Performance and interaction of sodium silicate activated slag with lignosulfonate superplasticiser added at different mixing stages

This paper investigated the effect of adding lignosulfonate (LS) superplasticiser at the different stages of mixing on the workability and rheological behaviour of sodium silicate activated slag (SSAS) in order to find a practically feasible approach to tackling the incompatibility issue between superplasticiser and alkaline activator. In addition to rheology and minislump tests, adsorption, zeta potential and environmental scanning electron microscopy tests were also undertaken to understand the interactions between the lignosulfonate and the fresh SSAS in order to reveal the mechanisms behind the observation. The results show that adding the LS and the activator separately at the different stages of mixing can significantly improve both the initial minislump and 60-min minislump retention due to the increased adsorption of LS and the improved dispersion of slag particles, with the prior addition of LS better than the delayed addition. However, a nonlinear rheological behaviour of SSAS was observed in the LS-superplasticised SSAS under separate addition and, consequently, modified Bingham model was found to be more suitable for describing this kind of rheological behaviour

Effects of Understory Vegetation and Litter on Plant Nitrogen (N), Phosphorus (P), N∶P Ratio and Their Relationships with Growth Rate of Indigenous Seedlings in Subtropical Plantations

Establishing seedlings in subtropical plantations is very important for forest health, succession and management. Information on seedling nutrient concentrations is essential for both the selection of suitable indigenous tree species to accelerate succession of the established plantation and sustainable forest management. In this study, we investigated the concentrations of nitrogen ([N]), phosphorus ([P]), and N∶P ratio in leaves, stems and roots of seedlings of three indigenous tree species (Castanopsis chinensis, Michelia chapensis and Psychotria rubra) transplanted with removing or retaining understory vegetation and litter at two typical subtropical forest plantations (Eucalyptus plantation and native species plantation). We also measured the relative growth rate (RGR) of seedling height, and developed the relationships between RGR and leaf [N], [P] and N∶P ratio. Results showed that treatments of understory vegetation and associated litter (i.e. removal or retained) generally had no significant effects on leaf [N], [P], N∶P ratio and RGR of the transplanted tree seedlings for the experimental period. But among different species, there were significant differences in nutrient concentrations. M. chapensis and P. rubra had higher [N] and [P] compared to C. chinensis. [N] and [P] also varied among different plant tissues with much higher values in leaves than in roots for all indigenous species. RGR of indigenous tree seedlings was mostly positively correlated with leaf [N] and [P], but negatively correlated with leaf N∶P ratio. Considering the low [P] and high N∶P ratio observed in the introduced indigenous tree seedlings, we propose that the current experimental plantations might be P limited for plant growth

Intra-valley Spin-triplet p+ipp+ip Superconducting Pairing in Lightly Doped Graphene

We analyze various possible superconducting pairing states and their relative stabilities in lightly doped graphene. We show that, when inter-sublattice electron-electron attractive interaction dominates and Fermi level is close to Dirac points, the system will favor intra-valley spin-triplet $p+\mathrm{i}p$ pairing state. Based on the novel pairing state, we further propose a scheme for doing topological quantum computation in graphene by engineering local strain fields and external magnetic fields.Comment: 5 pages, 2 figures were updated, 1 table, three references were added, minor revision, close to the published versio

Pharmacological isolation of postsynaptic currents mediated by NR2A- and NR2B-containing NMDA receptors in the anterior cingulate cortex

NMDA receptors (NMDARs) are involved in excitatory synaptic transmission and plasticity associated with a variety of brain functions, from memory formation to chronic pain. Subunit-selective antagonists for NMDARs provide powerful tools to dissect NMDAR functions in neuronal activities. Recently developed antagonist for NR2A-containing receptors, NVP-AAM007, triggered debates on its selectivity and involvement of the NMDAR subunits in bi-directional synaptic plasticity. Here, we re-examined the pharmacological properties of NMDARs in the anterior cingulate cortex (ACC) using NVP-AAM007 as well as ifenprodil, a selective antagonist for NR2B-containing NMDARs. By alternating sequence of drug application and examining different concentrations of NVP-AAM007, we found that the presence of NVP-AAM007 did not significantly affect the effect of ifenprodil on NMDAR-mediated EPSCs. These results suggest that NVP-AAM007 shows great preference for NR2A subunit and could be used as a selective antagonist for NR2A-containing NMDARs in the ACC