Robust room temperature emissions of trion in darkish WSe2 monolayers: effects of dark neutral and charged excitonic states.

Owing to nonzero charge and spin degrees of freedom, trions offer unprecedented tunability and open new paths for applications in devices based on 2D semiconductors. However, in monolayer WSe2, the trion photoluminescence is commonly detected only at low temperatures and vanishes at room temperature, which undermines practical applications. To unveil how to overcome this obstacle, we have developed a comprehensive theory to probe the impact of different excitonic channels on the trion emission in WSe2 monolayers, which combines ab initio tight-binding formalism, Bethe-Salpeter equation and a set of coupled rate equations to describe valley dynamics of excitonic particles. Through a systematic study in which new scattering channels are progressively included, we found that, besides the low electron density, strong many-body correlations between bright and dark excitonic states quenches the trion emission in WSe2. Therefore, the reduction of scatterings from bright to dark states is required to achieve trion emission at room temperature for experimentally accessible carrier concentrations.

Analytical compensation of axisymmetric equilibrium fluxes picked up by locked mode detectors in tokamaks.

In the detection of locked modes using saddle loops, the problem of how to remove the axisymmetric equilibrium flux picked up by the loops has still to be solved. The problem becomes more difficult when there are conductive structures located near the saddle loops. In this paper, we present an analytical model based on lumped eddy current circuits and use it to interpret the measured equilibrium flux and the corresponding eddy current fluxes. Using this model, precise compensation for fluxes induced by the horizontal field coils and the toroidal field coils, with relative errors of less than 1%, has been realized for the saddle loops in the Joint Texas Experimental Tokamak. This paper also presents a new method to compensate for the detection of equilibrium flux by the locked mode detector.

Investigation of giant magnetoconductance in organic devices based on hopping mechanism.

We suggest a spin-dependent hopping mechanism which includes the effect of the external magnetic field as well as hyperfine interaction (HFI) to explain the observed giant magnetoconductance (MC) in non-magnetic organic devices. Based on the extended Marcus theory, we calculate the MC by using the master equation. It is found that a MC value as large as 91% is obtained under a low driving voltage. For suitable parameters, the theoretical results are in good agreement with the experimental data. Influences of the carrier density, HFI, and the carrier localization on the MC value are investigated. Especially, it is found that a low-dimensional structure of the organic materials is favorable to get a large MC value.

Spin-dependent current modulation in organic spintronics.

We investigate the spin-dependent current modulation in a model organic semiconductor sandwiched by two ferromagnetic electrodes. When the conductance band of the system is activated by an applied bias voltage, the majority-spin electrons are successively blocked within the organic semiconductor and form nonequilibrium polarons. This majority-spin blockage will modulate the minority-spin current due to the effective spin-spin coupling mediated by the electron-phonon interaction. This study suggests that the spin-blockage induced current modulation is a rather robust phenomenon in organic spintronics.

Ground simulation of the G-excess illusion.

Objective. To observe the subjects' perception of orientation following certain head movements or change of simulator cab attitude in hypergravity (HG), and assess the feasibility of simulating G-excess illusion on the ground by a centrifuge-like Spatial Disorientation (SD) simulator. Method. 1.6 G force field was generated by planetary rotation of the simulator. Perception of orientation of the cab were collected from twelve male pilots' report following their heads pitch movements in pitch plane or cab attitude changes in roll plane under 1.6 G. Result. While making a pitch-up head movement, the pilots experienced a 63.8 degrees +/- 48.3 degrees pitch-up attitude change of the cab in pitch plane, and when the cab was tilted left 20 degrees, pilots experienced a tilt-left perception of 48.6 degrees +/- 39.4 degrees in roll plane. Conclusion. Although there's strong Coriolis effects onboard the SD simulator under 1.6 G, most pilots experienced the G-excess illusion. It demonstrated that it was feasible to use the centrifuge-like device to generate this kind of illusion on the ground.

[Air analysis of the doctor and nurse offices in tall hospital buildings].

O2, PO2, CO2, total number of bacteria were detected in doctor-nurse offices which are at the same side on the 6 and 7th floor in the first affiliated hospital of China Medical University. The results showed that the detected O2 and PO2 in doctor-nurse office were conformed to the normal range of country's indoor standard. The average value of bacteria detection was above the standard Which is less than 500/m3 in ordinary ward given by the Ministry of Health of China. The average CO2 detection was below 0.07%, but sometimes above 0.07% during the 8:30 detection in the morning, total number of bacteria was a little higher too, which suggested that more attention are needed.