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Grain size distribution and chemistry of the brackish Lake sediment in Korea
I Chan Shin,Tetsuji Akatsuka,Hisayuki Azumi,Lan Ao,Nozomi Amahashi,Maki Oyagi,Noriko Ishida,Naoshige Goto,Masahiro Maruo,Akihiko Yagi,Yashshi Seike,Seung Hyun Lee,Sung Ae Yoon,Jun Kil Choi,Young Woong 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.5
To determine the grain size distribution and chemical characteristics of bottom surface sediments in shallow brackish lagoons, we studied sediment samples collected from the entire horizontal lake area and in vertical profiles from three stations in Lakes Youngrang and Hwajinpo, on the eastern coast of Korea. Vertical and horizontal grain size distributions of the bottom sediments indicated predominantly sand- and silt in both lakes. The vertical distribution of C/N ratios ranged from 6.14 to 11.92 in Lake Youngrang, and 6.74 to 12.34 in Lake Hwajinpo. The horizontal distribution of C/N ratios in Lake Youngrang ranged from 6.1 to 17.6, whereas they ranged from 4.4 to 12.1 in Lake Hwajinpo. C/N ratios showed locally different responses to the origin of allochthonous (partial region) and autochthonous (entire region) organic materials. Horizontally, bottom sediment with low δ<SUP>13</SUP>C and high δ<SUP>15</SUP>N in Lake Youngrang were likely to be influenced by autochthonous organic material derived from primary production, and would be affected by N inputs from sources. In contrast, high δ<SUP>13</SUP>C and low δ<SUP>15</SUP>N sediments in Lake Hwajinpo were likely to be influenced by cyanobacteria.
Pejchal, Jan,Babin, Vladimir,Beitlerova, Alena,Kucerkova, Romana,Panek, Dalibor,Barta, Jan,Cuba, Vaclav,Yamaji, Akihiro,Kurosawa, Shunsuke,Mihokova, Eva,Ito, Akihiko,Goto, Takashi,Nikl, Martin,Yoshika Elsevier 2016 Optical Materials Vol.53 No.-
<P><B>Abstract</B></P> <P>Ce-doped lutetium aluminum garnet Lu<SUB>3</SUB>Al<SUB>5</SUB>O<SUB>12</SUB> (LuAG) nanoceramics were fabricated at 1600°C and 1700°C by spark-plasma sintering (SPS) method from nano-powders prepared by radiation synthesis. Both undoped and Ce-doped LuAG ceramic samples were also prepared from the nano-powders at 1700°C with significantly increased pre-heating rate. The backscattered electron images revealed large amount of pores in all the Ce-doped samples causing their significant opacity. On the other hand, very large grains and no pores were revealed in the undoped sample, which was the only transparent one. The radioluminescence measurements revealed superior overall scintillation efficiency of the samples sintered at the temperature 1700°C, and their defect emission in the UV region was ascribed to oxygen-vacancy-related defects such as F<SUP>+</SUP> centers. The photoluminescence decay of the defect emission was characterized by an extremely fast decay time of a few nanoseconds. Influence of sintering procedure and subsequent annealing on the luminescence and scintillation properties is discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ce-doped scintillation nanoceramics were prepared by a Spark-Plasma-Sintering method. </LI> <LI> High overall scintillation efficiency was found. </LI> <LI> For samples prepared with slower pre-heating, scintillation efficiency can be increased by annealing. </LI> <LI> Higher sintering temperatures and slower pre-heating stages positively influence scintillation efficiency. </LI> </UL> </P>