Profile decompositions of fractional Schrodinger equations with angularly regular data

Cho, Y.,Hwang, G.,Kwon, S.,Lee, S. Academic Press 2014 Journal of differential equations Vol.256 No.8

We study the fractional Schrodinger equations in R<SUP>1+d</SUP>, d≥3, of order d/(d-1)<α<2. Under the angular regularity assumption we prove linear and nonlinear profile decompositions which extend the previous results [9] to data without radial assumption. As applications we show blowup phenomena of solutions to mass-critical fractional Hartree equations.

Direct Gingival Fibroblast/Osteoblast Transdifferentiation via Epigenetics

Cho, Y.,Kim, B.,Bae, H.,Kim, W.,Baek, J.,Woo, K.,Lee, G.,Seol, Y.,Lee, Y.,Ku, Y. Journal of Dental Research, Inc 2017 Journal of dental research Vol.96 No.5

<P>Alveolar bone resorption caused by trauma or periodontal diseases has represented a challenge for both dental clinicians and researchers. In this study, we evaluate the osteogenic potential of human gingival fibroblasts (HGFs) through a direct transdifferentiation from HGFs to functional osteoblasts via epigenetic modification and osteogenic signaling with bone morphogenetic protein 2 (BMP2) in vitro and in vivo. HGF treatment with 5-aza-2'-deoxycytidine (5-aza-dC) induced demethylation in the hypermethylated CpG islands of the osteogenic lineage marker genes RUNX2 and ALP, and subsequent BMP2 treatment successfully drove the fibroblasts to the osteoblasts' lineage. Cell morphological changes viewed under microscopy and alkaline phosphatase (ALP) and alizarin red S (ARS) staining confirmed the osteoblastic change mediated by epigenetic modification as did real-time polymerase chain reaction (PCR), methylation-specific PCR (MSP), and chromatin immunoprecipitation (ChIP) assay, which demonstrated the altered methylation patterns in the RUNX2 and ALP promoter regions and their effect on gene expression. Furthermore, micro-computed tomography (CT) analysis of in vivo mouse cell transplantation experiments showed high-density signal in the epigenetically modified HGF group; in addition, a significant amount of bone formation was observed in the transplanted material using hematoxylin and eosin (H&E) staining as well. Collectively, our results indicate that epigenetic modification permits the direct programming of HGFs into functional osteoblasts, suggesting that this approach might open a novel therapeutic avenue in alveolar bone regeneration.</P>

Energy concentration of the focusing energy-critical fNLS

Cho, Y.,Hwang, G.,Shim, Y.S. Academic Press 2016 Journal of mathematical analysis and applications Vol.437 No.1

<P>We consider the fractional nonlinear Schrodinger equation (fNLS) with non-local dispersion vertical bar del vertical bar(alpha) and focusing energy-critical Hartree type nonlinearity [-(vertical bar x vertical bar(-2 alpha) * vertical bar u vertical bar(2))u]. We consider the energy -concentration phenomena of radial blowup solutions near the maximal existence time. We use the concentration -compactness approach of [19] for confined case and kinetic energy trapping approach of [21] for unconfined case. (C) 2015 Elsevier Inc. All rights reserved.</P>

Supercritical fluid chromatography coupled with in-source atmospheric pressure ionization hydrogen/deuterium exchange mass spectrometry for compound speciation

Cho, Y.,Choi, M.H.,Kim, B.,Kim, S. Elsevier 2016 Journal of chromatography A Vol.1444 No.-

<P>An experimental setup for the speciation of compounds by hydrogen/deuterium exchange (HDX) with atmospheric pressure ionization while performing chromatographic separation is presented. The proposed experimental setup combines the high performance supercritical fluid chromatography (SFC) system that can be readily used as an inlet for mass spectrometry (MS) and atmospheric pressure photo ionization (APPI) or atmospheric pressure chemical ionization (APCI) HDX. This combination overcomes the limitation of an approach using conventional liquid chromatography (LC) by minimizing the amount of deuterium solvents used for separation. In the SFC separation, supercritical CO2 was used as a major component of the mobile phase, and methanol was used as a minor co-solvent. By using deuterated methanol (CH3OD), AP HDX was achieved during SFC separation. To prove the concept, thirty one nitrogen- and/or oxygen-containing standard compounds were analyzed by SFC-AP HDX MS. The compounds were successfully speciated from the obtained SFC-MS spectra. The exchange ions were observed with as low as 1% of CH3OD in the mobile phase, and separation could be performed within approximately 20 min using approximately 0.24 mL of CH3OD. The results showed that SFC separation and APPI/APCI HDX could be successfully performed using the suggested method. (C) 2016 Elsevier B.V. All rights reserved.</P>

Spectral evidence for multi-pathway contribution to the upconversion pathway in NaYF4:Yb3+,Er3+ phosphors

Cho, Y.,Song, S.,Lim, S.,Kim, J.,Park, C.,Kim, H. Royal Society of Chemistry 2017 Physical chemistry chemical physics Vol.19 No.10

<P>Although upconversion phosphors have been widely used in nanomedicine, laser engineering, bioimaging, and solar cell technology, the upconversion luminescence mechanism of the phosphors has been fiercely debated. A comprehensive understanding of upconversion photophysics has been significantly impeded because the number of photons incorporated in the process in different competitive pathways could not be resolved. Few convincing results to estimate the contribution of each of the two-, three-, and four-photon channels of near-infrared (NIR) energy have been reported in yielding upconverted visible luminescence. In this study, we present the energy upconversion process occurring in NaYF4: Yb3+, Er3+ phosphors as a function of excitation frequency and power density. We investigated the upconversion mechanism of lanthanide phosphors by comparing UV/VIS one-photon excitation spectra and NIR multi-photon spectra. A detailed analysis of minor transitions in one-photon spectra and luminescence decay enables us to assign electronic origins of individual bands in multi-photon upconversion luminescence and provides characteristic transitions representing the corresponding upconversion channel. Furthermore, we estimated the quantitative contribution of multiple channels with respect to irradiation power and excitation energy.</P>

Development of a BSC-Based Evaluation Framework for e-Manufacturing Project

Cho, Y.,Kim, W.,Leem, C. S.,Choi, H. SPRINGER-VERLAG 2005 Lecture Notes in Computer Science Vol.3482 No.-

H₂ effects on diesel combustion and emissions with an LPL-EGR system

Cho, Y.,Song, S.,Chun, K.M. Pergamon Press ; Elsevier Science Ltd 2013 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.38 No.23

In this study, we examined H<SUB>2</SUB> effects on the combustion and emissions of a diesel engine with low-pressure loop (LPL) exhaust gas recirculation (EGR). We converted a 2.2-L four-cylinder direct-injection diesel engine satisfying Euro5 for H<SUB>2</SUB> supply. An LPL-EGR system replaced the high-pressure loop (HPL) EGR system. For all tests, the brake mean effective pressure (BMEP) was kept at 4 bar and the EGR ratio was varied from 9 to 42%. The H<SUB>2</SUB> energy percentage was varied from 0 to 7.4% independently to evaluate the H<SUB>2</SUB> effects and EGR effects separately. The heat release rate was calculated from the measured cylinder pressure. We found that substitution of H<SUB>2</SUB> for diesel fuel made the premixed burn fraction larger, and reduced the nitrous oxide (NOx) and particulate matter (PM) emissions simultaneously. For example, the NOx emissions were reduced by 36% for an EGR of 42% and an H<SUB>2</SUB> percentage of 7.4%. PM emissions were reduced by 18% for an EGR of 35% and an H<SUB>2</SUB> percentage of 7.4% compared with diesel fuel only cases.

A novel synthetic route for the preparation of core shell like carbon-supported nanoparticles with a Pt-rich shell

Cho, Y.,Lee, W.,Kim, H. Royal Society of Chemistry 2014 Journal of materials chemistry. A, Materials for e Vol.2 No.30

A novel synthetic process referred to as a protective coating method was developed for the fabrication of a carbon-supported Pt2Ni1 nanoparticle measuring approximately 5 nm in size with a Pt-rich shell via thermal treatment. A 3 to 5 nm thick potypyrrole layer encapsulating the surface of the Pt/C catalyst simultaneously acted as a sponge to absorb the Ni precursor and a physical barrier to inhibit the inevitable increase in particle size during the thermal treatment. The PPy layer does not behave as a poison to the catalyst because it is completely decomposed without carbonization on the Pt surface during the heat treatment in a H-2-Ar mixture. As a result, the resultant Pt2Ni1/C catalyst with a Pt-rich shell exhibited improved stability under acidic conditions and catalytic activity in an oxygen reduction reaction.

Towards an integrated management system based on abstraction of heterogeneous virtual resources

Springer Science + Business Media 2014 Cluster computing Vol.17 No.4

Enhanced energy harvesting based on surface morphology engineering of P(VDF-TrFE) film

Cho, Y.,Park, J.B.,Kim, B.S.,Lee, J.,Hong, W.K.,Park, I.K.,Jang, J.E.,Sohn, J.I.,Cha, S.,Kim, J.M. Elsevier 2015 Nano energy Vol.16 No.-

Polyvinylidene fluoride (PVDF) has great potential for its use as an energy harvesting material as it exhibits not only outstanding piezoelectric and electrostatic characteristics resulting from ferroelectric effects, but also remarkably robust stability against repeated mechanical stress compared to inorganic materials. We report enhanced performances of poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) based energy generators with wider range of selections of flexible substrates through a surface morphology engineering using solvent annealing method as the key technology for simple and cost-effective fabrication at room temperature. It is clearly revealed that a solvent annealed P(VDF-TrFE) film is crystallised at room temperature and that the surface morphology is changed from a rough surface into a smooth and flat surface with increasing annealing time. This surface morphology engineering results in 8 times enhanced output voltage and current of the energy generators because of well-aligned electrical dipoles. We also demonstrate a highly transparent and flexible energy generator by employing graphene electrodes with the solvent annealed P(VDF-TrFE) film, which can be effectively harvesting various mechanical energy sources.