We demonstrate low-temperature growth and direct transfer of graphene-graphitic carbon films (G-GC) onto plastic substrates without the use of supporting materials. In this approach, G-GC films were synthesized on copper layers by using inductively coupled plasma enhanced chemical vapor deposition, enabling the growth of few-layer graphene (G) on top of Cu and the additional growth of graphitic carbon (GC) films above the graphene layer at temperatures as low as 300 °C. The patterned G-GC films are not easily damaged or detached from the polymer substrates during the wet etching and transfer process because of the van der Waals forces and π-π interactions between the films and the substrates. Raman spectroscopy reveals the two-dimensional hexagonal lattice of carbon atoms and the crystallinity of the G-GC films. The optical transparency and sheet resistance of the G-GC films are controlled by modulating the film thickness. Strain sensors are successfully fabricated on plastic substrates, and their resistance modulation at different strains is investigated.
We investigated the characteristics of metal(loid) transport and dispersion in agricultural soils near an abandoned metal mine. Topsoil samples were collected from 162 sampling sites in the study area, including 1 in the mine tailing dumps, to analyze the total concentrations of As, Pb, Cd, and Zn. Subsequently, the metal(loid) transport and dispersion characteristics were investigated using geographic information system (GIS) technology. The results of this study clearly demonstrated the variation in the dispersal of As, Cd, Pb, and Zn from the mine tailing dumps to nearby agricultural soils and the element-specific spatial variability in their respective transport and dispersion characteristics. These findings suggested that compared with the migration behavior of Cd, Pb, and Zn, that of As has a farther-reaching impact on agricultural soils owing to its geochemical cycling in the soil and groundwater environment. This impact differed significantly in magnitude from that of the other investigated metals. Therefore, special consideration must be given to the migration behavior of As.
Pedotransfer functions (PTFs) were developed for each soil horizon to estimate hydraulic characteristics of mountainous forest soils in South Korea. Twenty one dominant soil series from 8 soil catenae such as granite-originated catena and volcanic ash-originated catena were selected for the study; gravel contents of selected soils were 10% or lower. Saturated conductivity (Ks) was measured for each horizon in situ. Particle size distribution and organic matter content of each horizon were also determined. Based on correlation analysis with total data set, sand separate showed positive relationship with Ks (r=0.24*) while clay separate had negative relationship with Ks (r=-0.29**). The correlation coefficients of sand, clay, and organic matter content with Ks increased to 0.41**, -0.67***, and 0.58***, respectively, using data from granite-or gneiss-originated catena with exception of volcanic ash-originated catena and sedimentary rock-originated catena. Determination coefficients of PTFs were 0.31 for A horizon, 0.25 for B, and 0.35 for C with all data set while those were 0.74 for A, 0.48 for B, and 0.54 for C. Organic matter was a dominant factor affecting Ks in A horizon but clay content was selected as the only factor influencing Ks in C horizon. It implies that PTFs should be developed with understanding characteristics of parent materials and horizons. Developed PTFs for granite-or gneiss-originated catena were following: A horizon: Log (K s x 10 7 ) = -0.031C + 0.398OM + 3.49 B horizon: Log (K s x 10 7 ) = -0.028C + 0.141OM + 4.05 C horizon: Log (K s x 10 7 ) = -0.072C + 4.66where C is clay separate (%) and OM is organic matter content (g kg -1 ). The unit of Ks is cm sec -1 .
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