Background and aims Biochar has attracted research interest due to its ability to increase the soil carbon pool and improve crop productivity. The objective of this study was to evaluate the metal immobilizing impact of chicken manure-and green waste-derived biochars, and their effectiveness in promoting plant growth. Methods The immobilization and phytoavailability of Cd, Cu and Pb was examined using naturally contaminated shooting range and spiked soils. Biochar samples prepared from chicken manure and green waste were used as soil amendments. Results Application of biochar significantly reduced NH 4 NO 3 extractable Cd, Cu and Pb concentrations of soils, indicating the immobilization of these metals. Chicken manure-derived biochar increased plant dry biomass by 353 and 572% for shoot and root, respectively with 1% of biochar addition. This might be attributed to reduced toxicity of metals and increased availability of nutrients such as P and K. Both biochars significantly reduced Cd, Cu and Pb accumulation by Indian mustard (Brassica juncea), and the reduction increased with increasing amount of biochar application except Cu concentration. Metal sequential fractionation data indicated that biochar treatments substantially modified the partitioning of Cd, Cu and Pb from the easily exchangeable phase to less bioavailable organic bound fraction.Conclusions The results clearly showed that biochar application was effective in metal immobilization, thereby reducing the bioavailability and phytotoxicity of heavy metals.

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We observe a significant splitting of a surface band on W(llO), while the analogous band on Mo(llO) is split to a much smaller extent. We conclude that this splitting is due to the spin-orbit interaction, similar to that recently proposed for Au(111). A smooth evolution of the magnitude of the splitting as monovalent atoms are adsorbed is attributed to increased surface localization of the wave function and to the altered potential gradient at the interface. We propose a spin ordering of the associated Fermi contours which has important implications for the electronic and spin excitations at this and closely related surfaces.

We report on a gate-recessed AlGaN/GaN highelectron mobility transistor (HEMT) on a SiC substrate with a record power-gain cutoff frequency (f max). To achieve this high f max , we combined a low-damage gate-recess technology, scaled device geometry, and recessed source/drain ohmic contacts to simultaneously enable minimum short-channel effects (i.e., high output resistance R ds) and very low parasitic resistances. A 60-nm-gate-length HEMT with recessed AlGaN barrier exhibited excellent R ds of 95.7 Ω • mm, R on of 1.1 ∼ 1.2 Ω • mm, and f max of 300 GHz, with a breakdown voltage of ∼20 V. To the authors' knowledge, the obtained f max is the highest reported to date for any nitride transistor. The accuracy of the f max value is verified by small signal modeling based on carefully extracted S-parameters.

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