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61.
62.
63.
We discuss the similarity and the difference between EXAFS and EELFS for catalysis study based on the theory developed by the present authors. The information obtained from small-and large-angle scattering EELFS is quite different, and the former setup is recommended for catalysis study. 相似文献
64.
Phospholipase A2 (PLA2) activity was investigated in various tissues of tobacco (Nicotiana tabacum). PLA2 activity in the flower was 15 times higher than that in the leaf, stem, and root. PLA2 activity in the flower appears to have originated from both Ca2+-dependent and-independent PLA2. A cDNA clone for protein with homology to animal secretory PLA2 (sPLA2), denoted as Nt PLA2, was isolated from the tobacco flower. The cDNA of Nt PLA2 encoded a mature protein of 127 amino acid residues with a putative signal peptide of 30 residues. The amino acid sequence
for mature Nt PLA2 contains 12 cysteines, a Ca2+ binding loop, and a catalytic domain that are commonly conserved in animal sPLA2. The Nt PLA2 mRNA was mainly expressed in the root and stem of tobacco. The recombinant Nt PLA2 was expressed as a fusion protein with thioredoxin in Escherichia coli. From the bacterial cell lysate, the fusion protein was recovered in soluble form and cleaved by Factor Xa proteinase. Then
the recombinant mature Nt PLA2 was purified by ion exchange chromatography. It was discovered that the purified Nt PLA2 essentially requires Ca2+, for the enzyme activity when the activity was determined using mixed-micellar phospholipid substrates with sodium cholate.
The optimal activity of Nt PLA2 was at pH 8–10 when PC was used as a substrate. 相似文献
65.
66.
Higuchi H. Oomura E. Hirano R. Sakakibara Y. Namizaki H. Susaki W. Fujikawa K. 《Electronics letters》1983,19(23):976-977
It is found that electroluminescent mode aging at high-temperature and high-current levels is useful for selecting long-lived InGaAsP 1.3 ?m lasers. Lasers selected by this screening have little change in threshold current or forward voltage through the aging test at an elevated temperature with constant light-output power. 相似文献
67.
Diffusion of silicon in aluminum 总被引:1,自引:0,他引:1
Shin-ichiro Fujikawa Ken-ichi Hirano Yoshiaki Fukushima 《Metallurgical and Materials Transactions A》1978,9(12):1811-1815
Interdiffusion coefficients in Al-Si alloys were determined by Matano’s method in the tem-perature range from 753 to 893 K
with the couple consisting of pure aluminum and an Al-Si alloy. Temperature dependence of the impurity diffusion coefficients
of Si in Al, obtained by extrapolation of the concentration dependence of the interdiffusion coeffi-cient to zero mole fraction
of Si, is given by the following equation: DSi/Al = (2.02+0.97
-0.66 × 10-4 exp [-(136 ±3) kJ mol-1/RT] m2/s. p ] The Kirkendall marker was found to move toward the Si-rich side, indicating that the Si atom diffuses faster than
the Al atom in Al-Si alloys. From the interdiffusion coeffi-cient and the marker shift, the intrinsic diffusion coefficients
were calculated.
The difference in the activation energies (ΔQ) between the impurity diffusion of Si in Al and the self-diffusion of Al was
estimated by means of the asymptotic oscillating po-tential and the Le Claire theory. The calculated value of ΔQ is in fair
agreement with the experimental value. The vacancy-solute binding energy for Si in Al was also dis-cussed based on the diffusion
data.
formerly Undergraduate Student, Tohoku University 相似文献
69.
70.
Tsunehiro Aki Yumiko Nagahata Katsuyuki Ishihara Yoshio Tanaka Tsutomu Morinaga Kenichi Higashiyama Kengo Akimoto Shigeaki Fujikawa Seiji Kawamoto Seiko Shigeta Kazuhisa Ono Osamu Suzuki 《Journal of the American Oil Chemists' Society》2001,78(6):599-604
A filamentous fungus producing significant levels of arachidonic acid (AA, C20∶4n−6) was isolated from a freshwater pond sample
and assigned to the species Mortierella alliacea. This strain, YN-15, accumulated AA mainly in the form of triglyceride in its mycelia. An optimized culture in 25 L of medium
containing 12% glucose and 3% yeast extract yielded 46.1 g/L dry cell weight, 19.5 g/L total fatty acid, and 7.1 g/L AA by
7-d cultivation in a 50-L jar fermenter. Assimilation of soluble starch by YN-15 was notably enhanced by the addition of oleic
acid, soybean oil, ammonium sulfate, or potassium phosphate to a starch-based medium. Using starch as a main carbon source
in the pre-pilot scale cultivation improved the production of AA by up to 5.0 g/L. Mortierella alliacea strain YN-15 is therefore a promising fungal isolate for industrial production of AA and other polyunsaturated fatty acids. 相似文献