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Search Results: 1 - 10 of 2777 matches for " Takaomi Kobayashi "
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Effect of Acidic Catalyst on Properties of Novel Conductive Copolymer Films Made of Pyrrole and Formyl Pyrrole  [PDF]
Yusuke Hoshina, Takaomi Kobayashi
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.43018
Abstract: Effect of acidic catalysis having carboxylic acid group was studied on properties of conductive copolymer films made of pyrrole (Py) and 2-formyl pyrrole (FPy). It was noted that trifluoroacetic acid (TFA) and trichloroacetic acid (TCA) were suitable for the preparation of copolymer films, which showed good properties in its strength and electrical conductivity of the copolymer films. When the concentration of TFA or TCA was increased in the monomer feed, the copolymerization yield became higher and the obtained films showed electrical conductivity in the range of 10–4 - 10–3 S/cm. FT-IR and UV-Vis spectra confirmed the formation of conjugate chemical structure in the copolymer film.
Photoresponsive Block Copolymers Containing Azobenzenes and Other Chromophores
Haifeng Yu,Takaomi Kobayashi
Molecules , 2010, DOI: 10.3390/molecules15010570
Abstract: Photoresponsive block copolymers (PRBCs) containing azobenzenes and other chromophores can be easily prepared by controlled polymerization. Their photoresponsive behaviors are generally based on photoisomerization, photocrosslinking, photoalignment and photoinduced cooperative motions. When the photoactive block forms mesogenic phases upon microphase separation of PRBCs, supramolecular cooperative motion in liquid-crystalline PRBCs enables them to self-organize into hierarchical structures with photoresponsive features. This offers novel opportunities to photocontrol microphase-separated nanostructures of well-defined PRBCs and extends their diverse applications in holograms, nanotemplates, photodeformed devices and microporous films.
Fabrication and Characterization of Pulp/Chitosan Composite Membranes Crosslinked with 3-Methylglutaric Anhydride for Pervaporation of Ethanol/Water Mixture  [PDF]
Truong Thi Cam Trang, Nguyen Thi Nhung, Takaomi Kobayashi
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.32014
Abstract: Chitosan/Cellulose (CTS/CL) composite membranes were prepared by cross-linking reaction with 3-methy- lglutaric anhydride (3MGA). The cross-linked membranes with CTS/CL were obtained at different CTS con- tents in variations from 50 to 100 wt%, and these membranes were applied in the dehydration of ethanol/wa- ter mixtures. Especially, it was observed that in the case of a composite membrane containing chitosan 80% (CTS/CL-80/20) showed a performance with a separation factor of α = 17.1 and a total permeation flux of J = 326 g/(m2h). It was observed that the total permeation flux decreased when the cross-linking increased and the increase in the ethanol content in the feed solution showed an increase in the separation factor. The CTS/ CL-80/20 showed excellent performance with good mechanical strength and dehydration performance in the ethanol/water mixture separation.
Bamboo Fibers Elaborating Cellulose Hydrogel Films for Medical Applications  [PDF]
Karla Lizette Tovar-Carrillo, Motohiro Tagaya, Takaomi Kobayashi
Journal of Materials Science and Chemical Engineering (MSCE) , 2013, DOI: 10.4236/msce.2013.17002

Bamboo fibers were used as source to prepare cellulose hydrogel films for cell cultivation scaffold. The preparation of cellulose solutions was carried out by three different dissolving methods with NaOH-based and NaOH/urea aqueous solutions and DMAc/LiCl solution. Several hydrogel films were elaborated and their properties were compared to evaluate the effect of the dissolving method. It was found that tensile strength of the resultant hydrogel films increased from 21 to 66 N/mm2 when DMAc/LiCl was used instead of the NaOH/urea solution. The same tendency was observed in the obtained elongation values. Moreover, a remarkable difference in fibroblast cell cultivation was observed in higher cell density, when DMAc/LiCl method was used. The obtained results with DMAc/LiCl also were seen to be higher than the results for PS dish used as control. However, low cytocompatibility was observed when NaOH and NaOH/urea methods were used. The obtained results showed that hydrogel films elaborated with cellulose solution prepared with DMAc/LiCl method exhibited good cytocompatibility for the cell cultivation scaffold.

Geopolymers Using Rice Husk Silica and Metakaolin Derivatives; Preparation and Their Characteristics  [PDF]
Francisco J. López, Satoshi Sugita, Motohiro Tagaya, Takaomi Kobayashi
Journal of Materials Science and Chemical Engineering (MSCE) , 2014, DOI: 10.4236/msce.2014.25006

The effect of the amorphous silica derived from biomass rice husk (RH) in the alkaline activating solution on the properties was investigated in geopolymerization process, when metakaolin was used as the aluminum source from metakaolin (MK). With changing a molar ratio of SiO2/Al2O3 = 3.0 and 10, the curing in the preparation of geopolymers was carried out at 85°C, 100°C and 200°C. Viscoelastic properties of the geopolymer pastes including SiO2 and Al2O3 components suggested that the alkaline activation was found in higher RH silica source. The mineralogical and microstructural characteristics of the cured products were evaluated to be amorphous aluminosilicate.

Metakaolin-Based Geopolymers for Targeted Adsorbents to Heavy Metal Ion Separation  [PDF]
Francisco J. López, Satoshi Sugita, Motohiro Tagaya, Takaomi Kobayashi
Journal of Materials Science and Chemical Engineering (MSCE) , 2014, DOI: 10.4236/msce.2014.27002

Geopolymer adsorbents were prepared from silica and metakaolin in different Al and Si components and applied for removal of metal ions, Cs+ and Pb2+, from other heavy metal ions mixture. The geopolymer was optimized at Si/Al = 2 as adsorbent, targeting to Cs+ and Pb2+ separation. The binding behavior was well fitted to Langmuir model, which proved that the metakaolin-based geopolymer had multibinding to adsorb ions. The effective adsorption was also observed independent of NaCl concentration for the Cs+ and Pb2+. This meant that the ion adsorption of geopolymers occurred under non-electrostatic mechanism.

Fabrication and Characterization of CTS/Coconut Composite Membranes Crosslinked with Glutaraldehyde for Elimination of Heavy Metal in Aqueous Solution  [PDF]
Truong Thi Cam Trang, Nguyen Quang Huy, Takaomi Kobayashi
Journal of Agricultural Chemistry and Environment (JACEN) , 2019, DOI: 10.4236/jacen.2019.82006
Abstract: Chitosan/coconut (CTS/coconut) composite membranes were successfully prepared by the cross-linking reaction with glutaraldehyde and they were applied in eliminating heavy metals from aqueous solutions. The cross-linked membranes were obtained at the ratios of 1/1, 1/1.5 and 1/2 and the coconut fiber was chemically treated by NaOCl/NaOH. The best ratio of CTS/coconut fiber is found to be 1/1.5 which has a relatively high stability with the degree of swelling (DS) and solvent content (SC) of membrane to be 13.33% and 69.88%, respectively. The results also indicate that the CTS membranes showed preferential separation of heavy metals for blend CTS/coconut membranes.
Dispersion and Polar Component of Specific Surface Free Energy of NaCl(100), KCl(100), and KBr(100) Single Crystal Surfaces  [PDF]
Takaomi Suzuk, Yuya Yamada
Journal of Crystallization Process and Technology (JCPT) , 2015, DOI: 10.4236/jcpt.2015.53006
Abstract: Contact angle of ethylene glycol and formamide on (100) faces of NaCl, KCl, and KBr single crystal was measured, and the specific surface free energy (SSFE) was calculated. Dispersion component of the SSFE was 90.57, 93.78, and 99.52 mN·m-1 for NaCl, KCl, and KBr, respectively. Polar component of the SSFE was 1.05, 0.65, and 0.45 mN·m-1 for NaCl, KCl, and KBr. Such a large ratio of dispersion component of SSFE results from the neutrality of the crystal surface of alkali halide. Lattice component of alkali halide is 780, 717 and 689 kJ·mol-1 for NaCl, KCl, and KBr. The larger lattice enthalpy decreases dispersion component, and increases polar component of the SSFE. The larger lattice enthalpy is considered to enhance the rumpling of the crystal surface more strongly, and such rumpling is considered to decrease the neutrality of the crystal surface.
Salmon Migration Patterns Revealed the Temporal and Spatial Fluctuations of the Radiocesium Levels in Terrestrial and Ocean Environments
Takaomi Arai
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100779
Abstract: The disabling of the Fukushima Daiichi Nuclear Power Plant (F1NPP) resulted in the release of radionuclides, including 134Cs and 137Cs, into the air and the ocean. The unpredicted nuclear accident is of global concern for human health and the ecosystem. Although investigations of radionuclides in environments were performed shortly after the accident started, the temporal and spatial impacts and fluctuations on the releasing radionuclides to natural environment remain unclear. I focused on salmon, which migrate from inland to the open ocean globally, to reveal the three-year (May 2011 to February 2014) fluctuations and accumulations of 134Cs and 137Cs from terrestrial to open ocean environments after the F1NPP accident. The 134Cs and 137Cs concentrations in six salmonids exhibited lower temporal variations for three years after the F1NPP accident, suggesting that these radionuclides are widely distributed and these radionuclides remain in the natural environment globally with less convergence. The accumulation patterns were significantly different among the different salmon species. Fluvial (freshwater residence) type salmons exhibited significantly higher accumulation in 134Cs (25.3–40.2 Bq kg?1 in mean) and 137Cs (41.4–51.7 Bq kg?1 in mean) than did the anadromous (sea-run) type salmons (0.64–8.03 Bq kg?1 in mean 134Cs and 0.42–10.2 Bq kg?1 in mean 137Cs) suggesting widespread contamination in terrestrial environments versus the coastal and open ocean environments. Salmonids are the most highly migratory animals and are characterised by their strong tendency to return home to their natal site for reproduction. Salmonids have a potential to be a good indicator as an effective monitoring animal.
Thermodinamic Interpretaion of the Morphology Individuality of Natural and Synthesized Apatite Single Crystals  [PDF]
Takaomi Suzuki, Haruka Takemae, Mika Yoshida
Journal of Crystallization Process and Technology (JCPT) , 2013, DOI: 10.4236/jcpt.2013.34019

Specific surface free energy (SSFE) of natural calcium fluorapatite from the same mother rock and synthesized barium chlorapatite from the same lot was determined using contact angle of water and formamide droplets, compared with grown length of crystal face (h). The experimentally obtained SSFEs have different values even for the same index faces of the different crystals. The SSFEs also have wide distribution for each face of crystals. Observed SSFE is considered to be not only the SSFE of ideally flat terrace face, but also includes the contribution of strep free energy. Though the crystals we experimentally obtained were growth form, the relationship between SSFE and h was almost proportional, which looks like satisfying Wulff’s relationship qualitatively. The slope of SSFE versus h line shows the driving force of crystal growth, and the line for larger crystal has less steep slope. The driving force of crystal growth for larger crystal is smaller, which also means that the chemical potential is larger for larger crystal. The individuality of crystals for the same lot can be explained by the difference of the chemical potential of each crystal.

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