Yokohama, Japan
Yokohama, Japan

Toin University of Yokohama is a private university in Aoba-ku, Yokohama, Kanagawa prefecture, Japan. Toin University of Yokohama was established in 1988. It offers degree programs in sports medicine, medical technology, engineering and law. Wikipedia.

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Yoshida M.,University of Tokyo | Yoshida K.,Toin University of Yokohama
Molecular Human Reproduction | Year: 2011

The chemotaxis of sperm towards eggs is a widespread phenomenon that occurs in most forms of life from lower plants to mammals and plays important roles in ensuring fertilization. In spermatozoa, the attractants act as beacons, indicating the path leading to the eggs from the same species. The existence of species-specific sperm chemotaxis has been demonstrated in marine invertebrates; thus, sperm chemotaxis may be involved in preventing crossbreeding, especially in marine invertebrates with external fertilization. However, the mechanisms of sperm chemotaxis in mammalian species differ from those of marine invertebrates. In mammals, the attractant source is not the egg, but follicular fluids or cumulus cells and chemotactic behaviour is shown only in small populations of sperm. Nevertheless, the fundamental mechanisms underlying sperm chemotaxis are likely to be common among all species. Among these mechanisms, intracellular Ca2+ concentration ([Ca2+]i) is an important factor for the regulation of chemotactic behaviour in spermatozoa. Sperm attractants induce the entry of extracellular Ca2+, resulting in [Ca2+]i increase in the sperm cells. Furthermore, [Ca2+]i modulates sperm flagellar movement. However, the relationship between [Ca2+]i and the chemotactic response of a sperm flagellum is not well known. Investigation of the dynamic responses of sperm cells to their attractants is important for our understanding of the regulation of fertilization. Here, we reviewed sperm chemotaxis focusing on the mechanisms that regulate sperm flagellar beating during the chemotactic response. © The Author 2011. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.

Miyasaka T.,Toin University of Yokohama
Journal of Physical Chemistry Letters | Year: 2011

Sensitized mesoscopic solar cells can exhibit high performance and processability by the use of a thin semiconductor layer in combination with a sensitizer of superior light-harvesting ability. This combination is an important key toward the realization of high-efficiency flexible solar cells using solution-based, rapid roll-to-roll printing processes. To this goal, preparation of a binder-free TiO2 paste is presented as a key process to low-temperature plastic electrode fabrication. For the future challenges of printable sensitized solar cells, this Perspective is focused on the importance of sensitizer choice for thin TiO2 films with regards to optimum light harvesting, showing photovoltaic behaviors of organic dye sensitizers and lead halide perovskite nanocrystals as inorganic sensitizers. Further, the author offers a comparison of the light-harvesting ability between organic dye sensitizers and inorganic quantum dot size sensitizers based on optical extinction coefficients and the surface density of the sensitizer. © 2011 American Chemical Society.

Muto T.,Toin University of Yokohama | Ikegami M.,Toin University of Yokohama | Miyasaka T.,Toin University of Yokohama
Journal of the Electrochemical Society | Year: 2010

Thin films of high cathodic activity for use in the counter electrode of a plastic dye-sensitized solar cell were prepared in the form of a mesoporous composite of metal oxide and conductive polymer, poly(3,4- ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT-PSS). The mesoporous film was prepared on an indium tin oxide-coated plastic electrode substrate by low temperature printing processes. As a low cost alternative to the conventional platinum-coated electrodes, it showed high activity as a cathode in a full-plastic dye-sensitized solar cell, yielding a photovoltaic conversion efficiency of 4.38%, which is close to that of the cell based on a vacuum-sputtered platinum electrode. Among various metal oxides (TiO 2, ZnO, NiO, and Al2 O3), TiO2 nanoparticles showed high activity in photocurrent enhancement in combination with PEDOT-PSS. © 2010 The Electrochemical Society.

Miyasaka T.,Toin University of Yokohama
Chemistry Letters | Year: 2015

Organo-lead halide perovskite compounds, otherwise called organicinorganic hybrid perovskite, represented by CH3NH3- PbI3, exhibit many rare functions as narrow-band-gap semiconductors that are superior in applications for photovoltaic power conversion as well as for high-gain photon-mode detection of visible light. In this review, photoelectric properties of solution-processed CH3NH3PbI3 films and future perspectives in low-cost device fabrication are discussed based on our investigations. © 2015 The Chemical Society of Japan.

Goto M.,Toin University of Yokohama | Goto M.,Yokohama General Hospital
Modern Rheumatology | Year: 2010

We prospectively compared the anti-inflammatory and antidyslipidemic effects of fenofibrate and statins in rheumatoid arthritis (RA) patients. Forty-four RA patients [male (M) = 7, female (F) = 37] with dyslipidemia were enrolled in this 6-month study and randomly allocated to the fenofibrate (2 M + 21 F = 23) or statins (5 M + 16 F = 21) group. We measured blood chemistry (serum lipid profile, sugar, urate, and γ-glutamyl transpeptidase) and blood pressure 2 h after breakfast. Visual analog scale (VAS), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and prednisolone (PSL) dosage were also recorded immediately before and after the study. Fenofibrate, but not statins, significantly decreased serum levels of total cholesterol, low-density lipoprotein-cholesterol, and triglycerides (all p < 0.05). A significant improvement in VAS was observed in both the fenofibrate group (49.1 ± 24.7 → 14.7 ± 11.2; p < 0.0001) and the statins group (47.4 ± 29.7 → 20.2 ± 16.5; p < 0.001). PSL dosage significantly decreased only in the fenofibrate group (3.58 ± 2.68 → 2.00 ± 2.22 mg/day; p < 0.01). Significant correlation was observed between DVAS and DCRP in the fenofibrate group (p < 0.05). Fenofibrate showed more anti-inflammatory and antidyslipidemic activity than statins in RA. © Japan College of Rheumatology 2010.

Sakai N.,Toin University of Yokohama | Miyasaka T.,Toin University of Yokohama | Murakami T.N.,Toin University of Yokohama | Murakami T.N.,Japan National Institute of Advanced Industrial Science and Technology
Journal of Physical Chemistry C | Year: 2013

ZnO is a promising candidate as a low-cost porous semiconductor material for photoelectrodes in dye-sensitized solar cells (DSSCs). However, ZnO-based DSSCs tend to exhibit lower energy conversion efficiencies than do those based on TiO2. In this study, the performance of ZnO porous electrodes was enhanced using a surface treatment carried out by immersion in cold aqueous TiCl4 solution that resulted in TiO2-coated ZnO (Z/T) electrodes. The Z/T electrodes were sensitized with either the Ru complex dye N719 or the organic indoline dye D149. For each dye, the DSSCs with the Z/T photoelectrodes showed the highest open-circuit voltage (Voc), short circuit current (Jsc), and power conversion efficiency compared to those with ZnO, TiO2, or TiO2-coated TiO2 (T/T) electrodes. To study the effects of the TiCl4 treatment, the relationships between the electron lifetime (τ), cell voltage, and electron density (n) of the cells prepared with each electrode, with each of the two dyes, or without either dye were assessed. It was found that the TiCl 4 treatment negatively shifted the conduction band edge (CBE) potential of the ZnO electrodes by more than 100 mV for both dyes and also in the absence of a dye. In addition, τ increased with the use of the organic D149 and in the absence of a dye. The DSSC with a D149-sensitized Z/T layer showed the highest efficiency of 4.89% under 100 mW cm-2 irradiation. © 2013 American Chemical Society.

Toyabe S.,Chuo University | Okamoto T.,Chuo University | Watanabe-Nakayama T.,Tokyo Institute of Technology | Taketani H.,Chuo University | And 2 more authors.
Physical Review Letters | Year: 2010

Molecular motors drive mechanical motions utilizing the free energy liberated from chemical reactions such as ATP hydrolysis. Although it is essential to know the efficiency of this free energy transduction, it has been a challenge due to the system's microscopic scale. Here, we evaluate the single-molecule energetics of a rotary molecular motor, F1-ATPase, by applying a recently derived nonequilibrium equality together with an electrorotation method. We show that the sum of the heat flow through the probe's rotational degree of freedom and the work against an external load is almost equal to the free energy change per a single ATP hydrolysis under various conditions. This implies that F1-ATPase works at an efficiency of nearly 100% in a thermally fluctuating environment. © 2010 The American Physical Society.

Ishii A.,Toin University of Yokohama | Miyasaka T.,Toin University of Yokohama
ChemPhysChem | Year: 2014

A thin solid-state dye-sensitized photovoltaic cell is fabricated by composing organic and inorganic heterojunctions in which the visible-light sensitizers are cyclopentadiene derivatives (Cp*) coordinated to a metal oxide, typically TiO2. The coordination bonds of the metallocene molecular complex (Ti-Cp*) create a new LMCT (ligand-to-metal charge transfer) absorption band and induce a rectified charge transfer from the organic ligands to TiO2, leading to photocurrent generation. Photovoltaic junctions are completed by coating crystalline organic molecules (perylene) as a hole-transport layer on the Cp*-coordinated TiO 2 surface by using the vapor deposition method. The molecular plane of Cp* on the TiO2 surfaces seems to help the hole-transport layer to form ordered structures, which effectively improve carrier conductivities and minimize interfacial resistance. The organic-inorganic hybrid thin-film photocell with metallocene molecular complexes is capable of generating high open-circuit voltages exceeding 1.2 V. Thin solid-state dye-sensitized photovoltaic cells are fabricated by composing organic and inorganic heterojunctions in which cyclopentadiene derivatives (Cp*) coordinated to a metal oxide (typically TiO2) act as visible-light sensitizers. The obtained organic-inorganic hybrid devices can generate open-circuit voltages greater than 1.2 V. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chen H.-W.,Toin University of Yokohama | Sakai N.,University of Oxford | Ikegami M.,Toin University of Yokohama | Miyasaka T.,Toin University of Yokohama
Journal of Physical Chemistry Letters | Year: 2015

Although there has been rapid progress in the efficiency of perovskite-based solar cells, hysteresis in the current-voltage performance is not yet completely understood. Owing to its complex structure, it is not easy to attribute the hysteretic behavior to any one of different components, such as the bulk of the perovskite or different heterojunction interfaces. Among organo-lead halide perovskites, methylammonium lead iodide perovskite (CH3NH3PbI3) is known to have a ferroelectric property. The present investigation reveals a strong correlation between transient ferroelectric polarization of CH3NH3PbI3 induced by an external bias in the dark and hysteresis enhancement in photovoltaic characteristics. Our results demonstrate that the reverse bias poling (-0.3 to -1.1 V) of CH3NH3PbI3 photovoltaic layers prior to the photocurrent-voltage measurement generates stronger hysteresis whose extent changes significantly by the cell architecture. The phenomenon is interpreted as the effect of remanent polarization in the perovskite film on the photocurrent, which is most enhanced in planar perovskite structures without mesoporous scaffolds. © 2014 American Chemical Society.

Ishii A.,Toin University of Yokohama | Miyasaka T.,Toin University of Yokohama
Chemical Communications | Year: 2012

A thin solid-state photovoltaic cell of organic-inorganic hetero junctions was fabricated by forming a dye-metal charge-transfer complex as the sensitizer monolayer at the interface of crystalline state organic and inorganic semiconductors. The organic-inorganic hybrid thin-film photocell generates a high photovoltage of 1.2 V, yielding an energy conversion efficiency of up to 1.5%. © The Royal Society of Chemistry 2012.

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