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Search Results: 1 - 10 of 11246 matches for " Chong-Yeon Park "
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Preparation, characterization and photocatalytic behavior of WO3-fullerene/TiO2 catalysts under visible light
Meng Ze-Da,Zhu Lei,Choi Jong-Geun,Park Chong-Yeon
Nanoscale Research Letters , 2011,
Abstract: WO3-treated fullerene/TiO2 composites (WO3-fullerene/TiO2) were prepared using a sol-gel method. The composite obtained was characterized by BET surface area measurements, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, and UV-vis analysis. A methyl orange (MO) solution under visible light irradiation was used to determine the photocatalytic activity. Excellent photocatalytic degradation of a MO solution was observed using the WO3-fullerene, fullerene-TiO2, and WO3-fullerene/TiO2 composites under visible light. An increase in photocatalytic activity was observed, and WO3-fullerene/TiO2 has the best photocatalytic activity; it may attribute to the increase of the photo-absorption effect by the fullerene and the cooperative effect of the WO3.
ZHU Lei,Trisha GHOSH,Chong-Yeon PARK,MENG Ze-Da,OH Won-Chun
催化学报 , 2012, DOI: 10.1016/S1872-2067(11)60430-0
Abstract: ?Aseriesofgraphene-TiO2compositeswasfabricatedfromgrapheneoxideandtitaniumn-butoxide(TNB)byanultrasonic-assistedmethod.ThestructureandcompositionofthenanocompositeswerecharacterizedbyRamanspectroscopy,BETsurfaceareameasurements,X-raydiffraction,transmissionelectronmicroscopy,andultraviolet-visibleabsorptionspectroscopy.TheaveragesizeoftheTiO2nanoparticlesonthegraphenenanosheetswascontrolledataround10–15nmwithoutusingsurfactant,whichisattributedtothepyrolysisandcondensationofdissolvedTNBintoTiO2byultrasonicirradiation.ThecatalyticactivityofthecompositesunderultrasonicirradiationwasdeterminedusingarhodamineB(RhB)solution.Thegraphene-TiO2compositespossessedahighspecificsurfacearea,whichincreasedthedecolorizationrateforRhBsolution.ThisisbecausethegrapheneandTiO2nanoparticlesinthecompositesinteractstrongly,whichenhancesthephotoelectricconversionofTiO2byreducingtherecombinationofphotogeneratedelectron-holepairs.
MENG Zada,ZHU Lei,CHOI Jong-geun,PARK Chong-yeon,OH Won-chun
催化学报 , 2011, DOI: 10.1016/S1872-2067(10)60258-6
Abstract: ?Rareearthoxide-treatedfullereneandtitaniacomposites(Y-fullerene/TiO2)werepreparedbythesol-gelmethod.Theproductshadinterestingsurfacecompositions.X-raydiffractionpatternsofthecompositesshowedthattheY-fullerene/TiO2compositescontainedasingleandclearanatasephase.Thesurfacepropertieswereobservedbyscanningelectronmicroscopy,whichgaveacharacterizationofthetextureontheY-fullerene/TiO2compositesandshowedahomogenousdistributionoftitaniumparticles.Theenergy-dispersiveX-rayspectrashowedthepresenceofCandTiwithstrongYpeaks.ThecompositeobtainedwasalsocharacterizedwithtransmissionelectronmicroscopyandUV-Visspectroscopy.ThephotocatalyticresultsshowedthattheY-fullerene/TiO2compositeshadexcellentactivityforthedegradationofmethyleneblueundervisiblelightirradiation.ThiswasattributedtoboththeeffectsonthephotocatalysisofthesupportedTiO2bychargetransferbythefullerene,andtheintroductionofyttriumtoenhancephoto-generatedelectrontransfer.
Synthesis of Carbon Nanomaterials-CdSe Composites and Their Photocatalytic Activity for Degradation of Methylene Blue
Ming-Liang Chen,Ze-Da Meng,Lei Zhu,Chong-Yeon Park,Jong-Geun Choi,Trisha Ghosh,Kwang-Youn Cho,Won-Chun Oh
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/964872
Abstract: We use multi-walled carbon nanotube (MWCNT) and graphene as carbon nanomaterials to obtain carbon nanomaterilas-CdSe composites using a facile hydrothermal method. The intrinsic characteristics of resulting composites were studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectrophotometer. The as-prepared carbon nanomaterilas-CdSe composites possessed great adsorptivity of dyes, extended light absorption range, and efficient charge separation properties simultaneously. Hence, in the photodegradation of methylene blue, a significant enhancement in the reaction rate was observed with carbon nanomaterilas-CdSe composites, compared to the CdSe compound.
Prospective Analysis on Survival Outcomes of Nonsmall Cell Lung Cancer Stages over IIIb Treated with HangAm-Dan
Tae-Young JEONG,Bong-Ky PARK,Yeon-Weol LEE,Chong-Kwan CHO
Chinese Journal of Lung Cancer , 2010,
Abstract: Background and objective Non-small cell lung cancer (NSCLC) stages over IIIb still remain as an intractable disease. Survival rate of NSCLC stages over IIIb could be increased through chemotherapy and radiation, but results are not satisfactory. Oriental medicine herbal formula, HangAm-Dan (HAD) has been developed for anti-tumor purpose and several previous studies have already reported its effects. The aim of this study is to assess HAD's efficacy on prolonging the survival rate of NSCLC stages over IIIb. Methods We have administered 3 000 mg of HAD daily to patients. The study included 74 first visit patients of East-West Cancer Center (EWCC) from November 2007 to April 2008, diagnosed with inoperable NSCLC stages over IIIb. Among them, 30 patients were in HAD group and 44 patients were in combined group with conventional therapy and HAD. We have observed and analyzed their overall survival. Results Of total 74 patients, overall 1 year, 2 year survival rates and the median survival time were 62.1%, 34.9% and 17.0 months (95%CI: 12.9-21.1). NSCLC stage IIIb patients showed higher survival rates than NSCLC stage IV patients (P=0.408). The 1 year, 2 year survival rates and the median survival time of the combined group were 70.5%, 37.9% and 20.0 months (95%CI: 16.4-24.6). In HAD group, the 1 year, 2 year survival rates and the median survival time were 50.0%, 25.7% and 12.0 months (95%CI: 6.6-17.4). The combined therapy group showed higher survival rates than the HAD group (P=0.034). Each groups treated with HAD for more than 4 weeks showed higher survival rates than those treated for less than 4 weeks, but there was no significant difference (P=0.278). In hazard ratio, the combined therapy group showed lower mortality rate than the HAD group with statistical significance (P=0.040). Conclusion HAD could prolong the survival rate of inoperable NSCLC stages over IIIb. HAD is more effective when combined with conventional therapy. In the future, more controlled clinical trials with larger sample in multi-centers are needed to reevaluate the efficacy and safety of HAD.
Neuroprotective Effects of Herbal Ethanol Extracts from Gynostemma pentaphyllum in the 6-Hydroxydopamine-Lesioned Rat Model of Parkinson's Disease
Hyun Sook Choi,Mi Sook Park,Seung Hwan Kim,Bang Yeon Hwang,Chong Kil Lee,Myung Koo Lee
Molecules , 2010, DOI: 10.3390/molecules15042814
Abstract: 6-Hydroxydopamine administration for 28 days (8 μg/2 μL) reduced the number of tyrosine hydroxylase (TH)-immunopositive neurons to 40.2% in the substantia nigra compared to the intact contralateral side. Dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid and norepinephrine levels were reduced to 19.1%, 52.3%, 47.1% and 67.4% in the striatum of 6-hydroxydopamine-lesioned rats compared to the control group, respectively. However, an oral administration of herbal ethanol extracts from Gynostemma pentaphyllum (GP-EX) (10 mg/kg and 30 mg/kg) starting on day 3 post-lesion for 28 days markedly ameliorated the reduction of TH-immunopositive neurons induced by 6-hydroxydopamine-lesioned rat brain from 40.2% to 67.4% and 75.8% in the substantia nigra. GP-EX administration (10 and 30 mg/kg) also recovered the levels of dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid and norepinephrine in post-lesion striatum to 64.1% and 65.0%, 77.9% and 89.7%, 82.6% and 90.2%, and 88.1% and 89.2% of the control group. GP-EX at the given doses did not produce any sign of toxicity such as weight loss, diarrhea and vomiting in rats during the 28 day treatment period and four gypenoside derivatives, gynosaponin TN-1, gynosaponin TN-2, gypenoside XLV and gypenoside LXXIV were identified from GP-EX. These results suggest that GP-EX might be helpful in the prevention of Parkinson’s disease.
Development of a Novel Fluorophore for Real-Time Biomonitoring System
Hyun-Ok Song, Binna Lee, Ram Prasad Bhusal, Byounghun Park, Kyoungsik Yu, Chom-Kyu Chong, PyoYun Cho, Sung Yeon Kim, Hak Sung Kim, Hyun Park
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048459
Abstract: Rapid in-field diagnosis is very important to prevent the outbreak of various infectious and contagious diseases. Highly sensitive and quantitative detection of diseases can be performed using fluorescent immunochemical assay with specific antigen-antibody binding and a good quality fluorophore. This can lead to the development of a small, portable, quantitative biosensor to transmit diagnostic results to a control center in order to systematically prevent disease outbreaks. In this study, we developed a novel fluorophore, coumarin-derived dendrimer, with high emission intensity, strong signal brightness, and high photostability. It is easily coupled with biomolecules and emits strong and stable fluorescence at 590 nm with excitation at 455 nm. Application to fluorescent immunochromatographic test (FICT) showed that the novel coumarin-derived dendrimer bioconjugate could detect antigens at amount as low as 0.1 ng. The clinical results and the spectral characteristics of the novel coumarin-derived dendrimer open, for the first time, the possibility of developing a cost/energy efficient LED-based portable quantitative biosensor for point-of-care (POC) disease diagnosis, which can permit real time monitoring (U-healthcare system) by a disease control center.
Effect of zinc injection on the corrosion products in nuclear fuel assembly  [PDF]
Jin-Soo Choi, Seung-Chul Park, Kyoung-Rok Park, Ho-Yeon Yang, O-Bong Yang
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.52027

The accumulation of corrosive and radioactive wastes in the primary system, including nuclear fuel assembly, significantly increases workers’ exposure to radiation. Zinc injection from 5 to 40 ppb into the Reactor Coolant System (RCS) of Pressurized Water Reactors (PWRs) has been known as an effective method to decrease the radiation fields and Primary Water Stress Corrosion Cracking (PWSCC). Zinc injection affects both corrosion product concentrations and characteristics of the deposited crud on oxide layers, because zinc is incorporated into the oxide films by displacing nickel, cobalt, and iron in primary systems. Radiation fields and corrosion might be mitigated as radioactive products, such as Co, which are removed by zinc injection. However, the zinc injection effects on fuel assembly in Nuclear Power Plants (NPPs) have not been much reported yet, even though some lab tests were carried out in USA and France. In this paper, we studied effects of zinc injection on the fuel assemblies in the Ulchin 1 NPP. The chemical and radiation analysis of radioactive corrosion products was performed to evaluate zinc injection effects on the fuel assembly in the Ulchin 1 NPP. Gamma spectroscopy was used to analyze crud samples for radioisotope contents. The Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) was used to analyze crud samples for elemental contents. The concentration of radioisotope Co-58 was decreased after zinc injection to 1/22 times that before the zinc injection. 1% - 2% wt% of zinc was incorporated through the substitution of Ni in the crud oxide layer. The Ni/Fe ratio was decreased to 0.69 from 1.12 after the injection, due to the Ni substitution by zinc. It was found that NiO and NiFe2O4 were converted to ZnO and ZnFe2O4, respectively. In conclusion, zinc injecttion was found to be an essential method to reduce the amount of radioactive Co-58 in the fuel assemblies of primary systems in NPPs.

Aqueous Two Phase Extraction for the Recovery of 1,3-Propanediol from Its Aqueous Solutions  [PDF]
Min Hee Chung, Yeon Ki Hong, Hyoung Wook Lee, Sung-Jun Park
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.24B040
Abstract: As the biodiesel production is rapidly enhanced, the crude glycerol, which is by-product of biodiesel processes, is state of surplus. 1,3-PDO (1,3-propanediol), a valuable monomer of poly(trimethylene terephthalate) (PTT), can be produced from the fermentation process using crude glycerin as a carbon source. For the economic biological production of 1,3-PDO, the low cost and high efficient separation processes is essential. In this study, aqueous two-phase system composed of various hydrophilic alcohols and salt was used as a primary separation step for 1,3-PDO. It was found that the aqueous two-phase systems are easily formed with decreasing of the polarity of alcohols. The extraction efficiency is proportional to the polarity of alcohols. In case of methanol or ethanol/K2HPO4, the extraction efficiency was more than 90%.  It was concluded that the aqueous two-phase extraction using methanol or ethanol/K2HPO4 can be applied  for the primary separation of 1,3-PDO  as an alternative to a conventional primary separation processes.
Micromorphology and Ultrastructure of the Foot of the Equilateral Venus Gomphina veneriformis (Bivalvia: Veneridae)  [PDF]
Jung Jun Park, Jung Sick Lee, Yeon Gyu Lee, Jae Won Kim
CellBio (CellBio) , 2012, DOI: 10.4236/cellbio.2012.11002
Abstract: The shape and microscopic structure of the foot of the equilateral Venus, Gomphina veneriformis are described by light and electron microscopy along with the substrate conditions of their habitat. The habitat sediment of G. veneriformis is composed of sand (2 - 0.063 mm in diameter), mainly. The foot is wedge-shaped with multiple vertical furrows on the surface. Although the foot is composed of an epithelial layer, a connective tissue layer and a muscular layer, the boundary between the connective tissue and muscular layer is not clear. The epithelial layer was composed mostly of ciliated columnar epithelia and secretory cells. Epithelial cells forming the apical region of the fold were long columnar, while cells of the interfold were mostly short columnar. The cilia and microvilli were commonly observed on the free surface of epithelial cells, while tight junctions of apico-lateral aspect and membrane interdigitations were found between the epithelial cells. Secretory cells were found to contain acidic mucopolysaccharide, and were classified into two types in accordance with the shapes and ultrastructures of secretory granules. The muscle fibers were composed of thin and thick microfilaments, the proportions of which were 81.3% and 18.7%, respectively. It was determined that such morphology and structural characteristics of the foot of G. veneriformis would present advantageous conditions for borrowing into substrate and mobility.
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