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101.
Y.?WeiEmail author B.?Fang T.?Arai M.?Kumagai 《Journal of Applied Electrochemistry》2005,35(6):561-566
The electrochemical oxidation behavior of Ce(III) in nitric acid and sulfuric acid media with various concentrations and compositions were investigated by cyclic voltammetry (CV) and potentiostatic electrolysis. In nitric acid media, the peak potential separation for the redox reactions of the Ce(III)/Ce(IV) couple shifted to base side with the increasing concentration of nitric acid from 1 to 6 M. The kinetics of the Ce(III)/Ce(IV) couple is rapid in high concentration nitric acid. The formal potential is independent of both proton and nitrate concentrations while the standard rate constant increases with added protons but is independent of nitrate concentration. Constant-potential electrolysis also shows that a high proton concentration is electrochemically favorable for the electron transfer of the Ce(III)/Ce(IV) couple and for a high Ce(IV) yield in nitric acid media. The current efficiency was ca. 75% for the oxidation process of Ce(III) at 298 K. A Ce(IV) yield of ca. 80% was achieved for the electrolysis of 100 mM Ce(III) in 6 M HNO3 solution. In sulfuric acid media, the peak potential separation for the redox reactions of the Ce(III)/Ce(IV) couple shifted to noble side with rising concentration of sulfuric acid from 0.1 to 2 M and then shifted to base side with further increase in the concentration. A Ce(IV) yield of ca. 95% was achieved for the potentiostatic electrolysis of 100 mM Ce(III) in 3 M H2SO4 solution. 相似文献
102.
A simple and inexpensive calculating device for electrical power and energy of transient electric discharges is described. The calculation is made by multiplication of the voltage and current of the discharge by use of wideband integrated circuits. 相似文献
103.
Seki Y Kandori A Ogata K Miyashita T Kumagai Y Ohnuma M Konaka K Naritomi H 《The Review of scientific instruments》2010,81(9):096103
Magnetoencephalography (MEG) noninvasively measures neuronal activity with high temporal resolution. The aim of this study was to develop a new type of MEG system that can measure bilateral MEG waveforms without a magnetically shielded room, which is an obstacle to reducing both the cost and size of an MEG system. An unshielded bilateral MEG system was developed using four two-dimensional (2D) gradiometers and two symmetric cryostats. The 2D gradiometer, which is based on a low-T(c) superconducting quantum interference device and wire-wound pickup coil detects a magnetic-field gradient in two orthogonal directions, or ?/?x(?(2)B(z)/?z(2)), and reduces environmental magnetic-field noise by more than 50 dB. The cryostats can be symmetrically positioned in three directions: vertical, horizontal, and rotational. This makes it possible to detect bilateral neuronal activity in the cerebral cortex simultaneously. Bilateral auditory-evoked fields (AEF) of 18 elderly subjects were measured in an unshielded hospital environment using the MEG system. As a result, both the ipsilateral and the contralateral AEF component N100m, which is the magnetic counterpart of electric N100 in electroencephalography and appears about 100 ms after the onset of an auditory stimulus, were successfully detected for all the subjects. Moreover, the ipsilateral P50m and the contralateral P50m were also detected for 12 (67%) and 16 (89%) subjects, respectively. Experimental results demonstrate that the unshielded bilateral MEG system can detect MEG waveforms, which are associated with brain dysfunction such as epilepsy, Alzheimer's disease, and Down syndrome. 相似文献
104.
Ni-free 23Cr-1N stainless steel was examined as bipolar plates for proton exchange membrane fuel cells. Corrosion resistance of the 23Cr-1N stainless steel was better relative to 22Cr stainless steel in the simulated cathodic environments. As confirmed by X-ray photoelectron spectroscopy, the polarized 22Cr and 23Cr-1N stainless steels at pH 2.3 presented predominantly chromium oxide in the outer passive layers. At pH 4.3, the passive layer of the polarized 22Cr stainless steel changed to iron oxides dominant. Interestingly, on the other hand, the polarized 23Cr-1N stainless steel preserved chromium oxide rich outer passive layer, which provides good corrosion resistance. As a result, although the initial cell voltage was slightly lower (∼40 mV), the 23Cr-1N stainless steel bipolar plates employing cell showed better cell voltage stability up to 1000 h, compared with the 22Cr stainless steel employing cell. The operation voltage became further higher through a surface modification of the 23Cr-1N stainless steel with TiN nanoparticles. It seems that the corrosion resistive Ni-free 23Cr-1N is possible to apply for bipolar plates of proton exchange membrane fuel cells. 相似文献
105.
Tetsuji Kaneko Norihiko Tanaka Shinichi Ishioka Fujii Kazumi Yuichi Fukaya Katsuhiko Kumagai 《Journal of Nuclear Science and Technology》2019,56(9-10):873-880
ABSTRACTFukushima Daiichi nuclear power plants (1F) were damaged by unprecedented severe accident in the great east Japan earthquake, and seawater and freshwater had been injected as an emergency countermeasure for the core cooling. Although, the primary containment vessel (PCV) was not supposed to be exposed to diluted seawater, the PCV will be exposed to diluted seawater environment until fuel debris removal is completed. Therefore, it is necessary to establish a countermeasure of corrosion for the PCVs made of carbon steel. In this study, the effect of the addition of corrosion inhibitor, which is one of the corrosion countermeasures, was investigated by two types of corrosion tests. As a result of the immersion corrosion test, it was found that any of the three kinds of corrosion inhibitor could suppress corrosion of carbon steel. In addition, as a result of the inhibitor interim addition test, it was found that corrosion of carbon steel covered with corrosion products could be suppressed by optimizing the additive amount of corrosion inhibitor in the cooling water. 相似文献
106.
Takashi Kumagai 《真空研究与实践》2020,32(5):33-37
A new low-temperature scanning tunneling microscopy technique with laser optics allows for optical excitation and spectroscopy at the level of a single atom or molecule. Shape and material of the microscope's tip prove essential for these investigations; thus, the tip is produced with nanoscale precision by Focused Ion-Beam milling. The localized surface plasmon properties of the tips are engineered by altering the tip structures providing spectral tunability. Local optical excitation is performed by a wavelength-tunable laser source. This tip-enhanced resonance Raman spectroscopy provides a new approach for the atomic-scale optical characterization of local electron-phonon coupling and could ultimately lead to new nanoscale optoelectronic devices with exceptional high sensitivity and efficiency. 相似文献
107.
Using C.I. Reactive Yellow 3 as the target compound, the effect of the combined use of ozonation and post-biodegradation on the decrease in dissolved organic carbon (DOC) concentration was investigated, and the synergistic effect (the difference in the amounts of DOC removed by the biological process between solutions with and without ozonation) was estimated. A decrease in DOC concentration was observed during ozonation and ΔO3/ΔDOC was decreased from 16.0 to 5.2 with increasing ozonation time. Moreover, an enhancement of biodegradability was shown. A further decrease in DOC concentration was observed during the biodegradation after ozonation. The total amount of DOC removed by the combined method was increased from 73.6 mg at 30 min to 159.9 mg at 4 h. The synergistic effect was in the range of 22.7 to 39.2 mg. BOD5 was a better indicator of the synergistic effect than BOD5/DOC. 相似文献
108.
Viscoelastic properties of epoxy resin. I. Effect of prepolymer structure on viscoelastic properties
The intermolecular cyclization reaction is investigated in highly crosslinked epoxy systems, where diepoxides with different mobilities between terminal epoxy groups were crosslinked with ethylene diamine. Based on the measured values of the Clash-Berg 10-sec modulus in the rubbery region, the correlation between the mobility and the cyclization reactivity of the diepoxides is discussed. The epoxide with higher mobility is found to have a higher rubbery modulus than that with lower mobility, as was expected. This is tentatively explained by the difference in the reactivity of the formation of the 11-membered ring. Dynamic mechanical measurements were also run on a forced vibration apparatus. The higher β-transition peak of the polymer of bisphenol-A diglycidyl ether was interpreted in terms of its higher free volume as well as lower density and lower glassy modulus. The higher modulus in the glassy region of ethylene glycol diglycidyl ether–ethylenediamine was explained on the basis of hydrogen bonding. 相似文献
109.
A series of Li1–xNaxV3O8 (0相似文献
110.
The effects of sites and plasticity index (Ip) on the inherent strength anisotropy of eleven different clay deposits are quantitatively examined by the unconfined compression test using a small size specimen with a different angle of inclination to the vertical. A new method for a slope stability analysis, taking the effects of the IASIA method (Inherent And Stress Induced Anisotropies) into consideration, is proposed. The applicability of the IASIA method and the optimum embankment design are examined through case histories of embankment failures on soft soils. The undrained strength anisotropy cannot be estimated by parameters such as the Ip value because of the complicated relationship with the factors influencing undrained anisotropic strength. It must be directly measured. The IASIA method was recommended from a study of a failed embankment. The probability of failure (Pf) and consumer's risk (Pc) from half of the unconfined compressive strength (qu/2) were (2.5~25.5)% and (4.7~42.3)% less than those of the Iwai qu/2(IASIA) and Urayasu qu/2(IASIA). Therefore, the design results were underestimated by disregarding strength anisotropies. If, Pf and Pc were considered, the Ct values increased. However, the Pc values drastically decreased to 24.8% from 54.3% concerning the 75-mm sampler and n increased, thus avoiding latent risks. These mean that the IASIA method can be used for optimum embankment design based on performance provisions. 相似文献