기검색어
- 검색키워드
- 저자 : Jonghwa Lee (검색결과 424 건)
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Lee, Jonghwa,Shin, Yongho,Lee, Junghak,Lee, Jiho,Kim, Byung Joon,Kim, Jeong-Han Elsevier 2018 CHEMOSPHERE - Vol.207 No.-
<P><B>Abstract</B></P> <P>In this study, we developed a multiresidue method for the analysis of 310 pesticides in representative agricultural produce (brown rice, orange, and spinach) using ultra high performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) combined with a modified QuEChERS procedure. The optimal mobile phase composition (Methanol containing 5 mM ammonium formate and 0.1% formic acid) produced high sensitivity and reliable results. Also, the relationship between injection volume and repeatability of peak area was investigated. Most of the target pesticides had a limit of quantitation under 10 ng g<SUP>−1</SUP>, and correlation coefficients (<I>r</I> <SUP>2</SUP>) > 0.99 in matrix-matched standards within the range of 1–100 ng g<SUP>−1</SUP>. To validate the optimized method, recovery tests were performed with each of the crops at 10 and 50 ng g<SUP>−1</SUP> spiking levels (<I>n</I> = <I>5</I>). Satisfactory recoveries were achieved showing that 86.8–88.7% (at 10 ng g<SUP>−1</SUP>) and 91.9–96.1% (at 50 ng g<SUP>−1</SUP>) of the pesticides met the validation criteria (recoveries in the range of 70–120% and relative standard deviation ≤ 20%). Fifteen compounds were found to show a loss of recovery due to adsorption by primary and secondary amine or graphite carbon black. In the case of brown rice, 86.1% of pesticides showed an insignificant matrix effect (<±20%), while 35.2% and 41.6% of pesticides in orange and spinach were in that range, respectively. Sixteen apple samples from local markets were analyzed to evaluate the applicability of the optimized method. Nineteen pesticides were detected, of which the concentrations were lower than the maximum residue limit.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The protocol can analyze large number of pesticides (310 analytes) with modified QuEChERS and LC-MS/MS. </LI> <LI> A relationship between injection volumes and repeatability in LC-MS/MS analysis. </LI> <LI> Mobile phase compositions were compared for best sensitivity in LC-MS/MS. </LI> <LI> The method is reproducible and sensitive. </LI> <LI> It was successfully used to determine pesticide residues in market samples. </LI> </UL> </P>
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Lee, Jonghwa,Kim, Leesun,Shin, Yongho,Lee, Junghak,Lee, Jiho,Kim, Eunhye,Moon, Joon-Kwan,Kim, Jeong-Han American Chemical Society 2017 Journal of agricultural and food chemistry Vol.65 No.16
<P>A multiresidue method for the simultaneous and rapid analysis of 360 pesticides in representative agricultural produce (brown rice, orange, spinach, and potato) was developed using a modified QuEChERS procedure combined with gas chromatography tandem mass spectrometry (GC-MS/MS). Selected reaction monitoring transition parameters (e.g., collision energy, precursor and product ions) in MS/MS were optimized to achieve the best selectivity and sensitivity for a wide range of GC-amenable pesticides. A short (20 m) microbore (0.18 mm i.d.) column resulted in better signal-to-noise ratio with reduced analysis time than a conventional narrowbore column (30 m X 0.25 mm i.d.). The priming injection dramatically increased peak areas by masking effect on a new GC liner. The limit of quantitation was <0.01 mg/kg, and the correlation coefficients (r(2)) of matrix-matched standards were >0.99 within the range of 0.0025-0.1 mg/kg. Acetonitrile with 0.1% formic acid without additional buffer salts was used for pesticide extraction, whereas only primary secondary amine (PSA) was used for dispersive solid phase extraction (dSPE) cleanup, to achieve good recoveries for most of the target analytes. The recoveries ranged from 70 to 120% with relative standard deviations of <= 20% at 0.01 and 0.05 mg/kg spiking levels (n = 6) in all samples, indicating acceptable accuracy and precision of the method. Seventeen real samples from local markets were analyzed by using the optimized method, and 14 pesticides in 11 incurred samples were found at below the maximum residue limits.</P>
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Kyeong Won Lee,Young Jun An,Janet Lee,Ye-Eun Jung,In Young Ko,Jonghwa Jin,Ji Hoon Park,Won Kyu Lee,Kiweon Cha,Sun-Shin Cha,Jung-Hyun Lee,Hyung-Soon Yim 한국미생물학회 2022 The journal of microbiology Vol.60 No.11
Fibroblast growth factor 11 (FGF11) is one of intracrine FGFs (iFGFs), which function within cells. Unlike canonical FGFs, FGF11 remains intracellularly and plays biological roles in FGF receptor (FGFR)-independent manner. Here, we established an expression system of recombinant FGF11 proteins in E. coli and investigated whether the extracellular administration of FGF11 can activate cellular signaling. Human FGF11 has two isoforms, FGF11a and FGF11b, depending on the presence of nuclear localization sequences (NLSs) in the N-terminus. Because these two isoforms are unstable, we prepared an FGF11a-Mut by substituting three cysteine residues in the NLS with serine and FGF11b-ΔC with C-terminal truncation. The introduction of mutation in the NLS improved the solubility of FGF11 prepared from E. coli. Exogenous addition of FGF11b and FGF11b-ΔC to BALB3T3 increased cell proliferation, while FGF11a-Mut exerted no effect. FGF11b-ΔC showed higher cell proliferation activity and FGFR signaling than FGF11b. The cell-proliferating activities of FGF11b and FGF11b-ΔC were blocked by an FGFR1 inhibitor or a recombinant FGFR1, confirming the FGFR1- dependent extracellular activity of FGF11b. The analysis of circular dichroism suggested that the C-terminus of FGF11 has an α-helical structure, which may affect its interaction with FGFR1. These results suggest that the N-and C-terminus of recombinant FGF11 are involved in the activation of FGFR1. The above results provide novel insights into the function and mechanism of FGF11 that may aid the development of useful ligands for FGFR regulation.
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Edge-adaptive Demosaicking for Artifact Suppression Along Line Edges
Jonghwa Lee,Taeuk Jeong,Chulhee Lee IEEE 2007 IEEE transactions on consumer electronics Vol.53 No.3
<P>In this paper, we present an edge-adaptive demosaicking method for artifact suppression along line edges. Although various demosaicking methods have been proposed, they still suffer from artifacts along line edges. In order to suppress these undesirable artifacts, the proposed method first determines the pattern of line edges and interpolates missing pixels along the detected direction during initial interpolation. Then, refinement and calibration processes are carried out in series to improve image quality. Experimental results demonstrate that the proposed method produces visually pleasing images and outperforms existing demosaicking methods in terms of the peak signal-to-noise ratio (PSNR) and the mean squared error of S-CIELAB.</P>
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Lee, Chan-Mi,Park, Jonghwa,Kim, Backki,Seo, Jeonghwan,Lee, Gileung,Jang, Su,Koh, Hee-Jong Springer US 2015 Rice Vol.8 No.-
<P><B>Background</B></P><P>Grain size is one of the key factors determining yield and quality in rice. A large number of genes are involved in the regulation of grain size parameters such as grain length and grain width. Different alleles of these genes have different impacts on the grain size traits under their control. However, the combined influence of multiple alleles of different genes on grain size remains to be investigated. Six key genes known to influence grain size were investigated in this study: <I>GS3</I>, <I>GS5</I>, <I>GS6</I>, <I>GW2</I>, <I>qSW5</I>/<I>GW5</I>, and <I>GW8</I>/<I>OsSPL16.</I> Allele and grain measurement data were used to develop a regression equation model that can be used for molecular breeding of rice with desired grain characteristics.</P><P><B>Results</B></P><P>A total of 215 diverse rice germplasms, which originated from or were developed in 28 rice-consuming countries, were used in this study. Genotyping analysis demonstrated that a relatively small number of allele combinations were preserved in the diverse population and that these allele combinations were significantly associated with differences in grain size. Furthermore, in several cases, variation at a single gene was sufficient to influence grain size, even when the alleles of other genes remained constant. The data were used to develop a regression equation model for prediction of rice grain size, and this was tested using data from a further 34 germplasms. The model was significantly correlated with three of the four grain size-related traits examined in this study.</P><P><B>Conclusion</B></P><P>Rice grain size is strongly influenced by specific combinations of alleles from six different genes. A regression equation model developed from allele and grain measurement data can be used in rice breeding programs for the development of new rice varieties with desired grain size and shape.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s12284-015-0066-1) contains supplementary material, which is available to authorized users.</P>
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Low-Complexity ICI Reduction Method for OFDM Systems With Large Subcarrier Numbers
Lee, Jinyong,Lee, Jonghwa,Kim, Jaehoon,Kim, Younglok IEEE 2015 IEEE Transactions on Vehicular Technology VT Vol.64 No.8
<P>The intercarrier interference (ICI) resulting from the loss of orthogonality caused by the time-varying property of the propagation channels degrades the data detection performance of orthogonal frequency-division multiplexing (OFDM)-based wireless communication systems. Further, the severity of the problem increases when the mobile speed is relatively higher than the number of subcarriers. In this paper, a time-varying filtering method is proposed that reduces ICI by obtaining an approximation of linear system solutions such as zero-forcing (ZF) and minimum mean square error (MMSE). The update rates of the time-varying filter coefficients, which are actually the minimum phase versions of the channel impulse responses, are also minimized to reduce the computational complexity. The simulation results show that the proposed method with lower complexity effectively reduces ICI such that practical application is deemed feasible for OFDM systems with a large number of subcarriers.</P>
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Validation protocol for whole-body dosimetry in an agricultural exposure study
Lee, Jiho,Kim, Eunhye,Shin, Yongho,Lee, Jonghwa,Lee, Junghak,Maasfeld, Wolfgang,Kim, Jeong-Han The Korean Society for Applied Biological Chemistr 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.1
Agricultural workers exposed to pesticides can experience adverse health impacts depending on toxicity and exposure amount. Whole-body dosimetry (WBD) is the most reliable, practical, and realistic method for measuring exposure. Since validation of analytical and experimental methodologies is critical for quantitative determination of exposure, we conducted a validation procedure to design an essential protocol for WBD exposure studies. Using the fungicide kresoxim-methyl, matrixmatched standards were prepared with various matrices including outer cloth, inner cloth, washing solution for gloves and hands, gauze, and glass fiber filter (IOM sampler) to determine the instrumental limit of quantitation for high-performance liquid chromatography (HPLC) (2 ng) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) (10 pg). Method limits of quantitation (MLOQ) were also set for HPLC (0.1 mg/L) and LC-MS/MS (0.005 mg/L). We observed good analysis repeatability (coefficient of variation < 6%), and the linearity of the calibration curves was reasonable ($r^2$ > 0.998) in the range of 0.001-10 mg/L in various matrices. Recovery tests were carried out at three levels of concentration (MLOQ, 10 MLOQ, and 100 MLOQ) and resulted in good recoveries (72.7-105.6%). We did not observe breakthrough of the compound in tests of holding capacity for glass fiber pesticide filters. The procedures established in the present study are applicable as an essential, comprehensive protocol for exposure assessment studies using WBD.
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Virus-mimetic polymer nanoparticles displaying hemagglutinin as an adjuvant-free influenza vaccine
Lee, Chaeyeon,Jeong, Jonghwa,Lee, Taeheon,Zhang, Wei,Xu, Li,Choi, Ji Eun,Park, Ji Hyun,Song, Jae Kwang,Jang, Sinae,Eom, Chi-Yong,Shim, KyuHwan,Seong Soo, A.An,Kang, Young-Sun,Kwak, Minseok,Jeon, Hyeon Elsevier 2018 Biomaterials Vol.183 No.-
<P><B>Abstract</B></P> <P>The generation of virus-mimetic nanoparticles has received much attention in developing a new vaccine for overcoming the limitations of current vaccines. Thus, a method, encompassing most viral features for their size, hydrophobic domain and antigen display, would represent a meaningful direction for the vaccine development. In the present study, a polymer-templated protein nanoball with direction oriented hemagglutinin1 on its surface (H1-NB) was prepared as a new influenza vaccine, exhibiting most of the viral features. Moreover, the concentrations of antigen on the particle surface were controlled, and its effect on immunogenicity was estimated by <I>in vivo</I> studies. Finally, H1-NB efficiently promoted H1-specific immune activation and cross-protective activities, which consequently prevented H1N1 infections in mice.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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