• Title, Summary, Keyword: Chemistry

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Direct Analysis in Real Time Mass Spectrometry: a Powerful Tool for Fast Analysis

  • Li, Xianjiang;Wang, Xin;Li, Linnan;Bai, Yu;Liu, Huwei
    • Mass Spectrometry Letters
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    • v.6 no.1
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    • pp.1-6
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    • 2015
  • Direct analysis in real time mass spectrometry (DART-MS) is one of the variants of ambient mass spectrometry. The ionization process of DART-MS is in open environment and only takes few seconds, so it is suitable for fast analysis. Actually, since its introduction in 2005, more and more attentions have been drawn to its various applications due to its excellent properties, e.g., fast analysis, and no or less sample preparation, high salt tolerance and so on. This review summarized the promising features of DART-MS, including its ionization mechanism, equipment modification, wide applications, coupling techniques and extraction strategies before analysis.

Highly Fluorescing Solid DNA-Cationic Polyelectrolyte Complexes Prepared from a Natural DNA and a Poly(fluorenevinylene-alt-phenylene) Bearing Quaternary Ammonium Pendants

  • Yu, Young-Jun;Kwon, Young-Wan;Kim, Kyu-Nam;Do, Eui-Doo;Choi, Dong-Hoon;Jin, Jung-Il;Shin, Hee-Won;Kim, Yong-Rok;Kang, Ik-Joong;Mikroyannidis, John A.
    • Macromolecular Research
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    • v.17 no.4
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    • pp.245-249
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    • 2009
  • A fluorescing, copolymer(Q)-bearing, quaternary ammonium pendant was mixed with excess natural salmon sperm DNA with a molecular weight of $1.3{\times}10^6$(2,000 base pairs) to afford highly fluorescing, complex mixtures. The fluorescence life-time of the polymer Q was greatly increased when mixed with DNA: for the mixture of Q:DNA=1:750 the fast and slow decay lifetimes increased from ca. 10 to 100 ps and from 20 ps to ca. 1 ns, respectively. The enhanced fluorescence of the mixtures was ascribed to efficient compartmentalization and reduced conformational relaxation of the polymer Q by complexation with excess DNA.

Relationship between the High School Chemistry I, II, and the General Chemistry, and College Students' Cognition about the Subject (대학교 일반화학과 고등학교 화학 I, 화학 II 교과의 연계성 및 일반화학에 대한 대학생들의 인식조사)

  • Moon, Sook-Hee;Lee, Sang-Joa
    • Journal of the Korean Chemical Society
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    • v.55 no.1
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    • pp.112-123
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    • 2011
  • The chemistry has the academic system in which a concept is jointly developed into the single strain, so the contents of the chemistry I II of the high school are very important in the connection of the general chemistry in the university. At this moment, it is possible for high school graduates to be accepted into science or engineering majors without taking the chemistry II. These the highest intensive election subject cause problems of differences in level of understanding and difficult of quality educations. In this study, we have analyzed similarity between the contents of the chemistry I II and the general chemistry. We also analyzed the cognition level of students without taking the chemistry II in understanding the general chemistry level classes. We found that the high school level chemistry I and II introduced about 27% and 62% of the essential concepts required for the general chemistry, respectively. In a case of M university in Chonnam, about 70% of students in the general chemistry classes have no exposure to the chemistry II in their high schools, causing difficulty of understanding new subjects due to their insufficient concepts for classes. The lack of knowledge caused lowering of learning achievement and decrease of interests in chemistry.

Synthesis of 2,5-Disubstituted Pyrrolidines from N-Alkenyl and Alkynyl N-Benzoyloxysulfonamides Catalyzed by (CuOTf)2・C6H6

  • Liu, Wei-Min;Liu, Zhen-Hong;Cheong, Wei-Wen;Priscilla, Lu-Yi Teo;Li, Yongxin;Narasaka, Koichi
    • Bulletin of the Korean Chemical Society
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    • v.31 no.3
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    • pp.563-569
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    • 2010
  • A new synthetic method of 2,5-disubstituted pyrrolidines is developed by the cyclization of unsaturated N-benzoyloxysulfonamides by $(CuOTf)_2{\cdot}C_6H_6$ in refluxing dichloroethane. Various N-4- and N-5-alkenyl and alkynyl N-benzoyloxysulfonamides are cyclized to give pyrrolidines. The cyclization proceeds via addition of sulfonamidoyl radicals to intramolecular unsaturated bonds or allylic hydrogen abstraction with the radical intermediates.

A Comparative Study of Secondary Chemistry Education in Korea and China

  • Lee, Wha-Kuk;Hur, Chinhyu;Chuan, Zhou
    • Journal of The Korean Association For Science Education
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    • v.21 no.5
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    • pp.944-967
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    • 2001
  • The purpose of this study is to compare and analyze secondary school chemistry education in Korea and China in order to identify implications for the improvement of Korean chemistry education. The school systems, curricula, and teacher education related to secondary chemistry education of both countries were compared and analyzed. The 6-3-3-4 school system is used in both countries, and national school curricula are formulated by the Ministries of Education in both countries. The 1996 chemistry curricular standard for advanced middle schools in China, and 1997 chemistry curriculum for Korean high schools were compared in several aspects, followed by comparisons of chemistry teacher education in both countries. Based on the comparative analysis of chemistry education, some ideas and issues which provide implications for improving Korean high school chemistry education were identified. Chemistry teaching in the junior secondary schools, tentative implementation of curricula, required course work in chemistry, structure of curricula, oral assessments, probation of teachers and other issues are identified and discussed in this study.

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Treatment of Industrial Wastewater with High Concentration of Hydrocarbons Using Membrane Reactors

  • Bienati, B.;Bottino, A.;Comite, A.;Ferrari, F.;Firpo, R.;Capannelli, G.
    • Membrane Journal
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    • v.17 no.2
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    • pp.112-117
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    • 2007
  • The application of membrane bioreactors for the depuration of wastewater coming from the washing of mineral oil storage tanks is described. Microfiltration hollow-fibre membranes were used in the submerged configuration. Filtration tests were carried out with a biomass concentration of about 15 g/L in order to assess the critical flux of the hollow fibre membrane used. Then particular care was taken in carrying out the performance runs in the sub-critical flux region. The reactor performance was very high, with removal efficiencies ranging between 93% and 97% also when the concentration of hydrocarbon was very high. Some kinetic parameters for the COD and the hydrocarbon removal were estimated.

Macasiamenene V, a New Stilbenoid from the Leaves of Macaranga inermis

  • Aldin, Muhammad Fajar;Tjahjandarie, Tjitjik Srie;Saputri, Ratih Dewi;Tanjung, Mulyadi
    • Natural Product Sciences
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    • v.27 no.1
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    • pp.45-48
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    • 2021
  • One new compound, macasiamenene V (1), and two known stilbenes (2-3) were isolated from Macaranga inermis Pax & K.Hoffm leaves. The structure of 1 was fully assigned based on the information on high-resolution MS and (1D, 2D) NMR spectra. The cytotoxic of compounds 1-3 was evaluated against 4T1 and HeLa cells. Compounds 2-3 showed high activity against HeLa cells with an IC50 value of 1.09 and 0.88 ㎍/mL, respectively.