Search

Active layers for organic photovoltaic devices (OPVs) were prepared by hand drawing with paint marker pens containing solutions of the materials. Although the pen-coated organic films were visually non-uniform with quite high surface roughness, OPV devices using these films exhibited similar or slightly better performances than those using spin-coated films. As such, the pen-coating technique represents an easily accessible, inexpensive, and highly material-efficient method for fabricating OPVs. [ABSTRACT FROM AUTHOR]

Owing to the emerging trend of non-volatile memory and data-centric computing, the demand for more functional materials and efficient device architecture at the nanoscale is becoming stringent. To date, 2D ferroelectrics are cultivated as channel materials in field-effect transistors for their retentive and switchable dipoles and flexibility to be compacted into diverse structures and integration for intensive production. This study demonstrates the in-plane (IP) ferroelectric memory effect of a 100 nm channel-length 2D ferroelectric semiconductor α-ln2Se3 stamped onto nanogap electrodes on Si/SiO2 under a lateral electric field. As α-ln2Se3 forms the bottom contact of the nanogap electrodes, a large memory window of 13 V at drain voltage between ±6.5 V and the on/off ratio reaching 103 can be explained by controlled IP polarization. Furthermore, the memory effect is modulated by the bottom gate voltage of the Si substrate due to the intercorrelation between IP and out-of-plane (OOP) polarization. The non-volatile memory characteristics including stable retention lasting 17 h, and endurance over 1200 cycles suggest a wide range of memory applications utilizing the lateral bottom contact structure. [ABSTRACT FROM AUTHOR]

The laminar-turbulent transition of a rotating-disk flow dominated by global instability is studied by solving the full Navier-Stokes equations in direct numerical simulations. A flow field in the 2π/32 region is computed using a periodic boundary condition. The flow field is disturbed in two ways. In the first case, a disturbance is introduced at the Reynolds number, Re ≈ 600, while in the second case, a disturbance is introduced at Re ≈ 650. In both cases, wall-normal short-duration suction and blowing are used to disturb the flow field. When a disturbance is added upstream at Re ≈ 600, the wavenumber 64 component becomes dominant when the flow reaches a steady state, whereas when a disturbance is added downstream at Re ≈ 650, the wavenumber 96 component becomes prominent. The transition points are different between the two cases. In addition, in both cases, the distances between neighboring spiral vortices are quite the same when measured at the locations where the turbulence begins. [ABSTRACT FROM AUTHOR]

Recent research on cellular circadian rhythms suggests that the coupling of transcription-translation feedback loops and intracellular redox oscillations is essential for robust circadian timekeeping. For clarification of the molecular mechanism underlying the circadian rhythm, methods that allow for the dynamic and simultaneous detection of transcription/translation and redox oscillations in living cells are needed. Herein, we report that the cyanobacterial circadian redox rhythm can be electrochemically detected based on extracellular electron transfer (EET), a process in which intracellular electrons are exchanged with an extracellular electrode. As the EETbased method is non-destructive, concurrent detection with transcription/translation rhythm using bioluminescent reporter strains becomes possible. An EET pathway that electrochemically connected the intracellular region of cyanobacterial cells with an extracellular electrode was constructed via a newly synthesized electron mediator with cell membrane permeability. In the presence of the mediator, the open circuit potential of the culture medium exhibited temperature-compensated rhythm with approximately 24 h periodicity. Importantly, such circadian rhythm of the open circuit potential was not observed in the absence of the electron mediator, indicating that the EET process conveys the dynamic information regarding the intracellular redox state to the extracellular electrode. These findings represent the first direct demonstration of the intracellular circadian redox rhythm of cyanobacterial cells. [ABSTRACT FROM AUTHOR]

The flapping motion of a permeable square-shaped flag is studied using an incompressible smoothed particle hydrodynamics method together with a newly proposed permeable flag model. Wind tunnel experiments are also performed, and the results are compared. The present model is successful in simulating two characteristic states depending on the uniform velocity, namely the ‘stretched-straight state’ and the ‘flapping state.’ Both the oscillation periods and the tail-end trajectories quantitatively agree with the experiments. However, the bistable region, which appears in the experiments, is not seen in the computational results. Except for the high-permeability case, the flags oscillate two dimensionally and no flow separation is observed irrespective of the permeability conditions. This might be due the flexibility of the flag in which the flag can change its shape in response to the low fluid pressure acting on the surface. A pair of longitudinal vortices rotating in opposite directions is generated at both spanwise ends of the flapping flag. Their strengths vary in accordance with the instantaneous lift force. When the flag is impermeable, these longitudinal vortices are connected to the spanwise vortex shed from the trailing edge and deform into a V-shaped vortex downstream. Conversely, the longitudinal vortices generated from a permeable flag simply move downstream without reconnecting. In addition, it is found that fluid permeation takes place at the location where the work by the fluid on the flag is concentrated. [ABSTRACT FROM AUTHOR]