• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.212-214
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• 2004

In this study, we fabricated the organic thin film by self-assembly method by using nitro-group and methoxy-group organic molecule. Also, we selected the organic single molecule in organic thin film and measured current-voltage characteristics by using scanning tunneling microscopy. The Organic molecules that use in an experiment is 4,4'-(diethynylphenyl)-2'-nitro-1-benzen ethiol and 4-[2,5-dimethoxy-4-ph enylethynylphenyl]ethynylphenylethanthiol. 4,4'-(dimet hynylphenyl)-2'-nitro-1-benzenethiol is applied widely in molecular electronic device and 4-[2,5-dime thoxy-4-phenylethynylphenyl]ethynylphenylethanthiol composed in Korea Research Institute of Chemical Technology. To be confirmed the formation of the self-assembled monolayers, we observed the real time frequency shift of the QCM and investigated surface of the self-assembled monolayers the using STM. With this, we measured current to the organic single molecule, in condition of the air state. As a result, we confirmed in constant voltage that properties of negative differential resistance. Using properties of negative differential resistance to get from this study, application is expected to be molecular switching device, memory device and logic device.

• Biomedical Science Letters
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• v.10 no.2
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• pp.75-84
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• 2004

Massive identification of differentially expressed patterns has been used as a tool to detect genes that are involved in disease related process. We employed circular single stranded sense molecules as probe DNA for a DNA chip. The circular single stranded DNAs derived from 1,152 unigene cDNA clones were purified in a high throughput mode from the culture supernatant of bacterial transformants containing recombinant phagemids and arrayed onto silanized slide glasses. The DNA chip was examined for its utility in detection of differential expression profile by using cDNA hybridization. Hybridization of the single stranded probe DNA were performed with Cy3- or Cy5-labeled target cDNA preparations at $60^\circ$C. Dot scanning performed with the hybridized slide showed 29 up-regulated and 6 down-regulated genes in a cancerous liver tissue when compared to those of adjacent noncancerous liver tissue. These results indicate that the circular single stranded sense molecules can be employed as probe DNA of arrays in order to obtain a precious panel of differentially expressed genes.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.555-559
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• 2015

Coherence length (time) is a key parameter in many classical and quantum optical applications. Two interferometers – Michelson and Young’s double-slit – are used to characterize the temporal coherence of single photons emitted from single terrylene molecules. For quantitative analysis, a dispersion-related distortion in the interference pattern of a Michelson interferometer is carefully corrected by a simple dispersion compensation. Additionally, it has been demonstrated that Young’s interferometer can be used in temporal coherence studies at the single photon level with high accuracy. The pros and cons of the two systems are discussed. The measured coherence lengths in the two systems are consistent with one another under the self-interference interpretations.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.746-750
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• 2011

Fluorescence correlation spectroscopy (FCS) is an emerging fluorescence technique used to study the dynamics of proteins on a millisecond to microsecond time scale at the single-molecule level. Solution pH-modulated protein conformational changes can be manifested by binding rate, fluorescence lifetime, and binding specificity of a probe molecule. The fluorescence lifetime of Nile red (NR) bound to apomyoglobin (apoMb) was measured to be $6{\pm}0.3$ ns, much longer than that in water solution ($2.9{\pm}0.2$ ns). As the unfolding population of apoMb increased by lowering pH of solution, the fraction for the longer lifetime of NR decreased with an increasing fraction for the shorter lifetime of NR in water. Unlike 1-anilino-8-naphthalene sulfonic acid, which has many lifetimes due to nonspecific binding to the unfolded apoMb, NR bound to apoMb possesses only a single lifetime. These results suggest that NR binds specifically to native apoMb and thus can be utilized to probe the folding/unfolding dynamics of apoMb using FCS.

• BMB Reports
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• v.54 no.3
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• pp.157-163
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• 2021

The transient interactions between cellular components, particularly on membrane surfaces, are critical in the proper function of many biochemical reactions. For example, many signaling pathways involve dimerization, oligomerization, or other types of clustering of signaling proteins as a key step in the signaling cascade. However, it is often experimentally challenging to directly observe and characterize the molecular mechanisms such interactions-the greatest difficulty lies in the fact that living cells have an unknown number of background processes that may or may not participate in the molecular process of interest, and as a consequence, it is usually impossible to definitively correlate an observation to a well-defined cellular mechanism. One of the experimental methods that can quantitatively capture these interactions is through membrane reconstitution, whereby a lipid bilayer is fabricated to mimic the membrane environment, and the biological components of interest are systematically introduced, without unknown background processes. This configuration allows the extensive use of fluorescence techniques, particularly fluorescence fluctuation spectroscopy and single-molecule fluorescence microscopy. In this review, we describe how the equilibrium diffusion of two proteins, K-Ras4B and the PH domain of Bruton's tyrosine kinase (Btk), on fluid lipid membranes can be used to determine the kinetics of homodimerization reactions.

• Journal of Sensor Science and Technology
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• v.31 no.4
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• pp.238-243
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• 2022

In this study, a pyrene-core single molecule with amino (-NH₂) functional group material was hybridized using ZnO quantum dots (QDs). The suppressed performance of the 1-aminopyrene (1-PyNH₂) single molecule as an emissive layer (EML) in light-emitting diodes (LEDs) was exploited by adopting the ZnO@1-PyNH₂ core-shell structure. Unlike pristine 1-PyNH₂ molecules, the ZnO@1-PyNH₂ hybrid QDs formed energy proximity levels that enabled charge transfer. This result can be interpreted as an improvement in surface roughness. The uniform and homogeneous EML alleviates dark-spot degradation. Moreover, LEDs with the ITO/PEDOT:PSS/TFB/EML/TPBi/LiF/Al configuration were fabricated to evaluate the performance of two emissive materials, where pristine-1-PyNH₂ molecules and ZnO@1-PyNH₂ QDs were used as the EML materials to verify the improvement in electrical characteristics. The ZnO@1-PyNH₂ LEDs exhibited blue luminescence at 443 nm (FWHM = 49 nm), with a turn-on voltage of 4 V, maximum luminance of 1500 cd/m², maximum luminous efficiency of 0.66 cd/A, and power efficiency of 0.41 lm/W.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.145.1-145.1
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• 2016

Binding and unbinding between molecular oxygen and metallo-porphyrin is a key process for oxygen delivery in respiration. It can be also used to control spin state of magnetic metallo-porphyrin molecules. Controlling and sensing spin states of magnetic molecules in such reactions at the single molecule level is essential for spintronic molecular device applications. Here, we demonstrate that spin states of metallo-porphyrin on surfaces can be controlled over by binding and unbinding of oxygen molecule, and be sensed using scanning tunneling microscopy and spectroscopy. Kondo localized state of metallo-porphyrin showed significant modification by the binding of oxygen molecule, implying that the spin state was changed. Our density functional theory calculation results explain the observations with the hybridization of unpaired spins in d and ${\pi}^*$ orbitals of metallo-porphyrin and oxygen, respectively. Our study opens up ways to control molecular spin state and Kondo effect by means of molecular binding and unbinding reactions on surfaces.

• Korean Journal of Poultry Science
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• v.10 no.1
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• pp.60-66
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• 1983

Monoclonal antibodies against Taka virus, a variant of Newcastle disease virus (NDV), were produced to compare the antigenicites of several avian paramyxoviruses including NDV. It was also used to study the activesite(s) of haemagglutin (HA) and neuraminidase activities of NDV. Five independent hybrid cell lines, which produced monoclonal antibodies against haemagglutinin-neuraminidase (HN) molecule of Taka virus, were established. From the results of the cross haemagglutination-inhibition(HI) test the monoclonal antibodies, the HN molecule of Taka virus seemed to have at least three different antigenic determinats; one was specific for all NDV strain tested, the second was only for Taka virus and the third was for Take virus, Banger and Yucaipa Furthermore the differences in the ratio of HI to neuraminidase-inhibition titers suggested that the active sites involved in HA and neuraminidase activities might be different from each other. However, since each of five monoclonal anitbodies was not especially specific for either HA or neuraminidase, the possibility that a single active site on the HN molecule may be responsible for both activities has not been excluded.

• Bulletin of the Korean Chemical Society
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• v.12 no.2
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• pp.178-181
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• 1991

The crystal structure of dehydrated fully $Cd^{2+}$-exchanged zeolite A evacuated at $2{\times}10^{-6}$ Torr and $450^{\circ}C (a = 12.225(2){\AA})$ and of its ethylene sorption complex (a = 12.219(2) ${\AA}$) have been determined by single crystal X-ray diffraction techniques in the cubic space group Pm3m at $21(1)^{\circ}$. The structures were refined to final error indices, $R_1$ = 0.063 and $R_2$ = 0.065 with 266 reflections and $R_1$ = 0.055 and $R_2$ = 0.062 with 260 reflections, respectively, for which $I{\gg}3{\sigma}(I)$. In both structures, six $Cd^{2+}$ ions lie at two distinguished three-fold axes of unit cell. Dehydrated $Cd_6$-A sorbs 4 ethylene molecules per unit cell at $25^{\circ}C$ (vapor pressure of ethylene is ca. 100 Torr). Each $Cd^{2+}$ ion forms a lateral ${pi}$ complex with an ethylene molecule. Four $Cd^{2+}$ ions exist in a nearly tetrahedral environment, 2.210(7)${\AA}$ apart from three framework oxygen ions (considering ethylene molecule as a monodentate ligand) and $2.67(6){\AA}$ from each carbon atom of ethylene molecule.

• Korean Journal of Optics and Photonics
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• v.10 no.1
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• pp.1-4
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• 1999

A confocal microscope system was used to study the bursts of fluorescence photons from single dye molecules excited at 638 nm by a short-pulsed diode laser with a repetition rate of 17 MHz. A red dye, JA22, in ethylene glycol solution was used as a sample. The fluorescence decay curves of single molecules were acquired using a time-correlated single photon counting and analyzed by a maximum likelihood estimator. It was possible to measure the fluorescence decay times with an error probability of 21% at photon number of more than 40 per dye molecule.