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  • Author or Editor: M. Jung x
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Summary  

We introduce a new characterization of linear isometries. More precisely, we prove that if a one-to-one mapping f:ℝn→ℝn(2≦n<∞) maps every regular pentagon of side length a> 0 onto a pentagon with side length b> 0, then there exists a linear isometry I :ℝn→ℝnup to translation such that f(x) = (b/a) I(x).

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Abstract  

Radiation treatment in the presence of catalysts such as anatase, P25 and bentonite showed efficient removal of TCE (trichloroethylene) and PCE (perchloroethylene) compared with gamma-irradiation alone. Gamma-ray pretreatment of P25 and bentonite enhanced the decomposition of TCE and PCE, respectively. The change in the catalysts by gamma-rays was characterized by their EPR spectra. For anatase and bentonite, the peaks in the spectra increased significantly, and the pattern of the spectra changed in the case of P25. The relationship between the peaks and pollutant decomposition should be further clarified due to the complexity of the spectra.

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Abstract  

Gamma-ray treatment in the presence of ozone (O3) and titanium dioxide (TiO2) showed an efficient removal of trichloroethylene (TCE) and perchloroethylene (PCE). Without gamma-irradiation, TCE and PCE were not sufficiently decomposed to comply with the water quality limit of groundwater. However, near 100% of TCE and PCE were removed at a dose of 300 Gy in the presence of O3 and TiO2, where TiO2 showed an explicit enhancement of decomposition. Cytotoxicity test using Chinese hamster V79 cells showed no toxicity of the TCE and PCE decomposition products.

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Abstract  

Carbonate ions significantly inhibit the decomposition of TCE (trichloroethylene) and PCE (perchloroethylene) by gamma-rays. The inhibition effect is larger in the case of TCE than PCE due to a greater dependence of TCE decomposition on hydroxyl radicals. The inhibition effect of carbonate ions was characterized by an EPR/spin-trapping technique. The intensity of DMPO-OH adduct signal decreased as the carbonate ion concentration increased and the percent of signal reduction was linearly proportional to the logarithm of carbonate ion concentration. This directly proves that the carbonate ions inhibit the decomposition of TCE and PCE by scavenging hydroxyl radicals.

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Abstract  

A pilot plant was developed for the reclamation and reuse of secondary effluent from a sewage treatment plant. The plant system consists of sand filtration, gamma-irradiation, ozonation and ion-exchange. Gamma-irradiation showed effective organic contaminant decomposition and this resulted in the reduction of 5-day biochemical oxygen demand (BOD5), color, chemical oxygen demand (CODCr) and total organic carbon (TOC). Ion-exchange significantly removed inorganic ions, and thus reduced total nitrogen (TN) and total phosphorus (TP). The average reduction in color, CODCr, BOD5, TOC, TN and TP, which was obtained after 12 operations, was 64, 52, 67, 61, 95 and 92%, respectively. Irrespective of applied radiation dose, the treated water fully satisfied the quality requirements of household water that can be used for all home uses except for drinking and human contact uses.

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Authors: M. Jung, I. Brizes, S. Wages, P. Ponce, M. Kang and P.D. Loprinzi

Abstract

No previous studies have evaluated the potential combined effects of acute exercise and acute hypoxia exposure on memory function, which was the purpose of this study. Twenty-five participants (Mage = 21.2 years) completed two laboratory visits in a counterbalanced order, involving 1) acute exercise (a 20-min bout of moderate-intensity exercise) and then 30 min of exposure to hypoxia (FIO2 = 0.12), and 2) exposure to hypoxia alone (FIO2 = 0.12) for 30 min. Following this, participants completed a cued-recall and memory interference task (AB/AC paradigm), assessing cued-recall memory (recall 1 and recall 2) and memory interference (proactive and retroactive interference). For cued-recall memory, we observed a significant main effect for condition, with Exercise + Hypoxia condition having significantly greater cued-recall performance than Hypoxia alone. Memory interference did not differ as a function of the experimental condition. This experiment demonstrates that engaging in an acute bout of exercise prior to acute hypoxia exposure had an additive effect in enhancing cued-recall memory performance.

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Abstract  

Hydrogen gas (H2) was produced by gamma-irradiation of pure water in the presence of various TiO2 catalysts. Most catalysts used in this work largely enhanced the radiolytic decomposition of water and subsequent production of H2. The different activity of catalysts was characterized by X-ray diffraction (XRD) patterns and by electron paramagnetic resonance (EPR) spectra. The addition of methanol as a sacrificing agent further increased the H2 production by scavenging hydroxyl radicals and the scavenging activity was directly identified using an EPR/spin-trapping technique. Among the catalysts studied, nanosized TiO2 (nTiO2) showed an excellent activity in the production of H2. Furthermore, the addition of EDTA instead of methanol largely increased the H2 production. This is quite promising since waste compounds such as EDTA can be removed with concomitant H2 production

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Authors: J. M. Hur, S. B. Park, C. S. Seo, K. J. Jung and S. W. Park

Summary  

The electrochemical reduction of uranium oxide in the treatment of spent nuclear fuel requires a characterization of the LiCl-Li2O salt used as a reaction medium. Physical properties, melting and vaporization are important for the application of the salt and thus they have been investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG), respectively. Experimental data suggest LiCl and Li2O compound formations, leading to a melting point depression of the LiCl and a co-vaporization of the LiCl-Li2O salt.

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Authors: Robert Vajtai, Sujit K. Biswas, Binqing Wei, Gouwen Meng, Yung Joon Jung and Pulickel M. Ajayan

Single and multiwalled carbon nanotubes have attracted significant interest due to their one-dimensional structure and unique electrical and mechanical properties. Among the wide variety of their potential applications most importantly they offer potential to serve as building blocks for future electronic device architectures [1, 2, 3, 4, 5, 6]. Carbon nanotubes may serve as active or passive electronic elements; and as passive elements they may serve as interconnects both on short and long ranges [7, 8]. The most essential prerequisite for realizing CNT architectures is to be able to grow nanotubes at controlled sites, in predetermined orientations and to form interconnections. Significant progresses in growing aligned carbon nanotube films have been made recently with a combined approach of the floating catalyst method using pre-patterned templates and chemical vapor deposition (CVD) [9, 10, 11, 12]. Recently we summarized our work on growing architectures of carbon nanotubes, which might be integrated into microelectronic circuits [13]. While the predefined growth of the above mentioned large nanotube structures is important and receives a lot of attention characterization of the product also deserves similarly high attention being a key for future applications and giving the real importance and purpose of the growth efforts. In this paper, we report some of our works, which are directed towards electrical tests on CNTs, namely high current carrying capacity; vertically organized multiwalled nanotubes showing the possible usage of highly ordered and well-shaped tubes; and characterization of singlewalled nanotube junctions.

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Authors: H. J. Jo, S. M. Lee, H. J. Kim, J. G. Kim, J. S. Choi, Y. K. Park and J. Jung

Summary  

In order to evaluate the use of gamma-ray treatment as a pretreatment to conventional biological methods, the effects of gamma-irradiation on biodegradability (BOD5/COD) of textile and pulp wastewaters were investigated. For all wastewaters studied in this work, the efficiency of treatment based on TOC removal was insignificant even at an absorbed dose of 20 kGy. However, the change of biodegradability was noticeable and largely dependent on the chemical property of wastewaters and the absorbed dose of gamma-rays. For textile wastewaters, gamma-ray treatment increased the biodegradability of desizing effluent due to degradation of polymeric sizing agents such as polyvinyl alcohol. Interestingly, the weight-loss showed the highest value of 0.97 at a relatively low dose of 1 kGy. This may be caused by the degradation of less biodegradable ethylene glycol prior to terephthalic acid decomposition. For pulp wastewater, the gamma-ray treatment did not improve the biodegradability of cooking and bleaching of C/D effluents. However, the biodegradability of bleaching E1 and final effluents was abruptly increased up to 5 kGy then slowly decreased as the absorbed dose was increased. The initial increase of biodegradability may be induced by the decomposition of refractory organic compounds such as chlorophenols, which are known to be the main components of bleaching C/D and final effluents.

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