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Search Results: 1 - 10 of 1032 matches for " Taketoshi Murakami "
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Synergistic Antibacterial Performance of a Cu/WO3-Added PTFE Particulate Superhydrophobic Composite under Visible-Light Exposure  [PDF]
Yanyan Yao, Kentaro Yamauchi, Goro Yamauchi, Tsuyoshi Ochiai, Taketoshi Murakami, Yoshinobu Kubota
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2012, DOI: 10.4236/jbnb.2012.34042
Abstract: Addition of TiO2 to a polytetrafluoroethylene (PTFE) particle-dispersed composite contributes to the self-cleaning properties of the water-repellent composite. However, its application is limited to outdoor usage or under ultraviolet (UV) irradiation. In this study, a novel visible-light-sensitive photocatalytic and superhydrophobic material was developed by adding Cu/WO3 to a PTFE particulate composite material to overcome this deficit. A remarkable property of this novel composite material is the synergistic antibacterial performance against Escherichia coli (E. coli), Staphylo-coccus aureus, and methicillin-resistant Staphylococcus aureus compared with the addition of Cu/WO3 without PTFE particles material. During 24-h exposure in visible light at 2000 lx, the number of viable cells of the three strains on the surface of the 8wt% Cu/WO3-added PTFE particulate composite decreased from 2 – 4 × 105 colony-formation units (CFUs) to less than 10, the limit of detection. This bactericidal rate is four times higher than that of 8wt% Cu/WO3 without PTFE particles material, which is attributed to the air trapped in the rough surface of the novel material providing additional oxygen to the photocatalytic reaction. Even for exposure to visible light at 100 lx, the decrease in CFUs of E. coli on the 12wt% Cu/WO3-added PTFE particulate composite reached nearly 2.0 logs. The characterization of the Cu/WO3-added PTFE particulate composite indicated that the composite material containing 80wt% PTFE maintained a superhydrophobic or water-repellent property with a water contact angle >150, although the Cu/WO3 in the composite material remained hydrophilic under visible light. The Cu/WO3-added PTFE particulate composite displayed photo-catalytic reactions to decompose oleic acid adsorbed on its surface and gaseous acetaldehyde under UV-A and visible-light illumination. All results demonstrate that the Cu/WO3-added PTFE particulate composite material may be used in sterilization, as a water repellent, for self-cleaning, and in the oxidative decomposition of volatile organic compounds (VOC) both indoors and outdoors.
Electrospinning Preparation and Photocatalytic Activity of Porous TiO2 Nanofibers
Shanhu Liu,Baoshun Liu,Kazuya Nakata,Tsuyoshi Ochiai,Taketoshi Murakami,Akira Fujishima
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/491927
Abstract: Porous TiO2 nanofibers were prepared via a facile electrospinning method. The carbon nanospheres were mixed with the ethanol solution containing both poly(vinylpyrrolidone) and titanium tetraisopropoxide for electrospinning; and subsequent calcination of as-spun nanofibers led to thermal decomposition of carbon nanospheres, leaving behind pores in the TiO2 nanofibers. The morphology and phase structure of the products were investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Furthermore, the photocatalytic activity of porous TiO2 nanofibers was evaluated by photodecomposition of methylene blue under UV light. Results showed that the porous TiO2 nanofibers have higher surface area and enhanced photocatalysis activity, compared to nonporous TiO2 nanofibers.
Synthesis, Characterization, and Photocatalysis of Fe-Doped : A Combined Experimental and Theoretical Study
Liping Wen,Baoshun Liu,Xiujian Zhao,Kazuya Nakata,Taketoshi Murakami,Akira Fujishima
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/368750
Abstract: Fe-doped TiO2 was prepared by hydrothermal treating Ti peroxide sol with different amount of iron nitrate. Fe ions can enter TiO2 lattice by substituting Ti4
Photomechanical Energy Conversion of Photoresponsive Fibers Exhibiting Bending Behavior
Kazuya Nakata,Yosuke Ishikawa,Munetoshi Sakai,Baoshun Liu,Tsuyoshi Ochiai,Hideki Sakai,Taketoshi Murakami,Masahiko Abe,Akira Fujishima
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/574124
Abstract: Photoresponsive fibers based on poly(acrylamide) (PAA) with methylene blue (MB) dye were prepared. All semicircular fibers show bending towards the direction of the flat surface of the fiber when illuminated. The fibers recover their initial shape when the illumination stops. The fiber is heated upon illumination and cooled to room temperature once the illumination is stopped. The fiber also is sensitive to humidity, showing bending behavior towards the direction of the flat surface of the fiber upon changing the humidity. The mechanical energy of the PAA/MB fiber is approximately 0.6?mN for the bending direction when it is illuminated. A possible mechanism for the bending behavior is as follow: (1) the fiber is heated upon illumination because of the photothermal effect, (2) the fiber loses water molecules, (3) the fiber shrinks; bending towards the direction of the flat surface of the fiber occurs because of a difference in the shrinkage for the flat surface and the other side of the fiber. Finally, we demonstrated that a PP ball (1.5?mg) can be moved by the mechanical energy produced by the changing shape of the fiber upon illumination. 1. Introduction Utilization of solar energy is a key factor for development of a sustainable society. Among a number of approaches for solar energy conversion, photomechanical energy conversion has significant advantages such as direct energy conversion from photo to mechanical, which may potentially lead to high energy conversion efficiency, no cable for working, and space-saving. Typical photomechanical materials that change shape in response to light are liquid crystalline elastomer films based on azobenzene derivatives [1–14]. These materials show bending behavior upon illumination because the structure of azobenzene derivative molecules in the film changes from trans to cis form, which generates mechanical energy. Although these materials have attracted much attention because they can be applied as photodriven motors [9], actuators [1, 3, 4, 6, 8, 10, 11, 15–17], and new types of solar energy conversion systems [2, 5, 7, 11–14, 16, 18, 19], they need multiple synthetic procedures followed by rubbing to align the azobenzene molecules, which makes them impractical for many applications. Materials exhibiting a volume change in response to light are of interest [20–22]. For example, hydrogels that show a volume change upon the application of light have been reported previously [21–23]. The basic mechanism for the volume change is a solvent absorption/desorption process. Suzuki and Tanaka reported that a polymer gel
Bone marrow cell transplantation efficiently repairs tendon and ligament injuries
Taketoshi Kushida
Frontiers in Cell and Developmental Biology , 2014, DOI: 10.3389/fcell.2014.00027
Abstract: Abstract Growth factors play key roles during the various stages of the tendon healing process and stimulate fibroblasts within or outside the tendon to induce type-I collagen synthesis. Furthermore, localized administration of growth factors has been successfully used for treating tendon and ligament injuries in animal models. Mesenchymal stem cells (MSCs) transplants have also been previously used to treat tendon and ligament injuries. MSCs can differentiate into fibroblasts, which secrete growth factors and cytokines that are essential for extrinsic healing and improved vascularization of the damaged tendon or ligament tissue. In addition, hematopoietic stem cells (HSCs)-derived hematolymphoid cells secrete growth factors and cytokines required for extrinsic healing. Therefore, a novel cost-efficient approach involves injecting fresh whole bone marrow cells, consisting of both MSCs and HSCs, into the injured tissue enables rapid healing. 1. Introduction Growth factors such as transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF-1), platelet-derived growth factor (PDGF), and basic fibroblast growth factor (bFGF) have been associated with the tendon healing process (Molloy et al., 2003; Zhang et al., 2003). Among these growth factors, TGF-β1 plays a key role during the various tissue repair stages and is secreted not only by fibroblasts differentiated from mesenchymal stem cells (MSCs), but also by several types of cells that differentiate from hematopoietic stem cells (HSCs; Sporn et al.,1986). In this review, the role of TGF-β and MSC-derived fibroblasts in tendon or ligament tissue repair is described. Furthermore, the potential application of bone marrow cell transplantation (BMCT) as a novel method for treating tendon and ligament injuries is also discussed. 2.1 Healing process Human tendon healing process is classified into five phases as follows: immediate post injury phase, inflammatory phase, proliferation phase, reparative phase, and remodeling phase (Molloy et al., 2003). Tissue repair depends on both intrinsic and extrinsic processes. Intrinsic healing occurs within the tendon itself as a result of the activity of intrinsic fibroblasts and an increased intratendinous blood supply from the synovium and osseous insertion (Rank et al., 1980; Deie et al., 1995; Koga et al., 2007). Extrinsic factors that influence tissue repair include the availability of proteins originating from peripheral fibroblasts, plasma, inflammatory cells, and extratendinous vascular invasion (DesRosiers et
Broad Spectrum Microbicidal Activity of Photocatalysis by TiO2
Ryuichi Nakano,Masayuki Hara,Hitoshi Ishiguro,Yanyan Yao,Tsuyoshi Ochiai,Kazuya Nakata,Taketoshi Murakami,Jitsuo Kajioka,Kayano Sunada,Kazuhito Hashimoto,Akira Fujishima,Yoshinobu Kubota
Catalysts , 2013, DOI: 10.3390/catal3010310
Abstract: Photocatalytically active titanium dioxide (TiO 2) is widely used as a self-cleaning and self-disinfecting material in many applications to keep environments biologically clean. Several studies on the inactivation of bacteria and viruses by photocatalytic reactions have also been reported; however, only few studies evaluated the spectrum of the microbicidal activity with photocatalysis for various species. There is a need to confirm the expected effectiveness of disinfection by photocatalysis against multidrug-resistant bacteria and viruses. In this study, microbicidal activity of photocatalysis was evaluated by comparing the inactivation of various species of bacteria and viruses when their suspensions were dropped on the surface of TiO 2-coated glass. Gram-positive bacteria, e.g., methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae, were easily inactivated by photocatalysis, whereas some gram-negative bacteria, e.g., Escherichia coli and multidrug-resistant Pseudomonas aeruginosa, were gradually inactivated by photocatalysis. Influenza virus, an enveloped virus, was significantly inactivated by photocatalysis compared with feline calicivirus, a non-enveloped virus. The effectiveness of microbicidal activity by photocatalysis may depend on the surface structure. However, they are effectively inactivated by photocatalysis on the surface of TiO 2-coated glass. Our data emphasize that effective cleaning and disinfection by photocatalysis in nosocomial settings prevents pathogen transmission.
Dynamic Effect of Low-Cost Entry on the Conduct Parameter: An Early-Stage Analysis of Southwest Airlines and America West Airlines  [PDF]
Hideki Murakami
Modern Economy (ME) , 2013, DOI: 10.4236/me.2013.44032

The purpose of this research is to investigate the dynamic changes in the competition between air carriers by applying a revised conduct parameter method. We examine the cases of Southwest Airlines and America West Airlines due to the availability of data. Our interests are in what fashion a low-cost carrier entered the market, how the rival reacted, and whether the fashions of competition between two types of air carrier remained stable as time passed. Our empirical results show that the fashions of competition fell between Cournot and “P = MC” competition, and competitive fashions were sometimes stable but sometimes not.

Dance Type and Flight Parameters Are Associated with Different Mushroom Body Neural Activities in Worker Honeybee Brains
Taketoshi Kiya,Takeo Kubo
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0019301
Abstract: Honeybee foragers can transmit the information concerning the location of food sources to their nestmates using dance communication. We previously used a novel immediate early gene, termed kakusei, to demonstrate that the neural activity of a specific mushroom body (MB) neuron subtype is preferentially enhanced in the forager brain. The sensory information related to this MB neuron activity, however, remained unclear.
Analysis of GABAergic and Non-GABAergic Neuron Activity in the Optic Lobes of the Forager and Re-Orienting Worker Honeybee (Apis mellifera L.)
Taketoshi Kiya,Takeo Kubo
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0008833
Abstract: European honeybee (Apis mellifera L.) foragers have a highly developed visual system that is used for navigation. To clarify the neural basis underlying the highly sophisticated visual ability of foragers, we investigated the neural activity pattern of the optic lobes (OLs) in pollen-foragers and re-orienting bees, using the immediate early gene kakusei as a neural activity marker.
Flavonoid Profiles of Wild Grapes Native to Japan: Vitis coignetiae Pulliat and Vitis ficifolia Bunge var. ganebu Hatusima  [PDF]
Shuji Shiozaki, Kazunori Murakami
Agricultural Sciences (AS) , 2017, DOI: 10.4236/as.2017.83017
Abstract: Flavonoids are a group of natural compounds in plants with versatile health benefits for humans. Grapes are a dietary source of flavonoids and the flavonoid components in grape berries can depend on the grape species and cultivar. In this experiment, proanthocyanidins, flavonols, and anthocyanins were analyzed in Vitis coignetiae and V. ficifolia var. ganebu, wild grapes native to Japan, and compared with those in V. labruscana cv. Muscat Bailey A, to evaluate the potential of the wild grapes as a grape resource. Proanthocyanidin contents in seeds were lower in the two wild grapes than in Muscat Bailey A. However, the skin of V. ficifolia var. ganebu was the richest source of proanthocyanidins. Flavonol levels in the skins of the two wild grapes were lower than that in the skin of Muscat Bailey A. Colorimetry determined that the total anthocyanin content in the skin of V. ficifolia var. ganebu was 6 times and 7 times higher, respectively, than those of V. coignetiae and Muscat Bailey A. Although monoglucoside anthocyanin levels analyzed by high-pressure liquid chromatography (HPLC) were in the order Muscat Bailey A > V. ficifolia var. ganebu > V. coignetiae, most of the diglucoside and acylated monoglucoside and diglucoside anthocyanin levels identified by HPLC-mass spectrometry were highest in V. ficifolia var. ganebu. These data suggest that V. ficifolia var. ganebu might be a novel source of flavonoids and superior to V. coignetiae as a source of flavonoids.
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