• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2240-2244
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• 2010

We have studied white OLED using two types of Zn-complexes as a emitting layer. We synthesized new emissive materials $Zn(HPQ)_2$ as a yellow emitting material and $Zn(HPB)_2$ as a blue emitting material. Zn-complexes have a low molecular compound and thermal stability. The fundamental structures of the fabricated OLED was ITO / NPB (40nm) / $Zn(HPB)_2$ (30nm) / $Zn(HPQ)_2$ / LiF / Al. We varied the thickness of the $Zn(HPQ)_2$ layer 20, 30 40 nm. When the thickness of the $Zn(HPQ)_2$ layer was 20 nm, white emission was achieved. The maximum luminance was 12,000 cd/$m^2$ at a current density of 800 mA/$cm^2$. The CIE coordinates of the white emission was (0.319. 0.338) at an applied voltage of 10 V.

• BMB Reports
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• v.29 no.2
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• pp.180-182
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• 1996

One of the essential functions of virus surface proteins is the recognition of specific receptors on target cell membranes, and cellular receptors play an important role in viral pathogenesis. But the earliest steps of hepatitis B virus (HBV) infection, such as hepatocyte receptor interaction with the virus, are poorly understood. Previous work has suggested an important role of the preS1 region of HBV envelope protein in mediating viral binding to hepatocytes. Although hepatitis B virus (HBV) infection appears to be initiated by specific binding of virions to cell membrane structures via one or potentially several viral surface proteins, data showing the identification or isolation of the HBV receptor (s) are not yet available. The receptor-like proteins on the plasma membrane surface of HepG2 cells that bind to PreS1 were separated and identified using affinity chromatography, and the amino-terminal amino acid sequences of the receptor-like proteins were determined.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1258-1262
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• 2011

A new organogelator, L-Alanine dihydrazide derivative can self-assemble in various organic solvents and turned them into thermally reversible physical supramolecular organogels at extremely low concentrations (< 2 wt %). The gel-sol phase transition temperatures ($T_{GS}$) were determined as a function of gelator concentration and the corresponding enthalpies (${\Delta}H_g$) were extracted. Scanning electron microscopy (SEM) measurements revealed that the interspaces of fiber-like network structures were diminished with the increasing of the LMOG concentration. FT-IR spectroscopy studies revealed that hydrogen-bonding and hydrophobic interaction were the driving forces for the formation of the gels. Based on the data of XRD and molecular modeling, the possible packing modes for the formation of organogelator aggregates were proposed.

• Macromolecular Research
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• v.17 no.4
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• pp.265-270
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• 2009

Noble thermosensitive nanoparticles, based on a PNIPAAm-co-AA core and a chitosan shell structure, were designed and synthesized for the controlled release of the loaded drug. PNIPAAm nanoparticles containing a carboxylic group on their surface were synthesized using emulsion polymerization. The carboxylic groups were conjugated with the amino group of a low molecular weight, water soluble chitosan. The particle size of the synthesized nanoparticles was decreased from 380 to 25 nm as the temperature of the dispersed medium was increased. Chitosan-conjugated nanoparticles with $2{\sim}5$ wt% MBA, a crosslinking monomer, induced a stable aqueous dispersion at a concentration of 1mg/1mL. The chitosan-conjugated nanoparticles showed thermo sensitive behaviors such as LCST and size shrinkage that were affected by the PNIPAAm core and induced some particle aggregation around LCST, which was not shown in the NIPAAm-co-AA nanoparticles. These chitosan-conjugated nanoparticles are also expected to be more biocompatible than the PNIPAAm core itself through the chitosan shell structures.

• BMB Reports
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• v.31 no.4
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• pp.307-327
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• 1998

Cytochrome c peroxidase (CcP) is a yeast mitochondrial enzyme which catalyzes the reduction of hydrogen peroxide to water using two equivalents of ferrocytochrome c. The CcP/cytochrome c system has many features which make it a very useful model for detailed investigation of heme protein structure/function relationships including activation of hydrogen peroxide, protein-protein interactions, and long-range electron transfer. Both CcP and cytochrome c are single heme, single subunit proteins of modest size. High-resolution crystallographic structures of both proteins, of one-to-one complexes of the two proteins, and a number of active-site mutants are available. Site-directed mutagenesis studies indicate that the distal histidine in CcP is primarily responsible for rapid utilization of hydrogen peroxide implying significantly different properties of the distal histidine in the peroxidases compared to the globins. CcP and cytochrome c bind to form a dynamic one-to-one complex. The binding is largely electrostatic in nature with a small, unfavorable enthalpy of binding and a large positive entropy change upon complex formation. The cytochrome c-binding site on CcP has been mapped in solution by measuring the binding affinities between cytochrome c and a number of CcP surface mutations. The binding site for cytochrome c in solution is consistent with the crystallographic structure of the one-to-one complex. Evidence for the involvement of a second, low-affinity cytochrome c-binding site on CcP in long-range electron transfer between the two proteins is reviewed.

• BMB Reports
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• v.39 no.4
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• pp.464-467
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• 2006

Recently, the nucleotide sequences of entire genomes became available. This information combined with older sequencing data discloses the exact chromosomal location of millions of nucleotide markers stored in the databases at NCBI, EMBO or DDBJ. Despite having resolved the intron/exon structures of all described genes within these genomes with a stroke of a pen, the sequencing data opens up other interesting possibilities. For example, the genomic mapping of the end sequences of the human, murine and rat BAC libraries generated at The Institute for Genomic Research (TIGR), reveals now the entire encompassed sequence of the inserts for more than a million of these clones. Since these clones are individually stored, they are now an invaluable source for experiments which depend on genomic DNA. Isolation of smaller fragments from such clones with standard methods is a time consuming process. We describe here a reliable one-step cloning technique to obtain a DNA fragment with a defined size and sequence from larger genomic clones in less than 48 hours using a standard vector with a multiple cloning site, and common restriction enzymes and equipment. The only prerequisites are the sequences of ends of the insert and of the underlying genome.

• Natural Product Sciences
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• v.17 no.4
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• pp.279-284
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• 2011

Phytochemical studies on the whole extract of Sedum hybridum L., a Mongolian medicinal plant, has been undertaken to isolate active principles responsible for its anti-oxidative and antibacterial activities. Eighteen known compounds, i.e. (1) quercetin, (2) kaempferol, (3) herbacetin-8-O-${\beta}$-D-xylopyranoside, (4) myricetin, (5) gossypetin-8-O-${\beta}$-D-xylopyranoside, (6) gallic acid, (7) 2,4,6-tri-O-galloyl-D-glucopyranose, (8) 6-O-galloylarbutin, (9) myricetin-3-O-${\alpha}$-L-arabinofuranoside, (10) quercetin-3-O-${\alpha}$-L-arabinofuranoside, (11) caffeic acid, (12) ethylgallate, (13) (-) epigallocatechin-3-O-gallate, (14) palmitic acid, (15) stearic acid, (16) stearic acid ethyl ether, (17) ${\beta}$-sitosterol and (18) ${\beta}$-sitosteryl-O-${\beta}$-D-glucopyranose have been isolated and their molecular structures identified by spectroscopic analysis. Thirteen substances including seven flavonol components (1, 2, 3, 4, 5, 9 and 10), five gallic acid derivatives (6, 7, 8, 12 and 13) and caffeic acid (11) exhibited significant, dose-dependent, DPPH radical scavenging activity. Galloyl esters 12 and 13 were revealed to be main active principles for the antibacterial property of the extract of Sedum hybridum L.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.120.2-120.2
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• 2011

The improvement of solar energy-to-electricity conversion efficiency has continued to be an important research area of dye-sensitized solar cells (DSSCs). The mechanism of DSSCs is based on the injection of electrons from the photoexcited dye into the conduction band of nanocrystalline TiO2 or ZnO. Thus, the electronic structures, such as HOMO, LUMO, and HOMO-LUMO band gaps of dye moleculed in DSSC are deeply related to the electron transfer by photoexcitation and redox potential. Organic dyes, because of their many advantages, such as high molar extinction coefficients, convenience of customized molecular design for desired photophysical and photochemical properties, inexpensiveness with no transition metals contained, and environment-friendliness, are suitable as photosensitizers for DSSC. We believe that practically useful organic dye photosensitizers can be produced by exploiting electron donor/acceptor system with proper length of ${\pi}$-conjugation in a chromophore to control the absorption wavelength and enhance the photovoltaic performance. In this research, We designed and synthesized organic dyes also investigated the photoelectrochemical properties of a series of ionic dyes in DSSCs.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.65-73
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• 2000

Surfactants have been extensively considered for decontamination of the subsurface polluted with hydrophobic organic compounds. In order to investigate the effect of molecular structures on the solubilization of hydrophobic organic compounds, solubility enhancement of two PAHs in solutions of three different surfactants-conventional, dianionic, and gemini. The batch experimental results showed that the gemini was the most effective and the dianionic was the least, indicating that organic carbon content of the surfactants was the major factor which determines the sorption capacity of surfactant aggregates in water, unlike some of the previous reports.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.347-358
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• 2011

Fomitopsis palustris, a brown-rot basidiomycete, causes the most destructive type of decay in wooden structures. In spite of its great economic importance, very little information is available at the molecular level regarding its complex decay process. To address this, we generated over 3,000 expressed sequence tags (ESTs) from a cDNA library constructed from F. palustris. Clustering of 3,095 high-quality ESTs resulted in a set of 1,403 putative unigenes comprising 485 contigs and 918 singlets. Homology searches based on BlastX analysis revealed that 78% of the F. palustris unigenes had a significant match to proteins deposited in the nonredundant databases. A subset of F. palustris unigenes showed similarity to the carbohydrateactive enzymes (CAZymes), including a range of glycosyl hydrolase (GH) family proteins. Some of these CAZyme-encoded genes were previously undescribed for F. palustris but predicted to have potential roles in biodegradation of wood. Among them, we identified and characterized a gene (FpCel45A) encoding the GH family 45 endoglucanase. Moreover, we also provided functional classification of 473 (34%) of F. palustris unigenes using the Gene Ontology hierarchy. The annotated EST data sets and related analysis may be useful in providing an initial insight into the genetic background of F. palustris.