Linking two optical frequency combs by heterodyne optical phaselocking between diode lasers at 2.6-THz frequency-difference

Two optical frequency combs (OFC) with total span of 8 THz have been realized and linked by injecting two laser beams into one OFC generator. Two lasers whose frequencies were separated by 2.6 THz were heterodyne phase-locked to link the two combs. The phase-locked loop bandwidth was 1 MHz and the phase error variance was estimated to be 0.08 rad²     

Changes in nutritional composition,enzyme activities and bioactive compounds of germinated buckwheat (Fagopyrum esculantum M.) under unchanged air and humidity conditions

The objective of this study was to investigate changes in nutritional and bioactive compounds in buckwheat seeds during germination under unchanged air and humidity conditions. The germination increased the crude protein, total lipid, reducing sugars, essential amino acids (EAA) and polyunsaturated fatty acids, but decreased the total ash, total carbohydrate and saturated fatty acids. After germinating for 48 h, the total EAA and polyunsaturated fatty acids significantly increased by 5.22% and 3.66%, respectively, as compared to those of ungerminated buckwheat. The total phenolics and flavonoids contents of both free and bound phenolic extracts of germinated buckwheat were also significantly higher than those of ungerminated buckwheat. The rutin content was found to gradually increase during germination, whereas the quercetin content was the highest in the 36 h-germinated buckwheat (0.26 mg g⁻¹ flour). Therefore, germinated buckwheat is considered as a potential material for producing healthy functional foods.     

Deducing structural variations of the apex of probes used in near-field optical microscopy through simultaneous measurement of shear force and evanescent intensity

We propose a simple method employing the simultaneous detection of evanescent intensity and shear force to deduce variations in the near-field optical morphology of the apex of the probes used in near-field microscopy. Fabrication of our probes involves sharpening by chemical etching, metal coating, and removal of metal from the apex. We show that through the simultaneous measurement of shear force and evanescent intensity, it is possible to detect variations in the optical morphology of the very apex of the probes during near-field imaging by a scanning near-field optical microscope.     

Supramolecular Nanostructures of Chiral Perylene Diimides with Amplified Chirality for High‐Performance Chiroptical Sensing

Chiral supramolecular nanostructures with optoelectronic functions are expected to play a central role in many scientific and technological fields but their practical use remains in its infancy. Here, this paper reports photoconductive chiral organic semiconductors (OSCs) based on perylene diimides with the highest electron mobility among the chiral OSCs and investigates the structure and optoelectronic properties of their homochiral and heterochiral supramolecular assemblies from bottom‐up self‐assembly. Owing to the well‐ordered supramolecular packing, the homochiral nanomaterials exhibit superior charge transport with significantly higher photoresponsivity and dissymmetry factor compared with those of their thin film and monomeric equivalents, which enables highly selective detection of circularly polarized light, for the first time, in visible spectral range. Interestingly, the heterochiral nanostructures assembled from co‐self‐assembly of racemic mixtures show extraordinary chiral self‐discrimination phenomenon, where opposite enantiomeric molecules are packed alternately into heterochiral architectures, leading to completely different optoelectrical performances. In addition, the crystal structures of homochiral and heterochiral nanostructures have first been studied by ab initio X‐ray powder diffraction analysis. These findings give insights into the structure–chiroptical property relationships of chiral supramolecular self‐assemblies and demonstrate the feasibility of supramolecular chirality for high‐performance chiroptical sensing.     

Simulation verification for the robustness of passive compass gait with a joint stiffness adjustment

A passive walking robot can achieve a smooth gait without any sensory feedback while walking down a slope. This phenomenon is based on the transformation of potential energy into kinetic energy in the legs. Although the entrainment is observed in a passive gait motion, there is a possibility that the passive gait cannot be achieved in the case of variations in physical parameters, initial conditions, and disturbances. To realize a robust passive gait against variations in physical parameters, this paper proposes a passive gait system that possesses a joint stiffness adjustment. Targeting a compass model, this paper investigates the effectiveness of the proposed method for a passive gait against variations in slope angle and hip joint mass through simulation. As a result, the simulation results show that this method especially has strong robustness against the slope angle variation.     

Coherent Response in a Chaotic Neural Network

We set up a signal-driven scheme of the chaotic neural network with the coupling constants corresponding to certain information, and investigate the stochastic resonance-like effects under its deterministic dynamics, comparing with the conventional case of Hopfield network with stochastic noise. It is shown that the chaotic neural network can enhance weak subthreshold signals and have higher coherence abilities between stimulus and response than those attained by the conventional stochastic model.