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ABSTRACT: (001)-oriented monoclinic nanorod and microplate WO3 films are fabricated on commercial FTO-coated glass substrates by a rubbing seed layer and a spin-coating seed layer assisted by hydrothermal reactions. The nanorod film obtained by the rubbing seed layer assisted by hydrothermal reactions is more regular and perpendicular to the substrate.
Nanoscale 05/2013; · 5.91 Impact Factor
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ABSTRACT: Herein, we demonstrate a facile approach to manganese-doped highly ordered mesoporous silicate with oxidation-suppression function. As biocompatible supports of guest ions, the ordered mesoporous silicate was synthesized by evaporation-induced self-assembly. The phase-transition from disordered to lamellar structures in the highly ordered mesoporous structure of these porosity-tuned materials was controlled by adjusting the concentration of a lab-made polystyrene-b-polyethylene oxide copolymer. Manganese was successfully incorporated as a guest in the hexagonally packed mesoporous silicate by using an ultrasound-assisted technique. The incorporation of manganese ions into the pores of a mesoporous silicate support could be induced for host-guest functional applications. Manganese-doped mesoporous silicate structures have been examined for their use as antioxidizing agents by electron spin resonance (ESR) measurements and radical-scavenging tests. The manganese atoms in the mesoporous structures could act in a free-radical-scavenging capacity, much like manganese nanoparticles. The high efficiency of their oxidation-suppression function is extended for application to catalytic products.
Chemistry 11/2012; · 5.93 Impact Factor
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ABSTRACT: Cu and Cu2O films can be prepared on indium-doped tin oxide glass substrates by simple electrodeposition in a solution containing 0.1 M Cu(NO3)2 and 3 M lactic acid at different pH values. At low pH (pH = 1.2), the uniform Cu films were obtained; when pH ≥ 7, the pure Cu2O films can be deposited. Especially, at pH = 11, the deposited Cu2O films exhibited cubic surface morphology exposing mainly {100} plane; in contrast, the films consisting of semi-spherical particles were obtained when the solution was being stirred for 2 weeks prior to use. The possible growth process and mechanism were comparatively discussed.
Thin Solid Films 10/2012; 524:50–56. · 1.89 Impact Factor
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ABSTRACT: We demonstrate a facile wet chemical approach for fabricating spherical metal/metal-oxide core@mesoporous silica shell hybrid nanoparticles with different core and shell thicknesses. Vertically aligned mesoporous silica (mSiO(2) ) shells were fabricated over the pre-synthesized spherical SiO(2) nanoparticles through a three-step strategy: 1) synthesis of core materials, 2) covering the core with an organic-inorganic composite layer, and 3) removing the organic template through calcinations in air. The mechanisms of hybrid structure formation are proposed. The multifunctional nature of the hybrid structures could be induced by incorporating guest ions/molecules, such as Ag, Mn, and TiO(2) , into the pores of an mSiO(2) shell. Mn and TiO(2) cluster- incorporated composite structures have been tested to be antioxidizing agents and effective photocatalysts through electron spin resonance, radical scavenging tests, and the photocatalytic degradation of rhodamine B. The possibility of incorporating several hetero-element guest clusters in these mesoporous composite particles makes them highly attractive for multifunctional applications.
Chemistry 08/2012; 18(39):12314-21. · 5.93 Impact Factor
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ABSTRACT: Mesoporous titania with crystalline pore walls and controlled pore sizes was fabricated through triblock copolymer (pluronic series) templated sol-gel process by changing the copolymer concentration and by adjusting their calcination temperature. Compared with mesoprous silicate, the synthetic condition of mesoporous titania would be sensitive to calcination temperature. Their pore arrangement and pore size depend strongly on the concentration of copolymer used as a template. Their arrangement of pores and specific surface area increases with the increase of calcination temperature up to critical limit, 320 degrees C. Beyond the critical temperature, the orderness of pores and specific surface area decreases due to the collapse of the pore walls. The specific surface area, pore size and pore orderness can be controlled by optimizing calcination temperature as well as polymer concentration. We demonstrate the mechanism of pore formation and their collapse in the sol-gel synthesis of mesoporous titania.
Journal of Nanoscience and Nanotechnology 07/2012; 12(7):5638-43. · 1.56 Impact Factor
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ABSTRACT: AbstractThe photoinduced electron transfer from chlorophyll a through the interface of positively charged dioctadecyltrimethylammonium
chloride (DODAC), neutral dipalmitoylphosphatidylcholine (DPPC) and negatively charged dihexadecylphosphate (DHP) headgroup
of the lipid bilayers was studied. The photoinduced radicals were identified by electron spin resonance (ESR) and radical
yields of chlorophyll a were determined by double integration of the ESR spectra. The formation of vesicles was identified
indirectly by measuring change of the λ
max value of optical absorption spectrophotometer from diethyl ether solution to vesicle solutions, and observed directly with
scanning and transmission electron microscopic images. The interaction distance between chlorophyll a and interface water
(D2O) determined by deuterium modulation depth with electron spin echo modulation (ESEM) showed a decreasing order DODAC>DPPC>DHP.
The interface charge of each vesicle was determined with zeta potential measurement. The interface charge of the lipid bilayers
affected the radical yields of chlorophyll a more critically than the interaction distance between chlorophyll a and interface
water.
Graphical Abstract
Applied Magnetic Resonance 04/2012; 40(4):567-580. · 0.75 Impact Factor
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ABSTRACT: Vertically and laterally oriented cobalt dendrite films with or without dendritic structures were synthesized by cathodic electrodeposition under different experimental conditions. The morphology of Co deposits was varied significantly depending on deposition conditions such as applied potential, precursor concentration and especially pH value. Co dendritic crystal growth along the [110] direction is preferred. The possible growth mechanism is discussed by supposing differing concentration areas. Results of glucose electrooxidation demonstrate that vertical Co dendrite films are promising materials as carbohydrate sensors with high sensitivity and fast response. In addition, magnetic measurements on cobalt samples under parallel and perpendicular direction of the applied magnetic field show that they exhibit a ferromagnetic behavior with different saturation magnetizations and coercivities.
Journal of Materials Chemistry 04/2012; 22:12296-12304. · 5.97 Impact Factor
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ABSTRACT: CuO/CuWO4 p–n junction thin films were prepared by using electrodeposited Cu films with an acidic cupric lactate system (pH ≤ 5). The photoelectrochemical properties of CuO and CuWO4–CuO films were studied by photoresponse and current–potential characteristics under 1 sun illumination. The photocurrent of CuO films prepared by annealing Cu films electrodeposited at pH 5 is about 0.6 mA/cm2 at −0.6 V vs Ag/AgCl. Both p-type and n-type behaviors occurred on CuO–CuWO4 film in the potential range from 0.8 V to −0.6 V vs Ag/AgCl. The photoelectrochemical photocurrent switching (PEPS) effect was observed in the case of p-CuO/n-CuWO4 heterojunction and the photocurrent switching potential is +0.33 V vs Ag/AgCl.
Electrochimica Acta 03/2012; 69:340–344. · 3.83 Impact Factor
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ABSTRACT: Copper nanoparticles are prepared in aqueous solution by reducing copper ions with hydrazine hydrate in the presence of cetyl trimethylammonium bromide (CTAB) and polyvinylpyrrolydone (PVP) as stabilizers. With only CTAB was used as stabilizer, copper nanoparticles are aggregated and partially oxidized to Cu(2)O. When both PVP and CTAB were used, dispersed copper nanoparticles with 56 nm diameter were obtained. Copper nanoparticles are simply mixed with poly (3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) in aqueous solution to form conducting composite. The effect of copper weight percent and surfactants on the conductivity and stability of the composite has been investigated.
Journal of Colloid and Interface Science 01/2012; 365(1):103-9. · 3.07 Impact Factor
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ABSTRACT: Unique ring-shaped single-crystal like mesoporous ZnO:Mn(2+) nanostructures have been fabricated through ultrasound assisted hydrolysis of zinc and manganese precursors. Incorporation of manganese into the nanostructures induced soft ferromagnetic behaviour. The nanostructures are of high optoelectronic quality with little structural and electronic defects. A mechanism of formation of the novel porous structures is proposed. The presence of manganese in Mn(2+) state with strong hyperfine splitting (89 G) promises the application of these porous nanostructures in designing nanometric spintronic devices.
Nanoscale 12/2011; 3(12):4962-5. · 5.91 Impact Factor
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ABSTRACT: We report a two-photon fluorescent probe (ACu1) that can be excited by 750 nm femto-second pulses, shows high photostability and negligible toxicity, and can visualize Cu(+) distribution in live cells and tissues by two-photon microscopy.
Chemical Communications 07/2011; 47(25):7146-8. · 6.17 Impact Factor
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Seok Min Hong,
Beom-Gyu Kim,
Boung Chul Lee,
Su-Kyoung Park,
Sung Kwang Hong,
Hyo-Jeong Lee,
Hyung-Jong Kim,
Jun Ho Lee, Chang Woo Kim,
Il-Seok Park,
Yong Bok Kim
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ABSTRACT: Dizziness is a common problem in older people, with a reported prevalence of 13-38%. A large percentage of patients with dizziness develop secondary psychiatric disorders over the course of their disease. In particular, clinical depression and anxiety are significant health problems for older adults. We investigated the relationship between dizziness and psychological distress (depression and anxiety) in elderly patients with dizziness, and the relationship with psychological symptoms after managing the dizziness. This study enrolled 126 patients with dizziness, who were 65 years or older. Dizziness and the psychological symptoms of all patients were measured using the Korean Version of the Vestibular Disorders Activities of Daily Living Scale (K-VADL), the Beck Depression Inventory (BDI), and the Spielberger State-Trait Anxiety Inventory (STAI) before and after management. We found a significant decrease in the BDI and STAI state scores after treatment with a reduction in the K-VADL score. For the STAI, the decrease in the score was relatively small after management. Nevertheless, there were significant correlations between the K-VADL score and both the BDI and STAI scores before and after management. Therefore, in the management of elderly patients with dizziness, a psychiatric approach should be considered and psychological support may be needed after managing the dizziness.
Archives of Oto-Rhino-Laryngology 03/2011; 269(1):39-43. · 1.29 Impact Factor
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ABSTRACT: Highly monodispersed electrophoretic particles of size ranging from 550 to 160 nm could be prepared through dispersion-polymerization of methyl methacrylate and ethylene glycol dimethacrylate in presence of pyrazoline nanoparticles in a methanol-water mixture. The size of the fabricated electrophoretic particles could be controlled by adjusting the concentration of surfactant. Stearic acid, used as surfactant during the polymerization process also acts as charge controlling additive to control the electrophoric mobility of the particles. Maximum electrophoric mobility (-7.513×10(-5) cm(2)/Vs) was obtained for the 400 nm electrophoretic particles prepared with 1.5 wt.% of stearic acid surfactant. The electrophoric display cells prepared with our electrophoretic particles reveal good current voltage characteristics and color change under applied bias voltage.
Journal of Colloid and Interface Science 01/2011; 357(1):31-5. · 3.07 Impact Factor
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ABSTRACT: A new magnetic fluid was prepared by colloidal dispersion of paramagnetic Fe3O4 nanoparticles coated with monomolecular adsorbed monolayer films of long-chain trimethoxyhexadecylsilane (THS) in a nonpolar hydrocarbon oil. The magnetic Fe3O4 nanoparticles were characterized by using TEM, XRD, FT-IR, and VSM. The silanization of the magnetic particle surface was conducted in methanol. The silanized films on the magnetic particles are characterized with FT-IR spectroscopy. The optical absorbance of the magnetic particle versus concentration of the solution was measured with a UV−vis spectrophotometer and shows a linear increase of absorbance. Langmuir behavior of the THS-coated Fe3O4 nanoparticles at the air/water interface was characterized with pressure−area isotherms and Brewster Angle Microscopy. The collapse pressure of the Langmuir monomolecular films was determined as 62 mN/m. The stability of magnetic fluids of the THS-coated Fe3O4 nanoparticles are comparatively studied with the conventional oleic acid-coated magnetic fluid of Fe3O4 nanoparticle at the acidic condition of pH 4. The durability of the magnetic fluid of THS-coated Fe3O4 nanoparticles is shown as it lasted longer than 60 days.
05/2010;
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ABSTRACT: The formation and crystal structure of sodium titanate nanobelts synthesized with various Ti precursors are reported. P25 (TiO2) powder, Ti(OBu)4, and TiCl4 were used as Ti precursors. Their nanobelts were synthesized via hydrothermal process at 180 °C for 24 h in concentrated aqueous NaOH solution. The product obtained with P25 (TiO2) was identified to be Na2Ti4O9·1.5H2O. The products obtained with Ti(O(CH2)3CH3)4 and TiCl4 were confirmed to be the crystal structure of Na2Ti2O4(OH)2. This means that the formation mechanism of the crystal structure in the synthetic process depends on their Ti source. Their morphology was compared with XRD, TEM, FE-SEM, Raman, and TGA. On the basis of their morphology results, the crystalline structure model and the formation mechanism of sodium titanate nanobelts are proposed.
04/2010;
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ABSTRACT: A nevus which is a benign melanocytic neoplasm rarely occurs within the external auditory canal (EAC). A dysplastic nevus presents atypical features both clinically and histologically, and is important as a potential precursor for melanoma. We present a case of a 33-year-old female patient with a dysplastic nevus in her EAC. Physical examination revealed a protruding mass arising from the posterior wall of the left cartilaginous EAC. The mass showed clinically characteristic findings of a melanocytic nevus. The patient underwent excisional biopsy via a transcanal approach under local anesthesia. Histopathological examination revealed an intradermal nevus with atypical melanocytes without pleomorphism. There was no evidence of recurrence two years after surgical excision.
Yonsei medical journal 12/2009; 50(6):845-7. · 0.77 Impact Factor
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Molecular Crystals and Liquid Crystals. 12/2009; 515(1):251-254.
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ABSTRACT: The temperature effect on the magnetic property of gamma-ray irradiated Nd-Fe-B and Sr-Ferrite magnets has been investigated. When the permanent magnets are exposed to gamma-ray, it's magnetic and other related properties are declined with degree of dose. The decreased magnetic property by gamma-ray irradiation at low temperature is similar with the result of magnet at high temperature. The temperature effect on the gamma-ray irradiation at exposed moment is also regarded as one of the important parameters for the reduced magnetic properties. The gamma-irradiation at low temperature was carried out at 195 K, and the changed properties of two kinds of magnets before and after gamma-irradiation were comparatively studied. The increased demagnetization of the magnets were studied by Hall probe. And changed Curie temperature and micro-crystal structure of each permanent magnet by gamma-ray irradiation has been also studied. Moreover the strong and broad single line shape of ESR signal in the resonance magnetic field is attributed to unpaired electron of Fe2+ in the sample by the effect of gamma-ray irradiation.
Journal of Nanoscience and Nanotechnology 12/2009; 9(12):6953-6. · 1.56 Impact Factor
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ABSTRACT: In this work, the metal plated film was prepared by electroless plating techniques. The film was prepared for the fabrication of EMI shielding. Polyimide film was treated by base solution for etching and then activated by silver. The modified polyimide film was immersed into the electroless copper plating solution which has different molar ratios of nickel in the solution. The thickness and surface morphology of copper layer on the polyimide films were characterized with scanning electron microscopy (SEM). Furthermore, EMI shielding ability of the film was calculated by measuring reflectivity of EM wave on the film surface using the equation of Schelkunoff theory.
Journal of Nanoscience and Nanotechnology 12/2009; 9(12):7065-70. · 1.56 Impact Factor
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ABSTRACT: Sm-Co magnetic nanoparticles were successfully synthesized at high temperature above 680 degrees C in solution phase. The chemical composition was determined by EDX and it was found that the composition of as-synthesized Sm-Co magnetic nanoparticles showed less Sm content compared with the composition of starting materials. From TEM and FE-SEM measurements, the morphology of as-synthesized and heat-treated Sm-Co a magnetic nanoparticle was confirmed as hexagon and apatite crystal structure. Curie temperature was observed at around 680 degrees C correspond to SmCo5 phase. The magnetic property was measured by VSM and shows the ferromagnetic characteristics.
Journal of Nanoscience and Nanotechnology 12/2009; 9(12):7071-5. · 1.56 Impact Factor
