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91.
Kiwa Kitada Siti Machmudah Mitsuru Sasaki Motonobu Goto Yuya Nakashima Shoichiro Kumamoto Takashi Hasegawa 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(5):657-661
BACKGROUND: Chlorella vulgaris is a green microalgae that contains various pigment components of carotenoids and chlorophylls. Supercritical CO2 is widely used for extraction of pharmaceutical compounds because it is non‐oxic and easily separated from extracted material by simply depressurizing. In this work, pharmaceutical compounds from Chlorella vulgaris have been extracted using supercritical CO2 with or without entrainer at various extraction conditions. RESULTS: Based on high performance liquid chromatography (HPLC) analysis, the extracts contained pigment components, such as lutein, β‐carotene, chlorophyll a and b. Higher extraction pressure and temperature promoted higher lutein extraction by supercritical CO2. The optimum pressure and temperature for extraction were obtained as 50 MPa and 80 °C. Ethanol as an entrainer was more effective than acetone for the extraction of pigment components. Pigment components in the extract obtained by supercritical CO2 with and without entrainer were compared with the extract obtained by a conventional extraction method. CONCLUSION: Supercritical CO2 has been successfully applied for the extraction of pigment components from Chlorella vulgaris. Supercritical CO2 enabled high selectivity for lutein extraction; however, the lutein yield was lower than that obtained by extraction using supercritical CO2 with ethanol and soxhlet. Copyright © 2008 Society of Chemical Industry 相似文献
92.
Yoshiro Nagata Eigo Shimizu Naoki Hibio Kumiko Ui-Tei 《International journal of molecular sciences》2013,14(6):11171-11189
Most of the intracellular endogenous microRNAs (endo-miRNAs) are considered to be saturated in Argonaute (Ago) proteins in the RNA-induced silencing complexes (RISCs). When exogenous miRNAs (exo-miRNAs) are introduced into cells, endo-miRNAs in the RISC may be replaced with exo-miRNAs or exo-miRNAs, and endo-miRNAs might also compete for the position in the newly synthesized RISC with each other. This would lead to the fluctuation of global gene expression not only by repression of exo-miRNA target gene expression, but also by the increase of the endo-miRNA target gene expression. In the present study, we quantified the changes in the expression levels of target genes of exo-miRNA and endo-miRNA in the cells transfected with fifteen different exo-miRNAs by microarray experiments. Different exo-miRNAs increased ratios of expression levels of target genes of a given endo-miRNA to different extents, suggesting that the replacement efficiencies might differ according to the exo-miRNA types. However, the increased ratios in the expression levels of each endo-miRNA target genes by the transfection of any particular exo-miRNA were mostly equivalent, suggesting that the endo-miRNAs present in the RISC might be replaced with excessive exo-miRNAs at similar levels, probably because they exist in single-stranded forms in the RISC. 相似文献
93.
Norihito Mayama Hiroyuki Yoshida Tatsuo Iwata Kaoru Sasakawa Atsushi Suzuki Yuya Hanaoka Yoshihiro Morita Akito Kuroda Masanori Owari 《Diamond and Related Materials》2010,19(7-9):946-949
In this study, we report the characterization of carbonaceous films deposited on metal substrates by liquid-phase electrodeposition in methanol. The characterization of carbonaceous films by electrodeposition was examined by means of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), secondary ion mass spectrometry (SIMS), atom probe (AP) and high resolution-elastic recoil detection analysis (HR-ERDA). From these results, it was found that the films deposited on the metal substrates were composed of the sp2 and sp3 carbon contents, of which the ratio was about 7:3. Furthermore, the films by electrodeposition contained much hydrogen. The hydrogen contents in the surface were about 60 at.% and those in the subsurface were a few 10 at.%. 相似文献
94.
Midorikawa K. Nagata Y. Kubodera S. Obara M. Toyoda K. 《IEEE journal of selected topics in quantum electronics》1995,1(3):931-940
Soft X-ray amplification by optical field-induced ionization (OFI) of a preformed plasma is investigated. A small-signal gain of 20 cm-1 and a gain-length product of 4 at 13.5 nm on the Lyman-α transition in hydrogen-like lithium have been obtained using the modified OFI scheme. Experimental and numerical results ensure that we have produced a plasma with a significantly lower electron temperature than what is expected by an above-threshold ionization model. To explain the results, a two component plasma model in which relatively high temperature electrons are produced by OFI in a cold electron bath of the preformed plasma is presented. The model indicates that the average electron temperature of the OFI plasma rapidly decreases since a high-temperature part of the electrons escapes from the focal volume without interaction. The initial electrons produced prior to the field ionization, which survive after the OEI, also significantly contribute to the rapid three-body recombination. Based on the ionization-induced refractive index change, the pulse propagation of a high-intensity pump laser during the OFI is also discussed 相似文献
95.
96.
H. Nagata G.D. Feke Yagang Li W.R. Bosenberg 《Photonics Technology Letters, IEEE》2004,16(7):1655-1657
DC drift characteristics of z-cut LiNbO/sub 3/ modulators with oxide buffer layers were studied with respect to their acceleration factors and long-term reliability. Analysis of more than 120 data points of measured drift tests indicate a slight nonlinear contribution by the starting bias voltage Vs to drift acceleration, with a factor equal to Vs/sup 1.27/. However, the observed nonlinearity is shown to have little affect on reliability estimations due to a dominant contribution from temperature activation energy; Ea=1.1 eV. The dc drift failure rates are estimated to be on the order of tens of failures in time for 20 years at 55/spl deg/C. 相似文献
97.
A highly functional circuit for pulse width modulation (PWM) signal processing is proposed as a core of the A-D merged circuit architecture for time-domain information processing. The core circuit employs a switched-current integration technique as its computing architecture and functions as a linear arithmetic operator, a memory, and also a delaying device of PWM signals. A 0.8-μm CMOS test chip includes 110 transistors plus two capacitors and performs parallel additions and multiplications at the accuracy of 1.2 ns. A cumulative property of the technique allows the circuit to serve as a low-power accumulator that consumes 23% of the energy of the full digital 7-b accumulator. A PWM multiply-accumulate unit and a nonlinear operation unit are also proposed to extend functionality of the circuit. Since the PWM signal carries multibit data in a binary amplitude pulse, these circuits can be favorably applicable to low-voltage and low-power designs in the deep submicrometer era 相似文献
98.
A lanthanum strontium manganese thin oxide layer was plated on yttria stabilized zirconia by oxidizing the lanthanum strontium manganese ions with hydrogen peroxide as the oxidant. The plated oxide layer was firmly adherent to the substrate, and its morphology was finely porous. The crystal phase of the oxide was determined by XRD to be a perovskite-type. The mechanism for the oxide layer formation by an oxide electroless plating was studied by means of ESCA. As a cathode of solid oxide fuel cell (SOFC), the electrode characteristics of an oxide plated in this way were measured by the current interruption method at 1000° C. The cathodic overpotential of this electrode was less than 40 mV at 1 A cm–2 This small overvoltage was considered to be based on an effective large electrode reaction area. 相似文献
99.
Wataru Nakao Hiroyuki Fukuyama Kazuhiro Nagata 《Journal of the American Ceramic Society》2002,85(4):889-896
The experimental method for the high-temperature reaction equilibria in the AlN-Al2 O3 system has been established. The equilibrium N2 -CO gas compositions coexisting with AlN- Al2 O3 -graphite have been successfully measured by quadrupole mass spectrometry and gas chromatography. From the obtained results, the standard Gibbs energy change of the forming reaction of AlN by carbothermal nitridation is determined at temperatures ranging from 1723 to 1899 K:
From the obtained result, the standard Gibbs energy of formation of AlN and the third-law enthalpy of formation of AlN at 298.15 K are derived as
The disagreement between the present results and values in the NIST–JANAF thermodynamic table is discussed. 相似文献
From the obtained result, the standard Gibbs energy of formation of AlN and the third-law enthalpy of formation of AlN at 298.15 K are derived as
The disagreement between the present results and values in the NIST–JANAF thermodynamic table is discussed. 相似文献
100.
Yamanaka K. Nagata Y. Nakano S. Koda T. Nishino H. Tsukahara Y. Cho H. Inaba M. Satoh A. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1995,42(3):381-386
We present principle and application of a novel noncontact velocity measurement of surface acoustic waves (SAW) on crystals and thin films using laser interference fringes scanned at the phase velocity of SAW. The scanning interference fringes (SIF) are produced by intersecting two laser beams with a frequency difference. The SAW velocity within the laser beam spot is measured as the ratio of observed SAW frequency and predetermined wave number of the SIF. The frequency measurement can be quite precise because of a large number of generated SAW carriers and amplitude enhancement effect. The SAW velocity measurement is free from the water loading effect accompanying the leaky SAW measurements. This principle was successfully applied to evaluate Si 3N4 and SiO2 films deposited on Si (001) surface 相似文献