• Title/Summary/Keyword: $\alpha$-spectroscopy

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Fabrication and Characterization of a Fiber-Optic Alpha/Beta Detector for Nuclear Medicine Application (핵의학 적용을 위한 광섬유 기반의 알파/베타 검출기의 제작 및 특성분석)

  • Hong, Seung-Han;Yoo, Wook-Jae;Shin, Sang-Hun;Seo, Jeong-Ki;Han, Ki-Tek;Jeon, Da-Yeong;Cho, Seung-Hyun;Lee, Bong-Soo
    • Journal of Sensor Science and Technology
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    • v.21 no.5
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    • pp.367-373
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    • 2012
  • We fabricated a fiber-optic alpha/beta detector, which is composed of a sensing probe, a plastic optical fiber, a photomultiplier tube, and a multichannel analyzer, to obtain the energy spectra of radioactive isotopes. As inorganic scintillators of a sensing probe, a ZnS(Ag) film was coupled with a $CaF_2$(Eu) crystal for alpha and beta spectroscopy. In this study, $^{210}Po$ and $^{90}Sr$ were used as alpha and beta sources, respectively, and we measured the radiation energy spectra using a fiber-optic alpha/beta detector to identify alpha and beta emitting radionuclides for nuclear medicine application. Also, the variations of energy spectrum were obtained according to the length of plastic optical fiber.

Adsorption and Desorption of CO on W(110) Surfaces

  • Yang, Taek-seung;Jee, Hae-geun;Boo, Jin-Hyo;Han, Hyun-Seok;Lee, Gyung-Hee;Kim, Young-Dok;Lee, Soon-Bo
    • Bulletin of the Korean Chemical Society
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    • v.29 no.6
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    • pp.1115-1120
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    • 2008
  • The adsorption of CO on W(110) surfaces was studied using thermal desorption spectroscopy (TDS), and core and valence level spectroscopy. At 120 K, CO forms a tilted structure at lower coverages ($\alpha$ 1), whereas it adsorbs normal to the surface at higher coverages ($\alpha$ 2). Tilted structures have been suggested to be precursors of dissociative chemisorption; however, experimental evidence is provided for the non-dissociative chemisorption of CO at temperatures above 900 K (which is referred to as the $\beta$ -state): TDS shows first order desorption kinetics. The core and valence level spectra of O/W(110) and those of $\beta$ -CO/W(110) are different. Most importantly, the 4$\sigma$ molecular orbital of CO can be identified in the valence level spectra of the $\beta$ -CO.

Preparation and Characterization of β-C3N4 in Presence of Seed Carbon Nitride Films Deposited by Laser-Electric Discharge Method

  • Kim, J.I.;Zorov, N.B.;Burdina, K.P
    • Transactions on Electrical and Electronic Materials
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    • v.3 no.3
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    • pp.29-33
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    • 2002
  • A procedure was developed for preparing bulk carbon nitride crystals from a polymeric $\alpha$ -C$_3$N$\_$4.2/ at high pressure and temperature in the presence of seeds of crystalline carbon nitride films prepared by a high voltage discharge plasma combined with pulsed laser ablation of graphite target. The samples were evaluated by x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, Auger electron spectroscopy (AES), secondary-ion mass spectrometry (SIMS), scanning electron microscopy (SEM) and x-ray diffraction (XRD). Notably, XPS studies of the film composition before and after thermobaric treatments demonstrate that the nitrogen composition in $\alpha$ -C$_3$N$\_$4.2/ material initially containing more than 58% nitrogen decreases during the annealing process and reaches a common, stable composition of ~45%. The thermobaric experiments were performed at 10-77 kbar and 350-1200 $\^{C}$.

Structural Analysis of Petroleum Fractions by Near-Infrared and $^{13}C$-NMR Spectroscopy (근적외선과 $^{13}C$-핵자기 공명 분광학에 의한 석유유분 구조분석)

  • Choi, Ju-Hwan;Kim, Hai-Dong;Choi, Young-Sang
    • Analytical Science and Technology
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    • v.9 no.2
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    • pp.168-178
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    • 1996
  • Molecular structures of petroleum fractions(diesel fuel, bunker-C oil, lubricant base stocks) have been analyzed and compared in terms of the compositions (aromatics, naphtherucs, paraffinics), aromatics(benzene-nuclear and bonded alkyl groups), C2(methylene) carbon atoms % $C_{\alpha}$ and $C_{\beta}$ carbon stom % in alkyl groups and paraffins(branched and normal) by near-infrared and $^{13}C$-NMR spectroscopy.

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Comparing the Stability of Geometrically rigid Tricyclopropyl Carbinyl Cations by $^{19}$F NMR Spectroscopy

  • Shin, Jung-Hyu;Kim, Kyong-Tae;Shin, Hun-Woo
    • Bulletin of the Korean Chemical Society
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    • v.8 no.3
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    • pp.144-145
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    • 1987
  • The relative stability as function of geometry in the rigid tricyclopropylcarbinyl cations with varied bond angle (${\alpha}$) between the plane of cyclopropane ring and the bond connecting cyclopropane ring to cationic carbon was examined by $^{19}F$ nmr spectroscopy. 7-p-Fluorophenyltricyclo[2.2.2.$0^{2,6}$]octan-7-yl(4) and 8-p-fluorophenyltricyclo[3.2.2.$0^{2,7}$]nonan-8-yl cation (8) were generated from corresponding tertiary alcohols under stable ion conditions, and their $^{19}F$ chemical shifts were compared with those of model compounds such as 7-nortricyclyl cation (3) and tricyclo[3.3.1.$0^{2,7}$]octan-8-yl cation (7). Consequently, it is concluded that the varied orientation of bond angle (${\alpha}$) within in the bisected conformation does not affect degree of the charge delocalization into cyclopropane ring.

A study on the growth and characterization of $\alpha$ -Sexithienyl thin films by OMBD(Organic Molecular Beam Deposition) technique (유기 분자빔 성막법을 이용한 $\alpha$-Sexithieny1 박막의 성장 및 특성 연구)

  • 박용인;박주강;권오관;김영관;최종선;신동병;손병청;강도열
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.11a
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    • pp.187-190
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    • 1996
  • Conducting polymers have band structures similar to those of inorganic semiconductors such as silicon. Several electronic devices have been constructed with conjugated polymers, mainly Schottky diodes and Metal-Insulator-Semiconductor Field-Effect Transistors (MISFET's). Organic semiconductor has been reported as active materials in MISFET's.$^{1.4}$ In our laboratory, $\alpha$-Sexithiencyl ($\alpha$-6T) has been synthesized and purified by sublimation method. In this study, thin films of $\alpha$-Sexithienyl were prepared on various substrates in ultra-high vacuum chamber by vacuum evaporation method, so called OMBD(Organic Molocular Beam Deposition).$^{7.9}$ The $\alpha$-Sexithienyl thin films were deposited with various deposition conditions. The crystalline structure, and molecular orientation of these films have being studied by using UV/Vis. spectroscopy and X-Ray Diffractometry.

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1H, 15N, and 13C Resonance Assignments of the Anti-CRISPR AcrIIA4 from Listeria monocytogenes Prophages

  • Kim, Iktae;Kim, Nak-Kyoon;Suh, Jeong-Yong
    • Journal of the Korean Magnetic Resonance Society
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    • v.22 no.3
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    • pp.71-75
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    • 2018
  • The CRISPR-Cas system is the adaptive immune system in bacteria and archaea against invading phages or foreign plasmids. In the type II CRISPR-Cas system, an endonuclease Cas9 cleaves DNA targets of phages as directed by guide RNA comprising crRNA and tracrRNA. To avoid targeting and destruction by Cas9, phages employ anti-CRISPR (Acr) proteins that act against host bacterial immunity by inactivating the CRISPR-Cas system. Here we report the backbone $^1H$, $^{15}N$, and $^{13}C$ resonance assignments of AcrIIA4 that inhibits endonuclease activity of type II-A Listeria monocytogenes Cas9 and also Streptococcus pyogenesis Cas9 using triple resonance nuclear magnetic resonance spectroscopy. The secondary structures of AcrIIA4 predicted by the backbone chemical shifts show an ${\alpha}{\beta}{\beta}{\beta}{\alpha}{\alpha}$ fold, which is used to determine the solution structure.

Structural Characterization of a Flavonoid Compound Scavenging Superoxide Anion Radical Isolated from Capsella bursa-pastoris

  • Kweon, Mee-Hyang;Kwak, Jae-Hyock;Ra, Kyung-Soo;Sung, Ha-Chin;Yang, Han-Chul
    • BMB Reports
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    • v.29 no.5
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    • pp.423-428
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    • 1996
  • A superoxide anion radical scavenger isolated from Capsella bursa-pastoris was characterized by infrared (IR) spectroscopy, sugar analysis, ultraviolet (UV) spectroscopy, $^{1}H$ and $^{13}C$ nuclear magnetic resonance (NMR) spectroscopies, and fast atom bombardment (FAB) mass analysis. The compound was assumed to be a flavonoid-O-glycoside from IR spectrum and UV absorption maxima. When the sugar composition of the compound was examined by thin layer chromatography (TLC) and gas chromatography (GC) of the acid hydrolysate, only glucose was detected. According to the results of UV spectrotroscopy by using shift reagents, the compound was supposed to be luteolin (5,7,3',4'-tetrahydroxy flavone) or chrysoeriol (5,7,4'-trihydroxy-3'-methoxy flavone) with glucose. Based on $^{1}H$- and $^{13}C-NMR$ spectroscopies, the compound was deduced as 7,4'-dihydroxy-5,3'-dimethoxy-${\alpha}$-6-c-glucosyl-${\beta}$-2"-o-glucosyl flavone. In FAB mass analysis the compound was finally characterized as 7,4'-dihydroxy-5,3'-dimethoxy-${\alpha}$-6-c-glucosyl-${\beta}$-2"-o-glucosyl flavone ($C_{29}H_{34}O_{16}$, M.W.=638).

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Periodicity in Chemical Shifts and Temperature Coefficients of $\alpha$-helix in TFE Solution

  • Suh, Jeong-Yong;Choi, Byong-Seok
    • Proceedings of the Korean Biophysical Society Conference
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    • 1997.07a
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    • pp.42-42
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    • 1997
  • Local conformation of helical peptides in TFE solution are studied by NMR spectroscopy. One is a helix containing proline and the other is its alanine derivative in which alanine is substituted for the proline. Chemical shift and temperature coefficient In NMR spectroscopy can be used preliminarily to determine secondary structure in proteins and peptides.(omitted)

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