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121.
J. M. Lo C. L. Tseng S. J. Yeh 《Journal of Radioanalytical and Nuclear Chemistry》1988,123(2):683-693
We have recently developed a new method of measuring the initial51Cr(III) produced from nuclear recoil of K2CrO4. In our method, K2CrO4 was mixed with MgO in the presence of a small amount of water, and the mixture was irradiated in a nuclear reactor. After irradiation, the mixture was dissolved in water, and MgO precipitate was separated from the solution. The yield of recoil51Cr(III) could be calculated from the51Cr activity in the precipitate measured. On the other hand, the yield of retention of51Cr as chromate could be calcualted from the activity found in the supernatant. The51Cr(III) yield thus obtained is almost a factor of 2 higher than observed in pure K2CrO4 without mixing with MgO, irradiated under the same condition. Another important observation is that the51Cr(III) yield is independent of irradiation time in the presence of MgO. Without MgO, the observed51Cr(III) yield decreases with increasing irradiation time, suggesting possible oxidation of Cr(III) to chromate during irradiation. This variation is not observed in the system of K2CrO4 containing MgO, indicating that the initial Cr(III) is adsorbed immediately after nuclear recoil by MgO and is protected from oxidation by gamma radiation. 相似文献
122.
Yao-Hsuan Tseng Hong-Ying Lin Chien-Sheng Kuo Yuan-Yao Li Chin-Pao Huang 《Reaction Kinetics and Catalysis Letters》2006,89(1):63-69
Summary Thermostability of P25 nanoparticle was carried out by ascending thermal annealing. The growth of particle was observed and
the activation energy of phase transition was calculated. The photocatalytic reactivity was measured in terms of the degradation
rate of methylene blue. Results indicated that the specific surface area and the aggregation of TiO2 are much important factors than the crystal phase on the photo-decoloration reaction. 相似文献
123.
In this paper a parallel algorithm to solve the stable marriage problem is given. The worst case performance of this algorithm is stated. A theoretical analysis shows that the probability of the occurrence of this worst case is extremely small. For instance, if there are sixteen men and sixteen women involved, then the probability that the worst case occurs is only 10–45. Possible future research is also discussed in this paper. 相似文献
124.
M. H. Yang P. Y. Chen C. L. Tseng S. J. Yeh P. S. Weng 《Journal of Radioanalytical and Nuclear Chemistry》1977,37(2):801-811
Dinonylnaphthalene sulfonic acid (HD) has been used as a preconcentrating agent to enrich trace metal ions and to separate
the interfering elements such as Na, K, Cl and Br which normally exist in the natural aqueous systems. Experiments were performed
by extracting the ions in the aqueous medium with HD in n-hexane and subsequently back-extracted into a minimal volume of
acid solution. Factors influencing the extraction efficiency of the ions of interest were investigated. The preconcentration
technique developed in this study was applied to the determination of trace elements in biological and natural water samples
by neutron activation analysis. 相似文献
125.
C L Tseng 《Radioisotopes》1976,25(9):523-526
This paper deals with a convenient method in the determination of trace amounts of mercury in water. After being irradiated with neutrons, water sample was treated with 7.0M HCIO4 solution and mercury was extracted with lubricating base oil. In such a simple operation, the sensitivity can reach 10(-8)g Hg/4ml H2O. 相似文献
126.
127.
Both exact and approximate analytical solutions of the Poisson-Boltzmann equation for two planar, parallel surfaces are derived for the case when a dispersion medium contains counterions only, and the results obtained are used to evaluate the critical coagulation concentration of a spherical dispersion. A correction factor, which is a function of the valence of counterions, the surface potential of a particle, and the potential on the midplane between two particles at the onset of coagulation, is derived to modify the classic Schulze-Hardy rule for the dependence of the critical coagulation concentration on the valence of counterions. The correction factor is found to increase with the increase in the valence of counterions and/or with the increase in the surface potential. However, it approaches a constant value of 0.8390 if the surface potential is sufficiently high. 相似文献
128.
[reaction: see text] The first highly enantioselective organocatalyzed carbo [3 + 3] cascade cycloaddition of alpha,beta-unsaturated aldehydes is reported. Using this methodology, crotonaldehyde is converted to 6-hydroxy-4-methylcyclohex-1-enecarbaldehyde, which is used in the synthesis of (-)-isopulegol hydrate, (-)-cubebaol, and p-tolualdehyde as well as (-)-6-hydroxy-4-methyl-1-cyclohexene-1-methanol acetate, an intermediate in the total synthesis of lycopodium alkaloid magellanine. Other alpha,beta-unsaturated aldehydes give rise to chiral cyclohexadienes via formal [4 + 2] reactions. 相似文献
129.
F T Tseng J N D Gupta E F StaffordJr 《The Journal of the Operational Research Society》2006,57(5):541-551
This paper considers the permutation flowshop scheduling problem with sequence-dependent set-up times and develops a penalty-based heuristic algorithm to find an approximately minimum makespan schedule. The proposed algorithm determines the penalty in time associated with a particular sequence and selects the sequence with the minimum time penalty as the best heuristic solution. Computational results comparing the effectiveness and efficiency of the proposed penalty-based heuristic algorithm with an existing savings index heuristic algorithm are reported and discussed. 相似文献
130.
Hikosaka Y Fushitani M Matsuda A Tseng CM Hishikawa A Shigemasa E Nagasono M Tono K Togashi T Ohashi H Kimura H Senba Y Yabashi M Ishikawa T 《Physical review letters》2010,105(13):133001
Photoelectron spectroscopy has been performed to study the multiphoton double ionization of Ar in an intense extreme ultraviolet laser field (hν ~ 21 eV, ~ 5 TW/cm2), by using a free electron laser (FEL). Three distinct peaks identified in the observed photoelectron spectra clearly show that the double ionization proceeds sequentially via the formation of Ar(+): Ar+hν→Ar (+) + e? and Ar2(+) + 2hν→Ar(+) + e?. Shot-by-shot recording of the photoelectron spectra allows simultaneous monitoring of FEL spectrum and the multiphoton process for each FEL pulse, revealing that the two-photon ionization from Ar(+) is significantly enhanced by intermediate resonances in Ar(+). 相似文献