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Search Results: 1 - 10 of 149837 matches for " H. Ogino "
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Fabrication of Microspheres Based on Poly(4-butyltriphenylamine) Blends with Poly(methyl methacrylate) and Block Copolymer by Solvent Evaporation Method  [PDF]
Hossein Taherzadeh, Kenji Ogino
Open Journal of Organic Polymer Materials (OJOPM) , 2015, DOI: 10.4236/ojopm.2015.52004
Abstract: Micron-sized polymer particles from single poly(4-butyltriphenylamine) (PBTPA) homopolymer, binary polymer blend [PBTPA/poly(methyl methacrylate) (PMMA)], and ternary polymer blend (PBTPA/PBTPA-b-PMMA/PMMA) via a solvent evaporation method, and the surface morphologies and inside structure of resulting particles were investigated. Spherical homopolymer particles with smooth surface were resulted from PBTPA with low molecular weight. In the case of binary blends (PBTPA/PMMA = 1/1), Janus (low molecular weight) and dumbbell (high molecular weight) type morphologies were observed. The particles based on ternary blends containing PBTPA-b-PMMA showed core-shell type morphologies (PMMA; core, PBTPA; shell). Degree of engulfment of PMMArich domain increased with the content of the block copolymer. The decrease of domain size was not observed although the block copolymer had a suitable structure as a compatibilizer for the blend. It was also found that the initial concentration of polymer solution had an effect on the final morphology.
Additive intraocular pressure-lowering effect of dorzolamide 1%/timolol 0.5% fixed combination on prostaglandin monotherapy in patients with normal tension glaucoma
Mizoguchi T, Ozaki M, Wakiyama H, Ogino N
Clinical Ophthalmology , 2011, DOI: http://dx.doi.org/10.2147/OPTH.S24058
Abstract: dditive intraocular pressure-lowering effect of dorzolamide 1%/timolol 0.5% fixed combination on prostaglandin monotherapy in patients with normal tension glaucoma Original Research (2879) Total Article Views Authors: Mizoguchi T, Ozaki M, Wakiyama H, Ogino N Published Date October 2011 Volume 2011:5 Pages 1515 - 1520 DOI: http://dx.doi.org/10.2147/OPTH.S24058 Takanori Mizoguchi1, Mineo Ozaki2, Harumi Wakiyama1,3, Nobuchika Ogino1 1Mizoguchi Eye Clinic, Sasebo, 2Ozaki Eye Clinic and Dept of Opthalmology, Faculty of Medicine, University of Miyazaki, Miyazaki, 3The Japanese Red Cross Nagasaki Genbaku Hospital, Nagasaki, Japan Purpose: To evaluate the intraocular pressure (IOP)-lowering effect of adding dorzolamide 1.0%/timolol 0.5% fixed combination (DTFC) to prostaglandin analogs (PGAs) as monotherapy in patients with normal tension glaucoma. Methods: A prospective, clinical, case-controlled study of patients with normal tension glaucoma. Patients had been on a once-daily night dose of prostaglandins (PGs) as monotherapy and then received DTFC added to PGs for 8 weeks. The IOP was measured at 9 am, week 0 (baseline), week 4, and week 8. Results: The baseline IOP of 40 patients who had previously been treated by prostaglandin monotherapy was 15.6 ± 2.0 mmHg at baseline. The IOPs at 4 and 8 weeks after adding DTFC to PGs were 13.5 ± 2.1 mmHg and 13.7 ± 2.2 mmHg, respectively. Significant decrease of the IOP was observed at each time point of measurement as compared with the baseline IOP before adding DTFC (P = 0.01). The percent IOP reduction from the baseline IOP at week 4 and week 8 was 13.5% ± 12.3% and 11.7% ± 13.1%, respectively. The percentage of patients who achieved 10% or more IOP reduction from the baseline IOP at week 8 was 62.5%. The baseline IOP was significantly correlated with the percent IOP reduction at week 8 (P = 0.03, r = 0.34). Conclusion: DTFC therapy added to PGAs as glaucoma monotherapy is effective in patients with normal tension glaucoma.
Additive intraocular pressure-lowering effect of dorzolamide 1%/timolol 0.5% fixed combination on prostaglandin monotherapy in patients with normal tension glaucoma
Mizoguchi T,Ozaki M,Wakiyama H,Ogino N
Clinical Ophthalmology , 2011,
Abstract: Takanori Mizoguchi1, Mineo Ozaki2, Harumi Wakiyama1,3, Nobuchika Ogino11Mizoguchi Eye Clinic, Sasebo, 2Ozaki Eye Clinic and Dept of Opthalmology, Faculty of Medicine, University of Miyazaki, Miyazaki, 3The Japanese Red Cross Nagasaki Genbaku Hospital, Nagasaki, JapanPurpose: To evaluate the intraocular pressure (IOP)-lowering effect of adding dorzolamide 1.0%/timolol 0.5% fixed combination (DTFC) to prostaglandin analogs (PGAs) as monotherapy in patients with normal tension glaucoma.Methods: A prospective, clinical, case-controlled study of patients with normal tension glaucoma. Patients had been on a once-daily night dose of prostaglandins (PGs) as monotherapy and then received DTFC added to PGs for 8 weeks. The IOP was measured at 9 am, week 0 (baseline), week 4, and week 8.Results: The baseline IOP of 40 patients who had previously been treated by prostaglandin monotherapy was 15.6 ± 2.0 mmHg at baseline. The IOPs at 4 and 8 weeks after adding DTFC to PGs were 13.5 ± 2.1 mmHg and 13.7 ± 2.2 mmHg, respectively. Significant decrease of the IOP was observed at each time point of measurement as compared with the baseline IOP before adding DTFC (P = 0.01). The percent IOP reduction from the baseline IOP at week 4 and week 8 was 13.5% ± 12.3% and 11.7% ± 13.1%, respectively. The percentage of patients who achieved 10% or more IOP reduction from the baseline IOP at week 8 was 62.5%. The baseline IOP was significantly correlated with the percent IOP reduction at week 8 (P = 0.03, r = 0.34).Conclusion: DTFC therapy added to PGAs as glaucoma monotherapy is effective in patients with normal tension glaucoma.Keywords: IOP-lowering effect, prostaglandin, dorzolamide 1%/timolol 0.5% fixed combination, fixed combination, normal tension glaucoma
Synthesis of Polyfluorene-Polytriarylamine Block Copolymer with Emitting Part at Junction Point for Light Emitting Applications  [PDF]
Mehdi Jahanfar, Kenta Suwa, Kousuke Tsuchiya, Kenji Ogino Ogino
Open Journal of Organic Polymer Materials (OJOPM) , 2013, DOI: 10.4236/ojopm.2013.32008
Abstract: A block copolymer consisting of polyfluorene (PF) and polytriarylamine (PTAA) functionalized with green emitting phenoxazine moiety at the junction point of two blocks was designed and prepared for electroluminescent application. PF homopolymer was synthesized by Suzuki coupling polymerization, and was reacted with brominated phenoxazine. In the presence of the resulting PF functionalized with phenoxazine, C-N coupling polymerization of 4-(4’-bromophenyl)-4’’-butyldiphenylamine was carried out to afford a triblock copolymer, PTAA-phenoxazine-PF-phenoxazine-PTAA (PF-Ph-PTAA). Two types of random copolymers were also synthesized with fluorene and phenoxazine (PF2) by Suzuki coupling polymerization for comparison. All the polymers were soluble in common organic solvents and readily formed thin films by a solution processing. Prepared polymers exhibited similar UV absorption and PL emission in chloroform solutions. In a film state, the existence of phenoxazine unit drastically changed PL spectra. Although the content of phenoxazine unit in PF-Ph-PTAA was relatively high (13 mol%), it showed similar PL spectrum to that of PF2(phenoxazine content, 0.2 mol%) indicating that phenoxazine unit is isolated in single polymer chain nevertheless the high content. EL device based on PF-Ph-PTAA showed green-emission, suggesting that emission sites predominantly located in the vicinity of phenoxazine moiety because of its shallow HOMO level.
Contrasting Pressure Effects in Sr2VFeAsO3 and Sr2ScFePO3
H. Kotegawa,T. Kawazoe,H. Tou,K. Murata,H. Ogino,K. Kishio,J. Shimoyama
Physics , 2009, DOI: 10.1143/JPSJ.78.123707
Abstract: We report the resistivity measurements under pressure of two Fe-based superconductors with a thick perovskite oxide layer, Sr2VFeAsO3 and Sr2ScFePO3. The superconducting transition temperature Tc of Sr2VFeAsO3 markedly increases with increasing pressure. Its onset value, which was Tc{onset}=36.4 K at ambient pressure, increases to Tc{onset}=46.0 K at ~4 GPa, ensuring the potential of the "21113" system as a high-Tc material. However, the superconductivity of Sr2ScFePO3 is strongly suppressed under pressure. The Tc{onset} of ~16 K decreases to ~5 K at ~4 GPa, and the zero-resistance state is almost lost. We discuss the factor that induces this contrasting pressure effect.
NMR Investigation of the iron-based superconductors Ca4(Mg,Ti)3Fe2As2O8-y and Ca5(Sc,Ti)4Fe2As2O11-y
Y. Tomita,H. Kotegawa,Y. Tao,H. Tou,H. Ogino,S. Horii,K. Kishio,J. Shimoyama
Physics , 2012, DOI: 10.1103/PhysRevB.86.134527
Abstract: $^{75}$As and $^{45}$Sc NMR measurements unravel the electronic state for Fe-based superconductors with perovskite-type blocking layers Ca$_4$(Mg,Ti)$_3$Fe$_2$As$_2$O$_{8-y}$ ($T_c^{onset}=47$ K) and Ca$_5$(Sc,Ti)$_4$Fe$_2$As$_2$O$_{11-y}$ ($T_c^{onset}=41$ K). In Ca$_5$(Sc,Ti)$_4$Fe$_2$As$_2$O$_{11-y}$, the nuclear spin relaxation rate $1/T_1$ shows pseudogap behavior below $\sim80$ K, suggesting that the electronic state is similar to that of LaFeAs(O,F) system with moderate electron doping. The presence of the pseudogap behavior gives an interpretation that the hole-like band (so-called $\gamma$ pocket) is located just below the Fermi level from the analogy to LaFeAs(O,F) system and the disappearance of the $\gamma$ pocket yields the suppression of the low-energy spin fluctuations. On the other hand, in Ca$_4$(Mg,Ti)$_3$Fe$_2$As$_2$O$_{8-y}$ satisfying the structural optimal condition for higher $T_c$ among the perovskite systems, the extrinsic contribution, which presumably originates in the Ti moment, is observed in $1/T_1T$; however, the moderate temperature dependence of $1/T_1T$ appears by its suppression under high magnetic field. In both systems, the high $T_c$ of $\sim40$ K is realized in the absence of the strong development of the low-energy spin fluctuations. The present results reveal that the structural optimization does not induce the strong development of the low-energy spin fluctuations. If we consider that superconductivity is mediated by spin fluctuations, the structural optimization is conjectured to provide a benefit to the development of the high-energy spin fluctuations irrespective to the low-energy part.
Towards the Realization of Higher Connectivity in MgB2 Conductors: In-situ or Sintered Ex-situ?
A. Yamamoto,H. Tanaka,J. Shimoyama,H. Ogino,K. Kishio,T. Matsushita
Physics , 2011, DOI: 10.1143/JJAP.51.010105
Abstract: The two most common types of MgB2 conductor fabrication technique - in-situ and ex-situ - show increasing conflicts concerning the connectivity, an effective current-carrying cross-sectional area. An in-situ reaction yields a strong intergrain coupling with a low packing factor, while an ex-situ process using pre-reacted MgB2 yields tightly packed grains, however, their coupling is much weaker. We studied the normal-state resistivity and microstructure of ex-situ MgB2 bulks synthesized with varied heating conditions under ambient pressure. The samples heated at moderately high temperatures of ~900{\deg}C for a long period showed an increased packing factor, a larger intergrain contact area and a significantly decreased resistivity, all of which indicate the solid-state self-sintering of MgB2. Consequently the connectivity of the sintered ex-situ samples exceeded the typical connectivity range 5-15% of the in-situ samples. Our results show self-sintering develops the superior connectivity potential of ex-situ MgB2, though its intergrain coupling is not yet fulfilled, to provide a strong possibility of twice or even much higher connectivity in optimally sintered ex-situ MgB2 than in in-situ MgB2.
Successive transition from superconducting to antiferromagnetic phase in (Ca_6(Al, Ti)_4O_y)Fe_2As_2 studied via ^{75}As and ^{27}Al NMR
T. Nakano,N. Fujiwara,S. Tsutsumi,H. Ogino,K. Kishio,J. Shimoyama
Physics , 2011, DOI: 10.1103/PhysRevB.84.060502
Abstract: An unusual successive phase transition from superconducting (SC) to antiferromagnetic (AF) phases was discovered via ^{75}As and ^{27}Al nuclear magnetic resonance (NMR) in (Fe_2As_2)(Ca_6(Al, Ti)_4O_y) with four (Al, Ti)O layers intercalated between FeAs planes. Although the spatially-uniform AF ordering is clearly visible from ^{27}Al spectra, the ordered moments are very small and the low-frequency fluctuation is much suppressed, contrary to existing pnictides with localized magnetic elements. Furthermore, the temperature (T) dependence of the fluctuation at both nuclei is very similar throughout the entire temperature range. These facts suggest that some hybridization between Ti and Fe orbitals induces a uniform electronic state within FeAs and (Al, Ti)O layers accompanied by the SC and AF transitions. The iron-based pnictide with Ti-doped blocking layers is the first high-T_c compound having metallic blocking layers.
Superconductivity at 17 K in (Fe2P2)(Sr4Sc2O6): a new superconducting layered pnictide oxide with a thick perovskite oxide layer
H. Ogino,Y. Matsumura,Y. Katsura,K. Ushiyama,S. Horii,K. Kishio,J. Shimoyama
Physics , 2009, DOI: 10.1088/0953-2048/22/7/075008
Abstract: A new layered oxypnictide (Fe2P2)(Sr4Sc2O6) have been synthesized by solid-state reaction. This material has an alternating layer stacking structure of anti-fluorite Fe2P2 and perovskite-based Sr4Sc2O6 oxide layers. Space group of the material is P4/nmm and lattice constants a and c are 4.016 A and 15.543 A, respectively. The interlayer Fe-Fe distance corresponding to the c-axis length is the longest ever reported in the iron-based oxypnictide systems. In both magnetization and resistivity measurements, the present compound exhibited superconductivity below 17 K, which is much higher than that of LaFePO and the highest in arsenic-free iron-based oxypnictide systems under ambient pressure.
Transition Temperature and Upper Critical Field in SmFeAsO1-xFx Synthesized at Low Heating Temperatures
S. J. Singh,J. Shimoyama,A. Yamamoto,H. Ogino,K. Kishio
Physics , 2013, DOI: 10.1109/TASC.2013.2239352
Abstract: Low-temperature synthesis is a promising and potentially effective method for improving superconducting properties. We report on the fabrication of polycrystalline samples of SmFeAsO1-xFx with nominal x content varying in a wide range of x = 0-0.35 synthesized at 900 deg C. This synthesis temperature is around 300 deg C lower than the conventional synthesis temperature. The variation in the lattice parameters and transition temperature (Tc) of various F-doped samples indicates that reduction of the unit cell volume (V) seems to be the main reason for the rise of Tc up to 57.8 K. Magnetoresistance measurements showed that the upper critical field slope (dHc2/dT) increased with increasing F concentration up to x = 0.2, where it reached a maximum value of -8 T/K corresponding to a coherence length of 10 angstrom. At still higher F doping levels, dHc2/dT and the low field Jc decreased; above 0.5 T, however, Jc had almost the same value. Compared with previous reports, the present synthesis route with low synthesis temperatures and commonly available FeF2 as the source of F is more effective at introducing F into the SmFeAsO system and thereby resulting in improved superconducting properties for the system. In addition, this new sample preparation method also reduces unnecessary problems such as the evaporation of F and reaction between the crucible and superconductor during the solid-state reaction.
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