The effect of particle size and amount of inoculum on fungal treatment of wheat straw and wood chips

Background： The aim of this study was to optimize the fungal treatment of lignocellulosic biomass by stimulating the colonization. Wheat straw and wood chips were treated with Ceriporiopsis subvermispora and Lentinula edodes with various amounts of colonized millet grains（0.5, 1.5 or 3.0 % per g of wet weight of substrate） added to the substrates. Also, wheat straw and wood chips were chopped to either 0.5 or 2 cm.Effectiveness of the fungal treatment after 0, 2, 4, 6, or 8 wk of incubation was determined by changes in chemical composition, in vitro gas production（IVGP） as a measure for rumen degradability, and ergosterol content as a measure of fungal biomass.Results： Incomplete colonization was observed for C. subvermispora treated wheat straw and L. edodes treated wood chips. The different particle sizes and amounts of inoculum tested, had no significant effects on the chemical composition and the IVGP of C. subvermispora treated wood chips. Particle size did influence L.edodes treatment of wheat straw. The L. edodes treatment of 2 cm wheat straw resulted in a more selective delignification and a higher IVGP than the smaller particles. Addition of 1.5 % or 3 % L. edodes inoculum to wheat straw resulted in more selective delignification and a higher IVGP than addition of 0.5 % inoculum.Conclusion： Particle size and amount of inoculum did not have an effect on C. subvermispora treatment of wood chips. At least 1.5 % L. edodes colonized millet grains should be added to 2 cm wheat straw to result in an increased IVGP and acid detergent lignin（ADL） degradation.

Influence of solute cloud and precipitates on spatiotemporal characteristics of Portevin-Le Chatelier effect in A2024 aluminum alloys

In this paper, solute concentration and precipitate content in A2024 aluminum alloy are adjusted by solution treatment （ST） at different temperatures and tensile experiments on these treated specimens are carried out. It is found that the temperature of solution treatment （ST temperature） has a remarkable influence on the amplitude of the serrated flow and the propagation characteristics of shear bands. These results are due to the effects of solute atoms and precipitates on dynamic strain aging （DSA）. When ST temperature is higher than 300 ℃, solute concentration is relatively high and solute cloud is a key factor of DSA. When ST temperature is lower than 300 ℃, precipitate content is relatively high and the mechanism of DSA is determined by precipitates.

Kinetics of chemical leaching of chalcopyrite from low grade copper ore: behavior of different size fractions

The kinetics of the chemical leaching of copper from low grade ore in ferric sulfate media was investigated using the constrained least square optimization technique. The experiments were carried out for different particle sizes in both the reactor and column at constant oxidation-reduction potential （Eh）, pH values, and temperature. The main copper mineral was chalcopyrite. About 40% of Cu recovery is obtained after 7 d of reactor leaching at 85℃ using -0.5 mm size fraction, while the same recovery is obtained at 75℃ after 24 d. Also, about 23% of Cu recovery is obtained after 60 d of column leaching for ＋4--8 mm size fraction whereas the Cu recovery is as low as about 15% for ＋8--12.7 and ＋12.7--25 mm size fractions. A 4-stage model for chalcopyrite dissolution was used to explain the observed dissolution behaviors. The results show that thick over-layers of sulphur components cause the parabolic behavior of chalcopyrite dissolution and the precipitation of Fe3＋ plays the main role in chalcopyrite passivation. In the case of coarse particles, transformation from one stage to another takes a longer time, thus only two stages including the initial reaction on fresh surfaces and S0 deposition are observed.