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).
Authors:J. M. Hur, S. B. Park, C. S. Seo, K. J. Jung, and S. W. Park
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.
Authors:M. Jung, I. Brizes, S. Wages, P. Ponce, M. Kang, and P.D. Loprinzi
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.
Authors:H. J. Jo, S. M. Lee, H. J. Kim, J. G. Kim, J. S. Choi, Y. K. Park, and J. Jung
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.