• 제목/요약/키워드: Chemical imaging

검색결과 364건 처리시간 0.023초

Imaging and Manipulation of Benzene Molecules on Si Surfaces Using a Variable-low Temperature Scanning Tunneling Microscope

  • Hahn, J. R.
    • Bulletin of the Korean Chemical Society
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    • 제26권7호
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    • pp.1071-1074
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    • 2005
  • A variable-low temperature scanning tunneling microscope (VT-STM), which operates from 77 to 350 K in ultrahigh vacuum, was built and used to study imaging and manipulation of benzene molecules on Si surfaces. Four types of benzene adsorption structures were first imaged on the Si(5 5 12)-2x1 surface. Desorption process of benzene molecules by tunneling electrons was studied on the Si(001)-2xn surface.

Synthesis and Evaluation of Estrogen Receptor β -Selective Ligands: Fluoroalkylated Indazole Estrogens

  • Moon, Byung-Seok;Katzenellenbogen, John A.;Cheon, Gi-Jeong;Chi, Dae-Yoon;Lee, Kyo-Chul;An, Gwang-Il
    • Bulletin of the Korean Chemical Society
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    • 제29권6호
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    • pp.1107-1114
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    • 2008
  • It is important to identify selective ligands for the estrogen receptor subtypes ER$\alpha$ or ER$\beta$ to evaluate them as pharmaceutical targets in breast cancer. To develop ER$\beta$-selective ligands as PET imaging agents, a series of aryl indazole estrogen analogues substituted at the C3 position with fluoroethyl and fluoropropyl groups were synthesized and evaluated for their relative binding affinities and selectivities for ER$\alpha$ vs ER$\beta$. The fluoroethylated indazole estrogen (FEIE, 1i) and fluoropropylated indazole estrogen (FPIE, 1h) showed 41- fold and 17-fold ER$\beta$/ER$\alpha$ selectivity, respectively. However, their binding affinities to ER$\alpha$ and ER$\beta$ were very low.

Chemical Imaging Analysis of the Micropatterns of Proteins and Cells Using Cluster Ion Beam-based Time-of-Flight Secondary Ion Mass Spectrometry and Principal Component Analysis

  • Shon, Hyun Kyong;Son, Jin Gyeong;Lee, Kyung-Bok;Kim, Jinmo;Kim, Myung Soo;Choi, Insung S.;Lee, Tae Geol
    • Bulletin of the Korean Chemical Society
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    • 제34권3호
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    • pp.815-819
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    • 2013
  • Micropatterns of streptavidin and human epidermal carcinoma A431 cells were successfully imaged, as received and without any labeling, using cluster $Au_3{^+}$ ion beam-based time-of-flight secondary ion mass spectrometry (TOF-SIMS) together with a principal component analysis (PCA). Three different analysis ion beams ($Ga^+$, $Au^+$ and $Au_3{^+}$) were compared to obtain label-free TOF-SIMS chemical images of micropatterns of streptavidin, which were subsequently used for generating cell patterns. The image of the total positive ions obtained by the $Au_3{^+}$ primary ion beam corresponded to the actual image of micropatterns of streptavidin, whereas the total positive-ion images by $Ga^+$ or $Au^+$ primary ion beams did not. A PCA of the TOF-SIMS spectra was initially performed to identify characteristic secondary ions of streptavidin. Chemical images of each characteristic ion were reconstructed from the raw data and used in the second PCA run, which resulted in a contrasted - and corrected - image of the micropatterns of streptavidin by the $Ga^+$ and $Au^+$ ion beams. The findings herein suggest that using cluster-ion analysis beams and multivariate data analysis for TOF-SIMS chemical imaging would be an effectual method for producing label-free chemical images of micropatterns of biomolecules, including proteins and cells.

The Reactions of O(3P) Atom with Halomethanes: Discharge Flow-Chemiluminescence Imaging Method

  • Lee, Jee-Yon;Yoo, Hee-Soo
    • Bulletin of the Korean Chemical Society
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    • 제23권2호
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    • pp.291-294
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    • 2002
  • The reactions of triplet oxygen atom with halomethanes as a potential fire extinguisher were studied by a discharge flow-chemiluminescence imaging method. The experiments were carried out under second order conditions. The bimolecular atom-molecule reaction rate constants were determined in terms of the initial rate method. The initial concentration of oxygen atom was also determined under second order rate law instead of the pseudo-first order conditions with $[O(^3P)]_0{\ll}[sample]_0$. The second order conditions were more reliable than pseudo-first order conditions for the determinations of rate constants. The rate constants of the reactions $CF_3I\;+\;O(^3P)$, $CH_3PI\;+\'O(^3P)$, and $CHBrCl_2\;+\;O(^3P)$ were determined to be $5.0\;{\times}\;10^{-12}$ , $1.1\;×\;0^{-11}$ , and $1.9\;{\times}\;10^{-14}cm^3molecule^{-1}s^{-1}$, respectively.

Mass Spectrometry Imaging of Microbes

  • Yang, Hyojik;Goodlett, David R.;Ernst, Robert K.;Scott, Alison J.
    • Mass Spectrometry Letters
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    • 제11권3호
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    • pp.41-51
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    • 2020
  • Microbes influence many aspects of human life from the environment to health, yet evaluating their biological processes at the chemical level can be problematic. Mass spectrometry imaging (MSI) enables direct evaluation of microbial chemical processes at the atomic to molecular levels without destruction of valuable two-dimensional information. MSI is a label-free method that allows multiplex spatiotemporal visualization of atomic- or molecular-level information of microbial and microberelated samples. As a result, microbial MSI has become an important field for both mass spectrometrists and microbiologists. In this review, basic techniques for microbial MSI, such as ionization methods and analyzers, are explored. In addition, we discuss practical applications of microbial MSI and various data-processing techniques.

Hyperpolarization: Sensitivity Boost in Magnetic Resonance Spectroscopy and Imaging

  • Ko, Hyeji;Gong, Gyeonghyeon;Jeong, Gijin;Choi, Ikjang;Seo, Hyeonglim;Lee, Youngbok
    • 한국자기공명학회논문지
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    • 제19권3호
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    • pp.124-131
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    • 2015
  • Hyperpolarization methods are the most emerging techniques in the field of magnetic resonance (MR) researches since they make a contribution to overcoming sensitivity limitation of MR spectroscopy and imaging, leading to new fields of researches, real-time in vivo metabolic/molecular imaging and MR analysis of chemical/biological reactions in non-equilibrium conditions. Make use of enormous signal enrichments, it becomes feasible to investigate various chemical and biochemical systems with low ${\gamma}$ nuclei in real-time. This review deals with the theoretical principals of common hyperpolarization methods and their experimental features. In addition, more detailed theories, mechanisms, and applications of dissolution dynamic nuclear polarization (D-DNP) are discussed.

Photodissociation of Nitrous Oxide by Slice Ion Imaging: The Stagnation Pressure Dependence

  • Cheong, Nu-Ri;Park, Hye-Sun;Nam, Sang-Hwan;Shin, Seung-Keun;Cho, Soo-Gyeong;Lee, Hai-Whang;Song, Jae-Kyu;Park, Seung-Min
    • Bulletin of the Korean Chemical Society
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    • 제30권11호
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    • pp.2661-2664
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    • 2009
  • Photodissociation of nitrous oxide near 203 nm has been studied by a combination of high resolution slice ion imaging technique and (2+1) resonance-enhanced multiphoton ionization (REMPI) spectroscopy of $N_2(X^1{{\Sigma}_g}^+)$ via the (a″$^1{{\Sigma}_g}^+$) state. We have measured the recoil velocity and angular distributions of $N_2$ fragments by ion images of the state-resolved photofragments. The $N_2$ fragments were highly rotationally excited and the NN-O bond dissociation energy was determined to be 3.635 eV. Also, we investigated the photofragment images from the photodissociation of $N_2O$ clusters with various stagnation pressures.