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Find video protocols related to scientific articles indexed in Pubmed.
Luminescence, patterned metallic regions, and photon-mediated electronic changes in single-sided fluorinated graphene sheets.
ACS Nano
PUBLISHED: 08-12-2014
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Single-sided fluorination has been predicted to open an electronic band gap in graphene and to exhibit unique electronic and magnetic properties; however, this has not been substantiated by experimental reports. Our comprehensive experimental and theoretical study of this material on a SiC(0001) substrate shows that single-sided fluorographene exhibits two phases, a stable one with a band gap of ?6 eV and a metastable one, induced by UV irradiation, with a band gap of ?2.5 eV. The metastable structure, which reverts to the stable "ground-state" phase upon annealing under emission of blue light, in our view is induced by defect states, based on the observation of a nondispersive electronic state at the top of the valence band, not unlike that found in organic molecular layers. Our structural data show that the stable C2F ground state has a "boat" structure, in agreement with our X-ray magnetic circular dichroism data, which show the absence of an ordered magnetic phase. A high flux of UV or X-ray photons removes the fluorine atoms, demonstrating the possibility of lithographically patterning conducting regions into an otherwise semiconducting 2D material.
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In situ electrokinetic remediation of As-, Cu-, and Pb-contaminated paddy soil using hexagonal electrode configuration: a full scale study.
Environ Sci Pollut Res Int
PUBLISHED: 08-09-2014
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We investigated the in situ applicability of the electrokinetic process with a hexagonal electrode configuration in order to remediate arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated paddy rice field soil at a field scale (width 17 m, length 12.2 m, and depth 1.6 m). An iron electrode was used in order to prevent the severe acidification of the soil near the anode. We selected ethylenediaminetetraacetic acid (EDTA) as a pursing electrolyte to enhance the extraction of Cu and Pb. The system removed 44.4 % of the As, 40.3 % of the Cu, and 46.6 % of the Pb after 24 weeks of operation. Fractionation analysis showed that the As bound to amorphous ion (Fe) and aluminum (Al) oxyhydroxides was changed into a form of As specifically bound. In the case of Cu and Pb, the fraction bound to Fe-Mn oxyhydroxide primarily decreased. The EDTA formed negatively charged complexes with Cu and Pb, and those complexes were transported toward the anode. The energy consumption was very low compared to that on a small scale because there was less energy consumption due to Joule heating. These results show that the in situ electrokinetic process could be applied in order to remediate paddy rice fields contaminated with multiple metals.
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Pyrolysis and co-pyrolysis of Laminaria japonica and polypropylene over mesoporous Al-SBA-15 catalyst.
Nanoscale Res Lett
PUBLISHED: 08-01-2014
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The catalytic co-pyrolysis of a seaweed biomass, Laminaria japonica, and a typical polymer material, polypropylene, was studied for the first time. A mesoporous material Al-SBA-15 was used as a catalyst. Pyrolysis experiments were conducted using a fixed-bed reactor and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). BET surface area, N2 adsorption-desorption isotherms, and NH3 temperature programmed desorption were measured to examine the catalyst characteristics. When only L. japonica was pyrolyzed, catalytic reforming slightly increased the gas yield and decreased the oil yield. The H2O content in bio-oil was increased by catalytic reforming from 42.03 to 50.32 wt% due to the dehydration reaction occurring on the acid sites inside the large pores of Al-SBA-15. Acids, oxygenates, mono-aromatics, poly aromatic hydrocarbons, and phenolics were the main components of the bio-oil obtained from the pyrolysis of L. japonica. Upon catalytic reforming over Al-SBA-15, the main oxygenate species 1,4-anhydro-d-galactitol and 1,5-anhydro-d-manitol were completely removed. When L. japonica was co-pyrolyzed with polypropylene, the H2O content in bio-oil was decreased dramatically (8.93 wt% in the case of catalytic co-pyrolysis), contributing to the improvement of the oil quality. A huge increase in the content of gasoline-range and diesel-range hydrocarbons in bio-oil was the most remarkable change that resulted from the co-pyrolysis with polypropylene, suggesting its potential as a transport fuel. The content of mono-aromatics with high economic value was also increased significantly by catalytic co-pyrolysis.
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Catalytic conversion of cellulose over mesoporous Y zeolite.
J Nanosci Nanotechnol
PUBLISHED: 04-25-2014
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Mesoporous Y zeolite (Meso-Y) was applied, for the first time, to the catalytic pyrolysis of cellulose which is a major constituent of lignocellulosic biomass, to produce high-quality bio-oil. A representative mesoporous catalyst Al-MCM-41 was also used to compare its catalytic activity with that of Meso-Y. Pyrolysis-gas chromatography/mass spectrometry was used for the experiments. Meso-Y, with higher acidity, led to larger yields of aromatics and furans with high value-added than Al-MCM-41, resulting in the production of bio-oil with higher quality. The effect of temperature on the catalytic pyrolysis was not significant within the range of 400-500 degrees C. When the Meso-Y to cellulose ratio was increased from 1/1 via 2/1 to 3/1, the deoxygenation efficiency increased, leading to increased yield of aromatics.
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Removal of NO(x) at low temperature over mesoporous alpha-Mn2O3 catalyst.
J Nanosci Nanotechnol
PUBLISHED: 04-22-2014
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Low-temperature selective catalytic reduction was carried out over various kinds of manganese oxide (MnOx) catalysts. Mesoporous alpha-Mn2O3, commercial bulk Mn2O3, and Mn/SBA-15 were used as the catalyst. The NOx removal performances of the catalysts were compared. Three different amounts of Mn (5, 10, and 15 wt%) were impregnated on SBA-15 to synthesize Mn/SBA-15. The physical and chemical properties of the catalysts were examined by Brunauer-Emmett-Teller, X-ray diffraction, X-ray photoelectron spectroscopy, and H2-temperature programmed reduction analyses. Of all catalysts examined, mesoporous alpha-Mn2O3 exhibited the highest low-temperature SCR de-NOx efficiency, reaching about 90% at 175 degrees C. This is attributed to strong reducing ability and high oxygen mobility of mesoporous alpha-Mn2O3 and well dispersed Mn2O3 in its mesoporous framework.
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Conversion of kraft lignin over hierarchical MFI zeolite.
J Nanosci Nanotechnol
PUBLISHED: 04-22-2014
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Catalytic pyrolysis of kraft lignin was carried out using pyrolysis gas chromatography/mass spectrometry. Hierarchical mesoporous MFI was used as the catalyst and another mesoporous material Al-SBA-15 was also used for comparison. The characteristics of mesoporous MFI were analyzed by X-ray diffraction patterns, N2 adsorption-desorption isotherms, and temperature programmed desorption of NH3. Two catalyst/lignin mass ratios were tested: 5/1 and 10/1. Aromatics and alkyl phenolics were the main products of the catalytic pyrolysis of lignin over mesoporous MFI. In particular, the yields of mono-aromatics such as benzene, toluene, ethylbenzene, and xylene were increased substantially by catalytic upgrading. Increase in the catalyst dose enhanced the production of aromatics further, which is attributed to decarboxylation, decarbonlyation, and aromatization reactions occurring over the acid sites of mesoporous MFI.
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In situ catalytic pyrolysis of miscanthus over modified SBA-15 catalysts using Py-GC/MS.
J Nanosci Nanotechnol
PUBLISHED: 04-22-2014
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Various SBA-15-based catalysts, Si-SBA-15, Pt/Si-SBA-15, Al-SBA-15, and Pt/Al-SBA-15, were applied to the catalytic pyrolysis of miscanthus. Pt nanoparticles with three different sizes, 1.7 nm, 2.9 nm, and 7.1 nm, were used to synthesize Pt/Si-SBA-15 and Pt/Al-SBA-15. Pyrolysis-gas chromatography/mass spectrometry was used for the pyrolysis experiments. The catalysts were characterized by X-ray diffraction patterns, transmittance electron microscopy, N2 adsorption-desorption, and Brunaure-Emmett-Teller surface area. The product species distribution of pyrolysis of miscanthus was significantly affected by the acid property of the catalyst and the presence of Pt. In particular, Pt/Al-SBA-15, which has both acid sites and Pt, changed the product species distribution to the largest extent; the main products were phenolics and furans. The effect of Pt particle size on the species distribution of pyrolysis product was negligible.
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Hydroisomerization of n-dodecane over Pt/Al-MCM-48 catalysts.
J Nanosci Nanotechnol
PUBLISHED: 04-17-2014
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The objective of this study is to evaluate the catalytic potential of Pt/Al-MCM-48 catalysts in hydroisomerization of n-dodecane. The effects of the Si/Al ratio and platinum loading on the acid characteristics of Al-MCM-48 and the catalytic performance in n-dodecane hydroisomerization were analyzed. The catalysts were characterized by X-ray diffraction, nitrogen adsorption, infrared spectroscopy of pyridine adsorption, and temperature programmed desorption of ammonia. The number of weak strength acid sites on Al-MCM-48 increased with 0.5 wt% platinum loading. The weak strength acid sites of Pt/Al-MCM-48 catalysts were ascribed to Lewis acid sites, which can be confirmed by NH3-TPD and FTIR spectra of pyridine adsorption. Iso-dodecane can be produced with high selectivity in n-dodecane hydrosisomerization over Pt/Al-MCM-48 catalysts. This is attributed to the mild acidic properties of Pt/Al-MCM-48 catalysts.
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Application of mesoporous Al-MCM-48 material to the conversion of lignin.
J Nanosci Nanotechnol
PUBLISHED: 04-17-2014
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Al-MCM-48 was applied to the catalytic pyrolysis of lignin for the first time. The pyrolysis reaction and in-situ product were analyzed by pyrolysis gas chromatography/mass spectrometry. The main products of the non-catalytic pyrolysis of lignin were phenols. The use of Al-MCM-48 increased the production of light phenols considerably. The yields of high-value-added compounds, such as hydrocarbons and aromatics, were also increased by catalytic upgrading. Al-MCM-48 is believed to promote cracking, aromatization and deoxygenation, such as decarbonylation. On the other hand, Si-MCM-48, which has no acid sites, showed lower deoxygenation efficiency than Al-MCM-48. Al-MCM-48 could be regenerated by calcining in air.
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Catalytic upgrading of xylan over mesoporous Y catalyst.
J Nanosci Nanotechnol
PUBLISHED: 04-17-2014
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In-situ catalytic cracking of xylan, a model compound of hemicellulose, was carried out using pyrolysis-gas chromatography/mass spectrometry over mesoporous Y for the first time. Experiments were conducted at three different temperatures, 400 degrees C, 450 degrees C, and 500 degrees C, to investigate the effect of reaction temperature. Three different biomass-to-catalyst ratios, 1:1, 1:2, and 1:3, were tested at 500 degrees C to examine the effect of catalyst dose. In addition, the catalytic activity of mesoporous Y was compared with that of Al-MCM-41. The catalysts used were characterized by N2 adsorption-desorption, temperature programmed desorption of NH3, and X-ray diffraction. The main pyrolysis products of xylan were acids, hydrocarbons, phenolics, oxygenates, aromatics, and polycyclic aromatic hydrocarbons. Mesoporous Y, which has acid sites with larger quantity and stronger acidity than those of Al-MCM-41, was shown to enhance the quality of bio-oil to a larger extent, producing a larger quantity of high-value-added products, such as aromatics and furans.
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Size-dependent clearance of gold nanoparticles from lungs of Sprague-Dawley rats after short-term inhalation exposure.
Arch. Toxicol.
PUBLISHED: 04-13-2014
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Gold nanoparticles are known to be distributed to many tissues following their oral, inhalation, or intravenous exposure. Information on the biodistribution and clearance of gold nanoparticles from these tissues is, therefore, important to understand their behavior in vivo. To study the effect of size on the biodistribution of gold nanoparticles, Sprague-Dawley rats were exposed by inhalation to small gold nanoparticles (13 nm in diameter on average) at an exposure concentration of 12.8 ± 2.42 µg/m(3), and to large gold nanoparticles (105 nm in diameter on average) at an exposure concentration of 13.7 ± 1.32 µg/m(3). The experimental animals were exposed to the gold nanoparticles and the control animals to fresh air for 5 days (6 h/day), followed by a recovery period of 1, 3, and 28 days in fresh air. None of the exposed animals exhibited any toxic response to the gold nanoparticles. Despite the difference in size, both small and large gold nanoparticles deposited mainly in rat lungs. Their biodistribution from the lungs to secondary target organs was significantly higher with the small compared to the large gold nanoparticles. While the large gold nanoparticles were only found in the blood, the small gold nanoparticles were detected in the liver, spleen, brain, testes, and blood. In addition, the elimination half-life of the small gold nanoparticles from the lungs was significantly shorter than that of the large gold nanoparticles. The present data may, therefore, suggest that the smaller gold nanoparticles are able to translocate from the lungs, the primary exposure organ to extrapulmonary organs at a faster rate than the larger gold nanoparticles and thus confirming previous observations reported in the literature.
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Excited-state dynamics of bis(9-fluorenyl)methane and its derivative 9-(9-ethylfluorenyl)-9'-fluorenylmethane: steric effect on energetics and dynamics of ground- and excited-state conformations.
J Phys Chem A
PUBLISHED: 03-05-2014
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Intramolecular excimer formation of bis(9-fluorenyl)methane (BFM) and 9-(9'-ethylfluorenyl)-9-fluorenylmethane (EFFM), in which an ethyl group is substituted to a 9-H atom in BFM, was studied by means of steady-state and time-resolved fluorescence. Ab initio and DFT calculations enabled the prediction of three conformers as stable species of orthogonal, trans-gauche, and gauche-gauche. The theoretical and experimental results reveal that the substitution effect is also found to appreciably influence the energies, spectroscopy, and kinetics associated with the interconversion of various conformers of the diaryl compounds. We have not observed the rising components in the excimer fluorescence decay of BFM and EFFM in PMMA as observed in the liquid solutions probably because of the existence of the sandwich conformer responsible for the excimer fluorescence prior to the laser irradiation.
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Multi-resistive reduced graphene oxide diode with reversible surface electrochemical reaction induced carrier control.
Sci Rep
PUBLISHED: 02-19-2014
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The extended application of graphene-based electronic devices requires a bandgap opening in order to realize the targeted device functionality. Since the bandgap tuning of pristine graphene is limited to 360 meV, the chemical modification of graphene is considered essential to achieve a large bandgap opening at the expense of electrical properties degradation. Reduced graphene oxide (RGO) has attracted significant interest for fabricating graphene-based semiconductors since it has several advantages over other forms of chemically modified graphene; such as tunable bandgap opening, decent electrical properties, and easy synthesis. Because of the reduced bonding nature of RGO, the role of metastable oxygen in the RGO matrix is recently highlighted and it may offer emerging ionic devices. In this study, we show that multi-resistivity RGO/n-Si diodes can be obtained by controlling the RGO thickness at a nanometer scale. This is made possible by (1) a metastable lattice-oxygen drift within bulk RGO and (2) electrochemical ambient hydroxyl (OH) formation at the RGO surface. The effect demonstrated in a p-RGO/n-Si heterojunction diode is equivalent to electrochemically driven reversible electronic manipulation and therefore provides an important basis for the application of O bistability in RGO for chemical sensors and electrocatalysis.
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Inhibitory effects of PPAR? ligands on TGF-?1-induced corneal myofibroblast transformation.
Am. J. Pathol.
PUBLISHED: 01-08-2014
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Corneal scarring, whether caused by trauma, laser refractive surgery, or infection, remains a significant problem for humans. Certain ligands for peroxisome proliferator-activated receptor gamma (PPAR?) have shown promise as antiscarring agents in a variety of body tissues. In the cornea, their relative effectiveness and mechanisms of action are still poorly understood. Here, we contrasted the antifibrotic effects of three different PPAR? ligands (15-deoxy-?12,14-prostaglandin J2, troglitazone, and rosiglitazone) in cat corneal fibroblasts. Western blot analyses revealed that all three compounds reduced transforming growth factor (TGF)-?1-driven myofibroblast differentiation and up-regulation of ?-smooth muscle actin, type I collagen, and fibronectin expression. Because these effects were independent of PPAR?, we ascertained whether they occurred by altering phosphorylation of Smads 2/3, p38 mitogen-activated protein kinase, stress-activated protein kinase, protein kinase B, extracellular signal-regulated kinase, and/or myosin light chain 2. Only p38 mitogen-activated protein kinase phosphorylation was significantly inhibited by all three PPAR? ligands. Finally, we tested the antifibrotic potential of troglitazone in a cat model of photorefractive keratectomy-induced corneal injury. Topical application of troglitazone significantly reduced ?-smooth muscle actin expression and haze in the stromal ablation zone. Thus, the PPAR? ligands tested here showed great promise as antifibrotics, both in vitro and in vivo. Our results also provided new evidence for the signaling pathways that may underlie these antifibrotic actions in corneal fibroblasts.
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Efficacy of short-term high-dose statin pretreatment in prevention of contrast-induced acute kidney injury: updated study-level meta-analysis of 13 randomized controlled trials.
PLoS ONE
PUBLISHED: 01-01-2014
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There have been conflicting results across the trials that evaluated prophylactic efficacy of short-term high-dose statin pre-treatment for prevention of contrast-induced acute kidney injury (CIAKI) in patients undergoing coronary angiography (CAG). The aim of the study was to perform an up-to-date meta-analysis regarding the efficacy of high-dose statin pre-treatment in preventing CIAKI.
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Catalytic conversion of Undaria Pinnatifida over nanoporous materials using Py-GC/MS.
J Nanosci Nanotechnol
PUBLISHED: 11-26-2013
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Catalytic pyrolysis of Undaria Pinnatifida was carried out over a nanoporous Al-SBA-15 catalyst for the first time. Pt nanoparticles were added to Al-SBA-15 to generate a Pt/Al-SBA-15 catalyst. The effect of the addition of the Pt nanoparticles on the catalytic pyrolysis was investigated. For rapid product analysis and catalyst evaluation, a pyrolysis-gas chromatography/mass spectrometry was used. The characteristics of the catalysts were analyzed using X-ray diffraction, nitrogen adsorption-desorption, transmission electron microscope, NH3 temperature programmed desorption, and inductively coupled plasma optical emission spectrometer. Compared to the non-catalytic pyrolysis, catalytic pyrolysis over Al-SBA-15 produced a higher-quality bio-oil with a high stability and a low oxygen content. When Pt/Al-SBA-15 was used, compared to Al-SBA-15, the improvement of bio-oil quality was more profound; the yield of high-value-added aromatics increased, while the yields of acids and oxygenates decreased.
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Catalytic oxidation of benzene using mesoporous alpha-Mn2O3.
J Nanosci Nanotechnol
PUBLISHED: 11-20-2013
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The catalytic oxidation of benzene was carried out over mesoporous alpha-Mn2O3, MnOx/KIT-6, and bulk commercial Mn oxides (Mn2O3, MnO2, and MnO). The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, and temperature-programmed reduction analysis. MnOx/KIT-6, prepared by impregnating MnOx on KIT-6, exhibited a low activity for the oxidation of benzene, whereas mesoporous alpha-Mn2O3, manufactured using KIT-6 as the template, showed a high activity. The order of the activities of bulk Mn oxides for benzene decomposition was shown to be Mn2O3 > MnO2 > MnO. Therefore, the high activity of mesoporous alpha-Mn2O3 is attributed to the uniform distribution of highly active Mn2O3 in the mesoporous structure.
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Effect of Pt particle size on the hydroisomerization of n-dodecane over Pt/Ai-SBA-15 catalysts.
J Nanosci Nanotechnol
PUBLISHED: 11-12-2013
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The hydroisomerization of n-dodecane was carried out over platinum-impregnated Al-SBA-15 as a bifunctional catalyst. A range of Pt/Al-SBA-15 catalysts with a Pt particle size of 1.7, 2.9 and 7.1 were prepared to examine the effect of the Pt particle size on the activity and selectivity for the hydroisomerization of n-dodecane. The catalysts were characterized by transmission electron microscopy, X-ray diffraction, nitrogen adsorption, pyridine Fourier transform infrared spectroscopy and NH3 temperature programmed desorption. The hydroisomerization of n-dodecane was performed in a batch-type reactor at 350 degrees C and 20 bar. The Pt(2.9)/Al-SBA-15 catalyst showed the highest selectivity to iso-dodecane due to its largest number of medium strength Brønsted acid sites and the optimum ratio of metallic/acid sites.
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Field application of electrokinetic remediation for multi-metal contaminated paddy soil using two-dimensional electrode configuration.
Environ Sci Pollut Res Int
PUBLISHED: 08-22-2013
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In this study, we evaluated the feasibility of in situ electrokinetic remediation for arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated soil, in a pilot-scale field application with two-dimensional electrode configurations. Square and hexagonal configurations with different electrode spacing, 1 m and 2?m, were investigated under a constant 100 V. A square configuration with electrode spacing of 2 m removed 61.5 % of As, 11.4 % of Cu, and 0.9 % of Pb, respectively, and a hexagonal configuration with the same spacing showed a higher removal efficiency in top (59 % of As, 0-0.5 m) and middle (53 % of As, 0.5-1.0 m) layers, but much lower removal efficiency in the bottom layer (1-1.5 m), which was thought to be due to groundwater flow through periodic rise and fall of tides. Fractionation analysis showed that As bound to Fe-Mn oxyhydroxide was the main form of As removed by the electrokinetic process. The two-dimensional configuration wasted less electrical energy by Joule heating, and required fewer electrode installations, compared to the one-dimensional electrode configuration.
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Multilayered nano-prism vertex tips for tip-enhanced Raman spectroscopy and imaging.
Analyst
PUBLISHED: 07-26-2013
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We presented a scalable fabrication method for the preparation of multilayered nano-prism vertex (NV)-tips whose dimensions can be controlled for tip-enhanced Raman spectroscopy (TERS). The NV-tip had sharp vertices (diameter ~20 nm) originated from the chemical lift-off process after the angle-grinding process, enabling high resolution imaging. TERS measurements were performed on brilliant cresyl blue (BCB) molecules using a Ag/Au NV-tip, revealing the enhanced field localization at the vertices of the NV-tip. Furthermore, we could observe the polarization effect of the NV-tip. Our NV-tips should be a powerful tool for basic research on TERS experiments and SPM applications.
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A selective functionalized mesoporous silica-supported Rh catalyst for effective 1-octene hydroformylation.
J Nanosci Nanotechnol
PUBLISHED: 06-15-2013
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Through different functionalization methods, three kinds of Rh-immobilized mesoporous silicas have successfully been prepared to investigate catalytic behavior, including yield and the linear/branched ratio of aldehyde (L/B) in 1-octene hydroformylation. A conventional post grafting method and two kinds of selective bifunctionalized methods for modification of the mesoporous silica have been applied for this purpose. A relatively high L/B (> 2.0) was effectively achieved using Rh-immobilized inner pores in the MCM-41 support due to the confinement effects of the Rh complex in the nanospace. Moreover, the Rh-immobilized MCM-41 catalyst, passivated with trimethylchlorosilane (TMCS) only on the external surface, showed fairly good yields of the aldehyde (> 40%).
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Removal of indoor formaldehyde over CMK-8 adsorbents.
J Nanosci Nanotechnol
PUBLISHED: 06-15-2013
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CMK-8, a mesoporous carbon material, was activated using different methods for the adsorption of low-concentration airborne formaldehyde. KOH and ammonia treatments were used to activate CMK-8. A CMK-8 sample was treated with KOH first followed by an ammonia-treatment at 700 degrees C to determine the effect of a combination of the two treatment methods. The adsorbents prepared were characterized by X-ray diffraction, N2 adsorption-desorption and X-ray photoelectron spectroscopy. The KOH treatment increased the concentration of oxygen functional groups, whereas the ammonia-treatment generated a significant amount of nitrogen functional groups. The formaldehyde adsorption efficiency was highest when both KOH- and ammonia-treatments were applied to CMK-8. The ammonia-treated CMK-8 exhibited higher formaldehyde adsorption ability than the KOH-treated one, whereas non-activated CMK-8 showed the lowest formaldehyde adsorption efficiency. The number of nitrogen functional groups and the specific surface area appeared to significantly affect the formaldehyde adsorption capability of the adsorbents, whereas oxygen functional groups played a less important role.
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Catalytic fast pyrolysis of lignin over mesoporous Y zeolite using Py-GC/MS.
J Nanosci Nanotechnol
PUBLISHED: 06-15-2013
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The catalytic pyrolysis of lignin was carried out at 500 degrees C using pyrolysis gas chromatography/mass spectrometry. In-situ vapor cracking method, in which the vapor-phase products from the noncatalytic pyrolysis step were catalytically upgraded in the second step, was used. Mesoporous Y zeolite, which was synthesized from commercial zeolite Y (CBV720) using the pseudomorphic synthesis method, was used for the catalytic pyrolysis of lignin for the first time. Further, a representative mesoporous material, Al-MCM-41, was applied for the catalytic pyrolysis of lignin. The main products of the non-catalytic pyrolysis of lignin were phenolic compounds because lignin mainly comprises phenylpropane units. Catalytic upgrading of the non-catalytic pyrolysis products resulted in increased yields of low-molecular-mass phenolics, mono aromatics, and poly aromatic hydrocarbons (PAHs). The production of mono aromatics and PAHs was enhanced remarkably when the more acidic mesoporous Y zeolite was used. Conversely, the yield-of alkoxy phenolics was higher when the less acidic Al-MCM-41 was used. With increasing mesoporous Y/lignin ratio, the yield of total phenolics decreased and that of light phenolics increased. The yields of mono aromatics and PAHs increased sharply with increasing mesoporous Y/lignin ratio.
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Bio-oil upgrading via catalytic pyrolysis of waste mandarin residue over SBA-15 catalysts.
J Nanosci Nanotechnol
PUBLISHED: 06-15-2013
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Mesoporous SBA-15-based catalysts were applied, for the first time, to the pyrolysis of waste mandarin residue. Si-SBA-15 with few acid sites, Al-SBA-15 with a significant amount of acid sites owing to the alumination treatment, and Pt/Al-SBA-15, which was synthesized by incorporating 7.1-nm Pt nanoparticles on Al-SBA-15, were used. Pyrolysis experiments were conducted by pyrolysis gas chromatography/mass spectroscopy to determine the catalytic activities of the catalysts used. X-ray diffraction, nitrogen adsorption, NH3-temperature-programmed desorption and transmission electron microscopy were used to characterize the catalysts. Al-SBA-15 produced higher quality bio-oil than Si-SBA-15 due to its better deoxygenation and cracking performance stemming from the presence of acid sites. Pt/Al-SBA-15 showed the highest oxygenate conversion as well as the largest yield of high-value-added compounds, such as aromatics, low-molecular-mass hydrocarbons and furans.
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Catalytic characteristics of titanium oxide/MCM-41 synthesized by liquid phase atomic layer deposition.
J Nanosci Nanotechnol
PUBLISHED: 06-13-2013
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Titanium oxide on MCM-41 was synthesized using the atomic layer deposition (ALD) method. BET, XRD, NH3-TPD and EDS were used to study the structural properties of the supported titanium oxides. The surface area of catalysts decreased with increasing of the amount of titanium in precursor solution. However, unique characteristics of 2-D hexagonal structure of mesopores in MCM-41 were maintained. The Ti/MCM-41 catalyst with titanium loading of 12.6 wt% showed the highest activity in the dehydration of 2-butanol, which was attributed to the highest overall amount of acid sites among the Ti/MCM-41 catalysts.
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Catalytic pyrolysis of waste mandarin over nanoporous materials.
J Nanosci Nanotechnol
PUBLISHED: 05-08-2013
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Catalytic pyrolysis of waste mandarin was performed using nanoporous catalysts. AI-MCM-41 and Meso-MFI, which had different acid characteristics, were used. In addition, the characteristics of Pt/Meso-MFI were compared with those of Meso-MFI. To analyze the characteristics of the catalyst samples, Brunauer-Emmett-Teller surface area, temperature programmed desorption of NH3, and N2 adsorption-desorption analyses were performed. In addition, pyrolysis gas chromatography/mass spectrometry was used to facilitate the direct analysis of the pyrolytic products. The products obtained from catalytic pyrolysis contained a greater amount of valuable components than did those obtained from non-catalytic pyrolysis, indicating that catalytic pyrolysis improved the quality of the bio-oil. Additionally, valuable products such as furan and aromatic compounds were produced in greater quantities when Meso-MFI was used. When Pt/Meso-MFI was used, the amounts of furan and aromatic compounds produced increased even further.
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Hydroconversion of n-dodecane over nanoporous catalysts.
J Nanosci Nanotechnol
PUBLISHED: 05-08-2013
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Platinum catalysts impregnated on different nanoporous materials, Meso-MFI, Si-SBA-15 and AI-SBA-15, were synthesized, and the hydroconversion of n-dodecane over these catalysts was performed. The catalytic characteristics were analyzed by Brunauer-Emmett-Teller surface area, X-ray diffraction, N2-adsorption-desorption and temperature programmed desorption of NH3. The effects of operation parameters, such as temperature and pressure, on the catalytic activities were investigated. The catalytic activities were affected considerably by the acidic properties of the catalysts, temperature and pressure. Higher acidity, high temperature and low hydrogen pressure resulted in higher hydroconversion and facilitated hydrocracking. The weak acidity, low temperature and high hydrogen pressure resulted in lower hydroconversion and higher selectivity to i-dodecane.
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Catalytic oxidation of benzene with ozone over Mn/KIT-6.
J Nanosci Nanotechnol
PUBLISHED: 05-08-2013
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Benzene is one of the target compounds to be removed from air owing to its carcinogenicity. In this study, benzene oxidation with ozone over a MnOx/KIT-6 catalyst was carried out for the first time. MnOx/KIT-6 was synthesized using two different Mn precursors: Mn acetate and Mn nitrate. The characteristics of the synthesized catalysts were examined by X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, Brunauer-Emmett-Teller (BET) surface area, and N2 adsorption-desorption. The catalytic activity was found to be dependent on the amount of ozone consumed and the dispersion and reducibility of MnOx on the catalyst surface.
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Biodiesel production via the transesterification of soybean oil using waste starfish (Asterina pectinifera).
Appl. Biochem. Biotechnol.
PUBLISHED: 04-30-2013
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Calcined waste starfish was used as a base catalyst for the production of biodiesel from soybean oil for the first time. A batch reactor was used for the transesterification reaction. The thermal characteristics and crystal structures of the waste starfish were investigated by thermo-gravimetric analysis and X-ray diffraction. The biodiesel yield was determined by measuring the content of fatty acid methyl esters (FAME). The calcination temperature appeared to be a very important parameter affecting the catalytic activity. The starfish-derived catalyst calcined at 750 °C or higher exhibited high activity for the transesterification reaction. The FAME content increased with increasing catalyst dose and methanol-over-oil ratio.
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Catalytic pyrolysis of mandarin residue from the mandarin juice processing industry.
Bioresour. Technol.
PUBLISHED: 03-07-2013
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In this study, the catalytic pyrolysis of mandarin residue from the mandarin juice processing industry was carried out using pyrolysis gas chromatography/mass spectroscopy and employing microporous zeolite catalysts, HZSM-5 (SiO2/Al2O3=23 and 80) and HBeta (SiO2/Al2O3=25). The effect of acidity of the catalyst was investigated by comparing the activity of two HZSM-5 catalysts with different SiO2/Al2O3 ratios. The effect of catalyst structure was explored by comparing the results obtained using HZSM-5 (23) and HBeta. Most oxygenates produced from non-catalytic pyrolysis were removed by catalytic upgrading, whereas the yields of mono-aromatics, which are important feedstock materials for the chemical industry, increased considerably, improving the quality of the bio-oil produced. HZSM-5 (23), having the highest acidity among the catalysts used in this study, showed superior catalytic activity to those of HZSM-5 (80) and HBeta. Pt/HZSM-5 (23) and Ga/HZSM-5 (23) resulted in an even higher yield of aromatics.
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Paraoxonase 1 gene polymorphism does not affect clopidogrel response variability but is associated with clinical outcome after PCI.
PLoS ONE
PUBLISHED: 02-13-2013
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Paraoxonase (PON) is a high-density-lipoprotein (HDL) associated enzyme with antioxidative and anti-atherogenic property. Its function is associated with coronary artery disease and its activity genetically controlled. We evaluated whether genetic variation of PON-1 is associated with clinical outcome in a large cohort of Korean patients with drug-eluting stents implantation.
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CYP3A4 genetic status may be associated with increased vulnerability to the inhibitory effect of calcium-channel blockers on clopidogrel.
Circ. J.
PUBLISHED: 02-09-2013
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Calcium-channel blockers (CCBs) inhibit the CYP3A4 enzyme, which is involved in clopidogrel activation. Studies have shown conflicting results regarding the effect of concomitant CCB administration on clopidogrel response. We investigated the relationship between CYP3A4 genotype and the inhibitory effect of CCBs on clopidogrel response.
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Dependence of efficiencies in GaN-based vertical blue light-emitting diodes on the thickness and doping concentration of the n-GaN layer.
Opt Express
PUBLISHED: 02-08-2013
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We investigate the dependence of various efficiencies in GaN-based vertical blue light-emitting diode (LED) structures on the thickness and doping concentration of the n-GaN layer by using numerical simulations. The electrical efficiency (EE) and the internal quantum efficiency (IQE) are found to increase as the thickness or doping concentration increases due to the improvement of current spreading. On the contrary, the light extraction efficiency (LEE) decreases with increasing doping concentration or n-GaN thickness by the free-carrier absorption. By combining the results of EE, IQE, and LEE, wall-plug efficiency (WPE) of the vertical LED is calculated, and the optimum thickness and doping concentration of the n-GaN layer is found for obtaining the maximum WPE.
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Topical rosiglitazone is an effective anti-scarring agent in the cornea.
PLoS ONE
PUBLISHED: 01-01-2013
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Corneal scarring remains a major cause of blindness world-wide, with limited treatment options, all of which have side-effects. Here, we tested the hypothesis that topical application of Rosiglitazone, a Thiazolidinedione and ligand of peroxisome proliferator activated receptor gamma (PPAR?), can effectively block scar formation in a cat model of corneal damage. Adult cats underwent bilateral epithelial debridement followed by excimer laser ablation of the central corneal stroma to a depth of ~160 µm as a means of experimentally inducing a reproducible wound. Eyes were then left untreated, or received 50 µl of either 10 µM Rosiglitazone in DMSO/Celluvisc, DMSO/Celluvisc vehicle or Celluvisc vehicle twice daily for 2 weeks. Cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and post-mortem immunohistochemistry for alpha smooth muscle actin (?SMA). Impacts of the wound and treatments on optical quality were assessed using wavefront sensing and optical coherence tomography at 2, 4, 8 and 12 weeks post-operatively. In parallel, cat corneal fibroblasts were cultured to assess the effects of Rosiglitazone on TGF?-induced ?SMA expression. Topical application of Rosiglitazone to cat eyes after injury decreased ?SMA expression and haze, as well as the induction of lower-order and residual, higher-order wavefront aberrations compared to vehicle-treated eyes. Rosiglitazone also inhibited TGF?-induced ?SMA expression in cultured corneal fibroblasts. In conclusion, Rosiglitazone effectively controlled corneal fibrosis in vivo and in vitro, while restoring corneal thickness and optics. Its topical application may represent an effective, new avenue for the prevention of corneal scarring with distinct advantages for pathologically thin corneas.
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Preparation of mesoporous alumina particles by spray pyrolysis and application to double bond migration of 2-butene.
J Nanosci Nanotechnol
PUBLISHED: 11-30-2011
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The objective of the present study is to investigate the catalytic performance of mesoporous alumina that were prepared via spray pyrolysis for double bond migration from 2-butene to 1-butene. The mesoporous alumina particles were prepared via spray pyrolysis by changing the types of organic surfactants and Al precursors. The texture and acidic properties of mesoporous alumina were analyzed through N2 adsorption, SEM, ammonia-temperature programmed desorption, and FT-IR of adsorbed pyridine. The morphologies and texture properties of the mesoporous alumina were found to have been strongly influenced by the combination of the Al precursor and the structure-directing agents. The mesoporous alumina samples had two kinds of acidic sites: a Lewis acid site and a H-bonded weak acid site. 1-Butene was produced selectively through double bond migration of 2-butene over all of the mesoporous alumina catalysts. The catalyst prepared by using a chloride compound as an aluminium precursor and CTAC as a structure-directing agent showed the highest activity in the double bond migration of 2-butene, which was attributed to its large surface area and an overall high amount of acid sites.
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Catalytic pyrolysis of oil fractions separated from food waste leachate over nanoporous acid catalysts.
J Nanosci Nanotechnol
PUBLISHED: 11-30-2011
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Oil fractions, separated from food waste leachate, can be used as an energy source. Especially, high quality oil can be obtained by catalytic cracking. In this study, nanoporous catalysts such as Al-MCM-41 and mesoporous MFI type zeolite were applied to the catalytic cracking of oil fractions using the pyrolysis gas chromatography/mass spectrometry. Mesoporous MFI type zeolite showed better textural porosity than Al-MCM-41. In addition, mesoporous MFI type zeolite had strong Brönsted acidity while Al-MCM-41 had weak acidity. Significant amount of acid components in the food waste oil fractions were converted to mainly oxygenates and aromatics. As a result of its well-defined nanopores and strong acidity, the use of a mesoporous MFI type zeolite produced large amounts of gaseous and aromatic compounds. High yields of hydrocarbons within the gasoline range were also obtained in the case of mesoporous MFI type zeolite, whereas the use of Al-MCM-41, which exhibits relatively weak acidity, resulted in high yields of oxygenates and diesel range hydrocarbons.
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Effect of Mn precursors on benzene oxidation with ozone over MnOx/MCM-41 at low temperature.
J Nanosci Nanotechnol
PUBLISHED: 11-23-2011
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Low temperature benzene oxidation in the presence of ozone on MnOx/MCM-41 catalysts has been studied. MnOx/MCM-41 catalysts were prepared from two different precursors, Mn(NO3)2 and Mn(CH3COO)2, and these samples were characterized by N2 sorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction. The characterization results showed that the MnOx/MCM-41 prepared from Mn(CH3COO)2 had higher oxygen mobility and dispersion than the MnOx/MCM-41 from Mn(NO3)2. As a result, the MnOx/MCM-41 obtained from Mn(CH3COO)2 showed higher catalytic activity for the oxidation of benzene using ozone; however, without ozone, the catalytic activity was negligible.
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Peroxisome proliferator-activated receptor-? activates endothelial progenitor cells to induce angio-myogenesis through matrix metallo-proteinase-9-mediated insulin-like growth factor-1 paracrine networks.
Eur. Heart J.
PUBLISHED: 09-14-2011
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The roles of peroxisome proliferator-activated receptor (PPAR)-? in vascular biology are mainly unknown. We investigated the effects of PPAR-? activation on the paracrine networks between endothelial progenitor cells (EPCs) and endothelial cells (ECs)/skeletal muscle.
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Direct imaging and chemical analysis of unstained DNA origami performed with a transmission electron microscope.
Chem. Commun. (Camb.)
PUBLISHED: 07-18-2011
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Here, we report a simple and rapid characterisation technique combining physical and chemical analysis for DNA origami with conventional TEM.
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A label-free, direct and noncompetitive FRET immunoassay for ochratoxin A based on intrinsic fluorescence of an antigen and antibody complex.
Chem. Commun. (Camb.)
PUBLISHED: 07-04-2011
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A label-free, direct and noncompetitive homogeneous immunoassay, in which ochratoxin A (OTA) coupled with the anti-OTA antibody participates in fluorescence resonance energy transfer (FRET), was developed for the detection of OTA with great specificity and a detection limit of 1 ng mL(-1).
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Catalytic pyrolysis of Laminaria japonica over nanoporous catalysts using Py-GC/MS.
Nanoscale Res Lett
PUBLISHED: 05-21-2011
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The catalytic pyrolysis of Laminaria japonica was carried out over a hierarchical meso-MFI zeolite (Meso-MFI) and nanoporous Al-MCM-48 using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The effect of the catalyst type on the product distribution and chemical composition of the bio-oil was examined using Py-GC/MS. The Meso-MFI exhibited a higher activity in deoxygenation and aromatization during the catalytic pyrolysis of L. japonica. Meanwhile, the catalytic activity of Al-MCM-48 was lower than that of Meso-MFI due to its weak acidity.
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Cross-cultural adaptation of the US consumer form of the short Primary Care Assessment Tool (PCAT): the Korean consumer form of the short PCAT (KC PCAT) and the Korean standard form of the short PCAT (KS PCAT).
Qual Prim Care
PUBLISHED: 05-18-2011
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It is well known that countries with well-structured primary care have better health outcomes, better health equity and reduced healthcare costs. This study aimed to culturally modify and validate the US consumer form of the short Primary Care Assessment Tool (PCAT) in primary care in the Republic of Korea (hereafter referred to as Korea).
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Subchronic inhalation toxicity of gold nanoparticles.
Part Fibre Toxicol
PUBLISHED: 05-14-2011
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Gold nanoparticles are widely used in consumer products, including cosmetics, food packaging, beverages, toothpaste, automobiles, and lubricants. With this increase in consumer products containing gold nanoparticles, the potential for worker exposure to gold nanoparticles will also increase. Only a few studies have produced data on the in vivo toxicology of gold nanoparticles, meaning that the absorption, distribution, metabolism, and excretion (ADME) of gold nanoparticles remain unclear.
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Effects of puffer (Sphoeroides rubripes) supplementation on disruption of antioxidant defense systems in ethanol-treated rats.
J. Nutr. Sci. Vitaminol.
PUBLISHED: 04-23-2011
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We investigated the effects of puffer (Sphoeroides rubripes) supplementation on antioxidant metabolism in ethanol-treated rats. Sprague-Dawley rats were randomly assigned into 4 groups of 7 rats each and fed (1) an AIN-93G diet (NC), (2) 25% ethanol (E), (3) 25% ethanol and an AIN-93G diet containing 1% puffer flesh (E+F), or (4) 25% ethanol and an AIN-93G diet containing 1% puffer skin (E+S) for 5 wk. At the end of the experimental period, the rats were sacrificed and their blood and organs were collected. To evaluate the effect of puffer supplementation, lipid-soluble antioxidant vitamin and conjugated diene (CD) levels, DNA damage, and mRNA expression of heme oxygenase-1 (HO-1) were assessed. Animals that were fed ethanol showed reduced plasma levels of lipid-soluble antioxidant vitamin and significantly increased levels of lipid peroxides, DNA damage, and HO-1 expression. Dietary supplementation with puffer conferred an antioxidant effect by significantly increasing the levels of ?-tocopherol, a lipid-soluble antioxidant vitamin, and by significantly decreasing the plasma levels of CD, DNA damage, and HO-1 expression. These results suggest that consumption of puffer improves the antioxidant status of ethanol-treated rats.
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Clinical outcomes of high on-treatment platelet reactivity in Koreans receiving elective percutaneous coronary intervention (from results of the CROSS VERIFY study).
Am. J. Cardiol.
PUBLISHED: 04-14-2011
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Platelet reactivity after clopidogrel therapy varies among patients. Whether clopidogrel response variability can predict clinical outcomes has not been verified in Asians. A prospective cohort was analyzed to evaluate clinical impact of clopidogrel response variability in patients who underwent elective percutaneous coronary intervention (PCI). A total of 809 consecutive patients receiving clopidogrel after elective PCI were followed for 1 year. On-treatment platelet reactivity (OPR) after clopidogrel therapy was measured with a point-of-care test, the VerifyNow P2Y12 assay. The primary end point was the composite of cardiac death and nonfatal myocardial infarction (MI) at 1 year. In this exclusively Korean cohort, the median OPR was 236 P2Y12 reactivity units. Using the definition of OPR ?235 P2Y12 reactivity units as high OPR (HOPR), 50.3% of the cohort showed HOPR. The group with HOPR had significantly higher rates of cardiac death and spontaneous MI (2.5% vs 0.5%, p = 0.022) than the group without HOPR. Multivariate-adjusted analysis showed that HOPR was an independent predictor of the composite of cardiac death and nonfatal MI. The difference in major adverse cardiac events between the groups with and without HOPR was more profound in those without major cardiovascular disease, such as hypertension, diabetes mellitus, or dyslipidemia. In conclusion, HOPR to clopidogrel was significantly associated with cardiac death and spontaneous MI after elective PCI, suggesting that clopidogrel response variability may be a significant risk factor of hard end points in Koreans.
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Removal of formaldehyde over amine functionalized SBA-15.
J Nanosci Nanotechnol
PUBLISHED: 04-02-2011
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Amine-functionalized SBA-15 materials were synthesized by a post synthesis method. Surface area and pore size decreased by attaching functional groups to the pore surface. Furthermore, pore volume was reduced with functionalization. The carbon and nitrogen content gradually increased with the number of amine groups in the silane precursors. Among the amine-functionalized SBA-15 materials, the SBA-15/TMSPDETA showed the highest removal activity given its high reactivity with formaldehyde.
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Catalytic conversion of 1,2-dichlorobenzene over mesoporous V2O5/TiO2 prepared from spray pyrolysis.
J Nanosci Nanotechnol
PUBLISHED: 04-02-2011
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Mesoporous V2O5/TiO2 particles were prepared by spray pyrolysis and applied to the catalytic oxidation of 1,2-dichlorobenzene (1,2-DCB). Two different precursors (alkoxide and nanoparticles) for the TiO2 support were used to determine the effects on the texture properties and the catalytic activity of the mesoporous V2O5/TiO2 particles. The 5 wt% V2O5/TiO2 particles had the largest surface area (173 m2/g) and 4.7 nm in average pore size. The catalytic activity of the V2O5/TiO2 particles depended strongly on the loading quantity of vanadium, whereas the P25-derived samples showed no significant change in catalytic activity with weight% of vanadium. The surface area of the V2O5/TiO2 particles prepared using the alkoxide precursor was larger than that of the particles prepared using P25 nanoparticles. The P25-derived V2O5/TiO2 particles, however, showed a higher catalytic activity compared with those alkoxide-derived, which is due to the difference in the vanadium quantity exposed to the pore surface. It was confirmed that the 10 wt% V2O5/TiO2 particles prepared by spray pyrolysis had an excellent activity for the oxidation of 1,2-DCB, particularly at temperatures below 300 degrees C.
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Utilization of a by-product produced from oxidative desulfurization process over Cs-mesoporous silica catalysts.
J Nanosci Nanotechnol
PUBLISHED: 04-02-2011
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We investigated the use of Cs-mesoporous silica catalysts to upgrade a by-product of oxidative desulfurization (ODS). Cs-mesoporous silica catalysts were characterized through N2 adsorption, XRD, CO2-temperature-programmed desorption, and XRF. Cs-mesoporous silica prepared by the direct incorporation method showed higher catalytic performance than a Cs/MCM-41 catalyst by impregnation method for the catalytic decomposition of sulfone compounds produced from ODS process.
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Catalytic pyrolysis of oilsand bitumen over nanoporous catalysts.
J Nanosci Nanotechnol
PUBLISHED: 03-31-2011
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The catalytic cracking of oilsand bitumen was performed over nanoporous materials at atmospheric conditions. The yield of gas increased with application of nanoporous catalysts, with the catalytic conversion to gas highest for Meso-MFI. The cracking activity seemed to correlate with pore size rather than weak acidity or surface area.
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Highly uniform and reproducible surface-enhanced Raman scattering from DNA-tailorable nanoparticles with 1-nm interior gap.
Nat Nanotechnol
PUBLISHED: 03-09-2011
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An ideal surface-enhanced Raman scattering (SERS) nanostructure for sensing and imaging applications should induce a high signal enhancement, generate a reproducible and uniform response, and should be easy to synthesize. Many SERS-active nanostructures have been investigated, but they suffer from poor reproducibility of the SERS-active sites, and the wide distribution of their enhancement factor values results in an unquantifiable SERS signal. Here, we show that DNA on gold nanoparticles facilitates the formation of well-defined gold nanobridged nanogap particles (Au-NNP) that generate a highly stable and reproducible SERS signal. The uniform and hollow gap (?1 nm) between the gold core and gold shell can be precisely loaded with a quantifiable amount of Raman dyes. SERS signals generated by Au-NNPs showed a linear dependence on probe concentration (R(2) > 0.98) and were sensitive down to 10 fM concentrations. Single-particle nano-Raman mapping analysis revealed that >90% of Au-NNPs had enhancement factors greater than 1.0 × 10(8), which is sufficient for single-molecule detection, and the values were narrowly distributed between 1.0 × 10(8) and 5.0 × 10(9).
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Size-dependent interaction of Au nanoparticles and graphene sheet.
Chem. Commun. (Camb.)
PUBLISHED: 02-03-2011
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We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent.
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Air-stable magnesium nanocomposites provide rapid and high-capacity hydrogen storage without using heavy-metal catalysts.
Nat Mater
PUBLISHED: 01-28-2011
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Hydrogen is a promising alternative energy carrier that can potentially facilitate the transition from fossil fuels to sources of clean energy because of its prominent advantages such as high energy density (142 MJ kg(-1); ref. 1), great variety of potential sources (for example water, biomass, organic matter), light weight, and low environmental impact (water is the sole combustion product). However, there remains a challenge to produce a material capable of simultaneously optimizing two conflicting criteria--absorbing hydrogen strongly enough to form a stable thermodynamic state, but weakly enough to release it on-demand with a small temperature rise. Many materials under development, including metal-organic frameworks, nanoporous polymers, and other carbon-based materials, physisorb only a small amount of hydrogen (typically 1-2 wt%) at room temperature. Metal hydrides were traditionally thought to be unsuitable materials because of their high bond formation enthalpies (for example MgH(2) has a ?Hf~75 kJ mol(-1)), thus requiring unacceptably high release temperatures resulting in low energy efficiency. However, recent theoretical calculations and metal-catalysed thin-film studies have shown that microstructuring of these materials can enhance the kinetics by decreasing diffusion path lengths for hydrogen and decreasing the required thickness of the poorly permeable hydride layer that forms during absorption. Here, we report the synthesis of an air-stable composite material that consists of metallic Mg nanocrystals (NCs) in a gas-barrier polymer matrix that enables both the storage of a high density of hydrogen (up to 6 wt% of Mg, 4 wt% for the composite) and rapid kinetics (loading in <30 min at 200 °C). Moreover, nanostructuring of the Mg provides rapid storage kinetics without using expensive heavy-metal catalysts.
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Fluorographene: a wide bandgap semiconductor with ultraviolet luminescence.
ACS Nano
PUBLISHED: 01-04-2011
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The manipulation of the bandgap of graphene by various means has stirred great interest for potential applications. Here we show that treatment of graphene with xenon difluoride produces a partially fluorinated graphene (fluorographene) with covalent C-F bonding and local sp(3)-carbon hybridization. The material was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, electron energy loss spectroscopy, photoluminescence spectroscopy, and near edge X-ray absorption spectroscopy. These results confirm the structural features of the fluorographane with a bandgap of 3.8 eV, close to that calculated for fluorinated single layer graphene, (CF)(n). The material luminesces broadly in the UV and visible light regions, and has optical properties resembling diamond, with both excitonic and direct optical absorption and emission features. These results suggest the use of fluorographane as a new, readily prepared material for electronic, optoelectronic applications, and energy harvesting applications.
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Porous structured SnSb/C nanocomposites for Li-ion battery anodes.
Chem. Commun. (Camb.)
PUBLISHED: 12-23-2010
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Here, we report a simple, cheap, and rapid synthesis method combined with physical and chemical routes for porous structured metal-based carbon nanocomposites, which can be applicable to anode materials for high performance Li-ion batteries.
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Cyclic nucleotide phosphodiesterase 1 regulates lysosome-dependent type I collagen protein degradation in vascular smooth muscle cells.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 12-09-2010
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The phenotypic modulation of vascular smooth muscle cells (VSMCs) to a synthetic phenotype is vital during pathological vascular remodeling and the development of various vascular diseases. An increase in type I collagen (collagen I) has been implicated in synthetic VSMCs, and cyclic nucleotide signaling is critical in collagen I regulation. Herein, we investigate the role and underlying mechanism of cyclic nucleotide phosphodiesterase 1 (PDE1) in regulating collagen I in synthetic VSMCs.
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Enhanced clopidogrel responsiveness in smokers: smokers paradox is dependent on cytochrome P450 CYP1A2 status.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 12-09-2010
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Observational studies have reported enhanced response to clopidogrel in smokers (the smokers paradox). We examined whether genetic variations in the cytochrome and drug transporter system are associated with the effect of smoking on clopidogrel response.
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Clinical predictors of high posttreatment platelet reactivity to clopidogrel in Koreans.
Cardiovasc Ther
PUBLISHED: 12-06-2010
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High posttreatment platelet reactivity to clopidogrel (HPPR) is associated with major adverse cardiac events. However, the clinical predictors of HPPR in Asians have not been studied previously.
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Ca2+/calmodulin-stimulated PDE1 regulates the beta-catenin/TCF signaling through PP2A B56 gamma subunit in proliferating vascular smooth muscle cells.
FEBS J.
PUBLISHED: 11-16-2010
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The phenotypic change of vascular smooth muscle cells (VSMCs), from a contractile phenotype to a synthetic phenotype, is crucial for pathogenic vascular remodeling in vascular diseases such as atherosclerosis and restenosis. Ca(2+)/calmodulin-stimulated phosphodiesterase 1 (PDE1) isozymes, including PDE1A and PDE1C, play integral roles in regulating the proliferation of synthetic VSMCs. However, the underlying molecular mechanism(s) remain unknown. In this study, we explore the role and mechanism of PDE1 isoforms in regulating ?-catenin/T-cell factor (TCF) signaling in VSMCs, a pathway important for vascular remodeling through promoting VSMC growth and survival. We found that inhibition of PDE1 activity markedly attenuated ?-catenin/TCF signaling by downregulating ?-catenin protein. The effect of PDE1 inhibition on ?-catenin protein reduction is exerted via promoting glycogen synthase kinase 3 (GSK3)? activation, ?-catenin phosphorylation and subsequent ?-catenin protein degradation. Moreover, PDE1 inhibition specifically upregulated phosphatase protein phosphatase 2A (PP2A) B56? subunit gene expression, which is responsible for the effects of PDE1 inhibition on GSK3? and ?-catenin/TCF signaling. Furthermore, the effect of PDE1 inhibition on ?-catenin was specifically mediated by PDE1A but not PDE1C isozyme. Interestingly, in synthetic VSMCs, PP2A B56?, phospho-GSK3? and phospho-?-catenin were all found in the nucleus, suggesting that PDE1A regulates nuclear ?-catenin protein stability through the nuclear PP2A-GSK3?-?-catenin signaling axis. Taken together, these findings provide direct evidence for the first time that PP2A B56? is a critical mediator for PDE1A in the regulation of ?-catenin signaling in proliferating VSMCs.
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Catalytic upgrading of oil fractions separated from food waste leachate.
Bioresour. Technol.
PUBLISHED: 09-06-2010
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In this work, catalytic cracking of biomass waste oil fractions separated from food waste leachate was performed using microporous catalysts, such as HY, HZSM-5 and mesoporous Al-MCM-48. The experiments were carried out using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) to allow the direct analysis of the pyrolytic products. Most acidic components, especially oleic acid, contained in the food waste oil fractions were converted to valuable products, such as oxygenates, hydrocarbons and aromatics. High yields of hydrocarbons within the gasoline-range were obtained when microporous catalysts were used; whereas, the use of Al-MCM-48, which exhibits relatively weak acidity, resulted in high yields of oxygenated and diesel-range hydrocarbons. The HZSM-5 catalyst produced a higher amount of valuable mono aromatics due to its strong acidity and shape selectivity. Especially, the addition of gallium (Ga) to HZSM-5 significantly increased the aromatics content.
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The interaction of Li+ with single-layer and few-layer graphene.
Nano Lett.
PUBLISHED: 08-04-2010
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The interaction of Li(+) with single and few layer graphene is reported. In situ Raman spectra were collected during the electrochemical lithiation of the single- and few-layer graphene. While the interaction of lithium with few layer graphene seems to resemble that of graphite, single layer graphene behaves very differently. The amount of lithium absorbed on single layer graphene seems to be greatly reduced due to repulsion forces between Li(+) at both sides of the graphene layer.
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The characteristics of bio-oil produced from the pyrolysis of three marine macroalgae.
Bioresour. Technol.
PUBLISHED: 06-30-2010
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The pyrolysis of two brown macroalgae (Undaria pinnatifida and Laminaria japonica) and one red macroalgae (Porphyra tenera) was investigated for the production of bio-oil within the temperature range of 300-600°C. Macroalgae differ from lignocellulosic land biomass in their constitutional compounds and high N, S and ash contents. The maximum production of bio-oil was achieved at 500°C, with yields between 37.5 and 47.4 wt.%. The main compounds in bio-oils vary between macroalgae and are greatly different from those of land biomass, especially in the presence of many nitrogen-containing compounds. Of the gaseous products, CO(2) was dominant, while C(1)-C(4) hydrocarbons gradually increasing at 400°C and above. The pretreatment of macroalgae by acid washing effectively reduced the ash content. The pyrolysis of macroalgae offers a new opportunity for feedstock production; however, the utilization of bio-oil as a fuel product needs further assessment.
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Incidence of subclinical coronary atherosclerosis in patients with suspected embolic stroke using cardiac computed tomography.
Int J Cardiovasc Imaging
PUBLISHED: 05-17-2010
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The purpose of this study was to investigate the incidence of subclinical coronary artery disease (CAD) in patients with suspected acute embolic stroke or transient ischemic attack (TIA) using 64-row multi-slice computed tomography (MSCT) and to examine its association with conventional risk stratification. We consecutively enrolled 175 patients (66 ± 13 years, 50% men) suspected to have had embolic stroke/TIA clinically or radiologically, and underwent 64-row MSCT to evaluate for a possible cardiac source of embolism. Both coronary artery calcium scoring (CACS) and coronary CT angiography (CCTA) were concurrently performed based on standard scanning protocols. Patients with a history of angina or documented CAD, and those with significant carotid stenosis were excluded. Atherosclerotic plaques were indentified in 105 (60%) individuals; 37 (21%) had occult CAD of ?50% diameter stenosis on CCTA. Subjects with and without ?50% occult CAD on CCTA had similar prevalence of cardiovascular risk factors. Thirty out of 175 (17%) individuals with ?50% occult CAD would have missed further cardiac testing based on the American Heart association and the American Stroke Association guideline. However, these numbers would be reduced to 2% (4/175) using CACS. In logistic regression analysis, only CACS independently predicted the presence ?50% occult CAD evidenced by CCTA. Subclinical CAD, including ?50% stenotic disease, is highly prevalent in patients who had suffered a suspected embolic stroke. The current guideline for further cardiac testing may have limited value to identify patients with ?50% CAD in this patient population, which can be improved by adopting CACS.
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Vinpocetine inhibits NF-kappaB-dependent inflammation via an IKK-dependent but PDE-independent mechanism.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 05-06-2010
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Inflammation is a hallmark of many diseases, such as atherosclerosis, chronic obstructive pulmonary disease, arthritis, infectious diseases, and cancer. Although steroids and cyclooxygenase inhibitors are effective antiinflammatory therapeutical agents, they may cause serious side effects. Therefore, developing unique antiinflammatory agents without significant adverse effects is urgently needed. Vinpocetine, a derivative of the alkaloid vincamine, has long been used for cerebrovascular disorders and cognitive impairment. Its role in inhibiting inflammation, however, remains unexplored. Here, we show that vinpocetine acts as an antiinflammatory agent in vitro and in vivo. In particular, vinpocetine inhibits TNF-alpha-induced NF-kappaB activation and the subsequent induction of proinflammatory mediators in multiple cell types, including vascular smooth muscle cells, endothelial cells, macrophages, and epithelial cells. We also show that vinpocetine inhibits monocyte adhesion and chemotaxis, which are critical processes during inflammation. Moreover, vinpocetine potently inhibits TNF-alpha- or LPS-induced up-regulation of proinflammatory mediators, including TNF-alpha, IL-1beta, and macrophage inflammatory protein-2, and decreases interstitial infiltration of polymorphonuclear leukocytes in a mouse model of TNF-alpha- or LPS-induced lung inflammation. Interestingly, vinpocetine inhibits NF-kappaB-dependent inflammatory responses by directly targeting IKK, independent of its well-known inhibitory effects on phosphodiesterase and Ca(2+) regulation. These studies thus identify vinpocetine as a unique antiinflammatory agent that may be repositioned for the treatment of many inflammatory diseases.
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Catalytic removal of sulfur dioxide from dibenzothiophene sulfone over Mg-Al mixed oxides supported on mesoporous silica.
J Nanosci Nanotechnol
PUBLISHED: 04-03-2010
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Dibenzothiophene sulfone (DBTS), one of the products of the oxidative desulfurization of heavy oil, can be removed through extraction as well as by an adsorption process. It is necessary to utilize DBTS in conjunction with catalytic cracking. An object of the present study is to provide an Mg-Al-mesoporous silica catalyst for the removal of sulfur dioxide from DBTS. The characteristics of the Mg-Al-mesoporous silica catalyst were investigated through N2 adsorption, XRD, ICP, and XRF. An Mg-Al-mesoporous silica catalyst formulated in a direct incorporation method showed higher catalytic performance compared to pure MgO during the catalytic removal of sulfur dioxide from DBTS. The higher dispersion of Mg as well as the large surface area of the Mg-Al-mesoporous silica catalyst strongly influenced the catalyst basicity in DBTS cracking.
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Catalytic conversion of 1,2-dichlorobenzene over mesoporous materials from zeolite.
J Nanosci Nanotechnol
PUBLISHED: 04-03-2010
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In this study, 1,2-dichlorobenzene (DCB), an important precursor of PCDDs and PCDFs, was chosen as a suitable model compound for the catalyzed deep oxidation of dioxin. The recently developed mesoporous materials from zeolites (MMZ) were used for the first time as a support for an oxidation catalyst. The catalytic oxidation of 1,2-dichlorobenzene over Pt/MMZ was carried out, and the catalytic activity was compared with that of Pt/gamma-Al2O3, Pt/Al-MCM-41 and Pt/Beta catalysts. Pt/MMZ showed the highest catalytic activity among the catalysts tested. Interestingly, the catalytic activity of Pt/MMZ was maintained (> 40%) at low temperatures (250 degrees C) at which the other catalysts showed extremely low activity (< 5%). The high catalytic activity of Pt/MMZ was attributed to both the sufficient acidity and mesoporosity of the MMZ support.
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Application of hierarchical MFI zeolite for the catalytic pyrolysis of Japanese larch.
J Nanosci Nanotechnol
PUBLISHED: 04-01-2010
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The catalytic pyrolysis of Japanese larch was carried out over a hierarchical MFI zeolite (Meso MFI C16). The zeolite was synthesized using an amphiphilic organosilane as a mesopore-directing agent, and its catalytic activity was compared with that of the conventional HZSM-5 and the mesoporous material from HZSM-5 (MMZ(ZSM-5)). The effect of the hierarchical MFI zeolite on the product distribution and chemical composition of the bio-oil was also examined. The hierarchical MFI zeolite exhibited the highest activity in deoxygenation and aromatization during the catalytic pyrolysis of Japanese larch. In particular, it showed high selectivity for valuable aromatics, such as benzene, toluene, and xylenes (BTX), even though it decreased the organic fraction of bio-oil. Its higher mesoporosity resulted, however, in an increase in the coke amount and in undesirable products, such as polycyclic aromatic hydrocarbons (PAHs).
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Synthesis of functionalized mesoporous material with various organo-silanes.
J Nanosci Nanotechnol
PUBLISHED: 04-01-2010
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Two kinds of ordered mesoporous silicas, SBA-15 and MSU-H, have been synthesized and functionalized by direct and post synthesis method to widen their various application possibilities. In this study, phenyltrimethoxysilane (PTMS), methacryloxy-methyltrimethoxysilane (MAMTMS), 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECETMS), and N(beta-aminoethyl)-gamma-aminopropylmethyldimethoxysilane (AEAPMDMS) were used as a silane precursor for the functionalization. The post synthesis was more effective method to sustain ordered pore structure than the direct synthesis method under our experimental conditions. The surface area and pore size of mesoporous silica SBA-15 and MSU-H decreased through the functionalization process. FT-IR and XPS results confirmed the functionalized silane existence in the SBA-15/MAMTMS. These functional groups (vinyl, epoxide, and amine group) could be useful for various applications such as a linker of functional organic materials or active metal for heterogeneous catalysts. As a practical instance, rhodium immobilized on the aminated SBA-15 was investigated as a 1-octene hydroformylation.
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Influence of nanopores of MCM-41 and SBA-15 confining (n-BuCp)2ZrCl2 on copolymerization of ethylene-alpha-olefin.
J Nanosci Nanotechnol
PUBLISHED: 04-01-2010
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The effect of nanopore in mesoporous materials confining (n-BuCp),ZrCl2 and methylaluminoxane (MAO) on ethylene-1-hexene and ethylene-1-octene copolymerization was investigated on the basis of the copolymerization results, and the analysis of the supported catalyst and the copolymers. SBA-15 and MCM-41 together with amorphous silica were employed as supports, which are capable of confining (n-BuCp)2ZrCl2 and MAO in the nanopore. The copolymerization activities of MCM-41-supported (n-BuCp)2ZrCl2 were higher than those of SBA-15 and SiO2 although that its Zr content was quite lower than those of SBA-15 and SiO2. SBA-15 and MCM-41 showed a remarkable decrease in BET surface area after confining MAO and (n-BuCp)2ZrCl2 compared to SiO2, explaining an even adsorption of MAO and (n-BuCp)2ZrCl2 complexes on the nanopore surface. Temperature rising elution fractionation (TREF) results showed bimodal curves of MCM-41-supported (n-BuCp)2ZrCl2 at the C6/C2 and C8/C2 molar ratios of 0.6 and 0.5, respectively, which was attributed to the differences in ethylene and alpha-olefin concentrations along with the cylindrical nanopore of MCM-41 due to the narrow nanospace.
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Exposure assessment of carbon nanotube manufacturing workplaces.
Inhal Toxicol
PUBLISHED: 02-04-2010
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Seven CNT (carbon nanotube) handling workplaces were investigated for exposure assessment. Personal sampling, area sampling, and real-time monitoring using an SMPS (scanning mobility particle sizer), dust monitor, and aethalometer were performed to characterize the mass exposure, particle size distribution, and particle number exposure. No workplace was found to exceed the current ACGIH (American Conference of Governmental Industrial Hygienists) TLVs (threshold limit values) and OELs (occupational exposure levels) set by the Korean Ministry of Labor for carbon black (3.5 mg/m(3)), PNOS (particles not otherwise specified; 3 mg/m(3)), and asbestos (0.1 fiber/cc). Nanoparticles and fine particles were most frequently released after opening the CVD (chemical vapor deposition) cover, followed by catalyst preparation. Other work processes that prompted nanoparticle release included spraying, CNT preparation, ultrasonic dispersion, wafer heating, and opening the water bath cover. All these operation processes could be effectively controlled with the implementation of exposure mitigation, such as engineering control, except at one workplace where only natural ventilation was used.
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