93,490 research outputs found
Identifying pollution sources of sediment in Lake Jangseong, Republic of Korea, through an extensive survey: Internal disturbances of past aquaculture sedimentation
No full textLake sediments are important sinks of various pollutants and preserve historical pollution records caused by anthropogenic activities. Recently, the sediments of Lake Jangseong, South Korea were first detected with high concentrations of organic matter (ignition loss [IL]; total organic carbon [TOC]), nutrients (total nitrogen [TN]; total phosphorus [TP]), and some heavy metals (Zn, Cu, Cd, and Hg). Here, we identified the origins of these concentrations accumulated in the sediments using extensive surveys and various assessments. Sediment pollution assessed by sediment quality guidelines, pollution load index, and potential ecological risk index was found to be of serious concern for IL, TN, TP, and Cd. Thus, we assessed pollution sources through spatial, grid, and vertical distributions and found that the high pollutant concentrations detected in 2020 were confirmed only at a certain location in the lake. Additionally, similar results were detected in the sedimentary layer below a sediment core at a depth of 15.0 cm. The high pollutant concentrations locally occurred around a “hotspot” site that was previously frequently used for aquaculture activities, indicating that the pollutants were accumulated in sediments owing to past cage fish farming rather than from influx of externally sourced pollution. Furthermore, chemical fractionation of phosphorus and heavy metals and assessment of stable isotopes (13C and 15N) of organic matter suggested that the pollutants in the sediments at the “hotspot” sites had different origins than those found at other sites. Accordingly, the by-products discharged after cage fish farming, such as residual feed, fish meal, and waste, accumulated in the sediments and were then exposed to natural internal disturbances caused by the effects of climate change-induced drought. This local distribution and the phosphorus and heavy metal chemical fraction results with low elution potential indicated that the pollutants in the sediments of Lake Jangseong had negligible impact on water quality.11Nsciescopu
Statistical sensitivity estimates for oscillating electric dipole moment measurements in storage rings
Full text linkIn this paper analytical expressions are derived to describe the spin motion of a particle in magnetic and electric fields in the presence of an axion field causing an oscillating electric dipole moment (EDM). These equations are used to estimate statistical sensitivities for axion searches at storage rings. The estimates obtained from the analytic expressions are compared to numerical estimates from simulations in Chang et al. (Phys Rev D 99(8):083002, 2019). A good agreement is found. © The Author(s) 202
In situ Target Strength versus Fork Length Relations of Trachurus Japonicus Extracted from a Set of Acoustic and Corresponding Length Surveys Dat
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Fabrication of plastic microlens array using gas-assisted micro-hot-embossing with a silicon mold
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Rh-Catalyzed one-pot and practical transformation of aldoximes to amides
No full textWilkinson's complex has been found to catalyze the one-pot transformation of aldoximes to the corresponding amides with high selectivity and efficiency under essentially neutral conditions
Chao Yuen Ren (1892–1982)
No full textY. R. Chao is easily the most famous linguist to have come out of China. Born before the end of the last dynasty in China, he received a traditional Confucian education, but was also one of the first Chinese people to be sent to the West for training in modern Western science (under the Boxer Indemnity Fund). The remarkable breadth and scope of his studies included physics, mathematics, linguistics, musical and literary composition, and translation, and he was a pioneer in many of these fields
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