Thermal currents obtained and mutually switched by a modified Haldane model in graphene

By using the transfer matrix method,we discover three types of current,such as the 100%spinvalley polarized current,pure spin-valley current and pure charge current,in a two-terminal graphene system.These types of current can be obtained and mutually switched by modulating the parameters of the modified Haldane model(MHM).In our work,these types of current are driven by the thermal bias.Compared with this method of increasing the one-lead temperature(with a fixed temperature difference),the thermal currents can be more effectively strengthened by increasing the temperature difference(with a fixed one-lead temperature).In order to rapidly turn off these currents,we choose to enhance the intensity of the off-resonant circularly polarized light instead of canceling the temperature difference.These results indicate that the graphene system with the MHM has promising applications in the spin and valley caloritronics.

Dynamics and Hopf Bifurcation Analysis of a Chemostat Model with Modified Growth Rate and Variable Yield Coefficient

The objective of this study is to analyze a chemostat model of very simple type with the Haldane expression of growth rate and a variable yield coefficient. The proposed modified model is analyzed qualitatively and quantitatively. Analytic conditions for stability and optimality are determined for washout and no washout equilibrium solutions. One of the main focuses of the study is to determine parameter values for which Hopf Bifurcations occur in a bioreactor. It has been shown that the maximum stable non-washout equilibrium exits at a residence time under suitable parameter values. Hopf bifurcation is observed at three different conditions of the parameters.

Observation of antichiral edge states in a circuit lattice

We construct an electrical circuit to realize a modified Haldane lattice exhibiting the phenomenon of antichiral edge states. The circuit consists of a network of inductors and capacitors with interconnections reproducing the effects of a magnetic vector potential. The next nearest neighbor hoppings are configured differently from the standard Haldane model, and as predicted by earlier theoretical studies, this gives rise to antichiral edge states that propagate in the same direction on opposite edges and coexist with bulk states at the same frequency. Using pickup coils to measure voltage distributions in the circuit, we experimentally verify the key features of the antichiral edge states, including their group velocities and ability to propagate consistently in a M?bius strip configuration.

Performance,microbial community and inhibition kinetics of long-term Cu2+ stress on an air-lift nitritation reactor with self-recirculation

Biological nitrogen removal process could be affected due to the presence of heavy metals owing to their toxicity and accumulation in the sludge.In this study,the impact of Cu2+shock on a long-term nitritation operation was investigated in an air-lift reactor with selfrecirculation.Both the dynamics of microbial community and inhibition kinetics under Cu2+stress were ascertained.The results showed that Cu2+exerted severe inhibition on nitritation performance of an air-lift reactor(ALR)at 25 mg/L.The corresponding NH4+-N removal efficiency decreased to below 50%,which was mainly due to the variation of microbial community structure,especially the inhibition of nitrifiers like Nitrosomonas(the relative abundance decreased from 30%to 1%after Cu2+inhibition).Kinetic parameters were obtained and compared after fitting the Haldane model.The long-term Cu2+stress on the ALR aggravated the ammonium affinity and the resistance to substrate self-inhibition of the nitritation sludge,but reduced the resistance to Cu2+inhibition.Furthermore,Cu2+acted as uncompetitive inhibitor on nitritation process.Our results provide new insights into the nitritation characteristics under long-term Cu2+stress.