Conductivity Prediction Method of Carbon Nanotube Resin Composites Considering the Quantum Tunnelling Effect.

Understanding and predicting the conductivity of carbon nanotube resin composites are essential for structural health detection and monitoring applications. Due to the complexity in the composition of carbon nanotube resin composites, it is of practical significance to develop a method for predicting the conductivity with a view to design and making of the composite. In this paper, the influence of carbon nanotube tunnelling on the conductivity was investigated thoroughly, where the tunnelling conductivity effect is considered as an independent conductive phase. Then, the effective medium model and the Hashin-Shtrikman (H-S) boundary model are used to predict the conductivity of carbon nanotube resin composites. The results presented in this paper show that the developed method can reduce the prediction range of the H-S boundary model and improve the prediction accuracy of the lower bound of the H-S boundary model. The results also show that the tunnelling has little effect on conductivity prediction based on the effective medium model. Based on the results, the effects of nanotube conductivity, the aspect ratio and the barrier height on the prediction of the effective conductivity are discussed to provide a guidance for the design and making of the composites.

[Effects of acidification and liming on organic matter leaching in forest soil].

The potential effects of acidification and liming on the dynamics of carbon pool in forest soil were studied through field experiments at Tieshanping, Chongqing in Southwest China. The changes of dissolved organic matter (DOM) concentration in soil water in different layers within three years after application of limestone or magnesite indicated that soil remediation had leaded to significant decrease of DOM in soil water from mineral layers [e.g., DOC concentration in the upper layer decreased from (20.32 +/- 3.19) mg x L(-1) in the reference plots to (15.69 +/- 2.39) mg x L(-1) in limestone plots and (11.44 +/- 1.87) mg x L(-1) in magnesite ones] as probably the results of increasing pH value and decreasing ion strength, although the DOM leaching from the litter layer was found increasing, especially in the first half year. Consequently, liming may not in longterm accelerate the transport of soil organic mater downward from the litter layer to the mineral layer, but prevent the acidified soil from DOM-leaching and thus carbon-pool losing.

[Contribution of simulated nitrogen deposition to forest soil acidification in area with high sulfur deposition].

The impacts of nitrogen deposition on a typical acidified soil under a masson pine (Pinus massoniana) forest at Tieshanping, Chongqing in Southwest China was studied through field experiments. The changes of soil water chemistry in different layers within one year after the spray of NH4NO3 and NaNO3 solution respectively [with the same nitrogen dose of 40 kg x (hm2 x a)(-1)] indicated that although the pH value decreased a little (treated by NH4NO3) or even increased somewhat (treated by NaNO3), the concentration of base cations, i.e. Ca2+ and Mg2+, and Al3+ increased remarkably, with the Al3+ to base cation (sum of Ca2+, Mg2+ and K+) molar ratio increased from 0.5 of the reference to around or even higher than 1.0, which means Al3+ might do harm to the vegetation. The enhanced leaching of base cations and activation of toxic Al3+ both indicated the deterioration of soil acidification. In addition, the nitrogen saturation occurred with the increasing NO3- leaching. Since it was detected that NH4+ had more effect on soil acidification and eutrophication than NO3- with the same equivalence, ammonia (NH3) emission abatement should be possibly preferred to nitrogen oxides (NO(x)) for nitrogen deposition control in China.

[Effect of limestone and magnesite application on remediation of acidified forest soil in Chongqing, China].

Effect of limestone and magnesite application on remediation of a typical acidified soil under a masson pine (Pinus massoniana) forest at Tieshanping, Chongqing in southwest China was studied through field experiments. The changes of soil water chemistry in different layers within one year after application of limestone or magnesite indicated that the remediation agents leaded to the recovery of acidified soil by significant increase of pH value and concentration of relative cation, i.e., Ca2+ or Mg2+, and notable decrease of inorganic monomeric aluminum (Ali). However, the accelerated leaching of NO3- and SO4(2-) might somewhat counteract the positive effects. Since the limestone powder applied was much finer and thus more soluble than the magnesite powder, it seemed that the addition of limestone was more effective than that of magnesite. However, the application of magnesite could probably improve the nutrient uptake and growth of plant, and thus limestone and magnesite should be used together. The change of soil water chemistry was much more notable in upper layer of soil than lower, which means that it will take long time to achieve the whole profile soil remediation.