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81.
Homologous recombination (HR) is thought to be important for the repair of stalled replication forks in hyperthermophilic archaea. Previous biochemical studies identified two branch migration helicases (Hjm and PINA) and two Holliday junction (HJ) resolvases (Hjc and Hje) as HJ-processing proteins; however, due to the lack of genetic evidence, it is still unclear whether these proteins are actually involved in HR in vivo and how their functional relation is associated with the process. To address the above questions, we constructed hjc-, hje-, hjm-, and pina single-knockout strains and double-knockout strains of the thermophilic crenarchaeon Sulfolobus acidocaldarius and characterized the mutant phenotypes. Notably, we succeeded in isolating the hjm- and/or pina-deleted strains, suggesting that the functions of Hjm and PINA are not essential for cellular growth in this archaeon, as they were previously thought to be essential. Growth retardation in Δpina was observed at low temperatures (cold sensitivity). When deletion of the HJ resolvase genes was combined, Δpina Δhjc and Δpina Δhje exhibited severe cold sensitivity. Δhjm exhibited severe sensitivity to interstrand crosslinkers, suggesting that Hjm is involved in repairing stalled replication forks, as previously demonstrated in euryarchaea. Our findings suggest that the function of PINA and HJ resolvases is functionally related at lower temperatures to support robust cellular growth, and Hjm is important for the repair of stalled replication forks in vivo. 相似文献
82.
Volatiles were extracted from rice plants of various growth stages with solid-phase microextraction (SPME) and analyzed by
gas chromatography-mass spectrometry (GC-MS) to identify attractants that cause invasion of the rice leaf bug Trigonotylus caelestialium (Kirkaldy) into paddy fields. The composition of volatile blends produced by rice plants changed with rice development. In
addition, volatile blend compositions differed between the panicles and the stems and leaves. The relative geranyl acetone
content was high in all plant structures analyzed. In volatiles from whole plants in the fourth-leaf stage and panicles in
the full-ripe stage, the relative content of green leaf volatiles (GLVs) was higher than that found in other rice plant structures.
In contrast, relative terpene levels emitted from whole plants in the panicle-formation stage and by panicles and stems and
leaves in the flowering stage were higher than those of other rice plant structures. However, the type of terpenes found differed
between the panicles and the stems and leaves. Relative levels of β-caryophyllene in whole plants in the panicle-formation
stage and panicles in the flowering stage were much higher than that in stems and leaves in the flowering stage. Our previous
studies demonstrated that the odor from whole plants in the panicle-formation stage and panicles in the flowering stage is
attractive to rice leaf bugs. Here, the attractiveness of β-caryophyllene to adult bugs was investigated in olfactometer assays.
Adult females were attracted to β-caryophyllene at a concentration of 0.001%, which is approximately equivalent to the concentration
produced by flowering rice panicles. However, β-caryophyllene also was present in the odor of whole plants in the fourth-leaf
stage and in stems and leaves in the flowering stage. Furthermore, the amounts of this compound emitted from these structures
were similar. Therefore, we suggest that the relative abundance of this compound in a volatile blend is important for attractance
of the bugs. 相似文献
83.
Simultaneous determination of five antioxidants in food by HPLC with fluorescence detection 总被引:2,自引:0,他引:2
Oishi M Matsuda T Nojiri S Saito K 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2002,43(2):104-109
An HPLC method with fluorescence detection was developed for the determination of propyl gallate, nordihydroguaiaretic acid, butylated hydroxyanisole (2- and 3-tert-butyl-4-hydroxyanisole), tert-butylhydroquinone and octyl gallate in edible oils and foods. The antioxidants in edible oil were isolated directly with acetonitrile saturated with n-hexane. The antioxidants in food were extracted with ethyl acetate and the extract was concentrated under vacuum. They were isolated from the residue with acetonitrile saturated with n-hexane. The acetonitrile layer was centrifuged at 5,000 rpm for 10 min. The HPLC separation was performed on a Symmetry C18 column (3.5 microns, 4.6 mm i.d. x 150 mm) using a mixture of 5% acetic acid-acetonitrile-methanol (4:3:3, v/v/v) as the mobile phase and monitored by using a fluorescence detector with time programming. Sample peaks were identified by comparison of the fluorescence spectra with those of antioxidant standards. Average recoveries of fortified antioxidants at 100 micrograms/g were 72.1-99.6%. Coefficients of variation were 0.7-7.2%. 相似文献
84.
T. Fujitani T. Matsuda Y. Kushida S. Ogihara T. Uchijima J. Nakamura 《Catalysis Letters》1997,49(3-4):175-179
The effect of ZnO/SiO2 in a physical mixture of Cu/SiO2 and ZnO/SiO2 on methanol synthesis from CO2 and H2 was studied to clarify the role of ZnO in Cu/ZnO-based catalysts. An active Cu/SiO2 was prepared by the following procedure: the Cu/SiO2 and ZnO/SiO2 catalysts with a different SiO2 particle size were mixed and reduced with H2 at 523-723 K, and the Cu/SiO2 was then separated from the mixture using a sieve. The methanol synthesis activity of the Cu/SiO2 catalyst increased with the reduction temperature and was in fairly good agreement with that previously obtained for the
physical mixture of Cu/SiO2 and ZnO/SiO2. These results indicated that the active site for methanol synthesis was created on the Cu/SiO2 upon reduction of the physical mixture with H2. It was also found that ZnO itself had no promotional effect on the methanol synthesis activity except for the role of ZnO
to create the active site. The active site created on the Cu/SiO2 catalyst was found not to promote the formation of formate from CO2 and H2 on the Cu surface based on in situ FT-IR measurements. A special formate species unstable at 523 K with an OCO asymmetric
peak at ~1585 cm-1 was considered to be adsorbed on the active site.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
85.
Kazuhiko Takeuchi Taka-aki Hanaoka Takehiko Matsuzaki Matti Reinikainen Yoshihiro Sugi 《Catalysis Letters》1991,8(2-4):253-261
Vapor phase hydroformylation of ethylene was studied with silica-supported metal catalysts. A cobalt metal catalyst derived from Co2(CO)8 gave propanal and its derivatives in as high selectivity of about 36% as Rh/SiO2 catalyst under the reaction conditions of 1.1 MPa of a gas-mixture of ArCOC2H4H2 = 1333 at 423–503 K. On the other hand, conventional cobalt catalysts derived from cobalt nitrate, chloride, or acetate, and other noble metal catalysts (Pd/SiO2 and Ir/SiO2) produced mainly ethane. 相似文献
86.
Several methods to determine number-average molecular weight Mn and weight-average molecular weight Mw, of a polymer sample are proposed from diffusion and sedimentation velocity measurements at the θ point. According to these methods, Mn and Mw are determined from the diffusion constant vs. molecular weight relationship, and also from the equations of Svedberg and Flory–Mandelkern, using the 2nd-order and the –2nd-order diffusion constants. These methods have been applied to four samples of polydisperse polystyrene in the θ solvent, cyclohexane at 35°C. It was experimentally ascertained that Mn and Mw of each sample determined by the present methods were in good agreement with the results of column fractionation, light scattering, and calculated values from molecular weight distribution curve within experimental errors. It is concluded that the present methods are useful for determining Mn and Mw, since the reliabilities of Mn and Mw values, which are fundamental quantities of polymer characterization, can be raised by comparing the experimental data observed by conventional methods such as osmotic pressure, light scattering, and the Archibald method with those observed by the present methods. 相似文献
87.
Yoshinori Nishiki Koichi Aoki Koichi Tokuda Hiroaki Matsuda 《Journal of Applied Electrochemistry》1987,17(1):67-76
On the basis of the observation of gas bubbles evolved by electrolysis, a two-dimensional vertical model cell composed of electrodes with open parts for releasing gas bubbles to the back side is proposed. The model cell consists of two layers. One layer forms a bubble curtain with a maximum volume fraction of gas bubbles in the vicinity of the working electrode with open parts. The other. being located out of the bubble layer, is a convection layer with a small volume fraction distributed in the vertical direction under forced convection conditions. The cell resistance and the current distribution were computed by the finite element method when resistivity in the back side varied in the vertical direction along the cell. The following three cases for overpotential were considered: no overpotential, overpotential of the linear type and overpotential of the Butler-Volmer type. It was found that the cell resistance was determined not only by the interelectrode gap but also by the percentage of open area and in some cases by the superficial surface area. The cell resistance varied only slightly with the distribution of the bubble layer in the back side.Nomenclature
b
linear overpotential coefficient given byb=/i
-
C
proportionality constant given by Equation 15
-
d
1
distance between front side of working electrode and separator
-
d
2
thickness of separator
-
F
Faraday constant
-
I
total current per half pitch
-
i
current density at working electrode
-
i
0
exchange current density
-
L
length of a real electrolysis cell
-
n
number of electrons transferred in electrode reaction
-
O
p
percentage of open area given by Equation 1
-
p
pitch, i.e. twice the length of the unit cell, defined by 2(BC) in Fig. 4
-
q
thickness of bubble curtain, defined by (AM) in Fig. 4
-
R
gas constant
-
r
t
total cell resistance
-
r
unit-cell resistance defined by (V – V
eq)/I
-
r
rs
residue ofr from sum ofr
0 andr
-
r
0
ohmic resistance of solution when0
p=0
-
r
resistance due to overpotential when0
p=0
-
s
electrode surface ratio or superficial surface area given by Equation 2 for the present model
-
T
absolute temperature
-
t
thickness of working electrode defined by EF in Fig. 4
-
V
cell voltage
-
V
eq
open circuit potential difference between working and counter electrodes
-
solution velocity in cell
- 0
solution velocity at bottom of cell
-
w
width of working electrode, defined by 2(DE) in Fig. 4
-
x
abscissa located on cell model
-
y
ordinate located on cell model
-
anodic transfer coefficient
-
linear overpotential kinetic parameter defined byb/[bc(p/2)]
- d
infinitesimally small length on the boundary
-
volume fraction of gas bubbles in cell
-
dimensionless cell voltage defined bynF(V – V
eq)/RT
-
overpotential at working electrode
-
Butler-Volmer overpotential kinetic parameter defined by [nFi
0bc(p/2)]/RT
-
coordinate perpendicular to boundary of model cell
- 1
resistivity of bubble-free solution
- 2
resistivity of separator
- bc
resistivity of bubble curtain
-
potential in cell 相似文献
88.
Motohide Matsuda Takushi Hosomi Kenji Murata Takehisa Fukui Michihiro Miyake 《Journal of power sources》2007
Bilayered Y2O3-stabilized ZrO2 (YSZ)/Sm2O3-doped CeO2 (SDC) electrolyte films were successfully fabricated on porous NiO–YSZ composite substrates by electrophoretic deposition (EPD) based on electrophoretic filtration followed by co-firing with the substrates. In EPD, positively charged YSZ and SDC powders were deposited directly on the substrates, layer by layer from ethanol-based suspensions. Delamination between YSZ and SDC films was avoided by reducing the SDC films’ thickness to ca. 1 μm. A single cell was constructed on the bilayered electrolyte films composed of ca. 4 μm-thick YSZ and ca. 1 μm-thick SDC films. As a cathode in the cell, La0.6Sr0.4Co0.2Fe0.8O3−x (LSCF) was used. Maximum output power densities greater than 0.6 W cm−2 were obtained at 700 °C for the bilayered YSZ/SDC electrolyte cells thus constructed. 相似文献
89.
Fa-Hsyang Chen Jim-Long Her Yu-Hsuan Shao Yasuhiro H Matsuda Tung-Ming Pan 《Nanoscale research letters》2013,8(1):18
In this letter, we investigated the structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics on the amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) devices. Compared with the Er2O3 dielectric, the a-IGZO TFT device incorporating an Er2TiO5 gate dielectric exhibited a low threshold voltage of 0.39 V, a high field-effect mobility of 8.8 cm2/Vs, a small subthreshold swing of 143 mV/decade, and a high Ion/Ioff current ratio of 4.23 × 107, presumably because of the reduction in the oxygen vacancies and the formation of the smooth surface roughness as a result of the incorporation of Ti into the Er2TiO5 film. Furthermore, the reliability of voltage stress can be improved using an Er2TiO5 gate dielectric. 相似文献
90.
Effect of treatment of activated carbon fiber cloth electrodes with cold plasma upon performance of electric double-layer capacitors 总被引:4,自引:0,他引:4
Masashi Ishikawa Atsushi Sakamoto Masayuki Monta Yoshiharu Matsuda Koichi Ishida 《Journal of power sources》1996,60(2):233-238
Charge/discharge behavior of electric double-layer capacitors composed of activated carbon fiber cloth (ACFC) electrodes and an organic electrolyte was investigated. The modification of the ACFC electrodes was performed using cold plasma generated in argon-oxygen atmosphere. The effect of the cold plasma treatment of the ACPC electrodes on the capacitor performance was discussed on the basis of the physical and chemical properties of the ACFC surface such as pore radius distribution and surface atom concentration. 相似文献