• Title/Summary/Keyword: General Chemistry

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FLUORESCENCE DEPOLARIZATION IN DIFFERENT MOLECULAR SYSTEMS

  • Kim, Hack-Jin;Kang, Tai-Jong
    • Journal of Photoscience
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    • v.1 no.1
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    • pp.75-82
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    • 1994
  • General features of the fluorescence depolarization are briefly reviewed. Molecular rotations and electronic excitation transports are considered to account for the fluorescence depolarization. Various molecular systems studied by the fluorescence depolarization are described. The FiSrster theory which forms a basis for the energy transfer is revisited. Several theoretical treatments for the fluorescence depolarization in liquid and solid phases such as classical hydrodynamics, probability distribution function, Green's function formalism, molecular dynamics simulation and Monte Carlo methods are introduced.

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Linear Relationships between Thermodynamic Parameters. Part 6 Solvent Effect on Chloride Exchanges in Benzyl Chloride (열역학함수간의 직선관계 (제6보) 염화벤질의 염소교환에 미치는 용매효과)

  • Lee, Ik-Choon;Park, Yong-Ja
    • Journal of the Korean Chemical Society
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    • v.12 no.4
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    • pp.160-162
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    • 1968
  • Rate constants and activation parameters have been petermined for the chloride exchanges of benzyl chloride in 60, 70, 80 and 90 vol.% ethanol-water solutions. Results showed a good linearity when appiled to our general equation. The significance of this linear fit has been discussed in conjunction with the Dewar's relation which was derived from the PMO method.

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Simple Detection of Opines by Paper Electrophoresis for Hairy Roots Transformed with Agrobacterium rhizogenes Strains

  • Cho, Hyeon-Je;Ha, Hyo-Cheol;Lee, Jae-Sung;Widholm, Jack M.
    • Journal of Applied Biological Chemistry
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    • v.44 no.2
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    • pp.92-94
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    • 2001
  • A simple protocol for the detection of opines, cucumopines and mikimopines using a general horizontal or vertical get electrophoresis system for protein or DNA separation in the laboratory are demonstrated. This electrophoresis method can also be applied to other opines as long as correct detection reagent and buffer system are used.

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Enantioselective Carboxylate Receptor Using Glycoluril Molecular Scaffold

  • Kim, Hyun-Gil;Kang, Jong-Min
    • Bulletin of the Korean Chemical Society
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    • v.27 no.11
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    • pp.1791-1794
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    • 2006
  • We have introduced a new enantioselective receptor 1 by incorporation of chiral building blocks to the previously reported carboxylate selective receptor 2. Binding studies carried out using $^1H$ NMR revealed that the receptor 1 showed moderate enantioselectivity with a general preference for D-amino acids and a highest enantioselectivity for leucine among the amino acids we investigated.

A Convenient Synthesis of Optically Active Unhindered Aliphatic Alcohols with High Optical Purity from Non-Racemic β-Hydroxy Sulfides

  • Cho, Byung-Tae;Kim, Dong-Jun
    • Bulletin of the Korean Chemical Society
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    • v.25 no.9
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    • pp.1385-1391
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    • 2004
  • A general route for the synthesis of optically active unhindered aliphatic alcohols, where the steric demands between two alkyl groups adjacent to the carbinol are similar, with high enantiomeric purity has been developed by sulfoxifation of chiral ${\beta}$-hydroxy sulfides, followed by alkylation and desulfurization.

Synthesis and Antitubercular Activity of 6-Chloro (Unsubstituted)- 2-Methoxy-9-Substituted Acridine Derivatives

  • Aly, Enayat I.;Abadi, Ashraf H.
    • Archives of Pharmacal Research
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    • v.27 no.7
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    • pp.713-719
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    • 2004
  • Several analogues of the general formulae 2-methoxy-9-substituted acridine and 6-chloro-2-methoxy-9-substituted acridine were synthesized and evaluated in vitro at 6.25 $\mu\textrm{g}$/mL against M. tuberculosis $H_{37}Rv$. Compounds 15 and 17 showed potential antitubercular activity with 100% inhibition to the virulent mycobacterium.

Gas Chromatography/Mass Spectrometry and Gas Chromatography/Tandem Mass Spectrometry of some s-Triazine Pesticides

  • Kim, Yoo-Joong;Kim, Myung-Soo
    • Bulletin of the Korean Chemical Society
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    • v.10 no.2
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    • pp.196-200
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    • 1989
  • Some s-triazine herbicides, namely simazine, atrazine, and propazine present as trace components in a complex mixture were analyzed by GC/MS and GC/MS/MS methods. Even though monitoring the molecular ions was the best in terms of sensitivity, adequate analysis could not be done when interfering species were present. When doubly charged ions which appeared at characteristic m/z values were monitored, chromatograms were rather free from interference. More importantly, selected reaction monitoring was found to provide a selective means of detection with general applicability.

Reexamination of Tris(hydroxymethyl)aminomethane-Catalyzed Hydrolysis of p-Nitrotrifluoroacetanilide

  • Suh, Jung-Hun;Han, Ok-Soo
    • Bulletin of the Korean Chemical Society
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    • v.5 no.5
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    • pp.207-208
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    • 1984
  • The tris(hydroxymethyl)aminomethane (Tris)-catalyzed hydrolysis of p-nitrotrifluoroacetanilide was kinetically studied. On the contrary to the previously reported results (R. M. Pollack and T. C.Dumsha, J. Am. Chem. Soc., 1973, 95, 4463), the dependence of the rate on [Tris] consists of an initial curve portion and a subsequent linear increase. This indicates that erroneous conclusions were made in the reported work due to the insufficient amount of data. The initial portions of the rate[Tris] profiles are attributed to the catalyzed breakdown of the tetrahedral intermediate, and the linear portions to the general base-catalyzed water attack at the substrate.

On-off controllable RNA hybrid expression vector for yeast three-hybrid system

  • Bak, Geunu;Hwang, Se-Won;Ko, Ye-Rim;Lee, Jung-Min;Kim, Young-Mi;Kim, Kyung-Hwan;Hong, Soon-Kang;Lee, Young-Hoon
    • BMB Reports
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    • v.43 no.2
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    • pp.110-114
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    • 2010
  • The yeast three-hybrid system (Y3H), a powerful method for identifying RNA-binding proteins, still suffers from many false positives, due mostly to RNA-independent interactions. In this study, we attempted to efficiently identify false positives by introducing a tetracycline operator (tetO) motif into the RPR1 promoter of an RNA hybrid expression vector. We successfully developed a tight tetracycline-regulatable RPR1 promoter variant containing a single tetO motif between the transcription start site and the A-box sequence of the RPR1 promoter. Expression from this tetracycline-regulatable RPR1 promoter in the presence of tetracycline-response transcription activator (tTA) was positively controlled by doxycycline (Dox), a derivative of tetracycline. This on-off control runs opposite to the general knowledge that Dox negatively regulates tTA. This positively controlled RPR1 promoter system can therefore efficiently eliminate RNA-independent false positives commonly observed in the Y3H system by directly monitoring RNA hybrid expression.

Adsorption of Phenols onto Chemically-Activated Carbons Developed from Wild Cherry Stones

  • Alaya, M.N.;Youssef, A.M.;Karman, M.;Abd El-Aal, H.E.
    • Carbon letters
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    • v.7 no.3
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    • pp.188-195
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    • 2006
  • Phosphoric acid-activated carbon WP's and zinc chloride-activated carbons WZ's were developed from wild cherry stones. The textural properties of the activated carbons were determined from nitrogen adsorption data at 77 K and the chemistry of the carbon surface, i.e. the surface carbon-oxygen groups (type and amount) was determined from the base and acid neutralization capacities (Boehm method). The adsorption of phenol, p-nitrophenol, p-chlorophenol, dinitrophenol and dichlorophenol was followed at 298 K. The activated carbons obtained were characterized by high surface area and large pore volumes as well as by high surface concentration of C-O groups. The investigated carbons exhibited high adsorption capacities towards phenols with these capacities increased with the increase of molecular weight and the decrease of the solubility of phenol in water. However, no general relationship could be observed between the adsorption capacities of carbons and any of their textural parameters or their surface chemistry. This may be attributed to the many factors controlling phenol adsorption and the different types and mechanisms of adsorption involved.

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