Research on Stretch-flangeability of High Mn TWIP Steel (초)

Chen Lei,Jin Kyung Kim,Han S. Kim,Sung Kyu Kim,Gyo Sung Kim,Kwang Geun Chin,B. C. De Cooman 대한금속ㆍ재료학회 2009 대한금속재료학회 학술대회 개요집 Vol.2009 No.1

Design of Silica-protected Surface-enhanced Raman Scattering Nanoprobe for Immunosorbent Assay#

CHEN LEI,사영조,Xu Wang,Bing Zhao,정영미 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.3

In this study, we present a method of achieving highly sensitive immunoassays based on surface-enhanced Raman scattering (SERS). The biofunctional-nanoprobe-linked immunosorbent assay is a closely related technique with a good linear range and the ability to simultaneously detect antigens with high sensitivity. Herein, we report a novel method based on a sandwich structure composed of a silver monolayer and biocompatible Au-mercaptobenzoic acid (MBA)@SiO2 that was assembled through an immune recognition reaction. To induce a strong plasmonic contribution of the nanoprobes, two or more MBA-adsorbed gold nanoparticles were saturated and loaded into silica. Silica-protected gold nanoaggregates exhibit stable SERS activity and biocompatibility for proteins. The capabilities of the proposed sandwich structure for analytical applications were demonstrated through the use of the SERS technique to detect antigens at very low concentrations. These techniques may prove to be superior to current protocols for biomarker research and clinical diagnosis, which require high sensitivity and quantitation over an extended range.

Enhanced catalyst activity by decorating of Au on Ag@Cu₂O nanoshell

Chen, Lei,Liu, Maomao,Zhao, Yue,Kou, Qiangwei,Wang, Yaxin,Liu, Yang,Zhang, Yongjun,Yang, Jinghai,Jung, Young Mee Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.435 No.-

<P><B>Abstract</B></P> <P>We successfully synthesized Au-decorated Ag@Cu<SUB>2</SUB>O heterostructures via a simple galvanic replacement method. As the Au precursor concentration increased, the density of the Au nanoparticles (NPs) on the Ag@Cu<SUB>2</SUB>O surface increased, which changed the catalytic activity of the Ag@Cu<SUB>2</SUB>O-Au structure. The combination of Au, Ag, and Cu<SUB>2</SUB>O exhibited excellent catalytic properties, which can further effect on the catalyst activity of the Ag@Cu<SUB>2</SUB>O-Au structure. In addition, the proposed Ag@Cu<SUB>2</SUB>O-Au nanocomposite was used to transform the organic, toxic pollutant, 4-nitrophenol (4-NP), into its nontoxic and medicinally important amino derivative via a catalytic reduction to optimize the material performance. The proposed Au-decorated Ag@Cu<SUB>2</SUB>O exhibited excellent catalytic activity, and the catalytic reduction time greatly decreased (5 min). Thus, three novel properties of Ag@Cu<SUB>2</SUB>O-Au, i.e., charge redistribution and transfer, adsorption, and catalytic reduction of organic pollutants, were ascertained for water remediation. The proposed catalytic properties have potential applications for photocatalysis and localized surface plasmon resonance (LSPR)- and peroxidase-like catalysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Au-decorated Ag@Cu<SUB>2</SUB>O heterostructures via a simple galvanic replacement method were designed. </LI> <LI> We can easily control the density of the Au NPs on Ag@Cu<SUB>2</SUB>O by changing the concentration of the Au precursor. </LI> <LI> Ag@Cu<SUB>2</SUB>O-Au nanomaterials with high absorption exhibited significantly enhanced catalytic activity for 4-NP. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Yersinia pestis antibiotic resistance: a systematic review

Chen Lei,Suresh Kumar 질병관리본부 2022 Osong Public Health and Research Persptectives Vol.13 No.1

Yersinia pestis, the cause of plague and a potential biological weapon, has always been a threatening pathogen. Some strains of Y. pestis have varying degrees of antibiotic resistance. Thus, this systematic review was conducted to alert clinicians to this pathogen’s potential antimicrobial resistance. A review of the literature was conducted for experimental reports and systematic reviews on the topics of plague, Y. pestis, and antibiotic resistance. From 1995 to 2021, 7 Y. pestis isolates with 4 antibiotic resistance mechanisms were reported. In Y. pestis 17/95, 16/95, and 2180H, resistance was mediated by transferable plasmids. Each plasmid contained resistance genes encoded within specific transposons. Strain 17/95 presented multiple drug resistance, since plasmid 1202 contained 10 resistance determinants. Strains 16/95 and 2180H showed single antibiotic resistance because both additional plasmids in these strains carried only 1 antimicrobial determinant. Strains 12/87, S19960127, 56/13, and 59/13 exhibited streptomycin resistance due to an rpsl gene mutation, a novel mechanism that was discovered recently. Y. pestis can acquire antibiotic resistance in nature not only via conjugative transfer of antimicrobial-resistant plasmids from other bacteria, but also by gene point mutations. Global surveillance should be strengthened to identify antibiotic-resistant Y. pestis strains by whole-genome sequencing and drug susceptibility testing.

Determination of Stress Intensity Factor $K_I$ from Two Fringe Orders by Fringe Multiplication and Sharpening

Chen, Lei,Baek, Tae-Hyun The Korean Society for Nondestructive Testing 2007 한국비파괴검사학회지 Vol.27 No.6

Stress intensity factor is one of the most important parameters in fracture mechanics. Both the stress field distribution and the crack propagation are closely related to these parameters. Due to the complexity of actual engineering problems, it is difficult to calculate the stress intensity factor by theoretical formulation, so photoelasticity method is a good choice. In this paper, modified two parameter method is employed to calculate stress intensity factor for opening mode by using data from more than one photoelastic fringe loop. For getting accurate experiment results, the initial fringes are doubled and sharpened by digital image programs from the fringe patterns obtained by a CCD camera. Photoelastic results are compared with those obtained by the use of empirical equation and FEM. Good agreement shows that the methods utilized in experiments are considerably reliable. The photoelastic experiment can be used for bench mark in theoretical study and other experiments.

SERS study of surface plasmon resonance induced carrier movement in Au@Cu₂O core-shell nanoparticles

Chen, Lei,Zhang, Fan,Deng, Xin-Yu,Xue, Xiangxin,Wang, Li,Sun, Yantao,Feng, Jing-Dong,Zhang, Yongjun,Wang, Yaxin,Jung, Young Mee Elsevier 2018 Spectrochimica acta. Part A, Molecular and biomole Vol.189 No.-

<P><B>Abstract</B></P> <P>A plasmon induced carrier movement enhanced mechanism of surface-enhanced Raman scattering (SERS) was investigated using a charge-transfer (CT) enhancement mechanism. Here, we designed a strategy to study SERS in Au@Cu<SUB>2</SUB>O nanoshell nanoparticles with different shell thicknesses. Among the plasmonically coupled nanostructures, Au spheres with Cu<SUB>2</SUB>O shells have been of special interest due to their ultrastrong electromagnetic fields and controllable carrier transfer properties, which are useful for SERS. Au@Cu<SUB>2</SUB>O nanoshell nanoparticles (NPs) with shell thicknesses of 48–56nm are synthesized that exhibit high SERS activity. This high activity originates from plasmonic-induced carrier transfer from Au@Cu<SUB>2</SUB>O to 4-mercaptobenzoic acid (MBA). The CT transition from the valence band (VB) of Cu<SUB>2</SUB>O to the second excited π-π* transition of MBA, and is of b<SUB>2</SUB> electronic symmetry, which was enhanced significantly. The Herzberg-Teller selection rules were employed to predict the observed enhanced b<SUB>2</SUB> symmetry modes. The system constructed in this study combines the long-range electromagnetic effect of Au NPs, localized surface plasmon resonance (LSPR) of the Au@Cu<SUB>2</SUB>O nanoshell, and the CT contribution to assist in understanding the SERS mechanism based on LSPR-induced carrier movement in metal/semiconductor nanocomposites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We designed a shell-dependent Au@Cu<SUB>2</SUB>O nanoshell for SERS study. </LI> <LI> SERS contribution enables us to understand the possible enhancement of hybrid nanostructures. </LI> <LI> LSPR-induced carrier movement in Au@Cu<SUB>2</SUB>O nanocomposites. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>We designed the shell-dependent Au@Cu<SUB>2</SUB>O core-shell nanoparticles (NPs) for SERS study. For the electron-hole pairs in the Cu<SUB>2</SUB>O, the plasmon induced resonant energy transfer from Au to the Cu<SUB>2</SUB>O and the direct electron transfer simultaneously which can be observed from the SERS intensity.</P> <P>[DISPLAY OMISSION]</P>

Highly sensitive determination of iron (III) ion based on phenanthroline probe: Surface-enhanced Raman spectroscopy methods

Chen, Lei,Ma, Ning,Park, Yeonju,Jin, Sila,Hwang, Hoon,Jiang, Dayu,Jung, Young Mee Elsevier 2018 Spectrochimica acta. Part A, Molecular and biomole Vol.197 No.-

<P><B>Abstract</B></P> <P>In this paper, we introduced Raman spectroscopy techniques that were based on the traditional Fe<SUP>3+</SUP> determination method with phenanthroline as a probe. Interestingly, surface-enhanced Raman spectroscopy (SERS)-based approach exhibited excellent sensitivities to phenanthroline. Different detection mechanisms were observed for the RR and SERS techniques, in which the RR intensity increased with increasing Fe<SUP>3+</SUP> concentration due to the observation of the RR effect of the phenanthroline-Fe<SUP>2+</SUP> complex, whereas the SERS intensity increased with decreasing Fe<SUP>3+</SUP> concentration due to the observation of the SERS effect of the uncomplexed phenanthroline. More importantly, the determination sensitivity was substantially improved in the presence of a SERS-active substrate, giving a detection limit as low as 0.001μg/mL, which is 20 times lower than the limit of the UV–vis and RR methods. Furthermore, the proposed SERS method was free from other ions interference and can be used quality and sensitivity for the determination of the city tap water.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We designed the RR and SERS spectroscopic techniques based determination methods for Iron (III). </LI> <LI> Different detection mechanisms were observed for the RR and SERS techniques for the proposed system. </LI> <LI> The determination sensitivity was substantially improved in the presence of a SERS-active substrate. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>Different detection mechanisms were observed for the RR and SERS techniques, in which the RR intensity increased with increasing Fe<SUP>3+</SUP> concentration due to the observation of the RR effect of the phenanthroline-Fe<SUP>2+</SUP> complex, whereas the SERS intensity increased with decreasing Fe<SUP>3+</SUP> concentration due to the observation of the SERS effect of the uncomplexed phenanthroline.</P> <P>[DISPLAY OMISSION]</P>

Quantitative evaluation of proteins with bicinchoninic acid (BCA): resonance Raman and surface-enhanced resonance Raman scattering-based methods

Chen, Lei,Yu, Zhi,Lee, Youngju,Wang, Xu,Zhao, Bing,Jung, Young Mee The Royal Society of Chemistry 2012 The Analyst Vol.137 No.24

<P>A rapid and highly sensitive bicinchoninic acid (BCA) reagent-based protein quantitation tool was developed using competitive resonance Raman (RR) and surface-enhanced resonance Raman scattering (SERRS) methods. A chelation reaction between BCA and Cu<SUP>+</SUP>, which is reduced by protein in an alkaline environment, is exploited to create a BCA–Cu<SUP>+</SUP> complex that has strong RR and SERRS activities. Using these methods, protein concentrations in solutions can be quantitatively measured at concentrations as low as 50 μg mL<SUP>−1</SUP> and 10 pg mL<SUP>−1</SUP>. There are many advantages of using RR and SERRS-based assays. These assays exhibit a much wider linear concentration range and provide an additional one (RR method) to four (SERRS method) orders of magnitude increase in detection limits relative to UV-based methods. Protein-to-protein variation is determined using a reference to a standard curve at concentrations of BSA that exhibits excellent recoveries. These novel methods are extremely accurate in detecting total protein concentrations in solution. This improvement in protein detection sensitivity could yield advances in the biological sciences and medical diagnostic field and extend the applications of reagent-based protein assay techniques.</P> <P>Graphic Abstract</P><P>A rapid and highly sensitive bicinchoninic acid (BCA) reagent-based protein quantitation tool was developed using competitive resonance Raman (RR) and surface-enhanced resonance Raman scattering (SERRS) methods. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2an35715a'> </P>

Discovery of Anticancer Activity of Amentoflavone on Esophageal Squamous Cell Carcinoma: Bioinformatics, Structure-Based Virtual Screening, and Biological Evaluation

Chen, Lei,Fang, Bo,Qiao, Liman,Zheng, Yihui The Korean Society for Microbiology and Biotechnol 2022 Journal of microbiology and biotechnology Vol.32 No.6

Esophageal squamous cell carcinoma (ESCC) is the most common primary esophageal malignancy with poor prognosis. Here, due to the necessity for exploring potential therapies against ESCC, we obtained the gene expression data on ESCC from the TCGA and GEO databases. Venn diagram analysis was applied to identify common targets. The protein-protein interaction network was constructed by Cytoscape software, and the hub targets were extracted from the network via cytoHubba. The potential hub nodes as drug targets were found by pharmacophore-based virtual screening and molecular modeling, and the antitumor activity was evaluated through in vitro studies. A total of 364 differentially expressed genes (DEGs) in ESCC were identified. Pathway enrichment analyses suggested that most DEGs were mainly involved in the cell cycle. Three hub targets were retrieved, including CENPF, CCNA2 (cyclin A), and CCNB1 (cyclin B1), which were highly expressed in esophageal cancer and associated with prognosis. Moreover, amentoflavone, a promising drug candidate found by pharmacophore-based virtual screening, showed antiproliferative and proapoptotic effects and induced G1 in esophageal squamous carcinoma cells. Taken together, our findings suggested that amentoflavone could be a potential cell cycle inhibitor targeting cyclin B1, and is therefore expected to serve as a great therapeutic agent for treating esophageal squamous cell carcinoma.

Antioxidant Capacities and Cytostatic Effect of Korean Red Pepper (Capsicum annuum L): a Screening and in vitro Study

Chen, Lei,Hwang, Ji-Eun,Choi, Boram,Gu, Kang Mo,Park, Youmie,Kang, Young-Hwa The Korean Society for Applied Biological Chemistr 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.1

Methanol extracts from 100 Korean varieties of red pepper (Capsicum annuum L) were obtained. Chromatic parameters ($L^*$, $a^*$, and $b^*$) and total phenolic content were analyzed. By evaluation of total phenolic content and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging based-antioxidant associated with surface color measurement, red pepper varieties were classified into four groups by hierarchical cluster analysis. Cultivars of 'PR-Sangsaeng', 'PR-Jijon', 'PR-Eowoolrim', 'PR-Chambut', 'PAK37', and 'Hojanggoonbigalim" had high quantity of pigments and high phenolic content. These six cultivars also with higher levels of antioxidant might give an advantage to local growers in Korea. For further cytostatic activity evaluation, extracts from various parts including pericarp, seed, and stalk of cultivar 'PAK37' and 'Hojanggoonbigalim' were prepared. Four human cancer cells (HepG2, AGS, MCF-7, and HT-29) were used. The tumor cell growth inhibitory effect was evaluated by in vitro MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. High capsaicin content and antioxidant activity-containing red pepper stalk extract showed the strongest cytostatic activity. Tumor cell growth inhibitory activity was positively correlated with the capsaicin content. The anticancer potentials of various red pepper parts were in the following order: stalk > seed > pericarp. The data suggest that red pepper parts might have a promising health benefit against liver cancer, colon cancer and gastric cancer more than breast cancer.