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Search Results: 1 - 10 of 894 matches for " Satoru Matsukawa "
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Tris(2,4,6-trimethoxyphenyl)phosphine (TTMPP): Efficient Catalysts for the Cyanosilylation and Cyanocarbonation of Aldehydes and Ketones
Satoru Matsukawa,Izumi Sekine,Ayumi Iitsuka
Molecules , 2009, DOI: 10.3390/molecules14093353
Abstract: A variety of aldehydes and ketones were transformed to their corresponding cyanohydrin silyl ethers in good to excellent yields in the presence of 1-5 mol% of tris(2,4,6-trimethoxyphenyl)phosphine (TTMPP). Cyanohydrin carbonates were also readily prepared using 5-10 mol% of TTMPP as an organocatalyst.
Restoration of magnetization reversal under hydrostatic pressure in the lightly electron-doped manganite compound (Ca,Sr)Mn0.95Sb0.05O3
Takahiro Fujiwara,Michiaki Matsukawa,Takahiro Aoyagi,Satoru Kobayashi Shigeki Nimori,Ramanathan Suryanarayanan
Physics , 2013,
Abstract: We report on the anomalous magnetization reversal under hydrostatic pressure in the lightly electron-doped manganite compound (Ca$_{1-x}$Sr$_{x}$)Mn$_{0.95}$Sb$_{0.05}$O$_{3}$ with its fixed carrier content. In a weakly magnetic field cooled measurement, diamagnetic magnetization is observed for $x\leq 15\%$, which changes to positive values for $x>15\%$. However, on an application of pressure on the samples with $x=16\%$ and 17$\%$, magnetization reverses sign and diamagnetism is restored. We present a magnetic phase diagram as a function of Sr concentration, under both ambient and hydrostatic pressures. To understand better the thermodynamical properties of this system, we have measured the specific heat as a function of temperature under a field cooling of 100 Oe. Our data show no anomalies associated with the temperature dependent magnetization reversal, indicating the absence of a long-rang magnetic ordering. The $ac$ magnetic susceptibility measurement points to the existence of magnetic frustration for the Sr substituted samples exhibiting diamagnetic behavior.
Effect of pressure on magnetization and magnetostriction jumps in the manganite Eu$_{0.58}$Sr$_{0.42}$MnO$_{3}$
Yoshiaki Yamato,Michiaki Matsukawa,Tasuku Inomata,Satoru Kobayashi,Ramanathan Suryanarayanan,Sigeki Nimori,Keiichi Koyama,Norio Kobayashi
Physics , 2010,
Abstract: We have demonstrated the effect of pressure on magnetization jump and its associated magnetostriction in Eu$_{0.58}$Sr$_{0.42}$MnO$_{3}$. The critical field lowered by the applied pressure is explained by a suppression of the metastable blocked state, which is inherent to the phase separated manganite system exhibiting the magnetic avalanche. To reduce a factor of the bad thermal coupling in the bulk sample, and to further examine the nature of the magnetization jump, we have performed the influence of pressure on the isothermal magnetization of the powder sample. There is no discrepancy in the critical field between the bulk and powder samples although the $MH$ curve of the latter is not saturated at high fields. These findings indicate a crucial role of the frozen phase separated state in the abrupt transition.
Magnetization and transport properties in the superconducting Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-δ}$ with metallic double-chain
Shibuki Toshima,Michiaki Matsukawa,Taiji Chiba,Satoru Kobayashi,Sigeki Nimori,Makoto Hagiwara
Physics , 2012, DOI: 10.1016/j.physc.2012.05.008
Abstract: We have reported the effect of pressure on the magnetization, and transport properties in the nominal composition Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-\delta}$ synthesized by a sol-gel technique. A reduction treatment of the as-sintered sample in vacuum causes higher superconductivity achieving $T_{c,on}=\sim 30$ K for $\delta =0.94$. Application of hydrostatic pressure on the oxygen depleted sample enhances its onset temperature up to 36 K at 1.2 GPa, indicating the nearly optimum doping level of the charge carrier in comparison to the pressure dependence of lower $T_{c}$ samples with $\delta =0.45$. Seebeck coefficient of the superconducting sample shows a metallic conduction, followed by a clear drop below $T_{c,on}$ and is in its temperature dependence below 100 K quite different from that of the non-superconducting one. This finding strongly suggests a dramatic change of the electronic state along the CuO double chain due to the reduction treatment for the appearance of superconductivity .
Suppression of the low-temperature phase-separated state under pressure in (Eu$_{1-x}$Gd$_{x}$)$_{0.6}$Sr$_{0.4}$MnO$_{3}$ ($x=0,0.1$)
Tasuku Inomata,Michiaki Matsukawa,Daichi Kimura,Yoshiaki Yamato,Satoru Kobayashi,Ramanathan Suryanarayanan,Sigeki Nimori,Keiichi Koyama,Norio Kobayashi
Physics , 2011, DOI: 10.1016/j.jmmm.2012.06.036
Abstract: We have demonstrated the effect of pressure on the steplike metamagnetic transition and its associated magnetostriction in (Eu$_{1-x}$Gd$_{x}$)$_{0.6}$Sr$_{0.4}$MnO$_{3}$ ($x=0$ and 0.1). The critical field initiating the field induced ferromagnetic transition in both samples is lowered by the applied pressure. The further application of external pressure up to 1.2 GPa on the $x=0$ parent sample causes a spontaneous ferromagnetic transition with a second-oder like character, leading to collapses of the steplike transition and its concomitant lattice striction. These findings indicate a crucial role of the low-temperature phase separated state characterized by a suppressed magnetization upon decreasing temperature.
STAT Proteins in Innate Immunity during Sepsis: Lessons from Gene Knockout Mice
Matsukawa,Akihiro
Acta Medica Okayama , 2007,
Abstract: The innate immune system provides immediate defense against infection and serves as the first line of host defense during infection. In innate immunity, leukocytes such as neutrophils and macrophages recognize and respond to pathogens in a non-specific manner. Therefore, the recruitment and activation of leukocytes are essential in innate immunity, and are governed by a variety of chemical mediators including cytokines. Cytokines are generally divided into 2 types, termed type-1 and type-2 cytokines. Type-1 cytokines are important in local host defense, while type-2 cytokines play a protective role when inflammatory response spreads to the body. These cytokines exert their biological functions through the janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. STAT1/3/4/6 are transcription factors that mediate IFNgamma/IL-10/IL-12/IL-13 cytokine signaling, respectively. Evidence indicates that STAT proteins have a significant impact on innate immunity during sepsis. This review focuses on recent understandings in the regulation of innate immunity by STAT proteins during sepsis and septic shock. The suppressor of cytokine signaling (SOCS) proteins are a family of SH2 domain-containing cytoplasmic proteins that complete a negative feedback loop to attenuate signal transduction from cytokines that act through the JAK/STAT pathway. The participation of SOCS proteins in sepsis is also discussed.
Effect of magnetic field on the superconducting phase in the electron-doped metallic double-chain compound Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-δ}$
Taiji Chiba,Michiaki Matsukawa,Junki Tada,Satoru Kobayashi,Makoto Hagiwara,Tsuyoshi Miyazaki,Kazuhiro Sano,Yoshiaki Ono,Takahiko Sasaki,Jun-ichi Echigoya
Physics , 2013,
Abstract: We report the magnetotransport and $dc$ magnetic susceptibility of the polycrystalline samples of Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-\delta}$, to examine the effect of magnetic field on the superconducting phase of the metallic CuO double chain. The resistive critical magnetic field is estimated to be about 21 T at low temperatures from the resistive transition data. On the other hand, the corresponding critical field determined from the magnetization measurements gives rise to a very low value of $\sim 0.3$T at 2 K. These discrepancies in the magnetic response between the resistivity and magnetization data are caused by disappearance of the magnetically shielding effect even in relatively lower fields. In spite of the observation of the resistive drop associated with the superconducting transport currents, the suppression of the diamagnetic signal is probably related to the superconductivity of quasi one-dimensional CuO double-chain. The behavior of Seebeck coefficient in the superconducting Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-\delta}$ is discussed on the basis of the double chain model from the density functional band calculation.
Case Studies of Energy Saving and CO2 Reduction by Cogeneration and Heat Pump Systems  [PDF]
Satoru Okamoto
Open Journal of Energy Efficiency (OJEE) , 2013, DOI: 10.4236/ojee.2013.22014
Abstract:

This paper describes two case studies: 1) a cogeneration system of a hospital and 2) a heat pump system installed in an aquarium that uses seawater for latent heat storage. The cogeneration system is an autonomous system that combines the generation of electrical, heating, and cooling energies in a hospital. Cogeneration systems can provide simultaneous heating and cooling. No technical obstacles were identified for implementing the cogeneration system. The average ratio between electric and thermal loads in the hospital was suitable for the cogeneration system operation. An analysis performed for a non-optimized cogeneration system predicted large potential for energy savings and CO2 reduction. The heat pump system using a low-temperature unutilized heat source is introduced on a heat source load responsive heat pump system, which combines a load variation responsive heat pump utilizing seawater with a latent heat-storage system (ice and water slurry), using nighttime electric power to level the electric power load. The experimental coefficient of performance (COP) of the proposed heat exchanger from the heat pump system, assisted by using seawater as latent heat storage for cooling, is discussed in detail.

Energy-Saving and Economical Evaluations of a Ceramic Gas Turbine Cogeneration Plant  [PDF]
Satoru Okamoto
Open Journal of Energy Efficiency (OJEE) , 2013, DOI: 10.4236/ojee.2013.22012
Abstract:

A ceramic gas turbine can save energy because of its high thermal efficiency at high turbine inlet temperatures. This paper deals with the thermodynamic and economic aspects of a ceramic gas turbine cogeneration system. Here cogeneration means the simultaneous production of electrical en-ergy and useful thermal energy from the same facility. The thermodynamic performance of a ceramic gas turbine cycle is assessed using a computer model. This model is used in parametric studies of performance under partial loads and at various inlet air temperatures. The computed performance is compared to the measured performance of a conventional gas turbine cycle. Then, an economic evaluation of a ceramic gas turbine cogeneration system is investigated. Energy savings provided by this system are estimated on the basis of the distributions of heat/power ratios. The computed economic evaluation is compared to the actual economic performance of a conventional system in which boilers produce the required thermal energy and electricity is purchased from a utility.

On the Application of the Laplace Transform in the Study of Phillips-Type Stabilization Policy  [PDF]
Satoru Kageyama
Theoretical Economics Letters (TEL) , 2015, DOI: 10.4236/tel.2015.56080
Abstract: This paper provides a reformulation of Phillips’s multiplier-accelerator model with stabilization policy in terms of the Laplace transform. Applying the Laplace transform, the differential equations of the economy are transformed into the algebraic ones on a complex variable. The transfer functions of economic variables are defined by these algebraic equations. With this representation, we show the effects of Phillips-type policy on equilibrium level and derive the necessary and sufficient condition for asymptotic stability.
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